2024/03/07 更新

写真a

キタハラ ケイ
北原 圭
KITAHARA Kei
所属
医歯薬学域 准教授(特任)
職名
准教授(特任)
外部リンク

学位

  • 博士(工学) ( 東京大学 )

研究分野

  • ライフサイエンス / 分子生物学

  • ライフサイエンス / ゲノム生物学  / メタゲノム

  • ライフサイエンス / 応用微生物学

  • 自然科学一般 / 地球生命科学

学歴

  • 東京大学   Graduate school of engineering   Department of chemistry and biotechnology

    2004年4月 - 2007年3月

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  • 東京大学   Graduate school of frontier sciences   Department of integrated biosciences

    2002年4月 - 2004年3月

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  • 京都大学   Faculty of agriculture   Department of bioproduction sciences and technology

    1998年4月 - 2002年3月

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経歴

  • 岡山大学インド感染症共同研究センター   特任准教授

    2020年10月 - 現在

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  • 北海道大学   大学院理学研究院化学部門   特任助教・研究員

    2014年10月 - 2020年9月

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  • 大阪大学   情報科学研究科   特別科学研究員

    2013年4月 - 2014年9月

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  • 独立行政法人科学技術振興機構   研究員

    2011年6月 - 2014年9月

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  • 独立行政法人産業技術総合研究所生物プロセス研究部門   特別研究員

    2010年4月 - 2011年5月

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  • 東京大学   特任研究員

    2007年4月 - 2010年3月

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▼全件表示

所属学協会

  • American Society for Microbiology

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  • 日本ゲノム微生物学会

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論文

  • Vibriosis in South Asia: a systematic review and meta-analysis. 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Ayumu Ohno, Januka Khatiwada, Shanta Dutta, Shin-Ichi Miyoshi

    International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases   2024年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: South Asia remains home to foodborne diseases caused by Vibrio species. We aimed to compile and update information on the epidemiology of vibriosis in South Asia. METHODS: For this systematic review and meta-analysis, we searched PubMed, Web of Science, EMBASE, and Google Scholar for studies related to vibriosis in South Asia published up to May 2023. A random-effects meta-analysis was used to estimate the pooled isolation rate of non-cholera-causing Vibrio species. RESULTS: In total 38 studies were included. Seven of these were case reports and 22 were included in the meta-analysis. Reported vibriosis cases were caused by non-O1/non-O139 V. cholerae, V. parahaemolyticus, V. fluvialis, and V. vulnificus. The overall pooled isolation rate was 4.0% (95% CI: 3.0-5.0%) in patients with diarrhea. Heterogeneity was high (I2= 98.0%). The isolation rate of non-O1/non-O139 V. cholerae, V. parahaemolyticus, V. fluvialis were 9.0 (95% CI: 7.0-10.0%), 1.0 (95% CI: 1.0-2.0%), and 2.0 (95% CI: 1.0-3.0%), respectively. Regarding V. parahaemolyticus, O3:K6 was the most frequently isolated serotype. Cases peaked during summer. Several studies reported antibiotic-resistant strains and those harboring extended-spectrum beta-lactamases genes. CONCLUSIONS: This study demonstrates a high burden of infections caused by non-cholera-causing Vibrio species in South Asia.

    DOI: 10.1016/j.ijid.2024.01.022

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  • Comprehensive full genome analysis of norovirus strains from eastern India, 2017–2021

    Mahadeb Lo, Yen Hai Doan, Suvrotoa Mitra, Ritubrita Saha, Shin-ichi Miyoshi, Kei Kitahara, Shanta Dutta, Tomoichiro Oka, Mamta Chawla-Sarkar

    Gut Pathogens   16 ( 1 )   2024年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

    Abstract

    Background

    Worldwide, noroviruses are the leading cause of acute gastroenteritis (AGE) in people of all age groups. In India, norovirus rates between 1.4 to 44.4% have been reported. Only a very few complete norovirus genome sequences from India have been reported.

    Objective

    To perform full genome sequencing of noroviruses circulating in India during 2017–2021, identify circulating genotypes, assess evolution including detection of recombination events.

    Methodology

    Forty-five archived norovirus-positive samples collected between October 2017 to July 2021 from patients with AGE from two hospitals in Kolkata, India were processed for full genome sequencing. Phylogenetic analysis, recombination breakpoint analysis and comprehensive mutation analysis were also performed.

    Results

    Full genome analysis of norovirus sequences revealed that strains belonging to genogroup (G)I were genotyped as GI.3[P13]. Among the different norovirus capsid-polymerase combinations, GII.3[P16], GII.4 Sydney[P16], GII.4 Sydney[P31], GII.13[P16], GII.16[P16] and GII.17 were identified. Phylogenetic analysis confirmed phylogenetic relatedness with previously reported norovirus strains and all viruses were analyzed by Simplot. GII[P16] viruses with multiple residue mutations within the non-structural region were detected among circulating GII.4 and GII.3 strains. Comprehensive mutation analysis and selection pressure analysis of GII[P16] viruses showed positive as well as negative selection sites. A GII.17 strain (NICED-BCH-11889) had an untypeable polymerase type, closely related to GII[P38].

    Conclusion

    This study highlights the circulation of diverse norovirus strains in eastern India. These findings are important for understanding norovirus epidemiology in India and may have implications for future vaccine development.

    DOI: 10.1186/s13099-023-00594-5

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    その他リンク: https://link.springer.com/article/10.1186/s13099-023-00594-5/fulltext.html

  • Foodborne Outbreak by Salmonella enterica Serovar Weltevreden in West Bengal, India

    Goutam Chowdhury, Falguni Debnath, Mainak Bardhan, Alok Kumar Deb, Rama Bhuina, Sudipta Bhattacharjee, Koushik Mondal, Kei Kitahara, Shin-ichi Miyoshi, Shanta Dutta, Asish K. Mukhopadhyay

    Foodborne Pathogens and Disease   2024年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Mary Ann Liebert Inc  

    DOI: 10.1089/fpd.2023.0064

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    その他リンク: https://www.liebertpub.com/doi/pdf/10.1089/fpd.2023.0064

  • The basic reproduction number (R0) of ebola virus disease: A systematic review and meta-analysis. 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Debmalya Mitra, Ngangu Patrick Ntontolo, Nlandu Roger Ngatu, Ayumu Ohno, Januka Khatiwada, Shanta Dutta, Shin-Ichi Miyoshi

