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91.
92.
Two forms of biologically active gonadotropin releasing hormones were isolated from the hypothalami ofCatla catla. Gonadotropin releasing hormone activity was studiedin vitro using enzymatically dispersed carp pituitary cell incubation system. Gonadotropin released into the medium was measured by
carp gonadotropin-radio immuno assay. Acetic acid extracted hypothalamic material was subjected to acetone fractionation.
Among the three protein pellets obtained at different time periods (ACI, ACII and ACIII), AC II exhibited the gonadotropin releasing hormone activity. Gel filtration of AC II through Sephadex G-25 column showed
three protein peaks (SG I, SG II SGIII) and only S G II demonstrated strong gonadotropin releasing hormone activity. Elution of SG II through FPLC Mono Q column
(an anion exchanger) in NaCl gradient programme showed one unadsorbed (MQ I) and three adsorbed (MQ II, MQ III and MQ IV)
protein peaks. MQ III, which was eluted with 51% NaCl, exhibited gonadotropin releasing hormone activity. Surprisingly, unadsorbed
fractions, MQ I, also showed gonadotropin releasing hormone activity. MQ 1 was therefore subjected to FPLC Mono S (a cation
exchanger) column chromatography where a highly active gonadotropin releasing hormone enriched peak, i.e., MS III, could be
eluted with 45% NaCl. These findings show thatCatla catla hypothalamus has two forms of gonadotropin releasing hormones one anionic (carp gonadotropin releasing hormone I) and another
cationic (carp gonadotropin releasing hormone II). These two forms of gonadotropin releasing hormones were also active in
heterologous carp species, rohu(Labeo rohita), mrigal(Cirrhinus mrigala) and an exotic common carp(Cyprinus carpio). Combined activity of two forms of gonadotropin releasing hormones was significantly greater as compared to any of the single
form. 相似文献
93.
OBJECTIVE: To devise an optimal cytology threshold for colposcopy referral in resource-limited settings. STUDY DESIGN: Four hundred seventy-two symptomatic women 20-60 years old were screened by both cytology and colposcopy. Onsite biopsy was taken if lesions grade 1 or above were detected on colposcopy. Women found to have cervical intraepithelial neoplasia (CIN) 2 and above lesions on histopathology were stratified according to their cytologic diagnosis (atypical squamous cells of undetermined significance [ASCUS]+ threshold, low grade squamous intraepithelial lesion [LSIL]+ threshold, and high grade squamous intraepithelial lesion [HSIL]+ threshold). The comparative sensitivity, specificity and predictive values in each group were calculated, taking biopsy as the gold standard. RESULTS: The sensitivity of LSIL + cytology to detect CIN 2+ lesions was 91.5% (referral load, 30.7%). While the sensitivity of ASCUS+ cytology threshold was almost the same (92.3%), the referral load was much higher (42.2%). With HSIL+ cytology threshold, though the referral load was reduced substantially (21.9%), the sensitivity also decreased, to 81.5%. CONCLUSION: The results indicate that in order to achieve high sensitivity, the LSIL cytology threshold appears to be optimum for colposcopic referrals. 相似文献
94.
Partho Ghosh 《Microbiological reviews》2004,68(4):771-795
The type III secretion system (TTSS) of gram-negative bacteria is responsible for delivering bacterial proteins, termed effectors, from the bacterial cytosol directly into the interior of host cells. The TTSS is expressed predominantly by pathogenic bacteria and is usually used to introduce deleterious effectors into host cells. While biochemical activities of effectors vary widely, the TTSS apparatus used to deliver these effectors is conserved and shows functional complementarity for secretion and translocation. This review focuses on proteins that constitute the TTSS apparatus and on mechanisms that guide effectors to the TTSS apparatus for transport. The TTSS apparatus includes predicted integral inner membrane proteins that are conserved widely across TTSSs and in the basal body of the bacterial flagellum. It also includes proteins that are specific to the TTSS and contribute to ring-like structures in the inner membrane and includes secretin family members that form ring-like structures in the outer membrane. Most prominently situated on these coaxial, membrane-embedded rings is a needle-like or pilus-like structure that is implicated as a conduit for effector translocation into host cells. A short region of mRNA sequence or protein sequence in effectors acts as a signal sequence, directing proteins for transport through the TTSS. Additionally, a number of effectors require the action of specific TTSS chaperones for efficient and physiologically meaningful translocation into host cells. Numerous models explaining how effectors are transported into host cells have been proposed, but understanding of this process is incomplete and this topic remains an active area of inquiry. 相似文献
95.
