An autophosphorylating but not transphosphorylating activity is associated with the unique N terminus of the herpes simplex virus type 1 ribonucleotide reductase large subunit.

We report on a protein kinase function encoded by the unique N terminus of the herpes simplex virus type 1 (HSV-1) ribonucleotide reductase large subunit (R1). R1 expressed in Escherichia coli exhibited autophosphorylation activity in a reaction which depended on the presence of the unique N terminus. When the N terminus was separately expressed in E. coli and partially purified, a similar autophosphorylation reaction was observed. Importantly, transphosphorylation of histones and of proteins in HSV-1-infected cell extracts was also observed with purified R1 and with truncated R1 mutants in which most of the N terminus was deleted. Ion-exchange chromatography was used to separate the autophosphorylating activity of the N terminus from the transphosphorylating activity of an E. coli contaminant protein kinase. We propose a putative function for this activity of the HSV-1 R1 N terminus during the immediate-early phase of virus replication.     

A deeper meaning for shallow-level phylogenomic studies: nested anchored hybrid enrichment offers great promise for resolving the tiger moth tree of life (Lepidoptera: Erebidae: Arctiinae)

Anchored hybrid enrichment (AHE) has emerged as a powerful tool for uncovering the evolutionary relationships within many taxonomic groups. AHE probe sets have been developed for a variety of insect groups, though none have yet been shown to be capable of simultaneously resolving deep and very shallow (e.g., intraspecific) divergences. In this study, we present NOC1, a new AHE probe set (730 loci) for Lepidoptera specialized for tiger moths and assess its ability to deliver phylogenetic utility at all taxonomic levels. We test the NOC1 probe set with 142 individuals from 116 species sampled from all the major lineages of Arctiinae (Erebidae), one of the most diverse groups of noctuoids (>11 000 species) for which no well-resolved, strongly supported phylogenetic hypothesis exists. Compared to previous methods, we generally recover much higher branch support (BS), resulting in the most well-supported, well-resolved phylogeny of Arctiinae to date. At the most shallow-levels, NOC1 confidently resolves species-level and intraspecific relationships and potentially uncovers cryptic species diversity within the genus Hypoprepia. We also implement a ‘sensitivity analysis’ to explore different loci combinations and site sampling strategies to determine whether a reduced probe set can yield results similar to those of the full probe set. At both deep and shallow levels, only 50–175 of the 730 loci included in the complete NOC1 probe set were necessary to resolve most relationships with high confidence, though only when the more rapidly evolving sites within each locus are included. This demonstrates that AHE probe sets can be tailored to target fewer loci without a significant reduction in BS, allowing future studies to incorporate more taxa at a lower per-sample sequencing cost. NOC1 shows great promise for resolving long-standing taxonomic issues and evolutionary questions within arctiine lineages, one of the most speciose clades within Lepidoptera.     

Persistence of a Wolbachia infection frequency cline in Drosophila melanogaster and the possible role of reproductive dormancy

Field populations of arthropods are often polymorphic for Wolbachia but the factors maintaining intermediate Wolbachia frequencies are generally not understood. In Drosophila melanogaster, Wolbachia frequencies are highly variable across the globe. We document the persistence of a Wolbachia infection frequency cline in D. melanogaster populations from eastern Australia across at least 20 years, with frequencies generally high in the tropics but lower in cool temperate regions. The results are interpreted using a model of frequency dynamics incorporating cytoplasmic incompatibility (CI), imperfect maternal transmission and Wolbachia effects on fitness. Clinal variation is less pronounced in eastern North America which may reflect annual recolonization at higher latitudes. Limited samples from Africa from latitudes matching our tropical and subtropical samples from Australia and North America show comparably high infection frequencies, but some equatorial samples show lower frequencies. Adult dormancy across cold periods may contribute to the Australian Wolbachia cline. Infected flies exposed to cold conditions for an extended period had reduced fecundity and viability, an effect not evident in unexposed controls. These fitness costs may contribute to the relatively low Wolbachia frequencies in Australian temperate areas; whereas different processes, including CI induced by young males, may contribute to higher frequencies in tropical locations.     

Has vertebrate chemesthesis been a selective agent in the evolution of arthropod chemical defenses?

