Faculty Profiles - FUNAHASHI Hiroaki

Papers - FUNAHASHI Hiroaki

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In-vitro Culture with a Tilting Device in Chemically Defined Media During Meiotic Maturation and Early Development Improves the Quality of Blastocysts Derived from In-vitro Matured and Fertilized Porcine Oocytes Reviewed

Takayuki Koike, Koji Matsuura, Keiji Naruse, Hiroaki Funahashi

JOURNAL OF REPRODUCTION AND DEVELOPMENT 56 ( 5 ) 552 - 557 2010.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：SOCIETY REPRODUCTION & DEVELOPMENT-SRD

Under physiological conditions, mammalian oocytes and embryos appear to be stimulated not only chemically but also mechanically, such as by compression, shear stress and/or friction force in the follicle and female reproductive tract. The present study was undertaken to examine the effects of kinetic culture with a tilting device in chemically defined media during in vitro maturation (IVM) of porcine oocytes and in vitro culture (IVC) following in vitro fertilization (IVF) on the early developmental competence and quality of blastocysts. After culture in a chemically defined IVM medium, modified porcine oocyte medium (mPOM) containing gonadotropins and dibutyryl cAMP for 20 h, the mean diameter of the cumulus-oocyte complexes (COCs) was larger in the tilting culture than in the static controls, whereas the diameter of the oocytes did not differ. When culture of the COCs was continued additionally in a fresh medium without gonadotropins and dibutyryl cAMP for 24 h, the incidences of oocytes completing GVBD and developing to the metaphase-II stage did not differ between the tilting and static culture systems. Furthermore, the sperm penetration after IVF and developmental competence of the oocytes to the blastocyst stage were not different between the tilting and static systems during IVM and IVC. However, tilting culture during both IVM and IVC had a significant positive effect on the number of cells per blastocyst (P<0.05). These observations indicate that tilting culture during IVM and IVC in chemically defined media improves the quality of blastocyst, as determined by the number of cells per blastocyst, without any effects on penetrability and developmental competence.

DOI： 10.1262/jrd.10-041H

Effect of blood serum, caffeine and heparin on in vitro phagocytosis of frozen-thawed bull sperm by neutrophils derived from the peripheral blood of cows Reviewed International journal

J. C. Li, H. Funahashi

Theriogenology 74 ( 4 ) 691 - 698 2010.9

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

Although polymorphonuclear leukocytes (PMNs) are recruited into the uterine lumen to phagocytize sperm, factors controlling the phagocytotic ability of PMNs in cattle are not well documented. The objective was to determine the effects of blood serum, caffeine, and heparin on chemotaxis of PMNs for sperm and phagocytosis of sperm by PMNs in cows. Polymorphonuclear leukocytes were obtained (centrifugation) from a cow's peripheral blood. In Experiment 1, the chemotactic activity of PMNs increased (P &lt
0.01) when fresh serum was included in the medium (1226 cells/mm2 in serum vs. 1110 cells/mm2 in BSA), regardless of the presence of sperm, whereas heat-inactivated serum (1099 cells/mm2) did not affect their activity (P = 0.65). Phagocytosis of live and dead sperm by PMNs both increased (P &lt
0.01) in the presence of fresh serum (incidences of 54.5 and 48.0%, respectively), but stimulation was decreased (P &lt
0.01) by supplementation of the medium with ≥1 mM caffeine (20.6-30.3%). Serum-stimulated chemotactic activity of PMNs (1218 cells/mm2) was also decreased (P &lt
0.01) in the presence of caffeine (1090 cells/mm2). Furthermore, supplementation of PMNs with heparin in the presence of serum decreased (P &lt
0.01) both phagocytotic (from 43.8% to 21.5-31.7%) and chemotactic activities of PMNs (from 1124 to 1048-1108 cells/mm2). We inferred that opsonization in the presence of active complement stimulated phagocytotic and chemotactic activities of PMNs, and that both caffeine and heparin decreased serum-stimulated phagocytotic and chemotactic activities of PMNs. © 2010 Elsevier Inc.

