Rapid sexing of water buffalo (Bubalus bubalis) embryos using loop-mediated isothermal amplification

Loop-mediated isothermal amplification (LAMP) is a novel DNA amplification method that amplifies a target sequence specifically under isothermal conditions. The objective of this study was to identify a Y chromosome-specific sequence in water buffalo and to establish an efficient procedure for embryo sexing by LAMP. The homologues of a Y chromosome-specific sequence, bovine repeat Y-associated.2, in swamp and river buffalo were cloned, and designated swamp buffalo repeat Y-associated.2 and river buffalo repeat Y-associated.2, respectively. Sexing by LAMP was performed using primers for swamp buffalo repeat Y-associated.2. A 12S rRNA was also amplified by LAMP as a control reaction in both male and female. The minimal amount of the template DNA required for LAMP appeared to be 0.1-10 pg. The sensitivity was further examined using swamp buffalo fibroblasts as templates. When fibroblasts were lysed with NaOH, the minimal cell number required for detection of both male-specific and male-female common DNA appeared to be two cells, whereas correct determination of sex could not be achieved using fibroblasts lysed by heat denaturation. Embryo sexing was also performed using blastomeres from interspecies nuclear transfer embryos. The sex determined by LAMP for blastomeres corresponded with the sex of nuclear donor cells in analyses using four or five blastomeres as templates. The LAMP reaction required only about 45 min, and the total time for embryo sexing, including DNA extraction, was about 1 h. In conclusion, the present procedure without thermal cycling and electrophoresis was reliable and applicable for water buffalo embryos.

Enrichment of in vitro maturation medium for buffalo (Bubalus bubalis) oocytes with thiol compounds: Effects of cystine on glutathione synthesis and embryo development

The purpose of this study was to evaluate whether enriching the oocyte in vitro maturation medium with cystine, in the presence of cysteamine, would improve the in vitro embryo production efficiency in buffalo by further increasing the GSH reservoir created by the oocyte during maturation. Cumulus-oocytes complexes were matured in vitro in TCM 199 + 10% FCS, 0.5 microg/ml FSH, 5 microg/ml LH and 1 microg/ml 17beta-estradiol in the absence or presence of cysteamine (50 microM), with or without 0.3mM cystine. In Experiment 1, glutathione content was measured by high-performance liquid chromatography and fluorimetric analysis in representative samples of oocytes matured in the four different experimental conditions. In Experiment 2, oocytes were fixed and stained to assess nuclear maturation and normal pronuclear development following IVM and IVF respectively. In Experiment 3, mature oocytes were in vitro fertilized and cultured to assess development to blastocysts. In all supplemented groups the intracytoplasmic GSH concentration was significantly higher than the control, with the highest GSH levels in oocytes matured in the presence of both thiol compounds (3.6, 4.7, 5.4 and 6.9 picomol/oocyte in the control, cysteamine, cystine and cystine+cysteamine groups, respectively; P < 0.05). Cystine supplementation of IVM medium, both in the presence or absence of cysteamine, significantly increased the proportion of oocytes showing two normal synchronous pronuclei following fertilization. In all supplemented groups, cleavage rate was significantly improved compared to the control (55, 66.1, 73.5 and 78.4% in the control, cysteamine, cystine and cystine+cysteamine groups, respectively; P < 0.05). Similarly, blastocyst yield was also increased in the three enriched groups compared to the control (17.1, 23.8, 29.3, 30.9% in the control, cysteamine, cystine and cystine+cysteamine groups, respectively; P < 0.05). Overall, the addition of cystine to a cysteamine-enriched medium resulted in a significant increase of cleavage rate and transferable embryo yield compared to the medium supplemented with only cysteamine.

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.

