A voyage to Terra Australis: human-mediated dispersal of cats.

BACKGROUND: Cats have been transported as human commensals worldwide giving rise to many feral populations. In Australia, feral cats have caused decline and extinction of native mammals, but their time of introduction and origin is unclear. Here, we investigate hypotheses of cat arrival pre- or post-European settlement, and the potential for admixture between cats of different invasion events. We analyse the genetic structure and diversity of feral cats from six locations on mainland Australia, seven Australian islands and samples from Southeast Asia and Europe using microsatellite and mitochondrial DNA data. RESULTS: Our results based on phylogeographic model selection are consistent with a European origin of cats in Australia. We find genetic distinctiveness of Australian mainland samples compared with Dirk Hartog Island, Flinders Island, Tasman Island and Cocos (Keeling) Island samples, and genetic similarities between some of the island populations. Historical records suggest that introduction of cats to these islands occurred at the time of European exploration and/or in connection with the pearling, whaling and sealing trades early in the 19th century. On-going influx of domestic cats into the feral cat population is apparently causing the Australian mainland populations to be genetically differentiated from those island populations, which likely are remnants of the historically introduced cat genotypes. CONCLUSION: A mainly European origin of feral cats in Australia, with possible secondary introductions from Asia following the initial establishment of cats in Australia is reasonable. The islands surrounding Australia may represent founding populations and are of particular interest. The results of the study provide an important timeframe for the impact of feral cats on native species in Australia.

The complete mitochondrial genome of Radix balthica (Pulmonata, Basommatophora), obtained by low coverage shot gun next generation sequencing.

A 454-FLX low-coverage sequencing approach was used to assemble the mitochondrial genome of Radix balthica. The mtDNA sequence is 13,993 nt long and contains 37 genes (13 protein coding genes, two rRNAs and 22 tRNAs). Four genes, the 12S RNA and seven tRNAs are transcribed in reverse order. The sequence is AT rich (71.3%), similar to other basommatophoran species. Comparison with the most closely related mt genomes available (Biomphalaria glabrata and Biomphalaria tenagophila) revealed identical gene orders except for five tRNAs. Next generation sequencing proved to be a fast and easy method for sequencing an entire mitochondrial genome.

Inferring the past to predict the future: climate modelling predictions and phylogeography for the freshwater gastropod Radix balthica (Pulmonata, Basommatophora).

Understanding the impact of past climatic events on species may facilitate predictions of how species will respond to future climate change. To this end, we sampled populations of the common pond snail Radix balthica over the entire species range (northwestern Europe). Using a recently developed analytical framework that employs ecological niche modelling to obtain hypotheses that are subsequently tested with statistical phylogeography, we inferred the range dynamics of R. balthica over time. A Maxent modelling for present-day conditions was performed to infer the climate envelope for the species, and the modelled niche was used to hindcast climatically suitable range at the last glacial maximum (LGM) c. 21,000 years ago. Ecological niche modelling predicted two suitable areas at the LGM within the present species range. Phylogeographic model selection on a COI mitochondrial DNA data set confirmed that R. balthica most likely spread from these two disjunct refuges after the LGM. The match observed between the potential range of the species at the LGM given its present climatic requirements and the phylogeographically inferred refugial areas was a clear argument in favour of niche conservatism in R. balthica, thus allowing to predict the future range. The subsequent projection of the potential range under a global change scenario predicts a moderate pole-ward shift of the northern range limits, but a dramatic loss of areas currently occupied in France, western Great Britain and southern Germany.

Highly polymorphic microsatellite markers for Radix balthica (Linnaeus 1758).

We present data for eight polymorphic microsatellite markers isolated from a microsatellite-enriched DNA library for the freshwater snail Radix balthica. Three of them were specific for R. balthica while five also amplified polymorphic products in two congeneric species. Test application on populations from all over the species range has shown that these loci are highly informative for analysing population structure and estimating migration rates. Observed deviations from Hardy-Weinberg equilibrium are attributed to a mixed mating system.

Postglacial recolonization at a snail's pace (Trochulus villosus): confronting competing refugia hypotheses using model selection.