    Travel medicine and infectious disease   57   102685 - 102685   2024年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: Ebola virus disease (Ebola) is highly pathogenic, transmissible, and often deadly, with debilitating consequences. Superspreading within a cluster is also possible. In this study, we aim to document Ebola basic reproduction number (R0): the average number of new cases associated with an Ebola case in a completely susceptible population. METHODS: We undertook a systematic review and meta-analysis. We searched PubMed, EMBASE, and Web of Science for studies published between 1976 and February 27, 2023. We also manually searched the reference lists of the reviewed studies to identify additional studies. We included studies that reported R0 during Ebola outbreaks in Africa. We excluded studies that reported only the effective reproduction number (Rt). Abstracting data from included studies was performed using a pilot-tested standard form. Two investigators reviewed the studies, extracted the data, and assessed quality. The pooled R0 was determined by a random-effects meta-analysis. R0 was stratified by country. We also estimated the theoretically required immunization coverage to reach herd-immunity using the formula of (1-1/R0) × 100 %. RESULTS: The search yielded 2042 studies. We included 53 studies from six African countries in the systematic review providing 97 Ebola mean R0 estimates. 27 (with 46 data points) studies were included in the meta-analysis. The overall pooled mean Ebola R0 was 1.95 (95 % CI 1.74-2.15), with high heterogeneity (I2 = 99.99 %; τ2 = 0.38; and p < 0.001) and evidence of small-study effects (Egger's statistics: Z = 4.67; p < 0.001). Mean Ebola R0 values ranged from 1.2 to 10.0 in Nigeria, 1.1 to 7 in Guinea, 1.14 to 8.33 in Sierra Leone, 1.13 to 5 in Liberia, 1.2 to 5.2 in DR Congo, 1.34 to 2.7 in Uganda, and from 1.40 to 2.55 for all West African countries combined. Pooled mean Ebola R0 was 9.38 (95 % CI 4.16-14.59) in Nigeria, 3.31 (95 % CI 2.30-4.32) in DR Congo, 2.0 (95 % CI 1.25-2.76) in Uganda, 1.83 (95 % CI 1.61-2.05) in Liberia, 1.73 (95 % CI 1.47-2.0) in Sierra Leonne, and 1.44 (95 % CI 1.29-1.60) in Guinea. In theory, 50 % of the population needs to be vaccinated to achieve herd immunity, assuming that Ebola vaccine would be 100 % effective. CONCLUSIONS: Ebola R0 varies widely across countries. Ebola has a much wider R0 range than is often claimed (1.3-2.0). It is possible for an Ebola index case to infect more than two susceptible individuals.

    DOI: 10.1016/j.tmaid.2023.102685

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  • Complete genomic sequence of Vibrio fluvialis strain IDH5335 isolated from a patient with diarrhea in Kolkata, India

    Goutam Chowdhury, Kei Kitahara, Makoto Taniguchi, Kazuma Uesaka, Basilua Andre Muzembo, Debmalya Mitra, Ayumu Ohno, Thandavarayan Ramamurthy, Shanta Dutta, Shin-ichi Miyoshi, Asish Kumar Mukhopadhyay

    Microbiology Resource Announcements   2023年11月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Society for Microbiology  

    ABSTRACT

    We isolated a Vibrio fluvialis strain (IDH5335) from a stool sample collected from a patient with diarrhea. In this announcement, we report the complete genomic sequence of this organism, which was obtained by combining Illumina and Oxford Nanopore sequencing data.

    DOI: 10.1128/mra.00707-23

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  • Flavobacterium okayamense sp. nov. isolated from surface seawater. 国際誌

    Kei Kitahara, Basilua Andre Muzembo, Sho Morohoshi, Tadao Kunihiro, Nozomi Tazato, Ayumu Ohno, Kazuma Uesaka, Makoto Taniguchi, Shin-Ichi Miyoshi

    Archives of microbiology   205 ( 10 )   346 - 346   2023年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Strain KK2020170T, a Gram-stain negative, yellow colony-forming bacterium, was isolated from surface seawater sampled in Kojima Bay, Okayama, Japan. Phylogenetic analysis based on the 16S rRNA gene revealed that strain KK2020170T belongs to the genus Flavobacterium, with Flavobacterium haoranii LQY-7T (98.1% similarity) being its closest relative, followed by Flavobacterium sediminis MEBiC07310T (96.9%) and Flavobacterium urocaniciphilum YIT 12746T (96.0%). Whole-genome shotgun sequencing showed that strain KK2020170T, when paralleled with F. haoranii LQY-7 T, had 81.3% average nucleotide identity, and 24.6% in silico DNA-DNA hybridization values, respectively. The DNA G + C content of strain KK2020170T was 31.1 mol%. The most abundant fatty acids (> 10%) of strain KK2020170T were iso-C15: 0, iso-C17: 0 3-OH and iso-C15: 1 G. The dominant respiratory quinone of the strain was menaquinone MK-6. Based on the phylogenetic and phenotypic analysis results, we propose that strain KK2020170T represents a novel species, for which the name Flavobacterium okayamense sp. nov. has been proposed. The type strain is KK2020170T (= ATCC TSD-280 T = NBRC 115344 T).

    DOI: 10.1007/s00203-023-03682-x

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  • Pentavalent outer membrane vesicles immunized mice sera confers passive protection against five prevalent pathotypes of diarrhoeagenic Escherichia coli in neonatal mice

    Soumalya Banerjee, Prolay Halder, Sanjib Das, Suhrid Maiti, Ushasi Bhaumik, Moumita Dutta, Goutam Chowdhury, Kei Kitahara, Shin-Ichi Miyoshi, Asish Kumar Mukhopadhyay, Shanta Dutta, Hemanta Koley

    Immunology Letters   2023年9月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.imlet.2023.09.009

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  • Shigellosis in Southeast Asia: A systematic review and meta-analysis. 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Debmalya Mitra, Ayumu Ohno, Januka Khatiwada, Shanta Dutta, Shin-Ichi Miyoshi

