Tinea Nigra: Report of Twelve Cases in Venezuela

Tinea nigra is a superficial mycotic infection produced by Hortaea werneckii, formerly known as Phaeoannelomyces werneckii, formerly known as Exophiala werneckii, and Stenella araguata, the latter autochthonous in Venezuela, it was first described and named as Cladosporium castellanii in 1973. The present report describes 12 cases in the period of 1972–2002, diagnosed at the Medical Mycology Section at the Tropical Institute of the Universidad Central de Venezuela, in Caracas. This mycosis is more prevalent among young people, with fair skin, from 3 to 28 years of age, who visited beaches and in whom the lesions are more evident. Out of these 12 patients, 8 (66.66%) had Phaeoannelomyces werneckii as the causal agent and 2 (16.67%) Stenella araguata was isolated. Two patients had more than one macule, and curiously in these cases, each lesion was caused by a different species of the aforementioned fungus.     

Fishery by-product as a nutrient source for bacteria and archaea growth media

A highly soluble fish protein hydrolysates (FPH) with an 80% protein (peptide size between 1.5 and 20 kDa) and a low free amino acid content was obtained from hake (Merluccius hubssi) filleting waste [Lat. Am. Appl. Res. 30 (2000) 241]. Assays with Halobacterium salinarum, Escherichia coli, Bacillus subtilis and Staphylococcus epidermidis were performed in order to test that FPH as nutrient source for archaea and eubacteria culture media. Cell growth was evaluated by plate count, and by monitoring turbidity and nucleic acids content in liquid cultures. Neither cell growth nor generation times resulting from control and FPH cultures exhibited statistically significant differences at alpha: 0.05 suggesting that FPH can be used as an alternative substrate for microorganism cultural purposes.     

Mutator activity and specificity of Escherichia coli dnaQ49 allele--effect of umuDC products

The high fidelity of DNA replication in Escherichia coli is ensured by the alpha (DnaE) and epsilon (DnaQ) subunits of DNA polymerase providing insertion fidelity, 3'-->5' exonuclease proofreading activity, and by the dam-directed mismatch repair system. dnaQ49 is a recessive allele that confers a temperature-sensitive proofreading phenotype resulting in a high rate of spontaneous mutations and chronic induction of the SOS response. The aim of this study was to analyse the mutational specificity of dnaQ49 in umuDC and DeltaumuDC backgrounds at 28 and 37 degrees C in a system developed by J.H. Miller. We confirmed that the mutator activity of dnaQ49 was negligible at 28 degrees C and fully expressed at 37 degrees C. Of the six possible base pair substitutions, only GC-->AT transitions and GC-->TA and AT-->TA transversions were appreciably increased. However, the most numerous mutations were frameshifts, -1G deletions and +1A insertions. All mutations which increased in response to dnaQ49 damage were to a various extent umuDC-dependent, especially -1G deletions. This type of mutations decreased in CC108dnaQ49DeltaumuDC to 10% of the value found in CC108dnaQ49umuDC+ and increased in the presence of plasmids producing UmuD'C or UmuDC proteins. In the recovery of dnaQ49 mutator activity the plasmid harbouring umuD'C genes was more effective than the one harbouring umuDC. Analysis of mutational specificity of pol III with defective epsilon subunit indicates that continuation of DNA replication is allowed past G:T, C:T, T:T (or C:A, G:A, A:A) mismatches but does not allow for acceptance of T:C, C:C, A:C (or A:G, G:G, T:G) (the underlined base is in the template strand).     

Spatial patterns of caddisflies from Austral South America

Trichoptera are relevant members of the freshwater benthos that can exploit a broad variety of habitats. We explored their distribution patterns in Austral South America using a network quantitative approach applied on point occurrence data. The primary goal was to recognize groups of species connected by strong links of sympatry and secondarily to evaluate the structure of the sympatry network (patterns of connectivity) at higher taxonomic levels. We compiled 2,522 geographic points associated with 446 species. The strength of sympatry links were inferred directly from dot maps. Using the taxonomic resolution of species, we identified two major groups of co-occurring species that mimic in a geographic context the classic zoogeographic division of the study area: the Andean–Patagonian complex (of “cold-adapted” organisms) versus the Extra-Andean domain (of “warm-adapted” organisms) spanning the subtropical belt of the region. Within these major divisions, groups of highly co-distributed species were also found which in turn show a variety of overlapping spatial configurations. Overlap was centred at the following pivoting areas: Yungas of NW Argentina, Paranaense forest of NE Argentina and Valdivian temperate forest of Patagonia. Three very interesting findings emerged from the analyses: (i) Sierras Centrales of Córdoba correspond to the southern portion of many subtropical elements occurring in NW Argentina, (ii) some elements fit the disjunction between NW and NE Argentina and (iii) Uruguay is more closely related to NE Argentina than to Buenos Aires, suggesting that the Pampas region (Uruguay + Buenos Aires) could be an ill-defined biogeographic entity. Patterns at the species level become progressively blurred in going upward through the hierarchical classification.     

Lipoprotein receptor LRP1 regulates leptin signaling and energy homeostasis in the adult central nervous system

Obesity is a growing epidemic characterized by excess fat storage in adipocytes. Although lipoprotein receptors play important roles in lipid uptake, their role in controlling food intake and obesity is not known. Here we show that the lipoprotein receptor LRP1 regulates leptin signaling and energy homeostasis. Conditional deletion of the Lrp1 gene in the brain resulted in an obese phenotype characterized by increased food intake, decreased energy consumption, and decreased leptin signaling. LRP1 directly binds to leptin and the leptin receptor complex and is required for leptin receptor phosphorylation and Stat3 activation. We further showed that deletion of the Lrp1 gene specifically in the hypothalamus by Cre lentivirus injection is sufficient to trigger accelerated weight gain. Together, our results demonstrate that the lipoprotein receptor LRP1, which is critical in lipid metabolism, also regulates food intake and energy homeostasis in the adult central nervous system.