The bighorn sheep is listed on the IUCN Red List of Threatened Species. By interspecies somatic cell nuclear transfer (ISCNT), other endangered species are cloned using somatic cells as nuclear donors, fusing them with enucleated oocytes from heterologous domestic species. On the other hand, resveratrol added during in vitro maturation (IVM) of domestic sheep oocytes favors the development of embryos produced in vitro. The aim of this study was to treat O. aries oocytes with resveratrol during IVM using them as cytoplasts in ISCNT via handmade cloning (HMC), evaluating its effect on the in vitro development of Mexican bighorn sheep (O. c. mexicana) cloned embryos. Post-mortem skin fibroblasts from an adult male specimen from the Chapultepec Zoo were frozen for 8 years, thawed, and reseeded for 8 cell passages. For IVM, O. aries oocytes were treated with 0, 0.5, or 1.0 µM resveratrol. Matured oocytes were manually enucleated, and triplets (O. aries cytoplast-O. c. mexicana karyoplast-O. aries cytoplast) were formed and electrically fused. The reconstructed embryos were chemically activated and cultured until they developed into blastocysts. For IVM, no differences were found between treatments, yet at 0.5 µM, resveratrol significantly increased (p<0.05) the blastocyst rate and decreased the fragmentation rate.

México alberga aproximadamente el 8.7 % de las especies de reptiles del mundo, dentro de estas se encuentran las serpientes, en este grupo de ofidios está el Cincuate o Alicante (Pituophis deppei), el cual presenta estacionalidad reproductiva. Para contribuir a la conservación se requieren estrategias para la obtención de gametos sin comprometer la integridad de los ejemplares donadores. El objetivo de este trabajo fue evaluar las variaciones de las características del semen de Pituophis deppei a lo largo de un año, con el fin de conocer posibles variaciones en la producción de semen que se puedan relacionar con su estacionalidad reproductiva. Se muestrearon nueve ejemplares de Pituophis, albergados en el Laboratorio de Herpetología de la Facultad de Estudios Superiores Iztacala-UNAM. La extracción seminal se realizó mediante estimulación manual sin la administración de fármacos. Los ejemplares muestreados aportaron semen a lo largo del año con una eficiencia del 60 % en su recolección. Se obtuvieron muestras de semen durante todo el año, con dos incrementos en la producción espermática muy marcados en febrero-marzo y julio, ambos con buena concentración espermática. Los valores promedios obtenidos en la espermatobioscopia manual, movilidad 52.27 ± 20.29 %, concentración 208.48 ± 221.09 x 106 células por ml. Febrero fue el mes con mayor volumen seminal y abril la mayor concentración promedio. Las variaciones en los parámetros evaluados en la espermatobioscopia no tuvieron una relación directa con los factores ambientales medidos como la temperatura o humedad relativa, sin embargo, son cercanos a la estacionalidad reproductiva conocida para la especie.

The aim of this study was to treat sheep oocytes with resveratrol during in vitro maturation (IVM) and use them as cytoplasts in ISCNT via handmade cloning (HMC), evaluating the effect of resveratrol on the in vitro development of cloned Mexican bighorn sheep embryos. Post mortem skin fibroblasts from an adult male specimen were frozen for 8 years, thawed, and reseeded for eight cell passages. For IVM, Ovis aries oocytes were treated with 0, 0.5, or 1.0 µM resveratrol. Matured oocytes were manually enucleated, and triplets (O. aries cytoplast–Ovis canadensis mexicana karyoplast–O. aries cytoplast) were formed and electrically fused. The reconstructed embryos were chemically activated and cultured for in vitro development (IVD). The IVM rate was 81.8 ± 10.4% for CG, 81.9 ± 6.7% for EG1, and 76.3 ± 7.7% for EG2, with no significant differences between groups. For IVD, EG1 showed a statistically significant increase (p < 0.05) in the blastocyst rate (31 ± 12.0%) and a statistically significant decrease in the fragmented embryo rate (25 ± 10.4) when compared with the other groups. It was concluded that better rates of cloned bighorn sheep blastocysts could be obtained in ISCNT via HMC when fusing O. aries oocytes supplemented with resveratrol during IVM with post mortem adult male O. c. mexicana fibroblasts that had been cryopreserved for 8 years.

Reproductive endocrinology plays a crucial role in the management of endangered species. Using non‐invasive techniques, the complex nature of their reproductive biology can be better understood. This study aimed to determine hormonal concentrations of progesterone (P4) and estradiol (E2) in female Greater Caribbean manatees ( Trichechus manatus manatus ) under human care and to establish whether there are differences in hormone concentrations between sexually mature and sexually immature females based on fecal analysis. The assessment of steroid metabolites was performed using the enzyme‐linked immunosorbent assay (ELISA) technique with a commercial DetectX kit. The results indicated reference values for progesterone (P4) ranging from 109.9 to 334.3 ng/g feces and for estradiol (E2) ranging from 12.2 to 90.9 ng/g feces. These results suggest an inversely proportional relationship between the two hormones, demonstrating a complex interaction in the estrous cycle of manatees. The findings also indicated no evidence that individual hormonal levels are correlated (Spearman correlation test: ρ = 0.122, p = 0.254; and Kendall correlation test: τ = 0.084, p = 0.245), although higher progesterone levels were associated with lower estradiol concentrations and vice versa. Similarly, no significant correlation was observed between the hormone concentrations of sexually mature and sexually immature females (Skillings–Mack test: P₄, p = 0.103, df = 34, 10,000 repetitions; E₂, p = 0.276, df = 34, 10,000 repetitions). Longer monitoring periods, along with vaginal cytology and ultrasound evaluations, are recommended.

Leporids play an important ecological role by contributing to seed dispersal and serving as prey for a wide range of predators. However, several leporid species are threatened by habitat degradation, highlighting the need for genetic resources that can support studies of wild and managed populations. The SRY gene, located on the Y chromosome in most male mammals, is a useful marker for paternal lineage studies and may provide information relevant to conservation genetics. Here, we generated partial Sex-determining region Y (SRY) sequences from 14 male leporids: 12 zoo-managed Romerolagus diazi, one wild R. diazi carcass, and one wild Sylvilagus floridanus carcass. Three unique consensus sequences were obtained and deposited in GenBank: PV612454 and PV612455 for R. diazi, and PV612456 for S. floridanus. The analyzed fragments comprised 703 base pairs (bp) in R. diazi and 741 bp in S. floridanus, including approximately 173 bp of the 5′ regulatory region and a partial transcriptional unit covering the first 176 codons, including the high-mobility group box domain; the complete SRY coding region was not recovered. Comparisons with available leporid SRY sequences showed that the regulatory region had lower guanine-cytosine content than the transcriptional unit, whereas R. diazi and S. floridanus showed relatively high guanine-cytosine values in the regulatory and 3′ SRY regions. Polymorphic sites were detected in the regulatory and coding regions, and amino acid variation was concentrated outside the conserved high-mobility group box domain. A distance-based, single-locus comparison provided a preliminary paternal-lineage framework among the leporid sequences analyzed.