    Travel medicine and infectious disease   52   102554 - 102554   2023年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: Southeast Asia is attractive for tourism. Unfortunately, travelers to this region are at risk of becoming infected with Shigella. We conducted a meta-analysis to provide updates on Shigella prevalence in Southeast Asia, along with their serogroups and serotypes. METHODS: We conducted a systematic search using PubMed, EMBASE, and Web of Science for peer-reviewed studies from 2000 and November 2022. We selected studies that detected Shigella in stools by culture or polymerase chain reaction (PCR). Two reviewers extracted the data using a standardized form and performed quality assessments using the Joanna Briggs Institute checklist. The random effects model was used to estimate the pooled prevalence of Shigella. RESULTS: During our search, we identified 4376 studies. 29 studies (from six Southeast Asian countries) were included in the systematic review, 21 each in the meta-analysis of the prevalence of Shigella (Sample size:109545) and the prevalence of Shigella serogroups. The pooled prevalence of Shigella was 4% (95% CI: 4-5%) among diarrhea cases. Shigella sonnei was the most abundant serogroup in Thailand (74%) and Vietnam (57%), whereas Shigella flexneri was dominant in Indonesia (72%) and Cambodia (71%). Shigella dysenteriae and Shigella boydii were uncommon (pooled prevalence of 1% each). The pooled prevalence of Shigella was 5% (95% CI: 4-6%) in children aged <5 years. The pooled prevalence showed a decreasing trend comparing data collected between 2000 and 2013 (5%; 95% CI: 4-6%) and between 2014 and 2022 (3%; 95% CI: 2-4%). Shigella prevalence was 6% in studies that included participants with mixed pathogens versus 3% in those without. Shigella flexneri serotype 2a was the most frequently isolated (33%), followed by 3a (21%), 1b (10%), 2b (3%), and 6 (3%). CONCLUSIONS: This study provides compelling evidence for the development of effective Shigella vaccines for residents of endemic regions and travellers to these areas.

    DOI: 10.1016/j.tmaid.2023.102554

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  • Environmental water in Kolkata is suitable for the survival of Vibrio cholerae O1 査読

    Eizo Takahashi, Kei Kitahara, Shin-ichi Miyoshi, Goutam Chowdhury, Asish K. Mukhopadhyay, Shanta Dutta, Sadayuki Ochi, Keinosuke Okamoto

    Environmental Research   222   115374 - 115374   2023年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.envres.2023.115374

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  • Burden of Shigella in South Asia: a systematic review and meta-analysis. 査読 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Debmalya Mitra, Ayumu Ohno, Januka Khatiwada, Shanta Dutta, Shin-Ichi Miyoshi

    Journal of travel medicine   30 ( 1 )   2022年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: Shigella remains one of the most common causes of diarrhoea in South Asia. Current estimates of the prevalence of Shigella are critical for guiding control measures. We estimated the prevalence of Shigella species and serogroups in South Asia. METHODS: We performed a systematic review using PubMed, EMBASE, Google Scholar, and Web of Science for peer-reviewed studies published between 2000 and June 19, 2022. We also manually searched the reference lists of the reviewed studies to identify additional studies. We included studies that detected the presence of Shigella in stool by culture or polymerase chain reaction (PCR). Studies associated with outbreaks were excluded. Two investigators independently reviewed the studies, extracted the data, and performed quality assessment. A random-effects meta-analysis was performed to determine the pooled prevalence of Shigella. RESULTS: Our search yielded 5707 studies, of which 91 studies from five South Asian countries were included in the systematic review, 79 in the meta-analysis of Shigella prevalence and 63 in the meta-analysis of Shigella serogroups prevalence. The pooled prevalence of Shigella was 7% (95% CI: 6-7%), with heterogeneity (I2 = 98.7; p < 0.01). The prevalence of Shigella was higher in children aged < 5 years (10%; 95% CI: 8-11%), in rural areas (12%; 95% CI: 10-14%), and in studies using PCR (15%; 95% CI: 11-19%). Shigella flexneri (58%) was the most abundant serogroup, followed by Shigella sonnei (19%), Shigella boydii (10%), and Shigella dysenteriae (9%). S. flexneri 2a was the most frequently isolated serotype (36%), followed by serotype 3a (12%), serotype 6 (12%), and serotype 1b (6%). The prevalence of non-typeable Shigella was 10.0%. CONCLUSIONS: Although the prevalence of Shigella in South Asia remains generally high, it varies by age group and geographical area, with data lacking in some countries. Effective Shigella vaccines would be advantageous for both endemic communities and travellers.

    DOI: 10.1093/jtm/taac132

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  • Colonization with extended-spectrum beta-lactamase-producing Escherichia coli and traveler's diarrhea attack rates among travelers to India: a systematic review and meta-analysis. 査読 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Ayumu Ohno, Keinosuke Okamoto, Shin-Ichi Miyoshi

    Tropical diseases, travel medicine and vaccines   8 ( 1 )   22 - 22   2022年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: India is an attractive destination for travelers. Unfortunately, numerous reports exist on traveler's diarrhea (TD) and fecal colonization with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) among international travelers visiting India. Here, we systematically reviewed studies published on the acquisition of ESBL-EC and TD attack rates among international visitors to India. METHODS: Design: Systematic review and meta-analysis. A systematic search was performed using Google Scholar, PubMed, EMBASE, Web of Science, and gray literature from 2000 to December 2021, for studies containing data for ESBL-EC acquisition or TD experience related to a trip to India. Random effects models were used to compute the prevalence of ESBL-EC acquisition and TD attack. RESULTS: The literature search yielded a total of 5023 records. Of these, 31 met our inclusion criteria for systematic review and only 17 could be meta-analyzed (9 for TD, and 8 for ESBL-EC). The overall pooled attack rate of TD was 39% (95% confidence interval, CI: 25-53%). In studies where travelers' memory was used to diagnose TD, the pooled attack rate of TD was slightly higher (42%, 95% CI: 21-64%) compared to those where TD was objectively documented (33%, 95% CI: 17-49%). There were significant risks to be colonized with ESBL-EC among the travelers who experienced TD. The pooled rate of ESBL-EC colonization was 72% (CI: 67-78%). Most ESBL-EC produced CTX-M-15 enzyme. Furthermore, most of the travelers who acquired ESBL-EC were from highly industrialized countries recruited from travel clinics: Canada (n = 80), Germany (n = 69), Netherlands (n = 20), Sweden (n = 18), Japan (n = 10), Finland (n = 8), USA (n = 7), Spain (n = 5), and Denmark (n = 3). CONCLUSIONS: TD pooled attack rate and ESBL-EC acquisition among international travelers visiting India were high in this study. However, we cannot make generalizations based upon this TD pooled attack rate for the current situation, due to a lack of current data. Our study highlights that travelers should be advised on TD to ensure that they do not disregard the risk of contracting TD and be better prepared as a result. It also illustrates the importance of international travel in acquiring antibiotic-resistant Escherichia coli.

