Genetic control and expression of the major ejaculatory bulb protein (PEB-me) inDrosophila melanogaster

PEB-me is a predominant protein of matureDrosophila melanogaster ejaculatory bulbs. It is resolved into four or five closely spaced subfractions (apparent molecular weight 35–39 kD) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four electrophoretic variants of PEB-me differing in apparent molecular weight by 200–800 daltons were found. These appear to be controlled by four alleles of a gene (peb) located by recombination and deletion mapping to the 60F1-2 region of chromosome 2. A minor ejaculatory bulb protein of ca. 80 kD (hPEB) was found to be immunochemically related to PEB and possibly encoded bypeb. PEB is not detected by immunoblotting techniques in virgin females, in male tissues other than the ejaculatory bulb, or during developmental stages preceding the formation of this organ. The results of transplantations of genital imaginal discs and of immature ejaculatory bulbs between two strains having different PEB alleles suggest that the ejaculatory bulb is the site of PEB synthesis. In flies mutant fortra, tra-2, dsx, orix, tissue specificity of PEB localization is retained and the protein is found whenever the ejaculatory bulb is formed, regardless of the chromosomal sex of the fly. The protein is transferred into the female genital duct during mating, where it can be detected for up to 12 hr. Possible functions of PEB inDrosophila reproduction are discussed.     

Dynamics of viscoelastic spherical membranes—the balloon model of the alveolus

Double-valued pressure-volume relationships in dynamic conditions for spherical membranes, modelling the lung alveoli, were obtained at small deformations. This hysteretic behavior was considered to be produced by at least three independent mechanisms: (1) the lung parenchyma exhibits viscoelastic properties; (2) the lung surface film, independent of the tissue, exhibits viscoelastic properties and (3) the pressure acting on the inner membrane surface depends on the rate of the alveolus volume change, due to the air viscous resistance in the bronchial tree. In each case, the maximum volume change, the hysteresis loop area, the tilt angle of the hysteresis loop and the relaxation time of the system were calculated. The results show pronounced hysteresis at normal breathing due to the air viscous resistance and smaller one due to the tissue and surface viscoelastic properties. In quasistatic conditions the values of the surface viscoelasticity and the tissue viscoelasticity effects are comparable or different, depending on the concrete external conditions. Comparison with the available experimental data is discussed in detail.     

Cryptic phenology in plants: Case studies,implications, and recommendations

Plant phenology—the timing of cyclic or recurrent biological events in plants—offers insight into the ecology, evolution, and seasonality of plant‐mediated ecosystem processes. Traditionally studied phenologies are readily apparent, such as flowering events, germination timing, and season‐initiating budbreak. However, a broad range of phenologies that are fundamental to the ecology and evolution of plants, and to global biogeochemical cycles and climate change predictions, have been neglected because they are “cryptic”—that is, hidden from view (e.g., root production) or difficult to distinguish and interpret based on common measurements at typical scales of examination (e.g., leaf turnover in evergreen forests). We illustrate how capturing cryptic phenology can advance scientific understanding with two case studies: wood phenology in a deciduous forest of the northeastern USA and leaf phenology in tropical evergreen forests of Amazonia. Drawing on these case studies and other literature, we argue that conceptualizing and characterizing cryptic plant phenology is needed for understanding and accurate prediction at many scales from organisms to ecosystems. We recommend avenues of empirical and modeling research to accelerate discovery of cryptic phenological patterns, to understand their causes and consequences, and to represent these processes in terrestrial biosphere models.     

Neuroimmunomodulative properties of dipeptidyl peptidase IV/CD26 in a TNBS-induced model of colitis in mice

