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131.
132.
Martha Robles-Flores Erika Rendon-Huerta Hector Gonzalez-Aguilar Guillermo Mendoza-Hernandez Socorro Islas Valentin Mendoza M Veronica Ponce-Castaneda Lorenza Gonzalez-Mariscal Fernando Lopez-Casillas 《The Journal of biological chemistry》2002,277(7):5247-5255
The aim of this study was to identify cellular proteins that bind protein kinase C (PKC) and may influence its activity and its localization. A 32-kDa PKC-binding protein was purified to homogeneity from the Triton X-100-insoluble fraction obtained from hepatocytes homogenates. The protein was identified by NH(2)-terminal amino acid sequencing as the previously described mature form of p32 (gC1qR). Recombinant p32 was expressed as a glutathione S-transferase fusion protein, affinity-purified, and tested for an in vitro interaction with PKC using an overlay assay approach. All PKC isoforms expressed in rat hepatocytes interacted in vitro with p32, but the binding dependence on PKC activators was different for each one. Whereas PKCdelta only binds to p32 in the presence of PKC activators, PKCzeta and PKCalpha increase their binding when they are in the activated form. Other PKC isoforms such as beta, epsilon, and theta bind equally well to p32 regardless of the presence of PKC activators, and PKCmu binds even better in their absence. It was also found that p32 is not a substrate for any of the PKC isoforms tested, but interestingly, its presence had a stimulatory effect (2-fold for PKCdelta) on PKC activity. We also observed in vivo interaction between PKC and p32 by immunofluorescence and confocal microscopy. A time course of phorbol ester treatment of cultured rat hepatocytes (C9 cells) showed that PKCtheta and p32 are constitutively associated in vivo, whereas PKCdelta activation is required for its association with p32. Our data also showed that phorbol ester treatment induces a transient translocation of p32 from the cytoplasm to the cell nucleus. Together, these findings suggest that p32 may be a regulator of PKC location and function. 相似文献
133.
Hector E. Flores Paula J. Sgrignoli 《In vitro cellular & developmental biology. Plant》1991,27(3):139-142
Summary The lengthy dormancy requirement of yew seeds can be overcome with a simple in vitro method. Viable embryos were excised from
seeds ofTaxus brevifolia and four cultivars ofT. media over a range of developmental stages. Embryos were cultured in several basal media formulations (Whites’, Gamborg’s B5 and
Murashige and Skoog’s) under dark or light. After a lag period of 1 to 2 wk, embryos of both species germinated precociously.
Germination rates of up to 70% were obtained withT. media cv. Hicksi embryos. The highest rates of germination were obtained in White’s and MS media. Embryos excised from green seeds
with undeveloped arils showed the highest germination rates. As the seeds approached maturity, in vitro germination rates
of the excised embryos declined dramatically. Green seeds and seeds with developing arils could be stored at 5° C without
large loss in embryo germination. Seeds with fully developed arils could be stored frozen at −20° C for 1 wk while still allowing
about 50% of embryo germination. At least 30% of the precociously germinated embryos of both species were able to develop
into full seedlings. Our method appears to be generally applicable toTaxus spp.
This research was supported by a grant from the Hawaii Biotechnology Group, Inc. 相似文献
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137.
Xinsheng Zhu Georgina Gurrola Ming Tao Jiang Jeffery W. Walker Hector H. Valdivia 《FEBS letters》1999,450(3):417-226
A 25 amino acid segment (Glu666-Pro691) of the II-III loop of the alpha1 subunit of the skeletal dihydropyridine receptor, but not the corresponding cardiac segment (Asp788-Pro814), activates skeletal ryanodine receptors. To identify the structural domains responsible for activation of skeletal ryanodine receptors, we systematically replaced amino acids of the cardiac II-III loop with their skeletal counterparts. A cluster of five basic residues of the skeletal II-III loop (681RKRRK685) was indispensable for activation of skeletal ryanodine receptors. In the cardiac segment, a negatively charged residue (Glu804) appears to diminish the electrostatic potential created by this basic cluster. In addition, Glu800 in the group of negatively charged residues 798EEEEE802 of the cardiac II-III loop may serve to prevent the binding of the activation domain. 相似文献
138.