Arthropods use a variety of chemical substances to repel potential predators, but how did they arrive at the suite of chemicals that they use? One way to explore this question is to map chemically defended arthropod species in a multidimensional "compound" space. Clustering within this space indicates species that share similar combinations of chemical compounds and can reflect a phylogenetic signal, common biochemical pathways, or both. More important for this study, clustering can help to identify allomone targets. We herein compare common arthropod allomones with known vertebrate trigeminal irritants. We argue that the degree of overlap between these two groups of compounds indicates that chemesthesis was an important determining factor in the evolution of many arthropod allomones. The multidimensional scaling methods used may also allow the identification of new irritant receptors.     

Genetic engineering of crops as potential source of genetic hazard in the human diet.

The benefits of genetic engineering of crop plants to improve the reliability and quality of the world food supply have been contrasted with public concerns raised about the food safety of the resulting products. Debates have concentrated on the possible unforeseen risks associated with the accumulation of new metabolites in crop plants that may contribute to toxins, allergens and genetic hazards in the human diet. This review examines the various molecular and biochemical mechanisms by which new hazards may appear in foods as a direct consequence of genetic engineering in crop plants. Such hazards may arise from the expression products of the inserted genes, secondary or pleiotropic effects of transgene expression, and random insertional mutagenic effects resulting from transgene integration into plant genomes. However, when traditional plant breeding is evaluated in the same context, these mechanisms are no different from those that have been widely accepted from the past use of new cultivars in agriculture. The risks associated with the introduction of new genes via genetic engineering must be considered alongside the common breeding practice of introgressing large fragments of chromatin from related wild species into crop cultivars. The large proportion of such introgressed DNA involves genes of unknown function linked to the trait of interest such as pest or disease resistance. In this context, the potential risks of introducing new food hazards from the applications of genetic engineering are no different from the risks that might be anticipated from genetic manipulation of crops via traditional breeding. In many respects, the precise manner in which genetic engineering can control the nature and expression of the transferred DNA offers greater confidence for producing the desired outcome compared with traditional breeding.     

Maize Brittle Stalk2-Like3, encoding a COBRA protein,functions in cell wall formation and carbohydrate partitioning

Carbohydrate partitioning from leaves to sink tissues is essential for plant growth and development. The maize (Zea mays) recessive carbohydrate partitioning defective28 (cpd28) and cpd47 mutants exhibit leaf chlorosis and accumulation of starch and soluble sugars. Transport studies with ¹⁴C-sucrose (Suc) found drastically decreased export from mature leaves in cpd28 and cpd47 mutants relative to wild-type siblings. Consistent with decreased Suc export, cpd28 mutants exhibited decreased phloem pressure in mature leaves, and altered phloem cell wall ultrastructure in immature and mature leaves. We identified the causative mutations in the Brittle Stalk2-Like3 (Bk2L3) gene, a member of the COBRA family, which is involved in cell wall development across angiosperms. None of the previously characterized COBRA genes are reported to affect carbohydrate export. Consistent with other characterized COBRA members, the BK2L3 protein localized to the plasma membrane, and the mutants condition a dwarf phenotype in dark-grown shoots and primary roots, as well as the loss of anisotropic cell elongation in the root elongation zone. Likewise, both mutants exhibit a significant cellulose deficiency in mature leaves. Therefore, Bk2L3 functions in tissue growth and cell wall development, and this work elucidates a unique connection between cellulose deposition in the phloem and whole-plant carbohydrate partitioning.

Mutations in Bk2L3 result in dwarfed plants with decreased anisotropic cell growth, cellulose deposition, phloem pressure, sucrose export, and carbohydrate hyperaccumulation in mature maize leaves.     

Delipidated retroviruses as potential autologous therapeutic vaccines--a pilot experiment

This pilot experiment in a simian immunodeficiency virus (SIV) chronic infection model aimed at extending our previous findings that vaccination with delipidated SIV resulted in more potent and diversified antiviral responses (1). Macaques chronically infected with SIVmac239 treated with antiretroviral therapy (ART) were vaccinated with autologous delipidated virus via consecutive lymph node targeted immunizations-1, 1 and 10 mug of virus spaced monthly. Results showed all animals had lasting viral load reduction approaching 1 log compared to set-point, and disease delay. Delipidation may enhance processing/ presentation of viral antigen eliciting potent antiviral control even at such late infection stage.