Phylogenetic signal at the Cytb-SertRNA-IG1-ND1 mitochondrial region in Anopheles (Kerteszia) neivai Howard, Dyar & Knab, 1913 / Señal filogenética de la región Cytb- SertRNA -IG1-ND1 en Anopheles (Kerteszia) neivai Howard, Dyar & Knab, 1913

Abstract Introduction: Mitochondrial DNA has proven its utility for the study of insect evolution. Genes such as cytochrome b (Cytb) and the transfer gene for serine (SertRNA) can be used to compare closely related organisms. Objective: The phylogenetic utility of Cytb-SertRNA-IG1-ND1 was tested for polymorphisms, and secondary structure modeling in SertRNA was done to detect possible cryptic species in Anopheles neivai. Materials and methods: Specimens from Colombia, Guatemala, and the type locality in Panamá were collected and sequenced for specimen comparison based on DNA polymorphisms, and secondary structure modeling for the SertRNA gene. Results: Thirty-six sequences for A. neivai and A. pholidotus were obtained. Conclusions: Polymorphic variants were detected in A. neivai for Cytb-SertRNA-IG1- ND1. Despite this variation in A. neivai, cryptic species could not be detected.

Resumen Introducción. El ADN mitocondrial ha demostrado su utilidad para el estudio de la evolución en los insectos. Existen algunos genes mitocondriales como el citocromo b (Cytb) y el gen de transferencia para el aminoácido serina (SertRNA) que pueden usarse en el diagnóstico de especies estrechamente relacionadas. Objetivo. Explorar la utilidad filogenética de la región Cytb-SertRNA-IG1-ND1 para detectar posibles especies crípticas en Anopheles neivai. Materiales y métodos. Se recolectaron especímenes en Colombia, Guatemala y en la localidad tipo en Panamá, los cuales se secuenciaron y se compararon mediante el polimorfismo de ADN en toda la región y mediante la simulación de estructuras secundarias del gen SertRNA. Resultados. Se obtuvieron las secuencias de especímenes de A. neivai (34) y A. pholidotus (2). Conclusiones. Se detectaron algunos polimorfismos para la regiónCytb-SertRNA-IG1-ND1 en A. neivai, pero no así especies crípticas.

Mutations of mitochondrial tRNAand their connection with hearing loss / 中华医学遗传学杂志

Mitochondrial tRNAgene mutation is closely related to acoustic nerve deafness. Some mutations can affect the structure and transcriptional processing of tRNA, for instance m.7444G>A mutation in tRNAprecursor 3' side, m.7472 insC as well as m.7511T>C mutations in the stem and ring of tRNA, may influence tRNAstability, thus affect the synthesis of mitochondrial peptides, reduce the production of ATP and cause deafness. This article focuses on mitochondrial tRNAgene mutations as well as the mechanism underlying hearing loss.

mtDNA mutations, hearing loss and aminoglycoside treatment in Mexicans / Mutações em DNA mitocondrial, hipoacusia e tratamento de mexicanos com aminoglicosídeos

Streptomycin and aminoglycoside derivatives are commonly used to treat tuberculosis and other stubborn infections; these drugs may alter auditory and/or vestibular function. Mutations in mitochondrial DNA have been associated with hypersensitivity to aminoglycosides; no studies have been conducted in Mexicans, which are very prone to such alterations because aminoglycosides have been prescribed carelessly for many years, irrespective of the ailment to be treated. AIM: We investigated "hot spot" mutations described previously as causing inner ear alterations. METHODS: Hot spot mutations at the 12S rRNA gene and the tRNA Serine (UCN) gene were screened by PCR-RFLP and sequencing in 65 subjects undergoing audiological and vestibular testing. STUDY DESIGN: Experimental. RESULTS: 32 individuals had healthy auditory and vestibular function, whereas 33 subjects had auditory affections. We found none of the previously reported mutations related to aminoglycoside hypersensitivity, or non-syndromic hearing loss. Two hearing-impaired patients that had been treated with streptomycin had the T1189C variant of the mitochondrial 12S rRNA region. CONCLUSION: Mutations related to hearing loss in other ethnic backgrounds were not found in Mexicans. However, the T1189C variant is possibly a putative mutation related to aminoglycoside hypersensitivity and was present in 2 patients.

