Spiny rats of the genus Proechimys are morphologically diverse, widely distributed and have diploid numbers ranging from 2n = 14-16 to 2n = 62. In this paper we present cytogenetical data and brief comments on morphological and biogeographical issues related to spiny rats. In our sample of 42 spiny rats collected from 12 Brazilian Amazonian tropical rainforest and the Cerrado (Brazilian savanna) sites we detected nine karyological entities: four different karyomorphs with 2n = 30, three with 2n = 28, one with 2n = 15 and one with 2n = 44. Based on qualitative morphological characters these karyomorphs can be allocated to five species within the goeldii, guyannensis and longicaudatus species groups.
Eight current species of snakes of the Bothrops neuwiedi group are widespread in South American open biomes from northeastern Brazil to southeastern Argentina. In this paper, 140 samples from 93 different localities were used to investigate species boundaries and to provide a hypothesis of phylogenetic relationships among the members of this group based on 1122bp of cyt b and ND4 from mitochondrial DNA and also investigate the patterns and processes occurring in the evolutionary history of the group. Combined data recovered the B. neuwiedi group as a highly supported monophyletic group in maximum parsimony, maximum likelihood and Bayesian analyses, as well as four major clades (Northeast I, Northeast II, East-West, West-South) highly-structured geographically. Monophyly was recovered only for B. pubescens. By contrast, B. diporus, B. lutzi, B. erythromelas, B. mattogrossensis, B. neuwiedi, B. marmoratus, and B. pauloensis, as currently defined on the basis of morphology, were polyphyletic. Sympatry, phenotypic intergrades and shared mtDNA haplotypes, mainly between B. marmoratus and B. pauloensis suggest recent introgressive hybridization and the possible occurrence of a narrow hybrid zone in Central Brazil. Our data suggest at least three candidate species: B. neuwiedi from Espinhaço Range, B. mattogrossensis (TM173) from Serra da Borda (MT) and B. diporus (PT3404) from Castro Barros, Argentina. Divergence estimates highlight the importance of Neogene events in the origin of B. neuwiedi group, and the origin of species and diversification of populations of the Neotropical fauna from open biomes during the Quaternary climate fluctuations. Data reported here represent a remarkable increase of the B. neuwiedi group sampling size, since representatives of all the current recognized species from a wide geographic range are included in this study, providing basic information for understanding the evolution and conservation of Neotropical biodiversity.
dRapid identification of drug resistance in clinical isolates of Mycobacterium tuberculosis is important in determining treatment for tuberculosis. The aim of this work was evaluate the performance of the GenoType MDRTBplus assay directly on sputum of patients who had treatment failure or relapse in a routine outpatient setting in southern Brazil.
Key words:Preparedness measures to cope with droughts and water scarcity in semi-arid climates in irrigated agriculture include the identification of irrigation scheduling strategies that minimize the water demand with acceptable impacts on yields. Those strategies may be produced by simulation and focus on different levels of water demand. The irrigation scheduling simulation model ISAREG, validated for Tunisia, is used to simulate those strategies. The generated irrigation scheduling strategies are applied to deficit irrigation of winter wheat, tomato and potato crops under semi-arid conditions in Central Tunisia. The alternative schedules are evaluated through the combined use of indicators relative to the reduction in demand for irrigation water, the consequent yield reduction and the impacts on farmer's income. The economic evaluation of those strategies is performed with the help of a linear programming model. Results indicate that, when there is limited water availability, each crop reacts differently to the water restrictions applied in terms of yield decrease and gross margin per unit surface and unit of water applied. For average demand, the adoption of deficit irrigation is generally feasible for all crops considered. However, for the tomato crop, there is a trend to restrict the cultivated surface when water scarcity increases. Under high and very high demand conditions, the gross margin per unit of water applied decreases for the potato and the tomato crops but increases for the wheat crop. Then, adopting deficit irrigation is not feasible for the tomato and potato crops, the option being to decrease the cultivated surface. On the contrary, the wheat crop responds wen to deficit irrigation, with a good water valorisation, including under drought conditions. A. Zairi et al.The frequent occurrence of droughts requires pro-active and rational water management approaches that could be helpful to both managers and farmers. Those measures include the reinforcement of the hydraulic infrastructures, increased waste water reuse, the enforcement of restrictions on water volumes supplied for irrigation, and changes in water prices . However, their application require s better knowledge of the climatic variability and respective impact on crop yields.A recent study shows that a decrease of 10 % in water supply to cereal s and fodder crops would result in a reduction of about 2 % in the net agricultural product, mainly as a consequence of a reduction in the irrigated area (DGIRE, 1997). Irrigated wheat surface (60 000 ha) is less than 5 % of the total cereal cropped area in Tunisia but, when drought occurs, the irrigated wheat area contributes with 20 % to the total cereal production, while also playing a main role in seed production (El Amami, 1995).In order to prepare appropriate irrigation strategies for wheat and main field horticultural crops, tomato and potato, when water supply restrictions have to be imposed, the present study was performed to assess how deficit irrigation (English and Raja, 1996) could...
Background: The thin-spined porcupine, also known as the bristle-spined rat, Chaetomys subspinosus (Olfers, 1818), the only member of its genus, figures among Brazilian endangered species. In addition to being threatened, it is poorly known, and even its taxonomic status at the family level has long been controversial. The genus Chaetomys was originally regarded as a porcupine in the family Erethizontidae, but some authors classified it as a spiny-rat in the family Echimyidae. Although the dispute seems to be settled in favor of the erethizontid advocates, further discussion of its affinities should be based on a phylogenetic framework. In the present study, we used nucleotide-sequence data from the complete mitochondrial cytochrome b gene and karyotypic information to address this issue. Our molecular analyses included one individual of Chaetomys subspinosus from the state of Bahia in northeastern Brazil, and other hystricognaths.
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