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The importance of host regulation to insect parasitoids.
Abstracts / Comparative Biochemistry and Physiology, Part B 126 (2000) S1-S108
THE IMPORTANCE OF HOST REGULATION TO INSECT PARASITOIDS. S. Bradleigh Vinson*, Francesco Pennacchio**, and Fernando L. Consoli* *Texas A&M University, College Station, TX (USA); **Universith della Basilicata, Potenza (Italy)
The regulation o f the physiology and behavior o f host insects by their habitual parasitoids is well established. Initially, regulation occurs through the injection o f materials into the host by the ovipositing female, but later may involve the release o f substances by the egg, larvae or associated cellular elements (teratocytes). The materials released range from venoms consisting o f simple biochemieals to complex proteins and enzymes to venoms consisting o f DNA sequences in the form o f the polydnaviruses. Likewise, the functions o f these materials and the physiological systems they effect within the host vary. These effects range from the alteration o f the phenyloxidase cascade, impacting the immune system o f the host, altering the uptake and storage or release o f nutrients from select tissues; to altering the neuro-endoerine system in ways that alters the subsequent growth and development o f the host. These endocrine effects appear to differ among the different interacting species ofparasitoid-host. But are there some common effects on the physiology o f the host that are the result o f these regulatory factors? We will look at this question by examining some o f the evolutionary challenges faced by parasitoids and examine the roles that these regulatory factors have played in allowing the parasitoids to meet these ehaUenges. These issues will be discussed through a biased look at two ectoparasitoids and three endoparasitoids focusing on the endocrine system o f the host and the nutritional needs o f the 5 species.
E F F E C T O F S U L F I D E ON E R Y T H R O C Y T E K ÷ F L U X P A T H W A Y S IN C R U C I A N C A R P AND R A I N B O W T R O U T S. V61kel I, M. Berenbrink 1, N. Heisler 1 and M. Nikinmaa 2 t Animal Physiology, Humboldt University, D-10115 Berlin, Germany 2 Department o f Biology, University of Turku, Turku, Finland Sulfide is extremely toxic for most fish species, eliciting its acute and lethal effects mainly on the basis of cytochrome coxidase inhibition [1]. In addition, red blood cell (RBC) functions may also be severely affected by sulfide entrance through the respiratory epithelia, e. g. by enzyme inhibition in bovine RBCs [2], or by impairment of oxygen transport on the basis of sulfhaemoglobin formation as in trout RBCs [3]. The present study was focused on the effect of sulfide on transmembrane K+flux in RBCs of sulfide-sensitiverainbow trout (Oncorhynchusraykiss)and sulfide-tolerantcrucian carp (Carassius carassius). In 1rout, the ouabain-sensitiveK~ influx was significantly reduced by 40 ~tmol1"~sulfide in the pH range 6.7 to 8.3. Maximal inhibition of Na÷, K+-ATPase (32 %) occurred at sulfide concentrations as low as 10 panol 11. Ouabain-resistant K÷ influx was minimal at pH values between 6.7 and 7.7 (independent of sulfide), the rising flux observed at higher pH became sensitive to 30 ~u,aol1-~sulfide (15 % inhibition). In contrast to trout, crucian carp erythrocytes were apparently insensitive to sulfide, with neither the ouabain-resistant nor the ouabaln-sensitive K÷ influx being affected by sulfide concentrations of up to 850 ~m~ol1-~. The extraordinary resistance ofK÷transport in crucian carp RBCs may contribute to the extremely high sulfide-tolerance of this species. [I] Nicholls,P. (1975) Biochim. Biophys. Acta 396: 24-35. [2] Khan, A.A. et al.(1987) Toxicol.Environm. Health 22: 481-490. [3] VSlkel, S.,Berenbrink, M. (2000) L exp. Biol.203: 1047-1058.
Supported by Deutscher Akademischer Austauschdienst (DAAD) and Academy of Finland
$99
THE IMPORTANCE OF HOST REGULATION TO INSECT PARASITOIDS. S. Bradleigh Vinson*, Francesco Pennacchio**, and Fernando L. Consoli* *Texas A&M University, College Station, TX (USA); **Universith della Basilicata, Potenza (Italy)
The regulation o f the physiology and behavior o f host insects by their habitual parasitoids is well established. Initially, regulation occurs through the injection o f materials into the host by the ovipositing female, but later may involve the release o f substances by the egg, larvae or associated cellular elements (teratocytes). The materials released range from venoms consisting o f simple biochemieals to complex proteins and enzymes to venoms consisting o f DNA sequences in the form o f the polydnaviruses. Likewise, the functions o f these materials and the physiological systems they effect within the host vary. These effects range from the alteration o f the phenyloxidase cascade, impacting the immune system o f the host, altering the uptake and storage or release o f nutrients from select tissues; to altering the neuro-endoerine system in ways that alters the subsequent growth and development o f the host. These endocrine effects appear to differ among the different interacting species ofparasitoid-host. But are there some common effects on the physiology o f the host that are the result o f these regulatory factors? We will look at this question by examining some o f the evolutionary challenges faced by parasitoids and examine the roles that these regulatory factors have played in allowing the parasitoids to meet these ehaUenges. These issues will be discussed through a biased look at two ectoparasitoids and three endoparasitoids focusing on the endocrine system o f the host and the nutritional needs o f the 5 species.
E F F E C T O F S U L F I D E ON E R Y T H R O C Y T E K ÷ F L U X P A T H W A Y S IN C R U C I A N C A R P AND R A I N B O W T R O U T S. V61kel I, M. Berenbrink 1, N. Heisler 1 and M. Nikinmaa 2 t Animal Physiology, Humboldt University, D-10115 Berlin, Germany 2 Department o f Biology, University of Turku, Turku, Finland Sulfide is extremely toxic for most fish species, eliciting its acute and lethal effects mainly on the basis of cytochrome coxidase inhibition [1]. In addition, red blood cell (RBC) functions may also be severely affected by sulfide entrance through the respiratory epithelia, e. g. by enzyme inhibition in bovine RBCs [2], or by impairment of oxygen transport on the basis of sulfhaemoglobin formation as in trout RBCs [3]. The present study was focused on the effect of sulfide on transmembrane K+flux in RBCs of sulfide-sensitiverainbow trout (Oncorhynchusraykiss)and sulfide-tolerantcrucian carp (Carassius carassius). In 1rout, the ouabain-sensitiveK~ influx was significantly reduced by 40 ~tmol1"~sulfide in the pH range 6.7 to 8.3. Maximal inhibition of Na÷, K+-ATPase (32 %) occurred at sulfide concentrations as low as 10 panol 11. Ouabain-resistant K÷ influx was minimal at pH values between 6.7 and 7.7 (independent of sulfide), the rising flux observed at higher pH became sensitive to 30 ~u,aol1-~sulfide (15 % inhibition). In contrast to trout, crucian carp erythrocytes were apparently insensitive to sulfide, with neither the ouabain-resistant nor the ouabaln-sensitive K÷ influx being affected by sulfide concentrations of up to 850 ~m~ol1-~. The extraordinary resistance ofK÷transport in crucian carp RBCs may contribute to the extremely high sulfide-tolerance of this species. [I] Nicholls,P. (1975) Biochim. Biophys. Acta 396: 24-35. [2] Khan, A.A. et al.(1987) Toxicol.Environm. Health 22: 481-490. [3] VSlkel, S.,Berenbrink, M. (2000) L exp. Biol.203: 1047-1058.
Supported by Deutscher Akademischer Austauschdienst (DAAD) and Academy of Finland
$99