First report of an aegagropilous form of Cladophora prolifera (Cladophorales, Chlorophyta) from the lagoon of Strunjan (Gulf of Trieste, northern Adriatic)

The occurrence of unattached spherical (aegagropilous) populations of the green alga Cladophora prolifera in the marine lagoon of Strunjan (Gulf of Trieste) is reported. Species identification was based on molecular and morphological data, and the distribution, ecology and morphological features of the aegagropilous populations are described. The ball-shaped form of this species differs from the typical upright attached form found on open shores by the radial arrangement of the branches and the absence of cells and rhizoids with clear annular constrictions. The formation of the aegagropilous form of C. prolifera likely results from specific hydrodynamic conditions in the human-mediated environment of the marine lagoon, in combination with morphological development of the species. The Strunjan marine lagoon appears to be the only location in the Mediterranean Sea, or even worldwide, where aegagropilous forms of C. prolifera occur in large abundance. Based on the high associated biodiversity, we propose the inclusion of these populations to be considered in conservation management plans in the area.

Interaction of Full-Length Glycosylphosphatidylinositol-Anchored Proteins with Serum Proteins and Their Translocation to Cells In Vitro Depend on the (Pre-)Diabetic State in Rats and Humans

Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs), which are anchored at the surface of mammalian cultured and tissue cells through a carboxy-terminal GPI glycolipid, are susceptible to release into incubation medium and (rat and human) blood, respectively, in response to metabolic stress and ageing. Those GPI-APs with the complete GPI still attached form micelle-like complexes together with (lyso)phospholipids and cholesterol and are prone to degradation by serum GPI-specific phospholipase D (GPLD1), as well as translocation to the surface of acceptor cells in vitro. In this study, the interaction of GPI-APs with GPLD1 or other serum proteins derived from metabolically deranged rat and humans and their translocation were measured by microfluidic chip- and surface acoustic wave-based sensing of micelle-like complexes reconstituted with model GPI-APs. The effect of GPI-AP translocation on the integrity of the acceptor cell surface was studied as lactate dehydrogenase release. For both rats and humans, the dependence of serum GPLD1 activity on the hyperglycemic/hyperinsulinemic state was found to be primarily based on upregulation of the interaction of GPLD1 with micelle-like GPI-AP complexes, rather than on its amount. In addition to GPLD1, other serum proteins were found to interact with the GPI phosphoinositolglycan of full-length GPI-APs. Upon incubation of rat adipocytes with full-length GPI-APs, their translocation from the micelle-like complexes (and also with lower efficacy from reconstituted high-density lipoproteins and liposomes) to acceptor cells was observed, accompanied by upregulation of their lysis. Both GPI-AP translocation and adipocyte lysis became reduced in the presence of serum proteins, including (inhibited) GPLD1. The reduction was higher with serum from hyperglycemic/hyperinsulinemic rats and diabetic humans compared to healthy ones. These findings suggest that the deleterious effects of full-length GPI-APs following spontaneous release into the circulation of metabolically deranged rats and humans are counterbalanced by upregulated interaction of their GPI anchor with GPLD1 and other serum proteins. Thereby, translocation of GPI-APs to blood and tissue cells and their lysis are prevented. The identification of GPI-APs and serum proteins interacting within micelle-like complexes may facilitate the prediction and stratification of diseases that are associated with impaired cell-surface anchorage of GPI-APs, such as obesity and diabetes.

Genetic data support reproductively isolated species in the endemic Cladophoraceae (Chlorophyta) of Lake Baikal, Russia

© 2020, © 2020 International Phycological Society. Ancient lakes are centres of biological diversification that hold many examples of adaptive radiation and species flocks. The recently discovered species flock of Cladophoraceae in Lake Baikal is a group of green algae that exhibit low genetic divergence in ribosomal markers (LSU, SSU, and ITS), but wide morphological differentiation. Microsatellite markers showed evidence of polyploidy in this group, requiring alternate data scoring methodologies. In this study, we use two clustering methods (STRUCTURE and Gaussian Clustering) to delineate species within 15 distinct morphotaxa of the cladophoralean Baikal clade. The two cluster analyses produced comparable results, although subtle differences in the assignment of individuals were observed. Our results indicate that many morphologically distinguishable species are discrete genetic clusters supporting reproductive isolation. This is the case for Chaetomorpha (= Ch.) baicalensis, the attached form of Ch. curta, Ch. moniliformis, Cladophora (= Cl.) compacta, and Cl. kursanovii. The unattached form of Ch. curta and a species of Rhizoclonium are recovered as growth forms of Ch. moniliformis and the attached form of Ch. curta, respectively. The remaining morphotaxa were not clearly delimited. While we have evidence for polyploidy within this species flock, it was not possible to determine the ploidy level of each individual with accuracy as no correlation in the number of alleles was observed between loci. A more detailed study including other sources of data, such as nuclear DNA content or chromosome counts, is required to demonstrate the ploidy changes and their role in speciation in these species.

