Local and regional scale habitat heterogeneity contribute to genetic adaptation in a commercially important marine mollusc (Haliotis rubra) from southeastern Australia

Characterising adaptive genetic divergence among conspecific populations is often achieved by studying genetic variation across defined environmental gradients. In marine systems this is challenging due to a paucity of information on habitat heterogeneity at local and regional scales and a dependency on sampling regimes that are typically limited to broad longitudinal and latitudinal environmental gradients. As a result, the spatial scales at which selection processes operate and the environmental factors that contribute to genetic adaptation in marine systems are likely to be unclear. In this study we explore patterns of adaptive genetic structuring in a commercially‐ harvested abalone species (Haliotis rubra) from southeastern Australia, using a panel of genome‐wide SNP markers (5,239 SNPs), and a sampling regime informed by marine LiDAR bathymetric imagery and 20‐year hindcasted oceanographic models. Despite a lack of overall genetic structure across the sampling distribution, significant genotype associations with heterogeneous habitat features were observed at local and regional spatial scales, including associations with wave energy, ocean current, sea surface temperature, and geology. These findings provide insights into the potential resilience of the species to changing marine climates and the role of migration and selection on recruitment processes, with implications for conservation and fisheries management. This study points to the spatial scales at which selection processes operate in marine systems and highlights the benefits of geospatially‐informed sampling regimes for overcoming limitations associated with marine population genomic research.     

A proteome catalog of Drosophila melanogaster: an essential resource for targeted quantitative proteomics

Proteomic analyses are critically important for systems biology because important aspects related to the structure, function and control of biological systems are only amenable by direct protein measurements. It has become apparent that the current proteomics technologies are unlikely to allow routine, quantitative measurements of whole proteomes. We have therefore suggested and largely implemented a two-step strategy for quantitative proteome analysis. In a first step, the discovery phase, the proteome observable by mass spectrometry is extensively analyzed. The resulting proteome catalog can then be used to select peptides specific to only one protein, so-called proteotypic peptides (PTPs). It represents the basis to realize sensitive, robust and reproducible measurements based on targeted mass spectrometry of these PTPs in a subsequent scoring phase. In this Extra View we describe the need for such proteome catalogs and their multiple benefits for catalyzing the shift towards targeted quantitative proteomic analysis and beyond. We use the Insulin signaling cascade as a representative example to illustrate the limitations of currently used proteomics approaches for the specific analysis of individual pathway components, and describe how the recently published Drosophila proteome catalog already helped to overcome many of these limitations.     

Clinical course of myelin oligodendrocyte glycoprotein 35-55 induced experimental autoimmune encephalomyelitis is aggravated by glia maturation factor

The role of glia maturation factor (GMF) in myelin oligodendrocyte glycoprotein (MOG) 35-55 peptide-induced experimental autoimmune encephalomyelitis (EAE) was investigated using GMF-deficient (GMF-KO) mice. We demonstrate that GMF-KO mice were resistant to the MOG 35-55 peptide-induced EAE as compared to wild type (Wt) mice (two in eight versus 10 in 10). Next, we examined the effect of administration of recombinant human GMF (rGMF) on MOG 35-55 peptide-induced EAE in mice. Daily administration of rGMF, staring days 1-14, resulted in significant exacerbation of clinical symptoms. Following rGMF injections, both GMF-KO (six in eight) and Wt mice (eight in eight) developed severe EAE (maximal clinical score of 3.5-4.0) with high frequency. The histological examination revealed severe infiltration of inflammatory cells in the spinal cord of MOG-immunized Wt mice while the resistance to EAE in GMF-KO mice was characterized by the absence of inflammatory cells. Administration of rGMF in Wt mice and GMF-KO mice resulted in a significant increase in infiltrating cells in the spinal cord following MOG-immunizations. We also evaluated cytokines and chemokines production as parameters of severity of inflammation in the spinal cord of Wt versus GMF-KO mice with and without GMF-reconstitution following MOG-immunizations. Cytokines (TNF-α, IFN-γ, IL-1β, IL-6) and chemokines (CCL2, CCL3, CXCL10, GM-CSF) production were significantly greater in Wt mice than in GMF-KO mice following MOG-immunization. Furthermore, the reconstitution experiment with rGMF showed that the administration of rGMF in both, Wt mice and GMF-KO mice produced significant increase in the GMF-mediated cytokine/chemokine production.     

