Cloning, expression and function of phosphate transporter encoded gene in Oryza sativa L.

OsPT6:1, a phosphate transporter encoding gene from the leaf samples of Oryza sativa, was identified through PCR with specifically designed primers. The phylogenetic analysis and the conserved amino acid residue site detection suggested OsPT6:1 a possible high-affinity phosphate transporter encoding gene. In situ hybridization and RT-PCR demonstrated the expression of OsPT6:1 in both roots and leaves. The peak expression signal was observed in mesophyll cells under low phosphorus (P) induction. A homologous recombination study indicated that OsPT6:1 can enhance the Pi uptake efficiency of Pichia pastoris. At the meantime, the introduction of OsPT6:1 was able to complement the Pi uptake function of yeast cells with high-affinity phosphate transporters deficient. Those results substantiated our contention that OsPT6:1 encoded a high-affinity phosphate transporter of Oryza sativa. These authors contributed equally to this work.     

Cloning and characterization of a novel splicing isoform of the iron-superoxide dismutase gene in rice (Oryza sativa L.)

Superoxide dismutases (SODs) are ubiquitous metalloenzymes in aerobic organisms that play a crucial role in protecting organisms against ROS. Here, we report the molecular cloning and functional characterization of a novel alternatively spliced variant of the iron-superoxide dismutase gene, OsFe-SODb, from a rice panicle cDNA library. The alternative splicing event occurred in the fourth exon of the OsFe-SOD gene, and led to the translation of two isoforms of different sizes. The 5′ flanking region of the OsFe-SOD was cloned and many cis-acting regulatory elements were found that are involved in light responsiveness, including a G-box and an I-box. RT-PCR analysis showed that the two alternative forms of OsFe-SOD were expressed in both the vegetative and reproductive tissues of Cpslo17. Moreover, accumulation of both isoforms was upregulated by light induction. In addition, the alternative splicing of OsFe-SOD mRNA was sensitive to low temperature. High yield production of the two recombinant OsFe-SOD isoforms was achieved in Escherichia coli. SOD assays showed that C-terminal truncation in OsFe-SODb did not result in a loss of SOD enzyme activity.     

Stage-specific expression of dynein light chain-1 and its interacting kinase, p21-activated kinase-1, in rodent testes: implications in spermiogenesis.

Mammalian spermatogenesis is a complex process involving regulatory interactions of many gene products. In this study, we found that dynein light chain-1 (DLC1), a component of the dynein motor complex, is highly expressed in mouse and rat testes. Immunohistochemically detectable levels of DLC1 are observed specifically in spermatids in steps 9-16 in distinct subcellular compartments: in steps 9-11, DLC1 is predominantly localized in the nucleus; in steps 12 and 13, it is found in both nucleus and cytoplasm; and in step 14-16, it is present exclusively in the cytoplasm. In addition, we found p21-activated kinase 1 (Pak1), a protein kinase that activates DLC1 by phosphorylating DLC1 at Serine 88, was also expressed during these stages of spermatogenesis. Pak1 was also expressed in Leydig cells, in preleptotene primary spermatocytes, and in round spermatids. The spermiogenic stage-specific expression of DLC1 suggests a role for DLC1 in chromatin condensation, spermatid shaping, and the final release of sperm from the spermatogenic epithelium. Further, Pak1 may also play a role in spermiogenesis by regulating DLC1 phosphorylation and, consequently, its function.     

Comparison of bacterial diversity along the human intestinal tract by direct cloning and sequencing of 16S rRNA genes

Bacterial diversity of the mucosal biopsies from human jejunum, distal ileum, ascending colon and rectum were compared by analysis of PCR-amplified 16S rDNA clone libraries. A total of 347 clones from the mucosal biopsies were partially sequenced and assigned to six phylogenetic phyla of the domain Bacteria: Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria, Verrucomicrobia, and Actinobacteria. The jejunum sample had least microbial diversity compared to the other samples and a trend towards highest diversity in ascending colon was observed. The clone libraries of distal ileum, ascending colon and rectum were not significantly different from each other (P>0.0043), but they differed significantly from the jejunum library (P=0.001). The population of sequences retrieved from jejunal biopsies was dominated by sequences closely related to Streptococcus (67%), while the population of sequences derived from distal ileum, ascending colon and rectum were dominated by sequences affiliated with Bacteroidetes (27-49%), and Clostridium clusters XIVa (20-34%) and IV (7-13%). The results indicate that the microbial community in jejunum is different from those in distal ileum, ascending colon and rectum, and that the major phylogenetic groups are similar from distal ileum to rectum.     

