Abstract
The evolutionary origin and significance of spliceosomal introns have been the subject of many investigations. Two theories, "introns-early" theory and "introns-late" theory, have been proposed to explain the evolution of introns in eukaryotic genes. Intron position is generally conserved in paralogue and orthologue genes. Some introns occur at similar but not necessarily identical positions in homologous genes, which were separated by great evolutionary distances. This event can be explained by insertion, loss or movement of the intron over short distances. Intron loss and gain events are unique in evolution and can be useful as markers for phylogenetic analyses. The insertion of introns at an identical position suggests a common ancestor gene. Here we analyzed, using PCR and RT-PCR, the structure of the 1,3-beta-glucan synthase gene (FKS) in several clinical isolates of Paracoccidioides brasiliensis (Pb): isolates Pb 01, Pb 4940, Pb 8515, Pb 8311, Pb 8334, Pb 4268, Pb 1668, and Pb E. Our results showed that seven of the isolates examined showed identical structures concerning the position of introns in PbFKS1. PbFKS4940 showed the intron described at the 3' end and had lost that one at the 5' end. The presence of the PbFKS4940 transcript suggests that it could be a functional gene. These data suggest a divergent evolution for introns with regard to the 1,3-beta-glucan synthase gene in P. brasiliensis isolates.
Highlights
Gastroenterology Medicine & ResearchGMR.000610. 5(2).2020 to study performed by Collins, in histopathological examination of 50000 vermicular appendixes, adenocarcinomas were found in 41 specimens [4]
Low-grade appendiceal mucinous neoplasm (LAMN) describes a neoplasm with dysplastic epithelium producing abundant mucin (Figure 3)
They were reexamined by the Head of the Pathological Department, who diagnosed low grade appendiceal mucinous neoplasm (LAMN)
Summary
GMR.000610. 5(2).2020 to study performed by Collins, in histopathological examination of 50000 vermicular appendixes, adenocarcinomas were found in 41 specimens [4]. 5(2).2020 to study performed by Collins, in histopathological examination of 50000 vermicular appendixes, adenocarcinomas were found in 41 specimens [4]. In retrospective clinicopathological analysis by Machado et al adenocarcinomas were diagnosed in 2 out of 1646 vermicular appendixes. The first adenocarcinoma of the appendix was described in 1882 by Berger [5]. Since that moment in literature there were 250 cases described worldwide [6,7]. Usual onset of the disease is 40-80 years of age [8]. It is usually diagnosed incidentally at histologic assessment of the surgical specimen collected during appendectomy due to appendicitis (Figure 2). Following histopathological types of malignant tumors of the appendix can be distinguished: 1. Following histopathological types of malignant tumors of the appendix can be distinguished: 1. Colonic-type adenocarcinoma
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