Blindness And Poverty: An Outreach-Based, Case-Control Study Assessing The Relationship Between Poverty And Visual Impairment From Cataract In Greater Accra, Central, Eastern, Western, Volta, And Ashanti Regions Of Ghana

Background Blinding cataracts have been linked to poverty, and are the most common form of preventable blindness in the developing world. The WHO has identified cataract surgery as one of the top five potential public health interventions in developing countries; however, studies exploring the initial economic attributes before cataract surgery and subsequent outcomes following the sight-restorative surgery in the developing world have not been undertaken. This study assesses the baseline economic and sociodemographic attributes of a cohort of 267 cataract cases in rural villages throughout southern Ghana and compares them with 100 controls to test whether those with existing cataracts are more likely to be impoverished than their peers. Furthermore, this study explores the economic and sociodemographic differences of patients who elect to undergo subsidized cataract surgery compared to those who referred for cataract surgery, but do not undergo the operation. Methods and Findings An outreach-based case-control study recruited 100 control patients and 267 cataract patients at village eye care outreaches in the months of June, July, and August 2011. Cases and controls were both 20 years or older, with cases having been diagnosed with a dense/blinding cataract. Controls were excluded if they were diagnosed with a dense/blinding cataract or if their visual acuity was 20/200 or worse. Enrolled patients completed a questionnaire where the Ghana-specific Poverty Scorecard was used to indirectly assess likelihood of poverty (defined as $2.50/day purchasing power parity (PPP)). Chi-square and multivariate logistic regression showed that cases were more likely to be living below the poverty line than controls (OR 0.91 (CI 0.89, 0.94)) and were 7.29 (CI 2.89, 18.62) times as likely to be in the lowest quintile of poverty. Among cases, unadjusted OR showed that those who underwent surgery were more likely to live bellow the established poverty level than those who did not go for surgery (OR 0.96 (CI 0.93, 0.98), p=0.0392)), however, this was no longer significant when controlling for age, sex, household size, and chorionic disease status (OR 0.97 (CI 0.94, 1.00) p=0.0974). Those that went for surgery were more often male (OR 2.54 (CI 1.09, 5.95) and unemployed (OR 5.62 (CI 1.55, 20.44). Conclusions Data from this study suggests that poverty and blindness from cataracts are linked in rural villages in Ghana. Whether the downward economic trends associated with cataracts are reversed following surgery remains a valuable question that will be explored in subsequent follow-up with this cohort. Additionally, evidence suggests that future interventions and policies should target women in the uptake of the sight-restoring surgery

On a recolouring version of Hadwiger’s conjecture

We prove that for any $\varepsilon>0$, for any large enough $t$, there is a graph $G$ that admits no $K_t$-minor but admits a $(\frac32-\varepsilon)t$-colouring that is ``frozen‘‘ with respect to Kempe changes, i.e. any two colour classes induce a connected component. This disproves three conjectures of Las Vergnas and Meyniel from 1981

Modelling the influence of dimerisation sequence dissimilarities on the auxin signalling network

International audienceBackground: Auxin is a major phytohormone involved in many developmental processes by controlling gene expression through a network of transcriptional regulators. In Arabidopsis thaliana, the auxin signalling network is made of 52 potentially interacting transcriptional regulators, activating or repressing gene expression. All the possible interactions were tested in two-way yeast-2-hybrid experiments. Our objective was to characterise this auxin signalling network and to quantify the influence of the dimerisation sequence dissimilarities on the interaction between transcriptional regulators.Results: We applied model-based graph clustering methods relying on connectivity profiles between transcriptional regulators. Incorporating dimerisation sequence dissimilarities as explanatory variables, we modelled their influence on the auxin network topology using mixture of linear models for random graphs. Our results provide evidence that the network can be simplified into four groups, three of them being closely related to biological groups. We found that these groups behave differently, depending on their dimerisation sequence dissimilarities, and that the two dimerisation sub-domains might play different roles.Conclusions: We propose here the first pipeline of statistical methods combining yeast-2-hybrid data and protein sequence dissimilarities for analysing protein-protein interactions. We unveil using this pipeline of analysis the transcriptional regulator interaction modes

Modeling the structure and dynamics of the auxin signaling network in the shoot apical meristem

International audienceno abstrac

Relationships between synoptic-scale transport and interannual variability of inorganic cations in surface snow at Summit, Greenland: 1992-1996

