Potential use of fatty Acid profile for Artemia spp. discrimination

The brine shrimpArtemiais of considerable economic importance in fish and shellfish larviculture. The quality of theArtemiaproduct, differs, in terms of hatching and biometric characteristics, from strain to strain and from location to location. The same applies for their nutritional value which is not constant but varies among strains and within batches of each strain, causing unreliable outputs in marine larviculture. In the present paper we report and compare the fatty acid profiles of decapsulatedArtemiacysts of thirteenArtemiapopulations from different species and geographical origins. Results showed that palmitic acid (16:0) was found in relatively constant proportions from 11.4 to 20.6% of total fatty acids in the cysts of all populations, while proportions of palmitoleic acid (16:1n-7) were higher in marine-type populations (18.6 to 19.1%) than in freshwater-type population (4.3 to 8.3%). In contrast, linoleic acid (18:2n-6) was observed in higher quantity in freshwater-type populations (4.0 to 8.1%) than in marine-type populations (3.1 to 3.3%). Furthermore, a higher n-3/n-6 HUFA ratio was observed in the marine-type population (>1) than in the freshwater-type population (<1). Principal component analysis revealed that total (n-3/n-6) HUFA ratio, C16:1(n-7), C20:5(n-3), C16:0/16:1 ratio and total (n-3/n-6) ratio are the most important variables for the differentiation between studied populations with a contribution of 49.6%. The analysis also showed that C16:1n-7, C18:2n-6, total n-3, total n-6 and total n-3 HUFA quantity as well as n-3/n-6 and n-3/n-6 HUFA ratio can also be used to discriminate between the differentArtemiatypes. On the other hand, despite the intra-population differences observed (when comparing our results with literature data) in fatty acid structure, it is clear that the structure and the proportion of the different fatty acids as well as the assignment of a population to the marine-or freshwater-type is stable, suggesting that the fatty acid profile is both under a genetic control and being affected by the prevailing abiotic conditions

PTPA variants and impaired PP2A activity in early-onset parkinsonism with intellectual disability

The protein phosphatase 2A complex (PP2A), the major Ser/Thr phosphatase in the brain, is involved in a number of signalling pathways and functions, including the regulation of crucial proteins for neurodegeneration, such as alphasynuclein, tau and LRRK2. Here, we report the identification of variants in the PTPA/PPP2R4 gene, encoding a major PP2A activator, in two families with early-onset parkinsonism and intellectual disability.We carried out clinical studies and genetic analyses, including genome-wide linkage analysis, whole-exome sequencing, and Sanger sequencing of candidate variants. We next performed functional studies on the disease-associated variants in cultured cells and knock-down of ptpa in Drosophila melanogaster.We first identified a homozygous PTPA variant, c.893T&gt;G (p.Met298Arg), in patients from a South African family with early-onset parkinsonism and intellectual disability. Screening of a large series of additional families yielded a second homozygous variant, c.512C&gt;A(p.Ala171Asp), in a Libyan family with a similar phenotype. Both variants co-segregate with disease in the respective families. The affected subjects display juvenile-onset parkinsonism and intellectual disability. The motor symptoms were responsive to treatment with levodopa and deep brain stimulation of the subthalamic nucleus.In overexpression studies, both the PTPA p.Ala171Asp and p.Met298Arg variants were associated with decreased PTPA RNA stability and decreased PTPA protein levels; the p.Ala171Asp variant additionally displayed decreased PTPA protein stability. Crucially, expression of both variants was associated with decreased PP2A complex levels and impaired PP2A phosphatase activation. PTPA orthologue knock-down in Drosophila neurons induced a significant impairment of locomotion in the climbing test. This defect was age-dependent and fully reversed by L-DOPA treatment.We conclude that bi-allelic missense PTPA variants associated with impaired activation of the PP2A phosphatase cause autosomal recessive early-onset parkinsonism with intellectual disability. Our findings might also provide new insights for understanding the role of the PP2A complex in the pathogenesis of more common forms of neurodegeneration