Human immunodeficiency virus (HIV) frequently causes neurological dysfunction and is abundantly expressed in the central nervous system (CNS) of acquired immunodeficiency syndrome (AIDS) patients with HIV encephalitis or myelopathy. The virus is found mostly in cells of the monocyte-macrophage lineage within the CNS, but the possibility of infection of other glial cells has been raised. Therefore, the effects of different HIV-1 and HIV-2 strains were studied in primary cultures of adult human brain containing microglial cells, the resident CNS macrophages, and astrocytes. These cultures could be productively infected with macrophage-adapted HIV-1 isolates but not with T lymphocyte-adapted HIV-1 isolates or two HIV-2 isolates. As determined with a triple-label procedure, primary astrocytes did not express HIV gag antigens and remained normal throughout the 3-week course of infection. In contrast, virus replicated in neighboring microglial cells, often leading to their cell fusion and death. The death of microglial cells, which normally serve immune functions in the CNS, may be a key factor in the pathogenesis of AIDS encephalitis or myelopathy. 相似文献
X-linked Alport syndrome is a hereditary glomerulonephritis in which progressive loss of kidney function is often accompanied by progressive loss of hearing. Ultrastructural defects in glomerular basement membranes (GBM) of Alport syndrome patients implicate an altered structural protein as the cause of nephritis. The product of COL4A5, the alpha 5(IV) collagen chain, is a specific component of GBM within the kidney, and the gene maps to the same X chromosomal region as does Alport syndrome. Three structural aberrations were found in COL4A5, in intragenic deletion, a Pst I site variant, and an uncharacterized abnormality, which appear to cause nephritis and deafness, with allele-specific severity, in three Alport syndrome kindreds in Utah. 相似文献
Confocal laser-scanned microscopy and long-wavelength calcium (Ca2+) indicators were combined to monitor both sustained and rapidly dissipating Ca2+ gradients in voltage-clamped sympathetic neurons isolated from the bullfrog. After a brief activation of voltage-dependent Ca2+ channels, Ca2+ spreads inwardly, and reaches the center of these spherical cells in about 300 milliseconds. Although the Ca2+ redistribution in the bulk of the cytosol could be accounted for with a radial diffusion model, local nonlinearities, suggesting either nonuniform Ca2+ entry or spatial buffering, could be seen. After electrical stimulation, Ca2+ signals in the nucleus were consistently larger and decayed more slowly than those in the cytosol. A similar behavior was observed when release of intracellular Ca2+ was induced by caffeine, suggesting that in both cases large responses originate from Ca2+ release sites near or within the nucleus. These results are consistent with an amplification mechanism involving Ca2(+)-induced Ca2+ release, which could be relevant to activity-dependent, Ca2(+)-regulated nuclear events. 相似文献
Among the most important Mediterranean annual crops, durum wheat is widely grown in drought-prone areas. Therefore, improving water-use efficiency (WUE) of durum wheat represents a major breeding goal. IDu-WUE (Improving Durum wheat for Water Use Efficiency and yield stability through physiological and molecular approaches) is a collaborative project among public and private research centres in Italy, Spain and WANA (West Asia and North Africa) countries (Morocco, Tunisia, Syria and Lebanon) funded by the European Union aimed at investigating the genetic variation for WUE and yield stability in durum wheat grown in Mediterranean droughtprone areas. During the first year of the project, a number of morpho-physiological traits (e.g. early vigour, flowering time, leaf rolling, number of fertile tillers, etc.), WUE, WUE-related traits (e.g. carbon isotope discrimination, canopy temperature, chlorophyll fluorescence, etc.), yield and its components have been investigated in a RIL population (249 lines) and a collection of ca. 190 durum wheat accessions characterized by a high level of linkage disequilibrium (Maccaferri et al., 2005), 相似文献
A total of 105 European wheat cultivars were assessed for seedling and adult plant resistance (APR) to stem rust using an
