Effect of soil microorganisms on the growth of roots in rice seedlings

Abstract

Root system of rice seedlings grown on nutrient solution inoculated with soil microorganisms were examined morphologically in comparison with those obtained under sterile condition. In the presence of soil microorganisms, primary roots increased in their number and decreased in the total length. Inoculated plants had more secondary roots equipped with tertiary roots. In addition, longer root hairs developed densely on primary and secondary roots of the inoculated seedlings.

Anatomical examination of the primary roots revealed that the number and width of cortical layers, as well as the length and width of the cortical cells, were increased by the effect of microorganisms. Microbial effect on outer morphology of rice roots, consequently, was estimated to have been induced from the alteration in histological and cytological activities including the activation of the periclinal divisions of the epidermal cells, the inactivation of the transverse divisions of the cortical cells and the activation of the elongation of cortical cells.     

Robust reconstitution of active cell-cycle control complexes from co-expressed proteins in bacteria

ABSTRACT: BACKGROUND: Cell proliferation is an important determinant of plant growth and development. In addition,modulation of cell-division rate is an important mechanism of plant plasticity and is key inadapting of plants to environmental conditions. One of the greatest challenges inunderstanding the cell cycle of flowering plants is the large families of CDKs and cyclins thathave the potential to form many different complexes. However, it is largely unclear whichcomplexes are active. In addition, there are many CDK- and cyclin-related proteins whosebiological role is still unclear, i.e. whether they have indeed enzymatic activity. Thus, abiochemical characterization of these proteins is of key importance for the understanding oftheir function. RESULTS: Here we present a straightforward system to systematically express and purify active CDKcyclincomplexes from E. coli extracts. Our method relies on the concomitant production of aCDK activating kinase, which catalyzes the T-loop phosphorylation necessary for kinaseactivity. Taking the examples of the G1-phase cyclin CYCLIN D3;1 (CYCD3;1), the mitoticcyclin CYCLIN B1;2 (CYCB1;2) and the atypical meiotic cyclin SOLO DANCERS (SDS) inconjunction with A-, B1- and B2-type CDKs, we show that different CDKs can interact withvarious cyclins in vitro but only a few specific complexes have high levels of kinase activity. CONCLUSIONS: Our work shows that both the cyclin as well as the CDK partner contribute to substratespecificity in plants. These findings refine the interaction networks in cell-cycle control andpinpoint to particular complexes for modulating cell proliferation activity in breeding.     

Comparative proteomic analysis of liver mitochondrial proteins derived from cloned adult pigs reconstructed with Meishan pig fibroblast cells and European pig enucleated oocytes

Somatic cell nuclear transfer (SCNT) has been exploited in efforts to clone and propagate valuable animal lineages. However, in many instances, recipient oocytes are obtained from sources independent of donor cell populations. As such, influences of potential nuclear-cytoplasmic incompatibility, post SCNT, are largely unknown. In the present study, alterations in mitochondrial protein levels were investigated in adult SCNT pigs produced by microinjection of Meishan pig fetus fibroblast cells into enucleated matured oocytes (maternal Landrace genetic background). Mitochondrial fractions were prepared from liver samples by mechanical homogenization and differential centrifugation. Liver mitochondria were then subjected to two-dimensional difference gel electrophoresis (2-D DIGE). Protein expression changes were confirmed with a volume ratio greater than 2 fold (P<0.05). 2-D DIGE analysis further revealed differential expression of three proteins between the Meishan (n=3) and Landrace (n=3) breeds. Differential expression patterns of 16 proteins were detected in SCNT pig liver tissue (n=3) when compared with Meishan control samples. However, none of the 16 proteins correlated with the three differentially expressed Meishan and Landrace liver mitochondrial proteins. In summary, alteration of mitochondrial protein expression levels was observed in adult SCNT pigs that did not reflect the breed difference of the recipient oocytes. Comparative proteomic analysis represents an important tool for further studies on SCNT animals.     

Simultaneous detection of benzimidazole-resistant strains of Fusarium head blight using the loop-mediated isothermal amplification-fluorescent loop primer method

The loop-mediated isothermal amplification (LAMP)-fluorescent loop primer (FLP) method detects genetic polymorphisms by using a LAMP amplicon and measuring the peak temperatures of fluorescence resonance energy transfer between an FLP and a quencher probe, which is specifically hybridized to a sequence including a single nucleotide polymorphism (SNP). In the present study, the LAMP-FLP method was used to detect mutant genotypes F167Y, E198Q, and F200Y in the β2-tubulin gene region of causal pathogens of Fusarium head blight of wheat that result in methyl benzimidazole carbamate (MBC) resistance, proving its usefulness for monitoring strains with SNPs in target regions of MBC resistance.     

