Agropyron repens - allelopathy?

Following the work of Becholtz and Bandeen, a series of glasshouse experiments was made to examine the effects of root-zone interference between Agropyron repens and wheat. In a solution-culture experiment the reduction in growth of wheat due to the presence of A. repens could be largely corrected by increasing the nutrient supply in the solution. In similar studies but using soils, the depression of growth of wheat could not be corrected. Foliage applications of nitrogen to wheat plants grown with A. repens had no effect. Using a split-pot technique it was found that the part of the root system of wheat growing in the same medium as the rhizomes and roots of A. repens was very severely suppressed. These results will be discussed.     

A Mass Spectrometric Study for Comparative Analysis and Evaluation of Metabolite Recovery from Plasma by Various Solvent Systems

A solvent system that extracts a maximum number of metabolites belonging to diverse chemical classes from complex biofluids, such as plasma, may offer useful inputs to understand the metabolic and physiological state of an individual. The present study compared seven solvent systems for extraction of metabolites from plasma. The extracts were analyzed by mass spectrometry (MS) and MS/MS (MS2) using a quadrupole time-of-flight liquid chromatography/MS system in positive and negative modes of ionization. Metabolites with molecular mass below 400 were identified using Human Metabolome Database MS2 and MS search interfaces. The acetone/isopropanol (2:1) system yielded promising results in positive ionization mode, as the maximum number of MS and MS2 features was detected in the extract. It was found to be superior in extraction of various classes of metabolites, especially organic acids, nucleosides and nucleoside derivatives, and heterocyclic molecules. Glycerophosphocholines in the mass range of 400–700 were found to be efficiently extracted by the methanol/chloroform/water (8:1:1) system. In negative mode as well, the maximum number of MS2 features was detected in methanol/chloroform/water and acetone/isopropanol extracts. The fingerprints of molecular features obtained in the negative and positive modes differed from each other to a significant extent.     

Regulation of hepatic glucocorticoid receptors in mice during dietary restriction.

The specific binding of [3H] dexamethasone to its receptor, activation of the hormone-receptor complexes and DNase I digestion of nuclear bound hormone-receptor complexes were studied in the liver of mice during dietary restriction (alternate days of feeding for 3 months) compared to animals fed ad libitum. Results indicate an increase of receptor level (fmol/mg protein) in the diet-restricted (DR) animals as compared to those fed ad libitum (AL). Scatchard analyses confirm the increase in the level of receptors in DR animals, while the affinity (Kd) remained same in both groups of mice. Protein slot-blot analysis also depicts the increase of the receptor level in DR fed compared to the AL fed animals. The extent of temperature- and salt-dependent activation of receptors showed no marked difference in AL- and DR-fed mice. DNase I extraction of bound hormone-receptor complexes from nuclei revealed similar pattern of digestion in both groups of animals.     

Pitstop 2 Is a Potent Inhibitor of Clathrin-Independent Endocytosis

Clathrin independent endocytosis (CIE) is a form of endocytosis present in all cells that mediates the entry of nutrients, macromolecules and membrane proteins into cells. When compared to clathrin-dependent endocytosis (CDE), however, much less is known about the machinery involved in forming CIE endosomes. One way to distinguish CIE from CDE has been to deplete cells of coat proteins involved in CDE such as clathrin or the dynamin GTPase, leading to a block of CDE but not CIE. A drawback of such genetic manipulations is that depletion of proteins important for mediating CDE over a period of days can have complex indirect effects on cellular function. The identification of chemical compounds that specifically and rapidly block CDE or CIE would facilitate the determination of whether a process involved CDE or CIE. To date, all of those compounds have targeted CDE. Dynasore and the dynoles specifically target and block dynamin activity thus inhibiting CDE but not most forms of CIE. Recently, a new compound called pitstop 2 was identified as an inhibitor of the interaction of amphiphysin with the amino terminal domain of clathrin, and shown to inhibit CDE in cells. Here we show that pitstop 2 is also a potent inhibitor of CIE. The effects of pitstop 2 are not restricted to inhibition of clathrin since knockdown of clathrin fails to rescue the inhibition of endocytosis of CIE proteins by the drug. Thus pitstop 2 has additional cellular targets besides the amino terminal domain of clathrin and thus cannot be used to distinguish CIE from CDE.     

Comparative Genomic Analysis Reveals a Possible Novel Non-Tuberculous Mycobacterium Species with High Pathogenic Potential

Mycobacteria have been reported to cause a wide range of human diseases. We present the first whole-genome study of a Non-Tuberculous Mycobacterium, Mycobacterium sp. UM_CSW (referred to hereafter as UM_CSW), isolated from a patient diagnosed with bronchiectasis. Our data suggest that this clinical isolate is likely a novel mycobacterial species, supported by clear evidence from molecular phylogenetic, comparative genomic, ANI and AAI analyses. UM_CSW is closely related to the Mycobacterium avium complex. While it has characteristic features of an environmental bacterium, it also shows a high pathogenic potential with the presence of a wide variety of putative genes related to bacterial virulence and shares very similar pathogenomic profiles with the known pathogenic mycobacterial species. Thus, we conclude that this possible novel Mycobacterium species should be tightly monitored for its possible causative role in human infections.