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1.
K. Das  H. M. Srivastava 《Genetica》1969,40(1):555-565
Observations on morphology, sterility and cytology of some interchangetrisomics obtained from the progeny of radiation induced interchangeheterozygotes in a 6-rowed barley (Hordeum vulgare L.) var. K12 are described. The different interchange trisomics show distinct phenotypic expression and have been classified as bushy, slender, robust, semi-erect and pseudonormal on the basis of their gross morphology, leaf characteristics, awn and spike lengths. All interchange trisomics show pollen and ovule sterility which varies between plants. Meiotic behaviour is described. The five different interchange trisomics appear to have different extra chromosomes.  相似文献   

2.
A flight of six major coral reef terraces, up to 700 m in altitude, occurs along the eastern and northern sides of Kabola Peninsula, Alor Island, Indonesia. Some radiometric dates have been obtained from unrecrystallized coral samples collected in growth position by three different methods (14C, 230Th/234U, ESR). This enabled the identification of the terraces corresponding to the Holocene and to oxygen-isotope stages 5c, 5e and 7. According to the present elevation of the dated terraces, a 1.0–1.2 mm/y mean rate of uplift can be discerned. Extrapolation of this trend to the whole sequence of terraces reveals a good correlation between the development of major terraces and interglacial or interstadial stages corresponding to astronomically calibrated oxygen isotope records, up to stage 13. The relatively rapid uplift rate in this region minimized the possibility of polycyclic sea-level stands at the same levels and contributed to the good preservation of some morphological reef features. Two superimposed marine notches are visible near the present shoreline, with retreat points at about 5.0 m and 8.6 m respectively above the present MLWST level. They can be interpreted as corresponding to a glacial interstadial (the upper notch) and to the Holocene sea-level peak (the lower one). As Holocene emergence has been less than what could be expected from a 1 mm/y rate of uplift, a major coseismic vertical displacement may occur in the future.This work is a contribution to the IGCP Project 367 Late Quaternary coastal records of rapid change and to the activities of the INQUA Commissions Neotectonics and Shorelines, the task group Paleoseismicity of the Late Holocene of the Inter-Union Commission on the Lithosphere, and the UNESCO-IUGS cooperative programme Earth Processes in Global Change (CLIP Pilot Project)  相似文献   

3.
Summary This work deals with the ability of phage 80 to provide defective mutants of with their missing functions. Functions Involved in Recombination. As shown by others, the Int mechanism of 80 cannot excise prophage . However, 80 efficiently excises recombinants from tandem dilysogens, using its Ter mechanism. Likewise, the nonspecific mechanism Red is interchangeable between 80 and . Maturation of DNA by 80. The Ter recombinants excised by 80 from tandem dilysogens are packaged into a 80 protein coat. This contrasts with the fact, already mentionned by Dove, that 80 is extremely inefficient for packaging phage superinfecting a -lysogen. The latter result is also found when the helper phage is a hybrid with the left arm of (80hy4 or 80hy41 — see Fig. 1). However, the maturation of the superinfecting is much more efficient if the 80hy used as a helper has the att-N region of (like 80hy1). Conversely a with the att-N region of 80 (hy6 — see Fig. 1) is packaged more efficiently by 80 or 80hy4 than by 80hy1. It is suggested that the maturation of chromosome superinfecting an immune cell requires a recombination with the helper phage. Vegetative Functions. Among the replicative functoons O and P, the latter only can be supplied by 80. That N mutants are efficiently helped by 80 does not tell that 80 provides the defective with an active N product; the chromosomes are simply packaged into a 80 coat. This shows that 80 is unable to switch on the late genes of . That neither 80 nor any of the 80hy tested can provide an active N product is shown in a more direct way by their complete failure to help N -r14; this phage carries a polar mutation which makes the expression of genes O and P entirely N-dependant. The maturation of a N - by 80 contrasts with the fact that mutants affected in late genes (A, F or H) are not efficiently helped by 80. This suggests that the products coded by these genes are not interchangeable between 80 and , and that packaging of DNA into 80 coats is possible but inhibited when late proteins are present in the cell. Activation of the Late Genes. Among the im 80 h + hybrids tested, only 80hy41 is able to switch on the late genes of a N defective mutant. This hybrid differs from the other hybrids studied here, by the fact that it has the Q-S-R region of (see Fig. 1). The results are consistant with the view that the product of Q gene is sufficient for activating the late genes of a DNA. N would thus control the expression of late genes only indirectly by controlling the expression of gene Q (Couturier & Dambly have independantly reached the same conclusion, 1970). Furthermore the failure of 80 and of the 80hy1 and 80hy4 to activate the late genes of would imply that these phages are unable to provide an Q product active on the chromosome Reciprocally, switches on the late genes of prophage 80hy41, but not of prophages 80hy1 and 80hy4. This suggests that the initiation of late genes expression takes place at a main specific site located in the Q-S-R region of the chromosome. The expression of the late genes would thus be sequential, and proceed through the left arm only when steaky ends cohere. Similar conclusions were reached independantly by Toussaint (1969) and by Herskowitz and Signer (1970).

