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11.
James E. Fleming Paula S. Melnikoff Klaus G. Bensch 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,802(2):340-345
Several hundred proteins have been resolved on two-dimensional gels of extracts of [35S]methionine-labeled adult Drosophila melanogaster. 27 of these polypeptides disappear from the gel pattern after feeding the K+ ionophore nonactin. These proteins have been identified as mitochondrial, since the two-dimensional gel pattern of extracts of isolated mitochondria correlates well with the pattern of the proteins missing from that of nonactin-treated flies. Nine new proteins also appear on the two-dimensional gels of the extracts from the nonactin-treated flies. Apparently, these nine proteins are precursors of the mature mitochondrial forms. These particular data support the concept that processing of many of the cytoplasmically synthesized mitochondrial proteins requires a specific membrane potential, and that some of these proteins are modified intramitochondrially. However, using [35S]methionine incorporation techniques, not all labeled polypeptides disappear from mitochondria during such treatment. Feeding similarly radiolabeled flies with chloramphenicol, an inhibitor of mitochondrial protein synthesis, results in the disappearance of only one protein from the gel pattern with the concurrent appearance of a ‘new’ high-molecular-weight polypeptide. Collectively, these data show that a specific group of [35S]methionine-labeled mitochondrial proteins can be identified by selective inhibition of mitochondrial function in whole cell protein maps of adult D. melanogaster. 相似文献
12.
The impact of ticks on pheasant territoriality 总被引:1,自引:0,他引:1
Pheasants are competent reservoir hosts for the Lyme disease spirochaete, Borrelia burgdorferi s.l., and carry large, but highly over-dispersed, infestations of the vector ticks, Ixodes ricinus . The effects of experimental reduction of tick infestation levels on the survival and territorial behaviour of male pheasants were studied. Over three years in two woodlands in southern England, birds were marked individually and half were fitted with a slow-release acaricide, which substantially reduced their tick burdens from March to August. Acaricide treatment affected reproductive success but had no discernible impact on the survival rates of male pheasants. The degree of wattle inflation by males, an indicator of territorial status and a correlate of harem acquisition, was significantly greater among treated males. In each year, a significantly higher proportion of treated (overall 44%) than control (22%) males acquired harems. Males that acquired females ranged over small areas on field edges. By contrast, those with no females ranged more widely in woods and the adjoining fields, increasing their exposure to questing ticks. The relative contribution of such roving males to tick-borne pathogen transmission may thus increase. 相似文献
13.
Wolfgang Witt Peter Hampel Klaus Böcker Angelika Mertsching 《Archives of microbiology》1989,151(2):154-158
Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 M. The inhibition by nucleotides in low concentrations is enhanced by divalent cations. 相似文献
14.
Summary In a geographically wide distribution the life cycles of different populations of the cabbage moth Mamestra brossicae are adapted to a remarkable diversity of climatic conditions. This is undoubtedly a proof of its success in adaptation. Some populations living in regions characterized by a drought period interrupting the growth season are capable of distinguishing between one critical day length signalling the onset of the drought period and another signalling the end of the growth season. This study, therefore, is primarily concerned with the geographical patterns in the variability of the adaptional responses of populations exposed to environmental conditions requiring different strategies and tactics in, synchronizing individual, life cycles. It is also a contribution to our understanding of evolutionary mechanisms maintaining median responses to photoperiodically inductive day lengths in geographically different populations. The populations investigated originated from regions differing in predictability of the incidence, onset and duration of a drought period: Freiburg (48.0°N, Southern Germany), Avignon (44.0°N, Southern France), and Argelès (42.5°N, Southern France). Geographical variation with respect to both onset and duration of a drought period consequently results in clinal variation of the variability of innate day length thresholds triggering aestival dormancy and of innate duration of aestivation. In this paper we considered the influence of geographically changing temperatures on aestival dormancy induction. Even in southern populations of M. brassicae a temperature dependent switch off-mechanism exists which prevents aestival dormancy under certain environmental conditions. The effective temperatures vary geographically, too. What the geographical patterns in adaptive responses really are, is discussed.This research was supported by the Deutsche Forschungsgemeinschaft (Sa 259/3-1) 相似文献
15.
Galactinol: raffinose-6-galactosyltransferase (EC 2.4.1.67), a stachyose synthase, was extracted from mature leaves of Cucumis melo cv. Ranjadew and was purified to homogeneity by (NH4)2SO4 precipitation, ion-exchange chromatography, gel-filtration and non-denaturing polyacrylamide gel electrophoresis. A specific activity of 516 kat · mg-1 and a 160-fold purification was achieved. The pH optimum of the enzyme reaction was found to be 6.8 in sodium-phosphate buffer, and the temperature optimum 32° C. The purified enzyme was very sensitive towards SH-poisons but its reaction was hardly affected by changes in the ion composition of the assay medium. The two-substrate enzyme was specific for galactinol and raffmose; uridine-diphosphate galactose and p-nitrophenyl--d-galactoside as well as melibiose were not accepted by the purified enzyme. Stachyose synthesis was competitively inhibited by concentrations >4 mM raffinose as well as 2.5 mM galactinol. The K
m values determined under non-saturating conditions were 3.3 mM for raffinose and 7.7 mM for galactinol. Myoinositol was a strong competitive inhibitor with a K
i of 1.8mM. Galactinol was hydrolyzed in the absence of raffinose with a K
m of 0.8 mM. The pure enzyme is a protein with a molecular weight of at least 95 kDa and an isoelectric point of 5.1. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the presence of two subunits of 45 and 50 kDa. Polyclonal antibodies from rabbit were obtained which were specific for the native enzyme but cross-reacted with other proteins separated under denaturing conditions.Abbreviations DEAE
diethylaminoethyl
- DTT
dithiothreitol
- FPLC
fast protein liquid chromatography
- HPLC
high-performance liquid chromatography
- PAGE
polyacrylamide gel electrophoresis
- SDS
sodium dodecyl sulfate
This work was supported by Deutsche Forschungsgemeinschaft. The gift of galactinol by Dr. T. Schweizer (Nestlé, Switzerland) is gratefully acknowledged. 相似文献
16.
