The sublethal effects of tebufenozide on the precopulatory and copulatory activities of Choristoneura fumiferana and C. rosaceana

The sublethal effects of tebufenozide, an ecdysone agonist, on the reproductive biology of Choristoneura fumiferana (Clem) and of Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), treated during the larval stage, were evaluated using two treatment methods: the force‐feeding method and the diet method. The percentage of mortality and the developmental time of survivors increased linearly with the concentration of tebufenozide used. This ecdysone analogue proved to be more toxic to C. fumiferana than to C. rosaceana. In C. rosaceana, the weight of males and females decreased proportionally with the dose ingested, but females were affected to a greater extent. This difference might be due to a greater consumption of the treated diet, or to a differential vulnerability to tebufenozide. Tebufenozide did not modify the pre‐copulatory activities associated with chemical communication in the females. However, the consumption of tebufenozide delayed ovarian maturation, causing a reduction in the fecundity of females. Treated males had smaller spermatophores and fewer eupyrene sperms in their bursa copulatrix and spermatheca, along with lower mating success. In C. fumiferana, tebufenozide delayed the females’ onset time of calling the first night after emergence, but did not affect the mean time spent calling or the production of the main component of the sex pheromone. The males showed significantly greater difficulty in executing oriented flight in a wind tunnel, although their mating success was not affected. We concluded that tebufenozide interferes with various aspects of the reproductive biology of males and females of C. fumiferana and C. rosaceana, including some pre‐copulatory behaviors associated with sex pheromone communication.     

In vitro peptidergic neurons from the adult locust pars intercerebralis: Morphological and immunocytological studies

Primary cell cultures were prepared from a major neurosecretory center of the adult locust brain, the pars intercerebralis, in order to characterize neurosecretory cells growingin vitro. Individual pars intercerebralis could be removed free of surrounding tissue and dissociated by mechanical treatment. Mature neurosecretory neurons of different sizes regenerate new neurites during the initial three daysin vitro in serum-free medium. They show a tendency to sprout one primary neurite from which fine processes develop. By means of electron microscopy, we observed the integrity of the cellular organelles, indicating that cultured neurons are healthy, and we were able to distinguish three types of neurosecretory neurons on the basis of the ultrastructural aspects of the neurosecretory material. These three types have the same ultrastructural characteristics asin situ neuroparsin, ovary maturing parsin and locust insulin related peptide neurons. Immunogold labelling at the electron microscopic level, using the two available specific antibodies, anti-neuroparsin and anti-ovary maturing parsin, confirms the morphological characterization of neuroparsin and ovary maturing parsin cells. These results show for the first time that cultured locust neurosecretory neurons behave like thosein vivo, in terms of their ultrastructure and immunocytochemistry. Moreover, the presence of recently-formed neurosecretory material both in the Golgi zone of the perikaryon and in the neuronal processes indicates that cultured neurons have functional capacity since they are able to synthesizede novo and to transport the neurosecretory material along the neurite. Thus our well-characterized culture system provides a suitable invitro model to investigate the secretory mechanism of locust neurosecretory neurons.     

Localization of the ribosomal RNA genes in Drosophila simulans

In situ hybridization of cloned rRNA genes from Drosophila melanogaster to D. simulans metaphase chromosomes shows that in the tested wild type strains both sex chromosomes contain a nucleolus organizer region. Silver grain counts support the published data that the X chromosomal rRNA gene number is significantly higher than the Y chromosomal.     

The mitochondrially encoded "phantom ATPase" of S. cerevisiae. II. A heterogeneous mitochondrial ATPase population in situ.

Summary The mitochondrial ATPase from a PHO 1 mutant (OLI 2, PHO 1, OLI 4 region on mit DNA of S. cerevisiae) was further examined. A new purification method using Lysolecithin instead of Triton allowed us to solubilize and separate a heterogeneous ATPase population from PHO 1-mitochondria: the major abnormal fraction had extremely low oligomycin-sensitivity (but normal specific immunological reactivity), while a minor normal fraction (representing about 20% of the initial mitochondrial ATPase activity) had high sensitivity and affinity for oligomycin.Moderate urea treatment of PHO 1-mitochondria leads to partial loss of ATPase activity and a concomitant increase of oligomycin-sensitivity, suggesting that a heterogeneous ATPase population exists in situ in the mitochondrial membrane: part of the major abnormal ATPase fraction is selectively inactivated by urea, producing a concomitant enrichment in the initially minor normal ATPase fraction.If the minor normal ATPase fraction is the only one capable of in vivo ATP synthesis, the deficient but oligomycin-sensitive cell growth and oxidative phosphorylation in vitro are readily explained.Further structural studies are under way to ascertain whether the minor normal ATPase fraction is strictly identical to the wild type, in which case PHO 1 is a regulatory gene, or not, in which case PHO 1 is a structural gene.     

Involvement of IS1 in the dissociation of the r-determinant and RTF components of the plasmid R100.1

Summary Detailed mapping localized the PHO 1 mutation between the OLI 2 and OLI 4 loci on mitochondrial DNA of Saccharomyces cerevisiae.In its mitochondrially integrated form, the PHO 1-ATPase³ was difficult to identify either immunologically or by specific inhibitors like oligomycin and DCCD. Solubilization by Triton X-100 allowed unambiguuous identification of this enzyme as an authentic mitochondrial ATPase. However, Triton extraction produced a 2 to 3 fold enhancement of the PHO 1-ATPase activity which also became drastically cold-sensitive. The wild type ATPase was neither activated nor made cold-labile by solubilization, and retained full sensitivity to oligomycin and DCCD.Sucrose gradient analysis of the Triton-extracted ATPase from wild type, PHO 1 mutant and rho ^- strains showed a density difference between the solubilized PHO 1-and wild type ATPase, and similarity between solubilized PHO 1-and rho ^- ATPase (F₁).Whole cells of the PHO 1 mutant present considerably increased respiration rates.Comparison of oligomycin-sensitivity in whole cells, coupled isolated mitochondria and membrane-bound ATPase indicates a contrast between oligomycin-resistance of the ATPase and oligomycin-sensitivity of in vivo or in vitro coupling systems, which might characterize the products of this region of mitochondrial DNA.     

