Life History Traits, Elasticity Analyses, and Phenotypic Plasticity of Squaliobarbus curriculus in the Pearl River Estuary, China

Squaliobarbus curriculus, commonly known as red-eye fish, is widely distributed in East Asia. It is one of the important aquatic germplasm resource and economic species in the Pearl River. To give suggestions for better protection and management, we investigated its life history and conducted elasticity analyses. Samples (n = 451) were collected between 2016 and 2017 from the western Pearl River estuary. There were no significant differences between the length-weight relationships of females and males (W = 0.00001SL3.121). The von Bertalanffy growth function was Lt = 553.2 [1 − e−0.111(t+1.009)]. The estimated length at 50% sexual maturity for females was 209.6 and 200.0 mm for males, both at 3 years of age. Oocyte size-frequency distribution suggested batch spawning. Fecundity ranged between 9,407 and 175,086 eggs per fish (mean = 51,040, or 143.9 eggs/g of fish weight). To better understand the ecological phenotypic plasticity of S. curriculus we conducted meta-analyses on all available life history data for this species. Our results showed that the standard lengths at ages 2 and 3 in the estuary were significantly smaller than in the upper reaches of the Pearl River basin, and there were also obvious differences in fecundity and oocyte size. For more, the standard lengths at ages 2 and 3 were correlated negatively with latitude. Elasticity analysis showed that juveniles’ (aged 1–3) survival had the largest contribution to the population growth rate, which suggests that management efforts should focus on the early life stages.

Effects of juvenile hormone in fertility and fertility-signaling in workers of the common wasp Vespula vulgaris

In the highly eusocial wasp, Vespula vulgaris, queens produce honest signals to alert their subordinate workers of their fertility status, and therefore they are reproductively suppressed and help in the colony. The honesty of the queen signals is likely maintained due to hormonal regulation, which affects fertility and fertility cue expression. Here, we tested if hormonal pleiotropy could support the hypothesis that juvenile hormone controls fertility and fertility signaling in workers. In addition, we aimed to check oocyte size as a proxy of fertility. To do that, we treated V. vulgaris workers with synthetic versions of juvenile hormone (JH) analogue and a JH inhibitor, methoprene and precocene, respectively. We dissected the treated females to check ovary activation and analyzed their chemical profile. Our results showed that juvenile hormone has an influence on the abundance of fertility linked compounds produced by workers, and it also showed to increase oocyte size in workers. Our results corroborate the hypothesis that juvenile hormone controls fertility and fertility signaling in workers, whereby workers are unable to reproduce without alerting other colony members of their fertility. This provides supports the hypothesis that hormonal pleiotropy contributes to keeping the queen fertility signals honest.

SPECIAL FEATURES OF OOCYTE SIZE IN SO-IUY MULLET (PLANILIZA HAEMATOCHEILA TEMMINCK & SCHLEGEL, 1845) IN THE SEA OF AZOV AT THE END OF THE WINTER SEASON, 2019

Analysis of special features of the reproductive system of so-iuy mullet Planiliza haematocheila (Temminck & Schlegel, 1845) females from the Azov and Black Sea Basin at the end of the winter season, 2019, has been conducted using the size of oocytes as its basis. Individual differences in distribution of oocyte sizes during the period of trophoplazmatic growth have been identified. Following the estimation of ordered series of oocyte sizes during the period of trophoplazmatic growth, the median and percentile values have been calculated; they can be used as reference values for qualitative characterization of ordered series for oocyte diameter in an individual specimen, using the empirical median, calculated for the respective specimen, as a basis. It has been found out that the sizes of trophoplazmatic growth oocytes, which are utilized during the spawning period of the current year, and, therefore, the degree of gonad maturity have individual characteristics independent of the age of an individual, of its length and weight, and of the content of reserve and bioactive substances in its tissues and blood.

Characterization of a protandrous hermaphroditic reproductive system in transitional and female phases of Norileca indica — morphological, histological and ultrastructural approach

The present study explores the reproductive system of Norileca indica during its transitional and female phase at morphological, histological, ultrastructural and histochemical levels. The paired and symmetrical hermaphroditic reproductive system of N. indica in the transitional and female phases lies dorsally in the thorax on either side of the gut, each consisting of a three-lobed testis (with lobes t1, t2 and t3) followed by an ovary and then a vas deferens, which opens into the paired penes located at sternite 7; the oviduct, arising laterally from the ovarian lobe, opens into the gonopore located on the 6th pereonite. In the transitional phase, the gonads show a presence of germ cells at different maturation stages: spermiogenesis in the testes has already halted, while the ovary undergoes active vitellogenesis. Spermatophores are frequently seen in the vas deferens but seldom in the testes; the size of the oocytes then is 250-1200 μm. The gonadosomatic index (GSI) and nucleocytoplasmic index (NCI) range over 0.090-0.198 and 0.46-0.11, respectively. In the female, oocyte size increases to 1500 μm; the GSI ranges 0.019-0.235 and the NCI from 2.40 to 0.09; testes and vas deferens are not prominent. This paper discusses the possible role of protandrous hermaphroditism in the reproductive life of N. indica.

Reproductive patterns of the black starry sea urchin Arbacia stellata in Punta Banda, Baja California, Mexico

Widely distributed species such as Arbacia stellata adjust patterns of their life history according to local conditions. In the present study the reproductive cycle of this species was analysed throughout a sampling year. Gonadal development cycle, sex ratio, actual fecundity and oocyte size distribution were characterized and the relationship of these reproductive characteristics with environmental variables such as sea surface temperature, photoperiod, chlorophyll a and net primary production evaluated. Our results showed that A. stellata is a gonochoric sea urchin. Gametogenesis was classified into six stages for both sexes (immature, growth, pre-maturity I, pre-maturity II, mature and spawning) and no synchrony was observed for the gonads between individuals. The female to male ratio was close to 1:1 in most months. The gonadosomatic index (GSI) showed significant differences between sexes or months; however, the highest values were observed during spring, with positive correlation with chlorophyll a. No significant differences were observed in the maturity index (MI) between sexes, with a positive correlation with temperature but negative with chlorophyll. Actual fecundity showed wide variations throughout the year and correlation with chlorophyll a and temperature. Oocyte size distribution was unimodal and the predominant frequency was that of mature oocytes. The reproductive cycle of A. stellata has a semi-continuous pattern for both sexes and partial spawning throughout the year in the sampling site. We observed nutrient assimilation in the gonads during spring and a larger reproductive activity from late summer to early winter.

Role of Oocyte Morphological Abnormality Rates on the Embryo Development and Implantation

<p><strong>OBJECTIVE: </strong>The aim of this study was to assess the impact of some oocyte morphological abnormality rates on embryo development and implantation.</p><p><strong>STUDY DESIGN:</strong> Oocyte morphological abnormalities including oocyte size, elliptical shape, vacuole, plain polar body, fragmented polar body, large perivitellin space, perivitellin debris, central granulation, dense central granulation, inclusion body, thick zona pellucida, clusters of smooth endoplasmic reticulum, easy needle insertion and dark cytoplasm were determined for each oocyte. Rates of these oocyte morphological anomalies were determined for each case and the impact of rates on the cycle outcome was analyzed.</p><p><strong>RESULTS: </strong>Similar oocyte morphology abnormality rates were observed between cycles with and without successful embryo implantation. On the other hand, both fragmented polar body and vacuole rates were found to be significantly higher in cycles with Grade 2 embryo transfer. These rate differences were remained significant after adjustment for the age and basal FSH level.</p><p><strong>CONCLUSION: </strong>None of the oocyte morphological features was found to have significant impact on ART outcome. </p>