Resistance to diamide insecticides in diamondback moth,Plutella xylostella (Lepidoptera: Plutellidae) is associated with a mutation in the membrane-spanning domain of the ryanodine receptor

Diamide insecticides such as chlorantraniliprole and flubendiamide are a new class of insecticide that selectively target insect ryanodine receptors (RyR), a distinct class of homo-tetrameric calcium release channels which play a pivotal role in calcium homeostasis in numerous cell types. Resistance to these insecticides has recently been reported in the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), a global lepidopteran pest of cruciferous crops. In the present study a region of the gene encoding the proposed diamide binding site of the RyR from P. xylostella collected from the Philippines and Thailand and found to be over 200-fold resistant to both chlorantraniliprole and flubendiamide compared to susceptible strains, were amplified by RT-PCR and sequenced. Comparison of the sequence with those from several susceptible reference strains revealed non-synonymous mutations in each of the resistant strains that in both cases lead to a glycine to glutamic acid substitution (G4946E) in the protein. The independent evolution of the same amino acid substitution within a highly conserved region of the proposed diamide binding site in two geographically separated resistant strains of P. xylostella strongly suggests a causal association with diamide resistance. Furthermore we designed a pyrosequencing-based diagnostic assay for resistance monitoring purposes that can be used to detect the G4946E mutation in field-collected samples of diamondback moth. The implications of the reported findings for resistance management strategies are discussed.     

Virus inhibition activity of effector memory CD8(+) T cells determines simian immunodeficiency virus load in vaccinated monkeys after vaccine breakthrough infection

The goal of an effective AIDS vaccine is to generate immunity that will prevent human immunodeficiency virus 1 (HIV-1) acquisition. Despite limited progress toward this goal, renewed optimism has followed the recent success of the RV144 vaccine trial in Thailand. However, the lack of complete protection in this trial suggests that breakthroughs, where infection occurs despite adequate vaccination, will be a reality for many vaccine candidates. We previously reported that neutralizing antibodies elicited by DNA prime-recombinant adenovirus serotype 5 (rAd5) boost vaccination with simian immunodeficiency virus strain mac239 (SIVmac239) Gag-Pol and Env provided protection against pathogenic SIVsmE660 acquisition after repeated mucosal challenge. Here, we report that SIV-specific CD8(+) T cells elicited by that vaccine lowered both peak and set-point viral loads in macaques that became infected despite vaccination. These SIV-specific CD8(+) T cells showed strong virus-inhibitory activity (VIA) and displayed an effector memory (EM) phenotype. VIA correlated with high levels of CD107a mobilization and perforin expression in SIV-specific CD8(+) T cells. Remarkably, both the frequency and the number of Gag CM9-specific public clonotypes were strongly correlated with VIA mediated by EM CD8(+) T cells. The ability to elicit such virus-specific EM CD8(+) T cells might contribute substantially to an efficacious HIV/AIDS vaccine, even after breakthrough infection.     

Hepatocyte DNA replication in growing liver requires either glutathione or a single allele of txnrd1

Ribonucleotide reductase (RNR) activity requires an electron donor, which in bacteria, yeast, and plants is usually either reduced thioredoxin (Trx) or reduced glutaredoxin. Mice lacking glutathione reductase are viable and, although mice lacking thioredoxin reductase 1 (TrxR1) are embryonic-lethal, several studies have shown that mouse cells lacking the txnrd1 gene, encoding TrxR1, can proliferate normally. To better understand the in vivo electron donor requirements for mammalian RNR, we here investigated whether replication of TrxR1-deficient hepatocytes in mouse livers either employed an alternative source of Trx-reducing activity or, instead, solely relied upon the glutathione (GSH) pathway. Neither normal nor genetically TrxR1-deficient livers expressed substantial levels of mRNA splice forms encoding cytosolic variants of TrxR2, and the TrxR1-deficient livers showed severely diminished total TrxR activity, making it unlikely that any alternative TrxR enzyme activities complemented the genetic TrxR1 deficiency. To test whether the GSH pathway was required for replication, GSH levels were depleted by administration of buthionine sulfoximine (BSO) to juvenile mice. In controls not receiving BSO, replicative indexes were similar in hepatocytes having two, one, or no functional alleles of txnrd1. After BSO treatment, hepatocytes containing either two or one copies of this gene were also normal. However, hepatocytes completely lacking a functional txnrd1 gene exhibited severely reduced replicative indexes after GSH depletion. We conclude that hepatocyte proliferation in vivo requires either GSH or at least one functional allele of txnrd1, demonstrating that either the GSH- or the TrxR1-dependent redox pathway can independently support hepatocyte proliferation during liver growth.     

