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Ways in which pathogens avoid being detected by the immune system Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Mechanisms of pathogen evasion 27/03/25, 11:23 Last updated: Published: 05/09/24, 10:54 Ways in which pathogens avoid being detected by the immune system Introduction Pathogens such as bacteria and viruses have evolved strategies to deceive and outsmart the immune system's defences. From hiding within cells to avoiding immune detection to blocking signals crucial for immune function, pathogens have developed an array of tactics to stay one step ahead of the immune system. This article introduces some key strategies pathogens employ to evade the immune system. Antigenic variation The influenza virus is a persistent and challenging pathogen to treat because it employs a clever strategy known as antigenic variation to evade the immune system. Antigenic variation is the pathogen’s ability to alter the proteins on its surface (antigens), particularly hemagglutinin (HA) and neuraminidase (NA), which are the primary targets of the immune system. As the virus conceals itself, it is no longer recognised and attacked by the host's defences. But how do the surface antigens change? This occurs through two primary mechanisms: antigenic drift and antigenic shift. The former process involves gradual changes in the virus's surface proteins by progressive accumulation of genetic mutations. Meanwhile, the latter requires a slightly different explanation. Antigenic shift is an abrupt process. It occurs when two influenza virus strains infect the same host cell and exchange genetic material. The exchange can lead to a new hybrid strain. This hybrid strain usually presents a new combination of surface proteins. It is a more abrupt process, and because the immune system lacks prior exposure to these new proteins, it fails to clear the viral pathogen. Antigenic shifts can lead to the emergence of strains to which the population has little to no pre-existing immunity. Some examples are the 1968 Hong Kong flu and the 2009 swine flu pandemic. Variable serotypes- Streptococcus pneumoniae When the host encounters a pathogen, the body creates antibodies against specific proteins on the pathogen's surface, ensuring long-term immunity. However, some species of pathogens evade this protection by evolving different strains. These strains involve multiple serotypes, each defined by distinct variations in the structure of their capsular polysaccharides. This variability allows them to infect the same host repeatedly, as immunity to one serotype does not confer protection against other serotypes. A perfect example of such a pathogen is the pneumonia-causing bacterium, Streptococcus pneumoniae , which has more than 90 strains. After successful infection with a particular S. pneumoniae serotype, a person will have devised antibodies that prevent reinfection with that specific serotype. However, these antibodies do not prevent an initial infection with another serotype, as illustrated in Figure 1 . Therefore, by evading the immune response, a new primary immune response is required to clear the infection. Latency- chicken pox & Human Immunodeficiency Virus (HIV) Pathogens can cleverly persist in the host by entering a dormant state where they are metabolically inactive. In this state, they are invisible to the immune system. Human Immunodeficiency Virus is well known for its use of HIV latent reservoirs. These reservoirs, consisting of metabolically inactive T-cells infected with HIV, can exist for years on end. When the host becomes immunocompromised at any stage in life, the T-cells in these reservoirs are suddenly activated to renew HIV production. The Varicella-Zoster Virus (VZV) is responsible for causing varicella (chickenpox) and zoster (shingles). Similarly, this virus can remain latent in the host to evade immune detection. VZV establishes latency in sensory ganglia, particularly in neurons. Since neurons are relatively immune-privileged sites, they are less accessible to immune surveillance mechanisms. This provides a safe haven from immune detection. When the host is immunocompromised, the virus reactivates. This renewed viral activity results in the production of viral particles which travel along the sensory nerve fibres towards mucous membranes. When the virus reaches the skin, it causes an inflammatory response. This results in painful vesicular skin lesions, commonly known as shingles (herpes zoster). Conclusion Pathogens employ diverse mechanisms to evade the host immune system, ensuring their survival and propagation through host cells. These evasion mechanisms can hinder the development of treatments for certain infectious diseases. For instance, the diversity in Strep A serotypes challenges vaccine development because immunity to one serotype may not confer protection against another. Additionally, the influenza virus constantly evolves via antigenic variation, always one step ahead of the immune system. The strategies employed by pathogens to evade the immune system are as diverse as they are sophisticated. Scientists continue to study these mechanisms, paving the way for developing more