Long term cortical plasticity in visual retinotopic areas in humans with silent retinal ganglion cell loss

Visual cortical plasticity induced by overt retinal lesions (scotomas) has remained a controversial phenomenon. Here we studied cortical plasticity in a silent model of retinal ganglion cell loss, documented by in vivo optical biopsy using coherence tomography. The cortical impact of non-scotomatous subtle retinal ganglion cell functional and structural loss was investigated in carriers of the mitochondrial DNA 11778G > A mutation causing Leber's hereditary optic neuropathy. We used magnetic resonance imaging (MRI) to measure cortical thickness and fMRI to define retinotopic cortical visual areas V1, V2 and V3 in silent carriers and matched control groups. Repeated Measures analysis of variance revealed a surprising increase in cortical thickness in the younger carrier group (below 21 years of age). This effect dominated in extrastriate cortex, and notably V2. This form of structural plasticity suggests enhanced plastic developmental mechanisms in extrastriate retinotopic regions close to V1 and not receiving direct retinocortical input

Towards honey authentication: Differentiation of Apis mellifera subspecies in European honeys based on mitochondrial DNA markers

Honey is the natural sweet substance produced by Apis mellifera honeybees in Europe. Depending on the country/region, the A. mellifera subspecies native to Europe belong to three different lineages: A (A. m. iberiensis), M (A. m. iberiensis and A. m. mellifera) and C (A. m. ligustica and A. m. carnica). In this work, two DNAbased approaches were developed with the aim of entomological authentication of European honeys. A cytb specific PCR assay was proposed to identify A-lineage honeybees, while a second method based on real-time PCR coupled to high resolution melting analysis targeting the COI gene was developed to differentiate C- and Mlineages honeybees. The proposed methodologies were validated successfully with honeys of known origin and applied to the entomological authentication of 20 commercial samples from different European countries. The results highlight the predominance of honeys from C-lineage honeybees in Europe, except in Iberian Peninsula countries (honey from A-lineage honeybees).The authors are grateful to Dora Henriques for assembling the mitogenomes and to Pilar de la Rua and António Pajuelo for supplying authentic honey samples. This work was supported by FCT (Fundação para a Ciência e Tecnologia) through project UID/QUI/50006/2013 – POCI/01/0145/FEDER/007265 with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020 and by the projects NORTE-01-0145- FEDER-000011 and BeeHappy – POCI-01-0145-FEDER-029871 (financed by FEDER through the COMPETE 2020 – Operational Programme for Competitiveness and Internationalisation (POCI) and FCT). S. Soares, L. Grazina and J. Costa are grateful to FCT grants (SFRH/BD/75091/2010, SFRH/BD/132462/2017 and SFRH/BPD/102404/2014, respectively) financed by POPH-QREN (subsidised by FSE and MCTES).info:eu-repo/semantics/publishedVersio

Mitochondrial DNA Variants in a Portuguese Population of Patients with Alzheimer’s Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder associated with dementia in late adulthood. Mitochondrial respiratory chain impairment has been detected in the brain, muscle, fibroblasts and platelets of AD patients, indicating a possible involvement of mitochondrial DNA (mtDNA) in the etiology of the disease. Several reports have identified mtDNA mutations in AD patients, but there is no consensual opinion regarding the cause of the impairment. We have studied mtDNA NADH dehydrogenase subunit 1 nucleotides 3337-3340, searching for mutations. Our study group included 129 AD patients and 125 healthy age-matched controls. We have found alterations in two AD patients: one had two already known mtDNA modifications (3197 T-C and 3338 T-C) and the other a novel transition (3199 T-C) which, to our knowledge, has not been described before

Identification of a novel deletion in SURF1 gene: Heterogeneity in Leigh syndrome with COX deficiency

Leigh syndrome (LS) is a rare, progressive neurodegenerative mitochondrial disorder of infancy. It is a genetically heterogeneous disease. The mutations in SURF1 gene are the most frequently known cause. Here two cases of LS likely caused by SURF1 gene variants are reported: a 39-year-old male patient with a novel homozygous deletion (c.-11_13del), and a case of a 6-year-old boy with the same deletion and a nonsense mutation (c.868dupT), both in heterozygosity. Blue native PAGE showed absence of assembled complex IV. This is the first report of a variant that may abolish the SURF1 gene initiation codon in two LS patients.info:eu-repo/semantics/publishedVersio

mtDNA copy number associated with age of onset in familial amyloid polyneuropathy

