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1.
Mutant of Escherichia coli with Anomalous Cell Division and Ability to Decrease Episomally and Chromosomally Mediated Resistance to Ampicillin and Several Other Antibiotics 总被引:30,自引:17,他引:13 下载免费PDF全文
In a mutation experiment with a rough, ampicillin-resistant strain, we isolated two smooth mutants which were both sensitive to ampicillin and carried defects in the cell envelope. One of the strains (with the envA gene) is hindered in its completion of septa and forms chains of cells. The envA gene has been mapped to a position between leu and proB, at 2 to 4 min. The envA gene decreased the resistance mediated by both episomal and chromosomal genes for resistance to several antibiotics. During growth the envA mutant was characterized by abnormal ratios between viable count or cell count and optical density. The ratio between viable count and optical density was affected during shift-up and shift-down experiments. When compared to the parent strain, the envA mutant was found to be more resistant to ultraviolet irradiation on plates. Prestarvation for tryptophan had a protective effect against irradiation both on the parent strain and the envA mutant. 相似文献
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Increased expression of the dyslexia candidate gene DCDC2 affects length and signaling of primary cilia in neurons 总被引:1,自引:0,他引:1
Massinen S Hokkanen ME Matsson H Tammimies K Tapia-Páez I Dahlström-Heuser V Kuja-Panula J Burghoorn J Jeppsson KE Swoboda P Peyrard-Janvid M Toftgård R Castrén E Kere J 《PloS one》2011,6(6):e20580
DCDC2 is one of the candidate susceptibility genes for dyslexia. It belongs to the superfamily of doublecortin domain containing proteins that bind to microtubules, and it has been shown to be involved in neuronal migration. We show that the Dcdc2 protein localizes to the primary cilium in primary rat hippocampal neurons and that it can be found within close proximity to the ciliary kinesin-2 subunit Kif3a. Overexpression of DCDC2 increases ciliary length and activates Shh signaling, whereas downregulation of Dcdc2 expression enhances Wnt signaling, consistent with a functional role in ciliary signaling. Moreover, DCDC2 overexpression in C. elegans causes an abnormal neuronal phenotype that can only be seen in ciliated neurons. Together our results suggest a potential role for DCDC2 in the structure and function of primary cilia. 相似文献
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Summary The aim of this investigation was to examine if 5-hydroxytryptamine (5-HT) is detectable not only in mast cells but also in
sympathetic nerve fibres in oral sites of the rat, including the periodontal ligament, pulp, palatal mucosa, and vestibular
sulcus. Antibodies against 5-HT and tyrosine hydroxylase were used. Maxillae from rats were dissected free, fixed, decalcified,
cut transversally, and processed for immunohistochemistry. Nerve fibres showing 5-HT-like immunoreactivity were regularly
observed in the walls of the arteries and arterioles in the vestibular sulcus and the periodontal ligament. However, 5-HT-like
immunoreactivity was not seen in the walls of the vessels of the palatal mucosa. Interestingly, 5-HT-like immunoreactivity
coexisted with tyrosine hydroxylase-like immunoreactivity in the innervation of the periodontal ligament and the vestibular
sulcus. Thus, the present study gives morphological correlate for the occurrence of effects of 5-HT derived not only from
mast cells but also from sympathetic nerve fibres in oral tissues. The source of 5-HT in the nerve fibres as well as the functional
implications of the observations remain to be determined. 相似文献
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A method of preparation and flow cytometric analysis of chromosomes from human peripheral lymphocytes is described. The procedure allows a resolution coefficient of variation better than 3% using propidium iodide staining and a commercially available flow cytometer. 相似文献
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Matsson H Davey EJ Draptchinskaia N Hamaguchi I Ooka A Levéen P Forsberg E Karlsson S Dahl N 《Molecular and cellular biology》2004,24(9):4032-4037
