Identification of an S-locus glycoprotein allele introgressed from B. napus ssp. rapifera to B. napus ssp. oleifera.

We have previously described a developmentally regulated mRNA in maize that accumulates in mature embryos and is involved in a variety of stress responses in the plant. The sequence of the encoded 16 kDa protein (MA16) predicts that it is an RNA-binding protein, since it possesses a ribonucleoprotein consensus sequence-type RNA-binding domain (CS-RBD). To assess the predicted RNA binding property of the protein and as a starting point to characterize its function we have used ribohomopolymer-binding assays. Here we show that the MA16-encoded protein binds preferentially to uridine- and guanosine-rich RNAs. In light of these results a likely role for this protein in RNA metabolism during late embryogenesis and in the stress response is discussed.     

World phylogeography and male‐mediated gene flow in the sandbar shark,Carcharhinus plumbeus

The sandbar shark, Carcharhinus plumbeus, is a large, cosmopolitan, coastal species. Females are thought to show philopatry to nursery grounds while males potentially migrate long distances, creating an opportunity for male‐mediated gene flow that may lead to discordance in patterns revealed by mitochondrial DNA (mtDNA) and nuclear markers. While this dynamic has been investigated in elasmobranchs over small spatial scales, it has not been examined at a global level. We examined patterns of historical phylogeography and contemporary gene flow by genotyping 329 individuals from nine locations throughout the species’ range at eight nuclear microsatellite markers and sequencing the complete mtDNA control region. Pairwise comparisons often resulted in fixation indices and divergence estimates of greater magnitude using mtDNA sequence data than microsatellite data. In addition, multiple methods of estimation suggested fewer populations based on microsatellite loci than on mtDNA sequence data. Coalescent analyses suggest divergence and restricted migration among Hawaii, Taiwan, eastern and western Australia using mtDNA sequence data and no divergence and high migration rates, between Taiwan and both Australian sites using microsatellite data. Evidence of secondary contact was detected between several localities and appears to be discreet in time rather than continuous. Collectively, these data suggest complex spatial/temporal relationships between shark populations that may feature pulses of female dispersal and more continuous male‐mediated gene flow.     

Global population structure of the spiny dogfish Squalus acanthias,a temperate shark with an antitropical distribution

The spiny dogfish (Squalus acanthias) is a temperate, coastal squaloid shark with an antitropical distribution in the Atlantic and Pacific oceans. The global population structure of this species is poorly understood, although individuals are known to undergo extensive migrations within coastal waters and across ocean basins. In this study, an analysis of the global population structure of the spiny dogfish was conducted using eight polymorphic nuclear microsatellite markers and a 566‐bp fragment of the mitochondrial ND2 gene region. A low level of genetic divergence was found among collections from the Atlantic and South Pacific basins, whereas a high level of genetic divergence was found among Pacific Ocean collections. Two genetically distinct groups were recovered by both marker classes: one exclusive to North Pacific collections, and one including collections from the South Pacific and Atlantic locations. The strong genetic break across the equatorial Pacific coincides with major regional differences in the life‐history characters of spiny dogfish, suggesting that spiny dogfish in areas on either side of the Pacific equator have been evolving independently for a considerable time. Phylogeographic analyses indicate that spiny dogfish populations had a Pacific origin, and that the North Atlantic was colonized as a result of a recent range expansion from the South American coast. Finally, the available data strongly argue for the taxonomic separation of the North Pacific spiny dogfish from S. acanthias and a re‐evaluation of the specific status of S. acanthias is warranted.     

Marked seasonal variation in the wild mouse gut microbiota

Recent studies have provided an unprecedented view of the microbial communities colonizing captive mice; yet the host and environmental factors that shape the rodent gut microbiota in their natural habitat remain largely unexplored. Here, we present results from a 2-year 16 S ribosomal RNA gene sequencing-based survey of wild wood mice (Apodemus sylvaticus) in two nearby woodlands. Similar to other mammals, wild mice were colonized by 10 bacterial phyla and dominated by the Firmicutes, Bacteroidetes and Proteobacteria. Within the Firmicutes, the Lactobacillus genus was most abundant. Putative bacterial pathogens were widespread and often abundant members of the wild mouse gut microbiota. Among a suite of extrinsic (environmental) and intrinsic (host-related) factors examined, seasonal changes dominated in driving qualitative and quantitative differences in the gut microbiota. In both years examined, we observed a strong seasonal shift in gut microbial community structure, potentially due to the transition from an insect- to a seed-based diet. This involved decreased levels of Lactobacillus, and increased levels of Alistipes (Bacteroidetes phylum) and Helicobacter. We also detected more subtle but statistically significant associations between the gut microbiota and biogeography, sex, reproductive status and co-colonization with enteric nematodes. These results suggest that environmental factors have a major role in shaping temporal variations in microbial community structure within natural populations.     

