Bicaudal‐D binds clathrin heavy chain to promote its transport and augments synaptic vesicle recycling

Cargo transport by microtubule‐based motors is essential for cell organisation and function. The Bicaudal‐D (BicD) protein participates in the transport of a subset of cargoes by the minus‐end‐directed motor dynein, although the full extent of its functions is unclear. In this study, we report that in Drosophila zygotic BicD function is only obligatory in the nervous system. Clathrin heavy chain (Chc), a major constituent of coated pits and vesicles, is the most abundant protein co‐precipitated with BicD from head extracts. BicD binds Chc directly and interacts genetically with components of the pathway for clathrin‐mediated membrane trafficking. Directed transport and subcellular localisation of Chc is strongly perturbed in BicD mutant presynaptic boutons. Functional assays show that BicD and dynein are essential for the maintenance of normal levels of neurotransmission specifically during high‐frequency electrical stimulation and that this is associated with a reduced rate of recycling of internalised synaptic membrane. Our results implicate BicD as a new player in clathrin‐associated trafficking processes and show a novel requirement for microtubule‐based motor transport in the synaptic vesicle cycle.     

Localization of a recessive juvenile cataract mutation to proximal chromosome 7 in mice

OBJECTIVE: To localize the chromosomal position of a novel cataract mutation (juvenile recessive cataract; jrc) in mice. METHODS: A mapping population was developed by crossing cataract males (albino MH) to wild-type females (black C57BL/6J). F1 females were backcrossed to albino MH males with cataracts. RESULTS: The results were consistent with a model of a single autosomal recessive gene [153 cataract, 169 wild-type; chi2 = 0.8, 1 degree of freedom (d.f.), p > 0.35]. Linkage with the albino (tyrosinase; Tyr) locus was evident (chi2 = 61.5, 1 d.f., p < 0.0001), implicating chromosome 7 as the location of jrc. Recombination percentages (+/- SE) between jrc and D7Mit340 (1.2 cM location), D7Mit227 (16.0 cM) and D7Mit270 (18.0 cM) were 17.1 +/- 2.1, 3.7 +/- 1.1 and 6.2 +/- 1.3%, respectively. Multi-point mapping determined that the most likely order of these loci is D7Mit340 - jrc - D7Mit227 - D7Mit270 - Tyr. Although animals with the mutant phenotype appeared to have little or no sense of sight, their growth was not different (p >0.20) from that of normal mice. CONCLUSION: The jrc mutation model may be useful in the study of the genetics of cataracts in other animal species, including humans.     

Silver staining of nucleolar organizer regions (NOR) in some species of Hymenoptera (bees and parasitic wasp) and Coleoptera (lady-beetle)

Adaptations of the nucleolar organizer regions (NOR) banding technique using precipitation of silver salts significantly improved the NOR characterization of some species of hymenopterans and one coleopteran. The bee Melipona marginata (2n = 18) showed one metacentric pair of chromosomes with a NOR in the pericentromeric position. The parasitic wasp Mellitobia australica (2n = 12) also showed one metacentric pair with a strongly Ag-positive NOR. The male lady-beetle Cycloneda sanguinea (2n = 18 + Xy(p)) displayed a NOR on a pair of acrocentric autosomes. In the male Euglossa sp. (a haplodiploid species) (n = 21) the NOR were multiple, and occurred in five chromosomes. In the bee Plebeia sp. 1 (2n = 34) the NOR seemed restricted to one of the homologues of a metacentric pair. The systematic advances brought out by using this technique in the context of current theories of karyotypic evolution of these taxa are described and discussed.     

Cephalopod paralarvae and upwelling conditions off Galician waters (NW Spain)

A total of 103 cephalopod paralarvae were sampled during June 1995 in Galician waters (NW Spain). Samples were taken with Bongo nets of 300 and 500 m mesh size at 48 sampling stations along 10 transverse transects ranging from 80 to 600 m water depth. Paralarvae of loliginid squid were most abundant (40%). The Rhynchoteuthion paralarvae of ommastrephid squid accounted for 25%, whereas sepiolids comprised 23% of the total sample. Octopods were scarce, at only 6.6%. Other cephalopod families accounted for 5%. Sizes of paralarvae ranged from 1.0 to 7.1 mm mantle length. Temperature and salinity distribution showed the presence of an intense upwelling during the survey period. The sampling data obtained before and during the presence of upwelled water off Rias of Pontevedra and Vigo (southern zone) showed that paralarval cephalopod abundance and distribution were closely related to the upwelled Eastern North-Atlantic Central Water (ENACW).      

An analysis of determinants of amino acids substitution rates in bacterial proteins

The variation of amino acid substitution rates in proteins depends on several variables. Among these, the protein's expression level, functional category, essentiality, or metabolic costs of its amino acid residues may play an important role. However, the relative importance of each variable has not yet been evaluated in comparative analyses. To this aim, we made regression analyses combining data available on these variables and on evolutionary rates, in two well-documented model bacteria, Escherichia coli and Bacillus subtilis. In both bacteria, the level of expression of the protein in the cell was by far the most important driving force constraining the amino acids substitution rate. Subsequent inclusion in the analysis of the other variables added little further information. Furthermore, when the rates of synonymous substitutions were included in the analysis of the E. coli data, only the variable expression levels remained statistically significant. The rate of nonsynonymous substitution was shown to correlate with expression levels independently of the rate of synonymous substitution. These results suggest an important direct influence of expression levels, or at least codon usage bias for translation optimization, on the rates of nonsynonymous substitutions in bacteria. They also indicate that when a control for this variable is included, essentiality plays no significant role in the rate of protein evolution in bacteria, as is the case in eukaryotes.     

