Production of buffalo (Bubalus bubalis) embryos in vitro: premises and promises

Impact of epidermal growth factor and/or β-mercaptoethanol supplementations on the in vitro produced buffaloes' embryos

The present study investigated the effects of epidermal growth factors (EGF) and/or β-Mercaptoethanol (βME) supplementations to oocyte maturation, fertilization, and culture media on the buffalo in vitro embryo production. The ovaries were collected and transferred within 2 h to the laboratory. The cumulus oocytes complexes were aspirated from 3 to 8 mm diameter follicles. Firstly, EGF; 0, 10, 20, or 50 ng/mL or βME; 0, 25, 50, 100, or 200 μM were supplemented to the in vitro maturation (TCM-199), fertilization (IVF-TALP), or culture (IVC: SOF) media. Our results revealed that supplementing EGF (20 ng/mL) to the TCM-199, IVF-TALP, or SOF media could efficiently improve the growth rates and development of buffalos' embryos, while EGF (50 ng/mL) could stimulate the embryo production only after treatment of the IVF-TALP /or SOF media, but not the IVM medium. However, βME was less efficient than EGF; it stimulated the growth rates of buffalo embryos when supplemented with the maturation and fertilization (IVF-TALP) media in a 50 μM concentration. Secondly, combined EGF (20 ng/mL) and βME (50 μM) were supplemented to the maturation media as effective concentration. The combined treatment of EGF (20 ng/mL) and βME (50 μM) showed no significant enhancing effect on the buffalo embryos compared to each alone. For future perspectives, further study is required to examine the effects of combined EGF and βME on the maturation and fertilization of buffalo oocytes at different categories of age and seasonal localities.

Optimization of gonadotropin stimulation protocols for in vitro embryo production in prepubertal Mediterranean water buffalo

Embryos can be produced from prepubertal donor animals using laparoscopic ovum pickup and in vitro embryo production technologies (LOPU-IVEP). Together, these tools can shorten the interval between generations, rapidly accelerating the rate of genetic gain. Here, we assessed the impact of different gonadotropin stimulation protocols in Mediterranean water buffalo heifer calves aged between 2 and 6 months old. Following gonadotropin stimulation, LOPU was performed at two-week intervals, with animals receiving different protocols on subsequent LOPUs. After collection, the cumulus-oocyte complexes (COCs) were matured and fertilized in vitro, and embryos were cultured to the blastocyst stage followed by transfer into synchronized adult recipients. The number and size of follicles aspirated during LOPU, the number and quality of COCs recovered, as well as cleavage, embryo development and pregnancy rates were assessed. First, we evaluated the impact of using FSH with and without eCG (administered 24-h prior to LOPU) and found that a combination of FSH and eCG was able to significantly improve embryo development rates (20.6 ± 2.0% vs. 9.0 ± 3.6%; P < 0.05). Second, we compared this protocol to a slow-release formulation of FSH reconstituted in hyaluronan. In addition to requiring less work to prepare the animals for LOPU, this slow-release formulation yielded numerically higher, but not statistically different, average number of recovered COCs (14.4 ± 2.1 vs. 10.3 ± 2.0; P > 0.05) and embryo development rates (22.9 ± 4.7% vs. 14.1 ± 5.2%; P > 0.05) compared to FSH given every 12 h. Next, we compared the length of gonadotropin treatment over 3-, 4- and 5-days prior to LOPU and found that as the length of gonadotropin treatment increased, although the number of COCs recovered steadily decreased (14.1 ± 2.4 vs. 8.7 ± 1.0 vs. 6.9 ± 0.7; P < 0.05), the embryo development rates steadily increased (14.4 ± 3.9 vs. 27.3 ± 4.4 vs. 35.9 ± 7.0; P < 0.05), presumably due to an increase in the proportion of large follicles at the time of LOPU. Numerically, the 4-day treatment yielded more transferrable embryos per donor per LOPU (2.70 ± 0.5) than 3-day (1.94 ± 0.6) and 5-day (2.25 ± 0.5) treatments. Finally, following embryo transfer, 26 of 90 recipient females became pregnant (28.9%). Pregnancies were established from all treatments, which suggests that post-implantation development was not affected among the gonadotropin treatments assessed.

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.

Oocyte IVM or vitrification significantly impairs DNA methylation patterns in blastocysts as analysed by single-cell whole-genome methylation sequencing

To explore the mechanisms leading to the poor quality of IVF blastocysts, the single-cell whole-genome methylation sequencing technique was used in this study to analyse the methylation patterns of bovine blastocysts derived from invivo, fresh (IVF) or vitrified (V_IVF) oocytes. Genome methylation levels of blastocysts in the IVF and V_IVF groups were significantly lower than those of the invivo group (P<0.05). In all, 1149 differentially methylated regions (DMRs) were identified between the IVF and invivo groups, 1578 DMRs were identified between the V_IVF and invivo groups and 151 DMRs were identified between the V_IVF and IVF groups. For imprinted genes, methylation levels of insulin-like growth factor 2 receptor (IGF2R) and protein phosphatase 1 regulatory subunit 9A (PPP1R9A) were lower in the IVF and V_IVF groups than in the invivo group, and the methylation level of paternally expressed 3 (PEG3) was lower in the V_IVF group than in the IVF and invivo groups. Genes with DMRs between the IVF and invivo and the V_IVF and IVF groups were primarily enriched in oocyte maturation pathways, whereas DMRs between the V_IVF and invivo groups were enriched in fertilisation and vitrification-vulnerable pathways. The results of this study indicate that differences in the methylation of critical DMRs may contribute to the differences in quality between invitro- and invivo-derived embryos.

