Physical structure and genetic expression of the sulfonamide-resistance plasmid pLS80 and its derivatives in Streptococcus pneumoniae and Bacillus subtilis

Summary The 10-kb chromosomal fragment of Streptococus pneumoniae cloned in pLS80 contains the sul-d allele of the pneumococcal gene for dihydropteroate synthase. As a single copy in the chromosome this allele confers resistance to sulfanilamide at 0.2 mg/ml; in the multicopy plasmid it confers resistance to 2.0 mg/ml. The sul-d mutation was mapped by restriction analysis to a 0.4-kb region. By the mechanism of chromosomal facilitation, in which the chromosome restores information to an entering plasmid fragment, a BamHI fragment missing the sul-d region of pLS80 established the full-sized plasmid, but with the sul-s allele of the recipient chromosome.A spontaneous deletion beginning 1.5 kb to the right of the sul-d mutation prevented gene function, possibly by removing a promoter. This region could be restored by chromosomal facilitation and be demonstrated in the plasmid by selection for sulfonamide resistance. Under selection for a vector marker, tetracycline resistance, only the deleted plasmid was detectable, apparently as a result of plasmid segregation and the advantageous growth rates of cells with smaller plasmids. When such cells were selected for sulfonamide resistance, the deleted region returned to the plasmid, presumably by equilibration between the chromosome and the plasmid pool, to give a low frequency (10^-3) of cells resistant to sulfanilamide at 2.0 mg/ml. Models for the mechanisms of chromosomal facilitation and equilibration are proposed.Several derivatives of pLS80 could be transferred to Bacillus subtilis, where they conferred resistance to sulfanil-amide at 2 mg/ml, thereby demonstrating cross-species expression of the pneumococcal gene. Transfer of the plasmids to B. subtilis gave rise to large deletions to the left of the sul-d marker, but these deletions did not interfere with the sul-d gene function. Restriction maps of pLS80 and its variously deleted derivatives are presented.     

Aminoimidazo[1,2-a]pyridines as a new structural class of cyclin-dependent kinase inhibitors. Part 1: Design, synthesis, and biological evaluation

We have identified a novel structural class of protein serine/threonine kinase inhibitors comprised of an aminoimidazo[1,2-a]pyridine nucleus. Compounds from this family are shown to potently inhibit cyclin-dependent kinases by competing with ATP for binding to a catalytic subunit of the protein. Structure-based design approach was used to direct this chemical scaffold toward generating potent and selective CDK2 inhibitors. The discovery of this new class of ATP-site directed protein kinase inhibitors, aminoimidazo[1,2-a]pyridines, provides the basis of new medicinal chemistry tool in search for an effective treatment of cancer and other diseases that involve protein kinase signaling pathways.     

TCEN-49, a monoclonal antibody that identifies a central body antigen in the planarian Dugesia (Girardia) tigrina. Implications for pattern formation and positional signalling mechanisms

We have produced monoclonal antibodies (mAbs) against antigens of the freshwater planarian Dugesia (G.) tigrina (Girard) using standard protocols. One of these mAbs, TCEN-49, detects an antigen (TCEN-49Ag) present in most cells of the central area of the body, including the pharynx. Labelled cells seem more related by position than by lineage, suggesting that TCEN-49Ag is involved somehow in the expression of central body positional identity. The spatial and temporal changes in TCEN-49Ag expression during growth/degrowth and regeneration have been monitored and the implications of these results are discussed.     

Glucose release in mantle tissue of Mytilus: regulation by calcium ions

Glucose release activity in mantle tissue of Mytilus galloprovincialis was studied. Mantle tissue shows a basal glucose releasing activity. The external Ca2+ absence increases 2 to 3-fold the basal glucose release, and when A23187 (10 microM) was simultaneously present the release doubled that obtained in Ca2(+)-absence. EGTA (2 mM), chlorpromazine (200 microM) and lanthanum (3 mM) decreased the glucose release promoted by external Ca2+ absence. This and other data suggest that glucose release activity in mantle tissue might be controlled by Ca2+ ions.     

气候变化对黄淮海平原冬小麦产量和耗水的影响及品种适应性评估

基于IPCC5 3种代表性温室气体浓度排放路径(RCP)的情景集成数据,采用VIP生态水文模型,模拟分析了黄淮海平原未来冬小麦产量、蒸散量的气候变化响应.模拟结果表明:未考虑CO2肥效时,3种典型排放路径下,冬小麦生育期都将因气温上升而缩短,其产量和蒸散量将呈下降趋势.CO2浓度增加对作物生长的有利影响强于气候变化带来的不利影响,是未来情景下冬小麦产量增加的主要原因.以RCP4.5为例,2050s黄淮海地区冬小麦平均产量将增加14.8%(无CO2肥效时产量下降2.5%),蒸散量降低2.1%.采用积温需求更高的品种将有利于冬小麦利用CO2肥效提高其产量,但耗水量将有所增加.因此,培育适应气候变化的作物品种、发展节水农业和管理技术是应对气候变化的关键.     

Synthesis and performance of 3D-megaporous structures for enzyme immobilization and protein capture

The preparation of megaporous bodies, with potential applications in biotechnology, was attempted by following several strategies. As a first step, naive and robust scaffolds were produced by polymerization of selected monomers in the presence of a highly soluble cross‐linker agent. Ion‐exchange function was incorporated by particle embedding, direct chemical synthesis, or radiation‐induced grafting. The total ionic capacity of such systems was 1.5 mmol H⁺/g, 1.4 mmol H⁺/g, and 17 mmol H⁺/g, respectively. These values were in agreement with the ability to bind model proteins: observed dynamic binding capacity at 50% breakthrough was ?7.2 mg bovine serum albumin/g, ?7.4 hen egg‐white lysozyme (HEWL) mg/g, and ?108 HEWL mg/g. In the later case, total (static) binding capacity reached 220 mg/g. It was observed that the structure and size of the megapores remained unaffected by the grafting procedure which, however, allowed for the highest protein binding capacity. Lysozyme supported on grafted body showed extensive clarification activity against a Micrococcus lysodekticus suspension in the flow‐through mode, i.e., 90% destruction of suspended microbial cells was obtained with a residence time ≈ 18 min. Both protein capture and biocatalysis applications are conceivable with the 3D‐megaporous materials described in this work. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011     

浙江短角瘿蚊属一新种记述(双翅目:瘿蚊科)

记述采自浙江省的短角瘿蚊1新种:狭短角瘿蚊Anarete angusta Mo et Xu,sp.nov..     

Fast-developing preimplantation embryo progeny from heterogametic females in mammals.

Karyotyping and cell number estimates in preimplantation embryos from heterogametic (XY*) and homogametic (XX) females of the field mouse Akodon azarae were studied to determine whether XX-XY-XY* differences exist in the rate of preimplantation development. At the morula stage, XY embryos from heterogametic mothers had twice the mean number of cells compared with XX embryos. However, this difference in cell numbers was not seen between XX and XY embryos from homogametic mothers. In this case, mean cell numbers were similar despite embryos being XX or XY. Furthermore, the mean cell number for XX and XY morulae from homogametic females was comparable to that for XX embryos from heterogametic females. It is concluded that XY* embryos (which will develop into heterogametic females) show an accelerated rate of preimplantation development.