Embryonic mortality in buffaloes synchronized and mated by AI during the seasonal decline in reproductive function

The aim was to determine the factors that contribute to embryonic mortality in buffaloes mated by AI during a period of increasing day length which corresponds to a natural decline in reproductive activity. Italian Mediterranean buffalo cows (n=243) showing regular estrous cycles were synchronized using the Ovsynch-TAI program and mated by AI at 16 and 40 h after the second injection of GnRH. Blood samples were collected on Days 10 and 20 after the first AI and assayed for progesterone (P4). Pregnancy diagnosis was undertaken on Days 26 and 40 after the first AI using rectal ultrasonography. Buffaloes with a conceptus on Day 26 but not on Day 40 were judged to have undergone embryonic mortality and for these animals uterine fluid was recovered by flushing and analysed for common infectious agents. Estrus synchronization was achieved in 86% of buffaloes and the pregnancy rate on Day 40 was 34%. Embryonic mortality between Days 26 and 40 occurred in 45% of buffaloes and was associated with the presence of significant infectious agents in only 10 buffaloes (8%). Concentrations of P4 on Day 10 after AI were higher (P<0.05) in buffaloes that established a pregnancy than in buffaloes that showed embryonic mortality that was not associated with infectious agents. Similarly, on Day 20 after AI P4 concentrations were higher (P<0.01) in pregnant buffaloes compared with non-pregnant buffaloes and buffaloes that had embryonic mortality. It is concluded that a reduced capacity for P4 secretion can explain around 50% of embryonic mortalities in buffaloes synchronised and mated by AI during a period of low reproductive activity and that other as yet unidentified factors also have a significant effect on embryonic survival.

Influence of epidermal growth factor and insulin-like growth factor 1 on nuclear maturation and fertilization of buffalo cumulus oocyte complexes in serum free media and their subsequent development in vitro

The in vitro maturation, fertilization and development of Indian water buffalo (Bubalus sp.) cumulus oocyte complexes (COCs) to blastocysts were studied during culture, either in serum free tissue culture medium 199 (TCM 199) or Waymouth MB (WM). Based on different supplements added to these media, the experimental groups included: (a) no supplement (control); (b) hormones (FSH, LH and oestradiol) (c) Epidermal growth factor (EGF); (d) IGF-1; and (e) EGF + IGF-1. Experiments were conducted to note three end points: (1) nuclear maturation 24 h after culture (eight replicates); (2) fertilization 24 h after insemination (10 replicates); (3) development to blastocysts (nine replicates). The oocytes were cultured in groups of up to five per drop. Using a two-way (5 x 2) factorial model with interactions, the results were compared using generalized linear models with binomial errors and the logit link function. In experiment 1, the proportion of oocytes reaching metaphase II was higher for all the supplement treatments than the control treatment (t = 3.68, p < 0.0001). The proportion of oocytes reaching metaphase II was 74.7, 63.2, 64.7 and 81% with hormone (chi2 = 17.23, p < 0.0001), EGF (chi2 = 7.07, p = 0.007), IGF-1 (chi2 = 19.21, p = 0.002) and EGF + IGF-1 (chi2 = 33.04, p < 0.0001) supplementation, respectively, compared to 46.6% in the control (no supplement) group. Media did not have an effect on outcome. In experiment 2, the proportion of oocytes fertilized was significantly higher with hormones (31.0%, chi2 = 12.5, p = 0.0004), IGF-1 (35.7%, chi2 = 20.53, p < 0.0001), and the EGF + IGF-1 combination (49.7%, chi2 = 51.35, p < 0.0001) compared to control (16.2%). No significant effect of media was seen. In experiment 3, the proportion of oocytes that cleaved at 48 h after culturing was significantly higher for all supplement treatments compared to control. IGF-1 supplementation was the only treatment that did not produce a significantly higher rate of progression to blastocysts compared to the control. Once again, media had no effect on outcome. It was concluded that maturation, fertilization and development of buffalo oocytes were enhanced by all supplements tested. Enhancement was maximal with the combination of EGF+IGF-1. In contrast, no significant differences were found between the two types of media used.

