Time-dependent perezone production in different culture systems of <Emphasis Type=Italic>Acourtia cordata</Emphasis>

Perezone, a sesquiterpenic benzoquinone with diverse medicinal properties, accumulates in the roots of Acourtia species. In this time-dependent study, the production of perezone was followed in A. cordata culture systems of plants kept in vitro or acclimated and grown in pots. Perezone was characterized by several analytical methods, using the crystallized compound isolated from roots of wild plants as standard. A procedure was developed for its selective quantification, which considers the specific bathochromic shift of the absorbance band in the visible region between the spectra of perezone in its non-ionic and ionic forms, with intensity directly proportional to concentration. In vitro, perezone was recovered from A. cordata roots in average amounts of 5.21 mg g⁻¹ dry weight. Contrastingly, in plants under ex vitro conditions, perezone in roots increased logarithmically, rising from an average of 2.4 mg g⁻¹ dry weight at the 12^th week, to 43.6 mg g⁻¹ dry weight at the 31^st week, an amount comparable to wild plants. These findings show the feasibility of in vitro and ex vitro culture systems to propagate and conserve the germplasm of perezone-producing Acourtia plants, and a fast and reliable method for the quantification of this valuable compound.     

Habitat,density, and spatial distribution of <Emphasis Type=Italic>Rivulus giarettai</Emphasis> (<Emphasis Type=Italic>Actinopterygii</Emphasis>, <Emphasis Type=Italic>Cyprinodontiformes</Emphasis>) in southeastern Brazil

We present data on the habitat, density, and spatial distribution of Rivulus giarettai, and discuss some biotic and abiotic variables related to its abundance in Free Flowing Waters (FFW) and Dam Reservoirs (DR) in palm grove (Mauritia flexuosa) marshes (Veredas) in Uberlandia, Minas Gerais, southeastern Brazil. The mean density (individuals/plot) of R. giarettai was about 13 times higher in FFW than in DR. In FFW, the density of R. giarettai was highest at intermediate amounts of substrate (plant mass) and it was positively rank-correlated with the depth, and the number of arthropods. Individuals occurred in an aggregated distribution. The aggregated pattern could be related to a concentration of individuals in microhabitats neither too much exposed nor completely saturated by plants. R. giarettai was relatively abundant and tolerant to slight man-made habitat modifications. Damming appeared to be especially problematic by negatively affecting its density.