Local regulation of antral follicle development and ovulation in monovulatory species

The identification of mutations in the genes encoding bone morphogenetic protein 15 (BMP15) and growth and differentiation factor 9 (GDF9) associated with phenotypes of sterility or increased ovulation rate in sheep aroused interest in the study of the role of local factors in preantral and antral folliculogenesis in different species. An additive mutation in the BMP15 receptor, BMPR1b, which determines an increase in the ovulatory rate, has been introduced in several sheep breeds to increase the number of lambs born. Although these mutations indicate extremely relevant functions of these factors, the literature data on the regulation of the expression and function of these proteins and their receptors are very controversial, possibly due to differences in experimental models. The present review discusses the published data and preliminary results obtained by our group on the participation of local factors in the selection of the dominant follicle, ovulation, and follicular atresia in cattle, focusing on transforming growth factors beta and their receptors. The study of the expression pattern and the functionality of proteins produced by follicular cells and their receptors will allow increasing the knowledge about this local system, known to be involved in ovarian physiopathology and with the potential to promote contraception or increase the ovulation rate in mammals

Analysis of nuclear maturation, DNA damage and repair gene expression of bovine oocyte and cumulus cells submitted to ionizing radiation

Radiotherapy causes destruction of tumor cells, but also threatens the integrity and survival of surrounding normal cells. Then, woman submitted to irradiation for cancer treatment may present permanent ovary damage, resulting in impaired fertility. The objective of this study was to investigate the effects of therapeutic doses of ionizing radiation (IR), used for ovarian cancer treatment in humans, on bovine cumulus-oocyte complexes (COCs) as experimental model. Bovine ovaries were exposed to 0.9 Gy, 1.8 Gy, 3.6 Gy or 18.6 Gy IR, and then COCs were collected and used to evaluate: (a) oocyte nuclear maturation; (b) presence of phosphorylated H2A.X (γH2AX), as an indicator of DNA double-strand breaks (DSBs); and (c) expression of genes involved in DNA repair (TP53BP1, RAD52, ATM, XRCC6 and XRCC5) and apoptosis (BAX). The radiation doses tested in this study had no detrimental effects on nuclear maturation and did not increase γH2AX in the oocytes. However, IR treatment altered the mRNA abundance of RAD52 (RAD52 homolog, DNA repair protein) and BAX (BCL2-associated X protein). We conclude that although IR doses had no apparent effect on oocyte nuclear maturation and DNA damage, molecular pathways involved in DNA repair and apoptosis were affected by IR exposure in cumulus cells

Transforming growth factor-beta family members are regulated during induced luteolysis in cattle

The transforming growth factors beta (TGFβ) are local factors produced by ovarian cells which, after binding to their receptors, regulate follicular deviation and ovulation. However, their regulation and function during corpus luteum (CL) regression has been poorly investigated. The present study evaluated the mRNA regulation of some TGFβ family ligands and their receptors in the bovine CL during induced luteolysis in vivo. On day 10 of the estrous cycle, cows received an injection of prostaglandin F2α (PGF) and luteal samples were obtained from separate groups of cows (n= 4-5 cows per time-point) at 0, 2, 12, 24 or 48 h after treatment. Since TGF beta family comprises more than 30 ligands, we focused in some candidates genes such as activin receptors (ACVR-1A, -1B, -2A, -2B) AMH, AMHR2, BMPs (BMP-1, -2, -3, -4, -6 and -7), BMP receptors (BMPR 1A, -1B and -2), inhibin subunits (INH-A, -BA, -BB) and betaglycan (TGFBR3). The mRNA levels of BMP4, BMP6 and INHBA were higher at 2 h after PGF administration (P<0.05) in comparison to 0 h. The relative mRNA abundance of BMP1, BMP2, BMP3, BMP4, BMP6, ACVR1B, INHBA and INHBB was upregulated up to 12 h post PGF (P<0.05). On the other hand, TGFBR3 mRNA that codes for a reservoir of ligands that bind to TGF-beta receptors, was lower at 48 h. In conclusion, findings from this study demonstrated that genes encoding several TGFβ family members are expressed in a time-specific manner after PGF administration

Does combining estradiol cypionate and GnRH for ovulation induction in recipient cows increase pregnancy rate after timed embryo transfer?