"Which Factors Affect Pregnancy Until Calving and Pregnancy Loss in Buffalo Recipients of in vitro Produced Embryos?"

In vitro embryo production and embryo transfer (ET) in buffaloes has been developed for decades. However, most studies are focused on the donor or laboratory improvements, and there is a lack of reports regarding the recipients. Therefore, our aim was to investigate factors associated to pregnancy (P/ET), pregnancy loss (PL), and calving rates in buffalo recipients. The studied factors were season, recipient parity, the synchronization protocol, the CL diameter, asynchrony between the embryo and the recipient, the day of the recipient estrous cycle, the embryo (fresh vs. vitrified), the day of embryo development, and the embryo stage. These retrospective data, from a program of in vitro produced embryos, were analyzed by logistic regression, and the odds ratio was also estimated. Two factors were related to P/ET and the calving rate: (1) progesterone associated to estradiol plus eCG protocol for fixed time ET tended to affect positively P/ET on day 30 (41.9 vs. 36.1%, respectively; P = 0.07; AOR = 1.28) and P/ET on day 60 (37.8 vs. 36.1%, respectively; P = 0.09; AOR = 1.08) compared to the Ovsynch protocol; and (2) the CL diameter (≥14.5 mm) at transfer increased P/ET on day 30 (47.4 vs. 32.5%; P < 0.01; AOR = 1.87) and on day 60 (45.3 vs. 27.7%; P < 0.01; AOR = 2.16), and also the calving rate (37.9 vs. 21.7%; P < 0.01; AOR = 2.20). PL was greater when ET was done in the nonbreeding season compared to the breeding season (PL 30-60: 12.8 vs. 0.0%, P = 0.01; AOR > 999.99; PL 60-calving: 26.8 vs. 3.6%, P = 0.03; AOR = 9.90; and PL 30-calving: 36.2 vs. 3.6%, P = 0.01; AOR = 15.30). In conclusion, the data of our study indicated that the synchronization protocol, the CL diameter, and ET during the breeding season impacted the reproductive efficiency of buffalo recipients.

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.

Developmental potential of buffalo embryos cultured in serum free culture system

The presence of serum in embryo culture medium has been implicated for increased embryo's sensitivity to cryopreservation, compromised viability, abnormal embryo and fetal development. Hence, designing a serum free culture system is indispensable. The present study aims to compare the efficiency of the serum and granulosa cells monolayer free commercial culture system (SFCS) with the conventional serum supplemented co-culture system (SSCS) and optimized culture system (OCS). Generally, SFCS is designed explicitly for bovine oocyte maturation and embryo culture (SF-IVM and SF-IVC), and SSCS (based on M199, SS-IVM, and SS-IVC) is utilized for buffalo in vitro embryo production. However, OCS is a newly designed culture system in which oocyte maturation is performed in serum supplemented maturation medium, and the subsequent embryos are co-cultured with granulosa cells in serum free culture medium. To evaluate the effect of serum on buffalo embryo production, buffalo oocytes, and their subsequent embryos were cultured in SSCS, SFCS, and OCS, simultaneously. The percentage of cleaved embryos cultured in SSCS and OCS was approximately 4% higher as compared to SFCS. However, OCS significantly showed the maximum proportion of embryos that developed to the blastocyst stage (7d) and hatched (6d) as compared to the SFCS and SSCS. Additionally, OCS promoted the expression of developmentally important genes (BCL2-L1 and VEGF-A), cell number, and cryo-survival ability of blastocysts in comparison with SSCS. Taken together, OCS is more suitable for the oocyte maturation and culture of buffalo embryos. However, to design the serum free culture system, it is recommended to find suitable serum alternatives for in vitro oocyte maturation.

Retinoic acid improves maturation rate and upregulates the expression of antioxidant-related genes in in vitro matured buffalo (Bubalus bubalis) oocytes

Retinoic acid, vitamin A metabolite, plays a role in oocyte development and maturation in different ways including gene expression alteration and/or prohibiting oxidative stress. The objective of this study was to examine the effect of 9-cis-retinoic acid (9-cisRA) on the quality and maturation rate of buffalo oocytes. Cumulus-oocyte complexes (COCs, n = 460) were collected from ovaries of slaughtered buffalos. Varying concentrations of 9-cisRA (0, 5, 50, and 200 nM) were added to the maturation medium, and the following parameters were analyzed: (i) maturation and cleavage rates, (ii) mitochondrial activity and reactive oxygen species (ROS) levels, (iii) expression level of antioxidant-related genes (PRDX1, SOD1, CAT, HOMX1, and GPX4) using RT-qPCR. Maturation rate was significantly improved in 5 nM 9-cisRA oocyte group (95.8%, P < .05) compared to control and other treatment groups (86.7% in control group). The same oocyte group exhibited significantly higher mitochondrial membrane potential activity and lower ROS accumulation level compared to other treatment groups. Antioxidant-related genes were up-regulated in oocytes matured with 5 or 50 nM 9-cisRA compared to control and 200 nM 9-cisRA groups. In contrast, 200 nM of 9-cisRA showed a clear down-regulation for antioxidant-related genes except for PRDX1. In conclusion, supplementation of 9-cisRA with a lower concentration (5 nM) to the buffalo oocytes maturation media promotes maturation rate through a protection mechanism that maintains adequate levels of antioxidant-related transcripts and improves mitochondrial activity. However, 9-cisRA has no significant effect on the cleavage rate of the treated oocytes.