DOI： 10.1016/j.theriogenology.2010.03.019

Application of a microfluidic sperm sorter to the in-vitro fertilization of porcine oocytes reduced the incidence of polyspermic penetration Reviewed International journal

Hikaru Sano, Koji Matsuura, Keiji Naruse, Hiroaki Funahashi

THERIOGENOLOGY 74 ( 5 ) 863 - 870 2010.9

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE INC

The objective of this study was to use a microfluidic sperm sorter (MFSS), designed to isolate motile human spermatozoa with laminar flows (no centrifugation), for porcine IVF. Boar spermatozoa were diluted at 1 x 10(8) with a diluent containing 20% seminal fluid and flowed with modified TCM-199 (mM199, with 5 mM caffeine) to introduce motile sperm into the exit chamber for IVF. In Experiment 1, after flowing for 5 min, sperm concentration varied significantly among specific sites within the MFSS collecting chamber (range, 0.8 +/- 0.5 x 10(4) to 575.0 +/- 56.3 x 10(4) cells/mL; mean +/- SEM). In Experiment 2, when porcine IVM oocytes were placed at three locations in the MFSS exit chamber (where only motile spermatozoa accumulated) and subsequently cultured in caffeine-free mM199 for 8 h, sperm penetration rate was not significantly different among places (86.1 +/- 10.5 to 100%), but the monospermic penetration rate was lower (P < 0.05) in oocytes 3.5 mm from the exit position (12.5 +/- 4.8%) than those at 7.5 mm (53.1 +/- 6.0%) or further (41.9 +/- 2.8%) from the exit. In Experiment 3, the normal fertilization index (ratio of monospermic oocytes to number of oocytes examined) 8 h after insemination was higher (P < 0.05) in the MFSS-IVF system (0.375 +/- 0.040) than both standard IVF and transient IVF (0.222 +/- 0.028 and 0.189 +/- 0.027, respectively, with co-culture for 8 h and for 5 min). Developmental competence of fertilized oocytes (blastocyst formation) was higher (P < 0.05) in the MFSS-IVF system (40.9 +/- 2.3%) than in either standard or transient IVF (22.6 +/- 1.4 and 33.7 +/- 3.5%). In conclusion, brief co-culture of porcine oocytes with spermatozoa gradually accumulated in the MFSS chamber improved the efficiency of producing monospermic fertilized embryos and blastocysts. Furthermore, efficiencies were significantly affected by oocyte location within the chamber. (C) 2010 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.theriogenology.2010.04.011

Application of mechanical stimuli using a microfluidic air actuating system to cultured mammalian embryos Reviewed

Jing Chun Li, Koji Matsuura, Yuka Kuroda, Hiroaki Funahashi, Keiji Naruse

2010 International Symposium on Micro-NanoMechatronics and Human Science: From Micro and Nano Scale Systems to Robotics and Mechatronics Systems, MHS 2010, Micro-Nano GCOE 2010, Bio-Manipulation 2010 29 - 34 2010

Language：English Publishing type：Research paper (international conference proceedings)

Mammalian embryos experience not only hormonal but also mechanical stimuli, such as shear stress, compression, and friction force, in the fallopian tube before nidation. We aim to develop a novel and simple system to apply mechanical stimuli (MS) similar to those generated inside the oviduct to cultured mammalian embryos. Possible MS include shear stress (SS) caused by fluid dynamics and compression of embryos due to interactions with the wall of the oviduct. A new culture system was developed to increase SS and to apply MS during in vitro embryo cultures. We developed an air actuating system with microfluidic channels to apply MS by deforming a 0.1-mm-thick poly(dimethylsiloxiane) membrane and evaluated MS applied to ICR mouse embryos inside the microfluidic channel. Using this air actuating system, we applied compression to mouse embryos inside the medium channel and estimated SS on the basis of the velocity of the embryos' motion. By changing the syringe velocity, we applied different types of MS to the em bryos. These results suggested that multiple MS such as SS and compression can be applied at the same time. MS applied using this system was similar to those generated in the physiological environment of the oviduct. ©2010 IEEE.

