Altered RNA structural constituents in aging and vitamin E deficiency.

Ribonucleoprotein (RNP) containing structural constituents in hepatocyte nuclei of adult, old and adult, vitamin E-deficient rats were investigated to assess the effect of aging and increased oxidative stress on nuclear functions. Fibrillar centres (FCs), dense fibrillar (DFC) and granular (GC) components of nucleoli as well as perichromatin granules (PGs) in the nucleoplasm were preferentially evidenced by the ethylenediaminetetracetic acid (EDTA) method and measured by computer-assisted morphometric procedures. FCs size and the percentage of nucleolar surface occupied by FCs significantly decreased during aging and vitamin E-deficiency. The percentage of nucleolar surface occupied by GC and DFC remained unchanged in adult and old rats, but in vitamin E-deficient animals GC increased and DFC decreased significantly. PG density significantly changed in aging and vitamin E-deficiency. Functionally, FCs, DFC and GC constitute sites of transcription and processing of ribosomal RNA while PGs are involved in intranuclear storage and transport of messenger RNA. Thus, the present structural changes during aging and vitamin E-deficiency correlate with a decay of nuclear responsiveness to cellular metabolic needs. Considering the antioxidant action of alpha-tocopherol, our data lend further support to the importance of free radical production and control in the aging process.

Ultrastructural analysis of pancreatic acinar cells from mice fed on genetically modified soybean.

No direct evidence that genetically modified (GM) food may represent a possible danger for health has been reported so far; however, the scientific literature in this field is quite poor. Therefore, we investigated the possible effects of a diet containing GM soybean on mouse exocrine pancreas by means of ultrastructural, morphometrical and immunocytochemical analyses. Our observations demonstrate that, although no structural modification occurs in pancreatic acinar cells of mice fed on GM soybean, quantitative changes of some cellular constituents take place in comparison to control animals. In particular, a diet containing significant amount of GM food seems to influence the zymogen synthesis and processing.

Ultrastructural morphometrical and immunocytochemical analyses of hepatocyte nuclei from mice fed on genetically modified soybean.

No direct evidence that genetically modified (GM) food may represent a possible danger for health has been reported so far; however, the scientific literature in this field is still quite poor. Therefore, we carried out an ultrastructural morphometrical and immunocytochemical study on hepatocytes from mice fed on GM soybean, in order to investigate eventual modifications of nuclear components of these cells involved in multiple metabolic pathways related to food processing. Our observations demonstrate significant modifications of some nuclear features in GM-fed mice. In particular, GM fed-mice show irregularly shaped nuclei, which generally represents an index of high metabolic rate, and a higher number of nuclear pores, suggestive of intense molecular trafficking. Moreover, the roundish nucleoli of control animals change in more irregular nucleoli with numerous small fibrillar centres and abundant dense fibrillar component in GM-fed mice, modifications typical of increased metabolic rate. Accordingly, nucleoplasmic (snRNPs and SC-35) and nucleolar (fibrillarin) splicing factors are more abundant in hepatocyte nuclei of GM-fed than in control mice. In conclusion, our data suggest that GM soybean intake can influence hepatocyte nuclear features in young and adult mice; however, the mechanisms responsible for such alterations remain unknown.