Adrenic acid Δ4 desaturation and fatty acid composition in the liver of marine-oil fed streptozotocin diabetic rats

The aim of the present study was to assess the effect of streptozotocin diabetes and insulin treatment on adrenic acid Δ4 desaturation and fatty acid composition of liver microsomes in Wistar rats fed a fat free semi-synthetic basal diet supplemented with 10% EPA-rich marine oil. Results showed that, in liver microsomes of hyperglycemic rats, the ratio in total lipids was elevated and desaturation of adrenic acid to n-6 docosapentaenoic acid was enhanced. Insulin treatment with 2.0 I.U./100 g body weight⁻¹ twice a day for 3 days resulted in hypoglycemia and suppressed both the increased Δ4 n-6 desaturation and ratio. It is concluded that the Δ4 desaturation enzyme system, which is activated by experimental diabetes, is regulated by mechanisms different from those regulating Δ6 and Δ5 desaturations.     

Modulation of rabbit articular chondrocyte (RAC) proliferation by TGF-β isoforms

We have previously shown that TGF-β1 exerts a bifunctional effect on RAC proliferation. Added to quiescent cultures, it inhibits the entry of G₀/G₁ cells into S phase whereas in S phase synchronized populations, it stimulates the DNA replication rate with a delayed G₂+ M phase and a subsequent transient increase of cell number. As TGF-β2 and β3 isoforms are also expressed in bone and cartilage tissues, it was of interest to study their effect on RAC proliferation, in comparison to that of TGF-β1. Using cell counting and tritiated thymidine incorporation, we found that all the TGF-βs used here induced an increase of RAC proliferation rate occurring between 24 and 48 h of exposure. TGF-β2 appeared as the most efficient form as judged from the maximum of thymidine labelling. However, TGF-β3 induced an increase of cell number slightly higher than both TGF-β1 and TGF-β2 (+30% versus 20% for TGF-β1 and β2). TGF-β2 and β3 were able to stimulate the DNA replication rate as previously demonstrated for TGF-β1. However, the effect occurred later for TGF-β2 and β3 (12 h) than for TGF-β1 (6 h). This was confirmed by flow cytometric analysis of DNA content. In addition, immunodetection by flow cytometry demonstrated that all TGF-β isoforms enhanced endogenous expression of TGF-β-related peptides. The effect was shown to be associated with the cell cycle S phase and was greater for TGF-β3 than for TGF-β1 and β2. These findings suggest that TGF-βs could act on RAC functions via autocrine and paracrine ways. Taken together, these data indicate that TGF-βs may modulate proliferation of articular chondrocytes and therefore could play a role in the activation of these cells in the early stages of osteoarthritis.     

Methane production and substrate degradation by rumen microbial communities containing single protozoal species in vitro

AIMS: To assess the effect of protozoal species on rumen fermentation characteristics in vitro. METHODS AND RESULTS: Entodinium caudatum, Isotricha intestinalis, Metadinium medium, and Eudiplodinium maggii from monofaunated wethers and mixed protozoa from conventional wethers were obtained by centrifugation, re-suspended at their normal densities in rumen fluid supernatants from defaunated or conventional wethers and incubated in vitro. The presence of protozoa increased the concentration of ammonia and altered the volatile fatty acids balance with more acetate and butyrate produced at the expense of propionate. Differences among species were observed, notably in the production of methane, which increased with E. caudatum as compared to other ciliates and to defaunated and mixed protozoa treatments (P < 0.05). The increased methanogenesis was not correlated to protozoal biomass indicating that the metabolism of this protozoan and/or its influence on the microbial ecosystem was responsible for this effect. CONCLUSIONS: Entodinium caudatum stimulated the production of methane, a negative effect that was reinforced by a concomitant increase in protein degradation. SIGNIFICANCE AND IMPACT OF THE STUDY: Comparison of individual species of protozoa highlighted the particular influence of E. caudatum on rumen fermentation. Its elimination (targeted defaunation) from the rumen could reduce methane production without affecting feed degradation.     

Genetic diversity of Schistosoma mansoni within and among individual hosts (Rattus rattus): infrapopulation differentiation at microspatial scale.

The distribution of genetic diversity in a local population of the trematode Schistosoma mansoni was determined within and between individual wild rats at a microspatial geographic scale of a standing water transmission site. Using RAPD markers, molecular variance and canonical correspondence analysis were performed to test the significance of genetic differentiation between infrapopulations. Of total gene diversity, 8 and 11% was partitioned between hosts trapped at few metres distance from each other. Significant temporal differentiation (2%) was also detected among schistosomes sampled at 6 month intervals with more infrapopulation pairs differentiated during the dry season of parasite transmission than during the rainy season (45 and 12%, respectively). A combination of factors such as restricted displacement of rats, patchy spatial aggregation of infected snails and limited cercarial dispersion in standing water are likely to promote the genetic differentiation observed between infrapopulations at this microgeographic scale.     

