127 research outputs found
A Reduction in Ribonucleotide Reductase Activity Slows Down the Chromosome Replication Fork but Does Not Change Its Localization
BACKGROUND:It has been proposed that the enzymes of nucleotide biosynthesis may be compartmentalized or concentrated in a structure affecting the organization of newly replicated DNA. Here we have investigated the effect of changes in ribonucleotide reductase (RNR) activity on chromosome replication and organization of replication forks in Escherichia coli. METHODOLOGY/PRINCIPAL FINDINGS:Reduced concentrations of deoxyribonucleotides (dNTPs) obtained by reducing the activity of wild type RNR by treatment with hydroxyurea or by mutation, resulted in a lengthening of the replication period. The replication fork speed was found to be gradually reduced proportionately to moderate reductions in nucleotide availability. Cells with highly extended C periods showed a "delay" in cell division i.e. had a higher cell mass. Visualization of SeqA structures by immunofluorescence indicated no change in organization of the new DNA upon moderate limitation of RNR activity. Severe nucleotide limitation led to replication fork stalling and reversal. Well defined SeqA structures were not found in situations of extensive replication fork repair. In cells with stalled forks obtained by UV irradiation, considerable DNA compaction was observed, possibly indicating a reorganization of the DNA into a "repair structure" during the initial phase of the SOS response. CONCLUSION/SIGNIFICANCE:The results indicate that the replication fork is slowed down in a controlled manner during moderate nucleotide depletion and that a change in the activity of RNR does not lead to a change in the organization of newly replicated DNA. Control of cell division but not control of initiation was affected by the changes in replication elongation
Reconstruction of major maternal and paternal lineages of the Cape Muslim population
The earliest Cape Muslims were brought to the Cape (Cape Town - South Africa) from Africa and Asia from 1652 to
1834. They were part of an involuntary migration of slaves, political prisoners and convicts, and they contributed to
the ethnic diversity of the present Cape Muslim population of South Africa. The history of the Cape Muslims has been
well documented and researched however no in-depth genetic studies have been undertaken. The aim of the present
study was to determine the respective African, Asian and European contributions to the mtDNA (maternal) and
Y-chromosomal (paternal) gene pool of the Cape Muslim population, by analyzing DNA samples of 100 unrelated
Muslim males born in the Cape Metropolitan area. A panel of six mtDNA and eight Y-chromosome SNP markers
were screened using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Overall
admixture estimates for the maternal line indicated Asian (0.4168) and African mtDNA (0.4005) as the main contributors.
The admixture estimates for the paternal line, however, showed a predominance of the Asian contribution
(0.7852). The findings are in accordance with historical data on the origins of the early Cape Muslims.Web of Scienc
Existence of a lens-shaped cluster of surfaces self-shrinking by mean curvature
We rigorously show the existence of a rotationally and centrally symmetric
"lens-shaped" cluster of three surfaces, meeting at a smooth common circle,
forming equal angles of 120 degrees, self-shrinking under the motion by mean
curvature.Comment: 22 pages, 2 figure
Policing, crime and ‘big data’; towards a critique of the moral economy of stochastic governance
Evidence-Based Management of Hand Eczema
Hand eczema is a common skin disease with a wide variation in morphology and a complex etiology based on endogenous and exogenous factors.The diagnosis of hand eczema is based on patient history, exposure assessment, physical examination, and the results of patch testing. Management of hand eczema starts with education of the patient on the etiology of the disease, and the needed changes in behavior regarding skin care and preventive measures, and avoidance of relevant exposure factors. In many cases, medical treatment is needed for successful management of the disease; use of medication can only be successful with proper education and avoidance of relevant exposure
Transmission of Mitochondrial DNA Diseases and Ways to Prevent Them
