New study shows that artificial light at night can be harmful to ecosystems, biodiversity, and human health
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Research
Feb 8th, 2023
Light Pollution is Killing Desert Rodents
- Life Sciences
- Medicine
- Environment
A new study from Tel Aviv University's School of Zoology tested the impact of prolonged low-intensity light pollution on two species of desert rodents: the diurnal golden spiny mouse, and the nocturnal common spiny mouse. The findings were highly disturbing: on two different occasions, entire colonies exposed to ALAN (Artificial Light At Night) died within days, and reproduction also decreased significantly compared to control groups. According to the researchers, the results show clearly for the first time that light pollution can be extremely harmful to these species, and suggest they may be harmful to ecosystems, biodiversity, and even human health.
"According to latest studies, about 80% of the world's human population is exposed to ALAN, and the area affected by light pollution grows annually by 2-6%. In a small and overcrowded state like Israel, very few places remain free of light pollution." Hagar Vardi-Naim
Humans Changed the Rules
The study was led by Prof. Noga Kronfeld-Schor, Chief Scientist of Israel's Ministry of Environmental Protection, and PhD student Hagar Vardi-Naim, both from TAU's School of Zoology and the Steinhardt Museum of Natural History. The paper was published in Scientific Reports.
"We have been studying these closely related rodent species for years. They both live in Israel's rocky deserts: the golden spiny mouse (Acomys russatus) is diurnal [active during the day], and the common spiny mouse (A. cahirinus) in nocturnal [active during the night]," explains Prof. Kronfeld-Schor. "The two species share the same natural habitat but use it at different times to avoid competition. By comparing closely related species that differ in activity times, we gain new insights into the biological clock and its importance to the health of both animals and humans."
Hagar Vardi-Naim notes that, "in most species studied to date, including humans, the biological clock is synchronized by light. This mechanism evolved over millions of years in response to the daily and annual cycles of sunlight – day and night and their varying lengths that correspond to the change of seasons. Different species developed activity patterns that correspond to these changes in light intensity and daylength and developed anatomical, physiological and behavioral adaptations suitable for day or night activity and seasonality."
"However, over the last decades, humans have changed the rules by inventing and extensively using artificial light, which generates light pollution. According to latest studies, about 80% of the world's human population is exposed to ALAN, and the area affected by light pollution grows annually by 2-6%. In a small and overcrowded state like Israel, very few places remain free of light pollution. In our study, we closely monitored the long-term effects of ALAN on individuals and populations under semi-natural conditions."
"We had seen no preliminary signs (…) We assume that exposure to ALAN had impaired the animals' immune response, leaving them with no protection against some unidentified pathogen [organism causing disease to its host]." Prof. Noga Kronfeld-Schor
Prof. Noga Kronfeld-Schor
Dramatic Turn of Events
In the study, the researchers placed 96 spiny mice, males and females in equal numbers, in eight spacious outdoor enclosures at TAU's Zoological Research Garden. The enclosures simulated living conditions in the wild: all animals were exposed to natural environmental conditions, including the natural light/dark cycle, ambient temperatures, humidity, and precipitation. Each enclosure contained shelters, nesting materials and access to sufficient amounts of food. The experimental enclosures were exposed to low-intensity ALAN (like a streetlamp in urban areas) of different wavelengths (colors) for 10 months: two enclosures were exposed to cold white light, two to warm white (yellowish) light, and two to blue light, while two of the enclosures remained dark at night and served as controls. All animals were marked to enable accurate monitoring of changes in behavior and physical condition. The experiment was conducted twice in two successive years.
"The average life expectancy of spiny mice is 4-5 years, and our original plan was to monitor the effects of ALAN on the same colonies, measuring the effects on reproductive output, wellbeing and longevity," says Prof. Kronfeld-Schor. "But the dramatic results thwarted our plans: on two unrelated occasions, in two different enclosures exposed to white light, all animals died within several days. We had seen no preliminary signs, and autopsies at TAU's Faculty of Medicine and the Kimron Veterinary Institute in Beit Dagan revealed no abnormal findings in the dead spiny mice. We assume that exposure to ALAN had impaired the animals' immune response, leaving them with no protection against some unidentified pathogen. No abnormal mortality was recorded in any of the other enclosures, and as far as we are aware, no similar event has ever been documented by researchers before."