Genetic control of experience-dependent plasticity in the visual cortex

Depriving one eye of visual experience during a sensitive period of development results in a shift in ocular dominance (OD) in the primary visual cortex (V1). To assess the heritability of this form of cortical plasticity and identify the responsible gene loci, we studied the influence of monocular deprivation on OD in a large number of recombinant inbred mouse strains derived from mixed C57BL/6J and DBA/2J backgrounds (BXD). The strength of imaged intrinsic signal responses in V1 to visual stimuli was strongly heritable as were various elements of OD plasticity. This has important implications for the use of mice of mixed genetic backgrounds for studying OD plasticity. C57BL/6J showed the most significant shift in OD, while some BXD strains did not show any shift at all. Interestingly, the increase in undeprived ipsilateral eye responses was not correlated to the decrease in deprived contralateral eye responses, suggesting that the size of these components of OD plasticity are not genetically controlled by only a single mechanism. We identified a quantitative trait locus regulating the change in response to the deprived eye. The locus encompasses 13 genes, two of which--Stch and Nrip1--contain missense polymorphisms. The expression levels of Stch and to a lesser extent Nrip1 in whole brain correlate with the trait identifying them as novel candidate plasticity genes.     

Orally active microtubule-targeting agent,MPT0B271, for the treatment of human non-small cell lung cancer,alone and in combination with erlotinib

Microtubule-binding agents, such as taxanes and vinca alkaloids, are used in the treatment of cancer. The limitations of these treatments, such as resistance to therapy and the need for intravenous administration, have encouraged the development of new agents. MPT0B271 (N-[1-(4-Methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-1-oxy-isonicotinamide), an orally active microtubule-targeting agent, is a completely synthetic compound that possesses potent anticancer effects in vitro and in vivo. Tubulin polymerization assay and immunofluorescence experiment showed that MPT0B271 caused depolymerization of tubulin at both molecular and cellular levels. MPT0B271 reduced cell growth and viability at nanomolar concentrations in numerous cancer cell lines, including a multidrug-resistant cancer cell line NCI/ADR-RES. Further studies indicated that MPT0B271 is not a substrate of P-glycoprotein (P-gp), as determined by flow cytometric analysis of rhodamine-123 (Rh-123) dye efflux and the calcein acetoxymethyl ester (calcein AM) assay. MPT0B271 also caused G2/M cell-cycle arrest, accompanied by the up-regulation of cyclin B1, p-Thr161 Cdc2/p34, serine/threonine kinases polo-like kinase 1, aurora kinase A and B and the downregulation of Cdc25C and p-Tyr15 Cdc2/p34 protein levels. The appearance of MPM2 and the nuclear translocation of cyclin B1 denoted M phase arrest in MPT0B271-treated cells. Moreover, MPT0B271 induced cell apoptosis in a concentration-dependent manner; it also reduced the expression of Bcl-2, Bcl-xL, and Mcl-1 and increased the cleavage of caspase-3 and -7 and poly (ADP-ribose) polymerase (PARP). Finally, this study demonstrated that MPT0B271 in combination with erlotinib significantly inhibits the growth of the human non-small cell lung cancer A549 cells as compared with erlotinib treatment alone, both in vitro and in vivo. These findings identify MPT0B271 as a promising new tubulin-binding compound for the treatment of various cancers.     

Substrate Mode-Integrated SPR Sensor

We present the design, implementation and characterisation of an integrated surface plasmon resonance (SPR) biosensor chip involving diffractive optical coupling elements avoiding the need of prism coupling. The integrated sensor chip uses the angular interrogation principle and includes two diffraction gratings and the SPR sensing zone. The theoretical design is presented as well as the fabrication process. Experimental results (response of a reference water droplet and phosphate-buffered saline/water kinetic) are presented and compared with those obtained with the classical Kretschmann prism coupling setup. We believe that this prism-free architecture is perfectly suitable for low-cost and reproducible SPR biochemical sensor chips since the sensing zone can be functionalised as any other one.     

Hybridization of reef fishes at the Indo-Pacific biogeographic barrier: a case study

Hybridization is recognized as an important source of genetic variation. In some reef fishes, including the Acanthuridae, hybridization has been detected due to intermediate colouration. This study used a molecular genetic approach to investigate hybridization in two Acanthurid species: Acanthurus leucosternon and Acanthurus nigricans, which have Indian and Pacific Ocean distributions respectively and are sympatric in the eastern Indian Ocean. In this area a putatitve hybrid, Acanthurus cf. leucosternon has been recognized based on intermediate colouration and restriction to the sympatric region of otherwise allopatric putative parental species. This study aimed to test this hypothesis using genetic tools. The three species were sampled from Cocos (Keeling) and Christmas Islands, the biogeographic boundary where many Indian and Pacific Ocean biota meet. Representatives from allopatric populations of both parental species and outgroups were also sampled. Mitochondrial COI and intron 1 of the nuclear ribosomal protein S7 were sequenced from 13 and 30 specimens respectively. Although sample sizes in this study are relatively small and more genetic data, including an extended phylogeographic sampling, is required to further evaluate these findings, the COI results support hybrid origins of Acanthurus cf. leucosternon, but S7 data are inconclusive due to the possibility of incomplete lineage sorting. The fourfold more abundant Acanthurus nigricans is most often the maternal parent. Inter-fertile hybrids apparently backcross with rare Acanthurus leucosternon males, transferring Acanthurus nigricans mitochondria to this species. These results suggest that Acanthurus leucosternon may eventually be lost from these islands, due to their relative rarity and introgressive hybridization.     

Functions and expression of liver N-CAM

In conclusion we have shown that: (a) liver N-CAM is a functionally active adhesion molecule, (b) its expression during the morphogenetic processes occurring during Xenopus laevis metamorphosis correlates with morphological changes in the cell-to-cell interaction; (c) Thyroxine is not directely involved in the activation of the expression of liver N-CAM.