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排序方式: 共有511条查询结果,搜索用时 15 毫秒
1.
Duccio Malinverni Simone Marsili Alessandro Barducci Paolo De Los Rios 《PLoS computational biology》2015,11(6)
Hsp70s are a class of ubiquitous and highly conserved molecular chaperones playing a central role in the regulation of proteostasis in the cell. Hsp70s assist a myriad of cellular processes by binding unfolded or misfolded substrates during a complex biochemical cycle involving large-scale structural rearrangements. Here we show that an analysis of coevolution at the residue level fully captures the characteristic large-scale conformational transitions of this protein family, and predicts an evolutionary conserved–and thus functional–homo-dimeric arrangement. Furthermore, we highlight that the features encoding the Hsp70 dimer are more conserved in bacterial than in eukaryotic sequences, suggesting that the known Hsp70/Hsp110 hetero-dimer is a eukaryotic specialization built on a pre-existing template. 相似文献
2.
3.
Summary In this paper the effect of temperature and pH on the settling behaviour of a flocculent strain ofZymomonas mobilis is studied by using the old fashioned batch settling technique. Plots are given to show the influence of the above mentioned parameters on the settling curve behaviour. 相似文献
4.
M. Aluja J. Guillen P. Liedo M. Cabrera E. Rios G. de la Rosa H. Celedonio D. Mota 《BioControl》1990,35(1):39-48
A total of 1,302 parasitoids representing 8 species and 4 families were recovered from 9,818 fruit fly host fruits sampled.
The most common parasitoid species wasDiachasmimorpha longicaudata (Ashmead). Average percent parasitism ranged between 0.44 and 29.23%. Parasitoid emergence data indicate thatAnastrepha ludens (Loew),A. obliqua (Sein),A. serpentina (Wiedeman),A. striata (Schiner) andToxotrypana curvicauda (Gerstaecker) were subject to parasitism. We provide information on the population fluctuation ofAnastrepha ludens, A. obliqua, A. serpentina, A. distincta (Greene),A. striata, A. fraterculus (Wiedeman),A. chiclayae (Greene),A. montei (Costa Lima),A. leptozona (Hendel) andA. tripunctata (Wulp).Anastrepha ludens andA. obliqua were the most common species, representing 95.3% of all fruit fly species caught in McPhail traps.
相似文献
5.
Leirla Salazar Hafida Fsihi Edda de Rossi Giovanna Riccardi Carmen Rios Stewart T. Cole Howard E. Takiff 《Molecular microbiology》1996,20(2):283-293
The genus Mycobacterium is composed of species with widely differing growth rates ranging from approximately three hours in Mycobacterium smegmatis to two weeks in Mycobacterium leprae. As DNA replication is coupled to cell duplication, it may be regulated by common mechanisms. The chromosomal regions surrounding the origins of DNA replication from M. smegmatis, M. tuberculosis, and M. leprae have been sequenced, and show very few differences. The gene order, rnpA-rpmH-dnaA-dnaN-recF-orf-gyrB-gyrA, is the same as in other Gram-positive organisms. Although the general organization in M. smegmatis is very similar to that of Streptomyces spp., a closely related genus, M. tuberculosis and M. leprae differ as they lack an open reading frame, between dnaN and recF, which is similar to the gnd gene of Escherichia coli. Within the three mycobacterial species, there is extensive sequence conservation in the intergenic regions flanking dnaA, but more variation from the consensus DnaA box sequence was seen than in other bacteria. By means of subcloning experiments, the putative chromosomal origin of replication of M. smegmatis, containing the dnaA-dnaN region, was shown to promote autonomous replication in M. smegmatis, unlike the corresponding regions from M. tuberculosis or M. leprae. 相似文献
6.
A. Diez de los Rios N. E. DeRose W. McD Armstrong 《The Journal of membrane biology》1981,63(1-2):25-30
Summary Open-tip and liquid ion-exchanger microelectrodes were used to study the effects of cAMP (6mm, added to the serosal medium) on apical membrane potential (E
m
) and intracellular sodium, potassium, and chloride activities (a
Na
i
,a
K
i
,a
Cl
i
) inNecturus gallbladder under open-circuit conditions. Transepithelial potential difference (E
Tr
) was also measured. In the presence of cAMP,a
Cl
i
fell from about 1.5 times its equilibrium value to a level that corresponded to electrochemical equilibrium across the apical and basolateral cell membranes. Under these conditionsa
Na
i
decreased anda
K
i
increased,E
m
was unchanged andE
Tr
increased from virtually zero to a small but significant serosal positive value. The cAMP-induced increase ina
K
i
was abolished when Cl–-free incubation media were used. Addition of the Ca++-ionophore A23187 (0.5 g/ml) to the serosal medium had no effect onE
m
,E
Tr
, ora
Cl
i
. When A23187 was added to the mucosal medium,E
m
and the basolateral membrane potential hyperpolarized by about 20 mV and an increase in the outwardly directed electrochemical driving force for Cl– was observed. These results indicate that cAMP inhibits coupled transapical Na–Cl entry into epithelial cells ofNecturus gallbladder and suggest that this inhibition may not be mediated by an increase in intracellular Ca++ concentration. 相似文献
7.
