ad hoc tools for affy tiling arrays?
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@kasper-daniel-hansen-2979
Last seen 18 months ago
United States
In a a sense tiling arrays are more general tools than expression arrays. What you are looking for (and hence your method of analysis) is (or at least should be) dependent on your research question. In comparison, with an expression array you are interested in genes that are DE between different experimental conditions. /Kasper On Jan 26, 2006, at 1:36 AM, Dario Greco wrote: > hi all, > we are probably going to use affymetrix tiling arrays for human. > i have understood that in some ways it is possible to use gcrma for > image > preprocessing and that the quantile normalization might be a > reasonable > method. > but i was wondering if there is (or if there is going to be) any ad > hoc tool > in bioconductor also for the later steps of the analysis and > interpretations > of such experiments. > any suggestions are warmly appreciated. > thanks, > > greetings > d > > -- > > Dario Greco > > Institute of Biotechnology - University of Helsinki > Building Cultivator II > P.O.Box 56 Viikinkaari 4 > FIN-00014 Finland > > Office: +358 9 191 58951 > Fax: +358 9 191 58952 > Mobile: +358 44 023 5780 > > Lab WebPage: > http://www.biocenter.helsinki.fi/bi/dna-microarray/ > > Personal WebPage: > http://www.biocenter.helsinki.fi/bi/dna-microarray/dario.htm > > _______________________________________________ > Bioconductor mailing list > Bioconductor at stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/bioconductor
Normalization Preprocessing gcrma Normalization Preprocessing gcrma • 1.1k views
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@sean-davis-490
Last seen 4 months ago
United States
Dario, I'll second this opinion. The design of the array, hypotheses being tested, sample characteristics, genomic features and how they relate to the features on the array, experimental design, and tiling array technology all play a VERY LARGE part in defining what can and should be done in terms of normalization and analysis. I'm not sure that relying on any "canned" solution for tiling arrays is possible at this time given the diverse nature of experiments that can be performed with them. Sean On 2/1/06 12:35 AM, "Kasper Daniel Hansen" <khansen at="" stat.berkeley.edu=""> wrote: > In a a sense tiling arrays are more general tools than expression > arrays. What you are looking for (and hence your method of analysis) > is (or at least should be) dependent on your research question. In > comparison, with an expression array you are interested in genes that > are DE between different experimental conditions. > > /Kasper > > On Jan 26, 2006, at 1:36 AM, Dario Greco wrote: > >> hi all, >> we are probably going to use affymetrix tiling arrays for human. >> i have understood that in some ways it is possible to use gcrma for >> image >> preprocessing and that the quantile normalization might be a >> reasonable >> method. >> but i was wondering if there is (or if there is going to be) any ad >> hoc tool >> in bioconductor also for the later steps of the analysis and >> interpretations >> of such experiments. >> any suggestions are warmly appreciated. >> thanks, >> >> greetings >> d >> >> -- >> >> Dario Greco >> >> Institute of Biotechnology - University of Helsinki >> Building Cultivator II >> P.O.Box 56 Viikinkaari 4 >> FIN-00014 Finland >> >> Office: +358 9 191 58951 >> Fax: +358 9 191 58952 >> Mobile: +358 44 023 5780 >> >> Lab WebPage: >> http://www.biocenter.helsinki.fi/bi/dna-microarray/ >> >> Personal WebPage: >> http://www.biocenter.helsinki.fi/bi/dna-microarray/dario.htm >> >> _______________________________________________ >> Bioconductor mailing list >> Bioconductor at stat.math.ethz.ch >> https://stat.ethz.ch/mailman/listinfo/bioconductor > > _______________________________________________ > Bioconductor mailing list > Bioconductor at stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/bioconductor
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Dario Greco ▴ 310
@dario-greco-1536
Last seen 10.3 years ago
hello, thanks a lot for your messages. actually, in case we will approach to the tiling arrays, we would like to screen the transcriptome, and not the genome. we would actually like to find non coding (novel ?!?!) RNAs having a different expresison pattern in several samples...or at least this would be the ultimate dream! so, in this situation, what would be the best analytical approach, in your opinion? thanks again, yours d -- Dario Greco Institute of Biotechnology - University of Helsinki Building Cultivator II P.O.Box 56 Viikinkaari 4 FIN-00014 Finland Office: +358 9 191 58951 Fax: +358 9 191 58952 Mobile: +358 44 023 5780 Lab WebPage: http://www.biocenter.helsinki.fi/bi/dna-microarray/ Personal WebPage: http://www.biocenter.helsinki.fi/bi/dna- microarray/dario.htm Quoting Sean Davis <sdavis2 at="" mail.nih.gov="">: > Dario, > > I'll