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971.
MicroRNAs (miRNAs) are non-coding small RNAs of ~22 nt that regulate the gene expression by base pairing with target mRNAs, leading to mRNA cleavage or translational repression. It is currently estimated that miRNAs account for ~1% of predicted genes in higher eukaryotic genomes and that up to 30% of genes might be regulated by miRNAs. However, only very few miRNAs have been functionally characterized and the general functions of miRNAs are not globally studied. In this study, we systematically analyzed the expression patterns of miRNA targets using several public microarray profiles. We found that the expression levels of miRNA targets are lower in all mouse and Drosophila tissues than in the embryos. We also found miRNAs more preferentially target ubiquitously expressed genes than tissue-specifically expressed genes. These results support the current suggestion that miRNAs are likely to be largely involved in embryo development and maintaining of tissue identity. 相似文献
972.
Celedón JC Soto-Quiros ME Avila L Lake SL Liang C Fournier E Spesny M Hersh CP Sylvia JS Hudson TJ Verner A Klanderman BJ Freimer NB Silverman EK Weiss ST 《Human genetics》2007,120(5):691-699
Although asthma is a major public health problem in certain Hispanic subgroups in the United States and Latin America, only
one genome scan for asthma has included Hispanic individuals. Because of small sample size, that study had limited statistical
power to detect linkage to asthma and its intermediate phenotypes in Hispanic participants. To identify genomic regions that
contain susceptibility genes for asthma and airway responsiveness in an isolated Hispanic population living in the Central
Valley of Costa Rica, we conducted a genome-wide linkage analysis of asthma (n = 638) and airway responsiveness (n = 488) in members of eight large pedigrees of Costa Rican children with asthma. Nonparametric multipoint linkage analysis
of asthma was conducted by the NPL-PAIR allele-sharing statistic, and variance component models were used for the multipoint
linkage analysis of airway responsiveness as a quantitative phenotype. All linkage analyses were repeated after exclusion
of the phenotypic data of former and current smokers. Chromosome 12q showed some evidence of linkage to asthma, particularly
in nonsmokers (P < 0.01). Among nonsmokers, there was suggestive evidence of linkage to airway responsiveness on chromosome 12q24.31 (LOD = 2.33
at 146 cM). After genotyping 18 additional short-tandem repeat markers on chromosome 12q, there was significant evidence of
linkage to airway responsiveness on chromosome 12q24.31 (LOD = 3.79 at 144 cM), with a relatively narrow 1.5-LOD unit support
interval for the observed linkage peak (142–147 cM). Our results suggest that chromosome 12q24.31 contains a locus (or loci)
that influence a critical intermediate phenotype of asthma (airway responsiveness) in Costa Ricans.
This work was supported by grants HL04370 and HL66289 from the National Institutes of Health. 相似文献
973.
The influence of female and male cues on the male searching behavior of the sheep tick, Ixodes ricinus (Acari: Ixodidae), was studied under constant laboratory conditions by means of a computerized video tracking system. Males
were released into an open glass arena in which one half had been exposed for 1 h to 5 freely walking unfed females or five
males. The obtained track data were analyzed to reveal if male walking pattern was random or affected by cues of conspecifics
left on the arena surface. The results showed that males spent significantly more time and walked a significantly longer distance
in the area with female cues compared to the control area. Moreover, the walking path of males was more tortuous on the cues
half than the control half. In contrast, walking behavior of males was not affected by male cues in any observed parameter.
These results provide the first evidence that unfed females leave sex-specific semiochemicals on a substrate during their
walk and that these cues have an effect on male searching behavior. Since this effect was not observed when female cues were
24-h old, the semiochemicals seem to either evaporate or are subject to degradation. The biological significance of these
findings for mate-searching in I. ricinus males is discussed. 相似文献
974.
Duarte AM de Jong ER Wechselberger R van Mierlo CP Hemminga MA 《Biochimica et biophysica acta》2007,1768(9):2263-2270
A 900-MHz NMR study is reported of peptide sMTM7 that mimics the cytoplasmic proton hemi-channel domain of the seventh transmembrane segment (TM7) from subunit a of H(+)-V-ATPase from Saccharomyces cerevisiae. The peptide encompasses the amino acid residues known to actively participate in proton translocation. In addition, peptide sMTM7 contains the amino acid residues that upon mutation cause V-ATPase to become resistant against the inhibitor bafilomycin. 2D TOCSY and NOESY (1)H-(1)H NMR spectra are obtained of sMTM7 dissolved in d(6)-DMSO and are used to calculate the three-dimensional structure of the peptide. The NMR-based structures and corresponding dynamical features of peptide sMTM7 show that sMTM7 is composed of two alpha-helical regions. These regions are separated by a flexible hinge of two residues. The hinge acts as a ball-and-joint socket and both helical segments move independently with respect to one another. This movement in TM7 is suggested to cause the opening and closing of the cytoplasmic proton hemi-channel and enables proton translocation. 相似文献
975.
