Breaking News
November 16, 2018 - Many RA patients’ pain related to central nervous system
November 16, 2018 - Changes in Himalayan gut microbiomes linked to diet
November 16, 2018 - Inhibition of prostaglandin E2 enhances ability to combat infectious colitis
November 16, 2018 - Chronic dry eye can slow reading rate and disrupt day to day tasks
November 16, 2018 - Researchers develop new drug molecule that inhibits inflammation
November 16, 2018 - Dementia symptoms peak in winter and spring, study finds
November 16, 2018 - Stanford tobacco researcher weighs in on JUUL
November 16, 2018 - Increasing omega-3 fatty acid intake during pregnancy reduces risk of premature birth, review finds
November 16, 2018 - Researchers find no link between infants waking up at night and later developmental problems
November 16, 2018 - Both parents and children agree about confidential medical services
November 16, 2018 - FDA warns against use of unapproved pain medications with implanted pumps
November 16, 2018 - Precision medicine-based approach to slow or reverse biologic drivers of Alzheimer’s disease
November 16, 2018 - Study provides new insight into norovirus outbreaks, may help guide efforts to develop vaccines
November 16, 2018 - Inexpensive, portable air purifier could help protect the heart from pollution
November 16, 2018 - New 15-minute scan could help diagnose brain damage in babies up to two years old
November 16, 2018 - Deep brain stimulation not effective for treating early Alzheimer’s
November 16, 2018 - Traditional chemotherapy superior to new alternative for oropharyngeal cancers | News Center
November 16, 2018 - What This Pond Protist Does With Its Genome Will Astound You
November 15, 2018 - Researchers develop tool that speeds up analysis and publication of biomedical data
November 15, 2018 - Scientists identify mechanism used by lung cancer cells to obtain glucose
November 15, 2018 - Abnormalities in development of the brain could be involved in onset of autism, finds new study
November 15, 2018 - Soy protein equally effective as animal protein in building muscle strength
November 15, 2018 - American Academy of Pediatrics, Nov. 2-6
November 15, 2018 - Dopamine drives early addiction to heroin
November 15, 2018 - Variance in gut microbiome in Himalayan populations linked to dietary lifestyle | News Center
November 15, 2018 - Reducing Cardiovascular Disease: The Amish Way
November 15, 2018 - King’s researchers launch charter to guide organizations to engage abuse survivors in research
November 15, 2018 - Enable Injections enters into development agreements with UCB and Apellis Pharmaceuticals
November 15, 2018 - TGen North collaborates with NARBHA Institute to advance human health
November 15, 2018 - Researchers discover molecular basis for therapeutic actions of an African folk medicine
November 15, 2018 - Human Cell Atlas study of early pregnancy shows how mother’s immune system is modified
November 15, 2018 - New guidelines for detecting and managing sarcopenia to be launched in the UK
November 15, 2018 - Researchers explore role of dietary composition on energy expenditure
November 15, 2018 - Elsevier launches Entellect™ Platform, unlocking value by creating AI-ready life sciences data
November 15, 2018 - Now that cannabis is legal in Canada, let’s use it to tackle the opioid crisis
November 15, 2018 - In the Spotlight: At the intersection of tech, health, and ethics
November 15, 2018 - Traditional Glaucoma Test Can Miss Severity of the Disease
November 15, 2018 - Researchers directly connect activities of genes with instinctive behavior in male cichlids
November 15, 2018 - Salk researchers report new methods to identify AD drug candidates with anti-aging properties
November 15, 2018 - St. Jude Hospital announces availability of largest collections of leukemia samples
November 15, 2018 - Attenua Announces First Patient Treated in Phase 2 Clinical Trial in Chronic Cough with Bradanicline
November 15, 2018 - Designing a novel cell-permeable peptide chimera to promote wound healing
November 15, 2018 - NEI investigators combine two imaging modalities to view the retina in unprecedented detail
November 15, 2018 - Determining how hearts develop to better understand congenital heart defects
November 15, 2018 - Maverick immune cells can act independently to identify and kill cancer cells, finds research
November 15, 2018 - Advanced AI and big data methods to tackle dementia
November 15, 2018 - Report reveals increase in pancreatic cancer death rates across Europe
November 15, 2018 - Luxia Scientific announces availability of its gut microbiome test in Luxembourg
November 15, 2018 - New diabetes drugs linked to increased risk of lower-limb amputation and ketoacidosis
November 15, 2018 - New approach targets matrix surrounding neurons to protect neurons after stroke
November 15, 2018 - Lilly Submits New Drug Application to the FDA for Lasmiditan for Acute Treatment of Migraine
November 15, 2018 - Heart failure patients shouldn’t stop meds even if condition improves: study
November 15, 2018 - Parents and carers of people with diabetes experience emotional or mental health problems
November 15, 2018 - RetiPharma secures funding to develop new peptide drug for treating degenerative eye disorders
November 15, 2018 - Breakthrough research could lead to a new wave of cancer-fighting antibodies
November 15, 2018 - Mylan and Biocon launch new insulin glargine biosimilar in the UK
November 15, 2018 - For wildfire safety, only particular masks guard against toxic particulate matter
November 15, 2018 - New study of tribe shows influence of Western diet and lifestyle on blood pressure
November 15, 2018 - Scientists harness power of natural killer cells to treat children with neuroblastoma
November 15, 2018 - Investigating foodborne disease outbreak in Bosnia and Herzegovina based on simulation game
November 15, 2018 - Recommendations Issued for Management of Bradycardia
November 15, 2018 - Benefit unclear due to a lack of suitable studies
November 15, 2018 - TAMEST recognizes UT Southwestern’s Ralph DeBerardinis for changing our understanding of cancer
November 15, 2018 - Researchers discover key factors behind intestinal inflammation in CVID patients
November 15, 2018 - CityU develops first microarrayed 3D neuronal culture platform
November 15, 2018 - Expert suggests ways to control uncomfortable vaginal symptoms in diabetic women
November 15, 2018 - New edition of Red Journal focuses on roles of imaging in radiation oncology
November 15, 2018 - Doctors Aren’t Promoting Breastfeeding’s Cancer-Protection Benefit
November 15, 2018 - Collection of demonstration projects highlights value of patient engagement in research
November 15, 2018 - Technique to ‘listen’ to a patient’s brain during tumour surgery
November 15, 2018 - Seven-year-old returns to life as a “normal, healthy child” following bone marrow transplant
November 15, 2018 - AMSBIO expands range of high quality FFPE cancer cell line controls
November 15, 2018 - Marijuana use by kidney donors has no effect on transplant outcomes
November 15, 2018 - Exploring NMR Spectroscopy Applications through Interesting Infographics
November 15, 2018 - Chapman University wins additional $2.9 million NIH grant to study Alzheimer’s disease
November 15, 2018 - Microgel powder reduces infection and promotes healing
November 15, 2018 - Suicidal patients with prescribed access to psychotropic drugs should be closely monitored
November 15, 2018 - Nitric oxide-releasing technology shows potential to reduce healing time of diabetic foot ulcers
November 15, 2018 - Mass shootings may trigger unnecessary blood donations
November 15, 2018 - From heart disease to cancer: New study tracks shift of county death rates
Scientists identify ancient light-sensing mechanism in modern mouse retinal cells