Ce travail a été réalisé dans le cadre du contrat d'association Euratom-U. L. B. 007-61-10 ABIB et avec l'aide du Fonds de la Recherche Fondamentale Collective.  相似文献   

4.
Occupational exposure to beryllium (Be) and Be compounds occurs in a wide range of industrial processes. A large number of workers are potentially exposed to this metal during manufacturing and processing, so there is a concern regarding the potential carcinogenic hazard of Be. Studies were performed to determine the carcinogenic potential of beryllium sulfate (BeSO4) in cultured mammalian cells. BALB/c3T3 cells were treated with varying concentrations of BeSO4 for 72 h and the transformation frequency was determined after 4 weeks of culturing. Concentrations from 50–200 g BeSO4/ml, caused a concentrationdependent increase (9–41 fold) in transformation frequency. Nontransformed BALB/c3T3 cells and cells from transformed foci induced by BeSO4 were injected into both axillary regions of nude mice. All ten Beinduced transformed cell lines injected into nude mice produced fibrosarcomas within 50 days after cell injection. No tumors were found in nude mice receiving nontransformed BALB/c3T3 cells 90 days postinjection. Gene amplification was investigated in Kras, cmyc, cfos, cjun, csis, erbB2 and p53 using differential PCR while random amplified polymorphic DNA fingerprinting was employed to detect genomic instability. Gene amplification was found in Kras and cjun, however no change in gene expression or protein level was observed in any of the genes by Western blotting. Five of the 10 transformed cell lines showed genetic instability using different random primers. In conclusion, these results indicate that BeSO4 is capable of inducing morphological cell transformation in mammalian cells and that transformed cells induced by BeSO4 are potentially tumorigenic. Also, cell transformation induced by BeSO4 may be attributed, in part, to the gene amplification of Kras and cjun and some BeSO4induced transformed cells possess neoplastic potential resulting from genomic instability.  相似文献   

5.
Summary Chorionic villi from first trimester and term human placentas have been incubated in vitro and shown to release the lysosomal enzymes, -hexosaminidase, -glucosidase and -gluctlronidase. There was negligible release of the cytoplasmic enzyme, lactate dehydrogenase, under the same conditions. The first trimester villi released proportionally more of their lysosomal enzyme content than did the term villi. Extracellular levels of -hexosaminidase were raised and those of -glucosidase and, -glucuronidase were lowered when tissue was incubated with 1 M colchicine, suggesting that microtubules are involved in the control of lysosomal enzyme release from placental villi.  相似文献   

6.
180 rainbow trouts (Salmo gairdneriRich.), aged from 1 to 3 years, were examined for fluctuations, caused by age and season, by means of colour index (CI), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC).CI and MCH behave similarly. Both are increasing until the 2nd year and stay relatively constant thereafter. If the gender is not considered — there are no significant differences in the values of males and females — the CI increases from 1,4 in the first year over 1,6 to 1,7 in the age of 3 years, and the MCH increases from 44,4 over 52,6 , 56,8 , 58,1 to 55,5 .A seasonal periodicity of both indices could not be indicated on not-matured animals (F2) which were two summers of age. Only, the january values appeared increased — CI: 2, MCH: 68,3 — otherwise the CI varies between 1,8 and 1,7 and the MCH between 53,3 and 59,1 .The MCHC-values of the age groups examined vary between 24,4% and 27,3%. The values of the yearlings form an exception (19,8%). These values certainly are inexact and too low because of the small number of individuals checked (3).

