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1.
Stems bearing egg masses of the western tent caterpillar ( Malacosoma californicum ), collected in Arizona and northern New Mexico during 1977–1980, had mean diameters between 2.9 and 4 mm. Mean lengths of the egg masses were consistently between 11 and 14 mm. 相似文献
2.
A three-base-pair deletion in the peripherin-RDS gene in one form of retinitis pigmentosa. 总被引:59,自引:0,他引:59
G J Farrar P Kenna S A Jordan R Kumar-Singh M M Humphries E M Sharp D M Sheils P Humphries 《Nature》1991,354(6353):478-480
The group of retinopathies termed retinitis pigmentosa (RP) greatly contribute to visual dysfunction in man with a frequency of roughly 1 in 4,000. We mapped the first autosomal dominant RP (adRP) gene to chromosome 3q, close to the gene encoding rhodopsin, a rod photoreceptor pigment protein. Subsequently, mutations in this gene have been implicated as responsible for some forms of adRP. Another adRP gene has been mapped to chromosome 8p. A third adRP gene in a large Irish pedigree has been mapped to chromosome 6p, showing tight linkage with the gene for peripherin, a photoreceptor cell-specific glycoprotein, which is thus a strong candidate for the defective gene. We have now identified a three-base-pair deletion which results in the loss of one of a pair of highly conserved cysteine residues in the predicted third transmembrane domain of peripherin. This deletion segregates with the disease phenotype but is not present in unaffected controls, and suggests that mutant peripherin gives rise to retinitis pigmentosa. 相似文献
3.
Stimulation of specific GTP binding and hydrolysis activities in lymphocyte membrane by interleukin-2 总被引:3,自引:0,他引:3
Interleukin-2 (IL-2) is a polypeptide growth factor which stimulates the proliferation and differentiation of T lymphocytes. The receptor for IL-2 is expressed on activated T lymphocytes, cloned IL-2 dependent cells and several other cell types. Analysis of the primary structure and of immune-precipitated receptor suggests that this molecule has no intrinsic signal transduction function, unlike other growth factors. IL-2 interaction with a high affinity receptor has been shown, however, to activate the calcium/phospholipid-dependent protein kinase C (PK-C) presumably via phosphoinositide hydrolysis. Members of a family of closely related guanine nucleotide binding proteins (G proteins) regulate a diverse group of metabolic events. Two of them, Gs and Gi, stimulate and inhibit adenylate cyclase activity respectively, and other G proteins are involved in diverse signal transduction system. Another member, Go, has no known function and activation of phospholipase C has been attributed to the action of an unidentified G protein, Gp. Since it has been observed that IL-2 inhibits the catalytic activity of adenylate cyclase and that agents such as PGE2 which stimulate adenylate cyclase activity inhibit the lymphoproliferative response to IL-2, association of GTP binding proteins with IL-2 signal transduction was investigated. In this report we describe for the first time the participation of a GTP binding protein in the action of a polypeptide growth factor, interleukin-2. 相似文献
4.
Complete genome sequence of a multiple drug resistant Salmonella enterica serovar Typhi CT18. 总被引:33,自引:0,他引:33
J Parkhill G Dougan K D James N R Thomson D Pickard J Wain C Churcher K L Mungall S D Bentley M T Holden M Sebaihia S Baker D Basham K Brooks T Chillingworth P Connerton A Cronin P Davis R M Davies L Dowd N White J Farrar T Feltwell N Hamlin A Haque T T Hien S Holroyd K Jagels A Krogh T S Larsen S Leather S Moule P O'Gaora C Parry M Quail K Rutherford M Simmonds J Skelton K Stevens S Whitehead B G Barrell 《Nature》2001,413(6858):848-852
Salmonella enterica serovar Typhi (S. typhi) is the aetiological agent of typhoid fever, a serious invasive bacterial disease of humans with an annual global burden of approximately 16 million cases, leading to 600,000 fatalities. Many S. enterica serovars actively invade the mucosal surface of the intestine but are normally contained in healthy individuals by the local immune defence mechanisms. However, S. typhi has evolved the ability to spread to the deeper tissues of humans, including liver, spleen and bone marrow. Here we have sequenced the 4,809,037-base pair (bp) genome of a S. typhi (CT18) that is resistant to multiple drugs, revealing the presence of hundreds of insertions and deletions compared with the Escherichia coli genome, ranging in size from single genes to large islands. Notably, the genome sequence identifies over two hundred pseudogenes, several corresponding to genes that are known to contribute to virulence in Salmonella typhimurium. This genetic degradation may contribute to the human-restricted host range for S. typhi. CT18 harbours a 218,150-bp multiple-drug-resistance incH1 plasmid (pHCM1), and a 106,516-bp cryptic plasmid (pHCM2), which shows recent common ancestry with a virulence plasmid of Yersinia pestis. 相似文献
5.
James J. Farrar 《西北部美国博物学家》2011,59(4)
Arabis pulchra plants infected by the crucifer rust fungus ( Puccinia consimilis ) develop pseduoflowers. These pseudoflowers are characterized by stems with short internodes and numerous closely spaced, bright yellow leaves coated with a sweet sugary substance. Pseudoflowers do not resemble normal A. pulchra flowers. Pseudoflowers, leaves, and stems of A. pulchra plants infected with P. consimilis and true flowers, stems, and leaves of uninfected A. pulchra plants were fixed, embedded, sectioned, and stained using standard microtechniques. Epidermal, ground, and vascular tissues of true leaves, true petals and pseudopetals were examined and compared for anatomic differences. Examination of anatomic characteristics revealed that pseudopetals are modified leaves. 相似文献
6.