Xu X Mannik J Kudryavtseva E Lin KK Flanagan LA Spencer J Soto A Wang N Lu Z Yu Z Monuki ES Andersen B 《Developmental biology》2007,312(2):484-500
The homeostasis of both cornea and hair follicles depends on a constant supply of progeny cells produced by populations of keratin (K) 14-expressing stem cells localized in specific niches. To investigate the potential role of Co-factors of LIM domains (Clims) in epithelial tissues, we generated transgenic mice expressing a dominant-negative Clim molecule (DN-Clim) under the control of the K14 promoter. As expected, the K14 promoter directed high level expression of the transgene to the basal cells of cornea and epidermis, as well as the outer root sheath of hair follicles. In corneal epithelium, the transgene expression causes decreased expression of adhesion molecule BP180 and defective hemidesmosomes, leading to detachment of corneal epithelium from the underlying stroma, which in turn causes blisters, wounds and an inflammatory response. After a period of epithelial thinning, the corneal epithelium undergoes differentiation to an epidermis-like structure. The K14-DN-Clim mice also develop progressive hair loss due to dysfunctional hair follicles that fail to generate hair shafts. The number of hair follicle stem cells is decreased by at least 60% in K14-DN-Clim mice, indicating that Clims are required for hair follicle stem cell maintenance. In addition, Clim2 interacts with Lhx2 in vivo, suggesting that Clim2 is an essential co-factor for the LIM homeodomain factor Lhx2, which was previously shown to play a role in hair follicle stem cell maintenance. Together, these data indicate that Clim proteins play important roles in the homeostasis of corneal epithelium and hair follicles. 相似文献
976.
The reduced expression of the HADH2 protein causes X-linked mental retardation, choreoathetosis, and abnormal behavior 下载免费PDF全文
977.
978.
Price ER Paladino FV Strohl KP Santidrián T P Klann K Spotila JR 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2007,146(3):422-428
The pattern and control of respiration is virtually unknown in hatchling sea turtles. Using incubator-raised turtles, we measured oxygen consumption, frequency, tidal volume, and minute volume for leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) turtle hatchlings for the first six days after pipping. In addition, we tested the hatchlings' response to hypercapnic, hyperoxic, and hypoxic challenges over this time period. Hatchling sea turtles generally showed resting ventilation characteristics that are similar to those of adults: a single breath followed by a long respiratory pause, slow frequency, and high metabolic rate. With hypercapnic challenge, both species responded primarily by elevating respiratory frequency via a decrease in the non-ventilatory period. Leatherback resting tidal volume increased with age but otherwise, neither species' resting respiratory pattern nor response to gas challenge changed significantly over the first few days after hatching. At the time of nest emergence, sea turtles have achieved a respiratory pattern that is similar to that of actively diving adults. 相似文献
979.
Wijayanti Nastiti Gazali Faris Muhammad Supriyati Endah Hakim Mohamad Saifudin Arguni Eggi Daniwijaya Marselinus Edwin Widyanto Nuryastuti Titik Nuhamunada Matin Nabilla Rahma Haryana Sofia Mubarika Wibawa Tri 《International microbiology》2022,25(3):531-540
International Microbiology - Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new virus responsible for the COVID-19 pandemic. The emergence of the new SARS-CoV-2 has been... 相似文献
980.
Myosin II isoforms with varying mechanochemistry and filament size interact with filamentous actin (F-actin) arrays to generate contractile forces in muscle and nonmuscle cells. How myosin II force production is shaped by isoform-specific motor properties and environmental stiffness remains poorly understood. Here, we used computer simulations to analyze force production by an ensemble of myosin motors against an elastically tethered actin filament. We found that force output depends on two timescales: the duration of F-actin attachment, which varies sharply with the ensemble size, motor duty ratio, and external load; and the time to build force, which scales with the ensemble stall force, gliding speed, and environmental stiffness. Although force-dependent kinetics were not required to sense changes in stiffness, the myosin catch bond produced positive feedback between the attachment time and force to trigger switch-like transitions from transient attachments, generating small forces, to high-force-generating runs. Using parameters representative of skeletal muscle myosin, nonmuscle myosin IIB, and nonmuscle myosin IIA revealed three distinct regimes of behavior, respectively: 1) large assemblies of fast, low-duty ratio motors rapidly build stable forces over a large range of environmental stiffness; 2) ensembles of slow, high-duty ratio motors serve as high-affinity cross-links with force buildup times that exceed physiological timescales; and 3) small assemblies of low-duty ratio motors operating at intermediate speeds are poised to respond sharply to changes in mechanical context—at low force or stiffness, they serve as low-affinity cross-links, but they can transition to force production via the positive-feedback mechanism described above. Together, these results reveal how myosin isoform properties may be tuned to produce force and respond to mechanical cues in their environment. 相似文献