The goal of the present study is to assess how landscape configuration influenced the distribution of life-history traits across bird, carabid beetle and butterfly communities of mosaic forest landscapes in south-western France. A set of 12 traits was selected for each species, characterizing rarity, biogeographical distribution, body size, trophic guild, dispersal power, reproductive potential and phenology. We used a three-table ordination method, RLQ analysis, to link directly bird, beetle and butterfly traits to the same set of landscape metrics calculated in 400 m-radius buffers around sample points. RLQ analyses showed significant associations between life-history traits and landscape configuration for all three taxonomical groups. Threatened species from all groups were characterized by a combination of life traits that makes them especially sensitive to the fragmentation of herbaceous and shrub-dominated habitats at the landscape scale. These key life traits were low productivity, intermediate body mass, restricted geographic range, late phenology and ground gleaning for threatened birds, intermediate body size, spring adult activity, northern distribution and summer breeding period for threatened carabids, and restricted range, overwintering as eggs or larvae, low mobility, monophagy and short flight periods for threatened butterflies. Focusing on species life traits can provide a functional perspective, which helps to determine adequate measures for the conservation of threatened species and communities of several taxonomical groups in mosaic landscapes. 相似文献
96.
Trautwein K Kühner S Wöhlbrand L Halder T Kuchta K Steinbüchel A Rabus R 《Applied and environmental microbiology》2008,74(8):2267-2274
The denitrifying betaproteobacterium "Aromatoleum aromaticum" strain EbN1 degrades several aromatic compounds, including ethylbenzene, toluene, p-cresol, and phenol, under anoxic conditions. The hydrophobicity of these aromatic solvents determines their toxic properties. Here, we investigated the response of strain EbN1 to aromatic substrates at semi-inhibitory (about 50% growth inhibition) concentrations under two different conditions: first, during anaerobic growth with ethylbenzene (0.32 mM) or toluene (0.74 mM); and second, when anaerobic succinate-utilizing cultures were shocked with ethylbenzene (0.5 mM), toluene (1.2 mM), p-cresol (3.0 mM), and phenol (6.5 mM) as single stressors or as a mixture (total solvent concentration, 2.7 mM). Under all tested conditions impaired growth was paralleled by decelerated nitrate-nitrite consumption. Additionally, alkylbenzene-utilizing cultures accumulated poly(3-hydroxybutyrate) (PHB) up to 10% of the cell dry weight. These physiological responses were also reflected on the proteomic level (as determined by two-dimensional difference gel electrophoresis), e.g., up-regulation of PHB granule-associated phasins, cytochrome cd(1) nitrite reductase of denitrification, and several proteins involved in oxidative (e.g., SodB) and general (e.g., ClpB) stress responses. 相似文献
97.
Covalent heme attachment in Synechocystis hemoglobin is required to prevent ferrous heme dissociation 下载免费PDF全文
Hoy JA Smagghe BJ Halder P Hargrove MS 《Protein science : a publication of the Protein Society》2007,16(2):250-260
Synechocystis hemoglobin contains an unprecedented covalent bond between a nonaxial histidine side chain (H117) and the heme 2-vinyl. This bond has been previously shown to stabilize the ferric protein against denaturation, and also to affect the kinetics of cyanide association. However, it is unclear why Synechocystis hemoglobin would require the additional degree of stabilization accompanying the His117-heme 2-vinyl bond because it also displays endogenous bis-histidyl axial heme coordination, which should greatly assist heme retention. Furthermore, the mechanism by which the His117-heme 2-vinyl bond affects ligand binding has not been reported, nor has any investigation of the role of this bond on the structure and function of the protein in the ferrous oxidation state. Here we report an investigation of the role of the Synechocystis hemoglobin His117-heme 2-vinyl bond on structure, heme coordination, exogenous ligand binding, and stability in both the ferrous and ferric oxidation states. Our results reveal that hexacoordinate Synechocystis hemoglobin lacking this bond is less stable in the ferrous oxidation state than the ferric, which is surprising in light of our understanding of pentacoordinate Hb stability, in which the ferric protein is always less stable. It is also demonstrated that removal of the His117-heme 2-vinyl bond increases the affinity constant for intramolecular histidine coordination in the ferric oxidation state, thus presenting greater competition for the ligand binding site and lowering the observed rate and affinity constants for exogenous ligands. 相似文献
98.
