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1.
High levels of expression of full length human pro-alpha 2(V) collagen cDNA in pro-alpha 2(V)-deficient hamster cells 总被引:2,自引:0,他引:2
A full length cDNA encoding human pro-alpha 2(V) collagen was constructed. Partial sequencing of the cDNA and primer extension analysis of mRNA from fibroblasts found that pro-alpha 2(V) mRNA differs from the mRNAs of other fibrillar collagens in the increased length of its 5'-untranslated region. The pro-alpha 2(V) cDNA was placed downstream of the human cytomegalovirus immediate early promoter/regulatory sequences for expression studies in cultured Chinese hamster lung cells. These cells have been shown previously to synthesize large quantities of pro-alpha 1(V) homotrimers as their only collagenous product. Transfection resulted in a number of clonal cell lines that express human alpha 2(V) RNA at levels comparable to, and in some cases greater than, levels found in normal human skin fibroblasts. Pro-alpha 2(V) chains produced in the majority of clonal lines were of sufficient quantity to complex all available endogenous pro-alpha 1(V) chains. Chimeric heterotrimers, composed of hamster alpha 1(V) and human alpha 2(V) chains in a 2:1 ratio, were stable to pepsin digestion and were found predominantly associated with the cell layer. Surprisingly, pro-alpha 2(V) chains, in excess to pro-alpha 1(V) chains, were found in the extracellular matrix and, in much greater abundance, in media. These chains were pepsin sensitive, indicating that pro-alpha 2(V) chains can be secreted as nonstable homotrimers or as free chains. 相似文献
2.
On fluid-mechanical simulations of cell division and movement 总被引:2,自引:0,他引:2
H P Greenspan 《Journal of theoretical biology》1978,70(1):125-134
Demonstrations are presented of the possible effects of variable surface tension and dynamical instability in cell cleavage and the formation of a contractile belt. Analysis of a theoretical absorption/desorption model of chemotaxis suggested by these experiments shows that occasional, unidirectional amoeboid movement can occur in an oscillatory field of chemical attractant. 相似文献
3.
W J Monafo N S Greenspan J A Cebra-Thomas J M Davie 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(8):2702-2707
Using monoclonal anti-idiotopes with previously defined specificities for the variable (V) domain of HGAC 39, a monoclonal antibody against streptococcal group A carbohydrate (GAC), we have studied the effect of anti-idiotope on an anticarbohydrate immune response. Anti-IdI-3a and anti-IdI-3b are anti-idiotopes which recognize binding site-associated determinants, whereas anti-IdX recognizes a framework-associated determinant on the HGAC 39 V kappa domain. Each of three anti-idiotopes elicited a specific idiotope response, as measured by inhibition radioimmunoassay, in A/J and C57BL/6J mice. A single immunization with conjugated anti-IdI-3a elicited an idiotope(+), GAC-binding(+) response in C57BL/6J and (BALB/c X CBA/N)F1 male mice, but not in A/J or (CBA/N X BALB/c)F1 male, X-linked immunodeficient mice. When C57BL/6J mice immunized initially with anti-idiotope were further treated with group A vaccine, those receiving anti-IdX had the greatest increase in anti-GAC activity. Stimulation of an anticarbohydrate response with anti-idiotope may therefore be enhanced by selecting anti-idiotopes against both binding site- and framework-associated determinants. 相似文献
4.
Type V collagen is a fibrillar collagen that is widely distributed in tissues as a minor component of extracellular matrix and is usually composed of one pro alpha 2 (V) and two pro alpha 1 (V) chains. In this report, recently isolated cDNA and genomic clones, which encode the pro alpha 1 (V) chain, are used as probes for hybridization to filter-bound DNA from a panel of human-mouse hybrid cell lines and for in situ hybridization to metaphase chromosomes. These studies establish the chromosomal location of the COL5A1 gene, which encodes the pro alpha 1 (V) chain, within segment 9q34.2----q34.3. These findings add to the previously characterized dispersion of collagen genes in the human genome, as this is the first example of a collagen locus on chromosome 9. In addition, these studies place COL5A1 near the locus for the genetic disorder, nail-patella syndrome (hereditary osteo-onychodysplasia), which also maps to 9q34. 相似文献
5.
Dopaminergic regulation of gonadotropin and thyrotropin hormone secretion is altered with age. 总被引:1,自引:0,他引:1
To determine if age-related changes in glycoprotein pituitary hormone secretion are associated with alterations in dopaminergic regulation, plasma gonadotropins and TSH were measured before and after L-dopa administration in 44 young (31-44 years of age) and 42 old (64-88 years of age) healthy male participants. Plasma GH and PRL were also determined in order to examine the somatotroph and lactotrope response. In the young, following L-dopa, plasma FSH, LH and TSH were unchanged from baseline. However, in older subjects, plasma FSH was significantly increased (p less than 0.001) and a similar trend was noted for LH. Plasma TSH was significantly depressed (p less than 0.002) in older subjects only. Following L-dopa, increases in plasma GH and decreases in plasma PRL were of similar magnitude in each group. These data indicate that dopaminergic modulation of gonadotropins and TSH is altered with age. 相似文献
6.
