1,720,980 research outputs found
Nuclei of aged myofibres undergo structural and functional changes suggesting impairment in RNA processing
No full textAdvancing adult age is associated with a progressive decrease in skeletal muscle mass, strength and quality known as sarcopenia. The mechanisms underlying age-related skeletal muscle wasting and weakness are manifold and still remain to be fully elucidated. Despite the increasing evidence that the progress of muscle diseases leading to muscle atrophy/dystrophy may be related to defective RNA processing, no data on the morpho-functional features of skeletal muscle nuclei in sarcopenia are available at present. In this view, we have investigated, by combining morphometry and immunocytochemistry at light and electron microscopy, the fine structure of myonuclei as well as the distribution and amount of RNA processing factors in skeletal myofibres of biceps brachii and quadriceps femoris from adult and old rats. Results demonstrate that the myonuclei of aged type II fibres show an increased amount of condensed chromatin and lower amounts of phosphorylated polymerase II and DNA/RNA hybrid molecules, clearly indicating a decrease in pre-mRNA transcription rate compared to adult animals. In addition, myonuclei of aged fibres show decreased amounts of nucleoplasmic splicing factors and an accumulation of cleavage factors, polyadenilated RNA and perichromatin granules, suggesting a reduction in the processing and transport rate of pre-mRNA. During ageing, it seems therefore that in rat myonuclei the entire production chain of mRNA, from synthesis to cytoplasmic export, is less efficient. This failure likely contributes to the reduced responsiveness of muscle cells to anabolic stimuli in the elderly
Hepatoma tissue culture (HTC) cells as a model for investigating the effects of low concentrations of herbicide on cell structure and function
No full textLiver represents a suitable model for monitoringthe eVects of a diet, due to its key role in controlling thewhole metabolism. Although no direct evidence has beenreported so far that genetically modiWed (GM) food mayaVect health, previous studies on hepatocytes from youngfemale mice fed on GM soybean demonstrated nuclearmodiWcations involving transcription and splicing pathways.In this study, the eVects of this diet were studied onliver of old female mice in order to elucidate possible interferencewith ageing. The morpho-functional characteristicsof the liver of 24-month-old mice, fed from weaning oncontrol or GM soybean, were investigated by combining aproteomic approach with ultrastructural, morphometricaland immunoelectron microscopical analyses. Several proteinsbelonging to hepatocyte metabolism, stress response,calcium signalling and mitochondria were diVerentiallyexpressed in GM-fed mice, indicating a more markedexpression of senescence markers in comparison to controls.Moreover, hepatocytes of GM-fed mice showed mitochondrialand nuclear modiWcations indicative of reducedmetabolic rate. This study demonstrates that GM soybeanintake can inXuence some liver features during ageing and,although the mechanisms remain unknown, underlines theimportance to investigate the long-term consequences ofGM-diets and the potential synergistic eVects with ageing,xenobiotics and/or stress conditions
HTC hepatoma cells as a model for investigating the effects of low herbicide concentrations
No full textThe work report a study on HTC hepatoma cells as a model for investigating the effects of low herbicide concentration
HTC hepatoma cells as a model for investigating the effects of low concentrations of herbicide on cell structure and function.
No full textRNA/MBNL1-containing foci in myoblast nuclei from patients affected by myotonic dystrophy type 2 (DM2): an immunocytochemical study.
No full textMyotonic dystrophy type 2 (DM2) is a dominantly inherited autosomal disease with multi-systemic clinical features and it is caused by expansion of a CCTG tetranucleotide repeat in the first intron of the zinc finger protein 9 (ZNF9) gene in 3q21. The expanded-CCUG-containing transcripts are retained in the cell nucleus and accumulate in the form of focal aggregates which specifically sequester the Muscleblind-like 1 (MBNL1) protein, a RNA binding factor involved in the regulation of alternative splicing. The structural organization and composition of the foci are still incomplete. In this study, the nuclear foci occurring in cultured myoblasts from DM2 patients were characterised at fluorescence and transmission electron microscopy by using a panel of antibodies recognizing transcription and processing factors of pre-mRNAs. MBNL1 proved to co-locate in the nuclear foci with snRNP and hnRNPs, whereas no co-location was observed with RNA polymerase II, the non-RNP splicing factor SC35, the cleavage factor CStF and the PML protein. At electron microscopy the MBNL1-containing nuclear foci appeared as roundish domains showing a rather homogeneous structure and proved to contain snRNP and hnRNPs. The sequestration of splicing factors involved in early phases of pre-mRNA processing supports the hypothesis of a general alteration in the maturation of several mRNAs, which could lead to the multiple pathological dysfunctions observed in dystrophic patients
Immunocytochemical characterisation of MBNL1-containing foci in myoblast nuclei from patients affected by myotonic dystrophy type 2.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
