Angiotensin-converting enzyme inhibition by Brazilian plants

The potential antihypertensive activity of Brazilian plants was evaluated in vitro by its ability to inhibit the angiotensin-converting enzyme (ACE). Forty-four plants belonging to 30 families were investigated. Plants were selected based on their popular use as antihypertensive and/or diuretics. The following plants presented significant ACE inhibition rates: Calophyllum brasiliense, Combretum fruticosum, Leea rubra, Phoenix roebelinii and Terminalia catappa.     

Neutral sugars in melanins synthesized by actinomycetes from Brazilian soils

 Nine actinomycete melanins synthesized under various culture conditions, eight of them by actinomycete samples isolated from Brazilian topsoils under savanna (cerrado) vegetation and one from an ATCC sample, were subjected to a two-step hydrolysis procedure and the sugars released qualitatively and quantitatively determined by capillary gas-liquid chromatography (GLC). Humic acids (HAs) extracted from these soils, analysed previously, were used for comparison. The neutral sugars glucose, galactose, mannose, xylose, arabinose, ribose, rhamnose and fucose and the alcohol sugar inositol were present in varying amounts in most of the melanins analysed. The same sugars were present in the HAs used for comparison, except for ribose. Some qualitative and quantitative differences observed in the two types of macromolecules would be expected, considering their origins. The results indicate that the actinomycete melanins have a qualitative sugar distribution pattern similar to that of the HAs from Brazilian tropical soils and of HAs reported for soils from other climatic regions. The possible participation of actinomycete melanins in the formation of soil humic substances is discussed. Received: 4 April 1997     

Morphometric relationships and indirect determination of the length frequency structure of the pirarucu, Arapaima gigas (Cuvier), in Brazilian Amazonia

Abstract The pirarucu (giant red fish), Arapaima gigas (Cuvier), (Arapaimidae) is among the diverse fish resources of Amazonia which are threatened by over-exploitation. Little is known about the biology of this species despite its commercial importance. The present paper provides indirect information about the length-frequency structure of the stock which was estimated by sampling its tongue bone in craft shops and weighing fresh mantas (processed fish product) in fish markets since these were the only remaining recognizable features of the fish. The length-frequency reconstruction was carried out using a regression analysis calculated by utilizing individuals caught in experimental fishing.     

The fatty acid compositions of total,neutral and polar lipids in wild and farmed lambari (Astyanax altiparanae) (Garutti & Britski, 2000) broodstock

One way to develop broodstock fish diets is to determine the compositions of wild broodstock tissues and attempt to replicate these compositions in the eggs of farmed fish via dietary manipulation. We collected 30 wild and 30 farmed lambari females that were in the reproductive stage. The extraction and separation of polar and neutral fractions and the saponification and methylation of lipids were performed and analysed in the muscles, livers and ovaries to determine the compositions of the fatty acids via gas chromatography. Regardless of habitat, lambaris mobilize large amounts of fat to the ovaries during the reproductive period, in addition to highly unsaturated fatty acids, such as arachidonic, eicosapentaenoic and docosahexaenoic acids. The wild lambaris were observed to contain higher levels of various fatty acids, including linoleic acid, which is an essential fatty acid. The most abundant fatty acid that was observed in the commercial diet was linoleic acid, which was supplied in all fish farmed tissues. The commercial diet has low AA, EPA and DHA contents, and, higher levels of these fatty acids were recorded in the tissues of farmed lambari, which suggests that this species are able to elongate and desaturate precursors, linoleic and linolenic acids, into highly unsaturated fatty acids.     

Phosphorus Desorption from Fe and Al Oxides Mediated by Soil Microorganisms

The capacity of soil microorganisms to desorb phosphorus (P) adsorbed to iron (Fe) and aluminum (Al) oxides was determined by impregnating paper strips with these oxides, adding P in quantities equivalent to the null points, and incubating the strips in Argisol and Latosol samples receiving increasing doses of glucose (0 to 10 mg g soil^?1). Glucose stimulated microbial activity and at the end of the incubation period 69 and 41 percent of the added carbon (C) had been released as carbon dioxide (CO₂) in the Argisol and Latosol. This stimulated activity resulted in increasing P desorption, reaching 66 and 67 percent of the adsorbed P in the Fe strips and 49 and 80 percent in the Al strips for the Argisol and Latosol, respectively. Therefore, microorganisms can desorb P adsorbed to Fe and Al oxides when stimulated by an easily assimilated C source. Fe- and Al-oxide-impregnated paper strips technique provided an adequate method to measure soil P desorption, as mediated by microorganisms.     

Participatory Extension as Basis for the Work of Rural Extension Services in the Amazon

Public extension services play a key role in the implementation of strategies for rural development based on the sustainable management of natural resources. However, the sector suffers from restricted financial and human resources. Using experiences from participatory action research, a strategy for rural extension in the Amazon was defined to increase the efficiency and the relevance of external support for local resource users. This strategy considered activities initiated and coordinated by local people. Short-term facilitation visits provided continuous external support for the purpose of establishing locally based planning and learning mechanisms. In collaboration with the municipality of Muaná in the Eastern Amazon, the strategy was tested in two traditional communities – Monte Moriat and Boa Esperança. Both communities recognized as most important the need to reduce their dependence on açaí (Euterpe oleracea Mart.), the principal source of food and income. This forest resource has been overexploited, seriously affecting açaí stands and diminishing the forest benefits fundamental for survival. Two local groups decided to raise chickens as a way to reduce nutritional problems and as an alternative source of income. Supported by monthly, short-term planning and evaluation visits, the groups managed to achieve significant progress in their endeavor. The groups identified (1) the control of decision-making and information, and (2) the absence of external obligations to be the greatest advantages of the development initiative. The study confirmed the potential of participatory strategies for public extension in the Amazon. Special attention was given to realistically define the role of forests for local development. However, drastic measures are necessary to smooth the way for real participation in governmental and non-governmental organizations acting in the Brazilian Amazon.     