Version of RecordTo fully utilize the long-term chemical records retrieved from central Greenland ice cores, specific relationships between atmospheric circulation and the variability of chemical species in the records need to be better understood. This research examines associations between the variability of surface snow inorganic cation chemistry at Summit, Greenland (collected during 1992-1996 summer field seasons) and changes in air mass transport pathways and source regions, as well as variations in aerosol source strength. Transport patterns and source regions are determined through 10-day isentropic backward air mass trajectories during a 1 month (late May to late June) common season over the 5 years. Changes in the extent of exposed continental surfaces in source regions are evaluated to estimate aerosol-associated calcium and magnesium ion source strength, while forest fire activity in the circumpolar north is investigated to estimate aerosol ammonium ion source strength. During the 1995 common season, 3 times more calcium and magnesium accumulated in the snowpack than the other study years. Also, an increasing trend of ammonium concentration was noted throughout the 5 years. Anomalous transport pathways and velocities were observed during 1995, which likely contributed to the high levels of calcium and magnesium. Increased forest fire activity in North America was concurrent with increased levels of ammonium and potassium, except for 1996, when ion levels were above average and forest fire activity was below average. Because of the ubiquitous nature of soluble ions, we conclude that it is very difficult to establish a quantitative link between the ion content of snow and firn at Summit and changes in aerosol source regions and source strength.Slater, J. F., Dibb, J. E., Keim, B. D., & Kahl, J. D. w. (2001). Relationships between synoptic-scale transport and interannual variability of inorganic cations in surface snow at Summit, Greenland: 1992-1996. Journal of Geophysical Research 106(D18), 20,897-20,91

Translational adaptation to heat stress is mediated by RNA 5-methylcytosine in Caenorhabditis elegans.

Methylation of carbon-5 of cytosines (m5 C) is a post-transcriptional nucleotide modification of RNA found in all kingdoms of life. While individual m5 C-methyltransferases have been studied, the impact of the global cytosine-5 methylome on development, homeostasis and stress remains unknown. Here, using Caenorhabditis elegans, we generated the first organism devoid of m5 C in RNA, demonstrating that this modification is non-essential. Using this genetic tool, we determine the localisation and enzymatic specificity of m5 C sites in the RNome in vivo. We find that NSUN-4 acts as a dual rRNA and tRNA methyltransferase in C. elegans mitochondria. In agreement with leucine and proline being the most frequently methylated tRNA isoacceptors, loss of m5 C impacts the decoding of some triplets of these two amino acids, leading to reduced translation efficiency. Upon heat stress, m5 C loss leads to ribosome stalling at UUG triplets, the only codon translated by an m5 C34-modified tRNA. This leads to reduced translation efficiency of UUG-rich transcripts and impaired fertility, suggesting a role of m5 C tRNA wobble methylation in the adaptation to higher temperatures

Pseudogenization of a Sweet-Receptor Gene Accounts for Cats' Indifference toward Sugar

Although domestic cats (Felis silvestris catus) possess an otherwise functional sense of taste, they, unlike most mammals, do not prefer and may be unable to detect the sweetness of sugars. One possible explanation for this behavior is that cats lack the sensory system to taste sugars and therefore are indifferent to them. Drawing on work in mice, demonstrating that alleles of sweet-receptor genes predict low sugar intake, we examined the possibility that genes involved in the initial transduction of sweet perception might account for the indifference to sweet-tasting foods by cats. We characterized the sweet-receptor genes of domestic cats as well as those of other members of the Felidae family of obligate carnivores, tiger and cheetah. Because the mammalian sweet-taste receptor is formed by the dimerization of two proteins (T1R2 and T1R3; gene symbols Tas1r2 and Tas1r3), we identified and sequenced both genes in the cat by screening a feline genomic BAC library and by performing PCR with degenerate primers on cat genomic DNA. Gene expression was assessed by RT-PCR of taste tissue, in situ hybridization, and immunohistochemistry. The cat Tas1r3 gene shows high sequence similarity with functional Tas1r3 genes of other species. Message from Tas1r3 was detected by RT-PCR of taste tissue. In situ hybridization and immunohistochemical studies demonstrate that Tas1r3 is expressed, as expected, in taste buds. However, the cat Tas1r2 gene shows a 247-base pair microdeletion in exon 3 and stop codons in exons 4 and 6. There was no evidence of detectable mRNA from cat Tas1r2 by RT-PCR or in situ hybridization, and no evidence of protein expression by immunohistochemistry. Tas1r2 in tiger and cheetah and in six healthy adult domestic cats all show the similar deletion and stop codons. We conclude that cat Tas1r3 is an apparently functional and expressed receptor but that cat Tas1r2 is an unexpressed pseudogene. A functional sweet-taste receptor heteromer cannot form, and thus the cat lacks the receptor likely necessary for detection of sweet stimuli. This molecular change was very likely an important event in the evolution of the cat's carnivorous behavior

A multiscale analysis of early flower development in Arabidopsis provides an integrated view of molecular regulation and growth control.

We have analyzed the link between the gene regulation and growth during the early stages of flower development in Arabidopsis. Starting from time-lapse images, we generated a 4D atlas of early flower development, including cell lineage, cellular growth rates, and the expression patterns of regulatory genes. This information was introduced in MorphoNet, a web-based platform. Using computational models, we found that the literature-based molecular network only explained a minority of the gene expression patterns. This was substantially improved by adding regulatory hypotheses for individual genes. Correlating growth with the combinatorial expression of multiple regulators led to a set of hypotheses for the action of individual genes in morphogenesis. This identified the central factor LEAFY as a potential regulator of heterogeneous growth, which was supported by quantifying growth patterns in a leafy mutant. By providing an integrated view, this atlas should represent a fundamental step toward mechanistic models of flower development