DOI： 10.1109/MHS.2010.5669581

Improved Fertility in Gilts and Sows after Artificial Insemination of Frozen-Thawed Boar Semen by Supplementation of Semen Extender with Caffeine and CaCl2 Reviewed

Shoichiro Yamaguchi, Hiroaki Funahashi, Tetsuya Murakami

JOURNAL OF REPRODUCTION AND DEVELOPMENT 55 ( 6 ) 645 - 649 2009.12

Language：English Publishing type：Research paper (scientific journal) Publisher：SOCIETY REPRODUCTION & DEVELOPMENT-SRD

Supplementation of semen extender with caffeine and CaCl2 for artificial insemination (Al) of fresh spermatozoa has been demonstrated to reduce recruitment of uterine polymorphonuclear leukocytes (PMNs) and the activity of phagocytosis. Here, we determined if addition of caffeine and CaCl2 to semen extender improves the fertility of frozen-thawed boar semen. In experiment 1, gilts were cervically inseminated twice with froxzen-thawed boar spermatozoa (25 x 10(8) cells per dose) suspended in Modena solution (n=7) or modified Beltsville Thawing Solution supplemented with caffeine and CaCl2 (BCC, n=7). The gilts were slaughtered 4 h later, and their oviducts and uterine horns plus the body of the uterus were flushed to recover PMNs and non-phagocytosed spermatozoa. There was no difference in the total number of uterine PMNs between gilts inseminated with Modena solution and those inseminated with BCC (3.8 x 10(8) vs. 1.5 x 10(8) cells, respectively); however, the total number of uterine spermatozoa was higher when gilts were inseminated with BCC (40.6 x 10(6) cells) compared with those inseminated with Modena solution (1.4 x 10(6) cells, P<0.05). In experiment 2, gilts and sows were subjected to intrauterine insemination twice with frozen-thawed spermatozoa suspended (25 x 10(8) sperm per dose) in Modena (n=21) or BCC (n=21). The overall pregnancy and farrowing rates were higher in females inseminated with BCC (71.4 and 61.9%, respectively) compared with those inseminated with Modena Solution (38.1 and 28.6%, respectively, P<0.05). However, no significant difference in litter size of piglets was observed between treatments (7.2 +/- 1.6 piglets for Modena solution vs. 8.2 +/- 0.9 piglets for BCC solution). In conclusion, we demonstrated that use of BCC solution for frozen-thawed boar semen produced better pregnancy and farrowing rates following Al. than Modena solution, probably by reducing the phagocytosis of spermatozoa.

DOI： 10.1262/jrd.20238

Successful Piglet Production in a Chemically Defined System for In-vitro Production of Porcine Embryos: Dibutyryl Cyclic AMP and Epidermal Growth Factor-family Peptides Support In-vitro Maturation of Oocytes in the Absence of Gonadotropins Reviewed

Yuka Akaki, Koji Yoshioka, Michiko Noguchi, Hiroyoshi Hoshi, Hiroaki Funahashi

JOURNAL OF REPRODUCTION AND DEVELOPMENT 55 ( 4 ) 446 - 453 2009.8

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：SOCIETY REPRODUCTION & DEVELOPMENT-SRD

To induce meiotic resumption of porcine oocytes, it is thought to be necessary to expose the cumulus-oocyte complexes (COCs) to gonadotropins during in-vitro maturation (IVM). However, the detailed mechanism of meiotic resumption by gonadotropins is still unknown, and successful piglet production has not been reported by using oocytes matured in gonadotropin-free media and fertilized in vitro. The present study was undertaken to examine the combinational effects of epidermal growth factor (EGF)-family members and dibutyryl cyclic AMP (cAMP) in a chemically defined medium on IVM of porcine oocytes and the developmental competence following in vitro fertilization (IVF). The basic IVM medium was a chemically defined medium, modified porcine oocyte medium (n-LPOM.). Supplementation of the IVM medium with 10 or 1000 ng/ml EGF, amphiregulin and betacellulin during the whole IVM period, except for 10 ng/ml amphiregulin, increased the percentage of oocytes maturing to the metaphase-II stage. When COCs were exposed to both dibutyryl cAMP and EGF-family members during the first 20-h of IVM and then culture was continued in the absence of EGF-family members and dibutyryl cAMP, the incidence of metaphase-II oocytes was significantly increased and was not different from that of oocytes cultured in a standard IVM system with gonadotropins. The developmental competence of the oocytes to the blastocyst stage following IVF was no different from that of control oocytes matured with gonadotropins. When these blastocysts were transferred into the uterine horn of three recipients, all of gilts became pregnant and delivered a total of 11 piglets. These observations indicate that supplementation of a chemically defined maturation medium with EGF-family members and dibutyryl cAMP during the first 20 h of IVM can support well the meiotic progress and developmental competence of porcine oocytes.

