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排序方式: 共有157条查询结果,搜索用时 46 毫秒
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The isolation of cod muscle tropomyosin by heat treatment 总被引:1,自引:0,他引:1
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Summary Life history theory predicts that migratory fishes should delay reproduction, be larger at first reproduction, and have higher fecundities than nonmigrants. We tested this hypothesis by comparing life histories of anadromous (estuary) and resident freshwater (upstream) threespine sticklebacks (Gasterosteus aculeatus L.) from the Navarro River, California, USA. Using a split-brood, two-environment breeding design, families from cach population were divided and reared in both freshwater and seawater overwintering environments. In both treatments, the more migratory estuary sticklebacks were larger at first reproduction and had large initial clutch sizes; in the freshwater treatment, the estuary sticklebacks matured later than the upstream fish. Population means varied little across treatments, indicating that the average effects of the different overwintering conditions were slight. The responses of individual families to a given overwintering treatment were highly variable in both populations, as reflected in significant family x treatment effects for all traits. Phenotypic correlations among life history traits were significant and positive for most traits, and were similar in magnitude in both populations. Differences in the relative degree of specialization for migration may in part explain variation in life history between these populations. 相似文献
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1. The metabolism of VLD lipoproteins (very-low-density lipoproteins) was studied in intact isolated beating-heart cells and isolated perfused rat heart from starved animals by using [14C]triacylglycerol fatty acid-labelled VLD lipoprotein prepared from rats previously injected with [1-14C]palmitate. 2. 14C-labelled VLD lipoprotein was metabolized by the isolated perfused heart, but was only minimally metabolized by the heart cells unless an exogenous source of lipoprotein lipase was added. 3. Measurements of lipoprotein lipase at pH 7.4 with the natural substrate 14C-labelled VLD lipoprotein indicated that during collagenase perfusion of the heart the enzyme was released into the perfusate, the activity released being proportional to the concentration of collagenase used. Lipoprotein lipase activity in homogenates of hearts that had been perfused with collagenase showed a corresponding loss of activity. 4. At high perfusate concentrations of collagenase, inactivation of the released lipoprotein lipase occurred. 5. Lipoprotein lipase activity was largely undetectable in the homogenate of the isolated heart cells. 6. It is concluded that the lipoprotein lipase responsible for the hydrolysis of VLD lipoprotein triacylglycerol is predominantly located externally to the heart muscle cells and that its release can be facilitated by perfusion of the heart with bacterial collagenase. 相似文献
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Interaction of dinitrophenyl-pepstatins with human cathepsin D and with anti-dinitrophenyl antibody. Development of potential reagents for the localization in vivo of active proteinases at sites of tissue injury. 下载免费PDF全文
C G Knight W Hornebeck I T Matthews R M Hembry J T Dingle 《The Biochemical journal》1980,191(3):835-843
Extracellular cathepsin D has been observed by various cytochemical methods at sites of tissue injury. However, the role of this enzyme in connective tissue matrix degradation is uncertain because there are no histochemical methods for determining whether or not the cathepsin D is active at such sites in living tissues. We considered that the combined use of a labelled tight-binding inhibitor with immunoprecipitation of the enzymes might overcome this problem. We have explored the application of derivatives of the inhibitor pepstatin, as only active cathepsin D binds pepstatin tightly. A series of N-pepstatinyl-N'-dinitrophenyl-alpha, omega-diaminoalkanes were synthesized with alkyl-chain lengths of two, four and six carbon atoms. These compounds were tight-binding inhibitors of human cathepsin D. In fluorescence-quenching titrations the dinitrophenyl groups were also fully available to bind high-affinity anti-dinitrophenyl antibody. It was shown by immunodiffusion in gels and by gel permeation chromatography that N-pepstatinyl-N'-dinitrophenyl-1,6-diaminohexane was a bifunction inhibitor able to bind cathepsin D and anti-dinitrophenyl antibody at the same time. 相似文献
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G E Kempson M A Tuke J T Dingle A J Barrett P H Horsfield 《Biochimica et biophysica acta》1976,428(3):741-760
The effects of the lysosomal proteinase cathepsin D on the mechanical properties of adult human articular cartilage were examined in detail in 7 joints within the age range 21 to 72 years. The results of a preliminary study on the effects of the lysosomal proteinase cathepsin B1 and clostridial collagenase on the mechanical properties of cartilage are also presented. Cartilage which had been incubated with either cathepsin D or cathepsin B1 showed increased deformation in uniaxial compression perpendicular to the articular surface. The enzyme-treated cartilage also showed decreased tensile stiffness at low values of stress. This effect was more pronounced in specimens from the deeper zone of cartilage than in specimens from the superficial zone. It was also more pronounced in specimens which were aligned perpendicular to the predominant alignment of the collagen fibres in the superficial zone than in specimens which were parallel to the collagen fibres. At higher stresses the tensile stiffness of the treated cartilage was not significantly different from that of the untreated tissue. The tensile fracture stress of the cartilage was also not significantly reduced by the action of cathepsin D. In contrast to the effects observed with the cathepsins, the preliminary results obtained by incubating cartilage for 24 h with clostridial collagenase showed that both the tensile stiffness and the fracture stress were considerably lower than the corresponding values for the untreated tissue. Biochemical analysis of the incubation media, and the specimens, revealed that a large proportion of the proteoglycans was released from the cartilage by each of the three enzymes. The proportion of the total collagen which was released from the cartilage was different for each enzyme: cathepsin D released between 0 and 1.5 per cent, cathepsin B1 released between 2.3 and 4.3 per cent and collagenase released between 5.3 and 27.8 per cent of the collagen after 24 h. 相似文献
9.