Mit finanzieller Unterstützung durch die DFG.Institut für Siedlungswasserbau und Wassergütewirtschaft der Universitat Stuttgart Fischtoxikologische Arbeitsgruppe  相似文献   

7.
Summary The appearance of and subunits of skeletal tropomyosin in early myogenesis was studied histochemically using monoclonal antibody to tropomyosin and affinity-purified polyclonal antibody to tropomyosin. In muscle cells, in both somites and limb buds, the and subunits are simultaneously expressed and first appear in the somites at the 30–36 somites. The relatively greater amount of than tropomyosin found in early myogenesis is thus likely to result from a higher rate of tropomyosin synthesis.  相似文献   

8.
Single-chain Fv molecules in monovalent (sFv) and divalent [(sFv')2] forms exhibit highly specific tumor targeting in mice as a result of their small size and rapid systemic clearance. As a consequence, there is a rapid reversal of the sFv blood/tumor gradient, resulting in diminished retention of sFv species in tumors. In this report we investigate two distinct strategies, dose escalation and repetitive intravenous (i.v.) dosing, aiming to increase the absolute selective retention of radiolabeled anti-c-erbB-2125I-741F8 (sFv')2 in c-erbB-2-overexpressing SK-OV-3 tumors in mice with severe combined immunodeficiency (SCID). A doseescalation strategy was applied to single i.v. injections of125I-741F8 (sFv')2. Doses from 50 g to 1000 g were administered without a significant decrease in tumor targeting or specificity. High doses resulted in large increases in the absolute retention of125I-741F8 (sFv')2. For example, raising the administered dose from 50 g to 1000 g increased the tumor retention 24 h after injection from 0.46 g/g to 9.5 g/g, and resulted in a net increase of greater than 9 /g. Over the same dose range, the liver retention rose from 0.06 g/g to 1 g/g, and resulted in a net increase of less than 1 g/g. The retention of 9.5 g/g in tumor 24 h fllowing the 1000-g dose of (sFv')2 was comparable to that seen 24 h after a 50-g dose of125I-741F8 IgG, indicating that the use of large doses of (sFv')2 may partially offset their rapid clearance. When two doses were administered by i.v. injection 24 h apart, the specificity of delivery to tumor observed after the first dose was maintained following the second injection. Tumor retention of125I-741F8 (sFv')2 was 0.32 g/g at 24 h and 0.22 g/g at 48 h following a single injection of 20 g/g, while 0.04 g/ml and 0.03 g/ml were retained in blood at the same assay times. After a second 20-g injection at the 24-h assay time, tumor retention increased to 0.49 g/g, and blood retention was 0.06 g/ml, at the 48-h point. These results suggest that multiple high-dose administrations of radiolabeled 741F8 (sFv')2 may lead to the selective tumor localization of therapeutic radiation doses.Supported by National Cancer Institute (NCI) National Cooperative Drug Discovery Group grant U01 CA51880, CA06927, an appropriation from the Commonwealth of Pennsylvania, and the Bernard A. and Rebecca S. Bernard Foundation  相似文献   

