Biological and genetic aspects of crosses between species of the genus Meccus (Hemiptera: Reduviidae Triatominae)

The degree of reproductive isolation between Meccus phyllosomus and the remaining five species of the genus Meccus, as well as between Meccus bassolsae and Meccus pallidipennis, Meccus longipennis and Meccus picturatus, was examined. Fertility and the segregation of morphological characteristics were examined in two generations of hybrids from crosses between these species. The percentage of couples with offspring (fertile) was high in the vast majority of sets of crosses, with the exception of that between ♀M. phyllosomus and ♂Meccus mazzottii. In sets of crosses involving M. bassolsae specimens, no first-generation (F1) individuals were morphologically similar to M. bassolsae, but instead shared the morphology of the other parental species. A similar phenomenon was observed in most sets of crosses involving M. phyllosomus. These results indicated that different degrees of reproductive isolation exist among the species of Meccus involved in this study. The biological evidence obtained in this study does not support the proposal that M. bassolsae is a full species. It could indicate that, on the contrary, it should be considered a subspecies of a single polytypic species. The biological evidence does support the proposal that M. phyllosomus is a full species.     

FTO and MC4R gene variants are associated with obesity in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the leading cause of anovulatory infertility in women. It is also associated with metabolic disturbances that place women at increased risk for obesity and type 2 diabetes. There is strong evidence for familial clustering of PCOS and a genetic predisposition. However, the gene(s) responsible for the PCOS phenotypes have not been elucidated. This two-phase family-based and case-control genetic study was designed to address the question of whether SNPs identified as susceptibility loci for obesity in genome-wide association studies (GWAS) are also associated with PCOS and elevated BMI. Members of 439 families having at least one offspring with PCOS were genotyped for 15 SNPs previously shown to be associated with obesity. Linkage and association with PCOS was assessed using the transmission/disequilibrium test (TDT). These SNPs were also analyzed in an independent case-control study involving 395 women with PCOS and 176 healthy women with regular menstrual cycles. Only one of these 15 SNPs (rs2815752 in NEGR1) was found to have a nominally significant association with PCOS (χ² = 6.11, P = 0.013), but this association failed to replicate in the case-control study. While not associated with PCOS itself, five SNPs in FTO and two in MC4R were associated with BMI as assessed with a quantitative-TDT analysis, several of which replicated association with BMI in the case-control cohort. These findings demonstrate that certain SNPs associated with obesity contribute to elevated BMI in PCOS, but do not appear to play a major role in PCOS per se. These findings support the notion that PCOS phenotypes are a consequence of an oligogenic/polygenic mechanism.     

Hidden prenatal malnutrition in the rat: role of β₁-adrenoceptors on synaptic plasticity in the frontal cortex

Moderate reduction in the protein content of the mother's diet (hidden malnutrition) does not alter body and brain weights of rat pups at birth, but leads to dysfunction of neocortical noradrenaline systems together with impaired long-term potentiation and visuo-spatial memory performance. As β?-adrenoceptors and downstream protein kinase signaling are critically involved in synaptic long-term potentiation and memory formation, we evaluated the β?-adrenoceptor density and the expression of cyclic-AMP dependent protein kinase, calcium/calmodulin-dependent protein kinase and protein kinase Fyn, in the frontal cortex of prenatally malnourished adult rats. In addition, we also studied if β?-adrenoceptor activation with the selective β? agonist dobutamine could improve deficits of prefrontal cortex long-term potentiation presenting these animals. Prenatally malnourished rats exhibited half of β?-adrenoceptor binding, together with a 51% and 65% reduction of cyclic AMP-dependent protein kinase α and calcium/calmodulin-dependent protein kinase α expression, respectively, as compared with eutrophic animals. Administration of the selective β? agonist dobutamine prior to tetanization completely rescued the ability of the prefrontal cortex to develop and maintain long-term potentiation in the malnourished rats. Results suggest that under-expression of neocortical β?-adrenoceptors and protein kinase signaling in hidden malnourished rats functionally affects the synaptic networks subserving prefrontal cortex long-term potentiation. β?-adrenoceptor activation was sufficient to fully recover neocortical plasticity in the PKA- and calcium/calmodulin-dependent protein kinase II-deficient undernourished rats, possibly by producing extra amounts of cAMP and/or by recruiting alternative signaling cascades.     

