Parasitized mates increase infection risk for partners

Individuals can gain fitness benefits and costs through their mates. However, studies on sexual selection have tended to focus on genetic benefits. A potentially widespread cost of pairing with a parasitized mate is that doing so will increase an individual's parasite abundance. Such a cost has been overlooked in systems in which parasites are indirectly transmitted. We manipulated the abundance of the nematode parasite Trichostrongylus tenuis, an indirectly transmitted parasite, within pairs of wild red grouse Lagopus lagopus scoticus in spring. Parasite levels were correlated within pairs before the experiment. We removed parasites from males, females, or both members of the pair and evaluated individual parasite uptake over the subsequent breeding period. At the end of the breeding season, an individual's parasite abundance was greater when its mate had not been initially purged of parasites. This cost appeared to be greater for males. We discuss the implications of our results in relation to the costs that parasites may have on sexual selection processes.     

Resveratrol downregulates Akt/GSK and ERK signalling pathways in OVCAR-3 ovarian cancer cells

Phytochemicals constitute a heterogeneous group of substances with an evident role in human health. Their properties on cancer initiation, promotion and progression are well documented. Particular attention is now devoted to better understand the molecular basis of their anticancer action. In the present work, we studied the effect of resveratrol on the ovarian cancer cell line OVCAR-3 by a proteomic approach. Our findings demonstrate that resveratrol down-regulates the protein cyclin D1 and, in a concentration dependent manner, the phosphorylation levels of protein kinase B (Akt) and glycogen synthase kinase-3β (GSK-3β). The dephosphorylation of these kinases could be responsible for the decreased cyclin D1 levels observed after treatment. We also showed that resveratrol reduces phosphorylation levels of the extracellular signal-regulated kinase (ERK) 1/2. Chemical inhibitors of phosphatidylinositol 3-kinase (PI3K) and ERK both increased the in vitro therapeutic efficacy of resveratrol. Moreover, resveratrol had an inhibitory effect on the AKT phosphorylation in cultured cells derived from the ascites of ovarian cancer patients and in a panel of human cancer cell lines. Thus, resveratrol shows antitumor activity in human ovarian cancer cell lines targeting signalling pathway involved in cell proliferation and drug-resistance.     

OrthoClusterDB: an online platform for synteny blocks

Background  

The recent availability of an expanding collection of genome sequences driven by technological advances has facilitated comparative genomics and in particular the identification of synteny among multiple genomes. However, the development of effective and easy-to-use methods for identifying such conserved gene clusters among multiple genomes–synteny blocks–as well as databases, which host synteny blocks from various groups of species (especially eukaryotes) and also allow users to run synteny-identification programs, lags behind.     

Determination of the absolute configuration of the glucosinolate methyl sulfoxide group reveals a stereospecific biosynthesis of the side chain

Glucosinolates are plant metabolites containing an anionic nitrogeneous thioglucosidic core structure and a structurally diverse amino acid-derived side chain, which after hydrolysis by thioglucohydrolases (myrosinases) afford biological active degradation products such as nitriles and isothiocyanates. Structural diversity in glucosinolates is partially due to enzymatic modifications occurring on the preformed core structure, like the recently described oxidation of sulfides to sulfoxides catalyzed by a flavin monooxygenase identified in Arabidopsis thaliana. The enzyme product, 4-methylsulfinylbutylglucosinolate, bears a chiral sulfoxide group in its side chain. We have analyzed the epimeric purity of 4-methylsulfinylbutylglucosinolate by NMR methods using a chiral lanthanide shift reagent. The absolute configuration of the sulfoxide group has been established by comparing the ¹H NMR spectra of the two sulfoximine diastereomers of natural 4-methylsulfinylbutylglucosinolate. According to our data, 4-methylsulfinylbutylglucosinolate isolated from broccoli and A. thaliana is a pure epimer and its sulfoxide group has the R_S configuration. The product of the A. thaliana flavin monooxygenase has these same properties demonstrating that the enzyme is stereospecific and supporting its involvement in glucosinolate side chain formation.     