    DOI: 10.1186/s40794-022-00179-1

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  • Rapid diagnostic tests versus RT-PCR for Ebola virus infections: a systematic review and meta-analysis. 査読 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Ayumu Ohno, Ngangu Patrick Ntontolo, Nlandu Roger Ngatu, Keinosuke Okamoto, Shin-Ichi Miyoshi

    Bulletin of the World Health Organization   100 ( 7 )   447 - 458   2022年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    OBJECTIVE: To evaluate the clinical accuracy of rapid diagnostic tests for the detection of Ebola virus. METHODS: We searched MEDLINE®, Embase® and Web of Science for articles published between 1976 and October 2021 reporting on clinical studies assessing the performance of Ebola virus rapid diagnostic tests compared with reverse transcription polymerase chain reaction (RT-PCR). We assessed study quality using the QUADAS-2 criteria. To estimate the pooled sensitivity and specificity of these rapid diagnostic tests, we used a bivariate random-effects meta-analysis. FINDINGS: Our search identified 113 unique studies, of which nine met the inclusion criteria. The studies were conducted in the Democratic Republic of the Congo, Guinea, Liberia and Sierra Leone and they evaluated 12 rapid diagnostic tests. We included eight studies in the meta-analysis. The pooled sensitivity and specificity of the rapid tests were 86% (95% confidence interval, CI: 80-91) and 95% (95% CI: 91-97), respectively. However, pooled sensitivity decreased to 83% (95% CI: 77-88) after removing outliers. Pooled sensitivity increased to 90% (95% CI: 82-94) when analysis was restricted to studies using the RT-PCR from altona Diagnostics as gold standard. Pooled sensitivity increased to 99% (95% CI: 67-100) when the analysis was restricted to studies using whole or capillary blood specimens. CONCLUSION: The included rapid diagnostic tests did not detect all the Ebola virus disease cases. While the sensitivity and specificity of these tests are moderate, they are still valuable tools, especially useful for triage and detecting Ebola virus in remote areas.

    DOI: 10.2471/BLT.21.287496

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  • Long-Term Kinetics of Serological Antibodies against Vibrio cholerae Following a Clinical Cholera Case: A Systematic Review and Meta-Analysis. 査読 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Debmalya Mitra, Ayumu Ohno, Shin-Ichi Miyoshi

    International journal of environmental research and public health   19 ( 12 )   2022年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: Approximately 2.9 million people worldwide suffer from cholera each year, many of whom are destitute. However, understanding of immunity against cholera is still limited. Several studies have reported the duration of antibodies following cholera; however, systematic reviews including a quantitative synthesis are lacking. OBJECTIVE: To meta-analyze cohort studies that have evaluated vibriocidal, cholera toxin B subunit (CTB), and lipopolysaccharide (LPS) antibody levels following a clinical cholera case. METHODS: Design: Systematic review and meta-analysis. We searched PubMed and Web of science for studies assessing antibodies against Vibrio cholerae in cohorts of patients with clinical cholera. Two authors independently extracted data and assessed the quality of included studies. Random effects models were used to pool antibody titers in adults and older children (aged ≥ 6 years). In sensitivity analysis, studies reporting data on young children (2-5 years) were included. RESULTS: Nine studies met our inclusion criteria for systematic review and seven for meta-analysis. The pooled mean of vibriocidal antibody titers in adults and older children (aged ≥ 6 years) was 123 on day 2 post-symptom onset, which sharply increased on day 7 (pooled mean = 6956) and gradually waned to 2247 on day 30, 578 on day 90, and 177 on day 360. Anti-CTB IgA antibodies also peaked on day 7 (pooled mean = 49), followed by a rapid decrease on day 30 (pooled mean = 21), and further declined on day 90 (pooled mean = 10), after which it plateaued from day 180 (pooled mean = 8) to 360 (pooled mean = 6). Similarly, anti-CTB IgG antibodies peaked in early convalescence between days 7 (pooled mean = 65) and 30 (pooled mean = 69), then gradually waned on days 90 (pooled mean = 42) and 180 (pooled mean = 30) and returned to baseline on day 360 (pooled mean = 24). Anti-LPS IgA antibodies peaked on day 7 (pooled mean = 124), gradually declined on day 30 (pooled mean = 44), which persisted until day 360 (pooled mean = 10). Anti LPS IgG antibodies peaked on day 7 (pooled mean = 94). Thereafter, they decreased on day 30 (pooled mean = 85), and dropped further on days 90 (pooled mean = 51) and 180 (pooled mean = 47), and returned to baseline on day 360 (pooled mean = 32). Sensitivity analysis including data from young children (aged 2-5 years) showed very similar findings as in the primary analysis. CONCLUSIONS: This study confirms that serological antibody (vibriocidal, CTB, and LPS) titers return to baseline levels within 1 year following clinical cholera, i.e., before the protective immunity against subsequent cholera wanes. However, this decay should not be interpreted as waning immunity because immunity conferred by cholera against subsequent disease lasts 3-10 years. Our study provides evidence for surveillance strategies and future research on vaccines and also demonstrates the need for further studies to improve our understanding of immunity against cholera.

    DOI: 10.3390/ijerph19127141

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  • Cholera Outbreaks in India, 2011-2020: A Systematic Review. 査読 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Anusuya Debnath, Ayumu Ohno, Keinosuke Okamoto, Shin-Ichi Miyoshi

    International journal of environmental research and public health   19 ( 9 )   2022年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Fecal contamination of water sources and open defecation have been linked to cholera outbreaks in India. However, a systematic review on the drivers responsible for these outbreaks has yet to be published. Here, we systematically review the published literature on cholera outbreaks in India between 2011 and 2020. We searched studies in English in three databases (MEDLINE, EMBASE, and Web of Science) and the Integrated Disease Surveillance Program that tracks cholera outbreaks throughout India. Two authors independently extracted data and assessed the quality of the included studies. Quantitative data on the modes of transmission reviewed in this study were assessed for any change over time between 2011-2015 and 2016-2020. Our search retrieved 10823 records initially, out of which 81 full-text studies were assessed for eligibility. Among these 81 studies, 20 were eligible for inclusion in this review. There were 565 reported outbreaks between 2011 and 2020 that led to 45,759 cases and 263 deaths. Outbreaks occurred throughout the year; however, they exploded with monsoons (June through September). In Tamil Nadu, a typical peak of cholera outbreaks was observed from December to January. Seventy-two percent (33,089/45,759) of outbreak-related cases were reported in five states, namely Maharashtra, West Bengal, Punjab, Karnataka, and Madhya Pradesh. Analysis of these outbreaks highlighted the main drivers of cholera including contaminated drinking water and food, inadequate sanitation and hygiene (including open defecation), and direct contact between households. The comparison between 2011-2015 and 2016-2020 showed a decreasing trend in the outbreaks that arose due to damaged water pipelines. Many Indians still struggle with open defecation, sanitation, and clean water access. These issues should be addressed critically. In addition, it is essential to interrupt cholera short-cycle transmission (mediated by households, stored drinking water and foodstuffs) during an outbreak. As cholera is associated with deprivation, socio-economic development is the only long-term solution.