effective vaccines, treatments, and public health strategies to out-manoeuvre these organisms. We can better protect human health by staying one step ahead of pathogen evolution. Written by Fozia Hassan Related articles: Allergies / Plant diseases REFERENCES Abendroth, Allison, et al. “Varicella Zoster Virus Immune Evasion Strategies.” Current Topics in Microbiology and Immunology , 2010, pp. 155–171, www.ncbi.nlm.nih.gov/pmc/articles/PMC3936337/ , https://doi.org/10.1007/82_2010_41 . Accessed 24 July 2024. Gougeon, M-L. “To Kill or Be Killed: How HIV Exhausts the Immune System.” Cell Death & Differentiation , vol. 12, no. S1, 15 Apr. 2005, pp. 845–854, www.nature.com/articles/4401616 , https://doi.org/10.1038/sj.cdd.4401616 . Accessed 24 July 2024. Parham, Peter. The Immune System . 5th ed., New York, Garland Science, 2015, read.kortext.com/reader/epub/1743564 . Accessed 24 July 2024. Shaffer, Catherine. “How HIV Evades the Immune System.” News-Medical.net , 21 Feb. 2018, www.news-medical.net/life-sciences/How-HIV-Evades-the-Immune-System.aspx . Accessed 24 July 2024. Project Gallery

​Dive into the latest biological research! Read about animal testing and ethics, and learn about the regulation and policy of stem cell research. Biology Articles Dive into the latest biological research! Read about animal testing and ethics, and learn about the regulation and policy of stem cell research. You may also like: Cancer , Ecology , Genetics , Immunology , Neuroscience , Zoology , and Medicine Regulation and policy of stem cell research The 14-day rule and stem cell-based embryo models Maveerar Naal Health, trauma, and resilience amid decades of war in Sri Lanka What are health inequalities? Unequal access to healthcare. Article #1 in a series on health inequalities. COMING SOON Previous

The secrets of the brain are secrets no longer; the field of neuroscience is rapidly expanding day by day. Read articles which discuss Parkinsonism, Huntington’s, degeneration, Alzheimer’s, and more. Neuroscience Articles The secrets of the brain are secrets no longer; the field of neuroscience is rapidly expanding day by day. Read articles which discuss Parkinsonism, Huntington’s, degeneration, Alzheimer’s, and more. You may also like: Biology , Immunology , Medicine Synaptic plasticity and London taxi drivers Synaptic plasticity and navigating our surroundings Stress and neurodegeneration And how the hormone cortisol plays a significant role Markers for Parkinsonism Exploring the role of TDP43 The wonders of the human brain A basic overview of brain function The brain-climate connection Can rising temperatures really affect our brains? Schizophrenia and accelerated ageing A complex medical phenotype Squid axons And how they were fundamental to discoveries in neuroscience Alzheimer's disease Its pathology and potential treatment Serial killers Their neurological basis Huntington's disease A rare, inherited, debilitating neurological disease Electricity in the body Luigi Galvani 's work PTSD and intrusive memories Article #1 in a series on Post Traumatic Stress Disorder and traumatic memories Mobility disorders Hypermobility spectrum disorders vs. Hypermobile Ehlers-Danlos Syndrome Brief neuroanatomy of autism Autism is a neurological and developmental disorder Oliver Sacks Who was this famous neuroscientist? A treatment for Huntington's disease Antisense oligonucleotide gene therapy PTSD and Tetris Article #2 in a series on Post Traumatic Stress Disorder and traumatic memories The dopamine connection The link between the brain and the digestive system Neuromyelitis optica (NMO)- Devic disease How is it different to Multiple Sclerosis? Article #8 in a series on Rare diseases. DFNB9 How was this form of deafness treated for the first time? Next

For this experiment, the gravitational acceleration was calculated by measuring the time period of a simple pendulum using three different experimental methods; methods 2 and 3 were more similar than method 1. This experiment is primarily for data analysis of the measurements taken of a simple pendulum oscillating freely to determine the acceleration due to gravity. Go back Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Outline of an investigation of the period of a single pendulum, and its relation to gravity Last updated: 13/11/24 Last updated: 26/01/23 For this experiment, the gravitational acceleration was calculated by measuring the time period of a simple pendulum using three different experimental methods; methods 2 and 3 were more similar than method 1. This experiment is primarily for data analysis of the measurements taken of a simple pendulum oscillating freely to determine the acceleration due to gravity. This experiment can be repeated but can be carried out in different viscous liquids to see how the extra damping force affects the time period of the oscillation and calculate the g value from it. This can be useful to know as then making pendulum watches to work, say in different environments (such as under water), will be easier to make. It has future implications in industries and/ or technologies that produce related devices. Overall, this experiment was flawed from the beginning from not correctly applying the small angle criteria (in methods 2 and 3). However, there was success for method 1. (Reduced from a full lab report) Written by Siam Sama Related article: Viscosity of castor oil experiment

