Correlation between ovarian steroidogenesis and beta-endorphin in the Lizard Uromastyx acanthinura: Immunohistochemical approach.

In Mammals, opioid peptides are involved in various physiological processes including the reproductive function. The knowledge of the distribution of beta-endorphin, one of opioid peptides in Reptiles ovaries is very limited. Therefore, the present study used the lizard ovarian follicles to further elucidate the role of this peptide in steroidogenesis. In Uromastyx acanthinura, the localization of both this peptide and sex steroid hormone was investigated by the immunohistochemical approach. This technique was used to evaluate the distribution of these substances and their relationship. The beta-endorphin is strongly distributed in the granulosa cells and oocyte cytoplasm of the previtellogenic follicles in sexually quiescent lizards (winter) when steroidogenesis was interrupted. In spring, the signal became weak, or even absent, in the vitellogenic and previtellogenic follicles. The granulosa cells of the previtellogenic follicles showed an important synthesis of 17beta-estradiol. Females that did not undergo in vitellogenesis in spring showed the same profile than quiescent females of winter. These findings represent the first evidence of the presence of beta-endorphin in the ovary of this lizard. The seasonal variations observed in the reproductive cycle suggest that this opioid peptide is involved in the modulation of seasonal steroidogenesis

Reproductive biology of the endangered percid Zingel asper in captivity: a histological description of the male reproductive cycle

The endemic Rhodanian percid Zingel asper (Linnaeus, 1758), is usually found throughout the Rhône basin, but this fish is now in sharp decline. Understanding its reproductive physiology is important so as to be able to artificially control its reproduction with a view to re-introducing it. This study was carried out on a population obtained by artificial fertilization and bred in external tanks. Fishes were observed from the juvenile stages through to adulthood. Patterns of testicular development were defined from histological observations. Testes of Z. asper were paired, elongated and fusiform dorsocaudal organs. The two lobes of each gonad joined together to form a duct that extended to the urogenital papillae. They showed a lobular structure. The testicular lobules were of the unrestricted spermatogonial type. Up to 10 months-old, most of the males were immature: their testes showed only type A spermatogonia. The appearance of type B spermatogonia in the lobules of a testis indicated the beginning of spermatogenesis in 10 months-old fish. Spermiogenesis occurred 24 months after the fertilization and, in 26 months-old fish, the cyst opened and released spermatozoa into the lumen of lobules. The spermiation belonged to a cystic type. During the third year, histological observations pointed to the same evolution of adult gonads as during the second year. Sexual maturity was reached in captive Z. asper after two years. The spawning occurred in May in the breeding conditions. (Folia Histochemica et Cytobiologica 2011, Vol. 49, No. 3, 486–496

Immunolocalization of estrogens and progesterone receptors within the ovary of the lizard Uromastyx acanthinura from vitellogenesis to rest season.

The sites of action and the physiological role of estrogens and progesterone in the ovary are poorly understood in Reptiles. We have undertaken a systematic study of the immunoexpression of classical oestrogen receptor (ER or ERalpha) and progesterone receptor (PR) in the female lizard during the reproductive cycle. During vitellogenesis, ER was not expressed in vitellogenic follicles whereas PR was weakly detected in the nucleus of some follicular cells and well expressed in the internal theca cells. The follicular and theca cells were immunopositive for ER in the previtellogenic follicles, the signal in both was cytosolic. PR was strongly expressed in the follicular cells, the signal was localised in the nucleus. In the post-reproductive period, ER was detected in the previtellogenic follicles in the same manner as in the breeding period. The staining for PR was expressed in both the nucleus and cytoplasm of follicular cells and theca cells. In the sexual rest, the previtellogenic follicles were all negative for ER and PR immunoexpression. These findings suggest that the main action of estrogens in the ovary is not mediated by ER. The expression of cytosolic PR only in the post-reproduction period, at the same time at the progesterone synthesis, supports the hypothesis which stipulates an exclusive nuclear localization in the absence of progesterone

Oviduct, egg, and egg sac structures in the Siberian salamander, Salamandrella keyserlingii (Caudata, Hynobiidae): a histological and histochemical study

