Search results for "Vertebra"
showing 10 items of 1220 documents
Development and Characterization of Diamondback Moth Resistance to Transgenic Broccoli Expressing High Levels of Cry1C
2000
ABSTRACT A field-collected colony of the diamondback moth, Plutella xylostella , had 31-fold resistance to Cry1C protoxin of Bacillus thuringiensis . After 24 generations of selection with Cry1C protoxin and transgenic broccoli expressing a Cry1C protein, the resistance that developed was high enough that neonates of the resistant strain could complete their entire life cycle on transgenic broccoli expressing high levels of Cry1C. After 26 generations of selection, the resistance ratios of this strain to Cry1C protoxin were 12,400- and 63,100-fold, respectively, for the neonates and second instars by a leaf dip assay. The resistance remained stable until generation 38 (G38) under continuous…
Association of Cry1Ac toxin resistance in Helicoverpa zea (Boddie) with increased alkaline phosphatase levels in the midgut lumen.
2012
ABSTRACT Resistance to Bacillus thuringiensis Cry1Ac toxin was characterized in a population of Helicoverpa zea larvae previously shown not to have an alteration in toxin binding as the primary resistance mechanism to this toxin. Cry1Ac-selected larvae (AR1) were resistant to protoxins and toxins of Cry1Ab, Cry1Ac, and the corresponding modified proteins lacking helix α-1 (Cry1AbMod and Cry1AcMod). When comparing brush border membrane vesicles (BBMVs) prepared from susceptible (LC) and AR1 larval midguts, there were only negligible differences in overall Cry1Ac toxin binding, though AR1 had 18% reversible binding, in contrast to LC, in which all binding was irreversible. However, no differe…
In Vivo and In Vitro Binding of Vip3Aa to Spodoptera frugiperda Midgut and Characterization of Binding Sites by 125 I Radiolabeling
2014
ABSTRACT Bacillus thuringiensis vegetative insecticidal proteins (Vip3A) have been recently introduced in important crops as a strategy to delay the emerging resistance to the existing Cry toxins. The mode of action of Vip3A proteins has been studied in Spodoptera frugiperda with the aim of characterizing their binding to the insect midgut. Immunofluorescence histological localization of Vip3Aa in the midgut of intoxicated larvae showed that Vip3Aa bound to the brush border membrane along the entire apical surface. The presence of fluorescence in the cytoplasm of epithelial cells seems to suggest internalization of Vip3Aa or a fragment of it. Successful radiolabeling and optimization of the…
A taphonomic investigation of small vertebrate accumulations produced by the snowy owl (Bubo scandiacus) and its implications for fossil studies
2019
17 pages; International audience; The action of predators, such as diurnal raptors, owls, mammals or humans, influence the nature of smallvertebrate fossil assemblages but currently their taphonomic features are still poorly understood. In this study,we investigate the taphonomic signature of the snowy owl (Bubo scandiacus) based on an analysis of pelletscollected at breeding sites located in Greenland and the Canadian Arctic. This taxon is widely distributedthrough the North Hemisphere and was an important predator in Pleistocene times. Taphonomic parameterssuggest that, contrary to previous assumptions, B. scandiacus produces, on average, moderate digestion of incisors,molars and post-cra…
Poggetti Vecchi (Tuscany, Italy): A late Middle Pleistocene case of human-elephant interaction
2019
Abstract A paleosurface with a concentration of wooden-, bone-, and stone-tools interspersed among an accumulation of fossil bones, largely belonging to the straight-tusked elephant Palaeoloxodon antiquus, was found at the bottom of a pool, fed by hot springs, that was excavated at Poggetti Vecchi, near Grosseto (Tuscany, Italy). The site is radiometrically dated to the late Middle Pleistocene, around 171,000 years BP. Notable is the association of the artifacts with the elephant bones, and in particular the presence of digging sticks made from boxwood (Buxus sp.). Although stone tools show evidence of use mainly on animal tissues, indicating some form of interaction between hominins and an…
MEDLEM database, a data collection on large Elasmobranchs in the Mediterranean and Black seas
2020
The Mediterranean Large Elasmobranchs Monitoring (MEDLEM) database contains more than 3,000 records (with more than 4,000 individuals) of large elasmobranch species from 21 different countries around the Mediterranean and Black seas, observed from 1666 to 2017. The principal species included in the archive are the devil ray (1,868 individuals), the basking shark (935 individuals), the blue shark (622 individuals), and the great white shark (342 individuals). In the last decades, other species such as the thresher shark (187 individuals), the shortfin mako (180 individuals), and the spiny butterfly ray (138) were reported with increasing frequency. This was possibly due to increased public a…
Biogenic habitat shifts under long-term ocean acidification show nonlinear community responses and unbalanced functions of associated invertebrates
2019
Este artículo contiene 8 páginas, 4 figuras.
Cellular, biochemical and molecular effects of cadmium on marine invertebrates: focus on Paracentrotus lividus sea urchin development
2009
Cadmium is a heavy metal that is toxic for living organisms even at low concentrations. The presence in the environment of this metal has grown because of its large employment in some industrial and agricultural activities. Although heavy metals are terrestrially produced, they flow into the sea through effluents and sewage or are directly discharged from industries placed on the seawater front. In addition to its release into costal waters, cadmium fallout, following atmospheric events, contributes to the pollution of marine ecosystems. It should be considered that cadmium concentrations determined in the field vary widely according to different seawater latitudes and depths and can be str…
Metal accumulation in sediments and benthic invertebrates in lakes of Latvia
1998
The concentrations of cadmium, lead, nickel and copper in waters, sediments (total metal concentrations and their speciation forms) and benthic macroinvertebrates in 11 lakes of Latvia were determined using atomic absorption spectroscopy. Metal concentrations in lake waters, sediments and biota were compared with water chemistry. Compared to total concentrations, metal speciation forms in sediments were better correlated with respective metal concentrations in invertebrates. Therefore, the evaluation of potential metal bioaccumulation should consider metal speciation. The mean concentrations of trace metals in benthic invertebrates in Latvia were much lower than in other countries, which ca…
Biomethylation of Heavy Metals in Soil and Terrestrial Invertebrates
2009
Heavy metals play a prominent role in the lives of all organisms. They can be essential, as in the cases of iron, manganese, nickel and copper, which are needed to obtain proper enzyme conformation and reactivity. Some heavy metals are toxic to organisms, such as mercury or cadmium. Often, these metals are rarely accessible in their inorganic form. After biological transformation into organometallic compounds, they exhibit increased toxicity and penetration into animal tissue is facilitated. The alkylation mechanisms of metals (especially mercury) performed by aquatic microorganisms have been well documented. The organometallic food chain from fish to humans has also been investigated. Howe…