空篷和正常板栗果实发育过程中氨基酸、碳水化合物变化规律的回归分析

本文研究了空篷和正常板栗果实发育过程中的氨基酸和碳水化合物的含量变化,并运用回归分析的方法探讨两者的变化规律及其差异．结果表明：在板栗不同发育时期,子房内氨基酸和淀粉含量变化具有规律性,并得到相关极显著的回归方程,空篷与正常栗具明显示的差异;总苞内除正常栗氨基酸含量得到相关极显著的回归方程外,其它的含量变化回归分析均未得到显著水平,空篷栗与正常栗的差异亦不显著．     

Assembly mechanism of [Fe2S2] cluster in ferredoxin from Acidithiobacillus ferrooxidans

Ferredoxin is a typical iron-sulfur protein that is ubiquitous in biological redox systems. This study investigates the in vitro assembly of a [Fe2S2] cluster in the ferredoxin from Acidithiobacillus ferrooxidans in the presence of three scaffold proteins: IscA, IscS, and IscU. The spectra and MALDI-TOF MS results for the reconstituted ferredoxin confirm that the iron-sulfur cluster was correctly assembled in the protein. The inactivation of cysteine desulfurase by L-allylglycine completely blocked any [Fe2S2] cluster assembly in the ferredoxin in E. coli, confirming that cysteine desulfurase is an essential component for iron-sulfur cluster assembly. The present results also provide strong evidence that [Fe2S2] cluster assembly in ferredoxin follows the AUS pathway.     

Development of microsatellite markers for the dove tree, Davidia involucrata (Nyssaceae), a rare endemic from China

? Premise of the study: Microsatellite primers were developed for the endangered Davidia involucrata to assess the population genetics and infer its evolutionary history. ? Methods and Results: Using both the modified magnetic bead hybridization method and the dual-suppression PCR method, we isolated and characterized 12 polymorphic microsatellite loci using 134 individuals from five populations in southwestern China. The number of alleles per locus ranged from six to 21 (mean = 10.8). The expected heterozygosity per locus ranged from 0.404 to 0.918 and observed heterozygosity ranged from 0.015 to 0.821. ? Conclusions: All of the 12 microsatellite markers developed for D. involucrata are polymorphic, and lay a solid foundation for further studies of the population genetics of this famous tree.     

Formation of a DNA mismatch repair complex mediated by ATP

The mismatch repair proteins, MutS and MutL, interact in a DNA mismatch and ATP-dependent manner to activate downstream events in repair. Here, we assess the role of ATP binding and hydrolysis in mismatch recognition by MutS and the formation of a ternary complex involving MutS and MutL bound to a mismatched DNA. We show that ATP reduces the affinity of MutS for mismatched DNA and that the modulation of DNA binding affinity by nucleotide is even more pronounced for MutS E694A, a protein that binds ATP but is defective for ATP hydrolysis. Despite the ATP hydrolysis defect, E694A, like WT MutS, undergoes rapid, ATP-dependent dissociation from a DNA mismatch. Furthermore, MutS E694A retains the ability to interact with MutL on mismatched DNA. The recruitment of MutL to a mismatched DNA by MutS is also observed for two mutant MutL proteins, E29A, defective for ATP hydrolysis, and R266A, defective for DNA binding. These results suggest that ATP binding in the absence of hydrolysis is sufficient to trigger formation of a MutS sliding clamp. However, recruitment of MutL results in the formation of a dynamic ternary complex that we propose is the intermediate that signals subsequent repair steps requiring ATP hydrolysis.     

Single-tube detection of nine bacterial antibiotic-resistance genes by a 2-dimensional multiplex qPCR assay based on fluorescence and melting temperature

Molecular Biology Reports - Simple, multiplex qPCR methods are advantages for rapid molecular diagnosis of multiple antibiotics-resistant genes simultaneously. However, the number of genes can be...     

Detection of wood boring insects by measurement of oxygen consumption

A possible method for detection of wood-boring insects in wood is the measurement of oxygen consumption. In order to develop such a method, several parameters have to be determined first. The most important one is to determine the respiration rate of possible pest species. To obtain the data for establishing the method mentioned above, the respiration rates of the following species were determined: the old house borer, Hylotrupes bajulus, common furniture beetle, Anobium punctatum and subterranean termite, Reticulitermes lucifugus. We compared the O₂ consumption between different species as well as between adults and larvae of one species in different environmental conditions (temperature, day/night and light/dark regime). The most intensive respiration rates were found for the larvae of Hylotrupes bajulus (4.0 ml/g h O₂) and Anobium punctatum (3.9 ml/g h O₂). Less intensive breathing was measured by Reticulitermes lucifugus (workers 2.9 ml/g h, nymphs 2.6 ml/g.h and soldiers 2.0 ml/g h O₂). These results indicate that it is possible to detect the presence of wood-boring insects respirometrically. To detect the presence of an individual insect in the wood by means of respirometry, the sensitivity of the instrument for oxygen measurement at the optimal conditions must be around 0.2 ml/h.     

Polymeric micelles with glycolipid-like structure and multiple hydrophobic domains for mediating molecular target delivery of paclitaxel

Herein, polymeric micelles with glycolipid-like structure and about 40 nm diameter are prepared by self-aggregation from stearate-grafted chitosan oligosaccharides in aqueous medium. The micelles, with high degree of substitution (DS), present specific spatial structure with multiple hydrophobic "minor cores", and thus obtain excellent internalization into cancer cells and accumulation in cytoplasm. Furthermore, the micelles showed pH-sensitive properties, thus favoring intracellular delivery of encapsulated drug via endocytosis. The cell cytotoxicity of paclitaxel encapsulated in micelles was improved sharply and contributed to the increased intracellular delivery of the drug. The present micelles are a promising carrier candidate for targeting therapy of antitumor drugs with a cytoplasmic molecule target.