The mcm17 mutation of yeast shows a size-dependent segregational defect of a mini-chromosome

Mini-chromosome-maintenance (mcm) mutants were described earlier as yeast mutants which could not stably maintain mini-chromosomes. Out of these, the ARS-specific class has been more extensively studied and is found to lose chromosomes and mini-chromosomes due to a defect in the initiation of DNA replication at yeast ARSs. In the present study we have identified a number of mcm mutants which show size-dependent loss of mini-chromosomes. When the size of the mini-chromosome was increased, from about 15 kb to about 60 kb, there was a dramatic increase in its mitotic stability in these mutants, but not in the ARS-specific class of mutants. One mutant, mcm17, belonging to the size-dependent class was further characterized. In this mutant, cells carried mini-chromosomes in significantly elevated copy numbers, suggesting a defect in segregation. This defect was largely suppressed in the 60-kb mini-chromosome. A non-centromeric plasmid, the TRP1ARS1 circle, was not affected in its maintenance. This mutant also displayed enhanced chromosome-III loss during mitosis over the wild-type strain, without elevating mitotic recombination. Cloning and sequencing of MCM17 has shown it to be the same as CHL4, a gene required for chromosome stability. This gene is non-essential for growth, as its disruption or deletion from the chromosome did not affect the growth-rate of cells at 23 °C or 37 °C. This work suggests that centromere-directed segregation of a chromosome in yeast is strongly influenced by its length

Constitutive association of Mcm2-3-5 proteins with chromatin in Entamoeba histolytica

Eukaryotic cells duplicate their genome once and only once per cell cycle. Our earlier studies with the protozoan parasite, Entamoeba histolytica, have shown that genome reduplication may occur several times ?without ?nuclear ?or ?cellular ?division. ?The Mcm2-7 protein complex is required for licensing of DNA replication. In an effort to understand whether genome reduplication occurs due to absence or failure of the DNA replication licensing system, we analysed the function of Mcm2-3-5 proteins in E. histolytica. In this study, we have cloned E. histolytica (Eh) MCM2 and Eh MCM5 genes, while Eh MCM3 was cloned earlier. The sequence of Eh MCM2-3-5 genes is well conserved with other eukaryotic homologues. We have shown that Eh Mcm2,3 proteins are functional in Saccharomyces cerevisiae. Our studies in E. histolytica showed that Eh Mcm2-3-5 proteins are associated with chromatin constitutively in cycling cells and during arrest of DNA synthesis induced by serum starvation. Alternation of genome duplication with mitosis is regulated by association-dissociation of Mcm2-7 proteins with chromatin in other eukaryotes. Our results suggest that constitutive association of Mcm proteins with chromatin could be one of the reasons why genome reduplication occurs in E. histolytica

Popular Actions, State Reactions: The Moral and Political Economy of Food in India

Can popular mobilisation activate accountability for hunger? In 2012, a group of researchers set out to explore this question through field research in four countries: Bangladesh, India, Kenya and Mozambique. The research was framed in ideas about a contemporary ‘moral economy’ – which when breached, would lead people to mobilise – either in the form of riots, or as movements for the right to food, thus activating state responses. This preliminary report is organised as follows: Section 2 briefly lays out the political economy context of this time. Section 3 elaborates on the impacts and political economy of food price volatility (FPV) and inflation, drawing upon general Indian data and academic debates. Having set the stage, Section 4 elaborates on the methods used in the study and the adaptation of methods to the Indian context. In Section 5 we place popular mobilisation in India in the context of the new social movements literature, to highlight how such mobilisation has been directed at the state. In particular, the features and mobilisation strategies of the Right to Food campaign are drawn out, to set the stage for the next two empirical sections that follow; the first one on popular mobilisation in Madhya Pradesh (Section 6) and the next on ration riots in West Bengal (Section 7). In Section 8 we trace the impact that these mobilisations had at national and state levels, drawing upon interviews with policymakers and activists. Bringing these sections together in Section 9, we revisit the core themes of the research: food price inflation, moral economy, popular mobilisation and policy responses. In the final Section 10 we conclude with observations about what these findings imply for the potential of popular mobilisation to elicit accountability for hunger from the state

