Search results for "Invertebrate Microbiology"
showing 10 items of 42 documents
Vip3C, a novel class of vegetative insectidal proteins from Bacillus thuringiensis
2012
Three vip3 genes were identified in two Bacillus thuringiensis Spanish collections. Sequence analysis revealed a novel Vip3 protein class (Vip3C). Preliminary bioassays of larvae from 10 different lepidopteran species indicated that Vip3Ca3 caused more than 70% mortality in four species after 10 days at 4 οg/cm 2. © 2012, American Society for Microbiology.
Spirochaeta coccoides sp. nov., a novel coccoid spirochete from the hindgut of the termite Neotermes castaneus.
2006
ABSTRACT A novel spirochete strain, SPN1, was isolated from the hindgut contents of the termite Neotermes castaneus . The highest similarities (about 90%) of the strain SPN1 16S rRNA gene sequence are with spirochetes belonging to the genus Spirochaeta , and thus, the isolate could not be assigned to the so-called termite clusters of the treponemes or to a known species of the genus Spirochaeta . Therefore, it represents a novel species, which was named Spirochaeta coccoides . In contrast to all other known validly described spirochete species, strain SPN1 shows a coccoid morphology and is immotile. The isolated strain is obligately anaerobic and ferments different mono-, di-, and oligosacc…
Molecular characterization of the leucine cluster in Buchnera PSY, primary endosymbiont of the aphid Pemphigus spyrothecae
2002
ABSTRACT Buchnera strains from most aphid subfamilies studied to date have been found to carry the leucine gene cluster ( leuA , - B , - C , and - D ) on a plasmid, an organization unique among bacteria. Here, however, we demonstrate a classical chromosomal location of the cluster in Buchnera sp. strain PSY from the aphid Pemphigus spyrothecae (subfamily Pemphiginae). The genes that flank leuABCD in Buchnera sp. strain PSY appear to be adjacent in the genome of Buchnera sp. strain APS, a strain carrying a leucine plasmid. We propose that the presence of a leucine plasmid predates the diversification of symbiotic Buchnera and that the chromosomal location observed in Buchnera sp. strain PSY …
Role of Bacillus thuringiensis Toxin Domains in Toxicity and Receptor Binding in the Diamondback Moth
1999
ABSTRACT The toxic fragment of Bacillus thuringiensis crystal proteins consists of three distinct structural domains. There is evidence that domain I is involved in pore formation and that domain II is involved in receptor binding and specificity. It has been found that, in some cases, domain III is also important in determining specificity. Furthermore, involvement of domain III in binding has also been reported recently. To investigate the role of toxin domains in the diamondback moth ( Plutella xylostella ), we used hybrid toxins with domain III substitutions among Cry1C, Cry1E, and Cry1Ab. Neither Cry1E nor G27 (a hybrid with domains I and II from Cry1E and domain III from Cry1C) was to…
Molecular and Insecticidal Characterization of a Cry1I Protein Toxic to Insects of the Families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae
2006
ABSTRACT The most notable characteristic of Bacillus thuringiensis is its ability to produce insecticidal proteins. More than 300 different proteins have been described with specific activity against insect species. We report the molecular and insecticidal characterization of a novel cry gene encoding a protein of the Cry1I group with toxic activity towards insects of the families Noctuidae, Tortricidae, Plutellidae, and Chrysomelidae. PCR analysis detected a DNA sequence with an open reading frame of 2.2 kb which encodes a protein with a molecular mass of 80.9 kDa. Trypsin digestion of this protein resulted in a fragment of ca. 60 kDa, typical of activated Cry1 proteins. The deduced sequen…
Use of Bacillus thuringiensis toxins for control of the cotton pest earias insulana (Boisd.) (Lepidoptera: Noctuidae)
2006
ABSTRACT Thirteen of the most common lepidopteran-specific Cry proteins of Bacillus thuringiensis have been tested for their efficacy against newly hatched larvae of two populations of the spiny bollworm, Earias insulana . At a concentration of 100 μg of toxin per milliliter of artificial diet, six Cry toxins (Cry1Ca, Cry1Ea, Cry1Fa, Cry1Ja, Cry2Aa, and Cry2Ab) were not toxic at all. Cry1Aa, Cry1Ja, and Cry2Aa did not cause mortality but caused significant inhibition of growth. The other Cry toxins (Cry1Ab, Cry1Ac, Cry1Ba, Cry1Da, Cry1Ia, and Cry9Ca) were toxic to E. insulana larvae. The 50% lethal concentration values of these toxins ranged from 0.39 to 21.13 μg/ml (for Cry9Ca and Cry1Ia, …
Analyses of Cry1Ab binding in resistant and susceptible strains of the European corn borer, Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae).
2006
ABSTRACT Cry1Ab toxin binding analysis was performed to determine whether resistance in laboratory-selected Ostrinia nubilalis strains is associated with target site alteration. Brush border membrane vesicles were prepared using dissected midguts from late instars of susceptible and resistant strains (Europe-R and RSTT) of O. nubilalis . Immunoblot analysis indicated that three different proteins bound to Cry1Ab toxin and were recognized by an anticadherin serum. In a comparison of resistant and susceptible strains, reduced Cry1Ab binding was apparent for all three bands corresponding to cadherin-like proteins in the Europe-R strain, while reduced binding was apparent in only one band for t…
Specific Detection and Localization of Microsporidian Parasites in Invertebrate Hosts by Using In Situ Hybridization
2013
ABSTRACT We designed fluorescence in situ hybridization probes for two distinct microsporidian clades and demonstrated their application in detecting, respectively, Nosema / Vairimorpha and Dictyoceola species. We used them to study the vertical transmission of two microsporidia infecting the amphipod Gammarus duebeni .
Lack of Detrimental Effects of Bacillus thuringiensis Cry Toxins on the Insect Predator Chrysoperla carnea : a Toxicological, Histopathological, and …
2006
ABSTRACT The effect of Cry proteins of Bacillus thuringiensis on the green lacewing ( Chrysoperla carnea ) was studied by using a holistic approach which consisted of independent, complementary experimental strategies. Tritrophic experiments were performed, in which lacewing larvae were fed Helicoverpa armigera larvae reared on Cry1Ac, Cry1Ab, or Cry2Ab toxins. In complementary experiments, a predetermined amount of purified Cry1Ac was directly fed to lacewing larvae. In both experiments no effects on prey utilization or fitness parameters were found. Since binding to the midgut is an indispensable step for toxicity of Cry proteins to known target insects, we hypothesized that specific bind…
Different mechanisms of resistance to Bacillus thuringiensis toxins in the indianmeal moth.
2001
ABSTRACT Susceptibility to protoxin and toxin forms of Cry1Ab and the binding of 125 I-labeled Cry1Ab and Cry1Ac has been examined in three Plodia interpunctella colonies, one susceptible (688 s ) and two resistant (198 r and Dpl r ) to Bacillus thuringiensis . Toxicological studies showed that the 198 r colony was 11-fold more resistant to Cry1Ab protoxin than to Cry1Ab activated toxin, whereas the Dpl r colony was 4-fold more resistant to protoxin versus toxin. Binding results with 125 I-labeled toxins indicated the occurrence of two different binding sites for Cry1Ab in the susceptible insects, one of them shared with Cry1Ac. Cry1Ab binding was found to be altered in insects from both re…