The rise to dominance of the angiosperm kingdom: dispersal,habitat widening and evolution during the Late Cretaceous of Europe

Coiffard, C. & Gomez, B. 2009: The rise to dominance of the angiosperm kingdom: dispersal, habitat widening and evolution during the Late Cretaceous of Europe. Lethaia, Vol. 43, pp. 164–169. The earliest fossil records of angiosperms in Europe occur in the Barremian and consist of freshwater wetland plants. From the Barremian onwards, angiosperms show a stepwise widening of their ecological range with the result that they inhabited most environments by the Cenomanian. Nevertheless, most angiosperms had still restricted habitats, while a few angiosperm trees were confined to disturbed environments, such as channel margins. A Wagner’s Parsimony Method analysis performed on a fossil plant and locality database from the Turonian to the Campanian of Europe indicates continued decrease in richness of ferns and gymnosperms compared with angiosperms, turnover between conifer and palm trees in freshwater‐related swamps at about the Cenomanian/Turonian boundary, and spreading of angiosperm trees through the floodplains. The ecological range of angiosperm trees was increased, being recorded in channel margins from the Cenomanian and spreading over floodplains (e.g. Platanaceae) and swamps (e.g. Arecaceae) by the Campanian. These new ecological ranges and successions went with innovative architectures, such as dicot trees and palm trees. Most living core angiosperm families had their earliest representatives in the Late Cretaceous, which should be considered as the dawn of modern angiosperm forests. □Core angiosperms, Europe, Late Cretaceous, palms, Wagner’s Parsimony Method.     

Developmental Role of Juvenile Hormone Metabolism in Lepidoptera

SYNOPSIS. Lepidopteran juvenile hormone (JH) esterase appearsto have a functional role in the regulation of embryogenesis,larval growth and development, and adult reproduction. In preovipositionaland newly laid eggs of the tobacco hornworm, Manduca sexta,JH esterase activity was elevated presumably to metabolize maternalJHs, and then declined after blastoderm formation. Also, a singlepeak in hemolymph JH esterase activity was found prior to ecdysisin the second through the fourth instar of M. sexta, the functionof which is unclear. However, in the last instar, elevated hemolymphJH esterase activity was noted prior to wandering and againprior to ecdysis to scavenge the last traces of JH necessaryfor normal development. The hemolymph JH esterase is likelyof multiple tissue origin for the prewandering peak with thefat body excluded as a source for the prepupal peak; an inhibitoryfactor from the brain and JH regulate JH esterase biosynthesis.In adult cabbage loopers, Trichoplusia ni, elevated hemolymphJH esterase activity appeared to be important in reducing theJH titer and preventing egg maturation. Structure/activity datawith trifluoromethylketones were incorporated into the designof a novel, JH esterase inhibitor, the sulfone and hydrate ofoctylthio-1,1,1- trifluoropropan-2-one, with selective and persistent,in vivo inhibitory activity. The topical application of thiscompound to last instar larvae and virgin adults of T. ni producedjuvenizing effects (delayed pupation and induced egg maturation/oviposition,respectively) providing direct evidence of a functional rolefor JH esterase in lepidopteran development.     

Comparison of marker types and map assumptions using Markov chain Monte Carlo-based linkage analysis of COGA data

We performed multipoint linkage analysis of the electrophysiological trait ECB21 on chromosome 4 in the full pedigrees provided by the Collaborative Study on the Genetics of Alcoholism (COGA). Three Markov chain Monte Carlo (MCMC)-based approaches were applied to the provided and re-estimated genetic maps and to five different marker panels consisting of microsatellite (STRP) and/or SNP markers at various densities. We found evidence of linkage near the GABRB1 STRP using all methods, maps, and marker panels. Difficulties encountered with SNP panels included convergence problems and demanding computations.