Potential inter-guild interactions to enhance biological control of Bactericera cockerelli on tomatoes: a laboratory and cage study

The tomato–potato psyllid (TPP) Bactericera cockerelli, is a serious pest of solanaceous crops. Some populations are becoming pesticide-resistant, increasing the need for alternatives such as biological control (BC). This approach may be improved by combining different species of BC agents. We conducted three separate experiments to test four BC agents, either alone or combined with others: (1) A laboratory assay to test the effect of buckwheat (Fagopyrum esculentum) and alyssum (Lobularia maritima) flowers on the longevity of females of the parasitic wasp Tamarixia triozae; (2) A no-choice laboratory assay to investigate the consumption of B. cockerelli life stages by the predatory bug Engytatus nicotianae; (3) A cage experiment in a greenhouse to assess four natural enemy species against B. cockerelli on tomatoes: these were the predators Cleobora mellyi, Amblydromalus limonicus, E. nicotianae, and T. triozae. Access to buckwheat flowers allowed female T. triozae to live for an average of 10.9 days compared to 2.1 days with alyssum and 1.4 day with water but did not improve the BC of B. cockerelli. Adult E. nicotianae preyed on all offered B. cockerelli stages. In experiment 3, combinations of T. triozae with A. limonicus or E. nicotianae were not significantly better than single natural enemy species, except for the reduction of nymphal populations when A. limonicus and T. triozae were combined. Although there were few significant reductions in numbers of TPP when using natural enemy species combinations, some species showed good potential when used alone. We suggest testing earlier release of combinations of natural enemy for evaluate its impact on TPP.

     

Disruption of Ttll5/Stamp Gene (Tubulin Tyrosine Ligase-like Protein 5/SRC-1 and TIF2-associated Modulatory Protein Gene) in Male Mice Causes Sperm Malformation and Infertility

TTLL5/STAMP (tubulin tyrosine ligase-like family member 5) has multiple activities in cells. TTLL5 is one of 13 TTLLs, has polyglutamylation activity, augments the activity of p160 coactivators (SRC-1 and TIF2) in glucocorticoid receptor-regulated gene induction and repression, and displays steroid-independent growth activity with several cell types. To examine TTLL5/STAMP functions in whole animals, mice were prepared with an internal deletion that eliminated several activities of the Stamp gene. This mutation causes both reduced levels of STAMP mRNA and C-terminal truncation of STAMP protein. Homozygous targeted mutant (Stamp^tm/tm) mice appear normal except for marked decreases in male fertility associated with defects in progressive sperm motility. Abnormal axonemal structures with loss of tubulin doublets occur in most Stamp^tm/tm sperm tails in conjunction with substantial reduction in α-tubulin polyglutamylation, which closely correlates with the reduction in mutant STAMP mRNA. The axonemes in other structures appear unaffected. There is no obvious change in the organs for sperm development of WT versus Stamp^tm/tm males despite the levels of WT STAMP mRNA in testes being 20-fold higher than in any other organ examined. This defect in male fertility is unrelated to other Ttll genes or 24 genes previously identified as important for sperm function. Thus, STAMP appears to participate in a unique, tissue-selective TTLL-mediated pathway for α-tubulin polyglutamylation that is required for sperm maturation and motility and may be relevant for male fertility.     

The first detection of influenza in the Finnish pig population: a retrospective study

Background

Swine influenza is an infectious acute respiratory disease of pigs caused by influenza A virus. We investigated the time of entry of swine influenza into the Finnish pig population. We also describe the molecular detection of two types of influenza A (H1N1) viruses in porcine samples submitted in 2009 and 2010.This retrospective study was based on three categories of samples: blood samples collected for disease monitoring from pigs at major slaughterhouses from 2007 to 2009; blood samples from pigs in farms with a special health status taken in 2008 and 2009; and diagnostic blood samples from pigs in farms with clinical signs of respiratory disease in 2008 and 2009.The blood samples were tested for influenza A antibodies with an antibody ELISA. Positive samples were further analyzed for H1N1, H3N2, and H1N2 antibodies with a hemagglutination inhibition test.Diagnostic samples for virus detection were subjected to influenza A M-gene-specific real-time RT-PCR and to pandemic influenza A H1N1-specific real-time RT-PCR. Positive samples were further analyzed with RT-PCRs designed for this purpose, and the PCR products were sequenced and sequences analyzed phylogenetically.

