Increased cold allodynia following intrathecal N-methyl-D-aspartate in rats with a mononeuropathy

NMDA receptors are involved in the modulation of neuropathic pain behavior and central sensitization. In vivo, this is mostly demonstrated by the use of specific antagonists such as MK801. Because studies evaluating the direct impact of spinal NMDA in neuropathic pain models are lacking, we performed a series of experiments to study the role of spinal NMDA injection on existing cold allodynia, as a measurement of neuropathic pain behavior in rodents. Intrathecal injection of NMDA resulted in an enhanced neuropathic pain behavior in CCI rats on a cold plate. The activity was present from a dose of 5 ng/rat onward and could selectively be reversed by intraperitoneal injections of doses of > or = 0.01 mg/kg MK801. These results support the regulatory role of NMDA receptors in the hypersensitivity to cold observed in neuropathic pain behavior in rodents.     

Tol-dependent macromolecule import through the Escherichia coli cell envelope requires the presence of an exposed TolA binding motif

The Tol-Pal proteins of the cell envelope of Escherichia coli are required for maintaining outer membrane integrity. This system forms protein complexes in which TolA plays a central role by providing a bridge between the inner and outer membranes via its interaction with the Pal lipoprotein. The Tol proteins are parasitized by filamentous bacteriophages and group A colicins. The N-terminal domain of the Ff phage g3p protein and the translocation domains of colicins interact directly with TolA during the processes of import through the cell envelope. Recently, a four-amino-acid sequence in Pal has been shown to be involved in Pal's interaction with TolA. A similar motif is also present in the sequence of two TolA partners, g3p and colicin A. Here, a mutational study was conducted to define the function of these motifs in the binding activity and import process of TolA. The various domains were produced and exported to the bacterial periplasm, and their cellular effects were analyzed. Cells producing the g3p domain were tolerant to colicins and filamentous phages and had destabilized outer membranes, while g3p deleted of three residues in the motif was affected in TolA binding and had no effect on cell integrity or colicin or phage import. A conserved Tyr residue in the colicin A translocation domain was involved in TolA binding and colicin A import. Furthermore, in vivo and in vitro coprecipitation analyses demonstrated that colicin A and g3p N-terminal domains compete for binding to TolA.     

Comparative study of metabolism and forms of transport of phosphate between Ascophyllum nodosum and Polysiphonia lanosa

Polysiphonia lanosa (L.) Tandy is a marine red alga that usually grows epiphytically on the fucale Ascophyllum nodosum (L.) Le Jolis. The present work was conducted in order to obtain more information on the relationships between these two algae, especially as regards the metabolism and long-distance transport of phosphorus. Three types of experiments were carried out using labelled phosphorus. (1) Comparative study of the metabolism of ³²P₁ absorbed by the tissues of each species. By means of two-dimensional chromatography and autoradiography, it was shown that ³²P₁ was rapidly incorporated into organic soluble compounds (adenosine triphosphate, hexose monophosphate, uridine diphosphoglucose, phosphoenolpyruvate + phosphoglyceric acid). Although the two algae belong to different phylae the phosphorylated compounds were not very different. The energy charges (0. 72 for both species) were in the usual range for aerobic plant tissues. On the other hand the incorporation of ³²P₁ into the insoluble P₀ fraction was doubled in P. lanosa compared to in A. nodosum (ca 80 and 40%, respectively). At the source level, the air bladder of A. nodosum. the same soluble compounds (inorganic phosphate, P₁ adenosine triphosphate, hexose monophosphate. etc.) represented the likely forms transported. A part of the soluble P₀ fraction may return to the P₁ fraction. (2) In translocation experiments conducted in situ, ³²P₁ locally injected into an air bladder moved over long distances not only through the thallus of A. nodosum but also into P. lanosa. The reciprocal transfer remained unsuccessful. (3) The ³²P₁ represented the predominant compound identified in the two species: this argues in favour of P₁ as the translocated form of phosphorus. Our results support the hypothesis of a parasitic rather than a simple epiphytic relationship between the two algae.     

