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71.
72.
Sequencing Studies of Icr-170 Mutagenic Specificity in the am (Nadp-Specific Glutamate Dehydrogenase) Gene of NEUROSPORA CRASSA 总被引:3,自引:2,他引:1
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The acridine half-mustard ICR-170-induced reversion of the mutant am15, which has a single base-pair deletion, at a frequency of between 9 and 28 X 10(-6). In each of three classes of revertants, the mutagen had induced the insertion of a -G- -C- base pair at a -G-G- -C-C- site. The mutant am6, which has a single base pair insertion, is known to be revertible, with UV light, by deletion of a -G- -C- base pair at a -G-G-G- -C-C-C- site. This mutant reverted with ICR-170 at a frequency of 0.1 X 10(-6). These results show that ICR-170 is able to induce addition frameshifts in Neurospora crassa within short, monotonous runs of G:C base pairs, but indicate a lack of deletion activity at such sequences. 相似文献
73.
Summary The distribution of types I, II, III, V and IX collagens in healing fractures of the rabbit tibia has been demonstrated by immunofluorescent techniques. It has also been shown that the mechanical stability of the healing fracture affects both the distribution and types of the collagens present.The initial fibrous matrix contains types III and V collagens; type I collagen was only located in this matrix if unfixed tissue was used. In mechanically stable fractures, cancellous bone forms over the entire periosteal surface by 5–7 days; type I collagen is laid down within the previous fibrous matrix. The trabeculae are heterogeneous in their collagen content. The cavities contain a matrix of types III and V collagens. Small nodules of cartilage may be present between 7 and 14 days; these contain types II and IX collagens.In mechanically unstable fractures, cancellous bone is initially formed away from the fracture gap. The fibrous tissue over the gap is replaced by cartilage; types II and IX collagens are laid down on the pre-existing fibrous matrix. The cartilage is replaced by endochondral ossification. At the ossification front, type I collagen is found around the chondrocyte lacunae of the spicules of cartilage. The new trabeculae contain a core of cartilage which is surrounded by a bone matrix of types I and V collagens.The fracture gaps are invaded by fibrous tissue, which contain types III and V collagens. This is later replaced by cancellous bone. 相似文献
74.
Keith Condon Douglas K. Charles James M. Cheverud Jane E. Buikstra 《American journal of physical anthropology》1986,71(3):321-330
The cementum annulation aging technique was evaluated in a sample of 80 clinically extracted premolars (age range 11–70 years). Demineralized thin sections (7μm) stained with hematoxylin were used. The correlation (r) between age and adjusted count (number of annulations added to age of tooth eruption) was 0.78 for the entire sample (N = 73) and 0.86 for a subsample in which teeth with periodontal disease were excluded (N = 55). Standard error of the estimates ranged from 4.7 to 9.7 years depending on sex and health status of the tooth. The technique provided significantly better estimates for females than for males. The overall inaccuracy (mean absolute error) of the technique was 6.0 years, with a bias (mean error) of 0.26 years. Reduced major axis regression of adjusted count on age produced a slope of 0.797 for the entire sample and 0.889 for the nonperiodontal disease subsample. These slopes are consistent with a hypothesis of annual deposition of cementum rings given a decrease in cementogenesis with increasing age. 相似文献
75.
76.
Growth Regulators Have Rapid Effects on Photosynthate Unloading from Seed Coats of Phaseolus vulgaris L 总被引:17,自引:1,他引:16
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Of nine plant growth regulators (indoleacetic acid, 1-naphthalene acetic acid, gibberellic acid, giberellin 4/7, 6-benzylaminopurine, 6-furfurylaminopurine, abscisic acid, and 1-aminocyclopropane carboxylic acid) tested, only 6-benzylaminopurine and abscisic acid affected 14C-photosynthate unloading from excised seed coats of Phaseolus vulgaris L. Unloading, in the presence of KCl, was stimulated by 25 to 40%. Stimulation occurred immediately for 6-benzylaminopurine and for abscisic acid within 10 to 12 minutes of application. 相似文献
77.
A new annual species ofMadia sect.Anisocarpus,Madia doris-nilesiae, from the serpentine soils of western Trinity County, California is described, illustrated, and compared to the other annual members of the section. On the basis of floral and fruit morphologies the annual members of the section can be divided into two geographical units.Madia dorisnilesiae is unique in that it has a combination of these characters. 相似文献
78.