second this opinion. The design of the array, hypotheses being > tested, > sample characteristics, genomic features and how they relate to the > features > on the array, experimental design, and tiling array technology all play > a > VERY LARGE part in defining what can and should be done in terms of > normalization and analysis. I'm not sure that relying on any "canned" > solution for tiling arrays is possible at this time given the diverse > nature > of experiments that can be performed with them. > > Sean > > On 2/1/06 12:35 AM, "Kasper Daniel Hansen" <khansen at="" stat.berkeley.edu=""> > wrote: > > > In a a sense tiling arrays are more general tools than expression > > arrays. What you are looking for (and hence your method of analysis) > > is (or at least should be) dependent on your research question. In > > comparison, with an expression array you are interested in genes that > > are DE between different experimental conditions. > > > > /Kasper > > > > On Jan 26, 2006, at 1:36 AM, Dario Greco wrote: > > > >> hi all, > >> we are probably going to use affymetrix tiling arrays for human. > >> i have understood that in some ways it is possible to use gcrma for > >> image > >> preprocessing and that the quantile normalization might be a > >> reasonable > >> method. > >> but i was wondering if there is (or if there is going to be) any ad > >> hoc tool > >> in bioconductor also for the later steps of the analysis and > >> interpretations > >> of such experiments. > >> any suggestions are warmly appreciated. > >> thanks, > >> > >> greetings > >> d > >> > >> -- > >> > >> Dario Greco > >> > >> Institute of Biotechnology - University of Helsinki > >> Building Cultivator II > >> P.O.Box 56 Viikinkaari 4 > >> FIN-00014 Finland > >> > >> Office: +358 9 191 58951 > >> Fax: +358 9 191 58952 > >> Mobile: +358 44 023 5780 > >> > >> Lab WebPage: > >> http://www.biocenter.helsinki.fi/bi/dna-microarray/ > >> > >> Personal WebPage: > >> http://www.biocenter.helsinki.fi/bi/dna-microarray/dario.htm > >> > >> _______________________________________________ > >> Bioconductor mailing list > >> Bioconductor at stat.math.ethz.ch > >> https://stat.ethz.ch/mailman/listinfo/bioconductor > > > > _______________________________________________ > > Bioconductor mailing list > > Bioconductor at stat.math.ethz.ch > > https://stat.ethz.ch/mailman/listinfo/bioconductor > > >
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On 2/1/06 7:11 AM, "Dario Greco" <dario.greco at="" helsinki.fi=""> wrote: > hello, > thanks a lot for your messages. > actually, in case we will approach to the tiling arrays, we would like to > screen the transcriptome, and not the genome. On tiling arrays, there is no distinction between transcriptome and genome--you are measuring every probe along the genome. Some will have signal and may represent transcription, while some will not. You will have to map each probe to genomic features (or lack thereof) before you know what you are measuring. > we would actually like to find non coding (novel ?!?!) RNAs having a > different expresison pattern in several samples...or at least this would > be the ultimate dream! You will likely find many novel transcripts, based on our experience and from that of others in the literature. Determining differential expression is potentially a very difficult problem. You are measuring at discrete probes, so you have to first determine what constitutes transcription, then whether it is represents a novel transcript, and finally if you are seeing differential expression. Each of these is an area of research in-and-of-itself. > so, in this situation, what would be the best analytical approach, in your > opinion? This cannot be summarized in any meaningful way in an email. There are just too many details to consider: What controls are present? What samples are being used? Is this one array or multiple to cover the genome? How dense are the probes? Do you need to compare across arrays for the same sample or not? Are the samples of similar quality? What genome annotation do you want to use? How do you want to "lump" probes into transcriptional units? What computational resources do you have? The first step is to get the Integrated Genome Browser from Affy and visualize your data. After that you can begin to decide what you will need/want to do. I would definitely recommend running some test slides to make sure that your experimental design is reasonable before you spend the presumably large amount of money on a full set of slides. Plan on several weeks to months to analyze the data. Read carefully the few papers available on tiling array analysis of the transcriptome to get ideas regarding the complexity. I'm certainly not an expert in this area, so it will be good to get others' opinions. However, I have done enough with tiling arrays to appreciate their complexity and am just trying to pass some of this along. Sean
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