In vitro maturation and fertilization, and subsequent development of buffalo (Bubalus bubalis) embryos: effects of oocyte quality and type of serum

Buffalo sperm membrane glycan-binding proteins reveal precise and preferential binding signatures with specific glycans targets on oviduct epithelium and zona pellucida-an implication in fertilization

Sperm membrane glycan-binding proteins (lectins) interact with the counterpart glycans in the oviduct, oocytes, and vice-versa. It has already been well known that specific glycans are present on oviductal epithelium and zona pellucida (ZP) in different mammalian species. Some of these glycans are necessary for oviductal sperm reservoir formation and gamete recognition. The specific binding phenomenon of lectin-glycans is one of the vital factors for successful fertilization in mammals. We hypothesized that buffalo sperm membrane glycan-binding proteins have specific glycan targets in the oviduct and ZP supporting the fertilization event. In the present investigation, sperm membrane proteins were extracted and assessed for their binding capacity with glycans using a high-throughput glycan microarray. The most promising glycan binding signals were evaluated to confirm the sperm putative receptors for glycan targets in the oviductal epithelial cells (OEC) and on ZP using an in-vitro competitive binding inhibition assay. Based on an array of 100 glycans, we found that N-acetyllactosamine (LacNAc), Lewis-a trisaccharide, 3'-sialyllactosamine and LacdiNAc were the most promising glycans and selected for further in-vitro validation. We established an inhibitory concentration of 12 mM Lewis-a trisaccharide and 10 μg/ml Lotus tetragonolobus (LTL) lectin for the sperm-OEC binding interaction, indicating its specificity and sensitivity. We observed that 3 mM 3'-sialyllactosamine, and LacdiNAc were the most competitive inhibitory concentration in sperm-ZP binding, suggesting a specific and abundance-dependent binding affinity. The competitive binding affinity of Maackia amurensis (MAA) lectin with Neu5Ac(α2-3)Gal(β1-4)GlcNAc further supports the abundance of 3'-sialyllactosamine on ZP responsible for sperm binding. Our findings develop the strong evidence on buffalo sperm putative receptors underlying their locking specificities with Lewis-a trisaccharide in oviduct and 3'-sialyllactosamine on ZP. The functional interaction of buffalo sperm lectins with the target glycans in OEC and ZP appears to be accomplished in an abundance-dependent manner, facilitating the fertilization event in buffaloes.

Review: Development, adoption, and impact of assisted reproduction in domestic buffaloes

The domestic buffalo (Bubalus bubalis), also known as water buffalo, comprises two sub-species the River buffalo (B. bubalis ssp. bubalis; 50 chromosomes) and the Swamp buffalo (ssp. carabanensis; 48 chromosomes). Domestic buffaloes are a globally significant livestock species. In South Asia, the River buffalo is a primary source of milk and meat and has a very important role in food security. The River buffalo also supports high-value, differentiated food production in Europe and the Americas. The Swamp buffalo is an important draft animal and a source of food in Southeast Asia and East Asia. The growing importance of buffaloes requires that they undergo an accelerated rate of genetic gain for efficiency of production, product quality, and sustainability. This will involve the increased use of assisted reproduction. The initial application of reproductive technology in buffaloes had variable success as it relied on the adoption of procedures developed for cattle. This included artificial insemination (AI), sperm cryopreservation, and embryo technologies such as cloning and in vitro embryo production (IVEP). Reproductive technology has been progressively refined in buffaloes, and today, the success of AI and IVEP is comparable to cattle. Ovarian follicular superstimulation (superovulation) combined with in vivo embryo production results in low embryo recovery in buffaloes and has limited practical application. The contribution of elite female buffaloes to future genetic improvement will therefore rely mainly on oocyte pickup and IVEP. This will include IVEP from females before puberty to reduce generation intervals. This review provides for the first time a clear chronology on the development, adoption, and impact, of assisted reproduction in domestic buffaloes.

Optimization of recovery and maturation methods for cumulus-oocyte complexes in jennies

Embryo production in donkeys is inefficient compared with that in other livestock. Obtaining a sufficient number of MII oocytes is the first step to solving this problem. In this study, the number, morphology and maturation rates of cumulus-oocyte complexes (COCs) obtained from abattoir-derived ovaries or live jennies were compared. The diameter of follicles from abattoir-derived ovaries was measured and divided into group 1 (2-6 mm), group 2 (6-10 mm), group 3 (10-20 mm), group 4 (20-28 mm) and group 5 (>28 mm). The results showed that the number of follicles per ovary in group 2 (3.6 ± 0.28) and 3 (4.2 ± 0.90) was higher than that in the other groups (p < .05). The recovery rate in group 3 was higher than group 1 (48.8% vs. 26.8%, p = .00), but lower than group 5 (48.8% vs. 76.5%, p = .025). The percentage of grade A COCs in group 3 was higher than group 2 (59.3% vs. 39.5%, p = .00) and group 1 (59.3% vs. 26.7%, p = .00). Moreover, the percentage of grade A COCs in group 4 (55.0%, p = .710) and group 5 (46.2%, p = .351) was reduced compared with that in group 3. From the above results, the developing follicles (group ovum pick-up [OPU], 10-20 mm) and preovulation follicles (group OPU-Preov, >35 mm) were aspirated from live jennies using OPU. Although there was no difference in the recovery rates of COCs between group 3 and OPU (48.8% vs. 43.0%, p = .184), the percentage of grades A COCs in group OPU was higher than group 3 (72.5% vs. 59.3%, p = .036). There was no difference in the maturation rate between group 3 and OPU (60.3% vs. 69.3%, p = .171) after the COCs matured in vitro. The rates of recovery (72.2%) and maturation (92.3%) in group OPU-Preov were higher than those in other groups (p < .05). Moreover, the effects of maturation time and serum type on maturation rates were evaluated in groups B44 (44 h, FBS), B36 (36 h, FBS) and D44 (44 h, foetal donkey serum, FDS). These results indicated that the maturation rate in group B36 was lower than group B44 (13.1% vs. 47.0%, p = .00) and group D44 (13.1% vs. 53.3%, p = .00). In conclusion, the quality of donkey COCs from OPU was higher than that from abattoir-derived ovaries, the suitable time of donkey in vitro maturation (IVM) was 44 h, and FBS could be replaced with FDS in donkey IVM medium.

Relative expression of the developmentally important candidate genes in immature oocytes and in vitro-produced embryos of buffalo (Bubalus bubalis)

The study was undertaken to examine the relative abundance (RA) of the major developmental important candidate genes in different grades of immature oocytes (A-grade, B-grade, C-grade and D-grade) and various stages of in vitro-produced embryos (2-cell, 4-cell, 8–16-cell, morula, and blastocyst) of buffalo using RT-qPCR. Results showed that the RA of GLUT1, CX43, HSP70.1 and GDF9 was significantly higher (P < 0.05) in the A-grade of oocytes than the C-grade and D-grade but did not differ significantly from the B-grade of oocytes. Similarly, RA of BMP15 and Survivin were significantly higher (P < 0.05) in A-grade than the other grades of oocytes, however, poly(A) polymerase expression was not significantly different (P > 0.05) among the immature oocytes. The expression of GLUT1 was significantly higher (P < 0.05) in the blastocysts, but the expression of CX43 (P < 0.05; P > 0.05), HSP70.1 (P < 0.05; P > 0.05) and GDF9 (P > 0.05) was higher at the 2-cell stage than the other stages of embryos. Interestingly, the expression levels of poly(A) polymerase (P < 0.05), BMP15 (P < 0.05; P > 0.05) and Survivin (P > 0.05) were higher at the 8–16-cell stage than the other stages of embryos. It is concluded that A-grade of immature oocytes has shown more mRNA abundance for the major developmental important genes; therefore A-grade oocytes may be considered as the most developmentally competent and suitable for handmade cloning research in buffalo.