DOI： 10.1262/jrd.20219

Exogenous adenosine Reduces the mitochondrial membrane potential of murine oocytes during the latter half of in vitro maturation and pronuclear formation following chemical activation Reviewed

Wataru Fujii, Hiroaki Funahashi

Journal of Reproduction and Development 55 ( 2 ) 187 - 193 2009.5

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

The present study was undertaken to determine the effect of nucleosides on nuclear and cytoplasmic maturation of mouse oocytes. Oocyte-cumulus complexes (OCCs) were collected from large antral follicles 4 h after eCG-hCG treatment and cultured in maturation medium with or without nucleosides (4 ribo- and 4 deoxyribonucleosides) for 12 h. A majority of the oocytes examined developed to the metaphase-II stage, and the same result was found with in-vivo matured oocytes. However, mitochondrial membrane potential (MMP) was significantly lower in the oocytes matured in the presence of nucleosides than in the nucleoside-free controls. Oocyte MMP increased in vivo between 8 to 12 h after hCG injection, whereas no increases in MMP were observed in oocytes matured in the presence of nucleosides. Oocyte MMP was significantly lower only when OCCs were exposed to nucleosides for the latter 8 h of IVM. When OCCs were exposed to adenosine during the latter 8 h of IVM, MMP was lower compared with in-vivo matured oocytes, whereas a mixture of other ribonucleosides (guanosine, cytidine and uridine) did not affect the level of MMP. The developmental competence of oocytes exposed to adenosine during the latter 8 h of IVM was lower after parthenogenetic activation due to the lower pronuclear formation of the oocytes. These observations indicate that adenosine inhibits increases in oocyte MMP during the latter half of meiotic maturation and detrimentally affects cytoplasmic maturation.

DOI： 10.1262/jrd.20122

Effect of glucose and pyruvate on nuclear and cytoplasmic maturation of porcine oocytes in a chemically defined medium Reviewed International journal

H. Funahashi, T. Koike, R. Sakai

Theriogenology 70 ( 7 ) 1041 - 1047 2008.10

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

The objective was to examine potential roles of glucose and pyruvate in nuclear and cytoplasmic maturation of porcine oocytes. Oocyte-cumulus complexes (OCC), derived from 3 to 6 mm follicles, were cultured in a chemically defined medium (pyruvate-free mNCSU37-PVA), with or without 5.55 mM glucose, during in vitro maturation (IVM); in the absence of glucose, germinal vesicle breakdown (GVBD) and nuclear maturation were prevented (P < 0.05). Subsequently, OCC were cultured for IVM in glucose-containing mNCSU37-PVA supplemented with 6-amononicotinamide (6-AN) and diphenyleneiodonium (DPI), inhibitors of the pentose phosphate pathway (PPP); both compounds (≥10 μM 6-AN and ≥10 nM DPI) inhibited resumption of meiosis (P < 0.05). Supplementation of glucose-free maturation medium with increasing concentrations of pyruvate induced resumption of meiosis and increased the incidence of oocytes reaching metaphase-II in a concentration-dependent manner (P < 0.05). More mature oocytes were obtained in the presence of pyruvate + glucose (P < 0.05). After culture to allow maturation, glutathione content was higher in oocytes cultured in the presence of pyruvate alone than in those cultured in glucose alone; inclusion of 6-AN abolished responses to pyruvate (P < 0.05). In conclusion, both glucose and pyruvate played a critical role in the release of porcine oocytes from arrest at the GV-I stage, probably through the PPP, whereas supplementation with pyruvate improved cytoplasmic maturation, as determined by oocyte glutathione content. © 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.theriogenology.2008.06.025

Metal mesh vitrification (MMV) method for cryopreservation of porcine embryos Reviewed

