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21.
Evolution of the WANCY region in amniote mitochondrial DNA 总被引:6,自引:1,他引:6
In most vertebrate mitochondrial genomes, the site for initiation of
light-strand replication, OL, is found within a cluster of five transfer
RNA (tRNA) genes (tRNA(Trp), tRNA(Ala), tRNA(Asn), tRNA(Cys), and
tRNA(Tyr)). This region and part of the adjacent cytochrome c oxydase
subunit I (COI) gene were sequenced for two crocodilian, two turtle, and
one snake species and for Sphenodon punctatus; part of the adjacent
nicotinamide adenine dinucleotide dehydrogenase subunit 2 (ND2) gene was
also sequenced for the crocodilian and turtle species. All had the typical
vertebrate gene order. The turtles and the snake have a lengthy noncoding
sequence between the tRNA(Asn) and tRNA(Cys) genes that we assumed to be
homologous to the mammalian OL. The crocodilians and Sphenodon lack such a
sequence, a condition they share with birds. Most proposed phylogenies for
the amniotes require that OL at this position was lost at least twice
during their diversification or was evolved independently more than once.
Within the five tRNA genes, frequencies of substitutions are much higher in
loops than in stems. Many loops vary dramatically in size among the
species; in the most extreme case, the D-arm of the Sphenodon tRNA(Cys) is
a "D-arm replacement" loop of seven nucleotides. Frequency of transitions
in stems is relatively uniform across tRNAs, but frequency of transversions
varies greatly. Mismatches in stems are infrequent, and their relative
frequency in a specific tRNA is unrelated to the frequency of substitution
in the corresponding gene. Several features of mammalian mitochondrial
tRNAs are conserved in WANCY tRNAs throughout amniotes. The inferred
initiation codon for COI is GTG in crocodilians, turtles, and the snake, a
condition they share with fishes, certain amphibians, and birds. TTG
appears to be the initiation codon for COI in Sphenodon; if correct, this
would be a novel initiation codon for vertebrate mitochondrial DNA.
Phylogenetic analyses of the inferred amino acid sequences of ND2 and COI
support the sister-group relationship of birds and crocodilians and suggest
that mammals are an early derived lineage within the amniotes.
相似文献
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23.
Daniel S. Higginson Alok Sahgal Michael V. Lawrence Sarah Moyer Mihaela Stefanescu Adam K. Willson Bahjat Qaqish Adam Zanation Lawrence B. Marks Seema Garg Bhishamjit S. Chera 《PloS one》2013,8(8)
Background
Radiation retinopathy is a possible post-treatment complication of radiation therapy. The pathophysiologic mechanism is hypothesized to be microvascular in origin, but evidence is limited. In an effort to study retinal oxygenation in these patients, we herein evaluate the repeatability and variability of retinal oximetry measurements in subjects who had previously received radiation and make comparisons to a cohort of unirradiated subjects.Methods
Using retinal oximetry, a non-invasive imaging modality, we performed in vivo measurements of arteriole (SaO2) and venule SO2 (SvO2) in subjects (n = 9, 18 retinas) who had received incidental radiation to their retinas (≥ 45 Gy to one retina) and in healthy subjects (n = 20, 40 retinas). A total of 1367 SO2 observations on 593 vessels in 29 persons were analyzed to assess three sources of variance in vessel SO2: 1) variance in repeated measurements of the same vessel (“repeatability”), 2) variance in different vessels within the same subject (“within-subject variability”), and 3) variance between subjects (“between-subject variability”).Results
Retinal oximetry measurements were highly repeatable in both irradiated patients and unirradiated subjects. The within-subject variability of SvO2 and SaO2 measurements constituted the highest component of variance in both groups and was significantly higher in venules vs. arterioles (relative effect size 1.8, p<0.001) and in irradiated subjects vs. unirradiated subjects (relative effect size 1.6, p<0.001).Conclusions
Retinal oximetry is a highly repeatable technology and can be reliably used to study vascular oxygenation in irradiated subjects. Different vessels within the same subject exhibit a high degree of variability, suggesting that pooled analyses of multiple vessels are most likely to be informative of regional retinal oxygenation. Finally, irradiated subjects exhibited significantly higher within-subject variability in SO2 measurements, suggesting that radiation may cause regional alterations in retinal oxygen delivery and/or metabolism. 相似文献24.
