Plans for the development of cryogenic engines for space exploration

The NASA Lewis Research Center (LeRC) is conducting a broad range of basic research and focused technology development activities in both aeronautical and space propulsion. By virtue of the successful conduct of these programs, LeRC is strongly qualified to lead Advanced Development and subsequent development programs on cryogenic space propulsion systems on support of the Space Exploration Initiative. A review is provided of technology status, including recent progress in the ongoing activities, and a top level description of the proposed program

Comprehensive analysis of Arabidopsis expression level polymorphisms with simple inheritance

In Arabidopsis thaliana, gene expression level polymorphisms (ELPs) between natural accessions that exhibit simple, single locus inheritance are promising quantitative trait locus (QTL) candidates to explain phenotypic variability. It is assumed that such ELPs overwhelmingly represent regulatory element polymorphisms. However, comprehensive genome-wide analyses linking expression level, regulatory sequence and gene structure variation are missing, preventing definite verification of this assumption. Here, we analyzed ELPs observed between the Eil-0 and Lc-0 accessions. Compared with non-variable controls, 5′ regulatory sequence variation in the corresponding genes is indeed increased. However, ∼42% of all the ELP genes also carry major transcription unit deletions in one parent as revealed by genome tiling arrays, representing a >4-fold enrichment over controls. Within the subset of ELPs with simple inheritance, this proportion is even higher and deletions are generally more severe. Similar results were obtained from analyses of the Bay-0 and Sha accessions, using alternative technical approaches. Collectively, our results suggest that drastic structural changes are a major cause for ELPs with simple inheritance, corroborating experimentally observed indel preponderance in cloned Arabidopsis QTL

A cross-country review of strategies of the German development cooperation to strengthen human resources

ABSTRACT: BACKGROUND: Recent years have seen growing awareness of the importance of human resources for health in health systems and with it an intensifying of the international and national policies in place to steer a response. This paper looks at how governments and donors in five countries - Cameroon, Indonesia, Malawi, Rwanda and Tanzania - have translated such policies into action. More detailed information with regard to initiatives of German development cooperation brings additional depth to the range and entry doors of human resources for health initiatives from the perspective of donor cooperation. METHODS: This qualitative study systematically presents different approaches and stages to human resources for health development in a cross-country comparison. An important reference to capture implementation at country level was grey literature such as policy documents and programme reports. In-depth interviews along a predefined grid with national and international stakeholders in the five countries provided information on issues related to human resources for health policy processes and implementation. RESULTS: All five countries have institutional entities in place and have drawn up national policies to address human resources for health. Only some of the countries have translated policies into strategies with defined targets and national programmes with budgets and operational plans. Traditional approaches of supporting training for individual health professionals continue to dominate. In some cases partners have played an advocacy and technical role to promote human resources for health development at the highest political levels, but usually they still focus on the provision of ad hoc training within their programmes, which may not be in line with national human resources for health development efforts or may even be counterproductive to them. Countries that face an emergency, such as Malawi, have intensified their efforts within a relatively short time and by using donor funding support also through new initiatives such as the Global Fund to Fight AIDS, Tuberculosis and Malaria. CONCLUSIONS: The country case studies illustrate the range of initiatives that have surged in recent years and some main trends in terms of donor initiatives. Though attention and priority attributed to human resources for health is increasing, there is still a focus on single initiatives and programmes. This can be explained in part by the complexity of the issue, and in part by its need to be addressed through a long-term approach including public sector and salary reforms that go beyond the health secto

MicroRNA Expression Analysis in the Cellulosic Biofuel Crop Switchgrass (Panicum virgatum) under Abiotic Stress

Switchgrass has increasingly been recognized as a dedicated biofuel crop for its broad adaptation to marginal lands and high biomass. However, little is known about the basic biology and the regulatory mechanisms of gene expression in switchgrass, particularly under stress conditions. In this study, we investigated the effect of salt and drought stress on switchgrass germination, growth and the expression of small regulatory RNAs. The results indicate that salt stress had a gradual but significant negative effect on switchgrass growth and development. The germination rate was significantly decreased from 82% for control to 36% under 1% NaCl treatment. However, drought stress had little effect on the germination rate but had a significant effect on the growth of switchgrass under the severest salinity stress. Both salt and drought stresses altered the expression pattern of miRNAs in a dose-dependent manner. However, each miRNA responded to drought stress in a different pattern. Salt and drought stress changed the expression level of miRNAs mainly from 0.9-fold up-regulation to 0.7-fold down-regulation. miRNAs were less sensitive to drought treatment than salinity treatment, as evidenced by the narrow fold change in expression levels. Although the range of change in expression level of miRNAs was similar under salt and drought stress, no miRNAs displayed significant change in expression level under all tested salt conditions. Two miRNAs, miR156 and miR162, showed significantly change in expression level under high drought stress. This suggests that miR156 and miR162 may attribute to the adaption of switchgrass to drought stress and are good candidates for improving switchgrass as a biofuel crop by transgenic technology