In wound care Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link The bright future of smart bandages 04/07/25, 12:57 Last updated: Published: 19/09/23, 16:30 In wound care Although wounds may seem miscellaneous to the naked eye, they can pose a great threat to the healthcare system, by overburdening health services through infections. Thus, it is essential to navigate wound care thoroughly to reduce burden and increase patient quality of life. Wounds can be caused by an array of different reasons and pose such a great threat because of the limited ways we’ve had to treat them which has resulted in issues such as antibiotic resistance, allergic reactions and so on. In recent times to enable higher quality treatment, a new invention known as the “smart bandage” has been made which uses nothing but light-emitting diode (LED) at its disposal to promote wound healing! The smart bandage is wireless and uses ultraviolet C radiation light (UVC) to sterilise wounds and prevent the risk of infection. This in turn decreases the chances of nosocomial incidences as well as opening doors for disinfection other than antibiotics or chemical based methods. The smart bandage is embedded with light emitting diodes called LEDs which emit UVC wavelength around 265-285nm using a controller. The smart bandage operates by effectively manipulating UVC’s germicidal and antimicrobial properties. Researchers produced a coil which is inductive and flexible so that the technology would easily be inserted into conventional fabric bandages. Wireless power via magnetic resonance is used by the coil so that the UVC LED’s can be powered without batteries being used. A second coil wirelessly transmits power to the inductive coil via electrical mains so that the LED is continuously receiving power supply till the required bacteria in the wound are eradicated. Scientists tested this technology on pathogens like Pseudoalteromonas sp , which are bacteria associated with bloodstream infections, surgical areas as well as wounds. Once the bacteria were cultured and grown, UVC LEDs were exposed to the culture which in turn resulted in the decreased growth of bacterial cells and within six hours completed stopped their growth by causing DNA damage leading to apoptosis of the bacterial cells. Currently, many wound treatment protocols involve the use of antibiotics which over time can lead to antibiotic resistance, thus straining health services by increasing hospital stays. The use of UVC based bandages not only decreases the risk of these consequences but is also environmentally friendly due to its low operating cost and reusability. Figure 4 also demonstrates added advantages of this technology. Looking forward, the revolutionary ability of smart bandages is undeniable. Currently, there is ongoing research being conducted into integrating a monitoring device which also has the capacity to send live data to healthcare professionals regarding the wound being treated. However, the results from this study are still to be replicated and tested in clinical studies. Although these innovations exhibit much promise by providing more flexible and higher quality care for patients, it is still in its infancy. But, it cannot be left unstated that the power of LED’s is remarkable, not only in their ability to treat but also in being economically beneficial. Written by Irha Khalid Related article: Virtual reality in healthcare Project Gallery

Ampere's Law and Faraday's Law Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Basics of transformer physics Last updated: 01/10/25, 10:49 Published: 24/04/25, 07:00 Ampere's Law and Faraday's Law Transformers have been around for decades. No, not the robots from the science fiction film franchise, although that would be amazing. Rather, the huge, technologically complex metal box-like things that play a key role in the electrical grid. You have likely seen transformers hidden behind extensive fencing, cabling, and ‘Danger! High Voltage!’ warning signs. These areas are not exactly accessible to tourists. Transformers play a crucial part in providing power to everything from your electric toothbrush to heating for your house to giant factories and just about anything in between. So it may come as a surprise that since their invention in the late 1800s, very little about them has changed. There are a number of different types of transformers that vary depending on voltage level, end user, location, etc. However, this article will only cover conventional transformers or, more specifically, the basic physics concepts behind how a typical transformer works. For those without a physical or electrical background, transformers can seem impossible to understand, but there are only two physics laws you need to understand: Ampere’s Law and Faraday’s Law. Ampere’s Law When charged particles like electrons flow in a particular direction, such as through a wire, this is an electric current . The moving charged particles affect the energy surrounding the wire, and