Maturational gene upregulation and mitochondrial activity enhancement in mouse in vitro matured oocytes and using granulosa cell conditioned medium

The high miscarriage rates that result following transfer of embryos derived from in vitro maturation (IVM) of oocytes necessitate improvements in the processes involved. This study aimed to improve the quality of in vitro matured oocytes using granulosa cell conditioned medium (GCCM) as the culture medium. In this work, germinal vesicle (GV)-stage oocytes from NMRI mice were collected and cultured using three types of culture medium: Base medium (BM) (control), 50% granulosa cell conditioned medium (GCCM50) and 100% GCCM (GCCM100). After IVM, the mitochondria activity potential and viability of metaphase II (MII) oocytes were evaluated by JC-1 and trypan blue staining, respectively. Maturational gene expression levels of CyclinB1, Cdk1 and Gdf9 in the control, GCCM50 and GCCM100 samples were analyzed using real-time polymerase chain reaction (PCR). The viability rate of in vitro matured oocytes was highest in the GCCM50 group. JC-1 staining showed that GCCM50 enhances mitochondrial activity more than the other groups (P < 0.05). Gene expression levels of Cdk1 and Gdf9 were higher in the group with GCCM50 treatment, than in the control and GCCM100 groups (P < 0.05), while the expression level of CyclinB1 did not differ among the groups. The results indicated that a 50% concentration of GCCM in combination with BM components enhanced MII and viability rates and mitochondria activity of mouse immature oocytes.

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.

Effect of melatonin on maturation capacity and fertilization of Nili-Ravi buffalo (Bubalus bubalis) oocytes

This study evaluated the effect of melatonin supplementation of in vitro maturation media on in vitro maturation (IVM) and in vitro fertilization (IVF) rate of buffalo oocytes. Cumulus oocytes complexes (COCs) were aspirated from follicles of 2-8 mm diameter. In experiment I, COCs were matured in IVM medium supplemented with 0 (control), 250, 500, and 1000 μM melatonin for 22-24 hours in CO₂ incubator at 38.5°C with 5% CO₂ and at 95% relative humidity. The maturation rate did not differ in media supplemented with melatonin at 250 μM, 500 μM, 1000 μM and control (0 μM). In experiment II, the matured oocytes were fertilized in 50 μl droplets of Tyrode’s Albumin Lactate Pyruvate (TALP) medium having 10 ug/ml heparin for sperm (2 million/ml) capacitation. The fertilization droplets were then kept for incubation at 5% CO₂, 39°C and at 95% relative humidity for 18 hours. The fertilization rate was assessed by sperm penetration and pronuclear formation. Fertilization rate was improved when maturation medium was supplemented with 250 μM melatonin compared to control. In conclusion, melatonin supplementation to serum free maturation media at 250 μM improved the fertilization rate of buffalo oocytes.

Advances in reproductive biotechnologies

In recent times, reproductive biotechnologies have emerged and started to replace the conventional techniques. It is noteworthy that for sustained livestock productivity, it is imperative to start using these techniques for facing the increasing challenges for productivity, reproduction and health with impending environment conditions. These recent biotechniques, both in male and female, have revolutionized and opened avenues for studying and manipulating the reproductive process both in vitro and in vivo in various livestock species for improving tis efficiency. This review attempts to highlight pros and cons, on the recent developments in reproductive biotechnologies, both in male and female in livestock species.

Expression and purification of buffalo interferon-tau and efficacy of recombinant buffalo interferon-tau for in vitro embryo development

The aim of our study was to optimize growth and induction parameters, for expression and large scale purification of functionally active buffalo interferon tau, and to study its possible impact on in vitro blastocyst development. The buffalo interferon-tau gene (BuIFN-T1) bearing gene bank accession No. JX481984, with signal sequence, was obtained through polymerase chain reaction (PCR) from bovine early embryos and was cloned into pJET vector. After being verified, the fragments without signal sequence, were inserted into the expression vector pET-22b and the recombinant plasmid was induced to express the recombinant protein in a prokaryotic expression system. The recombinant BuIFN-T was confirmed by SDS-PAGE and Western blot and subjected to three steps of large scale purification using His Affinity chromatography, Anion Exchange chromatography and Gel Filtration chromatography. The purified recombinant BuIFN-T protein was validated by mass spectroscopy analysis. To examine the effect of recombinant BuIFN-T protein on developmental competency of buffalo embryos, purified recombinant BuIFN-T protein was added to in vitro embryo culture medium (at concentration of 0, 1μg/ml, 2μg/ml, 4μg/ml) for 9days. Addition of recombinant BuIFN-T (2μg/ml) significantly improved the rate of blastocyst production, 45.55% against 31.1% control (p<0.01). Here we conclude that the recombinant BuIFN-T was successfully purified to homogeneity from a prokaryotic expression system and it significantly increased the blastocyst production rate in buffalo. These findings suggest a potential impact of IFN-T in promoting embryonic growth and development.