Biaxial cell stimulation: A mechanical validation

To analyse mechanotransduction resulting from tensile loading under defined conditions, various devices for in vitro cell stimulation have been developed. This work aimed to determine the strain distribution on the membrane of a commercially available device and its consistency with rising cycle numbers, as well as the amount of strain transferred to adherent cells.The strains and their behaviour within the stimulation device were determined using digital image correlation (DIC). The strain transferred to cells was measured on eGFP-transfected bone marrow-derived cells imaged with a fluorescence microscope. The analysis was performed by determining the coordinates of prominent positions on the cells, calculating vectors between the coordinates and their length changes with increasing applied tensile strain.The stimulation device was found to apply homogeneous (mean of standard deviations approx. 2% of mean strain) and reproducible strains in the central well area. However, on average, only half of the applied strain was transferred to the bone marrow-derived cells. Furthermore, the strain measured within the device increased significantly with an increasing number of cycles while the membrane's Young's modulus decreased, indicating permanent changes in the material during extended use. Thus, strain magnitudes do not match the system readout and results require careful interpretation, especially at high cycle numbers.     

Genetic transfer of fusion proteins effectively inhibits VCAM-1-mediated cell adhesion and transmigration via inhibition of cytoskeletal anchorage

The adhesion of leukocytes to endothelium plays a central role in the development of atherosclerosis and thus represents an attractive therapeutic target for anti-atherosclerotic therapies. Vascular cell adhesion molecule-1 (VCAM-1) mediates both the initial tethering and the firm adhesion of leukocytes to endothelial cells. Our work evaluates the feasibility of using the cytoskeletal anchorage of VCAM-1 as a target for gene therapy. As a proof of concept, integrin α_IIbβ₃-mediated cell adhesion with clearly defined cytoskeletal anchorage was tested. We constructed fusion proteins containing the intracellular domain of β₃ placed at various distances to the cell membrane. Using cell adhesion assays and immunofluorescence, we established fusion constructs with competitive and dominant negative inhibition of cell adhesion. With the goal being the transfer of the dominant negative mechanism towards VCAM-1 inhibition, we constructed a fusion molecule containing the cytoplasmic domain of VCAM-1. Indeed, VCAM-1 mediated leukocyte adhesion can be inhibited via transfection of DNA encoding the designed VCAM-1 fusion protein. This is demonstrated in adhesion assays under static and flow conditions using CHO cells expressing recombinant VCAM-1 as well as activated endothelial cells. Thus, we are able to describe a novel approach for dominant negative inhibition of leukocyte adhesion to endothelial cells. This approach warrants further development as a novel gene therapeutic strategy that aims for a locally restricted effect at atherosclerotic areas of the vasculature.     

Ein neues knospendes Bakterium aus der Ostsee

Zusammenfassung Aus Wasser der Ostsee wurde ein Bakterium isoliert, das durch Knospung sowie durch Mehrfachteilung kokkenähnlicher Einheiten eine Vielfalt von Zellformen und-aggregaten ausbildet, wie sie bisher in keiner Bakteriengattung bekannt sind. Es handelt sich um einen heterotrophen beweglichen grampositiven Brackwasserorganismus. Die vorliegende Arbeit behandelt morphologische, cytologische und physiologische Merkmale sowie die mögliche taxonomische Stellung des Organismus.

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A new budding bacterium from the Baltic Sea

Summary From water of the Baltic Sea a bacterium has been isolated which reproduces by budding and by multiple fission of coccoid units, thus giving rise to a variety of cell forms and aggregates, which so far have not been known in any bacterial genus. It is a heterotrophic, motile, grampositive organism, which grows best in brackish water media. This paper deals with morphological, cytological, and physiological characters and with the possible taxonomic position of the organism.