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Distribuzione spaziale e piani di campionamento di due specie afidiche dell'erba medica: Acyrthosiphon pisum (Harris) e Therioaphis trifolii f. maculata (Monell) (Homoptera, Aphidoidea)
No full textThe interplay between inflammation and neural plasticity determines serotoninergic antidepressant efficacy
Full text linkMajor Depressive Disorder (MDD) is a multifaceted disorder that imposes an enormous medical, societal and economic burden. Selective Serotonin Reuptake Inhibitors (SSRIs) are the most commonly prescribed antidepressant drugs. However, their efficacy is variable and incomplete and there is still limited understanding of the factors determining their beneficial action. With the purpose to identify these factors and develop more effective therapeutic strategies for MDD, we carried out preclinical studies exploiting a multidisciplinary strategy, spanning from molecular to cellular and behavioral assessment. We focused on inflammation and neural plasticity because, though these have been widely reported as key factors in determining SSRI outcome, their interplay has been limitedly explored. The results obtained show, on the one hand, that the increased neural plasticity induced by SSRI administration regulates inflammation counterbalancing both the activation and suppression of immune response, and, on the other, that any deviation towards an extreme immune activation or suppression results in reduced neural plasticity. These findings indicate that neural plasticity and inflammation are mutually regulating processes and that inflammatory levels should be kept within a strict physiological range to be permissive for neural plasticity. As further step, we explored a polypharmacological strategy aimed at increasing SSRI efficacy through the add-on treatment with metformin, a drug able to improve metabolic profile, which has been shown to be implicated in antidepressant efficacy. This approach is aimed at producing two concerted effects –increasing neural plasticity (i.e. SSRI) and regulating metabolism (i.e. metformin)—that together should lead to a more effective therapeutic strategy for MDD than the SSRI alone. The results suggest that the combined treatment has an improved efficacy and that multifactorial disorders such as MDD may be more effectively treated with strategies able to targeting several biological processes. Overall, our findings underpin the implementation of the precision medicine paradigm in the psychiatric field. Indeed, information concerning not only the patients’ mood but also selected physiological endpoints (e.g. inflammatory levels and metabolic profile) should be considered for an effective antidepressant therapeutic strategy
Host regulation effect of ovary fluid and venom of Aphidius ervi Haliday (Hymenoptera: Braconidae)
No full textThe host regulation effects of venom and ovary fluid of the endophagous braconid Aphidius ervi Haliday on the pea aphid, Acyrthosiphon pisum (Harris), have been studied. Extracts of ovaries and of venom glands were injected into nonparasitized 4th instar pea aphids. both separately and mixed. Aphids treated with parasitoid material died as 4th instars, often showing developmental arrest. In contrast, control aphids that received an injection of Pringle's saline solution regularly moulted to the adult stage and reproduced. Venom alone was as effective as the combined extracts in determining developmental arrest and death. Separate heat and protease treatments of these parasitoid's reproductive secretions significantly reduced their biological activity, suggesting that the active component(s) involved is a protein(s). SDS-PAGE analysis of haemolymph samples obtained from pea aphids which had received an injection of combined venom and ovary extract revealed an increase of the titre of various proteins, particularly in the 43-47 kDa interval, as registered for truly parasitized hosts. This altered protein profile was first detected 48 h following injection. Based on this information a tentative physiological model is proposed. The apical tract of host ovarioles, where the germarium and growing oocytes are located, is suggested to be one of the major targets of female parasitoid secretions injected with the egg. (C) 1998 Elsevier Science Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Growth and Development of Cardiochiles-nigriceps Viereck (hymenoptera, Braconidae) Larvae and Their Synchronization With Some Changes of the Hemolymph Composition of Their Host, Heliothis-virescens (f) (lepidoptera, Noctuidae)
No full textLarval development of the parasitoid Cardiochiles nigriceps Viereck occurs in the last instar larva of its host, Heliothis virescens (F.). This allows the parasitoid to exploit the nutritional increase in the biosynthetic activity occurring in the host in preparation for metamorphosis. To understand the biochemical basis of this host parasitoid developmental synchrony, we undertook host ligation studies and analyzed host hemolymph for proteins and glycerol esters. Parasitization affected the biochemical profile of the host. The hemolymph protein concentration of parasitized last instar H. virescens larvae increased through time, whereas unparasitized (control) larvae were characterized by a decrease in the protein titer when they reached the prepupal stage. The effect of parasitism on glyceride titers of host hemolymph was not as pronounced as the effect on proteins. Ligation conducted on 5th instar hosts, which were parasitized as 4th instars, affected parasitoid development in a time-dependent way. The percentage of successfully developing C. nigriceps larvae increased with the increase of the time interval between parasitization and ligation. Ligation performed before day 2 of the 5th larval instar of H. virescens completely inhibited parasitoid development. Ligations that disrupted parasitoid development were associated with a low host hemolymph protein concentration. Parasitoid development was successful when hemolymph protein titer was high, as occurred when ligations were performed after day 3 of the 5th host instar in both control and parasitized larvae. Ligations in both situations resulted in a slight increase in glyceride titers. The results suggest that host proteins and/or some factor(s) associated with them may play a role in parasitoid growth and development. (C) 1993 Wiley-Liss, Inc
