Cubebin and derivatives as inhibitors of mitochondrial complex I. Proposed interaction with subunit B8

The effects on mitochondrial respiration and complex I NADH oxidase activity of cubebin and derivatives were evaluated. The compounds inhibited the state 3 glutamate/malate-supported respiration of hamster liver mitochondria with IC(50) values ranging from 12.16 to 83.96 microM. NADH oxidase reaction was evaluated in submitochondrial particles. The compounds also inhibited this activity, showing the same order of potency observed for effects on state 3 respiration, as well as a tendency towards a non-competitive type of inhibition (K(I) values ranging from 0.62 to 16.1 microM). A potential binding mode of these compounds with complex I subunit B8, assessed by docking calculations, is proposed.     

The effect of different glaciation patterns over the current genetic structure of the southern beech <Emphasis Type="Italic">Nothofagus antarctica</Emphasis>

Different regional patterns of glaciation are expected to have brought about a differential effect on the present genetic structure of natural tree populations in the temperate regions. The aim of the present study is to test this hypothesis in Nothofagus antarctica, a key tree species of the temperate forests of southern South America. An almost continuous ice layer characterized the region of the Andes south of 41°S, while towards northern latitudes the pattern was more fragmented. Therefore, a higher chance for the location of larger or more numerous glacial refuges in the north of the Argentinean range, leads us to predict a higher genetic diversity in this region. Twelve natural populations of N. antarctica were sampled along the northern half of its Argentinean range, including six above 41°S and six below that latitude. Sampled populations were genetically characterized through cpDNA and isozyme gene markers. Both groups of populations were compared by means of several diversity and differentiation parameters. A genetic structure analysis was conducted with isozyme data through clustering and Bayesian approaches. Based on three polymorphic chloroplast regions, only two haplotypes were distinguished, one corresponding to the nine northernmost sampled populations and the other to the two southernmost ones. Only the population located between those two groups resulted polymorphic. AMOVA analyses also revealed a latitudinal genetic structure for the populations surveyed, and higher levels of genetic variation were recognized in the northern populations.     

Detection of sialoglycomolecules in five plant trypanosomatids and in an insect phytophagous isolate

A mutation in the cell division gene ftsK causes super-induction of sigma(70)-dependent stress defense genes, such as uspA, during entry of cells into stationary phase. In contrast, we report here that stationary phase induction of sigma(S)-dependent genes, uspB and cfa, is attenuated and that sigma(S) accumulates at a lower rate in ftsK1 cells. Ectopic overexpression of rpoS restored induction of the rpoS regulon in the ftsK mutant, as did a deletion in the recA gene. Thus, a mutation in the cell division gene, ftsK, uncouples the otherwise coordinated induction of sigma(S)-dependent genes and the universal stress response gene, uspA, during entry into stationary phase.     

Differential effect of losartan in female and male spontaneously hypertensive rats

We demonstrated that the decreased response to acetylcholine observed in aorta of male and female spontaneously hypertensive rats is corrected after sustained (15 days) reduction of blood pressure levels by losartan. In order to verify if the same occurs in resistance vessels, vascular diameter changes induced by topical application of acetylcholine and bradykinin (endothelium-dependent vasodilators) and sodium nitroprusside (endothelium-independent vasodilator) to mesenteric arterioles studied in vivo, in situ were determined in rats treated with losartan for 24 h (acute) or 15 days (chronic). Rats that presented similar reduction (in %) of the blood pressure levels after losartan treatment were chosen. Sodium nitroprusside induced similar responses in losartan-treated and untreated male or female SHR. Whereas in female SHR, losartan corrected the diminished arteriolar response to endothelium-dependent vasodilators after acute and chronic treatment, in male SHR this correction only occurred after chronic treatment. Thus, losartan corrected the endothelial dysfunction more easily in female than in male SHR and independently of the normalization or the magnitude of the reduction of the blood pressure levels. In an attempt to explain the difference, we evaluated the losartan effect on nitric-oxide synthase (NOS) activity and angiotensin II AT1 and AT2 receptor gene expression in these animals. In male and female SHR, NOS activity and AT1 receptor expression were not altered by acute or chronic treatment. On the other hand, AT2 receptor expression was augmented only in female SHR by these treatments. Therefore, augmented AT2 receptor expression, but not alteration of NOS activity or AT1 receptor expression, might explain the difference observed.     

Use of near-infrared raman spectroscopy to detect IgG and IgM antibodies against Toxoplasma gondii in serum samples of domestic cats.

Near-infrared Raman spectroscopy (NIRS) is a particularly promising technique that is being used in recent years formany biomedical applications. Optical spectroscopy has gained increasing prominence as a tool for quantitative analysis of biological samples, clinical diagnostic, concentration measurements of blood metabolites and therapeutic drugs, and analysis of the chemical composition of human tissues. Toxoplasmosis is an important zoonosis in public health, and domestic cats are the most important transmitters of the disease. This disease can be detected by several serological tests, which usually have a high cost and require a long time. The goal of this work was to investigate a new method to diagnosis Toxoplasma gondii infections using NIRS. In order to confirm antibody detection, 24 cat blood serum samples were analyzed by the Raman spectra, from which 23 presented positive serology to toxoplasmosis and one was a reference negative serum. Characteristic Raman peaks allowed differentiation between negative and positive sera, confirming the possibility of antibody detection by Raman spectroscopy. These results give the first evidence that this technique can be useful to quantify antibodies in cat sera.     

Chloroplast DNA markers reveal a geographical divide across Argentinean southern beech Nothofagus nervosa (Phil.) Dim. et Mil. distribution area

  Nothofagus nervosa is one of the most important species of the temperate forests of southern South America. On the eastern slope of the Andes Mountains (Argentina) it has a very small and narrow natural distribution area which follows the valleys of the numerous west-east lake basins. Re-colonisation after the last glaciation is assumed to have originated from refugia located in the western pacific coast or even in free interglacial patches of the Andes Mountains. Sixteen pairs of primers were used to amplify 16 non-coding regions of chloroplast DNA in 11 populations from over the entire distribution area in Argentina. After restriction analysis two polymorphic fragments were found which defined two haplotypes and allowed a differentiation among populations. A clear geographic divide occurs separating populations distributed south and north of a west-east mountain chain. This suggests that after the last glaciation the species spread out from at least two different refugia. Hypotheses about the possible location of these refugia are discussed. Received: 28 October 1997 / Accepted: 19 March 1998     

A Misclassification Model for the Non‐Disjunction Fraction in Meiosis I

In this paper we introduce a misclassification model for the meiosis I non‐disjunction fraction in numerical chromosomal anomalies named trisomies. We obtain posteriors, and their moments, for the probability that a non‐disjunction occurs in the first division of meiosis and for the misclassification errors. We also extend previous works by providing the exact posterior, and its moments, for the probability that a non‐disjunction occurs in the first division of meiosis assuming the model proposed in the literature which does not consider that data are subject to misclassification. We perform Monte Carlo studies in order to compare Bayes estimates obtained by using both models. An application to Down Syndrome data is also presented. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)