Relationship between DNA damage response and telomere maintenance

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Telomeres are regions of repetitive DNA bound with a set of specialized proteins required to protect chromosomes from fusing with each other and from eliciting DNA damage response. Dysfunctional telomere maintenance can lead to premature cellular senescence, premature organismal aging and cancer predisposition. In the last few years the evidence has emerged indicating a link between dysfunctional maintenance of telomeres and defective DNA damage response. The objective of this project was to explore further this link by examining effects of some DNA damage response proteins on telomeres that have not been examined before and examining DNA damage response in cells in which telomeres are dysfunctional as a result of alterations in genes not directly involved in DNA damage response. We have developed a method, termed IQ-FISH, for accurate identification of average telomere length in interphase cells from individuals with defective DNA damage response. By applying IQ-FISH we could successfully measure telomere lengths in cell lines from patients that are heterozygous (+/-) and cell lines from patients or animals that are homozygous (-/-) with respect to mutations in these genes. We then analysed telomere length and function, as well as DNA damage response, in lymphoblastoid cell lines originating from BRCA1 and BRCA2 carriers (+/-) and also a single fibroblast cell line from a patient with bi-allelic mutations in BRCA2 (-/-). In addition we have analysed a mouse embryonic stem cell line in which Brca1 was deleted (Brca1-/-) by gene targeting. Our results show lack of correlation between DNA damage response and telomere maintenance in heterozygous cell lines (with the exception of one BRCA1+/- cell line) but a clear positive correlation in the case of cell lines with homozygous mutations. Finally, as a model for telomere dysfunction we have chosen cell lines from Dyskeratosis Congenita (DC) patients. DC is a rare progressive congenital disorder which results in premature aging. DC is primarily a disorder of dysfunctional telomere maintenance and we used cell lines from patients with mutations in DKC1, a gene encoding a protein termed Dyskerin which forms a part of the telomerase enzyme complex. Our results indicate that DC cells with dysfunctional DKC1 may have a dysfunctional DNA damage response

An Electrochemical Investigation of Methanol Oxidation on Nickel Hydroxide Nanoparticles

In this work, a nickel-modified glassy carbon electrode (GCE) was prepared using a potentiostatic method in 0.1Macetate buffer solution at pH 4.0 containing 1.0 mM nickel nitrate. Nickel hydroxide nanoparticles were prepared using consecutive potential scanning in 0.1 M NaOH solution. The as-prepared catalyst was characterized by field emission scanning electron microscopy and electrochemical methods. Electrochemical characterization exhibited stable redox behaviour of the Ni(III)/Ni(II) couple. Cyclic voltammetric experiments showed that electrocatalytic oxidation of methanol can occur at the modified electrode, whereas it is not observed at a bare GCE. The effect of potential sweep rates and methanol concentration on its electrochemical behaviour was studied. The rate constant (k) for the chemical reaction between methanol and catalytic centres has been evaluated by chronoamperometry. In addition, long-term stability of the modified electrode was investigated by electrochemical methods.KEYWORDS Cyclic voltammetry, electrooxidation, glassy carbon electrode, methanol, nickel hydroxide nanoparticles

The mathematical description of the electrosynthesis of composites of oxy-hydroxycompounds cobalt with polypyrrole overooxidazed

The electrosynthesis of the composite with of the overoxidized polypyrrole with cobalt oxy-hydroxide in strongly acidic media has been described mathematically, using linear stability theory and bifurcation analysis. The steadystates stability conditions and oscillatory and monotonic instability requirements have been described too. The system´s behavior was compared with behavior of other systems with overoxidation, electropolymerization of heterocyclic compounds and electrosynthesis of the cobalt oxy-hydroxides

Exploring the extra-planetary : social studies of outer space

Within the past decade, national and commercial activity in and connected to outer space has accelerated at an astounding rate. As anthropology and related social sciences keep pace with these developments, scholars have trained their critical faculties to understand how societies have related to space in the past and the present and how we may approach space in the future. In the autumn of 2021, the members of the project Anthropological Research into the Imaginaries and Exploration of Space (ARIES) developed and taught a class covering this latest turn toward space at Jagiellonian University. Using their experience running this course as a launchpad, this article surveys the current state of space anthropology, highlighting four major themes: science and technology, terrestrial inequalities, environmental justice and alternative relations to the cosmos. It concludes with reflections on the utility and ethics of extraplanetary social scientific research

The mechanism for the electrooxidation of procarbazine pharmaceutical preparation in alkaline media and its mathematical description

The mechanism for the electrooxidation of procarbazine in alkaline media has been proposed. The process is realized completely on the electrode surface and is adsorption-controlled. The oscillatory behavior in this case is more probable, than for neutral media and may be caused by influences of electrochemical oxidation and salt dissolution from the electrode surface

Dysfunctional telomeres in primary cells from Fanconi anemia FANCD2 patients

© 2012 Joksic et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Background: Fanconi anemia (FA) is characterized by sensitivity to DNA cross-linking agents, mild cellular, and marked clinical radio sensitivity. In this study we investigated telomeric abnormalities of non-immortalized primary cells (lymphocytes and fibroblasts) derived from FA patients of the FA-D2 complementation group, which provides a more accurate physiological assessment than is possible with transformed cells or animal models. Results: We analyzed telomere length, telomere dysfunction-induced foci (TIFs), sister chromatid exchanges (SCE), telomere sister chromatid exchanges (T-SCE), apoptosis and expression of shelterin components TRF1 and TRF2. FANCD2 lymphocytes exhibited multiple types of telomeric abnormalities, including premature telomere shortening, increase in telomeric recombination and aberrant telomeric structures ranging from fragile to long-string extended telomeres. The baseline incidence of SCE in FANCD2 lymphocytes was reduced when compared to control, but in response to diepoxybutane (DEB) the 2-fold higher rate of SCE was observed. In contrast, control lymphocytes showed decreased SCE incidence in response to DEB treatment. FANCD2 fibroblasts revealed a high percentage of TIFs, decreased expression of TRF1 and invariable expression of TRF2. The percentage of TIFs inversely correlated with telomere length, emphasizing that telomere shortening is the major reason for the loss of telomere capping function. Upon irradiation, a significant decrease of TIFs was observed at all recovery times. Surprisingly, a considerable percentage of TIF positive cells disappeared at the same time when incidence of γ-H2AX foci was maximal. Both FANCD2 leucocytes and fibroblasts appeared to die spontaneously at higher rate than control. This trend was more evident upon irradiation; the percentage of leucocytes underwent apoptosis was 2.59- fold higher than that in control, while fibroblasts exhibited a 2- h delay before entering apoptosis. Conclusion: The results of our study showed that primary cells originating from FA-D2 patients display shorten telomeres, elevated incidence of T-SCEs and high frequency of TIFs. Disappearance of TIFs in early response to irradiation represent distinctive feature of FANCD2 cells that should be examined further.This article is made available through the Brunel Open Access Publishing Fund. This work was supported by the Ministry of Education and Science of the Republic of Serbia (Project No.173046)