    DOI: 10.3390/ijerph19095738

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  • Misconceptions and Rumors about Ebola Virus Disease in Sub-Saharan Africa: A Systematic Review. 査読 国際誌

    Basilua Andre Muzembo, Ngangu Patrick Ntontolo, Nlandu Roger Ngatu, Januka Khatiwada, Tomoko Suzuki, Koji Wada, Kei Kitahara, Shunya Ikeda, Shin-Ichi Miyoshi

    International journal of environmental research and public health   19 ( 8 )   2022年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We sought to summarize knowledge, misconceptions, beliefs, and practices about Ebola that might impede the control of Ebola outbreaks in Africa. We searched Medline, EMBASE, CINAHL, and Google Scholar (through May 2019) for publications reporting on knowledge, attitudes, and practices (KAP) related to Ebola in Africa. In total, 14 of 433 articles were included. Knowledge was evaluated in all 14 articles, and they all highlighted that there are misconceptions and risk behaviors during an Ebola outbreak. Some communities believed that Ebola spreads through the air, mosquito bites, malice from foreign doctors, witchcraft, and houseflies. Because patients believe that Ebola was caused by witchcraft, they sought help from traditional healers. Some people believed that Ebola could be prevented by bathing with salt or hot water. Burial practices where people touch Ebola-infected corpses were common, especially among Muslims. Discriminatory attitudes towards Ebola survivors or their families were also prevalent. Some Ebola survivors were not accepted back in their communities; the possibility of being ostracized from their neighborhoods was high and Ebola survivors had to lead a difficult social life. Most communities affected by Ebola need more comprehensive knowledge on Ebola. Efforts are needed to address misconceptions and risk behaviors surrounding Ebola for future outbreak preparedness in Africa.

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  • Accuracy of cholera rapid diagnostic tests: a systematic review and meta-analysis. 査読 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Anusuya Debnath, Keinosuke Okamoto, Shin-Ichi Miyoshi

    Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases   28 ( 2 )   155 - 162   2022年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    BACKGROUND: Cholera is an acute diarrheal disease caused by Vibrio cholerae O1 or O139. Cholera rapid diagnostic tests (RDTs) are widely used to screen for cholera cases. However, their accuracy has not been systematically reviewed. OBJECTIVES: To evaluate the diagnostic accuracy of cholera RDTs. METHODS: Systematic review and meta-analysis. DATA SOURCES: Medline, EMBASE and Web of science through to November 2020; references of included studies and a technical guidance on cholera RDTs. This review is registered with PROSPERO (CRD42021233124). STUDY ELIGIBILITY CRITERIA: Cross-sectional studies comparing the performance of cholera RDTs either to stool culture or PCR. PARTICIPANTS: Individuals with clinically suspected cholera. DATA EXTRACTION: Two authors independently extracted data and assessed the quality using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) criteria. RESULTS: Eighteen studies were included in the systematic review of which 17 were used for meta-analysis. Crystal VC was the most frequently used RDT (13 studies), followed by Cholkit and Institut Pasteur cholera dipstick (three studies each), SD Bioline (two studies), Artron (one study) and Smart (one study). Using direct testing (n = 12 627 specimens), the bivariate random-effects model yielded a pooled sensitivity and specificity of 91% (95% CI 87%-94%) and 80% (95% CI 74%-84%), respectively. However, through alkaline peptone water (APW) enrichment (n = 3403 specimens), the pooled sensitivity and specificity were 89% (95% CI 79%-95%) and 98% (95% CI 95%-99%), respectively. CONCLUSION: Cholera RDTs, especially when enriched with APW, have moderate sensitivity and specificity. Although less useful for clinical management, the current generation of RDTs have clear utility for surveillance efforts if used in a principled manner. Enrichment of stool specimens in APW before using cholera RDTs reduces the possibility of obtaining false-positive results, despite the few cholera cases that go undetected. It is noteworthy that APW-enriched cholera RDTs are not necessarily rapid tests, and are not listed in the Global Task Force on Cholera Control/WHO target product profile.

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  • Quercetin, a flavonoid, combats rotavirus infection by deactivating rotavirus-induced pro-survival NF-κB pathway. 査読 国際誌

    Shreya Banerjee, Rakesh Sarkar, Arpita Mukherjee, Shin-Ichi Miyoshi, Kei Kitahara, Prolay Halder, Hemanta Koley, Mamta Chawla-Sarkar

    Frontiers in microbiology   13   951716 - 951716   2022年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Rotavirus (RV) is the leading cause of acute gastroenteritis and watery diarrhea in children under 5 years accounting for high morbidity and mortality in countries with poor socioeconomic status. Although vaccination against RV has been implemented in more than 100 countries, the efficacy of vaccine has been challenged in low-income settings. The lack of any FDA-approved drug against RV is an additional concern regarding the treatment associated with rotavirus-induced infantile death. With the purpose for the discovery of anti-RV therapeutics, we assessed anti-rotaviral potential of quercetin, a well-characterized antioxidant flavonoid. In vitro study revealed that quercetin treatment resulted in diminished production of RV-SA11 (simian strain) viral particles in a concentration-dependent manner as estimated by the plaque assay. Consistent with this result, Western blot analysis also revealed reduced synthesis of viral protein in quercetin-treated RV-SA11-infected MA104 cells compared to vehicle (DMSO) treated controls. Not surprisingly, infection of other RV strains A5-13 (bovine strain) and Wa (Human strain) was also found to be abridged in the presence of quercetin compared to DMSO. The IC50 of quercetin against three RV strains ranges between 2.79 and 4.36 Mm, and S.I. index is greater than 45. Concurrent to the in vitro results, in vivo study in mice model also demonstrated reduced expression of viral proteins and viral titer in the small intestine of quercetin-treated infected mice compared to vehicle-treated infected mice. Furthermore, the result suggested anti-rotaviral activity of quercetin to be interferon-independent. Mechanistic study revealed that the antiviral action of quercetin is co-related with the inhibition of RV-induced early activation of NF-κB pathway. Overall, this study delineates the strong anti-RV potential of quercetin and also proposes it as future therapeutics against rotaviral diarrhea.

