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51.
From siliceous shales (Lower Carboniferous, Rheinisches Schiefergebirge), in direct neighborhood to a bed of allodapic limestone, the following fluontized radiolarian fauna has been extracted by chemical transformation of originally calcified skeletons:Albaillella cartalla, Latentifistula turgida, Eostylodktya cf. eccentrica, Tetragregnon sycamorensis sycamorensis, Belowea variabilis, Callela? hexactinia, Entactinia tortispina and Entactinia variospina. The limestone bed has been dated by calcareous foraminifera as being mid Visean in age (V 2b-3a, Cf 5-foraminiferal zone). The diagenetic calcification took place after the selective dissolution of the skeletons and was in itself not selective. 相似文献
52.
53.
Potato cells (cv. Norchip) were cultured from tuber parenchymal tissue and subcultured to dissociate and habituate the despecialized cells. After several subculturings on a minimal nutrient media, this line of cells demonstrated repeatable physical growth profiles for dry weight (DW), fresh weight (FW) and protein. Two enzymes of plant lipid metabolism were investigated, lipolytic acyl hydrolase (LAH) and lipoxygenase (LOX), which respectively liberate and peroxidize fatty acids from lipid in cellular membranes. LAH, measured as p-nitrophenyl palmitate hydrolase, was present in this line of cells in easily detectable amounts (317 units g-1 DW) albeit much lower than that found in mother tuber (9878 units g-1 DW). The presence of LAH in this line is significant because LAH isozymes are often described as storage proteins, yet activity per gram fresh weight in these unorganized cells is reasonably constant until culture growth exits the linear phase. However, LOX, the most active free fatty acid metabolizing enzyme in potato tubers (89,800 units g-1 DW), was not detectable in this line of callus or suspension cultured cells. The absence of LOX activity in this line of cells was verified by a number of assay approaches and was confirmed by activity staining of extracted enzymes separated in polyacrylamide gels. The absence of LOX in these cultured cells is especially important in determining the functions of this lipid peroxidation system and how it may be genetically regulated.Mention of company or trade name does not imply endorsement by the United States Department of Agriculture over others not named.A laboratory cooperatively operated by the Midwest Area, Agricultural Research Service, U.S. Department of Agriculture, The Minnesota Agricultural Experiment Station, the North Dakota Agrcultural Experiment Station, and the Red River Valley Potato Grower's Association. 相似文献
54.
J. J. Wang S. R. Roffler M. H. Yu C. S. Yin M. Y. Yeh 《Histochemistry and cell biology》1992,97(6):453-461
Summary The specific binding and nature of the epitope recognized by monoclonal antibody (Mab) 1H10, which binds an antigen expressed on human cervical tumors, was characterized by enzyme digestion, lectin competition assay and immuno-electron microscopy. Membrane homogenates of CaSki cervical carcinoma cells were digested with various enzymes, then analysed by SDS-PAGE and immunoblotting. Cells grown on coverslips were treated with various enzymes and in situ binding of Mab 1H10 to cells was analysed by electron microscopy. The ability of lectin-conjugates to block Mab 1H10 binding to CaSki cells was also examined. Treatment of samples with sodium periodate abrogated antigen recognition by Mab 1H10. Neuraminidase and hyaluronidase digestion decreased but did not eliminate Mab 1H10 binding to cells in situ. Chondroitinase ABC digestion, in contrast, removed Mab 1H10 binding sites both in vitro and in situ. Trypsin and chymotrypsin digestion of cell membrane homogenates decreased the molecular weight of the Mab 1H10 antigen but did not decrease the binding intensity. Wheat germ agglutinin (WGA) strongly bound to CaSki cells and partially blocked Mab 1H10 binding, indicating that the antigen contains N-acetyl-galactosamine residues at or near the epitope recognized by Mab 1H10. Ricinus communis agglutinin (RCA) exhibited a similar binding pattern to WGA. However, concanavalin A bound only weakly to CaSki cells and was ineffective at blocking Mab 1H10 binding. The tumor-associated antigen recognized by Mab 1H10 is concluded to be a chondroitin sulphate glycoprotein or proteoglycan rather than a mucopolysaccharide or lipoprotein. 相似文献
55.
P. Edward Purdue Michael J. Lumb Jennifer Allsop Christopher J. Danpure 《Human genetics》1991,87(4):394-396
Summary We report here the identification of a duplication within the first intron of the gene encoding human alanine:glyoxylate aminotransferase (AGT); this duplication is closely linked to two point mutations associated with peroxisome-to-mitochondrion mistargeting of AGT in primary hyperoxaluria type 1 (PH1) patients. Polymerase chain reaction amplification of regions of the AGT gene including the insertion site from individuals heterozygous for this duplication, produces allele-specific fragments of different sizes. We have taken advantage of this to identify a nonsense mutation within a non-expressed allele of a compound heterozygote PH1 patient with mitochondrial AGT. 相似文献
56.