Bridgette M. Dingle Yuying Liu Nicole Y. Fatheree Juleen Min J. Marc Rhoads Dat Q. Tran 《PloS one》2013,8(12)
Necrotizing enterocolitis (NEC) results from severe intestinal inflammation in premature infants. FoxP3+ regulatory T cells (Tregs) are central to gut homeostasis. While Treg proportions are significantly reduced in the ileums of premature infants with NEC, it is unknown whether they play a critical function in preventing NEC. This study investigated Treg development in newborn rat pups and their role in experimental NEC induction. Utilizing an established rat model of experimental NEC, the ontogeny of T cells and Tregs in newborn pups was characterized by flow cytometry. To investigate the functions of Tregs, newborn pups were given Tregs harvested from adult rats prior to NEC induction to assess clinical improvement and mechanisms of immune regulation. The results revealed that there were few Treg numbers in the terminal ileums of newborn rats and 8-fold reduction after NEC. Adoptive transfer of Tregs significantly improved weight loss, survival from 53% to 88%, and NEC incidence from 87% to 35%. The Tregs modulated the immune response as manifested in reduced CD80 expression on antigen presenting cells and decreased T cell activation within the mesenteric lymph nodes. These findings suggest that while Tregs are present in the intestines, their numbers might be insufficient to dampen the excessive inflammatory state in NEC. Adoptive transfer of Tregs attenuates the severity of NEC by limiting the immune response. Strategies to enhance Tregs have a therapeutic potential in controlling the development of NEC. 相似文献
10.
A Modified RNA-Seq Approach for Whole Genome Sequencing of RNA Viruses from Faecal and Blood Samples
Elizabeth M. Batty T. H. Nicholas Wong Amy Trebes Karène Argoud Moustafa Attar David Buck Camilla L. C. Ip Tanya Golubchik Madeleine Cule Rory Bowden Charis Manganis Paul Klenerman Eleanor Barnes A. Sarah Walker David H. Wyllie Daniel J. Wilson Kate E. Dingle Tim E. A. Peto Derrick W. Crook Paolo Piazza 《PloS one》2013,8(6)
To date, very large scale sequencing of many clinically important RNA viruses has been complicated by their high population molecular variation, which creates challenges for polymerase chain reaction and sequencing primer design. Many RNA viruses are also difficult or currently not possible to culture, severely limiting the amount and purity of available starting material. Here, we describe a simple, novel, high-throughput approach to Norovirus and Hepatitis C virus whole genome sequence determination based on RNA shotgun sequencing (also known as RNA-Seq). We demonstrate the effectiveness of this method by sequencing three Norovirus samples from faeces and two Hepatitis C virus samples from blood, on an Illumina MiSeq benchtop sequencer. More than 97% of reference genomes were recovered. Compared with Sanger sequencing, our method had no nucleotide differences in 14,019 nucleotides (nt) for Noroviruses (from a total of 2 Norovirus genomes obtained with Sanger sequencing), and 8 variants in 9,542 nt for Hepatitis C virus (1 variant per 1,193 nt). The three Norovirus samples had 2, 3, and 2 distinct positions called as heterozygous, while the two Hepatitis C virus samples had 117 and 131 positions called as heterozygous. To confirm that our sample and library preparation could be scaled to true high-throughput, we prepared and sequenced an additional 77 Norovirus samples in a single batch on an Illumina HiSeq 2000 sequencer, recovering >90% of the reference genome in all but one sample. No discrepancies were observed across 118,757 nt compared between Sanger and our custom RNA-Seq method in 16 samples. By generating viral genomic sequences that are not biased by primer-specific amplification or enrichment, this method offers the prospect of large-scale, affordable studies of RNA viruses which could be adapted to routine diagnostic laboratory workflows in the near future, with the potential to directly characterize within-host viral diversity. 相似文献