we call this changing energy a magnetic field . Ampere’s Law mathematically describes the relationship between the flowing electrical current and the resultant magnetic field. The more intense the electrical current is, the stronger the magnetic field. Faraday’s Law Faraday’s Law allows us to predict how the magnetic field and the electrical current will interact. This interaction produces an electromotive force , which essentially means that as a magnetic field changes over time, it produces a force that creates or induces an electrical current. Basic physics of the transformer core Conventional transformers harness both Ampere’s Law and Faraday’s law in its core. The core is made of sheets of silicon steel, also known as electrical steel, that are very carefully stacked together. They are manufactured to form a square-like closed loop. A wire is wound on one side of the square loop, which carries the input current from the power source. On the opposite side of the square loop, a second wire is wound, which carries the output current leading farther downstream into the electrical grid. This may be to a ‘load’ or endpoint for the current, i.e. a house, warehouse, etc. Wire 1, carrying the input current, is not physically connected to Wire 2, the output current. These are two completely different wires. Ampere’s Law + Faraday’s Law is used to create, or induce , the output current in Wire 2. Recall that a moving electrical current creates a magnetic field. This is what occurs on the side of the core with Wire 1. The input current flows along Wire 1 as it coils around that side of the core, and a strong magnetic field is produced. For all intents and purposes, we can say that Wire 2 is ‘empty’, meaning that there is no input current here - it is not connected to a power source. However, as the current in Wire 1 produces a magnetic field, this field affects the energy around Wire 2 and induces a current in Wire 2, which then flows out of the transformer farther into the electrical grid. While there are different types of transformers with varying core configurations as well as additional complex physics to consider during manufacturing, it is too extensive to consider in this article. However, the processes described here form the basis of conventional transformer physics. Written by Amber Elinsky Related article: Wireless electricity Project Gallery

The current conflict has caused unfathomable mental distress and health problems for the Kashmiri people Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Health gaps in conflict-affected Kashmir Last updated: 18/09/25, 08:41 Published: 17/07/25, 07:00 The current conflict has caused unfathomable mental distress and health problems for the Kashmiri people This is article no. 5 in a series about global health injustices. Previous article: Syria and Lebanon ’s diverging yet connected struggles . Next article: Health inequalities in Bangladesh . Introduction Welcome to the fifth article of the Global Health Injustices Series. The previous article was a collaborative endeavour focused on the populations in Syria and Lebanon. Now, I will focus on the people living in Kashmir, who are currently experiencing a lot of health and wellbeing challenges, primarily attributed to conflict. For example, on top of the enduring conflict in Kashmir, the COVID-19 pandemic had worsened the mental health of the Kashmiri population, where 1.8 million adults were living with any type of mental distress. Despite these concerns, the Kashmiri people have not had their voices heard as clearly in mainstream discourse compared to other vulnerable populations discussed in previous articles. Kashmir: a rich history to current conflict Kashmir (also known as Jammu & Kashmir) is a region within the Northern Indian subcontinent, bordered mainly by Pakistan and China. Kashmir is a disputed territory between the militaries of India and Pakistan since the Indian subcontinent was divided up by the British Empire in 1947. Even before that, conflicts were driven by issues with local governments and tensions between cultural and ethnic groups within the region. These issues, among others, have contributed to the instability and health challenges encountered by the Kashmiri people. In recent years, tensions and violence have accelerated, particularly in 2024, due to the Indian government wanting to maintain control of the Kashmiri region. This has led to vast protests and friction between civilians and armed forces. In turn, this has weakened ties within the region, particularly between India and neighbouring nations. Another overlooked impact (which I will be discussing further) of this current conflict is on Kashmiri women, who encounter certain challenges, which include loss of family members, displacement and Gender-Based Violence. Considering this background of Kashmir is crucial because it will help with understanding the current geopolitical climate and how it detrimentally affects the health of the Kashmiri people. Geopolitics and health in Kashmir Similar to the populations discussed in previous articles, the Kashmiri people are encountering a lot of mental distress attributed to the ongoing conflict. One study from 2009 