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排序方式: 共有255条查询结果,搜索用时 15 毫秒
11.
Abstract Opportunistic sightings and strandings of Caperea marginata (n=196) from the vicinity of Australia and New Zealand (1884 to early 2007) were used to relate geographic and temporal patterns to oceanographic and broad-scale climatic variability. Records were not uniformly distributed along the coast and more (69%) were from Australia than New Zealand. Seven coastal whale ‘hotspots’ were identified which accounted for 61% of records with locality data. Half of the hotspot records were from southeast (37) and northwest (20) Tasmania—others each had 9–15 events. Upwelling and/or high zooplankton abundance has been documented near all whale hotspots. Records of C. marginata occurred in all months, with 75% in spring and summer. Inter-annual variability showed broad agreement between increased whale records (usually in spring/summer) and strongly positive ‘Niño 3.4’ during 1980–1995 but not thereafter. Coastal upwelling and productivity increase during climatic phenomena such as El Niño and are likely to be quickly beneficial to plankton-feeding whales such as C. marginata. 相似文献
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An effective immune response against cancer requires the activation and expansion of specific T cells. Tumor antigens, however, are generally poor immunogens. To achieve expansion of tumor-reactive T cells in vivo, we used a strategy of generating dual-specific T cells that could respond to a powerful immunogen while also possessing tumor reactivity. We generated dual-specific T cells by genetic modification of alloreactive T cells with a chimeric receptor recognizing folate-binding protein, an ovarian cancer-associated antigen. Mouse dual-specific T cells responded in vitro to both allogeneic antigen and tumor cells expressing folate-binding protein, and expanded in number in vivo in response to immunization with allogeneic cells. Most importantly, the combination of dual-specific T cells and immunization had an antitumor effect in vivo. We also generated human dual-specific T cells and characterized the dual-specific nature of individual clones. Assigning the tasks of expansion and tumor reactivity to different receptors within the same lymphocyte may help to overcome the problem of poor immunogenicity of tumor antigens. 相似文献
15.
A novel disorder caused by defective biosynthesis of N-linked oligosaccharides due to glucosidase I deficiency 总被引:11,自引:0,他引:11
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De Praeter CM Gerwig GJ Bause E Nuytinck LK Vliegenthart JF Breuer W Kamerling JP Espeel MF Martin JJ De Paepe AM Chan NW Dacremont GA Van Coster RN 《American journal of human genetics》2000,66(6):1744-1756
Glucosidase I is an important enzyme in N-linked glycoprotein processing, removing specifically distal alpha-1,2-linked glucose from the Glc3Man9GlcNAc2 precursor after its en bloc transfer from dolichyl diphosphate to a nascent polypeptide chain in the endoplasmic reticulum. We have identified a glucosidase I defect in a neonate with severe generalized hypotonia and dysmorphic features. The clinical course was progressive and was characterized by the occurrence of hepatomegaly, hypoventilation, feeding problems, seizures, and fatal outcome at age 74 d. The accumulation of the tetrasaccharide Glc(alpha1-2)Glc(alpha1-3)Glc(alpha1-3)Man in the patient's urine indicated a glycosylation disorder. Enzymological studies on liver tissue and cultured skin fibroblasts revealed a severe glucosidase I deficiency. The residual activity was <3% of that of controls. Glucosidase I activities in cultured skin fibroblasts from both parents were found to be 50% of those of controls. Tissues from the patient subjected to SDS-PAGE followed by immunoblotting revealed strongly decreased amounts of glucosidase I protein in the homogenate of the liver, and a less-severe decrease in cultured skin fibroblasts. Molecular studies showed that the patient was a compound heterozygote for two missense mutations in the glucosidase I gene: (1) one allele harbored a G-->C transition at nucleotide (nt) 1587, resulting in the substitution of Arg at position 486 by Thr (R486T), and (2) on the other allele a T-->C transition at nt 2085 resulted in the substitution of Phe at position 652 by Leu (F652L). The mother was heterozygous for the G-->C transition, whereas the father was heterozygous for the T-->C transition. These base changes were not seen in 100 control DNA samples. A causal relationship between the alpha-glucosidase I deficiency and the disease is postulated. 相似文献
