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Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sections 总被引:15,自引:4,他引:11 下载免费PDF全文
A method of rapid freezing in supercooled Freon 22 (monochlorodifluoromethane) followed by cryoultramicrotomy is described and shown to yield ultrathin sections in which both the cellular ultrastructure and the distribution of diffusible ions across the cell membrane are preserved and intracellular compartmentalization of diffusabler ions can be quantitated. Quantitative electron probe analysis (Shuman, H., A.V. Somlyo, and A.P. Somlyo. 1976. Ultramicros. 1:317-339.) of freeze-dried ultrathin cryto sections was found to provide a valid measure of the composition of cells and cellular organelles and was used to determine the ionic composition of the in situ terminal cisternae of the sarcoplasmic reticulum (SR), the distribution of CI in skeletal muscle, and the effects of hypertonic solutions on the subcellular composition if striated muscle. There was no evidence of sequestered CI in the terminal cisternae of resting muscles, although calcium (66mmol/kg dry wt +/- 4.6 SE) was detected. The values of [C1](i) determined with small (50-100 nm) diameter probes over cytoplasm excluding organelles over nuclei or terminal cisternae were not significantly different. Mitochondria partially excluded C1, with a cytoplasmic/ mitochondrial Ci ratio of 2.4 +/- 0.88 SD. The elemental concentrations (mmol/kg dry wt +/- SD) of muscle fibers measured with 0.5-9-μm diameter electron probes in normal frog striated muscle were: P, 302 +/- 4.3; S, 189 +/- 2.9;C1, 24 +/- 1.1;K, 404 +/- 4.3, and Mg, 39 +/- 2.1. It is concluded that: (a) in normal muscle the "excess CI" measured with previous bulk chemical analyses and flux studies is not compartmentalized in the SR or in other cellular organelles, and (b) the cytoplasmic C1 in low [K](0) solutions exceeds that predicted by a passive electrochemical distribution. Hypertonic 2.2 X NaCl, 2.5 X sucrose, or 2.2 X Na isethionate produced: (a) swollen vacuoles, frequently paired, adjacent to the Z lines and containing significantly higher than cytoplasmic concentrations of Na and Cl or S (isethionate), but no detectable Ca, and (b) granules of Ca, Mg, and P = approximately (6 Ca + 1 Mg)/6P in the longitudinal SR. It is concluded that hypertonicity produces compartmentalized domains of extracellular solutes within the muscle fibers and translocates Ca into the longitudinal tubules. 相似文献
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AV Shevchenko IG Budzanivska TP Shevchenko VP Polischuk D Spaar 《Archives Of Phytopathology And Plant Protection》2013,46(2):139-146
The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants. 相似文献
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Downs Stephen G.; Ratnieks Francis L. W.; Badcock Nichola S.; Mynott Amanda 《Behavioral ecology》2001,12(1):47-50
Honeybee (Apis mellifera) colonies rob honey from each other
during periods of nectar shortage. Persistent robbing can killweak colonies. Primarily responsible for preventing robbingare guard bees. Previous research has shown that the probabilityof both nest mate and non-nest mate workers being acceptedby guards at the nest entrance increases as nectar availability
increases. The mechanism responsible for this change in guardacceptance can be explained by two competing hypotheses: OdorConvergence and Adaptive Threshold Shift. In this study wetested the Odor Convergence hypothesis. The acceptance by guardsat the nest entrance of workers transferred between four coloniesthat had been fed either odorless sucrose syrup (two colonies)or diluted heather honey (Calluna vulgaris) (two colonies)was measured for 3 days before feeding and during 2 weeks offeeding. Despite the large sample sizes, the probability ofguards accepting non-nest mates was not affected by the similaritiesor dissimilarities in food odor between guards' and non-nestmates' colonies. This finding contrasts with the accepted wisdom
that food odors are important in nest mate recognition in honeybeesand the data, therefore, strongly reject the Odor Convergencehypothesis. 相似文献
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Usdin K; Chevret P; Catzeflis FM; Verona R; Furano AV 《Molecular biology and evolution》1995,12(1):73-82
The single most difficult problem in phylogenetic analysis is deciding
whether a shared taxonomic character is due to common ancestry or one that
appeared independently due to convergence, parallelism, or reversion to an
ancestral state. Mammalian L1 retrotransposons undergo periodic
amplifications in which multiple copies of the elements are interspersed in
the genome. Because these elements apparently are transmitted only by
inheritance and are retained in the genome, a shared L1 amplification event
can only be an inherited ancestral character. We propose that L1
amplification events can be an excellent tool for analyzing mammalian
evolution and demonstrate here how we addressed several refractory problems
in rodent systematics using L1 DNA as a taxonomic character.
