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31.
32.
Scantlebury M Shanas U Kupshtein H Speakman JR Haim A 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2004,137(2):419-423
The common spiny mouse Acomys cahirinus, of Ethiopian origin, has a widespread distribution across arid, semi-arid and Mediterranean parts of the Arabian sub-region. We compared the daily energy expenditure (DEE), water turnover (WTO) and sustained metabolic scope (SusMS=DEE/resting metabolic rate) of two adjacent populations during the winter. Mice were captured from North- and South- facing slopes (NFS and SFS) of the same valley, comprising mesic and xeric habitats, respectively. Both DEE and SusMS winter values were greater in NFS than SFS mice and were significantly greater than values previously measured in the summer for these two populations in the same environments. However, WTO values were consistent with previously established values and were not significantly different from allometric predictions for desert eutherians. We suggest that physiological plasticity in energy expenditure, which exists both temporally and spatially, combined with stable WTO, perhaps reflecting a xeric ancestry, has enabled A. cahirinus to invade a wide range of habitats. 相似文献
33.
Huemmerich D Scheibel T Vollrath F Cohen S Gat U Ittah S 《Current biology : CB》2004,14(22):2070-2074
Spider dragline silk, which exhibits extraordinary strength and toughness, is primarily composed of two related proteins that largely consist of repetitive sequences. In most spiders, the repetitive region of one of these proteins is rich in prolines, which are not present in the repetitive region of the other. The absence of prolines in one component was previously speculated to be essential for the thread structure. Here, we analyzed dragline proteins of the garden spider Araneus diadematus, ADF-3 and ADF-4, which are both proline rich, by employing the baculovirus expression system. Whereas ADF-3 represented an intrinsically soluble protein, ADF-4 was insoluble in vitro and self-assembled into filaments in the cytosol of the host insect cells. These ADF-4 filaments displayed the exceptional chemical stability of authentic silk threads. We provide evidence that the observed properties of ADF-3 and ADF-4 strongly depend on intrinsic characteristics such as hydropathicity, which differs dramatically between the two proteins, as in most other pairs of dragline silk proteins from other Araneoidea species, but not on their proline content. Our findings shed new light on the structural components of spider dragline silk, allowing further elucidation of their assembly properties, which may open the door for commercial applications. 相似文献
34.
BACKGROUND: Neurons in primary auditory cortex are known to be sensitive to the locations of sounds in space, but the reference frame for this spatial sensitivity has not been investigated. Conventional wisdom holds that the auditory and visual pathways employ different reference frames, with the auditory pathway using a head-centered reference frame and the visual pathway using an eye-centered reference frame. Reconciling these discrepant reference frames is therefore a critical component of multisensory integration. RESULTS: We tested the reference frame of neurons in the auditory cortex of primates trained to fixate visual stimuli at different orbital positions. We found that eye position altered the activity of about one third of the neurons in this region (35 of 113, or 31%). Eye position affected not only the responses to sounds (26 of 113, or 23%), but also the spontaneous activity (14 of 113, or 12%). Such effects were also evident when monkeys moved their eyes freely in the dark. Eye position and sound location interacted to produce a representation for auditory space that was neither head- nor eye-centered in reference frame. CONCLUSIONS: Taken together with emerging results in both visual and other auditory areas, these findings suggest that neurons whose responses reflect complex interactions between stimulus position and eye position set the stage for the eventual convergence of auditory and visual information. 相似文献
35.
Development of arbuscular mycorrhizal (AM) symbiosis with plant root system in term of molecular and cellular events have been analysed. A role of AM symbiosis in plant life has been discussed. Molecular methods for analysis of arbuscular mycorrhizal fungi have been described. 相似文献
36.
A novel founder mutation in the RNASEL gene, 471delAAAG,is associated with prostate cancer in Ashkenazi Jews 总被引:7,自引:0,他引:7
Rennert H Bercovich D Hubert A Abeliovich D Rozovsky U Bar-Shira A Soloviov S Schreiber L Matzkin H Rennert G Kadouri L Peretz T Yaron Y Orr-Urtreger A 《American journal of human genetics》2002,71(4):981-984
HPC1/RNASEL was recently identified as a candidate gene for hereditary prostate cancer. We identified a novel founder frameshift mutation in RNASEL, 471delAAAG, in Ashkenazi Jews. The mutation frequency in the Ashkenazi population, estimated on the basis of the frequency in 150 healthy young women, was 4% (95% confidence interval [CI] 1.9%-8.4%). Among Ashkenazi Jews, the mutation frequency was higher in patients with prostate cancer (PRCA) than in elderly male control individuals (6.9% vs. 2.4%; odds ratio = 3.0; 95% CI 0.6-15.3; P=.17). 471delAAAG was not detected in the 134 non-Ashkenazi patients with PRCA and control individuals tested. The median age at PRCA diagnosis did not differ significantly between the Ashkenazi carriers and noncarriers included in our study. However, carriers received diagnoses at a significantly earlier age, compared with patients with PRCA who were registered in the Israeli National Cancer Registry (65 vs. 74.4 years, respectively; P<.001). When we examined two brothers with PRCA, we found a heterozygous 471delAAAG mutation in one and a homozygous mutation in the other. Loss of heterozygosity was demonstrated in the tumor of the heterozygous sib. Taken together, these data suggest that the 471delAAAG null mutation is associated with PRCA in Ashkenazi men. However, additional studies are required to determine whether this mutation confers increased risk for PRCA in this population. 相似文献
37.