8.
Solar radiation and functional traits explain the decline of forest primary productivity along a tropical elevation gradient
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Nikolaos M. Fyllas Lisa Patrick Bentley Alexander Shenkin Gregory P. Asner Owen K. Atkin Sandra Díaz Brian J. Enquist William Farfan‐Rios Emanuel Gloor Rossella Guerrieri Walter Huaraca Huasco Yoko Ishida Roberta E. Martin Patrick Meir Oliver Phillips Norma Salinas Miles Silman Lasantha K Weerasinghe Joana Zaragoza‐Castells Yadvinder Malhi 《Ecology letters》2017,20(6):730-740
One of the major challenges in ecology is to understand how ecosystems respond to changes in environmental conditions, and how taxonomic and functional diversity mediate these changes. In this study, we use a trait‐spectra and individual‐based model, to analyse variation in forest primary productivity along a 3.3 km elevation gradient in the Amazon‐Andes. The model accurately predicted the magnitude and trends in forest productivity with elevation, with solar radiation and plant functional traits (leaf dry mass per area, leaf nitrogen and phosphorus concentration, and wood density) collectively accounting for productivity variation. Remarkably, explicit representation of temperature variation with elevation was not required to achieve accurate predictions of forest productivity, as trait variation driven by species turnover appears to capture the effect of temperature. Our semi‐mechanistic model suggests that spatial variation in traits can potentially be used to estimate spatial variation in productivity at the landscape scale. 相似文献
9.
The oxidative process of LDL particles generates molecules which are structurally similar to platelet-activating factor (PAF), and some effects of oxidized LDL (oxLDL) have been shown to be dependent on PAF receptor (PAFR) activation. In a previous study, we showed that PAFR is required for upregulation of CD36 and oxLDL uptake. In the present study we analyzed the molecular mechanisms activated by oxLDL in human macrophages and the contribution of PAFR to this response. Human adherent monocytes/macrophages were stimulated with oxLDL. Uptake of oxLDL and CD36 expression were determined by flow cytometry; MAP kinases and Akt phosphorylation by Western blot; IL-8 and MCP-1 concentration by ELISA and mRNA expression by real-time PCR. To investigate the participation of the PI3K/Akt pathway, Gαi-coupled protein or PAFR, macrophages were treated with LY294002, pertussis toxin or with the PAFR antagonists WEB2170 and CV3988, respectively before addition of oxLDL. It was found that the addition of oxLDL to human monocytes/macrophages activates the PI3K/Akt pathway which in turn activates the MAPK (p38 and JNK). Phosphorylation of Akt requires the engagement of PAFR and a Gαi-coupled protein. The upregulation of CD36 protein and the uptake of oxLDL as well as the IL-8 production are dependent on PI3K/Akt pathway activation. The increased CD36 protein expression is dependent on PAFR and Gαi-coupled protein. Transfection studies using HEK 293t cells showed that oxLDL uptake occurs with either PAFR or CD36, but IL-8 production requires the co-transfection of both PAFR and CD36. These findings show that PAFR has a pivotal role in macrophages response to oxLDL and suggest that pharmacological intervention at the level of PAFR activation might be beneficial in atherosclerosis. 相似文献
10.
Ana Paula de Araújo Maria Alice Varjal de Melo-Santos Sidney de Oliveira Carlos Eugênia Maria Mariz Maranho Rios Lêda Regis 《Biological Control》2007,41(3):339-347
The larvicidal activity of an experimental formulation of Bacillus thuringiensis israelensis (Bti) against Aedes aegypti larvae was evaluated under laboratory and simulated field conditions (SFC). Samples of technical powder (TP) were assayed to establish the LC50 and the potency of the product. The larvicidal activity of the TP and the tablet (T) were evaluated under SFC to assess the efficacy and the residual activity, measured against Ae. aegypti larvae. Either a T or 250 mg of TP were added to 50 L of water in plastic containers. Containers were exposed to sunlight or kept in the shade. Results showed a LC50 of 0.26 mg/L and a potency of 750 ITU/mg. In spite of differences in the toxicity amongst TP and T samples, all of them killed 98–100% of the larvae and the mortality remained high for six months, in the shade. The replacement of 20% or 60% of the water volume did not affect the activity of the product. Seasonal differences influenced the persistence of the product in containers exposed to sunlight. Both formulations showed an excellent performance, especially when kept in the shade. The Bti tablet evaluated in this study is potentially very useful in programs to control dengue vectors. 相似文献