Spatial distribution of root activity and nitrogen fixation in sorghum/pigeonpea intercropping on an Indian Alfisol

A medium-duration pigeonpea cultivar (ICP 1–6) and a hybrid sorghum (CSH 5) were grown on a shallow Alfisol in monocropping and intercropping systems. Using a monolith method, spatial distribution of nodulation, acetylene reduction activity (ARA) and root respiration were measured.The number, mass and ARA of nodules decreased exponentially with distance from the plant base except at the late reproductive stage. Nodulation and ARA tended to be higher in the intercrop than in the monocrop.Respiration rate of roots increased with distance from the plant base and reached a maximum value at about 20–30 cm. The rate was higher in pigeonpea than in sorghum and also higher in intercrop than in monocrop.This study suggests that pigeonpea roots are physiologically more active than sorghum roots, implying that pigeonpea may become a strong competitor for nutrients in the soil when intercropped. The nitrogen-fixing ability of pigeonpea may be enhanced by intercropping because the sorghum rapidly absorbed inorganic N which would otherwise inhibit N₂ fixation.     

Expression of the [beta]-Glucuronidase Gene in Pollen of Lily (Lilium longiflorum), Tobacco (Nicotiana tabacum), Nicotiana rustica,and Peony (Paeonia lactiflora) by Particle Bombardment

A [beta]-glucuronidase (GUS) gene that is under the control of the anther-specific LAT52 promoter of tomato (Lycopersicon esculentum) and the nopaline synthetase polyadenylation terminator was successfully expressed in pollen of Lilium longiflorum, Nicotiana tabacum, Nicotiana rustica, and Paeonia lactiflora using a pneumatic particle gun. The GUS gene in plasmid pBI221 was also expressed, to a lesser extent, in pollen of all of these species. The presence of methanol in the substrate solution for histochemical GUS assay and the incubation time in this solution influenced successful detection of GUS expression in bombarded pollen. Cytological analysis of GUS-expressing pollen of lily showed that introduced gold particles were seen in intracellular compartments of pollen, including the vegetative cytoplasm, vegetative nucleus, and generative cytoplasm.     

Solid-state NMR analysis of calcium and d-mannose binding of BMY-28864, a water-soluble analogue of pradimicin A

Pradimicin A (PRM-A) is a unique antibiotic with a lectin-like ability to recognize d-mannopyranosides (Man) in the presence of Ca(2+) ion. BMY-28864 (1) is a water-soluble analogue of PRM-A, which has been extensively used for studies on the mode of Man recognition and antifungal action of pradimicins. Although it has been assumed that PRM-A and 1 bind Man in a similar fashion, direct experimental evidence has yet to be provided. In this report, we compared Ca(2+) and Man binding of 1 with that of PRM-A through two solid-state NMR experiments. The solid-state (113)Cd NMR analysis using (113)Cd(2+) ion as a surrogate for Ca(2+) ion suggested the similarity in Ca(2+) coordination of PRM-A and 1. The dipolar assisted rotational resonance (DARR) analysis using (13)C-labeled 1 clearly showed that 1 as well as PRM-A binds Man near its carboxyl group. These results collectively indicate that the mode of binding of Ca(2+) ion and Man is nearly identical between PRM-A and 1.     

Metal ion dependency of serine racemase from Dictyostelium discoideum

D-Serine is known to act as an endogenous co-agonist of the N-methyl-D-aspartate receptor in the mammalian brain and is endogenously synthesized from L-serine by a pyridoxal 5'-phosphate-dependent enzyme, serine racemase. Though the soil-living mycetozoa Dictyostelium discoideum possesses no genes homologous to that of NMDA receptor, it contains genes encoding putative proteins relating to the D-serine metabolism, such as serine racemase, D-amino acid oxidase, and D-serine dehydratase. D. discoideum is an attractive target for the elucidation of the unknown functions of D-serine such as a role in cell development. As part of the elucidation of the role of D-serine in D. discoideum, we cloned, overexpressed, and examined the properties of the putative serine racemase exhibiting 46% amino acid sequence similarity with the human enzyme. The enzyme is unique in its stimulation by monovalent cations such as Na(+) in addition to Mg(2+) and Ca(2+), which are well-known activators for the mammalian serine racemase. Mg(2+) or Na(+) binding caused two- to ninefold enhancement of the rates of both racemization and dehydration. The half-maximal activation concentrations of Mg(2+) and Na(+) were determined to be 1.2?μM and 2.2?mM, respectively. In the L-serine dehydrase reaction, Mg(2+) and Na(+) enhanced the k (cat) value without changing the K (m) value. Alanine mutation of the residues E207 and D213, which correspond to the Mg(2+)-binding site of Schizosaccharomyces pombe serine racemase, abolished the Mg(2+)- and Na(+)-dependent stimulation. These results suggest that Mg(2+) and Na(+) share the common metal ion-binding site.     

