Search

I mitili rappresentano un modello sperimentale particolarmente idoneo per il biomonitoraggio perché sono organismi sessili e filtratori con un elevato potenziale di bioaccumulazione e un basso potenziale di biotrasformazione (Ortiz et Al., 2006). Tra i contaminanti organici largamente diffusi in aree marine costiere a forte impatto antropico si trova una vasta categoria di sostanze chimiche che interferiscono con il sistema endocrino: i distruttori o interferenti endocrini. Uno degli effetti di tali molecole è l’induzione della sintesi di vitellogenina (VTG), una lipofosfoglicoproteina prodotta dai geni presenti nel fegato di femmine sessualmente mature; nelle femmine sessualmente immature e nei maschi i geni della VTG sono silenti, per cui in tali esemplari la presenza della VTG è considerata un importante biomarker per l’individuazione di composti estrogenici ambientali (Polzonetti-­‐ Magni et al, 2004). Nei vertebrati le VTG sono state ampiamente caratterizzate, a differenza degli invertebrati ed in particolare dei molluschi, dove le indagini relative alla VTG sono ancora limitate e soprattutto non conclusive (Pipe, 1987; Osada et al., 2004; Matsumoto et al., 2008). Scopo del nostro lavoro è determinare le sedi di sintesi della VTG in Mytilus galloprovincialis, un taxon che potrebbe rappresentare una valida specie sentinella da utilizzare in studi sull’inquinamento del Golfo di Napoli, dove noi operiamo. Le nostre indagini hanno dimostrato che la sintesi di VTG avviene solo nella gonade femminile, in particolare negli ovociti e nelle cellule follicolari e connettivali. L’attività di sintesi è evidente già in ovociti nelle prime fasi di accrescimento, caratterizzati da un citoplasma con numerose cisterne di RER e complessi di Golgi circondati da placchette vitelline in formazione; la sintesi della VTG continua negli ovociti che assumono una forma a pera, e progressivamente si riduce negli ovociti che hanno terminato l’accrescimento. Alla sintesi della VTG partecipano anche le cellule follicolari e del connettivo che probabilmente operano un trasferimento di VTG all’ovocita, mediato da endocitosi. Nessuna attività vitellogenica è mai riscontrabile nella ghiandola digestiva. I dati nel loro insieme indicano fortemente che nella gonade di Mytilus galloprovincialis la vitellogenesi avviene parallelamente per autosintesi all’interno degli ovociti e per eterosintesi nelle cellule follicolari e connettivali.

The aim of this investigation was to assess the effects of nonylphenol (NP), an oestrogen-like environmental pollutant, on the vitellogenin (VTG) synthesis in adult males of the aplacental viviparous cartilaginous fish Torpedo marmorata. The VTG recovery in males is considered a biomarker of xeno-oestrogenic pollution as this lipophosphoglycoprotein is physiologically induced by oestrogens only in females of oviparous and ovoviparous vertebrates. Using in situ hybridization and immunohistochemistry, T. marmorata males injected with nonylphenol showed the presence of VTG in the liver and the kidney. In particular, vtg messenger (m)RNA and VTG protein were expressed in the liver, whereas in the kidney cells only the presence of VTG was recorded. By contrast, no expression for VTG was detected in the testis. These results demonstrate that in T. marmorata NP induces the expression of vtg only in the liver; the presence of VTG in the kidney and its absence in the testis are discussed.

Glyphosate (Gly) is a broad-spectrum herbicide widely used thanks to its high efficiency and low toxicity. However, evidence exists of its toxic effects on non-target organisms. Among these, the animals inhabiting agricultural fields are particularly threatened. Recent studies demonstrated that exposure to Gly markedly affected the morphophysiology of the liver and testis of the Italian field lizard Podarcis siculus. The present study aimed to investigate the effects of the herbicide on the female reproductive system of this lizard in order to have a full picture of Gly-induced reproductive impairment. The animals were exposed to 0.05 and 0.5 μg/kg of pure Gly by gavage for 3 weeks. The results demonstrated that Gly, at both doses tested, profoundly interfered with ovarian function. It induced germ cells’ recruitment and altered follicular anatomy by anticipating apoptotic regression of the pyriform cells. It also induced thecal fibrosis and affected oocyte cytoplasm and zona pellucida organizations. At the functional levels, Gly stimulated the synthesis of estrogen receptors, suggesting a serious endocrine-disrupting effect. Overall, the follicular alterations, combined with those found at the level of the seminiferous tubules in males, suggest serious damage to the reproductive fitness of these non-target organisms, which over time could lead to a decline in survival.

