128 research outputs found

    Farmer Perception of Technology and its Impact on Technology Uptake: The Case of Fodder Legume in Central Kenya Highlands.

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    Technology adoption by farmers is crucial to increasing agricultural productivity hence meeting food and nutrition challenges in Africa. Economists investigating consumer demand have accumulated considerable evidence showing that consumers generally have subjective preferences for product attributes. However, when investigating adoption of new agricultural technologies, economists have lagged behind in analysing how farmers' (the consumer of agricultural technologies) subjective perceptions of technology characteristics affect their adoption decisions. Focusing on farmer perceptions of technologies may provide a better understanding of technology adoption since they deal with the technologies and probably perceive technologies differently from researchers and extension agents. The objective of this paper is to investigate farmers' perception of technology and its impact on adoption using a case study of legume forages in central Kenya highlands. Data from a random sample of 131 farm households in four districts in central Kenya was used. Using participatory techniques, four most important fodder legume attributes to farmers in their adoption decision were identified. These were then used in conjoint analysis. An ordered probit model was estimated to assess relative importance of each attribute to the farmer. A tobit model was also estimated to show the effect of farmers' perception of calliandra and desmodium on probability and intensity of adoption. Results showed that dry season tolerance and economy on land are most important characteristics of fodder legumes to the farmers. It was also found that Calliandra and desmodium were more relevant to the farmers in the area than other fodders. Farmers' perception of the two fodders had a significant impact on their adoption. Consequently, it was recommended that before introducing a technology in an area, it is necessary that the farmers' perception of the technology be analysed Conjoint analysis, ordered probit and tobit estimates, fodder legume adoption.Research and Development/Tech Change/Emerging Technologies,

    Myocardin regulates vascular smooth muscle cell inflammatory activation and disease.

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    OBJECTIVE: Atherosclerosis, the cause of 50% of deaths in westernized societies, is widely regarded as a chronic vascular inflammatory disease. Vascular smooth muscle cell (VSMC) inflammatory activation in response to local proinflammatory stimuli contributes to disease progression and is a pervasive feature in developing atherosclerotic plaques. Therefore, it is of considerable therapeutic importance to identify mechanisms that regulate the VSMC inflammatory response. APPROACH AND RESULTS: We report that myocardin, a powerful myogenic transcriptional coactivator, negatively regulates VSMC inflammatory activation and vascular disease. Myocardin levels are reduced during atherosclerosis, in association with phenotypic switching of smooth muscle cells. Myocardin deficiency accelerates atherogenesis in hypercholesterolemic apolipoprotein E(-/-) mice. Conversely, increased myocardin expression potently abrogates the induction of an array of inflammatory cytokines, chemokines, and adhesion molecules in VSMCs. Expression of myocardin in VSMCs reduces lipid uptake, macrophage interaction, chemotaxis, and macrophage-endothelial tethering in vitro, and attenuates monocyte accumulation within developing lesions in vivo. These results demonstrate that endogenous levels of myocardin are a critical regulator of vessel inflammation. CONCLUSIONS: We propose myocardin as a guardian of the contractile, noninflammatory VSMC phenotype, with loss of myocardin representing a critical permissive step in the process of phenotypic transition and inflammatory activation, at the onset of vascular disease.This work was supported by Wellcome Trust funding for MAJ (Studentship 086799/Z/08/Z), British Heart Foundation grants (PG/10/007/28184) for AT, and (RG/08/009/25841) for MRB, and SS (FS/13/29/30024), the Cambridge NIHR Biomedical Research Centre and the NIH for JM (NIH HL-117907).This is the accepted manuscript of a paper published in Arteriosclerosis, Thrombosis, and Vascular Biology, 2015, doi: 10.1161/ATVBAHA.114.30521

    CRISPR-Cas9 Mediated Epitope Tagging Provides Accurate and Versatile Assessment of Myocardin

