Montserrat Fernández

Regulation of the futile cycle of fructose phosphate in sea mussel

Carbohydrate metabolism in mussels shows two phases separated seasonally. During summer and linked to food supply, carbohydrates, mainly glycogen, are accumulated in the mantle tissue. During winter, mantle glycogen decreases concomitantly with an increase in triglyceride synthesis. In spring, after spawning, the animals go in to metabolic rest until the beginning of a new cycle. This cycle is regulated by the futile cycle of fructose phosphate that implicates PFK-1 and FBPase-1 activities. These enzymes and the bifunctional PFK-2/FBPase-2 that regulates the Fru-2,6-P2 levels, are seasonally modulated by covalent phosphorylation/dephosphorylation mechanisms, as a response to unknown factors. The futile cycle of the fructose phosphates also controls the transition from physiological aerobiosis to hypoxia. The process is independent of the phosphorylation state. In this sense, a pH decrease triggers a small Pasteur effect during the first 24 h of aerial exposure. Variations in the concentration of Fru-2,6-P2 and AMP are the sole factor responsible for this effect. Longer periods of hypoxia induce a metabolic depression characterized by a decrease in Fru-2,6-P2 which is hydrolyzed by drop in the pH. In this review, the authors speculate on the two regulation processes.

cAMP‐dependent phosphorylation activates phosphofructokinase from mantle tissue of the mollusc Mytilus galloprovincialis. Identification of the phosphorylated site

Phosphofructokinase from mantle tissue of the sea mussel Mytilus galloprovincialis was phosphorylated in vitro by a protein kinase isolated from the same tissue, homologous to mammalian cAMP‐dependent protein kinase; the maximal level of phosphorylation achieved was around 1 mol of Pi/mol of phosphofructokinase subunit. The covalent incorporation of phosphate leads to a notable increase in the enzyme activity assayed at near‐physiological concentrations of substrates and allosteric modulators and neutral pH. Tryptic digestion of labeled phosphofructokinase released a phosphopeptide whose sequence was Lys‐Asp‐Ser(P)‐Ile‐Trp‐Ile‐Gln‐Thr‐Gly‐Arg. This sequence showed high homology with the phosphopeptides from other invertebrates whose phosphofructokinase is also activated by cAMP‐dependent phosphorylation.

Identification of RII-binding proteins in the mollusc Mytilus galloprovincialis

Several proteins with M r 70 kDa from various tissues of the sea mussel Mytilus galloprovincialis were specifically recognized in vitro by the regulatory subunit (type RIIα) of cAMP‐dependent protein kinase (cAPK) from porcine heart. However, none of these proteins interacted with the regulatory subunit of cAPK from the mollusc itself. The results suggest that, unlike mammalian RII, regulatory subunit from mussel lacks the specific residues responsible for interaction with R‐binding proteins. Consequently, the identified molluscan RIIα‐binding proteins should play a distinct role from cAPK anchoring.

Uncommon genetic syndromes and narrative production - Case Studies with Williams, Smith-Magenis and Prader-Willi Syndromes?

Abstract This study compares narrative production among three syndromes with genetic microdeletions: Williams syndrome (WS), Smith-Magenis syndrome (SMS), and Prader-Willi syndrome (PWS), characterized by intellectual disabilities and relatively spared language abilities. Our objective is to study the quality of narrative production in the context of a common intellectual disability. To elicit a narrative production, the task Frog! Where Are You was used. Then, structure, process, and content of the narrative process were analysed in the three genetic disorders: WS (n = 2), SMS (n = 2), and PWS (n = 2). Data show evidence of an overall low narrative quality in these syndromes, despite a high variability within different measures of narrative production. Results support the hypothesis that narrative is a highly complex cognitive process and that, in a context of intellectual disability, there is no evidence of particular ‘hypernarrativity’ in these syndromes.