Causal connections between dipeptidyl peptidase IV, also known as CD26 molecule (DPP IV/CD26) and inflammatory bowel disease (IBD) have been shown, but mechanisms of these interactions are unclear. Our hypothesis was that DPP IV/CD26 could affect the neuroimmune response during inflammatory events. Therefore, we aimed to evaluate its possible role and the relevance of the gut-brain axis in a model of IBD in mice. Trinitrobenzenesulfonic acid-induced (TNBS) colitis was induced in CD26-deficient (CD26(-/-) ) and wild-type (C57BL/6) mice. Pathohistological and histomorphometrical measurements were done. Concentrations and protein expressions of DPP IV/CD26 substrates neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP) were determined. Concentrations of IL-6 and IL-10 were evaluated. Investigations were conducted at systemic and local levels. Acute inflammation induced increased serum NPY concentrations in both mice strains, more enhanced in CD26(-/-) mice. Increased NPY concentrations were found in colon and brain of C57BL/6 mice, while in CD26(-/-) animals only in colon. VIP and IL-6 serum and tissue concentrations were increased in both mice strains in acute inflammation, more pronouncedly in CD26(-/-) mice. IL-10 concentrations, after a decrease in serum of both mice strains, increased promptly in CD26(-/-) mice. Decreased IL-10 concentration was found in brain of C57BL/6 mice, while it was increased in colon of CD26(-/-) mice in acute inflammation. DPP IV/CD26 deficiency affects the neuroimmune response at systemic and local levels during colitis development and resolution in mice. Inflammatory changes in the colon reflected on investigated parameters in the brain, suggesting an important role of the gut-brain axis in IBD pathogenesis.     

A dual function of the CRISPR-Cas system in bacterial antivirus immunity and DNA repair

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) and the associated proteins (Cas) comprise a system of adaptive immunity against viruses and plasmids in prokaryotes. Cas1 is a CRISPR-associated protein that is common to all CRISPR-containing prokaryotes but its function remains obscure. Here we show that the purified Cas1 protein of Escherichia coli (YgbT) exhibits nuclease activity against single-stranded and branched DNAs including Holliday junctions, replication forks and 5'-flaps. The crystal structure of YgbT and site-directed mutagenesis have revealed the potential active site. Genome-wide screens show that YgbT physically and genetically interacts with key components of DNA repair systems, including recB, recC and ruvB. Consistent with these findings, the ygbT deletion strain showed increased sensitivity to DNA damage and impaired chromosomal segregation. Similar phenotypes were observed in strains with deletion of CRISPR clusters, suggesting that the function of YgbT in repair involves interaction with the CRISPRs. These results show that YgbT belongs to a novel, structurally distinct family of nucleases acting on branched DNAs and suggest that, in addition to antiviral immunity, at least some components of the CRISPR-Cas system have a function in DNA repair.     

Specific and Selective Bacteriophages in the Fight against Multidrug-resistant Acinetobacter baumannii

Acinetobacter baumannii causes serious infections especially in immunocompromised and/or hospitalized patients. Several A. baumannii strains are multidrug resistant and infect wounds, bones, and the respiratory tract. Current studies are focused on finding new effective agents against A. baumannii. Phage therapy is a promising means to fight this bacterium and many studies on procuring and applying new phages against A. baumannii are currently being conducted. As shown in animal models, phages against multidrug-resistant A. baumannii may control bacterial infections caused by this pathogen and may be a real hope to solve this dangerous health problem.     

Continual assembly of desmosomes within stable intercellular contacts of epithelial A-431 cells

Subclones of human carcinoma-derived A-431 cell line stably producing fusion proteins consisting of the enhanced green fluorescent protein and either human desmoglein 2 (Dsg-GFP) or human plakoglobin (GFP-Pg) were used to examine the behavior of desmosomes in living cells. Immunofluorescence microscopy of the fixed cells showed that both fusion proteins, which were expressed in significantly lower levels relative to their endogenous counterparts, were efficiently recruited into desmosomes. Time-lapse confocal imaging of these cells reveals that such GFP-labeled desmosomes (GFP desmosomes) are stable structures which exhibit various dynamic and motile activities. The most notable are independent lateral mobility and fusion. Furthermore, the continual assembly of new nascent desmosomes is observed within stable contacts located at the middle of the epithelial sheet. A new GFP desmosome appears as a closely apposed group of fine patches which after a few minutes aggregate into a single structure. These three dynamic processes resulted in constant changes of desmosome distribution, numbers, and sizes. In addition, fluorescence recovery after photobleaching experiments showed that fine patches of desmosomal proteins may participate in desmosome maintenance. Such a diverse range of dynamic activities of desmosomes apparently produces flexible but tight cell-cell adhesion required for different morphogenetic events in epithelial structures.This work was supported by grant AR44016-04 from the National Institutes of Health