Browsing by Author "de los Reyes, Monica"

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    Chronic Undernutrition in Ovine Twin Pregnancies Abolishes Differences in Birth Weight Due to Sex: An Evaluation of the Role of Nutritional and Antioxidant Supplementation
    (2024) Sales, Francisco; Peralta, oscar A.; de los Reyes, Monica; Sandoval, Camila; Martinez-Ros, Paula; Rojas, Carolina; Gonzales-Bulnes, Antonio; Parraguez, Victor H.
    Simple Summary The fetal growth pattern in twin pregnancies is usually affected by the sex of the co-twin pairs, among other factors, with females being lighter than males at birth. We aimed to determine the effect of the sex of co-twins on lambs' birth weight in ovine pregnancies developed under natural undernourishment, a condition of sheep farming frequently encountered worldwide. Additionally, we sought to investigate whether the nutritional and/or antioxidant supplementation provided to ewes during pregnancy could modulate the potential effects associated with the sex of co-twins. We found that maternal nutrient restriction abolishes the sex differences in body weight at birth between co-twins. However, improving maternal nutrition and supplementation with antioxidants during gestation not only improves maternal weight and body condition but also tends to restore birth weight and its differences between female and male offspring, an effect that is enhanced with the combined supplementation of concentrated food and antioxidants. These results suggest that undernutrition not only may alter the intrauterine growth through the maternal-fetal relationship, but also through the feto-fetal relationship, which can be normalized via strategically targeting interventions such as maternal nutrient supplementation or antioxidant supplementation during gestation. Thus, a better understanding of the driving factors of this effect is of major relevance to improving fetal growth and lamb survival in harsh environments.Abstract In twin pregnancies of discordant sex, the male fetus grows larger than the female co-twin. Our study aimed to determine the effect of the sex of co-twins on lambs' birth weight in ovine pregnancies developed under natural undernourishment. Additionally, we investigated whether the nutritional and/or antioxidant supplementation provided to ewes during pregnancy could modulate the potential effects associated with the sex of co-twins. Ninety-six birth records of twin pregnancies of sheep grazing the natural Patagonian prairies were analyzed. The animals were divided into four groups: control (no supplementation), N (concentrate supplementation, 100% NRC), A (antioxidant supplementation), and NA (concentrate + antioxidant supplementation). Supplementation occurred from day 35 of gestation onwards until lambing. There were no differences in female or male birth weight in the control undernourished group. However, in group N, females or males with sex-discordant co-twins had a higher birth weight than did those with co-twins of the same sex. Group A males with female co-twins had a higher birth weight compared to males whose co-twins were also males. In NA lambs, males had a higher birth weight compared to females, regardless of their co-twin's sex. Therefore, chronic undernutrition abolished the differences in birth weight due to fetal sex. Restoring maternal nutrition or antioxidant supplementation tends to normalize birth weight and restore the differences between females and males. This effect is enhanced with the combined supplementation of concentrated food and antioxidants.
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    Early apoptosis detection in canine granulosa cells through the analysis of BCL-2 and BAX proteins during the follicular development associated with oocyte maturation
    (2024) Salinger, Michelle; Palomino, Jaime; Peralta, Oscar A.; Parraguez, Victor H.; de los Reyes, Monica
    The objective of this study was to investigate the early follicular apoptosis in canine ovarian follicles by examining the expression of anti-apoptotic BCL-2 and pro-apoptotic BAX proteins throughout the estrous cycle associated with oocyte maturation. Follicular cells from preantral and antral follicles of varying sizes were isolated and grouped based on follicle type and estrous phase. Antral follicles underwent flow cytometry analysis, whereas preantral follicles were subjected to Western blotting. The meiotic capacity of oocytes from these different follicle types was evaluated through in vitro maturation. Statistical analysis included ANOVA and Duncan's test. Results showed fluctuations in BCL-2 and BAX levels across different follicular stages and estrous phases. BCL-2 levels increased (P<0.05) with follicular development in antral follicles, particularly during estrus, while BAX exhibited variations peaking (P<0.05) during estrus. The BCL-2/ BAX ratio in antral follicles was higher (P<0.05) in estrus and diestrus compared to anestrus and proestrus. Additionally, BCL-2 and BAX proteins were detected in preantral follicles, with varying expression levels (P<0.05) across estrous phases. The BCL-2/BAX ratio in preantral follicles was highest (P<0.05) during anestrus and estrus and decreased (P<0.05) in proestrus and diestrus. Oocytes from preantral follicles did not reach the MII stage, regardless of the levels of BCL-2/BAX. Conversely, oocytes obtained from large follicles during estrus showed the highest (P<0.05) maturation percentages, which were associated with the highest BCL-2/BAX ratio. These findings provide insights into the dynamic patterns of BCL-2 /BAX in canine follicles across the estrous cycle, shedding light on their potential roles in oocyte development.
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    Potential of mesenchymal stromal/stem cells and spermatogonial stem cells for survival and colonization in bull recipient testes after allogenic transplantation
    (2024) Segunda, Moises N.; Cortez, Jahaira; Diaz, Carlos; Arancibia, Richard; Torres, Cristian G.; Parraguez, Victor H.; de los Reyes, Monica; Peralta, Oscar A.
    Stem cell transplantation into seminiferous tubules of recipient testis could become a tool for fertility restoration, genetic improvement, or conservation of endangered species. Spermatogonial stem cells (SSCs) are primary candidates for transplantation; however, limited abundance, complexity for isolation and culture, and lack of specific markers have limited their use. Mesenchymal stromal/stem cells (MSCs) are multipotent progenitors that are simple to isolate and culture and possess specific markers for identification, and immune evasive and migratory capacities. The objective of the present study was to evaluate the potential for survival and colonization in seminiferous tubules of two different concentrations of bovine fetal adipose tissue-derived MSCs (ATMSCs), native of pre-induced, and to compare the fate of bovine adult peripheral blood-derived MSCs (PB-MSCs) and SSCs after allogenic transplantation in testis of recipient bulls. In experiment 1, AT-MSCs at two concentrations (1x107 and 2x107; n = 3) or pre-exposed to 2 mu M testosterone and 1 mu M retinoic acid (RA) for 14 days (n = 5) were evaluated. In experiment 2, adult PB-MSCs and SSCs (4x107 cells each) pre-exposed to Sertoli cell conditioned media (SCs/CM; n = 4) for 14 days were compared. Each cell type was separately labelled with PKH26 and then transplanted into testes of 8-month-old recipient bulls. Four weeks (Exp. 1) and two weeks (Exp. 2) after transplantation, testicular tissue was processed for confocal microscopy detection of PKH26-positive cells. Mean number of PKH26-positive cells were higher (P < 0.05) in testis transplanted with 2x107 AT-MSCs in the proximal (6.7 f 3.7) and medial (6.6 f 3.2) sections compared to testis transplanted with 1x107 ATMSCs (proximal: 1.9 f 1; medial: 1.9 f 1) sections or pre-induced AT-MSCs (proximal: 4.7 f 5.6; medial: 3.8 f 4.1). In Exp. 2, mean number of PKH26-positive SSCs in medial testicular section (22.5 f 1.3) were higher (P <0.05) compared to respective section in PB-MSCs group (17 f 4.2). Thus, in vivo data indicates that a higher number of transplanted AT-MSCs resulted in more cells surviving and colonizing seminiferous tubules; however, pre-induction with testosterone and RA did not improve these capacities. SSCs displayed a greater capacity for survival and colonization in recipient seminiferous tubules; however, PB-MSCs were observed in all sections of testis after two weeks of transplantation.