Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and leptin on hypothalamic mRNA expression of factors participating in food intake regulation in a TCDD-sensitive and a TCDD-resistant rat strain

An acutely toxic dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) leads to a drastically and permanently reduced feed intake and wasting by an unknown mechanism. We focused on the possible interference of TCDD with hypothalamic factors known to take part in the regulation of eating and metabolism, utilizing the over 1000-fold TCDD-sensitivity difference between Long-Evans (Turku/AB; L-E) and Han/Wistar (Kuopio) rats. The mRNA expression of 18 hypothalamic factors (including NPY, AgRP, and CART) was measured by quantitative RT-PCR at 6, 24 and 96 h after TCDD administration. The effects of TCDD were compared with those of leptin and with feed restriction employing a TCDD dose that elicited a severe reduction of feed intake in L-E rats. TCDD mainly modified expression of orexigenic factors causing an initial suppression followed by reversal to enhanced expression by 96 h. The latter was also seen in feed-restricted controls. In contrast, leptin altered both orexigenic and anorexigenic factor mRNAs in a more even manner and its effects were clustered at 6 h. The transient nature of feeding-promoting factor suppression does not strongly support a key role for this phenomenon in TCDD-induced wasting syndrome. However, the fact that TCDD mainly affected orexigenic factors and the temporal differences in response found between the rat strains warrant further research.     

Biological effects of Trichoderma harzianum peptaibols on mammalian cells

Trichoderma species isolated from water-damaged buildings were screened for toxicity by using boar sperm cells as indicator cells. The crude methanolic cell extract from Trichoderma harzianum strain ES39 inhibited the boar sperm cell motility at a low exposure concentration (50% effective concentration, 1 to 5 microg [dry weight] ml of extended boar semen(-1)). The same exposure concentration depleted the boar sperm cells of NADH(2). Inspection of the exposed boar sperm cells by transmission electron microscopy revealed damage to the plasma membrane. By using the black lipid membrane technique, it was shown that the semipurified metabolites (eluted from a SepPak C(18) cartridge) of T. harzianum strain ES39 induced voltage-dependent conductivity. The high-performance liquid chromatography-purified metabolites of T. harzianum strain ES39 dissipated the mitochondrial membrane potential (Deltapsi(m)) of human lung epithelial carcinoma cells (cell line A549). The semipurified metabolites (eluted from a SepPak C(18) cartridge) of T. harzianum strain ES39 were analyzed by mass spectrometry (MS). Matrix-assisted laser desorption ionization and nanoflow electrospray ionization MS revealed five major peptaibols, each of which contained 18 residues and had a mass ranging from 1,719 to 1,775 Da. Their partial amino acid sequences were determined by collision-induced dissociation tandem MS.     

Division of Labor during Biofilm Matrix Production

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The archaeal elongation factor 1alpha bound to GTP forms a ternary complex with eubacterial and eukaryal aminoacyl-tRNA.

The archaeal Sulfolobus solfataricus elongation factor 1alpha (SsEF-1alpha) bound to GTP or to its analogue guanyl-5'-yl imido diphosphate [Gpp(NH)p] formed a ternary complex with either Escherichia coli Val-tRNAVal or Saccharomyces cerevisiae Phe-tRNAPhe as demonstrated by gel-shift and gel-filtration experiments. Evidence of such an interaction also came from the observation that SsEF-1alphaz.rad;Gpp(NH)p was able to display a protective effect against either the spontaneous deacylation or the digestion of aminoacyl-tRNA by RNase A. Protection against the deacylation of aminoacyl-tRNA allowed evaluatation of the affinity of SsEF-1alphaz. rad;Gpp(NH)p for both aminoacyl-tRNAs used. The K'd values of the ternary complex containing S. cerevisiae Phe-tRNAPhe or E. coli Val-tRNAVal were 0.3 microM and 4.4 microM, respectively. In both cases, the affinity of SsEF-1alphaz.rad;Gpp(NH)p for aminoacyl-tRNA was three orders of magnitude lower than that of the homologous eubacterial ternary complexes, but comparable with the affinity shown by the ternary complex involving eukaryal EF-1alpha [Negrutskii, B.S. & El'skaya, A.V. (1998) Prog. Nucleic Acids Res. 60, 47-77]. As already observed with eukaryal EF-1alpha, SsEF-1alpha in its GDP-bound form was also able to protect the ester bond of aminoacyl-tRNA, even though with a 10-fold lower efficiency compared with SsEF-1alphaz.rad;Gpp(NH)p. The overall results indicated that the archaeal elongation factor 1alpha shares several properties with eukaryal EF-1alpha but not with eubacterial EF-Tu.     

A feasibility study of altered spatial distribution of losses induced by eddy currents in body composition analysis

Background  

Tomographic imaging has revealed that the body mass index does not give a reliable state of overall fitness. However, high measurement costs make the tomographic imaging unsuitable for large scale studies or repeated individual use. This paper reports an experimental investigation of a new electromagnetic method and its feasibility for assessing body composition. The method is called body electrical loss analysis (BELA).     

Central boreal mire plant communities along soil nutrient potential and water content gradients

Peatlands have traditionally been exploited in forestry and agriculture over the boreal region, yet they also provide substantial source of fuel production. The large-scale exploitation of peatlands has raised a concern about the diversity of mire plant communities. We studied composition of mire plant communities along soil nutrient potential and water content gradients, to recognize the areas with the high plant diversity. Soil electrical conductivity (EC_b) was measured to characterise soil nutrient regimes and soil dielectric permittivity (DP) the soil (volumetric) water regimes. A total of 115 mire sites were studied in the central boreal region of south-western Finnish Lapland. We found that Ward’s hierarchical cluster analysis produced eight stable EC_b and DP clusters with discrete vegetation compositions. On the basis of a locally weighted regression analysis (Loess), Carex dioica L., Comarum palustre L., Equisetum fluviatile L., Menyanthes trifoliata L., and Scorpidium scorpioides (Hedw.) Limpr. were found as indicator species for nutrient-rich regimes as designated by high soil EC_b. The soil EC_b is a diagnostic measure of plant diversity as EC_b?>?7 mSm^?1 resulted in a considerable increase in species richness. Our classification method, based on electrical measurements, provides a simple way to classify mires and focus detailed research to areas with potentially high conservation value.     

A rationally designed synthetic mimic of the discontinuous CD4-binding site of HIV-1 gp120

Synthetic mimetics of the CD4-binding site of HIV-1 gp120 are promising candidates for HIV-1 entry inhibition, as well as immunogen candidates for the elicitation of virus-neutralizing antibodies. On the basis of the crystal structure of gp120 in complex with CD4, we have used a recently introduced strategy for the generation of structurally diverse scaffolds to design and synthesize a scaffolded peptide, in which three fragments, making up the sequentially discontinuous binding site of gp120 for CD4, are presented in a nonlinear and discontinuous fashion through a molecular scoffold, which restrains conformational flexibility. The affinities of this molecule to CD4, as well as to the broadly neutralizing antibody mAb b12, whose epitope overlaps the CD4-binding site of gp120, were determined in competitive binding assays.