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71.
Summary A large pedigree with a satellited Yq chromosome is described, Q, C, and NOR banding were performed. Family C proband suffers from a Klinefelter syndrome. 相似文献
72.
Elizabeth van Pelt Verkuil 《Journal of insect physiology》1978,24(5):375-382
Biochemical evidence was obtained for an increase in acid phosphatase activity in the larval fat body of Calliphora erythrocephala during larval and pharate pupal instars. This observation is in conflict with published data indicating a decreasing enzyme activity in late third stage larvae. Centrifugation and filtration studies showed that the pH of the homogenisation medium has a strong influence on the solubilisation of acid phosphatase and its distribution in homogenate components. Differences in biochemical techniques including the pH value may explain the discrepancy between the published results and the present findings.The observed increase in acid phosphatase activity is related to the activity of the lysosomal system in the period immediately preceding pupal-adult apolysis. 相似文献
73.
Lourival D. Possani Alejandro C. Alagón Paul L. Fletcher Bruce W. Erickson 《Archives of biochemistry and biophysics》1977,180(2):394-403
The water-soluble part of the dried venom from the scorpion, Tityus serrulatus Lutz and Mello (range, Southeastern Brazil), showed 16 polypeptide bands on polyacrylamide gel electrophoresis. This material exhibited toxic and hyaluronidase activity but no phospholipase, phosphodiesterase, protease, or fibrinolytic activity. Fractionation on glycinamide-treated Sephadex G-50 afforded three protein fractions, which were non-toxic, equitoxic, and three times more toxic than the water-soluble venom. Subsequent separation of the toxic fractions on carboxymethyl-cellulose with phosphate buffers furnished five toxic components, which were further purified on carboxymethyl-cellulose with a salt gradient in acetate buffer. Toxin γ, the major and most basic toxin, is a 62-residue protein that, unlike other scorpion toxins, contains methionine. Automated Edman degradation showed the amino-terminal sequence to be H-Lys-Glu-Gly-Tyr-Leu-Met-Asp-His-Glu-Gly-Cys-Lys-Leu-Ser-Cys-Phe-Ile-Arg-Pro-Ser-Gly-Tyr-Cys-Gly-Arg-Glu-Cys-Gly-Ile-. Toxin γ is the first example of a fifth structural type of mammalian toxin from scorpion venom. Its amino-terminal sequence shows greater homology with toxins similar to Centruroides suffusus suffusus toxin III and Androctonus australis toxin II than with toxins similar to A. australis toxin I or Bhutus occitanus tunetanus toxin I. 相似文献
74.
This work is concerned with statistical methods to estimate yield and maintenance parameters associated with microbial growth. For a given dilution rate, an experimenter typically measures substrate concentration, oxygen utilization rate, the rate of carbon dioxide evolution, and biomass concentration. These correlated response variables each contain information about the maintenance and yield parameters of interest. A maximum likelihood estimator which combines this correlated information for the yield and maintenance parameters is proposed, evaluated, and tested on literature data. Both point and interval estimators are considered. 相似文献
75.
76.
In the embryo, fibroblasts migrating through extracellular matrices (ECM) are generally elongate in shape, exhibiting a leading pseudopodium with filopodial extensions, and a trailing cell process. Little is known about the mechanism of movement of embryonic cells in ECM, for studies of fibroblast locomotion in the past have been largely confined to observations of flattened cells grown on planar substrata. We confirm here that embryonic avian corneal fibroblasts migrating within hydrated collagen gels in vitro have the bipolar morphology of fibroblasts in vivo, and we show for the first time that highly flattened gerbil fibroma fibroblasts, grown as cell lines on planar substrata, can also respond to hydrated collagen gels by becoming elongate in shape. We demonstrate that the collagen-mediated change in cell shape is accompanied by dramatic rearrangement of the actin, α-actinin, and myosin components of the cytoskeleton. By immunofluorescence, the stress fibers of the flattened corneal fibroblasts grown on glass are seen to stain with antiactin, anti-α-actinin, and antimyosin, as has been reported for fibroma and other fibroblasts grown on glass. Stress fibers, adhesion plaques, and ruffles do not develop when the corneal or fibroma fibroblast is grown in ECM; these features seem to be a response to strong attachment of the cell underside to a planar substratum. When the fibroblasts are grown in ECM, antimyosin staining is distributed diffusely through the cytoplasm. Antiactin and anti-α-actinin stain the microfilamentous cell cortex strongly. We suggest that locomotion of the fibroblast in ECM is accompanied by adhesion of the cell to the collagen fibrils and may involve an interaction of the myosin-rich cytosol with the actin-rich filamentous cell cortex. Interestingly, the numerous filopodia that characterize the tips of motile pseudopodia of cells in ECM are very rich in actin and α-actinin, but seem to lack myosin; if filopodia use myosin to move, the interaction must be at a distance. Soluble collagen does not convert flattened fibroblasts on planar substrata to bipolar cells. Thus, the effect of collagen on the fibroblast cytoskeleton seems to depend on the presence of collagen fibrils in a gel surrounding the cell. 相似文献
77.