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    Objective- Unreliable antibodies often hinder the accurate detection of an endogenous protein, and this is particularly true for the cardiac and smooth muscle cofactor, MYOCD (myocardin). Accordingly, the mouse Myocd locus was targeted with 2 independent epitope tags for the unambiguous expression, localization, and activity of MYOCD protein. Approach and Results- 3cCRISPR (3-component clustered regularly interspaced short palindromic repeat) was used to engineer a carboxyl-terminal 3×FLAG or 3×HA epitope tag in mouse embryos. Western blotting with antibodies to each tag revealed a MYOCD protein product of ≈150 kDa, a size considerably larger than that reported in virtually all publications. MYOCD protein was most abundant in some adult smooth muscle-containing tissues with surprisingly low-level expression in the heart. Both alleles of Myocd are active in aorta because a 2-fold increase in protein was seen in mice homozygous versus heterozygous for FLAG-tagged Myocd. ChIP (chromatin immunoprecipitation)-quantitative polymerase chain reaction studies provide proof-of-principle data demonstrating the utility of this mouse line in conducting genome-wide ChIP-seq studies to ascertain the full complement of MYOCD-dependent target genes in vivo. Although FLAG-tagged MYOCD protein was undetectable in sections of adult mouse tissues, low-passaged vascular smooth muscle cells exhibited expected nuclear localization. Conclusions- This report validates new mouse models for analyzing MYOCD protein expression, localization, and binding activity in vivo and highlights the need for rigorous authentication of antibodies in biomedical research

    CRISPR-Cas9 Mediated Epitope Tagging Provides Accurate and Versatile Assessment of Myocardin--Brief Report

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    OBJECTIVE: Unreliable antibodies often hinder the accurate detection of an endogenous protein, and this is particularly true for the cardiac and smooth muscle cofactor, MYOCD (myocardin). Accordingly, the mouse Myocd locus was targeted with 2 independent epitope tags for the unambiguous expression, localization, and activity of MYOCD protein. APPROACH AND RESULTS: 3cCRISPR (3-component clustered regularly interspaced short palindromic repeat) was used to engineer a carboxyl-terminal 3xFLAG or 3xHA epitope tag in mouse embryos. Western blotting with antibodies to each tag revealed a protein product of approximately 150 kDa, a size considerably larger than that reported in virtually all publications. MYOCD protein was most abundant in some adult smooth muscle-containing tissues with surprisingly low-level expression in the heart. Both alleles of Myocd are active in aorta because a 2-fold increase in protein was seen in mice homozygous versus heterozygous for FLAG-tagged Myocd. ChIP-quantitative polymerase chain reaction studies provide proof-of-principle data demonstrating the utility of this mouse line in conducting genome-wide ChIP-seq studies to ascertain the full complement of MYOCD-dependent target genes in vivo. Although FLAG-tagged MYOCD protein was undetectable in sections of adult mouse tissues, low-passaged vascular smooth muscle cells exhibited expected nuclear localization. CONCLUSIONS: This report validates new mouse models for analyzing MYOCD protein expression, localization, and binding activity in vivo and highlights the need for rigorous authentication of antibodies in biomedical research

    A Role for the Long Noncoding RNA SENCR in Commitment and Function of Endothelial Cells

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    Despite the increasing importance of long non-coding RNA in physiology and disease, their role in endothelial biology remains poorly understood. Growing evidence has highlighted them to be essential regulators of human embryonic stem cell differentiation. SENCR, a vascular-enriched long non-coding RNA, overlaps the Friend Leukemia Integration virus 1 (FLI1) gene, a regulator of endothelial development. Therefore, we wanted to test the hypothesis that SENCR may contribute to mesodermal and endothelial commitment as well as in endothelial function. We thus developed new differentiation protocols allowing generation of endothelial cells from human embryonic stem cells using both directed and haemogenic routes. The expression of SENCR was markedly regulated during endothelial commitment using both protocols. SENCR did not control the pluripotency of pluripotent cells; however its overexpression significantly potentiated early mesodermal and endothelial commitment. In HUVEC, SENCR induced proliferation, migration and angiogenesis. SENCR expression was altered in vascular tissue and cells derived from patients with critical limb ischemia and premature coronary artery disease compared to controls. Here, we showed that SENCR contributes to the regulation of endothelial differentiation from pluripotent cells and controls the angiogenic capacity of HUVEC. These data give novel insight into the regulatory processes involved in endothelial development and function

    Retinoid-Induced Expression and Activity of an Immediate Early Tumor Suppressor Gene in Vascular Smooth Muscle Cells