Comparative angiogenic activities of induced pluripotent stem cells derived from young and old mice

Advanced age is associated with decreased stem cell activity. However, the effect of aging on the differentiation capacity of induced pluripotent stem (iPS) cells into cardiovascular cells has not been fully clarified. We investigated whether iPS cells derived from young and old mice are equally capable of differentiating into vascular progenitor cells, and whether these cells regulate vascular responses in vivo. iPS cells from mouse embryonic fibroblasts (young) or 21 month-old mouse bone marrow (old) were used. Fetal liver kinase-1 positive (Flk-1(+)) cells, as a vascular progenitor marker, were induced after 3 to 4 days of culture from iPS cells derived from young and old mice. These Flk-1(+) cells were sorted and shown to differentiate into VE-cadherin(+) endothelial cells and α-SMA(+) smooth muscle cells. Tube-like formation was also successfully induced in both young and old murine Flk-1(+) cells. Next, hindlimb ischemia was surgically induced, and purified Flk-1(+) cells were directly injected into ischemic hindlimbs of nude mice. Revascularization of the ischemic hindlimb was significantly accelerated in mice transplanted with Flk-1(+) cells derived from iPS cells from either young or old mice, as compared to control mice as evaluated by laser Doppler blood flowmetry. The degree of revascularization was similar in the two groups of ischemic mice injected with iPS cell-derived Flk-1(+) cells from young or old mice. Transplantation of Flk-1(+) cells from both young and old murine iPS cells also increased the expression of VEGF, HGF and IGF mRNA in ischemic tissue as compared to controls. iPS cell-derived Flk-1(+) cells differentiated into vascular progenitor cells, and regulated angiogenic vascular responses both in vitro and in vivo. These properties of iPS cells derived from old mice are essentially the same as those of iPS cells from young mice, suggesting the functionality of generated iPS cells themselves to be unaffected by aging.     

Chloroplast DNA phylogeny of Asian Bamboos (Bambusoideae,Poaceae) and its systematic implication

The bamboo is usually classified as a subfamily Bambusoideae of Poaceae, and includes approximately 20 genera and 300 species. To estimate phylogenetic relationships among these genera, we examined restriction site mutations of cpDNA for 16 Asian genera. In the cladogram obtained, the Bambosoideae was divided into two major lineages, one includingPleioblastus, Pseudosasa, Semiarundinaria, Shibataea, Phyllostachys, Sasa, Sinobambusa, Chimonobambusa, Arthrostylidium, andYushania, and the other consisting ofBambusa, Gigantochloa, Dendrocalamus, Thyrostachys, Melocanna, andSchizostachyum. Monophylly of each clade was supported by 83% and 98% bootstrap probability, respectively. The present result supports monophylly of Arundinarieae of Potztal's (1964) classical system, but does not support his treatment to recognize Dendrocalameae.     

Fibronectin Combined with Stem Cell Factor Plays an Important Role in Melanocyte Proliferation,Differentiation and Migration in Cultured Mouse Neural Crest Cells

