Paternal mtDNA and Maleness Are Co-Inherited but Not Causally Linked in Mytilid Mussels

BACKGROUND: In marine mussels of the genus Mytilus there are two mitochondrial genomes. One is transmitted through the female parent, which is the normal transmission route in animals, and the other is transmitted through the male parent which is an unusual phenomenon. In males the germ cell line is dominated by the paternal mitochondrial genome and the somatic cell line by the maternal. Research to date has not allowed a clear answer to the question of whether inheritance of the paternal genome is causally related to maleness. METHODOLOGY/PRINCIPAL FINDINGS: Here we present results from hybrid crosses, from triploid mussels and from observations of sperm mitochondria in fertilized eggs which clearly show that maleness and presence of the paternal mitochondrial genome can be decoupled. These same results show that the female mussel has exclusive control of whether her progeny will inherit the mitochondrial genome of the male parent. CONCLUSIONS/SIGNIFICANCE: These findings are important in our efforts to understand the mechanistic basis of this unusual mode of mitochondrial DNA inheritance that is common among bivalves

Defensome against Toxic Diatom Aldehydes in the Sea Urchin Paracentrotus lividus

Many diatom species produce polyunsaturated aldehydes, such as decadienal, which compromise embryonic and larval development in benthic organisms. Here newly fertilized Paracentrotus lividus sea urchins were exposed to low concentration of decadienal and the expression levels of sixteen genes, implicated in a broad range of functional responses, were followed by Real Time qPCR in order to identify potential decadienal targets. We show that at low decadienal concentrations the sea urchin Paracentrotus lividus places in motion different classes of genes to defend itself against this toxic aldehyde, activating hsp60 and two proteases, hat and BP10, at the blastula stage and hsp56 and several other genes (14-3-3ε, p38 MAPK, MTase, and GS) at the prism stage. At this latter stage all genes involved in skeletogenesis (Nec, uni, SM50 and SM30) were also down-expressed, following developmental abnormalities that mainly affected skeleton morphogenesis. Moreover, sea urchin embryos treated with increasing concentrations of decadienal revealed a dose-dependent response of activated target genes. Finally, we suggest that this orchestrated defense system against decadienal represents part of the chemical defensome of P. lividus affording protection from environmental toxicants

A novel myopathy-associated mitochondrial DNA mutation altering the conserved size of the tRNA(Gln) anticodon loop

We report a novel mitochondrial DNA alteration in a 12-year-old boy with myopathy. We identified a single nucleotide insertion tan adenine) in the mitochondrial tRNA-glutamine gene. This addition of an additional adenine in a polyadenine stretch (at mitochondrial DNA positions 4366-4369), alters the length of the evolutionary conserved anticodon loop from seven to eight bases. the nt-4370 addition was heteroplasmic and was abundant in the patient's muscle. Lower proportions of mutated mitochondrial DNA were observed in skin fibroblasts. but were below delectable levels in while blood cells. A muscle biopsy of the patient showed ragged red fibers and an unusually high percentage of cytochrome c oxidase-deficient fibers (89%). the pathogenicity of the mutation was also evident by the fact that fibers harboring lower levels of the mutation showed normal cytochrome c oxidase activity. the insertion in the anticodon loop of tRNA(Gln) gene identified in our patient may provide a unique tool to study protein synthesis in human mitochondria. ( (C) 2000 Elsevier Science B.V. All rights reserved.Univ Miami, Sch Med, Dept Neurol, Miami, FL 33136 USAUniversidade Federal de São Paulo, Escola Paulista Med, Div Clin Neurol, São Paulo, BrazilDac Med FAMERP, Dept Neurosci, Sao Jose Do Rio Preto, BrazilUniv Miami, Sch Med, Dept Cell Biol & Anat, Miami, FL 33136 USAUniversidade Federal de São Paulo, Escola Paulista Med, Div Clin Neurol, São Paulo, BrazilWeb of Scienc

Mitochondrial DNA defects in Brazilian patients with chronic progressive external ophthalmoplegia

We report herein on eleven Brazilian patients with mitochondrial DNA (mtDNA) deletions, found among thirteen patients with chronic progressive external ophthalmoplegia (CPEO) and ragged-red fibers (RRF). the molecular data was correlated with the morphological and clinical findings. the muscle biopsies were studied by histochemistry, immunohistochemistry and DNA analysis. Muscle mtDNA deletions were mapped and quantitated by Southern blot analysis, polymerase chain reaction and sequencing. of the eleven patients, ten had CPEO without multisystemic involvement and one had Kearns-Sayre syndrome. Three patients had multiple deletions, two of them with no apparent family history. Eight patients showed heteroplasmic single deletions, ranging in length from 2309 to 7566 bp; three of them had the same 'common deletion' of 4977 bp. the proportion of deleted mtDNA ranged from 14 to 89%. Immunohistochemical studies revealed decreased reactivity with the mtDNA-encoded subunit II of cytochrome c oxidase (COX) in all patients, but preserved activity with the nuclear-encoded COX subunit IV in COX-deficient fibers. Two cases presented a few COX-negative fibers with reduced COX IV immunostaining. We found a high frequency of mtDNA deletions in Brazilian patients with CPEO. There was no correlation between clinical severity, morphological findings and the size or amount of the mutated mtDNA in muscle, suggesting that there are still unknown factors influencing the disease phenotype. (C) 1997 Elsevier Science B.V.UNIV MIAMI,SCH MED,DEPT NEUROL,MIAMI,FLUNIV MIAMI,SCH MED,DEPT CELL BIOL & ANAT,MIAMI,FL 33101Web of Scienc

Frequency of dystrophic muscle abnormalities in chronic progressive external ophthalmoplegia: analysis of 86 patients

Background: There are few reports describing the coexistence of dystrophic features with those typical of mitochondrial myopathies in muscle biopsy. A recent study suggested that dystrophic features are frequent in patients with chronic progressive external ophthalmoplegia ( CPEO) with a high mutation load, but the actual frequency of these abnormalities in CPEO remains undetermined.Objective: To review the occurrence of dystrophic abnormalities in a large series of patients with CPEO to assess the frequency of such abnormalities and to verify whether they are correlated with specific mitochondrial DNA ( mtDNA) mutations.Methods: Retrospective survey of case series ( 86 patients with CPEO).Results: Only three cases with dystrophic abnormalities were found: two with a large scale mtDNA deletion and one with the A3251G mutation. All three patients showed predominantly proximal muscular weakness resembling limb girdle muscular dystrophy.Conclusions: Dystrophic abnormalities are rare in CPEO and are not correlated with a specific molecular defect.Universidade Federal de São Paulo, Escola Paulista Med, Dept Neurol, BR-04039032 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, BR-04039032 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Dept Neurol, BR-04039032 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, BR-04039032 São Paulo, BrazilWeb of Scienc