Flight Behavior of the Aphid Parasitoid Aphidius-ervi (hymenoptera, Braconidae) In Response To Plant and Host Volatiles
No full textThe flight behaviour of the aphid parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) has been studied in a wind tunnel, in response to the following natural odour sources: broad bean plants infested with Acyrthosiphon pisum (Harris) (Homoptera: Aphididae) (PHC, plant-host complex), damaged broad bean plants from which the aphids were removed (HDP, host damaged plants), aphids (H, host) and uninfested broad bean plants (P, plant). The most attractive odour sources were PHC and HDP, which both stimulated a similar high number of oriented straight flights. In contrast, H and P were much less attractive and did not seem to be important in the long range attraction of the parasitoids
Effect of adult experience on in-flight orientation to plant and plant-host complex volatiles in Aphidius ervi Haliday (Hymenoptera, Braconidae)
No full textThe effect of adult experience on in-flight orientation to plant-host complex volatiles by Aphidius ervi Haliday was studied in a wind tunnel bioassay, using Acyrthosiphon pisum (Harris), maintained on broad bean plants (Vicia faba) as host. A short oviposition experience (15 s) on the plant-host complex (PHC) was sufficient to induce a drastic decrease of flight propensity and stimulated a foraging behavior characterized by intense walking activity, However, flight activity resumed to normal levels 1 h after the oviposition experience on the PHC occurred. For parasitoids conditioned on the PHC for at least 1 min the recorded proportion making oriented flights to the PHC was significantly higher than that for naive females, In contrast, oviposition experience in the absence of plant material did not influence the A. ervi flight response, Oviposition attempts on aphid dummies without egg release did not reduce flight activity. When A. ervi females were exposed to glass beads coated with Ac. pisum cornicle secretion, a priming effect was observed, resulting, compared with naive females, in a significantly higher rate of oriented flights to the PHC. In contrast, oviposition attempts visually induced by colored aphid dummies did not influence flight behavior. A strong reaction to volatile cues from uninfested plants was induced by oviposition experience on newly infested broad bean plants, This appears to be a case of associative learning. In fact, uninfested broad bean plants are basically unattractive to naive A. ervi females. The results demonstrate that adult experience has a considerable influence on A. ervi behavior and may have important implications for biological control of natural pest aphid populations. (C) 1997 Academic Press
Preliminary-results On Invitro Rearing of the Endoparasitoid Cardiochiles-nigriceps From Egg To 2nd Instar
No full textThe composition of an artificial medium and technical procedures used for in vitro rearing of the endophagous larval parasitoid Cardiochiles nigriceps Viereck (Hymenoptera, Braconidae), from post-germ band egg to the 2nd instar larva, are described. Amino acids, carbohydrates, salts, and vitamins were supplied in defined amounts as an aqueous solution which, when supplemented with 20 mg/ml of bovine albumin, 5 mg/ml of lactalbumin (enzymatic hydrolysate), 20 % (v/v) fetal bovine serum, 20 % (v/v) milk and 10% (v/v) chicken egg yolk, allowed for parasitoid growth and molting to the 2nd instar. Molting to the final instar was never observed
Host regulation by the aphid parasitoid Aphidius ervi: the role of teratocytes
No full textThe biochemical profile and metabolism of Acyrthosiphon pisum (Harris) (Homoptera, Aphididae) are markedly altered and redirected in response to parasitization by the endophagous braconid Aphidius ervi Haliday (Hymenoptera, Braconidae). In the present study, the role played in the host regulation process by teratocytes, cells deriving from the dissociation of the embryonic membrane of the parasitoid, is taken into consideration. The protein synthesis activity of these cells of embryonic origin is analysed in vitro and an essential characterization of those proteins de novo synthesized and released in the incubation medium is provided. Teratocytes, obtained by dissecting parasitized host aphids, 3, 4 and 5 days after parasitoid oviposition, were incubated in vitro and, at the end of the incubation period, were separated from the medium for SDS-PAGE analysis of both cellular and secreted proteins. Various cellular proteins were more abundant as the time between parasitization and teratocyte collection increased. Furthermore, two proteins, showing an approximate molecular mass of 15 kD (p15) and 45 kD (p45) respectively, were abundantly secreted in the incubation medium by 5 day-old teratocytes. Incubations in presence of S-35 radiolabelled amino acids indicated that p15 and p45 are both synthesized by A. ervi teratocytes. The amino acid composition of these two proteins was similar to that reported for other insect proteins with a demonstrated nutritional function. The p45 protein was found to be glycosylated. A tentative physiological model describing the host regulation role played by different parasitoid-derived factors is proposed
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