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101.
Havill LM Snider CL Leland MM Hubbard GB Theriot SR Mahaney MC 《Journal of medical primatology》2003,32(3):131-138
Although published normative reference standards for hematologic and clinical chemistry measures are available for adult baboons, their applicability to infants has not been addressed. We analyzed these measures in 110 infant baboons (55 females and 55 males) from a large breeding colony at the Southwest Regional Primate Research Center in San Antonio, Texas. The sample consists of olive baboons and olive/yellow baboon hybrids, 1 week to 12 months of age. We produced cross-sectional reference values and examined the effects of age, sex, and subspecies on these variables. Hematology reference ranges for infant baboons are similar to, but wider than, those for adults. Reference ranges for blood biochemistry measures are generally more dissimilar to adults, indicating that for many variables, reference ranges for adult baboons are not adequate for infants. Although sex and subspecies differences are rare, age accounts for more than 10% of the variance in many of the variables. 相似文献
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104.
Dugan JE Hubbard DM Lastra M 《Journal of experimental marine biology and ecology》2000,255(2):229-245
To investigate factors related to the distribution of intertidal species, and specific predictions of the swash exclusion hypothesis for exposed sandy beaches, we compared the burrowing abilities and swash behavior of three species of anomuran crabs in the superfamily Hippoidea (Emerita analoga, Blepharipoda occidentalis and Lepidopa californica) which commonly inhabit the intertidal and shallow subtidal zones of beaches along the California coast. Burrowing times in the laboratory increased significantly with crab size for all species in five sediment grain sizes ranging from fine sand to gravel (0.15 to 3.24 mm). For each species, burrowing times differed significantly among sand grain sizes, ranging from 0.3 to 21.5 s. Burrowing times for the hippid crab, E. analoga, were relatively constant across sediment types, while those of the albuneid crabs, B. occidentalis and L. californica, were rapid in fine to medium sands, and much slower in coarser sediments. Our results indicate that E. analoga is a substrate generalist while L. californica and B. occidentalis are substrate sensitive. Pre-burrowing times and behavior, distance moved, and burrowing times differed among the species in the swash zone. Combined times of preburrowing and burrowing were shorter than the swash period (6 s) for most E. analoga individuals. Fifty percent of the individuals of L. californica reached the substrate and burrowed in the swash period, while no individuals of B. occidentalis burrowed in that time. Pre-burrowing behavior and time may be valuable in explaining spatial and temporal patterns in the distribution of hippoid crabs on California beaches. Our results support predictions of the swash exclusion hypothesis concerning the burrowing and locomotory abilities of sandy beach macrofauna. The substrate generalist characteristics, and unique orientation and swimming abilities of the hippid crab, E. analoga, in intertidal swash may help explain the success of this species and its congeners, and have important implications for understanding patterns of macrofauna community structure on exposed sandy beaches in California and other regions. 相似文献
105.
Using experimental information to produce a model of the transmembrane domain of the ion channel phospholamban. 总被引:1,自引:1,他引:0 下载免费PDF全文
Molecular models of the transmembrane domain of the phospholamban pentamer have been generated by a computational method that uses the experimentally measured effects of systematic single-site mutations as a guiding force in the modeling procedure. This method makes the assumptions that 1) the phospholamban transmembrane domain is a parallel five-helix bundle, and 2) nondisruptive mutation positions are lipid exposed, whereas 3) disruptive or partially disruptive mutations are not. Our procedure requires substantially less computer time than systematic search methods, allowing rapid assessment of the effects of different experimental results on the helix arrangement. The effectiveness of the approach is investigated in test calculations on two helix-dimer systems of known structure. Two independently derived sets of mutagenesis data were used to define the restraints for generating models of phospholamban. Both resulting models are left-handed, highly symmetrical pentamers. Although the overall bundle geometry is very similar in the two models, the orientation of individual helices differs by approximately 50 degrees, resulting in different sets of residues facing the pore. This demonstrates how differences in restraints can have an effect on the model structures generated, and how the violation of these restraints can identify inconsistent experimental data. 相似文献
106.