Recent reports of strong selection of mitochondrial DNA (mtDNA) during transmission in animal models of mtDNA disease, and of nuclear transfer in both animal models and humans, have important scientific implications. These are directly applicable to the genetic management of mtDNA disease. The risk that a mitochondrial disorder will be transmitted is difficult to estimate due to heteroplasmy—the existence of normal and mutant mtDNA in the same individual, tissue, or cell. In addition, the mtDNA bottleneck during oogenesis frequently results in dramatic and unpredictable inter-generational fluctuations in the proportions of mutant and wild-type mtDNA. Pre-implantation genetic diagnosis (PGD) for mtDNA disease enables embryos produced by in vitro fertilization (IVF) to be screened for mtDNA mutations. Embryos determined to be at low risk (i.e., those having low mutant mtDNA load) can be preferentially transferred to the uterus with the aim of initiating unaffected pregnancies. New evidence that some types of deleterious mtDNA mutations are eliminated within a few generations suggests that women undergoing PGD have a reasonable chance of generating embryos with a lower mutant load than their own. While nuclear transfer may become an alternative approach in future, there might be more difficulties, ethical as well as technical. This Review outlines the implications of recent advances for genetic management of these potentially devastating disorders
Genetic variation and diversity of pearl millet [Pennisetum glaucum (L.)] genotypes assessed for millet head miner, Heliocheilus albipunctella resistance, in West Africa
Pearl millet (Pennisetum glaucum L.), the
major source of minerals and dietary energy for people
living in the semi-arid regions of Sahel, is regularly
damaged by millet head miner, Heliocheilus albipunctella.
In order to identify the plant-based resistance
sources for millet head miner along with high
grain Fe and Zn, we have screened forty pearl millet
genotypes, using an artificial infestation method.
Analysis of variance revealed significant differences
in the genotypes tested for head miner resistance. The
genotypes Gamoji, ICMP 177001, ICMP 177002,
ICMV 177003, ICMV IS 90311, LCIC9702, Souna 3,
ICMV IS 94206 and PE08043 exhibited antibiosis
resistance mechanism to Heliocheilus albipunctella
with appreciable agronomy and grain yield when
compared with the susceptible check ICMV IS 92222.
The genotypes Faringuero, ICMV 167005, ICMV IS
99001, Sadore local, SOSAT-C88, and ICMP 177004
exhibited tolerance to head miner damage with good
per se performance. The genotypes ICMP 177001,
ICMP 177002, ICMV 177003, and Moro exhibited
resistance to millet head miner and had consistent
grain Fe content across seasons (ranging from 44 to
70 ppm). Association between the head miner resistance
and morphological traits showed a positive and significant correlation of larval production index (%)
with head miner damage (r = 0.59**). Grain Fe and
Zn contents exhibited negative association with panicle
length and grain yield indicating proper care
should be taken in breeding for these traits. Hence, the
identified resistance sources can be effectively utilized
in breeding head miner resistant pearl millet OPV’s/
hybrids, with high grain yield including Fe and Zn
concentrations, to overcome the hunger and malnutrition
seen in populations living in the semi-arid tropics
Conventional and Molecular Breeding Approaches for Biofortification of Pearl Millet
Pearl millet [Pennisetum glaucum (L.) R. Br.] is an essential diet of more than 90
million people in the semi-arid tropics of the world where droughts and low fertility
of soils cause frequent failures of other crops. It is an important nutri-rich grain
cereal in the drier regions of the world grown on 26 mha by millions of farmers
(IFAD 1999; Yadav and Rai 2013). This makes pearl millet the sixth most important
crop in the world and fourth most important food crop of the India, next to rice,
wheat, and maize with annual cultivation over an area of ~8 mha. Pearl millet is also
primary food crop in sub-Saharan Africa and is grown on 15 mha (Yadav and Rai
2013). The significant increase in productivity of pearl millet in India is attributed
to development and adoption of hybrids of early to medium duration maturity. More
than 120 diverse hybrids/varieties have been released till date for various production
environments. The heterosis breeding and improved crop management technologies
increased productivity substantially achieving higher increased production of
9.80 mt in 2016–2017 from 2.60 mt in 1950–1951 in spite of declined of area under
the crop by 20–30% over last two decades (Yadav et al. 2012)
Fabry nephropathy: a review – how can we optimize the management of Fabry nephropathy?
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