768 research outputs found
In situ analysis of pH gradients in mosquito larvae using non-invasive, self-referencing, pH-sensitive microelectrodes
No full textThe alkaline environment, pH approximately 11, in the anterior midgut lumen of mosquito larvae is essential for normal nutrition and development. The mechanism of alkalization is, however, unknown. Although evidence from immunohistochemistry, electron microscopy and electrophysiology suggests that a V-ATPase is present in the basal membranes of the epithelial cells, its physiological role in the alkalization process has not been demonstrated. To investigate a possible role of the V-ATPase in lumen alkalization, pH gradients emanating from the hemolymph side of the midgut in semi-intact mosquito larvae were measured using non-invasive, self-referencing, ion-selective microelectrodes (SERIS). Large H+ concentration gradients, with highest concentrations close to the basal membrane (outward [H+] gradients), were found in the anterior midgut, whereas much smaller gradients, with concentrations lowest close to this membrane (inward [H+] gradients), were found in the gastric caeca and posterior midgut. Similar region-specific pH gradients, with consistent anterior-to-posterior profiles, were observed in individuals of two Aedes species, Aedes aegypti from semi-tropical Florida and Aedes canadensis from north-temperate Massachusetts. The gradients remained in a steady state for up to 6 h, the maximum duration of the recordings. Bafilomycin A1 (10(-5), 10(-7 )mol x l(-1)) on the hemolymph side greatly diminished the [H+] gradients in the anterior midgut but had no effect on the gradients in the gastric caecum and posterior midgut. These physiological data are consistent with the previous findings noted above. Together, they support the hypothesis that a basal, electrogenic H+ V-ATPase energizes luminal alkalization in the anterior midgut of larval mosquitoes
How problem solving changes affect adult neurogenesis in Octopus vulgaris
No full textOctopus vulgaris has a complex and centralized nervous system, located around oesophagus, with a hierarchical organization. It is considered the most intelligent invertebrate due to its advanced cognitive capability, as learning and memory, and complex behaviour that results in an enormous capability of problem solving. “Problem solving” is the capability to use cognitive processing to find a solution to a problematic situation. Several behavioural experiments show that octopus has this kind of skill (FINN et al., 2009). Neural plasticity and synaptic remodelling are the base of adult neurogenesis that occur in organisms that have complex and centralized nervous system, as teleosts, amphibians, reptiles, birds and mammals, and among invertebrates, decapods and insects. Recently, our group demonstrated its occurrence also in O. vulgaris brain, resulting the first demonstration across Lophotrochozoa clade.
The experimental data have been obtained by problem solving behavioural experiments and the evaluation of the Oct-Pax6 expression. Pax6 gene is known as neurogenic marker during cephalopod brain development (NAVET et al., 2017). Specimens of O. vulgaris were divided into two experimental groups: challenged and control. After the acclimatization period, the standard housing condition was altered adding jars containing food providing a cognitive challenge. During experimental days, octopuses had not feeding opportunities except to open the jars to reach the food. Control animals were not challenged and they were fed regularly without any task. At last, challenged and control octopuses were scarified as described in POLESE et al. (2014) and their brains were dissected out to be processed for RNA extraction with Trizol. cDNA obtained was used to evaluate the amount of Oct-Pax6 through a semi-quantitative PCR, using -tubulin as normalizer. PCR products were analysed on 2% agarose gel at the Bio-Rad ChemiDoc, and quantified using ImageJ.
Our data show that octopuses challenged with problem solving tasks vs. unchallenged animals result in up- regulation of Oct-Pax6 in areas of the brain previously described as sites of adult neurogenesis (BERTAPELLE et al., 2017).
In conclusion, these results support that intellectual, physical and sensory challenges increase neural plasticity and synaptic remodelling through adult neurogenesis
Letter to L.L. McGee from unknown author regarding members of an all state team
No full textLetter listing selections for the all state team for Douglass High School
Essay about how the image of Maine is constructed by institutions like L.L. Bean
No full textEssay about how the image of Maine is constructed by institutions like L.L. Bean and Bert and I. The author asks if local imagemakers are more true to life than their mass market counterparts
Development and characterization of a thermostable nckel-alumina methanation catalyst
No full textApplied Science
Matthew Flinders, Capt. R.N. 1809, author of Trim [picture] /
No full textTitle from inscription l.r.; Inscription l.l.: Recollection of a miniature.; Signature l.l.; In his Album of drawings.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an6325371; R8205
An interpretation of the U.V. and E.S.R. spectra of some chlorocomplexes of tervalent titanium
No full textApplied Science
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