Genetic data support reproductively isolated species in the endemic Cladophoraceae (Chlorophyta) of Lake Baikal, Russia

© 2020, © 2020 International Phycological Society. Ancient lakes are centres of biological diversification that hold many examples of adaptive radiation and species flocks. The recently discovered species flock of Cladophoraceae in Lake Baikal is a group of green algae that exhibit low genetic divergence in ribosomal markers (LSU, SSU, and ITS), but wide morphological differentiation. Microsatellite markers showed evidence of polyploidy in this group, requiring alternate data scoring methodologies. In this study, we use two clustering methods (STRUCTURE and Gaussian Clustering) to delineate species within 15 distinct morphotaxa of the cladophoralean Baikal clade. The two cluster analyses produced comparable results, although subtle differences in the assignment of individuals were observed. Our results indicate that many morphologically distinguishable species are discrete genetic clusters supporting reproductive isolation. This is the case for Chaetomorpha (= Ch.) baicalensis, the attached form of Ch. curta, Ch. moniliformis, Cladophora (= Cl.) compacta, and Cl. kursanovii. The unattached form of Ch. curta and a species of Rhizoclonium are recovered as growth forms of Ch. moniliformis and the attached form of Ch. curta, respectively. The remaining morphotaxa were not clearly delimited. While we have evidence for polyploidy within this species flock, it was not possible to determine the ploidy level of each individual with accuracy as no correlation in the number of alleles was observed between loci. A more detailed study including other sources of data, such as nuclear DNA content or chromosome counts, is required to demonstrate the ploidy changes and their role in speciation in these species.

Multifunctional Role of Choline Binding Protein G in Pneumococcal Pathogenesis

ABSTRACT Members of the choline binding protein (Cbp) family are noncovalently bound to phosphorylcholine residues on the surface of Streptococcus pneumoniae. It has been suggested that CbpG plays a role in adherence and increase virulence both at the mucosal surface and in the bloodstream, but the function of this protein has been unclear. A new sequence analysis indicated that CbpG is a possible member of the S1 family of multifunctional surface-associated serine proteases. Clinical isolates contained two alleles of cbpG, and one-third of the strains expressed a truncated protein lacking the C-terminal, cell wall-anchoring choline binding domain. CbpG on the surface of pneumococci (full length) or released into the supernatant (truncated) showed proteolytic activity for fibronectin and casein, as did CbpG expressed on lactobacilli or as a purified full-length or truncated recombinant protein. Recombinant CbpG (rCbpG)-coated beads adhered to eukaryotic cells, and TIGR4 mutants lacking CbpG or having a truncated CbpG protein showed decreased adherence in vitro and attenuation of disease in mouse challenge models of colonization, pneumonia, and bacteremia. Immunization with rCbpG was protective in an animal model of colonization and sepsis. We propose that CbpG is a multifunctional surface protein that in the cell-attached or secreted form cleaves host extracellular matrix and in the cell-attached form participates in bacterial adherence. This is the first example of distinct functions in virulence that are dependent on natural variation in expression of a choline binding domain.

Requirement for Ras Guanine Nucleotide Releasing Protein 3 in Coupling Phospholipase C-γ2 to Ras in B Cell Receptor Signaling

Two important Ras guanine nucleotide exchange factors, Son of sevenless (Sos) and Ras guanine nucleotide releasing protein (RasGRP), have been implicated in controlling Ras activation when cell surface receptors are stimulated. To address the specificity or redundancy of these exchange factors, we have generated Sos1/Sos2 double- or RasGRP3-deficient B cell lines and determined their ability to mediate Ras activation upon B cell receptor (BCR) stimulation. The BCR requires RasGRP3; in contrast, epidermal growth factor receptor is dependent on Sos1 and Sos2. Furthermore, we show that BCR-induced recruitment of RasGRP3 to the membrane and the subsequent Ras activation are significantly attenuated in phospholipase C-γ2–deficient B cells. This defective Ras activation is suppressed by the expression of RasGRP3 as a membrane-attached form, suggesting that phospholipase C-γ2 regulates RasGRP3 localization and thereby Ras activation.

Anaerobic treatment of domestic sewage at low temperature

The results of research concerning the feasibility of anaerobic treatment of domestic sewage at low temperature are summarized in this article. The batch tests demonstrated a high biodegradability of domestic sewage at 20°C (74%). Both batch and continuous experiments for the treatment of domestic sewage showed that the removal of SS prior to anaerobic treatment of domestic sewage not only provides a stable reactor performance but also improves the removal of both colloidal (CODcol) and dissolved COD (CODdis). The results of the pre-treatment of domestic sewage in an anaerobic filter (AF) and an anaerobic hybrid (AH) reactor showed that the AF reactor is an efficient process for the removal of suspended COD (CODss), viz. 82%, at an HRT of 4 h and 13°C. The novel AF reactor consists of vertical sheets of reticulated polyurethane foam with knobs, where the biomass was only in attached form. For the treatment of pre-settled sewage at 13°C, the AH reactor, with granular sludge, showed a higher total COD (CODt) removal than the UASB reactor as a result of higher CODcol removal. Therefore, the performance of a two-step system, AF+AH (with granular sludge) reactor, was investigated with different HRTs at 13°C. For optimization of CODss and CODdis an HRT of 4+4 h is needed, while for optimization of CODcol removal an HRT of 4+8 h is required. A CODt removal of 71% was achieved with 60% conversion to methane from the removed CODt when the AF+AH system was operated at an HRT of 4+8 h at 13°C.

Free and membrane-bound forms of bacterial cytochrome c4

Cytochrome c4 was isolated from cells of Pseudomonas aeruginosa, Pseudomonas stutzeri and Azotobacter vinelandii. The dihaem nature, Mr of approx. 20,000 and ferrohaem spectra in the region of the alpha- and beta-peaks define this family of cytochromes c. The behaviour of the holocytochromes in SDS was atypical, but removal of the haem groups resulted in a normal migration. In all three organisms most of the cytochrome c4 was tightly bound to the membrane, but some free cytochrome was detected. The membrane-attached cytochrome could be extracted with butanol, and this solubilized form was then indistinguishable in properties from the free form. Denitrifying rather than aerobic growth conditions hardly affected the total cytochrome c4 in the two pseudomonads, but there was slightly more free form and less membrane-attached form in denitrifying growth. The nature of the attachment of cytochrome c4 to the membrane is discussed and a model is proposed for the process of solubilization.