Rubén Montes-Pérez

Seasonal changes of progesterone and testosterone concentrations throughout gonad maturation stages of the Mexican octopus, Octopus maya (Octopodidae: Octopus)

Variations in progesterone (P4) and testosterone (T) levels in the gonad of Octopus maya from Sisal in Yucatan State, Mexico, were investigated by radioimmunoassays and in relation to four gonad maturation stages (GMS) and to the reproductive cycle, as represented by two maturity indices (microscopic ‘MiMI’ and macroscopic ‘MaMI’). According to the GMS and the maturity indices, the reproductive season of O. maya from Yucatan occurred from February to June. In females, P4 and T displayed the same pattern, with a tendency to increase at the same time, although on average, P4 had seven-fold higher concentrations than T. In contrast, P4 and T in male gonads displayed a different pattern, where T concentrations were relatively stable throughout all of the study months. In the female gonad P4 was lowest (close to 0 pg g–1) during both developing (GMS-I) and maturing (GMS-II) stages, and increased (189 ± 53 pg g–1) approaching the mature stage (GMS-III) to a maximum value of 611 pg g–1. Concentrations of T in the male gonad were lowest (106 ± 9 pg g–1) during the maturing stage (GMS-II) and increased up to the mature stage (GMS-III), reaching a maximum of 440 pg g–1. Pearsons correlation (r) between hormones and maturity indices showed strong relationships for females (around 0.4 and −0.7; p < 0.05), but there were negligible or weak relationships for males (0.2 and −0.1; p > 0.05). Hormone correlations in females were inverse with MaMI and direct with MiMI. Our major findings showed that gonadal P4 levels were elevated during GMS-III and GMS-IV (i.e. periods of vitellogenic oocytes), where the characteristic aspect is an ovary with very high oocyte diameters, with the primary follicle cells deeply infolded in the ooplasm for yolk synthesis. These results suggested a synchrony between P4 and the process of folliculogenesis, and in turn, vitellogenesis.

Development and Validation of a Solid-Phase Radioimmunoassay for Measuring Progesterone and Testosterone in Octopus Gonad Extracts

ABSTRACT Commercially available radioimmunoassays (RIA) with 125I-labeled hormones were adapted, developed and validated to quantify progesterone and testosterone in gonad extracts of Octopus maya, considered an easily domesticated species with potential in aquaculture. Development of the RIAs was divided into four phases: (1) extraction of progesterone and testosterone from gonads, (2) preparation of gonad extracts for RIA, (3) standards preparation, and (4) RIA procedure. Hormones were extracted twice with 15 mL of diethyl-ether each time. The recovered hormone and the solvent effect on extraction were evaluated. RIAs were validated based on specificity, sensitivity, accuracy, precision and reproducibility. Serially diluted gonad extracts were parallel to the standard curves of each hormone, indicating specificity. Sensitivities for both hormones were less than 0.1 ng·g-1, and did not change by more than 20% during the 125I half-life. Accuracy was 102.25 ± 11.22% for progesterone and 81.62 ± 6.24% for testosterone. For both hormones, precision was close to 13% and reproducibility 17%. The precision/reproducibility ratio indicated a system with good stability. The amounts of the hormones recovered increased when the number of extractions was increased. Hormone concentrations also increased when the volume of diethyl-ether used per extraction was increased. The range of progesterone and testosterone concentrations quantified in this study is in agreement with the range found in other octopuses. Finally, the developed and validated RIAs meet the requirements for quantification of progesterone and testosterone in Octopus gonad extracts and show that it is possible to use 125I-labeled hormone as well as the plastic coated-tubes from commercial RIA kits to analyse variations in hormone levels associated with gonad developmental stages and the reproductive cycle of octopuses, allowing exploration of their possible functions.

Perfiles sanguíneos de progesterona y estradiol del Pecari tajacu en cautiverio

The objective was to characterize the levels of progesterone (P4) and 17b estradiol (E-17b) in blood of 11 Pecari tajacu adult females in captivity. The females were in the presence of males but separated by a wire mesh. Blood samples were taken every 6 days during 3 months. The estimation of the levels of the steroid hormones was carried out by radioimmunoassay in solid phase. Hormonal profiles were plotted against time, to determine the duration of each ovarian cycle and the number of cycles. Nine animals showed estrous cycle and 2 did not. The average duration of the ovarian cycle was 26.8±4.8 days. The average concentration of P4 in the luteal phase was 22.95±4.94 ng/mL, and during the follicular phase was 1.2±0.73 ng/mL (p<0.05). The levels of E-17b in the luteal phase were 6.89±2.79 pg/mL, and 32.17±7.29 pg/mL in the follicular phase (p<0.05). The presence of the ovarian cycles was variable, although the duration was within the range of values established for this species under captivity. The synchrony of the hormonal profiles of P4 and E-17b during the ovarian cycle was inverted.

EVALUACIÓN DE ESTRÉS EN EL PECARI TAJACU SOMETIDO A DOS DENSIDADES DE POBLACIÓN

Resumen es: El objetivo de este trabajo fue evaluar el nivel de estres producido por dos densidades de poblacion en pecaries de collar (Pecari tajacu) en cautiverio....