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  • Cholera Rapid Diagnostic Tests for the Detection of Vibrio cholerae O1: An Updated Meta-Analysis. 査読 国際誌

    Basilua Andre Muzembo, Kei Kitahara, Ayumu Ohno, Anusuya Debnath, Keinosuke Okamoto, Shin-Ichi Miyoshi

    Diagnostics (Basel, Switzerland)   11 ( 11 )   2021年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    UNLABELLED: The rapid diagnosis of cholera contributes to adequate outbreak management. This meta-analysis assesses the diagnostic accuracy of cholera rapid tests (RDTs) to detect Vibrio cholerae O1. METHODS: Systematic review and meta-analysis. We searched four databases (Medline, EMBASE, Google Scholar, and Web of Science up to 8 September 2021) for studies that evaluated cholera RDTs for the detection of V. cholerae O1 compared with either stool culture or polymerase chain reaction (PCR). We assessed the studies' quality using the QUADAS-2 criteria. In addition, in this update, GRADE approach was used to rate the overall certainty of the evidence. We performed a bivariate random-effects meta-analysis to calculate the pooled sensitivity and specificity of cholera RDTs. RESULTS: Overall, 20 studies were included in this meta-analysis. Studies were from Africa (n = 11), Asia (n = 7), and America (Haiti; n = 2). They evaluated eight RDTs (Crystal VC-O1, Crystal VC, Cholkit, Institut Pasteur cholera dipstick, SD Bioline, Artron, Cholera Smart O1, and Smart II Cholera O1). Using direct specimen testing, sensitivity and specificity of RDTs were 90% (95% CI, 86 to 93) and 86% (95% CI, 81 to 90), respectively. Cholera Sensitivity was higher in studies conducted in Africa [92% (95% CI, 89 to 94)] compared with Asia [82% (95% CI, 77 to 87)]. However, specificity [83% (95% CI, 71 to 91)] was lower in Africa compared with Asia [90% (95% CI, 84 to 94)]. GRADE quality of evidence was estimated as moderate. CONCLUSIONS: Against culture or PCR, current cholera RDTs have moderate sensitivity and specificity for detecting Vibrio cholerae O1.

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  • Complete Genome Sequence of Vibrio rotiferianus Strain AM7 査読 国際誌

    Kentaro Miyazaki, Apirak Wiseschart, Kusol Pootanakit, Kei Kitahara

    Microbiology Resource Announcements   9 ( 21 )   2020年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Society for Microbiology  

    We isolated the novel strain Vibrio rotiferianus AM7 from the shell of an abalone. In this article, we report the complete genome sequence of this organism, which was obtained by combining Oxford Nanopore long-read and Illumina short-read sequencing data.

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  • Isolation, identification and antibiogram profiling of bacteria isolated from water, seafood, and macroplastic samples from Baseco Beach, Manila Bay 査読

    Balolong MP, Pagoso EJA, Tesoro, ANE, Carrillo, MCO, Kitahara, K

    Philippine Journal of Health Research and Development   24 ( 3 )   2020年

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    記述言語:英語  

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  • Complete Genome Sequence of Staphylococcus arlettae Strain P2, Isolated from a Laboratory Environment. 査読 国際誌

    Yu H, Taniguchi M, Uesaka K, Wiseschart A, Pootanakit K, Nishitani Y, Murakami Y, Ishimori K, Miyazaki K, Kitahara K

    Microbiology resource announcements   8 ( 45 )   2019年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1128/MRA.00696-19

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  • Functional metagenomic approach to identify overlooked antibiotic resistance mutations in bacterial rRNA 査読 国際誌

    Miyazaki, K, Kitahara, K

    Scientific Reports 8: 5179 | DOI:10.1038/s41598-018-23474-4.   8 ( 1 )   5179 - 5179   2018年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1038/s41598-018-23474-4

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  • Constructing mutant ribosomes containing mutant ribosomal RNAs 招待 査読

    Kitahara, K., Miyazaki, K.

    Applied RNA Bioscience   2018年

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Applied RNA Bioscience  

    DOI: 10.1007/978-981-10-8372-3_2

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  • Comparative RNA function analysis reveals high functional similarity between distantly related bacterial 16 S rRNAs 査読 国際誌

    Tsukuda, M, Kitahara, K, Miyazaki, K

    Scientific Reports 7: 9993 | DOI:10.1038/s41598-017-10214-3.   7 ( 1 )   9993 - 9993   2017年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1038/s41598-017-10214-3

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    その他リンク: http://www.nature.com/articles/s41598-017-10214-3

  • Revisiting bacterial phylogeny: Natural and experimental evidence for horizontal gene transfer of 16S rRNA 招待 査読 国際誌

    Kitahara, K, Miyazaki, K

    Mobile Genetic Elements   3 ( 1 )   e24210   2013年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Mutational robustness of 16S ribosomal RNA, shown by experimental horizontal gene transfer in Escherichia coli 査読 国際誌

    Kei Kitahara, Yoshiaki Yasutake, Kentaro Miyazaki

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   109 ( 47 )   19220 - 19225   2012年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATL ACAD SCIENCES  

    The bacterial ribosome consists of three rRNA molecules and 57 proteins and plays a crucial role in translating mRNA-encoded information into proteins. Because of the ribosome's structural and mechanistic complexity, it is believed that each ribosomal component coevolves to maintain its function. Unlike 5S rRNA, 16S and 23S rRNAs appear to lack mutational robustness, because they form the structural core of the ribosome. However, using Escherichia coli Delta 7 (null mutant of operons) as a host, we have recently shown that an active hybrid ribosome whose 16S rRNA has been specifically substituted with that from non-E. coli bacteria can be reconstituted in vivo. To investigate the mutational robustness of 16S rRNA and the structural basis for its functionality, we used a metagenomic approach to screen for 16S rRNA genes that complement the growth of E. coli Delta 7. Various functional genes were obtained from the Gammaproteobacteria and Betaproteobacteria lineages. Despite the large sequence diversity (80.9-99.0% identity with E. coli 16S rRNA) of the functional 16S rRNA molecules, the doubling times (DTs) of each mutant increased only modestly with decreasing sequence identity (average increase in DT, 4.6 s per mutation). The three-dimensional structure of the 30S ribosome showed that at least 40.7% (628/1,542) of the nucleotides were variable, even at ribosomal protein-binding sites, provided that the secondary structures were properly conserved. Our results clearly demonstrate that 16S rRNA functionality largely depends on the secondary structure but not on the sequence itself.