found that the prevalence of depression was 55.72%. Meanwhile, another study from 2017 uncovered that approximately 45% of adults experienced mental distress, with specific rates of 41% for depression, 26% for anxiety, and 19% for post-traumatic stress disorder (PTSD). This difference presumably came from wider geopolitical factors, as measuring mental health is challenging during conflict. As such, the healthcare system in Kashmir needs urgent improvement to better support mental health. Even though it does better in some areas compared to the national average, the demand for services, especially in conflict-affected areas, is overwhelming. There are not enough mental health professionals, and many healthcare providers lack the training to handle trauma-related issues properly. Investing in training, community mental health initiatives, and integrating mental health services with regular healthcare could help improve the overall mental health of the Kashmiri people. Focusing on mental health just as much as physical health to build resilience in Kashmir is essential. As for the health infrastructure in Kashmir, noted in one review, they have 4433 government health institutions and a doctor-patient ratio of 1:1880, which is lower than the World Health Organisation (WHO) recommendation of 1:1000, yet higher than the national level of 1:2000. Moreover, the state of Kashmir was shown to have better health indices compared to the national average, including life expectancy, infant mortality rate, and crude birth and death rates. Despite these improvements, challenges persist, such as the inadequate health infrastructure and a shortage of financial resources and technical staff, despite relatively stable trends ( Table 1 ). In one study, the authors noted that among the Schedule tribes in Kashmir, they encounter significant health challenges attributed to illiteracy, poverty, and inadequate healthcare facilities and infrastructure, leading to increased non-communicable diseases (NCDs). There is a high prevalence of poor nutrition and undernutrition, which contributes to the susceptibility of these populations to NCDs (7). Moreover, a lack of access to clean water and sanitation worsens health issues, which increases their risk of infectious diseases. Social taboos and beliefs hinder healthcare service utilisation among the population, which impacts health outcomes and even awareness of NCDs ( Figure 1 ). Focusing on violence exposure in Kashmir, another study among households found that respondents documented high levels of violence, which include: exposure to crossfire (85.7%), round-up raids (82.7%), witnessing torture (66.9%), experiences of rape (13.3%) and forced labor (33.7%). What this study also found was that males noted more violent confrontations and had higher odds of experiencing different forms of maltreatment compared to females. Given that this study was conducted in 2008, these figures are likely to be either higher or lower now, depending on the magnitude of violence and warfare. Nonetheless, the high frequency of violence has led to substantial health issues, specifically mental health problems among the affected Kashmiri population. A severely overlooked impact of conflict in Kashmir is on the women, who encounter specific tragedies, including loss of family members and displacement. Moreover, the use of rape as a weapon in conflict stresses the convergence of gender and political power, particularly in Kashmir. Unfortunately, there have been some researchers who usually depict Kashmiri women as solely victims, which can undermine their autonomy and political involvement. Therefore, addressing the plight of Kashmiri women by allowing them to discuss their experiences openly and actively involving them in key decisions regarding Kashmir can be a vital stepping stone towards supporting their health and well-being. To truly understand all of the various health challenges illustrated above impacting the Kashmiri population, it is vital to cite the various geopolitical factors I discussed in previous articles on Yemen, Sudan and Palestine. The most notable factor is the continuous international weapons/ arms trade, which I firmly believe must be thwarted because of how much damage it has caused, particularly through the sale of bombs and other explosives used to target the most vulnerable populations. However, stopping this trade requires actual political will and legislation, which is unlikely to happen anytime soon because our leaders make a lot of profit from selling weapons. NGOs: their role in supporting Kashmir International non-governmental organisations (INGOs), notably Aakar Patel, chair of board at Amnesty International India, shared this statement in 2024 regarding Kashmir: The Indian authorities are using arbitrary restrictions and punitive actions to create a climate of fear in Jammu and Kashmir. Anyone daring to speak out – whether to criticize the government or to stand up for human rights – faces a clampdown on their rights to freedom of expression and association and cannot move freely within and outside the country. Amnesty International also shared testimonies from a few Kashmiri people: I feel a deep responsibility