Results

In the blood samples from pigs in special health class farms producing replacement animals and in diagnostic blood samples, the first serologically positive samples originated from the period July–August 2008. In samples collected for disease monitoring, < 0.1%, 0% and 16% were positive for antibodies against influenza A H1N1 in the HI test in 2007, 2008, and 2009, respectively.Swine influenza A virus of avian-like H1N1 was first detected in diagnostic samples in February 2009. In 2009 and 2010, the avian-like H1N1 virus was detected on 12 and two farms, respectively. The pandemic H1N1 virus (A(H1N1)pdm09) was detected on one pig farm in 2009 and on two farms in 2010.

Conclusions

Based on our study, swine influenza of avian-like H1N1 virus was introduced into the Finnish pig population in 2008 and A(H1N1)pdm09 virus in 2009. The source of avian-like H1N1 infection could not be determined. Cases of pandemic H1N1 in pigs coincided with the period when the A(H1N1)pdm09 virus was spread in humans in Finland.

     

A metabolomic,geographic, and seasonal analysis of the contribution of pollen-derived adenosine to allergic sensitization

Background

Studies on ragweed and birch pollen extracts suggested that the adenosine content is an important factor in allergic sensitization. However, exposure levels from other pollens and considerations of geographic and seasonal factors have not been evaluated.

Objective

This study compared the metabolite profile of pollen species important for allergic disease, specifically measured the adenosine content, and evaluated exposure to pollen-derived adenosine.

Methods

An NMR metabolomics approach was used to measure metabolite concentrations in 26 pollen extracts. Pollen count data was analyzed from five cities to model exposure.

Results

A principal component analysis of the various metabolites identified by NMR showed that pollen extracts could be differentiated primarily by sugar content: glucose, fructose, sucrose, and myo-inositol. In extracts of 10 mg of pollen/ml, the adenosine was highest for grasses (45 µM) followed by trees (23 µM) and weeds (19 µM). Pollen count data showed that tree pollen was typically 5–10 times the amount of other pollens. At the daily peaks of tree, grass, and weed season the pollen-derived adenosine exposure per day is likely to be only 1.1, 0.11, and 0.12 µg, respectively. Seasonal models of pollen exposure and respiration suggest that it would be a rare event limited to tree pollen season for concentrations of pollen-derived adenosine to approach physiological levels.

Conclusion

Sugar content and other metabolites may be useful in classifying pollens. Unless other factors create localized exposures that are very different from these models, pollen-derived adenosine is unlikely to be a major factor in allergic sensitization.

     

NMR assignment of polymerase β labeled with 2H, 13C, and 15N in complex with substrate DNA

DNA Polymerase β is a multifunctional enzyme involved in base excision repair of nuclear DNA in vertebrate cells. We present here the first assignments of the full-length protein (335 residues, 39 kDa) in the presence of a double gap—double hairpin DNA (22 nucleotides, 7 kDa).     

