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排序方式: 共有8063条查询结果,搜索用时 484 毫秒
51.
João Ricardo Sato Claudinei Eduardo Biazoli Ana Paula Arantes Bueno Arthur Caye Pedro Mario Pan Marcos Santoro Jessica Honorato-Mauer Giovanni Abrahão Salum Marcelo Queiroz Hoexter Rodrigo Affonseca Bressan Andrea Parolin Jackowski Euripedes Constantino Miguel Sintia Belangero Luis Augusto Rohde 《Genes, Brain & Behavior》2023,22(2):e12838
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This study addresses the ability of DNA fragments from various sources to mediate autonomous DNA replication in cultured Drosophila melanogaster cells. We created a series of plasmids containing genomic DNA fragments from the Ultrabithorax gene of Drosophila and tested them for autonomous replication after transfection into Schneider line 2 cells. We found that all plasmids containing Drosophila DNA fragments were able to replicate autonomously, as were plasmids containing random human and Escherichia coli genomic DNA fragments. Most of the plasmids were detectable 18 days after transfection in the absence of selection, suggesting that transfected DNA is maintained in Drosophila cells without rapid loss or degradation. The finding that all plasmids containing Drosophila, human, or bacterial DNA replicate autonomously in Drosophila cells suggests that the signals that direct autonomous replication in Drosophila contain a low degree of sequence specificity. A two-dimensional gel analysis of initiation on one of the plasmids was consistent with many dispersed initiation sites. Low sequence specificity and dispersed initiation sites also characterize autonomous replication in human cells and Senopus eggs and may be general properties of autonomous replication in animal cells. 相似文献
54.
J. C. du Preez M. Immelman J. L. F. Kock S. G. Kilian 《World journal of microbiology & biotechnology》1997,13(1):81-87
The effect of different initial acetic acid concentrations on the growth of and lipid and gamma-linolenic acid (GLA) production
byMucor circinelloides CBS 203.28 was determined in a 14 litre stirred tank reactor operated in a fedbatch, pH-stat mode with acetic acid as carbon
source and pH titrant. Increased acetic acid concentrations in the culture resulted in a significant increase in the crude
oil content of the biomass. By contrast, all the other parameters such as the biomass concentration, GLA and oil yield on
acetic acid, the GLA content of the biomass and oil, the growth rate and volumetric rate of GLA production decreased with
an increase in acetic acid concentration. The best results were obtained with acetic acid at 2 g/1, which gave 39.8 mg GLA/g
biomass and 15.6% GLA in the neutral lipid fraction, amounting to 340 mg GLA/1 culture. A decrease in the glyco- and phospho-lipid
fractions during the cultivation coincided with an increase in the neutral lipid fraction. The GLA content of the biomass
remained within rather narrow limits of 3.5% to 4% of the biomass, irrespective of the oil content of the biomass. The fatty
acid profile was not greatly affected by the acetic acid concentration. The hyphae of the fungus were characterized by the
accumulation of large intracellular oil droplets and some septa delimited the hyphae. 相似文献
55.
Philippus A. Venter Bronwin Dawson Joan L. Du Toit Esme L. Smith Nicolene Kritzinger Annette S. Landman Anna S. Cronje Johann Op't Hof 《Human genetics》1984,67(2):121-125
Summary We present here a familial case of a paracentric inversion in man with a short review of the literature. A paracentric inversion of chromosome 10(q11q26) was found in the amniocytes drawn for advanced maternal age. The presence of the inversion was investigated in 35 family members in three generations. No recombinants were recognized. The significance of these data for appropriate genetic counselling and possible reproductive risks is discussed.Genetic Nurses, Department of Health and Welfare 相似文献
56.
E L du Brul 《American journal of physical anthropology》1977,47(2):305-320
Three predominant influences mark the evolution of human head form: big brain, erect bipedalism, modified oral apparatus. Confusing interplay between different adaptive requirements of each feature has made explanation of skull structure extremely difficult in the past. It now seems possible to isolate each influence in early fossil forms. A model of mammalian modes of feeding adaptation is proposed in the form of a “Natural Experiment” for tighter analysis of fossil forms. Two forms of australopithecines are recognized, “gracile” and “robust.” Both had closely similar brains, both had erect bipedalism, but each had different masticatory construction. Separation of the first two similar influences isolates the adaptive differences in oral mechanics. The gracile form had a projecting oral apparatus, distinct canine and zygomatic buttresses, moderate jaw-lever development, jaw joint not unlike most higher primates, large unusual anterior teeth, moderately sized posterior teeth. The robust form had a retruded, greatly deepened oral apparatus, “dished-in” face with fused canine and zygomatic buttresses, powerful jaw-lever development, distinctively different joint construction, remarkably small anterior teeth, enormous posterior teeth. Striking evidence for extraordinary jaw movements emerges from these features in the robust form. This is strongly supported by remarkably close parallels in Ursidae: grizzly bear and giant panda. 相似文献
57.
Purified Agave aminopeptidase was characterized with respect to the thermodynamic properties of the reaction catalysed by the enzyme. Kinetic studies were conducted at different temperatures ranging from 7.8 to 45°. The energy of activation, Ea, as well as the constants ΔH, ΔF and ΔS were calculated for both the formation of the enzyme-substrate complex, and the dissociation of the enzyme-product complex. Kinetic studies in buffers with varying dielectric constants enabled the determination of the electrostatic as well as the non-electrostatic components of ΔS. These results fit well into the overall kinetic picture of this enzyme-catalysed reaction as reported previously. 相似文献
58.
Copper toxicosis of Bedlington Terriers (Chronic progressive hepatitis) is a genetically transmitted disease. The typical feature of this disease is accumulation of copper in the liver tissue. The changes vary from mild hepatitis to chronic progressive hepatitis and cirrhosis. The material of this study consists of 2 cases of copper toxicosis examined at the Department of Pathology in Helsinki in the years 1980–82. Moreover a re-examination of tissue samples was made of all Bedlington Terriers examined during the years 1969–1982 at the same department. Six of the 14 examined dogs showed a positive reaction for copper in their liver tissues. The possible relationship of the examined dogs is not yet known. 相似文献
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