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Variation in heat-shock proteins among species of desert fishes (Poeciliidae, Poeciliopsis) 总被引:4,自引:0,他引:4
Analysis of the heat-shock proteins (hsps) of six closely related species
of Poeciliopsis demonstrated the existence of biochemical diversity in the
hsp100, hsp70, hsp60, and hsp30 protein families among species. Each
species expressed five to seven hsp70-related isoforms. Constitutive 70-kD
isoforms were identical among species, but four different patterns of
heat-inducible isoforms were seen in these six species. Members of the
hsp70 family of molecular chaperones are included among the most highly
conserved proteins known, and the possibility of variation in hsp70 among
closely related species has rarely been addressed. The hsp30 family is
known to be less conserved than the hsp70 family, and, as expected, the
Poeciliopsis hsp30 patterns showed more variation. Most of the hsp30
isoforms characteristic of a particular species were unique to that
species. Hsp100 and hsp60 were identical in five of the species, but
alternate isoforms were found in P. monacha. The small size and limited
geographical distribution of the P. monacha population have probably
contributed to the uniqueness of the monacha pattern. Two of the species
were shown to acquire thermotolerance, the ability to withstand normally
lethal temperatures when subjected to a gradual temperature increase.
Rapid-heating protocols commonly used to establish critical thermal maxima
of organisms do not include this inducible component of thermoresistance
and therefore do not adequately assess an organism's capacity to withstand
thermal stress.
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4.
Use of a Plasmid DNA Probe To Monitor Populations of Bacillus pumilus Inoculant Strains in Hay 总被引:2,自引:0,他引:2 下载免费PDF全文
Carol A. Hendrick Brenda K. Smiley Terrence H. Shelley Nancy J. Tomes 《Applied microbiology》1991,57(3):686-693
We are evaluating naturally occurring isolates of Bacillus pumilus for use as microbial hay preservatives. Seven isolates of B. pumilus from hay contained a 42-kb cryptic plasmid (pMGD296). We wished to determine whether pMGD296 could be used as a molecular marker to follow populations of these isolates in hay over time. Southern blots and colony blots of 69 isolates of B. pumilus and other Bacillus spp. were probed with 32P-labeled pMGD296. Twenty-nine probe-positive isolates were identified; of these, 28 contained a plasmid with a restriction profile identical to that of pMGD296. One isolate from untreated hay contained a 40-kb plasmid (pMGD150) that was homologous to pMGD296 but had a different restriction fragment pattern. Regions of homology between the two plasmids were identified by Southern blotting, and a 1.9-kb HindIII-PstI fragment of pMGD296 lacking strong homology to pMGD150 was cloned in pUC18. The cloned fragment hybridized only with isolates containing pMGD296 and was used to estimate populations of these isolates in treated and untreated hay. 相似文献
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Andrew P. Dare Sumathi Tomes Midori Jones Tony K. McGhie David E. Stevenson Ross A. Johnson David R. Greenwood Roger P. Hellens 《The Plant journal : for cell and molecular biology》2013,74(3):398-410
We have identified in apple (Malus × domestica) three chalcone synthase (CHS) genes. In order to understand the functional redundancy of this gene family RNA interference knockout lines were generated where all three of these genes were down‐regulated. These lines had no detectable anthocyanins and radically reduced concentrations of dihydrochalcones and flavonoids. Surprisingly, down‐regulation of CHS also led to major changes in plant development, resulting in plants with shortened internode lengths, smaller leaves and a greatly reduced growth rate. Microscopic analysis revealed that these phenotypic changes extended down to the cellular level, with CHS‐silenced lines showing aberrant cellular organisation in the leaves. Fruit collected from one CHS‐silenced line was smaller than the ‘Royal Gala’ controls, lacked flavonoids in the skin and flesh and also had changes in cell morphology. Auxin transport experiments showed increased rates of auxin transport in a CHS‐silenced line compared with the ‘Royal Gala’ control. As flavonoids are well known to be key modulators of auxin transport, we hypothesise that the removal of almost all flavonoids from the plant by CHS silencing creates a vastly altered environment for auxin transport to occur and results in the observed changes in growth and development. 相似文献
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Yunes R Tomes C Michaut M De Blas G Rodriguez F Regazzi R Mayorga LS 《FEBS letters》2002,525(1-3):126-130
The interaction between Rab3A and calmodulin is necessary for the inhibitory effect of Rab3A in neuroendocrine cells. Contrastingly, Rab3A triggers the exocytosis known as acrosome reaction in permeabilized spermatozoa. Here we show that a Rab3A mutant that cannot bind calmodulin was fully capable of triggering acrosomal exocytosis. Additionally, calmodulin by itself abrogated the exocytosis triggered by Rab3A. The effect was observed with both the wild type protein and the calmodulin binding deficient mutant. Our results indicate that the inhibitory and stimulatory effects of Rab3A in different exocytic processes are mediated by different effectors. 相似文献
8.
In clinical neurology, a comprehensive understanding of consciousness has been regarded as an abstract concept - best left
to philosophers. However, times are changing and the need to clinically assess consciousness is increasingly becoming a real-world,
practical challenge. Current methods for evaluating altered levels of consciousness are highly reliant on either behavioural
measures or anatomical imaging. While these methods have some utility, estimates of misdiagnosis are worrisome (as high as
43%) - clearly this is a major clinical problem. The solution must involve objective, physiologically based measures that
do not rely on behaviour. This paper reviews recent advances in physiologically based measures that enable better evaluation
of consciousness states (coma, vegetative state, minimally conscious state, and locked in syndrome). Based on the evidence
to-date, electroencephalographic and neuroimaging based assessments of consciousness provide valuable information for evaluation
of residual function, formation of differential diagnoses, and estimation of prognosis. 相似文献
9.
The acrosome is a membrane-limited granule that overlies the nucleus of the mature spermatozoon. In response to physiological or pharmacological stimuli, sperm undergo calcium-dependent exocytosis termed the acrosome reaction, which is an absolute prerequisite for fertilization. Protein tyrosine phosphorylation and dephosphorylation are a mechanisms by which multiple cellular events are regulated. Here we report that calcium induces tyrosine phosphorylation in streptolysin O (SLO)-permeabilized human sperm. As expected, pretreatment with tyrphostin A47-a tyrosine kinase inhibitor-abolishes the calcium effect. Interestingly, the calcium-induced increase in tyrosine phosphorylation has a functional correlate in sperm exocytosis. Masking of phosphotyrosyl groups with a specific antibody or inhibition of tyrosine kinases with genistein, tyrphostin A47, and tyrphostin A51 prevent the acrosome reaction. By reversibly sequestering intra-acrosomal calcium with a photo-inhibitable chelator, we show a requirement for protein tyrosine phosphorylation late in the exocytotic pathway, after the efflux of intra-acrosomal calcium. Both mouse and human sperm contain highly active tyrosine phosphatases. Importantly, this activity declines when sperm are incubated under capacitating conditions. Inhibition of tyrosine phosphatases with pervanadate, bis(N,N-dimethylhydroxoamido)hydroxovanadate, ethyl-3,4-dephostatin, and phenylarsine oxide prevents the acrosome reaction. Our results show that both tyrosine kinases and phosphatases play a central role in sperm exocytosis. 相似文献
10.
The development and release of a new tomato variety which produces fruit containing approximately ten times the provitamin A content of common red tomatoes is announced. The betacarotene values for Caro-Red are within the lower ranges reported for carrots. Present consumer usage of a variety such as Caro-Red will most likely be confined to use as a garden type where additional variety and flavor are desired. 相似文献