Expression and characterization of a recombinant Cry1Ac crystal protein with enhanced green fluorescent protein in acrystalliferous Bacillus thuringiensis

AIMS

To investigate fusion expression between Bacillus thuringiensis crystal protein and a foreign protein, the expression of a fusion protein comprised of Cry1Ac, and enhanced green fluorescent protein (EGFP) in B. thuringiensis Cry(-)B strain was examined.

METHODS AND RESULTS

The N-terminal fusion expression of EGFP in Cry1Ac was attempted under the control of the native cry1Ac promoter. The EGFP gene was cloned into pProMu and named pProMu-EGFP. The transformant, ProMu-EGFP/CB produced parasporal inclusions that were of bipyramidal-shaped crystals in size ranging from 200 to 300 nm. The fusion protein was approximately 150 kDa and identified by the immunoblot analysis using a Cry1Ac antibody and also a GFP antibody. The LC(50) of the ProMu-EGFP/CB was twofold higher when compared with that by the ProAc/CB. However, the crystal protein produced by the ProMu-EGFP/CB was effective on Plutella xylostella larvae.

CONCLUSIONS

The ProMu-EGFP/CB produced bipyramidal shaped and insecticidal crystals comprising fusion proteins.

SIGNIFICANCE AND IMPACT OF THE STUDY

Through the N-terminal fusion expression of EGFP and Cry1Ac, expression and crystallization between the B. thuringiensis crystal protein and a foreign protein were validated.

Right stereoisomers for sex pheromone components of the apple leafminer, Lyonetia prunifoliella, in Korea

The sex pheromone of the American population of Lyonetia prunifoliella (Lepidoptera: Lyonetiidae) was reported to be composed of three components, 10,14-dimethyloctadec-1-ene (10me14me-1-ene-18Hy), 5,9-dimethyloctadecane (5me9me-18Hy), and 5,9-dimethylheptadecane (5me9me-17Hy). Studies with a Korean population showed that the 10S, 14S isomer of the major compound was the major electrophysiologically by active stereoisomer. The 5S,9S isomers of the minar constituents also elicited electrophysiological responses. In field trappings, among the three components, the racemic mixture of 10me14me-1-ene-18Hy attracted L. prunifoliella males strongly, and the binary or tertiary combinations with racemic mixtures of the other two components did not increase trap catches. Among the four stereoisomers of 10me14me-1-ene-18Hy, only the 10S,14S isomer attracted L. prunifoliella males, as suggested by the EAG test, and attraction to the other three isomers was not observed. All stereoisomers of each minor component, as well as their racemic components, did not seem to have any additional effect on male attraction in Korea.

Isolation and characterization of a strain of Bacillus thuringiensis ssp. kurstaki containing a new delta-endotoxin gene

A strain of Bacillus thuringiensis that showed significantly high toxicity to Plutella xylostella and Spodoptera exigua was isolated from a Korean soil sample and characterized. The isolate, named B. thuringiensis K1, was determined to belong to ssp. kurstaki (H3a3b3c) type by an H antisera agglutination test and produced bipyramidal inclusions. Plasmid pattern of K1 was different from that of the reference strain, ssp. kurstaki HD-1, but the parasporal inclusion protein profile of K1 had two major bands that were similar in size to those of ssp. kurstaki HD-1. To verify the delta-endotoxin gene types of K1, PCR analysis with specific cry gene primers was performed to show that K1 contained a new cry gene in addition to cry1Aa, cry1Ab, cry1Ac, cry1E and cry2 genes. PCR-amplified region of the new cry gene, cryX, showed 79% similarity to cry1Fa1 gene (GenBank Accession No. M63897). In an insect toxicity assay, K1 had higher toxicity against Plutella xylostella and S. exigua than ssp. kurstaki HD-1.