Estradiol cypionate (EC) or GnRH have been widely used for ovulation induction in timed embryo transfer (TET). EC administration increases the proportion of cows that show estrus, whereas GnRH promotes more synchronized ovulations. The aim of the present study was to evaluate the potential beneficial effects of combining EC and GnRH in TET. In experiment 1, no difference was observed on serum progesterone concentrations on Day 6 and 13 after GnRH treatment between GnRH and EC+GnRH groups. In experiment 2, pregnancy per embryo transfer (P/ET) did not differ (p = 0.69) between GnRH (62.8%) and EC+GnRH (58.7%) groups. In conclusion, combining EC and GnRH for ovulation induction does not increase progesterone secretion and pregnancy rate after TET in cattle

Regulatory mechanisms in cumulus expansion, oocyte maturation and block to polyspermy in mammals

The main purpose of this dissertation was to determine the effect of gonadotropins and the interaction between different second messengers on regulation of cumulus expansion and cytoplasmic maturation. The first objective was to verify the effect of gonadotropins on mucification of cumulus cells and on cytoplasmic maturation of mouse oocytes using a serum-free medium. Percentages of fertilized oocytes were greater (p $<$ 0.05) when LH was present. In contrast, expansion of cumulus cells was only observed when COC were matured in the presence of FSH. The percentage of male and female pronuclei formation after 5 h of incubation with sperm was significantly reduced in penetrated oocytes (p $<$ 0.02) suggesting that FSH delays cytoplasmic maturation. Development to two-cell embryos was not affected by the presence of gonadotropins in the oocyte maturation medium.The second objective of this study was to investigate the effect of fetuin (a proteinase inhibitor) in the block to polyspermy. The inhibition of proteinases during fertilization induced polyspermy in 52.4% of the eggs. A significant reduction in the percentage of polyspermic eggs over time following penetration (F = 7.34; p = 0.0190) occurred. Structures similar to cytoplasmic blebs were observed in some eggs cultured for 6 and 24 hours. The results demonstrate that fetuin inhibits the block to polyspermy when present in the fertilization medium. More relevant was the demonstration of a mechanism for eliminating supernumerary sperm from within the egg.Finally, an investigation was undertaken on the role of cAMP, Ca\sp{\rm 2+}-calmodulin (CaM), diacylglycerol (DG) and the interaction between these intracellular messengers on the mucification of the cumulus cells. Activators of protein kinase A stimulated cumulus expansion while activators of protein kinase C induced mucification of cumulus cells only under conditions that increased levels of cAMP. Effect of activators of protein kinase A to stimulate cumulus expansion was totally suppressed by an inhibitor of the Ca\sp{\rm 2+}CaM complex (W7). The compounds were not toxic since their effects were reversible. These results suggest that not only cAMP but other intracellular messengers such as Ca\sp{\rm 2+}-CaM complex and DG are involved and interact in the regulation of cumulus expansion.U of I OnlyETDs are only available to UIUC Users without author permissio

Suplementação de progestágenos no pré-parto em suínos : estratégia para facilitar assistência aos leitões e evitar partos precoces