Unraveling morphological and chemical features of the eggs’ jelly layers and other clutch elements, formed by the oviduct of a female, is necessary for the understanding of reproductive adaptation in amphibians. Our study is the first microstructural and histochemical descriptions about the complexity of oviduct, ovisac, jelly layer of the ovum, and egg sac in hynobiid salamanders. We examined female Salamandrella keyserlingii in preovulatory (gravid) and ovulatory (spent) conditions using anatomical, histological, and histochemical methods. Each ovum was covered with two jelly layers. All ova from one oviduct fell into one egg sac. Inner space of the oviduct, in which ova were passed through, was filled with jelly-like substances designated as «intermediate fluids». We named the membrane-like outer layer of the egg sac as «theca». Jelly layers surrounding the ovum were formed by the oviducal tubular glands of the pars recta and pars convoluta of the oviduct, consisting of acidic and neutral glycoproteins. In the ovisac (i.e., homologous uterus), there were three glandular regions and one aglandular dilatable ovisac. Of the ovisac, glands A, B, and C secreted acidic and neutral glycoproteins for the intermediate fluids, neutral glycoproteins for the theca, and mucus-like materials with a neutral glycoprotein nature, respectively. We suggest that these mucus-like materials are essential to attaching the adhesive tips of the egg sacs to some substrates during oviposition

Spermatogenesis in the Siberian salamander, Salamandrella keyserlingii (Caudata: Hynobiidae)

Spermatogenic cycles of hynobiid salamanders are interesting for the study of male reproductive adaptations in amphibians living under different environmental conditions. In order to detect the main differences between spermatogenic cycles of hynobiids, we studied the spermatogenic cycle of Salamandrella keyserlingii from the suburbs of Tomsk (southeastern Western Siberia) and compared it with those in the literature of hynobiids from different regions of Asia. We histologically and histochemically examined the testes of males captured from April to September. In April, the testes of males entering breeding sites contained bundles of spermatozoa (Sz) and primary (Sg I) and secondary spermatogonia (Sg II). After spermiation and breeding, Sg II began to proliferate. Meiosis of spermatocytes occurred in late June through July. The spermiogenesis began in late July; spermatids and Sz appeared in August. In September, Sz, Sg I, and Sg II were found in testes, which was also when Sg II proliferated. There are two types of spermatogenic cycles in the studied salamanders. The first one includes one period of spermatogonial proliferation (SP) in the first half of the active season. The second type consists of two periods of SP, with one occurring at the beginning and the other at the end of the active season. To identify possible differences in hynobiid spermatogenic cycles, we tested the relation of the duration of active season (DAS), the duration of SP period in the first half of cycle (DSPP), and the number of SP periods per year (NSPPs), considering environmental (air) temperatures in these species’ habitats. We could not find a direct relationship between NSPPs and air temperatures, but DAS and DSPP were correlated with temperature. We assume that two periods of SP can play the most apparent adaptive role in S. keyserlingii in a subarctic climate and in Batrachuperus tibetanus under mountain conditions

Histological and immunohistological aspects of the ovarian cycle of the algerian wild sand rat, Psammomys obesus Cretzschmar, 1828.

The sand rat, Psammomys obesus, is largely used as a model for studying several metabolic disorders. In order to perform breeding laboratory conditions, the reproductive function of this species was investigated. Using histological and immunohistochemical techniques, several aspects of the ovaries were studied throughout the sexual cycle. During the ovarian cycle, the different stages of folliculogenesis, from primordial to Graafian follicle, have been shown; the differentiation of both granulosa and theca cells, the formation of the antrum, cumulus oophorus and corona radiate were described. Broken follicles and corpora lutea have been observed, confirming a spontaneous ovulation in isolated females. Steroid activities were analysed using immunohistochemical techniques. Estrogen, androgen and progesterone hormones were visualized in the different compartments of the ovary

Morphometry and immunohistochemistry of follicles growth and steroidogenesis in saharian wild sand rat, Psammomys obesus, ovary.