to be the voice of my people, who are currently voiceless. There are no stories coming out of Kashmir anymore. - Masrat Zahra, an award-winning Kashmiri photojournalist. My freedom of movement is a right enshrined in the Indian Constitution, but I had to really struggle to exercise this right. - Iltija Mufti, daughter and media advisor to ex-chief minister of Jammu & Kashmir. To address the complex health and social issues previously discussed, international organisations and local communities need to come together for solutions. Programs focusing on building mental health support, improving healthcare availability, and creating safe spaces for women and young people can make a difference. The Kashmiri people need to have their voices heard in discussions about their health and wellbeing. Otherwise, their challenges will continue to affect their lives. Conclusion Overall, the health and well-being issues in Kashmir are closely linked to the long-standing conflict and warfare. Although this region has a rich cultural history and shows a lot of resilience, the current conflict has caused unfathomable mental distress and health problems for the Kashmiri people. The rise in mental health issues and the inadequate healthcare infrastructure illustrate that reforms are urgently needed. There is a real shortage of support for mental health, particularly when dealing with the trauma from ongoing violence. Moreover, marginalised groups face tremendous health challenges because of various factors ranging from poverty to a lack of education to limited access to basic needs. Living in violence and conflict not only affects physical health, but also leads to ongoing psychological trauma that is often ignored. Tackling these health inequalities and inequities requires a comprehensive approach incorporating mental health care into the standard healthcare system, improving access to clean water and food, and building communities. Listening to the Kashmiri people and focusing on their health needs is key to achieving peace and better living standards in the region. Therefore, national and international players must recognise these issues and take real action to ensure they receive the support they need and deserve. Only with continued efforts can we expect a healthier future for Kashmir. The following article in the Global Health Injustices series will focus on Bangladesh and the plight of the Rohingya population, which will also be a collaborative endeavour. Written by Sam Jarada Related articles: Impacts of global warming on dengue fever / Understanding health through different stances / South Asian famine / South Asian mental health REFERENCES Sheikh Shoib, Arafat SMY. Mental health in Kashmir: conflict to COVID-19. Public Health. 2020 Sep 1;187:65–6. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC7484691/ Center for Preventive Action. Conflict Between India and Pakistan. Global Conflict Tracker. 2015. Available from: https://www.cfr.org/global-conflict-tracker/conflict/conflict-between-india-and-pakistan Zeeshan S, Hanife Aliefendioğlu. Kashmiri women in conflict: a feminist perspective. Humanities and Social Sciences Communications. 2024 Feb 12;11(1). Available from: https://www.nature.com/articles/s41599-024-02742-x Amin S, Khan A. Life in conflict: Characteristics of Depression in Kashmir. International Journal of Health Sciences. 2009 Jul;3(2):213. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC3068807/ Housen T, Lenglet A, Ariti C, Shah S, Shah H, Ara S, et al. Prevalence of anxiety, depression and post-traumatic stress disorder in the Kashmir Valley. BMJ Global Health. 2017 Oct;2(4):e000419. Available from: https://gh.bmj.com/content/2/4/e000419 Mir A, Bhat S. Health Status and Access to Health Care Services in Jammu and Kashmir State. Asian Review of Social Sciences [Internet]. 2018;7(3):52–7. Available from: https://www.trp.org.in/wp-content/uploads/2018/11/ARSS-Vol.7-No.3-October-December-2018-pp.52-57.pdf Habib A, Iqbal A, Rafiq H, Shah A, Amin S, Suheena, et al. Trends in the Magnitude of NCDs among Schedule Tribe Population of Kashmir with Special Reference to Health and Nutritional [Internet]. Journal of Community Medicine & Public Health. Gavin Publishers; 2023 [cited 2025 May 5]. Available from: https://www.gavinpublishers.com/article/view/trends-in-the-magnitude-of-ncds-among-schedule-tribe-population-of-kashmir-with-special-reference-to-health-and-nutritional Jong K de, Ford N, van, Kamalini Lokuge, Fromm S, Galen R van, et al. Conflict in the Indian Kashmir Valley I: exposure to violence. Conflict and Health [Internet]. 2008 Oct 14 [cited 2025 May 5];2(1). Available from: https://conflictandhealth.biomedcentral.com/articles/10.1186/1752-1505-2-10 Authorities must end repression of dissent in Jammu and Kashmir [Internet]. Amnesty International. 2024 [cited 2025 Jun 11]. Available from: https://www.amnesty.org/en/latest/news/2024/09/india-authorities-must-end-repression-of-dissent-in-jammu-and-kashmir/ Project Gallery

