1,720,979 research outputs found
H4 Histone in the Macronucleus of "Blepharisma japonicum"
No full textTwo clones, obtained by polymerase chain reaction from macronuclear DNA of the unicellular ciliated protist Blepharisma
japonicum, were isolated and sequenced. They correspond to fragments of two different putative H4 histone genes. The
existence of multiple H4 histone genes was also suggested by Southern blot hybridisation experiments employing one of the
obtained clones as a probe. Two B. japonicum H4 protein fragments, which were directly sequenced, show differences in the
amino acid sequences too. The comparison of the obtained B. japonicum H4 partial amino acid sequences with each other, and
with H4 from other ciliates and from representative microbial and multicellular organisms, highlights the larger histone
heterogeneity of lower eukaryotes compared to that observed in higher organis
Expression of hsp90 mediates cytoprotective effects in the gastrodermis of planarians
No full textHeat shock proteins (HSPs) play a crucial role in the protection of cells. In the present study, we have identified an hsp90-related gene (Djhsp90) encoding a cytosolic form of HSP90 that is primarily expressed in gastrodermis of the planarian Dugesia japonica. Djhsp90 becomes significantly induced after traumatic amputation or other stress stimuli, such as exposure to X-ray or ultraviolet radiations, heat shock, or prolonged starvation. When Djhsp90 is silenced by ribonucleic acid interference (RNAi), planarians dramatically decrease in size, becoming unable to eat, and die in a few weeks. Our results indicate that this gene plays an essential cytoprotective role in the gastrodermis of planarians and suggest that this chaperone can be involved in autophagic processes that are activated by this tissue
Characterization of hsp genes on planarian stem cells
No full textPlanarians are a model system known for regenerative potential, body plasticity and continuous turnover of all differentiated cell types. These characteristics are based on the presence of pluripotent stem cells, called neoblasts. Damage or reduction in the number of neoblasts deeply affects planarian regeneration and survival. Heat shock proteins (HSPs) are known to perform essential cytoprotective functions in all organisms. To investigate the potential role of hsp-related genes on the dynamics of planarian stem cells, representative hsp-related genes were identified and characterized in normal conditions and after different stress stimuli. Our work revealed that two different hsp genes (Djhsp60 and Djmot) are constitutively expressed in neoblasts, suggesting that their products play important roles in cytoprotection of these cells. RNAi-based functional studies provide evidence of an involvement of Djhsp60 and Djmot in the adaptive response of planarian stem cells to stress and indicate that expression of these genes is critical for planarian survival
A mortalin-like gene is crucial for planarian stem cell viability
No full textIn adult organisms, stem cells are crucial to homeostasis and regeneration of damaged tissues. In planarians,
adult stem cells (neoblasts) are endowed with an extraordinary replicative potential that guarantees
unlimited replacement of all differentiated cell types and extraordinary regenerative ability. The molecular
mechanisms by which neoblasts combine long-term stability and constant proliferative activity, overcoming
the impact of time, remain by far unknown. Here we investigate the role of Djmot, a planarian orthologue
that encodes a peculiar member of the HSP70 family, named Mortalin, on the dynamics of stem cells of
Dugesia japonica. Planarian stem cells and progenitors constitutively express Djmot. Transient Djmot
expression in differentiated tissues is only observed after X-ray irradiation. DjmotRNA interference causes
inability to regenerate and death of the animals, as a result of permanent growth arrest of stem cells. These
results provide the first evidence that an hsp-related gene is essential for neoblast viability and suggest the
possibility that high levels of Djmot serve to keep a p53-like protein signaling under control, thus allowing
neoblasts to escape cell death programs. Further studies are needed to unravel the molecular pathways
involved in these processes
Gypsy/Ty3-like elements in the genome of the terrestrial salamander Hydromantes (Amphibia, Urodela)
No full textA TANDEMLY REPEATED DNA FAMILY ORIGINATED FROM SINE-RELATED ELEMENTS IN THE EUROPEAN PLETHODONTID SALAMANDERS (AMPHIBIA, URODELA)
No full textA Molecular Approach to the Regenerative Process of Freshwater Tricladida: Cloning and Expression of a Gene of the MCM/P1 Family
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