Search results for "nuclei"
showing 10 items of 1273 documents
Genes, genomes, and codes : revisiting some key terms with multiple meanings
2015
Is a genome the full complement of an organism?s genes or of its DNA? Is genetics the study of genes or of heredity? Is the genetic code the mechanism for translating nucleotide sequence to amino acid sequence or to phenotype? Does «genetic information» refer to the sequences coding for proteins or to all DNA sequences? Each of these questions stems from an elision between one, concrete, meaning, and another, open-ended and ambiguous. Such elision invites the illusion that the ambiguity of the open-ended term has been resolved, and by implication, that the gap between actual achievement and promise has been closed. Yet, despite the phenomenal progress molecular biology has made, we remain w…
Does the VP1 gene of foot-and-mouth disease virus behave as a molecular clock?
1992
We have carried out a phylogenetic study of the evolution of the VP1 gene sequence from different serological types and subtypes of foot-and-mouth disease virus (FMDV). The maximum-likelihood method developed by Hasegawa and co-workers (Hasegawa et al. 1985) for the estimation of evolutionary parameters and branching dates has been used to decide between alternative models of evolution: constant versus variable rates. The results obtained indicate that a constant rate model, i.e., a molecular clock, seems to be the most plausible one. However, additional information suggests the possibility that the appearance of serotype CS has been accompanied by an episode of rapid evolution (Villaverde …
2019
Codon composition, GC content and local RNA secondary structures can have a profound effect on gene expression, and mutations affecting these parameters, even though they do not alter the protein sequence, are not neutral in terms of selection. Although evidence exists that, in some cases, selection favours more stable RNA secondary structures, we currently lack a concrete idea of how many genes are affected within a species, and whether this is a universal phenomenon in nature. We searched for signs of structural selection in a global manner, analysing a set of 1 million coding sequences from 73 species representing all domains of life, as well as viruses, by means of our newly developed s…
Molecular Evolution of the Globin Gene Cluster E in Two Distantly Related Midges, Chironomus pallidivittatus and C. thummi thummi
1998
We have studied the evolutionary dynamics of a cluster of insect globin genes by comparing the organization and sequence of the gene group in two distantly related species, Chironomus pallidivittatus and C. t. thummi. Although the general architecture of the globin gene cluster has been conserved, we have found an additional, previously undescribed gene (named Cpa F) in C. pallidivittatus which shows signs of accelerated sequence evolution at nonsynonymous codon positions. This new gene is clearly functional, as demonstrated by Northern analysis. Comparison of paralogous and orthologous genes reveals patterns of intraspecific sequence homogenization. The head-to-head-oriented globin 3 and 4…
Sequence of rat cDNA clone pLR 112 coding for the RT1.D 1 chain
1990
Forced Retroevolution of an RNA Bacteriophage
2000
AbstractThe operator hairpin ahead of the replicase gene in RNA bacteriophage MS2 contains overlapping signals for binding the coat protein and ribosomes. Coat protein binding inhibits further translation of the gene and forms the first step in capsid formation. The hairpin sequence was partially randomized to assess the importance of this structure element for the bacteriophage and to monitor alternative solutions that would evolve on the passaging of mutant phages. The evolutionary reconstruction of the operator failed in the majority of mutants. Instead, a poor imitation developed containing only some of the recognition signals for the coat protein. Three mutants were of particular inter…
Molecular cloning ofTrichophyton mentagrophytes DNA sequences with promoter activity inEscherichia coli
1992
A promoter probe library from the dermatophyte fungusTrichophyton mentagrophytes has been constructed in the pVB32 plasmid vector. Using this library, a set ofT. mentagrophytes DNA sequences with promoter activity inEscherichia coli has been cloned. The size and the resistance phenotype conferred by these DNA fragments varied. Southern blot analysis confirmed that they were derived fromT. mentagrophytes genomic DNA.
A method to isolate cDNA-quality RNA from adult conifer needles and a psbA cDNA from Norway spruce
1996
Summary In order to investigate the expression of the psbA gene in damaged and undamaged Norway spruce trees ( Picea abies ) a cDNA clone encoding the D1 protein was isolated via RT-PCR. Applying a method developed by Schneiderbauer et al. (1991) with some modifications, we were able to obtain the required RNA from mature needles and successfully reverse transcribe it into cDNA. Sequence analysis of the cDNA clone revealed an open reading frame (ORF) encoding a 353 amino acid polypeptide that is highly homologous to the D1 protein sequences deduced from higher plant psbA genes. A 4 bp insertion, directly following the stop codon ochre (TAA), was found by comparison with two Pinus species, t…
Basic issues in forensic DNA typing
1997
DNA analysis has become the standard method in forensic stain typing (termed DNA profiling). In contrast to conventional serological methods, any human tissue or body fluid can be analysed by DNA profiling as long as it contains nucleated cells. The majority of genetic systems studied at the DNA level are derived from "non-coding" portions from the human genome, and are located either in the vicinity of expressed (coding) genes or in stretches of DNA sequences interspersing with the genes. The typing results are usually recorded as DNA fragment lengths or "alleles" indicating the number of core repeat elements for short tandem repeat systems. These typing results do not contain any useful i…