Cell-free extracts from leaves of Rhus typhina L. (sumach) were found to transfer the 1-O-galloyl moiety of l,6-di-O-galloyl-β-d-glucose to the 2-position of the same compound, yielding 1,2,6-tri-O-galloyl-β-d-glucose and leaving 6-O-galloylglucose as the deacylated by-product. The enzyme catalyzing this ‘disproportionation’ was purified almost 1700-fold. It had a molecular weight of approx. 56 000, a K m value of 11.5 mM, was stable between pH 4.5 and 6.5, and most active at pH 5.9 and 40° C. The systematic name “1,6-di-O-galloyl-glucose: 1,6-di-O-galloylglucose 2-O-galloyltransferase” (EC 2.3.1.) was proposed for this new enzyme whose detection provided evidence that, in addition to β-glucogallin (1-O-galloyl-β-d-glucose), higher substituted glucose esters also have the potential to serve as acyl donors in the biosynthesis of gallotannins. 相似文献
17.
Katrin Kausch Clemens R. Müller Tiemo Grimm Kenneth Ricker Marcella Rietschel Sabine Rudnik-Schöneborn Klaus Zerres 《Human genetics》1991,86(3):317-318
Summary Two recent articles have reported the linkage of a gene for recessive spinal muscular atrophy (SMA) on the chromosome region 5q11.2–13.3. Our data show no linkage of the dominantly inherited forms of SMA to this chromosome region. 相似文献
18.
B lymphocyte receptors and polyphosphoinositide degradation 总被引:43,自引:0,他引:43
Resting B lymphocytes can be activated and induced to proliferate by antibodies against their antigen receptors (anti-lg). We demonstrate an early increase in the level of [3H]inositol trisphosphate in [3H]inositol-labeled murine B cells, which suggests breakdown of phosphatidylinositol bisphosphate by phospholipase C. In line with this, the level of [3H]1,2-diacylglycerol was also elevated after incubation of [3H]arachidonic-acid-labeled B cells with anti-Ig. Anti-lg also caused a rapid increase in the level of cytosolic Ca2+ in B cells. In contrast, two other polyclonal B cell activators, lipopolysaccharide and phorbol myristate acetate, failed to induce any of these effects. Our results suggest that anti-lg may induce B cell growth via phosphoinositide degradation and Ca2+ mobilization, and that phorbol myristate acetate, and possibly lipopolysaccharide, bypass these initial events. 相似文献
19.
Primary production data from the south-eastern Weddell Sea 总被引:2,自引:2,他引:0
Klaus von Bröckel 《Polar Biology》1985,4(2):75-80
Summary Phytoplankton production for three size classes (<20 m, 20–100 m, >100 m), total primary production and qualitative composition of phytoplankton populations were recorded from 18 stations in the south-eastern Weddell Sea in February/March 1983. Total primary production ranged between 80 and 1670 mg C m-2 d-1 with an average of 670 mg C m-2 d-1, nearly 70% of which was contributed by the <20 m size fraction (usually pennate and/or centric diatoms). Production of phytoplankton was in the higher range of values reported by other authors for the same region. Variations in primary production could not be attributed to composition of populations, ambient light levels or concentrations of macronutrients (N, P, Si). Phytoplankton populations had a higher diversity in the deeper parts of the Weddell Sea and coincided with different oceanographic situations. Three zones (along the shelf-ice edge from Atka Bay to Halley Bay, west of Halley Bay and off the Filchner/Rønne Ice Shelf) with different communities could be clearly distinguished. 相似文献
20.
Ulrich Speck Klaus Urich 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1969,63(4):405-409
Zusammenfassung Aus dem exponentiellen Abfall der spezifischen Aktivität nach einmaliger Injektion von L-Leucin-14C wurden die Halbwertszeiten der Gesamtproteine in den meisten Organen des Mußkrebses zu 8,5–19 Tagen bestimmt, in Leber und Niere der Maus zu 1,6–1,7 Tagen. Muskel- und Hämolymphproteine des Krebses zeigten weit längere Halbwertszeiten. Berücksichtigt man die Temperaturdifferenz von 25° unter Annahme eines Q
10 von 2,0–2,5, so ergeben sich für Maus und Krebs etwa übereinstimmende Geschwindigkeiten des Proteinturnovers.
Mit Unterstützung der Deutschen Forschungsgemeinschaft. 相似文献
Protein turnover in the tissues of the crayfish, Orconectes limosus
Summary The exponential decay of protein radioactivity after injection of L-Leucin-14C was measured in the different tissues of the crayfish, and in liver and kidney of the mouse. The half life time of tissue proteins was calculated to be 8.5 to 19 days in most crayfish tissues, 1.6 to 1.7 days in the mouse liver and kidney. Proteins of muscle and hemolymph of crayfish had much longer half life values. Taking into consideration the temperature difference of 25° C and assuming a Q 10 of 2.0 to 2.5, the speed of protein turnover corresponds in the mouse and the crayfish.
Mit Unterstützung der Deutschen Forschungsgemeinschaft. 相似文献