9.
Rapid multiplication of axillary meristems and direct shoot development occurred from nodal explants of mature Eucalyptus tereticornis Sm. with 5.3 M NAA, 1.1 M IAA and 4.4 M BA in Murashige-Skoog medium. Repeated subcultures of the second generation shoot cultures into low cytokinin-auxin containing media (0.44–0.88 M BA+0.1 M NAA) yielded axillary microshoots in large numbers. Half-strength MS liquid medium with 4.9 M IBA, 5.5 M IAA and 5.3 M NAA for four days, half-strength semi-solid hormonefree MS medium with charcoal, and MS liquid medium without charcoal and hormones, in sequence, induced rooting of shoots in the dark. This system is suitable for the mass propagation of this difficult-to-root eucalypt.Abbreviations BA 6-benzyladenine - IAA indole-3-acetic acid - IBA -indole-3-butyric acid - 2-iP isopentyl adenine - Kn kinetin - MS Murashige-Skoog - NAA -naphthalene acetic acid - PVP polyvinylpyrrolidone  相似文献   

10.
Temperature dependencies were established for the egg-to-mummy and mummy-to-adult phases, for mummy mortality, and for parasitism of Aphidius ervi Haliday, Aphidius rhopalosiphi De Stefani-Perez, and Praon volucre (Haliday) (Hymenoptera, Aphidiidae), three parasitoids of Sitobion avenae (Fabricius) (Homoptera, Aphididae), at 8°C, 12°C, 16°C, 20°C, and 25°C on winter wheat (cv. Haven). A physiological model described temperature-dependent development over the full temperature range, whereas a linear model was fitted for data above 8°C and used to estimate the lower temperature thresholds and day-degrees (° D) required for development. The thresholds for A. ervi were 2.2°C for egg-mummy development and 6.6°C for mummy-adult development, those for A. rhopalosiphi were 4.5°C and 7.2°C, and those for P. volucre were 3.8°C and 5.5°C. The time to develop into mummies and adults differed significantly between the three species: A. ervi development into mummies required an average of 159 ° D, while development into adults took an average of 73 ° D. The corresponding average times required for A. rhopalosiphi and P. volucre to develop mummies were 124° D and 126° D, while their development into adults required an average of 70° D and 150° D, respectively. Mummy mortality was 25–35% at 8°C and less at the higher temperatures tested, but began to increase again at 25°C, showing a quadratic relationship between mortality and temperature. Parasitization was very low or, in the case of P. volucre, absent up to 12°C and thereafter increased with increasing temperature. The relationship between parasitization, recorded as percent aphids mummified, and temperature was linear at the temperatures tested and depended on species. A. ervisuperparasitized 11.1% aphids at 20°C and 16.6% aphids at 25°C, whereas superparasitism was low in A. rhopalosiphi and absent in P. volucre. From 16°C to 25°C the P. volucre sex ratio increased. For A. ervi and A. rhopalosiphi there was no trend with temperature, but at 20°C and 25°C it was close to even. Field data for 1996 and 1997 allowed for a comparison of actual and expected emergence of overwintering mummies. In both years, parasitoids were predicted to have emerged from overwintering mummies well in advance of the onset of aphid infestation, and more than a month earlier than the first parasitized aphids were found in winter wheat. Observations from trap plants in other crops supported the predictions of the models. Other factors that can affect biological control by cereal aphid parasitoids are discussed.  相似文献   

