Assisted quantification of abdominal adipose tissue based on magnetic resonance images

An assisted method to segment Visceral Adipose Tissue (VAT) and Subcutaneous Adipose Tissue (SAT) from Magnetic Resonance Imaging (MRI) slices is presented. The segmentation process, called shape-based segmentation, consists in three main steps: 1) to draw a series of closed curves at different slices that separates the abdominal structures of interest, 2) to generate a 3D model from the closed curves for each abdominal structure by using shape-based interpolation and 3) to apply a segmentation algorithm to define the adipose tissue. The 3D models considerably simplify the problem since the abdominal structures are separated, and in turn, this reduces the possibility of large segmentation errors. In addition, a fully automatic segmentation procedure was also implemented. Twenty slices of MRI at the abdominal region for each of twelve subjects were analysed. The results of the shape-based and automatic segmentation were compared with the expert segmentation carried out in the slice located at the umbilicus level. Correlation Coefficient (CC) and volume error (VE) were used as performance measures. The comparison between the expert and shape-based segmentation for SAT yielded results of CC= 0.974 and VE=-0.01 ± 5.8 cm3, while for VAT the performance indexes were CC= 0.993 and VE= 0.9 ± 1.8 cm3. The results suggest that the shape-based segmentation provides an accurate and simple assessment of the abdominal adiposity with minimal human intervention and it could be used as a simple tool in clinics

Insertionslinien als Werkzeuge für funktionelle Genomforschung

Huep G, Kleinbölting N, Appelhagen I, Viehöver P, Weisshaar B. Insertionslinien als Werkzeuge für funktionelle Genomforschung. BIOspektrum. 2013;19(6):639-641

Identification of a splicing coactivator gene that affects the production of ochratoxin a in Aspergillus carbonarius

Ochratoxin A is a mycotoxin produced by some fungi species. Among them, Aspergillus carbonarius is considered a powerful producer. Genes involved in the ochratoxin A biosynthesis pathway have been identified in some producer species. However, there are few studies that purpose to identify these genes in A. carbonarius. The use of insertion mutants to identify genes associated with certain properties has been increased in the literature. In this work, the region of T-DNA integration was investigated in one A. carbonarius ochratoxin-defective mutant previously obtained by Agrobacterium tumefaciens-mediated transformation, in order to find an association between interrupted gene and the biosynthesis of ochratoxin A. The integration occurred in a gene that possibly encodes a splicing coactivator protein. The analysis of the relative expression of the splicing coativator gene from A. carbonarius wild type strain in four different media showed high correlation between the transcript levels and the ochratoxin A production.<br>A ocratoxina A é uma micotoxina frequentemente encontrada em uma grande variedade de produtos alimentares e apresenta efeitos nefrotóxicos e potencial carcinogênico para animais e humanos. É naturalmente produzida por algumas espécies fúngicas, como Aspergillus carbonarius, que é considerado um potente produtor. Apesar disso, o número de estudos que visam identificar genes que são essenciais para a biossíntese de ocratoxina em A. carbonarius é ainda reduzido. Um mutante de A. carbonarius com baixa produção de ocratoxina A previamente obtido por transformação mediada por Agrobacterium tumefaciens foi investigado com o objetivo de encontrar uma associação entre o gene interrompido e a biossíntese desta micotoxina. Os resultados mostraram a ocorrência de uma junção não exata entre o T-DNA e o DNA genômico do fungo durante o evento de integração. A integração do T-DNA no genoma do mutante T188 provocou deleção de 727 nucleotídeos. Esta deleção inclui uma porção final do gene coativador de splicing e uma região não-codificante entre este gene e o gene F-actina. A expressão relativa do gene coativador de splicing na linhagem selvagem cultivada em quatro diferentes meios mostrou associação entre a quantidade de ocratoxina A e os níveis dos transcritos