Cobalt-substituted horseradish peroxidase.

Horseradish peroxidase can be reconstituted with cobalt porphyrin to give a cobaltic holoenzyme having physicochemical properties quite similar to those of the native ferric protein. The cobaltic protein (Co3+HRP) can be reduced to the cobaltous form (CoHRP), the analogue of ferroperoxidase and the reduced cobalt protein can bind O2 to form an analogue of oxyferroperoxidase (Compound III). Since both the CoHRP and oxy-CoHRP are EPR-visible, the cobalt has been used to probe the nature of the heme crevice in these two protein forms. The occurrence of a three-line 14N superhyperfine pattern in the spectrum of the former unambiguously shows that in the divalent state of the protein the proximal axial ligand is a nitrogenous base. The spectrum of the latter shows a uniquely large Aparallel(59Co) = 23.2 G. Although we confirm the reported failure of the Co3+HRP to catalyze peroxide-dependent oxidations of classical peroxidase substrates (Gjessing, E.C., and Sumner, J.B. (1942) Arch. Biochem. 1, 1), the oxy-CoHRP does undergo oxidation-reduction reactions analogous to those exhibited in the cytochrome P-450 catalytic cycle.     

Exploring the stereochemistry of CXCR4-peptide recognition and inhibiting HIV-1 entry with D-peptides derived from chemokines

Chemokine receptor CXCR4 plays an important role in the immune system and the cellular entry of human immunodeficiency virus type 1 (HIV-1). To probe the stereospecificity of the CXCR4-ligand interface, d-amino acid peptides derived from natural chemokines, viral macrophage inflammatory protein II (vMIP-II) and stromal cell-derived factor-1alpha (SDF-1alpha), were synthesized and found to compete with (125)I-SDF-1alpha and monoclonal antibody 12G5 binding to CXCR4 with potency and selectivity comparable with or higher than their l-peptide counterparts. This was surprising because of the profoundly different side chain topologies between d- and l-enantiomers, which circular dichroism spectroscopy showed adopt mirror image conformations. Further direct binding experiments using d-peptide labeled with fluorescein (designated as FAM-DV1) demonstrated that d- and l-peptides shared similar or at least overlapping binding site(s) on the CXCR4 receptor. Structure-activity analyses of related peptide analogs of mixed chiralities or containing alanine replacements revealed specific residues at the N-terminal half of the peptides as key binding determinants. Acting as CXCR4 antagonists and with much higher biological stability than l-counterparts, the d-peptides showed significant activity in inhibiting the replication of CXCR4-dependent HIV-1 strains. These results show the remarkable stereochemical flexibility of the CXCR4-peptide interface. Further studies to understand the mechanism of this unusual feature of the CXCR4 binding surface might aid the development of novel CXCR4-binding molecules like the d-peptides that have high affinity and stability.     

Simultaneous determination of the carboxylate and lactone forms of 10-hydroxycamptothecin in human serum by restricted-access media high-performance liquid chromatography

A simple restricted-access media (RAM) HPLC method for simultaneous determination of the lactone and carboxylate forms of 10-hydroxycamptothecin (HCPT) in human serum was established. Using a RAM Hisep analytical column, serum samples were directly injected into the HPLC system. The eluted peaks of two forms of HCPT were monitored with a fluorescence detector. The separation was completed in 17 min. The linear range was 20-1000 ng/ml, intra-day and inter-day variations being less than 5%. The kinetic equation was introduced according to the analytical results. The equation shows that the course of the HCPT lactone form converting to carboxylate form in human serum at 4 degrees C is a first-order kinetic course. The concentration of each form at the moment of sampling was calculated by extrapolation.     

Delayed minocycline but not delayed mild hypothermia protects against embolic stroke

Background  

Inflammatory reactions occurring in the brain after ischemia may contribute to secondary damage. In the present study, effects of minocycline, an anti-inflammatory agent, alone or in combination with mild hypothermia on focal embolic cerebral ischemia have been examined.