Association of the estrogen receptor alpha gene polymorphisms with osteoporosis in the Mexican population.

The estrogen receptor gene (ER alpha) has been implicated in the development of osteoporosis. In this study, the association of two ER alpha gene polymorphic markers (a TA dinucleotide repeat and a single nucleotide polymorphism, G2014A) with osteoporosis was tested in 70 osteoporotic women, 70 non-osteoporotic women and 500 subjects from the Mexican population. According to the genetic analysis of the Mexican population using eight unlinked polymorphic markers, we found that our population is structured into three subpopulations; therefore, the allele-phenotype relationship was analyzed with a statistical method that considered population stratification. We found that the G2014A polymorphism is associated with the presence of osteoporosis while the TA dinucleotide repeat is not. The G allele and the GG genotype frequencies of the G2014A marker were significantly higher in osteoporotic than in non-osteoporotic women. Likewise, subjects bearing the G allele in heterozygous or homozygous displayed lower values for lumbar bone mineral density and T score than those who did not present any G allele. The effect of confounders for osteoporosis on the association of G allele-osteoporosis was ruled out. In summary, we conclude that the G2014 polymorphism may become a useful marker for genetic studies of osteoporosis in the Mexican population.

Biodiversity of rocky intertidal benthic communities associated with copper mine tailing discharges in northern Chile.

Copper mine tailings have been discharged around the city of Chanaral, in northern Chile, for more than 60 years. This report summarizes a 17-month long monitoring study of species richness and biodiversity at five intertidal sites around the point of the tailing discharge. Total dissolved copper in sites close to the point of discharge varied between 8.72 microg/l and 34.15 microg/l, showing that there has not been a significant reduction since 1994. However, species richness has increased, suggesting a possible recovery of the system. While diversity of sessile organisms correlates negatively with dissolved copper, diversity of mobile invertebrates did not correlate with the metal concentration. To explain the observed results we discuss the role of algal turf interference on the distribution of mobile invertebrates at reference sites, a top-down effect caused by the absence of carnivores at impacted sites, and an avoidance strategy by some species to reduce their contact with contaminated seawater.

Infectious diseases in Mazzaella laminarioides (Rhodophyta): estimating the effect of infections on host reproductive potential.

Very little is known about the potential effects of endophytic infections on the host in algae, especially in terms of fitness. In this study, we report a first attempt at quantifying the effects of the endophytes Endophyton ramosum (Chlorophyta) and Pleurocapsa sp. (Cyanophyta) on the reproductive potential of their host Mazzaella laminarioides (Rhodophyta). Density of reproductive structures and spore germination rates was compared between infected and non-infected fronds. It was found that differences in density of reproductive structures between infected and non-infected fronds were not significant, which suggests that the level of maturity of the host is unaltered by the endophytes. On the other hand, carpospore germination rates significantly decreased when produced by fronds infected by the cyanobacterium Pleurocapsa sp. Thus, in the general context of host fitness, we discuss the fact that only some of the components of the reproductive output of M. laminarioides are negatively affected by the endophytes.