Expression of the developmental important candidate genes in oocytes, embryos, embryonic stem cells, cumulus cells, and fibroblast cells of buffalo (Bubalus bubalis)

The present study was undertaken to study the expression of the developmental important gene transcripts in immature oocytes, mature oocytes, different stages of IVF produced embryos, embryonic stem (ES), cumulus (BCC), fetal fibroblast (BFF), newborn fibroblast (NBF) and adult fibroblast (BAF) cells of buffalo by semi-quantitative RT-PCR. The expression of GLUT1, HSP70.1, POL A Polymerase, GDF9, BMP15, and SURVIVIN transcripts was found in immature oocytes, mature oocytes, 2-cell, 4-cell, 8-16 cell, morula, and the blastocyst. Interestingly, the CX43 expression was found in oocytes, embryos, and other cell types, but it was not detected in the blastocyst. However, the IFNT expression was found in the blastocyst only, but not in other cells. The buffalo ES cells showed the expression of intracellular and cell surface markers (NANOG, OCT4, SOX2, FOXD3, SSEA-3, SSEA-4, TRA-1-60, and TRA-1-81) and alkaline phosphatase activity. Two ES cell lines (S-line and M-line-II) were continued to survive up to 98th passages (~630 days) and 97th passages (~624 days), respectively. It was interesting to note that GLUT1, CX43, HSP70.1, POL A Polymerase, GDF9, BMP15, and SURVIVIN transcripts (except the IFNT) were expressed in buffalo ES, BCC, BFF, NBF and BAF cells. This is the first preliminary report that the buffalo ES, BCC, BFF, NBF, and BAF cells expressed the several developmental important candidate genes. It is concluded that the expression of the major developmental important genes was not only expressed in the oocytes and embryos but also expressed in the ES, BCC, BFF, NBF, and BAF cells of buffalo.

Relative abundance of pluripotency-associated candidate genes in immature oocytes and in vitro-produced buffalo embryos (Bubalus bubalis)

The present study was undertaken to analyze the relative abundance (RA) of pluripotency-associated genes (NANOG, OCT4, SOX2, c-MYC, and FOXD3) in different grades of immature oocytes and various stages of in vitro-produced buffalo embryos using RT-qPCR. Results showed that the RA of NANOG, OCT4, and FOXD3 transcripts was significantly higher (P < 0.05) in A grade oocytes compared with the other grades of oocytes. The RA of the c-MYC transcript was significantly higher (P < 0.05) in A grade compared with the C and D grades of oocytes, but the values did not differ significantly from the B grade of oocytes. The RA of the SOX2 transcript was almost similar in all grades of the oocytes. The expression levels of NANOG (P > 0.05), OCT4 (P > 0.05), c-MYC (P > 0.05) and SOX2 (P < 0.05) were higher in the blastocysts compared with the other stages of the embryos. Markedly, FOXD3 expression was significantly higher (P < 0.05) in 8-16-cell embryos compared with the 2-cell and 4-cell embryos and blastocyst, but did not differ significantly from the morula stage of the embryos. In the study, the majority of pluripotency-associated genes showed higher expression in A grade immature oocytes. Therefore, it is concluded that the A grade oocytes appeared to be more developmental competent and are suitable candidates for nuclear cloning research in buffalo. In buffalo, NANOG, OCT4, SOX2, and c-MYC are highly expressed in blastocysts compared with the other stages of embryos.

Effect of basic fibroblast growth factor (FGF2) on cumulus cell expansion, in vitro embryo production and gene expression in buffalo (Bubalus bubalis)

The present study was undertaken to evaluate the effect of different concentration of FGF2 viz. 5 ng (T1), 10 ng (T2), and 20 ng/mL (T3) on cumulus cell expansion, oocyte maturation, in vitro embryo production, total cell number (TCN) of the blastocyst, and expression of the FGF2 and FGFR2 transcripts in buffalo oocytes and the embryos. Results showed that the effect of FGF2 on the diameter of buffalo COC was significantly higher (P < 0.05) in the T1 group than the other groups at 24h of maturation. The maturation and cleavage rate of oocytes was significantly higher (P < 0.05) in the T3 group than the control, however, the values did not different (P> 0.05) from other groups. The effect of FGF2 on morula and blastocyst yield did not different (P > 0.05) between treatment groups. However, the TCN of the blastocyst was slightly higher (P > 0.05) in the T3 group than the control and other groups. In subsequent trials, the expression of the FGF2 transcript was higher (P < 0.05) in A-grade of oocytes than the C- and D-grade of oocytes, but the expression was not different (P> 0.05) from the B-grade of oocytes. While the FGFR2 expression was higher (P < 0.05) in cumulus cells than any grades of oocytes. The relative abundance of FGF2 and FGFR2 transcripts was significantly higher (P < 0.05) in the 2-cell stage of the embryo than the other stages of embryos. This study was further extended to characterize the FGF2 ligand-binding site in the D3 domain of the buffalo FGF2 receptor. Bioinformatics analysis showed that the bovine FGF2 ligand-binding site in the D3 domain of buffalo was different from the D3 domain of the cattle.

Semen parameters and fertility potency of a cloned water buffalo (Bubalus bubalis) bull produced from a semen-derived epithelial cell

Semen contains epithelial cells that can be cultured in vitro. For somatic cell nuclear transfer applications, it is essential to know whether clone(s) produced from semen-derived epithelial cells (SedECs) are healthy and reproductively competent. In this study, the semen and fertility profile of a cloned bull (C1) that was produced from a SedEC were compared with its donor (D1) and with two cloned bulls (C2, C3) that were produced from commonly used skin-derived fibroblast cells (SkdFCs). We observed variations in some fresh semen parameters (ejaculated volume and mass motility), frozen-thawed sperm parameters (plasma membrane integrity, and computer-assisted semen analysis (CASA) indices), but values are within the normal expected range. There was no difference in sperm concentration of ejaculated semen and frozen-thawed semen parameters which include sperm motility, percentage of live and normal morphology sperm, and distance traveled through oestrus mucus. Following in vitro fertilization (IVF) experiments, zygotes from C1 had higher (P < 0.05) cleavage rates (81%) than C2, C3, and D1 (71%, 67%, and 75%, respectively); however, blastocyst development per cleaved embryo and quality of produced blastocysts did not differ. The conception rate of C1 was 46% (7/15) and C2 was 50% (8/15) following artificial insemination with frozen-thawed semen. Established pregnancies resulted in births of 7 and 6 progenies sired by C1 and C2, respectively, and all calves show no signs of phenotypical abnormalities. These results showed that semen from a cloned bull derived from SedECs is equivalent to semen from its donor bull and bulls cloned from SkdFCs.

In vitro production of early stage buffalo embryos in modified synthetic oviductal fluid (mSOF) medium

The objective of the present study was to observe the developmental rates and the stage of development since fertilization of in vitro produced early stage buffalo embryos. Buffalo cumulus-oocyte complexes (COC’s) obtained from slaughterhouse ovaries were matured and fertilized in vitro. The fertilized oocytes (400) were then cultured in modified synthetic oviductal fluid (mSOF) medium containing bovine serum albumin (BSA) and fetal bovine serum (FBS) and evaluated for the developmental stages of preimplantation early stage embryos up to morula on 48 h, 72 h, 96 h and 7th day post fertilization. Highest percentage of 8 cell embryos were obtained followed by 16 cell, 2 cell, 4 cell and morula at the end of in vitro culture (IVC). Similarly, the mean embryo percent of 2 cell, 4 cell, 8 cell, 16 cell and morula stage at the end of IVC was 8.20±1.28, 6.50±0.97, 12.19±1.03, 11.83±0.96 and 5.27±0.87. The overall embryos developed at the end of IVC were 43.98±2.11%. The percentage of oocytes which arrested and subsequently degenerated were 56.02% till day 7 post-insemination. It can be concluded that early stage buffalo embryos till morulae can be produced by using modified synthetic oviductal fluid (mSOF) medium as embryo development medium but for further development, the supplementation of different growth factors required.