Boutennoune H Qaqish A Al-Aghbar M Abdel-Hafez S Al-Qaoud K 《Parasite (Paris, France)》2012,19(2):183-188
A pre-designed plasmid containing the gene encoding the second subunit of Echinococcus granulosus AgB8 (EgAgB8/2) was used to study the effect of the immunization route on the immune response in BALB/c mice. Mice were immunized with pDRIVEEgAgB8/2 or pDRIVE empty cassette using the intramuscular (i.m.), intranasal (i.n.) or the epidermal gene gun (g.g.) routes. Analysis of the antibody response and cytokine data revealed that gene immunization by the i.m. route induced a marked bias towards a T helper type 1 (Th1) immune response as characterized by high IFN-γ gene expression and a low IgG1/IgG2a reactivity index (R.I.) ratio of 0.04. The i.n. route showed a moderate IFN-γ expression but a higher IgG1/IgG2a R.I. ratio of 0.25 indicating a moderate Th1 response. In contrast, epidermal g.g. immunization induced a Th2 response characterized by high IL-4 expression and the highest IgG1/IgG2a R.I. ratio of 0.58. In conclusion, this study showed the advantage of genetic immunization using the i.m. route and i.n. over the epidermal g.g. routes in the induction of Th1 immunity in response to E. granulosus AgB gene immunization. 相似文献
25.
Trotta MB Serro Azul JB Wajngarten M Fonseca SG Goldberg AC Kalil JE 《Immunity & ageing : I & A》2011,8(1):4
Background
The increase in life expectancy within the general population has resulted in an increasing number of elderly adults, including patients with Down syndrome (DS), with a current life expectancy of about 50 years. We evaluate the parameters of humoral and cellular immune response, the quantitative expression of the regulator of calcineurin1 gene (RCAN1) and the production of cytokines. The study group consisted of adults DS (n = 24) and a control group with intellectual disability without Down syndrome (ID) (n = 21) and living in a similar environmental background. It was evaluated serology, immunophenotyping, the quantitative gene expression of RCAN1 and the production of cytokines. 相似文献26.
27.
Perseus I Missirlis Carri-Lyn R Mead Stefanie L Butland BF Francis Ouellette Rebecca S Devon Blair R Leavitt Robert A Holt 《BMC bioinformatics》2005,6(1):145
Background
To date, 35 human diseases, some of which also exhibit anticipation, have been associated with unstable repeats. Anticipation has been reported in a number of diseases in which repeat expansion may have a role in etiology. Despite the growing importance of unstable repeats in disease, currently no resource exists for the prioritization of repeats. Here we present Satellog, a database that catalogs all pure 1–16 repeat unit satellite repeats in the human genome along with supplementary data. Satellog analyzes each pure repeat in UniGene clusters for evidence of repeat polymorphism. 相似文献28.
29.
Sohrab?P?Shah Yong?Huang Tao?Xu Macaire?MS?Yuen John?Ling BF?Francis?OuelletteEmail author 《BMC bioinformatics》2005,6(1):34
Background
We present a biological data warehouse called Atlas that locally stores and integrates biological sequences, molecular interactions, homology information, functional annotations of genes, and biological ontologies. The goal of the system is to provide data, as well as a software infrastructure for bioinformatics research and development. 相似文献30.
Peri-urban water bodies are at risk from excessive pollution as they are direct sinks for urban effluents. The occurrence of oestrogenic and androgenic endocrine disrupting chemicals (EDCs) in effluents and water bodies around the city of Bulawayo, Zimbabwe, and their effects on wild fish was investigated in 2013. Effluent and water were sampled from sewage treatment plants, an urban stream, and effluent-polluted dams, and were compared with a ‘pristine’ dam upstream of Bulawayo. Organic pollutants were extracted by solid-phase extraction and tested for EDCs using a yeast oestrogen/androgen screen. Oestrogenic and androgenic potencies were expressed as 17β-oestradiol equivalent (EEq) or dihydrotestosterone equivalent (TEq). Tilapia and catfish from the dams were analysed for gonado-somatic indices and testis histopathology. Effluents from STPs, which directly flow into Umguza Dam, had EEq of 33 ng l?1 and 55 ng l?1, respectively. Umguza Dam, Khami Dam and Matsheumhlope Stream had EEqs of 237 ng l–1, 9 ng l?1 and 2 ng l?1, respectively. Androgenic activity was detected in only one STP (TEq = 93 ng l?1). Tilapia sampled from effluent-polluted dams had high incidences of testis-ova, but catfish had no signs of reproductive dysfunction. These findings underscore the need for greater attention to EDCs in developing countries where there is scant literature regarding their occurrence and impacts. 相似文献