Comparison of cold enrichment and U.S. Department of Agriculture methods for isolating Listeria monocytogenes from naturally contaminated foods. The Listeria Study Group.

We compared the cold enrichment (CE) and U.S. Department of Agriculture (USDA) methods for isolating Listeria monocytogenes by examining 402 food samples. The food samples were collected from refrigerators of listeriosis patients as part of a multistate active surveillance project to determine the role of foods in sporadic listeriosis in the United States. L. monocytogenes was isolated from 51 food samples (13%). The USDA method was significantly better (P less than 0.001) than the CE method. The isolation efficiencies of the USDA and CE methods were 96 and 59%, respectively. Quantitation of L. monocytogenes in the food samples revealed that many food samples containing less than 0.3 CFU/g were negative as determined by the CE method but positive as determined by the USDA method.     

Antiovulatory antagonists of LHRH related to antide

We report 104 analogues of the potent antiovulatory antagonist of LHRH, N-Ac-D -Nal-D -Cpa-D -Pal-Ser-Lys(Nic)-D -Lys(Nic)-Leu-Ilys-Pro-D -Ala-NH₂, Antide. We replaced the Nic group in Antide with other acyl substituents to modulate size, hydrophilicity or basicity of the molecule, we also replaced th Lys residues with shorter basic amino acids, and made cyclic 5/6 analogues as well as position 5 or 6 dimers. We substituted Ilys⁸ with other alkyl groups and acyl derivatives. When injected in 0.1% DMSO in water in a typical antiovulatory (AO) assay, Antide gives six rats ovulating out of eight (6/8) at 2 μg, 4/8 at 4 μg, and the histamine release assay (HRA), ED₅₀ is >300 μg/ml; [Lys(N-Isobutyl)⁸]Antide gave 2/8 at 2 μg/rat; [Lys (8-Qis)⁵]Antide gave 1/8 at 1 μg, and 0/8 at 2 μg, and in the HRA ED₅₀, 22 μg/ml; [D -Lys(8-Qis)⁶]Antide gave 4/8 at 1 μg and 0/8 at 2 μg, and in the HRA, ED₅₀ was 27 μg/ml; [Lys(8-Qic)⁸] gave 5/8 at 1 μg, 1/8 at 2 μg/ [Lys(2-Pyc)⁵]Antide gave 5/8 at 1 μg and 0/8 at 2 μg, and in the HRA ED₅₀ was 116 μg/ml; [D -Lys (2-Pyc)⁶]Antide gave 3/8 at 1 μg, and in the HRA, ED₅₀ was 100 - >300 μg/ml; [Lys(2-Pyc)⁵,D -Lys(2-Pyc)⁶]Antide gave 2/8 at 1 μg. The substitutions of the Nic groups of Antide at Lys⁵ or D -Lys⁶ with 8-Qis or with 2-Pyc groups seem to give highly potent antiovulatory antagonists of LHRH and constitute significant new leads to generate potent antiovulatory compounds endowed with moderate or low histamine release.     

Identification of salt-responsive genes from C4 halophyte Suaeda nudiflora through suppression subtractive hybridization and expression analysis under individual and combined treatment of salt and elevated carbon dioxide conditions

Physiology and Molecular Biology of Plants - Salinization of soil is a prime abiotic stress that limits agriculture productivity worldwide. To Study the mechanisms that halophytes take up to...     

Inhibition of catalytic activities of botulinum neurotoxin light chains of serotypes A,B and E by acetate,sulfate and calcium

The catalytic domain, known as light chain (Lc), of the most poisonous botulinum neurotoxins (BoNTs), possesses endoprotease activity that triggers the ultimate poisonous effect to animals and humans. X-ray crystallographic structure of Lc of several BoNT serotypes has identified at least four small ligands at or near the respective active sites. They are sulfate ions in LcA, LcB, and LcE; an acetate ion in LcA; a calcium ion in LcB; and a potassium ion in LcD. Roles of these ligands on the structure and function of the proteins are not known. We have investigated the roles of sulfate, acetate, and calcium on the catalytic activities of LcA, LcB, and LcE using 17-35-residue synthetic peptide substrates. All three ligands inhibited all Lc activities. For LcA and LcB, the order of inhibition effectiveness was calcium>sulfate>acetate. The inhibition effectiveness expressed as IC₅₀, did not correlate with the occurrence or proximity of the ions to the active site. Moreover, addition of acetate or sulfate to LcA did not affect the near-UV circular dichroism spectra, tryptophan, and tyrosine fluorescence spectra, and mid points of thermal denaturation of LcA. Our results suggest that acetate, sulfate, and calcium nonspecifically interact with BoNT Lc, and their occurrence in the crystal structures could have been due to opportunistic binding to complementary pockets.