Do toxic Pseudo-nitzschia species pose a threat to aquaculture in the southern Benguela eastern boundary upwelling system?

The productive but highly exposed coastline of the southern Benguela eastern boundary upwelling system offers limited natural environment for aquaculture. Saldanha Bay located on the west coast of South Africa is one of the few embayments on the coastline that provides a productive and relatively sheltered environment suitable for the cultivation of shellfish. Consequently, bivalve culture in South Africa is centered in Saldanha Bay and is presently targeted for expansion. Pseudo-nitzschia blooms including toxin-producing species are shown to contribute significantly to the phytoplankton of Saldanha Bay specifically in spring and summer. Their dominance at this time of the year, when upwelling is strongest, fits the ecological profile of Pseudo-nitzschia occurring during periods of high turbulence and nutrients. Multiple Pseudo-nitzschia blooms were sampled under varying environmental conditions and the strength of the relationship between Pseudo-nitzschia cell abundance and particulate domoic acid (pDA) content, reflecting bloom toxicity, varied greatly. This variability is the result of the combined influence of species and strain composition of the Pseudo-nitzschia assemblage and the effect of environmental conditions on toxin production. Elevated levels of pDA were associated with higher concentrations of cells of the P. seriata complex differentiated by frustule width (>3 µm). P. australis was identified as a toxin-producing species and a prominent member of the P. seriata complex. Low DA levels in shellfish in Saldanha Bay are considered a function of low cellular domoic acid (cDA). Silicate limitation has emerged as an important factor inducing DA production in Pseudo-nitzschia species. The high ratio of silicate to nitrate in Saldanha Bay provides a plausible explanation for the low toxin content of Pseudo-nitzschia blooms in the bay and the consequent low risk posed by these blooms to the aquaculture sector.

MED13L-related intellectual disability: involvement of missense variants and delineation of the phenotype.

Molecular anomalies in MED13L, leading to haploinsufficiency, have been reported in patients with moderate to severe intellectual disability (ID) and distinct facial features, with or without congenital heart defects. Phenotype of the patients was referred to "MED13L haploinsufficiency syndrome." Missense variants in MED13L were already previously described to cause the MED13L-related syndrome, but only in a limited number of patients. Here we report 36 patients with MED13L molecular anomaly, recruited through an international collaboration between centers of expertise for developmental anomalies. All patients presented with intellectual disability and severe language impairment. Hypotonia, ataxia, and recognizable facial gestalt were frequent findings, but not congenital heart defects. We identified seven de novo missense variations, in addition to protein-truncating variants and intragenic deletions. Missense variants clustered in two mutation hot-spots, i.e., exons 15-17 and 25-31. We found that patients carrying missense mutations had more frequently epilepsy and showed a more severe phenotype. This study ascertains missense variations in MED13L as a cause for MED13L-related intellectual disability and improves the clinical delineation of the condition.

Presence of Gamma-Aminobutyric Acid (Gaba) in the Pedal Mucus of the Critically Endangered Species Patella ferruginea.

Patella ferruginea is a giant patellid limpet endemic to the Mediterranean Sea. It presently is in danger of extinction, and many have called for developing conservation measures including the mass production of spats for re-introduction projects. However, so far all attempts have been relatively unsuccessful. Previous work analyzing the effects of gamma-aminobutyric acid (GABA) on the recruitment of patellid limpets has shown that larvae respond to the presence of this signaling molecule. This response could explain the gregarious distribution typical of this species. In the present study, we demonstrated that GABA is naturally secreted by P. ferruginea in the pedal mucus. GABA is preferentially secreted during the summer, coinciding with the reproductive resting period of the species. Further research should aim to analyze the effects of GABA on larval development and metamorphosis in order to assess its potential use to improve conservation efforts.

Latitudinal transects in the southeastern Pacific Ocean reveal a diverse but patchy distribution of phycotoxins.

Phycotoxin distribution and abundance was determined during an oceanographic expedition along a latitudinal transect of 27° extent in the southeastern Pacific Ocean, from the fjords of Tierra del Fuego Island to offshore Copiapó in the Atacama region along the Chilean coast. Plankton samples were harvested at regular intervals during the entire cruise and later analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) for domoic acid (DA) and lipophilic toxins. Although no evident toxic algal bloom was encountered during this transect, several phycotoxin analogues from distinct toxin groups were detected. These phycotoxins included DA, the pectenotoxins PTX-2, PTX-2sa and PTX-11, dinophystoxin-1 (DTX-1) and gymnodimine (GYM), which is the first report of this latter toxin in the southeast Pacific. A region-specific and rather disjunct distribution of GYM, DA and DTX-1 was observed, whereas PTX-2, PTX-2sa and PTX-11 were more widely distributed over almost the entire transect. This work represents the first assessment of lipophilic toxins through a wide latitudinal transect of the southeastern Pacific, revealing a patchy distribution of several phycotoxins and pointing out the specific geographical distribution of the putative toxigenic organisms.

PCB/toxaphene group separation on silica prior to congener specific determination of toxaphene residues in fish and other samples by GC/ECD.

A precise quantification of toxaphene residues of environmental samples by gas chromatography/ electron capture detection (GC/ECD) requires the separation of the bulk of the polychlorinated biphenyls (PCBs) from the compounds of technical toxaphene (CTT) fraction. For this reason, a PCB/CTT group separation on silica was developed. B8-1413 (Parlar #26) and B7-515 (Parlar #32) eluted as first and last out of ten important CTT standards, and can be used to determine the elution volume of the CTT fraction on silica. GC/ECD quantification of CTTs was possible after separation of PCBs on 8.0 g activated silica eluted with 48 mL n-hexane followed by quantitative elution of CTTs with n-hexane/toluene (65:35; v/v). This method is a compromise between separation efficiency and consumption of material. Finally, eight CTTs were quantified in cod liver samples from Iceland and the Baltic Sea.