Yu W Ginjala V Pant V Chernukhin I Whitehead J Docquier F Farrar D Tavoosidana G Mukhopadhyay R Kanduri C Oshimura M Feinberg AP Lobanenkov V Klenova E Ohlsson R 《Nature genetics》2004,36(10):1105-1110
Chromatin insulators demarcate expression domains by blocking the cis effects of enhancers or silencers in a position-dependent manner. We show that the chromatin insulator protein CTCF carries a post-translational modification: poly(ADP-ribosyl)ation. Chromatin immunoprecipitation analysis showed that a poly(ADP-ribosyl)ation mark, which exclusively segregates with the maternal allele of the insulator domain in the H19 imprinting control region, requires the bases that are essential for interaction with CTCF. Chromatin immunoprecipitation-on-chip analysis documented that the link between CTCF and poly(ADP-ribosyl)ation extended to more than 140 mouse CTCF target sites. An insulator trap assay showed that the insulator function of most of these CTCF target sites is sensitive to 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase activity. We suggest that poly(ADP-ribosyl)ation imparts chromatin insulator properties to CTCF at both imprinted and nonimprinted loci, which has implications for the regulation of expression domains and their demise in pathological lesions. 相似文献
7.
Altered cytosol/membrane enzyme redistribution on interleukin-3 activation of protein kinase C 总被引:1,自引:0,他引:1
Interleukin-3 (IL-3) is a member of a family of growth and differentiation peptides, collectively referred to as colony-stimulating factors, which regulate haematopoiesis. IL-3 has been highly purified from medium conditioned by WEHI-3B cells, and recently the molecular cloning of complementary DNA for murine IL-3 has been reported. IL-3 seems to stimulate a wide range of colony-forming cells derived from murine bone marrow and has consequently been studied under a variety of names, including burst-promoting activity, mast cell growth factor, P-cell stimulating factor and multi-colony-stimulating factor. Here we present evidence that IL-3-receptor interaction stimulates the rapid and transient redistribution of protein kinase C (PK-C) from cytosol to plasma membrane in FDC-P1 cells. Phorbol myristate acetate (PMA) is shown to have a similar effect in these IL-3-dependent FDC-P1 cells. Our data suggest that IL-3 and phorbol esters share a common feature of transmembrane signalling crucial for growth and differentiation. 相似文献
8.
Interleukin-2 (IL-2) is a regulatory peptide important for the growth and differentiation of antigen-specific T lymphocytes and large granular lymphocytes. Interaction of IL-2 with its specific receptor results in the promotion of S-phase progression as well as, in certain circumstances, the production and release of gamma-interferon (IFN-gamma). Although the binding of IL-2 with high-affinity specific receptors has been well characterized, the intracellular mechanisms by which this ligand-receptor interaction promotes growth and differentiation are unknown. Here, we present evidence that IL-2/receptor interaction produces a rapid and transient redistribution of protein kinase C (PK-C) from the cytosol to the plasma membrane. Phorbol myristate acetate (PMA) also induces PK-C transposition in an analogous manner, except that PMA-induced PK-C transposition to the plasma membrane is apparently protracted. As phorbol esters have been shown to mimic IL-2 in the regulation of cellular proliferation as well as IFN-gamma production, the activation of PK-C by either phorbol esters or IL-2/receptor interaction seems to have a crucial role in signal transduction elicited by these extracellular messengers. 相似文献
9.
Whipple predicted the existence of micrometeorites, small interplanetary particles which enter the Earth's atmosphere without being melted by frictional heating. During the past 2 yr, large numbers of micrometre sized stratospheric particles have been collected which are believed to be extraterrestrial, because their elemental compositions closely match those of primitive meteorites. We report here the detection of large concentrations of 4He in some of the particles. This not only suggests an exposure to solar wind, but also indicates that these particles are true micrometeorites in the sense that they were not strongly heated by entry into the atmosphere. Strong heating would have caused much of the helium to escape. 相似文献
10.
KE Holt S Baker FX Weill EC Holmes A Kitchen J Yu V Sangal DJ Brown JE Coia DW Kim SY Choi SH Kim WD da Silveira DJ Pickard JJ Farrar J Parkhill G Dougan NR Thomson 《Nature genetics》2012,44(9):1056-1059
Shigella are human-adapted Escherichia coli that have gained the ability to invade the human gut mucosa and cause dysentery, spreading efficiently via low-dose fecal-oral transmission. Historically, S. sonnei has been predominantly responsible for dysentery in developed countries but is now emerging as a problem in the developing world, seeming to replace the more diverse Shigella flexneri in areas undergoing economic development and improvements in water quality. Classical approaches have shown that S. sonnei is genetically conserved and clonal. We report here whole-genome sequencing of 132 globally distributed isolates. Our phylogenetic analysis shows that the current S. sonnei population descends from a common ancestor that existed less than 500 years ago and that diversified into several distinct lineages with unique characteristics. Our analysis suggests that the majority of this diversification occurred in Europe and was followed by more recent establishment of local pathogen populations on other continents, predominantly due to the pandemic spread of a single, rapidly evolving, multidrug-resistant lineage. 相似文献