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101.
The Rhizobium meliloti dctA gene encodes the C4-dicarboxylate permease which mediates uptake of C4-dicarboxylates, both in free-living and symbiotic cells. Based on the hydrophobicity of the DctA protein, 12 putative membrane spanning regions were predicted. The membrane topology was further analysed by isolating in vivo fusions of DctA to Escherichia coli alkaline phosphatase (PhoA) and E. coli β-galactosidase (LacZ). Of 10 different fusions 7 indicated a periplasmic and 3 a cytoplasmic location of the corresponding region of the DctA protein. From these data a two-dimensional model of DctA was constructed which comprised twelve transmembrane α-helices with the amino-terminus and the carboxy-terminus located in the cytoplasm. In addition, four conserved amino acid motifs present in many eukaryotic and prokaryotic transport proteins were observed. 相似文献
102.
103.
Paula Tatiana Lopes Seixas Antonio Jacinto Demuner Luiz Claudio Almeida Barbosa Cristiane Isaac Cerceau Daiane Einhardt Blank Marcelo Henrique Dos Santos Elizeu de Sá Farias Marcelo Coutinho Picanço 《Journal of Applied Entomology》2023,147(2):116-125
Aedes aegypti L. (Diptera: Culicidae) is a vector for serious diseases in tropical regions. This pest is mainly controlled by commercial larvicides but the application of such products has led to environmental problems. Essential oils (EO) have been consistently reported as molecules with insecticidal activity and can be used to produce more environmentally friendly larvicides in the control of A. aegypti. In this study, the larvicidal effect of essential oils (EO) from the leaves of three Artemisia species was evaluated against A. aegypti. The oils were obtained from steam distillation and their chemical composition was determined by gas chromatography–mass spectrometry. The EO of Artemisia camphorata was the most active in the screening bioassay and presented LC50 and LC95 of 64.95 and 74.18 μg ml−1, respectively. In addition, we found that germacrene D-4-ol was the constituent responsible for the toxicity of this EO. Artemisia camphorata EO and its major constituent, germacrene D-4-ol, are promising for the development of natural larvicides against A. aegypti. 相似文献
104.
Alfred L. George Jr. Geeta S. Iyer Robert Kleinfield Roland G. Kallen Robert L. Barchi 《Genomics》1993,15(3)
Voltage-dependent sodium channels are essential for normal membrane excitability and contractility in adult skeletal muscle. The gene encoding the principal sodium channel α-subunit isoform in human skeletal muscle (SCN4A) has recently been shown to harbor point mutations in certain hereditary forms of periodic paralysis. We have carried out an analysis of the detailed structure of this gene including delineation of intron-exon boundaries by genomic DNA cloning and sequence analysis. The complete coding region of SCN4A is found in 32.5 kb of genomic DNA and consists of 24 exons (54 to > 2.2 kb) and 23 introns (97 bp-4.85 kb). The exon organization of the gene shows no relationship to the predicted functional domains of the channel protein and splice junctions interrupt many of the transmembrane segments. The genomic organization of sodium channels may have been partially conserved during evolution as evidenced by the observation that 10 of the 24 splice junctions in SCN4A are positioned in homologous locations in a putative sodium channel gene in Drosophila (para). The information presented here should be extremely useful both for further identifying sodium channel mutations and for gaining a better understanding of sodium channel evolution. 相似文献
105.
This paper reviews several aspects of discordant growth in multiple pregnancies. Discordant growth is not a chance event and therefore several patterns can be discerned. About 75% of twins exhibit < 15% discordance (concordant), 20% are 15-25% (mildly) discordant, and about 5% are more than 25% (severely) discordant. Higher frequencies and increased severity are seen among triplets. Five observations regarding discordance became generally accepted: (a) not all discordant pairs are similar; (b) the larger the discordance level the greater is the risk for an adverse outcome; (c) discordant growth does not necessarily represent growth restriction; (d) a discordance level may have a different clinical implication in different gestational ages; and (e) the smaller fetuses in severely discordant pairs are at disproportionate risk for neonatal mortality. Mild discordance may represent a normal variation between sibs whereas severely discordant pairs often exhibit patterns of growth restriction. Not infrequently, discordance may represent an adaptation to the limited intrauterine space in order to increase gestational age. 相似文献
106.
