Expression profiles of astakine-like transcripts in the tarnished plant bug, Lygus lineolaris, exposed to fungal spores of Beauveria bassiana.

Astakines are hematopoietic cytokines originally isolated from crustaceans. We identified three astakine-like transcripts in the tarnished plant bug (Lygus lineolaris), LlAst-1, LlAst-2 and LlAst-3, containing prokineticin domains. Quantitative real-time PCR showed variation in expression patterns of astakines in different tissues and between sexes. Relative expression levels of LlAst-1 were highest in the fat bodies of females, while LlAst-2 expression was highest in the fat bodies of both males and females. LlAst-3 expression was higher in male legs compared with the female legs, but lower in all other tissues. Infection with the entomopathogenic fungus Beauveria bassiana slightly elevated LlAst-1 expression 48 h after infection in both males and females. In contrast, the expression levels of LlAst-2 and LlAst-3 were not significantly changed in males and females. Compared with 12:00 h, LlAst-1 level was higher in both sexes at 18:00 h and 00:00 h (midnight). By 6:00 h, the LlAst-1 level in females was significantly reduced while that in males remained high. LlAst-2 and -3 had highest relative expression levels in females at midnight but were significantly lower than in males at midnight and in both sexes at 18:00 h and 6:00 h. This is the first report of expression of astakine-like cytokines from insects.

Preemption of local smoke-free air ordinances: the implications of judicial opinions for meeting national health objectives.

Elimination of state laws that preempt local antismoking ordinances is a national health objective. However, the tobacco industry and its supporters have continued to pursue state-level preemption of local tobacco control ordinances as part of an apparent strategy to avoid the diffusion of grassroots antismoking initiatives. And, an increasing number of challenges to local ordinances by the tobacco industry and persons supported by the tobacco industry are being decided in state supreme courts and courts of appeals. The outcomes of seemingly similar cases about the validity of local smoke-free air ordinances vary significantly by state. This paper examines the common and unique aspects of the decisions and the potential implications of court rulings on preemption for future state tobacco control efforts and achievement of national health objectives around the elimination of preemption. Using a search strategy developed for the Centers for Disease Control and Prevention's State Tobacco Activities Tracking and Evaluation (STATE) System, cases where a state or federal appellate level court made a finding on the validity of a local smoke-free air ordinance or regulation were identified in 19 states. In contrast to previous studies, we found that cases in approximately half of states were decided for local governments. We also found that across the states, courts were considering similar factors in their decisions including the extent to which: (1) the local government possessed the authority to pass the ordinance, (2) the ordinance conflicted with the state constitution, and (3) state statutes preempt the ordinance.

Parasitism-linked block of host plasma melanization.

When parasitized by the Ichneumonid parasitoid Campoletis sonorensis, larvae of the Noctuid moth, Heliothis virescens, are unable to mount an effective immune response against parasitoid eggs. Defensive melanization of plasma and cellular encapsulation of parasite eggs are dramatically inhibited by infection with the symbiotic immunosuppressive C. sonorensis ichnovirus (CsIV). This study demonstrates that the CsIV-mediated inhibition of melanization is associated with reduction in the enzymatic activity and protein titer of key enzymes in the melanization pathway, phenoloxidase, dopachrome isomerase, and DOPA decarboxylase. Inhibition of the synthesis of key melanization enzymes leads to reductions in the melanization substrates l-dihydroxyphenylalanine, N-acetyldopamine, and N-beta-alanyl dopamine from millimolar to nanomolar levels in parasitized larvae. By contrast, concentration of a precursor catecholamine, dopamine, rises fourfold in these larvae. Thus in CsIV-infected larvae, enzymatic deficiencies in the melanization pathway lead to reduced concentrations of specific enzyme substrates, causing failure of melanization in parasitized insects.

Polydnavirus-mediated suppression of insect immunity.

Polydnaviruses are symbiotic proviruses of some ichneumonid and braconid wasps that modify the physiology, growth and development of host lepidopteran larvae. Polydnavirus infection targets neuroendocrine and immune systems, altering behavior, stunting growth, and immobilizing immune responses to wasp eggs and larvae. Polydnavirus-mediated disruption of cellular and humoral immunity renders parasitized lepidopteran larvae suitable for development of wasp larvae as well as more susceptible to opportunistic infections. Evidence from the Campoletis sonorensis polydnavirus system indicates that the unique genomic organization of polydnaviruses may have evolved to amplify the synthesis of immunosuppressive viral proteins. Immunosuppressive viruses have been essential to elucidating vertebrate immunity. Polydnaviruses have similar potential to clarify insect immune responses and may also provide novel insights into the role of insect immunity in shaping polydnavirus genomes.

Polydnavirus-mediated inhibition of lysozyme gene expression and the antibacterial response.