Characterization of (1'R,4S,4aR,7S,7aR)-dihydronepetalactol as a semiochemical for lacewings, including Chrysopa spp. and Peyerimhoffina gracilis

The enantiomerically pure diastereoisomers (1R,4S,4aR,7S,7aR)- (1) and (1R,4R,4aR,7S,7aR)-dihydronepetalactol (2) were synthesized diastereoselectively from a renewable resource, (4aS,7S,7aR)-nepetalactone (3), isolated as the main constituent of the essential oil of the catmint plant Nepeta cataria. The stereochemistry of the compounds was determined by NMR spectroscopy and X-ray crystallography, and the compounds were identified, respectively, as neomatatabiol and isoneomatatabiol, natural products from Actinidia polygama, for which the lactol stereochemistry was previously incompletely defined. Compound 1 was found to catch significant numbers of three species of lacewing in the field: in Korea. Chrysopa cognata, and in the United Kingdom, Nineta vittata and most notably Peverimhoffina gracilis. All species caught in significant numbers were found more frequently in traps releasing 1 than 2, while more C. cognata, C. formosa, and C. phyllochroma were found in traps releasing (1R,4aS,7S,7aR)-nepetalactol (4). The catch of P. gracilis with 1 is of particular interest as this lacewing has only recently been recorded in the United Kingdom. Where sexed, the lacewings of all species trapped were found to be male, implying a possible pheromonal role for these or structurally related compounds.

Isolation and characterization of a Bacillus thuringiensis ssp. kurstaki strain toxic to Spodoptera exigua and Culex pipiens

A strain of Bacillus thuringiensis with dual toxicity was isolated from Korean soil samples and named K2. K2 was determined as ssp. kurstaki (H3a3b3c) by serological test and produced bipyramidal-shaped parasporal inclusions. The plasmid and protein profiles of B. thuringiensis K2 were different from those of the reference strain, ssp. kurstaki HD-1. To verify gene type of B. thuringiensis K2, PCR analysis with specific cry gene primers was performed. The result showed that B. thuringiensis K2 had cry1Aa, cry1Ab, cry1C, and cry1D type genes, whereas ssp. kurstaki HD-1 had cry1Aa, cry1Ab, cry1Ac, and cry2 type genes. In addition, B. thuringiensis K2 had high toxicity against Spodoptera exigua and Culex pipiens, whereas B. thuringiensis ssp. kurstaki HD-1 does not have high toxicity against these two insect species.

Structural polymorphism of the luciferase gene in the firefly, Luciola lateralis

To study the structural features of genes for luciferase in Luciola lateralis, two different, functional luciferase genes, Luc1 and Luc2, were cloned and their nucleotide sequences were determined. The two genes were nearly identical, but a deletion of 128 bp was found in the 5' upstream region of Luc2, and minor deletions and additions were also found in the 3' downstream region. Seven base substitutions in the coding region produced two amino acid residue differences between the two genes. Southern blot analysis of genomic DNA isolated from 33 individual fireflies revealed that 26 were homozygous for the Luc1 gene and one was homozygous for Luc2. The others were heterozygotes with two, or even three, different alleles for the luciferase gene.

Isolation and identification of the cDNA encoding the pheromone biosynthesis activating neuropeptide and additional neuropeptides in the oriental tobacco budworm, Helicoverpa assulta (Lepidoptera: Noctuidae)