Salome LopezSerna Catalina GonzalezQuevedo Hector Fabio RiveraGutierrez 《Ecology and evolution》2021,11(24):18552
In animal communication, signals are expected to evolve to be honest, so that receivers avoid being manipulated by signalers. One way that signals can evolve to be honest is for them to be costly, with only high‐quality individuals being able to bear the costs of signal expression. It has been proposed that parasites can introduce costs that affect the expression of sexually selected traits, and there is evidence to support the role of parasitism in modulating animal behavior. If host infection status or intensity is found to relate to differences in signal expression, it may indicate a fitness cost that mediates honesty of signals. Birdsong is a good model for testing this, and physically challenging songs representing complex motor patterns provide a good example of sexually selected traits indicating individual condition. We performed a field study to evaluate the relationship between song performance and avian malaria infection in a common songbird. Previous work on this subject has almost always evaluated avian malaria in terms of binary infection status; however, parasitemia—infection intensity—is rarely assessed, even though differences in parasite load may have profound physiological consequences. We estimated parasitemia levels by using real‐time PCR. We found that birds with higher parasitemia displayed lower vocal performance, providing evidence that this song trait is an honest signal of parasitic load of haemosporidian parasites. To our knowledge, this study links parasite load and the expression of a sexually selected trait in a way that has not been addressed in the past. Studies using song performance traits and parasitemia offer an important perspective for understanding evolution of characters via sexual selection. 相似文献
139.
Hector M. Alvarez Frank Mayer Dirk Fabritius A. Steinbüchel 《Archives of microbiology》1996,165(6):377-386
An oleaginous hydrocarbon-degrading Rhodococcus opacus strain (PD630) was isolated from a soil sample. The cells were able to grow on a variety of substrates and to produce large
amounts of three different types of intracellular inclusions during growth on alkanes, phenylalkanes, or non-hydrocarbon substrates.
Electron microscopy revealed large numbers of electron-transparent inclusions with a sphere-like structure. In addition, electron-dense
inclusions representing polyphosphate and electron-transparent inclusions with an elongated disc-shaped morphology occurred
in small amounts. The electron-transparent inclusions of alkane- or gluconate-grown cells were composed of neutral lipids
(98%, w/w), phospholipids (1.2%, w/w), and protein (0.8%, w/w). The major component of the cellular inclusions was triacylglycerols;
minor amounts of diacylglycerols and probably also some free fatty acids were also present. Free fatty acids and/or fatty
acids in acylglycerols in cells of R. opacus amounted up to 76 or 87% of the cellular dry weight in gluconate- or olive-oil-grown cells, respectively. The fatty acid composition
of the inclusions depended on the substrate used for cultivation. In cells cultivated on n-alkanes, the composition of the
fatty acids was related to the substrate, and intermediates of the β-oxidation pathway, such as hexadecanoic or pentadecanoic
acid, were among the acylglycerols. Hexadecanoic acid was also the major fatty acid (up 36% of total fatty acids) occurring
in the lipid inclusions of gluconate-grown cells. This indicated that strain PD630 utilized β-oxidation and de novo fatty
acid biosynthesis for the synthesis of storage lipids. Inclusions isolated from phenyldecane-grown cells contained mainly
the non-modified substrate and phenylalkanoic acids derived from the hydrocarbon oxidation, such as phenyldecanoic acid, phenyloctanoic
acid, and phenylhexanoic acid, and approximately 5% (w/w) of diacylglycerols. The lipid inclusions seemed to have definite
structures, probably with membranes at their surfaces, which allow them to maintain their shape, and with some associated
proteins, probably involved in the inclusion formation.
Received: 22 December 1995 / Accepted: 12 March 1996 相似文献
140.
Hector Hernandez-Vargas Marie-Pierre Lambert Florence Le Calvez-Kelm Géraldine Gouysse Sandrine McKay-Chopin Sean V. Tavtigian Jean-Yves Scoazec Zdenko Herceg 《PloS one》2010,5(3)