Dietary input of microbes and host genetic variation shape among-population differences in stickleback gut microbiota

To explain differences in gut microbial communities we must determine how processes regulating microbial community assembly (colonization, persistence) differ among hosts and affect microbiota composition. We surveyed the gut microbiota of threespine stickleback (Gasterosteus aculeatus) from 10 geographically clustered populations and sequenced environmental samples to track potential colonizing microbes and quantify the effects of host environment and genotype. Gut microbiota composition and diversity varied among populations. These among-population differences were associated with multiple covarying ecological variables: habitat type (lake, stream, estuary), lake geomorphology and food- (but not water-) associated microbiota. Fish genotype also covaried with gut microbiota composition; more genetically divergent populations exhibited more divergent gut microbiota. Our results suggest that population level differences in stickleback gut microbiota may depend more on internal sorting processes (host genotype) than on colonization processes (transient environmental effects).     

Living in isolation – population structure,reproduction, and genetic variation of the endangered plant species Dianthus gratianopolitanus (Cheddar pink)

The endangered plant species Dianthus gratianopolitanus exhibits a highly fragmented distribution range comprising many isolated populations. Based upon this pattern of distribution, we selected a study region in Switzerland with a lower magnitude of isolation (Swiss Jura) and another study region in Germany with a higher degree of isolation (Franconian Jura). In each region, we chose ten populations to analyze population structure, reproduction, and genetic variation in a comparative approach. Therefore, we determined population density, cushion size, and cushion density to analyze population structure, investigated reproductive traits, including number of flowers, capsules, and germination rate, and analyzed amplified fragment length polymorphisms to study genetic variation. Population and cushion density were credibly higher in German than in Swiss populations, whereas reproductive traits and genetic variation within populations were similar in both study regions. However, genetic variation among populations and isolation by distance were stronger in Germany than in Switzerland. Generally, cushion size and density as well as flower and capsule production increased with population size and density, whereas genetic variation decreased with population density. In contrast to our assumptions, we observed denser populations and cushions in the region with the higher magnitude of isolation, whereas reproductive traits and genetic variation within populations were comparable in both regions. This corroborates the assumption that stronger isolation must not necessarily result in the loss of fitness and genetic variation. Furthermore, it supports our conclusion that the protection of strongly isolated populations contributes essentially to the conservation of a species' full evolutionary potential.     

Caspase-mediated cleavage of the exosome subunit PM/Scl-75 during apoptosis

Recent studies have implicated the dying cell as a potential reservoir of modified autoantigens that might initiate and drive systemic autoimmunity in susceptible hosts. A number of subunits of the exosome, a complex of 3'→5' exoribonucleases that functions in a variety of cellular processes, are recognized by the so-called anti-PM/Scl autoantibodies, found predominantly in patients suffering from an overlap syndrome of myositis and scleroderma. Here we show that one of these subunits, PM/Scl-75, is cleaved during apoptosis. PM/Scl-75 cleavage is inhibited by several different caspase inhibitors. The analysis of PM/Scl-75 cleavage by recombinant caspase proteins shows that PM/Scl-75 is efficiently cleaved by caspase-1, to a smaller extent by caspase-8, and relatively inefficiently by caspase-3 and caspase-7. Cleavage of the PM/Scl-75 protein occurs in the C-terminal part of the protein at Asp369 (IILD³⁶⁹↓G), and at least a fraction of the resulting N-terminal fragments of PM/Scl-75 remains associated with the exosome. Finally, the implications of PM/Scl-75 cleavage for exosome function and the generation of anti-PM/Scl-75 autoantibodies are discussed.     

Genetic variation of two species with different life‐history traits in the endangered renosterveld of South Africa – a comparative analysis of Eriocephalus africanus and Hemimeris racemosa

We tested the effects of life‐history traits on genetic variation and conducted a comparative analysis of two plant species with differing life‐history traits co‐occurring in the highly endangered renosterveld of South Africa. We selected eighteen renosterveld remnants with varying degrees of size and isolation where populations of the herbaceous, annual and insect‐pollinated Hemimeris racemosa and the shrubby perennial and both wind‐ and insect‐pollinated Eriocephalus africanus occurred. We postulated a lower genetic variation within populations and increased genetic variation between populations in the annual than in the perennial species. Genetic variation was lower within populations of H. racemosa than within E. africanus, as is typical for annual compared to perennial species. Variation within populations was, however, not correlated with fragment size or distance in either of the two species and genetic variation between populations of the two species was comparable (Φ_ST = 0.10, 0.09).     

