<Emphasis Type="Italic">Trixis forzzae</Emphasis> (Compositae: Mutisieae), a new species from Minas Gerais,Brazil

The new species Trixis forzzae Borges & Saavedra, from Serra do Ibitipoca, Minas Gerais, Brazil is described and illustrated. Taxonomic relationships with similar species and those of similar geographical distribution are discussed.     

Conversion of proteins to diazeniumdiolate-based nitric oxide donors.

Michael reaction of the methoxymethyl-protected monodiazeniumdiolate of piperazine (MOM-PIPERAZI/NO) with 4-maleimidobutyric acid followed by its conversion to the N-hydroxy-succinimido ester produces a reagent capable of transferring the nitric oxide (NO)-donating diazeniumdiolate group to the terminal amines of the lysine residues contained in proteins. The reagent has been used to produce diazeniumdiolated bovine serum albumin (D-BSA) and diazeniumdiolated human serum albumin (D-HSA) containing 22 and 19 modified lysyl groups, respectively. Upon dissolution in pH 7.4 phosphate buffer at 37 degrees C, these albumin derivatives gradually released all of their contained NO (approximately 40 mol/mol of protein) with initial rates of about 30-40 pmol/min/mg and half-lives on the order of 3 weeks. This methodology is now available for use in exploiting the unique specific metabolic interactions of proteins to target NO therapy to specific physiological processes in vivo.     

Effects of chorda tympani nerve anesthesia on taste responses in the NST

Human clinical and psychophysical observations suggest that the taste system is able to compensate for losses in peripheral nerve input, since patients do not commonly report decrements in whole mouth taste following chorda tympani nerve damage or anesthesia. Indeed, neurophysiological data from the rat nucleus of the solitary tract (NST) suggests that a release of inhibition (disinhibition) may occur centrally following chorda tympani nerve anesthesia. Our purpose was to study this possibility further. We recorded from 59 multi- and single- unit taste-responsive sites in the rat NST before, during and after recovery from chorda tympani nerve anesthesia. During anesthesia, average anterior tongue responses were eliminated but no compensatory increases in palatal or posterior tongue responses were observed. However, six individual sites displayed increased taste responsiveness during anesthesia. The average increase was 32.9%. Therefore, disinhibition of taste responses was observed, but infrequently and to a small degree in the NST At a subset of sites, chorda tympani-mediated responses decreased while greater superficial petrosal-mediated responses remained the same during anesthesia. Since this effect was accompanied by a decrease in spontaneous activity, we propose that taste compensation may result in part by a change in signal-to-noise ratio at a subset of sites.      

A descriptive and analytical study of four neotropical drosophilid communities

Drosophilid communities living in four different physiographical regions of the state of Rio Grande do Sul (27°/34°S; 49.7°/57.5°W), Brazil, were analysed. Ignoring cosmopolitan species, this is about the southern limit of the majority of typically neotropical Drosophila species distribution. Numerical fluctuations of the most frequent species populations from each place were investigated in relation to climatic data and trophic-resource availability. Of the four locations studied, Turvo is remarkable for being an enormous ecological reserve covered with subtropical perennially rainy forest, and for having stable weather conditions. Guaiba, on the other hand, is a more climatically unstable place, with unpredictable and more scarce resources. In Turvo, the community structure is shaped by the dominance of Drosophila willistoni and a low species diversity throughout the year. Low average niche-breadth and niche-overlap indices have also been found at feeding and breeding site levels. Guaíba showed the highest species-diversity levels and was better exploited by D. simulans, a cosmopolitan species with a well-known colonizing capacity. High niche breadth and overlap indices were characteristic for most species at this place. Results are discussed in the light of the communities' species composition and of environmental factors.