A comparative study on the formation of citric acid and polyols and on morphological changes of three strains of free and immobilized Aspergillus niger

Summary The formation of citric acid, oxalic acid, erythritol and glycerol by three strains of Aspergillus niger immobilized in calcium alginate was investigated and compared with that of free cells when cultivated in shake flasks under phosphate limitation. Morphological changes were followed using an electron microscope. The production of acids and polyols, the consumption of glucose and fructose, and also the morphological changes were strain-dependent. The results also reflected the influence of long storage of a strain on productivity, morphological behaviour and phosphate consumption. Offprint requests to: H.-J. Rehm     

Internode length inPisum: Genelkc

A new single gene-recessive internode length mutant inPisum, lkc, is characterized. The internodes oflkc plants are 30–40% shorter than those of comparableLkc plants, and this is attributable to reductions in both cell length and the number of cells per internode. Dwarfism in the mutant is not due to modified gibberellin (GA) levels, as determined by gas chromatography-selected ion monitoring (GC-SIM) for GA₁ and GA₂₀, and bioassay (rice cv. Tan-ginbozu). Furthermore,lkc plants are not as responsive as the wild-type to applied GA₁. The diminished stature oflkc plants appears to result from a direct or indirect interference with the transduction of the GA₁ signal.     

Processing and characterization of porous structures from chitosan and starch for tissue engineering scaffolds

Natural biodegradable polymers were processed by different techniques for the production of porous structures for tissue engineering scaffolds. Potato, corn, and sweet potato starches and chitosan, as well as blends of these, were characterized and used in the experiments. The techniques used to produce the porous structures included a novel solvent-exchange phase separation technique and the well-established thermally induced phase separation method. Characterization of the open pore structures was performed by measuring pore size distribution, density, and porosity of the samples. A wide range of pore structures ranging from 1 to 400 microm were obtained. The mechanisms of pore formation are discussed for starch and chitosan scaffolds. Pore morphology in starch scaffolds seemed to be determined by the initial freezing temperature/freezing rate, whereas in chitosan scaffolds the shape and size of pores may have been determined by the processing route used. The mechanical properties of the scaffolds were assessed by indentation tests, showing that the indentation collapse strength depends on the pore geometry and the material type. Bioactivity and degradation of the potential scaffolds were assessed by immersion in simulated body fluid.     

乌鲁木齐雅玛里克山土壤动物群落结构及其多样性研究

为了查明不同海拔高度对土壤动物群落多样性及其时空动态的影响,对乌鲁木齐雅玛里克山6种不同海拔高度样带土壤动物群落进行了调查分析,以探讨雅玛里克山土壤动物群落结构与不同海拔高度之间的关系.结果表明,共获得大、中小型土壤动物7 375只,隶属于6门16纲35目,其中真螨目(52.28%)和弹尾目(15.61%)为优势类群,共占总捕获量的67.89%,而寄螨目(8.37%)、三肠目(7.78%)、膜翅目(2.74%)、茅线目(1.53%)、双翅目幼虫(1.48%)、垫刃目(1.27%)、鞘翅目(1.11%)及半翅目(1.07%)等8类为常见类群,占总捕获量的25.35%,其余的25类为稀有类群,占总捕获量的6.76%.在6种不同海拔样带土壤动物个体数和类群数之间存在显著差异(P<0.05),个体数顺序为:样带A>样带B>样带C>样带E>样带D>样带F,而类群数顺序为:样带A>样带B>样带C>样带D>样带E>样带F.3个不同季节有明显的差异(P<0.01),其个体数依次为秋>春>夏.在6种不同高度样带和不同生境土壤动物群落多样性指标之间存在差异(P<0.05).组间聚类和排序结果表明,将6种不同海拔高度生境分为山底生境型、山中生境型及山顶生境型等三大类型.     

Systematic review of Atractus schach (Serpentes: Dipsadidae) species complex from the Guiana Shield with description of three new species

The Guiana Shield harbours one of the best preserved and largest extents of tropical forest on Earth and an immense biodiversity. The herpetofauna of this region remains poorly known. The species-rich snake genus Atractus contains ～140 species, many with complicated taxonomic histories, including A. schach. Examination of specimens in museums and newly collected material from French Guiana has allowed the illustration of hemipenial morphology for the first time and an expanded diagnosis. Concatenated molecular phylogenetic (mitochondrial and nuclear genes) and phenotypic (morphometrics, external and hemipenial morphology) analyses confirm non-monophyly of the A. flammigerus group and indicate that A. schach is a species complex with three new species described here. The geographic distribution of A. schach sensu stricto is restricted to Guiana, Surinam, and French Guiana north of Tumucumaque massif. Populations tentatively assigned to A. schach from the east from French Guiana in the Roura lowlands to Almeirim, and from central Amazonia between the Negro and Trombetas rivers in Brazil are also recognized as new species. Our results suggest that populations from south of the Amazon River are not conspecific with those from the Guiana Shield.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:A7AE40BC-4716-4302-B3BE-1F43600B0A72     

Increase in the ability of human cancer cells to induce cytotoxic T lymphocytes by ultraviolet irradiation

The roles of ultraviolet-B (UV) radiation in the immunogenicity of human cancer cells have not been fully studied. We have investigated the effects of UV radiation on metastatic melanoma and renal cell carcinoma cells with regard to MHC antigen expression and the ability to induce cytotoxic T lymphocyte (CTL) activity in peripheral blood mononuclear cells (PBMC) or tumor-infiltrating lymphocytes (TIL) against untreated autologous tumor cells. UV radiation respectively decreased or increased MHC class I expression of freshly isolated tumor cells or cultured tumor cells, and also decreased MHC class I expression of starved cultured tumor cells. It increased the ability of both freshly isolated and cultured tumor cells to induce CTL activity from PBMC against untreated autologous tumor cells. UV-irradiated subclones that were more susceptible to CTL lysis were more potent for CTL induction from TIL than either an untreated parental clone or a UV-irradiated subclone that was resistant to CTL lysis. In summary, UV radiation increased the ability of tumor cells to induce CTL activity without a corresponding effect on MHC antigen expression.This work was supported in part by a grant CA47891 from the National Cancer Institute, USA, a grant-in-aid of the comprehensive 10-years strategy for cancer control from ministry of a Health and Welfare, Japan, and the Ishibashi Research Fund, Japan