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981.
Three minor small RNA species from Novikoff hepatoma cells, with homology to repetitive DNA sequences, have been identified
and characterized. These small RNAs, designated 5.1S, 6S and T3 RNAs, show homology to Alu 1, Alu 2, and Alu 3 sequences,
respectively. 6S and T3 RNAs were found both in the nucleus and cytoplasm, whereas 5.1S RNA was not found in the nucleus.
Neural tissues were found to contain a 6S-sized BC1 RNA with homology to I.D. sequences [19]; in contrast, the current study
shows that Novikoff hepatoma cells contain a 75–80 nucleotide long (T3) RNA, homologous to I.D. sequences. These data suggest
that BCl and T3 small RNAs, homologous to I.D. sequences, are expressed in a tissue-specific manner. These results also show
that in addition to the abundant 7SL, 4.5S and 4.5S1 RNAs having homology to repetitive DNA, Novikoff hepatoma cells also
contain several minor small RNAs with homology to repetitive sequences. 相似文献
982.
J. Brown P. D. S. Caligari M. F. B. Dale G. E. L. Swan G. R. Mackay 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,76(1):33-38
Summary Most previous studies on cross prediction methods have examined relatively few crosses, particularly in relation to the numbers involved in most breeding programmes. In this paper the feasibility of using cross prediction methods was examined in a practical potato (Solanum tuberosum) breeding scheme by the analyses of progeny from 52 crosses. The variate considered was breeder's preference, a visual assessment made of the harvested tubers to estimate their commercial potential. The results showed that it was possible to identify the superior crosses. Cross prediction based simply on the mean preference scores, averaged over scorers and clones within progenies, estimated on seedlings or first clonal year plants, provided the best estimate of a progeny's performance in the third clonal generation. Predictions based on the expected proportion of clones that would transgress a given target value also provided a good indication of a progeny's potential. The poorest prediction was obtained by using the observed frequency of desirable clones in a progeny sample. The implications for potato breeding are discussed. 相似文献
983.
Element interactions in forest ecosystems: succession,allometry and input-output budgets 总被引:3,自引:3,他引:0
Element interactions within forests differ from those in other major ecosystems for three major reasons: — a greater allocation of carbon to structural material; — a greater element storage within biomass; and — the diversity of carbon- and nutrient-containing metabolites produced. The most important of these differences is structural material, which can lead to C: element ratios in biomass (as a whole) 100 × greater than those in unicellular organisms. Stand allometry causes the amount of carbon stored and C:element ratios in biomass to change in predictable ways in the course of secondary succession. Such changes affect microbial dynamics and C: element interactions within soils. Bicarbonate, organic acids, nitrate, phosphate, and sulfate are major anions within forest soils: they control leaching of both anions and cations. Biotic interactions of C, N, P, and S during both uptake and mineralization control the potential for production of these anions within forests, and geochemical interactions regulate their mobility and loss. 相似文献
984.
The band patterns of zein polypeptides were determined for many commercial inbred corn lines and maize stocks using isofocusing in agarose gels and sodium dodecyl sulfate (SDS)-urea gels. Each inbred line or homozygous maize strain genotype has a distinct zein profile which has been catalogued according to the distance of charge migration and molecular weight (kilodaltons). Several zein polypeptides were mapped to chromosomes 4 and 10 with the use of reciprocal translocations. The mapping of at least two polypeptides on distal 4L and 10L had not been previously reported. The general methods used in the present research will permit the mapping of all the zein polypeptides to chromosomal sites.Pioneer Hi-Bred International provided financial support. 相似文献
985.
High-molecular-weight precursor of epidermal filaggrin and hypothesis for its tandem repeating structure 总被引:4,自引:0,他引:4
Filaggrin is a histidine-rich protein that is intimately involved in mammalian epidermal keratinization. Using a combination of immunologic and in vivo pulse-chase studies with radiolabeled histidine and phosphate, we show that the phosphorylated precursor of both rat and mouse filaggrin has an apparent molecular weight much higher than previously realized (6 X 10(5) and 3.9 X 10(5), respectively). These high-molecular-weight filaggrin precursors can be rapidly labeled with histidine and extracted from the epidermis under denaturing conditions. More than half of the label incorporated in the precursor at 2 h is found in filaggrin at 24 h after injection, even though filaggrin is less than 10% of the size of the precursor. Limited proteolytic digestion of the precursor in vitro results in the formation of an oligomeric series of peptides based on a phosphorylated fragment slightly larger than filaggrin itself. More extensive digestion of this fragment shows that it is composed of filaggrin with few or no additional unrelated peptides, suggesting that the major part of the high-molecular-weight filaggrin precursor must be composed of repeated domains of filaggrin. Because the primary translation product of filaggrin mRNA is large, we propose that these domains are repeated in tandem. In addition, from molecular weight computations and peptide map analyses, we suggest that the filaggrins are themselves composed of multiple repeating units of an unidentified peptide of approximately Mr 8600. This value is derived from the molecular weights of filaggrin from several mammalian species that differ by integral multiples of 8600. A model for the structure of the high-molecular-weight precursor of filaggrin is presented.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
986.
