1,720,995 research outputs found
Histological and histochemical study of female germ cell development in the dusky grouper Epinephelus marginatus (Lowe, 1834).
No full textThe developmental stages of female germ cells were analysed in a wild population of the protogynous teleost Epinephelus marginatus (Lowe, 1834). 321 wild dusky grouper females were collected in the South Mediterranean Sea during the spawning season and their ovaries analysed using histological and histochemical techniques. Oocyte morphology, nucleus-cytoplasm ratio (N/C) range, location and movements of cytoplasmic inclusions during primary growth, vitellogenesis and final oocyte maturation were described. The distribution of proteins, lipids and carbohydrates through oocyte development was also investigated in 50 females. Lipid vesicles appeared firstly in the mid ooplasm of oocytes larger than 130mm, at the beginning of the secondary growth phase. Immediately afterwards, small carbohydrate granules (PAS and Alcian blue positive) appeared before the occurrence of the first yolk granules. Tyrosine-enriched proteins were especially evidenced in the zona radiata interna of late vitellogenic oocytes. Specific lectin binding patterns reflected characteristic differences in the content and distribution of specific sugar moieties expressed in the oocytes during vitellogenesis and final maturation. At the end of vitellogenesis and during final maturation, follicular cells, zona radiata, and cortical alveoli were characterised by a strong increase of specific binding for WGA
Annual sex steroid levels in cultured dusky grouper females
No full textThe dusky grouper Epinephelus marginatus is a proteroginic hermaphrodite that exhibits a complex reproductive biology. Under captive condition most females do not proceed into vitellogenesis and do not spawn spontaneously. Sex-steroids profiles during the reproductive cycle have been recently studied in the wild (Marino et a. 1997), but no data are available on sex steroids levels in cultured fish. This study describes the seasonal variation of 17ß-estradiol (E2) and testosterone (T), 11-ketotestosterone (11-KT) and 11ß hydroxyandrostenedione (OHA) plasma levels in dusky grouper females
First observation of intersex cyprinids in the Po River (Italy)
No full textBarbel ŽBarbus plebejus, Cyprinidae. were captured in the Po River, upstream and downstream from the confluence of the Lambro River, a polluted tributary of the major Italian watercourse. The gonads of the two groups of barbel have been histologically examined, and only the downstream specimens showed histo-morphological alterations that can be related to the Lambro tributary as a source to the main river of endocrine disrupting chemicals, possibly with estrogenic effects. In fact, 50% of the barbel captured Ž8 of 16 fish. in the downstream reach showed intersex gonads
Molecular and endocrinological monitoring for artificial reproduction in new finfish species
No full textThe sex steroid pattern during sex inversion in the dusky grouper, Epinephelus marginatus, was studied. In vivo and in vitro technoques were performed to investigate steroidogenesis and final maturation of oocytes in Seriola dumerilii during the reproductive season. Preliminary results on isolation and purification of vitellogenin in E. marginatus are also presented in this study
Endocrine disrupting chemicals (EDC) with (anti)estrogenic and (anti)androgenic modes of action affecting reproductive biology of Xenopus laevis: Effects on sexual steroids levels and biomarker expression in the liver
No full textAdult Xenopus laevis were exposed in vivo to ethinylestradiol, tamoxifen, methyldihydrotestosterone and flutamide as (anti)estrogenic and (anti)androgenic compounds, respectively, for four weeks at a concentration of 10(-8) M and to Lambro river water, a polluted river from Italy. Effects of the treatments were analysed by mRNA expression of retinol-binding protein (RBP), transferrin (TF), transthyretin (TTR) and vitellogenin (VTG) in the liver of male and female X. laevis, to analyse the potential of these genes to detect endocrine disrupting compounds (EDC) with different modes of action. In addition, plasma VTG and sex steroid levels, estradiol-17beta (E(2)) and testosterone (T), were analysed. Sex steroids were depressed by ethinylestradiol in both sexes whereas tamoxifen increased E(2) in females. The induction of VTG protein plasma levels was more pronounced at the protein level compared to hepatic VTG mRNA expression in response to estrogenic treatment but VTG mRNA expression detected both, estrogenic and antiestrogenic EDC. The mRNA expression of TF was decreased by estrogenic and increased by antiestrogenic treatment while TTR mRNA expression was down-regulated and RBP mRNA up-regulated by estrogenic exposure. The other treatments did not affect the mRNA expression of the examined genes
17α-20ß-dihydroxy-4-pregen-3-one levels during the spawning period in wild amberjack (Seriola dumerilii).
No full textSeriola dumerilii, (Carangidae, Perciformes) is a gonochoric teleost occurring in the Mediterranean Sea. Despite the growing interest for this species, little is known on sex steroid pattern during the reproductive season. Aim of this study was to verify if 17-20ß-dihydroxy-progesterone (DHP) could be involved as maturation inducing substance (MIS) in S. dumerilii as in other species. 244 females of wild S. dumerilii were collected in South Mediterranean Sea (Pelagie Islands), during three spawning seasons and histologically staged. Blood samples were withdrawn by puncturing the gill artery and plasma aliquots were frozen at -20°C for steroid RIAs. DHP plasma values were measured in wild females at the end of vitellogenesis and during final maturation (FOM). DPH values were related both to 17ß-estradiol and testosterone values and to morphological features of oocytes. All specimens with ovaries characterised by a population of oocytes undergoing FOM, showed a significant increase (P<0.01) in DHP value. Furthermore, we analysed DHP plasma values in relation to three different stages occurring during FOM. Early FOM, including GV migration and lipid droplets coalescence, showed the first increase in DHP values (xxpg/ml±xx). Middle FOM corresponding to GVBD was characterised by the higher values of DHP (xxxpg/ml±xx). In late FOM (hydration), DHP started to decrease (xxxpg/ml±xxx). These results suggest that DHP could be considered as the MIS in S. dumerili
Sex steroid and vitellogenin plasma levels in intersexual fish captured in a polluted area of the Po river.
No full textImmature rainbow trout females (Oncorhynchus mykiss, n=250) were exposed for 10 and 23 days to waters collected from the River Lambro, which drains areas characterized by severe anthropic pressure. Water was collected every two days and analysed for wide-spread xenoestrogens such as 4-nonylphenol (NP) and octylphenol (OP). Fish were exposed to graded concentrations of Lambro water in a flow-through system. Five aquaria, respectively containing tap unchlorinated water (negative control), 10%, 20% and 40% Lambro and 20% sewage effluent (positive control) were set up (C, L10, L20, L40 and EF20, respectively). Plasma levels of vitellogenin (Vtg), 17ß-oestradiol (E2) and testosterone (T) were measured. Histomorphological aspects of gonads and liver were also evaluated. Significant increase of plasma steroid and Vtg levels were observed in L40 fish after 10-day exposure. E2 significantly increased after 23-day exposure, in a dose-dependent manner. E2 and Vtg levels were never correlated in any of the treated fish. After 23-day exposure, a marked decrease of T levels in L40 and EF20 was observed
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