Gestation length in swine has a considerable amplitude and both early and delayed parturition are common. This variation increases the occurrence of unassisted farrowing and could lead to a wide-ranging age at weaning for piglets born from one batch. Supervision of sow parturition is crucial to reduce mortality of neonate piglets. To facilitate assistance, induction of farrowing using prostaglandin F2α (PGF) has been widely used in batch farrowing systems, whereby synchronization would concentrate the time of farrowing, allowing for better organization of employees. However, a viable alternative method that can be implemented to manage farrowing is to sustain high progestagen levels in the final days of gestation and, consequently, prevent early parturition. Efficient techniques to delay farrowing such as using oral progestagen supplementation have been previously described, but are only recently being considered for commercial use. The present manuscript reviews publications regarding delaying parturition and discusses the use of intravaginal devices (IVDs) containing progestagen. There is limited data addressing the effect of progestagen treatment during gestation on productive and reproductive performance. Therefore, future studies should focus on improving synchronization protocols following progestagen supplementation and evaluating piglet viability and sow fertility, before widely using progestagen supplementation to manipulate parturition.Como a duração da gestação de suínos pode ter ampla variação, é comum a ocorrência de partos antecipados ou gestações prolongadas. Isso aumenta as chances de partos sem assistência e leva a uma grande variação de idade dos leitões dentro do lote de produção. Portanto, a supervisão do parto é indispensável para reduzir as perdas neonatais. Para facilitar o auxílio aos leitões, a indução do parto com prostaglandina F2α (PGF) é eficaz e amplamente utilizada, sendo indicada para concentrar os partos em momentos mais adequados, preferencialmente durante o horário com maior disponibilidade de colaboradores. Uma alternativa viável é manipular o momento do parto, através da manutenção de níveis plasmáticos elevados de progestágeno durante o final da gestação, a fim de evitar partos antecipados. Formas eficientes de evitar o parto através de suplementação oral de progestágenos foram descritas há décadas, mas apenas recentemente tem sido cogitada a utilização comercial. A presente revisão aborda estudos disponíveis na literatura relacionados ao protelamento do parto, incluindo a utilização de dispositivos intravaginais (DIVs) impregnados com progestágeno. São poucos os dados disponíveis relacionados ao uso de progestágenos na gestação com índices produtivos e reprodutivos. Portanto, alguns pontos ainda devem ser melhor avaliados, especialmente com relação à determinação da sincronia dos partos após o fim da suplementação com progestágenos, à viabilidade dos neonatos e à fertilidade subsequente das fêmeas antes da ampla adoção desta técnica

Association between reproductive traits and four microsatellites in Brangus-Ibagé cattle

The aim of the present study was to verify associations between reproductive efficiency and four microsatellite markers located in synteny with genes involved in the regulation of reproductive mechanisms. A sample of 107 females from a Brangus Ibagé population (5/8 Aberdeen Angus x 3/8 Nelore) was characterized for ETH225 (D9S1) and MM12E6 (D9S20) microsatellites, mapped on chromosome 9, and HEL5 (D21S15) and AFZ1 (D21S37) on chromosome 21. Associations between the genetic markers and reproductive efficiency were determined by one-way analysis of variance using calving interval (CI), live weight at calving (LWC), live weight at first calving (LW1C) and live weight at second calving (LW2C) as dependent variables. The genotypes were classified according to allele size into homozygous for long alleles, homozygous for short alleles and heterozygous. A longer CI was observed for individuals homozygous for long alleles at the HEL5 locus compared with the others (p = 0.022). For the AFZ1 locus, an inverse correlation between allele size and calving interval was observed (p = 0.022), suggesting that homozygosity for long alleles at this microsatellite could be advantageous. Analysis of the combined effect of favorable genotypes at HEL5 and AFZ1 indicated that animals with unfavorable genotypes (homozygous for long alleles at HEL5 and homozygous for short alleles at AFZ1) presented a significantly longer CI (p = 0.003) when compared to the other genotypes. The ETH225 and MM12E6 systems did not present any association with CI. None of the systems studied showed any significant association with LWC, LW1C or LW2C

Follicular dynamic in charolais cows after preventing to be suckled by fitting nose-plates to the calves at 35 and 70 days postpartum

