Mitochondrial DNA analysis confirms the existence of two glacial races of rainbow smelt
            Osmerus mordax
            and their reproductive isolation in the St Lawrence River estuary (Quebec, Canada)

Ecological isolation through resource partitioning is invoked as a major factor for explaining the persistence of genetically distinct yet closely related sympatric populations. Two genetically distinct sympatric populations of anadromous rainbow smelt (Osmerus mordax) exist in the middle estuary of the St. Lawrence River. The persistence of these coexisting populations in sympatry is in conflict with current theoretical concepts predicting population richness. In the present study, we performed mtDNA PCR-RFLP analysis of 922 larvae from 33 sampling stations to test the hypothesis that the larvae belonging to the two sympatric smelt populations of the St. Lawrence middle estuary are spatially segregated and that such segregation may promote the persistence of the populations. Results clearly revealed spatial homogeneity in the relative distribution of larvae from the two populations. Consequently, they did not support our working hypothesis that larvae belonging to the two sympatric smelt populations are spatially segregated. Two alternative explanations may account for the lack of spatial partitioning observed here. Competition may not be important enough to promote resource partitioning at the larval stage. Alternatively, resource partitioning occurs, but not spatially. This study also demonstrated that the effect of historical events may have been as important as contemporary ecological settings in determining genetic population structure in smelt.

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Leber Hereditary Optic Neuropathy - Idebenone, Hope of Treatment

Revista de Chimie ◽

10.37358/rc.19.12.7740 ◽

2020 ◽

Vol 70 (12) ◽

pp. 4244-4247

Keyword(s):

Mitochondrial Dna ◽

Visual Field ◽

Optic Neuropathy ◽

Mitochondrial Function ◽

Dna Analysis ◽

Central Vision ◽

Leber Hereditary Optic Neuropathy ◽

Mitochondrial Dna Analysis ◽

Hereditary Optic Neuropathy

Leber hereditary optical neuropathy (LHON) is part of the class of optic neuropathies in which the mitochondrial function is impaired and is characterized by a painless, subacute, bilateral decrease of the central vision. We shall present the case of two brothers AM aged 31 and AT aged 40 who were diagnosed with LHON and whom we initiated treatment with idebenone 900 mg / day with monitoring at one month and 6 months. The mitochondrial DNA analysis demonstrated the existence of mutations 11778G>A for the mtND4 gene in both patients. Idebenone is a synthetic benzoquinone, analogue of ubiquinone. We found a slight but significant improvement in the visual field in patient AM at one month of treatment. We have not found another case in the literature with an improvement in vision so fast after this treatment, and this has led us to write this article. Keywords: Leber hereditary optical neuropathy (LHON), idebenone, mutations 11778G>A, mtND4 gene

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