添加玉米和水稻秸秆对淹水土壤pH、二氧化碳及交换态铵的影响

通过温室土壤培养试验,研究了不同添加量玉米和水稻秸秆对淹水土壤pH、CO₂及交换态铵的影响.结果表明：在接近中性的土壤中加入秸秆可使土壤pH值降低,4 g·kg^-1玉米和水稻秸秆处理的土壤pH值均与对照差异显著（P＜0.05）,而1 g·kg^-1玉米和水稻秸秆处理与对照差异不显著（P＞0.05）.土壤溶液中的CO₂含量随秸秆添加量的增加而增大,1 g·kg^-1玉米和水稻秸秆处理的土壤溶液CO₂含量最大值分别为35.9％和31.9％（v/v）,与对照（25.8％）差异达显著水平（P＜0.05）,但两者间差异不显著（P＞0.05）;4 g·kg^-1玉米和水稻秸秆处理的土壤溶液CO₂含量最大值分别为54.2％和41.8％（v/v）,与对照差异极显著（P＜0.01）,两者间差异也达显著水平（P＜0.05）.在不施氮肥的情况下,添加秸秆可降低土壤铵态氮浓度,且铵态氮浓度随秸秆添加量的增加而降低,不同添加量处理间差异显著（P＜0.05）;在施入氮肥的情况下,1 g·kg^-1玉米和水稻秸秆处理提高了土壤铵态氮浓度,而4 g·kg^-1玉米和水稻秸秆处理降低了土壤铵态氮浓度.无论是否施入氮肥,玉米和水稻秸秆处理的土壤铵态氮浓度差异不显著（P＞0.05）.     

Alkane composition diversity among populations of dwarf forms of Juniperus communis L.: comparison between western Europe and northern American populations

The cuticular wax composition of leaves has been analysed in three western European populations (Corsica, central Pyrenees, northern Alps) of Juniperus communis var. saxatilis Pall. (=  J. nana Willd., nom illeg.) and in one population of J. communis L. var. depressa Pursh. from North America (Sierra Nevada). Gas chromatography shows the presence of 13 alkanes in all samples ranging from C₂₃ to C₃₅ with important intraspecific polymorphism in alkane content. The dominant alkanes range from C₃₃ to C₃₅. Alkanes C₂₁ and C₂₂ were found only in Corsica and Sierra Nevada populations. Canonical discriminant analysis separated the J. communis L. var. depressa Pursh. of the population of Sierra Nevada from other populations of J. communis var. saxatilis Pall. on the basis of their higher C₃₁ content and the constant presence of C₂₁ and C₂₂ alkanes. J. communis var. saxatilis Pall. populations from the Pyrenees are close to northern Alps populations characterized by high concentrations of C₃₃, C₃₄ and C₃₅ alkanes. This paper confirms the existence of Juniperus var. saxatilis Pall. in the Pyrenees (France).  © The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 165–168.     

Gender-dependent IL-12 secretion by APC is regulated by IL-10

Female SJL mice preferentially mount Th1-immune responses and are susceptible to the active induction of experimental allergic encephalomyelitis. By contrast, young adult male SJL are resistant to experimental allergic encephalomyelitis due to an APC-dependent induction of Th2 cells. The basis for this gender-dependent differential T cell induction was examined by analysis of macrophage APC cytokine secretion during T cell activation. APC derived from females secrete IL-12, but not IL-10, during T cell activation. By contrast, APC derived from males secrete IL-10, but not IL-12, during T cell activation. Activation of T cells with APC derived from the opposite sex demonstrated that these cytokines were derived from the respective APC populations. Furthermore, inhibition of IL-10, but not TGF-beta, during T cell activation resulted in the secretion of IL-12 by male-derived APC. APC from naive male mice, in which IL-10 was reduced in vivo before isolation, also secrete IL-12, demonstrating altered APC cytokine secretion was due to an environment high in IL-10 before Ag encounter. Finally, APC derived from castrated male mice preferentially secrete IL-12 during T cell activation. These data demonstrate a link between gonadal hormones and APC activity and suggest that these hormones alter the APC, thereby influencing cytokine secretion during initial T cell activation.     

