Enhancement of Bacillus thuringiensis toxicity by feeding Spodoptera littoralis larvae with bacteria expressing immune suppressive dsRNA

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Transgenic plants expressing immunosuppressive dsRNA improve entomopathogen efficacy against Spodoptera littoralis larvae

Transgenic plants that express double-stranded RNA (dsRNA) targeting vital insect genes have recently emerged as a valuable new tool for pest control. In this study, tobacco plants were transformed to produce dsRNA targeting Sl 102 gene that is involved in the immune response of Spodoptera littoralis larvae, a serious lepidopteran pest of several crops. Experimental larvae reared on transgenic tobacco lines showed (1) a strongly reduced level of Sl 102 transcripts, which was positively associated with food consumption; (2) a substantial impairment of the encapsulation response mediated by hemocytes; and (3) a marked increase in the susceptibility to Xentari™, a Bacillus thuringiensis-based insecticide. Importantly, this approach may allow a reduction in the doses of B. thuringiensis used for field applications and enhance its killing activity on mature larvae. The results obtained thus support the use of immunosuppressive RNAi plants to enhance the performance of microbial insecticides on lepidopteran larvae

Trichoderma atroviride P1 Colonization of Tomato Plants Enhances Both Direct and Indirect Defense Barriers Against Insects

Numerous microbial root symbionts are known to induce different levels of enhanced plant protection against a variety of pathogens. However, more recent studies have demonstrated that beneficial microbes are able to induce plant systemic resistance that confers some degree of protection against insects. Here, we report how treatments with the fungal biocontrol agent Trichoderma atroviride strain P1 in tomato plants induce responses that affect pest insects with different feeding habits: the noctuid moth Spodoptera littoralis (Boisduval) and the aphid Macrosiphum euphorbiae (Thomas). We observed that the tomato plant–Trichoderma P1 interaction had a negative impact on the development of moth larvae and on aphid longevity. These effects were attributed to a plant response induced by Trichoderma that was associated with transcriptional changes of a wide array of defense-related genes. While the impact on aphids could be related to the up-regulation of genes involved in the oxidative burst reaction, which occur early in the defense reaction, the negative performance of moth larvae was associated with the enhanced expression of genes encoding for protective enzymes (i.e., Proteinase inhibitor I (PI), Threonine deaminase, Leucine aminopeptidase A1, Arginase 2, and Polyphenol oxidase) that are activated downstream in the defense cascade. In addition, Trichoderma P1 produced alterations in plant metabolic pathways leading to the production and release of volatile organic compounds (VOCs) that are involved in the attraction of the aphid parasitoid Aphidius ervi, thus reinforcing the indirect plant defense barriers. Our findings, along with the evidence available in the literature, indicate that the outcome of the tripartite interaction among plant, Trichoderma, and pests is highly specific and only a comprehensive approach, integrating both insect phenotypic changes and plant transcriptomic alterations, can allow a reliable prediction of its potential for plant protectio

Evolution of an insect immune barrier through horizontal gene transfer mediated by a parasitic wasp.

Genome sequencing data have recently demonstrated that eukaryote evolution has been remarkably influenced by the acquisition of a large number of genes by horizontal gene transfer (HGT) across different kingdoms. However, in depth-studies on the physiological traits conferred by these accidental DNA acquisitions are largely lacking. Here we elucidate the functional role of Sl gasmin, a gene of a symbiotic virus of a parasitic wasp that has been transferred to an ancestor of the moth species Spodoptera littoralis and domesticated. This gene is highly expressed in circulating immune cells (haemocytes) of larval stages, where its transcription is rapidly boosted by injection of microorganisms into the body cavity. RNAi silencing of Sl gasmin generates a phenotype characterized by a precocious suppression of phagocytic activity by haemocytes, which is rescued when these immune cells are incubated in plasma samples of control larvae, containing high levels of the encoded protein. Proteomic analysis demonstrates that the protein Sl gasmin is released by haemocytes into the haemolymph, where it opsonizes the invading bacteria to promote their phagocytosis, both in vitro and in vivo. Our results show that important physiological traits do not necessarily originate from evolution of pre-existing genes, but can be acquired by HGT events, through unique pathways of symbiotic evolution. These findings indicate that insects can paradoxically acquire selective advantages with the help of their natural enemies

Lesioni non palpabili della mammella: la Mammotome-biopsy nella gestione preoperatoria del cancro della mammella

