Efficacy of selected insecticides against eggs of Euschistus servus and Acrosternum hilare (Hemiptera: Pentatomidae) and the egg parasitoid Telenomus podisi (Hymenoptera: Scelionidae)

Brown stink bug, Euschistus servus (Say), and green stink bug, Acrosternum hilare (Say) (Hemiptera: Pentatomidae), are major agricultural pests. Although various insecticides are used to control nymphs and adults, little is known about how they affect eggs. Laboratory bioassays and field trials were conducted to determine the efficacy of common field rates of acephate, lamda-cyhalothrin, spinosad, and thiamethoxam on developing E. servus and A. hilare eggs, as well as Telenomus podisi Ashmead (Hymenoptera: Scelionidae) parasitoids developing in E. servus eggs. In laboratory bioassays, egg masses were dipped into insecticide and water solutions and assessed for mortality after 2 wk. In the field trials, egg masses on a cloth section were pinned to leaves in each plot ofa randomized complete block and returned to the laboratory 24 h after exposure to insecticide sprays. Mortality was assessed after 2 wk. In dip bioassays, there was a significant effect of insecticide treatment on A. hilare eggs with all insecticides resulting in greater mortality than the water control. However, no effect of treatment occurred in the field with A. hilare or for E. serous eggs in both the laboratory bioassays and the field trials. In contrast, developing T. podisi parasitoids showed significant mortality when exposed to all insecticide treatments, when dipped or field-treated. Spinosad and lamda-cyhalothrin treatments resulted in 100% mortality of T. podisi, and acephate resulted in greater mortality than thiamethoxam. Our results suggest that there is relatively little efficacy from insecticide sprays on stink bugs developing in eggs but that mortality of egg parasitoids may be significant.     

The genome of Yoka poxvirus

Yoka poxvirus was isolated almost four decades ago from a mosquito pool in the Central African Republic. Its classification as a poxvirus is based solely upon the morphology of virions visualized by electron microscopy. Here we describe sequencing of the Yoka poxvirus genome using a combination of Roche/454 and Illumina next-generation sequencing technologies. A single consensus contig of ～175 kb in length that encodes 186 predicted genes was generated. Multiple methods were used to show that Yoka poxvirus is most closely related to viruses in the Orthopoxvirus genus, but it is clearly distinct from previously described poxviruses. Collectively, the phylogenetic and genomic sequence analyses suggest that Yoka poxvirus is the prototype member of a new genus in the family Poxviridae.     

Prion protein interacts with BACE1 protein and differentially regulates its activity toward wild type and Swedish mutant amyloid precursor protein

In Alzheimer disease amyloid-β (Aβ) peptides derived from the amyloid precursor protein (APP) accumulate in the brain. Cleavage of APP by the β-secretase BACE1 is the rate-limiting step in the production of Aβ. We have reported previously that the cellular prion protein (PrP(C)) inhibited the action of BACE1 toward human wild type APP (APP(WT)) in cellular models and that the levels of endogenous murine Aβ were significantly increased in PrP(C)-null mouse brain. Here we investigated the molecular and cellular mechanisms underlying this observation. PrP(C) interacted directly with the prodomain of the immature Golgi-localized form of BACE1. This interaction decreased BACE1 at the cell surface and in endosomes where it preferentially cleaves APP(WT) but increased it in the Golgi where it preferentially cleaves APP with the Swedish mutation (APP(Swe)). In transgenic mice expressing human APP with the Swedish and Indiana familial mutations (APP(Swe,Ind)), PrP(C) deletion had no influence on APP proteolytic processing, Aβ plaque deposition, or levels of soluble Aβ or Aβ oligomers. In cells, although PrP(C) inhibited the action of BACE1 on APP(WT), it did not inhibit BACE1 activity toward APP(Swe). The differential subcellular location of the BACE1 cleavage of APP(Swe) relative to APP(WT) provides an explanation for the failure of PrP(C) deletion to affect Aβ accumulation in APP(Swe,Ind) mice. Thus, although PrP(C) exerts no control on cleavage of APP(Swe) by BACE1, it has a profound influence on the cleavage of APP(WT), suggesting that PrP(C) may be a key protective player against sporadic Alzheimer disease.     