Chemical activation of buffalo (Bubalus bubalis) oocytes by different methods: effects of aging on post-parthenogenetic development

The possibility of artificially inducing activation of MII buffalo oocytes may allow us to evaluate indirectly the quality of oocytes after in vitro maturation. The aim of this work was to compare buffalo embryo development after IVF and after chemical activation by two different agents. A further goal was to evaluate the effects of aging of oocytes on post-parthenogenetic and post-fertilization development. In Experiment 1 cumulus-oocyte complexes (COCs) were recovered from abattoir-derived ovaries and matured in vitro. After IVM the COCs were either fertilized in vitro (positive control) or activated with ethanol and ionomycin, both followed by immediate exposure to 6-diethylaminopurine (6-DMAP) for 4 h. In vitro culture (IVC) was carried out up to the blastocyst stage. In Experiment 2 COCs were matured in vitro for 18, 21, 24, 27 and 30 h before activation was triggered with ethanol, followed by 6-DMAP. In Experiment 3 COCs were fertilized in vitro at 18, 21, 24, 27 and 30 h post-maturation. Ethanol activation gave better results than the IVF control group, with higher cleavage rate (71.4 +/- 7.8 versus 55.8 +/- 5.8, respectively; P < 0.05) and a higher proportion of oocytes developing into morulae-blastocysts (32.6 +/- 6.5 versus 22.9 +/- 7.5, respectively; P < 0.05). Within the activation groups, ethanol supported the highest development in terms of cleavage (71.4 +/- 7.8 versus 59.4 +/- 10.7; P < 0.05) and morulae-blastocysts rate (32.6 +/- 6.5 versus 25.7 +/- 8.3; n.s.). It was also demonstrated that aging negatively affects post-parthenogenetic and post-fertilization development.

Telomerase Activity in Swamp Buffalo (Bubalus bubalis) Oocytes and Embryos Derived from In Vitro Fertilization, Somatic Cell Nuclear Transfer and Parthenogenetic Activation

The objective of this study was to examine the telomerase activity in swamp buffalo oocytes and pre-implantation stage embryos derived from in vitro fertilization (IVF), somatic cell nuclear transfer (NT) and parthenogenetic activation (PA). Immature and mature oocytes, and embryos at the 2-4 cell, 8-16 cell, morula and blastocyst stages produced by IVF, NT and PA were collected and the telomerase activity was assayed by using a Telomerase PCR ELISA kit. Telomerase activity was detected in all developmental stages evaluated from immature oocytes to blastocyst stage embryos. Telomerase activity was detected in higher amounts in immature as compared with mature oocytes (p < 0.05). Embryos derived from NT showed a profile of telomerase activity similar to that of IVF. In IVF and NT embryos, telomerase activity was low in the 2-4 cell and 8-16 cell stages, but the activity significantly increased (p < 0.05) at the morula stage, reaching its highest level at the blastocyst stage. In PA embryos, low levels of telomerase activity were detected from the 2-4 cell to the morula stage, and the highest level of telomerase activity was found at the blastocyst stage. Telomerase activity in NT blastocysts is higher than that derived from IVF and the activity is highest in PA blastocysts. These results suggest that the successful reprogramming of telomerase activity in buffalo NT embryos follow a pattern similar to that in embryos derived from IVF and PA.

Post-warming hatching and birth of live calves following transfer of in vitro-derived vitrified water buffalo (Bubalus bubalis) embryos

Viability of in vitro-derived vitrified-warmed preimplantation stage buffalo embryos were assessed in vitro and in vivo. Oocytes were collected from ovaries of slaughtered riverine buffaloes, matured and fertilized in vitro with frozen semen from riverine buffalo bull and cultured on cumulus cell monolayers. Resultant preimplantation stage embryos were cryopreserved by vitrification with ethylene glycol, ficoll and sucrose. Seventy-one frozen embryos were warmed in 0.5M sucrose and were further cultured in vitro for 72 h to assess hatching rate. On the other hand, 95 embryos were transferred non-surgically to riverine buffalo recipients to assess development competence in vivo through detection of pregnancy and birth of live calves. Hatching rate of 83.10% (59/71) was noted among embryos cultured in vitro. Pregnancy rate was 16.36% (9/55) while calving rate was 10.91% (6/55) after transfer of in vitro-derived vitrified-warmed embryos to recipient animals. Six healthy and normal calves with average birth weight of 38.75+/-3.55 kg were born from the transferred embryos. These results indicate the viability of vitrified in vitro-derived buffalo embryos and the potential application of in vitro embryo production and vitrification techniques for production and transport of buffalo embryos from germplasm-rich sources to guarantee genetic improvement in many parts of the world.