Y. Fujino, T. Kojima, Y. Nakamura, H. Kobayashi, K. Kikuchi, H. Funahashi

Theriogenology 70 ( 5 ) 809 - 817 2008.9

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

The objective was to develop a simpler, more reliable vitrification method for porcine embryos. Prepubertal donor gilts were induced to ovulate with eCG and hCG, and then inseminated artificially. Morulae and expanding blastocysts approximately 200 μm in diameter were collected 6 or 7 d after hCG treatment. Embryos collected from donor gilts were maintained, so as to be individually recognizable, and handled in batches of four or five. The embryos together with a minimum volume (&lt
2 μL) of vitrification solution were placed onto stainless steel metal meshes or plastic plates, and then plunged into liquid nitrogen-metal mesh vitrification (MMV) and plastic plate vitrification (PPV), respectively. The meshes or plates were stored in 1.8-mL cryotubes submerged in liquid nitrogen. Stored embryos were subsequently removed, cultured in medium for 24 h, and then assessed for viability. The survival rate (84.4%) of expanding blastocysts cooled by MMV was higher than that (53.1%) of embryos cooled by PPV (P &lt
0.05). There was no significant difference in total cell number between MMV and PPV. The survival rate of morulae cooled by MMV was 55.0%. Transfer of 200 expanding blastocysts cooled by MMV to 10 synchronized recipient gilts resulted in 37 live piglets from 7 recipients. In conclusion, the MMV method was an effective vitrification procedure for cryopreservation of expanding porcine blastocysts. However, there was a batch effect on embryo survival after vitrification. © 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.theriogenology.2008.05.045

In vitro development of non-enucleated rat oocytes following microinjection of a cumulus nucleus and chemical activation Reviewed International journal

Wataru Fujii, Hiroaki Funahashi

Zygote 16 ( 2 ) 117 - 125 2008.5

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

The present study examined in vitro development and the cytological status of non-enucleated rat oocytes after microinjection of cumulus nuclei and chemical activation. Oocytecumulus complexes were collected from gonadotropin-treated prepubertal female Wistar rats 14 h after human chorionic gonadotropin (hCG) injection. Cumulus nuclei were injected into ovulated oocytes and then stimulated in the presence of 5 mM SrCl2 for 20 min at various time points (03.5 h) after injection. Some of the reconstituted eggs were cultured to observe the pronuclear formation, cleavage, and blastocyst formation. The incidences of eggs forming at least one pronucleus or containing two pronuclei were not significantly different among the periods (82.483.5% and 43.451.9%, respectively). Nor did the incidences of eggs cleaving (86.797.7%) and developing to the blastocyst stage (03.5%) differ depending on when, after injection, stimulation began. When some of the reconstituted eggs were observed for cytological morphology 11.5 h after injection, 71.7% of the eggs caused premature chromatin condensation, but only 46.2% of them formed two spindles around each of maternal and somatic chromatins. However, the morphology of the somatic spindles differed from that of the spindles, which formed around the oocyte chromatins. Only 7.5% of the eggs contained the normal chromosomal number. In many reconstituted oocytes, before activation, an abnormal spindle formation was observed in the somatic chromatins. In conclusion, these results show that non-enucleated rat oocytes injected with cumulus nuclei can form pronuclei and cleave following chemical activation, whereas blastocyst formation is very limited, probably caused by abnormalities in the spindle formation and distribution of somatic chromatids. © 2008 Cambridge University Press.

DOI： 10.1017/S0967199408004632

Up date of in vitro production of porcine embryos Invited Reviewed International journal

Takashi Nagai, Hiroaki Funahashi, Koji Yoshioka, Kazuhiro Kikuchi

Frontiers in bioscience-landmark 11 ( SUPPL. 2 ) 2565 - U34 2006.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Bioscience research inst-bri

There have been intensive attempts to establish reliable in vitro maturation (IVM) and fertilization (IVF) methods in pigs. Although a great deal of progress has been made, current IVM-IVF systems still suffer from a low rate and poor quality of in vitro produced embryos. In this review, we will review the recent studies about IVM-IVF of porcine oocytes and the in vitro culture (IVC) system, especially modified in vitro production (IVP) system that produces high quality of porcine blastocysts. We then try to suggest practical ways to solve the problems mentioned above in the pigs.