Post-logging regeneration and recruitment of shihuahuaco (Dipteryx spp.) in Peruvian Amazonia: Implications for management

Over the past decade, shihuahuaco timber - comprising several species of Dipteryx (Fabaceae) traded internationally as “cumarú” or “Brazilian teak” - has become one of the most highly demanded types of hardwood from Peruvian Amazonia, particularly in the Chinese market. Dipteryx is an ecologically important canopy-emergent genus with widespread distribution in neotropical forests. To assess the response of Dipteryx to logging, we conducted inventories in three logging areas in the Regions of Ucayali and Loreto, Peru. The size-class distributions of Dipteryx populations in recently logged sites showed that initial post-logging conditions enhance recruitment of residual seedlings. These conditions are created by a combination of logging gaps and the activities of farmers migrating into logged lands. Through protection and liberation of shihuahuaco seedlings in post-logged forest as well as within and around agricultural fields, local residents and timber companies could favor the recovery of this valued resource. However, as logged land is increasingly converted to agriculture and pastureland, the reestablishment of mature seed trees is not assured.     

Leptospira strains isolated from cattle in the Amazon region,Brazil, evidence of a variety of species and serogroups with a high frequency of the Sejroe serogroup

In Brazil, there have been few leptospires isolated from cattle, especially in the Amazon, implying that the epidemiology of the disease in this region is still largely unclear. In a previous study, 52 Leptospira isolates were obtained from urine of cattle raised in the Brazilian Amazon and, to achieve a greater understanding of Leptospira infection in cattle of this region, the present study aimed to serologically and molecularly characterizes all these isolates. The laboratory assays used were the microscopic agglutination test (MAT) adopting a panel of polyclonal antisera against Leptospira spp. for serogrouping the isolates, DNA sequencing (secY) and multiple locus variable number tandem repeat analysis (MLVA). The isolates belonged to five species: 20/52 were identified as L. borgpetersenii (38.5 %); 18/52 as L. kirschneri (34.6 %); 9/52 as L. santarosai (17.3 %); 3/52 as L. noguchii (5.8 %) and 2/52 as L. interrogans (3.8 %). With serogrouping, nine different serogroups were detected, with a high frequency of the Sejroe serogroup. MLVA showed that all L. borgpetersenii isolates had a profile compatible with serovar Hardjo; moreover, the other isolates demonstrated a diversity of patterns, and some of them may represent strains not yet characterized. In the Brazilian Amazon, the leptospires circulating in cattle revealed the unique aspects of infections in this area which, in addition to a variety of strains, were characterized by a high frequency of the Sejroe serogroup, highlighting the serovar Hardjo, which has not been reported in other regions of Brazil.     

Regional Comparative Advantage,Location of Agriculture,and Deforestation in Brazil

ABSTRACT

This article highlights how deforestation is not only linked to economic processes within the Amazon, but also to economic forces in the rest of Brazil. In light of recent trends in Brazil's agricultural production inside and outside the Amazon, this article maintains that the growing importance of beef production in the Amazon relative to the rest of Brazil is likely to lead to further increases in deforestation. From 1991 to 2001 the Amazon's share of the Brazilian bovine herd increased from 15% to 25%—an average change of 1% per year. With the Brazilian herd size in 2003 estimated at 196 million head of cattle, the current rate of increase implies an increase of 1.96 million cattle per year in the Amazon. At Brazil's average stocking rate of 1.1 head of cattle per hectare, it means that an additional 18,000 km² of land are needed each year in the Amazon to account for this expansion. However, Brazil has abundant agricultural land outside the Amazon to meet increases in demand for beef. The difficulty lies in the comparative advantage of these other areas in producing soy and grains as opposed to livestock. I conclude that targeting resources toward specific agricultural development opportunities outside the Amazon—especially grain-fed beef— would be an effective way to reduce incentives to clear land in the Amazon.     

Predation effects on matrotrophy,superfetation and other life history traits in Phalloceros harpagos

This study investigates the effect of a predation gradient on the female life history traits of the poeciliid live‐bearing fish Phalloceros harpagos from a tropical stream in Brazil. Females’ length at maturity, somatic dry mass, reproductive allotment and fecundity varied significantly among predation sites. Phalloceros harpagos from the high‐predation site showed smaller size at maturity and somatic dry mass, greater reproductive allotment and higher fecundity than the nonpredation site. In all sites, we observed superfetation: pregnant females with two broods at different developmental stages. The presence of superfetation was not observed before in other congeneric species, and it may represent an additional independent evolutionary origin of superfetation in the fish family Poeciliidae. Matrotrophy, the postfertilisation maternal provisioning of nutrients to developing embryos throughout gestation, was observed in all three sites, with values of the matrotrophy index above two. The population under high predation pressure showed the highest degree of matrotrophy (embryos quadruplicate their dry mass during development) and the greatest percentage of females with superfetation (44.4%). Some life history traits responded more strongly to predators’ presence and others to predator density. These results suggest that different predation regimes shape female life history traits, increasing fecundity in high‐predation sites. The results also suggest a link between the cost of reproduction and the evolution of matrotrophy and superfetation, potentially to reduce the risk of predation without reducing fecundity.