Lisa G. Shaffer Colleen K. Jackson-Cook Joanne M. Meyer Judith A. Brown J. Edward Spence 《Human genetics》1991,86(4):375-382
Summary The largest class of de novo chromosomal rearrangements in Down syndrome are rea(21q21q). Classically, these rearrangements have been termed Robertsonian translocations, implying an attachment of two different chromosome 21 homologues. Additionally, a Robertsonian translocation between two chromosomes 21 cannot be distinguished from an isochromosome composed of genetically identical arms by cytogenetic analyses. Therefore, we have used molecular techniques to differentiate between true Robertsonian translocations and isochromosomes. Samples were obtained from 12 probands, ascertained for de novo rearrangements between homologous chromosomes 21 [11 rea(21q21q) and 1 rea (21;21)(q22;q22)], their parents (n = 24) and available siblings (n = 7). The parental origins of the de novo rearrangements were assigned using molecular and cytogenetic analyses. Although not statistically significant, there was a two-fold increase in the number of paternally derived de novo rearrangements (n = 8) as compared with maternally derived rearrangements (n = 4). To distinguish between rob(21q21q) and i(21q), we used restriction fragment length polymorphisms (RFLPs) spanning the length of chromosome 21. Using all informative and partially informative RFLPs, we used the method of maximum likelihood to assign the most likely rearrangement definition (i or rob) and parental origin in each family. The maximum likelihood estimates indicated that all rearrangements tested (n = 8) were isochromosomes. C-banding revealed two centromeres in three cases indicating that a U-type exchange occurred between sister chromatids in these rearrangements. Our results suggest that the majority of de novo rea(21q21q) are isochromosomes derived from a single parental chromosome 21. 相似文献
57.
Charles M. Lent David Zundel Edward Freedman James R. Groome 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(2):191-200
Summary Stridulation of grasshoppers is controlled by hemisegmental pattern generator subunits which probably are restricted to the metathoracic ganglion complex (TG3-complex). The coordination of left and right pattern generator subunits depends on commissures of the TG3-complex (Ronacher 1989). The coordination of the stridulatory movements was studied in Chorthippus dorsatus males with partial mediosagittal incisions in the TG3-complex.Animals bearing anterior incisions in the TG3-complex, by which all commissures of the metathoracic neuromere and the first abdominal neuromere were transected, were still able to produce bilaterally coordinated species-specific stridulatory movements. Commissures of the T3- and A1-neuromere, thus, are not necessary, and the A2-, A3-commissures are sufficient for this coordination (Figs. 3, 4).Animals with partial posterior incisions, extending until A1, had deficits in their stridulation pattern; the coordination between the hindlegs was impaired though not completely lost (Fig. 6). This is discussed in view of the structure of stridulation interneurons identified in a related grasshopper species (Omocestus viridulus).These results indicate an unexpected substantial contribution of the abdominal neuromeres A2 and A3 to the control of stridulatory movements. This constitutes an interesting parallel to the flight control system of locusts where interneurons located in the first 3 abdominal neuromeres also appear to contribute to the flight pattern generator (Robertson et al. 1982).Abbreviations
A1–A3
abdominal neuromeres 1–3
-
T3
metathoracic neuromere
-
TG3-complex
metathoracic ganglion complex including A1–A3 相似文献
58.
High-level secretion of correctly processed recombinant human interleukin-1 beta in Kluyveromyces lactis. 总被引:1,自引:0,他引:1
R Fleer X J Chen N Amellal P Yeh A Fournier F Guinet N Gault D Faucher F Folliard H Fukuhara 《Gene》1991,107(2):285-295
The lactose-assimilating yeast, Kluyveromyces lactis, has been developed as a microbial host for the synthesis and secretion of human proteins. Here, we report the use of multi-copy vectors based on the 2 mu-like plasmid pKD1 from Kluyveromyces drosophilarum [Chen et al., Nucleic Acids Res. 14 (1986) 4471-4481] for the secretion of recombinant human interleukin-1 beta (reIL-1 beta). High levels of reIL-1 beta were secreted into the growth medium when the structural gene was fused in-frame to a synthetic secretion signal derived from the 'pre'-region of the K. lactis killer toxin. N-terminal sequencing of the excreted protein showed highly efficient (greater than 95%) maturation of the signal sequence. Synthesis as prepro-IL-1 beta, the 'pro'-sequence being derived from the human serum albumin-encoding gene, resulted in equally efficient secretion of mature IL-1 beta. Cytoplasmic production of Met-IL-1 beta, without a secretion signal, was found to be toxic to K. lactis. As in Saccharomyces cerevisiae [Baldari et al., EMBO J. 6 (1987) 229-234], but unlike native human IL-1 beta, K. lactis reIL-1 beta is glycosylated. This glycosylation led to a 95% loss of its biological activity. Removal of the carbohydrate chains by endo-beta-N-acetyl-glucosamidase H treatment fully restored the biological activity. A modified form of IL-1 beta (Asn7----Gln7), in which the unique site for Asn-linked glycosylation was deleted, exhibited the same biological activity as native IL-1 beta. The level of secretion of mature recombinant IL-1 beta ws glycosylation-independent. 相似文献
59.
60.
Chromosome distribution of intracisternal A-particle sequences in the Syrian hamster and mouse 总被引:5,自引:0,他引:5
Edward L. Kuff Joseph E. Fewell Kira K. Lueders Joseph A. DiPaolo Suzanne C. Amsbaugh Nicholas C. Popescu 《Chromosoma》1986,93(3):213-219
Metaphase chromosomes of Syrian hamster and BALB/c mice were hybridized in situ with radiolabeled probes derived from cloned intracisternal A-particle (IAP) genes of the corresponding species. The DNAs of these species are known to contain about 900 and 1,000 copies, respectively, of the retrovirus-like IAP sequence elements per haploid genome. Multiple IAP sequences were found on all chromosomes of both hamster and mouse. In the hamster, more than half of the IAP sequences were located in regions of non-centromeric constitutive heterochromatin, at an average concentration per unit chromosome length 5 times greater than in the euchromatic regions. The other dispersed sequences showed marked local variations in concentration along the chromosome lengths; both discrete foci and large grain clusters were observed as well as regions apparently lacking IAP sequences. Within the resolution of the techniques, IAP sequences appeared to be more evenly distributed over the mouse chromosomes; however, some prominent variations in concentration were seen. The number of potentially active IAP genes in the Syrian hamster, and by extension in the mouse, may be restricted by the preferential location of IAP sequences in genetically inert regions of the genome. 相似文献