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.

Development of swamp buffalo (Bubalus bubalis) embryos after parthenogenetic activation and nuclear transfer using serum fed or starved fetal fibroblasts

The knowledge of oocyte activation and somatic cell nuclear transfer in the swamp buffalo (Buballus bubalis) is extremely rare. The objectives of this study were the following: (1) to investigate the various activation treatments on the parthenogenetic development of buffalo oocytes, (2) to examine the events of nuclear remodeling and in the in vitro development of cloned buffalo embryos reconstructed with serum fed or starved fetal fibroblasts, and (3) to investigate the in vivo development of cloned embryos derived from serum fed or starved cells after transfer into the recipients. The rates of cleavage and blastocyst development were found to be significantly higher (P < 0.05) when the oocytes were activated by the combination treatment of calcium ionophore (A23187) or ethanol followed by 6-DMAP than those activated by electrical pulses and 6-DMAP or other single treatments. Flow cytometric analysis revealed that the percentage in the G0/G1 phase in serum starved cells was significantly (P < 0.05) higher than that in serum fed cells (88.8 +/- 6.2 vs. 68.2 +/- 2.6). At 1 h post fusion (hpf), most of the transferred nuclei (71%) from serum fed cells did not change in size, and the nuclear envelope remained intact, whereas 29% underwent NEBD and PCC. When serum starved cells were used, 83% of the transferred nuclei underwent NEBD and PCC whereas 17% remained intact. The nuclear swelling and pronucleus (PN) formation were observed at 2-4 and 12 h post activation (hpa), respectively. The remodeled nuclei underwent mitotic division and developed to the 2-cell stage within 18-24 hpa. Fifty-five percent of oocytes reconstructed with serum fed cells were 2PN and 45% were 1PN, whereas 79% of the embryos reconstructed from starved cells were 1PN and 21% were 2PN. The percentage of blastocyst development of the embryos derived from starved cells was higher than that from the serum fed cells (35% vs. 21%, P < 0.05). Pregnancy was detected after the transfer of cloned blastocysts into the recipients but no recipients supported the development to term. The results of this work can be used to establish effective activation protocols for buffalo oocytes which can be used during nuclear transfer experiments.

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.

Glutathione synthesis during in vitro maturation of buffalo (Bubalus bubalis) oocytes: effects of cysteamine on embryo development

It was demonstrated that cysteamine supplementation during in vitro maturation (IVM) improves embryo development by increasing glutathione (GSH) synthesis in several species. An improved developmental competence of oocytes matured in the presence of cysteamine was also recorded in buffalo species. The purpose of this work was to investigate (1) if glutathione is de novo synthesized during in vitro maturation of buffalo oocytes, (2) if cysteamine improves buffalo embryo development via an increase in GSH synthesis, and (3) if the inhibition of glutathione synthesis by buthionine sulfoximide (BSO), in the presence or absence of cysteamine, affects subsequent embryo development and GSH synthesis.Cumulus-oocytes complexes (COCs), recovered from slaughtered animals, were matured in vitro in TCM199+10% fetal calf serum (FCS), 0.5 microg/ml FSH, 5 microg/ml LH and 1 microg/ml 17-beta-estradiol in the absence or presence of cysteamine (50 microM), with or without 5mM BSO. Glutathione content was measured by high-performance liquid chromatography (HPLC) and fluorimetric analysis in immature oocytes and in oocytes matured in the different experimental conditions. In a second experiment, the mature oocytes were in vitro fertilized and cultured for 7 days in order to assess development to blastocysts (BLs). It was demonstrated that buffalo oocytes synthesize glutathione during in vitro maturation and that cysteamine increases glutathione synthesis. Furthermore, the promoting effects of cysteamine on embryo development and GSH synthesis were neutralized by buthionine sulfoximide. These results indicate that glutathione plays a critical role on buffalo embryo development.