Premessa: Il tumore del seno è nei paesi occidentali al primo posto per frequenza nelle donne e la sua incidenza è in costante crescita. Grazie soprattutto alla diffusione dello screening mammografico e ad una maggiore consapevolezza del problema, negli ultimi anni è aumentata la diagnosi delle cosiddette lesioni “non palpabili”; parimenti si è assistito ad un importante sviluppo delle metodiche diagnostiche di tipo mininvasivo. Alla tradizionale citologia con ago sottile si sono affiancate infatti varie procedure bioptiche percutanee; tali metodiche microistologiche hanno quasi del tutto sostituito la biopsia chirurgica escissionale e l’esame intra-operatorio al congelatore. Pazienti e metodo: Nella nostra Divisione di Chirurgia Generale, Vascolare e Mininvasiva, dal dicembre 1999 al settembre 2004 abbiamo eseguito, in collaborazione con il servizio di Radiologia, 214 biopsie su guida ecografia utilizzando la vacuum-assisted biopsy (Mammotome® ) con ago 11-Gauge. I risultati ottenuti per ciò che concerne l’accuratezza diagnostica, la quantità e qualità delle informazioni ottenute, il significato delle stesse nella eventuale gestione chirurgica, il discomfort globale per la paziente sono stati analizzati e discussi nel presente lavoro. Risultati: Delle 214 biopsie eseguite con tecnica Mammotome, nell’89,3% dei casi si è trattato di lesioni clinicamente non palpabili, con un diametro medio di 8 mm. L’età media delle pazienti era di 57,6 anni (range 31-88). La positività per patologia maligna è stata di 90 casi (42%). Nei casi di iperplasia duttale atipica e radial scar (6%) è stata effettuata l’exeresi chirurgica della lesione che ha confermato nel 100% dei casi la precedente diagnosi bioptica. Il 19% delle pazienti sottoposte a biopsia Mammotome era stato precedentemente sottoposto ad un prelievo citologico con ago sottile. Confrontando i risultati delle due metodiche, l’attendibilità diagnostica della seconda risulta essere significativamente superiore (p<0,05) come pure il numero di informazioni ottenute (istotipo, invasività, grading, recettori ormonali, etc.); il discomfort legato alla procedura, valutato in termini di dolore (VAS), è risultato inferiore a quello del prelievo con ago sottile (p<0,05). L’unica complicanza della biopsia Mammotome è rappresentata dall’ematoma nella sede del prelievo (8% dei casi). Il numero dei falsi negativi è stato di un caso, dovuto ad un non corretto centraggio del bersaglio. Conclusioni: Allo stato attuale in presenza di una lesione non palpabile della mammella la scelta della metodica diagnostica (agobiopsia o Mammotome) è legata al sospetto radiologico nella prospettiva di un eventuale intervento chirurgico. La biopsia con Mammotome nelle lesioni non palpabil

Prev Chronic Dis

IntroductionCount data are often collected in chronic disease research, and sometimes these data have a skewed distribution. The number of unhealthy days reported in the Behavioral Risk Factor Surveillance System (BRFSS) is an example of such data: most respondents report zero days. Studies have either categorized the Healthy Days measure or used linear regression models. We used alternative regression models for these count data and examined the effect on statistical inference.MethodsUsing responses from participants aged 35 years or older from 12 states that included a homeownership question in their 2009 BRFSS, we compared 5 multivariate regression models \u2014 logistic, linear, Poisson, negative binomial, and zero-inflated negative binomial \u2014 with respect to 1) how well the modeled data fit the observed data and 2) how model selections affect inferences.ResultsMost respondents (66.8%) reported zero mentally unhealthy days. The distribution was highly skewed (variance = 58.7, mean = 3.3 d). Zero-inflated negative binomial regression provided the best-fitting model, followed by negative binomial regression. A significant independent association between homeownership and number of mentally unhealthy days was not found in the logistic, linear, or Poisson regression model but was found in the negative binomial model. The zero-inflated negative binomial model showed that homeowners were 24% more likely than nonowners to have excess zero mentally unhealthy days (adjusted odds ratio, 1.24; 95% confidence interval, 1.08\u20131.43), but it did not show an association between homeownership and the number of unhealthy days.ConclusionOur comparison of regression models indicates the importance of examining data distribution and selecting models with appropriate assumptions. Otherwise, statistical inferences might be misleading.2014720

Host-parasitoid developmental interactions are modulated by venom components of Aphidius ervi (Hymenoptera, Braconidae)

Aphidius ervi regulates physiology and reproduction of the pea aphid, to enhance its nutritional suitability for the developing offspring. Here we investigated the functional role of the main components of A. ervi venom, Ae-γ-glutamyl transpeptidases (Ae-γ-GTs), using RNA interference. The suppression of Ae-γ-GTs was obtained through microinjection of dsRNA solution in A. ervi female pupae, and their relative expression was checked by qRT-PCR. Parasitism by knocked down females induced a significant increase of aphid size and bacterial load of the primary aphid’s symbiont Buchnera aphidicola. Similarly, both A. ervi larvae and teratocytes showed a significant increase in size. The silencing of Ae-γ-GTs significantly reduced the host castration which resulted similar to that induced by wild type parasitoid females. Parasitoid adults were of larger size, but this trait was associated with a reduced survival and fecundity, suggesting a trade-off of the body size increase. These results shed light on the role of venom in the intricate network of interactions among the parasitoid, the host aphid and its symbiont, which finely orchestrate the development of parasitoid’s offspring

Impact of Deformed Wing Virus infection on honey bee gut microbiota

Honey bee health decline represents a problem of global importance for the remarkable impact of these pollinators on the environment and human economy. The reduced bee survival is the final result of a multifactorial syndrome triggered by several stress factors, that may synergistically interact, inducing a reduction of bee immunocompetence. A common element to all collapsing colonies is the high loads of parasites and associated pathogens, such as Deformed Wing Virus (DVW). DWV is an endemic immunosuppressive virus that generates asymptomatic covert infections, kept in check by the bees' immune system when not exposed to stress agents which weaken antiviral barriers. Here we focus on the role that DWV viral infections can have on the modulation of honey bee microbiota. We compared microbiota composition of bees with low and high DWV levels, pointing out the occurrence of a gut dysbiosis in highly infected bees, which are characterized by a reduced level of Lactobacillus species. The comprehension of DWV effect on microbiota will likely allow to define blends of probiotic microorganisms which may help to rescue the decay of honey bee immune competence