BAPTA-AM dramatically improves maturation and development of bovine oocytes from grade-3 cumulus-oocyte complexes

Intracellular free calcium ([Ca²⁺ ]_i ) is essential for oocyte maturation and early embryonic development. Here, we investigated the role of [Ca²⁺ ]_i in oocytes from cumulus-oocyte complexes (COCs) with respect to maturation and early embryonic development, using the calcium-buffering agent BAPTA-AM (1,2-bis[2-aminophenoxy]ethane-N,N,N',N'-tetraacetic acid tetrakis [acetoxymethyl ester]). COCs were graded based on compactness of the cumulus mass and appearance of the cytoplasm, with Grade 1 indicating higher quality and developmental potential than Grade 3. Results showed that: (i) [Ca²⁺ ]_i in metaphase-II (MII) oocytes from Grade-3 COCs was significantly higher than those from Grade-1 COCs, and was significantly reduced by BAPTA-AM; (ii) nuclear maturation of oocytes from Grade-3 COCs treated with BAPTA-AM was enhanced compared to untreated COCs; (iii) protein abundance of Cyclin B and oocyte-specific Histone 1 (H1FOO) was improved in MII oocytes from Grade-3 COCs treated with BAPTA-AM; (iv) Ca²⁺ transients were triggered in each group upon fertilization, and the amplitude of [Ca²⁺ ]_i oscillations increased in the Grade-3 group upon treatment with BAPTA-AM, with the magnitude approaching that of the Grade-1 group; and (v) cleavage rates and blastocyst-formation rates were improved in the Grade-3 group treated with BAPTA-AM compared to untreated controls following in vitro fertilization and parthenogenetic activation. Therefore, BAPTA-AM dramatically improved oocyte maturation, oocyte quality, and embryonic development of oocytes from Grade-3 COCs.

Sperm preparation through Sephadex™ filtration improves in vitro fertilization rate of buffalo oocytes

Routinely, swim-up method is used to separate high-quality sperm; however, long processing time and close cell-to-cell contact during the centrifugation step are inevitable elements of oxidative stress to sperm. The objective was to evaluate Sephadex^™ and glass wool filtration to separate motile, intact and viable sperm for in vitro fertilization in buffalo. The cumulus-oocyte complexes (COCs) were collected from ovaries of slaughtered buffaloes by aspiration and matured for 24 hr in CO₂ incubator at 38.5°C and 5% CO₂ . Matured COCs were rinsed twice in fertilization TALP and placed in the pre-warmed fertilization medium without sperm. Cryopreserved buffalo semen was thawed at 37°C for 30 s and processed through Sephadex^™ , glass wool filtration and swim-up (control). Total and motile sperm recovery rates were assessed, resuspended in fertilization TALP and incubated for 15-20 min in CO₂ incubator. Samples prepared by each method were divided into two aliquots: one aliquot was studied for sperm quality (progressive motility, membrane integrity, viability, liveability), while the other was subjected to co-incubation with sets of 10-15 in vitro matured oocytes. Data on sperm quality were analysed by ANOVA, while in vitro fertilizing rates were compared by chi-squared test using SPSS-20. Least significant difference (LSD) test was used to compare treatment means. Glass wool filtration yielded higher total and motile sperm recovery rate, while Sephadex^™ filtration improved (p < .05) sperm quality (progressive motility, membrane integrity, viability, liveability). Sperm preparation through Sephadex filtration yielded higher in vitro fertilization rate in terms of cleavage rate compared to glass wool filtration and swim-up (control). In conclusion, cryopreserved Nili-Ravi buffalo sperm selected through Sephadex filtration showed improved quality and yielded better fertilization rates (cleavage rate) of in vitro matured/fertilized oocytes. Sephadex filtration could be a promising technique for use in in vitro fertilization in buffalo.

Melatonin Improves the Quality of Inferior Bovine Oocytes and Promoted Their Subsequent IVF Embryo Development: Mechanisms and Results

The inferior oocytes (IOs), which are not suitable for embryo development, occupy roughly one-third or more of the collected immature bovine oocytes. The IOs are usually discarded from the in vitro bovine embryo production process. Improving the quality of the inferior oocytes (IOs) and make them available in in vitro embryo production would have important biological, as well as commercial, value. This study was designed to investigate whether melatonin could improve the quality of IOs and make them usable in the in vitro maturation (IVM) and subsequent (in vitro fertilization) IVF embryo development. The results indicated that: the maturation rate of IOs and their subsequent IVF embryo developments were impaired compared to cumulus-oocyte complexes and melatonin treatment significantly improved the quality of IOs, as well as their IVF and embryo developments. The potential mechanisms are that: (1) melatonin reduced reactive oxygen species (ROS) and enhanced glutathione (GSH) levels in the IOs, thereby protecting them from oxidative stress; (2) melatonin improved mitochondrial normal distribution and function to increase ATP level in IOs; and (3) melatonin upregulated the expression of ATPase 6, BMP-15, GDF-9, SOD-1, Gpx-4, and Bcl-2, which are critical genes for oocyte maturation and embryo development and downregulated apoptotic gene expression of caspase-3.

Effect of recombinant and native buffalo OVGP1 on sperm functions and in vitro embryo development: a comparative study

Background

An oviduct- specific glycoprotein, OVGP1, is synthesized and secreted by non-ciliated epithelial cells of the mammalian oviduct which provides an essential milieu for reproductive functions. The present study reports the effects of recombinant buffalo OVGP1 that lacks post-translational modifications, and native Buffalo OVGP1 isolated from oviductal tissue, on frozen- thawed sperm functions and in vitro embryo development.

Results

The proportion of viable sperms was greater (P < 0.05) in the recombinant OVGP1-treated group compared to the native OVGP1-treated group at 2 h, 3 h, and 4 h of incubation. The proportion of motile sperms at 3 h and 4 h of incubation; and membrane- intact sperms at 4 h was greater (P < 0.05) in the native OVGP1-treated group compared to the control and recombinant OVGP1-treated groups. The proportion of capacitated and acrosome- reacted sperms was greater (P < 0.05) in the native OVGP1-treated group compared to the recombinant OVGP1 group at 4 h. The rates of cleavage of embryos and their development to the blastocyst stage were greater (P < 0.05) in the presence of either native or recombinant OVGP1 in comparison to control at 10 μg/mL concentration as compared to 5 or 20 μg/mL.

Conclusions

The study suggests that both native and recombinant OVGP1 impart a positive effect on various sperm features and in vitro embryo development. However, native OVGP1 was found to have a more pronounced effect in comparison to recombinant non-glycosylated OVGP1 on various sperm functions except viability. Hence, our current findings infer that glycosylation of OVGP1 might be essential in sustaining the sperm functions but not the in vitro embryo development.

Electronic supplementary material

The online version of this article (doi:10.1186/s40104-017-0201-5) contains supplementary material, which is available to authorized users.