The effects of addition of cellular fibronectin on the cell-to-substrate contacts of a non-transformed adhesion-defective mutant, AD6, of the BALB/ c3T3 cell-line, and of transformed L-929 fibroblasts have been examined by interference reflection microscopy (IRM). We report that formation of the close contact, but not focal contacts, is promoted in parallel with an increase in spreading in both cell types. These results provide strong evidence for a functional role of fibronectin in the formation of the adhesive close contact. 相似文献
78.
Summary The effect of protoplast-isolating enzymes on spontaneous fusion of maize protoplasts (Zea mays L. cv. Black Mexican Sweet) was investigated using a convenient ethidium bromide nuclear staining procedure. After 2–2.5 hour digestion in an enzyme solution containing 1% Cellulysin, 0.5% Rhozyme, and 0.02% Pectolyase Y-23, 50–75% of the protoplasts contained multiple nuclei. The cellulase Cellulysin was identified as the factor causing the spontaneous protoplast fusion; when Cellulysin was replaced by CELF cellulase, most protoplasts were uninucleate. Calcium and other components in the enzyme solution did not affect spontaneous fusion. Cellulysin also increased the percentage of multinucleate protoplasts from rice and asparagus suspensions. Presence of multiple nuclei might affect genetic manipulations involving protoplasts. 相似文献
79.
We have previously demonstrated that glial fibrillary acidic protein (GFAP) containing intermediate filaments in retinal Müller cells undergo both quantitative induction and subcellular reorganization as a response to long-term retinal detachment (an induced CNS degeneration wherein the Müller cells form a multicellular scar). This study demonstrates by RNA blotting analysis that normal retina expresses a low basal level of GFAP mRNA, which is induced approximately 500% within 3 days of retinal detachment. At the cellular level, electron microscopic in situ hybridization analysis readily detects GFAP mRNA in Müller cells of detached retinas, but not in normal retinas. On the other hand, GFAP mRNA was readily detected in retinal astrocytes (which appear to express GFAP mRNA at high, constitutive levels). In both cell types, the ultrastructural localization of GFAP mRNA was the same. In the nuclei, the GFAP mRNA was associated with amorphous, electron-dense regions within the euchromatin. In the cytoplasm, the GFAP mRNA was associated with intermediate filaments near the nuclear pores, along the filaments when no other structures were apparent, and when the filaments appeared to be associated with ribosomes and polysomes. The ultrastructural location of the GFAP mRNA (especially along the intermediate filaments) may be unique to this mRNA or may represent a more generalized mRNA phenomenon. 相似文献
80.
Purification and partial characterization of a 65-kDa platelet aggregation-associated protein antigen from the surface of Streptococcus sanguis 总被引:5,自引:0,他引:5
Cells of Streptococcus sanguis express a collagen-like immunodeterminant (class II antigen) on their cell walls that induces aggregation of platelets in plasma. These platelet aggregation-associated proteins (PAAPs) are recovered in cell-free preparations obtained from cells of S. sanguis after 5 min of sonic or limited trypsin treatment. Pretreatment of platelet-rich plasma with these soluble preparations selectively inhibits platelet aggregation in response to S. sanguis cells. A PAAP antigen was isolated and purified from minimal tryptic digests of S. sanguis cells using (i) immunoaffinity chromatography or (ii) gel filtration and ion-exchange chromatography. A monospecific rabbit antiserum was prepared against PAAP (from procedure ii) and used to verify identity with PAAP fragments in different preparations. Criteria of purity included single precipitins in immunoelectrophoresis and crossed immunoelectrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western immunoblot, and COOH (Lys)- and NH2 (Pro)-terminal analyses. The 65-kDa (p65) antigen isolated by immunoaffinity chromatography had 50-fold greater specific inhibitory activity in S. sanguis-induced PRP aggregation than the original tryptic digest and about 1.4 times that recovered by sequential column chromatography. Amino acids of the p65 PAAP fragment constituted 89.5% of the total dry weight, with glycine, lysine, and glutamic acid predominant. Lesser amounts of proline were also noted. Monosaccharides, including glucose and galactose, comprised 4.0% of the total. A platelet interactive determinant of p65 was localized to a 23-kDa tryptic fragment after further trypsin treatment. Amino acids of this 23-kDa fragment constituted 99.8% of the total dry weight. In their native state on the cell wall of platelet-interactive strains of S. sanguis, platelet aggregation-associated proteins are probably assembled on fibrils as polyvalent agonists. 相似文献