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51.
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
52.
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
53.
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
54.
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
55.
56.
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
57.
58.
A method is presented for determining both the average turnover rate and the standard deviation of the average turnover rate of the adenine nucleotide (AN) pool within a population of microorganisms. The method requires the calculation of the initial slope and curvature of a plot of AN specific activity versus time following the introduction of [3H]adenine. An analysis of noise-corrupted data indicated that the method is capable of detecting a lack of uniformity in the turnover rate when the coefficient of variation of the turnover rate exceeds 39%. An analysis of field data revealed a significant lack of uniformity in the turnover rates of microbial communities in a marine sediment sample and freshwater pond but no significant nonuniformity in the turnover rates of microbial communities in a seawater sample and in a second freshwater pond. Although the method has been applied only to the analysis of AN turnover rates, it is applicable to any intracellular pool for which a suitable radioactive precursor exists. 相似文献
59.
Acetylene Metabolism and Stimulation of Denitrification in an Agricultural Soil 总被引:1,自引:1,他引:0
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The effects of C2H2 metabolism on N2O production were examined in soil slurries. Enrichment of C2H2 consumption activity occurred only in aerobic incubations. Rapid disappearance of subsequent C2H2 additions, stimulation of CO2 production, and most-probable-number enumerations of C2H2 utilizers indicated enrichment of the population responsible. During C2H2 consumption in slurries incubated statically under air, maximal rates of N2O evolution were 19 times higher than those in anaerobic incubations. After 20 days of enrichment with C2H2, the production of N2O by slurries supplemented with C2H2 and nitrate was 10 times higher than that in the unenriched controls. A Nocardia- or Arthrobacter-like bacterium was isolated that grew on C2H2 but did not denitrify. The behavior of soil inoculated with this bacterium became similar to that of C2H2-enriched soil incubated aerobically. Ethanol, acetate, and acetaldehyde were identified in enrichment experiments, and denitrification in soil slurries was stimulated by addition of the supernatant from a pure culture grown on mineral medium with C2H2. These results indicate that denitrification can be stimulated by the actions of an aerobic, nondenitrifying C2H2-metabolizing population. Utilization of intermediate metabolites by denitrifiers and enhanced O2 consumption are two possible mechanisms for this stimulation. 相似文献
60.
Edward S. Deevey Michael W. Binford Mark Brenner Thomas J. Whitmore 《Hydrobiologia》1986,143(1):49-53
Transfer functions relating trophic state (Carlson's TSIchlorophyll-a) to present day accumulation rate of (1) nutrients, (2) cations, and (3) organic sediment, are computed using Binford's 210Pb-dilution method. As computed from surficial sediments of 27 lakes, former trophic states are reconstructed for recent (210Pb-dated) sedimentary histories of 14 lakes. Of the three kinds of models potentially available, model (3) (TSI vs. organic accumulation) is the weakest statistically, and may be unduly influenced by exceptional deposition and/or preservation of allochthonous organic matter. At present, however, it is the only model applicable to all 14 of the histories tested. Results are encouraging in that model accurately predicts observed TSI's in several mesotrophic and eutrophic lakes. Clearly significant increases (accelerations) are inferred only for a of the most eutrophic lakes of the set, while the model consistently overpredicts TSI's of the 7 most oligotrophic lakes. As Whitmore's diatom-assemblage index is a better predictor of TSI than is model (3) in the one eutrophic lake in which it has been tested, we expect more persuasive results when models (1) and (2) can be tested within a more complete set of analytical data. We were surprised to find 3 severely disturbed lakes among the 12 that show little or no acceleration in rate of eutrophication in recent decades, but we defer attempts at explanation until former nutrient loading can be tested by model (1). 相似文献