Chapter 11 provides knowledge of DNA and Its role in heredity. In this chapter, we will address the following questions: What is the evidence that the gene is DNA? What is the evidence that the gene is DNA? How is DNA replicated? How are errors in DNA repaired? What are some applications of our knowledge of DNA structure and replication?
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Radiation Oncology cung cấp cho các bạn kiến thức về ngành y đề tài: The use of caspase inhibitors in pulsed-field gel electrophoresis may improve the estimation of radiation-induced DNA repair and apoptosis...
We report the cloning and functional charaterization of the full-length cDNA and gene encoding a Toxoplasma gondii DNA repair enzyme designated TgDRE. The gene is composed of three exons separated by two introns of 780 and 630 bp, and encodes a protein with a predicted molecular mass of 49.6 kDa. The native TgDRE protein, with a molecular mass of 60 kDa, is only detected in the virulent tachyzoite stage of T. gondii. However, the transcript is present in both asexual parasite stages, virulent tachyzoite and avirulent encysted bradyzoite. ...
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành y đề tài: Underexpression of mitochondrial-DNA encoded ATP synthesis-related genes and DNA repair genes in systemic lupus erythematosus...
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: " A general framework for quantifying the effects of DNA repair inhibitors on radiation sensitivity as a function of dose
Human cells contain two homologs of the yeast RAD23 protein, hHR23A
and hHR23B, which participate in the DNA repair process. hHR23B hou-ses a domain (residues 277–332, called XPCB) that binds specifically and
directly to the xeroderma pigmentosum group C protein (XPC) to initiate
nucleotide excision repair (NER). This domain shares sequence homology
with a heat shock chaperonin-binding motif that is also found in the stress-inducible yeast phosphoprotein STI1.
Since the discovery of the DNA structure researchers have been highly interested in the molecular basis of genome inheritance. This book covers a wide range of aspects and issues related to the field of DNA replication. The association between genome replication, repair and recombination is also addressed, as well as summaries of recent work of the replication cycles of prokaryotic and eukaryotic viruses. The reader will gain an overview of our current understanding of DNA replication and related cellular processes, and useful resources for further reading....
Rad51 and disrupted meiotic cDNA1 (Dmc1) are the two eukaryotic DNA
recombinases that participate in homology search and strand exchange
reactions during homologous recombination mediated DNA repair. Rad51
expresses in both mitotic and meiotic tissues whereas Dmc1 is confined to
Base excision DNA repair (BER) is fundamentally important in handling
diverse lesions produced as a result of the intrinsic instability of DNA or
by various endogenous and exogenous reactive species. Defects in the BER
process have been associated with cancer susceptibility and neurodegenera-tive disorders.
We observed previously that cisplatin-resistant HeLa cells were cross-resistant to UV light due to accumulation of DDB2, a protein implicated in DNA repair. More recently, we found that cFLIP, which represents an anti-apoptotic protein whose level is induced by DDB2, was implicated in preventing apoptosis induced by deathreceptor signaling. In the present study, we investigated whether DDB2 has a protective role against UV irradiation and whether cFLIP is also involved in this process. Methods: We explored the role of DDB2 in mediating UV resistance in both human cells and Drosophila.
During DNA replication, transcription and DNA repair in
eukaryotes, the cellular machineries performing these tasks
need to gain access to the DNA that is packaged into
chromatin in the nucleus.Chromatin is a dynamic structure
thatmodulates the access of regulatory factors to the genetic
material.A precise coordination and organization of events
in opening and closing of the chromatin is crucial to ensure
that the correct spatial and temporal epigenetic code is
maintained within the eukaryotic genome....
Little is known about the functions of DNA polymerasek
(Pol k) recently identified in mammals. From the genomic
sequence information of rice andArabidopsis, we found that
Polkmay be the only member of the X-family in higher
plants. We have succeeded in isolating the cDNA and
recombinant protein of Polkin a higher plant, rice (Oryza
sativaL. cv. Nipponbare) (OsPolk). OsPolkhad activities
of DNA polymerase, terminal deoxyribonucleotidyl trans-ferase and deoxyribose phosphate lyase, a marker enzyme
for base excision repair. ...
The organization of DNA within eukaryotic cell nuclei poses special problems and opportunities for the cell. For example, assembly of DNA into chromatin is thought to be a principle mechanism by which adventitious general transcription is repressed. However, access to genomic DNA for events such as DNA repair must be facilitated by energy-intensive processes that either directly alter chromatin structure or impart post-translational modiﬁcations, leading to increased DNA accessibility.
Tyrosyl-DNA phosphodiesterase (TDP) cleaves the phosphodiester bond linking the active site tyrosine residue of topoisomerase I with the 3¢ terminus of DNA in topoisomerase I–DNA complexes which accumulate during treatment of cancer with camptothecin. In yeast, TDP mutation confers a 1000-fold hypersensitivity to camptothecin in the presence of an additional mutation of RAD9 gene [Pouliot, J.J., Yao, K.C., Robertson, C.A. & Nash, H.A. (1999) Science 286, 552–555].
When you finish this chapter, you should: Understand semi-conservative mode of DNA replication; know the difference between conservative, semi-conservative and random modes of DNA replication; understand the Messelson and Stahl experiments; know that DNA replication is bi-directional and semi-discontinuous; know the functions of the three DNA polymerases in E. coli;...
In this chapter, the following content will be discussed: DNA replication is semiconservative, general features of DNA replication, DNA polymerases, the mechanism of DNA replication, eukaryotic DNA replication, telomeres and telemerases, reverse transcriptase, DNA repair.
he tumor suppressor, breast cancer susceptibility gene 1 (BRCA1), plays
an integral role in the maintenance of genome stability and, in particular,
the cellular response to DNA damage. Here, the emerging role of BRCA1
in nonhomologous end-joining-mediated DNA repair following DNA dam-age will be reviewed, as well as the activation of apoptotic pathways.
Cockayne syndrome (CS) is a complex, progressive disease that involves
neurological and developmental impairment and premature aging. The
majority of CS patients have mutations in theCSBgene. The CSB protein
is involved in multiple DNA repair pathways and CSBmutated cells are
sensitive to a broad spectrum of genotoxic agents.
DNA repair must take place within the context of chromatin, and it is
therefore not surprising that many aspects of both chromatin components
and proteins that modify chromatin have been implicated in this process.
One of the best-characterized chromatin modification events in DNA-dam-age responses is the phosphorylation of the SQ motif found in histone
H2A or the H2AX histone variant in higher eukaryotes. This modification
is an early response to the induction of DNA damage, and occurs in a wide
range of eukaryotic organisms, suggesting an important conserved func-tion....
Formamidopyrimidine-DNA glycosylase (Fpg protein) of
Escherichia coliis a DNA repair enzyme that excises oxi-dized purine bases, most notably the mutagenic 7-hydro-8-oxoguanine, from damaged DNA. In order to identify
specific contacts between nucleobases of DNA and amino
acids from theE. coliFpg protein, photochemical cross-linking was employed using new reactive DNA duplexes
containing 5-[4-[3-(trifluoromethyl)-3H-diazirin-3-yl]phe-nyl]-2¢-deoxyuridine dU* residues near the 7-hydro-8-oxoguanosine (oxoG) lesion. ...