Com o objetivo de avaliar o efeito do desmame interrompido na dinâmica folicular aos 35 e 70 dias pós-parto, I 5 vacas da raça Charolesa com parição na primavera, manejadas em campo nativo, foram distribuídas de forma aleatória em cinco diferentes tratamentos de desmame como segue: uso de tabuleta por dois dias (TAB 2), quatro dias (TAB 4), separação total por dois dias (TOT 2), quatro dias (TOT 4) e controle. A partir do início dos tratamentos, foi realizado monitoramento da atividade ovariana durante oito dias, e coletas diárias de sangue para dosagem de progesterona e identificação de cio com auxaio de rufião. Os ovários foram avaliados eco graficamente e os folículos foram classificados, conforme o diâmetro, em pequenos(~ 3mm), médios (4 a 9mm) e grandes (.? JOmm). A população de folículos pequenos e médios não variou entre os tratamentos e durante os oito dias, nos diferentes tratamentos aplicados aos 35 e 70 dias. Com relação aos folículos grandes, ocorreu diferença (p = 0,0001) nos tratamentos aplicados aos 35 dias pós-parto, em pelo menos um dos dias da avaliação, sendo que o grupo TOT 4 apresentou um aumento significativo da população de folículos grandes (p = 0,001 ), a partir do segundo dia de desmame, diminuindo apó, o quinto dia, devido à ovulação. Nos demais tratamentos, não houve diferença nos diferentes dias. Aos 70 dias, a população defolículos grandes variou no tratamento TAB 4 (p = 0,05) e TOT 4 (p = 0,013), que apresentaram uma distribuição quadrática. Os resultados demonstram também que houve efeito do indivíduo dentro dos tratamentos (p = 0,0001). Conclui-se que o desmame com tabuleta por dois dias, aplicado aos 35 e 70 dias pós-parto, não altera a dinâmica folicular. O desmame com tabuleta, aplicado por quatro dias, não altera a dinâmica folicular quando aplicado aos 35 dias pós-parto, mas ocasiona um aumento da população de folículos grandes e ovulação aos 70 dias. A separação total induz um aumento dos folículos grandes quando aplicada por quatro dias, aos 35 e 70 dias pós-parto, mas não altera a dinâmica folicular quando aplicado por dois dias.The aim of the present work was to determine the weaning effect on ovarian activity during postpartum period, 35 and 70 days after parturition, in Charolais cows that calved during spring season in natural pasture condition. Fifteen cows were randomly assigned to five weaning treatments as the following: nose-plates for two days (TAB 2), for four days (TAB 4), calves remova! for two days (TOT 2), or for four days (TOT 4) and neither nose-plates nor calves remova[ as a contrai group. Ovarian activity was controlled for eight days from the beginning of the treatments, followed by both daily blood collection for determining progesterone levei and heat identification. Ovaries were evaluated by ultrasound and follicles were classified in small (~ 3mm), medium (4 a 9mm) and large-size (.?JOmm). The number of small and medium size follicles did not change during the eight days of examination among the different treatments at 35 and 70 days in one day at least postpartum. The large size follicles population changed at 35 days postpartum amoung treatments (p = 0.0001) and second day group TOT 4 presented a increase on large size follicle population on second day. decreasing after fifth day hy ovulations. The other treatments did not change on different days. At 70 days postpartum, the large size follicles population changed on TAB 2 (p = 0.05) and TOT 4 (p = 0.013), showing a quadratic· distrihution. There was an animal effect inside treatments (p = 0.0001 ). Considering the data, it is possible to conclude that weaning with nose plates for two days at either 35 or 70 days postpartum do not change follicular dynamic. The nose plates for four days do not change fol/icular dynamic at 35 days postpartum but induce an increase in large size follicle population and ovulation at 70 days. The calves remova! also induce an increase in large size follicles for 4 days at 35 and 70 days postpartum hut do not change follicle dynamic for 2 days

Follicular dynamic in charolais cows after preventing to be suckled by fitting nose-plates to the calves at 35 and 70 days postpartum

