Navigation Links
Gene expression in mouse neural retina sequenced

PROVIDENCE, R.I. [Brown University] The population of Eric Morrow's seminar "Neurogenetics and Disease" comprises mainly undergraduates who were skipping down the halls of their elementary schools when the first drafts of human genome sequences were published. When Morrow, assistant professor of biology, recently asked the class how to find the mutation behind a disease, a hand shot up in the back of the class to signal the answer: "Sequence the patient's genome."

Ah, to be 19 and take gene sequencing for granted. Fifteen years ago the student's answer would have been unthinkable. Five years ago, it would have been possible, but prohibitively expensive and cumbersome.

Now, armed with so-called "next-generation sequencing" technology, which brings the costs down to thousands rather than hundreds of millions of dollars, Morrow and other properly equipped researchers are obtaining detailed and comprehensive genetic sequences of cells from tissues of interest with relative ease.

In a new study, published in the journal Genomics, Morrow led a research group that has for the first time sequenced the entire "transcriptome" all the messenger RNA transcribed from the DNA that codes proteins of the mouse neural retina. Morrow's overall goal is to investigate the genetic nature of disease in neural tissue and sure enough, the research has yielded some intriguing clues, Morrow said. He added that he will publicly share the entire dataset.

"The reason we studied the neural retina is that we wanted to ask: Is there anything different about those genes that cause disease in the nervous system and all of the other genes in the genome," Morrow said. "There were some fairly prominent differences."

Insights in the mouse retina

The study team, including first author and postdoctoral scholar Ece Gamsiz, produced four main insights:

Although only 114 of 15,251 genes are known to be associated with disease, the disease genes were disproportionately highly expressed to a statistically significant degree. Six disease genes were among the 20 most highly expressed genes, including a sweep of the top three. Disease genes also had much longer sequences on average (4,333.4 bases on average, vs. 3,323 for non-disease genes). Disease genes were somewhat, but significantly, more likely to have alternate transcripts than non-disease genes. This means that there were more different versions in RNA produced from the information encoded in DNA. Neurons in the retina expressed less than a third of the available genes for their synaptic vesicles, which are essential components for how nerve cells transmit signals.

To Morrow, whose studies include the genetics of autism, the next steps have involved sequencing the transcriptomes of other neural tissues to see whether his observations from the retina are more generally true. For example, are disease-related genes unusually highly expressed elsewhere, too? And do specific neural tissues use a "synaptic vesicle" code, like the retina appears to have, or is this more specific just to retina as well?

Morrow said he's been sharing his raw transciptome data publicly so that other scientists can ask their own questions.

"When we go to meetings, people ask us about their particular genes in their particular networks," he said.

Sequencing sensation

Morrow has all but switched methods of genetic analysis. Before sequencing, scientists would use microarrays, which can be stocked with complementary strands of DNA or RNA to detect thousands of genes if they are present in a sample. But for a cost that's tens of thousands of dollars and dropping, Morrow said, sequencing allows him to see everything in the cell and learn about the entire picture, whether genes were well-known enough to be on a gene chip or not.

"You don't need to be sitting on a genome center to do this type of work anymore," Morrow said.

In a similar vein in October, colleagues at Brown and Women & Infants Hospital reported sequencing the transcriptome of human egg cells and, in another first, their sidecar-like "polar bodies." Their key insight: Expendable polar bodies reflect the gene expression of the precious eggs, making them potentially good, nondestructive indicators of which egg to choose for in vitro fertilization.

Only by seeing all the transcripts of all the genes in the mouse retina, and their full sequences, for example, could Morrow and Gamsiz have learned that disease genes are significantly longer, more likely to be transcribed in different ways, and expressed more abundantly.

"I think expression microarrays are becoming a little outdated," Morrow said. "Not that we didn't do well with them. But with them you are missing what you are not looking for because you don't know what's out there."

What makes next-generation sequencing, in this case on an Illumina Genome Analyzer IIx, work better than the slow, labor-intensive and expensive technology used for sequencing just 10 years ago is partly that it sequences a large number of DNA or RNA fragments in parallel, vastly increasing the sequencing system's throughput.

"The technology is amazing, it's a game changer," Morrow said. "In terms of molecular approaches to gene expression, genetics, and genomics it's like a new day. The data are truly beautiful."

As that metaphorical first light shines on the mouse retina transcriptome, an improved understanding of the genetics of neural disease may dawn with it.

Contact: David Orenstein
Brown University

Related medicine news :

1. Personal Tragedy Reveals Untapped Artistic Expression / Family Business Memorializes Loved Ones with Compassion During Grieving
2. Gene expression test reduces need for invasive heart muscle biopsy
3. Spanish gene expression data promise targeting of anti-angiogenesis treatment
4. “You Are Very Pretty”, Says Myeexpert As It Releases A Book, Poetic Expressions, Dedicated To The Beauty of Women.
5. Expression of certain transporter proteins may predict resistance to drug therapy
6. New genetic analysis reveals principles of phenotypic expression
7. Infants hemodynamic responses to happy and angry facial expressions
8. Attention ladies and gentlemen: Courtship affects gene expression
9. Overexpression of repetitive DNA sequences discovered in common tumor cells
10. Oncometabolite linked with widespread alterations in gene expression
11. Gene expression to distinguish metastasizing from non-metastasizing head and neck cancers
Post Your Comments:
(Date:6/25/2016)... (PRWEB) , ... June 25, 2016 , ... Austin residents ... the American College of Mohs Surgery and to Dr. Russell Peckham for medical and ... highly effective treatment for skin cancer. The selective fellowship in Mohs Micrographic Surgery completed ...
(Date:6/25/2016)... (PRWEB) , ... June 25, 2016 , ... As a ... Magna Cum Laude and his M.D from the David Geffen School of Medicine at ... returned to Los Angeles to complete his fellowship in hematology/oncology at the UCLA-Olive View-Cedars ...
(Date:6/24/2016)... ... June 24, 2016 , ... A recent article ... are unfamiliar with. The article goes on to state that individuals are now more ... these less common operations such as calf and cheek reduction. The Los Angeles area ...
(Date:6/24/2016)... ... June 24, 2016 , ... ... Sessions in Dallas that it will receive two significant new grants to support ... as PHA marked its 25th anniversary by recognizing patients, medical professionals and scientists ...
(Date:6/24/2016)... ... ... BioMedics, Inc, makers of Topricin and MyPainAway Pain Relief Products, join The ‘Business for a ... an hour by 2020 and then adjusting it yearly to increase at the same rate ... assure the wage floor does not erode again, and make future increases more predictable. , ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... NAMUR , Belgium , ...  (NYSE MKT: VNRX), today announced the appointment of ... Board of Directors as a Non-Executive Director, effective ... the Company,s Audit, Compensation and Nominations and Governance ... Board, Dr. Futcher will provide independent expertise and ...
(Date:6/23/2016)... Any dentist who has made an implant supported ... Many of them do not even offer this as a ... laboratory costs involved. And those who ARE able to offer ... high cost that the majority of today,s patients would not ... Zadeh , founder of Dental Evolutions Inc. and inventor of ...
(Date:6/23/2016)... Research and Markets has announced the addition of ... Forecast to 2022" report to their offering. ... date financial data derived from varied research sources to present ... impact on the market during the next five years, including ... sub markets, regional and country level analysis. The report provides ...
Breaking Medicine Technology: