Female crabs enter a stage of rapid ovarian development after mating, and cholesterol is a substrate for steroid hormone synthesis. Therefore, in this experiment, an 8-week feeding trial was conducted to investigate the effects of mating treatments (mated crab and unmated crab) and three dietary cholesterol levels (0·09 %, 0·79 % and 1·40 %) on ovarian development, cholesterol metabolism and steroid hormones metabolism of adult female swimming crab (Portunus trituberculatus). The results indicated that crabs fed the diet with 0·79 % cholesterol significantly increased gonadosomatic index (GSI) and vitellogenin (VTG) content than other treatments in the same mating status. Moreover, mated crabs had markedly increased GSI and VTG content in the ovary and hepatopancreas than unmated crabs. The histological observation found that exogenous vitellogenic oocytes appeared in the mated crabs, while previtellogenic oocytes and endogenous vitellogenic oocytes were the primary oocytes in unmated crabs. The transmission electron microscopy analysis showed that when fed diet with 0·79 % cholesterol, the unmated crabs contained more rough endoplasmic reticulum and mated crabs had higher yolk content than other treatments. Furthermore, mating treatment and dietary 0·79 % cholesterol level both promoted cholesterol deposition by up-regulation of the mRNA and protein expression levels of class B scavenger receptors 1 (Srb1), while stimulating the secretion of steroid hormones by up-regulation of the mRNA and protein expression of steroidogenic acute regulatory protein (Star). Overall, the present results indicated that mating behaviour plays a leading role in promoting ovarian development, and dietary 0·79 % cholesterol level can further promote ovarian development after mating.

Gut microbiome changed dramatically during pregnancy and played important roles in metabolic status and reproductive endocrinology in mammals. However, investigating the functional microbiota and metabolites to improve the reproductive performance and understanding the host–microbiota interaction are still arduous tasks. This study aims to reveal the dominant strains and metabolites that improve the reproductive performance. We analyzed the fecal microbiota composition and metabolic status of higher yield Chinese pig breed Meishan (MS) sows and lower yield but widespread raised hybrid pig breed Landrace × Yorkshire (L × Y) sows on days 28 and 100 of gestation. Results showed that MS sows had higher litter sizes and steroid hormone level but lower short-chain fatty acid level in feces. Fecal metabolomic analysis revealed that MS sows showed a different metabolic status compared with L × Y sows both at early and late pregnancy, which enriched with phenylpropanoid biosynthesis, bile secretion, steroid hormone biosynthesis, and plant secondary metabolite biosynthesis. In addition, 16S rDNA and internal transcribed spacer sequencing indicated that MS sows showed different structures of microbiota community and exhibited an increased bacterial α-diversity but non-differential fungal α-diversity than L × Y sows. Moreover, we found that the litter sizes and bacteria including Sphaerochaeta, Solibacillus, Oscillospira, Escherichia–Shigella, Prevotellaceae_UCG-001, dgA-11_gut_group, and Bacteroides, as well as fungi including Penicillium, Fusarium, Microascus, Elutherascus, and Heydenia both have positive association to the significant metabolites at the early pregnancy. Our findings revealed significant correlation between reproductive performance and gut microbiome and provided microbial and metabolic perspective to improve litter sizes and steroid hormones of sows.