The sand rat (Psammomys obesus) constitutes a model to study seasonal changes and several metabolic disorders. In order to perform breeding laboratory conditions, the reproductive function of this species living in North Occidental Algerian Sahara was studied. The aim of this work was to investigate the follicular growth changes and the steroidogenic associated aspects. The study was performed using morphometrical and immunohistochemical methods. From primordial to preantral states, the follicle diameter increased progressively from 17-20 mum to 192-225 mum. The preovulatory follicles reached about 500 mum in diameter. Immunoreactivity to progesterone, androstenediol and estradiol, varied in the different parts of the ovary and follicular cells. The progesterone antibody appeared clearly labelled in the theca interna of the growing follicle and increased in the granulosa; the androgen antibody was continuously weak and diffuses in all follicles; the estradiol labelling appeared weak and diffuse in preantral follicles then increased in antral follicles in both theca and granulosa or only in granulosa. In antral follicles, estradiol label was clearly localized in granulosa cells and totally devoid in theca cells. In Psammomys ovary, labels of hormone were diffuse or localized, weak or intense in the theca and or in the granulosa according to the follicle size

Study of the hydromineral regulation of Typhlonectes compressicauda according to the seasonal variation

Introduction. Typhlonectes compressicauda is a viviparous gymnophionan amphibian living in tropical areas of South America. This lengthened amphibian is submitted to seasonal variations characterized by the rainy season (from January to June) and the dry season (from July to December). The mineral homeostasis in amphibians is partly ensured by the neurohormones arginine-vasotocin (AVT), and mesotocin (MST). These two hormones were localized in the hypothalamus, and their receptors, mesotocin receptors (MTR) and vasotocin receptors (VTR2) in the kidney. The aim of the study was to better understand the physiology of the hydromineral regulation of the studied species. Material and methods. The specimens of T. compressicauda male and female adult were divided into 6 groups: males in the rainy season, males in the dry season, females pregnant in the rainy season, females pregnant in the dry season, females not pregnant in the rainy season, females not pregnant in the dry season. We studied the expression of hormones (AVT, MST) and their receptors (MTR, VTR2) in the hypothalamus and the kidney, respectively, by immunohistochemical and histological techniques. We also studied the expression of aquaporin-2 (AQP2), a water-channel protein in the kidney. Results. We found that the MST (diuretic hormone) and its receptor were more intensively expressed during the rainy season, whereas the period of maximal AVT (anti-diuretic hormone) and VTR2 expression was the dry season. A quantitative analysis showed significant differences in the number of labeled cells in the hypothalamus depending on the seasonal variation. The expression of AQP2 was observed in renal tubules during both seasons with an increased intensity during the dry season. Conclusion. The expression of the MST/AVT in brain, their receptors MTRs/VTR2, and AQP2 in kidney changed in T. compressicauda according to the seasonal variations. A direct relationship between the seasonal cycle and reproduction cycle was demonstrated in this species

Harmful Effects of Nanoparticles on Animals

Since several years nanoparticles (NPs) are produced by industries and used in several fields of activities. They are finally found in aquatic and terrestrial environments, where they are ingested by living organisms in which they accumulate, before being eliminated. In organisms, NPs represent foreign elements with their own physicochemical properties due to their small size. So NPs may interfere with the normal physiological mechanisms of the embryos, growing animals, and adults, and it is indispensable to understand their potentially direct or indirect harmful effects on living organisms. It has been already shown that NPs could be toxic to bacteria, algae, invertebrates, and vertebrates. In this review, several examples of recent studies are given. We will examine successively the effects of NPs on terrestrial and semiaquatic and aquatic vertebrate and invertebrate animals

Relationships between calpains and glutamate- or kainate-induced apoptosis in Xenopus laevis tadpoles

Abstract: Cell glutamate-damage induced by overstimulation of ionotropic receptors is initiated by modification of the intracellular Ca2+ homeostasis and the concomitant activation of Ca2+-dependent cysteine proteases, the calpain and caspase families. The resultant cleavage of target molecules mediates a critical function in the execution of the cell death. In this work, we investigated relationships between the activity of calpain and glutamate-orkainate-induced apoptosis in several organs of Xenopus laevis tadpole. Animals (stage 48) were incubated for 3 hours with glutamate (30–120 mM) or kainate (0.015–0.75 mM) and the rise of both apoptosis and calpain was observed in several organs. Our results indicated that glutamate (120 mM) or kainate (0.15 mM) exposure induced cell death with apoptotic features. The toxic effects of drugs into the organs were variable. Apoptosis was probably not the only form of cell death and option of necrosis or apoptosis was depending on the stimulation degree of the receptor, i.e. the receptor type, intensity and time course of molecule exposure. The increase of ubiquitous calpain was not correlated with the peak of apoptosis, suggesting the role of calpain in cell death was complex: calpain and caspase pathways were tightly interrelated in the glutamate- or kainate-induced cell death and the contribution of calpain to another type of death than apoptosis was perhaps preferred