FGR对水涨龙眼座果及枝梢生长的效应

1990～1991年的研究结果表明,FGR 1000～3000ppm 4月中旬处理水涨龙眼,对提高果实座果数有明显效果,两年呈一致结果。高浓度(3000ppm)处理,1990年及1991年的座果数比对照分别增加1.38倍和1.07倍(P≤0.05),具有显著的保果效应。FGR各处理对龙眼果实品质及结果期间的夏延秋梢生长发育两年均未见不良影响。     

Decomposition and nutrient liberation rates of plant material in the Parana medio River (Argentina)

The degradation of plant material was studied in order to obtain degradation coefficients and nutrient release kinetics of the vegetation that will be submerged during the filling of the future Parana Medio man-made lake. A group of 13 plant species representative of the whole vegetation of the area were chosen.The plant samples (submerged at 2.5–4 m in the Setubal lagoon), were periodically analyzed during 97 days. The experimental data were fitted to an exponential decomposition model. The plants were classified according to their velocities of degradation into three groups: fast (K>0.01), mean (0.01>K>0.005) and slow (K<0.005). The curves of release of P, N, Ca, Mg, Na and K in function of time are presented and discussed.     

Group sequential distribution-free methods for the analysis of multivariate observations.

Many studies involve the collection of multivariate observations, such as repeated measures, on two groups of subjects who are recruited over time, i.e., with staggered entry of subjects. Various marginal distribution-free multivariate methods have been proposed for the analyses of such multivariate observations where some measures may be missing at random. Using the multivariate U statistic of Wei and Johnson (1985, Biometrika 72, 359-364), we describe the group sequential analysis of such a study where the multivariate observations are observed sequentially--both within and among subjects. We describe a multivariate generalization of the Hodges and Lehmann (1963, Annals of Mathematical Statistics 34, 598-611) estimator of a location shift that can be obtained via the multivariate U statistic with the Mann-Whitney-Wilcoxon kernel. We then describe large-sample group sequential interval estimators and tests based on an aggregate estimate of the location shift combined over all of the repeated measures. We also describe how the same steps could be employed to perform a group sequential analysis based on any one of the variety of marginal multivariate methods that have been proposed. These methods are applied to a real-life example.     

A comparison of neural networks and partial least squares for deconvoluting fluorescence spectra

This article compares backpropagation neural networks (BNN) with partial least squares (PLS) techniques in terms of their ability to deconvolute fluorescence spectra. Both actual experimental and simulated spectral data are studied for 2 binary systems. These systems consist of mixtures of tryptophan and tyrosine, and NADH and tryptophan over a total concentration range of 10(-7) to 10(-4) M. It is shown that BNN is superior to PLS for both systems.     

Enhancement of cellular immune function during cold adaptation of BALB/c inbred mice.

The cell-mediated immune function of cold-adapted BALB/c inbred mice was studied in experiments of splenic lymphocyte blastogenesis, indicated by tritium-labeled deoxythymidine incorporation and SDS-PAGE autoradiography of synthetic proteins in lymphocytes. Male BALB/c inbred mice were randomly divided into two groups: control (living at 25 degrees C) and cold-exposed (living at 2 degrees C). Results are as follows: in contrast with the control group, there was an obvious fluctuation of cell-mediated immune function in the cold-exposed group at initial cold exposure because of transient stress to cold; then cell-mediated immune function gradually recovered to control level. From Day 15, the cell-mediated immune function of the cold-exposed group was remarkably enhanced. On Day 15, the lymphocyte blastogenesis rate was increased by 20.66% (P less than 0.05), which implies the onset of cold adaptation; on Days 21 and 31, the rates increased by 80.15% (P less than 0.05) and 40.36% (P less than 0.05), respectively. Two to six months later, with continuing cold exposure, the murine lymphocyte blastogenesis rate in the cold-exposed group remained higher than that in the control group. The lymphocyte protein synthesis of the cold-exposed group, indicated by tritium-labeled leucine incorporation, apparently increased on Day 15 and the stimulated rate was 101.47% (P less than 0.05). SDS-PAGE autoradiography of synthetic proteins in lymphocytes demonstrated that after 2 weeks of cold exposure, protein bands were enriched in both quantity and quality. These results are identical to the results obtained from lymphocyte blastogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

A Single Genetic Locus, Ckr1, Defines Arabidopsis Mutants in which Root Growth Is Resistant to Low Concentrations of Cytokinin

Arabidopsis mutants resistant to cytokinin (benzyladenine [BA]) have been isolated with the intent to find plants defective in cytokinin perception or response. At low concentrations, BA produces a “cytokinin root syndrome” in which primary root elongation is inhibited, but root hair elongation is stimulated. Five independent mutants that did not express this syndrome in the presence of BA were selected. All five mutants were recessive, and crosses between them indicated that they were in the same complementation group. The genetic locus represented by these mutations has been designated ckr1 and mapped to chromosome 5.     

UNC-5, a transmembrane protein with immunoglobulin and thrombospondin type 1 domains, guides cell and pioneer axon migrations in C. elegans.

The unc-5 gene is required for guiding pioneering axons and migrating cells along the body wall in C. elegans. In mutants, dorsal migrations are disrupted, but ventral and longitudinal movements are largely unaffected. The gene was tagged for molecular cloning by transposon insertions. Based on genomic and cDNA sequencing, the gene encodes UNC-5, a transmembrane protein of 919 aa. The predicted extracellular N-terminus comprises two immunoglobulin and two thrombospondin type 1 domains. Except for an SH3-like motif, the large intracellular C-terminus is novel. Mosaic analysis shows that unc-5 acts in migrating cells and pioneering neurons. We propose that UNC-5 is a transmembrane receptor expressed on the surface of motile cells and growth cones to guide dorsal movements.     

Genetic and molecular analysis of pIP417 and pIP419: Bacteroides plasmids encoding 5-nitroimidazole resistance.

This report describes a genetic and molecular analysis of two transferable Bacteroides plasmids, pIP417 and pIP419, which carry genetic determinants conferring low-level resistance to 5-nitroimidazoles. The restriction endonuclease cleavage sites for each plasmid were localized. The NiR genetic determinants of pIP417 and pIP419 plasmids have been cloned into the Bacteroides cloning vector pBI191 (C.J. Smith, J. Bacteriol. 164, 294-301, 1985) as PvuII and Sau3A fragments, respectively. Both inserts had different restriction sites and did not cross-hybridize by Southern blot analysis. Genetic data obtained by cloning into pBI191 clearly show that the PvuII-generated fragments A (Rep) and B (Mob) of pIP417 are involved in plasmid replication and transfer, respectively. Although encoding resistance to the same antibiotic, both plasmids appeared different with regard to the 5-nitroimidazole resistance and replication genetic determinants. However, they share a homology in a region involved, at least in one case, in plasmid transfer. Considering the spontaneous high level of resistance to 5-nitroimidazole in Escherichia coli, this work, based on direct gene cloning into Bacteroides, demonstrates the value of such an approach.