Adenovirus-mediated expression of pig α(1,3) galactosyltransferase reconstructs Gal α(1,3) Gal epitope on the surface of human tumor cells

INTRODUCTIONGal a(1, 3) Gal (gal epitope) is a carbohydrate epitope, which is produced in large amounton the cells of pigs, mice and New World monkey(monkey of South America) by the glycosylationenzyme G alal 1 ) 4G IcNAc3- a- D- galactosyltransferase[or(1, 3)GT; EC2.4.1.511111. This enzyme is active in the Golgi appaxatus of cells and transfers galactose from the sugandonor uridine diphoSphate galactose (UDP-galactose) to the acceptor Nacetyllactosamine residue (Galaal-4GlcNAc-R…     

Cerebral dicarboxylate transport and metabolism studied with isotopically labelled fumarate,malate and malonate

Transport and metabolism of dicarboxylates may be important in the glial-neuronal metabolic interplay. Further, exogenous dicarboxylates have been suggested as cerebral energy substrates. After intrastriatal injection of [(14) C]fumarate or [(14) C]malate, glutamine attained a specific activity 4.1 and 2.6 times higher than that of glutamate, respectively, indicating predominantly glial uptake of these four-carbon dicarboxylates. In contrast, the three-carbon dicarboxylate [(14) C]malonate gave a specific activity in glutamate which was approximately five times higher than that of glutamine, indicating neuronal uptake of malonate. Therefore, neurones and glia take up different types of dicarboxylates, probably by different transport mechanisms. Labelling of alanine from [(14) C]fumarate and [(14) C]malate demonstrated extensive malate decarboxylation, presumably in glia. Intravenous injection of 75 micromol [U-(13) C]fumarate rapidly led to high concentrations of [U-(13) C]fumarate and [U-(13) C]malate in serum, but neither substrate labelled cerebral metabolites as determined by (13) C NMR spectroscopy. Only after conversion of [U-(13) C]fumarate into serum glucose was there (13) C-labelling of cerebral metabolites, and only at <10% of that obtained with 75 micromol [3-(13) C]lactate or [2-(13) C]acetate. These findings suggest a very low transport capacity for four-carbon dicarboxylates across the blood-brain barrier and rule out a role for exogenous fumarate as a cerebral energy substrate.     

Genetic analysis of functions involved in the late stages of biofilm development in Burkholderia cepacia H111

Burkholderia cepacia and Pseudomonas aeruginosa often co-exist as mixed biofilms in the lungs of patients suffering from cystic fibrosis (CF). Here, we report the isolation of 13 random mini-Tn5 insertion mutants of B. cepacia H111 that are defective in biofilm formation on a polystyrene surface. We show that the screening procedure used in this study is biased towards mutants defective in the late stages of biofilm development. A detailed quantitative analysis of the biofilm structures formed by wild-type and mutant strains revealed that the isolated mutants are impaired in their abilities to develop a typical three-dimensional biofilm structure. Molecular investigations showed that the genes required for biofilm maturation fall into several classes: (i). genes encoding for surface proteins; (ii). genes involved in the biogenesis and maintenance of an integral outer membrane; and (iii). genes encoding regulatory factors. It is shown that three of the regulatory mutants produce greatly reduced amounts of N-octanoylhomoserine lactone (C8-HSL). This compound serves as the major signal molecule of the cep quorum-sensing system. As this density-dependent regulatory system is involved in the regulation of biofilm maturation, we investigated the interplay between the three regulatory genes and the quorum-sensing cascade. The results of these investigations show that the identified genes encode for regulatory elements that are positioned upstream of the cep system, indicating that the quorum-sensing system of B. cepacia is a major checkpoint for biofilm formation.     

Advanced high school biology in an era of rapid change: a summary of the biology panel report from the NRC Committee on Programs for Advanced Study of Mathematics and Science in American High Schools

A recently released National Research Council (NRC) report, Learning and Understanding: Improving Advanced Study of Mathematics and Science in U.S. High Schools, evaluated and recommended changes in the Advanced Placement (AP), International Baccalaureate (IB), and other advanced secondary school science programs. As part of this study, discipline-specific panels were formed to evaluate advanced programs in biology, chemistry, physics, and mathematics. Among the conclusions of the Content Panel for Biology were that AP courses in particular suffer from inadequate quality control as well as excessive pressure to fulfill their advanced placement function, which encourages teachers to attempt coverage of all areas of biology and emphasize memorization of facts rather than in-depth understanding. In this essay, the Panel's principal findings are discussed, with an emphasis on its recommendation that colleges and universities should be strongly discouraged from using performance on either the AP examination or the IB examination as the sole basis for automatic placement out of required introductory courses for biology majors and distribution requirements for nonmajors.     

Methods for homocysteine analysis and biological relevance of the results

It is now widely accepted that increased total plasma homocysteine (tHcy) is a risk factor for cardiovascular disease. Hyperhomocysteinemia can be caused by impaired enzyme function as a result of genetic mutation or vitamin B (B(2), B(6), B(9), B(12)) deficiency. A lot of methods are now available for tHcy determination. High-pressure liquid chromatography (HPLC) with fluorescence detection are at present the most widely used methods but immunoassays, easier to use, begin to supplant in-house laboratory methods. In order to help with the choice of a main relevant homocysteine analytical method, the characteristics, performances and limits of the main current methods are reviewed. One major drawback among all these available methods is the transferability which is not clearly established to date. The impact of both inter-method and inter-laboratory variations on the interpretation of the tHcy results are discussed.     

农作物遗传多样性农家保护的现状及前景

农作物地方品种的有效保护是农业生物多样性的可持续利用的基础。由于现代农业的集约化生产方式使大量农作物地方品种被少数高产改良品种所取代,造成农作物基因库的严重“基因流失”（genetic erosion)。农家保护是在农业生态系统中进行的动态保护,被保护的生物多亲性可在其生境中继续进化而产生新的遗传变异,在而是农业生物多样性就地保护的重要途径。然而,尽管人们对作物品种资源农家保护的兴趣不断增长,也有大量有关农家的保护的研究和案例分析,但目前为止还没有比较成功的农家保护实例报道。因此,对农家保护的机制及科学问题进行深入的研究,并寻求一条新的途径来充分发挥农家保护应有的作用,显得格外重要。利用生物多样性布局的水稻混合间栽的生产模式,不仅解决了病害控制的问题,而且也保护了水稻地方品种的多样性。这种混合间栽的生物多样性布局和生产方式可能成为农保护的一条新途径。