Nano Layers of 2D Graphene Versus Graphene Oxides for Sensing Hydrogen Gas

Hydrogen is one of the most useful but dangerous gases because of its broad combustion range and small ignition temperature. Currently, there is a great need for hydrogen detectors with selectivity, high sensitivity and reliable operations in view of its safe production, storage, transportation and other applications. In this regard, nano thin films of two dimensional materials like graphene, graphene oxide (GO) and reduced graphene oxide (rGO) have immense promise because their material attributes can be exceptionally tuned to achieve the desired characteristics. Also graphene oxide and reduced graphene oxide serve as potential sensing hosts due to the presence of functional groups on their surfaces. In this chapter, an attempt has been made to compare the work done in the field of hydrogen sensors using pure graphene and graphene derivatives such as graphene oxide and reduced graphene oxide. The response parameters like sensitivity, stability, selectivity, response time, recovery time, detection limit, linearity, dynamic range, and working temperatures for various graphene based sensors have been elaborately compared. Finally, a conclusion and future outlook on nano scale thin film of graphene and graphene oxides for gas sensing have been briefly discussed

The Iml3 protein of the budding yeast is required for the prevention of precocious sister chromatid separation in meiosis I and for sister chromatid disjunction in meiosis II

The mitotic kinetochore of the budding yeast contains a number of proteins which are required for chromosome transmission but are non-essential for vegetative growth. We show that one such protein, Iml3, is essential for meiosis, in that the absence of this protein results in reduced spore viability, precocious sister chromatid segregation of artificial and natural chromosomes in meiosis I and chromosome non-disjunction in meiosis II

Foetus Papyraceous

Fetus papyraceous or compress is the compressed, mummified, parchment-like remains of a dead twin which is retained in-utero after intrauterine death in the second trimester. It is an uncommon finding. The incidence of fetus papyraceous is reported as 1 in 17,000 to 1 in 20,000 pregnancies. Incidence of fetus papyraceous in twin pregnancy is 1 in 184 to 1 in 200 pregnancies. A case of fetus papyraceous which was discovered following expulsion of a Twin at 17 weeks and 1 day of gestation with low lying placenta in a monochorionic monoamniotic twin pregnancy is reported here

Bestrophinopathy: An RPE-Photoreceptor Interface Disease

Bestrophinopathies, one of the most common forms of inherited macular degenerations, are caused by mutations in the BEST1 gene expressed in the retinal pigment epithelium (RPE). Both human and canine BEST1-linked maculopathies are characterized by abnormal accumulation of autofluorescent material within RPE cells and bilateral macular or multifocal lesions; however, the specific mechanism leading to the formation of these lesions remains unclear. We now provide an overview of the current state of knowledge on the molecular pathology of bestrophinopathies, and explore factors promoting formation of RPE-neuroretinal separations, using the first spontaneous animal model of BEST1-associated retinopathies, canine Best (cBest). Here, we characterize the nature of the autofluorescent RPE cell inclusions and report matching spectral signatures of RPE-associated fluorophores between human and canine retinae, indicating an analogous composition of endogenous RPE deposits in Best Vitelliform Macular Dystrophy (BVMD) patients and its canine disease model. This study also exposes a range of biochemical and structural abnormalities at the RPE-photoreceptor interface related to the impaired cone-associated microvillar ensheathment and compromised insoluble interphotoreceptor matrix (IPM), the major pathological culprits responsible for weakening of the RPE-neuroretina interactions, and consequently, formation of vitelliform lesions. These salient alterations detected at the RPE apical domain in cBest as well as in BVMD- and ARB-hiPSC-RPE model systems provide novel insights into the pathological mechanism of BEST1-linked disorders that will allow for development of critical outcome measures guiding therapeutic strategies for bestrophinopathies. © 2017 Elsevier Lt

Serine Proteases-Like Genes in the Asian Rice Gall Midge Show Differential Expression in Compatible and Incompatible Interactions with Rice

The Asian rice gall midge, Orseolia oryzae (Wood-Mason), is a serious pest of rice. Investigations into the gall midge-rice interaction will unveil the underlying molecular mechanisms which, in turn, can be used as a tool to assist in developing suitable integrated pest management strategies. The insect gut is known to be involved in various physiological and biological processes including digestion, detoxification and interaction with the host. We have cloned and identified two genes, OoprotI and OoprotII, homologous to serine proteases with the conserved His87, Asp136 and Ser241 residues. OoProtI shared 52.26% identity with mosquito-type trypsin from Hessian fly whereas OoProtII showed 52.49% identity to complement component activated C1s from the Hessian fly. Quantitative real time PCR analysis revealed that both the genes were significantly upregulated in larvae feeding on resistant cultivar than in those feeding on susceptible cultivar. These results provide an opportunity to understand the gut physiology of the insect under compatible or incompatible interactions with the host. Phylogenetic analysis grouped these genes in the clade containing proteases of phytophagous insects away from hematophagous insects