The ribosomal protein S19 (RPS19) is located in the small (40S) subunit and is one of 79 ribosomal proteins. The gene encoding RPS19 is mutated in approximately 25% of patients with Diamond-Blackfan anemia, which is a rare congenital erythroblastopenia. Affected individuals present with decreased numbers or the absence of erythroid precursors in the bone marrow, and associated malformations of various organs are common. We produced C57BL/6J mice with a targeted disruption of murine Rps19 to study its role in erythropoiesis and development. Mice homozygous for the disrupted Rps19 were not identified as early as the blastocyst stage, indicating a lethal effect. In contrast, mice heterozygous for the disrupted Rps19 allele have normal growth and organ development, including that of the hematopoietic system. Our findings indicate that zygotes which are Rps19(-/-) do not form blastocysts, whereas one normal Rps19 allele in C57BL/6J mice is sufficient to maintain normal ribosomal and possibly extraribosomal functions. 相似文献
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Susanne Åkesson Phil W. Atkinson Ana Bermejo Javier de la Puente Mauro Ferri Chris M. Hewson Jan Holmgren Erich Kaiser Lyndon Kearsley Raymond H. G. Klaassen Heikki Kolunen Gittan Matsson Fausto Minelli Gabriel Norevik Hannu Pietiäinen Navinder J. Singh Fernando Spina Lukas Viktora Anders Hedenström 《Evolution; international journal of organic evolution》2020,74(10):2377-2391
Spectacular long-distance migration has evolved repeatedly in animals enabling exploration of resources separated in time and space. In birds, these patterns are largely driven by seasonality, cost of migration, and asymmetries in competition leading most often to leapfrog migration, where northern breeding populations winter furthest to the south. Here, we show that the highly aerial common swift Apus apus, spending the nonbreeding period on the wing, instead exhibits a rarely found chain migration pattern, where the most southern breeding populations in Europe migrate to wintering areas furthest to the south in Africa, whereas the northern populations winter to the north. The swifts concentrated in three major areas in sub-Saharan Africa during the nonbreeding period, with substantial overlap of nearby breeding populations. We found that the southern breeding swifts were larger, raised more young, and arrived to the wintering areas with higher seasonal variation in greenness (Normalized Difference Vegetation Index) earlier than the northern breeding swifts. This unusual chain migration pattern in common swifts is largely driven by differential annual timing and we suggest it evolves by prior occupancy and dominance by size in the breeding quarters and by prior occupancy combined with diffuse competition in the winter. 相似文献
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Leif Matsson 《Journal of biological physics》2005,31(3-4):303-321
Before DNA replication can be initiated a definite number of adenosine triphosphate (ATP) containing pre-replication protein
complexes (pre-RCs) must be assembled and bound to DNA like in a super-critical mass. A chemically driven dynamics of the
Ginzburg-Landau (GL) type is derived, using the non-equilibrium equation for binding of pre-RCs to DNA and a probabilistic
conformational distribution of these protein complexes. This dynamics, in which the DNA-protein system behaves like a nonlinear
elastically braced string (NEBS), can control the cell cycle via conformational transitions such that G2 cells contain exactly twice as much DNA as G1 cells. After adjustment of previously-made derivations, the model is compared with cell growth data from the T lymphocyte
MLA-144. 相似文献
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The Carboxin-Binding Site on Paracoccus denitrificans Succinate:Quinone Reductase Identified by Mutations 总被引:1,自引:0,他引:1
Succinate:quinone reductase catalyzes electron transfer from succinate to quinone in aerobic respiration. Carboxin is a specific inhibitor of this enzyme from several different organisms. We have isolated mutant strains of the bacterium Paracoccus denitrificans that are resistant to carboxin due to mutations in the succinate:quinone reductase. The mutations identify two amino acid residues, His228 in SdhB and Asp89 in SdhD, that most likely constitute part of a carboxin-binding site. This site is in the same region of the enzyme as the proposed active site for ubiquinone reduction. From the combined mutant data and structural information derived from Escherichia coli and Wolinella succinogenes quinol:fumarate reductase, we suggest that carboxin acts by blocking binding of ubiquinone to the active site. The block would be either by direct exclusion of ubiquinone from the active site or by occlusion of a pore that leads to the active site. 相似文献