Soluble 5''-Nucleotidase Activities in Rat Brain

5'-Nucleotidase activity was assayed in 105,000-g supernatants from rat brain by following conversion of [3H]AMP into adenosine. The effect of ATP on this process was complex and suggested the presence of at least two soluble 5'-nucleotidase activities: one inhibited by ATP and another activated by ATP. The relative proportions of these activities differed considerably among brain regions. Activity changes induced by hypothyroidism also suggested that these activities may be regulated independently. These findings may have consequences for the regional regulation of adenosine formation in the brain.     

Sexual dichromatism,size dimorphism,and microscale anatomy of white wing stripe in blue tits

Achromatic patches are a common element of plumage patterns in many bird species and there is growing body of evidence that in many avian taxa they can play a signaling role in mate choice. Although the blue tit Cyanistes caeruleus is a well-established model species in the studies on coloration, its white wing patch has never been examined in the context of sex-specific trait expression. In this exploratory study, we examined sexual size dimorphism and dichromatism of greater covert’s dots creating white wing patch and analyzed its correlations with current body condition and crown coloration—a trait with established role in sexual selection. Further, we qualitatively analyzed microstructural barb morphology underlying covert’s coloration. We found significant sexual dimorphism in the dot size independent of covert size and sexual dichromatism in both white dot and blue outer covert’s vane spectral characteristics. Internal structure of covert barbs within the white dot was similar to the one found in barbs from the blue part that is, with a medullary area consisting of dead keratinocytes containing channel-type ß-keratin spongy nanostructure and centrally located air cavities. However, it lacked melanosomes which was the main observed difference. Importantly, UV chroma of covert’s blue vane was positively correlated with crown UV chroma and current condition (the latter only in males), which should be a premise for further research on the signal function of the wing stripe.     

Influence of laser light on mycelial growth of Hebeloma mesophaeum and ectomycorrhizal development on Scots pine

 The effects of exposure to helium-neon (He-Ne) or Argon (Ar) laser light (λ=632.8 nm and 514 nm, respectively) on the growth of Hebeloma mesophaeum mycelium in pure culture were studied. Growth rates were highest after exposure to the He-Ne laser (1×60 s)+Ar laser (2×60 s) and to the He-Ne laser for 3×30. Container-grown Pinus sylvestris (pine) seedlings were inoculated with a water suspension of H. mesophaeum mycelium previously exposed to different kinds of laser light. After 3 months, the percentage of mycorrhizal associations on pine roots was 34.3% higher after He-Ne laser treatment and 47.1% higher after Ar laser treatment than in the controls with untreated fungus. However, seedlings infected with treated fungus were smaller than the control. Overall, laser light stimulated growth of H. mesophaeum mycelia in pure culture and enhanced mycorrhizal development on Scots pine seedlings.     

Degradation by proteases Lon, Clp and HtrA, of Escherichia coli proteins aggregated in vivo by heat shock; HtrA protease action in vivo and in vitro

Thermally aggregated, endogenous proteins of Escheri-chia coli form a distinct fraction, denoted S, which is separable by sucrose-density-gradient centrifugation. It was shown earlier that DnaK, DnaJ, IbpA and IbpB heat-shock proteins are associated with the S fraction. Comparison of the rise and decay of the S fraction in mutants defective for heat-shock proteases Lon (La), Clp, HtrA (DegP, Do) and in wild-type strains made studies of proteolysis and the function of the heat-shock response possible in vivo. Different timing and the extent of action of particular proteases was revealed by the initial size and decay kinetics of the S fraction. The proteases Lon, Clp, and HtrA all participated in removal of the aggregated proteins. Mutation in the gene encoding ClpB caused the most prominent effect (47% stabilization of the S fraction). The correlation between the disappearance of the S fraction and proteolytic activity was supported by the result of the in vitro reaction. Approximately one third of the isolated S fraction was converted to trichloroacetic acid-soluble products by the purified HtrA protease. Mg²⁺ ions stimulated the reaction, in contrast to the reaction of the HtrA protease with casein. The digestion of the aggregated proteins, unlike the digestion of casein, by HtrA protease in vitro was inhibited by added DnaJ, which might reflect protection of the aggregated proteins in vivo by DnaJ from excessive degradation. One might expect that such an activity of DnaJ would promote denatured protein renaturation versus proteolysis. Moreover, among the aggregated proteins that are discernible by electrophoresis, none could be identified as being more susceptible than any other to HtrA degradation. The separation pattern of these proteins before and after the in vitro digestion did not show a difference corresponding to the loss of about 30% of constituting proteins. This was interpreted as recognition by the HtrA protease of a state of protein denaturation rather than specific amino acid sequences in particular proteins. We conclude that the fraction consisting of proteins heat- aggregated in vivo (i.e. the S fraction) contains endogenous substrates for the heat-shock proteases tested. Their use for in vitro reaction reveals information that is in some respects different from that obtained with exogenous substrates such as casein.     

Concomitant Staining of Mast and Parietal Cells in Human Gastric Mucosa

A simple technique for concomitant staining of mast and parietal cells in the same section is described. Mast cells were stained by alcian blue or astra blue in methanol-formalinacetic acid fixed biopsies of gastric mucosa. Parietal cells were visualized by Dolichos biflorus lectin binding.     