Combining geometric morphometrics and genetic analysis to identify species of Opisthonema Gill, 1861 in the eastern Mexican Pacific

Studies focusing on the specific identification of the taxonomic cast within the genus Opisthonema are scarce and contradictory, in spite of this species commercial importance and of the potential ecological impact that fisheries may have on the pelagic ecosystem. In this study, the specific composition of thread herrings Opisthonema (O. bulleri, O. medirastre, and O. libertate) in the southeastern region of the Gulf of California was identified using meristic characters, morphometric data, and mtDNA sequences. In this paper we supported the hypothesis that the commercial catch comprises three evolutionary entities with meristic and morphometric differences. The results were based on the number of ceratobranchial gill rakers, the presence of spicules on the gill rakers, the form of insertion of the gill rakers base onto the ceratobranchial segment, the geometric morphometrics of body shape, and the genetic distances from a fragment of Cytochrome Oxidase Subunit I gene (COI) of mtDNA. Specimens of Pacific thread herring were obtained from landings of the small pelagic fleet at Mazatlan, Sinaloa during 2011–2012. Taxonomic categories were assigned to 1060 individuals according to the measurement of meristic characters. A total of 228 thread herrings O. bulleri, (n = 76), O. medirastre (n = 76), and O. libertate (n = 76) were used in the morphometric analysis, and 25 specimens (O. bulleri n = 8, O. medirastre n = 7, and O. libertate n = 10) were used for genetic comparisons. The morphometric results showed differences among the three groups that had been previously identified using meristic characters, giving support to the existence of three discrete morphotypes. The percentage of sequence divergence of the COI gene supports the existence of three clades. Genetic distances were considerably lower within each clade than between clades. The results of this study provide sufficient evidence for the existence of three Pacific thread herring species in the southern Gulf of California.     

Magellanic woodpecker ( Campephilus magellanicus) abundance and foraging in Tierra del Fuego, Chile

The Magellanic woodpecker (Campephilus magellanicus) is a vulnerable and poorly studied bird in the sub-antarctic deciduous and evergreen beech (Nothofagus) forests of South America. On Tierra del Fuego island (Chile), we compared Magellanic woodpecker abundance and its foraging habitat in two forest types: pure N. pumilio and mixed forests composed by N. pumilio and N. betuloides, including managed and non managed stands. At a regional scale, abundance of woodpeckers was greater in landscapes including both forest types than in pure N. pumilio landscapes. When both forest types occurred together, woodpecker abundance did not differ between them. The number of trees with foraging signs was correlated with Magellanic woodpecker abundance and was also associated with N. betuloides and snag densities, but was not affected by forest management. Occurrence of pecking on foraging trees was greater in mixed Nothofagus than pure N. pumilio stands. Woodpeckers foraged disproportionately more on larger diameter and more decayed trees. Moreover, trees used for foraging were positively correlated with canopy cover and snag density and were negatively correlated with distance to nearby peatlands and beaver ponds. Direct observation revealed that the flying distance between trees was negatively correlated with proportion of trees with foraging signs. Woodpeckers chose trees that were visited before, suggesting a pattern of tree recognition within foraging territories.Communicated by F. Bairlein     

Structure, organization and characterization of the gene cluster involved in the production of microcin E492, a channel-forming bacteriocin

Microcin E492 is a low-molecular-weight, channel-forming bacteriocin produced and excreted by Klebsiella pneumoniae RYC492. A 13 kb chromosomal DNA fragment from K. pneumoniae RYC492 was sequenced, and it was demonstrated by random Tn5 mutagenesis that most of this segment, which has at least 10 cistrons, is needed for the production of active microcin and its immunity protein. Genes mceG and mceH correspond to an ABC exporter and its accessory protein, respectively, and they are closely related to the colicin V ABC export system. The microcin E492 system also requires the product of gene mceF as an additional factor for export. Despite the fact that this bacteriocin lacks post-translational modifications, genes mceC, mceI and mceJ are needed for the production of active microcin. Genes mceC and mceI are homologous to a glycosyl transferase and acyltransferase, respectively, whereas mceJ has no known homologue. Mutants in these three genes secrete an inactive form of microcin, able to form ion channels in a phospholipidic bilayer, indicating that the mutation of these microcin genes does not alter the process of membrane insertion. On the other hand, microcin isolated from mutants in genes mceC and mceJ has a lethal effect when incubated with spheroplasts of sensitive cells, indicating that the microcin defects in these mutants are likely to alter receptor recognition at the outer membrane. A model for synthesis and export is proposed as well as a novel maturation pathway that would involve conformational changes to explain the production of active microcin E492.     