Ebselen Protects Ca2+ Influx Blockage But Does Not Protect Glutamate Uptake Inhibition Caused By Hg2+

The goal of this study was to investigate the isolated and combined effect of ebselen and Hg2+ on calcium influx and on glutamatergic system. We examined the in vitro effects of 2 phenyl-1,2-benzisoselenazol-3(2H)-ona), (Ebselen) on 45Ca2+ influx in synaptosomes of rat at rest and during depolarization and glutamate uptake into synaptosomes. Entry of 45Ca was measured during exposure to mercury in non-depolarizing and depolarizing solutions. Ebselen abolished the inhibition of 45Ca2+ influx on non-depolarizing conditions; however, ebselen did no modify inhibition uptake of 45Ca2+ caused by Hg2+ in high K+ depolarizing medium. Ebselen did not modify glutamate uptake inhibition caused by Hg2+ in synaptosomes. These results indicate that ebselen has an in vitro protective effect against Hg2+ induced inhibition of Ca2+ influx into synaptosomes, depending on the depolarizing conditions of the assay. The effects of Hg2+ on glutamate uptake were not modified by ebselen, suggesting that its protection is dependent on the target protein considered.     

Activity of oil-formulated Beauveria bassiana against Triatoma sordida in peridomestic areas in Central Brazil

Field tests were carried out during the rainy season of 2001/2002 in S?o Luís de Montes Belos, Goiás, Brazil, to evaluate the potential of the entomopathogenic fungus, Beauveria bassiana, against peridomestic Triatoma sordida. An oil-water formulation of the isolate CG 14 (Embrapa) was applied in triatomine infested hen houses of four farms at a final concentration of 10(6) conidia/cm2. Numbers of T. sordida decreased over the next 25 days, after application of the fungus, and B. bassiana developed on dead insects in one hen house. A high number of B. bassiana colonies was detected in substrates collected in treated hen houses 24 h after application of CG 14. In the following three months the presence of B. bassiana declined to values found before treatment.     

Effect of angiotensin II and losartan on the phagocytic activity of peritoneal macrophages from Balb/C mice

Angiotensin II (AII), a product of rennin-angiotensin system, exerts an important role on the function of immune system cells. In this study, the effect of AII on the phagocytic activity of mouse peritoneal macrophages was assessed. Mice peritoneal macrophages were cultured for 48 h and the influence of different concentrations of AII (10(-14) to 10(-7) M) and/or losartan, 10(-16) to 10(-6) M), an AT1 angiotensin receptor antagonist, on phagocytic activity and superoxide anion production was determined. Dimethylthiazoldiphenyltetrazolium bromide reduction and the nucleic acid content were used to assess the cvtotoxicity of losartan. A stimulatory effect on phagocytic activity (P < 0.05) was observed with 10(-13) M and 10(-12 M) AII concentrations. The addition of losartan (up to10(-14) M) to the cell cultures blocked (P < 0.001) the phagocytosis indicating the involvement of AT1 receptors. In contrast, superoxide anion production was not affected by AII or losartan. The existence of AT1 and AT2 receptors in peritoneal macrophages was demonstrated by immunofluorescence microscopy. These results support the hypothesis that AII receptors can modulate murine macrophage activity and phagocytosis, and suggest that AII may have a therapeutic role as an immunomodulatory agent in modifying the host resistance to infection.     

Brain natriuretic peptide and left ventricular dysfunction in chagasic cardiomyopathy

Global left ventricular (LV) systolic dysfunction is the strongest predictor of morbidity and mortality in Chagas disease. Echocardiography is considered the gold standard for the detection of LV dysfunction, but not always available in endemic areas where chagasic cardiomyopathy is most common. Brain natriuretic peptide (BNP) is a neurohormone that has been recently described as a simple and inexpensive diagnostic and prognostic marker for patients with congestive heart failure. Chagasic patients (n = 63) and non-infected healthy individuals (n = 18) were recruited prospectively and underwent complete clinical examination, echocardiography and 24-h Holter monitoring. BNP was measured from thawed plasma samples using the Triage BNP test. We observed high levels of BNP in association with depression of LV ejection fraction, with increase of LV end-diastolic diameter and with LV premature complexes. An elevated concentration of BNP, defined as a concentration of 60 pg/ml or more, had a sensitivity of 91.7%, specificity of 82.8%, positive predictive value of 52.4%, and negative predictive value of 98% for detecting LV dysfunction (LV ejection fraction < 40%).BNP measurement using a simple, relatively inexpensive and rapid test has a promising role in identifying LV dysfunction associated with chagasic cardiomyopathy. Equally important, patients with Trypanosoma cruzi infection who have low levels of BNP level in plasma have a very low likelihood of severe cardiac involvement, and echocardiography is probably not necessary.