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.

α-Tocopherol and l-ascorbic acid increase the in vitro development of IVM/IVF swamp buffalo ( Bubalus bubalis) embryos

This study was conducted to investigate the effects of capacitating agents added at in vitro fertilization (IVF) and antioxidants supplemented during in vitro culture (IVC) on the development of buffalo embryos. In experiment I, in vitro embryo development of buffalo embryos was compared when the IVF medium was supplemented with heparin, caffeine and calcium ionophore A23187 either alone or in combination. There was no significant difference (P > 0.05) in the cleavage rates of oocytes among the treatment groups but the development rate to the blastocyst stage and the cell numbers of blastocyst in the heparin-treated group were significantly higher (P < 0.05) than that of other treatments. In experiment II, in vitro embryo development of buffalo embryos was compared when IVC medium was supplemented with either α-tocopherol (250 and 500 μM) or l-ascorbic acid (250 and 500 μM). The rate of development to the blastocyst stage of embryos cultured in medium supplemented with 250 μM α-tocopherol (33%, 41/123) and 250 μM l-ascorbic acid (31%, 38/123) was significantly higher (P < 0.05) than that of those cultured in medium alone (19%, 20/108) but not significantly different (P < 0.05) from medium supplemented with either 500 μM α-tocopherol (24%, 30/123) or 500 μM l-ascorbic acid (25%, 33/133). These results suggest that buffalo spermatozoa treated with heparin were suitable for IVF and that α-tocopherol and l-ascorbic acid added during IVC increased the rate of buffalo embryo development.

A reporter promoter assay confirmed the role of a distal promoter NOBOX binding element in enhancing expression of GDF9 gene in buffalo oocytes

Growth differentiation factor 9 is primarily expressed in oocytes and plays a vital role in oocyte cumulus crosstalk. Earlier studies with buffalo oocytes revealed differential expression of this gene under different media stimulation conditions which, in turn, are correlated with the blastocyst yield. In this study, different germ cell specific cis elements including a NOBOX binding elements (NBE) and several E-boxes were identified at the 5' upstream region of buffalo GDF9 gene and their potential role in GDF9 expression was investigated. Transfecting oocytes with GDF9 promoter deletion constructs harbouring the NBE reporter gene revealed a 33% increase in GFP as well as the luciferase signal signifying its role in stimulating the minimal promoter activity of GDF9 in buffalo oocytes. Site directed mutation of core binding nucleotides at NBE at 1.8 kb upstream to TSS further confirmed its role for enhancing the basal transcriptional activity of GDF9 promoter in buffalo oocytes. Current work will provide important leads for understanding the role of GDF9 in oocytes competence and designing a more physiological IVF protocol in case of buffalo.

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.

Assisted reproductive techniques for cattle breeding in developing countries: a critical appraisal of their value and limitations

Commercialization of animal biotechnologies, including those related to reproduction [also known as assisted reproductive techniques (ARTS)], is an increasing reality in developing countries, following the enormous flow of information around us and the increasing global commercial interests in areas where cattle production has its major assets. The present review discusses the achievements of various biotechnological tools for reproduction in cattle including semen handling for artificial insemination (AI), superovulation and embryo transfer (MOET), in vitro handling of oocytes and production of embryos, reproductive cloning and emerging technologies (sex selection, gene targeting and nuclear transfer for livestock transgenesis, genomics for marker-assisted selection, etc.). The application of these technologies for cattle breeding is critically discussed in relation to their impact in the improvement of the efficiency of dairy and beef production in developed and - particularly - in developing countries, which ultimately rule the possibilities of a competitive and sound production of food for human consumption. Despite the remarkable progress made and the punctual importance of some of the above-mentioned technologies, AI remains the most important assisted reproductive technology (ART) in developing countries. Any attempt to gain widespread of any other ART under the predominant economical conditions in developing countries ought to match the simplicity and the success of AI as a breeding tool.

Characterization of oocyte-expressed GDF9 gene in buffalo and mapping of its TSS and putative regulatory elements

Summary In spite of emerging evidence about the vital role of GDF9 in determination of oocyte competence, there is insufficient information about its regulation of oocyte-specific expression, particularly in livestock animals. Because of the distinct prominence of buffalo as a dairy animal, the present study was undertaken to isolate and characterize GDF9 cDNA using orthologous primers based on the bovine GDF9 sequence. GDF9 transcripts were found to be expressed in oocytes irrespective of their follicular origin, and shared a single transcription start site (TSS) at -57 base pairs (bp) upstream of ATG. Assignment of the TSS is consistent with the presence of a TATA element at -23 of the TSS mapped in this study. Localization of a buffalo-specific minimal promoter within 320 bp upstream of ATG was consolidated by identification of an E-box element at -113bp. Presence of putative transcription factor binding sites and other cis regulatory elements were analyzed at ~5 kb upstream of TSS. Various germ cell-specific cis-acting regulatory elements (BNCF, BRNF, NR2F, SORY, Foxh1, OCT1, LHXF etc.) have been identified in the 5' flanking region of the buffalo GDF9 gene, including NOBOX DNA binding elements and consensuses E-boxes (CANNTG). Presence of two conserved E-boxes found on buffalo sequence at -520 and -718 positions deserves attention in view of its sequence deviation from other species. Two NOBOX binding elements (NBE) were detected at the -3471 and -203 positions. The fall of the NBE within the putative minimal promoter territory of buffalo GDF9 and its unique non-core binding sequence could have a possible role in the control of the core promoter activity.