Ovum pick-up interval in buffalo (Bubalus bubalis) managed under wetland conditions in Argentina: Effect on follicular population, oocyte recovery, and in vitro embryo development

The excellent adaptation of water buffalo (Bubalis bubalis) to swampy environments means that animals are frequently managed in areas with restricted access for reproductive procedures. The objective of this study was to evaluate the effect of the ovum pick-up (OPU) interval on follicular population, oocyte recovery, oocyte quality and in vitro embryo production. Twelve Murrah buffaloes were subjected to two consecutive dominant follicle reductions, and randomly assigned to either 7-day (n=6) or 14-day (n=6) OPU interval groups. Although there was no significant difference in the average number of small (<3mm) and large (>8mm) diameter follicles available per OPU, a higher proportion of medium-sized follicles (3-8mm) were observed in the 14-day interval group (5.129 vs 3.267; p<0.05). The number of recovered oocytes per donor was also significantly higher (4.51 vs. 2.8; p<0.05) in the 14-day interval group, although this was attributed to an increase in the proportion of lower quality oocytes (grades III and IV). After in vitro fertilization, embryo developmental competence from grade I and II oocytes was superior to that from grade III and IV oocytes, irrespective of OPU interval group. There was no significant difference in the proportion of grade I and II oocytes cleaved after sperm co-incubation; however, there was a higher proportion of blastocysts produced in 14-day interval group (28 vs. 6%, p<0.05). No blastocysts were produced from grade III and IV oocytes. This study indicates it is possible to use a 14-day interval for oocyte collection in water buffalo; this approach could be considered as an alternative when access to animals is restricted.

Effect of testicular tissue lysate on developmental competence of porcine oocytes matured and fertilized in vitro

The objective of the present study was to investigate the effect of testicular tissue lysate (TTL) on developmental competence of germinal vesicle (GV) stage porcine oocytes. Two types of TTL were prepared through repeated freeze-thaw in liquid nitrogen, one from whole testicular tissue (wTTL) and other from either of four different sections of testes, namely just beneath the tunica albuginea (TA), from the transitional area between the seminiferous cord/tubules and the mediastinum testis (TR) and from the intermediate area (parenchymal tissue origin) and CE (cauda epididymis origin). The whole or section-wise TTL treatments were given for 44 hr during in vitro maturation (IVM). Oocyte maturation was done in either of the two media, namely defined (high-performance basic medium for porcine oocyte maturation, commercially available) and serum containing (TCM199). After maturation, oocytes were co-incubated with fresh spermatozoa for 6 hr and then transferred to embryo culture media. Treatment of GV stage oocytes with wTTL (1 mg/ml) increased the cleavage and morula percentage rate (69.23 ± 6.23 and 48.15 ± 6.77, respectively) than that of their control (58.33 ± 8.08 and 32.54 ± 5.53, respectively) in defined media, and in serum-containing media, cleavage and morula percentage rate were almost equal in both treatment (54.56 ± 7.79 and 34.70 ± 6.78, respectively) and control (59.52 ± 8.21 and 38.52 ± 6.54, respectively). However, effect of wTTL was not significant. In case of section-wise TTL supplements, TR section significantly (p < .01) improved cleavage and morula rate (58.43 ± 7.98 and 36.14 ± 6.89, respectively) followed by TA. In conclusion, present study indicates that IVM, in vitro fertilization and in vitro culture of embryo are improved in the presence of TTL, particularly its TR section. Further study is expected to reveal the principal components of TTL which may prove useful for IVM.

Differences in developmental competence and gene expression profiles between buffalo (Bubalus bubalis) preimplantation embryos cultured in three different embryo culture media

The objective of this study was to compare effects of in vitro culture systems on embryonic development and expression patterns of developmentally important genes in preimplantation buffalo embryos. After IVM/IVF presumptive zygotes were cultured in one of three systems: undefined TCM-199, mCR2aa medium supplemented with 10 % FBS and defined PVA-myo-inositol-phosphate-EGF medium. No (P > 0.05) differences at 2-cell, 4-cell and 8-cell to 16- cell stages were observed among the three cultured media used, however, increased (P < 0.05) blastocyst yield, cell number and hatching rate were found in defined medium compared to undefined media. The expression patterns of genes implicated in embryo metabolism (GLUT-1), anti-apoptosis (BCL-2), imprinting (IGF-2R), DNA methylation (DNMT-3A) and maternal recognition of pregnancy (IFNT) were increased (P < 0.05) in hatched blastocysts derived from defined medium compared to undefined media. In conclusion, serum-free, defined medium improved developmental competence of in vitro cultured buffalo embryos. Whether these differences in morphological development and gene expression have long-term effects on buffalo calves born after embryo transfer remains unknown. However, it is possible that early adaptations of the preimplantation embryo to its environment persist during fetal and post-natal development.

Molecular characterization of IFN-T expressed in buffalo embryonic trophoblasts and expression of recombinant BuIFN-T1a2 and BuIFN-T8 isoforms in E. coli

Interferon tau (IFN-T) acts as a signaling molecule for maternal recognition of pregnancy (MRP) in ruminants. Aim of the present study was to identify various Buffalo Interferon tau (BuIFN-T) transcripts in buffalo trophoblast, phylogenetic comparison of these sequences with known mRNA sequences of buffalo, bovine, caprine and ovine and to express and purify the recombinant BuIFN-T (rBuIFN-T) isoforms. Following RNA extraction from trophectodermal cells, RT-PCR was performed using Ifn-t gene specific primers. 13 distinct cDNA variants encoding eight different BuIFN-T proteins were identified. BuIFN-T1a2 and BuIFN-T8 were expressed in prokaryotic expression system at 37 °C, 25 °C and 16 °C with 1 mM IPTG for 12 h and the recombinant proteins expressed at 16 °C were partially purified by Immobilised Metal Affinity Chromatography (IMAC). BuIFN-T isoforms have greater nucleotide and amino acid homology with caprine (98-100%, 96-100%), ovine (94-97%, 90-95%) and bovine (89.6-90.6%, 82-86%). These novel BuIFN-T isoforms contained pronounced nucleotide and amino acid sequence identity with one another (99.1-99.8%, 98-99%) but moderate sequence identity with previously identified buffalo IFN-T (90-92%, 82-86%). Solubility of expressed recombinant isoforms (rBuIFN-T1a2 and rBuIFN-T8) was highest at 16 °C. In conclusion, 13 distinct Ifn-t gene variants exist in trophectoderm of in vitro developed buffalo blastocysts that encode eight different proteins. rBuIFN-T1a2 and rBuIFN-T8 were successfully expressed in soluble form in Escherichia coli expression system at 16 °C with 1 mM IPTG and the resulting recombinant proteins were partially purified by IMAC.

Activation and Inhibition of The Wnt3A Signaling Pathway in Buffalo (Bubalus bubalis) Embryonic Stem Cells: Effects of WNT3A, Bio and Dkk1

BACKGROUND

This research studies the effects of activation and inhibition of Wnt3A signaling pathway in buffalo (Bubalus bubalis) embryonic stem (ES) cell-like cells.

MATERIALS AND METHODS

To carry on this experimental study, the effects of activation and inhibition of Wnt3A signaling in buffalo ES cell-like cells were examined using Bio (0.5 mM) combined with WNT3A (200 ng/ml), as an activator, and Dickkopf-1 (Dkk1, 250 ng/ml), as an inhibitor, of the pathway. ES cells were cultured up to three weeks in ES cell medium without fibroblast growth factor-2 (FGF-2) and leukemia inhibitory factor (LIF), but in the presence of Bio, WNT3A, Bio+WNT3A and Dkk1. The effects of these supplements were measured on the mean area of ES cell colonies and on the expression levels of a number of important genes related to pluripotency (Oct4, Nanog, Sox2 and c-Myc) and the Wnt pathway (β-catenin). ES cell colonies cultured in ES cell medium that contained optimized quantities of LIF and FGF-2 were used as the control. Data were collected for week-1 and week-3 treated cultures. In addition, WNT3A-transfected ES cells were compared with the respective mock-transfected colonies, either alone or in combination with Dkk1 for expression of β-catenin and the pluripotency-related genes. Data were analyzed by ANOVA, and statistical significance was accepted at P<0.05.

