Chemotaxis ofRhizobium sp. Towards root exudate ofCicer Arietinum L.

Summary Root exudate from seedlings ofCicer arietinum L. was collected in a chamber under aseptic conditions. The exudate was fractionated into anion, cation and neutral fractions. The anionic fraction was made up of galacturonic acid, gluconic acid, mannuronic acid and two unidentified compounds withR _f values 0.56 and 0.62. The cationic fraction contained alanine, arginine, aspartic acid, cystine, glycine, histidine, isoleucine, leucine, lysine and serine. The neutral fraction was made up of arabinose, galactose, glucose, ribose and xylose. The amino acids contributed to the bulk of the root exudate. The ratio of anionic, cationic and neutral fraction was 1∶7∶2. The crude root exudate was tested for its chemotactic ability using the capillary tube method. It was highly chemotactic for theRhizobium sp. The individual fractions and their various combinations were tested for chemotaxis. The chemotactic response of the Cicer strain of Rhizobium was least with anionic fraction most with cationic fraction and intermediate with neutral fraction. Maximum chemotactic response among the fractional combinations was obtained with all the three fractions and least with cationic plus neutral factions. Individual compounds constituting the various fractions were also tried for their ability to elicit chemotactic response. The organism exhibited maximum positive chemotactic response to histidine and negative response to alanine among the amino acids and to glucose and gluconic acid among the sugars and sugar acids.     

Identification of novel dysregulated circular RNAs in early-stage breast cancer

Breast cancer is a major cause of cancer-related death in women worldwide. Non-coding RNAs are a potential resource to be used as an early diagnostic biomarker for breast cancer. Circular RNAs are a recently identified group of non-coding RNA with a significant role in disease development with potential utility in diagnosis/prognosis in cancer. In this study, we identified 26 differentially expressed circular RNAs associated with early-stage breast cancer. RNA sequencing and two circRNA detection tools (find_circ and DCC) were used to understand the circRNA expression signature in breast cancer. We identified hsa_circ_0006743 (circJMJD1C) and hsa_circ_0002496 (circAPPBP1) to be significantly up-regulated in early-stage breast cancer tissues. Co-expression analysis identified four pairs of circRNA-miRNA (hsa_circ_0023990 : hsa-miR-548b-3p, hsa_circ_0016601 : hsa_miR-1246, hsa_circ_0001946 : hsa-miR-1299 and hsa_circ_0000117:hsa-miR-502-5p) having potential interaction. The miRNA target prediction and network analysis revealed mRNA possibly regulated by circRNAs. We have thus identified circRNAs of diagnostic implications in breast cancer and also observed circRNA-miRNA interaction which could be involved in breast cancer development.     

Structure of the manganese complex in photosystem II: insights from X-ray spectroscopy

We have used Mn K-edge absorption and Kbeta emission spectroscopy to determine the oxidation states of the Mn complex in the various S states. We have started exploring the new technique of resonant inelastic X-ray scattering spectroscopy; this technique can be characterized as a Raman process that uses K-edge energies (1s to 4p, ca. 6550 eV) to obtain L-edge-like spectra (2p to 3d, ca. 650 eV). The relevance of these data to the oxidation states and structure of the Mn complex is presented. We have obtained extended X-ray absorption fine structure data from the S(0) and S(3) states and observed heterogeneity in the Mn-Mn distances leading us to conclude that there may be three rather than two di-mu-oxo-bridged units present per tetranuclear Mn cluster. In addition, we have obtained data using Ca and Sr X-ray spectroscopy that provide evidence for a heteronuclear Mn-Ca cluster. The possibility of three di-mu-oxo-bridged Mn-Mn moieties and the proximity of Ca is incorporated into developing structural models for the Mn cluster. The involvement of bridging and terminal O ligands of Mn in the mechanism of oxygen evolution is discussed in the context of our X-ray spectroscopy results.     

Androgen receptor expression and DNA content of paraffin-embedded archival human prostate tumors

BACKGROUND: Androgen receptors (AR) are expressed in human prostate cells and immunohistochemistry has been used for qualitative analysis of AR expression in prostate tumor cells. Quantitative and multiparametric analysis of receptor expression could be of diagnostic and prognostic value in the management of patients on antiandrogen therapy. Multiparametric flow cytometric methods have been developed for analysis of hormone receptor expression and DNA content in nuclei isolated from formalin-fixed/paraffin-embedded human solid tumors. The present study was undertaken for analysis of AR expression and DNA content in archival human prostate tumors. METHODS: AR expression and DNA content were measured in nuclei isolated by enzyme digestion from thick sections cut from 51 paraffin-embedded human prostate tumors. AR expression in different subpopulations was studied by gated analysis. The relationship among AR activity, DNA content, and histopathological grade was analyzed. RESULTS: Distinct aneuploid populations were observed in 23% of tumors examined. AR activity was observed in all the specimens and the percentage of AR- positive nuclei in the 48 samples analyzed was <10% (n = 4), 11-50% (n = 39), and >51% (n = 5). Tumor subpopulations with aneuploid DNA content had higher AR expression (percent AR-positive cells and mean log fluorescence) than the diploid subpopulations. No strong correlation was seen between AR expression and histopathological grade of the tumors. CONCLUSIONS: Flow cytometric analysis of archival prostate tumor can be used for rapid determination of aneuploid DNA content and AR expression in subpopulations of nuclei isolated from formalin-fixed/paraffin-embedded prostate tumor blocks.     

