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Oliveira C.S.,Sao Paulo State University | Oliveira C.S.,Embrapa Dairy Cattle Research Center | Saraiva N.Z.,Sao Paulo State University | Cruz M.H.C.,Sao Paulo State University | And 4 more authors.
Reproduction | Year: 2013

During initial development, both X chromosomes are active in females, and one of them must be silenced at the appropriate time in order to dosage compensate their gene expression levels to male counterparts. Silencing involves epigenetic mechanisms, including histone deacetylation. Major X chromosome inactivation (XCI) in bovine occurs between hatching and implantation, although in vitro culture conditions might disrupt the silencing process, increasing or decreasing X-linked gene expression. In this study, we aimed to address the roles of histone deacetylase inhibition by trichostatin A (TSA) on female preimplantation development.We tested the hypothesis that by enhancing histone acetylation, TSA would increase the percentage of embryos achieving 16-cell stage, reducing percentage of embryos blocked at 8-cell stage, and interfere with XCI in IVF embryos. We noticed that after TSA treatment, acetylation levels in individual blastomeres of 8-16 cell embryos were increased twofold on treated embryos, and the samewas detected for blastocysts. Changes among blastomere levels within the same embryo were diminished on TSA group, as low-acetylated blastomeres were no longer detected. The percentage of embryos that reached the 5th cleavage cycle 118 h after IVF, analyzed by Hoechst staining, remained unaltered after TSA treatment. Then, we assessed XIST and G6PD expression in individual female bovine blastocysts by quantitative real-time PCR. Even though G6PD expression remained unaltered after TSA exposure, XIST expression was eightfold decreased, and we also detected a major decrease in the percentage of blastocysts expressing detectable XIST levels after TSA treatment. Based on these results, we conclude that HDAC is involved on XCI process in bovine embryos, and its inhibition might delay X chromosome silencing and attenuate aberrant XIST expression described for IVF embryos. © 2013 Society for Reproduction and Fertility. Source

Lessard C.,Agriculture and Agri Food Canada | Lessard C.,University of Saskatchewan | Siqueira L.G.,Embrapa Dairy Cattle Research Center | D'Amours O.,Laval University | And 3 more authors.
Theriogenology | Year: 2011

The objective of this case report was to identify the cause of apparent idiopathic infertility in a Red Angus (beef) bull. Semen was collected by electroejaculation and submitted to a series of assays, including evaluation of sperm motility by computer-assisted sperm analysis (CASA), sperm morphology and DNA integrity, semen cryopreservation, AI, IVF, induction of the acrosome reaction, and determination of the level of sperm proteins associated with bull fertility potential. Total (92 ± 2%) and progressive (79 ± 4%) sperm motility; sperm concentration (1647 ± 429 10 6 sperm/mL); proportions of morphologically normal sperm (83 ± 6%) and DNA integrity (96 ± 2), and acrosome-intact sperm (64 ± 4%) exceeded minimum acceptable values. Frozen sperm had good total (58.7 ± 6.7%) and progressive (43.9 ± 9.2%) motility immediately after thawing. However, AI of 16 heifers resulted in no pregnancies and blastocyst production rate (following IVF using sperm from this infertile bull) was nearly identical to that produced using dead sperm (a control of parthenogenesis; 2 ± 2 and 2 ± 3%; respectively P < 0.05). Treatment with a calcium ionophore (A23187) failed to induce the acrosome reaction in sperm from the infertile bull (P < 0.05). Evaluation of several proteins associated with the fertility potential of bulls revealed that the level of Binder Sperm Protein-1 (BSP1), known to be associated with the capacitation process, was much greater on sperm from the infertile bull compared to that of his sire. In conclusion, we inferred that the idiopathic infertility in this bull was caused by a failure to complete the capacitation process. © 2011 Elsevier Inc. Source

Souza J.M.G.,Federal University of Vicosa | Torres C.A.A.,Federal University of Vicosa | Maia A.L.R.S.,Federal University of Fluminense | Brandao F.Z.,Federal University of Fluminense | And 4 more authors.
Animal Reproduction Science | Year: 2011