Combined prime-boost vaccination against tick-borne encephalitis (TBE) using a recombinant vaccinia virus and a bacterial plasmid both expressing TBE virus non-structural NS1 protein

Background  

Heterologous prime-boost immunization protocols using different gene expression systems have proven to be successful tools in protecting against various diseases in experimental animal models. The main reason for using this approach is to exploit the ability of expression cassettes to prime or boost the immune system in different ways during vaccination procedures. The purpose of the project was to study the ability of recombinant vaccinia virus (VV) and bacterial plasmid, both carrying the NS1 gene from tick-borne encephalitis (TBE) virus under the control of different promoters, to protect mice against lethal challenge using a heterologous prime-boost vaccination protocol.     

SEGMENTATION APPROACHES THAT DIFFERENTIATE CONSUMPTION FREQUENCY FROM SENSORY PREFERENCE1

People can eat a food without having a strong preference for it, and people can prefer a food without eating it. Given this seeming disconnect between attitude and behavior, which type of measure or segment can best be used to profile or identify loyal consumer segments of a food, such as soy? This research compares a usage‐based method (heavy‐light‐nonusers) with a new attitude‐based method (seeker‐neutral‐avoider), and finds that the attitude‐based method differentiates purchase‐related intentions better than the usage‐based method. Implications for profiling consumer taste patterns and consumer segments are provided.     

Characterization and molecular genetic complementation of mutants affecting dimorphism in the fungus ustilago maydis

Ustilago maydis, the causal agent of corn smut disease, displays dimorphic growth in which it alternates between a unicellular, nonpathogenic yeast-like form and a dikaryotic, pathogenic filamentous form. Previously, a constitutively filamentous haploid mutant was obtained. Complementation of this mutant led to the isolation of the gene encoding adenylate cyclase, uac1. Secondary mutagenesis of a uac1 disruption strain allowed the isolation of a large number of suppressor mutants, termed ubc, for Ustilago bypass of cyclase, lacking the filamentous phenotype. Analysis of one of these suppressor mutants previously led to the identification of the ubc1 gene, encoding the regulatory subunit of cAMP-dependent protein kinase. In this report we describe the isolation of cosmids containing three new ubc genes, termed ubc2, ubc3, and ubc4. We also describe the morphology of the ubc2, ubc3, and ubc4 mutants in a uac1- background as well as in a background with a functional uac1 gene. In addition, we describe several mutant strains not complemented with any of the genes currently in hand and that are thus presumed to possess mutations in additional ubc genes. Copyright 1998 Academic Press.     

Body size effects and rates of cytochrome b evolution in tube-nosed seabirds

Variation in rates of molecular evolution now appears to be widespread. The demonstration that body size is correlated with rates of molecular evolution suggests that physiological and ecological factors may be involved in molecular rate variation, but large-scale comparative studies are still lacking. Here, we use complete cytochrome b sequences from 85 species of tube-nosed seabirds (order Procellariiformes) and 5 outgroup species of penguins (order Sphenisciformes) to test for an association between body mass and rates of molecular evolution within the former avian order. Cladistic analysis of the 90 sequences estimates a phylogeny largely consistent with the traditional taxonomy of the Procellariiformes. The Diomedeidae, Procellariidae, and Pelecanoididae are monophyletic, while the Hydrobatidae are basal and paraphyletic. However, the two subfamilies within the Hydrobatidae (Hydrobatinae and Oceanitinae) are monophyletic. A likelihood ratio test detects significant deviation from clocklike evolution in our data. Using a sign test for an association between body mass and branch length in the seabird phylogeny, we find that larger taxa tend to have shorter terminal branch lengths than smaller taxa. This observation suggests that rates of mitochondrial DNA evolution are slower for larger taxa. Rate calibrations based on the fossil record reveal concordant body size effects. We interpret these results as evidence for a metabolic rate effect, as the species in this order exhibit large differences in metabolic rates, which are known to be highly correlated with body mass in this group. Our results support previous findings of body size effects and show that this effect can be significant even within a single avian order. This suggests that even lineage-specific molecular clocks may not be tenable if calibrations involve taxa with different metabolic rates.