Scientists identify ancient light-sensing mechanism in modern mouse retinal cells

image_pdfDownload PDFimage_print

Scientists at Johns Hopkins Medicine say they have identified what may be an ancient light-sensing mechanism in modern mouse retinal cells.

“Some evolutionary biologists have proposed that ancient organisms may have had two separate light-response mechanisms that coexisted in a single photoreceptor, and through evolution, these two mechanisms separated into different cell types. Our research seems to provide evidence that photoreceptors containing both light-sensing mechanisms may still exist in modern mammals,” says King-Wai Yau, Ph.D., a professor of neuroscience at the Johns Hopkins University School of Medicine. In a report of their experiments in mice published Oct. 18 in Cell, the scientists say they focused their research on light-sensing cells that govern so-called “non-image forming” vision.

“When we think about vision, we tend to associate it with seeing an image, such as a person’s face. But light also has other effects, such as making our pupils constrict in bright light to limit its intensity on our retina or helping us overcome jet lag when traveling across time zones,” says Yau, who also is a professor of ophthalmology at Johns Hopkins Wilmer Eye Institute.

Such non-image forming vision, Yau says, is controlled by a subgroup of ganglion cells that reside in the retina of many, most likely all, mammals, including humans. These cells, called intrinsically photosensitive retinal ganglion cells (ipRGCs), are photoreceptors, much like the more familiar rods and cones, and there are five subtypes of them, M1 through M5.

In a bid to understand the biochemical pathway that ipRGCs use to respond to light, Yau and his colleagues first looked to the anatomy of other photoreceptors.

Most photoreceptors have either a kind of tail called cilium or a tufted protrusion called microvilli. The photoreceptors that sport a cilium or cilia on their surface use an intracellular chemical called cyclic nucleotide to respond to light. Other photoreceptors that are speckled with microvilli use, instead, an enzyme called phospholipase C to respond to light. Until now, the two pathways had not been found to coexist in a single photoreceptor.

It turns out that ipRGCs have no cilia or microvilli, so scientists had no anatomical clue to which pathway they use to respond to light. But in research published in 2011 by Yau’s team, they found that the M1 subtype of ipRGCs uses the phospholipase C pathway.

For the current work, Yau and his team focused on subtypes M2 and M4 of ipRGCs to determine if they used the same biochemical pathway as M1 cells.

To do this, the Johns Hopkins scientists genetically engineered mice to remove molecular components in the phospholipase C pathway. If M2 and M4 cells also used the phospholipase C pathway, disrupting the pathway would hamper the cells’ ability to respond to light.

No matter how the scientists disrupted the phospholipase C pathway, however, M4 cells still responded to light without a reduction in the size of response, and M2 cells responded by about half as much as control mice. So, M2 cells seem to use, in part, the phospholipase C pathway, but M4 cells hardly use it.

“That prompted us to search for an alternative pathway the cells might be using,” says Zheng Jiang, Ph.D., a research associate who works in Yau’s laboratory.

In their search, according to Jiang, they found one biochemical pathway involving HCN channels, that, when disrupted, almost completely blocked the intrinsic light response in M4 cells and partly blocked it in M2 cells. Thus, M2 cells were using both the phospholipase C and the newly found HCN-channel pathway, and M4 cells seemed to mostly use the HCN pathway.

HCN channels, which stands for hyperpolarization-activated and cyclic nucleotide-gated channel, are found also in mammalian heart cells, acting as a pacemaker to set heart rate.

The observation that M2 cells use two biochemical pathways for light response suggests a primordial link, say the researchers, harkening back to the proposal by evolutionary biologists that the earliest photoreceptor may contain both mechanisms in the same cell.

Yau says this phenomenon likely exists in the retinas of humans, as well.

Source:

https://www.hopkinsmedicine.org/news/newsroom/news-releases/some-of-retinas-light-sensing-cells-may-have-ancient-roots

Tagged with:

About author

Related Articles