Biological differences reflect host preference in two parasitoids attacking the bark beetle Ips typographus (Coleoptera: Scolytidae) in Belgium

The basic reproductive biology of two ectoparasitoids developing on the late larval instars of the scolytid Ips typographus Linnaeus, a pest of spruce forests in Eurasia, was studied with the purpose of explaining which biological features allow the two species to share the same host. The anautogenous braconid Coeloides bostrichorum Giraud had a longer pre-oviposition period (5.1 vs. 3.3 days), a greater egg load (8.1 vs. 6.1 eggs), survived longer and emerged later than the pteromalid Rhopalicus tutela (Walker). In contrast, R. tutela was autogenous and tended to be more fecund under constrained conditions (9.7 vs. 5.1 total offspring per female). The longer pre-oviposition period of the specialist C. bostrichorum, coupled with its greater longevity, afforded the opportunity of better synchronization of ovipositing females with late instar larvae of I. typographus. By contrast, the polyphagous R. tutela matured rapidly, allowing parasitism of both younger and older larval instars of I. typographus in addition to other species. These small differences favoured the co-occurrence of the two parasitoid species on the same attacked trees.     

Dynamic energy budget theory restores coherence in biology

We present the state of the art of the development of dynamic energy budget theory, and its expected developments in the near future within the molecular, physiological and ecological domains. The degree of formalization in the set-up of the theory, with its roots in chemistry, physics, thermodynamics, evolution and the consistent application of Occam's razor, is discussed. We place the various contributions in the theme issue within this theoretical setting, and sketch the scope of actual and potential applications.     

Tropomyosin and caldesmon regulate cytokinesis speed and membrane stability during cell division

The contractile ring and the cell cortex generate force to divide the cell while maintaining symmetrical shape. This requires temporal and spatial regulation of the actin cytoskeleton at these areas. We force-expressed misregulated versions of actin-binding proteins, tropomyosin and caldesmon, into cells and analyzed their effects on cell division. Cells expressing proteins that increase actomyosin ATPase, such as human tropomyosin chimera (hTM5/3), significantly speed up division, whereas cells expressing proteins that inhibit actomyosin, such as caldesmon mutants defective in Ca(2+)/calmodulin binding (CaD39-AB) and in cdk1 phosphorylation sites (CaD39-6F), divide slowly. hTM5 and hTM5/3-expressing cells lift one daughter cell off the substrate and twist. Furthermore, CaD39-AB- and CaD39-6F-expressing cells are sensitive to hypotonic swelling and show severe blebbing during division, whereas hTM5/3-expressing cells are resistant to hypotonic swelling and produce membrane bulges. These results support a model where Ca(2+)/calmodulin and cdk1 dynamically control caldesmon inhibition of tropomyosin-activated actomyosin to regulate division speed and to suppress membrane blebs.     

Abnormal liver function associated with occupational exposure to dimethylformamide and glutathione S-transferase polymorphisms.

Dimethylformaide (DMF) is a major solvent predominately used in synthetic leather and resin production. Many human and animal studies have linked the cause of hepatoxicity to DMF. Previously, the authors demonstrated the significant dose-response relationship between abnormal liver function tests and DMF exposure and the interaction with hepatitis B virus (HBV) infection in Taiwanese workers. Because the toxic effect of various chemicals can be modified by metabolic traits, the study also investigated the influence of the glutathione S-transferases (GSTM1 and GSTT1) on the toxic effect of DMF. The average DMF exposure concentration was 23.87 ppm (range 5.2-86.6 ppm) in the high-exposure (>/=5 ppm) group and 2.41 ppm (range 0.9-4.3 ppm) in the low-exposure (<5 ppm) group. There were 13 of 44 (29.6%) abnormal liver function tests (elevations of either glutamate oxaloacetate transaminase (GOT) or glutamate pyruvate transaminase (GPT)) among the high DMF exposure workers, two of 22 (9.1%) abnormal liver function tests among the low DMF exposure workers. Chronic liver disease as determined by ultrasonography was present in seven of 44 (15.9%) high DMF exposure workers, and 0 of 22 (0%) low DMF exposure workers. There were 11 of 34 (32.4%) abnormal liver function tests among the GSTT1 null genotype workers, and four of 32 (12.5%) abnormal liver function tests among the GSTT1-positive genotype workers. Compared with the low DMF exposure workers, the adjusted odds ratio and 95% confidence intervals for abnormal liver function tests was 6.78 (0.94-48.7) for the high DMF exposure workers. Compared with the GSTT1-positive genotype workers, the adjusted odds ratio and 95% confidence intervals for abnormal liver function tests was 4.41 (1.15-16.9) for the GSTT1 null genotype workers. Compared with the low DMF group with GSTT1-positive genotype workers, the odds ratio (adjusted for HBV status) of abnormal liver function test was 12.38, 95% CI=(1.04-146.9) for the high DMF group with GSTT1 null genotype workers. This study indicates that abnormal liver function and chronic liver disease are associated with DMF exposure, and there are more than multiplicative interaction effects on abnormal liver function tests between the DMF exposure and the GSTT1 genotype.     

On the Structure and Reactivity of Y-Nucleoside [Wyosine]

Abstract

Wyosine-Triacetate 4 has found to undergo electrophilic reactions exclusively at the C-7 position. ¹⁵N-NMR of 4, shows that the primary site of protonation is N-5 suggesting that the “right” imidazole ring is more aromatic that the “left” imidazole moiety.     