Outbreak of gastroenteritis caused by the pandemic Vibrio parahaemolyticus O3:K6 in Mexico

During 2003 and during late September of 2004, more than 1230 cases of gastroenteritis were reported in the south of Sinaloa State, north-western Mexico. All cases were attributed to the consumption of raw or undercooked shrimp collected at the Huizache-Caimanero lagunary system. Vibrio parahaemolyticus was identified by standard biochemical methods, and many strains were positive for PCR amplifications of the tlh and tdh genes and negative for the trh gene. A representative strain belonged to the O3:K6 serogroup. This is the first outbreak of gastroenteritis caused by the pandemic strains of O3:K6 V. parahaemolyticus in México.     

Direct measurements of the kinematics and dynamics of bat flight

Experimental measurements and analysis of the flight of bats are presented, including kinematic analysis of high-speed stereo videography of straight and turning flight, and measurements of the wake velocity field behind the bat. The kinematic data reveal that, at relatively slow flight speeds, wing motion is quite complex, including a sharp retraction of the wing during the upstroke and a broad sweep of the partially extended wing during the downstroke. The data also indicate that the flight speed and elevation are not constant, but oscillate in synchrony with both the horizontal and vertical movements of the wing. PIV measurements in the transverse (Trefftz) plane of the wake indicate a complex 'wake vortex' structure dominated by a strong wing tip vortex shed from the wing tip during the downstroke and either the wing tip or a more proximal joint during the upstroke. Data synthesis of several discrete realizations suggests a 'cartoon' of the wake structure during the entire wing beat cycle. Considerable work remains to be done to confirm and amplify these results.     

Structural Insights on Two Hypothetical Secretion Chaperones from <Emphasis Type="Italic">Xanthomonas axonopodis</Emphasis> pv<Emphasis Type="Italic">. citri</Emphasis>

Several Gram-negative bacterial pathogens have developed type III secretion systems (T3SSs) to deliver virulence proteins directly into eukaryotic cells in a process essential for many diseases. The type III secretion processes require customized chaperones with high specificity for binding partners, thus providing the secretion to occur. Due to the very low sequence similarities among secretion chaperones, annotation and discrimination of a great majority of them is extremely difficult and a task with low scores even if genes are encountered that codify for small (<20 kDa) proteins with low pI and a tendency to dimerise. Concerning about this, herein, we present structural features on two hypothetical T3SSs chaperones belonging to plant pathogen Xanthomonas axonopodis pv. citri and suggest how low resolution models based on Small Angle X-ray Scattering patterns can provide new structural insights that could be very helpful in their analysis and posterior classification.     

Epigenetic mechanism underlying the development of polycystic ovary syndrome (PCOS)-like phenotypes in prenatally androgenized rhesus monkeys

The pathogenesis of polycystic ovary syndrome (PCOS) is poorly understood. PCOS-like phenotypes are produced by prenatal androgenization (PA) of female rhesus monkeys. We hypothesize that perturbation of the epigenome, through altered DNA methylation, is one of the mechanisms whereby PA reprograms monkeys to develop PCOS. Infant and adult visceral adipose tissues (VAT) harvested from 15 PA and 10 control monkeys were studied. Bisulfite treated samples were subjected to genome-wide CpG methylation analysis, designed to simultaneously measure methylation levels at 27,578 CpG sites. Analysis was carried out using Bayesian Classification with Singular Value Decomposition (BCSVD), testing all probes simultaneously in a single test. Stringent criteria were then applied to filter out invalid probes due to sequence dissimilarities between human probes and monkey DNA, and then mapped to the rhesus genome. This yielded differentially methylated loci between PA and control monkeys, 163 in infant VAT, and 325 in adult VAT (BCSVD P<0.05). Among these two sets of genes, we identified several significant pathways, including the antiproliferative role of TOB in T cell signaling and transforming growth factor-β (TGF-β) signaling. Our results suggest PA may modify DNA methylation patterns in both infant and adult VAT. This pilot study suggests that excess fetal androgen exposure in female nonhuman primates may predispose to PCOS via alteration of the epigenome, providing a novel avenue to understand PCOS in humans.     

