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排序方式: 共有124条查询结果,搜索用时 15 毫秒
91.
Yeo M Acosta N Llewellyn M Sánchez H Adamson S Miles GA López E González N Patterson JS Gaunt MW de Arias AR Miles MA 《International journal for parasitology》2005,35(2):225-233
Trypanosoma cruzi, the causative agent of Chagas disease, has at least two principal intraspecific subdivisions, T. cruzi I (TCI) and T. cruzi II (TCII), the latter containing up to five subgroups (a-e). Whilst it is known that TCI predominates from the Amazon basin northwards and TCII to the South, where the disease is considered to be clinically more severe, the precise clinical and evolutionary significance of these divisions remains enigmatic. Here, we present compelling evidence of an association between TCI and opossums (Didelphis), and TCII and armadillos, on the basis of key new findings from the Paraguayan Chaco region, together with a comprehensive analysis of historical data. We suggest that the distinct arboreal and terrestrial ecologies, respectively, of these mammal hosts provide a persuasive explanation for the extant T. cruzi intraspecific diversity in South America, and for separate origins of Chagas disease in northern South America and in the southern cone countries. 相似文献
92.
93.
M.V. Martinez-Toledo J. Gonzalez-Lopez T. de la Rubia A. Ramos-Cormenzana 《FEMS microbiology letters》1985,31(4):197-203
Abstract Bacteria showing rapid growth on a nitrogenfree medium and acetylene-reducing activity were isolated from maize roots collected from agricultural soils in Spain. The isolates were Gram-negative motile rods and were identified as Azotobacter chroococcum . Acetylene-reducing activity and microbial counts were determined on root segments from 7- and 30-day-old plants. Rates obtained were in the range of 0.0053–0.848 nmol C2 H2 · g−1 · h−1 . Root populations were 1.4–6.0 × 104 micro-organisms · g−1 . These results showed that there was an association between A. chroococcum strains and roots of maize planted in some Spanish soils. 相似文献
94.
Environmental suitability for Agrilus auroguttatus (Coleoptera: Buprestidae) in Mexico using MaxEnt and database records of four Quercus (Fagaceae) species
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Víctor López‐Martínez Guillermo Sánchez‐Martínez Daniel Jiménez‐García Nidia B. Pérez‐De la O Tom W. Coleman 《Agricultural and Forest Entomology》2016,18(4):409-418
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95.
José Gilmar C. Oliveira Júnior Luana P. S. Silva Ana C. M. Malhado Vandick S. Batista Nidia N. Fabré Richard J. Ladle 《PloS one》2016,11(3)
Given limited funds for research and widespread degradation of ecosystems, environmental scientists should geographically target their studies where they will be most effective. However, in academic areas such as conservation and natural resource management there is often a mismatch between the geographic foci of research effort/funding and research needs. The former frequently being focused in the developed world while the latter is greater in the biodiverse countries of the Global South. Here, we adopt a bibliometric approach to test this hypothesis using research on artisanal fisheries. Such fisheries occur throughout the world, but are especially prominent in developing countries where they are important for supporting local livelihoods, food security and poverty alleviation. Moreover, most artisanal fisheries in the Global South are unregulated and unmonitored and are in urgent need of science-based management to ensure future sustainability. Our results indicate that, as predicted, global research networks and centres of knowledge production are predominantly located in developed countries, indicating a global mismatch between research needs and capacity. 相似文献
96.
Silvina Mónica Alvarez Nidia Noemí Gómez Luis Scardapane Miguel Walter Fornés María Sofía Giménez 《Biometals》2007,20(5):727-741
Cadmium is an environmental toxic metal implicated in human prostate carcinogenesis. The mechanism of its toxicity is not
fully understood. Previously, we showed that cadmium exposure induces oxidative stress, especially lipid peroxidation. This
study evaluates the effect of chronic exposure to 0.886 mM of cadmium (Cd) per liter in the drinking water on prostate lipid
content and metabolism in Wistar rats. We determined the lipid profile and measured the expression of lipogenic enzymes: FAS,
GPAT, LPL, DGAT-1, DGAT-2, ACO, CPT-1 and CT, and of certain factors involved in lipid regulation and fatty acid transporters:
FAT/CD36, E-FABP, SREBP-2, PPAR-γ and PPAR-α by RT-PCR. Ultrastructure was analyzed by electron microscopy and, as prostate
is an androgen controlled gland, AR expression was measured by RT-PCR and Western blot. Cd altered the prostatic lipid profile.
Triglycerides (TG) and esterified cholesterol (EC) decreased, free cholesterol (FC) and phospholipids (PL) increased and total
cholesterol (TC) did not change. FAS, MDH and IDH activities did not vary but G6PDH decreased significantly in Cd group. Regarding
TG synthesis, DGAT-1 decreased while GPAT increased and FAS, LPL and DGAT-2 remained unchanged. Regarding beta oxidation,
CPT-1 increased while ACO expression decreased in Cd group. In the PL pathway, CT expression was increased. All these results
would justify the decrease of TG in Cd group when compared to control. In the cholesterol metabolic pathway, HMGCoAR and SREBP-2
increased. PPAR-α increased but PPAR-γ did not change. Regarding fatty acid transporters, FAT/CD36 decreased, while E-FABP
increased. AR mRNA and protein expression decreased. Ultrastructural analysis showed a decrease in lipid droplets and signs
of cellular damage in the Cd group.
Cadmium exposure induces important changes in prostatic lipid profile and metabolism, confirmed by the morphology analyses,
which also showed signs of cellular damage. These results could be important to further understanding the complex mechanism
of cadmium toxicity in prostate and in the development of better treatments for people and animals exposed to the heavy metal.
Fellowship from the National Council of Scientific and Technical Investigations (CONICET) – Argentina.
Career Scientific Investigator. National Council of Scientific and Technical Investigations (CONICET) – Argentina. 相似文献
97.
98.
Sophia Spadavecchia Olga Gonzalez-Lopez Kyla Driscoll Carroll Diana Palmeri David M. Lukac 《Journal of virology》2010,84(20):10488-10500
99.
In light of the Central American Initiative for the control of Chagas disease, efforts were made on the part of Costa Rican and Nicaraguan teams, working separately, to determine the present status of Rhodnius pallescens in areas close to the common border of the two countries, where the insect has appeared within the last few years. The opportunity was also used to establish whether R. prolixus, a vector present in some areas of Nicaragua, has been introduced in recent years into Costa Rica with Nicaraguan immigrants. It became evident that wild adults of R. pallescens are common visitors to houses in different towns of a wide area characterized as a humid, warm lowland, on both sides of the frontier. Up to the present, this bug has been able to colonize a small proportion of human dwellings only on the Nicaraguan side. There was strong evidence that the visitation of the adult bug to houses is related to the attraction of this species to electric lights. There were no indications of the presence of R. prolixus either in Nicaragua or in Costa Rica in this area of the Caribbean basin. Triatoma dimidiata, a widespread domestic species in both countries, was totally absent in the explored areas of Costa Rica but occasionally occurs on the Nicaraguan side. Serological surveys in children of both areas showed that transmission of Chagas disease takes place in a rather small degree in Costa Rica and more commonly in Nicaragua, indicating that R. pallescens could be a potential threat as a vector in this particular region. 相似文献
100.
The formation of calcite and struvite crystals byAzotobacter vinelandii andA.chroococcum was studied on chemically defined media. The crystals were identified microscopically and by X-ray differentiation analysis. Calcite crystal formation was inhibited specifically with 0.05 % ammonium sulfate. However, 0.2 % ammonium sulfate was required for struvite crystal formation. 相似文献