The localization of Last Glacial Maximum (LGM) refugia is crucial information to understand a species' history and predict its reaction to future climate changes. However, many phylogeographical studies often lack sampling designs intensive enough to precisely localize these refugia. The hairy land snail Trochulus villosus has a small range centred on Switzerland, which could be intensively covered by sampling 455 individuals from 52 populations. Based on mitochondrial DNA sequences (COI and 16S), we identified two divergent lineages with distinct geographical distributions. Bayesian skyline plots suggested that both lineages expanded at the end of the LGM. To find where the origin populations were located, we applied the principles of ancestral character reconstruction and identified a candidate refugium for each mtDNA lineage: the French Jura and Central Switzerland, both ice-free during the LGM. Additional refugia, however, could not be excluded, as suggested by the microsatellite analysis of a population subset. Modelling the LGM niche of T. villosus, we showed that suitable climatic conditions were expected in the inferred refugia, but potentially also in the nunataks of the alpine ice shield. In a model selection approach, we compared several alternative recolonization scenarios by estimating the Akaike information criterion for their respective maximum-likelihood migration rates. The 'two refugia' scenario received by far the best support given the distribution of genetic diversity in T. villosus populations. Provided that fine-scale sampling designs and various analytical approaches are combined, it is possible to refine our necessary understanding of species responses to environmental changes.

Effects of climate-driven temperature changes on the diversity of freshwater macroinvertebrates.

Increasing temperatures due to climate change were found to influence abundance and timing of species in numerous ways. Whereas many studies have investigated climate-induced effects on the phenology and abundance of single species, less is known about climate-driven shifts in the diversity and composition of entire communities. Analyses of long-term data sets provide the potential to reveal such relationships. We analysed time series of entire communities of macrozoobenthos in lakes and streams in Northern Europe. There were no direct linear effects of temperature and climate indices (North Atlantic Oscillation index) on species composition and diversity, but using multivariate statistics we were able to show that trends in average temperature have already had profound impacts on species composition in lakes. These significant temperature signals on species composition were evident even though we analysed comparatively short time periods of 10-15 years. Future climate shifts may thus induce strong variance in community composition.

Separating historic events from recurrent processes in cryptic species: phylogeography of mud snails (Hydrobia spp.).

The present study combines methods that were designed to infer intraspecific relationships (e.g. nested-clade analysis (NCA), mismatch distributions and maximum likelihood gene flow analysis) to analyse historic events and recurrent processes in the cryptic mud snail species Hydrobia acuta and H. glyca. Specifically, we test the proposed allopatry of cryptic species and whether the peculiar range-subdivision of the putative subspecies H. a. acuta and H. a. neglecta is a result of long-distance dispersal or continuous range expansion. The NCA indicates a past fragmentation of the two H. acuta subspecies as well as past fragmentations within H. glyca. Gene-flow analyses show extensive gene flow in an E-W direction (towards the Atlantic) in the Mediterranean H. a. acuta, generally low gene flow in a W-E direction in the Atlantic H. a. neglecta and complex gene-flow pattern in a N-S but also in a S-N direction (against the Gulf Stream) in H. glyca. Based on these data and supportive ecological and oceanographical data, we hypothesize that the separation of the two H. acuta subspecies was not caused by long-distance dispersal but by a range shift and/or range expansion of the closely related competitor H. glyca as a result of an interglacial warming with a subsequent range shift in H. acuta. Moreover, our data do not show evidence for a long-term, stable sympatry of Hydrobia species, supporting the concept of allopatric relationships within cryptic radiations. NCA and gene-flow analyses indicate that the only sympatric population found in our study is the result of a recent dispersal event from the nearby Mediterranean. It is assumed that allopatric relationships in ephemeral Hydrobia populations constitute an evolutionary advantage relative to competition, recruitment and re-establishment of habitats. Mechanisms that could be of relevance for maintaining allopatry are discussed.

Phenotypic evolution and hidden speciation in Candidula unifasciata ssp. (Helicellinae, Gastropoda) inferred by 16S variation and quantitative shell traits.

