A decreased mitochondrial DNA content is related to insulin resistance in adolescents

The aim of this study was to investigate whether mitochondrial DNA (mtDNA) content is associated with insulin resistance (IR) in a sample of adolescents with features of metabolic syndrome. We further studied the link between polymorphisms in three genes involved in mitochondrial biogenesis and the presence of deleted mtDNA and mtDNA content. Data and blood samples were collected from 175 adolescents out of a cross-sectional, population-based study of 934 high school students. On the basis of the median value of homeostasis model assessment of IR (HOMA-IR) of the whole sample (2.2), the population was divided into two groups: noninsulin resistance (NIR) and IR. mtDNA quantification using nuclear DNA (nDNA) as a reference was carried out using a real-time quantitative PCR method. Genotyping for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) (pro12Ala), PPAR- gamma coactivator-1alpha (PGC-1alpha) (Gly482Ser), and Tfam (rs1937 and rs12247015) polymorphisms was performed by PCR-based restriction fragment length polymorphism. Long-extension PCR was performed to amplify the whole mitochondrial genome. The mtDNA/nDNA ratio was significantly lower in the IR group (median: 9.08, range: 68.94) in comparison with the NIR group (12.24, 71.92) (P<0.03). Besides, the mtDNA/nDNA ratio was inversely correlated with HOMA (R: -0.18, P<0.02), glucose (R: -0.21, P<0.008), and uric acid (R: -0.18, P<0.03). Genotypes for the PPAR- gamma, PGC-1alpha, and Tfam variants were not associated with the mtDNA/nDNA ratio. Long-extension PCR did not show significant levels of mtDNA deletions. In conclusion, our findings indicate that reduced mtDNA content in peripheral leukocytes is associated with IR. This result seems not to be related with the previously mentioned variants in genes involved in the regulation of mitochondrial biogenesis.     

Reversible effect of potassium sorbate on Balanus amphitrite larvae. Potential use as antifoulant

Marine biofouling constitutes a major worldwide technical and economic problem. International regulations concerning the protection of both the environment and industrial workers have prompted paint manufacturers and end users to look for suitable replacements for traditional antifouling (AF) pigments. For this reason, the potential AF activity of potassium sorbate (KS) on nauplii and cyprids of Balanus amphitrite was tested in laboratory and field trials. Larval bioassays demonstrated a marked inhibitory and reversible effect. The values obtained for EC₅₀ and LC₅₀ were 9.91 mM and 36.73 mM, respectively, and the therapeutic ratio was 3.71, indicating that KS acts via a non-toxic mechanism. After 60 days in the sea, a varnish coating incorporating KS showed a substantial decrease in micro- and macrofouling density and diversity. This investigation indicated that KS is a promising AF agent for replacing the traditional toxic compounds.     

Comparison of diurnal variation of airborne pollen in Mar del Plata (Argentina)

Intradiurnal variation of arboreal pollen (AP) in Mar del Plata city is compared during three non - consecutive years of survey and described in relation to the associated weather. The daily pattern of pollen abundance has a maximum between 10:00 and 12:00?h, while a minimum occurs at 18:00?h. The first two years of survey showed homogeneous daily trends, but in 1995 the maximum and minimum concentrations were delayed because of the change in position of the collecting station. Arboreal pollen spectrum presented qualitative and quantitative changes in the three years analysed. Results indicate optimal conditions for diurnal dispersion of arboreal pollen are high temperatures and low relative humidity. Also interaction between source position and wind direction has important effects on the timing of the peaks of some pollen types.     

Glycogen synthase kinase-3 beta regulates NF-kappa B1/p105 stability

A number of different kinases have been implicated in NF-kappa B regulation and survival function. Here we investigated the molecular cross-talk between glycogen synthase kinase-3 beta (GSK-3 beta) and the p105 precursor of the NF-kappa B p50 subunit. GSK-3 beta forms an in vivo complex with and specifically phosphorylates NF-kappa B1/p105 at Ser-903 and Ser-907 in vitro. In addition, the p105 phosphorylation level is reduced in fibroblasts lacking GSK-3 beta as compared with wild-type cells. GSK-3 beta has a dual effect on p105: it stabilizes p105 under resting conditions and primes p105 for degradation upon tumor necrosis factor (TNF)-alpha treatment. Indeed, constitutive processing of p105 to p50 occurs at a higher rate in cells lacking GSK-3 beta with respect to wild-type cells and can be reduced upon reintroduction of GSK-3 beta by transfection. Moreover, p105 degradation in response to TNF-alpha is prevented in GSK-3 beta-/- fibroblasts and by a Ser to Ala point mutation on p105 at positions 903 or 907. Interestingly, the increased sensitiveness to TNF-alpha-induced death occurring in GSK-3 beta-/- fibroblasts, which is coupled to a perturbation of p50/105 ratio, can be reproduced by p105 silencing in wild-type fibroblasts.     

Possible Balancing Selection in Human Female Homosexuality

A growing number of researchers suggest that female homosexuality is at least in part influenced by genetic factors. Unlike for male homosexuality, few familial studies have attempted to explore maintenance of this apparently fitness-detrimental trait in the population. Using multiple recruitment methods, we explored fecundity and sexual orientation within the pedigrees of 1,458 adult female respondents. We compared 487 homosexual and 163 bisexual with 808 heterosexual females and 30,203 of their relatives. Our data suggest that the direct fitness of homosexual females is four times lower than the direct fitness of heterosexual females of corresponding ages. The prevalence of nonheterosexuality within the homosexual female respondents’ families (2.83%) appear to be more than four times higher than the basal prevalence in the Italian population (0.63%). Pedigree size and relative fecundity in both the paternal and maternal sides of the homosexual women’s families were significantly higher than in the heterosexuals’ families. If confirmed, the relative average fecundity increase within the family seems to offset the loss in fitness due to the low direct fitness of homosexual females. Therefore, the balanced fecundity in the homosexual females’ families may allow the trait to be maintained at a low-frequency equilibrium in the population.     

Heterogeneity of heterochromatin in six species ofCtenomys (Rodentia: Octodontoidea: Ctenomyidae) from Argentina revealed by a combined analysis of C- and RE-banding

Exceptional chromosomal variability makesCtenomys an excellent model for evolutionary cytogenetic analysis. Six species belonging to three evolutionary lineages were studied by means of restriction endonuclease and C-chromosome banding. The resulting banding patterns were used for comparative analysis of heterochromatin distribution on chromosomes. This combined analysis allowed intra- and inter-specific heterochromatin variability to be detected, groups of species belonging to different lineages to be characterized, and phylogenetic relationships hypothesized from other data to be supported. The “ancestral group”,Ctenomys pundti andC. talarum, share three types of heterochromatin, the most abundant of which was also found in C. aff.C. opimus, suggesting that the latter species also belongs to the “ancestral group”. Additionally, within the subspeciesC. t. talarum, putative chromosomal rearrangements distinguishing two of the three chromosomal races were identified. Two species belong to an “eastern lineage”,C. osvaldoreigi andC. rosendopascuali, and share only one type of heterochromatin homogeneously distributed across their karyotypes.C. latro, the only analyzed species from the “chacoan” lineage, showed three types of heterochromatin, one of them being that which characterizes the “eastern lineage”.C. aff.C. opimus, because of its low heterochromatin content, is the most primitive karyotype of the genus yet described. The heterochromatin variability showed by these species, reflecting the evolutionary divergence toward different heterochromatin types, may have diverged since the origin of the genus. Heterochromatin amplification is proposed as a trend withinCtenomys, occurring independently of chromosomal change in diploid numbers.