11.
Influenza A and Sendai viruses bind toneolacto-series gangliosides isolated from human granulocytes. Differences in receptor specificity of influenza viruses A/PR/8/34 (H1N1), A/X-31 (H3N2), and parainfluenza Sendai virus (HNF1, Z-strain) were determined by two direct solid phase binding assays: the overlay technique, which combines high-resolution in the separation of gangliosides on thin-layer chromatograms with direct binding; and the microwell adsorption assay as a convenient binding assay which is performed in microtitre wells to estimate the avidity of binding to an isolated ganglioside. Both methods were applied for comparative binding studies. Viruses were found to exhibit specificity for oligosaccharides and sialic acids as well as for chain length of the neutral carbohydrate backbone, whereas differing fatty acids (C24:1 and C16:0) in the ceramide portion had no impact on virus adsorption. Terminal sialyloligosaccharides Neu5Ac2-3Gal1-4Glc-R of GM3, and Neu5Ac2-3Gal1-4GlcNAc-R as well as Neu5Ac2-6Gal1-4GlcNAc-R ofneolacto-series gangliosides with nLcOse4Cer and nLcOse6Cer backbone, exhibited significant specific receptor activity towards the different viruses. To compare the data revealed from both test systems, values of virus binding were ascertained by a non-parametric statistical approach based on rank correlation. The rank correlation coefficientr s was calculated according to Spearman from each virus binding towards GM3, IV3Neu5Ac-nLcOse4Cer, IV6Neu5Ac-nLcOse4Cer and VI3Neu5Ac-nLcOse6SCer. The rank correlation coefficients 0.74, 0.95 and 0.92, which were determined for A/PR/8/34 (H1N1), A/X-31 (H3N2) and Sendai virus (HNF1, Z-strain), respectively, indicated that both assays generate highly correlated experimental data. Based on these results, analyses of virus binding on thin-layer chromatograms as well as in microwells were found equivalent tools for ganglioside receptor studies. Abbreviations: BSA, bovine serum albumin; GSL(s), glycosphingolipids; HPTLC, high performance thin-layer chromatography; PBS, phosphate buffered saline; Neu5Ac,N-acetylneuraminic acid [35];r s = rank correlation coefficient according to Spearman. The designation of the glycosphingolipids follows the IUPAC-IUB recommendations [36]. LacCer or lactosylceramide, Gal1-4Glc1-1Cer; lacto-N-neotetraosylceramide or nLcOse4Cer, Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; lacto-N-norhexaosylceramide or nLcOse6Cer, Gal1-4GlcNAc1-3Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; GM3 (according to Svennerholm [37]) or II3Neu5AcLacCer.  相似文献   

12.
A (13, 14)--glucan 4-glucanohydrolase [(13, 14)--glucanase, EC 3.2.1.73] was purified to homogeneity from extracts of germinated wheat grain. The enzyme, which was identified as an endohydrolase on the basis of oligosaccharide products released from a (13, 14)--glucan substrate, has an apparent pI of 8.2 and an apparent molecular mass of 30 kDa. Western blot analyses with specific monoclonal antibodies indicated that the enzyme is related to (13, 14)--glucanase isoenzyme EI from barley. The complete primary structure of the wheat (13, 14)--glucanase has been deduced from nucleotide sequence analysis of cDNAs isolated from a library prepared using poly(A)+ RNA from gibberellic acid-treated wheat aleurone layers. One cDNA, designated LW2, is 1426 nucleotide pairs in length and encodes a 306 amino acid enzyme, together with a NH2-terminal signal peptide of 28 amino acid residues. The mature polypeptide encoded by this cDNA has a molecular mass of 32085 and a predicted pI of 8.1. The other cDNA, designated LW1, carries a 109 nucleotide pair sequence at its 5 end that is characteristic of plant introns and therefore appears to have been synthesized from an incompletely processed mRNA. Comparison of the coding and 3-untranslated regions of the two cDNAs reveals 31 nucleotide substitutions, but none of these result in amino acid substitutions. Thus, the cDNAs encode enzymes with identical primary structures, but their corresponding mRNAs may have originated from homeologous chromosomes in the hexaploid wheat genome.  相似文献   