It's in the diet Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link How epigenetic modification gives the queen bee her crown 23/01/25, 11:52 Last updated: Published: 26/11/23, 10:46 It's in the diet Honey bee colonies are comprised of three kinds of adult bees: workers, drones and a single queen. While all drones are male, the queen and the worker bees are female. Within the female population, only the queen bee is fertile and is thus responsible for laying eggs which are fertilised by drones. Additionally, a queen bee is larger than worker bees and produces pheromones to allow the colony to function. However, worker and queen bees are genetically identical, so how is it possible that they are so fundamentally different? ( Figure 1 ) The answer lies in epigenetic modification , defined as the alteration in gene function without a change in the DNA sequence. Types of epigenetic regulation include histone modification, DNA methylation and action of noncoding RNA. The honey bee Apis mellifera is amongst the many species that can produce different characteristics of organisms using the same genome. The mechanism by which honey bees do this derives from epigenetic modification resulting from the difference in diet during larval development. All larvae feed on royal jelly during the first three days of their development ( Figure 2 ). However, worker larvae will then feed on a diet of honey and pollen, which constitutes worker jelly. In comparison, the queen larva maintains a diet of royal jelly; this is a complex mixture produced by nurse bees and contains water, crude protein, monosaccharides, and fatty acids. Subsequently, the difference in dietary intake provides information to facilitate the correct epigenome which in turn allows correct transcription. Thus, key studies have taken place to investigate the effect of epigenetic marks on the development of bees. DNA methyltransferase DNMT3 is responsible for the methylation of DNA and is a repressive mark; a study found that the silencing of DNMT3 resulted in worker larvae developing into queens that had developed ovaries. Consequently, this shows that royal jelly gives information to larvae destined to be queens that can be interpreted to apply the correct epigenome. Additionally, certain histone deacetylase inhibitors have been observed in royal jelly including the compound 10 HDA and phenylbutyrate. Histone acetylation within regions of the genome results in chromatin opening; acetylation is associated with active regions. HDACi activity will inhibit the removal of such acetylation and maintain open regions of DNA. However, note that worker bees are not just a repressed version of queen bees, as they have overexpressed genes of their own to facilitate their specific behaviours. On examination of the methylome (see Figure 3 ), different genes were identified as being hypo- or hyper- methylated within worker vs queen bees. See the table below for a detailed analysis of worker and queen bees on days 3-5 of development. How exactly the specificity of epigenetic modifications is accomplished is not completely realised. To exemplify this, DNMTs do not have specificity, and thus, there must be an interplay between chromatin modifiers and cellular components to accomplish the correct recruitment of enzymes involved in epigenetic modification. However, it is clear that the epigenomes of workers vs queen bees are decidedly different and thus are the cause of different physiological and behavioural characteristics. Written by Isobel Cunningham Related articles: An introduction to epigenetics / Famine-induced epigenetic changes Project Gallery

Discussing Peto's Paradox Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Why blue whales don't get cancer 14/07/25, 15:16 Last updated: Published: 16/10/23, 21:22 Discussing Peto's Paradox Introduction: What is Peto’s Paradox? Cancer is a disease that occurs when cells divide uncontrollably, owing to genetic and epigenetic factors . Theoretically, the more cells an organism possesses, the higher the probability should be for it to develop cancer. Imagine that you have one tiny organism – a mouse, and a huge organism – an elephant. Since an elephant has more cells than a mouse, it should have a higher chance of developing cancer, right? This is where things get mysterious. In reality, animals with 1,000 times more cells than humans are not more likely to develop cancer. Notably, blue whales, the largest mammals, hardly develop cancer. Why? In order to understand this phenomenon, we must dive deep into Peto’s Paradox. Peto’s paradox is the lack of correlation between body size and cancer risk. In other words, the number of cells you possess does not dictate how likely you are to develop cancer. Furthermore, research has shown body mass and life expectancy are unlikely to impact the risk of death from cancer . (see figure 1) Peto’s Paradox: Protective Mechanisms Mutations, otherwise known as changes or alterations in the deoxyribonucleic acid (DNA) sequence, play a role in cancer and ageing. Research scientists have analysed mutations in the intestines of several mammalian species , ranging from mice, monkeys, cats, dogs, humans, and giraffes, to tigers and lions. Their results reveal that these mutations mostly come from processes that occur inside the body, such as chemicals causing changes in DNA. These processes were similar in all the animals they