Com o objetivo de avaliar o efeito do desmame interrompido na dinâmica folicular aos 35 e 70 dias pós-parto, I 5 vacas da raça Charolesa com parição na primavera, manejadas em campo nativo, foram distribuídas de forma aleatória em cinco diferentes tratamentos de desmame como segue: uso de tabuleta por dois dias (TAB 2), quatro dias (TAB 4), separação total por dois dias (TOT 2), quatro dias (TOT 4) e controle. A partir do início dos tratamentos, foi realizado monitoramento da atividade ovariana durante oito dias, e coletas diárias de sangue para dosagem de progesterona e identificação de cio com auxaio de rufião. Os ovários foram avaliados eco graficamente e os folículos foram classificados, conforme o diâmetro, em pequenos(~ 3mm), médios (4 a 9mm) e grandes (.? JOmm). A população de folículos pequenos e médios não variou entre os tratamentos e durante os oito dias, nos diferentes tratamentos aplicados aos 35 e 70 dias. Com relação aos folículos grandes, ocorreu diferença (p = 0,0001) nos tratamentos aplicados aos 35 dias pós-parto, em pelo menos um dos dias da avaliação, sendo que o grupo TOT 4 apresentou um aumento significativo da população de folículos grandes (p = 0,001 ), a partir do segundo dia de desmame, diminuindo apó, o quinto dia, devido à ovulação. Nos demais tratamentos, não houve diferença nos diferentes dias. Aos 70 dias, a população defolículos grandes variou no tratamento TAB 4 (p = 0,05) e TOT 4 (p = 0,013), que apresentaram uma distribuição quadrática. Os resultados demonstram também que houve efeito do indivíduo dentro dos tratamentos (p = 0,0001). Conclui-se que o desmame com tabuleta por dois dias, aplicado aos 35 e 70 dias pós-parto, não altera a dinâmica folicular. O desmame com tabuleta, aplicado por quatro dias, não altera a dinâmica folicular quando aplicado aos 35 dias pós-parto, mas ocasiona um aumento da população de folículos grandes e ovulação aos 70 dias. A separação total induz um aumento dos folículos grandes quando aplicada por quatro dias, aos 35 e 70 dias pós-parto, mas não altera a dinâmica folicular quando aplicado por dois dias.The aim of the present work was to determine the weaning effect on ovarian activity during postpartum period, 35 and 70 days after parturition, in Charolais cows that calved during spring season in natural pasture condition. Fifteen cows were randomly assigned to five weaning treatments as the following: nose-plates for two days (TAB 2), for four days (TAB 4), calves remova! for two days (TOT 2), or for four days (TOT 4) and neither nose-plates nor calves remova[ as a contrai group. Ovarian activity was controlled for eight days from the beginning of the treatments, followed by both daily blood collection for determining progesterone levei and heat identification. Ovaries were evaluated by ultrasound and follicles were classified in small (~ 3mm), medium (4 a 9mm) and large-size (.?JOmm). The number of small and medium size follicles did not change during the eight days of examination among the different treatments at 35 and 70 days in one day at least postpartum. The large size follicles population changed at 35 days postpartum amoung treatments (p = 0.0001) and second day group TOT 4 presented a increase on large size follicle population on second day. decreasing after fifth day hy ovulations. The other treatments did not change on different days. At 70 days postpartum, the large size follicles population changed on TAB 2 (p = 0.05) and TOT 4 (p = 0.013), showing a quadratic· distrihution. There was an animal effect inside treatments (p = 0.0001 ). Considering the data, it is possible to conclude that weaning with nose plates for two days at either 35 or 70 days postpartum do not change follicular dynamic. The nose plates for four days do not change fol/icular dynamic at 35 days postpartum but induce an increase in large size follicle population and ovulation at 70 days. The calves remova! also induce an increase in large size follicles for 4 days at 35 and 70 days postpartum hut do not change follicle dynamic for 2 days