background Transthyretin-related familial amyloid polyneuropathy (TTR-Fap Val30Met) shows a wide variation in age-at-onset (aO) between generations and genders, as in portuguese families, where women display a later onset and a larger anticipation (>10 years). Mitochondrial DNa (mtDNa) copy number was assessed to clarify whether it has a modifier effect on aO variability in portuguese patients. Methods The mtDNa copy number of 262 samples (175 Val30Met TTR carriers and 87 controls (proven Val30Val)) was quantified by quantitative real-time pcR. statistical analysis was performed using IBM spss V.23 software. results This study shows that Val30Met TTR carriers have a significantly higher (p<0.001) mean mtDNa copy number than controls. Furthermore, the highest mtDNa copy number mean was observed in early-onset patients (aO <40 years). Importantly, early-onset offspring showed a significant increase (p=0.002) in the mtDNa copy number, when compared with their late aO parents. Conclusions The present findings suggest, for the first time, that mtDNa copy number may be associated with earlier events and may therefore be further explored as a potential biomarker for follow-up of TTR-Fap Val30Met carriers.DS and MA-F are recipients of an FCT fellowship (SFRH/BD /91160/2012 and SFRH/BD/101352/2014, respectively). Our funding sources supported the data collection and analysis, but did not play a role in the study design, in interpretation of data, in the writing of the report or in the decision to submit the paper for publication

Novel diagnostic tools for Asian (Apis cerana) and European (Apis mellifera) honey authentication

Honey can be produced by different species of honeybees, with two being of economic importance due to their use in apiculture, namely Apis mellifera (known as European honeybee) and Apis cerana (known as Asian honeybee). Due to the decline of the wild populations of the Asian honeybee, this honey generally attains much higher market value, being prone to adulteration. This work aims at proposing new tools, based on the use of molecular markers, for the entomological authentication of honey. To this end, new species-specific primers were designed targeting the tRNA leu -cox2 intergenic region and allowing the detection of A. cerana DNA by qualitative polymerase chain reaction (PCR). Additionally, a novel real-time PCR method with high resolution melting analysis was developed to target the 16S rRNA gene of both bee species, allowing their discrimination in different clusters. The proposed methodologies were further applied with success in the authentication of Asian and European honey samples by the identification of honeybee DNA, demonstrating the usefulness of these simple and cost-effective new approaches.We thank Matt Webster from Uppsala University for providing the A. cerana samples from China and Thailand. This work was supported by FCT (Fundação para a Ciência e Tecnologia) through project UID/QUI/50006/2013 – POCI/01/0145/FEDER/007265 with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020 and by the project NORTE-01-0145-FEDER-000011. S. Soares and J. Costa are grateful to FCT grants (SFRH/BD/75091/2010 and SFRH/BPD/102404/2014, respectively) financed by POPH-QREN (subsidised by FSE and MCTES).info:eu-repo/semantics/publishedVersio

Mitochondrial-dependent apoptosis in Huntington's disease human cybrids

We investigated the involvement of mitochondrial-dependent apoptosis in Huntington's disease (HD) vs. control (CTR) cybrids, obtained from the fusion of human platelets with mitochondrial DNA-depleted NT2 cells, and further exposed to 3-nitropropionic acid (3-NP) or staurosporine (STS). Untreated HD cybrids did not exhibit significant modifications in the activity of mitochondrial respiratory chain complexes I-IV or in mtDNA sequence variations suggestive of a primary role in mitochondrial susceptibility in the subpopulation of HD carriers studied. However, a slight decrease in mitochondrial membrane potential and increased formation of intracellular hydroperoxides was observed in HD cybrids under basal conditions. Furthermore, apoptotic nuclei morphology and a moderate increase in caspase-3 activation, as well as increased levels of superoxide ions and hydroperoxides were observed in HD cybrids upon 3-NP or STS treatment. 3-NP-evoked apoptosis in HD cybrids involved cytochrome c and AIF release from mitochondria, which was associated with mitochondrial Bax translocation. CTR cybrids subjected to 3-NP showed increased mitochondrial Bax and Bim levels and the release of AIF, but not cytochrome c, suggesting a different mode of cell death, linked to the loss of membrane integrity. Additionally, increased mitochondrial Bim and Bak levels, and a slight release of cytochrome c in untreated HD cybrids may help to explain their moderate susceptibility to mitochondrial-dependent apoptosi

Brief report: High frequency of biochemical markers for mitochondrial dysfunction in autism: no association with the mitochondrial aspartate/glutamate carrier SLC25A12 gene

In the present study we confirm the previously reported high frequency of biochemical markers of mitochondrial dysfunction, namely hyperlactacidemia and increased lactate/pyruvate ratio, in a significant fraction of 210 autistic patients. We further examine the involvement of the mitochondrial aspartate/glutamate carrier gene (SLC25A12) in mitochondrial dysfunction associated with autism. We found no evidence of association of the SLC25A12 gene with lactate and lactate/pyruvate distributions or with autism in 241 nuclear families with one affected individual. We conclude that while mitochondrial dysfunction may be one of the most common medical conditions associated with autism, variation at the SLC25A12 gene does not explain the high frequency of mitochondrial dysfunction markers and is not associated with autism in this sample of autistic patients