A preliminary survey of airborne pollen in Madras City

The atmospheric pollen of Madras city was surveyed during a 1-year period (January–December 1995) with a vertical cylinder trap. A total of 32 pollen types were identified, among which nine were present throughout the year. These belonged to Poaceae,Casuarina equisetifolia Foster and Foster f.,Prosopis juliflora (SW.) DC.,Acalypha indica L.,Parthenium hysterophorus L., Cyperaceae,Cocos nucifera L., Amaranthaceae, andTypha angustata Borry and Chaub. Among the identified pollen, 61.05% belonged to trees, 21.01% to grasses, 11.65% to herbs and 6.27% to shrubs. Anemophilous pollen contributed about 52.87% to the total while entomophilous and amphiphilous pollen contributed 38.89 and 8.22%, respectively. Pollen belonging to Poaceae were found to be most predominant in the air of Madras city followed byCasuarina equisetifolia andProsopis juliflora.     

Syntheses, structures and properties of copper(II) complexes containing N-(2-hydroxybenzyl)-amino amide ligands

Four copper(II) complexes containing the reduced Schiff base ligands, namely, N-(2-hydroxybenzyl)-glycinamide (Hsglym) and N-(2-hydroxybenzyl)-l-alaninamide (Hsalam) have been synthesized and characterized. The crystal structures of [Cu₂(sglym)₂Cl₂] (1), [Cu₂(salam)₂(NO₃)₂] · H₂O (3), [Cu₂(salam)₂(NO₃)(H₂O)](NO₃) · 1.5H₂O (4), [Cu₂(salam)₂](ClO₄)₂ · 2H₂O (5) show that the Cu(II) atoms are bridged by two phenolato oxygen atoms in the dimers. The sglym ligand bonded to Cu(II) in facial manner while salam ligand prefers to bind to Cu(II) in meridonal geometry. Variable temperature magnetic studies of 3 showed it is antiferromagnetic. These Cu(II) complexes and [Cu₂(sglym)₂(NO₃)₂] (2), exhibit very small catecholase activity as compared to the corresponding complexes containing acid functional groups.     

Probing the sterol binding site of soybean sterol methyltransferase by site-directed mutagenesis: functional analysis of conserved aromatic amino acids in Region 1

Soybean sterol methyltransferase (SMT) in the presence of AdoMet catalyzes the transmethylation of the delta24-bond of the sterol side chain to produce phytosterols with a methyl(lene) or ethyl(idene) group at C-24. The function of six aromatic amino acids associated with the putative active center of the SMT, i.e., Region 1 that extends from Phe82 to Phe93 in soybean SMT, was studied by site-directed mutagenesis and heterologous expression in BL21(DE3) bacterial cells. The enzyme-generated products were characterized kinetically and by GC-MS analysis. Substitution of the aromatic amino acids at positions 82, 83, 85, 87, 91, and 93 with a leucine residue produced mutant SMTs with varying activities. The mutants converted cycloartenol to 24(28)-methylene cycloartanol [C1-activity] from a few percent to as much as 95% of the control activity. In contrast, none of the leucine mutants were found to catalyze 24(28)-methylene lophenol [C2-activity], suggesting a loss of function associated with the second C1-transfer activity. In contrast to the loss of the second C1-transfer activity of the Phe82Leu, replacement of the Phe82 residue to isoleucine had minimal effect on the first or second C1-transfer activities, suggesting that the increased bulk (branching) in the leucine side chain contributes to significant perturbations in the active site that generate inaccurate positioning of the substrate side chain disfavoring the second C1-transfer activity. Replacement of Tyr83 to phenylalanine resulted in an increase of the specificity constant (kcat/Km) for the substrate of the second C1-transfer activity by a factor of 5 compared to control and an increase of delta24(28)Z-ethylidene sterol formation in the 24-ethyl sterol product set, suggesting that loss of steric bulk from the phenolic hydroxyl group on tyrosine generates a less precise fit of the delta24(28) sterol side chain into the active site favoring the second C1-transfer activity and prompting reaction channeling during catalysis. Circular dichroism spectra, equilibrium dialysis studies of AdoMet, and chromatographic information of the wild-type and Tyr83 mutants confirmed retention of the overall conformation of the enzyme during the experiments. Together, these findings suggest that the amino acids of Region 1 provide a tight substrate orientation imposed by hydrophobic interactions between the sterol side chain and the SMT active site contacts and control the production and processing of the transmethylation pathways governed by the first and second C1-transfer activities.