Das SK Tan J Raja S Halder J Paria BC Dey SK 《The Journal of biological chemistry》2000,275(37):28834-28842
Estrogen actions in target organs are normally mediated via activation of nuclear estrogen receptors (ERs). By using mRNA differential display technique, we show, herein, that estradiol-17beta (E(2)) and its catechol metabolite 4-hydroxy-E(2) (4OHE(2)) can modulate uterine gene expression in ERalpha(-/-) mice. Whereas administration of E(2) or 4OHE(2) rapidly up-regulated (4-8-fold) the expression of immunoglobulin heavy chain binding protein (Bip), calpactin I (CalP), calmodulin (CalM), and Sik similar protein (Sik-SP) genes in ovariectomized wild-type or ERalpha(-/-) mice, the expression of secreted frizzled related protein-2 (SFRP-2) gene was down-regulated (4-fold). Bip, CalP, and CalM are calcium-binding proteins and implicated in calcium homeostasis, whereas SFRP-2 is a negative regulator of Wnt signaling. Bip and Sik-SP also possess chaperone-like functions. Administration of ICI-182,780 or cycloheximide failed to influence these estrogenic responses, demonstrating that these effects occur independent of ERalpha, ERbeta, or protein synthesis. In situ hybridization showed differential cell-specific expression of these genes in wild-type and ERalpha(-/-) uteri. Although progesterone can antagonize or synergize estrogen actions, it had minimal effects on these estrogenic responses. Collectively, the results demonstrate that estrogens have a unique ability to influence specific genes in the uterus not involving classical nuclear ERs. 相似文献
99.
The extent of adsorption (Gamma2(1)) of bovine serum albumin (BSA), beta-lactoglobulin, lysozyme, gelatin, and DNA from aqueous solution onto the hydrophilic surface of cellulose has been measured as function of biopolymer concentration at different temperatures, pHs, and ionic strengths, and in the presence of a high concentration of inorganic salts and denaturants. In all cases, the value of Gamma2(1) increases with the increase of biopolymer concentration (X2) in bulk and it attains a maximum value at a critical mole fraction concentration X2m. The value of Gamma2m depends upon the nature of protein, temperature, pH, and ionic strength, as well as the nature of neutral salts present in excess. Gamma2m for proteins at a fixed physicochemical condition stands in the following order: Gelatin>betalactoglobulin>lysozyme>BSA. The isotherms for adsorption of DNA nucleotides on cellulose surface at pH 4.0 have been compared at different temperatures and ionic strengths, and in the presence of high concentration of inorganic salts LiCl, NaCl, KCl, and Na2SO4. Values of Gamma2m for different systems have been evaluated and critically compared. At pH 6.0 and 8.0, Gamma2(1) values of DNA nucleotides on cellulose are all negative due to the excess positive hydration of cellulose. At pH 4.0, adsorption of nucleotides of acid, alkali, and heat-denatured DNA widely differ from each other and in the presence of excess concentration of urea becomes negative. The probable mechanisms of biopolymer-cellulose adsorption in terms of polymer hydration, steric interaction, London-van der Waals, hydrophobic, and other types of interactions have been discussed qualitatively. The standard free energy change for the adsorption of protein and DNA nucleotides on the cellulose surface at the state of adsorption saturation has been calculated in kJ per kg of cellulose using an integrated form of the Gibbs adsorption equation. The relation between DeltaG degrees and maximum affinities between biopolymers and the polysaccharide interface have been discussed for various systems. 相似文献
100.
Sumit Handa Blair G. Paul Jeffery F. Miller David L. Valentine Partho Ghosh 《BMC structural biology》2016,16(1):13