Parasitism of lepidopteran host larvae by hymenopteran parasitoids impairs the cellular immune response via expression of polydnavirus genes. Encapsulation of parasitoid eggs is thereby prevented. Parasitized insects are susceptible to opportunistic infections, suggesting that additional components of the immune system are affected. Insects normally respond to infection by inducing the synthesis of an array of antibacterial factors, including cecropins and lysozyme via a NFkappaB/lkappaB-like signal transduction pathway. To characterize the effects of PDVs on the antibacterial immune response, plasma antibacterial activities were assayed in H. virescens larvae infected with the C. sonorensis PDV. Plasma lysozyme activity in Heliothis virescens was reduced in parasitized and PDV-infected larvae after immune challenge. To examine the regulation of lysozyme after CsPDV injection, the Heliothis virescens lysozyme cDNA was cloned. In contrast to plasma lysozyme activity, the 1.1 kb lysozyme mRNA was induced in fat body and haemocytes by known elicitors. The data suggest that CsPDV, like some other viruses, regulates host cell gene expression at the level of translation. We propose that the immunodeficiencies caused by CsPDV injection are caused, in part, by the targeted translational inhibition of specific humoral immune response transcripts.

Polydnavirus infection inhibits translation of specific growth-associated host proteins.

The wasp Campoletis sonorensis injects a polydnavirus (CsPDV) along with its egg during parasitization of Heliothis virescens larvae. CsPDV protects the wasp egg and larvae by selectively disabling the host's cellular immune response, and by altering host physiology, growth, and development. Among the changes in host physiology brought about by CsPDV infection is a rapid, and specific decline in the translation of fat body mRNAs encoding selected major plasma proteins. Translational inhibition of the synthesis of all storage protein monomers, p82 (Riboflavin binding hexamer), and p74/p76 (arylphorin), occurs upon infection with CsPDV. Moreover, the prewandering peak of the plasma enzyme juvenile hormone esterase (JHE) was blocked by CsPDV injection. Northern blotting of fat body mRNA demonstrated that transcript levels of storage proteins were not affected by infection. Plasma titers of the iron binding proteins transferrin (p72) and ferritin (p24/26), and of the plasma juvenile hormone binding protein (p25) were not changed by CsPDV infection. That storage protein and JHE synthesis are translationally suppressed, while the synthesis of other plasma proteins continues apace, suggests that CsPDV infection may lead to translational discrimination among available mRNAs in CsPDV infected fat bodies. The effect of this translational discrimination is to shunt host resources away from larval growth and adult development, which presumably makes them available to the developing endoparasitoid.

Polydnavirus infection inhibits synthesis of an insect plasma protein, arylphorin.

The wasp Campoletis sonorensis injects a segmented, double-stranded DNA polydnavirus (CsPDV) along with its egg during parasitization of Heliothis virescens larvae. After parasitization, CsPDV protects the wasp egg and larva by selectively disabling the host's cellular immune response. Other host physiological systems including growth and development are affected to the apparent benefit of the parasite. To begin the characterization of the biochemical effects and mode of action of CsPDV on host growth, the titre of a developmentally regulated insect storage protein, arylphorin, was studied. Parasitized or virus-infected insects had substantially less circulating arylphorin than control insects. Fat bodies from parasitized larvae also synthesized less arylphorin in vitro. However, Northern blots of total RNA from parasitized and non-parasitized, control insects showed that the arylphorin transcript level was unaffected by parasitization suggesting a biochemical block at the translational level. In vitro translation followed by immunoprecipitation of arylphorin indicated that the mRNA was present and translatable at equal levels in both parasitized and control insects. Injection of purified virus elicited the response observed in naturally parasitized larvae, demonstrating that the effect on arylphorin synthesis is mediated, either directly or indirectly, by polydnavirus gene product(s).

Protein phosphorylation and control of tick salivary gland function.

Tick salivary glands are controlled by nerves, dopamine being a neurotransmitter at the neuroeffector junction. Dopamine and cyclic AMP (cAMP) stimulate fluid secretion by isolated salivary glands. Dopamine activates an adenylate cyclase to increase intracellular cAMP within the female salivary glands. Phosphoproteins whose levels of phosphate are affected by cAMP-dependent protein kinase have been identified in subcellular fractions. Protein(s) phosphorylated by cAMP appears to activate protein phosphatase in the salivary glands. Another phosphorylation pathway appears to act through protein kinase C because of an ability of phorbol esters (known activators of protein kinase C) to stimulate the phosphorylation of proteins, and an ability of a peptide factor in tick brain to metabolize salivary-gland phosphoinositides, an event that often precedes activation of protein kinase C. Because cAMP modulates brain-factor-stimulated formation of inositol phosphates (products of phosphoinositide breakdown) an interrelationship between the two pathways seems likely. Evidence of regulatory processes, including protein phosphorylation/dephosphorylation reactions, will provide a basis for helping assess the physiological significance of secretory products and the role of the salivary glands in disease transmission.