The ethics of blood donation: Does altruism suffice?

Is the recommendation of the WHO, endorsed by all member states, that all blood donations should be voluntary and non-compensated ethically coherent and realizable in practice? In a recent paper, Farrugia et al have argued for a plurality of both compensated and non-compensated systems, claiming that, from both an ethical and practical perspective, the classical concept of the ‘the gift relationship’, advocated over 40 years ago by Richard Titmuss, is unnecessary and inadequate. This paper focuses on the ethical aspects of this debate, considering the concepts of altruism, reciprocity and social solidarity as they apply to the procurement of blood and blood products, as well as evidence regarding safety of different sources of blood and the motivations of regular donors. It concludes with a discussion of the view summarized in a recent publication by Campbell (2009), that, although the body may be monetized, doing so would result in a loss of human value.     

Genome-wide metabolic network reconstruction of the picoalga Ostreococcus

The green picoalga Ostreococcus is emerging as a simple plant model organism, and two species, O. lucimarinus and O. tauri, have now been sequenced and annotated manually. To evaluate the completeness of the metabolic annotation of both species, metabolic networks of O. lucimarinus and O. tauri were reconstructed from the KEGG database, thermodynamically constrained, elementally balanced, and functionally evaluated. The draft networks contained extensive gaps and, in the case of O. tauri, no biomass components could be produced due to an incomplete Calvin cycle. To find and remove gaps from the networks, an extensive reference biochemical reaction database was assembled using a stepwise approach that minimized the inclusion of microbial reactions. Gaps were then removed from both Ostreococcus networks using two existing gap-filling methodologies. In the first method, a bottom-up approach, a minimal list of reactions was added to each model to enable the production of all metabolites included in our biomass equation. In the second method, a top-down approach, all reactions in the reference database were added to the target networks and subsequently trimmed away based on the sequence alignment scores of identified orthologues. Because current gap-filling methods do not produce unique solutions, a quality metric that includes a weighting for phylogenetic distance and sequence similarity was developed to distinguish between gap-filling results automatically. The draft O. lucimarinus and O. tauri networks required the addition of 56 and 70 reactions, respectively, in order to produce the same biomass precursor metabolites that were produced by our plant reference database.     

Semaphorin 3A is a marker for disease activity and a potential immunoregulator in systemic lupus erythematosus

Introduction

Higher levels of high density lipoprotein (HDL) subfractions HDL3-chol and particularly HDL2-chol protect against cardiovascular disease (CVD), but inflammation reduces the HDL level and may impair its anti-atherogenic effect. Changed HDL composition through the impact of inflammation on HDL subfractions may contribute to the excess risk of CVD in rheumatoid arthritis (RA). In this study, we investigated whether HDL2-chol and HDL3-chol concentrations differ between RA patients and healthy controls, and whether these levels are related to the level of RA disease activity.

Methods

Non-fasting blood samples were collected from 45 RA patients and 45 healthy controls. None of the participants had a history of CVD, diabetes, or used lipid-lowering drugs. HDL2-chol and HDL3-chol concentrations were obtained by ultracentrifugation. Regression modeling was used to compare HDL subfraction levels between RA patients and healthy controls, and to analyze the effect of disease activity on HDL2-chol and HDL3-chol.

Results

HDL2-chol and HDL3-chol were significantly lower in RA patients compared to healthy controls (P = 0.01, P = 0.005, respectively). The HDL2:HDL3 ratio was significantly lower in patients compared to controls (P = 0.04). Reduced HDL2-chol and HDL3-chol levels were primarily present in female RA patients and not in male RA patients. A modest effect of the disease activity score in 28 joins ( DAS28) on HDL2-chol concentrations was found, after correction for disease duration, glucocorticosteroid use and body mass index (BMI), with a 0.06 mmol/L decrease with every point increase in DAS28 (P = 0.05). DAS28 did not significantly affect HDL3-chol concentrations (P = 0.186).

Conclusions

Both HDL subfractions but particularly HDL2-chol concentrations were decreased in RA, primarily in women. This seems to be associated with disease activity and is of clinical relevance. The reduction of the HDL subfraction concentrations, particularly the supposedly beneficial HDL2-chol, may negatively impact the cardiovascular risk profile of women with RA.