背包问题DNA算法的反应设计及其生物实现(英文)

有关背包问题的DNA算法近年来得到重视,文中实现了求解背包问题的并行搜索解的实验,通过最优的方法完成有限容量背包的物品选择．展示了面向反应的DNA片段设计,计算过程为溶液DNA高效连接反应,反应结果分别用定量（PCR）和定性（测序）两种方法检测．文中的方法适用于多重约束条件的优化问题．     

Bovine Muc1 is a highly polymorphic gene encoding an extensively glycosylated mucin that binds bacteria

The bovine Muc1 protein is synthesized by mammary epithelial cells and shed into milk as an integral component of the milk fat globule membrane; however, the structure and functions of this mucin, particularly in relation to lactation, are poorly defined. The objectives of this investigation were to investigate the Muc1 gene and protein structures in the context of lactation and to test the hypothesis that Muc1 has a role in innate immune defense. Polymerase chain reaction analysis of genomic DNA from 630 cattle revealed extensive polymorphism in the variable number of tandem repeats (VNTR) in the bovine Muc1 gene. Nine allelic variants spanning 7 to 23 VNTR units, each encoding 20 AA, were identified. Three alleles, containing 11, 14, and 16 VNTR units, respectively, were predominant. In addition, a polymorphism in one of the VNTR units has the potential to introduce a unique site for N-linked glycosylation. Statistical analysis indicated weak associations between the VNTR alleles and milk protein and fat percentages in a progeny-tested population of Holstein-Friesian dairy cattle. No association with somatic cell count could be demonstrated. Bovine Muc1 was purified from milk fat globule membranes and characterized. The protein was highly glycosylated, primarily with O-linked sialylated T-antigen [Neu5Ac(α2-3)-Gal(β1-3)-GalNAcα1] and, to a lesser extent, with N-linked oligosaccharides, which together accounted for approximately 60% of the apparent mass of Muc1. Purified bovine Muc1 directly bound fluorescently labeled Escherichia coli BioParticles (Invitrogen, Mount Waverley, Australia) and inhibited their binding to bovine mammary epithelial cells grown in vitro. It was also demonstrated that the expression of Muc1 mRNA in bovine mammary epithelial cells was markedly upregulated by lipopolysaccharide. Muc1 may be a pattern recognition protein that has the capacity to sequester bacteria and prevent their attachment to epithelial surfaces by immobilizing and subsequently shedding Muc1-bound bacteria from the cell surface. It was concluded that bovine Muc1 is probably an inducible innate immune effector and an important component of the first line of defense against bacterial invasion of epithelial surfaces, particularly mammary epithelial surfaces and the neonatal gut.     

Femtosecond laser-induced simultaneous surface texturing and crystallization of a-Si:H thin film: morphology study

Hydrogenated amorphous silicon (a-Si:H) thin films have been considered for use in solar cell applications because of their significantly reduced cost compared with crystalline bulk silicon; however, their overall efficiency and stability are less than that of their bulk crystalline counterparts. Limited work has been performed on solving the efficiency and stability issues of a-Si:H simultaneously. Surface texturing and crystallization on a-Si:H thin film can be achieved through one-step femtosecond laser processing, which can potentially alleviate the disadvantages of a-Si:H in solar cell applications. In this study, submicrometer conical and pillar-shaped spikes are fabricated by irradiating a-Si:H thin films deposited on glass substrates with hundreds of 800 nm-wavelength, 130 fs-duration laser pulses in air, and water environments, respectively. The formation mechanisms for the surface spikes are discussed, and the differences in the surface feature characteristics are also presented and explained within the context of the different processing environments. The effect of laser processing on light absorption and crystallinity will be studied later.     

Binary component sorption of Cu(II) and Pb(II) with activated carbon from Eucalyptus camaldulensis Dehn bark

The objective of this work is to illustrate the potential in the use of activated carbon in the binary component sorption of copper and lead ions. Eucalyptus bark was used as a precursor for the activated carbon which was prepared through the phosphoric acid activation process. This activated carbon was then used for the sorption of copper and lead ions. The quantity of the metal ions in the solution was measured with the Flame & Graphite Furnace Atomic Adsorption Spectrophotometer. The results indicated that the optimal pH for sorption was 5. The maximum sorption capacities for Cu(II) and Pb(II) were 0.45 and 0.53 mmol g⁻¹. Carboxylic, amine and amide groups were found to involve in the sorptions of Cu(II) and Pb(II). A major mechanism for the uptake of both heavy metals was proven not to be ion exchange but adsorption. In binary component sorptions, activated carbon still could sorb Pb(II) in a greater amount than Cu(II). However, the presence of the secondary metal ions suppressed the sorption of the primary metal ions. There seemed to have a linear inverse dependency between the sorption capacity and the concentration of the secondary metal ion.     

Cellular responses to chitosan in vitro: The importance of deacetylation

Chitin and chitosan (a deacetylated derivative of chitin) have been proposed for biomedical applications because of their biocompatibility and abundance in nature. We have investigated the effect of the percentage of deacetylation (%DD) of chitosan on biocompatibility from two sources, shrimp and cuttle fish, with two cell lines, L929 and BHK21(C13). The difference in %DD for each source was approximately 10% in the range of 76–90%. Biocompatibility was investigated for: (1) cell adherence and growth on the chitosan samples as substrate; (2) the effect of extract media on 2d and 7d growth; and (3) the presence of an inhibition zone. The results were similar for both cell lines. The chitosan samples were air-dried on to tissue culture-grade petri dishes to provide a substrate for the adherent-cell cultures. The higher %DD substrates from each source supported attachment of the cells, while the lower %DD did not. Cells cultured in medium conditioned by each substrate (i.e. extract medium) displayed an initial difference in growth which was abrogated in cultures incubated for 7 days. No inhibition zone was apparent. However, after 7 days, some cells were noted migrating on to the low %DD substrate disks. The morphology of these cells was changed with the presence of pseudopodia being apparent. Thus, especially with regard to attachment the %DD has a very important effect on the biocompatibility of the chitosan and should be monitored carefully.