Chronological Reorganization of Microtubules, Actin Microfilaments, and Chromatin during the First Cell Cycle in Swamp Buffalo (Bubalus bubalis) Embryos

This paper aimed to study the dynamics of early embryonic development, in terms of redistribution of cytoskeleton (microtubules, actin microfilaments) and chromatin configurations during the first cell cycle in swamp buffalo embryos. Oocytes were matured and fertilized in vitro, and they were fixed at various time points after IVF. At 6 h after IVF, 44.4% matured oocytes were penetrated by spermatozoa. Partial ZP digestion, however, did not improve fertilization rate compared to control (P > .05). At 12 h after IVF, the fertilized oocytes progressed to the second meiotic division and formed the female pronucleus simultaneously with the paternal chromatin continued to decondense. A sperm aster was observed radiating from the base of the decondensing sperm head. At 18 h after IVF, most presumptive zygotes had reached the pronuclear stage. The sperm aster was concurrently enlarged to assist the migration and apposition of pronuclei. Cell cleavage was facilitated by microfilaments and firstly observed by 30 h after IVF. In conclusion, the cytoskeleton actively involves with the process of fertilization and cleavage in swamp buffalo oocytes. The centrosomal material is paternally inherited. Fertilization failure is predominantly caused by poor sperm penetration. However, partial digestion of ZP did not improve fertilization rate.

Ultrastructure of in vitro oocyte maturation in buffalo (Bubalus bubalis)

The objective of the present study was to describe ultrastructural changes in the nucleus and cytoplasmic organelles during in vitro maturation (IVM) of buffalo cumulus–oocyte complexes (COCs). The structures were collected by ovum pick-up (OPU). Some COCs, removed from maturation medium at 0, 6, 12, 18 and 24 h, were processed for transmission electron microscopy. The average number of COCs collected by OPU/animal/session was 6.4, and 44% of them were viable. Immature oocytes had a peripherally located nucleus, Golgi complex and mitochondrial clusters, as well as a large number of coalescent lipid vacuoles. After 6 h of IVM, the oocyte nucleus morphology changed from round to a flatter shape, and the granulosa cells (GC) lost most of their contact with zona pellucida (ZP). At 12 h the first polar body was extruded and the aspect of lipid droplet changed to dark, probably denoting lipid oxidation. Cortical granules were clearly visible at 18 h of maturation, always located along the oocyte periphery. At 24 h of IVM the number of cortical granules increased. Ultrastructure studies revealed that: (1) immature oocytes have a high lipid content; (2) the perivitelline space (PS) increases during IVM; (3) Golgi complexes and mitochondrial clusters migrate to oocyte periphery during IVM; (4) 6 h of IVM are enough to lose contact between GC and ZP; (5) the oocyte lipid droplets’ appearance changes between 6 and 12 h of IVM.

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.

Motility, acrosome integrity, membrane integrity and oocyte cleavage rate of sperm separated by swim-up or Percoll gradient method from frozen-thawed buffalo semen

Frozen-thawed semen of five buffalo bulls was used to compare efficacy of swim-up and Percoll gradient methods for separating viable spermatozoa. Sperm separated by the two methods were also tested to differentiate buffalo bulls on the basis of in vitro fertilization (IVF) rates. Recovery of motile sperm (%), increase in membrane integrity (%) and acrosome integrity (%) were compared after two sperm separation methods in experiment I, and in vitro fertilization rate (cleavage rate and cleavage index) was compared in experiment II. Swim-up separated sperm showed a higher motility (P<0.05), while percent recovery of motile sperm was higher with Percoll separation (P<0.05). Membrane integrity (%) of sperm separated with swim-up was significantly higher (P<0.05) as compared to sperm separated with Percoll gradient. Swim-up separated sperm gave a higher cleavage rate and cleavage index (P<0.001). Sperm separated by swim-up showed significant difference among the bulls in cleavage rate and cleavage index (P<0.05), while the Percoll gradient method did not. It has been concluded that separation of sperm from frozen-thawed buffalo semen by swim-up method can be more expedient for IVF in buffalo.

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 taurine and melatonin in the culture medium on buffalo in vitro embryo development