array of Australian isolates of Puccinia graminis f. sp. tritici. Twenty-seven cultivars were susceptible at both seedling and adult plant growth stages. Twelve catalogued seedling stem
rust resistance genes (Sr7b, Sr8a, Sr8b, Sr9b, Sr9g, Sr11, Sr15, Sr17, Sr29, Sr31, Sr36 and Sr38) were detected in the remaining cultivars, and 13 cultivars carried additional seedling resistance genes that could not be
postulated with the isolates used. Low levels of APR to stem rust were found in the cultivars Artaban, Forno, Mec, Mercia,
Pandas and Vlada. Although the genetic identity of this APR was not determined, it was clear that the only designated stem
rust APR gene Sr2 was not present in any of the cultivars tested based on the absence of the linked traits seedling chlorosis and pseudo black
chaff. One of these cultivars, Forno, is believed to carry the leaf rust APR gene Lr34, previously reported to be associated with improved resistance to stem rust. A detailed genetic characterisation of the APRs
in these cultivars will be needed to understand their modes of inheritance and relationships with catalogued stem rust resistance
genes. Such knowledge may help in developing cultivars with effective gene combinations that confer higher levels of protection. 相似文献
A total of 50 wheat (Triticum aestivum L.) cultivars were evaluated for resistance to tan spot, using Pyrenophora tritici‐repentis race 1 and race 5 isolates. The cultivars ‘Salamouni’, ‘Red Chief’, ‘Dashen’, ‘Empire’ and ‘Armada’ were resistant to isolate ASC1a (race 1), whereas 76% of the cultivars were susceptible. Chi‐squared analysis of the F2 segregation data of hybrids between 20 monosomic lines of the wheat cultivar ‘Chinese Spring’ and the resistant cultivar ‘Salamouni’ revealed that tan spot resistance in ‘Salamouni’ was controlled by a single recessive gene located on chromosome 3A. This gene is designated tsn4. The resistant cultivars identified in this study are recommended for use in breeding programmes to improve tan spot resistance in common wheat. 相似文献
The objective was to determine the critical N dilution curve of linseed, which is the minimal total N concentration in shoots necessary to produce the maximal shoot dry matter, and to explain possible differences with other C3 species. One main experiment was carried out in 1998/1999 on winter linseed with four levels of fertilizer N. Two plant densities were also studied, the recommended one (600 seeds m−2) and the minimum for canopy closure (150 seeds m−2), in order to investigate the stability with plant density of the critical N dilution curve. Shoot dry weights (WS) and shoot N contents expressed in percentage (NS) were measured for the determination of the critical dilution curve, along with organ N percentages and relative weights. The results of four other experiments were used to validate the critical N dilution curve. Three of these four trials were conducted on winter linseed (one in 1996/1997 and two in 1997/1998) with five levels of fertilizer N, and one on spring linseed in 1999 with six levels of fertilizer N.
The critical N dilution curve of linseed was different from those of other C3 species. The curve was steeper, indicating a greater decrease in the critical shoot N concentration (NSC) as the critical shoot dry weight (WSC) increased. This linseed curve determined with the data of the main experiment was relevant when compared to the data of the four other experiments. Organ weight ratios and N concentration of organs were investigated in a fertilizer N treatment resulting in NS close to the critical N values, NSC. In this treatment, the decrease in NS was the result of both a decrease in the N percentage of all organs and a decrease in the leaf weight ratio. The difference between linseed and other C3 species was mainly due to an acceleration of the dilution of N when leaf emission stopped and the flower bud emission began. At this stage of development, the leaf weight ratio of linseed was less than that of wheat, resulting in lower NS. For a given WS, no significant differences in NS, organ N percentages nor organ weight ratios were observed between the two plant densities. This indicates that the difference between linseed and other C3 species could not result from very high plant densities in linseed. Hence, it is concluded that the linseed N accumulation in shoot is different from other C3 species. 相似文献