Localization of translocation breakpoints in somatic metaphase chromosomes of barley

Karyotype analyses based on staining by acetocarmine followed by Giemsa N-banding of somatic metaphase chromosomes of Hordeum vulgare L. were carried out on 61 reciprocal translocations induced by X-irradiation. By means of computer-based karyotype analyses all of the 122 breakpoints could be localized to defined sites or segments distributed over the seven barley chromosomes. The pre-definition of translocations with respect to their rearranged chromosome arms from other studies rendered it possible to define the break positions even in translocations having exchanged segments equal in size and the breakpoints located distally to any Giemsa band or other cytological marker. The breakpoints were found to be non-randomly spaced along the chromosomes and their arms. All breaks but one occurred in interband regions of the chromosomes, and none of the breaks was located directly within a centromere. However, short and long chromosome arms recombined at random. An improved tester set of translocations depicting the known break positions of most distal location is presented.     

First report of intersex in a lutjanid: the goldband snapper Pristipomoides multidens

This is the first report of intersex in a lutjanid species, the goldband snapper Pristipomoides multidens, in which the gonads of a male fish contain multifocal oocytes scattered among testicular tissue. The incidence rate of intersex was low (<1.0%), with oocytes observed in the testes of only two of 206 male fish examined. The capacity for P. multidens to develop an intersex condition suggests that future monitoring of this species should include histological analysis of gonads.     

Ab initio study of polar and non-polar aprotic solvents effects on some 3-hydroxychromones and 3-hydroxyquinolones derivatives

The photophysical properties of some 3-hydroxychromones (3-HC) and 3-hydroxyquinolones (3-HQ) derivatives are investigated in polar and non-polar aprotic solvents using the TDDFT method and the PCM formalism. In acetonitrile and n-hexane, 2–(2-benzothienyl)-3-HC) (BTHC), 2-furyl-3-HQ (FHQ), and 1-methyl-2-furyl-3-HQ (MFHQ) have exhibited dual emission bands due to the excited state intramolecular proton transfer (ESIPT) reaction, leading to a single excited tautomer form. Our results indicate a very high BTHC light absorption efficiency and radiative rate constant. A charge transfer (CT) analysis suggests that the chromone moiety acts as an acceptor group while quinolone moiety acts as an electron donor. In addition, in non-polar n-hexane the furyl group may act as an acceptor, while in polar acetonitrile it may act as an electron donor. The energies of the upper and lower states of the normal form fluorescence have been decreased by the introduction of ortho-methyl group in FHQ. In all states, MFHQ exhibits large distortions of the dihedral angle between the chromone moiety and the furan group in para position. The ESIPT reaction is irreversible for the three derivatives in all cases studied in this work. Since experimental data with n-hexane are not available, results concerning this solvent are only predictions.     

Cyclic diguanylate regulation of Bacillus cereus group biofilm formation

Biofilm formation can be considered a bacterial virulence mechanism. In a range of Gram‐negatives, increased levels of the second messenger cyclic diguanylate (c‐di‐GMP) promotes biofilm formation and reduces motility. Other bacterial processes known to be regulated by c‐di‐GMP include cell division, differentiation and virulence. Among Gram‐positive bacteria, where the function of c‐di‐GMP signalling is less well characterized, c‐di‐GMP was reported to regulate swarming motility in Bacillus subtilis while having very limited or no effect on biofilm formation. In contrast, we show that in the Bacillus cereus group c‐di‐GMP signalling is linked to biofilm formation, and to several other phenotypes important to the lifestyle of these bacteria. The Bacillus thuringiensis 407 genome encodes eleven predicted proteins containing domains (GGDEF/EAL) related to c‐di‐GMP synthesis or breakdown, ten of which are conserved through the majority of clades of the B. cereus group, including Bacillus anthracis. Several of the genes were shown to affect biofilm formation, motility, enterotoxin synthesis and/or sporulation. Among these, cdgF appeared to encode a master diguanylate cyclase essential for biofilm formation in an oxygenated environment. Only two cdg genes (cdgA, cdgJ) had orthologs in B. subtilis, highlighting differences in c‐di‐GMP signalling between B. subtilis and B. cereus group bacteria.