Spectrum of MHC class II variability in Darwin's finches and their close relatives

The study describes >400 major histocompatibility complex (MHC) class II B exon 2 and 114 intron 2 sequences of 36 passerine bird species, 13 of which belong to the group of Darwin's finches (DFs) and the remaining 23 to close or more distant relatives of DFs in Central and South America. The data set is analyzed by a combination of judiciously selected statistical methods. The analysis reveals that reliable information concerning MHC organization, including the assignment of sequences to loci, and evolution, as well as the process of species divergence, can be obtained in the absence of genomic sequence data, if the analysis is taken several steps beyond the standard phylogenetic tree construction approach. The main findings of the present study are these: The MHC class II B region of the passerine birds is as elaborate in its organization, divergence, and genetic diversity as the MHC of the eutherian mammals, specifically the primates. Hence, the reported simplicity of the fowl MHC is an oddity. With the help of appropriate markers, the divergence of the MHC genes can be traced deep in the phylogeny of the bird taxa. Transspecies polymorphism is rampant at many of the bird MHC loci. In this respect, the DFs behave as if they were a single, genetically undifferentiated population. There is thus far no indication of alleles that could be considered species, genus, or even DF group specific. The implication of these findings is that DFs are in the midst of adaptive radiations, in which morphological differentiation into species is running ahead of genetic differentiation in genetic systems such as the MHC or the mitochondrial DNA. The radiations are so young that there has not been enough time to sort out polymorphisms at most of the loci among the morphologically differentiating species. These findings parallel those on Lake Victoria haplochromine fishes. Several of the DF MHC allelic lineages can be traced back to the MHC genes of the species Tiaris obscura, which we identified previously as the closest extant relative of DFs in continental America.     

X-Ray structure determination of three mutants of the bacterial photosynthetic reaction centers from Rb. sphaeroides; altered proton transfer pathways

In the photosynthetic reaction center (RC) from Rhodobacter sphaeroides, the reduction of a bound quinone molecule Q(B) is coupled with proton uptake. When Asp-L213 is replaced by Asn, proton transfer is inhibited. Proton transfer was restored by two second-site revertant mutations, Arg-M233-->Cys and Arg-H177-->His. Kinetic effects of Cd(2+) on proton transfer showed that the entry point in revertant RCs to be the same as in the native RC. The structures of the parental and two revertant RCs were determined at resolutions of 2.10, 1.80, and 2.75 A. From the structures, we were able to delineate alternate proton transfer pathways in the revertants. The main changes occur near Glu-H173, which allow it to substitute for the missing Asp-L213. The electrostatic changes near Glu-H173 cause it to be a good proton donor and acceptor, and the structural changes create a cavity which accommodates water molecules that connect Glu-H173 to other proton transfer components.     

Analysis of Wnt8 for neural posteriorizing factor by identifying Frizzled 8c and Frizzled 9 as functional receptors for Wnt8

The dorsal ectoderm of vertebrate gastrula is first specified into anterior fate by an activation signal and posteriorized by a graded transforming signal, leading to the formation of forebrain, midbrain, hindbrain and spinal cord along the anteroposterior (A-P) axis. Transplanted non-axial mesoderm rather than axial mesoderm has an ability to transform prospective anterior neural tissue into more posterior fates in zebrafish. Wnt8 is a secreted factor that is expressed in non-axial mesoderm. To investigate whether Wnt8 is the neural posteriorizing factor that acts upon neuroectoderm, we first assigned Frizzled 8c and Frizzled 9 to be functional receptors for Wnt8. We then, transplanted non-axial mesoderm into the embryos in which Wnt8 signaling is cell-autonomously blocked by the dominant-negative form of Wnt8 receptors. Non-axial mesodermal transplants in embryos in which Wnt8 signaling is cell-autonomously blocked induced the posterior neural markers as efficiently as in wild-type embryos, suggesting that Wnt8 signaling is not required in neuroectoderm for posteriorization by non-axial mesoderm. Furthermore, Wnt8 signaling, detected by nuclear localization of beta-catenin, was not activated in the posterior neuroectoderm but confined in marginal non-axial mesoderm. Finally, ubiquitous over-expression of Wnt8 does not expand neural ectoderm of posterior character in the absence of mesoderm or Nodal-dependent co-factors. We thus conclude that other factors from non-axial mesoderm may be required for patterning neuroectoderm along the A-P axis.     