Microvascular architecture of the fetal cotyledons in water buffaloes (Bubalus bubalis) during different stages of pregnancy

To elucidate the morphological background of physiological differences between bovine and buffalo gestation forty-two placentae ranging from the 3rd to 10th month of pregnancy were used to study the microvascular architecture of the fetal cotyledons in the buffalo. The tissues were prepared for light and scanning electron microscopy by paraformaldehyde fixation and corrosion casting of the fetal cotyledonary vascular system. Histology and vascular casts revealed the buffalo fetal cotyledons to consist of a series of conical villous trees changing from a wide to slender shape during pregnancy, and with a base strictly facing the fetal side. The branches of these trees, intermediate and terminal villi, projected radially from the stem, thus representing a rough type of villous tree. A second type of tree lacked these branches and was therefore termed smooth villus. The rough type was most prevalent, and the intermediate and terminal villi showed capillary complexes arranged in stories by the 4th to 5th month of gestation. The stories became broader and denser with the progress of pregnancy (6th to 7th month of gestation), due to extensive growth of new capillaries and simultaneous development of convolutions causing the vascular ridges of the terminal villi to appear bushy. Near term (9th to 10th month) the capillary system became very dense, particularly at the margin of the vascular ridges, leaving only narrow spaces for the corresponding maternal septal tissue. In detail, at its base the trunk of each villous tree contained a single central stem artery which originated from the allantochorionic arterial system, and 1-3 parallel peripheral stem veins. When approaching the cone tip, these vessels branched into new stem arteries and veins, each giving rise to arterioles and venules according to the principle vascularization of the stem villus first, followed by intermediate and terminal villi. The capillary complex of the terminal villi consisted of arterial capillary limbs, capillary loops with sinusoidal dilatations and anastomoses, and venous capillary limbs. The latter converged into venules of terminal and intermediate villi which joined stem veins leading into allantochorionic veins. In conclusion, the fetal vasculature of the buffalo placentome was greatly increased from early pregnancy to near term. This was denoted by the general development of stem villous trees and an increase in the volume and density of the capillary system of the terminal villi, reflecting the increasing need of materno-fetal substance exchange in the buffalo placenta, particularly near term.

Developmental failure of hybrid embryos generated by in vitro fertilization of water buffalo (Bubalus bubalis) oocyte with bovine spermatozoa

The developmental potential of inter-species hybrid embryos produced by in vitro fertilization of in vitro matured buffalo oocytes with bovine spermatozoa was studied with a view to investigate pre-implantation embryo development and its gross morphology, early embryonic gene expression, and embryonic genome activation. Fertilization events with both buffalo and cattle spermatozoa were almost similar. Overall fertilization rate with cattle spermatozoa was 78.4% was not significantly different from that of buffalo spermatozoa (80.2%). Initial cleavage rate between buffalo and hybrid embryo was also similar, and there was no significant difference in their developmental rate till 8-cell stage (26.0 +/- 4.1 vs. 24.3 +/- 4.8). However, only 5.3% of hybrid embryos developed into blastocyst stage compared to 21.7% in buffalo. mRNA phenotyping of insulin-like growth factor family (Insulin, insulin receptor, IGF-I, IGF-I receptor, IGF-II, and IGF-II receptor) and glucose transporter isoforms (GLUT-I, II, III, IV) in hybrid embryos clearly showed that these molecules were not expressed after 8-cell stage onward. Similarly, as observed in buffalo embryos, incorporation of (35)S-methionine and (3)H-uridine could not be observed in hybrid embryos from 8-cell stage onward. This suggests that the maternal-zygotic genome activation did not occur in hybrid embryos. Differential staining also showed that the blastomere stopped dividing after 8-cell stage. Collectively, these parameters clearly showed that there was developmental failure of hybrid embryos.