Stem cell factor (SCF) is essential to the migration and differentiation of melanocytes during embryogenesis because mutations in either the SCF gene, or its ligand, KIT, result in defects in coat pigmentation in mice. Using a neural crest cell (NCC) primary culture system from wild‐type mice, we previously demonstrated that KIT‐positive and/or L ‐3, 4‐dihydroxyphenylalanine (DOPA)‐positive melanocyte precursors proliferate following the addition of SCF to the culture medium. Extracellular matrix (ECM) proteins are considered to play a role in the migration and differentiation of various cells including melanocytes. We cultured mouse NCCs in the presence of SCF in individual wells coated with ECM; fibronectin (FN), collagen I (CLI), chondroitin sulphate, or dermatan sulphate. More KIT‐positive cells and DOPA‐positive cells were detected in the presence of SCF on ECM‐coated wells than on non‐coated wells. A statistically significant increase in DOPA‐positive cells was evident in FN and CLI wells. In contrast, in the absence of SCF, few DOPA‐positive cells and KIT‐positive cells were detected on either the ECM‐coated or non‐coated wells. We concluded that ECM affect melanocyte proliferation and development in the presence of SCF. To determine the key site of FN function, RGDS peptides in the FN sequence, which supports spreading of NCCs, were added to the NCC culture. The number of DOPA‐positive cells decreased with RGDS concentration in a dose‐dependent fashion. Immunohistochemical staining revealed the presence of integrin a5, a receptor of RGDS, in NCCs. These results suggest the RGDS domain of FN plays a contributory role as an active site in the induction of FN function in NCCs. In addition, we examined the effect of FN with SCF on the NCC migration by measuring cluster size, and found an increase in size following treatment with FN.     

Phosphoenolpyruvate:carbohydrate phosphotransferase systems in Enterococcus faecalis

A wild-type strain of Enterococcus faecalis and its mutants resistant to 2-deoxy-D-glucose (2DG) were examined for the presence of phosphoenolpyruvate:carbohydrate phosphotransferase systems (PTSs) with 12 carbohydrates, which were utilized by the organism, as the substrates. The wild-type strain possessed a constitutive mannose-PTS, which was reactive with glucose, mannose, glucosamine, 2DG and fructose. This activity was absent in the mutants. No independent glucose- or fructose-PTS was found in the mannose-PTS-defective mutants. The mutants, however, showed a low level of a constitutive PTS activity with maltose, suggesting the existence of an independent maltose-PTS in the organism. Both wild-type and mutant strains possessed inducible lactose-, mannitol-, and trehalose-PTSs. Lactose-PTS was induced by either lactose or galactose in the parent, but only by lactose in the mutants. The lactose-PTS was not reactive with galactose, and no separate galactose-PTS was present. These observations suggest that the inducer for lactose-PTS, probably being galactose 6-phosphate, may not be formed from galactose in the organism when the constitutive mannose-PTS is lost by mutation.     

Increased Expression of 15-Hydroxyprostaglandin Dehydrogenase in Spinal Astrocytes During Disease Progression in a Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult-onset, progressive, and fatal neurodegenerative disease caused by selective loss of motor neurons. Both ALS model mice and patients with sporadic ALS have increased levels of prostaglandin E2 (PGE2). Furthermore, the protein levels of microsomal PGE synthase-1 and cyclooxygenase-2, which catalyze PGE2 biosynthesis, are significantly increased in the spinal cord of ALS model mice. However, it is unclear whether PGE2 metabolism in the spinal cord is altered. In the present study, we investigated the protein level of 15-hydroxyprostaglandin dehydrogenase (15-PGDH), a key enzyme in prostaglandin metabolism, in ALS model mice at three different disease stages. Western blotting revealed that the 15-PGDH level was significantly increased in the lumbar spinal cord at the symptomatic stage and end stage. Immunohistochemical staining demonstrated that 15-PGDH immunoreactivity was localized in glial fibrillary acidic protein (GFAP)-positive astrocytes at the end stage. In contrast, 15-PGDH immunoreactivity was not identified in NeuN-positive large cells showing the typical morphology of motor neurons in the anterior horn. Unlike 15-PGDH, the level of PGE2 in the spinal cord was increased only at the end stage. These results suggest that the significant increase of PGE2 at the end stage of ALS in this mouse model is attributable to an imbalance of the synthetic pathway and 15-PGDH-dependent scavenging system for PGE2, and that this drives the pathogenetic mechanism responsible for transition from the symptomatic stage.     

Gender differences in muscle strength after 20 days bed rest

In the previous studies, when Bed rest (BR) was prolonged over 2 weeks, muscle mass and strength began progressively to become reduced. There are many publications investigating the changes in skeletal muscles during inactivity. However it is still unclear whether the changing degrees of muscle mass and strength not only in antigravity muscles but also in non-antigravity muscles differ between males and females. So, the purpose of this study is to investigate gender difference in the effect of 20 days of BR (BR 20) on regional muscle mass and strength of the arm and leg.