DOI： 10.2741/1991

In vitro maturation and fertilization of porcine oocytes after a 48 h culture in roscovitine, an inhibitor of p34(cdc2)/cyclin B kinase Reviewed International journal

R Romar, H Funahashi

ANIMAL REPRODUCTION SCIENCE 92 ( 3-4 ) 321 - 333 2006.5

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

Maintaining oocytes at the germinal vesicle (GV) stage in vitro may permit enhanced acquisition of the developmental competence. The objective of the current study was to evaluate the nuclear and cytoplasmic maturation in vitro of porcine oocytes after pretreatment with S-roscovitine (ROS). Cumulus oocyte complexes (COC) were treated with 50 mu M ROS for 48 h and then matured for various lengths of time in a conventional step-wise in vitro maturation (IVM) system by using dibutyryl cyclic AMP. The COC that were matured in the same system for 44 h without pretreatment with ROS were used as the control group. At various periods after the start of IVM, oocytes were assessed for the meiotic stages and subjected to in vitro fertilization (IVF) with fresh spermatozoa. The ROS treatment inhibited GV breakdown of 94.4% oocytes, with the majority arrested at the GV-1 stage (67.4%). Maximum maturation rate to the metaphase-II stage after ROS treatment was achieved by 44 h of IVM (92.1 %) and no differences were observed with control oocytes (95.0%). Penetration rate was correlated to the maturation rate. The duration of IVM had no effects on polyspermy and male pronuclear (MPN) fort-nation rates at 8 h post insemination (hpi), whereas both rates increased at 22 hpi. Direct comparison with controls assessed at 22 hpi confirmed a lesser MPN formation in ROS-treated oocytes (73.7% compared with 53.6%). Glutathione (GSH) concentrations were less in oocytes treated with ROS than in control oocytes (5 compared with 7.7 pmol/oocyte) as well as blastocyst rate (22.0% compared with 38.1%, respectively). These results demonstrate that cytoplasmic maturation in porcine oocytes pretreated with ROS for 48 h did not equal that of control oocytes in the current lVM system. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.anireprosci.2005.04.017

Effect of beta-mercaptoethanol during in vitro fertilization procedures on sperm penetration into porcine oocytes and the early development in vitro. Reviewed International journal

Hiroaki Funahashi

Reproduction (cambridge, england) 130 ( 6 ) 889 - 98 2005.12

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

This study was carried out to determine the effects of beta-mercaptoethanol (bME) during a transient co-culture of gametes for 10 min, and/or the following culture until 6-9 h after insemination, on sperm penetration of porcine in vitro maturation (IVM) oocytes and the early development in vitro. When fresh spermatozoa were cultured in various concentrations of bME for 2 h, bME neutralized the stimulatory effect of caffeine-benzoate on sperm capacitation and the spontaneous acrosome reaction at 50-250 micromol/l. When 50 micromol/l bME were added during a transient co-culture of gametes for 10 min, the sperm penetration rate was reduced 9 h after insemination (70.5-82.0% vs 90.5-94.0% in the absence of bME), but the incidence of monospermic penetration was not affected. When 50 micromol/l bME were supplemented during culture after a transient co-culture, the sperm penetration rate was not affected, but the incidence of monospermy oocytes was increased (43.9-45.8% vs 31.7-34.3% in the absence of bME). The presence of bME following a transient co-culture minimized a decrease of oocyte glutathione content at 6 h after insemination (7.9 pmol/oocyte before in vitro fertilization (IVF), 6.7 pmol/oocyte in the presence of bME vs 5.5 pmol/oocyte in the absence of bME). When the distribution of cortical granules was evaluated 1 h after activation with calcium ionophore, mean pixel intensity of fluorescein isothiocyanate-labeled peanut agglutinin (FITC-PNA) at the cortex region was lower in the oocytes activated and cultured in the presence of 50 micromol/l bME. Although the presence of 50 micromol/l bME during a transient co-culture for 10 min and the following culture did not increased blastocyst formation (29.6-37.7%), 50 micromol/l bME during the following culture significantly increased the mean cell numbers per blastocyst (73.3-76.4 vs 51.2 in the presence and absence of bME respectively). These results demonstrate that supplementation with bME during IVF procedures, except during a transient co-culture period of gametes in the presence of caffeine, has a beneficial effect in maintaining the function of gametes, the incidence of normal fertilization and, consequently, the quality of IVF embryos.