glp-1 encodes a member of the highly conserved LIN-12/Notch family of receptors that mediates the mitosis/meiosis decision in the C. elegans germline. We have characterized three mutations that represent a new genetic and phenotypic class of glp-1 mutants, glp-1(Pro). The glp-1(Pro) mutants display gain-of-function germline pattern defects, most notably a proximal proliferation (Pro) phenotype. Each of three glp-1(Pro) alleles encodes a single amino acid change in the extracellular part of the receptor: two in the LIN-12/Notch repeats (LNRs) and one between the LNRs and the transmembrane domain. Unlike other previously described gain-of-function mutations that affect this region of LIN-12/Notch family receptors, the genetic behavior of glp-1(Pro) alleles is not consistent with simple hypermorphic activity. Instead, the mutant phenotype is suppressed by wild-type doses of glp-1. Moreover, a trans-heterozygous combination of two highly penetrant glp-1(Pro) mutations is mutually suppressing. These results lend support to a model for a higher-order receptor complex and/or competition among receptor proteins for limiting factors that are required for proper regulation of receptor activity. Double-mutant analysis with suppressors and enhancers of lin-12 and glp-1 further suggests that the functional defect in glp-1(Pro) mutants occurs prior to or at the level of ligand interaction. 相似文献
107.
Insulin's structural behavior and its relation to activity 总被引:3,自引:0,他引:3
This paper discusses the hypothesis that insulin undergoes a conformational change either before or during its binding to the receptor. The evidence for this is not conclusive but allows us to reconcile the following observations: (1) no chemical modification or deletion of invariant surface residues has abolished the hormone's activity—only reduced its potency. (2) Reduction in potency follows many modifications to different side chains, both variant and invariant. (3) There are insulins with perfectly preserved structure (by the criteria of aggregation, spectroscopy, and x-ray analysis) that have markedly reduced potency. (4) Insulins with disturbed structure still exhibit real, sometimes substantial activity. 相似文献
108.
Hormonal imprinting takes place at the first encounter of the hormone and receptor, and results in a changed binding capacity and reaction of the cell and its progeny generations. The imprinting effect of three amino acids and their oligopeptides is studied using fluorescent-labelled peptides. Glycine and lysine could provoke positive imprinting (increased binding in the progeny generations) for their own peptides, but alanine could not. Mostly positive imprinting was provoked by glycine and lysine peptides for their own peptides of different chain length. The optimal chain length provoking self-imprinting was four for glycine, two for lysine and three for alanine. Except in this case, alanine was neutral or provoked mostly negative imprinting. After reaching the optimal chain length, there is a decline in binding. Evolutionary conclusions are discussed. 相似文献
109.
Brownridge P Holman SW Gaskell SJ Grant CM Harman VM Hubbard SJ Lanthaler K Lawless C O'Cualain R Sims P Watkins R Beynon RJ 《Proteomics》2011,11(15):2957-2970
In this paper, we discuss the challenge of large-scale quantification of a proteome, referring to our programme that aims to define the absolute quantity, in copies per cell, of at least 4000 proteins in the yeast Saccharomyces cerevisiae. We have based our strategy on the well-established method of stable isotope dilution, generating isotopically labelled peptides using QconCAT technology, in which artificial genes, encoding concatenations of tryptic fragments as surrogate quantification standards, are designed, synthesised de novo and expressed in bacteria using stable isotopically enriched media. A known quantity of QconCAT is then co-digested with analyte proteins and the heavy:light isotopologues are analysed by mass spectrometry to yield absolute quantification. This workflow brings issues of optimal selection of quantotypic peptides, their assembly into QconCATs, expression, purification and deployment. 相似文献
110.
Membranes from adipocytes of adult and young rats have been compared. Phospholipid fatty acids from adult rats were more saturated than those from young rats. This difference was associated with a decreased fluidity in the membranes of the adult rats, which was inferred from measurements of fluorescence polarisation of the fluorescent probe, 1,6-diphenylhexa-1,3,5-triene. 相似文献