Cadmium contaminated soil affects retinogenesis in lizard embryos

Abstract

Lizards are soil surface animals that represent an important link between invertebrates and higher predators. Being part of wild fauna, they can be affected by contamination from anthropic activities and in particular, pesticides and chemical substances of various nature that reach the soil surface directly or through fall out. Among these substances, heavy metals such as cadmium may exert particularly marked toxic effect on both adult and embryos. In lizards, recent studies show that cadmium may cause developmental defects, including alteration of eye development, with appearance of unilateral microphthalmia and retinal folding. In the present study, the effects of cadmium incubation on retinal development were investigated demonstrating that cadmium interferes with cell cycle regulation by increasing proliferation. An increased expression of Otx2 and Pax6 genes, markers of retinal differentiation, was also found. However, the cellular localization of Pax6 and Otx2 transcripts did not change in treated embryos: in the early stages of retinogenesis, the two genes were expressed in all retinal cells; in the differentiated retina, Otx2 remained in the cellular bodies of retinal cells forming the nuclear and the ganglion layers, whereas Pax6 was expressed only in the cells of the inner nuclear and the ganglion layers. Data suggest that the increased expression of Pax6 and Otx2 could be ascribed to the hyperproliferation of retinal cells rather than to an effective gene overexpression.

The expression of estrogen receptors during the Mytilus galloprovincialis ovarian cycle

“…In situ hybridization was carried out as described elsewhere (Agnese et al, ; Agnese, Valiante, Rosati, Andreuccetti, & Prisco, ; Prisco et al, ; Simoniello et al, ). Dig‐labeled ER1 and ER2 complementary DNA probes were generated by PCR using the Dig‐DNA labeling mix (Roche Diagnostics, Indianapolis, IN).…”

The Broad-Scale Analysis of Metals, Trace Elements, Organochlorine Pesticides and Polycyclic Aromatic Hydrocarbons in Wetlands Along an Urban Gradient, and the Use of a High Trophic Snake as a Bioindicator

“…Developing embryos can also be exposed to metals through the egg shell (Marco et al 2004). Consequently, absorption of Cd can cause malformation of eye development in the Italian wall lizard (Podarcis sicula) (Simoniello et al 2014) and the running speed of hatchling Iberian rock lizard (Iberolacerta monticola) was negatively correlated with embryonic As absorption (Marco et al 2004). Metal body burdens or exposure levels that cause physiological or behavioural alterations in the aforementioned studies are well above what we observed in the livers of our adult tiger snakes from the Swan Coastal Plain; however, chronically contaminated reptiles are susceptible to a variety of pernicious developmental and behavioural disorders.…”

Effects of Cadmium Sulfate on the Brown Garden Snail Cornu aspersum: Implications for DNA Methylation

“…This evolutionary conserved epigenetic mark [9] occurs via covalent addition of a methyl (CH 3 ) group to the 5 -carbon position of cytosine pyrimidine ring primarily found in cytosine-guanine (CpG) dinucleotides [10]. Global and gene-specific changes in 5mC content associated with Cd exposure have been described in most vertebrate classes [11][12][13][14][15]. However, limited information exists for terrestrial invertebrates routinely used as sentinel organisms, such as annelids [16] or land snails [7].…”