Sulfonated phenylene-isothiocyanate-polyaerylamide as support for solid-phase sequencing of proteins

A hydrophylic isothiocyanate resin has been synthesized starting from a commercial polyacrylic acid. Lysine-containing proteins easily react with this support in aqueous media, yielding an insoluble derivative able to be sequenced by conventional methods.     

Novel endomorphin-2 analogs with mu-opioid receptor antagonist activity.

A series of position 4-substituted endomorphin-2 (Tyr-Pro-Phe-Phe-NH2) analogs containing 3-(1-naphthyl)-alanine (1-Nal) or 3-(2-naphthyl)-alanine (2-Nal) in L- or D-configuration, was synthesized. The opioid activity profiles of these peptides were determined in the mu-opioid receptor representative binding assay and in the Guinea-Pig Ileum assay/Mouse Vas Deferens assay (GPI/MVD) bioassays in vitro, as well as in the mouse hot-plate test of analgesia in vivo. In the binding assay the affinity of all new analogs for the mu-opioid receptor was reduced compared with endomorphin-2. The two most potent analogs were [D-1-Nal(4)]- and [D-2-Nal4]endomorphin-2, with IC50 values 14 +/- 1.25 and 19 +/- 2.1 nM, respectively, compared with 1.9 +/- 0.21 nM for endomorphin-2. In the GPI assay these analogs were found to be weak antagonists and they were inactive in the MVD assay. The in vitro GPI assay results were in agreement with those obtained in the in vivo hot-plate test. Antinociception induced by endomorphin-2 was reversed by concomitant intracerebroventricula (i.c.v.) administration of [D-1-Nal4]- and [D-2-Nal4]-endomorphin-2, indicating that these analogs were mu-opioid antagonists. Their antagonist activity was compared with that of naloxone. At a dose 5 microg per animal naloxone almost completely inhibited antinociceptive action of endomorphin-2, while [D-1-Nal4]endomorphin-2 in about 46%.     

An international parentage and identification panel for the domestic cat (Felis catus)

Seventeen commercial and research laboratories participated in two comparison tests under the auspices of the International Society for Animal Genetics to develop an internationally tested, microsatellite-based parentage and identification panel for the domestic cat (Felis catus). Genetic marker selection was based on the polymorphism information content and allele ranges from seven random-bred populations (n = 261) from the USA, Europe and Brazil and eight breeds (n = 200) from the USA. Nineteen microsatellite markers were included in the comparison test and genotyped across the samples. Based on robustness and efficiency, nine autosomal microsatellite markers were ultimately selected as a single multiplex 'core' panel for cat identification and parentage testing. Most markers contained dinucleotide repeats. In addition to the autosomal markers, the panel included two gender-specific markers, amelogenin and zinc-finger XY, which produced genotypes for both the X and Y chromosomes. This international cat parentage and identification panel has a power of exclusion comparable to panels used in other species, ranging from 90.08% to 99.79% across breeds and 99.47% to 99.87% in random-bred cat populations.     

Cholinergic differentiation factor (CDF/LIF) promotes survival of isolated rat embryonic motoneurons in vitro.

We present evidence that the cholinergic differentiation factor (CDF), originally purified from cardiac and skeletal muscle cell-conditioned medium and found to be identical to leukemia inhibitory factor (LIF), promotes survival of embryonic day 14 rat motoneurons in vitro. These neurons were retrogradely labeled with the fluorescent tracer Dil and enriched on a density gradient or purified to homogeneity by fluorescence-activated cell sorting. Subnanomolar concentrations of CDF/LIF supported the survival of 85% of the motoneurons that would have died between days 1 and 4 of culture. The enhanced survival was accompanied by a 4-fold increase in choline acetyltransferase (ChAT) activity per culture. CDF/LIF also increased ChAT activity in dorsal spinal cord cultures, but had no detectable effect on ChAT levels in septal or striatal neuronal cultures. For comparison, other neurotrophic molecules were tested on motoneuron cultures. Ciliary neurotrophic factor had effects on motoneuron survival similar to those of CDF/LIF, whereas basic fibroblast growth factor was somewhat less effective. Nerve growth factor had no effect on the survival of rat motoneurons.     

SLP-2 interacts with prohibitins in the mitochondrial inner membrane and contributes to their stability

Stomatin is a member of a large family of proteins including prohibitins, HflK/C, flotillins, mechanoreceptors and plant defense proteins, that are thought to play a role in protein turnover. Using different proteomic approaches, we and others have identified SLP-2, a member of the stomatin gene family, as a component of the mitochondria. In this study, we show that SLP-2 is strongly associated with the mitochondrial inner membrane and that it interacts with prohibitins. Depleting HeLa cells of SLP-2 lead to increased proteolysis of prohibitins and of subunits of the respiratory chain complexes I and IV. Further supporting the role of SLP-2 in regulating the stability of specific mitochondrial proteins, we found that SLP-2 is up-regulated under conditions of mitochondrial stress leading to increased protein turnover. These data indicate that SLP-2 plays a role in regulating the stability of mitochondrial proteins including prohibitins and subunits of respiratory chain complexes.