RESULTS

Among various examined concentrations of Bio (0.5-5 mM), the optimum effect was observed at the 0.5 mM dose as indicated by colony area and expressions of pluripotency-related genes at both weeks-1 and -3 culture periods. At this concentration,the expressions of Nanog, Oct3/4, Sox2, c-Myc and β-catenin genes were nonsignificantly higher compared to the controls. Expressions of these genes were highest in the Bio+WNT3A treated group, followed by the WNT3A and Bio-supplemented groups, and lowest in the Dkk1-treated group. The WNT-transfected colonies showed higher expressions compared to both mock and Dkk1-treated mock transfected colonies.

CONCLUSION

WNT3A functions to maintain the pluripotency of ES cell-like cells both as an exogenous growth factor as well as an endogenously expressed gene. It complements the absence of FGF-2 and LIF, otherwise propounded essential for buffalo ES cell culture. WNT3A antagonizes the inhibitory effects of Dkk1 and acts in combination with its activator, Bio, to activate the Wnt signaling pathway.

Caspase-9 inhibitor Z-LEHD-FMK enhances the yield of in vitro produced buffalo (Bubalus bubalis) pre-implantation embryos and alters cellular stress response

The present investigation was done to study the effect of caspase-9 inhibitor Z-LEHD-FMK, on in vitro produced buffalo embryos. Z-LEHD-FMK is a cell-permeable, competitive and irreversible inhibitor of enzyme caspase-9, which helps in cell survival. Buffalo ovaries were collected from slaughterhouse and the oocytes were subjected to in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC). The culture medium was supplemented with Z-LEHD-FMK at different concentrations i.e. 0 μM (control), 10 μM, 20 μM, 30 μM and 50 μM during IVM and IVC respectively. After day-2 post-insemination, the cleavage rate was significantly higher (74.20 ± 5.87% at P<0.05) in the group treated with 20 μM of Z-LEHD-FMK than at any other concentration. Same trend was observed in the blastocyst production rate which was higher at 20 μM (27.42 ± 2.94% at P<0.05). The blastocysts obtained at day-8 of the culture at different concentrations were subjected to TUNEL assay, to determine the level of apoptosis during the culture medium supplied with 20 μM Z-LEHD-FMK which showed apoptotic index significantly lower (1.88 ± 0.87 at P<0.05). There was a non-significant increase in total cell number in all Z-LEHD-FMK treated blastocysts. The quantitative gene expression of CHOP and HSP10 genes showed significant increase (P<0.05) in the group treated with 50 μM Z-LEHD-FMK, while, HSP40 showed significant increase (P<0.05) at 30 μM and 50 μM Z-LEHD-FMK concentrations. From the afore mentioned results we conclude that, Z-LEHD-FMK at 20 μM increased the cleavage and blastocyst rate of buffalo pre-implantation embryos also affecting the rate of apoptosis and cellular stress at various concentrations.

Optimization of Buffalo (Bubalus bubalis) Embryonic Stem Cell Culture System

OBJECTIVE

In order to retain an undifferentiated pluripotent state, embryonic stem (ES) cells have to be cultured on feeder cell layers. However, use of feeder layers limits stem cell research, since experimental data may result from a combined ES cell and feeder cell response to various stimuli.

MATERIALS AND METHODS

In this experimental study, a buffalo ES cell line was established from in vitro derived blastocysts and characterized by the Alkaline phosphatase (AP) and immunoflourescence staining of various pluripotency markers. We examined the effect of various factors like fibroblast growth factor 2 (FGF-2), leukemia inhibitory factor (LIF) and Y-27632 to support the growth and maintenance of bubaline ES cells on gelatin coated dishes, in order to establish feeder free culture systems. We also analyzed the effect of feeder-conditioned media on stem cell growth in gelatin based cultures both in the presence as well as in the absence of the growth factors.

RESULTS

The results showed that Y-27632, in the presence of FGF-2 and LIF, resulted in higher colony growth and increased expression of Nanog gene. Feeder-Conditioned Medium resulted in a significant increase in growth of buffalo ES cells on gelatin coated plates, however, feeder layer based cultures produced better results than gelatin based cultures. Feeder layers from buffalo fetal fibroblast cells can support buffalo ES cells for more than two years.

CONCLUSION

We developed a feeder free culture system that can maintain buffalo ES cells in the short term, as well as feeder layer based culture that can support the long term maintenance of buffalo ES cells.

WNT3A signalling pathway in buffalo (Bubalus bubalis) embryonic stem cells

The aim of this study was to investigate the transcriptional profile and role of WNT3A signalling in maintaining buffalo embryonic stem (ES) cells in a pluripotent state and in the induction of their differentiation. ES cells were derived from embryos produced by in vitro fertilisation (iESC), parthenogenesis (pESC) and hand-made cloning (cESC). The expression of WNT3A, its receptors and intermediate signalling pathways were found to be conserved in ES cells derived from the three different sources. WNT3A was expressed in ES cells but not in embryoid bodies derived from iESC or in buffalo fetal fibroblast cells. It was revealed by real-time polymerase chain reaction analysis that following supplementation of culture medium with WNT3A (100, 200 or 400ngmL(-1)) a significant increase (P<0.05) was observed in the expression level of β-CATENIN, which indicated the activation of the canonical WNT pathway. WNT3A, in combination with exogenous fibroblast growth factor-2 and leukaemia inhibitory factor, induced proliferation of undifferentiated ES cells. Differentiation studies showed that WNT3A caused formation of scaffold-like structures and inhibition of differentiation into neuron-like cells. In conclusion, the WNT3A signalling pathway is necessary both for maintaining undifferentiated buffalo ES cells as well as for directing their differentiation.

Developmental competence and expression pattern of bubaline (Bubalus bubalis) oocytes subjected to elevated temperatures during meiotic maturation in vitro

OBJECTIVE

To determine the direct effect of physiologically relevant high temperatures (40.5 and 41.5 °C) for two time periods (12 and 24 h) on bubaline oocytes during in vitro maturation.

METHOD

The control group oocytes were cultured at 38.5 °C for 24 h. The treatment 1 (T1) and 3 (T3) group oocytes were cultured at 40.5 and 41.5 °C respectively, for the first 12 h and at 38.5 °C for rest of the 12 h. However, treatment 2 (T2) and 4 (T4) group oocytes were cultured at 40.5 and 41.5 °C for complete 24 h.

RESULTS

Development of oocytes to blastocyst was severely compromised (p < 0.001) when matured at 40.5 and 41.5 °C for both exposure periods (12 h and 24 h). It was found that the cleavage rates, blastocyst yield and mean cell number decreased remarkably (p < 0.001) in the treatment groups compared to control. The relative mRNA expression of heat shock protein (Hsp 70.1, 70.2, 70.8, 60, 10 and HSF1), pro-apoptotic (caspases-3, -7, -8, Bid and Bax) and oxidative stress (iNOS) related genes was significantly higher (p < 0.05) in all the treatment groups compared to control. However, mRNA abundance of anti-apoptotic (Bcl-2, Mcl-1, Bcl-xl), glucose transport (Glut1, Glut3 and IGF1R), developmental competence (ZAR1 and BMP15) and oxidative stress (MnSOD) related genes was significantly decreased (p < 0.05) in the treatment groups compared to control.

CONCLUSION

The present study clearly establishes that physiologically relevant elevated temperatures during in vitro meiotic maturation reduce developmental competence of bubaline oocytes.