13.
Zusammenfassung Die Fortpflanzungsperiode der Palmtaube (Streptopelia s. senegalensis L.) fängt in Diyarbakir/Türkei (37°55N/40°12E) schon Anfang Februar an und kann bis Mitte November dauern. In diesem Zeitraum kann ein Paar bis zu sieben Bruten beginnen (Tab. 1). Nach der Paarbildung fangen die Kopulationen an, die vor allem in der Woche vor der Eiablage stark zunehmen. Während des Brütens und der ersten Woche der Jungenaufzucht sind sie dagegen nicht zu beobachten. Sie werden vom im allgemeinen mit sog. Flügeltippen bzw. Scheinputzen eingeleitet. Nach der Begattung paradiert das um das , das auf der Stelle verharrt. Vor dem Tretakt fällt das dagegen in infantiles Verhalten und bettelt unter Flügelzittern den Partner um Futter an. Es bekommt auch tatsächlich Futter. Die Palmtauben sind zumindest für eine Fortpflanzungssaison monogam. U. a. spielen wechselseitige Gefiederpflege und Anschlußbruten sowie die Fütterung des durch das eine wichtige Rolle für das Zusammenleben und -bleiben der Partner. Der Nistplatz wird vom gezeigt, aber vom gewählt. Das Nistmaterial wird vom eingetragen und im allgemeinen vom alleine in das Nest eingefügt. Nur während des Brutwechsels bringt auch das hin und wieder Nistmaterial, das aber wahrscheinlich nur für den Partner, nicht für das Nest dient. In den späteren Phasen des Brütens gilt dies wahrscheinlich auch für das . 1–4 Tage nach dem Nestbaubeginn wird gegen Abend das erste Ei gelegt, womit auch das Brüten anfängt. Das zweite Ei folgt dann rund 38 Stunden später.
On the reproductive behaviour of the Laughing Dove (Streptopelia senegalensis): pair-formation to egg-laying
Summary In Diyarbakr/Turkey, the reproductive season of the Laughing Dove begins in early February and lasts til mid November. One pair may start with breeding up to seven times a year. The frequency of copulations which could be observed only after pair formation increased considerably in the week before incubation starts. During incubation and during the first week of the nestling period no copulations could be observed. Usually copulations are initiated by the male pecking behind its folded wings (displacement-preening). Before mating, the female turns into infantile behaviour begging food from its partner by wing-twitching. Food is then delivered by the male. After mating the female parades around the male which stays motionless. Paired birds stay together at least during one reproductive season. Reinforcement of the pair bond will be achieved by mutual preening, courtship feeding of the female by the male, and successive broods. The male indicates the nest site which is successively chosen by the female. The nest material is brought by the male and usually placed by the female at the nest site. Only during change-overs the female sometimes brings nesting material, too. However, this material probably is for the partner, not actually for the nest. The same may be true for similar behaviour of the male in late stages of incubation. One to four days after nest building has started the first egg is laid, mostly in late afternoon. Incubation starts with the first egg; the second egg is laid about 38 hours later.
  相似文献   

14.
Idioms of distress refers to the popular expression of emotional tension that arises in the relationship between sickness and kinship. By reference to case studies and discussions among the Polynesian people of Tonga, the author shows where such tension arises and how it influences the sickness process. Sickness is necessarily a collective phenomenon which can best be understood not simply as a clinical event, but as an experience that is part of the experience of family. Various ways of expressing distress as a reflexive encounter between personal and cultural meaning systems are reviewed, as are several new concepts such as doing sickness as kinship, and turning in the process of decision making in the kinship management of sickness. The explanatory models of sickness in Tonga are shown to encompass culturally sanctioned expressions of distress as part of the adaptive coping mechanisms in that society. Distress frequently emerges in somatic form, as a number of studies have shown. However, the author emphasizes the kinship meaning of sickness, kinship management and sickness therapy, the adaptive process of idiomatic expressions of distress, which are expanded here and offered as potential avenues for elaboration in other cultural milieu. Two aspects of the notion idioms of distress are noted, and the phenomenon is understood as a process which acts as a prime mover in social change.  相似文献   

