A web server to locate periodicities in a sequence

Summary : FT is a tool written in C++, which implements the Fourier analysis method to locate periodicities in aminoacid or DNA sequences. It is provided for free public use on a WWW server with a Java interface. Availability : The server address is http://o2.db. uoa.gr/FT Contact : shamodr@atlas.uoa.gr      

Factors Affecting Engorgement Behavior in the Salt Marsh Horse Fly, <Emphasis Type="Italic">Tabanus nigrovittatus</Emphasis> Macquart (Diptera: Tabanidae)

Female Tabanus nigrovittatus were field collected and used in laboratory experimentation to explore physiological and behavioral factors that affect engorgement. Previous studies showed sulfakinins act as feeding satiety factors in insects. This study demonstrates that sulfakinins have differing effects on engorgement that is dependent on the feeding technique used in the laboratory. The satiety effect of sulfakinin on flies engorging using the blood-soaked Kimwipe® feeding technique is not in agreement with previous experiments using an alternate feeding technique with artificial membranes. This study is the first to demonstrate that the temperature of blood is a significant factor for engorgement in this species. Also, the percentage of flies engorging is significantly different depending on the feeding technique used.     

The elastin-binding protein of Staphylococcus aureus (EbpS) is expressed at the cell surface as an integral membrane protein and not as a cell wall-associated protein.

The elastin-binding proteins EbpS of Staphylococcus aureus strains Cowan and 8325-4 were predicted from sequence analysis to comprise 486 residues. Specific antibodies were raised against an N-terminal domain (residues 1-267) and a C-terminal domain (residues 343-486) expressed as recombinant proteins in Escherichia coli. Western blotting of lysates of wild-type 8325-4 and Newman and the corresponding ebpS mutants showed that EbpS migrated with an apparent molecular mass of 83 kDa. The protein was found exclusively in cytoplasmic membrane fractions purified from protoplasts or lysed cells, in contrast to the clumping factor ClfA, which was cell-wall-associated. EbpS was predicted to have three hydrophobic domains H1-(205-224), H2-(265-280), and H3-(315-342). A series of hybrid proteins was formed between EbpS at the N terminus and either alkaline phosphatase or beta-galactosidase at the C terminus (EbpS-PhoA, EbpS-LacZ). PhoA and LacZ were fused to EbpS between hydrophobic domains H1-H2 and H2-H3, and distal to H3. Expression of enzymatic activity in E. coli showed that EbpS is an integral membrane protein with two membrane-spanning domains H1 and H3. N-terminal residues 1-205 and C-terminal residues 343-486 were predicted to be exposed on the outer face of the cytoplasmic membrane. The ligand-binding domain of EbpS is known from previous studies to be present in the N terminus between residues 14-34 and probing whole cells with anti-EbpS1-267 antibodies indicated that this region is exposed on the surface of intact cells. This was also confirmed by the observation that wild-type S. aureus Newman cells bound labeled tropoelastin whereas the ebpS mutant bound 72% less. In contrast, the C terminus, which carries a putative LysM peptidoglycan-binding domain, is not exposed on the surface of intact cells and presumably remains buried within the peptidoglycan. Finally, expression of EbpS was correlated with the ability of cells to grow to a higher density in liquid culture, suggesting that EbpS may have a role in regulating cell growth.     

Perturbation of phospholipid membranes by juvenile hormone

The effects of juvenile hormone and its analogs Altozar 4E and ZR-777 5E on the phase properties of liposomes prepared from dipalmitoyl phosphatidyl-choline (DPPC) have been examined by differential scanning calorimetry. Each of these compounds reduced the co-operativity of the gel to liquid-crystalline phase transition, which is manifest as a distinct broadening of the main transition endotherm, and split the transition into two distinguishable components centered at 34 and 37°C. However, there was no significant change in enthalpy of the main phase transition, suggesting that juvenile hormone and its analogs perturb the bilayer primarily in the vicinity of the phospholipid headgroups. Moreover, this perturbation does not appear to influence bilayer permeability since the osmotic swelling rates of liposomes prepared from either phosphatidylcholine or dipalmitoyl phosphatidylcholine that contained up to 33 mol% juvenile hormone were not significantly different from the swelling rates of corresponding liposomes containing no juvenile hormone. Splitting of the transition endotherm into two peaks appeared to be peculiar to compounds possessing juvenile hormone activity. A mixture of fatty acid methyl esters broadened the main transition of DPPC, but did not split the endotherm or shift the transition midpoint, and the insect hormone ecdysone had no discernible effect on the DPPC transition apart from eliminating the pretransition. The data indicate that juvenile hormone and its analogs can modulate the physical properties of phospholipid bilayers, and raise the prospect that some of the physiological effects of this hormone may be achieved through its influence on the molecular organization of membrane lipid.     

The influence of sex and spawning on levels of tryptophan, serotonin and 5-hydroxyindoleacetic acid in the brains of wild brook trout, Salvelinus fontinalis

Levels of tryptophan (TP), serotonin (5-hydroxytryptamine, 5HT) and 5-hydroxyindoleacetic acid (5HIAA) have been determined in the brains of wild brook trout, Salvelinus fontinalis (Mitchill), and brown trout, Salmo trutta L., using high performance liquid chromatography with electrochemical detection. Immediately prior to spawning, adult female brook trout exhibit higher levels of 5HT in the brain than adult males, immature brook trout and immature brown trout. After spawning, the highest levels of TP are found in spent males, which also have higher levels of 5HT in the brain than spent females and immature brook trout. Immature brook trout exhibit higher levels of 5HIAA than prespawning adults. This difference disappears after the spawning season. Serum protein levels and condition factors are lower in spent female brook trout; however, haematocrit values for both sexes remain unchanged after spawning.     

Amiloride does not alter NaCl avoidance in Fischer-344 rats

Fischer-344 (F-344) rats differ from other common rat strains in that they fail to show any preference for NaCl at any concentration in two- bottle preference tests. Because 100 microM amiloride partially blocks the NaCl-evoked chorda tympani (CT) response in electrophysiological studies, we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without 100 microM amiloride solution as the solvent. A third group was tested with unadulterated NaCl solutions following CT transection. Amiloride had no significant effect on the NaCl preference-aversion function, whereas CT transection significantly reduced NaCl avoidance. These results suggest that the amiloride-sensitive component of the NaCl response is not necessary for F-344 rats to display avoidance of NaCl, but the entire CT input is.