studied, with slight differences. Interestingly, annually, animals with longer lifespans were found to have fewer mutations in their cells ( figure 2 ). These findings suggest that the rate of mutations is associated with how long an animal lives and might have something to do with why animals age. Furthermore, even though these animals have very different lifespans and sizes, the amount of mutations in their cells at the end of their lives was not significantly different – this is known as cancer burden. Since animals with a larger size or longer lifespan have a larger number of cells (and hence DNA) that could undergo mutation, and a longer time of exposure to mutations, how is it possible that they do not have a higher cancer burden? Evolution has led to the formation of mechanisms in organisms that suppress the development of cancerous cells . Animals possessing 1,000 times as many cells as humans do not display a higher susceptibility to cancer, indicating that natural mechanisms can suppress cancer roughly 1,000 times more efficiently than they operate in human cells . Does this mean larger animals have a more efficient protective mechanism against cancer? A tumour is an abnormal lump formed by cells that grow and multiply uncontrollably. A tumour suppressor gene acts like a bodyguard in your cells. They help prevent the uncontrollable division of cells that could form tumours. Previous analyses have shown that the addition of one or two tumour suppressor gene mutations would be sufficient to reduce the cancer risk of a whale to that of a human. However, evidence does not suggest that an increased number of tumour suppressor genes correlated with increasing body mass and longevity. Although a study by Caulin et al . identified biomarkers in large animals that may explain Peto’s paradox, more experiments need to be conducted to confirm the biological mechanisms involved. Just over a month ago, an investigation of existing evidence on such mechanisms revealed a list of factors that may contribute to Peto’s paradox. This includes replicative immortality, cell senescence, genome instability and mutations, proliferative signalling, growth suppression evasion and cell resistance to death. As far as we know, different strategies have been followed to prevent cancer in species with larger sizes or longer lifespans . However, more studies must be conducted in the future in order to truly explain Peto’s paradox. Peto’s Paradox: Other Theories There are several theories that attempt to explain Peto’s paradox. One of which explains that large organisms have a lower basal metabolic rate, leading to less reactive oxygen species. This means that cells in larger organisms incur less oxidative damage, causing a lower mutation rate and lower risk of developing cancer. Another popular theory is the formation of hypertumours . As cells divide uncontrollably in a tumour, “cheaters” could emerge. These “cheaters”, known as hypertumours, are cells which grow and feed on their original tumour, ultimately damaging or destroying the original tumour. In large organisms, tumours have more time to reach lethal size. Therefore, hypertumours have more time to evolve, thereby destroying the original tumours. Hence, in large organisms, cancer may be more common but is less lethal. Clinical Implications Curing cancer has posed significant challenges. Consequently, the focus on cancer treatment has shifted towards cancer prevention . Extensive research is currently underway to investigate the behaviour and response of cancer cells to the treatment process. This is done through a multifaceted approach; investigating the tumour microenvironment and diagnostic or prognostic biomarkers. Going forward, a deeper understanding of these fields enables the development of prognostic models as well as targeted treatment methods. One example of an exciting discovery is the revelation of TP53 . The discovery of this tumour suppressor gene indicates that it plays a role in making elephant cells more responsive to DNA damage and in triggering apoptosis by regulating the TP53 signaling pathway. These findings imply that having more copies of TP53 may have directly contributed to the evolution of extremely large body sizes in elephants, helping resolve Peto’s paradox . Particularly, there are 20 copies of the TP53 gene in elephants, but only one copy of the TP53 gene in humans (see figure 3 ). Through more robust studies and translational medicine, it would be fascinating to see how such discoveries could be applied into human medicine ( figure 4 ). Conclusion The complete mechanism of how evolution has enabled organisms that are larger in size and have longer lifespans than humans is still a mystery. There is a multitude of hypotheses that need to be extensively investigated with large-scale experiments. By unravelling the mysteries of Peto’s paradox, these studies could provide invaluable insights into cancer resistance and potentially transform cancer prevention strategies for humans. Written by Joecelyn Kirani Tan Related articles: Biochemistry of cancer / Orcinus orca (killer whale) / Canine friends and cancer Project Gallery

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