This study was carried out to investigate the effect of supplementing culture medium with different concentrations of taurine and melatonin, on buffalo oocyte in vitro meiotic maturation and embryo development. In experiment 1, oocytes were matured in vitro and the cleaved embryos were cultured in the same following seven culture medium; (i) control (TCM 199 + 10% SS); (ii) control + 0.5 mM taurine; (iii) control + 1 mM taurine; (iv) control + 3 mM taurine; (v) control + 5 microM melatonin; (vi) control + 10 microM melatonin and (vii) control + 50 microM melatonin. In experiment 2, based on the results of experiment 1, to examine the synergistic effect of antioxidants, the oocytes were matured in culture medium (TCM199 + 10% SS), supplemented with both taurine at 1 mM and melatonin at 10 microM concentration and the cleaved embryos were cultured in the same medium. Supplementation of taurine at 1 mM concentration in the culture medium resulted in a higher (p < 0.05) transferable embryo (TE) yield when compared with control (20.6% vs 14.1%). Supplementation of melatonin at 10 and 50 microM concentration in the culture medium resulted in a higher (p < 0.05) meiotic maturation rate (90.3% and 88.8% respectively) and TE yield (28.4% and 27.2% respectively), than the other treatments. In experiment 2, the TE yield did not improve by supplementing the culture medium with both taurine and melatonin, when compared with melatonin alone. In conclusion, the results of this study demonstrated that, enriching the culture medium with taurine and melatonin, improves in vitro embryo production efficiency in buffaloes. In particular, a high TE yield was obtained by enriching the culture medium with 10 microM melatonin.

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.

In vitro embryo development and blastocyst hatching rates following vitrification of river buffalo embryos produced from oocytes recovered from slaughterhouse ovaries or live animals by ovum pick-up

The present study was undertaken to determine whether the source of oocytes (ovum pick up versus slaughterhouse ovaries) affected in vitro embryo production and embryo survival (as measured by blastocyst hatching rates) following vitrification in buffaloes (Bubalus bubalis). Oocytes recovered from live buffaloes (n=6) by ovum pick up (OPU) and by manual aspiration from slaughterhouse ovaries were in vitro matured, fertilized and cultured to blastocyst stage under same culture conditions. Vitrification of blastocysts was carried out in two steps at 24 degrees C. Embryos were equilibrated in 10% EG+10% DMSO+0.3 M sucrose in base medium for 4 min. Subsequently, the embryos were transferred into 25% EG+25% DMSO+0.3 M sucrose in base medium for 45 s and then the embryos were loaded into straws and immersed in liquid nitrogen. Following warming, blastocysts were cultured in vitro for 48 h to assess hatching. Oocytes derived from live animals by OPU resulted in a significantly higher blastocyst yield then those derived from slaughterhouse ovaries (30.6+/-4.3 versus 18.5+/-1.8). Blastocyst hatching rates following vitrification of buffalo embryos produced from the oocytes collected from live animals by OPU was significantly higher than the oocytes collected from slaughterhouse ovaries (52.8+/-4.2 versus 40.2+/-4.4). In conclusion, the present study showed that source of oocytes (OPU versus slaughterhouse ovaries) affects the in vitro embryo development and blastocyst hatching rates following vitrification of embryos in buffaloes.

Selection of developmentally competent buffalo oocytes by brilliant cresyl blue staining before IVM

The brilliant cresyl blue (BCB) test determines the activity of glucose-6-phosphate dehydrogenase (G6PDH); the activity of this enzyme is greatest in growing oocytes, but it declines as oocytes mature. The objective was to develop and evaluate this test for assessing development of buffalo oocytes (to select developmentally competent oocytes for increased in vitro embryo production). Oocytes were exposed to BCB stain diluted in mDPBS (DPBS with 0.4% BSA) for 90 min at 38.5 degrees C in a humidified air atmosphere; those with or without blue coloration of the cytoplasm were designated as BCB+ and BCB-, respectively. In Experiment 1, oocytes were exposed to 13, 26, or 39 microM BCB. There were fewer BCB+ oocytes after exposure to 13 microM BCB (10%) than after exposure to 26 or 39 microM BCB (57.2 and 61.8%; P<0.05), but there was no significant difference among treatments for blastocyst production rate. In Experiment 2, the diameter of BCB+ oocytes (144.4+/-4.2 microm; mean+/-S.E.M.) was higher (P<0.05) than that of BCB- oocytes (136.8+/-4.6 microm). In Experiment 3, oocytes were allocated into three groups: control (immediately cultured); holding-control (kept in mDPBS for 90 min before cultured); and treatment-incubation (incubated with 26 microM BCB). After IVM, oocytes were fertilized in vitro and cultured on an oviductal monolayer. The nuclear maturation rate was higher (P<0.05) in BCB+ (86.2%), control (83.4%) and holding-control (82.6%) oocytes than BCB- (59.2%) oocytes. The BCB+ oocytes yielded more blastocysts than control or holding-control oocytes (33.4, 20.2, and 21.0%, P<0.05); blastocyst development was lowest in BCB- oocytes (5.2%). In conclusion, staining of buffalo oocytes with BCB before IVM may be used to select developmentally competent oocytes for increased in vitro embryo production.

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.

In vitro developmental competence of buffalo oocytes collected at various stages of the estrous cycle