Safran M Solomon I Shmueli O Lapidot M Shen-Orr S Adato A Ben-Dor U Esterman N Rosen N Peter I Olender T Chalifa-Caspi V Lancet D 《Bioinformatics (Oxford, England)》2002,18(11):1542-1543
MOTIVATION: In the post-genomic era, functional analysis of genes requires a sophisticated interdisciplinary arsenal. Comprehensive resources are challenged to provide consistently improving, state-of-the-art tools. RESULTS: GeneCards (Rebhan et al., 1998) has made innovative strides: (a). regular updates and enhancements incorporating new genes enriched with sequences, genomic locations, cDNA assemblies, orthologies, medical information, 3D protein structures, gene expression, and focused SNP summaries; (b). restructured software using object-oriented Perl, migration to schema-driven XML, and (c). pilot studies, introducing methods to produce cards for novel and predicted genes. 相似文献
38.
Katz U Rozman A Gabbay S 《Journal of experimental zoology. Part A, Comparative experimental biology》2003,298(1):1-9
The onset of active Na(+) transport and activated Cl(-) conductance (G(Cl)) across the skin epithelium of Pelobates syriacus was investigated during natural ontogenetic development. Structural features, including band three and Peanut lectin bindings were tested in parallel and structure-function relationships were attempted. The 22 specimens studied were divided into two tadpole, three juvenile, and two adult stages, corresponding to the Taylor-Kollros standard table, in accordance with external morphology of their developmental stage. Onset of transepithelial electrical potential and drop in conductance occurred abruptly, coinciding with metamorphosis climax of tadpoles into juveniles at about stage XXI of development. Amiloride-sensitive Na(+) transport occurred a little later at stage XXIII, followed by the appearance of activated Cl(-) conductance, G(Cl). Parallel structural examination showed that skin MR cells occurred upon metamorphosis, as the tadpole integument transformed into the adult epithelium and could be associated with the occurrence of activated G(Cl). It was not related temporally with the appearance of band three protein in MR cells. Our findings support the association of G(Cl) with MR cells, whereas band three may only be a corollary of G(Cl) and not necessarily essential for its manifestation. 相似文献
39.
Like higher plants, unicellular green algae of the genus Dunaliella respond to light stress by enhanced de-epoxidation of violaxanthin and accumulation of Cbr, a protein homologous to early
light-inducible proteins (Elips) in plants. Earlier studies indicated that Cbr was associated with the light-harvesting complex
of photosystem II (LHCII) and suggested it acted as a zeaxanthin-binding protein and fulfilled a photo-protective function
(Levy et al. 1993, J. Biol. Chem. 268: 20892–20896). To characterize the protein-pigment subcomplexes containing Cbr in greater
detail than attained so far, thylakoid membranes from Dunaliella salina grown in high light or normal light were solubilized with dodecyl maltoside and fractionated by isoelectric-focusing. Analysis
of the resolved LHCII subcomplexes indicated preferred associations among the four LHCIIb polypeptides and between them and
Cbr: subcomplexes including Cbr contained one or two of the more acidic of the four LHCIIb polypeptides as well as large amounts
of lutein and zeaxanthin relative to chlorophyll a/b. After sucrose gradient centrifugation, Cbr free of LHCIIb polypeptides
was detected together with released pigments; this Cbr possibly originated in subcomplexes dissociated in the course of the
analysis. These results agree with the conclusion that Cbr is part of the network of LHCIIb protein-pigment complexes and
suggest that the role played by Cbr involves the organization and/or stabilization of assemblies highly enriched in zeaxanthin
and lutein. Such assemblies may function to protect PSII from photodamage due to overexcitation.
Received: 6 August 1999 / Accepted: 23 November 1999 相似文献
40.
Sak K Uri A Enkvist E Raidaru G Subbi J Kelve M Järv J 《Biochemical and biophysical research communications》2000,272(2):327-331
Novel type antagonists for P2Y(1) adenine nucleotide receptors were synthesized by coupling of adenosine 5'-OH group with oligo-aspartate chain via a carbonyl linker. All these conjugates (AdoOC(O)Asp(n), n = 1-4) inhibited the 2MeSADP-stimulated synthesis of inositol phosphates in 1321N1 human astrocytoma cells stably expressing human P2Y(1) receptors. This inhibitory effect followed the rank order AdoOC(O)Asp(2)> AdoOC(O)Asp(3)> AdoOC(O)Asp(1)> AdoOC(O)Asp(4) with antagonistic constant pA(2) = 5.4 for AdoOC(O)Asp(2). Potency of this non-phosphate inhibitor was comparable with the previously known adenosine 3',5'- and 2', 5'-bisphosphates. Chemical and biological stabilities of these novel adenosine derived antagonists of the nucleotide receptor provide perspectives of their pharmacological implication. 相似文献