In an effort to link quantitative morphometric information with molecular data on the population level, we have analysed 19 populations of the conchologically variable land snail Candidula unifasciata from across the species range for variation in quantitative shell traits and at the mitochondrial 16S ribosomal (r)DNA locus. In genetic analysis, including 21 additional populations, we observed two fundamental haplotype clades with an average pairwise sequence divergence of 0.209 +/- 0.009 between clades compared to 0.017 +/- 0.012 within clades, suggesting the presence of two different evolutionary lineages. Integrating additional shell material from the Senckenberg Malacological Collection, a highly significant discriminant analysis on the morphological shell traits with fundamental haplotype clades as grouping variable suggested that the less frequent haplotype corresponds to the described subspecies C. u. rugosiuscula, which we propose to regard as a distinct species. Both taxa were highly subdivided genetically (FST = 0.648 and 0.777 P < 0.001). This was contrasted by the partition of morphological variance, where only 29.6% and 21.9% of the variance were distributed among populations, respectively. In C. unifasciata, no significant association between population pairwise FST estimates and corresponding morphological fixation indices could be detected, indicating independent evolution of the two character sets. Partial least square analysis of environmental factors against shell trait variables in C. u. unifasciata revealed significant correlations between environmental factors and certain quantitative shell traits, whose potential adaptational values are discussed.

Dynamic microsatellites in transcribed regions of gastropod mitochondrial 16S rDNA.

Length variations of repetitive sequences in different AT-rich loop-coding regions of mitochondrial 16S rDNA in two gastropod species were discovered during intraspecific haplotype surveys. Examination of the discrete length variation of the basic repeat unit in a phylogenetic framework led to the conclusion of a microsatellite-like mutational dynamic. The observations suggest that the presence of a repetitive sequence structure alone is sufficient to trigger this dynamic.

Northern blot analysis of simple repetitive sequence transcription in plants.

The presence of simple repetitive sequence motifs in RNA from various plant species was probed by Northern blot analysis. Hybridization of total, poly(A)(+)- and poly(A)(-)-RNA with microsatellite-complementary oligonucleotide probes revealed distinct bands with most but not all probe/species combinations, demonstrating the presence of di-, tri- and tetranucleotide repeat motifs in plant transcripts. Only trinucleotide repeat-derived hybridization signals were found to be enriched in the poly(A)(+)-fraction. The quality of Northern blot signals proved to be highly dependent on hybridization stringency. Thus, under the stringency conditions usually applied for oligonucleotide hybridization, some probes [(GT)8, (CAC)5, (TCC)5, and (CCTA)4] cross-hybridized to bands corresponding in size to 18S and/or 26S rRNA. Cross-hybridization to rRNA was significantly reduced at higher stringencies. These results stress the importance of carefully adjusting the hybridization conditions in Northern blot analysis of simple sequence transcripts.

Developmentally regulated oligosaccharides in mouse spermatogenic cells.

Mouse spermatogenic cells were separated into four populations, pachytene spermatocytes, round spermatids, elongated spermatids, and residual bodies. Each cell population was metabolically labeled with [3H]galactose, [3H]glucosamine, or [3H]fucose. Glycopeptides were prepared from the radiolabeled glycoproteins by pronase digestion and fractionated by serial lectin affinity chromatography and gel filtration. The presence of O-linked oligosaccharides was assessed by pronase digestion of [3H]galactose-labeled glycoproteins, exclusion of the radiolabeled glycopeptides from a ConA-Sepharose column, gel filtration, and treatment with alkaline borohydride. This analysis reveals that a large proportion of [3H]galactose-labeled oligosaccharides (47-52%) are O-linked structures, while the majority (80-90%) of [3H]fucose-labeled oligosaccharides are N-linked. The proportions of triantennary, biantennary, oligomannose, and hybrid oligosaccharides linked to asparagine vary with the cell populations. Furthermore, in round spermatids, but not in the other cell populations, a relatively large proportion (15%) of [3H]glucosamine-labeled oligosaccharides consists of terminal O-linked N-acetylglucosamine. Taken together these data show that each spermatogenic cell population contains a unique complement of oligosaccharide structures that could play an important role as differentiation signals in the interactions among these cells and/or with Sertoli cells.