Expression pattern of pluripotent markers in different embryonic developmental stages of buffalo (Bubalus bubalis) embryos and putative embryonic stem cells generated by parthenogenetic activation

In this study, we describe the production of buffalo parthenogenetic blastocysts and subsequent isolation of parthenogenetic embryonic stem cell (PGESC)-like cells. PGESC colonies exhibited dome-shaped morphology and were clearly distinguishable from the feeder layer cells. Different stages of development of parthenogenetic embryos and derived embryonic stem cell (ESC)-like cells expressed key ESC-specific markers, including OCT-4, NANOG, SOX-2, FOXD3, REX-1, STAT-3, TELOMERASE, NUCLEOSTEMIN, and cMYC. Immunofluorescence-based studies revealed that the PGESCs were positive for surface-based pluripotent markers, viz., SSEA-3, SSEA-4, TRA 1-80, TRA 1-60, CD-9, and CD-90 and exhibited high alkaline phosphatase (ALP) activity. PGEC cell-like cells formed embryoid body (EB)-like structures in hanging drop cultures and when cultured for extended period of time spontaneously differentiated into derivatives of three embryonic germ layers as confirmed by RT-PCR for ectodermal (CYTOKERATIN8, NF-68), mesodermal (MSX1, BMP-4, ASA), and endodermal markers (AFP, HNF-4, GATA-4). Differentiation of PGESCs toward the neuronal lineage was successfully directed by supplementation of serum-containing media with retinoic acid. Our results indicate that the isolated ESC-like cells from parthenogenetic blastocyst hold properties of ESCs and express markers of pluripotency. The pluripotency markers were also expressed by early cleavage-stage of buffalo embryos.

Effect of physiologically relevant heat shock on development, apoptosis and expression of some genes in buffalo (Bubalus bubalis) embryos produced in vitro

For investigating the effects of physiologically relevant heat shock, buffalo oocytes/embryos were cultured at 38.5°C (control) or were exposed to 39.5°C (Group II) or 40.5°C (Group III) for 2 h once every day throughout in vitro maturation (IVM), fertilization (IVF) and culture (IVC). Percentage of oocytes that developed to 8-cell, 16-cell or blastocyst stage was lower (p < 0.05) and the number of apoptotic nuclei was higher (p < 0.05) for Group III > Group II > controls. At both 8-16-cell and blastocyst stages, relative mRNA abundance of stress-related genes HSP 70.1 and HSP 70.2 and pro-apoptotic genes CASPASE-3, BID and BAX was higher (p < 0.05) in Groups III and II than that in controls with the exception of stress-related gene HSF1. Expression level of anti-apoptotic genes BCL-XL and MCL-1 was also higher (p < 0.05) in Groups III and II than that in controls at both 8-16-cell and blastocyst stages. Among the genes related to embryonic development, at 8-16-cell stage, the expression level of GDF9 was higher (p < 0.05) in Group III than that in controls, whereas that of GLUT1, ZAR1 and BMP15 was not significantly different among the three groups. At the blastocyst stage, relative mRNA abundance of GLUT1 and GDF9 was higher (p < 0.05) in Group II than that in controls, whereas that of ZAR-1 and BMP15 was not affected. The results of this study demonstrate that exposure of buffalo oocytes and embryos to elevated temperatures for duration of time that is physiologically relevant severely compromises their developmental competence, increases apoptosis and affects stress-, apoptosis- and development-related genes.

Kinetics of GDF9 expression in buffalo oocytes during in vitro maturation and their associated development ability

The capacity of fully grown oocytes to regulate their own microenvironment by secreted paracrine factors contribute to their developmental competence. In spite of growing evidence about the vital role of Growth Differentiation Factor 9 (GDF9) in determination of oocyte developmental competence, there is insufficient information about time dependent behavior of its expression during in vitro maturation (IVM) to have definite understanding about at what time point during IVM it plays most crucial role. The study reports the kinetics of GDF9 expression under four different IVM supplement conditions in buffalo oocytes and their concomitant development rate up to blastocyst. Oocytes matured under an ideal media condition with all supplements and those cultured with only FSH resulted in significantly higher cumulus expansion, nuclear maturation, cleavage and blastocyst rates. GDF9 expression at both mRNA and protein levels at different time points of IVM revealed that magnitude of mRNA abundance at 8h of IVM was most important towards imparting development competence to buffalo oocytes. Appearance of GDF9 protein in maturing oocytes was found asynchronous with mRNA appearance in the time course of IVM suggesting possible posttranscriptional regulation of this gene under dynamic oocyte cumulus cell communication process. Abundance of mature GDF9 protein at 16 h was most consistently related with all oocyte development parameters.

Equivalency of buffalo (Bubalus bubalis) embryonic stem cells derived from fertilized, parthenogenetic, and hand-made cloned embryos

This study was aimed at establishing buffalo embryonic stem cells (ESCs) from in vitro fertilized (IVF), parthenogenetic, and hand-made cloned (HMC) embryos and to check their equivalency in terms of stem cell marker expression, longevity, proliferation, and differentiation pattern. ESCs derived from all three sources were found by immunofluorescence to express the pluripotency markers SSEA-4, TRA-1-60, TRA-1-81, OCT4, and SOX2 and were able to form embryoid bodies containing cells expressing genes specific to endoderm (AFP, HNF4, and GATA4), mesoderm (MSX1, BMP4, and ASA), and ectoderm (cytokeratin 8 and NF68). Reverse transcriptase PCR (RT-PCR) showed cells from all sources to be positive for pluripotency markers OCT4, SOX2, NANOG, STAT3, REX1, FOXD3, NUCLEOSTEMIN, and TELOMERASE. Pluripotency markers OCT4, SOX2, NANOG, and c-MYC were also analyzed by real-time PCR. No significant differences were observed among ESCs from all three sources for all these genes except NANOG, whose expression was higher (p<0.05) in HMC-derived ESCs (6.897±2.3) compared to that in parthenogenesis- and IVF-derived cells (1.603±0.315 and 1±0, respectively). Pluripotent, stable buffalo ESC lines derived from IVF, parthenogenesis, and HMC embryos may be genetically manipulated to provide a powerful tool for studies involving embryonic development, genomic imprinting, gene targeting, cloning, chimera formation, and transgenic animal production.

Optimization of culture conditions to support long-term self-renewal of buffalo (Bubalus bubalis) embryonic stem cell-like cells

A culture system capable of sustaining self-renewal of buffalo embryonic stem (ES) cell-like cells in an undifferentiated state over a long period of time was developed. Inner cell masses were seeded on KO-DMEM+15% KO-serum replacer on buffalo fetal fibroblast feeder layer. Supplementation of culture medium with 5 ng/mL FGF-2 and 1000 IU/mL mLIF gave the highest (p<0.05) rate of primary colony formation. The ES cell-like cells' colony survival rate and increase in colony size were highest (p<0.05) following supplementation with FGF-2 and LIF compared to other groups examined. FGF-2 supplementation affected the quantitative expression of NANOG, SOX-2, ACTIVIN A, BMP 4, and TGFβ1, but not OCT4 and GREMLIN. Supplementation with SU5402, an FGFR inhibitor (≥20 μM) increased (p<0.05) the percentage of colonies that differentiated. FGFR1-3 and ERK1, K-RAS, E-RAS, and SHP-2, key signaling intermediates of FGF signaling, were detected in ES cell-like cells. Under culture conditions described, three ES cell lines were derived that, to date, have been maintained for 135, 95, and 85 passages for over 27, 19, and 17 months, respectively, whereas under other conditions examined, ES cell-like cells did not survive beyond passage 10. The ES cell-like cells were regularly monitored for expression of pluripotency markers and their potency to form embryoid bodies.