William K. Fitt Michael P. Labare W. Claiborne Fuqua Marianne Walch Steven L. Coon Dale B. Bonar Rita R. Colwell Ronald M. Weiner 《Microbial ecology》1989,17(3):287-298
Dissolved chemical inducers of settlement behavior of veliger larvae of the oysterCrassostrea gigas are found in supernatants of both pigmented species of bacteria (Alteromonas colwelliana, Vibrio cholerae strain HTX) as well as nonpigmented bacteria (Excherichia coli, Vibrio cholerae strain 596-B). Usually less than 10% of veligers exhibited settlement behavior in response to supernatants from the early bacterial growth phases, whereas 30–90% of larvae responded when exposed to supernatant from late-log and stationary phase cultures. Percentages of larvae exhibiting settlement behavior were inversely correlated with oxygen levels in the culture. Furthermore, the behavioral response decreased with pigment formation, suggesting that quantities of noxious compounds such as quinones may build up in the supernatants of cultures of pigmented bacteria. Tyrosinase, an enzyme that converts L-tyrosine to L-DOPA in the first step of melanogenesis, was detected both in the bacterial pellet and the supernatant during growth of the pigmented species. The enzyme is not required for the production of settlement inducer as the nonpigmented speciesE. coli andV. cholerae (596-B) also released inducer into the supernatant and had no detectable tyrosinase. The data suggest either that there is more than one inducer of settlement behavior found in bacterial supernatants or that the inducer is not L-DOPA or an L-DOPA-mimetic associated with the melanin biochemical pathway. 相似文献
987.
988.
Summary A number of parameters characteristic of the wing margin precursor in imaginal discs of Drosophila are known: the zone of non-proliferating cells or ZNC (O'Brochta and Bryant 1985), aldehyde oxidase (AO) and other enzyme staining patterns (Sprey et al. 1982), E1C antigen localization in a narrow band along the margin (Piovant and Lena 1988). To test our hypothesis that such parameters, and others, act in concert to determine margin identity and the positional information that specifies the bristles and hairs appropriate to the anterior, posterior and distal margins, we have examined these parameters in the dominant mutant Lyra, in which much of the anterior and posterior margins is missing. After establishing that Lyra phenotype is already evident in the early pupal wing, we tested the known imaginal disc parameters and found that only Mab E1C (Piovant and Lena 1988) distribution differs from wild type, suggesting that E1C antigen may be a component of positional information. Sibatani's (1983) model for specification of positional information (PI) applied to wing discs predicts the Lyra adult wing shape as well as the reduced distribution of E1C antigen in Lyra wing discs. The model is based on the assumption that specification of positional information depends on interactions of multiple, independent factors. Clonal analysis with shaggy (Simpson et al. 1988 and Ripoll et al. 1988) indicates that factors in addition to E1C antigen contribute to margin PI in Lyra wings and should allow us to test the multi-component hypothesis further. 相似文献
989.
Jerry Y. Niederkorn Dale R. Meyer John E. Ubelaker James H. Martin 《In vitro cellular & developmental biology. Plant》1990,26(9):923-930
Summary A widely utilized rabbit corneal cell line, SIRC, was characterized ultrastructurally and immunohistologically. Although SIRC
cells are often described as being of epithelial origin, important ultrastructural and antigenic characteristics indicate
that these cells are fibroblastic and not epithelial. SIRC cells lack desmosomes, cytoplasmic filaments, and cytokeratin—structures
that are characteristic of corneal epithelial cells. By contrast, the dendritic morphology, presence of vimentin, and the
extensive dense accumulations of ribosomes and rough endoplasmic reticulum are consistent with a fibroblastic phenotype. Collectively,
the morphology, ultrastructural features, and antigenic composition favor the hypothesis that SIRC cells are fibroblastic
cells (keratocytes) and not corneal epithelial cells.
This work supported in part by grant EY 07641 from the National Institutes of Health, Bethesda, MD, and an unrestricted grant
from Research to Prevent Blindness, Inc., New York. 相似文献
990.
Kristopher E. Boyle Karen S. MacMillan David A. Ellis James P. Lajiness William M. Robertson Dale L. Boger 《Bioorganic & medicinal chemistry letters》2010,20(6):1854-1857
The design, synthesis and evaluation of methyl 1,2,8,8a-tetrahydrocyclopropa[c]oxazolo[2,3-e]indol-4-one-6-carboxylate (COI) derivatives are detailed representing analogs of duocarmycin SA containing an oxazole replacement for the fused pyrrole found in the alkylation subunit. 相似文献