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  • Base methylations in the double-stranded RNA by a fused methyltransferase bearing unwinding activity 査読 国際誌

    Satoshi Kimura, Yoshiho Ikeuchi, Kei Kitahara, Yuriko Sakaguchi, Takeo Suzuki, Tsutomu Suzuki

    NUCLEIC ACIDS RESEARCH   40 ( 9 )   4071 - 4085   2012年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    Modifications of rRNAs are clustered in functional regions of the ribosome. In Helix 74 of Escherichia coli 23S rRNA, guanosines at positions 2069 and 2445 are modified to 7-methylguanosine(m(7)G) and N-2-methylguanosine(m(2)G), respectively. We searched for the gene responsible for m(7)G2069 formation, and identified rlmL, which encodes the methyltransferase for m(2)G2445, as responsible for the biogenesis of m(7)G2069. In vitro methylation of rRNA revealed that rlmL encodes a fused methyltransferase responsible for forming both m(7)G2069 and m(2)G2445. We renamed the gene rlmKL. The N-terminal RlmL activity for m(2)G2445 formation was significantly enhanced by the C-terminal RlmK. Moreover, RlmKL had an unwinding activity of Helix 74, facilitating cooperative methylations of m(7)G2069 and m(2)G2445 during biogenesis of 50S subunit. In fact, we observed that RlmKL was involved in the efficient assembly of 50S subunit in a mutant strain lacking an RNA helicase deaD.

    DOI: 10.1093/nar/gkr1287

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  • Specific inhibition of bacterial RNase T2 by helix 41 of 16S ribosomal RNA 査読 国際誌

    Kei Kitahara, Kentaro Miyazaki

    NATURE COMMUNICATIONS   2   549 - 549   2011年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATURE PUBLISHING GROUP  

    Ribonuclease (RNase) T2 is involved in scavenging exogenous RNAs in the periplasmic space of bacteria. In Escherichia coli, although the 30S ribosomal subunit has long been known as a specific inhibitor of RNase T2 (designated as RNase I in E. coli), both the biochemical mechanisms and physiological roles of this interaction remain to be elucidated. Here we show, by creating hybrid ribosomes and mutational studies, that helix 41 (h41) of the E. coli 16S ribosomal RNA has a crucial role in the specific inhibition of RNase I. Notably, h41-mutant strains exhibit a lower survival rate at stationary phase and severe cell lysis when the post-segregation killing protein SrnB is expressed. These phenotypic defects accompany significant RNA degradation caused by RNase I. Thus, h41 in 16S rRNA provides a physiological benefit for the host cells in coping with the potential cytotoxicity of RNase T2.

    DOI: 10.1038/ncomms1553

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  • The Ordered Transcription of RNA Domains Is Not Essential for Ribosome Biogenesis in Escherichia coli 査読 国際誌

    Kei Kitahara, Tsutomu Suzuki

    MOLECULAR CELL   34 ( 6 )   760 - 766   2009年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CELL PRESS  

    Ribosome biogenesis is coupled to the transcription of ribosomal (r)RNAs, which enables an ordered and hierarchical assembly of the ribosome starting with the 5&apos;-terminal domain. We constructed four circular permutants (CPs) of Escherichia coli rRNAs in which the original termini of 16S or 23S rRNAs were genetically connected, and new termini were created elsewhere within the same rRNAs (in helix 33 of 16S rRNA, or in helices 45, 63, and 78 of 23S rRNA). Unexpectedly, all CPs tested were able to rescue E coli strain Delta 7 prrn, which lacks all chromosomal rRNA operons. This result demonstrates that hierarchical assembly from the 5&apos;-terminal domain of both 16S and 23S rRNAs is not essential for ribosomal formation in the cell. However, severe growth defects of all CPs were found in the absence of the DEAD box RNA helicase deaD, indicating that DeaD assists in the efficient assembly of each subunit in the cell.

    DOI: 10.1016/j.molcel.2009.05.014

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  • The RNA acetyltransferase driven by ATP hydrolysis synthesizes N-4-acetylcytidine of tRNA anticodon 査読 国際誌

    Yoshiho Ikeuchi, Kei Kitahara, Tsutomu Suzuki

    EMBO JOURNAL   27 ( 16 )   2194 - 2203   2008年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATURE PUBLISHING GROUP  

    The wobble base of Escherichia coli elongator tRNA(Met) is modified to N-4-acetylcytidine (ac(4)C), which is thought to ensure the precise recognition of the AUG codon by preventing misreading of near-cognate AUA codon. By employing genome-wide screen of uncharacterized genes in Escherichia coli ('ribonucleome analysis'), we found the ypfI gene, which we named tmcA (tRNA(Met) cytidine acetyltransferase), to be responsible for ac(4)C formation. TmcA is an enzyme that contains a Walker-type ATPase domain in its N-terminal region and an N-acetyltransferase domain in its C-terminal region. Recombinant TmcA specifically acetylated the wobble base of E. coli elongator tRNA(Met) by utilizing acetyl-coenzyme A (CoA) and ATP (or GTP). ATP/GTP hydrolysis by TmcA is stimulated in the presence of acetyl-CoA and tRNA(Met). A mutation study revealed that E. coli TmcA strictly discriminates elongator tRNA(Met) from the structurally similar tRNA(Ile) by mainly recognizing the C27-G43 pair in the anticodon stem. Our findings reveal an elaborate mechanism embedded in tRNA(Met) and tRNA(Ile) for the accurate decoding of AUA/AUG codons on the basis of the recognition of wobble bases by the respective RNA-modifying enzymes.

    DOI: 10.1038/emboj.2008.154

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  • Functional genetic selection of Helix 66 in Escherichia coli 23S rRNA identified the eukaryotic-binding sequence for ribosomal protein L2 査読 国際誌

    Kei Kitahara, Akimasa Kajiura, Neuza Satomi Sato, Tsutomu Suzuki

    NUCLEIC ACIDS RESEARCH   35 ( 12 )   4018 - 4029   2007年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    Ribosomal protein L2 is a highly conserved primary 23S rRNA-binding protein. L2 specifically recognizes the internal bulge sequence in Helix 66 (H66) of 23S rRNA and is localized to the intersubunit space through formation of bridge B7b with 16S rRNA. The L2-binding site in H66 is highly conserved in prokaryotic ribosomes, whereas the corresponding site in eukaryotic ribosomes has evolved into distinct classes of sequences. We performed a systematic genetic selection of randomized rRNA sequences in Escherichia coli, and isolated 20 functional variants of the L2-binding site. The isolated variants consisted of eukaryotic sequences, in addition to prokaryotic sequences. These results suggest that L2/L8e does not recognize a specific base sequence of H66, but rather a characteristic architecture of H66. The growth phenotype of the isolated variants correlated well with their ability of subunit association. Upon continuous cultivation of a deleterious variant, we isolated two spontaneous mutations within domain IV of 23S rRNA that compensated for its weak subunit association, and alleviated its growth defect, implying that functional interactions between intersubunit bridges compensate ribosomal function.

