Molecular phylogenetics of mouse opossums: new findings on the phylogeny of Thylamys (Didelphimorphia,Didelphidae)

The mouse opossums of the genus Thylamys constitute a group of species mainly adapted to open xeric‐like habitats and restricted to the southern portion of South America. We used molecular data (mitochondrial and nuclear sequences) to evaluate the phylogenetic and biogeographical relationships of all currently known living species of the genus, recognizing a new taxon from the middle and high elevations of the Peruvian Andes and evaluating the phylogenetic structuring within T. pallidior and T. elegans, as well as the validity of T. sponsorius, T. cinderella and T. tatei, and the haplogroups recognized within T. pusillus. Our results confirm the monophyly of the genus and that the Caatinga and the Cerrado inhabitants Thylamys karimii and T. velutinus are the most basal species in the radiation of Thylamys. We also calibrated a molecular clock which hypothesized a time of origin of the genus of about 24 My, with most species differentiating in middle and late Miocene and Plio‐Pleistocene times of South America.     

Evidence for the persistence of an active endogenous retrovirus (ERVE) in humans

Transposable elements (TEs) account for nearly half (44 %) of the human genome. However, their overall activity has been steadily declining over the past 35–50 million years, so that <0.05 % of TEs are presumably still “alive” (potentially transposable) in human populations. All the active elements are retrotransposons, either autonomous (LINE-1 and possibly the endogenous retrovirus ERVK), or non-autonomous (Alu and SVA, whose transposition is dependent on the LINE-1 enzymatic machinery). Here we show that a lineage of the endogenous retrovirus ERVE was recently engaged in ectopic recombination events and may have at least one potentially fully functional representative, initially reported as a novel retrovirus isolated from blood cells of a Chinese patient with chronic myeloid leukemia, which bears signals of positive selection on its envelope region. Altogether, there is strong evidence that ERVE should be included in the short list of potentially active TEs, and we give clues on how to identify human specific insertions of this element that are likely to be segregating in some of our populations.     

The isolation of another new compound from the urine of humans with porphyria cutanea tarda

The present report deals with the isolation of Phyriazulin, another new compound, from human phorphyria cutanea tarda urine. The substance has been crystallized and some of its properties are described.     

Indole fragments for the design of lead molecules against pancreatitis

Abstract

Communicated by Ramaswamy H. Sarma     

Chronicle of an extinction foretold: genetic properties of an extremely small population of Iberolacerta monticola

The fragmentation and destruction of natural habitats by human intervention is producing a continuous and inexorable reduction of the size of populations in multitude of species all over the world. Small and isolated populations face higher extinction risks, due to demographic and environmental stochasticity, and also because of several genetic threats, among which inbreeding is considered the most important one. For many of these species, the extinction of a population is an irreversible event, so that determining the immediate importance of these risk factors and understanding their interactions is crucial for conservation plans. Iberolacerta monticola is a small lacertid endemic to the northwestern Iberian Peninsula, distributed mainly across moderate/high altitude mountainous regions. Some populations are found nearly at sea-level, though, in fluvial valleys with relict Atlantic forests, in the severely fragmented western part of its range. One of them has been dramatically reduced over the last 30 years, and presently is on the brink of extinction. Using microsatellite nuclear markers, we obtained different measures of genetic variation at this site, together with demographic and breeding data. Both the level of heterozygosity and the number of alleles per locus indicate that the level of variation in this population is comparatively high, and the average inbreeding coefficient is very low. Individuals appear healthy and long-lived, and are related by a few different lines of descent. These findings are discussed in the context of current theories and experimental evidence of associative overdominance and purging of the genetic load of populations, with special emphasis on the evolutionary potential of recovery of small evolutionary units.     

Laboratory characterization of residual sludge from natural gas extraction by hydraulic fracturing in the Burgos Basin,Mexico

Abstract

Pollutants and microbiota present in the residual sludge of hydraulic fracturing were determined and characterized physicochemically. Analyses included determination of pH, electric conductivity, organic matter percentage, as well as total carbonates, inorganic nitrogen and extractable phosphorous. In addition, presence of hydrocarbons by gas chromatography, potentially toxic elements (PTEs) by atomic absorption and presence of radioactive isotopes by gamma spectrometry were determined. Moreover, fungi and bacteria present in the residual sludge were classified taxonomically to the level of genus. Medium and heavy hydrocarbon fractions were found in concentrations above the maximum limits permitted (MLP) by Mexican environmental norms. Cu, Pb, Zn, Fe and Mg, however, were below the MLP. Likewise, gamma spectrometry analysis revealed naturally occurring Ac²²⁸, Ra²²⁶ and K⁴⁰. The microbiological analysis found presence of the bacteria Bacillus spp., Micrococcus sp., Diplococcus sp. and Staphylococcus sp. and the fungi Trichoderma sp., Aspergillus sp. and Penicillium spp.     

Subdermal contraceptive implants

Subdermal contraceptive implants involve the delivery of a steroid progestin from polymer capsules or rods placed under the skin. The hormone diffuses out slowly at a stable rate, providing contraceptive effectiveness for 1–5 years. The period of protection depends upon the specific progestin and the type of polymer. Advantages of progestin implants include long term contraceptive action without requiring the user's or provider's attention, low dose of highly effective contraception without the use of estrogen, and fertility is readily reversible after the removal of implants. The levonorgestrel implant Norplant R system is the only one that has been approved for distribution. The contraceptive efficacy of Norplant is the highest observed amongst the most effective methods with an annual pregnancy rate of 0.2 during the first and second year and 1.1 on the fifth year. Menstrual problems are the main reason for the discontinuation of Norplant and 9% of women stopped using it during the first year of treatment. Other implants are still under development trying to simplify the method by reducing the number of units and to introduce other progestins that may minimize side effects. Norplant-2 was designed to release the same dose of progestin from only two covered rods. Evaluation of 1400 women enrolled, indicates that over 2 years the cumulative pregnancy rate is below 0.5 per 100 women. There are three single implants under development: Nestorone, 3-Keto-desogestrel and Uniplant that are expected to be effective for 1–2 years. Phase II clinical trials with Nestorone have been completed and no pregnancies have been observed in 1570 woman-months of use. Bleeding irregularities occurred in 20–30% of the women but there were only four terminations because of bleeding problems. A multricentric study is ongoing with a newly designed 3-keto-desogestrel implant named Implanon, which releases approx. 60 μg/day of the hormone. The objectives of this study are to assess contraceptive efficacy, safety and acceptability of Implanon. Another multricentric study is ongoing with Uniplant, which releases nomegestrol acetate with a duration of action for only 1 year. The objectives of the trial are to study the endocrine profile of Uniplant users and to evaluate the efficacy and acceptability of the method.