After parasitization, some wasps induce hosts prematurely to initiate metamorphic development that is then suspended in a postwandering, prepupal state. Following egression of the parasite larva, the host remains in this developmentally arrested state until death. Teratocytes, cells released at egg hatch from extra-embryonic serosal membranes of some wasp parasites, inhibit growth and development when injected into host larvae independent of other parasite factors (e.g. venom, polydnavirus). Synthesis of some developmentally regulated, abundantly expressed Heliothis virescens host proteins is inhibited in hosts parasitized by Microplitis croceipes and by teratocyte injection. A cDNA encoding a 13.9 kDa protein (TSP14) that inhibited protein synthesis, growth and development was isolated from a protein fraction secreted by teratocytes. TSP14 appears to be responsible, in part, for the teratocyte-mediated inhibition of host growth and development. Interestingly, this cDNA encoded a cysteine-rich amino acid motif similar to that described from Campoletis sonorensis polydnavirus, a mutualistic virus that enables wasp parasitization of lepidopteran larvae. Moreover, TSP14 inhibited protein synthesis in a dose-dependent manner in rabbit reticulocyte lysate and wheat germ extract translation systems. We hypothesize that some wasp parasites inhibit translation as a general means to regulate and redirect lepidopteran host physiology to support endoparasite development.

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We report on a phospholipase A 2 (PLA 2 ) found in the oral secretions, but not midgut contents, of the burying beetle, Nicrophorus marginatus. PLA 2 is responsible for hydrolyzing fatty acids from the sn-2 position of dietary phospholipids (PLs), an essential step in digestion and absorption of essential polyunsaturated fatty acids. Like the digestive PLA 2 s known from mammalian systems, and the one described insect digestive PLA 2 the N. marginatus oral secretion PLA 2 depends upon Ca 2+ for full activity. However, unlike most digestive PLA 2 s, the N. marginatus enzyme is only partially inactivated in the absence of Ca 2+ . The PLA 2 in N. marginatus oral secretions was influenced by altering the enzyme reaction conditions, including reaction time, protein concentration, pH, and temperature. Standard reaction conditions for assessing enzyme activity include 1.0 μg protein/μl incubated at pH 9.0 for 30 min at 28°C.

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UL34 encodes the transcriptional repressor of the human cytomegalovirus immune evasion gene, US3, and is essential for viral replication in tissue culture. Two different monocistronic transcripts originate from UL34 at early and late times postinfection and encode two predominant proteins and a third, minor protein. The UL34 proteins are differentially expressed throughout the viral replication cycle, with both proteins localizing to the nucleus and repressing expression of the US3 gene.

SummaryWe have isolated a teratocyte secretory protein (TSP14) gene product from a hymenopteran endoparasite that disrupts the growth of lepidopteran insect larvae. To evaluate the insecticidal activity of TSP14 for the protection of crops from insect damage, chimeric gene constructs of TSP14 were expressed in transgenic plants. The coding sequence of the TSP14 gene, with and without its native signal peptide, was placed between the modified peanut chlorotic streak virus (PClSV) full-length transcript (FLt) promoter with duplicated enhancer domains and the terminator sequence from the rbcSE9 gene. These chimeric genes, expressed in transgenic tobacco (Nicotiana tabacum cv. Samsun NN) were stably inherited in successive plant generations (R 0 , R 1 and R 2 progeny) as shown by molecular analysis.A Western blot analysis of plant extracts showed the presence of a polypeptide of the expected size that cross-reacted with TSP14-specific antibodies. Larvae of the tobacco budworm (Heliothis virescens) and tobacco hornworm (Manduca sexta) which were fed with several independent homozygous transgenic plant lines (R 2 progeny) exhibited mortality and reduced growth rates compared to those fed with plants transformed by a vector control. Our results demonstrate the potential for introduction of the TSP14 gene into plants in order to achieve protection against lepidopteran pests.

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