Effect of osmotic stress on protein turnover in Lemna minor fronds

Evidence is presented that although many proteins from the fronds of Lemna minor L. undergo enhanced degradation during osmotic stress, ribulose-1,5-bisphosphate carboxylase (RuBPCase) is not degraded. Instead RuBPCase is converted in a series of steps to a very high-molecular-weight form. The first step involves the induction of an oxidase system which after 24 h of stress converts RuBPCase to an acidic and catalytically inactive form. Subsequently, the oxidised RuBPCase protein is gradually polymerized to a number of very large aggregates (molecular weight of several million).The conversion of RuBPCase to a high-molecular-weight form appears to be correlated with (i) a reduction in the number of-SH residues and (ii) the susceptibility to in-vitro proteolysis. Indeed, the number of-SH groups per RuBPCase molecule decreases from 89 in the native enzyme to 54 and 22 in the oxidised and polymerized forms, respectively. On the other hand, the oxidised enzyme is more susceptible to in-vitro proteolysis than the native form. However, it is the polymerized form of RuBPCase which is particularly susceptible to in-vitro proteolysis.Western-blotting experiments and anti-ubiquitin antibodies were used to detect the presence of ubiquitin conjugates in extracts from osmotically stressed Lemna fronds. The possible involvement of ubiquitin in the formation of the aggregates is discussed.Abbreviations DTT dithiothreitol - EDTA ethylenediamine-tetraacetic acid - FPLC fast protein liquid chromatography - kDa kilodaltons - PAGE polyacrylamide gel electrophoresis - PMSF phenylmethylsulphonyl fluoride - RuBPCase ribulose bisphosphate carboxylase - SDS sodium dodecyl sulphate - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol     

Genome-wide CRISPR Screens in T Helper Cells Reveal Pervasive Crosstalk between Activation and Differentiation

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Protective effect of anacardic acids from cashew (Anacardium occidentale) on ethanol-induced gastric damage in mice

Cashew nut-shell liquid and the contained anacardic acids (AAs) have been shown to possess antioxidant, lipoxygenase inhibitory, anti-Helicobacter pylori and antitumor properties. Despite these known effects, hitherto there were no published reports on their likely gastroprotective effects. The present study was designed to verify whether AAs afford gastroprotection against the ethanol-induced gastric damage and to examine the underlying mechanism(s). Gastric damage was induced by intragastric administration of 0.2 mL of ethanol (96%). Mice in groups were pretreated orally with AAs (10, 30 and 100 mg/kg), misoprostol (50 μg/kg), or vehicle (2% Tween 80 in saline, 10 mL/kg), 45 min before ethanol administration. They were sacrificed 30 min later, the stomachs excised, and the mucosal lesion area (mm²) measured by planimetry. Gastroprotection was assessed in relation to inhibition of gastric lesion area. To study the gastroprotective mechanism(s), its relations to capsaicin-sensitive fibers, endogenous prostaglandins, nitric oxide and ATP-sensitive potassium channels were analysed. Treatments effects on ethanol-associated oxidative stress markers GSH, MDA, catalase, SOD, and total nitrate/nitrite levels as an index of NO were measured in gastric tissue. Besides, the effects of AAs on gastric secretory volume and total acidity were analysed in 4-h pylorus-ligated rat. AAs afforded a dose-related gastroprotection against the ethanol damage and further prevented the ethanol-induced changes in the levels of GSH, MDA, catalase, SOD and nitrate/nitrite. However, they failed to modify the gastric secretion or the total acidity. It was observed that the gastroprotection by AAs was greatly reduced in animals pretreated with capsazepine, indomethacin, l-NAME or glibenclamide. These results suggest that AAs afford gastroprotection principally through an antioxidant mechanism. Other complementary mechanisms include the activation of capsaicin-sensitive gastric afferents, stimulation of endogenous prostaglandins and nitric oxide, and opening of K⁺_ATP channels. These combined effects are likely to be accompanied by an increase in gastric microcirculation.