Application of Nile red, a fluorescent hydrophobic probe, for the detection of neutral lipid deposits in tissue sections: comparison with oil red O 总被引:12,自引:0,他引:12
Nile red is a phenoxazone dye that fluoresces intensely, and in varying color, in organic solvents and hydrophobic lipids. However, the fluorescence is fully quenched in water. The dye acts, therefore, as a fluorescent hydrophobic probe. We utilized this novel property of nile red to develop a sensitive fluorescent histochemical stain for tissue lipids. Nile red was prepared by boiling Nile blue A under reflux for 2 hr in 0.5% H2SO4, and extracting the product into xylene. For staining, the purified dye is dissolved in 75% glycerol (1-5 micrograms/ml) and applied to frozen tissue sections. Tissue lipids then fluoresce yellow-gold to red, depending on their relative hydrophobicity. Using sections of liver and aorta from a cholesterol-fed rabbit, we assessed the value of Nile red as a stain for neutral lipids by comparing the staining pattern obtained with that produced by oil red O, a commonly used dye for tissue cholesteryl esters and triacylglycerols. In the cholesterol fatty liver, Nile red staining was comparable to that of oil red O. In contrast, Nile red staining of rabbit aortic atheroma revealed ubiquitous lipid deposits not observed with oil red O staining. These latter results suggest that Nile red can detect neutral lipid deposits, presumably unesterified cholesterol, not usually seen with oil red O or other traditional fat stains. 相似文献
7.
Spectrofluorometric studies of the lipid probe, nile red 总被引:18,自引:0,他引:18
We found that the dye nile red, 9-diethylamino-5H-benzo[alpha]phenoxazine-5-one, can be applied as a fluorescent vital stain for the detection of intracellular lipid droplets by fluorescence microscopy and flow cytofluorometry (J. Cell. Biol. 1985. 100: 965-973). To understand the selectivity of the staining, we examined the fluorescence properties of nile red in the presence of organic solvents and model lipid systems. Nile red was found to be both very soluble and strongly fluorescent in organic solvents. The excitation and emission spectra of nile red shifted to shorter wavelengths with decreasing solvent polarity. However, the fluorescence of nile red was quenched in aqueous medium. Nile red was observed to fluoresce intensely in the presence of aqueous suspensions of phosphatidylcholine vesicles (excitation maximum: 549 nm; emission maximum: 628 nm). When neutral lipids such as triacylglycerols or cholesteryl esters were incorporated with phosphatidylcholine to form microemulsions, nile red fluorescence emission maxima shifted to shorter wavelengths. Serum lipoproteins also induced nile red fluorescence and produced spectral blue shifts. Nile red fluorescence was not observed in the presence of either immunoglobulin G or gelatin. These results demonstrate that nile red fluorescence accompanied by a spectral blue shift reflects the presence of nile red in a hydrophobic lipid environment and account for the selective detection of neutral lipid by the dye. Nile red thus serves as an excellent fluorescent lipid probe. 相似文献
8.
Mevinolinic acid biosynthesis by Aspergillus terreus and its relationship to fatty acid biosynthesis. 总被引:2,自引:0,他引:2
Mevinolinic acid, the open acid form of mevinolin, which is a metabolite of Aspergillus terreus, has been shown to be a competitive inhibitor of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (Alberts et al., Proc. Natl. Acad. Sci. U.S.A. 77:3957-3961, 1980). The biosynthesis of mevinolinic acid was studied by examining the incorporation of [1-14C]acetate and [methyl-14C]methionine into the molecule. These isotopes were rapidly incorporated into mevinolinic acid, with [1-14C]acetate and [methyl-14C]methionine incorporation being linear for at least 10 and 30 min, respectively. A comparison of acetate incorporation into mevinolinic acid and fatty acids indicated that mevinolinic acid biosynthesis increased with a maximum between days 3 and 5 of growth; at this time cell growth had ceased and fatty acid biosynthesis was negligible. Hydrolysis of the mevinolinic acid and isolation of the products showed that [1-14C]acetate and [methyl-14C]methionine were incorporated into the 2-methylbutyric acid side chain as well as into the main (alcohol) portion of the molecule. 相似文献
9.
10.
REINHARD B
SE KARL T. FRIEDHOFF SYLVIA OLBRICH 《The Journal of eukaryotic microbiology》1987,34(1):110-113
Four fallow deer, Cervus dama, became infected with Trypanosoma (Megatrypanum) sp. by oral application of triturated guts from tabanids collected in an area with deer but without any cattle; four control calves remained negative. Upon challenge with triturated guts from tabanids from an area with pastured cattle, the four calves became infected with Trypanosoma (M.) theileri. The prepatent period in deer was five days or less. Haematopota spp. and Tabanus spp. were identified as vectors of the deer trypanosomes. It is concluded that the trypanosomes of C. dama belong to a Megatrypanum species that is not identical with T. theileri. 相似文献