Behavioral effects of long-term exposure to magnetic fields in rats

Male rats and pregnant and nonpregnant female rats of the Wistar strain were sham-exposed or exposed to static (0.49 T) or to extremely low frequency (50 Hz) magnetic fields (0.018 T) 2 h per day for 20 consecutive days. Measures of irritability, exploratory activity, and locomotion were made in that order before and after the 4th, 10th, and 17th 2-h exposures. A reliable decrease in the irritability of rats after repeated exposure to a static or undulating field was found. No significant effects of treatment conditions on open-field behavior and locomotor activity were observed. Pregnancy had no influence on the behavioral end points. These results indicate that irritability of rats may be used as a simple behavioral indicant of mammalian sensitivity to magnetic fields. © 1993 Wiley-Liss. Inc.     

Contact prediction in protein modeling: Scoring,folding and refinement of coarse-grained models

Background  

Several different methods for contact prediction succeeded within the Sixth Critical Assessment of Techniques for Protein Structure Prediction (CASP6). The most relevant were non-local contact predictions for targets from the most difficult categories: fold recognition-analogy and new fold. Such contacts could provide valuable structural information in case a template structure cannot be found in the PDB.     

Theoretical study of the kinetics and mechanism of the decomposition of trifluoromethanol, trichloromethanol, and tribromomethanol in the gas phase

Ab initio calculations at the G2 level were used in a theoretical analysis of the kinetics of unimolecular and water-accelerated decomposition of the halogenated alcohols CX₃OH (X = F, Cl, and Br) into CX₂O and HX. The calculations show that reactions of the unimolecular decomposition of CX₃OH are of no importance under atmospheric conditions. A considerably lower energy pathway for the decomposition of CX₃OH is accessible by homogenous reactions between CX₃OH and water. It is shown that CX₃OH + H₂O reactions proceed via the formation of intermediate complexes. The mechanism of the reactions appears to be complex and consists of three consecutive elementary processes. The calculated values of the second-order rate constants are of 2.5 × 10⁻²¹, 2.1 × 10⁻¹⁹, and 1.2 × 10⁻¹⁷ cm³molecule⁻¹s⁻¹ at 300 K for CF₃OH + H₂O, CCl₃OH + H₂O, and CBr₃OH + H₂O, respectively. The theoretically derived atmospheric lifetimes of the CX₃OH molecules indicate that the water-mediated decomposition reactions CX₃OH + H₂O may be the most efficient process of CF₃OH, CCl₃OH, and CBr₃OH loss in the atmosphere.     

A shared promoter region suggests a common ancestor for the human VCX/Y, SPANX, and CSAG gene families and the murine CYPT family

Many testis-specific genes from the sex chromosomes are subject to rapid evolution, which can make it difficult to identify murine genes in the human genome. The murine CYPT gene family includes 15 members, but orthologs were undetectable in the human genome. However, using refined homology search, sequences corresponding to the shared promoter region of the CYPT family were identified at 39 loci. Most loci were located immediately upstream of genes belonging to the VCX/Y, SPANX, or CSAG gene families. Sequence comparison of the loci revealed a conserved CYPT promoter-like (CPL) element featuring TATA and CCAAT boxes. The expression of members of the three families harboring the CPL resembled the murine expression of the CYPT family, with weak expression in late pachytene spermatocytes and predominant expression in spermatids, but some genes were also weakly expressed in somatic cells and in other germ cell types. The genomic regions harboring the gene families were rich in direct and inverted segmental duplications (SD), which may facilitate gene conversion and rapid evolution. The conserved CPL and the common expression profiles suggest that the human VCX/Y, SPANX, and CSAG2 gene families together with the murine SPANX gene and the CYPT family may share a common ancestor. Finally, we present evidence that VCX/Y and SPANX may be paralogs with a similar protein structure consisting of C terminal acidic repeats of variable lengths.     

The structure of the oligosaccharides of N-cadherin from human melanoma cell lines

N-cadherin is calcium-dependent cell adhesion molecule that mediates cell-cell adhesion and also modulates cell migration and tumor invasion. N-cadherin is a heavily glycosylated protein. Many studies have demonstrated that malignant transformation of a number of cell types correlates with changes of cell surface N-linked oligosacharides. We have studied the carbohydrate profile of N-cadherin synthesized in human melanoma cell lines and the effect of this protein and complex N-glycans on in vitro migration of melanoma cells from the primary tumor site—WM35 and from different metastatic sites WM239 (skin), WM9 (lymph node), and A375 (solid tumor). N-cadherin was immunoprecipitated with anti-human N-cadherin polyclonal antibodies. Characterization of its carbohydrate moieties was carried out by SDS-PAGE electrophoresis and blotting, followed by immunochemical identification of the N-cadherin polypeptides and on-blot deglycosylation using PNGase F for glycan release. N-glycans were separated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) and their structures identified by the computer matching of the resulting masses with those derived from a sequence database. The assay of in vitro chemotaxic cell migration was performed using QCM? Cell Invasion Assay (Chemicon). N-cadherin from WM35 (primary tumor site) possessed high-mannose and biantennary complex type glycans with α2–6 linked sialic acid. N-cadherin from WM239, WM9, and A375 cell lines possessed mostly tri- or tetra-antennary complex type glycans. In addition, N-cadherin from WM9 (lymph node metastatic site) and A375 (solid tumor metastatic site) contained heavily α-fucosylated complex type chains with α2,3 linked sialic acid. Blocking of N-cadherin-mediated intercellular interaction by N-cadherin-specific antibodies significantly (of about 40%) inhibited migration of melanoma cells. Inhibition of synthesis of complex type N-glycans by swainsonine (mannosidase II inhibitor) led to 50% decrease of cell migration. The results indicated differences between N-cadherin glycans from primary and metastatic sites and confirmed influence of N-cadherin and complex -type N-glycans on in vitro migration of melanoma cells. Published in 2004.