Although in vivo and in vitro approaches appear to be very different, they are related and complementary techniques and both are essential for the investigation of diverse biological topics. The employment of both techniques was considered particularly appropriate to investigate the role of 17β-oestradiol and testosterone in echinoid reproductive biology. The relationship between sex-steroids and echinoid reproduction has not been clearly determined yet, due to the highly variable and sometimes contrasting results obtained from steroid administration experiments. These might be due to the activation of protective metabolic mechanisms that can prevent the exogenous molecules from exerting their biological functions, as observed in our previous research. To clarify these aspects, in the present study we explored sex-steroid involvement in the reproduction of the sea urchin Paracentrotus lividus, employing both in vivo and in vitro approaches: (1) an experiment involving hormone dietary administration was performed and different reproductive parameters were deeply analysed; (2) ovarian cells were cultured in the presence of the same steroids and morphological and biochemical analyses were carried out. According to our results, sex-steroids appear not to be involved in sea urchin gonad development and gamete maturation, as neither in vivo administration nor in vitro exposure influenced gonad and gamete growth. In addition, in vitro hormonal treatment did not affect sea urchin Major Yolk Protein content. Overall, the present work complements our previous research providing information on sex-steroid involvement in echinoid reproduction and illustrates new methodological approaches that will be useful for future research on invertebrate biology and physiology.

The physiologically active form of vitamin B6, pyridoxal 5′-phosphate (PLP), is known to function as a cofactor in many enzymic reactions in amino acid metabolism. Recent studies have shown that, apart from its role as a coenzyme, PLP acts as a modulator of steroid hormone receptor-mediated gene expression. Specifically, elevation of intracellular PLP leads to a decreased transcriptional response to glucocorticoid hormones, progesterone, androgens, and oestrogens. For example, the induction of cytosolic aspartate aminotransferase (cAspAT) in rat liver by hydrocortisone is suppressed by the administration of pyridoxine. The suppression of the cAspAT induction by pyridoxine is caused by a decrease in the expression of the cAspAT gene, which is brought about by inactivation of the binding activity of the glucocorticoid receptor to the glucocorticoid-responsive element in the regulatory region of the cAspAT gene. Vitamin B6 has recently been found to modulate gene expression not only for steroid hormone-responsive or PLP-dependent enzymes but also for steroid- and PLP-unrelated proteins such as serum albumin. Albumin gene expression was found to be modulated by vitamin B6 through a novel mechanism that involves inactivation of tissue-specific transcription factors, such as HNF-1 or C/EBP, by direct interaction with PLP in a similar manner to glucocorticoid receptor. Enhancement of albumin gene expression in the liver by an increased supply of amino acids can be explained by elevated binding of HNF-1 and C/EBP to their DNA-binding sites which, in turn, is caused by a decrease in the intracellular level of PLP by the increased amino acid supply. These findings that vitamin B6 acts as a physiological modulator of gene expression add a new dimension to the hitherto recognized function of vitamin B6 as a cofactor of enzyme action.

The amphibian testis is a useful model because of its zonal organisation in lobules, distributed along the cephalocaudal axis, each containing a unique germ cell type. Sperm empty lobules form the so-called glandular tissue at the posterior region of the gonad. Androgen production is limited to the cells of the interstitial tissue surrounding lobules with spermatozoa bundles and to the cells of the glandular tissue. In this work, we have studied the distribution of terminal carbohydrate moieties of N- and O-linked oligosaccharides in the interstitial and glandular tissue of the Pleurodeles waltl testis, by means of 14 lectins combined with chemical and enzymatic deglycosylation pretreatment. Some differences in glycan composition between the interstitial and the glandular tissue have been detected. Thus in both tissues, N-linked oligosaccharides contained mannose, Gal(β1,4)GlcNAc, and Neu5Ac(α2,3)Gal(β1,4)GlcNAc, while O-linked oligosaccharides contained Con A-positive mannose, Gal(β1,3)GalNAc, Gal(β1,4)GlcNAc, Neu5Ac(α2,3)Gal(β1,4)GlcNAc, and WGA-positive GlcNAc. Fucose was also detected in both tissues. However, GlcNAc on N-linked oligosaccharides and GalNAc and Neu5Ac(α2,6)Gal/GalNAc on both N- and O-linked oligosaccharides were found only in the interstitial tissue. As glandular tissue cells arise from the innermost cells of interstitial tissue that surround lobules, the differences in the glycan composition of interstitial and glandular tissue shown in this work may be related to the start of androgen synthesis when steroid hormone (SH)-secreting cells develop.