Search results for "MIDGUT"
showing 10 items of 81 documents
Study of the bacillus thuringiensis Cry1Ia protein oligomerization promoted by midgut brush border membrane vesicles of lepidopteran and coleopteran …
2020
Bacillus thuringiensis (Bt) produces insecticidal proteins that are either secreted during the vegetative growth phase or accumulated in the crystal inclusions (Cry proteins) in the stationary phase. Cry1I proteins share the three domain (3D) structure typical of crystal proteins but are secreted to the media early in the stationary growth phase. In the generally accepted mode of action of 3D Cry proteins (sequential binding model), the formation of an oligomer (tetramer) has been described as a major step, necessary for pore formation and subsequent toxicity. To know if this could be extended to Cry1I proteins, the formation of Cry1Ia oligomers was studied by Western blot, after the incuba…
Determination of mercury by cold‐vapour technique in several tissues of treated American red crayfish (Procambarus clarkii)
1988
Abstract Adult intermolt specimens of American red crayfish (Procambarus clarkii) collected from Lake Albufera (Valencia, Spain), were exposed to mercury during 96 h. The Hg‐concentrations used were 50, 100, and 250 μg Hg/1 as Cl2Hg. The content of mercury in muscle, midgut gland, antennal glands and gills was investigated. Determinations of mercury were made by cold‐vapour technique and AAS. The mercury levels in all examinated tissues increased significantly (ANOVA test, p < 0.01) with increasing Hg‐concentration in the water.
Carbonic anhydrase activity in a calcium-mobilizing epithelium of the crustacean Orchestia cavimana during molting
1987
We investigated the involvement of the enzyme, carbonic anhydrase, in the calcification-decalcification processes occurring in the posterior caeca of the midgut of the terrestrial crustacean, Orchestia cavimana, before and after exuviation. This enzyme was ultrahistochemically localized throughout the membranes of the caecal epithelium as well as extracellularly, i.e., within pre-exuvial calcareous concretions and postexuvial calcified spherules. During the molt cycle, the pattern of carbonic anhydrase activity in the posterior caeca was correlated with the calcium content at this level. Acetazolamide treatment in vivo inhibited about 50% of the calcium uptake during both pre-exuvial secret…
A Systems Level Analysis Reveals Transcriptomic and Proteomic Complexity in Ixodes Ricinus Midgut and Salivary Glands During Early Attachment and Fee…
2014
Although pathogens are usually transmitted within the first 24–48 h of attachment of the castor bean tick Ixodes ricinus, little is known about the tick's biological responses at these earliest phases of attachment. Tick midgut and salivary glands are the main tissues involved in tick blood feeding and pathogen transmission but the limited genomic information for I. ricinus delays the application of high-throughput methods to study their physiology. We took advantage of the latest advances in the fields of Next Generation RNA-Sequencing and Label-free Quantitative Proteomics to deliver an unprecedented, quantitative description of the gene expression dynamics in the midgut and salivary glan…
The Independent Biological Activity of Bacillus thuringiensis Cry23Aa Protein Against Cylas puncticollis
2020
The Cry23Aa/Cry37Aa proteins from Bacillus thuringiensis (Bt) have been described toxic to Cylas puncticollis larvae. In general, it is believed that Cry23Aa and Cry37Aa act jointly to exert the insecticidal activity, while there is no evidence of their toxicity individually. Therefore, in the present study, the contribution of each protein in the insecticidal activity toward C. puncticollis larvae has been assessed. The results showed that both proteins were toxic for C. puncticollis larvae when tested individually. Contrary to what was claimed previously, our results suggest that the presence of both proteins is not necessary to exert toxicity against C. puncticollis larvae. Also, the bin…
Unraveling assemblage, functions and stability of the gut microbiota of Blattella germanica by antibiotic treatment
2020
Symbiosis between prokaryotes and eukaryotes is a widespread phenomenon that has contributed to the evolution of eukaryotes. In cockroaches, two types of symbionts coexist: an endosymbiont in the fat body (Blattabacterium), and a rich gut microbiota. The transmission mode of Blattabacterium is vertical, while the gut microbiota of a new generation is mainly formed by bacterial species present in feces. We have carried out a metagenomic analysis of Blattella germanica populations, treated and non-treated with two antibiotics (vancomycin and ampicillin) over two generations to (1) determine the core of bacterial communities and potential functions of the gut microbiota and (2) to gain insight…
Molecular architecture and activation of the insecticidal protein Vip3Aa from Bacillus thuringiensis
2020
9 p.-5 fig.
Variability in the cadherin gene in an Ostrinia nubilalis strain selected for Cry1Ab resistance
2008
Transgenic corn expressing Cry1Ab (a Bacillus thuringiensis toxin) is highly effective in the control of Ostrinia nubilalis. For its toxic action, Cry1Ab has to bind to specific insect midgut proteins. To date, in three Lepidoptera species resistance to a Cry1A toxin has been conferred by mutations in cadherin, a protein of the Lepidoptera midgut membrane. The implication of cadherin in the resistance of an Ostrinia nubilalis colony (Europe-R) selected with Bacillus thuringiensis Cry1Ab protoxin was investigated. Several major mutations in the cadherin (cdh) gene were found, which introduced premature termination codons and/or large deletions (ranging from 1383 to 1701bp). The contribution …
Effects of azadirachtin on the regulation of midgut peristalsis by the stomatogastric nervous system inLocusta migratoria
2000
A single injection of azadirachtin into nymphal and adult locusts results in a decrease of food intake but not in reduced food utilization. Feeding deterrency is correlated with a gradual inhibition of midgut peristalsis. Gut movement is under the control of the stomatogastric nervous system, especially the ingluvial ganglion, as demonstrated in anin vitro system. Serotonin is the most potent peristalsis-stimulating drugin vitro. Concurrent with the cessation of midgut peristalsis after azadirachtin injection, a depletion of the serotoninergic cell bodies in the frontal ganglion can be observed. Midgut preparations which show strongly inhibited contractions due to previous azadirachtin trea…
A new gene superfamily of pathogen-response (repat) genes in Lepidoptera: Classification and expression analysis
2012
Repat (REsponse to PAThogens) genes were first identified in the midgut of Spodoptera exigua (Lepidoptera: Noctuidae) in response to Bacillus thuringiensis and baculovirus exposure. Since then, additional repat gene homologs have been identified in different studies. In this study the comprehensive larval transcriptome from S. exigua was analyzed for the presence of novel repat-homolog sequences. These analyses revealed the presence of at least 46 repat genes in S. exigua, establishing a new gene superfamily in this species. Phylogenetic analysis and studies of conserved motifs in these hypothetical proteins have allowed their classification in two main classes, αREPAT and βREPAT. Studies o…