The objective was to determine the in vitro developmental competence of buffalo oocytes collected from abattoir-derived ovaries at various stages of the estrous cycle and follicular status. In Experiment 1, ovaries (n=476 pairs) were collected and divided into the following five groups: (a) ovaries with a corpus hemorragicum and no dominant follicle (CH-NO-DF); (b) ovaries with a mature functional corpus luteum (CL) and a dominant follicle (CL-DF); (c) ovaries with a mature functional CL and no dominant follicle (CL-NO-DF); (d) ovaries with a regressing CL and a dominant follicle (RCL-DF); and (e) ovaries without any luteal structures and only small follicles (ANEST). In Experiment 2, 144 pairs of ovaries with a CL (or regressing CL) and a dominant follicle were collected and follicles were classified as dominant, largest subordinate, and subordinate. In both experiments, the dominant follicle was defined as any follicle >10mm in diameter that exceeded the diameter of all other (subordinate) follicles. Although oocytes were collected from each group of ovaries, only Grades A or B oocytes were used for in vitro embryo production. Cleavage rates were higher (P<0.05) from oocytes collected from ovaries in the CH-NO-DF (59.6%) and CL-NO-DF (59.2%) groups than those collected from CL-DF (52.2%) and ANEST (43.6%) groups. The yield of transferable embryos was higher (P<0.05) from oocytes collected from CH-NO-DF (27.4%) and CL-NO-DF (24.0%) ovaries than from CL-DF (16.2%), RCL-DF (15.4%), and lowest (P<0.05) from ANEST (8.8%). In Experiment 2, oocytes from the dominant follicle had a higher (P<0.05) cleavage rate (65.2 %) and transferable embryo yield (30.2%) than those collected from the largest subordinate and subordinate follicles. In conclusion, oocyte competence depended on the morphofunctional state of ovaries. Oocyte development was maximal in pairs of ovaries with a corpus hemorragicum or CL and no dominant follicle; in paired ovaries with a CL and a dominant follicle, development was maximal in oocytes derived from the dominant follicle.

Advanced reproductive technology in the water buffalo

Embryo transfer techniques in water buffalo were derived from those in cattle. However, the success rate is much lower in buffaloes, due to their inherent lower fertility and poor superovulatory response. The buffalo ovary has a smaller population of recruitable follicles at any given time than the ovary of the cow (89% fewer at birth). In addition, estrus detection is problematic. Progress in the field of embryo transfer in water buffalo has been slow, and is primarily due to a poor response to superovulation. The average yield of transferable embryos is less than one per superovulated donor. In vitro embryo production could considerably improve the efficacy and logistics of embryo production. The technique of Ovum Pick Up is superior to superovulation; it can yield more transferable embryos per donor on a monthly basis (2.0 versus 0.6). The feasibility of intergeneric embryo transfer between buffalo and cattle has been investigated. No pregnancy resulted after transfer of 13 buffalo embryos to synchronized Holstein heifers. Preliminary successes with nucleus transfer of Bubalus bubalis fetal and adult somatic nuclei into enucleated bovine oocytes and subsequent development to the blastocyst stage have been reported.

Development of a Competitive Quantitative PCR Strategy for Evaluating the Expression Stability of 18s rRNA during In Vitro Maturation of Buffalo (Bubalus bubalis) Follicular Oocytes

The present work describes the development of a quantitative competitive PCR strategy for quantifying the relative abundance of 18s rRNA transcripts in buffalo oocytes during in vitro maturation (IVM). As a method, the competitive PCR overcomes some of the shortcomings of conventional reverse transcriptase polymerase chain reaction (RT-PCR) procedure making it a more authentic quantitative method. A composite primer based approach was used to generate the competitor cDNA to be used as external control. Validity of the method for its efficiency was demonstrated by quantitative analysis of the competition parameters. Using this method the relative abundance of buffalo oocyte 18s rRNA transcript over the period of IVM was found to vary within a narrow range of 0.93-1.06 folds which establishes the accuracy of the method and reflects the stability of its expression during IVM. This qualifies the use of this house keeping gene as a valid internal control in studies investigating the gene expression pattern in buffalo oocytes. The competitive PCR approach described in this study could be used for quantification of other transcripts from a limited number of oocytes where a conventional RT-PCR method is either difficult to use or multiplexing it with highly abundant house keeping genes is apparently problematic.

Somatic cell nuclear transfer in buffalos: effect of the fusion and activation protocols and embryo culture system on preimplantation embryo development

The present study was conducted primarily to evaluate several factors that affect the nuclear transfer programme in water buffalos, in which relatively few studies have been performed. Embryos reconstructed with quiescent fetal fibroblasts and metaphase II cytoplasts were matured for 24 h, and activation was found to be comparatively better than in those matured for 30 h. A significantly higher proportion of embryos fused (52.0 ± 1.9) and cleaved (51.2 ± 1.7) when the couplets were fused 4–6 h before activation than when fused and activated simultaneously (46.5 ± 1.6 and 44.5 ± 2.0, respectively). Development of nuclear transfer embryos to the blastocyst stage (4.8 ± 2.2) was supported by a commercially available sequential medium, and cleavage (76.5 ± 2.8) was significantly higher in this medium compared with cleavage in TCM-199 with oviduct epithelial cell coculture (45.6 ± 1.5) and synthetic oviduct fluid (21.8 ± 6.6). Of the 16 cloned embryos transferred, none resulted in pregnancy. The present study demonstrates that optimal numbers of cloned buffalo blastocysts can be obtained from oocytes matured for 24 h, fused 3–4 h before activation and cultured in a commercially available sequential media (G1/G2), thus providing further information to enable successful nuclear transfer in buffalos.

