Models of fibronectin.

The radius of gyration of human plasma fibronectin was determined by light scattering both under conditions in which the molecule is in an extended conformation (ionic strength 1.01 M, pH 8) and close to its native, more compact conformation (ionic strength 0.16 M, pH 8). These values were found to be 17.5 +/- 0.8 nm and 10.7 +/- 0.9 nm respectively, for a constant mol. wt of 533,000 +/- 8000, in excellent agreement with the value of 520,000 deduced from its known composition. A set of models, each made of two identical, end-to-end joined chains of 28 beads, was then constructed, and their calculated physico-chemical parameters were compared with those available for the whole fibronectin molecule and for some of its proteolytic fragments in both conformations. Two possible models for the circulating form are presented here: in both, the fibronectin molecule is in a compact, tangled conformation, with the amino-terminal end of one chain folded over to the carboxy end of itself or of the other chain either in a hairpin or in a circular fashion. With the exception of the carboxy-terminal fibrin(ogen)-binding domains, all the domains appear to be well exposed to the solvent, and thus free to interact with potential ligands.     

Ultrastructural immuno-localization of tropoelastin in the chick eye

Summary Immuno-gold labeling at the electron-microscopy level was used to investigate the distribution of tropoelastin in the chick eye. Intense staining was found in the amorphous part of mature elastic fibers in different regions of the organ. In elaunin fibers, both the amorphous core and the surrounding microfibrils were clearly labeled. In addition, reactive sites were detected in the oxitalan fibers of the stroma of the cornea and in Descemet's membrane, which showed a gradient of reactive sites increasing from the center toward the periphery. Oxitalan fibers of the stroma often fused with Descemet's membrane; the pattern of immunological staining suggested a continuity between the two structures. In the ciliary zonule, labeling for tropoelastin was observed in discrete areas on the bundles of microfibrils. The results show a complex structural organization of elastic tissue; this may be important in endowing the various parts of the eye with different mechanical properties.     

Colonization factors of diarrheagenicE. coli and their intestinal receptors

WhileEscherichia coli is common as a commensal organism in the distal ileum and colon, the presence of colonization factors (CF) on pathogenic strains ofE. coli facilitates attachment of the organism to intestinal receptor molecules in a species- and tissue-specific fashion. After the initial adherence, colonization occurs, and the involvement of additional virulence determinants leads to illness. EnterotoxigenicE. coli (ETEC) is the most extensively studied of the five categories ofE. coli that cause diarrheal disease, and has the greatest impact on health worldwide. ETEC can be isolated from domestic animals and humans. The biochemistry, genetics, epidemiology, antigenic characteristics, and cell and receptor binding properties of ETEC have been extensively described. Another major category, enteropathogenicE. coli (EPEC), has virulence mechanisms, primarily effacement and cytoskeletal rearrangement of intestinal brush borders, that are distinct from ETEC. An EPEC CF receptor has been purified and characterized as a sialidated transmembrane glycoprotein complex directly attached to actin, thereby associating CF-binding with host-cell response. Three, additional categories ofE. coli diarrheal disease, their colonization factors and their host cell receptors are discussed. It appears that biofilms exist in the intestine in a manner similar to oral bacterial biofilms, and thatE. coli is part of these biofilms as both commensals and pathogens.Abbreviations CF colonization factor - CFA Colonization Factor Antigen - CS coli-surface-associated antigen - EAggEC enteroaggregativeE. coli - ECDD E. coli diarrheal disease - EHEC enterohemorrhagicE. coli - EIEC enteroinvasiveE. coli - EPEC enteropathogenicE. coli - ETEC enterotoxigenicE. coli - Gal galactose - GalNAc N-acetyl galactosamine - LT heat-labile toxin - NeuAc N-acetyl neuraminic acid - PCF Putative colonization factor - RBC red blood cells - SLT Shiga-like toxin - ST heat-stable toxin     

Determination of acid α-naphthyl acetate esterase enzyme activity in peripheral blood leukocytes of gazelles (Gazella subgutturosa)

We examined gazelle peripheral blood leucocytes using the α-Naphthyl acetate esterase (ANAE) staining technique (pH 5.8). Our purpose was to determine the percentage of ANAE positive lymphocytes. The proportion of ANAE positive T-lymphocytes was 72%. T-lymphocytes showed an ANAE positive reaction, but eosinophilic granulocytes and monocytes also showed a positive reaction. By contrast, no reaction was detected in B-lymphocytes, neutrophil granulocytes or platelets. The reaction observed in T-lymphocytes was a red-brown coloration, usually 1–2 granules, but enough granules to fill the cytoplasm were detected rarely. As a result of ANAE enzyme staining, we concluded that the staining technique can be used as a cytochemical marker for gazelle T-lymphocytes.     