Functional analysis in yeast of the Brix protein superfamily involved in the biogenesis of ribosomes

An extensive homology search based on the sequence of the yeast protein Brx1p (biogenesis of ribosomes in Xenopus, YOL077c) revealed that it is a member of a superfamily of proteins sharing remarkable sequence similarities. Previous work on Brx1p showed that this protein is involved in the process of ribosome biogenesis [Kaser et al., Biol. Chem. 382 (2001) 1637-1647]. Brx1p is the founding member of one of the five existing eukaryotic subfamilies which are all present in yeast. Four of them are represented by one essential gene each and one family is represented by two closely related genes which can functionally replace each other but are essential together for survival. We created conditional alleles of four of the five genes which allowed us to study the effect of depletion of the respective proteins on the ribosome profiles of the strains. In this study we show that not only Brx1p but also three additional superfamily members, namely YHR088w (Rpf1p), YKR081c (Rpf2p) and the homologous proteins Ssf1p (YHR066w)/Ssf2p (YDR312w) are all involved in the multistep process of the assembly of the large ribosomal subunit. This agrees well with the fact that these three proteins, like Brx1p, are located in the nucleolus. Moreover, all four proteins closely interact functionally, because all four mutants are suppressed by the same multicopy suppressor gene.     

Substituted 2-(R)-methyl piperazines as muscarinic M(2) selective ligands

A novel series of 2-(R)-methyl-substituted piperazines (e.g., 2) is described. They are potent M(2) selective ligands that have >100-fold selectivity versus the M(1) receptor. In the rat microdialysis assay, compound 14 showed significantly enchanced levels of acetylcholine after oral administration.     

Structural basis for inhibition promiscuity of dual specific thrombin and factor Xa blood coagulation inhibitors

BACKGROUND: A major current focus of pharmaceutical research is the development of selective inhibitors of the blood coagulation enzymes thrombin or factor Xa to be used as orally bioavailable anticoagulant drugs in thromboembolic disorders and in the prevention of venous and arterial thrombosis. Simultaneous direct inhibition of thrombin and factor Xa by synthetic proteinase inhibitors as a novel approach to antithrombotic therapy could result in potent anticoagulants with improved pharmacological properties. RESULTS: The binding mode of such dual specific inhibitors of thrombin and factor Xa was determined for the first time by comparative crystallography using human alpha-thrombin, human des-Gla (1--44) factor Xa and bovine trypsin as the ligand receptors. The benzamidine-based inhibitors utilize two different conformations for the interaction with thrombin and factor Xa/trypsin, which are evoked by the steric requirements of the topologically different S2 subsites of the enzymes. Compared to the unliganded forms of the proteinases, ligand binding induces conformational adjustments of thrombin and factor Xa active site residues indicative of a pronounced induced fit mechanism. CONCLUSION: The structural data reveal the molecular basis for a desired unselective inhibition of the two key components of the blood coagulation cascade. The 4-(1-methyl-benzimidazole-2-yl)-methylamino-benzamidine moieties of the inhibitors are able to fill both the small solvent accessible as well as the larger hydrophobic S2 pockets of factor Xa and thrombin, respectively. Distal fragments of the inhibitors are identified which fit into both the cation hole/aromatic box of factor Xa and the hydrophobic aryl binding site of thrombin. Thus, binding constants in the medium-to-low nanomolar range are obtained against both enzymes.     

The Personality Behind Cheating: Behavioural Types and the Feeding Ecology of Cleaner Fish

The complex mutualistic relationship between the cleaner fish (Labroides dimidiatus) and their ‘clients’ in many reef systems throughout the world has been the subject of debate and research interest for decades. Game‐theory models have long struggled with explaining how the mixed strategies of cheating and honesty might have evolved in such a system and while significant efforts have been made theoretically, demonstrating the nature of this relationship empirically remains an important research challenge. Using the experimental framework of behavioural syndromes, we sought to quantitatively assess the relationship between personality and the feeding ecology of cleaner fish to provide novel insights into the underlying mechanistic basis of cheating in cleaner‐client interactions. First, we observed and filmed cleaner fish interactions with heterospecifics, movement patterns and general feeding ecology in the wild. We then captured and measured all focal individuals and tested them for individual consistency in measures of activity, exploration and risk taking (boldness) in the laboratory. Our results suggest a syndrome incorporating aspects of personality and foraging effort are central components of the behavioural ecology of L. dimidiatus on the Great Barrier Reef. We found that individuals that exhibited greater feeding effort tended to cheat proportionately less and move over smaller distances relative to bolder more active, exploratory individuals. Our study demonstrates for the first time that individual differences in personality might be mechanistically involved in explaining how the mixed strategies of cheating and honesty persist in cleaner fish mutualisms.