Function and anatomy of plant siRNA pools derived from hairpin transgenes

<p>Abstract</p> <p>Background</p> <p>RNA interference results in specific gene silencing by small-interfering RNAs (siRNAs). Synthetic siRNAs provide a powerful tool for manipulating gene expression but high cost suggests that novel siRNA production methods are desirable. Strong evolutionary conservation of siRNA structure suggested that siRNAs will retain cross-species function and that transgenic plants expressing heterologous siRNAs might serve as useful siRNA bioreactors. Here we report a detailed evaluation of the above proposition and present evidence regarding structural features of siRNAs extracted from plants.</p> <p>Results</p> <p>Testing the gene silencing capacity of plant-derived siRNAs in mammalian cells proved to be very challenging and required partial siRNA purification and design of a highly sensitive assay. Using the above assay we found that plant-derived siRNAs are ineffective for gene silencing in mammalian cells. Plant-derived siRNAs are almost exclusively double-stranded and most likely comprise a mixture of bona fide siRNAs and aberrant partially complementary duplexes. We also provide indirect evidence that plant-derived siRNAs may contain a hitherto undetected physiological modification, distinct from 3' terminal 2-O-methylation.</p> <p>Conclusion</p> <p>siRNAs produced from plant hairpin transgenes and extracted from plants are ineffective for gene silencing in mammalian cells. Thus our findings establish that a previous claim that transgenic plants offer a cost-effective, scalable and sustainable source of siRNAs is unwarranted. Our results also indicate that the presence of aberrant siRNA duplexes and possibly a plant-specific siRNA modification, compromises the gene silencing capacity of plant-derived siRNAs in mammalian cells.</p

The Information Systems Academic Discipline in Hong Kong

This paper looks to the history of the development of Information Systems in Hong Kong as a contextual base for examining the Information Systems discipline in Hong Kong. The historical analysis highlights the newness of Information Systems as an academic discipline in Hong Kong, dating back little more than 20 years. The study reports on data from eight of the ten universities in Hong Kong. All Information Systems groups in Hong Kong universities are shown to be located in business schools, with almost all groups having no separate Information Systems identity. Few Information Systems academics in Hong Kong are reported to have senior faculty positions. In keeping with the placement of Information Systems groups, and reflective of Hong Kong\u27s status as a world finance centre, Information Systems curricula are shown to have a level of consistency across the state, with a heavy business component. By contrast, the study reports diversity in Information Systems research topics and research methods. Although the data analysed suggests that that the Information Systems discipline is immature in Hong Kong, evidence of a strong turnaround in ICT in Hong Kong and the recent establishment of the Hong Kong Association for Information Systems suggest a basis for boosting the status of Information Systems as a discipline in Hong Kong universities

Integration of PV & Simulated DC Sources for the DC House

The DC House, an ever improving project, uses only pure DC power which most renewable energy sources generate, from solar to wind power. The DC House and this project expect a donation of photovoltaic modules to supply a constant source of DC power. At the moment, the DC House desperately needs power sources because not only does the house have various loads unaccounted for, but the distribution system to determine proper power flow needs a redesign. The project chose to account for these issues by implementing a solar panel onto the DC House and a power distribution module to have the power available where it is needed. Several loads will be applied after the installation of the panel to test whether or not the desired amount of power supplies the appropriate load. This project converts solar power and various other DC Sources into DC electrical power and delivers power efficiently across several DC loads within the DC House

Leak testing of single-use biocontainer for bulk product storage and transport using flow measurement instrument

For some bulk drug products, the biopharmaceutical industry requires a complex transportation network for global shipping and storage under cold temperatures. With the growing demand for single-use technologies, there is need of an accurate method for assuring that single-use biocontainers remain integral throughout such transport and storage. Please click Additional Files below to see the full abstract

Mineral chemistry and origin of the olivine-rich zone of the Palisades sill

The Palisades Sill contains an olivine-rich zone that has attracted scientific attention for over one hundred years. Despite the amount of focus, a definitive explanation for the origin of this layer has not been reached. Through the use of detailed petrographic analyses and electron microscopy, the aim of this study was to collect data on mineral phases from the Palisades Sill in order to better understand the history. Extremely broad ranges in mineral compositions indicate that the olivine-rich zone evolved through in situ equilibrium crystallization, implying that it was injected once the main body of the sill had already been emplaced and partly solidified, a result that confirms certain previous work

Efficient Feeder-Free Episomal Reprogramming with Small Molecules

Genetic reprogramming of human somatic cells to induced pluripotent stem cells (iPSCs) could offer replenishable cell sources for transplantation therapies. To fulfill their promises, human iPSCs will ideally be free of exogenous DNA (footprint-free), and be derived and cultured in chemically defined media free of feeder cells. Currently, methods are available to enable efficient derivation of footprint-free human iPSCs. However, each of these methods has its limitations. We have previously derived footprint-free human iPSCs by employing episomal vectors for transgene delivery, but the process was inefficient and required feeder cells. Here, we have greatly improved the episomal reprogramming efficiency using a cocktail containing MEK inhibitor PD0325901, GSK3β inhibitor CHIR99021, TGF-β/Activin/Nodal receptor inhibitor A-83-01, ROCK inhibitor HA-100 and human leukemia inhibitory factor. Moreover, we have successfully established a feeder-free reprogramming condition using chemically defined medium with bFGF and N2B27 supplements and chemically defined human ESC medium mTeSR1 for the derivation of footprint-free human iPSCs. These improvements enabled the routine derivation of footprint-free human iPSCs from skin fibroblasts, adipose tissue-derived cells and cord blood cells. This technology will likely be valuable for the production of clinical-grade human iPSCs

De invloed van de temperatuur tijdens de opkweekperiode op de positie van de 1e tros, bij verschillende rassen van tomaat, 1961-1962

<p><b>Copyright information:</b></p><p>Taken from "Function and anatomy of plant siRNA pools derived from hairpin transgenes"</p><p>http://www.plantmethods.com/content/3/1/13</p><p>Plant Methods 2007;3():13-13.</p><p>Published online 25 Nov 2007</p><p>PMCID:PMC2217544.</p><p></p> mC9 sense and anti-sense sequences separated by the TGA1 intron (I) with expression by the CMV 35S promoter (35S) and NOS terminator. Transgene integrity for plants Tc9 #1, 3, 5, 9, 11, 13 was verified via PCR (primer position indicated by black arrows) to detect sense (s) and anti-sense (as) transgene elements. Endogenous rbcL is control. For siRNA expression 30 μg of total RNA from wt tobacco or Tc9 transformants was analysed by Northern blotting. A 31 nt mC9 DNA oligo (m) is size marker and an overnight phosphor-image is shown. In vivo gene silencing in Tc9 transformants. Transient transformation was performed by co-infiltration of tobacco wt, Tc9 #1 and #3 with plasmids expressing mC9 sense (pBmC9s) and EYFP transcripts (pBEYFP). Transcript levels in leaf regions were analysed 48 hr post-infiltration by Northern blotting (as described in materials and methods)