Diagnóstico de neumonía por legionella pneumophila mediante inmunofluorescencia directa del lavado broncoalveolar / Diagnosis of legionella pneumophila pneumonia through direct immunofluorescence in bronchoalveolar lavage fluid

Investigamos retrospectivamente la presencia de Legionella pneumonophila mediante la técnica de inmunofluorescencia directa (IFD) para detección de antígenos polivalentes (Organon Teknika) en 50 muestras almacenadas de lavado broncoalveolar (LBA). La IFD fue realizada ignorando los datos clínicos de los pacientes, 64 porciento de los cuales habían tenido una neumonía, de acuerdo a criterios clínicos, radiológicos y microbiológicos. La IFD fue positiva en dos muestras. El primero fue un varon de 44 años, con un cuadro clínico de neumonía adquirida en la comunidad, tratada por tres días con penicilina sódica sin resultados. El estudio corriente de LBA no fue diagnóstico. Se trató con roxitromicina, con buena respuesta clínica y radiográfica. El segundo corresponde a un varón de 45 años, con rechazo agudo de transplante renal que desarrolló una neumonía fulminante que lo llevó a la muerte, pese a un tratamiento antimicrobiano de amplio espectro, que incluía eritromicina. Concluímos que en nuestro medio existen neumonías graves por L. pneumophila que pueden ser detectadas mediante IFD de LBA, método que es altamente específico

A 43 kD c-mos protein is only expressed before meiosis during rat spermatogenesis.

We have investigated the RNA and protein expression pattern of the rat c-mos proto-oncogene during spermatogenesis. In mouse testis a 43kD c-mos protein is expressed throughout spermatogenesis, which is in agreement with one report detecting a 1.7 kb c-mos RNA in pachytene spermatocytes and in early spermatids. However, several other reports show that the mouse 1.7 kb c-mos RNA is exclusively expressed in post-meiotic male germ cells. We report that in rat male germ cells three c-mos RNA species of 5, 3.6 and 1.7 kb are detectable by Northern blotting analysis both before and after meiosis, with highest levels in early spermatids. However, western immuno-blot analysis reveals the presence of a 43 kD c-mos protein in total testis and pachytene spermatocytes, but not in post-meiotic cells. These findings combined with those made in the mouse system strongly suggest that c-mos protein may be a regulator of meiosis during spermatogenesis.

Developmentally regulated plasmalemmal glycoconjugates of the surface and neural ectoderm.

The plasmalemmal glycoconjugates of the ectoderm surrounding the rat embryo's caudal neuropore were mapped at the ultrastructural level, using various lectin probes. These included the agglutinins of wheat germ, soybean, Ricinus communis, Lotus tetragonolobus, and Canavalia ensiformis. Each lectin produced a characteristic binding pattern. Comparison of precursor cells of surface ectoderm, neural crest, and neural tube revealed that, even prior to neural tube formation, these three cell types can be distinguished by the sets of lectin receptors they express on their apical plasmalemma. The high density of lectin receptors found at the open neural groove level decreases dramatically during neurulation. Further changes in surface glycoconjugates must occur during neuronal differentiation because sprouting neurons exhibit yet another lectin binding pattern (K.H. Pfenninger, M.-F. Maylié-Pfenninger, L. B. Friedman, and P. Simkowitz, 1984, Dev. Biol. 106, 97-108). These results indicate that the commitment of ectodermal cells to diverging lineages (epidermis, neural crest, and tube) is reflected in their surface carbohydrates and occurs while they are still part of a continuous epithelial sheet. Furthermore, the plasmalemmal glycoconjugates of the ectoderm are developmentally regulated, and particularly dramatic changes in glycoconjugates expression are linked to neurulation.

Lectin labeling of sprouting neurons. III. Type-specific glycoconjugates on growth cones of different origin.

Ferritin conjugates of various lectins were used to determine the densities of surface carbohydrates on nerve growth cones produced by different classes of neuron. These neurons, from superior cervical and dorsal root ganglia, spinal cord, olfactory bulb, and cerebellum of the fetal rat, were grown as explant cultures, labeled with the probes, and then processed for quantitative electron microscopic analysis. It has been observed that each type of growth cone carries a characteristic set of lectin receptors on its surface, a "surface carbohydrate signature." Neurons derived from the neural tube generally exhibit lower levels of lectin binding sites on their growth cones compared with those derived from the neural crest. However, after neuraminidase treatment, lectin labeling is consistently dense for all growth cone types. These findings suggest (i) that neurons are programmed, possibly at the time of neurulation, to generate high- or low-sialic-acid patterns of surface carbohydrates on their growth cones according to their origin, and (ii) that the specific glycoconjugate pattern found for each type of neuron may be involved in selective cell-cell interactions during nervous system development.