"Our findings show that light pollution, especially cold white and blue light, increases mortality and disrupts reproduction, and thus may be detrimental to the fitness and survival of species in the wild. This adverse effect can have far-reaching consequences at the current wide distribution of light pollution." Prof. Noga Kronfeld-Schor
Disrupted Reproduction
Other findings also indicated that exposure to ALAN disrupts the reproductive success of spiny mice: "In the wild both species of spiny mice breed mainly during summer, when temperatures are high, and the newborn pups are most likely to survive," shares Hagar Vardi-Naim. "Artificial light, however, seemed to confuse the animals. The common spiny mice began to breed year-round but produced a lower number of pups per year. Pups born during winter are not expected to survive in nature, which would further reduce the species' reproductive success in the wild."
"The reproduction of golden spiny mice was affected in a different way: colonies exposed to ALAN continued to breed in the summer, but the number of young was reduced by half compared to the control group, which continued to thrive and breed normally. These findings are in accordance with the fact that in seasonal long day breeders the cue for reproduction is day length."
Additional tests revealed that exposure to ALAN caused physiological and hormonal changes – most significantly in the level of cortisol, an important stress hormone involved in the regulation and operation of many physiological pathways, including the regulation of the immune system. Lab tests indicated that exposure to blue light increased cortisol levels of golden spiny mice, while white light reduced cortisol levels of golden spiny mice males in winter.
"Our findings show that light pollution, especially cold white and blue light, increases mortality and disrupts reproduction, and thus may be detrimental to the fitness and survival of species in the wild. This adverse effect can have far-reaching consequences at the current wide distribution of light pollution. Our clear results are an important step toward understanding the impact of light pollution on biodiversity and will help us promote science-based policies, specifically with regard to the use of artificial light in both built and open areas. In future studies we plan to investigate what caused the extensive deaths in the enclosures exposed to ALAN, focusing on the effect of light pollution exposure on the immune system," concludes Prof. Kronfeld Schor.
Research
Feb 7th, 2023
Researchers Identify A New Genetic Risk Factor for Age-related Eye Disease
Age-related Macular Degeneration (AMD) is a leading cause for loss of eyesight at an advanced age
- Medicine
Researchers at Tel Aviv University identified a new genetic risk factor for the complex eye disease AMD (Age-related Macular Degeneration), a leading cause for loss of eyesight at an advanced age. For the first time, the researchers identified proteins that play a key role in the development and functioning of the tissue affected by the disease, found their exact sites in the genome, and discovered the connection between variations in these genomic regions and the risk for AMD. The researchers: "The new discovery enhances our understanding of the previously unknown function of genomic regions outside the genes. The method we applied may enable the deciphering of additional genetic mechanisms involved in various complex genetic diseases."
"Comparative studies have identified whole genomic regions that are probably related to the disease but were unable to pinpoint any specific feature in these regions and define it as a risk factor. Our study addressed this problem." Prof. Ran Elkon
Decoding Mechanisms of a Complex Disease
The study was led by Prof. Ruth Ashery-Padan and Prof. Ran Elkon and their research teams, Mazal Cohen Gulkar, Naama Mesika, Ahuvit David, and May Eshel, from the Department of Human Molecular Genetics and Biochemistry at the Sackler Faculty of Medicine and the Sagol School of Neuroscience at Tel Aviv University. The paper was published in PLOS Biology.
Prof. Ashery-Padan explains that "one of the greater challenges in genetic research today is decoding the genetic mechanisms of complex diseases caused by a combination of several different genetic and environmental factors (rather than an identifiable defect in a single gene). Diabetes, bowel diseases, and various mental illnesses are just a few examples. In our study we chose to focus on AMD, which causes degeneration of the central retina - a major cause of loss of vision at an advanced age in developed countries."
Prof. Elkon adds: "AMD has a significant genetic component. Studies comparing the genomes of people with and without AMD (as well as a range of other complex genetic diseases) have found differences in several genomic regions, probably associated with risk factors for the disease. However, these differences were not detected in any specific gene, but rather in the extensive regions that stretch between the genes, whose functions and modes of operation are still largely unknown. In fact, comparative studies have identified whole genomic regions that are probably related to the disease but were unable to pinpoint any specific feature in these regions and define it as a risk factor. Our study addressed this problem."
The study focused on the cells of a layer of tissue called retinal pigmented epithelium (RPE), which supports photoreceptors in the retina, and is essential for their initial development as well as their survival throughout an individual's lifetime. According to the researchers, this tissue is affected right from the earliest stages of AMD.
Prof. Ruth Ashery-Padan
"Our findings provide new insight into a previously unsolved issue: the functions and mode of operation of genomic sequences located outside the genes, and how they are involved in complex genetic diseases." Prof. Ruth Ashery-Padan
Novel Research Methodology
"First, we wanted to understand the genetic mechanism that activates and regulates the specific activity of pigmented epithelium cells," says Prof. Ashery-Padan. "Through a series of experiments, knocking down different proteins in both a mouse model and human cells, we identified two key proteins, LHX2 and OTX2, which together dictate the expression of many genes unique to this tissue. The proteins act as transcriptional activators - binding to specific regulatory sites in the genome to determine which genes will be expressed in a particular cell."