All the colors of the world: biotic homogenization-differentiation dynamics of freshwater fish communities on demand of the Brazilian aquarium trade

Hydrobiologia - Non-native freshwater fish introduced via the aquarium trade can cause major changes at the community level over time and space, resulting in dynamics context dependencies within...     

Development of a RNA extraction method from milk for gene expression study in the mammary gland of sheep

The aim of the study was to develop a reliable method for the RNA extraction from milk of Sarda sheep breed and to highlight if the extracted RNA can be used for expression study on mammary genes involved in milk fat synthesis using RT-qPCR. The main result is that a sample of 150 ml of milk provides an optimal amount of RNA (73.5 μg/ml). The highest RNA concentration has been found in the samples analysed within 4 h after collection. The RNA extracted was positively correlated to the number of somatic cells (P < 0.001). The efficiency of the extraction method was confirmed by the results obtained from qPCR which showed a Ct value, for SREBPF1 gene of 26.8 ± 0.15. This research demonstrated that the high-quality of the RNA obtained is suited to use for studies of mammary genes expression in sheep, avoiding any damage caused by mammary gland biopsy.     

Synthesis and Structural Studies of a Pentapeptide Sequence of Elastin. Poly (Val-Gly-Gly-Leu-Gly)

Abstract

Poly (Val-Gly-Gly-Leu-Gly), a polypeptide mimicking the physico-chemical properties of the glycine-rich regions of elastin, has been synthesized and studied both in solution and in the aggregated state. By comparison, also the conformation of different “monomeric” units has been investigated. The polymer showed increased disorder with respect to the “monomers”, the molecular conformation being accounted for by a more or less random collection of isolated β-turns. Nevertheless, in the solid state the polymer is able to adopt supramolecular structures reminiscent of those found for elastin.     

Melanoma central nervous system metastases: An update to approaches,challenges, and opportunities

In February 2018, the Melanoma Research Foundation and the Moffitt Cancer Center hosted the Second Summit on Melanoma Central Nervous System (CNS) Metastases in Tampa, Florida. In this white paper, we outline the current status of basic science, translational, and clinical research into melanoma brain metastasis development and therapeutic management. We further outline the important challenges that remain for the field and the critical barriers that need to be overcome for continued progress to be made in this clinically difficult area.     

The identification of Wos2, a p23 homologue that interacts with Wee1 and Cdc2 in the mitotic control of fission yeasts

The Wee1 kinase inhibits entry into mitosis by phosphorylation of the Cdc2 kinase. Searching for multicopy suppressors that abolish this inhibition in the fission yeast, we have identified a novel gene, here named wos2, encoding a protein with significant homology to human p23, an Hsp90-associated cochaperone. The deletion mutant has a modest phenotype, being heat-shock sensitive. Using antibodies raised against bacterially produced protein, we determined that Wos2 is very abundant, ubiquitously distributed in the yeast cell, and its expression dropped drastically as cells entered into early stationary phase, indicating that its function is associated with cell proliferation. In proliferating cells, the amount of Wos2 protein was not subjected to cell cycle regulation. However, in vitro assays demonstrated that this Hsp90 cochaperone is potentially regulated by phosphorylation. In addition to suppressing Wee1 activity, overproduction of Wos2 displayed synthetic lethality with Cdc2 mutant proteins, indicating that this Hsp90 cochaperone functionally interacts with Cdc2. The level of Cdc2 protein and its associated H1 kinase activity under synthetic lethal conditions suggested a regulatory role for this Wos2-Cdc2 interaction. Hsp90 complexes are required for CDK regulation; the synergy found between the excess of Wos2 and a deficiency in Hsp90 activity suggests that Wos2 could specifically interfere with the Hsp90-dependent regulation of Cdc2. In vitro analysis indicated that the above genetic interactions could take place by physical association of Wos2 with the single CDK complex of the fission yeast. Expression of the budding yeast p23 protein (encoded by the SBA1 gene) in the fission yeast indicated that Wos2 and Sba1 are functionally exchangeable and therefore that properties described here for Wos2 could be of wide significance in understanding the biological function of cochaperone p23 in eukaryotic cells.