Buffalo and cattle hybrid embryo development is decreased by caffeine treatment during in vitro fertilization

Water buffalo are renowned for difficulties in the implementation of assisted reproductive technologies, with both males and females being problematic. In this study, we used cattle oocytes to assess the effect of treatments with heparin and caffeine on buffalo spermatozoa and subsequent fertilization and embryo development in vitro. There was no significant difference between buffalo and bovine spermatozoa in the events associated with fertilization. Fertilization of cattle oocytes with buffalo spermatozoa resulted in 7.8% of oocytes developing into hybrid embryos. A difference in the developmental capability of hybrid embryos compared with the cattle control was observed. This has not been previously reported. The subsequent transfer of a limited number of hybrid embryos did not produce a viable pregnancy. However, control treatments in this experiment also failed to achieve pregnancy, so objective data is not available to provide conclusions about the developmental competence of the buffalo and cattle hybrid embryos. Optimal spermatozoa capacitation treatments achieved 61% fertilization and 21% zygote cleavage into two cell embryos. There was no significant difference in fertilization or development due to heparin or spermatozoa concentrations. However, treatment of buffalo and cattle spermatozoa with caffeine significantly decreased embryo cleavage but also tended to decrease embryo development to the blastocyst stage. These studies suggest that problems with reproduction in buffalo may reside with biological mechanisms associated with the oocyte that are often complicated by poor male reproductive performance. Selection for bull fertility would prevent some of these complications.

Sex determination of buffalo embryos (Bubalus bubalis) by polymerase chain reaction

The aim of this study was to identify a simple, rapid method for sex determination of in vitro produced buffalo embryos, amplifying Y-chromosome-specific repeat sequences by polymerase chain reaction (PCR). Buffalo oocytes collected from slaughtered animals were matured, fertilised and cultured in vitro for 7 days. On day 7 embryos were evaluated and divided in to six groups according to developmental stage (2, 4, 8, 16 cells, morulae and blastocyst). Each embryo was stored singly in phosphate-buffered saline at -20 degrees C until PCR. Two different methods of extraction of DNA were compared: a standard procedure (ST), using a normal extraction by phenol-chloroform, isoamyl alcohol and final precipitation in absolute ethanol and a direct procedure (DT), using a commercial kit (Qiaquik-Qiagen mini blood). A pair of bovine satellite primers and two pairs of different bovine Y-chromosome-specific primers (BRY4.a and BRY.1) were used in the PCR assay on embryos and on whole blood samples collected from male and female adult buffaloes, used as control. The trial was carried out on 359 embryos (193 for ST and 166 for DT). When DNA samples from blood were amplified, the sex determined by PCR always corresponded to the anatomical sex. Embryo sexing was not possible in two embryos in ST and one embryo in DT. Both extraction protocols recovered sufficient quantities of target DNA at all developmental stages, but the time required for the ST (24 h) limits its use in embryo sexing and supports the use of commercial extraction kits (5 h).

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.

Somatic cell cloning in Buffalo (Bubalus bubalis): effects of interspecies cytoplasmic recipients and activation procedures

Successful nuclear transfer (NT) of somatic cell nuclei from various mammalian species to enucleated bovine oocytes provides a universal cytoplast for NT in endangered or extinct species. Buffalo fetal fibroblasts were isolated from a day 40 fetus and were synchronized in presumptive G(0) by serum deprivation. Buffalo and bovine oocytes from abattoir ovaries were matured in vitro and enucleated at 22 h. In the first experiment, we compared the ability of buffalo and bovine oocyte cytoplasm to support in vitro development of NT embryos produced by buffalo fetal fibroblasts as donor nuclei. There were no significant differences (p > 0.05) between the NT embryos derived from buffalo and bovine oocytes, in fusion (74% versus 71%) and cleavage (77% versus 75%) rates, respectively. No significant differences were also observed in blastocyst development (39% versus 33%) and the mean cell numbers of day 7 cloned blastocysts (88.5 +/- 25.7 versus 51.7 +/- 5.4). In the second experiment, we evaluated the effects of activation with calcium ionophore A23187 on development of NT embryos after electrical fusion. A significantly higher (p < 0.05) percentage of blastocyst development was observed in the NT embryos activated by calcium ionophore and 6-DMAP when compared with 6-DMAP alone (33% versus 17%). The results indicate that the somatic nuclei from buffalo can be reprogrammed after transfer to enucleated bovine oocytes, resulting in the production of cloned buffalo blastocysts similar to those transferred into buffalo oocytes. Calcium ionophore used in conjunction with 6-DMAP effectively induces NT embryo development.

