Evidence of egg laying grounds for critically endangered flapper skate (Dipturus intermedius) off Orkney, UK

Funding information: Surveys were supported by a grant from WWF Netherlands. The writing of this paper was funded via the SeaMonitor project; supported by the European Union’s INTERREG VA Programme (Environment Theme) and managed by the Special EU Programmes Body (SEUPB) (Grant IVA5060).Essential fish habitats (EFHs) are critical for fish life-history events, including spawning, breeding, feeding or growth. Here we provide evidence of EFH for the Critically Endangered flapper skate (Dipturus intermedius) in the waters around the Orkney Isles, Scotland based on citizen-science observation data. The habitats of potential egg laying sites were parametrised as >20m depth, with boulders or exposed bedrock, in moderate current flow (0.3 - 2.8 knots) with low sedimentation. This information provides a significant contribution to our understanding of EFH for flapper skate. Publisher PDFPeer reviewe

Diagnosis of mitochondrial disorders: clinical and biochemical approach.

Item does not contain fulltextThe topic of Workshop W3-1 was clinical and biochemical approaches to the diagnosis of mitochondrial respiratory chain disorders. Four main questions were addressed in an attempt to make some progress towards a consensus diagnostic approach: What are the major limitations in diagnosis of respiratory chain dysfunction? What is the ideal approach to investigating children with a suspected respiratory chain disorder? Can we begin to develop consensus diagnostic criteria? Can we develop a quality assurance (QA) scheme for respiratory chain enzyme assays? The workshop demonstrated strong consensus on recognizing the limitations of current diagnostic approaches, on the ideal diagnostic approach and on the desirability of an enzyme QA scheme. There was also support for the desirability of consensus diagnostic criteria, albeit with some concerns about the practicality of gaining consensus. Two potential approaches to developing consensus criteria were described

Mitochondrial DNA mutations at nucleotide 8993 show a lack of tissue- or age-related variation

Two pathogenic mitochondrial DNA mutations, a T-to-G substitution (8993T > G) and a T-to-C substitution (8993T > C), at nucleotide 8993 have been reported. We describe 13 pedigrees with mitochondrial DNA mutations at nucleotide 8993; 10 pedigrees with the 8993T > G mutation and three with the 8993T > C mutation. Prenatal diagnosis of the nucleotide 8993 mutations is technically possible. However, there are three major concerns: (i) that there is variation in mutant loads among tissues; (ii) that the mutant load in a tissue may change over time; and (iii) that the genotype-phenotype correlation is not clearly understood. We have used the 13 pedigrees to determine specifically the extent of tissue- and age-related variation of the two mutations at nucleotide 8993 in the mitochondrial DNA. The tissue variation was investigated by analysing two or more different tissues from a total of 18 individuals. The age-related variation of the mutation was investigated by comparing the amount of both mutations in blood taken at birth and at a later age. No substantial tissue variation was found, nor was there any substantial change in the proportion of either mutation over periods of 8-23 years in the four individuals studied. In addition, we noted that two features were remarkably common in families with nucleotide 8993 mutations, namely (i) unexplained infant death (8 cases in 13 pedigrees), and (ii) de novo mutations (5 of the 10 8993T > G pedigrees)

Preliminary insight into the reproductive traits of the flapper skate (Dipturus intermedius) using in-field ultrasonography and circulating hormone concentrations

Due to global population declines, there is a pressing need for data on the life history traits of many elasmobranch species to support the development of species-specific management plans. A lack of information on the reproductive cycle of the Critically Endangered flapper skate (Dipturus intermedius) was recently identified as a hindrance to its conservation. To address this data gap by combining non-lethal ultrasound and hormone analysis to investigate the size at maturity and reproductive cycle of the flapper skate in the Loch Sunart to the Sound of Jura Marine Protected Area off the west coast of Scotland. In-field ultrasound imagery revealed in-utero encapsulated eggs and was used to determine the presence and size of ovarian follicles. Combining these images with levels of plasma testosterone, progesterone, and oestradiol provided valuable insights into the timing of the reproductive cycle and maturity state of the flapper skate. This preliminary study suggests that male skate start to mature at 165 cm and female skate at 203 cm total length. Oestradiol appears to be the primary hormone controlling the female reproductive cycle and, along with ultrasound images, indicate that females lay pairs of eggs throughout a winter egg-laying season. This study further highlights how non-lethal investigation methods can be used to investigate the life history of oviparous elasmobranchs in the field. This information will support the identification of important life history groups and their associated habitats, helping to develop management strategies for these species

74th ENMC International Workshop: Mitochondrial Diseases

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Deleterious variants in CRLS1 lead to cardiolipin deficiency and cause an autosomal recessive multi-system mitochondrial disease

Mitochondrial diseases are a group of inherited diseases with highly varied and complex clinical presentations. Here, we report four individuals, including two siblings, affected by a progressive mitochondrial encephalopathy with biallelic variants in the cardiolipin biosynthesis gene CRLS1. Three affected individuals had a similar infantile presentation comprising progressive encephalopathy, bull's eye maculopathy, auditory neuropathy, diabetes insipidus, autonomic instability, cardiac defects and early death. The fourth affected individual presented with chronic encephalopathy with neurodevelopmental regression, congenital nystagmus with decreased vision, sensorineural hearing loss, failure to thrive and acquired microcephaly. Using patient-derived fibroblasts, we characterized cardiolipin synthase 1 (CRLS1) dysfunction that impaired mitochondrial morphology and biogenesis, providing functional evidence that the CRLS1 variants cause mitochondrial disease. Lipid profiling in fibroblasts from two patients further confirmed the functional defect demonstrating reduced cardiolipin levels, altered acyl-chain composition and significantly increased levels of phosphatidylglycerol, the substrate of CRLS1. Proteomic profiling of patient cells and mouse Crls1 knockout cell lines identified both endoplasmic reticular and mitochondrial stress responses, and key features that distinguish between varying degrees of cardiolipin insufficiency. These findings support that deleterious variants in CRLS1 cause an autosomal recessive mitochondrial disease, presenting as a severe encephalopathy with multi-systemic involvement. Furthermore, we identify key signatures in cardiolipin and proteome profiles across various degrees of cardiolipin loss, facilitating the use of omics technologies to guide future diagnosis of mitochondrial diseases.Genome Instability and Cance