DOI： 10.1530/rep.1.00702

Select antioxidants improve the function of extended boar semen stored at 10°C Reviewed

H. Funahashi, T. Sano

Theriogenology 63 ( 6 ) 1605 - 1616 2005.4

Reduction of the incidence of polyspermic penetration into porcine oocytes by pretreatment of fresh spermatozoa with adenosine and a transient co-incubation of the gametes with caffeine Reviewed

Hiroaki Funahashi, Raquel Romar

Reproduction 128 ( 6 ) 789 - 800 2004.12

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Bioscientifica

To reduce the incidence of polyspermic penetration, the effects of transient exposure of washed fresh spermatozoa to caffeine in a brief co-culturein vitrofertilization (IVF) system were examined. A pretreatment effect of spermatozoa with adenosine was also examined. When 5 mmol caffeine/l was supplemented during periods of co-culture and additional culture periods until 8 h after insemination, a shortened co-incubation period of gametes (30 denuded oocytes in 100 μl modified Medium 199-suspended spermatozoa at 2.5 ×10⁵sperm/ml) from 30 to 5 min increased the monospermy rate in total mature oocytes examined. The number of spermatozoa binding to the zona surface was significantly lower in oocytes co-cultured for 5 min (33.1 ± 2.2) than 8 h (207.6 ± 13.7). A limited exposure of gametes to 5 mmol caffeine/l only during a transient co-culture period for 5 or 30 min significantly reduced the mean number of sperm cells that penetrated into the oocyte. Transient exposure of spermatozoa to caffeine for only 5 min increased the percentage of capacitated cells but not acrosome-reacted cells, as compared with a whole exposure treatment. Furthermore, preincubation of spermatozoa with 10 μmol adenosine/l for 90 min increased both the incidence of capacitated cells and the monospermy rate and consequently decreased the number of sperm cells that penetrated into the oocyte. In conclusion, these results have demonstrated that a new transient co-incubation IVF system, in which denuded oocytes are co-cultured with spermatozoa in medium containing caffeine for 5 to 30 min and then continuing the culture in caffeine-free medium, will reduce the incidence of polyspermic penetration. Preincubation of fresh spermatozoa with adenosine before the transient co-incubation IVF can also improve the monospermy rate. Furthermore, asynchrony in the morphology of sperm nuclei in polyspermic oocytes was reduced by the pretreatment with adenosine and a brief exposure to caffeine.

DOI： 10.1530/rep.1.00295

Other Link： https://rep.bioscientifica.com/downloadpdf/journals/rep/128/6/1280789.xml

Polyspermic penetration in porcine IVM - IVF systems Reviewed

Hiroaki Funahashi

Reproduction, Fertility and Development 15 ( 3 ) 167 - 167 2003

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：CSIRO Publishing

Although techniques for in vitro production of porcine embryos have proceeded very rapidly during the past decade, polyspermic penetration still remains a persistent obstacle to porcine in vitro fertilization (IVF) systems. Considerable research on in vitro polyspermic penetration in porcine in vitro-matured (IVM) oocytes has been undertaken to try to solve this problem. In the current paper, recent advancements in overcoming the problems of polyspermy in porcine IVF systems are reviewed. Partial induction of the acrosome reaction of boar spermatozoa in IVF media that contain caffeine is likely to be one of the major causes of polyspermy. A reduction in the number of incompletely acrosome-reacted spermatozoa, which can bind tightly to the zona pellucida and mask free sperm receptors of the zona pellucida, could reduce the incidence of polyspermic penetration; however, morphological differences in the reaction of the zona pellucida have been observed between IVM and ovulated oocytes, which suggests that altered zona morphology may be another cause of polyspermic penetration. It has been shown that the developmental ability of polyspermic porcine embryos to the blastocyst stage is similar to that of normal embryos but that developmental competence to term is much lower. To overcome the current problems of polyspermy, it is suggested that future efforts should be focused on controlling boar sperm function and/or sperm–zona binding to achieve the final maturation associated with normal zona modifications of porcine oocytes at fertilization.

DOI： 10.1071/rd02076

Induction of capacitation and the acrosome reaction of boar spermatozoa by L-arginine and nitric oxide synthesis associated with the anion transport system Reviewed

