Clastogenic effects of bisphenol A on human cultured lymphocytes.

Bisphenol A is an endocrine disrupting compound widely used in the production of polycarbonate plastics and epoxy resins. It is ubiquitously present in the environment, mostly in aquatic environments, with consequent risks to the health of aquatic organisms and humans. In the present study, we analysed the cytogenetic effects of bisphenol A on human lymphocytes using in vitro chromosomal aberrations and micronuclei assays. Lymphocyte cultures were exposed to five different concentrations of BP-A (0.20, 0.10, 0.05, 0.02 and 0.01 µg/mL) for 24 h (for chromosomal aberrations test) and 48 h (for micronuclei test). The concentration of 0.05 µg/mL represents the reference dose established by United States Environmental Protection Agency (US EPA); 0.02 µg/mL represents the higher concentration of unconjugated BP-A found in human serum and 0.01 µg/mL represents the tolerable daily intake established by European Union. Data obtained from both assays showed significant genotoxic effects of the bisphenol A at concentrations of 0.20, 0.10 and 0.05 µg/mL, whereas at the concentration of 0.02 µg/mL, we observed only a significant increase in the micronuclei frequency. Finally, at the concentration of 0.01 µg/mL, no cytogenetic effects were observed, indicating this latter as a more tolerable concentration for human health with respect to 0.05 µg/mL, the reference dose established by US EPA.

Genotyping for cytokine polymorphisms in a Northern Ivory Coast population reveals a high frequency of the heterozygote genotypes for the TNF-α-308G/A SNP.

Cytokine polymorphisms influence the outcomes of parasitic diseases and vary among populations because of their different evolutionary histories and selective pressures imposed by host-pathogen interactions. In this frame, we investigated the frequencies of TNF-α (-308G/A), TGF-ß(1) (codon 10C/T, codon 25C/G) and IL-10 (-1082A/G) SNPs in 133 individuals from Ouangolodougou, a rural village in Northern Ivory Coast, where malaria and other parasitic diseases are endemic. The SNPs alleles were determined by ARMS-PCR methodology. Allele frequencies of the SNPs investigated were as follows: IL 10 -1082G = 0.741 and -1082A = 0.259; TGF-ß(1) Codon 10 C = 0.835 and T = 0.165; TGF-ß(1) Codon 25 G = 0.782 and C = 0.218. For the TNF-α gene, we found high frequencies of the -308A allele (0.305) and heterozygote genotypes (0.594), with a consequent deviation from the Hardy-Weinberg equilibrium. The high heterozygosity at the TNF-α locus suggests a possible selective advantage of the heterozygote genomes, associated with intermediate levels of TNF-α expression, against the infectious agents endemic in Western Africa.

Gender expression and group size: a test in a hermaphroditic and a gonochoric congeneric species of Ophryotrocha (Polychaeta).

Hermaphroditism and gonochorism are two contrasting forms of sexuality. Hermaphroditic species are generally seen as species adapted to conditions of low density, stabilized by poor mate search efficiency and high costs of searching. They can adjust allocation of reproductive resources to each sex function in response to current social conditions, making reproduction more efficient, at least in principle. By contrast, gonochorism (separate sexes) is advantageous when mates are frequent, making it ineffective to maintain two sex functions in a single individual. This, however, also rules out the need for a flexible response to mating opportunities as known for hermaphrodites. In the hermaphroditic marine polychaete worm Ophryotrocha diadema we showed earlier that group size is assessed through a chemical cue. In this study we verified the accuracy of the response to gradients of the chemical cue used to assess group size by O. diadema by checking reduction in egg production as the group of partners increases, as expected according to sex allocation theory. Furthermore we compared the effect of such a gradient with a similar gradient in a closely related gonochoric species (O. labronica). Here sex allocation adjustment is not predicted, thus an adaptive change in egg production in response to group-size cues is not expected. In fact, our results show that the group-size effect only occurs in O. diadema and not in O. labronica. Moreover, our study provides evidence of high perceptual abilities of chemical cues in O. diadema, suggesting that perceiving social cues and adjusting sex allocation appropriately are special properties of hermaphrodites.

Outcrossing hermaphroditic polychaete worms adjust their sex allocation to social conditions.

Sex allocation theory predicts that simultaneous hermaphrodites shift sex allocation facultatively in response to variation in local group size. This study was performed to evaluate the relative investment in each sex function by the simultaneously hermaphroditic polychaete worm Ophryotrocha diadema and to test whether allocation to each sex depends on the number of reproductive competitors. Four experimental groups were set up (in a 2 x 2 factorial design) with small or large group size and with small or large enclosures to control for potential confounding effects of density. We measured the proportion of female and male investment in focal individuals. Results revealed that individuals regulated their reproductive output so that when reproductive competitors were present, the number of female gametes was strongly reduced and the male function increased. In contrast, under monogamy, individuals in small groups produced lower numbers of sperm but had a higher egg output than worms in large groups. Density did not affect sex allocation in our experiment. Our findings provide qualitative support for Local Mate Competition theory, but also show that the pattern of sex allocation specific to this species is more complex than expected by current theory.