Programmed synthesis of collagen during postembryonic development of the nematode Panagrellus silusiae.

The relative rate of collagen synthesis in the free-living nematode Panagrellus silusiae during postembryonic development was found to be discontinuous by measuring either the incorporation of tritium into material extracted as collagen or the amount of collagen-bound tritiated proline and hydroxyproline after 2-hr incubations of whole worms with [³H]proline. A peak of collagen production preceded each of the three molts that were examined. Moreover, protocollagen prolyl hydroxylase activity during each intermolt period paralleled the pattern of collagen synthesis. On the other hand, a triphasic pattern was not observed when noncollagenous proteins were labeled with either [³H]tryptophan or [³H]leucine. In addition, the level of soluble radioactive proline that accumulates in whole organisms after 2-hr incubation periods did not fluctuate appreciably during postembryonic development. The mean ratio of hydroxy-proline to proline in a number of collagen samples extracted at various times during the maturation phase was 0.113 ± 0.040. Pulse and chase experiments with [³H]proline indicated that most of the collagen synthesized during a peak period is lost after the second ecdysis following the labeling interval. In contrast, a considerable proportion of the collagen synthesized during nonpeak periods is retained throughout the postembryonic period. It is postulated that the modulated pattern of collagen biosynthesis in Panagrellus reflects, for the most part, a quantitative regulation of the production of cuticular collagen during postembryonic development.     

Stabilization of the μ-Opioid Receptor by Truncated Single Transmembrane Splice Variants through a Chaperone-like Action

The μ-opioid receptor gene, OPRM1, undergoes extensive alternative pre-mRNA splicing, as illustrated by the identification of an array of splice variants generated by both 5′ and 3′ alternative splicing. The current study reports the identification of another set of splice variants conserved across species that are generated through exon skipping or insertion that encodes proteins containing only a single transmembrane (TM) domain. Using a Tet-Off system, we demonstrated that the truncated single TM variants can dimerize with the full-length 7-TM μ-opioid receptor (MOR-1) in the endoplasmic reticulum, leading to increased expression of MOR-1 at the protein level by a chaperone-like function that minimizes endoplasmic reticulum-associated degradation. In vivo antisense studies suggested that the single TM variants play an important role in morphine analgesia, presumably through modulation of receptor expression levels. Our studies suggest the functional roles of truncated receptors in other G protein-coupled receptor families.     

ISDra2 transposition in Deinococcus radiodurans is downregulated by TnpB

Transposable elements belonging to the recently identified IS200/IS605 family radically differ from classical insertion sequences in their transposition mechanism by strictly requiring single‐stranded DNA substrates. This IS family includes elements encoding only the transposase (TnpA), and others, like ISDra2 from Deinococcus radiodurans, which contain a second gene, tnpB, dispensable for transposition and of unknown function to date. Here, we show that TnpB has an inhibitory effect on the excision and insertion steps of ISDra2 transposition. This inhibitory action of TnpB was maintained when ISDra2 transposition was induced by γ‐irradiation of the host cells and required the integrity of its putative zinc finger motif. We also demonstrate the negative role of TnpB when ISDra2 transposition was monitored in a heterologous Escherichia coli host, indicating that TnpB‐mediated inhibition does not involve Deinococcus‐specific factors. TnpB therefore appears to play a regulatory role in ISDra2 transposition.     

Synthesis, structure elucidation, determination of the lipophilicity and identification of antitumour activities in vitro of novel 3-(2-furanyl)-8-aryl-7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones with a low cytotoxicity towards normal human skin fibroblast cells

Eleven novel 3-(2-furanyl)-8-aryl-7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-ones (12-22) were designed and obtained from appropriate 1-aryl-2-hydrazonoimidazolidines (1-11) by condensation reaction with 2-oxo-2-furanacetic acid and subsequent cyclocondensation of intermediate chain derivatives. IR, (1)H NMR and (13)C NMR spectra and elemental analyses confirmed the chemical structure of all the synthesized compounds. The reversed-phase HPLC method was optimized and proved to be applicable and reliable for the analysis of these unknown small molecules (12-22). These compounds were chromatographed on octadecyl silica (ODS) stationary phase and their hydrophobic parameters expressed as the log k(w) values were determined by RP-HPLC, using mixtures of methanol and water as mobile phases with different methanol concentrations. Octane-1-sulfonic acid sodium salt (OSA-Na) and 20% acetate buffer (pH 3.5) was added to the mobile phase (eluent containing 0.01 M/L OSA-Na in organic modifier (MeOH)-buffered mobile phase). The high values of regression coefficients (r >0.9841) for all the compounds investigated proved the excellent fit between experimental data and the Snyder-Soczewiński equation. Results obtained from the reversed-phase HPLC were compared both with those theoretically calculated and with those obtained from an ALOGPS 2.1. software by the use of nine different computational methods for estimation of log P. The predicted values of log P by use of AB log P algorithm revealed the best correlation with the experimental log k(w) values for the investigated solutes, since a good correlation (r=0.7760) between these quantities was found. The majority of novel imidazotriazinones were found to be evidently effective in vitro against human cancerous cells (HeLa and T47D) in an effective concentration of 50 μg/mL. Five compounds (13, 15, 16, 18 and 22) revealed remarkable antiproliferative activities and selective cytotoxicities for cancer cells over normal HSF cells. Therefore these ones may be considered as a basis for the design of novel useful non-toxic (13, 15 and 16) and low toxic (18 and 22) anticancer agents.     

Host location by larvae of a parasitic barnacle: larval chemotaxis and plume tracking in flow

Numerous studies describe stimulation and/or enhancement oflarval settlement by distance chemoreception in response tochemical factors emitted by conspecific adults, host and preyspecies and microbial films. However, active upstream trackingof odor plumes, needed in order to locate specific, spatiallylimited settlement sites, has thus far received little scientificattention. This study examines host location in flow and stillwater by larvae of the parasitic barnacle Heterosaccus dollfusi,which inhabits the brachyuran crab Charybdis longicollis. Experimentsincluded analysis of larval motion patterns under four conditions:still water, in flow, in still water with waterborne host metabolitesand in flow with host metabolites. Our results show that H.dollfusi larvae are capable of actively and effectively locatingtheir host in still water and in flow, using chemotaxis andrheotaxis and modifying their swimming pattern, direction, velocity,determination and turning rate to accommodate efficient navigationin changing environmental conditions.     

Contestable shelters provoke aggression among 0+ perch, <Emphasis Type="BoldItalic">Perca fluviatilis</Emphasis>

Synopsis We examined behavioural interactions and feeding within triads of young-of-the-year (YOY) Eurasian perch, Perca fluviatilis, in aquaria with and without a shelter. For the first time we showed that competition for shelters, but not for food, provokes aggressiveness and triggers establishment of social hierarchy among young perch. No aggressiveness occurred during feeding bouts, when food was a limited resource. We expect the observed interactions to occur in natural heterogeneous habitats providing limited number of refuges and high local density of fish. They may ultimately lead to previously anticipated interference competition among juvenile perch.