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531.
532.
The sequences of ITS regions in 30 species and two groups of the genusPythium were resolved. In the phylogenetic trees, the species were generally divided into two clusters, referred to here as the F
and S groups. The species in the two groups correspond in terms of their sporangial morphology, with the F group being filamentous/lobulate
and the S group being spherical. Genetic divergence within the F group was lower than that within the S group. Other morphological
characteristics such as oogonial structure and sexual nature appeared to be unrelated to the groupings in these trees. An
alignment analysis revealed common sequences to all the species and arrangements specific to each F or S group. It was found
that the ITS region was a good target in designing species-specific primers for the identification and detection ofPythium species. In the tree based on 5.8S rDNA sequences, oomycetes are distantly related to other fungi but separated from algae
in Chromista. 相似文献
533.
Growth promotion ability of zoysiagrass rhizosphere fungi in consecutive plantings of wheat and soybean 总被引:1,自引:0,他引:1
Manchanahally Byrappa Shivanna Manchanahally Shivanna Meera Koji Kageyama Mitsuro Hyakumachi 《Mycoscience》1996,37(2):163-168
Several isolates ofPhoma sp., certain nonsporulating fungi, as well asPenicillium andTrichoderma, all isolated from zoysiagrass rhizosphere, promoted growth of wheat and soybean under greenhouse conditions. However, the
ability of these rhizosphere fungi to enhance plant growth varied with the crop tested. For example, most of the fungi effectively
promoted the growth of wheat, whereas only a few fungi were effective on soybean. In consecutive plantings of wheat and soybean
grown in soil previously infested with these zoysiagrass rhizosphere fungi, the growth promotion ability of the fungi was
lowered. However, addition of fresh potting medium appeared to restore their growth-promotive effects. It appears that the
activation of plant growth-promoting fungi in soil might depend on the availability of organic substrates to colonize, as
evidenced by the promotion of plant growth. 相似文献
534.
Dana S. Wall Alan J. Mears Brian McNeill Chantal Mazerolle Sherry Thurig Yaping Wang Ryoichiro Kageyama Valerie A. Wallace 《The Journal of cell biology》2009,184(1):101-112
Sonic hedgehog (Shh) is an indispensable, extrinsic cue that regulates progenitor and stem cell behavior in the developing and adult mammalian central nervous system. Here, we investigate the link between the Shh signaling pathway and Hes1, a classical Notch target. We show that Shh-driven stabilization of Hes1 is independent of Notch signaling and requires the Shh effector Gli2. We identify Gli2 as a primary mediator of this response by showing that Gli2 is required for Hh (Hedgehog)-dependent up-regulation of Hes1. We also show using chromatin immunoprecipitation that Gli2 binds to the Hes1 promoter, which suggests that Hes1 is a Hh-dependent direct target of Gli2 signaling. Finally, we show that Shh stimulation of progenitor proliferation and cell diversification requires Gli2 and Hes1 activity. This paper is the first demonstration of the mechanistic and functional link between Shh, Gli, and Hes1 in the regulation of progenitor cell behavior. 相似文献
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