Navigation Links
Exploring how the nervous system develops
Date:6/19/2014

The circuitry of the central nervous system is immensely complex and, as a result, sometimes confounding. When scientists conduct research to unravel the inner workings at a cellular level, they are sometimes surprised by what they find.

Patrick Keeley, a postdoctoral scholar in Benjamin Reese's laboratory at UC Santa Barbara's Neuroscience Research Institute, had such an experience. He spent years analyzing different cell types in the retina, the light-sensitive layer of tissue lining the inner surface of the eye that mediates the first stages of visual processing. The results of his research are published today in the journal Developmental Cell.

Using a rodent model, Keeley and his colleagues quantified the number of cells present in each retina for 12 different retinal cell types across 30 genetically distinct lines of mice. For every cell type the team investigated, the researchers found a remarkable degree of variation in cell number across the strains. More surprising, the variation in the number of different cell types was largely independent of one another across the strains. This has substantial implications for retinal wiring during cellular development.

"These cells are connected to each other, and their convergence ratios are believed to underlie various aspects of visual processing," Keeley explained, "so it was expected that the numbers of these cell types might be correlated. But that was not the case at all. We found very few significant correlations and even the ones we did find were modest."

Using quantitative trait locus (QTL) analysis a statistical method that links two types of information, in this case cell number and genetic markers Keeley's team compared not only the covariance between different types of cells but also the genetic co-regulation of their number. When they mapped the variation in cell number to locations within the genome, the locations were rarely the same for different types of cells. The result was entirely unexpected.

"Current views of retinal development propose that molecular switches control the alternate fates a newborn neuron should adopt, leading one to expect negative correlations between certain cell types," said Reese, who is also a professor in UCSB's Department of Psychological and Brain Sciences. "Still others have proposed that synaptically connected nerve cells 'match' their pre- and post-synaptic numbers through a process of naturally occurring cell death, leading one to expect positive correlations between connected cell types. Neither expectation was borne out."

"If the cell types are not correlated, then some mice will have retinas with a lot of one cell type say, photoreceptors but not a lot of another cell type to connect to, in this case bipolar cells, or vice versa," Keeley added. "So how does the developing retina accommodate this variation?"

The authors posit that since the ratios of pre- to post-synaptic cell number are not precisely controlled, the rules for connecting them should offer a degree of plasticity as they wire their connections during development.

Take bipolar cells as an example. To test this assumption, the scientists looked at the morphology of their dendrites, the threadlike extensions of a neuron that gather synaptic input. Keeley and coworkers examined their size, their branching pattern and the number of contacts they formed as a function of the number of surrounding bipolar cells and the number of photoreceptors across these different strains.

"We found that the extent of dendritic growth was proportional to the local density of bipolar cells," Keeley explained. "If there are more, they grow smaller dendrites. If there are fewer, they grow larger dendrites.

"Photoreceptor number, on the other hand, had no effect upon the size of the dendritic field of the bipolar cells but determined the frequency of branching made by those very dendrites," he added. "This plasticity in neural circuit assembly ensures that the nervous system modulates its connectivity to accommodate the independent variation in cell number."

This research gives scientists an idea of how individual cell types are generated, how they differentiate and how they form appropriate connections with one another. Researchers in the Reese lab are trying to understand the genes that control these processes.

"I think that's important when we discuss cellular therapeutics such as transplanting stem cells to replace cells that are lost," Keeley said. "We're going to need this sort of fundamental knowledge about neural development to promote the differentiation and integration of transplanted stem cells. This focus on genetic and cellular mechanisms is going to be important for developing new therapies to treat developmental disorders affecting the eye."


'/>"/>

Contact: Julie Cohen
julie.cohen@ucsb.edu
805-893-7220
University of California - Santa Barbara
Source:Eurekalert  

Related medicine news :

1. Exploring a legal and ethical gray area for people with dementia
2. Nuanced Media Client, Andrea Blatterg of of ABC Senior Placement Advisors Presents: Wildflower Group’s November Event, "Exploring the Allure of Senior Living"
3. EmpowHER’s Michelle King Robson Announces Launch of HER Radio – Exploring all things Woman
4. Sofia University Hosts Exploring O’Sensei’s Aikido & Zen Calligraphy Workshop
5. Agenda Announced for the BioTechniques 2013 Virtual Symposium on Exploring the Modern Lab
6. Outlook with Ben Kingsley Exploring Sports Injuries in Children
7. Outlook with Ben Kingsley Exploring Role of Nanotechnology in Medicine for Upcoming Report
8. Cola and honey: Exploring food riddles in rhythm disturbances
9. Impact with Martin Sheen Exploring Molecular Medicine in a New Report
10. Yeast Infection No More: Review Exploring Linda Allen's Holistic Yeast Infection Treatment Released
11. Registration Opens for the 2013 BioTechniques Virtual Symposium—Exploring the Modern Lab
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Exploring how the nervous system develops
(Date:6/24/2016)... ... ... Global law firm Greenberg Traurig, P.A. announced that 20 Florida attorneys are recognized ... this recognition are considered among the top 2 percent of lawyers practicing within the ... this year’s Legal Elite Hall of Fame: Miami Shareholders Mark D. Bloom, Burt ...
(Date:6/24/2016)... San Diego, CA (PRWEB) , ... June 24, 2016 , ... ... up with the American Cancer Society and the Road To Recovery® program to drive ... care to seniors and other adults to ensure the highest quality of life and ...
(Date:6/24/2016)... ... June 24, 2016 , ... People across the U.S. are sharpening ... Talker Award, an essay contest in which patients and their families pay tribute to ... at the 2016 National Society of Genetic Counselors (NSGC) Annual Education Conference (AEC) this ...
(Date:6/24/2016)... New York, NY (PRWEB) , ... June 24, ... ... lifestyle publication Haute Living, is proud to recognize Dr. Barry M. Weintraub as ... believes that “the most beautiful women in the world, and the most handsome ...
(Date:6/24/2016)... ... June 24, 2016 , ... Strategic Capital Partners, LLC ... by obtaining investment capital for emerging technology companies. SCP has delivered investment ... resulted in more than a million dollars of capital investment for five companies. ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... -- Dehaier Medical Systems Ltd. (NASDAQ: DHRM ... sells medical devices and wearable sleep respiratory products in ... agreement with Hongyuan Supply Chain Management Co., Ltd. (hereinafter ... 2016, to develop Dehaier,s new Internet medical technology business. ... leverage Hongyuan Supply Chain,s sales platform to reach Dehaier,s ...
(Date:6/24/2016)... , June 24, 2016 According ... by Type (Standard Pen Needles, Safety Pen Needles), Needle ... GLP-1, Growth Hormone), Mode of Purchase (Retail, Non-Retail) - ... This report studies the market for the forecast period ... reach USD 2.81 Billion by 2021 from USD 1.65 ...
(Date:6/24/2016)...  Arkis BioSciences, a leading innovator in the ... cerebrospinal fluid treatments, today announced it has secured ... led by Innova Memphis, followed by Angel Capital ... Arkis, new financing will accelerate the commercialization of ... of its in-licensed Endexo® technology. ...
Breaking Medicine Technology: