RESUMEN
In most of the studied organisms, gene expression is associated with a number of evolutionary features pertaining to the protein-coding sequences. In particular, gene expression positively correlates with the average intensity of negative selection and influences codon usage. Here, we study the connection between gene expression and selection patterns in two species of ciliate protists of the genus Euplotes. We find that codon usage is influenced by gene expression in these organisms, pointing at additional evolutionary constraints on mutations in heavily expressed genes relative to the genes expressed at lower rates. At the same time, at the level of synonymous vs. non-synonymous substitutions we observe a stronger constraint on the genes expressed at lower rates relative to those with higher rates of expression. Our study adds to the discussion about the general evolutionary patterns and opens new questions about the mechanisms of control of gene expression in ciliates.
Asunto(s)
Euplotes , Codón , Euplotes/genética , Mutación , Expresión GénicaRESUMEN
Due to the high incidence of head and neck cancer and under-diagnosis in the early stages, non-invasive and highly accurate diagnostic tests are required for cancer detection. Recent advances in Raman spectroscopy techniques have yielded promising sensitivity and specificity results in the evaluation of cancer. The aim of this study was to investigate the potential value of Raman spectroscopy in oral cavity and oropharyngeal cancer diagnosis based on currently available scientific papers. A search of the PubMed database was performed using a specific strategy and according to the PRISMA guidelines. Raman spectroscopy achieved a maximum accuracy of 98% in cancer detection, while accuracy was 97.24% for tumour grading evaluation, 95% for cancer treatment assessment, and 77% for the detection of cancer recurrence. Moreover, early-stage cancer can be identified by Raman spectroscopy investigation of liquid biopsy samples. An in vivo technique with direct mucosa examination by fibre-optic Raman spectroscopy obtained a maximum accuracy of 94% in cancer diagnosis. The most prominent markers of the presence of malignancy were an increase in Raman signal intensity for proteins, nucleic acids, and water and a decrease for lipids. These cancer discriminants were detected in both fingerprint and high wavenumber regions. In conclusion, Raman spectroscopy is a promising tool for oral cavity and oropharyngeal cancer screening.
Asunto(s)
Neoplasias Orofaríngeas , Espectrometría Raman , Humanos , Espectrometría Raman/métodos , Recurrencia Local de Neoplasia , Neoplasias Orofaríngeas/diagnóstico , Detección Precoz del Cáncer , BocaRESUMEN
Bacterial chromosomes are widely thought of as circular DNA molecules. However, linear bacterial chromosomes, as well as linear mitochondrial and plastid chromosomes, are fairly common. The most frequent causes of linearization are reparation system defects, incorporation of plasmids in the genome, and recombination compromising the circular topology of chromosomes. Genomes of some bacterial species had undergone frequent linearization-circularization events, which resulted in an increased variability of gene content at linear chromosome ends. Similarly to eukaryotes, bacteria that have linear genomes face the problem of end replication, which different species solve in a variety of ways. A theoretically important issue is the adaptive value of chromosome linearization. This review discusses theories concerning the evolution of linear genomes and supporting experiments. The most common mechanisms of linear bacterial genomes replication and possible ways of their emergence are also considered.