15.
InEchinops the flowers are surrounded by several scales and initiated in an acropetal and spiral succession on a cone-like inflorescence axis (Figs. 1–6). The floral organs originate in the following sequence: petals—stamens—carpels—pappus. The petals arise from a meristematic rim and therefore are already interconnected when they arise as primordia. This sympetalous zone remains rather inconspicuous for a long period, but eventually, the elongated corolla tube is formed through intercalary growth in a ring zone. Thereby, the stamens are moved upwards and form ledges on the corolla tube (Fig. 34). In the inferior ovary the usual zones of the typical angiospermous gynoecium can be distinguished, namely a synascidiate, symplicate and hemisymplicate zone. The ovule is borne on carpellary tissue.
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16.
This paper addresses the visual culture of late-19th-century experimental physiology. Taking the case of Johann Nepomuk Czermak (1828–1873) as a key example, it argues that images played a crucial role in acquiring experimental physiological skills. Czermak, Emil Du Bois-Reymond (1818–1896) and other late-19th-century physiologists sought to present the achievements and perspective of their discipline by way of immediate visual perception (unmittelbare Anschauung). However, the images they produced and presented for this purpose were strongly mediated. By means of specifically designed instruments, such as the cardioscope, the contraction telegraph, and the frog pistol, and of specifically constructed rooms, so-called spectatoriums, physiologists trained and controlled the perception of their students before allowing them to conduct experiments on their own. Studying the material culture of physiological image production reveals that technological resources such as telegraphy, photography, and even railways contributed to making physiological facts anschaulich. At the same time, it shows that the more traditional image techniques of anatomy played an important role in physiological lecture halls, especially when it came to displaying the details of vivisection experiments to the public. Thus, the images of late 19th century physiology stood half-way between machines and organisms, between books and instruments.This paper was written in the context of ten project, The Experimentalizaiton of Life: Configurations of Life Sciences, Art, and Technology (1830–1930). The project is based at the Max Planck Institute for the History of Science (Dept. III: Hans-Jörg Rheinberger), Berlin, and receives funding from the Volkswagen Stiftung, Hannover. A first draft of this paper was presented, accompanied by Sven Dierig on the Virtual Laboratory, at the Institute of Theater Sciences, Free university Berlin, in December 2000. I would like to thank Sven Dierig and the other members of the project as well as Nick Hopwood, Skúli Sigurdsson and the anonymous referees and the editors of this journal for their helpful comments on an earlier version of this paper. Thanks also to Laurie McLaughlin and Nancy Anderson for helping me with the English version of the text.  相似文献   

17.
The magnitude of the proton motive force (p) and its constituents, the electrical () and chemical potential (-ZpH), were established for chemostat cultures of a protease-producing, relaxed (rel ) variant and a not protease-producing, stringent (rel +) variant of an industrial strain ofBacillus licheniformis (respectively referred to as the A- and the B-type). For both types, an inverse relation of p with the specific growth rate was found. The calculated intracellular pH (pHin) was not constant but inversely related to . This change in pHin might be related to regulatory functions of metabolism but a regulatory role for pHin itself could not be envisaged. Measurement of the adenylate energy charge (EC) showed a direct relation with for glucose-limited chemostat cultures; in nitrogen-limited chemostat cultures, the EC showed an approximately constant value at low and an increased value at higher . For both limitations, the ATP/ADP ratio was directly related to .The phosphorylation potential (G'p) was invariant with . From the values for G'p and p, a variable H+/ATP-stoichiometry was inferred: H+/ATP=1.83+0.52µ, so that at a given H+/O-ratio of four (4), the apparent P/O-ratio (inferred from regression analysis) showed a decline of 2.16 to 1.87 for =0 to max (we discuss how more than half of this decline will be independent of any change in internal cell-volume). We propose that the constancy of G'p and the decrease in the efficiency of energy-conservation (P/O-value) with increasing are a way in which the cells try to cope with an apparent less than perfect coordination between anabolism and catabolism to keep up the highest possible with a minimum loss of growth-efficiency. Protease production in nitrogen-limited cultures as compared to glucose-limited cultures, and the difference between the A- and B-type, could not be explained by a different energy-status of the cells.Abbreviations CCCP carbonylcyanide-p-trichloromethoxyphenylhydrazone - DW dry weight of biomass - F Faraday's constant, 96.6 J/(mV × mol) - Fo chemostat outflow-rate (ml/h) - FCCP carbonylcyanide-p-trifluoromethoxyphenylhydrazone - G'p phosphorylation potential, the Gibbs energy change for ATP-synthesis from ADP and Pi - G'0p standard Gibbs energy change at specified conditions - H+/ATP number of protons translocated through - ATP synthase in synthesis of one ATP - H+/O protons translocated during transfer of 2 electrons from substrate to oxygen - specific growth rate (1/h) - H+ transmembrane electrochemical proton potential, J/mol - Mb molar weight (147.6 g/mol) of bacteria with general cell formula C6.0H10.8O3.0N1.2 - pHout,in extracellular, intracellular pH - Pi (intracellular) inorganic phosphate - p proton motive force, mV - pH transmembrane pH-difference - transmembrane electrical potential, mV - P/O number of ADP phosphorylated to ATP upon reduction of one O2– to H2O by two electrons transferred through the electron transfer chain - P/O (H+/O) × (H+/ATP)–1 - P/OF, P/ON P/O with the two electrons donated by resp. (NADH + H+) and FADH - q specific rate of consumption or production (mol/g DW × h) - rel +,rel stringent, relaxed genotype - R universal gas constant, 8.36 J/(mol × degree) - T absolute temperature - TPMP+ triphenylmethylphosphonium ion - TPP+ tetraphenyl phosphonium ion - Y growth yield, g DW/mol - Z conversion constant=61.8 mV for 310 K (37 °C) - ZpH transmembrane proton potential or chemical potential, mV  相似文献   

