Limiting Similarity
Mostrando 13-24 de 63 artigos, teses e dissertações.
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13. Recent studies on Schistosoma intercalatum: taxonomic status, puzzling distribution and transmission foci revisited
Schistosoma intercalatum, which causes human rectal schistosomiasis in Africa, still presents a great interest for its imprecise taxonomic status and its puzzling distribution in Africa. Two geographically isolated strains of S. intercalatum are recognized, the Lower Guinea strain and the Congo strain, which differ from each other in a number of morphologica
Memórias do Instituto Oswaldo Cruz. Publicado em: 2001-09
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14. Does environmental variability limit niche overlap?
A stochastic theory of limiting similarity is presented that attempts to quantify the relationship between tolerable niche overlap among competing species and the degree of environmental fluctuation. The theory is based on a heuristic analytical approximation that provides conditions under which a rare invading species can increase in the presence of a commu
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15. Limiting long-term illness and its associations with mortality and indicators of social deprivation.
STUDY OBJECTIVE--To examine geographical variation in limiting long-term illness in England and Wales and assesses the extent of its similarity with the distribution of mortality rates and of deprivation. DESIGN--A geographically based study using data from the 1991 census on limiting long term illness. Maps and regression analysis are used to compare the di
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16. Ecological Similarity and Coexistence of Epiphytic Ice-Nucleating (Ice+) Pseudomonas syringae Strains and a Non-Ice-Nucleating (Ice-) Biological Control Agent
De Wit replacement series were used to study competitive interactions between epiphytic Ice+Pseudomonas syringae strains and the biological frost control agents Ice-P. syringae TLP2del1 and Pseudomonas fluorescens A506. Mixtures containing two strains in different proportions but at a constant total population size were inoculated onto potato leaves. The pop
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17. The Bradyrhizobium japonicum fegA gene encodes an iron-regulated outer membrane protein with similarity to hydroxamate-type siderophore receptors.
Iron is important in the symbiosis between soybean and its nitrogen-fixing endosymbiont Bradyrhizobium japonicum, yet little is known about rhizobial iron acquisition strategies. Analysis of outer membrane proteins (OMPs) from B. japonicum 61A152 identified three iron-regulated OMPs in the size range of several known receptors for Fe(III)-scavenging sideroph
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18. Expression of Helicobacter pylori urease genes in Escherichia coli grown under nitrogen-limiting conditions.
Helicobacter pylori produces a potent urease that is believed to play a role in the pathogenesis of gastroduodenal diseases. Four genes (ureA, ureB, ureC, and ureD) were previously shown to be able to achieve a urease-positive phenotype when introduced into Campylobacter jejuni, whereas Escherichia coli cells harboring these genes did not express urease acti
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19. Structural and functional conservation between yeast and human 3-hydroxy-3-methylglutaryl coenzyme A reductases, the rate-limiting enzyme of sterol biosynthesis.
The pathway of sterol biosynthesis is highly conserved in all eucaryotic cells. We demonstrated structural and functional conservation of the rate-limiting enzyme of the mammalian pathway, 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMG-CoA reductase), between the yeast Saccharomyces cerevisiae and humans. The amino acid sequence of the two yeast HMG-C
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20. SurA assists the folding of Escherichia coli outer membrane proteins.
Many proteins require enzymatic assistance in order to achieve a functional conformation. One rate-limiting step in protein folding is the cis-trans isomerization of prolyl residues, a reaction catalyzed by prolyl isomerases. SurA, a periplasmic protein of Escherichia coli, has sequence similarity with the prolyl isomerase parvulin. We tested whether SurA wa
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21. Isolation and characterization of a sulfur-regulated gene encoding a periplasmically localized protein with sequence similarity to rhodanese.
During sulfur-limited growth, the cyanobacterium Synechococcus sp. strain PCC 7942 loses most of its photosynthetic pigments and develops an increased capacity to acquire sulfate. Sulfur deprivation also triggers the synthesis of several soluble polypeptides. We have isolated a prominent polypeptide of 33 kDa that accumulates specifically under sulfur-limiti
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22. Scaling placental oxygen diffusion to birthweight: studies on placentae from low- and high-altitude pregnancies.
Stereological analysis of tissue sections has been used to estimate partial and total conductances of the human placental oxygen diffusion pathway. Analyses were undertaken for neonates and term placentae from populations living at low (400 m) and high (3600 m) altitude in Bolivia. Relationships between conductances and birthweight (and between trophoblast v
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23. Arabidopsis thaliana contains two differentially expressed 3-hydroxy-3-methylglutaryl-CoA reductase genes, which encode microsomal forms of the enzyme.
The enzyme 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR; EC 1.1.1.34) catalyzes the first rate-limiting step in plant isoprenoid biosynthesis. Arabidopsis thaliana contains two genes, HMG1 and HMG2, that encode HMGR. We have cloned these two genes and analyzed their structure and expression. HMG1 and HMG2 consist of four exons and three small introns that
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24. Identification of multiple RNA polymerase sigma factor homologs in the cyanobacterium Anabaena sp. strain PCC 7120: cloning, expression, and inactivation of the sigB and sigC genes.
The sigA gene of Anabaena sp. strain PCC 7120, encoding the principal RNA polymerase sigma factor, and the complement of the rpoD oligonucleotide (K. Tanaka, T. Shiina, and H. Takahashi, Science 242:1040-1042, 1988) were used as probes to isolate two genes, sigB and sigC, which encode two putative sigma factors exhibiting high degrees of similarity to SigA,