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    Retinoids are used clinically to treat a number of hyper-proliferative disorders and have been shown in experimental animals to attenuate vascular occlusive diseases, presumably through nuclear receptors bound to retinoic acid response elements (RARE) located in target genes. Here, we show that natural or synthetic retinoids rapidly induce mRNA and protein expression of a specific isoform of A-Kinase Anchoring Protein 12 (AKAP12β) in cultured smooth muscle cells (SMC) as well as the intact vessel wall. Expression kinetics and actinomycin D studies indicate Akap12β is a retinoid-induced, immediate-early gene. Akap12β promoter analyses reveal a conserved RARE mildly induced with atRA in a region that exhibits hyper-acetylation. Immunofluorescence microscopy and protein kinase A (PKA) regulatory subunit overlay assays in SMC suggest a physical association between AKAP12β and PKA following retinoid treatment. Consistent with its designation as a tumor suppressor, inducible expression of AKAP12β attenuates SMC growth in vitro. Further, immunohistochemistry studies establish marked decreases in AKAP12 expression in experimentally-injured vessels of mice as well as atheromatous lesions in humans. Collectively, these results demonstrate a novel role for retinoids in the induction of an AKAP tumor suppressor that blocks vascular SMC growth thus providing new molecular insight into how retiniods may exert their anti-proliferative effects in the injured vessel wall

    Smooth Muscle miRNAs Are Critical for Post-Natal Regulation of Blood Pressure and Vascular Function

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    Phenotypic modulation of smooth muscle cells (SMCs) plays a key role in vascular disease, including atherosclerosis. Several transcription factors have been suggested to regulate phenotypic modulation of SMCs but the decisive mechanisms remain unknown. Recent reports suggest that specific microRNAs (miRNAs) are involved in SMC differentiation and vascular disease but the global role of miRNAs in postnatal vascular SMC has not been elucidated. Thus, the objective of this study was to identify the role of Dicer-dependent miRNAs for blood pressure regulation and vascular SMC contractile function and differentiation in vivo. Tamoxifen-inducible and SMC specific deletion of Dicer was achieved by Cre-Lox recombination. Deletion of Dicer resulted in a global loss of miRNAs in aortic SMC. Furthermore, Dicer-deficient mice exhibited a dramatic reduction in blood pressure due to significant loss of vascular contractile function and SMC contractile differentiation as well as vascular remodeling. Several of these results are consistent with our previous observations in SM-Dicer deficient embryos. Therefore, miRNAs are essential for maintaining blood pressure and contractile function in resistance vessels. Although the phenotype of miR-143/145 deficient mice resembles the loss of Dicer, the phenotypes of SM-Dicer KO mice were far more severe suggesting that additional miRNAs are involved in maintaining postnatal SMC differentiation

    Smooth muscle enriched long non-coding RNA (SMILR) regulates cell proliferation

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    Background—Phenotypic switching of vascular smooth muscle cells from a contractile to a synthetic state is implicated in diverse vascular pathologies, including atherogenesis, plaque stabilization, and neointimal hyperplasia. However, very little is known about the role of long noncoding RNA (lncRNA) during this process. Here, we investigated a role for lncRNAs in vascular smooth muscle cell biology and pathology. Methods and Results—Using RNA sequencing, we identified >300 lncRNAs whose expression was altered in human saphenous vein vascular smooth muscle cells following stimulation with interleukin-1α and platelet-derived growth factor. We focused on a novel lncRNA (Ensembl: RP11-94A24.1), which we termed smooth muscle–induced lncRNA enhances replication (SMILR). Following stimulation, SMILR expression was increased in both the nucleus and cytoplasm, and was detected in conditioned media. Furthermore, knockdown of SMILR markedly reduced cell proliferation. Mechanistically, we noted that expression of genes proximal to SMILR was also altered by interleukin-1α/platelet-derived growth factor treatment, and HAS2 expression was reduced by SMILR knockdown. In human samples, we observed increased expression of SMILR in unstable atherosclerotic plaques and detected increased levels in plasma from patients with high plasma C-reactive protein. Conclusions—These results identify SMILR as a driver of vascular smooth muscle cell proliferation and suggest that modulation of SMILR may be a novel therapeutic strategy to reduce vascular pathologies

    Response to correspondence on Reproducibility of CRISPR-Cas9 Methods for Generation of Conditional Mouse Alleles: A Multi-Center Evaluation

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