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Zusammenfassung Mit Untersuchungen über die Abhängigkeit des Zellvolumens vom osmotischen Wert und über die Konzentration der Zellinhaltsstoffe wird versucht, zur Kenntnis der Ursachen der Osmotoleranz bei Hefen beizutragen. In konzentrierten Lösungen verringern alle untersuchten Hefen ihr Volumen, die osmotoleranten Hefen aber weniger als die nichtosmotoleranten. Der Beginn einer meßbaren Volumenverringerung tritt bei osmotoleranten Hefen bei höheren Konzentrationen ein als bei nichtosmotoleranten. Eine Abhängigkeit der Zellgröße vom osmotischen Wert kann nur in einem bestimmten Konzentrationsbereich (zwischen 0,7–2% und 10% NaCl) festgestellt werden. Darunter fehlt eine osmotische Reaktion, und darüber bleibt die Zellgröße gleich. In Nährlösungen mit erhöhtem osmotischen Wert vermehren sich Zellen beider Typen in ihrer normalen Größe. Der osmotische Wert ihres Zellinhaltes ist annähernd gleich groß. Eine veränderte Struktur des Zellplasmas bzw. ein dadurch bedingter höherer Gehalt an fest gebundenem Hydratationswasser wird als Ursache der Osmotoleranz bei Hefen angesehen.
About the causes of osmotolerance in yeasts
Summary The question, if the yeast cell volume depends on the osmotic pressure and on the solutes of the cell, has been investigated. In concentrated solutions all yeasts investigated reduced their volume. A smaller reduction was found in osmotolerant yeasts. Osmotolerant yeasts begin to reduce their volume at higher osmotic pressures than non-osmotolerant ones. In concentrated nutrient media the cells of osmotolerant and non-osmotolerant yeasts grow in their normal size. The cell size depends only in the range between 0.7 to 2% and 10% NaCl approximately on the osmotic pressure of the surrounding medium. Beneath 2% there is no osmotic reaction and above 10% the cell size remains unchanged. The osmotic value in the cells of both yeast types is about the same. Causes of osmotolerance in yeasts may be a modified structure of cytoplasm and an increased content of bound water.


(Prof. Dr. S. Windisch)  相似文献   
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IntroductionSuccessful graft ingrowth following reconstruction of the anterior cruciate ligament is governed by complex biological processes at the tendon-bone interface. The aim of this study was to investigate in an in vitro study the effects of bone morphogenetic protein 7 (BMP-7) on tendon-bone integration.ResultsIn both models, positive effects of BMP-7 on ALP enzyme activity were observed (p<0.001). Additionally, similar results were noted for LDH activity and lactate concentration. BMP-7 stimulation led to a significant increase in OCN expression. Whereas the effects of BMP-7 on tendon monoculture peaked during an early phase of the experiment (p<0.001), the cocultures showed a maximal increase during the later stages (p<0.001). The histological analysis showed a stimulating effect of BMP-7 on extracellular matrix formation. Organized ossification zones and calcium carbonate-like structures were only observed in the BMP-stimulated cell cultures.DiscussionThis study showed the positive effects of BMP-7 on the biological process of tendon-bone integration in vitro. Histological signs of improved mineralization were paralleled by increased rates of osteoblast-specific protein levels in primary bovine osteoblasts and fibroblasts.ConclusionOur findings indicated a role for BMP-7 as an adjuvant therapeutic agent in the treatment of ligamentous injuries, and they emphasized the importance of the transdifferentiation process of tendinous fibroblasts at the tendon-bone interface.  相似文献   
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The conditions are outlined under which the body construction of annelids could have been transformed into that of arthropods. As an adaptation to a vagile life and an uptake of food by filtering particles from the sediment, the body was more and more flattened. Thus lateral protrusions, the subsequent pleurotergites, developed, and the parapodia were shifted to a more ventral position and could differentiate into the branched limbs typical for arthropods. This is the condition under which parts of the body wall were kept immobile, so that they could become sclerotized in the form of rigid plates.  相似文献   
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Cell lines derived from the small intestine that reflect authentic properties of the originating intestinal epithelium are of high value for studies on mucosal immunology and host microbial homeostasis. A novel immortalization procedure was applied to generate continuously proliferating cell lines from murine E19 embryonic small intestinal tissue. The obtained cell lines form a tight and polarized epithelial cell layer, display characteristic tight junction, microvilli and surface protein expression and generate increasing transepithelial electrical resistance during in vitro culture. Significant up-regulation of Cxcl2 and Cxcl5 chemokine expression upon exposure to defined microbial innate immune stimuli and endogenous cytokines is observed. Cell lines were also generated from a transgenic interferon reporter (Mx2-Luciferase) mouse, allowing reporter technology-based quantification of the cellular response to type I and III interferon. Thus, the newly created cell lines mimic properties of the natural epithelium and can be used for diverse studies including testing of the absorption of drug candidates. The reproducibility of the method to create such cell lines from wild type and transgenic mice provides a new tool to study molecular and cellular processes of the epithelial barrier.  相似文献   
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Experimental studies have identified a complex link between neurodegeneration, β-amyloid (Aβ) and calcium homeostasis. Here we asked whether early phase β-amyloid pathology in transgenic hAPPSL mice exaggerates the ischemic lesion and remote secondary pathology in the thalamus, and whether a non-selective calcium channel blocker reduces these pathologies. Transgenic hAPPSL (n = 33) and non-transgenic (n = 30) male mice (4–5 months) were subjected to unilateral cortical photothrombosis and treated with the non-selective calcium channel blocker bepridil (50 mg/kg, p.o., once a day) or vehicle for 28 days, starting administration 2 days after the operation. Animals were then perfused for histological analysis of infarct size, Aβ and calcium accumulation in the thalamus. Cortical photothrombosis resulted in a small infarct, which was associated with atypical Aβ and calcium accumulation in the ipsilateral thalamus. Transgenic mice had significantly smaller infarct volumes than non-transgenic littermates (P<0.05) and ischemia-induced rodent Aβ accumulation in the thalamus was lower in transgenic mice compared to non-transgenic mice (P<0.01). Bepridil decreased calcium load in the thalamus (P<0.01). The present data suggest less pronounced primary and secondary pathology in hAPPSL transgenic mice after ischemic cortical injury. Bepridil particularly decreased calcium pathology in the thalamus following ischemia.  相似文献   
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The universally valid genetic code is the final result of a multi-stage course of development. Degeneracy, as an important property of the genetic code, was possibly not yet present in the earliest code, first appearing at a later stage of development (Code III). Possibly this step in development is coupled with the presence of a total of four amino acid groups (L, I, E, F). Each group contains a specific number of amino acid (AL, AI, AE, AF). Amino acid groups: - (L) hydrophobic - (I) weakly hydrophobic or polar but uncharged - (E) hydrophilic, acidic - (F) hydrophilic, basic - (D) hydrophobic, aromatic (only in Code IV and Code M. This group is not considered in the calculations below.) In a subsequent stage of development the number of amino acids increases further. At the same time the code becomes more degenerate. The universal genetic code is characterized by three constants of being degenerate. Its immediate predecessor has linear degeneration with two constants. The mitochondrial code represents a transitional form between these two codes.  相似文献   
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