10 research outputs found
Visual Lateralization in Wild Striped Dolphins (Stenella coeruleoalba) in Response to Stimuli with Different Degrees of Familiarity
Background: Apart from findings on both functional and motor asymmetries in captive aquatic mammals, only few studies have focused on lateralized behaviour of these species in the wild. Methodology/Principal Findings: In this study we focused on lateralized visual behaviour by presenting wild striped dolphins with objects of different degrees of familiarity (fish, ball, toy). Surveys were conducted in the Gulf of Taranto, the northern Ionian Sea portion delimited by the Italian regions of Calabria, Basilicata and Apulia. After sighting striped dolphins from a research vessel, different stimuli were presented in a random order by a telescopic bar connected to the prow of the boat. The preferential use of the right/left monocular viewing during inspection of the stimuli was analysed. Conclusion: Results clearly showed a monocular viewing preference with respect to the type of the stimulus employed. Due to the complete decussation of the optical nerves in dolphin brain our results reflected a different specialization of brain hemispheres for visual scanning processes confirming that in this species different stimuli evoked different patterns of eye use. A preferential use of the right eye (left hemisphere) during visual inspection of unfamiliar targets was observed supporting the hypothesis that, in dolphins, the organization of the functional neural structures which reflected cerebral asymmetries for visual object recognition could have been subjected to a deviation from the evolutionary line of mos
ENPP1 Affects Insulin Action and Secretion: Evidences from In Vitro Studies
The aim of this study was to deeper investigate the mechanisms through which
ENPP1, a negative modulator of insulin receptor (IR) activation, plays a role on
insulin signaling, insulin secretion and eventually glucose metabolism. ENPP1
cDNA (carrying either K121 or Q121 variant) was transfected in HepG2 liver-, L6
skeletal muscle- and INS1E beta-cells. Insulin-induced IR-autophosphorylation
(HepG2, L6, INS1E), Akt-Ser473,
ERK1/2-Thr202/Tyr204 and GSK3-beta Ser9
phosphorylation (HepG2, L6), PEPCK mRNA levels (HepG2) and
2-deoxy-D-glucose uptake (L6) was studied. GLUT 4 mRNA
(L6), insulin secretion and caspase-3 activation (INS1E) were also investigated.
Insulin-induced IR-autophosphorylation was decreased in HepG2-K, L6-K, INS1E-K
(20%, 52% and 11% reduction vs. untransfected cells) and
twice as much in HepG2-Q, L6-Q, INS1E-Q (44%, 92% and 30%).
Similar data were obtained with Akt-Ser473,
ERK1/2-Thr202/Tyr204 and GSK3-beta Ser9 in
HepG2 and L6. Insulin-induced reduction of PEPCK mRNA was progressively lower in
untransfected, HepG2-K and HepG2-Q cells (65%, 54%, 23%).
Insulin-induced glucose uptake in untransfected L6 (60% increase over
basal), was totally abolished in L6-K and L6-Q cells. GLUT 4 mRNA was slightly
reduced in L6-K and twice as much in L6-Q (13% and 25% reduction
vs. untransfected cells). Glucose-induced insulin secretion was 60%
reduced in INS1E-K and almost abolished in INS1E-Q. Serum deficiency activated
caspase-3 by two, three and four folds in untransfected INS1E, INS1E-K and
INS1E-Q. Glyburide-induced insulin secretion was reduced by 50% in
isolated human islets from homozygous QQ donors as compared to those from KK and
KQ individuals. Our data clearly indicate that ENPP1, especially when the Q121
variant is operating, affects insulin signaling and glucose metabolism in
skeletal muscle- and liver-cells and both function and survival of insulin
secreting beta-cells, thus representing a strong pathogenic factor predisposing
to insulin resistance, defective insulin secretion and glucose metabolism
abnormalities
Targets.
<p>Visual stimuli: a) blue-fish life-size plastic model; b) coloured ball; c) fabric toy.</p
Eye preference to look at different targets.
<p>Preferentially right (black histograms) and left (white histograms) eye use during visual inspection of different visual stimuli (means with S.E.M. are shown; * P<0.05; ** P<0.01, Wilcoxon's signed-ranks test).</p
Individual identification.
<p>Characteristic markings on the body used for dolphin individual identification (white circles): a-b-d) scratches of different colors; c) fin injuries.</p
Testing apparatus.
<p>Experimental setup: a) Striped Dolphin approaching to the testing apparatus; b) Schematic representation of the testing apparatus, lateral view.</p
Total time spent looking at different targets.
<p>Total time spent during visual inspection of toy (black histogram), ball (gray histogram) and fish (white histogram) stimuli (means with S.E.M. are shown; * P<0.01, Mann-Whitney U-test).</p
Eye preference to look at different targets - Total time.
<p>Total time spent using either the left (white histograms) or right (black histograms) eye during visual inspection of targets (means with S.E.M. are shown; * P<0.01; ** P<0.001, Mann-Whitney U-test).</p