Jiin-Chyuan Luo Alfred I. Neugut Gail Garbowski Kenneth A. Forde Michael Treat Steven Smith Henry Niman Paul W. Brandt-Rauf 《Biomarkers》1996,1(1):29-33
Over-expression of p21 ras-related protein was determined in the plasma by immunoblotting and in the tissue by immuno-histochemistry in a cohort of patients undergoing colonoscopy. In the plasma samples, p21 ras over-expression was detected in: 9% (4/47) of normal controls; 21% (13/61) of individuals with normal colonoscopies but with a prior history of colonic neoplasia; 12% (4/33) of small adenoma patients, 29% (6/21) of large adenoma patients; 63% (5/8) of carcinoma-in-adenoma patients; 50% (2/4) of Dukes' A carcinoma patients; and 20% (2/10) of Dukes' B-D carcinoma patients. In the tissue samples, p21 ras over-expression was detected in: 25% (2/8) of small adenoma patients; 44% (4/9) of large adenoma patients; 100% (4/4) of carcinoma-in-adenoma patients; and 33% (1/3) of Dukes' B-C carcinoma patients. For matched plasma-tissue pairs, there was a statistically significant correlation for p21 ras over-expression (R = 0.47, p = 0.02). 相似文献
107.
Characterization of two mannose-binding protein cDNAs from rhesus monkey (Macaca mulatta): structure and evolutionary implications 总被引:3,自引:0,他引:3
Mannose-binding proteins (MBPs), members of the collectin family,have been implicated as lectin opsonins for various virusesand bacteria. Two distinct but related MBPs, MBP-A and MBP-C,with -55% identity at the amino acid level, have been previouslycharacterized from rodents. In humans, however, only one formof MBP has been characterized. In this paper we report studieselucidating the evolution of primate MBPs. ELISA and Westernblot analyses indicated that rhesus and cynomolgus monkeys havetwo forms of MBP in their sera, while chimpanzees have onlyone form, similar to humans. Two distinct MBP cDNA clones wereisolated and characterized from a rhesus monkey liver cDNA library.Rhesus MBP-A is closely related to the mouse and rat MBP-A,showing 77% and 75% identity at the amino acid level, respectively.Rhesus MBP-A also has three cysteines at the N-terminus, similarto mouse and rat MBP-A and human MBP. Rhesus MBP-C shares 90%identity with the human MBP at the amino acid level and hasthree cysteines at the N-terminus, in contrast to two cysteineresidues found in rodent MBP-C. A stretch of nine amino acidsclose to the N-terminus, absent in both mouse and rat MBP-A,but present in rodent MBP-C, chicken and human MBPs, is alsofound in the rhesus MBP-A. The phylogenetic analysis of rhesusand other mammalian MBPs, coupled with the serological datasuggest that at least two distinct MBP genes existed prior tomammalian radiation and the hominoid ancestor apparently lostone of these genes or failed to express it. collectin rhesus monkey mannose-binding protein MBP cDNA mannan-binding protein 相似文献
108.
Ingmar Sethson Ulf Edlund Tadeusz A. Holak Alfred Ross Bengt-Harald Jonsson 《Journal of biomolecular NMR》1996,8(4):417-428
Summary The backbone NMR resonances of human carbonic anhydase I (HCA I) have been assigned. This protein is one of the largest monomeric proteins assigned so far. The assignment was enabled by a combination of 3D triple-resonance experiments and extensive use of amino acid-specific 15N-labeling. The obtained resonance assignment has been used to evaluate the secondary structure elements present in solution. The solution structure appears to be very similar to the crystal structure, although some differences can be observed. Proton-deuteron exchange experiments have shown that the assignments provide probes that can be used in future folding studies of HCA I.The chemical shift data have been deposited in the BioMagResBank in Madison, WI, U.S.A. 相似文献
109.
Monika Kröckel Michael Grodzicki Vasilios Papaefthymiou Alfred X. Trautwein Athanassios Kostikas 《Journal of biological inorganic chemistry》1996,1(2):173-176
Values for the exchange-coupling constant J and the double-exchange parameter B have been estimated for dimeric and hexameric
mixed-valence iron clusters. For sulfur-bridged species the range of J values is 300–450 cm–1, and B values vary between 320 and 400 cm–1. For an OH-bridged diiron cluster B is as large as 1300 cm–1.
Received and accepted: 23 January 1996 相似文献
110.