Effect of sterol structure on ordered membrane domain (raft) stability in symmetric and asymmetric vesicles

Sterol structure influences liquid ordered domains in membranes, and the dependence of biological functions on sterol structure can help identify processes dependent on ordered domains. In this study we compared the effect of sterol structure on ordered domain formation in symmetric vesicles composed of mixtures of sphingomyelin, 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol, and in asymmetric vesicles in which sphingomyelin was introduced into the outer leaflet of vesicles composed of DOPC and cholesterol. In most cases, sterol behavior was similar in symmetric and asymmetric vesicles, with ordered domains most strongly stabilized by 7-dehydrocholesterol (7DHC) and cholesterol, stabilized to a moderate degree by lanosterol, epicholesterol and desmosterol, and very little if at all by 4-cholesten-3-one. However, in asymmetric vesicles desmosterol stabilized ordered domain almost as well as cholesterol, and to a much greater degree than epicholesterol, so that the ability to support ordered domains decreased in the order 7-DHC > cholesterol > desmosterol > lanosterol > epicholesterol > 4-cholesten-3-one. This contrasts with values for intermediate stabilizing sterols in symmetric vesicles in which the ranking was cholesterol > lanosterol ~ desmosterol ~ epicholesterol or prior studies in which the ranking was cholesterol ~ epicholesterol > lanosterol ~ desmosterol. The reasons for these differences are discussed. Based on these results, we re-evaluated our prior studies in cells and conclude that endocytosis levels and bacterial uptake are even more closely correlated with the ability of sterols to form ordered domains than previously thought, and do not necessarily require that a sterol have a 3β-OH group.     

Development and evaluation of a boronate inhibitor of gamma-glutamyl transpeptidase

Gamma-glutamyl transpeptidase (gamma-GT) plays a central role in the metabolism of glutathione and is also a marker for neoplasia and cell transformation. We have investigated the compound L-2-amino-4-boronobutanoic acid (ABBA) as a structural analog of the putative ternary complex formed by the enzyme, L-serine, and borate, proposed to function as a transition state analog inhibitor. ABBA was found to be a potent inhibitor of the enzyme, with Ki = 17 nM using typical assay conditions (pH 8, gamma-glutamyl-p-nitroanilide substrate, 20 mM glycyl-glycine acceptor). ABBA is a stable amino acid analog with pK values determined from 13C and 11B NMR to be 2.3, 11.0 (amino titration), and 7.9 (boronate titration). The structural similarity to glutamate suggested that it might function as a glutamate analog for some glutamate-dependent enzymes or receptors. Transamination of pyruvate by ABBA to yield alanine in the presence of glutamic pyruvic transaminase was demonstrated by 13C NMR. The 2-keto-4-boronobutanoic acid transamination product is apparently fairly labile to hydrolysis, leading to formation of 2-ketobutanoic acid plus borate. The latter is also subsequently transaminated to yield 2-aminobutanoic acid. Both of these metabolites were observed in the 13C NMR spectrum. However, the corresponding transamination of oxaloacetate by ABBA in the presence of glutamic oxaloacetic transaminase was not observed. Effects of ABBA on the growth of cultured rat liver cell lines ARL-15C1 (nontumorigenic, low gamma-GT activity) and ARL-16T2 (tumorigenic, high gamma-GT activity) were also investigated, both in standard Williams Media as well as in a low cysteine growth medium. A high concentration (1 mM) of ABBA inhibited the growth of both cell lines in both media, with the degree of inhibition greater in the low cysteine medium. Alternatively, growth inhibition by 10 microM ABBA could be observed only in the low cysteine media. In general, there were no significant differences between the two cell lines in terms of sensitivity to ABBA.     

The inter-ligand Overhauser effect: A powerful new NMR approach for mapping structural relationships of macromolecular ligands

NMR experiments that transfer conformational information from the bound to the uncomplexed state via exchange have been utilized for many years. It is demonstrated here that inter-ligand NOEs (ILOEs), which exist in ternary complexes with enzymes or other macromolecular receptors, can be transferred via exchange to pairs of uncomplexed ligands. This approach is illustrated by studies of glycolate + NAD⁺ in the presence of porcine heart lactate dehydrogenase, and by glucose-6-phosphate + NADPH in the presence of L. mesenteroides glucose-6-phosphate dehydrogenase. This strategy opens up a general methodology for exploring the active sites of enzymes and for the development of artificial ligands which can function as inhibitors, or more generally as modifiers of protein function.