Intravaginal progesterone devices are used worldwide for estrus induction in goats. Reused devices are able to induce estrus; however, this can be a health risk within a flock. The objective was to compare new and previously used (and autoclaved) progesterone-releasing intravaginal devices for induction of estrus and ovulation in seasonally anestrous Toggenburg goats. Anestrous goats (n=42) received new intravaginal devices containing 0.3. g progesterone (CONTROL), or similar devices previously used for either 6 (USED6) or 12. d (USED12) and subsequently autoclaved. All goats received 5. mg dinoprost at device insertion and 200 IU eCG 5. d later, and all devices were removed after 6. d. After device removal, estrus was monitored and females displaying signs of estrus were mated by fertile bucks. Transrectal ovarian ultrasonography was performed after device removal until detection of ovulation. Blood samples were collected for determination of plasma progesterone concentration at different times. There was no difference (P>0.05) among groups CONTROL, USED6 or USED12 for: estrus response (87, 100 or 100%, respectively); duration of estrus (32.3±2.3, 25.2±3.4 or 27.3±4.1. h); ovulation rate (100, 88 or 100%); number of ovulations (1.5±0.2, 1.9±0.3 or 1.7±0.3); and pregnancy rate (60, 58 or 67%). Plasma progesterone (P4) concentrations were greater (P<0.05) in CONTROL than in USED6-treated and USED12-treated goats (7.2±1.2, 4.7±0.7 and 4.3±0.6. ng/mL, respectively) at 6. h after device insertion; these differences were maintained until 4. d after device insertion (3.4±0.4, 2.3±0.2, and 2.5±0.2. ng/mL). Overall, plasma progesterone concentrations were greater (P<0.05) in nulliparous than in lactating goats (3.1±0.8 compared to 2.4±0.6. ng/mL, respectively). In conclusion, autoclaved, previously used intravaginal progesterone-releasing devices resulted in significant lesser plasma progesterone concentrations than new devices, but were similarly effective in inducing estrus and ovulation in anestrous goats. © 2011 Elsevier B.V. Source

Auad A.M.,Embrapa Dairy Cattle Research Center | Resende T.T.,Embrapa Dairy Cattle Research Center | da Silva D.M.,Federal University of Lavras | das Gracas Fonseca M.,Embrapa Dairy Cattle Research Center
Agroforestry Systems | Year: 2012

The objective of this work was to estimate the abundance, diversity and constancy of families from the order Hymenoptera, such as the seasonality of those through a survey on the insect population in a silvopastoral system. We installed a Malaise-type trap in a Brachiaria decumbens area managed by a silvopastoral system in Coronel Pacheco, MG, from August 2006 to July 2008. The trapped insects were screened, and those of the order Hymenoptera were classified into their respective family categories and quantified. We adopted the methodology of Bodenheimer to calculate the indices of constancy, while other indices were estimated PAST program. We sampled 5841 specimens in total, which included 549 morphospecies and were distributed among 11 families. Of the total specimens sampled, 80% were Formicidae, which besides being the most abundant, was also the most diverse and constant family. When entomophagous insects were analyzed, the highest values for these indices were recorded for the families Ichneumonidae, Braconidae, and Vespidae. Pollinators were less prevalent compared to the total number of sampled individuals. The population density in the Hymenoptera was not correlated between the two sampling years and climate factors. © 2011 Springer Science+Business Media B.V. Source

Viana J.H.M.,Embrapa Dairy Cattle Research Center | Palhao M.P.,Federal University of Vicosa | Siqueira L.G.B.,Embrapa Cerrados | Fonseca J.F.,Embrapa Goats and Sheep Research Center | Camargo L.S.A.,Embrapa Dairy Cattle Research Center
Theriogenology | Year: 2010

The objective of this study was to evaluate ovarian follicular dynamics during intervals between successive ovum pick-up (OPU) and determine its effects on the number and quality of recovered cumulus-oocyte complexes (COCs) in Zebu cows (Bos indicus). Pluriparous nonlactating Gyr cows (Bos indicus; n = 10) underwent four consecutive OPU sessions at 96-h intervals. The dynamics of ovarian follicular growth between OPU sessions was monitored by twice-daily ultrasonographic examinations. A single dominant follicle (DF) or two codominant (CDF) follicles (>9 mm) were present in 63.3% (19 of 30) of intervals studied, with follicle deviation beginning when the future dominant follicle (F1) achieved a diameter of 6.2 ± 0.3 mm. The phenomenon of codominance was observed in four (13.3%) of the inter-OPU intervals. The remaining intervals (36.6%, 11 of 30) were characterized by a greater follicular population, lower rate of follicular growth, and a smaller diameter F1 (P < 0.0001). There was a tendency (P = 0.08) toward an increase in the number of recovered COCs when dominant follicles were not present (NDF). The quality of COCs was not affected by the presence of a single dominant follicle, but codominant follicles resulted in recovery of a lower proportion of viable embryos (40.0%, 62.1%, and 63.6%; P < 0.05) and higher proportions of degenerate COCs (56.0%, 30.3%, and 28.6%; P < 0.05) for CDF, NDF, and DF respectively. We concluded that, in Zebu cows, (a) repeated follicle aspirations altered ovarian follicular dynamics, perhaps by increasing follicular growth rate; (b) follicular dominance could be established in cows undergoing twice-a-week OPU; and (c) the presence of a dominant follicle during short inter-OPU intervals may not affect COC quality, except when a codominant follicle was present. © 2010 Elsevier Inc. All rights reserved. Source

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