RESUMO
Genes of box C/D small nucleolar RNAs (snoRNAs) were searched for in the genomes of members of all classes of vertebrates that do not belong to placental mammals. A tendency for an increase in the number of copies of snoRNA genes was observed in such vertebrates. This trend was most pronounced in anamnia (amphibians and fish). Box C mutations were found in 14 snoRNAs in all gene copies among all species studied. The role of the described events is discussed.
Assuntos
RNA Nucleolar Pequeno/genética , Animais , Bases de Dados Genéticas , Dosagem de Genes , VertebradosRESUMO
Small nucleolar RNAs (snoRNAs) are an abundant class of non-protein-coding RNAs. In association with proteins they perform two most frequent nucleotide modifications in rRNAs and some other cellular RNAs: 2'-O-ribose methylation and pseudouridylation. SnoRNAs also participate in pre-rRNA cleavage and telomerase functions. Most snoRNAs fall into two families, box C/D and H/ACA, distinguished by the presence of conserved sequence boxes. Although C/D and H/ACA snoRNP proteins contain homologous regions, the assembly of these RNPs significantly differ. In addition, snoRNAs include the RNA component of RNAses P and MRP. The structure and function of small RNPs from Cajal bodies (small organelles associated with nucleoli) similar to snoRNP are also discussed.
Assuntos
RNA Nucleolar Pequeno/classificação , RNA Nucleolar Pequeno/metabolismo , Animais , Corpos Enovelados/genética , Corpos Enovelados/metabolismo , RNA Nucleolar Pequeno/genética , Ribonucleoproteínas Nucleolares Pequenas/genética , Ribonucleoproteínas Nucleolares Pequenas/metabolismoRESUMO
Small nucleolar RNAs (snoRNAs) are one of the most numerous and well-studied groups of non-protein-coding RNAs. In complex with proteins, snoRNAs perform the two most common nucleotide modifications in rRNA: 2'-O-methylation of ribose and pseudouridylation. Although the modification mechanisms and shoRNA structures are highly conserved, the snoRNA genes are surprisingly diverse in organization. In addition to genes transcribed independently, there are genes that are in introns of other genes, form clusters transcribed from a common promoter, or cluster in introns. Interestingly. one type of gene organization usually prevails in different taxa. Vertebrate snoRNAs mostly originate from introns of protein-coding genes; a small group of snoRNAs are encoded by introns of genes for noncoding RNAs.
Assuntos
Nucléolo Celular/metabolismo , Evolução Molecular , RNA Nuclear Pequeno/metabolismo , Animais , Nucléolo Celular/genética , Genes Arqueais , Genes Bacterianos , Genes Fúngicos , Genes de Insetos , Íntrons , Invertebrados , Metilação , RNA Ribossômico/genética , RNA Ribossômico/metabolismo , RNA Nuclear Pequeno/genética , VertebradosRESUMO
AIM: Analysis of the course and rate of progression of morphologically confirmed forms of chronic glonerulonephritis (CGN) with onset in childhood and adolescence (1950 to 2005). MATERIAL AND METHODS: The course of the disease was examined in 110 patients with morphologically verified form of CGN with onset in childhood. Maximal history of CGN was 42 years. RESULTS: CGN was morphologically mesangio-proliferative in 50.9% patients, while nephritis with minimal alterations occurred only in 10% patients. Most of the patients (71; 64.6%) had secondary hypertension, chronic renal failure (39; 35.5%). Programmed hemodialysis was conducted in 14 (12.7%) patients, 10 (9.1%) patients died. Stable dysability developed in 41 (37.3%) patients. The most severe course of the diseases was observed in patients with family history of CGN. CONCLUSION: Recently, CGN with debut in childhood shows a trend to an unfavourable course, had severe manifestations at a disease debut, and progresses rapidly.
Assuntos
Glomerulonefrite/epidemiologia , Glomérulos Renais/patologia , Adolescente , Adulto , Distribuição por Idade , Idade de Início , Biópsia , Criança , Pré-Escolar , Avaliação da Deficiência , Progressão da Doença , Feminino , Seguimentos , Glomerulonefrite/patologia , Glomerulonefrite/reabilitação , Humanos , Masculino , Prevalência , Prognóstico , Estudos Retrospectivos , Federação Russa/epidemiologia , Taxa de Sobrevida , Fatores de TempoRESUMO
The vast majority of C/D box small nucleolar RNAs (snoRNAs) direct site-specific methylation of ribose in rRNA. New mammalian snoRNA U87 belongs to the C/D family and is involved in ribose methylation of guanylic acid residue (position 3468) in 28S rRNA. A host gene harboring the U87 snoRNA gene in its intron was described for rodents and humans. In humans it has three neighbouring transcription start sites whereas in rat there are many scattered start sites. The transcript of this gene possesses some characteristic features of an mRNA (splicing, polyadenylation and cytoplasmic localization) but lacks long open reading frames and the degree of its conservation is much less than that of other host gene mRNAs. Such low conservation is discussed in the context of functional significance of exonic sequences of the gene.