In vitro production of cattle-water buffalo (Bos taurus--Bubalus bubalis) hybrid embryos

Interspecific hybrid embryos are useful models for the study of maternal-fetal interactions, transmission pattern of species-specific markers and parental contributions to growth and developmental potential of pre-attachment embryos. In an attempt to investigate the possibility of producing hybrid embryos of domestic cattle (Bos taurus) and water buffalo (Bubalus bubalis), cattle oocytes were exposed to buffalo sperm and buffalo oocytes were exposed to cattle sperm and the cleavage rate and the post-fertilisation features of hybrid embryos up to the blastocyst stage were compared with those of buffalo and cattle embryos. The cleavage rate in buffalo oocytes exposed to cattle sperm was low (40.8%), with only 8.8% of these hybrid embryos reaching the blastocyst stage. Cattle oocytes exposed to buffalo sperm showed 86.3% cleavage, while 25.9% of these attained the blastocyst stage. The speed of development of both types of hybrids was intermediate between that of cattle and buffalo embryos, with hatching occurring on day 7.5 in hybrid embryos, day 8-9 in cattle and day 7 in buffalo. The proportions of cells contributing to the trophectoderm and the inner cell mass were closer to those of the maternal species in both types of hybrid embryos. Our results indicate that cattle-water buffalo hybrid embryos produced using inter species gametes are capable of developing to advanced blastocyst stages and that their in vitro fate, and developmental potential, are influenced by the origin of the oocyte.

Morphostructural changes of the kidney microvasculature during the prenatal period in Bubalus bubalis

The microcirculation of the foetal kidney was studied in the buffalo using light (LM) and scanning electron microscopy (SEM). The primordial glomerules originated from the peripheral zone of the metanephros at the stage of 8 cm CRT. The glomerular capillaries started to differentiate at the stage of 10-15 cm CRT. They were sparse and showed a few primordial pores. In addition, they began to make contacts with primordial podocytes. At the stage of 40-60 cm CRT, the renal microcirculation showed a complex and almost completely organized morphology.

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

Techniques for in vitro production (IVP) of buffalo embryos adopting the procedures developed in cattle have received increasing interest in the recent times. A high oocyte maturation, fertilization and cleavage rate and a low rate of blastocyst yield and calving following transfer of in vitro produced buffalo embryos have been obtained. The efficiency of IVP in buffalo is much lower than that in cattle. Several problems need to be resolved before IVP technology can be used regularly in buffalo breeding. This review attempts to present an overview of the different techniques used in buffalo to produce transferable embryos in vitro, namely in vitro maturation and fertilization of immature oocytes and in vitro development of the resulting cleaved embryos to the blastocyst stage before transfer. The problems associated with IVP, the possible solutions and the new biotechniques linked to IVP are discussed.

Timing of sequential changes in cumulus cells and first polar body extrusion during in vitro maturation of buffalo oocytes

Studies were conducted to investigate the degree of the cumulus cell expansion and expulsion of the first polar body in relation to time of incubation in three different culture media during in vitro maturation of buffalo oocytes and to suggest a suitable practical method for assessment of in vitro maturation rate of buffalo oocytes. Buffalo oocytes were aspirated from ovaries collected from a local slaughterhouse. Only oocytes with more than two layers of cumulus cells and homogenous ooplasm were cultured into 50 microl droplets of three different culture systems: (1) TCM-199 + steer serum (10%): (2) TCM-199 + steer serum (10%) + PMSG (40 IU/ml); and (3) TCM-199 + steer serum (10%) + PMSG (40 IU/ml) + estradiol 17beta (1 microg/ml) in a 35 mm Petri dish. The droplets were covered with warm (39 degrees C) mineral oil and incubated in a CO2 incubator (39 degrees C, 5% CO2 in air, 90-95% relative humidity) for 16-18, 20, 22, and 24 h. The maturation rate was assessed by evaluation of degree of cumulus cells expansion and identifying first polar body extrusion into the perivitelline space under stereo zoom microscope. Matured oocytes were inseminated in vitro with 9-10 million sperm/ml of Brackett and Oliphant (BO) medium. Cleaved embryos were cultured in TCM-199 supplemented with steer serum (10%) for 8 days. Cumulus expansion and extrusion of first polar body commenced at 16 and 17 h, respectively, of buffalo oocyte culture. These events mainly exhibited during 22-24 h of culture. Oocytes with Degrees 1 and 2 cumulus cells expansion and extruded first polar body in degree 0 oocytes may be considered as matured and can be used in IVF studies.

