Characterization of polymorphic microsatellite loci in the terrestrial isopod Armadillidium vulgare

The common pill bug, Armadillidium vulgare, is known to harbour two distinct strains of the feminizing proteobacteria Wolbachia. In order to study the effect of the presence of Wolbachia on the evolution of A. vulgare populations, we developed and characterized a set of nine polymorphic microsatellite loci from two microsatellite‐enriched genomic libraries. We screened 48 individuals from three French populations and found high genetic variation. Locus‐specific allelic diversity ranged from four to 28 and observed heterozygosity from 0.40 to 1.00, which indicates that these markers can be used to conduct population genetic studies in A. vulgare.     

On the monophyly of Dactylorhiza Necker ex Nevski (Orchidaceae): is Coeloglossum viride (L.) Hartman a Dactylorhiza?

Previous phylogenetic analyses of Orchidaceae subtribe Orchidinae resulted in the proposal to classify Coeloglossum viride (L.) Hartman within the genus Dactylorhiza in order to maintain its monophyly. In this paper, we report some results that contradict previous studies regarding the monophyly of the traditional Dactylorhiza and its phylogenetic relationship with Coeloglossum. Our results, which combine sequences of the internal and external transcribed spacers of the nuclear ribosomal DNA, support the monophyly of Dactylorhiza , with Coeloglossum being a sister clade. The position of C. viride in the phylogenetic tree, and the considerable morphological differences with respect to Dactylorhiza , incline us to retain both lineages as distinct genera.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 261–269.     

Type‐II histone deacetylases: elusive plant nuclear signal transducers

Since the beginning of the 21st century, numerous studies have concluded that the plant cell nucleus is one of the cellular compartments that define the specificity of the cellular response to an external stimulus or to a specific developmental stage. To that purpose, the nucleus contains all the enzymatic machinery required to carry out a wide variety of nuclear protein post‐translational modifications (PTMs), which play an important role in signal transduction pathways leading to the modulation of specific sets of genes. PTMs include protein (de)acetylation which is controlled by the antagonistic activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Regarding protein deacetylation, plants are of particular interest: in addition to the RPD3‐HDA1 and Sir2 HDAC families that they share with other eukaryotic organisms, plants have developed a specific family called type‐II HDACs (HD2s). Interestingly, these HD2s are well conserved in plants and control fundamental biological processes such as seed germination, flowering or the response to pathogens. The aim of this review was to summarize current knowledge regarding this fascinating, but still poorly understood nuclear protein family.     

Screening of ESTs from Septoria musiva (teleomorph Mycosphaerella populorum) for detection of SSR and PCR–RFLP markers

The development of an expressed sequence tag (EST) collection for the poplar pathogen Septoria musiva presented an opportunity for the development of locus‐specific polymorphic markers. Five microsatellites simple sequence repeat (SSR) and six polymerase chain reaction (PCR)–restriction fragment length polymorphism (RFLP) markers were identified and tested on three S. musiva populations collected in the north‐central and northeastern regions of North America. The results obtained support previously published random amplified polymorphic DNA (RAPD) data.     

Tetraploid Rangpur lime rootstock increases drought tolerance via enhanced constitutive root abscisic acid production

Whole‐genome duplication, or polyploidy, is common in many plant species and often leads to better adaptation to adverse environmental condition. However, little is known about the physiological and molecular determinants underlying adaptation. We examined the drought tolerance in diploid (2x) and autotetraploid (4x) clones of Rangpur lime (Citrus limonia) rootstocks grafted with 2x Valencia Delta sweet orange (Citrus sinensis) scions, named V/2xRL and V/4xRL, respectively. Physiological experiments to study root–shoot communication associated with gene expression studies in roots and leaves were performed. V/4xRL was much more tolerant to water deficit than V/2xRL. Gene expression analysis in leaves and roots showed that more genes related to the response to water stress were differentially expressed in V/2xRL than in V/4xRL. Prior to the stress, when comparing V/4xRL to V/2xRL, V/4xRL leaves had lower stomatal conductance and greater abscisic acid (ABA) content. In roots, ABA content was higher in V/4xRL and was associated to a greater expression of drought responsive genes, including CsNCED1, a pivotal regulatory gene of ABA biosynthesis. We conclude that tetraploidy modifies the expression of genes in Rangpur lime citrus roots to regulate long‐distance ABA signalling and adaptation to stress.     

