Use of cell cultures in vitro to assess the uptake of long dsRNA in plant cells

In Vitro Cellular & Developmental Biology - Plant - While RNAi approaches based on transgenic plants overexpressing double-stranded RNAs (dsRNAs) have yielded a number of genetically modified...     

Lateral hydrological connectivity differentially affects the community characteristics of multiple groups of aquatic invertebrates in tropical wetland pans in South Africa

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Livestock disturbances in Mediterranean temporary ponds: A mesocosm experiment with sheep manure and simulated trampling

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Defining the risks of mesenchymal stromal cell therapy

We address the issue of the potential for malignant transformation of cultured mesenchymal stromal cells (MSC) commonly used in clinical cell-therapy protocols and describe the culture conditions under which tumorigenesis is likely to be an extremely uncommon event.     

Expanded bed adsorption as a unique unit operation for the isolation of bacteriocins from fermentation media

Expanded bed adsorption using a strong cation exchanger allowed the direct isolation of amylovorin L471, a bacteriocin from Lactobacillus amylovorusDCE 471, from the fermentation medium. The pH of the loading and elution buffer were optimised in a packed bed with cell-free culture supernatant. Bound bacteriocin was eluted with 1.0 M NaCl. The highest recovery (30%) was obtained at the lowest pH (3.6). At higher pH values the recovery was lower, namely 12%, 15% and 7% at pH 4.5, 6.5 and 8.0, respectively. In expanded bed mode, direct isolation of the bacteriocin from the fermentation medium at pH 3.6 (loading and elution) initially resulted in a recovery of 12%. After optimisation of the pH (loading and elution at pH 3.6 and 6.5, respectively), the recovery for amylovorin L471 increased up to 30% and higher. Recovery of enterocin A from Enterococcus faeciumCTC 492 fermentation medium averaged 15% (loading and elution at pH 3.6 and 6.0, respectively). With pediocin, produced by Pediococcus acidilactici ATCC 8042, 26% recovery was obtained at a pH of 6.5 during loading and elution. Low recoveries can be ascribed to non-optimal operation conditions (pH of loading and elution buffer), inactivation of the bacteriocin on a cationic resin, and the formation of more insoluble and less active, strongly hydrophobic bacteriocin aggregates upon further purification.     

Inhibition of Na+-K+-2Cl- cotransport by mercury

Mercury alters thefunction of proteins by reacting with cysteinyl sulfhydryl(SH) groups. Theinorganic form (Hg²⁺) is toxicto epithelial tissues and interacts with various transport proteinsincluding the Na⁺ pump andCl channels. In this study,we determined whether theNa⁺-K⁺-Clcotransporter type 1 (NKCC1), a major ion pathway in secretory tissues,is also affected by mercurial substrates. To characterize theinteraction, we measured the effect ofHg²⁺ on ion transport by thesecretory shark and human cotransporters expressed in HEK-293 cells.Our studies show that Hg²⁺inhibitsNa⁺-K⁺-Clcotransport, with inhibitor constant(K_i) values of25 µM for the shark carrier (sNKCC1) and 43 µM for thehuman carrier. In further studies, we took advantage of speciesdifferences in Hg²⁺ affinity toidentify residues involved in the interaction. An analysis ofhuman-shark chimeras and of an sNKCC1 mutant(Cys-697Leu) reveals that transmembrane domain 11 plays an essential role in Hg²⁺binding. We also show that modification of additionalSH groups by thiol-reactingcompounds brings about inhibition and that the binding sites are notexposed on the extracellular face of the membrane.

     

Reexamination of hemocytes in brine shrimp (Crustacea, branchiopoda)

In 1941, a single type of hemocyte was described in the blood of the brine shrimp Artemia salina using light microscopy. This condition is unusual because most crustaceans examined using morphological, cytochemical, and functional methods have at least two types of hemoctyes. Upon examining A. franciscana, we found a single type of disk-shaped hemocyte, with a centrally located nucleus and about 15 large (6 microm diameter) granules. The granules stain for the presence of acid phosphatase and react with L-DOPA suggesting, respectively, that they are involved in degrading ingested material and possess the phenoloxidase system. Hemocytes require calcium for adhesion, bind together to mend small wounds in the body wall, and are able to phagocytose bacteria. Blood cells of A. franciscana are morphologically and functionally similar to those of the primitive chelicerate, Limulus polyphemus, and both forms have apparently given rise to more advanced taxa with multiple types of hemocytes. The major difference between the two species is the presence of the phenoloxidase system in the Crustacea and its apparent absence in the chelicerates.     

La 12′-hydroxyisostrychnobiline: Nouvel alcaloïde du Strychnos variabilis

The structure of a new bisindole alkaloid, 12′-hydroxyisostrychnobiline, has been proposed from the analysis of its 300 MHz ¹H NMR spectrum and comparison of the spectroscopic data with those of various monomeric and dimeric alkaloids, previously isolated from the same Strychnos species