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書籍等出版物

  • Constructing mutant ribosomes containing mutant ribosomal RNAs. Applied RNA Bioscience

    Kitahara, K, Miyazaki, K( 担当: 共著)

    Springer  2018年4月 

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  • 「リボソームの立体構造と抗生物質の作用機序」バイオテクノロジーシリーズRNA工学の基礎と応用 (pp. 225-236、監修 中村義一、大内将司) シーエムシー出版

    北原 圭, 鈴木 勉( 担当: 共著)

    シーエムシー出版  2010年 

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MISC

  • ゲノム微生物学分野の研究動向:リボソームRNAの変異体作成技術, 招待

    北原 圭

    Soc. Genome Microbiol. JPN   12   4 - 9   2015年12月

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    記述言語:日本語  

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  • Investigating bactericidal mechanism of antimicrobial peptides

    Kitahara, K, Sunami, T, Yomo, T

    Polymer Preprints Japan   63 ( 1 )   2014年7月

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  • Can bacteria adapt to starvation-free environment?

    Kitahara, K

    Nature Precedings, hdl:10101/npre.2012.7017.1   2012年3月

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  • Circular permutants of the ribosomes in the cell

    Tsutomu Suzuki, Kei Kitahara

    FASEB JOURNAL   23   2009年4月

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    記述言語:英語   掲載種別:研究発表ペーパー・要旨(国際会議)   出版者・発行元:FEDERATION AMER SOC EXP BIOL  

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  • Systematic deletion of rRNAs for investigating ribosome architecture and function 国際誌

    Kitahara, K, Sato, N. S, Namba, N, Yokota, T, Tsujimura, T, Suzuki, T

    Nucleic Acids Symposium Series   50 ( 50 )   287 - 288   2006年11月

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講演・口頭発表等

  • ASCODD 2022: The 16th Asian Conference on Diarrhoeal Disease and Nutrition 招待

    Kei Kitahara

    2022年11月 

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    記述言語:英語   会議種別:シンポジウム・ワークショップ パネル(指名)  

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  • Biometal Science 2019, Sapporo, Japan 招待

    Kei Kitahara

    2019年6月 

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    記述言語:英語   会議種別:シンポジウム・ワークショップ パネル(指名)  

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  • PU-HU Joint Symposium, Beijing, China 招待

    Kei Kitahara

    2018年9月10日 

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  • BIOTEC-HU-AIST Joint Symposium 2018, Thailand Science Park, Thailand 招待

    Kei Kitahara

    2018年3月 

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  • The 13th Nanging University-Hokkaido University-NIMS-Jiaxing University Joint symposium, Bojin-Wan, Jiaxing, China 招待

    Kei Kitahara

    2017年10月 

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  • JKU-HU Joint Symposium on Chemical Sciences and Engineering 2017, Johannes Kepler University, Linz, Austria 招待

    Kei Kitahara

    2017年2月 

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受賞

  • Academic Fantasista(「国民との科学・技術対話」推進事業)

    2018年7月   北海道大学  

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  • 第3回ビジネスモデル発見&発表会 北海道大会 研究者特別賞

    2017年2月  

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  • "Topics of the session"

    2009年7月   第11回日本RNA学会年会(平成21年、新潟)  

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共同研究・競争的資金等の研究

  • 大腸菌はどこまで速く増殖可能か?―増殖システムの効率限界の探索

    研究課題/領域番号:20K20301  2017年06月 - 2023年03月

    日本学術振興会  科学研究費助成事業  挑戦的研究(開拓)

    北原 圭, 宮崎 健太郎

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    配分額:19760000円 ( 直接経費:15200000円 、 間接経費:4560000円 )

    代表者は、生物システムを非生物システムから区別する性質である「自己増殖能」を効率性の観点から徹底的に理解することを試みるために本研究を実施している。特に、生命(=増殖)システムの本質を理解するためには、その化学的な最大効率を明らかにする必要があると考えた。究極的には2分とか3分とかで倍加するような生物を開発することを目指す研究を通じ、「最も生物らしいひとつのシステム」がどのように構築し得るのかについてアプローチしたいと考えている。今年度は、申請書記載の研究計画を実施するとともに、これまでとは異なる観点の研究項目も新たに取り入れた。まず、自然界から増殖速度が大きい(倍加時間が短い)バクテリアを探索する技術開発を進め、複数の高速増殖(分離)株を入手することに成功した。これらの株のうちいくつかは系統的に大腸菌と近縁であったことから、これらの株のゲノム配列を参照することにより大腸菌の増殖速度を高めることができるのではないかと期待している。次年度の研究では、この観点でのアプローチを用いた研究を具体的に展開したいと考えている。また、大腸菌の増殖速度を最大限に高めることができる培養条件を昨年度までに構築しているが、こちらについても更なる条件検討を行うことにより効率的に大腸菌を増殖させる条件が明らかになってきた。また、培地添加物として培地中に導入すると効果的であるいくつかの成分を特定することができたので、その条件を基本培養条件として固定し、上述の組み換え大腸菌の増殖速度が野生型の限界よりもさらに上昇するかどうかを検討していきたい。バクテリアの増殖に対する律速となるのは、タンパク質合成装置リボソームの主成分であるリボソームRNA (rRNA)の数であることが古くから指摘されている。高速培養条件、あるいは高速増殖株で翻訳系にそのような変化が起きるのかについても併せて検討していく予定である。

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  • 16S rRNA遺伝子の異種間水平伝播の可能性を探求する

    研究課題/領域番号:25830132  2013年04月 - 2015年03月

    日本学術振興会  科学研究費助成事業  若手研究(B)

    北原 圭

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    配分額:2860000円 ( 直接経費:2200000円 、 間接経費:660000円 )

    原核生物では遺伝子の水平伝播が一般的であるため、その分子分類は16S rRNA遺伝子の塩基配列の相同性を基準に行われることが多い。この手法の理論的大前提には「16S rRNA遺伝子は異種間水平伝播が困難である」という仮定(complexity仮説)が存在する。本研究は分子進化におけるcomplexity仮説という、一見確立されたモデルを批判的に検証することを目的としている。そのために大腸菌をモデルとして、メタゲノム由来16S rRNA遺伝子を実験的に水平伝播させる実験を実施した。

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  • 平成22年度笹川科学研究助成学術研究部門

    2010年04月 - 2011年03月

    日本科学財団 

    北原 圭

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    担当区分:研究代表者  資金種別:競争的資金

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  • 平成21年度調査研究助成

    2010年04月 - 2011年03月

    財団法人科学技術融合振興財団(FOST) 

    北原 圭

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    担当区分:研究代表者  資金種別:競争的資金

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