Genetic structure of insular Mediterranean populations of the house mouse

The genetic structure of six western Mediterranean island populations of Mus musculus domesticus were investigated by means of an electrophoretic analysis at 34 loci and compared to that of five neighbouring mainland populations. No reduction in variability (H = 0.09 for both island and mainland samples) was observed in the island populations except for a very small island (6 ha), in which one-third of the variability was lost. Patterns of colonization inferred from a Wagner cluster analysis and the distribution of rare variants suggest that, although these island populations are clearly related to European mainland mice, their genetic structure is the result of multiple founding events from sources dispersed throughout the Mediterranean Basin. Furthermore, the presence of the same rare alleles in Sardinia, Corsica and Piana, suggest that the three islands share a common history of colonization.
Estimates of genetic distance and gene flow indicate that the level of genie differentiation is greater between island and mainland populations that between the latter due to geographic isolation. Multiple founder events and post-colonization evolution are the factors that best explain the observed levels of genie variability and differentiation in these Mediterranean islands.     

Efficacy of tags impregnated with pheromone and acaricide for control of Amblyomma variegatum

The efficacy of tags impregnated with pheromone and acaricide for control of Amblyomma variegatum on cattle in Guadeloupe was determined for a 13-week trial. Comparisons were made between untreated cattle and cattle with tags containing either pheromones alone (o-nitrophenol, methyl salicylate, 2,6-dichlorophenol and phenylacetaldehyde), pheromones plus acaricide (cyfluthrin or deltamethrin), or acaricide alone. Tags were fastened to cattle both on collars on the neck and with adhesive to tail hairs, with over 98 and 90% of tags retained, respectively, during the trial. By the end of the trial, tick infestations increased on untreated cattle (311.7%) and cattle with pheromone tags (154.8%) but decreased on cattle with pheromone/cyfluthrin (–45.0%), cyfluthrin (–42.8%), pheromone/deltamethrin (–68.7%) and deltamethrin tags (–87.6%). Cattle with pheromone tags had greater proportions of ticks on the hind regions (81%) compared to untreated cattle (62.5%) and on the front regions (18.2%) compared to untreated cattle (8.2%) indicating that ticks aggregated in response to pheromones. Analysis of hair samples by gas chromatography indicated that, within 2 days of placement, cyfluthrin spread rapidly over the body from the tags. Both cyfluthrin and deltamethrin were present in detectable levels on all eight body regions examined throughout the trial. Analysis of the tags indicated that they all still contained pheromone components after 13 weeks under field conditions.     

ADAPTATION TO SEVERE CONDITIONS OF PROPAGATION: LONG-DISTANCE DISTRESS CALLS; AND COURTSHIP CALLS OF A COLONIAL SEABIRD

ABSTRACT

The boatwhistle sound produced by male toadfish during the reproductive season attracts females to the nest site. Boatwhistles consist of a series of rapidly produced, amplitude modulated ‘pulses’ of sound that are generated by specific muscles of the gas bladder. Previous studies have shown that boatwhistle characteristics vary with temperature and geographic location. This study investigated the normal range of variation in boatwhistles produced by males in a northern population of O. tau. Multiple boatwhistles were recorded from individuals at different sites around Waquoit Bay, Massachusetts. Multiple boatwhistles were recorded at different sites to assess the range of variation in boatwhistle production from this population. Pulse repetition rates varied from a low of 125 pulses/sec at 16 °C to a high of 219 pulses/sec at 21 °C. Careful examination of recordings from different sites indicated that individuals vary in the durations of their boatwhistles as well as in the pulse repetition rates during the very consistently produced second segment of the call. In particular, pulse repetition rate (PRR) varied significantly (p < 0.001) among most individuals recorded at the same temperatures. Psychophysical testing as well as behavioral choice experiments are needed to assess the relative importance of PRR and spectral cues in species recognition and/or mate choice.     

Modeling the date of leaf appearance in low-arctic tundra

One of the reported changes of arctic ecosystems in response to warming climate is the advance of the leaf appearance in spring. Such phenological changes play a role in the structural changes within tundra ecosystem communities. Recently, we developed a model that estimates the leaf appearance date for deciduous trees in taiga. We apply this model to the whole low-arctic tundra, and we compare the simulated green-up dates with the green-up dates obtained from satellite observations and to in situ measurements of deciduous shrub leaf appearance. The model, although calibrated for taiga, performs remarkably well in tundra, with root mean square error ranging between 4 and 8 days for most of the tundra region, the same order as in taiga regions. The results seem to indicate that air temperature is the main factor controlling spring leaf phenology in tundra, just as in taiga, although these results do not permit us to reject soil temperature as the main trigger for leaf appearance in tundra. Because our model performs in tundra as well as in taiga, it can be used across the ecotone, and during a northward migration of the species from the taiga to the low-arctic region. The leaf appearance model and the satellite observations reveal that leaf appearance has tended to occur earlier by approximately 10 days both in Alaska since 1975, and in west Siberian tundra since 1965.