Detection of kappa and delta opioid receptors in skin--outside the nervous system

Opioid receptors (OR) are widely expressed in the central nervous system (CNS). Opioid antinociception might be initiated by activation of OR outside the CNS, indicating targeting of peripheral OR could be useful in the treatment of chronic pain. This study was designed to detect OR in skin tissues of healthy volunteers at both mRNA and protein levels. Skin samples from 10 healthy individuals were investigated. Total isolated RNAs were reverse transcribed, amplified and quantified by real-time PCR. Tissue and skin fibroblast OR protein was detected by immunohistochemistry, Western blot, and immunofluorescence. All skin tissue samples expressed delta- (DOR) and kappa-OR (KOR) mRNAs. Using immunohistochemistry, DOR and KOR were localized in skin fibroblast-like and mononuclear cells. Skin fibroblasts in culture expressed DOR and KOR mRNA. Using immunofluorescence, both DOR and KOR proteins were expressed predominantly on the cell membrane with minor staining in the cytoplasm. We suggest that enhanced expression of DOR and KOR in skin justifies the exploration of selective novel delta and kappa agonists for local pain treatment.     

Issues in using whole slide imaging for diagnostic pathology: “routine” stains,immunohistochemistry and predictive markers

The traditional microscope, together with the “routine” hematoxylin and eosin (H & E) stain, remains the “gold standard” for diagnosis of cancer and other diseases; remarkably, it and the majority of associated biological stains are more than 150 years old. Immunohistochemistry has added to the repertoire of “stains” available. Because of the need for specific identification and even measurement of “biomarkers,” immunohistochemistry has increased the demand for consistency of performance and interpretation of staining results. Rapid advances in the capabilities of digital imaging hardware and software now offer a realistic route to improved reproducibility, accuracy and quantification by utilizing whole slide digital images for diagnosis, education and research. There also are potential efficiencies in work flow and the promise of powerful new analytical methods; however, there also are challenges with respect to validation of the quality and fidelity of digital images, including the standard H & E stain, so that diagnostic performance by pathologists is not compromised when they rely on whole slide images instead of traditional stained tissues on glass slides.     

Wide distribution of the cysteine string proteins in Drosophila tissues revealed by targeted mutagenesis

The “cysteine string protein” (CSP) genes of higher eukaryotes code for a novel family of proteins characterized by a “J” domain and an unusual cysteine-rich region. Previous studies had localized the proteins in neuropil and synaptic terminals of larval and adult Drosophila and linked the temperature-sensitive paralysis of the mutants described here to conditional failure of synaptic transmission. We now use the null mutants as negative controls in order to reliably detect even low concentrations of CSPs by immunohistochemistry, employing three monoclonal antibodies. In wild-type flies high levels of cysteine string proteins are found not only in apparently all synaptic terminals of the embryonic, larval, and adult nervous systems, but also in the “tall cells” of the cardia, in the follicle cells of the ovary, in specific structures of the female spermatheca, and in the male testis and ejaculatory bulb. In addition, low levels of CSPs appear to be present in all tissues examined, including neuronal perikarya, axons, muscles, Malpighian tubules, and salivary glands. Western blots of isolated tissues demonstrate that of the four isoforms expressed in heads only the largest is found in non-neural organs. The wide expression of CSPs suggests that at least some of the various phenotypes of the null mutants observed at permissive temperatures, such as delayed development, short adult lifespan, modified electroretinogram, and optomotor behavior, may be caused by the lack of CSPs outside synaptic terminals.     

Genetic variation of Eryngium campestre L. (Apiaceae) in Central Europe

In Germany, Eryngium campestre is restricted to dry habitats along the rivers Rhine and Elbe and to a few areas in Central Germany. This distribution pattern is usually regarded as a typical pattern of postglacial immigration. In the present study, we investigated whether these two geographically distinct distribution areas are genetically differentiated and whether conclusions can be drawn regarding colonization history. To analyse the phylogeographic structure of E. campestre in Central Europe, 278 individuals from 29 populations within Germany and from further reference populations within Europe were analysed. We applied amplified fragment length polymorphisms to examine their genetic relatedness. Our analyses revealed three groups: a Mediterranean group additionally including two Rhine populations; a Rhine–Main group which further includes the westernmost population from the central German dry area; and one group which includes all eastern populations. Our results show that the two geographically distinct areas are genetically differentiated. As genetic diversity within the Elbe populations is very low, we conclude that this area, which was strongly affected through the late glacial maximum, was colonized relatively recently. High genetic diversity in the Rhine populations indicates a contact zone where lineages of different origin met. This would imply that today's patterns of genetic variation were caused through glacial range contractions and expansions. The present study is one of the first studies that deal with the postglacial distribution pattern of a dry grassland plant species in Central Europe and the results suggest that a survival of E. campestre at least during the Dryas cold stage might be possible.