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R Alan Harris Dorottya Nagy-Szakal Sabina AV Mir Eibe Frank Reka Szigeti Jess L Kaplan Jiri Bronsky Antone Opekun George D Ferry Harland Winter Richard Kellermayer 《Epigenetics》2014,9(8):1131-1137
Inflammatory bowel diseases (IBD) are emerging globally, indicating that environmental factors may be important in their pathogenesis. Colonic mucosal epigenetic changes, such as DNA methylation, can occur in response to the environment and have been implicated in IBD pathology. However, mucosal DNA methylation has not been examined in treatment-naïve patients. We studied DNA methylation in untreated, left sided colonic biopsy specimens using the Infinium HumanMethylation450 BeadChip array. We analyzed 22 control (C) patients, 15 untreated Crohn’s disease (CD) patients, and 9 untreated ulcerative colitis (UC) patients from two cohorts. Samples obtained at the time of clinical remission from two of the treatment-naïve UC patients were also included into the analysis. UC-specific gene expression was interrogated in a subset of adjacent samples (5 C and 5 UC) using the Affymetrix GeneChip PrimeView Human Gene Expression Arrays. Only treatment-naïve UC separated from control. One-hundred-and-twenty genes with significant expression change in UC (> 2-fold, P < 0.05) were associated with differentially methylated regions (DMRs). Epigenetically associated gene expression changes (including gene expression changes in the IFITM1, ITGB2, S100A9, SLPI, SAA1, and STAT3 genes) were linked to colonic mucosal immune and defense responses. These findings underscore the relationship between epigenetic changes and inflammation in pediatric treatment-naïve UC and may have potential etiologic, diagnostic, and therapeutic relevance for IBD. 相似文献
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Detection of attachment of enterotoxigenic Escherichia coli (ETEC) to human small intestinal cells by enzyme immunoassay 总被引:1,自引:0,他引:1
Tracey L. Mynott Richard K.J. Luke David S. Chandler 《FEMS immunology and medical microbiology》1995,10(3-4):207-218
Abstract Simple immunoassays were developed to study the binding between enterocytes of the small intestine and other cell types, and enterotoxigenic Escherichia coli (ETEC). CFA/I or CFA/II pilus protein or CFA-positive E. coli bacteria were wells of microtitre plates and incubated with vesicles or crude mucus prepared from human brush border enterocytes. Binding of the cell preparations was detected by adding specific rabbit anti-brush border IgG followed by urease-labelled goat anti-rabbit IgG and urea substrate. The binding of purified CFA/I to human or rabbit small intestine, human oral epithelial cells or Caco-2 cells was detected with specific anti-CFA/I IgG. Both human brush border and mucus-derived preparations were able to attach to ETEC. The binding was CFA-specific and strong enough to withstand several washings. In contrast, CFA/I did not bind to small intestinal cells of non-human small intestinal origin, indicating that there may be important differences in affinity between receptors present on human small intestinal cells and cells of non-human small intestinal origin. Antibodies directed against human small intestinal and non-small intestinal cells did not cross-react with either preparation, indicating that receptors between these different cell sources are different. The EIA proved useful during the identification of a newly-recognised 15 kDa bacterial surface component of ETEC strain H10407P, which may function as a putative attachment factor. The EIAs developed in this study were easy to perform and multiple tests could be performed on small samples, including biopsy samples obtained during endoscopy. 相似文献
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AV. H. HEWOOD EDITAE 《Botanical journal of the Linnean Society. Linnean Society of London》1979,78(3):235-236
Following the publication of the last of the series of Flora Europaea Notulae, No. 20 in the Botanical Journal of the Linnean Society , 76: 297–384 (1978), a number of additions or alterations have been drawn to our attention. These are published in continuation. 相似文献
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