Snakes of the United States and Canada: By Carl H. Ernst and Evelyn M. Ernst. Smithsonian Institution Press, Washington and London. 2003. ISBN 1-58834-019-8 (cloth). 668pp. Price £54.00     

Peter Stafford 《Biological conservation》2004,117(3):357

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Structure of PTB bound to RNA: specific binding and implications for splicing regulation     

Oberstrass FC  Auweter SD  Erat M  Hargous Y  Henning A  Wenter P  Reymond L  Amir-Ahmady B  Pitsch S  Black DL  Allain FH 《Science (New York, N.Y.)》2005,309(5743):2054-2057

The polypyrimidine tract binding protein (PTB) is a 58-kilodalton RNA binding protein involved in multiple aspects of messenger RNA metabolism, including the repression of alternative exons. We have determined the solution structures of the four RNA binding domains (RBDs) of PTB, each bound to a CUCUCU oligonucleotide. Each RBD binds RNA with a different binding specificity. RBD3 and RBD4 interact, resulting in an antiparallel orientation of their bound RNAs. Thus, PTB will induce RNA looping when bound to two separated pyrimidine tracts within the same RNA. This leads to structural models for how PTB functions as an alternative-splicing repressor.  相似文献   

Plant Cell Wall Polymers. Biogenesis and Biodegradation. Norman G. Lewis and Michael G. Paice, Eds. American Chemical Society, Washington, DC, 1989. xii, 676 pp., illus. $119.95. ACS Symposium Series, vol. 399. From a symposium, Toronto, ON, June 1988     

Stafford HA 《Science (New York, N.Y.)》1990,247(4941):476-477

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Predictive thresholds for plague in Kazakhstan     

Davis S  Begon M  De Bruyn L  Ageyev VS  Klassovskiy NL  Pole SB  Viljugrein H  Stenseth NC  Leirs H 《Science (New York, N.Y.)》2004,304(5671):736-738

In Kazakhstan and elsewhere in central Asia, the bacterium Yersinia pestis circulates in natural populations of gerbils, which are the source of human cases of bubonic plague. Our analysis of field data collected between 1955 and 1996 shows that plague invades, fades out, and reinvades in response to fluctuations in the abundance of its main reservoir host, the great gerbil (Rhombomys opimus). This is a rare empirical example of the two types of abundance thresholds for infectious disease-invasion and persistence- operating in a single wildlife population. We parameterized predictive models that should reduce the costs of plague surveillance in central Asia and thereby encourage its continuance.  相似文献   

Editing of CD1d-bound lipid antigens by endosomal lipid transfer proteins   总被引：3，自引：0，他引：3  

Zhou D  Cantu C  Sagiv Y  Schrantz N  Kulkarni AB  Qi X  Mahuran DJ  Morales CR  Grabowski GA  Benlagha K  Savage P  Bendelac A  Teyton L 《Science (New York, N.Y.)》2004,303(5657):523-527

It is now established that CD1 molecules present lipid antigens to T cells, although it is not clear how the exchange of lipids between membrane compartments and the CD1 binding groove is assisted. We report that mice deficient in prosaposin, the precursor to a family of endosomal lipid transfer proteins (LTP), exhibit specific defects in CD1d-mediated antigen presentation and lack Valpha14 NKT cells. In vitro, saposins extracted monomeric lipids from membranes and from CD1, thereby promoting the loading as well as the editing of lipids on CD1. Transient complexes between CD1, lipid, and LTP suggested a "tug-of-war" model in which lipid exchange between CD1 and LTP is on the basis of their respective affinities for lipids. LTPs constitute a previously unknown link between lipid metabolism and immunity and are likely to exert a profound influence on the repertoire of self, tumor, and microbial lipid antigens.  相似文献   

Neuroscience. Brain under surveillance: the microglia patrol     

Fetler L  Amigorena S 《Science (New York, N.Y.)》2005,309(5733):392-393

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Historical essay. A history of HIV discovery     

Montagnier L 《Science (New York, N.Y.)》2002,298(5599):1727-1728

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Microbial community composition and carbon cycling within soil microenvironments of conventional, low-input, and organic cropping systems   总被引：1，自引：0，他引：1  

