Examining the Gm18 and m1G Modification Positions in tRNA Sequences

The tRNA structure contains conserved modifications that are responsible for its stability and are involved in the initiation and accuracy of the translation process. tRNA modification enzymes are prevalent in bacteria, archaea, and eukaryotes. tRNA Gm18 methyltransferase (TrmH) and tRNA m1G37 methyltransferase (TrmD) are prevalent and essential enzymes in bacterial populations. TrmH involves itself in methylation process at the 2'-OH group of ribose at the 18th position of guanosine (G) in tRNAs. TrmD methylates the G residue next to the anticodon in selected tRNA subsets. Initially, m1G37 modification was reported to take place on three conserved tRNA subsets (tRNA(Arg), tRNA(Leu), tRNA(Pro)); later on, few archaea and eukaryotes organisms revealed that other tRNAs also have the m1G37 modification. The present study reveals Gm18, m1G37 modification, and positions of m1G that take place next to the anticodon in tRNA sequences. We selected extremophile organisms and attempted to retrieve the m1G and Gm18 modification bases in tRNA sequences. Results showed that the Gm18 modification G residue occurs in all tRNA subsets except three tRNAs (tRNA(Met), tRNA(Pro), tRNA(Val)). Whereas the m1G37 modification base G is formed only on tRNA(Arg), tRNA(Leu), tRNA(Pro), and tRNA(His), the rest of the tRNAs contain adenine (A) next to the anticodon. Thus, we hypothesize that Gm18 modification and m1G modification occur irrespective of a G residue in tRNAs.

Authentication of Lonicera japonica using bidirectional PCR amplification of specific alleles / 中国中药杂志

<p><b>OBJECTIVE</b>To identify SNP in flos Lonicerae, and authenticate Lonicera japonica from its adulterants and the mixture by using bidirectional PCR amplification of specific alleles (Bi-PASA).</p><p><b>METHOD</b>SNP of L. japonica and its adulterants was identified by using ClustulW to align trnL-trnF sequences of the Lonicera genus from GenBank database. Bi-PASA primer was designed and the PCR reaction systems including annealing temperature optimized. Optimized result was performed in 84 samples to authenticate L. japonica, its adulterants and the mixture.</p><p><b>RESULT</b>When the annealing temperature was 61 degrees C, DNA from L. japonica would be amplified 468 bp whereas PCR products from all of the 9 adulterants were 324 bp. The established method also can detect 5% of intentional adulteration DNA into L. japonica.</p><p><b>CONCLUSION</b>The Bi-SPASA could authenticate L. japonica from its adulterants and the mixture.</p>

Heteroplasmy level of the mitochondrial tRNaLeu(UUR) A3243G mutation in a Chinese family is positively associated with earlier age-of-onset and increasing severity of diabetes / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the mutations of mitochondrial genome in a pedigree with suspected maternally inherited diabetes and deafness and to explore the correlations between the mutations and clinical features.</p><p><b>METHODS</b>Genomic DNA was isolated from blood leucocytes of each member of the pedigree. The mitochondrial genome was amplified with 24-pair primers that could cover the entire mitochondrial DNA. Direct sequencing of PCR products was used to identify any mitochondrial DNA mutations.</p><p><b>RESULTS</b>Family members on the maternal side all harbored the tRNALeu(UUR) A3243G mutation. The paternal side family members did not have the mutation. The age-of-onset of diabetes of the 4 maternal side family members was 15, 41, 44, and 65 years old, and their corresponding heteroplasmy level of the mutation was 34.5%, 14.9%, 14.6%, and 5.9%, respectively. The age-of-onset of diabetes and heteroplasmy level of A3243G mutation were negatively correlated with a correlation coefficient of -0.980 (P = 0.02). Meanwhile, patient with high heteroplasmy level of A3243G mutation had relatively low severity of disease. Moreover, 6 reported polymorphisms and 2 new variants were found.</p><p><b>CONCLUSIONS</b>The main cause of diabetes in this pedigree is the tRNALeu(UUR) A3243G mutation. However, other gene variants may contribute to its pathogenicity. The heteroplasmy level of the tRNALeu(UUR) A3243G mutation is positively associated with earlier age-of-onset and increasing severity of diabetes.</p>

Analysis of mitochondrial DNA gene tRNALeu(UUR) A3243G mutation in diabetic pedigrees / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the clinical characteristics and the prevalence of mitochondrial gene A3243G mutation in diabetic pedigrees.</p><p><b>METHODS</b>Nineteen suspected mitochondrial DNA diabetic family members from three families were recruited. The gene fragment was amplified by PCR, and mutation was detected by direct sequencing.</p><p><b>RESULTS</b>In three pedigrees, the three probands and their mothers were found carrying the most common nt3243A>G mutation. Most of diabetic patients in these families were deaf and diabetes was developed at early age, characterized by impaired beta cell function and low body mass index (BMI).</p><p><b>CONCLUSION</b>The mitochondrial gene A3243G mutation may cause diabetes mellitus and deaf.</p>

A case of maternally inherited diabetes and deafness with rhabdomyolysis / 대한내과학회지

mutation at position 3,243 in the mtDNA-encoded tRNALeu (UUR) gene is associated with the syndrome of maternally inherited diabetes and deafness (MIDD). It is a rare form of diabetes first described in 1992 characterized by maternal relatives with an early middle-aged onset of diabetes, bilateral sensorineural hearing loss, and a normal or low body mass index. A 37-year-old woman was admitted because of general weakness. She had diabetes mellitus (DM) and deafness. Her mother had DM, her second sister had DM and deafness, and her little brother had DM. The molecular genetic analysis identified the A3243G point mutation. In addition, rhabdomyolysis was diagnosed based on the initial laboratory findings and a whole-body bone scan. We report a case of MIDD with rhabdomyolysis due to a low carbohydrate intake and present it with a literature review.

Cucumber chloroplast trnL(CAA) gene: nucleotide sequence and in vivo expression analysis in etiolated cucumber seedlings treated with benzyladenine and light.

The nucleotide sequence of a 714 bp BamHI-EcoRI fragment of cucumber chloroplast DNA was determined. The fragment contained a gene for tRNA(Leu) together with its flanking regions. The trnL(CAA) gene sequence is about 99% in similarity to broad bean, cauliflower, maize, spinach and tobacco corresponding genes. The relative expression level of the gene was determined by Northern (tRNA) gel blot and Northern (total cellular RNA) slot-blot analyses using the trnL gene probe in 6-day old etiolated cucumber seedlings and the seedlings that had been kept in the dark (dark-grown), treated with benzyladenine (BA) and kept in the dark (BA-treated dark-grown), illuminated (light-grown), and treated with BA and illuminated (BA-treated light-grown), for additional 4, 8 or 12 hr. The trnL transcripts and tRNA(Leu) levels in BA-treated dark-grown seedlings were 5 and 3 times higher, respectively after 4 hr BA treatment, while in the BA treated light-grown seedlings the level of trnL transcripts was only 3 times higher and had no detectable effect on mature tRNA(Leu) when compared to the time-4 hr dark-grown seedlings. However, the level of mature tRNA(Leu) did not show marked changes in the light-grown seedlings, whereas the level of trnL transcripts increases 3 times after 8 hr illumination of dark-grown seedlings. These data indicate that both light and cytokinin can signal changes in plastid tRNA gene expression. The possible regulatory mechanisms for such changes are discussed.