The present study is concerned with cloning and characterizing Has-PBAN cDNA which is 756 nucleotides long, isolated from the brain and suboesophageal ganglion complex (Br-Sg) of Helicoverpa assulta adults. The 194-amino acid sequence deduced from this cDNA possessed the proteolytic endocleavage sites to generate multiple peptides. From the processing of the prepro-hormone, it can be predicted that the cDNA has a PBAN domain with 33 amino acids and four additional peptide domains: 24 amino acid-, 7 amino acid-, 18 amino acid- and 8 amino acid-long sequences, with FXPR (or K) L (X = G, T or S) amidated at their C-termini. The amino acid sequence of all five predicted peptides, including the PBAN, are identical to that of Helicoverpa zea (Raina, A.K., Jaffe, H., Kempe, T.G., Keim, P., Blacher, R.W., Fales, H.M., Riley, C.T., Klun, J.A., Ridgway, R.L., Hayes, D.K., 1989. Identification of a neuropeptide hormone that regulates sex pheromone production in female moths. Science 244, 796-798 and Ma, P.W.K., Knipple, D.C., Roelofs, W.L., 1994. Structural organization of the Helicoverpa zea gene encoding the precursor protein for pheromone biosynthesis-activating neuropeptide and other neuropeptides. Proc. Natl. Acad. Sci., U.S.A. 91, 506-510). A single mRNA species corresponding to the size of Has-PBAN cDNA was detected from the Br-Sg of 1-3-day old female and male adults, and their expression was also at a similar level. Pheromone production was induced upon injection of female or male Br-Sg extracts or synthetic PBAN into the haemocoel of decapitated 1-3-day old female adults during the photophase when they are not supposed to produce pheromone. From these results, H. assulta adult females seem to use their own PBAN for regulating sex pheromone biosynthesis. Functions of the four other peptides ending with FXPR (or K) L in the Has-PBAN cDNA and of the male PBAN remain to be elucidated.

Protein purification and cDNA cloning of a cecropin-like peptide from the larvae of fall webworm (Hyphantria cunea)

A proteinous antimicrobial substance was purified from the bacteria-challenged larvae of the fall webworm, Hyphantria cunea. It is a cecropin-like antibacterial peptide which exhibits antibacterial activity against Gram-negative and Gram-positive bacteria, and known as Hyphantria cecropin A. The cDNA clones corresponding to this peptide were isolated from a cDNA library constructed from the bacteria-challenged larvae and obtained complete nucleotide sequences. In addition to the Hyphantria cecropin A sequence, we obtained three other cDNAs exhibiting high sequence similarity with Hyphantria cecropin A. We synthesized the C-terminally amidated peptide of 35 residues based on the deduced sequence of the isolated cDNA of Hyphantria cecropin A. The synthetic peptide exhibited strong antibacterial activity against several microbes including medically important bacteria such as Salmonella, Shigella, and fungus such as Candida. A Southern blot experiment using these cloned cDNAs as probes predicted the existence of multiple forms of Hyphantria cecropin genes.

Johnston's organ of the black fly Simulium vittatum Zett

Ultrastructure of the Johnston's organ was similar in both sexes of the black fly Simulium vittatum. Three types of scolopidia were found: types A, B, and C. Type A and B scolopidia are amphinematic and type C scolopidia are mononematic. Males had slightly wider pedicels than females and bore about 30 type A, 150 type B, and 4 type C scolopidia. Females had about 20 type A, 105 type B, and 5 type C scolopidia. The basic structure and location of each type are similar to, although less well organized than, these types in the adult mosquito. The number of type A and B scolopidia, while much lower than that found in mosquitoes, is similar to the number in other insects. Each amphinematic scolopidium has either two (type A) or three (type B) sensory cells, as well as three sheath cells and a long cuticular cap. A mononematic type C scolopidium has two sensory cells, a sheath cell, a short cap, and a microtubular cap cell. The structure of the Johnston's organ complements previous behavioural observations indicating that sound detection is absent or minimal in the black fly, even in the mate-seeking males. The probable function of each scolopidial type is discussed as it may relate to flying and wind detection.

The quantitation of trypanosoma congolense in calves. III. A quantitative comparison of trypanosomes in jugular vein and microvasculature and tests of dispersing agents

Hemocytometer and cytofluorometric methods were used to count trypanosomes in the blood of neonatal and six-month-old calves infected with T. congolense. The correlation between these methods was highest in the six-month-old calves because their parasitemia was greater and the accuracy of cytofluorometric counting is reduced below 1,000 trypanosomes per microliter of blood. Fine needle aspiration biopsies showed many trypanosomes marginated in cerebral cortical capillaries, but few in muscle or liver. Quantitatively, the cerebral capillaries in the infected six-month-old calves were significantly wider than their controls with fewer endothelial nuclei suggesting capillary dilatation. There were fewer trypanosomes and no significant changes in capillary width in the neonatal calves. Several drugs were tried for activity in dispersing marginated trypanosomes into axial flow. Berenil and dexamethasone had a significant effect on trypanosome counts in blood and tissue whereas, epinephrine caused a fleeting increase in parasitemia. Hetastarch, dextran and cyclophosphamide had no specific effect. Fine needle aspiration bipsies of brain, thirty minutes after Berenil injection showed that the capillaries were cleared of trypanosomes.