Kong AY  Scow KM  Córdova-Kreylos AL  Holmes WE  Six J 《Soil biology & biochemistry》2011,43(1):20-30

This study coupled stable isotope probing with phospholipid fatty acid analysis (¹³C-PLFA) to describe the role of microbial community composition in the short-term processing (i.e., C incorporation into microbial biomass and/or deposition or respiration of C) of root- versus residue-C and, ultimately, in long-term C sequestration in conventional (annual synthetic fertilizer applications), low-input (synthetic fertilizer and cover crop applied in alternating years), and organic (annual composted manure and cover crop additions) maize-tomato (Zea mays - Lycopersicum esculentum) cropping systems. During the maize growing season, we traced ¹³C-labeled hairy vetch (Vicia dasycarpa) roots and residues into PLFAs extracted from soil microaggregates (53-250 μm) and silt-and-clay (<53 μm) particles. Total PLFA biomass was greatest in the organic (41.4 nmol g⁻¹ soil) and similar between the conventional and low-input systems (31.0 and 30.1 nmol g⁻¹ soil, respectively), with Gram-positive bacterial PLFA dominating the microbial communities in all systems. Although total PLFA-C derived from roots was over four times greater than from residues, relative distributions (mol%) of root- and residue-derived C into the microbial communities were not different among the three cropping systems. Additionally, neither the PLFA profiles nor the amount of root- and residue-C incorporation into the PLFAs of the microaggregates were consistently different when compared with the silt-and-clay particles. More fungal PLFA-C was measured, however, in microaggregates compared with silt-and-clay. The lack of differences between the mol% within the microbial communities of the cropping systems and between the PLFA-C in the microaggregates and the silt-and-clay may have been due to (i) insufficient differences in quality between roots and residues and/or (ii) the high N availability in these N-fertilized cropping systems that augmented the abilities of the microbial communities to process a wide range of substrate qualities. The main implications of this study are that (i) the greater short-term microbial processing of root- than residue-C can be a mechanistic explanation for the higher relative retention of root- over residue-C, but microbial community composition did not influence long-term C sequestration trends in the three cropping systems and (ii) in spite of the similarity between the microbial community profiles of the microaggregates and the silt-and-clay, more C was processed in the microaggregates by fungi, suggesting that the microaggregate is a relatively unique microenvironment for fungal activity.  相似文献   

Assessment of motor pathways by magnetic stimulation in human and veterinary medicine     

Iris Van Soens  Luc M. Van Ham 《Veterinary journal (London, England : 1997)》2011,187(2):174-181

Magnetic stimulation is a non-invasive and painless technique for studying the motor pathways in medical neurology. A time-varying magnetic field induces an electrical field in conducting objects, such as nervous tissue. The technique can be applied to nerve roots and peripheral nerves or to the motor cortex of the brain in human and veterinary medicine. In this review, the basic principles, applications and risk factors of peripheral nerve and motor cortex stimulation in human and veterinary medicine are discussed.  相似文献   

Risk factors and clinical presentation of cats with feline idiopathic cystitis     

Defauw PA  Van de Maele I  Duchateau L  Polis IE  Saunders JH  Daminet S 《Journal of Feline Medicine and Surgery》2011,13(12):967-975

Feline idiopathic cystitis (FIC) is the most common cause of feline lower urinary tract disease (FLUTD). This retrospective, case-controlled study evaluated possible risk factors associated with FIC and compared different clinical presentations in 64 cats with FIC. Several risk factors known to be involved in FLUTD were identified as playing a role in FIC. Of the stressful situations considered, most did not occur with increased frequency in cats with FIC compared to controls, except for a house move. The presence of pyuria, haematuria and an increased urine protein:creatinine ratio were significantly higher in obstructed males compared with non-obstructed males. An obstruction was significantly more likely in cats with struvite crystalluria compared with cats without struvite crystalluria. These findings suggest that urethral plugs might be an important cause or contributing factor of obstruction in FIC. Episodes of FIC seem to occur mainly in susceptible cats in combination with a deficient environment.  相似文献