NMR characterization of three forms of ferredoxin from Desulphovibrio gigas, a sulphate reducer

A NMR and magnetic susceptibility study of the oxidized and reduced states of three different oligomers (forms) of a [4Fe-4S] ferredoxin protein from Desulphovibrio gigas, FdI, FdI′, and FdII was carried out. FdI and FdI′ are different trimers and FdII a tetramer of the same basic subunit. A probable assignment of the contact shifted resonances is indicated. Since the temperature dependences of the contact shifted resonances associated with each [4Fe-4S] are not all similar a delocalized model for the spin densities on the 4Fe does not apply. The exchange rate between oxidized and reduced states is slow on the NMR time scale. The three oligomers are not magnetically equivalent. Using the “three state hypothesis” terminology it is shown that FdI_ox is predominantly in the C^2? state and changes upon reduction into the C^3? state, while FdII_ox is in the C^? state and changes into the C^2? state. FdI′ does not easily fit into this classification. This study shows a similarity of magnetic behaviour between FdI and bacterial ferredoxins (e.g. Bacillus polymyxa) and between FdII and HiPIP from Chromatium sp.. The influence of the quaternary structure on the stabilization of the different oxidation states of ferredoxins as well as on their redox potentials is discussed.     

Purification,characterization and biological activity of three forms of ferredoxin from the sulfate-reducing bacterium Desulfovibrio gigas

Three forms of ferredoxin FdI, FdI′, and FdII have been isolated from Desulfovibrio gigas, a sulfate reducer. They are separated by a combination of DEAE-cellulose and gel filtration chromatographic procedures. FdI and FdI′ present a slight difference in isoelectric point which enables the separation of the two forms over DEAE-cellulose, while FdII is easily separated from the two other forms by gel filtration. The three forms have the same amino acid composition and are isolated in different aggregation states. Molecular weight determinations by gel filtration gave values of 18 000 for FdI and FdI′ and 24 000 for FdII, whereas a value of 6000 is determined when dissociation is accomplished with sodium dodecyl sulfate. The electronic spectra are different and their ultraviolet-visible absorbance rations are 0.77, 0.87 and 0.68 respectively for FdI, FdI′ and FdII. Despite these differences, the physiological activities of the three forms are similar as far as the reduction of sulfite by molecular hydrogen is concerned.     

Phylogenetic and biogeographic analysis of the genus Phytoseiulus (Acari: Phytoseiidae)

Kanouh, M., Tixier, M.‐S., Okassa, M. & Kreiter, S. (2010). Phylogenetic and biogeographic analysis of the genus Phytoseiulus (Acari: Phytoseiidae) —Zoologica Scripta, 39, 450–461. The taxonomy of the genus Phytoseiulus (sub‐family Amblyseiinae), has a tumultuous and confused history. This genus currently contains four species, but in previous revisions it contained five, sometimes grouped in two genera. There are no thorough phylogenetic analyses available for the group, analyses against which taxonomic and evolutionary hypotheses could be tested. The present study aims to apply morphological and molecular data to determine phylogenetic relationships among the four species presently included in this genus plus Afroseiulus robertsi, which was previously included in this genus. The new analyses show that the species of the genus Phytoseiulus do not constitute a monophyletic group. A delineation between (i) P. macropilis, P. persimilis, P. fragariae and (ii) P. longipes and A. robertsi is observed. Biogeographic data sets showed that the Neotropical and Afrotropical regions contain the highest diversity of species of Phytoseiulus and of their host plants. Consequently, the western part of Gondwana is hypothesized to be the probable centre of origin for this taxon.     

Propylisopropylacetic acid (PIA), a constitutional isomer of valproic acid,uncompetitively inhibits arachidonic acid acylation by rat acyl-CoA synthetase 4: A potential drug for bipolar disorder

Background

Mood stabilizers used for treating bipolar disorder (BD) selectively downregulate arachidonic acid (AA) turnover (deacylation–reacylation) in brain phospholipids, when given chronically to rats. In vitro studies suggest that one of these, valproic acid (VPA), which is teratogenic, reduces AA turnover by inhibiting the brain long-chain acyl-CoA synthetase (Acsl)4 mediated acylation of AA to AA-CoA. We tested whether non-teratogenic VPA analogues might also inhibit Acsl4 catalyzed acylation, and thus have a potential anti-BD action.

Methods

Rat Acsl4-flag protein was expressed in Escherichia coli, and the ability of three VPA analogues, propylisopropylacetic acid (PIA), propylisopropylacetamide (PID) and N-methyl-2,2,3,3-tetramethylcyclopropanecarboxamide (MTMCD), and of sodium butyrate, to inhibit conversion of AA to AA-CoA by Acsl4 was quantified using Michaelis–Menten kinetics.

Results

Acsl4-mediated conversion of AA to AA-CoA in vitro was inhibited uncompetitively by PIA, with a K_i of 11.4 mM compared to a published K_i of 25 mM for VPA, while PID, MTMCD and sodium butyrate had no inhibitory effect.

Conclusions

PIA's ability to inhibit conversion of AA to AA-CoA by Acsl4 in vitro suggests that, like VPA, PIA may reduce AA turnover in brain phospholipids in unanesthetized rats, and if so, may be effective as a non-teratogenic mood stabilizer in BD patients.