18.
We have isolated an unusual T cell receptor chain cDNA clone (7.1) from a library made from RNA derived from adult thymus of C57BL/Ka mice. This cDNA clone corresponds to the appropriately processed C1 constant region exons preceded by 1.5 kb of J-C1 intron. The 7.1 coding region is extremely homologous to the C1 gene of BALB/c mice, differing at the protein level by a single deletion (alanine 139) and a single substitution. This latter change eliminates the sole N-linked sugar attachment site, providing a basis for strain-specific glycosylation patterns. The J-C1 intronic region contains two DNA segments (termed J1 and J2) that are highly reminiscent of joining (J) segments; both have potentially functional recombination and donor splice sequences flanking an open reading frame. Northern analysis suggests that 7.1 may be derived from a large, variable region-containing precursor.  相似文献   

19.
Poly--hydroxyalkanoate (PHA) from crotonate-grown cultures of Syntrophomonas wolfei contained only the d-isomer of -hydroxybutyrate. The PHA from cultures grown with trans-2-pentenoate or one of several hexenoates as the substrate also contained small amounts (5%) of -hydroxypentanoate or -hydroxyhexanoate, respectively. Thus, some PHA was synthesized without cleavage of the carbon skeleton of the substrate, but the predominant route for PHA synthesis was by the condensation and subsequent reduction of acetyl-coenzyme A (CoA). The ratio of the -hydroxypentanoate to the -hydroxybutyrate in PHA in pentenoate-grown cultures increased immediately after inoculation and then decreased as the amount of the -hydroxybutyrate in PHA increased. The amount of -hydroxypentanoate in the PHA did not markedly change throughout the remainder of growth. These data indicated that the unbroken carbon-chain was used for polymer production only in the early stages of growth and, later, polymer synthesis occurred by the condensation and reduction of acetyl-CoA molecules.  相似文献   

20.
Ray  I.  Chauhan  A.  Wisniewski  H. M.  Wegiel  J.  Kim  K. S.  Chauhan  V. P. S. 《Neurochemical research》1998,23(10):1277-1282
Amyloid beta-protein (A), in its soluble form, is known to bind several circulatory proteins such as apolipoprotein (apo) E, apo J and transthyretin. However, the binding of A to intracellular proteins has not been studied. We have developed an overlay assay to study A binding to intracellular brain proteins. The supernatants from both rat and human brains were found to contain several proteins that bind to A 1–40 and A 1–42. No major difference was observed in the A binding-proteins from brain supernatants of patients with Alzheimer's disease and normal age-matched controls. Binding studies using shorter amyloid beta-peptides and competitive overlay assays showed that the binding site of A to brain proteins resides between 12–28 amino acid sequence of A. The presence of several intracellular A-binding (AB) proteins suggests that these proteins may either protect A from its fibrillization or alternatively promote A polymerization. Identification of these proteins and their binding affinities for A are needed to assess their potential role in the pathogenesis of Alzheimer's disease.  相似文献   

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