The next challenge was mapping the precise locations of the two proteins in the genome. The researchers used the innovative technology ChIP-seq – a DNA sequencing method that identifies binding sites where proteins bind to the DNA.
"We found that the binding sites of the two proteins were quite close to each other," explains Prof. Elkon. "Moreover, these same sites had previously been identified as related to risk factors for AMD (namely, sequences that showed differences between people with and without AMD). We assume that due to changes in DNA sequences in these genomic regions, transcriptional proteins cannot easily find and bind with their binding sites. This reduces the expression of the nearby gene regulated by the transcriptional proteins, which encodes an ion channel known as important to eye function. The decrease in the gene's activity affects the entire tissue, increasing the risk for development of AMD."
Prof. Ashery-Padan sums up the study: "In our study we identified two proteins related to risk factors for the complex genetic eye disease AMD. In addition, for the first time, we were able to map the exact genomic sites of these proteins and found that they operate in a region previously identified as related to risk factors for AMD. Our findings provide new insight into a previously unsolved issue: the functions and mode of operation of genomic sequences located outside the genes, and how they are involved in complex genetic diseases. We believe that our novel research methodology will enable the identification and mapping of many other genetic mechanisms related to AMD and other complex genetic diseases."
Research
Jan 31st, 2023
Do You Have a Rightist or a Leftist Brain?
Political orientation can be predicted by measuring brain activation while watching campaign-ads
- Social Sciences
- Psychology
A first-of-its-kind study scanned the brains of dozens of politically involved participants while they watched campaign-ads and speeches by parties from both ends of the political spectrum, just before one of the last rounds of elections. The participants, half right-wing and half left-wing, were scanned using magnetic resonance imaging (fMRI), a method that measures brain activation. Surprisingly, political-dependent differences in the brain response emerged already in early brain regions, such as regions involved in vision and hearing, and in fact the response in these regions was enough to predict an individual's political views.
Great Minds Think Alike
The study was led by Noa Katabi, a research student in the lab of Dr. Yaara Yeshurun in The School of Psychological Sciences and the Sagol School of Neuroscience. The study was published in the Journal of Neuroscience.
During the study, participants watched video-clips, including a neutral (in terms of political characteristics) video-clip and different political campaign-ads and political speeches by politicians from both blocs, Right and Left. The researchers were surprised to discover widespread partisanship-dependent brain activation and synchronization when Right-wing individuals watched the videos of their political bloc, or when Left-wing individuals watched the videos of left-wing politician.
Interestingly, the researchers found that such partisanship-dependent differences in brain synchronization was not limited to "higher" areas of the brain, associated with interpretation and abstract thinking, as was previously found. Rather, these differences occurred already in regions responsible for sight, hearing and even touch.
"This is the first study to show political-dependent brain activity in early sensory and motor areas, and it can be said that at the most basic brain level, rightists and leftists in Israel literally (and not just metaphorically) don't see and hear the same things." Dr. Yaara Yeshurun
Dr. Yaara Yeshurun
Rightists and Leftists Experience Things Differently
"The research clearly showed that the more the subjects were politically aligned with a certain group, the more their brain response was synchronized, including in motor and somatosensory areas, that is, those areas of the brain that are active when we move or feel things with our senses," explains Dr. Yeshurun. "In fact, just by the brain’s response in these primary sensory areas we could tell if a certain individual was left or wight wing. Intriguingly, it was not necessary to examine the activity in 'higher' brain areas - areas that are involved in understanding why a certain character did something, or what that character thinks and feels - to predict participants' political views, it could even be done by examining an area of the brain that is responsible for seeing or hearing.”
The researchers think that this surprising finding is due to the fact that the participants they chose were politically involved, and also due to the timing of the experiment - a few weeks before the elections, when the political atmosphere in Israel was very present and emotional.
"This is the first study to show political-dependent brain activity in early sensory and motor areas, and it can be said that at the most basic brain level, rightists and leftists in Israel literally (and not just metaphorically) don't see and hear the same things. I think that if we try to understand how people who hold opposite political views to ours experience the world, we might be able to conduct a slightly more effective public discussion that can hopefully attenuate the current political polarization,” adds Dr. Yeshurun.
