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981.
Tol1和Tol2是在青鳉基因组中发现的具有自主活性的DNA转座子,而Tol1转座子的自主活性是新近才发现的,因此对它的报道较少。较之Tol2,Tol1可以携带更大片段的DNA进行转座,且Tol1的转座不受转座酶"过量表达抑制"的影响。研究已证实,Tol1转座子在秀丽线虫、斑马鱼、爪蟾和人等多种生物中具有转座活性。因此,在动物转基因和基因功能研究等方面有重要的应用前景。从Tol1转座子的结构特征、转座机制和作为基因转移载体的优点,以及应用研究等方面进行了简要的综述。 相似文献
982.
983.
984.
Xianting Zhou Bizhen Xu Changling Chu Guifang Xia Ning Li Ren Sha 《Human genetics》1984,67(3):249-251
Summary A chromosome hot point, 3p14, in healthy peasants, mentally retarded patients (MR), and epileptic patients (EP) was studied. The frequency of the hot point, 3p14 break, was significantly higher in EP. It may be caused by folic acid reduction in patients' serum induced by the antiepileptic drugs. The difference between hot point and fragile site is discussed. 相似文献
985.
986.
Freshwater green algae, Chlorella, have heavy cell walls and their size usually exceeds the lower limits of limb size of herbivorous Daphnia (Cladocera). According to the optimal foraging theory, we speculated that Daphnia would graze more exposed and relatively large Clamydomonas rather than Chlorella, and this process would lead to small-sized Chlorella becoming a superior competitor in the presence of Daphnia. We used Daphnia
magna, Clamydomonas
sajao and Chlorella pyrenoidosa to test this hypothesis. Our grazing experiments showed that Daphnia preferred C. sajao to C. pyrenoidosa, regardless of the concentration and relative abundance of these two algae. The decrease in relative abundance of high-quality
Clamydomonas in Clamydomonas–Chlorella assemblages did not diminish the grazing efficiency of Daphnia on this algal species, but increased selectivity of low-quality Chlorella. However, when the concentration of Clamydomonas was extremely high, the grazing of Daphnia on Clamydomonas decreased. In competition experiments, we observed that the presence of Clamydomonas restrained the growth potential of Chlorella; however, the introduction of herbivorous Daphnia into the competing environment weakened this influence and to some extent enhanced the growth ability of Chlorella. Moreover, we also observed that the intensity of herbivory, imposed by different densities of Daphnia, had an obvious influence on the competition outcome between Clamydomonas and Chlorella. At the highest intensity of herbivory (10 Daphnia), C. sajao was eliminated from the culture medium whereas C. pyrenoidosa could persist, but at low cell density. 相似文献
987.
988.
989.
The effects of vanadium-enriched and wild Inonotus obliquus were tested on hyperglycemic mice. The vanadium content of the culture medium was 0.6%, reaching a concentration of 3.0?mg/g in the cultured mushroom while in the wild variety is 1/100 of that amount. The toxicity of vanadium at the 3.0?mg/g level is negligible, but its anti-diabetic effects are significantly different to those of the wild variety (p?0.05). Due to its high bioavailability and low toxicity, vanadium-enriched I. obliquus could be used as a means of vanadium supplementation, with expectation of obtaining higher bioavailability and lower toxicity in animals. 相似文献
990.
The UDP-N-acetylglucosamine (UDP-GlcNAc) is present as one of the glycosyl donors for disaccharide linker (d-N-GlcNAc-l-rhamnose) and the precursor of peptidoglycan in mycobacteria. The bifunctional enzyme GlmU involves in the last two sequential
steps of UDP-GlcNAc synthetic pathway. Glucosamine-1-phosphate acetyltransferase catalyzes the formation of N-acetylglucosamine-1-phosphate
(GlcNAc-1-P) from glucosamine-1-phosphate (GlcN-1-P) and acetyl coenzyme A (Acetyl CoA), and N-acetylglucosamine-1-phosphate
uridyltransferase catalyzes the synthesis of UDP-GlcNAc from GlcNAc-1-P and UTP. The previous studies demonstrating the essentiality
of GlmU to mycobacterial survival supported GlmU as a novel and potential target for TB drugs. In this work, two accurate
and simple colorimetric assays based on 96-well microtiter plate were developed to measure the kinetic properties of bifunctional
GlmU including initial velocity, optimal temperature, optimal pH, the effect of Mg2+, and the kinetic parameters. Both of the colorimetric assays for bifunctional GlmU enzyme activities and the kinetic properties
will facilitate high-throughput screening of GlmU inhibitors. 相似文献