Summary The inoculation ofAlnus rubra (red alder) withFrankia sp. can lead to a highly efficient symbiosis. Several factors contribute to the successful establishment of nitrogenfixing nodules: (1) quantity and quality ofFrankia inoculant; (2) time and method of inoculation; (3) nutritional status of the host plant.Frankia isolates were screened for their ability to nodulate and promote plant growth of container-grown red alder. Inoculations were performed on seedlings and seeds. Apparent differences in symbiotic performance could be seen when seeds or seedlings were inoculated. Plants inoculated at planting performed significantly better than those inoculated four weeks later in terms of shoot height, nodule number and shoot dry weight. If inoculation was delayed further, reduction in shoot height, nodule number and shoot dry weight resulted. The effect of fertilizer was also investigated with regard to providing optimal plant growth after inoculation. Plants receiving 1/5 Hoagland's solution minus nitrogen showed maximal plant growth with abundant nodulation. Plants receiving 1/5 Hoagland's solution with nitrogen showed excellent plant growth with significantly reduced nodulation. 相似文献
79.
Clifford A. Siegfried 《Hydrobiologia》1985,122(2):175-180
The life history characteristics, population dynamics and production of Pontoporeia hoyi in Lake George, New York, were studied from May 1981 through October 1982. P. hoyi, in terms of both density and standing crop, is the most prevalent member of the deep water macrobenthos of Lake George. It reproduces in the winter, with young being released in the late winter-early spring. At the southernmost study site, young released in the spring grew to 6–7 mm in length and bred during their first winter. At the remaining sites, P. hoyi required two years to complete its life cycle. This difference in life history characteristics can be related to food availability and temperature differences. The open waters of the south end of Lake George are not only more productive but are also more closely associated with the littoral zone, providing a wealth of bacteria-rich detritus for benthic deposit feeders. The greater food availability in the south basin of Lake George is reflected in significantly larger brood sizes and smaller size at maturity for P. hoyi populations from the south end of the lake.The southernmost study site has significantly greater P. hoyi density and standing crop than all other sites. The cohort of the year dominated density and standing crop at the southern site while the cohort of the previous year dominated standing crop at the other sites. Peak abundance ranged from 600 · m–2 at the north site to 2 900 · m–2 at the south site. Cohort production ranged from 2g · m–2 at the north site to 15g · m–2 at the south site. 相似文献
80.
Clifford A. L. Becker 《Inorganica chimica acta》1985,100(2):227-233
Equilibrium constants, Kdis, for the solvent- dependent, solution-phase disproportionation equilibria of monosubstituted pentakis(arlisocyanide)cobalt(I) complexes: 2[Co(CNR)4L]+?[Co(CNR)3L2]+ + [Co(CNR)5]+, Kdis = are measured by planimeter-integration of proton- NMR spectra at ambient temperature. The complexes, [Co(CNR)4L]ClO4, R = 2,6-Me2C6H3, L = P(C6H5)3, P(C6H4Cl-p)3, P(OC6H5)3, P(OC6H4Cl-p)3; R = o-MeC6H4, L = P(C6H4Cl-p)3, P(OC6H5)3, P(OC6H4Cl-p)3; R = 2,4,6-Me3C6H2, L = P(C6H5)3; R = 2,6-Et2C6H3, L = P(C6H5)3; are investigated in the deuterated solvents, CDCl3, CD3CN, (CD3)2CO, C5D5N, CD3NO2, and (CD3)2SO. Disproportionation seems to occur in all [Co(CNR)4L]+, but NMR study is facilitated by utilizing equivalent alkyl protons (i.e., Me-groups) on the RNC ligands.Correlation of Kdis values with steric-hindrance of the RNC in sets of complexes with the same P-ligand is evident in all solvents: Kdis decreases with increased steric-hindrance in RNC. The Kdis values for complexes with the same RNC and analogous triarylphosphine, triarylphosphite ligands (i.e., PR3, P(OR)3, same R) are approximately equal. The Kdis values for complexes of P-ligands with Cl-substituent are significantly larger than Kdis values for complexes with the corresponding unsubstituted P-ligands (e.g., [Co(CNR)4P(C6H4Clp)3]ClO4vs. [Co(CNR)4P(C6H5)3]ClO4) in (CD3)2CO and C5D5N solution, but are smaller in CDCl3 and CD3CN, and approximately equal in CD3NO2 and (CD3)2SO. Properties of the solvents are also considered. 相似文献