Right or left? "If we try to understand how people who hold opposite political views to ours experience the world, we might be able to conduct a slightly more effective public discussion (…)"
Research
Jan 30th, 2023
People With Autism Experience Pain at a Higher Intensity
Findings contradict prevalent belief that people on the autism spectrum are 'indifferent to pain'
- Medicine
A new study examined the pain perception among people with autism and found that they experience pain at a higher intensity than the general population and are less adaptable to the sensation. This finding is contrary to the prevalent belief that people with autism are supposedly 'indifferent to pain'. The researchers expressed the hope that the findings of their study will lead to more appropriate treatment on the part of medical staff, caregivers, and parents toward people with autism, who do not always express the experience of pain in the usual way.
The study was funded by the Israel Science Foundation and was led by four researchers: Dr. Tami Bar-Shalita of the Sackler Faculty of Medicine at Tel Aviv University who initiated the study, Dr. Yelena Granovsky of the Technion and Rambam Medical Center, and Prof. Irit Weissman-Fogel and Prof. Eynat Gal of the University of Haifa. This study constitutes a framework for the theses of PhD students Tzeela Hofmann and Mary Klingel-Levy, and three articles based on it have already been published or approved for publishing. The present study has been published in the prestigious PAIN journal.
"We know that self-harm could stem from attempts to suppress pain, and it could be that [people with autism] hurt themselves to activate, unconsciously, a physical mechanism of 'pain inhibits pain'." Dr. Tami Bar-Shalita
Self-harm Not Proof of Indifference to Pain
"Approximately 10% of the general population suffer from sensory modulation dysfunction, which means sensory hypersensitivity at a level that compromises normal daily functioning and quality of life. These people have difficulty, for example, ignoring or adapting to buzzing or flickering of fluorescent lights, humming of air conditioners or fans, or the crunching of popcorn by someone sitting next to them in the cinema," explains Dr. Bar-Shalita.
"In previous studies in the lab we found that these people suffer from pain more than those without sensory modulation dysfunction. Since it is known that sensory modulation dysfunction occurs in people with autism at a rate of 70-90%, it constitutes a criterion for diagnosing autism, and is associated with its severity. We were interested in exploring pain perception in autism, so we asked: do people with autism hurt more than the general population? This question was hardly studied in the lab before we got started."
According to the researchers, for many years the prevalent opinion was that 'people with autism hurt less' or that they were 'indifferent to pain'. Actually, 'indifference to pain' is one of the characteristics presented in the current diagnostic criteria of autism.
The proof of this was, supposedly, their tendency to inflict pain on themselves by self-harm.
Dr. Bar-Shalita: "this assumption is not necessarily true. We know that self-harm could stem from attempts to suppress pain, and it could be that they hurt themselves to activate, unconsciously, a physical mechanism of 'pain inhibits pain'."
"The results of our study indicate that in most cases, the sensitivity to pain of people with autism is higher than that of most of the population, while at the same time they are unsuccessful at effectively suppressing painful stimuli." Dr. Tami Bar-Shalita
Dr. Tami Bar-Shalita
Contributing to Advancement of Personalized Treatment
This study is a laboratory pain study approved by the ethics committee of the academic institutions and Rambam Medical Center. The study included 52 adults with high-functioning autism (HFA) and normal intelligence – hitherto the largest reported sample in the world in studies on pain among people with autism. The study made use of psychophysical tests to evaluate pain, commonly used in the area of pain study. These methods examine the link between stimulus and response, while the researcher, using a computer, controls the duration and intensity of stimulus and the examinee is asked to rank the intensity of the pain felt by him on a scale of 0 to 100.
The findings have proven beyond doubt that people with autism hurt more. Furthermore, their pain suppression mechanism is less effective.
The researchers conducted a variety of measurements, aimed among other things at examining whether the hypersensitivity to pain derives from a sensitized nervous system or from suppression of mechanisms that are supposed to enable adjustment and, over time, reduce the response to the stimulus. They found that in the case of people with autism, it is a combination of the two: an increase of the pain signal along with a less effective pain inhibition mechanism.
Dr. Bar-Shalita concludes: "our study constituted a comprehensive, in-depth study of the intensity of pain experienced by people with autism. The prevalent belief was that they are supposedly 'indifferent to pain', and there are reports that medical and other professional staff treated them accordingly. The results of our study indicate that in most cases, the sensitivity to pain of people with autism is higher than that of most of the population, while at the same time they are unsuccessful at effectively suppressing painful stimuli. We hope that our findings will benefit the professionals and practitioners handling this population and contribute to the advancement of personalized treatment."
In additional articles soon to be published, the researchers have examined the brain activity of people with autism during pain stimuli, and sub-groups within this population concerning their perception of pain.