In vitro Development of Buffalo Oocytes in Media-containing Fluids from Different Size Class Follicles

Studies were conducted to investigate the effect of supplementation of fluid from different sized class [small (SFF, < 3 mm), medium (MFF, 3-8 mm) and large (LFF, > 8 mm)] of normal and cystic (CFF) ovarian follicles in oocyte culture media on oocyte maturation rate and embryo development in vitro and to test the efficacy of follicular fluid (FF) from different size classes as a whole oocyte maturation medium. Results suggested that FF were capable of developing buffalo oocytes to embryonic stage in vitro although its efficacy was lower than that of serum. Regardless of high maturation rates after in vitro maturation (IVM) in media containing FF or IVM in whole FF, low blastocyst rates were obtained after in vitro fertilization (IVF) and culture of embryos. Follicular fluid from small follicles had significantly (p < 0.05) higher potential of developing buffalo oocytes to embryonic stage in vitro than that from medium and large follicles. Cystic FF was not capable of supporting development of buffalo oocytes in vitro.

Vitrification of bovine oocytes and its application to intergeneric somatic cell nucleus transfer

We determined the efficacy of a microdrop vitrification procedure for cryopreservation of bovine oocytes, using vitrified oocytes as cytoplasts for intraspecies and intergeneric somatic cell nucleus transfer (NT). In vitro matured bovine MII oocytes were vitrified in microdrops with a vitrification solution containing 35% ethylene glycol, 5% polyvinyl pyrrolidone, and 0.4 M trehalose. After warming, approximately 80% of the vitrified oocytes were morphologically normal, and their enucleation rate was similar to that of fresh oocytes. The NT embryos constructed with bovine cumulus cells and the vitrified oocytes developed similar to blastocysts constructed with fresh oocytes, although the cell number of NT blastocysts originating from vitrified oocytes was lower than that of the fresh control. In a second experiment, we examined the development of NT embryos constructed with vitrified bovine oocytes and bovine fibroblasts (intraspecies NT embryos) or swamp buffalo fibroblasts (intergeneric NT embryos). There were no differences between the intraspecies and intergeneric NT embryos in fusion, cleavage and development to blastocysts, except for lower cell numbers in the intergeneric NT blastocysts. In conclusion, the efficacy of this microdrop vitrification procedure and the production of swamp buffalo NT blastocysts using vitrified bovine oocytes was demonstrated.

Developmental competence and post-thaw survivability of buffalo embryos produced in vitro: effect of growth factors in oocyte maturation medium and of embryo culture system

The present study was conducted to examine the effects of supplementation to IVM medium of epidermal growth factor (EGF), fibroblast growth factor (FGF) and vasoactive intestinal peptide (VIP) along with pregnant mare serum gonadotrophin (PMSG) on oocyte maturation and cleavage of buffalo embryos (experiment 1). The developmental competence of cleaved embryos cultured in either a complex co-culture system (TCM-199+10% serum+oviduct cell monolayer) or defined media (a) modified form of synthetic oviductal fluid (mSOF) was evaluated (experiment 2). The post-thaw morphology and survivability of frozen blastocysts developed from embryos cultured either in complex or defined medium was compared (experiment 3). Aspirated oocytes were cultured in maturation medium (TCM-199+PMSG (40 IU/ml-control)) supplemented with EGF (20 ng/ml), FGF (20 ng/ml) and VIP (20 ng/ml), either alone or in combination, in a CO(2) incubator at 38.5 degrees C for 24h. Maturation rate was assessed and oocytes were inseminated in vitro with frozen-thawed sperm processed in Brackett and Oliphant (BO) medium. The cleaved embryos were cultured either in complex co-culture system or mSOF. Results suggested that EGF had more beneficial effect on buffalo oocyte maturation, and embryo cleavage than FGF. Addition of VIP to the oocyte maturation medium did not improve the results. Blastocyst yields from buffalo oocytes were significantly higher in a complex co-culture system than in defined media (mSOF) when oocytes were matured in presence of EGF either alone or in combination with FGF and VIP. The mean percent of morphologically normal blastocysts after thawing and their survivability were significantly higher in blastocysts obtained from embryos cultured in mSOF than those cultured in complex co-culture system.

In vitro maturation and fertilization of buffalo oocytes: effects of storage of ovaries, IVM temperatures, storage of processed sperm and fertilization media

Studies were conducted to examine the possibility of preserving slaughterhouse-derived buffalo ovaries at 4 degrees C for 0 (control), 12 and 24 h to maintain the developmental competence of the oocytes (experiment 1), to assess the effect of incubation temperature during oocyte maturation on rates of in vitro maturation (IVM) and in vitro fertilization (IVF) of buffalo oocytes and embryo development (experiment 2), and to examine the effect of storage at 25 degrees C for 0 (control), 4 and 8 h of frozen-thawed buffalo sperm and BO and H-TALP as sperm processing and fertilization media on cleavage and embryo development in vitro of buffalo oocytes (experiment 3) in order to optimize the IVF technology in buffalo. Results suggested that storage of ovaries at 4 degrees C for 12 or 24 h significantly (p < 0.05) reduced the developmental potential of oocytes. Incubation temperatures during the IVM influenced the fertilization rate but had no significant effect on maturation and subsequent embryo development. The incubation temperature of 38.5 degrees C during IVM was found to be optimum for embryo production in vitro. Storage of frozen-thawed sperm at 25 degrees C for 8 h significantly (p < 0.05) decreased its ability to cleave the oocytes. Sperm processed in BO medium had significantly (p < 0.05) higher ability to cleave the oocytes than the H-TALP medium.