RESUMO
The aetiology of variation in transcription of ribosomal genes is still an open question. Investigations carried out in many organisms showed that the variation depends not only on genetic mechanisms such as rDNA methylation, elimination of rDNA or the position effects. In this review, we discuss the results of the studies on repression of rRNA transcriptional activation from protein factors to conditions of cell culture, which may influence the variation of nucleolar organizer region activity.
Assuntos
RNA Ribossômico/genética , Transcrição Gênica , Região Organizadora do NucléoloRESUMO
In this case report we present a child with an additional chromosome in the karyotype. The karyotypes of the boy and his parents were analyzed by use of a conventional banding technique (GTG) and fluorescence in situ hybridization (FISH). Probes painting whole chromosomes 12 and 18 were used in FISH. Cytogenetic examination of the parents revealed that his mother was carrying balanced reciprocal translocation between chromosomes 12 and 18. Her karyotype was described as 46,XX,t(12;18)(p13;q12). Father's karyotype was normal, described as 46,XY. The boy's karyotype was defined as 47,XY,+der(18)t(12;18)(p13;q12). The additional chromosome appeared probably due to 3:1 meiotic disjunction of the maternal balanced translocation, known as tertiary trisomy. The mother displayed a normal phenotype and delivered earlier a healthy child. However, the boy with the unbalanced karyotype shows multiple congenital abnormalities.
Assuntos
Anormalidades Múltiplas/genética , Aneuploidia , Cromossomos Humanos Par 12/genética , Cromossomos Humanos Par 18/genética , Translocação Genética/genética , Humanos , Hibridização in Situ Fluorescente , Recém-Nascido , Padrões de Herança/genética , Cariotipagem , Masculino , PolôniaRESUMO
An extended definition of the term metabolic engineering is given and its successful use in the construction of biorecognition elements of sensors is demonstrated. It is shown that genetic and chemical modifications of methylotrophic yeast cells provide directed changes in their physiological responses towards methanol, ethanol and formaldehyde resulting in enhanced selectivity and shorter time response of the corresponding potentiometric and amperometric biosensors.