Effect of cytoplasmic volume on developmental competence of buffalo (Bubalus bubalis) embryos produced through hand-made cloning

This study examined the effects of cytoplasmic volume on the developmental competence of hand-made cloned buffalo embryos. Two different cell types, that is, buffalo fetal fibroblast (BFF) and buffalo embryonic stem (ES) cell-like cells were taken as donor cell and fused with one, two, or three demicytoplasts to generate embryos with decreased, normal (control), and increased cytoplasmic volume. Using BFF as a nuclear donor, the cleavage rate was similar in all the groups (p > 0.05), but the blastocysts rate was significantly lower (p < 0.05) for embryos generated with decreased cytoplasmic volume. Using ES cell-like cells, the cleavage and blastocyst rate with increased cytoplasmic volume was significantly higher (p < 0.05) compared that with reduced cytoplasmic volume. Blastocysts produced from embryos having increased cytoplasmic volume had significantly higher (p < 0.05) cell number than normal (control) embryos in both BFF and ES cell-like cells groups. Pregnancies were established in all the groups except for the embryos reconstructed with decreased cytoplasmic volume. The pregnancy rate was almost double for embryos reconstructed using increased cytoplasmic volume compared to that with the controls. Most of the pregnancies aborted in the first trimester and one live calf was delivered through Caesarean, which died 4 h after birth.

Production of cloned and transgenic embryos using buffalo (Bubalus bubalis) embryonic stem cell-like cells isolated from in vitro fertilized and cloned blastocysts

Here, we report the isolation and characterization of embryonic stem (ES) cell-like cells from cloned blastocysts, generated using fibroblasts derived from an adult buffalo (BAF). These nuclear transfer embryonic stem cell-like cells (NT-ES) grew in well-defined and dome-shaped colonies. The expression pattern of pluripotency marker genes was similar in both NT-ES and in vitro fertilization (IVF) embryo-derived embryonic stem cell-like cells (F-ES). Upon spontaneous differentiation via embryoid body formation, cells of different morphology were observed, among which predominant were endodermal-like and epithelial-like cell types. The ES cell-like cells could be passaged only mechanically and did not form colonies when plated as single cell suspension at different concentrations. When F-ES cell-like, NT-ES cell-like, and BAF cells of same genotype were used for hand-made cloning (HMC), no significant difference (p > 0.05) was observed in cleavage and blastocyst rate. Following transfer of HMC embryos to synchronized recipients, pregnancies were established only with F-ES cell-like and BAF cell-derived embryos, and one live calf was born from F-ES cell-like cells. Further, when transfected NT-ES cell-like cells and BAF were used for HMC, no significant difference (p > 0.05) was observed between cleavage and blastocyst rate. In conclusion, here we report for the first time the derivation of ES cell-like cells from an adult buffalo, and its genetic modification. We also report the birth of a live cloned calf from buffalo ES cell-like cells.

Buffalo (Bubalus bubalis) embryonic stem cell-like cells and preimplantation embryos exhibit comparable expression of pluripotency-related antigens

In this study, inner cell mass (ICM) cells were isolated from in vitro produced buffalo blastocysts and were cultured on mitomycin-C treated buffalo foetal fibroblast feeder layer for producing embryonic stem (ES) cells. Among different sources (hatched vs expanded blastocysts) or methods (enzymatic vs mechanical), mechanical isolation of ICM from hatched blastocysts resulted in the highest primary colony formation rate and the maximum passage number up to which ES cells survived. Putative ES cells expressed alkaline phosphatase and exhibited a normal karyotype up to passage 7. Putative ES cells and embryos at 2- to 4-cell, 8- to 16-cell, morula and blastocyst stages strongly expressed stage-specific embryonic antigen (SSEA)-4 but lacked expressions of SSEA-1 and SSEA-3. Putative ES cells also expressed tumour rejection antigen (TRA)-1-60, TRA-1-81 and Oct4. Whereas in all early embryonic stages, TRA-1-60 was observed only in the periplasmic space, and TRA-1-81 expression was observed as small spots at a few places inside the embryos, both these markers were expressed by ICM. Oct4 expression, which was observed at all the embryonic stages and also in the trophectoderm, was the strongest in the ICM. Buffalo putative ES cells possess a unique pluripotency-related surface antigen phenotype, which resembles that of the ICM.

Factors affecting laboratory production of buffalo embryos: a meta-analysis

In vitro fertilization (IVF) provides an excellent and inexpensive source of embryos for carrying out basic research on developmental physiology, farm animal breeding, and for commercial applications. Meta-analysis of the results from different publications rather than a narrative review may provide a current status of this technology in buffalo (Bubalus bubalis). In order to gain an idea of the factors affecting the IVF in buffalo, a review of the various studies conducted on buffalo IVF and a meta-analysis of their findings was undertaken. More than 100 articles published from 1991 to 2008 were searched, and results were subjected to meta-analysis to determine the treatment variations without any bias. Thirty factors affecting in vitro embryo production in buffalo were considered. Initially, both fixed- and random-effect models were used. We did not observe any heterogeneity between the studies. Thereafter, all the studies were pooled using the fixed-effect model for analysis. Our analysis suggested that good buffalo oocytes with more than three to five cumulus layers recovered from large-sized follicles in cold seasons when cultured in TCM-199 supplemented with serum, follicle-stimulating hormone, and cysteamine resulted in maximum maturation rate and subsequent embryonic development after insemination. The values obtained in the current study may be considered for a simulation model in establishing a cost-effective suitable method for buffalo IVF in further planned research.

Some studies on the morphological aspects of buffalo oocytes in relation to the ovarian morphology and culture condition

The present study was conducted to establish the effects of ovarian morphology on oocyte quantity and quality, as well as the effect of preincubated granulosa cells (PGCs) on in vitro maturation of buffalo oocytes and steroid hormones production. A total of 52 ovarian pairs were grouped into three types: type I (with functional corpus luteum), type II (with regressed corpus luteum), and type III (without corpus luteum). The number of follicles and oocytes/ovary were documented. The follicles were classified into three groups (<2, 2-6, and >6 mm Ø). Oocytes were classified according to their morphology into four grades (grades A, B, C, and D), or according to their cumulus compactness into four groups (more than three layers, one to three layers of cumulus cells, partial remnants of cumulus cells, and no cumulus cells). A PGCs was used to investigate their steroidogenic potential on the in vitro maturation. The highest number of follicles and oocytes was found in type III than types II and I. Grades A and B oocytes were significantly higher (P < 0.01) in number in type III ovaries. Oocytes with more than three layers of cumulus cells showed higher maturation rate than oocytes with partial remnants or no cumulus cells but with small difference from oocytes having one to three layers of cumulus cells. Beside the higher maturation rate in compact than denuded oocytes, a significantly higher (P < 0.01) rates obtained in compact or denuded oocytes when cultured in vitro with PGCs than the corresponding oocytes with no PGCs. These maturation rates coincided with higher level (P < 0.05) of estradiol-17ss when compact oocytes cultured with or without PGCs than denuded oocytes and higher level (P < 0.05) of progesterone after culture with PGCs for both compact and denuded oocytes than the corresponding oocytes with no PGCs. In summary, buffalo ovaries with no corpus luteum may be suggested for obtaining high number of follicles and good oocytes than the others. Oocytes with intact cumulus showed better maturation than those with partial or denuded cumulus, although the denuded oocytes improved their meiotic competence to a less or greater extent when cultured in vitro with PGCs.

