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101.
Gerd N. La Mar Kiyoshi Nagai Thomas Jue David L. Budd K. Gersonde H. Sick T. Kagimoto A. Hayashi F. Taketa 《Biochemical and biophysical research communications》1980,96(3):1172-1177
The proton nmr spectra of the synthetic valency hybrids, α2(β+CN)2, (α+CN)2β2 of hemoglobin A and the natural valency hybrids of the mutant hemoglobins Boston, Iwate and Milwaukee have led to the unambiguous assignment of the two proximal histidyl imidazole exchangeable proton signals at 64 and 76 ppm to individual α and β subunits, respectively. New single non-exchangeable proton resonances detected in the extreme downfield region of the spectra of Hbs Boston and Iwate are tentatively assigned to the coordinated tyrosine of the mutated α chains. 相似文献
102.
Summary
D. melanogaster males of
bb/O genetic constitution undergoing rDNA magnification were mated singly to XXbb
+/O females, yielding
bb/O male progeny, and to XNO-w sn bb
+ fameles, yielding
bb/XNO- females. The male and female offspring were scored for the bb
+ phenotype.Results show that there is a higher percentage of bb
+ flies in the
bb/O male progeny than in
bb/XNO- females progeny, in single crosses as well as in the combined data. rRNA/DNA hybridization experiments agree with this observation, by showing that the rDNA content in the progeny of premagnified flies was higher in the sons than in the daughters.These data indicate that the increase of ribosomal RNA genes is not due to a stable event such as an unequal mitotic sister exchange, whereas they do not contrast with the extracopy model. 相似文献
103.
The identification of Tithonia voucher specimens as T. rotundifolia (Mill.) Blake, used for sesquiterpene lactone chemical investigations, have been found to be T. diversifolia (Hemsl.) A. Gray. The compound Ivalin, also is reported for the first time from T. calva Sch. Bip. in Semann. 相似文献
104.
Aldolase-like imine formation in the mechanism of action of phosphonoacetaldehyde hydrolase. 总被引:5,自引:0,他引:5 下载免费PDF全文
Phosphonoacetaldehyde hydrolase (EC 3.11.1.1), the bacterial enzyme that catalyses the reaction HCO-CH2-PO(OH)2+H2O leads to HCO-CH3+Pi, is inactivated by borohydride if either phosphonoacetaldehyde or acetaldehyde is present. This supports the suggestion that the substrate forms an imine with an amino group of the enzyme. Such imine formation would labilize the C-P bond in the same way that aldolase and related enzymes labilize C-C and C-H bonds (Scheme 1a). 相似文献
105.
Summary Ultrastructural examination ofStreblonema sp. revealed icosahedral virus-like particles (135–150 nm) throughout the cytoplasm of vegetative cells. The densely packed particles consist of an osmiophilic coat around a fibrillar core. Most cytoplasmic organelles are excluded from the regions where the particles are extremely abundant, but no degeneration of plastids, mitochondria or dictyosomes is evident. The virogenic stroma contains many ribosomes and fibers possibly representing DNA strands remaining from the lysed nucleus. No decrease in vigor seemed to be associated with the presence of the particles. 相似文献
106.
MS-222 is an anesthetic that is widely used for cold-blooded animals. The present study uses contact circum-corneal electrodes and conventional recording equipment to determine the effect of this anesthetic on the electroretinogram (ERG) of the rough-skinned newt (). When applied prior to retinal bleach, MS-222 retarded the rate of subsequent dark adaptation. This retardation was evidenced by a decreased sensitivity to light during the adaptation process, and by a higher threshold for induction of an ERG response after bleach. 相似文献
107.
Ruby Celeste Eugene Ackerman Laël C. Gatewood Clayton Reynolds George D. Molnar 《Bulletin of mathematical biology》1978,40(1):59-77
Mathematical models afford a procedure of unifying concepts and hypotheses by expressing quantitative relationships between
observables. The model presented indicates the roles of both insulin and glucagon as regulators of blood glucose, albeit in
different ranges of the blood glucose concentrations. Insulin secretion is induced during hyperglycemia, while glucagon secretion
results during hypoglycemia. These are demonstrated by simulations of a mathematical model conformed to data from the oral
glucose tolerance test and the insulin infusion test in normal control subjects and stable and unstable diabetic patients.
The model studies suggest the parameters could prove of value in quantifying the diabetic condition by indicating the degree
of instability.
Presented at the Society for Mathematical Biology Meeting, University of Pennsylvania, Philadelphia, August 19–21, 1976. 相似文献
108.
Chlorosis induced with a supraoptimum dose of phosphorus in nutrient solution (69 mg P l-1) was reverted by spraying of leaves of chlorotio maize plants (Zea mays L.) with FeEDTA. Biomass formation, chlorophyll and iron content were decreased in the above-ground parts of plants grown
under chlorosis-inducing conditions. Spraying always decreased content of inorganic phosphorus (Pi/Fe ratio was significantly changed), increased chlorophyll content in old plants and stimulated dry mass formation at supraoptimum
phosphorus doses. FeEDTA application improved phosphate utilization (portion of phosphate in organic bonds was increased).
This may be the basis of chlorosis-reverting effect of FeEDTA. 相似文献
109.
Ralph L. Holloway Marie Christine De La Costelareymondie 《American journal of physical anthropology》1982,58(1):101-110
Observations on petalial asymmetry for 190 hominoid endocasts are reported, and their statistical differences assessed. While all taxa of hominoids show asymmetries to various degrees, the patterns or combinations of petalial asymmetries are very different, with fossil hominids and modern Homo sapiens showing an identical pattern of left-occipital, right-frontal petalias, which contrasts with those found normally in pongids. Of the pongids, Gorilla shows the greater degree of asymmetry in left-occipital petalias. Only modern Homo and hominids (Australopithecus, Homo erectus, Neandertals) show a distinct left-occipital, right-frontal petalial pattern. Analysis by x2 statistics shows the differences to be highly significant. Due to small sample size and incompleteness of endocasts, small-brained hominids, i.e., Australopithecus, are problematical. To the degree that gross petalial patterns are correlated with cognitive task specialization, we speculate that human cognitive patterns evolved early in hominid evolution and were related to selection pressures operating on both symbolic and spatiovisual integration, and that these faculties are corroborated in the archaeological record. 相似文献
110.
Biological characterization of Trichinella isolates from various host species and geographical regions. 总被引:4,自引:0,他引:4
Forty isolates of Trichinella collected from 5 continents were compared for 7 biological characters: newborn larvae produced per female worm cultured in vitro at the seventh, eighth, and ninth day postinfection, host muscle nurse cell development time, reproductive capacity index in rats and chickens, and resistance of muscle larvae to freezing. The isolates also were compared by analyses of an environmental character of the location from which they were isolated: the isotherms for January and July. By factorial analysis of correspondence of the biological and environmental data, the 40 isolates were grouped into 8 gene pools (T1-T8). The environmental temperature-related distribution was more evident for the sylvatic isolates (T2, T3, T5, T6, T7, T8), than for T1, which was isolated from domestic pigs, and for T4, a bird-adapted, nonencapsulating genetic type. The 8 biological groups correlated closely with the 8 gene pools previously identified on the basis of allozyme analysis. These results support the concept that the genus Trichinella is composed of at least 5 distinct gene pools or sibling species: Trichinella spiralis sensu stricto (T1), Trichinella nativa (T2), Trichinella sp. (T3), Trichinella pseudospiralis (T4), and Trichinella nelsoni (T7), and 3 other groups of uncertain taxonomic status (i.e., T5, T6, and T8). 相似文献