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Based on the tertiary structure of the ribosome-inactivating protein alpha-sarcin, domains that are responsible for hydrolyzing ribosomes and naked RNA have been dissected. In this study, we found that the head-to-tail interaction between the first amino beta-strand and the last carboxyl beta-strand is not involved in catalyzing the hydrolysis of ribosomes or ribonucleic acids. Instead, a four-strand pleated beta-sheet is indispensable for catalyzing both substrates, suggesting that alpha-sarcin and ribonuclease T1 (RNase T1) share a similar catalytic center. The integrity of an amino beta-hairpin and that of the loop L3 in alpha-sarcin are crucial for recognizing and hydrolyzing ribosomes in vitro and in vivo. However, a mutant protein without the beta-hairpin structure, or with a disrupted loop L3, is still capable of digesting ribonucleic acids. The functional involvement of the beta-hairpin and the loop L3 in the sarcin stem/loop RNA of ribosomes is demonstrated by a docking model, suggesting that the two structures are in essence naturally designed to distinguish ribosome-inactivating proteins from RNase T1 to inactivate ribosomes. 相似文献
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Characterization of terminal NeuNAcalpha2-3Galbeta1-4GlcNAc sequence in lipooligosaccharides of Neisseria meningitidis 总被引:1,自引:0,他引:1
Group B and C Neisseria meningitidis are the major cause of meningococcal
disease in the United States and in Europe. N . meningitidis
lipooligosaccharide (LOS), a major surface antigen, can be divided into 12
immunotypes of which L1 through L8 were found among Group B and C
organisms. Groups B and C but not Group A may sialylate their LOSs with
N-acetylneuraminic acid (NeuNAc) at the nonreducing end because they
synthesize CMP-NeuNAc. Using sialic acid-galactose binding lectins as
probes in an ELISA format, six of the eight LOS immunotypes (L2, L3, L4,
L5, L7, and L8) in Groups B and C bound specifically to Maackia amurensis
leukoagglutinin (MAL), which recognizes NeuNAcalpha2- 3Galbeta1-4GlcNAc/Glc
sequence, but not to Sambucus nigra agglutinin, which binds
NeuNAcalpha2-6Gal sequence. The combination of SDS-PAGE and MAL-blot
analyses revealed that these six LOSs contained only the
NeuNAcalpha2-3Galbeta1-4GlcNAc trisaccharide sequence in their 4.1 kDa LOS
components, which have a common terminal lacto-N-neotetraose (LNnT,
Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) structure when nonsialylated as shown
by previous studies. The LOS-lectin binding was abolished when the LOSs
were treated with Newcastle disease viral neuraminidase which cleaves
alpha2-->3 linked sialic acid. Methylation analysis of a representative
LOS (L2) confirmed that NeuNAc is 2-->3 linked to Gal. Thus, these LOSs
structurally mimic certain glycolipids, i.e., paragloboside (LNnT-ceramide)
and sialylparagloboside and some glycoproteins in having LNnT and
N-acetyllactosamine sequences, respectively, with or without alpha2-->3
linked NeuNAc. The molecular mimicry of the LOSs may play a role in the
pathogenesis of N.meningitidis by assisting the organism to evade host
immune defenses in man.
相似文献
18.
Pasquier CM; Promponas VI; Varvayannis NJ; Hamodrakas SJ 《Bioinformatics (Oxford, England)》1998,14(8):749-750
Summary : FT is a tool written in C++, which implements the Fourier
analysis method to locate periodicities in aminoacid or DNA sequences. It
is provided for free public use on a WWW server with a Java interface.
Availability : The server address is http://o2.db. uoa.gr/FT Contact :
shamodr@atlas.uoa.gr
相似文献
19.
Ja-an Annie Ho Li-Chen Wu Li-Hui Chang Kuo-Chu Hwang Jih-Ru Reuben Hwu 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(2):172-176
Immunoglobulin E (IgE)-mediated type I allergies affect over 25% of the world's population; they are among the most common diseases in developed countries. Therefore, simple and rapid in vivo and in vitro methods for diagnosing allergies are becoming increasingly important. In this paper, we demonstrate the feasibility of using sulforhodamine B, a fluorescent dye, entrapped inside immunoliposomes, the outer surfaces of which were sensitized with IgE, as a signal amplifier for the development of a simple, rapid, and inexpensive colorimetric affinity chromatographic immunoassay for the detection of total IgE in serum. This assay operates based on competition between standards (or human serum samples) containing IgE and IgE-sensitized immunoliposomes for the limited number of antigen binding sites of immobilized anti-IgE antibodies at the antigen capture (AC) zone on the nitrocellulose membranes. The color density of the AC zone is indirectly proportional to the number of IgE units present in the test sample. The detection limit of this liposome-based immunoaffinity chromatographic assay was 0.37 ng in IgE-free serum solution (equivalent to 20 μL of a 18.5 ng mL−1 solution). A commercially available ELISA kit was used as a reference method to validate the proposed assay through the analysis of three human serum samples. 相似文献
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