Quantitative Analysis of miRNA Expression in Seven Human Foetal and Adult Organs

miRNAs have been found to repress gene expression at posttranscriptional level in cells. Studies have shown that expression of miRNAs is tissue-specific and developmental-stage-specific. The mechanism behind this could be explained by miRNA pathways. In this study, totally 54 miRNAs were analysed in 7 matched human foetal and adult organs (brain, colon, heart, kidney, liver, lung and spleen) using real-time PCR. Quantitative analysis showed that a big proportion of the 54 miRNAs have higher general expression in the organs of the foetal period than the adult period, with the exception of the heart. The miRNA gene promoter methylation level in the adult stages was higher than in the foetal stages. Moreover, there is a high general expression level of several miRNAs in both stages of brain, kidney, liver, lung and spleen, but not seen in colon and heart. Our results indicate that the miRNAs may play a bigger role in the foetal stage than the adult stage of brain, colon, kidney, liver, lung and spleen. The majority of the miRNAs analysed may play an important role in the growth and development of brain, kidney, liver, lung and spleen. However, a minority of the miRNAs may be functional in colon and heart

Identification and characterization of maize microRNAs involved in the very early stage of seed germination

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are a new class of endogenous small RNAs that play essential regulatory roles in plant growth, development and stress response. Extensive studies of miRNAs have been performed in model plants such as rice, <it>Arabidopsis thaliana </it>and other plants. However, the number of miRNAs discovered in maize is relatively low and little is known about miRNAs involved in the very early stage during seed germination.</p> <p>Results</p> <p>In this study, a small RNA library from maize seed 24 hours after imbibition was sequenced by the Solexa technology. A total of 11,338,273 reads were obtained. 1,047,447 total reads representing 431 unique sRNAs matched to known maize miRNAs. Further analysis confirmed the authenticity of 115 known miRNAs belonging to 24 miRNA families and the discovery of 167 novel miRNAs in maize. Both the known and the novel miRNAs were confirmed by sequencing of a second small RNA library constructed the same way as the one used in the first sequencing. We also found 10 miRNAs that had not been reported in maize, but had been reported in other plant species. All novel sequences had not been earlier described in other plant species. In addition, seven miRNA* sequences were also obtained. Putative targets for 106 novel miRNAs were successfully predicted. Our results indicated that miRNA-mediated gene expression regulation is present in maize imbibed seed.</p> <p>Conclusions</p> <p>This study led to the confirmation of the authenticity of 115 known miRNAs and the discovery of 167 novel miRNAs in maize. Identification of novel miRNAs resulted in significant enrichment of the repertoire of maize miRNAs and provided insights into miRNA regulation of genes expressed in imbibed seed.</p

Genome-Wide Functional Analysis of the Cotton Transcriptome by Creating an Integrated EST Database

A total of 28,432 unique contigs (25,371 in consensus contigs and 3,061 as singletons) were assembled from all 268,786 cotton ESTs currently available. Several in silico approaches [comparative genomics, Blast, Gene Ontology (GO) analysis, and pathway enrichment by Kyoto Encyclopedia of Genes and Genomes (KEGG)] were employed to investigate global functions of the cotton transcriptome. Cotton EST contigs were clustered into 5,461 groups with a maximum cluster size of 196 members. A total of 27,956 indel mutants and 149,616 single nucleotide polymorphisms (SNPs) were identified from consensus contigs. Interestingly, many contigs with significantly high frequencies of indels or SNPs encode transcription factors and protein kinases. In a comparison with six model plant species, cotton ESTs show the highest overall similarity to grape. A total of 87 cotton miRNAs were identified; 59 of these have not been reported previously from experimental or bioinformatics investigations. We also predicted 3,260 genes as miRNAs targets, which are associated with multiple biological functions, including stress response, metabolism, hormone signal transduction and fiber development. We identified 151 and 4,214 EST-simple sequence repeats (SSRs) from contigs and raw ESTs respectively. To make these data widely available, and to facilitate access to EST-related genetic information, we integrated our results into a comprehensive, fully downloadable web-based cotton EST database (www.leonxie.com)

MiRNA Control of Vegetative Phase Change in Trees

After germination, plants enter juvenile vegetative phase and then transition to an adult vegetative phase before producing reproductive structures. The character and timing of the juvenile-to-adult transition vary widely between species. In annual plants, this transition occurs soon after germination and usually involves relatively minor morphological changes, whereas in trees and other perennial woody plants it occurs after months or years and can involve major changes in shoot architecture. Whether this transition is controlled by the same mechanism in annual and perennial plants is unknown. In the annual forb Arabidopsis thaliana and in maize (Zea mays), vegetative phase change is controlled by the sequential activity of microRNAs miR156 and miR172. miR156 is highly abundant in seedlings and decreases during the juvenile-to-adult transition, while miR172 has an opposite expression pattern. We observed similar changes in the expression of these genes in woody species with highly differentiated, well-characterized juvenile and adult phases (Acacia confusa, Acacia colei, Eucalyptus globulus, Hedera helix, Quercus acutissima), as well as in the tree Populus x canadensis, where vegetative phase change is marked by relatively minor changes in leaf morphology and internode length. Overexpression of miR156 in transgenic P. x canadensis reduced the expression of miR156-targeted SPL genes and miR172, and it drastically prolonged the juvenile phase. Our results indicate that miR156 is an evolutionarily conserved regulator of vegetative phase change in both annual herbaceous plants and perennial trees