Antennal sensory receptors of the male mosquito, Anopheles stephensi

It was shown by electron microscopy that antennae of male Anopheles stephensi have the same types of sensory receptors as the females, with sunken pegs (sensilla ampullacea and sensilla coeloconica), surface pegs (sensilla basiconica), hairs (sensilla trichodea), bristles and fibrillae (sensilla chaetica), and scolopidia in the Johnston's organ. Compared with the female, the male mosquito has fewer than half of the sensory cells in the flagellum, but many more in the Johnston's organ. The smaller number of flagellar sensory neurons in the male was due mainly to fewer sensory receptors of possibly olfactory types. Sensory cells of mechano- and thermoreceptors were present in almost identical numbers in both sexes, as only about 15% of the long fibrillae, abundant as whorls in the male mosquito, are innervated by a single neuron.

Fine structure of the antennal sensory hairs in female Anopheles stephensi

The fine structure of the sensory hairs on the antennal flagellum of female Anopheles stephensi was studied by electron microscopy. The antennal hairs were divided into at least five different types, on the basis of hair diameter, hair wall thickness, communicating channel density, and dendritic branching in the hair lumen. Regardless of different types, however, all hairs, presumed to be olfactory receptors, were found to be innervated by two sensory cells.

Fine structure of surface and sunken grooved pegs on the antenna of female Anopheles stephensi (Diptera: Culicidae)

The antenna of female Anopheles stephensi Liston bears three types of sensilla with grooved pegs: those sunken in pits and subtypes A and B of those located on the flagellar surface. The sunken peg sensilla are innervated by four or five neurons with branching dendrites. The dendrites are exposed to the exterior by means of longitudinal clefts at the bases of the grooves in the peg wall. Surrounding the dendrites and extending into the clefts is an extracellular material of medium electron density. Three sheath cells are associated with each sunken peg sensillum.Subtype-A surface peg sensilla are generally similar to the sunken peg sensilla, except that they are located on the antenna) surface and are innervated by two neurons with unbranched dendrites. Subtype-B surface peg sensilla have three or four neurons, the dendrites of which do not branch and are exposed less to the exterior than those in the other peg sensilla because the clefts in the peg wall are smaller and less frequent. Only trace amounts of electron-dense material occur in the clefts of the subtype-B surface peg sensilla.The sunken peg and both subtypes of the surface peg sensilla are probably olfactory receptors.

Fine structure of sunken thick-walled pegs (sensilla ampullacea and coeloconica) on the antennae of mosquitoes

Sensilla ampullacea (pegs in tubes), a type of sensillum heretofore unknown from mosquitoes, occur on the antennae of female Anopheles stephensi Liston and Aedes aegypti (L.). Sensilla coeloconica (pegs in pits) with thick-walled pegs, previously reported from A. aegypti and Culex pipiens L. also occur on the antennae of An. stephensi.The fine structure of the sensilla ampullacea and coeloconica is similar. Each sensillum consists of a non-perforated, thick-walled peg located in either a deep tube or a pit, and is innervated by three neurons. The unbranched dendrites of two neurons extend into the lumen of the peg. The dendrite of the third neuron, which is distally folded into lamellae in all of the sensilla ampullacea and some of the sensilla coeloconica, terminates beneath the peg. Three sheath cells are associated with each sensillum.Sensilla coeloconica on the antennae of female Aedes aegypti are thermoreceptors. On the basis of similarity in fine structure, sensilla coeloconica and ampullacea of An. stephensi probably also play a role in thermoreception.