Search results for "CELL DIVISION"
showing 10 items of 457 documents
Nuclear Pore Complex Acetylation Regulates mRNA Export and Cell Cycle Commitment in Budding Yeast
2021
AbstractNuclear pore complexes (NPCs) mediate communication between the nucleus and the cytoplasm and regulate gene expression by interacting with transcription and mRNA export factors. Lysine acetyl-transferases (KATs) promote transcription through acetylation of chromatin-associated proteins. We find that Esa1, the KAT subunit of the yeast NuA4 complex, also acetylates the nuclear pore basket component Nup60 to promote mRNA export. Acetylation of Nup60 recruits to the nuclear basket the mRNA export factor Sac3, the scaffolding subunit of the Transcription and Export 2 (TREX-2) complex. Esa1-dependent nuclear export of mRNAs promotes entry into S phase, and is inhibited by the Hos3 deacety…
Studies on the Effect of Cell Division-inhibiting Herbicides on Unialgal and Mixed Algal Cultures
1989
The effect of two cell division inhibiting herbicides on unialgal and mixed algal cultures was studied in laboratory tests. The herbicides studied were trifluralin (analytical grade) and the active ingredient as well as the preparation (80 % a.i.) of diphenamid. The three green algal species used were Selenastrum capricornutum PRINTZ, Scenedesmus quadricauda (TURP.) BREB., Oocystis parva W. et G. S. WEST. The response of algae to herbicides was determined by cell counting, and measured by turbidity (750 nm) and the 02-production of some of the treated cultures. The EC50-value (96 h) of trifluralin to Selenastrum capricornutum was 3.3 mg/l. There were differences in the sensitivity of the th…
Expression of the pea S -adenosylmethionine decarboxylase gene is involved in developmental and environmental responses
2002
A cDNA, able to complement the S-adenosyl-L-methionine decarboxylase (SAMdC; EC 4.1.1.50)-defective yeast strain Y342, has been isolated from pea (Pisum sativum L.). Expression of the SAMdC gene was characterised during pea development. Northern analysis showed a differential expression of the pea SAMdC gene in vegetative and reproductive tissues. The highest SAMdC mRNA levels were found in undifferentiated callus and tissues with high rates of cell division, and at the onset of fruit development. SAMdC expression was also induced in senescing ovaries, probably in relation to an accumulation of spermine during ovary senescence. Finally, the levels of SAMdC transcripts in leaves and shoots w…
Sister-chromatid exchange in cultured lymphocytes of ewes and their newborn lambs
1984
The incidence of sister-chromatid exchange (SCE) in cultured lymphocytes of ewes and their newborn lambs was determined using the BrdU-Giemsa technique. In all ewe-lamb pairs, the SCE rate in the lambs was less than that of the ewes. The mean SCE frequencies per chromosome of the ewes after lambing and of the newborn lambs were 0.1909 and 0.1581, respectively. The statistical analysis shows that a significant difference exists between SCE in the adult female sheep and their lambs. At the same time, a negative correlation was observed between SCE rate and cell proliferation. The results of this study are compared with those of previous reports on age-dependency of SCE.
Unique astrocyte ribbon in adult human brain contains neural stem cells but lacks chain migration
2003
The subventricular zone (SVZ) is a principal source of adult neural stem cells in the rodent brain, generating thousands of olfactory bulb neurons every day. If the adult human brain contains a comparable germinal region, this could have considerable implications for future neuroregenerative therapy. Stem cells have been isolated from the human brain, but the identity, organization and function of adult neural stem cells in the human SVZ are unknown. Here we describe a ribbon of SVZ astrocytes lining the lateral ventricles of the adult human brain that proliferate in vivo and behave as multipotent progenitor cells in vitro. This astrocytic ribbon has not been observed in other vertebrates s…
Looking for Immunological Risk Genotypes
2004
Several functional markers of the immune system may be used either as markers of successful aging or conversely as markers of unsuccessful aging. Particularly, a combination of high CD8 and low CD4 and poor T cell proliferation has been associated with a higher two-year mortality in very old subjects. Therefore, genetic determinants of longevity should reside in those polymorphisms for the immune system genes that regulate immune responses. Concerning these changes in T cell subpopulations, how much they depend on the immunogenetic background and how much they depend on individual antigenic load, such as chronic infections, should be assessed. As previously demonstrated in our population, t…
Blood supply, oxygenation status and metabolic micromilieu of breast cancers: characterization and therapeutic relevance.
2000
The metabolic microenvironment of a tumor is predominantly determined by the efficacy of blood flow, flux parameters (such as diffusion and convective currents in the interstitial space) and metabolic rates. The most important factors in this context include oxygen and nutrient supply, tissue pH and the bioenergetic status. It is now widely accepted that the metabolic microenvironment of a tumor can dramatically influence a range of factors such as proliferation rate, cell cycle position, growth rate and the development of apoptosis and necrosis. At the same time, these parameters can have an impact on tumor detection, therapeutic response to conventional irradiation, some chemotherapy agen…
Effect of cordycepin on interleukin-10 production of human peripheral blood mononuclear cells
2002
Therapeutic options for controlling autoimmune diseases are still very limited. Interleukin-10 has been reported to be a promising approach to therapeutic intervention. In the search for a drug which results in the selective upregulation of interleukin-10, we investigated the immunoregulative effects of cordycepin. We have measured interleukin-10 and interleukin-2 secretion of human peripheral blood mononuclear cells that were incubated with cordycepin and assessed the influence of cordycepin on the expression of interleukin-10 mRNA, the proliferative response and the expression of surface markers on T lymphocytes. In addition, the subsets of interleukin-10-secreting cells, the influence of…
Impairment of gamma/delta T lymphocytes in elderly: implications for immunosenescence
2004
Gamma/delta T lymphocytes cells recognize the antigen in a non-classical way and are considered the third branch of the immune system devoted to defend the integrity of the body. Ageing is characterized by an impairment of the main way of protection (the adaptive branch) but, successfully aged people show compensatory mechanisms of defense such as proneness to inflammation. Moreover, very old subjects show an increased number of NK cells. We have previously demonstrated that gamma delta T lymphocytes are reduced in elderly. In the present paper we have studied some characteristics of these cells to evaluate the possibility that these cells might balance the decreased action of the adaptive …
Histological and fine structural features of pancreatic ductal adenocarcinomas in relation to growth and prognosis: studies in xenografted tumours an…
1985
Histology and fine structure of pancreatic ductal adenocarcinomas were assessed with respect to their significance for tumour growth and prognosis. The histological parameters included glandular differentiation, nuclear anaplasia, nuclear size, and mitotic activity (number of mitoses per high power field). Using these criteria three grades of malignancy were distinguished. They correlated well with the growth kinetics of seven human pancreatic ductal adenocarcinomas transplanted into nude mice. The tumour doubling time of a G 3 carcinoma was about half that of a G 1 carcinoma. On electron microscopy the tumour grade was reflected in the degree of functional differentiation of the neoplastic…