Derivados de aminoglicosídeos e estreptomicina são comumente utilizados para tratar tuberculose e outras infecções mais resistentes; esses medicamentos podem alterar a função vestibular e/ou auditiva. Mutações no DNA mitocondrial têm sido associadas à hipersensibilidade a aminoglicosídeos; não há estudos conduzidos com mexicanos, que são muito predispostos a tais alterações, uma vez que aminoglicosídeos têm sido exageradamente prescritos há anos, sem associações à doença sendo tratada. OBJETIVO: investigamos mutações "hot spot" previamente descritas como causas de alterações no ouvido interno. MÉTODOS: Mutações hot spot no gene 12S rRNA e gene SerinatRNA (UCN) foram triados pela PCR-RFLP e sequenciados em 65 indivíduos sujeitos a exames audiométricos e vestibulares. Desenho do estudo: Experimental. RESULTADOS: 32 indivíduos com funções auditiva e vestibular normais, e 33 indivíduos com doenças auditivas. Não encontramos nenhuma das mutações previamente relatadas como associadas à hipersensibilidade aos aminoglicosídeos, ou perda auditiva não-sindrômica. Dois pacientes com hipoacusia que haviam sido tratados com estreptomicina tinham a variante T1189C na região 12S rRNA. CONCLUSÃO: Mutações associadas à hipoacusia em outras etnias não foram encontradas em mexicanos. Entretanto, a variante T1189C é possivelmente uma mutação associada à hipersensibilidade a aminoglicosídeos, e esteve presente em dois pacientes.

Prevalence of the A1555G (12S rRNA) and tRNA Ser(UCN) mitochondrial mutations in hearing-impaired Brazilian patients

Mitochondrial mutations are responsible for at least 1 percent of the cases of hereditary deafness, but the contribution of each mutation has not yet been defined in African-derived or native American genetic backgrounds. A total of 203 unselected hearing-impaired patients were screened for the presence of the mitochondrial mutation A1555G in the 12S rRNA gene and mutations in the tRNA Ser(UCN) gene in order to assess their frequency in the ethnically admixed Brazilian population. We found four individuals with A1555G mutation (2 percent), which is a frequency similar to those reported for European-derived populations in unselected samples. On the other hand, complete sequencing of the tRNA Ser(UCN) did not reveal reported pathogenic substitutions, namely A7445G, 7472insC, T7510C, or T7511C. Instead, other rare substitutions were found such as T1291C, A7569G, and G7444A. To evaluate the significance of these findings, 110 "European-Brazilians" and 190 "African-Brazilians" unrelated hearing controls were screened. The T1291C, A7569G and G7444A substitutions were each found in about 1 percent (2/190) of individuals of African ancestry, suggesting that they are probably polymorphic. Our results indicate that screening for the A1555G mutation is recommended among all Brazilian deaf patients, while testing for mutations in the tRNA Ser(UCN) gene should be considered only when other frequent deafness-causing mutations have been excluded or in the presence of a maternal transmission pattern.

Mutation analysis of 12S rRNA and tRNA-Ser(UCN) genes in a large Chinese family with maternally inherited nonsyndromic hearing loss by intermarriage / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the possible mutation at possible sites in different mitochondrial genes that leads to hearing loss in a large Chinese pedigree.</p><p><b>METHODS</b>Blood samples from a Hunan pedigree were obtained with informed consent. Genomic DNA was extracted from peripheral blood leukocytes using kit. The target fragments were amplified and detected by polymerase chain reaction (PCR) and directly sequencing respectively.</p><p><b>RESULTS</b>The result of direct sequencing revealed the A1555G mutation in 12S rRNA gene was inherited in this pedigree and no one has A7445G mutation or other mutations in its neighborhood region.</p><p><b>CONCLUSION</b>Sequence analysis confirmed that the pedigree carries the A1555G mutation. With some members ever exposure of aminoglycoside antibiotics, mutation of A1555G may play a pivotal role in the pathogenesis of hearing loss in the large pedigree.</p>

Screening for mitochondrial DNA mutation in two pedigrees with nonsyndromic inherited sensorineural hearing loss / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the genetic mechanism of maternal nonsyndromic inherited sensorineural hearing loss(SNHL), to identify the incidence of the 7445(G) mutation in such pedigrees and sporadic patients with SNHL, and to provide the theoretical evidence for the diagnosis of this disease.</p><p><b>METHODS</b>Blood samples were obtained from 2 pedigrees and 14 sporadic patients with SNHL. DNA was extracted from the isolated leukocytes. The mitochondrial DNA (mtDNA) fragments were amplified by PCR. The 1555(G), 3243(G) and 7445(G) mutation was detected by Alw 26 I, Apa I and Xba I restriction endonuclease digestion respectively. The sequence of 12S rRNA, tRNA(Leu(UUR)) and tRNA(Ser(UCN)) was examined.</p><p><b>RESULTS</b>Restriction endonuclease digestion analysis showed that 12 individuals from 2 pedigrees carried homoplasmic 7445(G) mutation, which was of maternal inheritance. Six individuals from 2 pedigrees and 14 sporadic patients did not have 7445(G) mutation. All individuals did not have 1555(G) and 3243(G) mutation. The sequence analysis further showed that none of them carried homoplasmic 1555(G) and 3243(G) mutation, 12 individuals had (nt)7445 A--> G substitution in tRNA(Ser(UCN)) gene.</p><p><b>CONCLUSION</b>The incidence of 7445(G) mutation in such pedigrees is higher than that in sporadic patients. Screening for mtDNA 7445(G) mutation combined with 1555(G) examination is of much value to clinical use.</p>