The expansion of agriculture produces a steady increase in habitat fragmentation and degradation due to the increased use of pesticides and herbicides. Habitat loss and alteration associated with crop production play an important role in reptile decline, among which lizards are particularly endangered. In this study, we evaluated testicular structure, steroidogenesis, and estrogen receptor expression/localization after three weeks of oral exposure to glyphosate at 0.05 and 0.5 μg/kg body weight every other day in the field lizard Podarcis siculus. Our results show that glyphosate affected testicular morphology, reduced spermatogenesis, altered gap junctions and changed the localization of estrogen receptors in germ cells, increasing their expression; the effects were mostly dose-dependent. The result also demonstrates that glyphosate, at least at these concentrations, did not influence steroidogenesis. Overall, the data indicate that this herbicide can disturb the morphophysiology of the male lizard’s reproductive system, with obviously detrimental effects on their reproductive fitness. The effects of glyphosate must be considered biologically relevant and could endanger the reproductive capacity not only of lizards but also of other vertebrates, including humans; a more controlled and less intensive use of glyphosate in areas devoted to crop production would therefore be advisable.

Obesity and overweight are frequently associated with male subfertility. To address new findings on the players involved in the obesity-induced impairment of spermatogenesis, we used a high-fat diet-induced overweight-rat model. Following four weeks of high-fat diet, the organization of seminiferous epithelium was affected, and tubules lumen showed immature/degenerated cells, typical signs of hormonal imbalance and testicular damage. Real-time PCR analysis allowed us to detect increased levels of ERα and decreased levels of aromatase CYP19 transcripts in testis, suggesting an increase in circulating estrogens derived from the accumulating adipose tissue rather than the induction of testicular estrogen synthesis. Moreover, in situ hybridization analysis showed an increased susceptibility towards estrogens in testis from high-fat fed rats, being ERs expressed not only in spermatogonia, as in control testis, but also in spermatids. Western blot and immunohistochemical analyses revealed an increase in the amount of p53 and PCNA, together with a change in their immunodetection, being the proteins localised on germ cells at different stages of maturation. Differences in p53 and PCNA expression may give evidence and be part of a cellular response to stress conditions and damage caused by the excessive intake of saturated fatty acids.

Spermatogenesis is a fascinating biological process aiming to generate haploid spermatozoa from diploid spermatogonia through a specific hormonal network between gonadotropins and steroids. Increasing evidence suggests that the primary female sex hormone estrogen plays an active role in this process. This research points out on the role of estrogen during lizard spermatogenesis by using three experimental approaches: (1) exposure to an analogue of nonsteroidal estrogen as Clomiphene citrate that acts both as estrogen agonist and antagonist; (2) exposure to the gonadotropin FSH; and (3) exposures to FSH followed by Clomiphene. Histological and immunohistochemical results demonstrate that in the lizardPodarcis siculaduring the mating period, Clomiphene as well as FSH determines the breakdown of spermatogenesis and the epididymal regression, presumably through estrogens input as indirectly demonstrated by the appearance of ERαand vitellogenin in the liver. The ability of Clomiphene to restore the gonadal natural condition after FSH treatment is also demonstrated. Finally, data indicate that lizard testis and epididymis control their morphophysiology regulating the intracellular presence of ERα.

The Heat Shock Proteins (HSPs) are a superfamily of molecular chaperones that maintain cellular homeostasis under stress. HSP70 represents the major stress-inducible family member, often activated in response to changes in thermal ranges of organisms, and therefore playing an important role enhancing thermal tolerance limits in ectothermic animals. The present study aimed to investigate the presence and the localization of HSP70 through the development of Podarcis siculus, an oviparous lizard inhabiting temperate Mediterranean regions, showing a limited potential to tolerate thermal changes during embryogenesis. Immunohistochemical analysis demonstrated that HSP70 protein is constitutively present in early embryonic stages, abundantly distributed in eye, in encephalic domains (predominantly in ventricular areas and in grey matter), in grey matter of spinal cord, in lung, gut mucosa, hepatic cords and kidney tubules. Interestingly, a severe drop in incubation temperature (5 °C for 3 days) does not induce enhancements in HSP70 levels nor changes in tissues localization. These results suggest that the HSP70 found in P. siculus embryos represents a non-inducible, constitutive molecular chaperone that should be better called Heat Shock Cognate 70 (HSC70); the presence of stress-induced members of the HSP family in P. siculus has yet to be proven.