H Funahashi

Reproduction 857 - 864 2002.12

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Bioscientifica

The aim of this study was to determine the effect of L-arginine on nitric oxide (NO) synthesis, capacitation and acrosome reaction of boar spermatozoa. Ejaculated boar spermatozoa were washed and then cultured in a bicarbonate:CO(2)-buffered medium, modified NCSU-37, for 2 h. At the end of the culture, the status of spermatozoa was determined. The presence of (0.1-2.0 mmol l(-1)) L-arginine in the culture medium induced an acrosome reaction as determined by fluorescein isothiocyanate-peanut agglutinin (FITC-PNA) and increased intracellular NO content, as quantified by a fluorescent indicator, diaminofluorescein-2 diacetate (DAF-2 DA). This stimulatory effect of L-arginine was neutralized by supplementation with an NO synthase inhibitor, N(omega)-nitro-L-arginine methyl ester (1 mmol l(-1)). However, the inactive enantiomorph, N(omega)-nitro-D-arginine methyl ester, did not affect the stimulatory effect of L-arginine. These results indicate that L-arginine induces an acrosome reaction through the NO signal pathway in boar spermatozoa. Furthermore, the stimulatory effect of L-arginine was inhibited in the presence of an anion transport inhibitor, 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulphonic acid (SITS; 0.1 mmol l(-1)), whereas any responses of spermatozoa to caffeine were not inhibited by SITS. A stimulatory effect of L-arginine on capacitation and acrosome reaction of spermatozoa was also observed in modified NCSU37 medium by using a chlortetracycline fluorescence assay, but not in supplemented bicarbonate-free Tris-buffered medium. These results indicate that the presence of L-arginine induces nitric oxide synthesis and stimulates capacitation and acrosome reaction of boar spermatozoa only when active sperm anion transport is present as a result of bicarbonate supplementation.

DOI： 10.1530/rep.0.1240857

Other Link： https://rep.bioscientifica.com/downloadpdf/journals/rep/124/6/857.xml

Effect of Methyl-.BETA.-Cyclodextrin and Fertilization Promoting Peptide on Capacitation of Boar Spermatozoa in a Protein-Free Medium. Reviewed

Hiroaki FUNAHASHI

Journal of Reproduction and Development 48 ( 1 ) 57 - 63 2002

Nuclear Transfer of Blastomeres Expressing EGFP-Reporter Gene May Improve the Efficiency of Transgenic Cattle Reviewed

H. Funahashi, A. Ideta, M. Konishi, M. Urakawa, K. Uruno, Y. Aoyagi, M. Okabe, K. Niwa

Cloning and Stem Cells 3 ( 4 ) 183 - 190 2001.12

Transmission electron microscopy studies of the zona reaction in pig oocytes fertilized in vivo and in vitro Reviewed

H Funahashi, H Ekwall, K Kikuchi, H Rodriguez-Martinez

Reproduction 443 - 452 2001.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：Bioscientifica

The aim of this study was to determine the ultrastructure of cross-sectioned zonae pellucidae of in vitro-matured and ovulated pig oocytes before or after sperm penetration in vitro and in vivo, respectively. The in vitro and in vivo (ovulated) oocytes and zygotes (fertilized in vitro and in vivo) were fixed with glutaraldehyde either directly or after pretreatment with ruthenium red and saponin, processed and then examined using transmission electron microscopy. The thickness of the zona pellucida, as measured on the section of the specimens with largest diameter fixed with glutaraldehyde, differed between the in vivo (9.19 +/- 0.47 microm) and in vitro (5.95 +/- 0.51 microm) oocytes. The in vivo oocytes had a rather thick external mesh-like structure, whereas it was much thinner in the in vitro oocytes. This mesh-like external rim was less apparent in both in vivo and in vitro zygotes. Obvious differences in the density of the lattice formed by the fixed zonae pellucidae were visible between the outer and inner (ad-oolemmal) zonae. The outer area always formed a concentrically arrayed fibrillar network, whereas the inner area showed a much more compact, trabecule-like mesh. However, both areas, but particularly the outer network, were much more compacted after the zona reaction. Clear differences in the degree of fibrillar aggregation of the inner zona area were also observed between in vitro and in vivo zygotes, being much higher in the latter. This fibrillar network was more clearly visible in the zygotes pretreated with ruthenium red and saponin; the in vitro zygotes had a fibrillar, radially oriented set of parallel fibrils, whereas it was much more aggregated and trabecule-like in the in vivo zygotes. These results demonstrate that the fine structure of the zona pellucida and the zona reaction at sperm penetration differ between pig oocytes fertilized in vivo and in vitro. Moreover, the ultrastructure of the outer and inner pig zonae pellucidae has a different network organization.

DOI： 10.1530/rep.0.1220443

Other Link： https://rep.bioscientifica.com/downloadpdf/journals/rep/122/3/443.xml

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