Experimental studies on SO2 injuries in higher plants III: Inhibitory effect of suite ion on 14 CO 2 fixation

Photosynthesis decreases reversibly in plants exposed to SO₂. Photosynthesis recovers when the exposure to SO₂ is discontinued. Inactivation of a photosynthetic enzyme, ribulose-1,5-diphosphate carboxylase, by sulfonation of its SH groups was investigated as a cause of the reversible reduction of photosynthesis. The relationship between the sulfite ion concentration in the reaction mixture and ¹⁴CO₂ fixation catalized by the enzyme which was prepared from alfalfa leaves was explored by using radioactive NaHCO₃. About 50% and 85% inhibitions of ¹⁴CO₂ fixation were observed at 3 × 10^?3 M and 3 × 10^?2 M concentration of sulfite ion in the reaction mixture, respectively. The accumulation of 3 × 10^?4 M sulfite ion on the reaction site of the enzyme involved in the plants which were exposed to SO₂ could considerably reduce the CO₂ assimilation of the plant.     

Multiplex PCR and Genescan analysis to detect immunoglobulin heavy chain gene rearrangement in feline B-cell neoplasms

Lymphoid neoplasms are usually diagnosed on the basis of cytological and histopathological findings. However, in some cases, discrimination of lymphoid neoplasms from reactive lymphoid proliferation is difficult. PCR amplification of complementarity-determining region 3 (CDR3) of the immunoglobulin heavy-chain variable region (IGHV) gene can be used to assess clonality of B-cell populations as a supportive diagnostic tool for B-cell neoplasms. Because of the sequence variation and possible somatic hypermutation of the IGHV gene, sensitivity of the PCR-based assay to detect clonal IGHV gene rearrangement largely depends on the sequences and numbers of primer sets. Prior to the development of an efficient assay, we cloned and sequenced 97 IGHV complementary DNAs (48 IGHV-1 and 49 IGHV-3 clones) from normal cat spleens. On the basis of these sequences, we designed 6 forward primers at the variable region and 5 reverse primers at the joining region. Using each of 6 forward primers and a mixture of 5 reverse primers, we amplified CDR3 of IGHV genes and analyzed the PCR products by conventional PAGE and Genescan analyses using fluorescence-labeled primers. Twenty-six feline B-cell neoplasms diagnosed by histopathological and immunohistochemical examinations were subjected to the newly developed analysis of IGHV gene rearrangement. Clonal IGHV gene rearrangement was detected in 22 of 26 (84%) samples by both PAGE and Genescan analyses. To reduce the number of PCR reactions, we constructed a multiplex PCR analysis system using a mixture of IGHV-1- and IGHV-3-specific primers as forward primers and a mixture of 5 joining region reverse primers. Results of the multiplex PCR were 100% concordant with those obtained by each of the singleplex PCRs. The multiplex PCR-based assay and Genescan analysis developed in the present study would be useful and practical tools to detect clonal IGHV gene rearrangement in feline B-cell neoplasms.     

Olfactory plasticity is regulated by pheromonal signaling in Caenorhabditis elegans

Population density-dependent dispersal is a well-characterized strategy of animal behavior in which dispersal rate increases when population density is higher. Caenorhabditis elegans shows positive chemotaxis to a set of odorants, but the chemotaxis switches from attraction to dispersal after prolonged exposure to the odorants. We show here that this plasticity of olfactory behavior is dependent on population density and that this regulation is mediated by pheromonal signaling. We show that a peptide, suppressor of NEP-2 (SNET-1), negatively regulates olfactory plasticity and that its expression is down-regulated by the pheromone. NEP-2, a homolog of the extracellular peptidase neprilysin, antagonizes SNET-1, and this function is essential for olfactory plasticity. These results suggest that population density information is transmitted through the external pheromone and endogenous peptide signaling to modulate chemotactic behavior.     

Reduction of ferric chelate caused by various wood-rot fungi

The reduction of ferric chelate caused by various wood-rot fungi was analyzed. Ferric chelate reductive activity was detected in cell-free extracts of seven wood-rot fungi:Phanerochaete chrysosporium, P. sordida YK-624,Ganoderma sp. YK-505,Coriolus versicolor, Bjerkandera adusta, Tyromyces palustris, andGloeophyllum trabeum. These fungi produced NADPH- or NADH-dependent ferric chelate reductive enzymes (or both) of different molecular weight. In the liquid culture ofP. sordida YK-624 andC. versicolor, a positive correlation was observed between extracellular MnP activity and intracellular NADPH-dependent ferric chelate reductive activity.