Homologies of the adductor mandibulae muscles in Tetraodontiformes as indicated by nerve branching patterns

Homologies of the adductor mandibulae muscles in eight families of Tetraodontiformes were hypothesized from the branching patterns of ramus mandibularis trigeminus. Insertions of the muscles to the upper or lower jaw were weak indicators of homology, migrations of the sites occurring frequently in A1, A2, A2, and A3. In monacanthids, tetraodontids, and diodontids, A1 tended to be split into numerous subsections, whereas in aracanids and ostraciids, A3 was highly developed, comprising three or four subsections. In tetraodontids, A2 was found to be a composite of A1 subsection and A2. The methods of and limits to applying nerve branching patterns to muscle homology are discussed. A new naming system that reflects both muscle homologies and insertions is proposed.     

Measurements of intracellular ionized calcium in squid giant axons using calcium-selective electrodes

Ca²⁺-selective electrodes have been used to measure free intracellular Ca²⁺ concentrations in squid giant axons. Electrodes made of glass cannulas of about 20 μm in diameter, plugged with a poly(vinyl chloride) gelled sensor were used to impale the axons axially. They showed a Nernstian response to Ca²⁺ down to about 3 μM in solutions containing 0.3 M K⁺ and 0.025 M Na⁺. Sub-Nernstian but useful responses were obtained up to pCa 8. The electrodes showed adequate selectivity to Ca²⁺ over Mg²⁺, H⁺, K⁺ and Na⁺. To calibrate them properly, a set of standard solutions were prepared using different Ca²⁺ buffers (EGTA, HEEDTA, nitrilotriacetic acid) after carefully characterizing their apparent Ca²⁺ association constants under conditions resembling the axoplasmic environment. In fresh axons incubated in artificial seawater containing 4 mM Ca²⁺, the mean resting intracellular ionized calcium concentration was 0.106 μM ($\text{n = 15}$). The Ca²⁺-electrodes were used to investigate effects of different experimental procedures on the [Ca²⁺]_i. The main conclusions are: (i) intact axons can extrude calcium ions at low [Ca²⁺]_i levels by a process independent of external Na⁺; (ii) poisoned axons can extrude calcium ions at high levels of [Ca²⁺]_i by an external Na⁺-dependent process. The level of free intracellular Ca attained at these latter conditions is about an order to magnitude greater than the resting physiological value.     

Ontogeny of the circadian variation of plasma prolactin in sheep

The ontogeny of circadian rhythms is unknown. The newborn sheep has a circadian rhythm of temperature; to study the ontogeny of other rhythms, we examined the 24-h variation of plasma prolactin concentration in fetal and newborn sheep. To this effect, we measured plasma prolactin concentration in chronically catheterized fetuses (n = 7) and in newborn lambs raised under short day nycthemeral (12 light:12 dark, n = 13) or constant light conditions (n = 5). Indwelling catheters were implanted into the jugular vein and carotid artery of late gestation fetuses (0.9 gestation) and newborns (5-29 days old). Experiments were performed 4 or more days after surgery. Lambs were kept in a canvas sling and were fed cow's milk either by mouth or through a nasogastric catheter at established time intervals. Haematocrit, pH, and blood gases were measured before and after the experiments in all cases and remained within normal values. Lights were on and room temperature was maintained constant during the whole experiment. Samples were obtained every 1-2 h for 24 h in fetuses and newborn lambs under nycthemeral conditions and every hour for 48 h in newborn lambs kept under constant light. Plasma prolactin was measured by radioimmunoassay. The presence of a 24 h rhythm was determined by Cosinor analysis. Fetuses, aged 129 +/- 6 days (SD) n = 7, showed a variation in plasma prolactin concentration with a period of 24 h that fits the equation: plasma prolactin (ng ml-1) = 97.0 + 15.4 cos 15 (t-23.0), P = 0.035.(ABSTRACT TRUNCATED AT 250 WORDS)