Reproductive biotechniques in buffaloes (Bubalus bubalis): status, prospects and challenges

The swamp buffalo holds tremendous potential in the livestock sector in Asian and Mediterranean countries. Current needs are the faster multiplication of superior genotypes and the conservation of endangered buffalo breeds. Recent advances in assisted reproductive technologies, including in vitro embryo production methodologies, offer enormous opportunities to not only improve productivity, but also to use buffaloes to produce novel products for applications to human health and nutrition. The use of molecular genomics will undoubtedly advance these technologies for their large-scale application and resolve the key problems currently associated with advanced reproductive techniques, such as animal cloning, stem cell technology and transgenesis. Preliminary success in the application of modern reproductive technologies warrants further research at the cellular and molecular levels before their commercial exploitation in buffalo breeding programmes.

Effect of type of cryoprotectant on morphology and developmental competence of in vitro-matured buffalo (Bubalus bubalis) oocytes subjected to slow freezing or vitrification

The present study examined the effects of different cryoprotectants on morphology and developmental competence of in vitro-matured buffalo oocytes after slow freezing or vitrification. After slow freezing in dimethyl sulfoxide (DMSO), ethylene glycol (EG) or 1,2-propanediol (PROH), at 1.0 or 1.5 m each, the proportion of morphologically normal oocytes recovered was significantly higher (P < 0.05) with 1.5 than 1.0 m for all cryoprotectants and was highest (P < 0.05) for 1.5 m DMSO. Following vitrification, the percentage of morphologically normal oocytes recovered was lower (P < 0.01) for 40% EG than for 40% DMSO, 20% EG + 20% DMSO or 20% EG + 20% PROH. The most common damage, irrespective of the cryopreservation method, was loss of cumulus mass. The cleavage rate and the proportion of vitrified-warmed oocytes that developed to morulae/blastocysts were significantly higher (P < 0.01) for 20% EG + 20% DMSO than for the other groups. A higher proportion of oocytes developed to morulae (11.5% v. 4.3%) or blastocysts (5.4% v. 0.6%) after vitrification in 20% EG + 20% DMSO than after slow freezing in 1.5 m DMSO. In conclusion, vitrification was more effective than slow freezing for the cryopreservation of in vitro-matured buffalo oocytes.

Cysteamine supplementation of in vitro maturation medium, in vitro culture medium or both media promotes in vitro development of buffalo (Bubalus bubalis) embryos

The effects of supplementation of in vitro maturation (IVM) or in vitro culture (IVC) or both IVM and IVC media with cysteamine on the yield, hatching rate (HR) and total cell number (TCN) of buffalo blastocysts were examined. Oocytes obtained from slaughterhouse buffalo ovaries were subjected to IVM and IVF. The IVM or IVC media were supplemented with 0, 50, 100 or 200 microm cysteamine. Supplementation of IVM medium with 50 microm cysteamine increased (P < 0.01) the cleavage rate and blastocyst yield without affecting the HR and TCN whereas a higher concentration of 200 microm significantly (P < 0.05) reduced the blastocyst yield but not TCN. Similar increases in blastocyst yield, without any effect on HR and TCN were observed after supplementation of the IVC medium with 100 (P < 0.01) or 50 microm (P < 0.05) cysteamine, whereas 200 microm cysteamine was ineffective. Supplementation of both IVM medium with 50 microm cysteamine and of IVC medium with 100 microm cysteamine increased the yield of blastocysts and hatched blastocyst by over 100% (P < 0.01) compared with the controls without any adverse effects on HR or TCN. The results of the present study suggest that supplementation of both IVM and IVC media improves the yield of blastocysts without compromising their health.

Effect of slow freezing on morphology and developmental competence of buffalo (Bubalus bubalis) immature oocytes

The present study was conducted to evaluate the effects of three cryoprotectants, dimethyl sulphoxide (DMSO), ethylene glycol (EG) and 1,2-propanediol (PROH), each used at two concentrations (1.0 and 1.5 M) on the morphology, maturation rate and developmental capacity of usable quality immature buffalo oocytes subjected to slow freezing. The addition of the cryoprotectant before freezing and its dilution after thawing were carried out in a two- (for 1.0 M) or three-step manner (for 1.5 M). The incidence of damage was found to be significantly higher (P<0.05) with the lower concentration of 1.0 M, compared to that with 1.5 M for all the three cryoprotectants examined. The proportion of immature oocytes recovered in a morphologically normal state was significantly higher (P<0.05) for DMSO than those for EG or PROH at both 1.0 and 1.5 M concentrations. Among the six combinations evaluated, that of DMSO at 1.5 M concentration was found to be superior to others. Irrespective of the type or concentration of the cryoprotectant, partial or complete loss of the cumulus mass was the most prevalent damage. Following in vitro maturation, the nuclear maturation rate was significantly higher (P<0.05) for DMSO than those for EG or PROH at both 1.0 and 1.5 M concentrations. When the in vitro matured oocytes were subjected to in vitro fertilization after slow freezing, using 1.5 M DMSO as cryoprotectant, 4.5% and 0.6% of them were able to develop to morulae and blastocysts, respectively, on Day 9 post insemination, compared to 19.2% and 10.6%, respectively, for the controls. In conclusion, DMSO was more effective than EG or PROH for the slow freezing of immature buffalo oocytes and blastocysts could be produced from immature buffalo oocytes subjected to slow freezing in 1.5 M DMSO.

Nuclear morphology, diameter and meiotic competence of buffalo oocytes relative to follicle size

The nuclear morphology, diameter and in vitro meiotic competence of buffalo oocytes was compared relative to follicle size. Cumulus-oocyte complexes (COCs) were collected from 1-<2, 2-<3, 3-<4, 4-<6 and 6-<8 mm follicles from abattoir ovaries. Cumulus cells were removed using 3 mg mL(-1) hyaluronidase in saline and repeated pipetting. Denuded oocytes were measured, fixed in 3% glutaraldehyde, stained with 4,6-diamidoino-2-phenylindole and evaluated for nuclear morphology, namely the stage of germinal vesicle (GV) development before in vitro maturation (IVM). The COCs from >2-mm follicles were matured in vitro in their respective size groups for 24 h in Medium 199 supplemented with 10 microg mL(-1) follicle-stimulating hormone, 10 microg mL(-1) luteinizing hormone, 1.5 microg mL(-1) oestradiol, 75 microg mL(-1) streptomycin, 100 IU mL(-1) penicillin, 10 mM HEPES and 10% fetal bovine serum. Matured oocytes were fixed, stained and evaluated for GV status and meiotic development. The number of oocytes collected from follicles 1-<8 mm in diameter averaged 1.82 per ovary. Oocytes from follicles 1-<2 mm (107.7 +/- 1.6 microm), 2-<3 mm (108 +/- 1.1 microm) and 3-<4 mm (114.6 +/- 1.3 microm) in diameter were smaller in diameter (P < 0.05) than oocytes from follicles 4-<6 mm (124.4 +/- 1.3 microm) and 6-<8 mm (131.9 +/- 1.4 microm) in diameter. A majority of oocytes (P< 0.05) from <4-mm follicles was at the initial stages of GV development (GV-I, II and III), whereas oocytes from 4-<6- and 6-<8-mm follicles were at the final stages of GV-IV (35.0 and 21.6% respectively) and GV-V (49.1 and 67.5% respectively). Poor IVM rates of 32.0% and 32.7% to metaphase (M)-II were observed for oocytes isolated from 2-<3- and 3-<4-mm follicles, respectively, whereas significantly (P< 0.05) more oocytes from 4-<6- and 6-<8-mm follicles reached M-II (67.1% and 79.1% respectively). In conclusion, buffalo oocytes displayed a size-dependent ability to undergo meiotic maturation and we suggest that oocytes from >4-mm follicles should be considered in buffalo in vitro fertilization systems for better results.