In vitro embryo production in buffalo species: state of the art

In the last several years, there has been an increasing interest in in vitro embryo production (IVEP) technologies for faster propagation of superior germplasm in buffalo because of the low efficiency of superovulation (SO) and embryo transfer (ET) programs in this species. Although the IVEP efficiency has improved, embryo yield and development to term are still very low. This paper reviews the progress made in optimizing the IVM, IVF, and IVC systems. It also highlights the importance of embryo cryopreservation, which might critically contribute to the diffusion of ET procedures in the field. The acquisition of more information on embryo physiology, metabolism, and culture requirements in this species is critical to optimize the efficiency of advanced reproductive strategies. Further studies are also needed to improve the cryopreservation of IVEP embryos. The second part of the work underlines the potential impact of ovum pick-up (OPU) technique combined with IVEP on genetic improvement of buffalos. The OPU technique is a non-invasive and repeatable procedure for recovering large numbers of meiotically competent oocytes from antral follicles of live animals. Our experience, in buffalo, has demonstrated that OPU is superior to SO because it can yield more transferable embryos (TE) per donor on a monthly basis (2 TE vs 0.6, respectively). Therefore this technology has great potential to improve the genetic progress of buffalo through the maternal lineage.

Influence of oocyte quality, culture media and gonadotropins on cleavage rate and development of in vitro fertilized buffalo embryos

The present study was designed to examine the influence of oocyte quality, culture media and gonadotropins on cleavage rate and development of in vitro fertilized buffalo embryos. Three experiments were conducted. In experiment 1, oocytes were classified by number of cumulus cell layers and morphology of the ooplasm as good, fair or poor. Oocytes were cultured for IVM, IVF and IVC in CR1aa medium. In experiment 2, good quality oocytes were cultured for maturation in: (1) CR1aa; (2) CR2aa; (3) TCM-199; (4) MEM or (5) RPMI-1640, and then fertilized using frozen thawed buffalo spermatozoa in CR1aa. The oocytes were cultured in the same medium used for maturation after fertilization. In experiment 3, oocytes were classified into three groups: group (1) was without gonadotropin and serve as a control; group (2) in which IVM medium was supplemented with 10microg/ml FSH and group (3) in which IVM medium was supplemented with 10IUml(-1) eCG. In all experiments, oocytes were kept at 38.5 degrees C under 5% CO(2) for IVM, IVF, IVC and examined for cleavage and embryo development rates on days 3 and 8, respectively. Good and fair quality oocytes produced a higher cleavage rate (P<0.01) than poor quality oocytes. Morula production rate was also higher (P<0.01) for good as compared with fair quality oocytes. Embryo development with poor quality oocytes was arrested at the two to sixteen cell stage. In experiment 2, the cleavage rate was higher (P<0.05) in CR1aa than CR2aa, and higher (P<0.01) than TCM-199, MEM and RPMI-1640. The numbers of morulae and blastocysts were higher (P<0.01) for oocytes cultured in CR1aa and CR2aa media than TCM-199 or MEM. In experiment 3, the addition of FSH or eCG to the maturation medium increased (P<0.01) cleavage and developmental rates of buffalo embryo compared with control medium. In conclusion, the IVM of good quality buffalo oocytes in CR1aa or CR2aa medium and the addition of FSH or eCG in maturation medium produced higher cleavage and developmental rates of IVF buffalo embryos.