BIOLOGY MAGAZINE SUMMER 2025
ft#‘The#amazing# world#of#sea# slugs’#by#Dr# Thorne#
NB the magazine’s theme applies to images + facts throughout the magazine, however not necessarily the content of individual articles
How chocolate a+ects dogs
Lucy Francis-Jones, LVI
Discovering Diabetes
Amy Lukama and Annabelle Wong, Y8
Animal of the Issue
Tardigrades
How diet and medication can a+ect the gut-mind connection and in turn the early development of children
Victoria Stefak, Y11
The amazing world of sea slugs
Dr Thorne, staD
Pictures taken by Daisy M, 2019
How chocolate affects dogs
LUCY FRANCIS-JONES, LVI
Chocolate’s main ingredient, cacao, contains two compounds that are toxic to dogs: theobromine (3,7dimethylxanthine) and caffeine (1,3,7-trimethylxanthine).
Theobromine Caffeine
Theobromine is a naturally occurring compound, and a bitter alkaloid of the methylxanthine class, along with caffeine. An alkaloid is a nitrogenous organic compound of plant origin which have physiological actions on humans and animals.
After ingestion, theobromine and caffeine are readily absorbed from the GI tract and widely distributed throughout the body. They undergo hepatic metabolism, which is a mechanism that converts drugs and other compounds into products with a lower pharmacological activity that are easily excreted. After this, they commence enterohepatic recycling which circulates substances from the liver to bile, followed by entry into the small intestine, absorption by the intestinal absorptive cells and transport back to the liver. They are then excreted in urine as metabolites and unchanged parent compounds.
Dogs are sensitive to them as they stimulate the nervous and cardiovascular systems. They inhibit cellular adenosine receptors, resulting in CNS stimulation, diuresis, and tachycardia. Adenosine receptors comprise of a group of G protein-coupled receptors which mediate the physiological actions of adenosine. The inhibition of adenosine receptors prevents the signalling that would occur when adenosine attaches to its receptor.
Theobromine can greatly overstimulate the brain and other parts of the nervous system, leading to excitability, hyperactivity and restlessness, and tremors and convulsions in severe cases. Diuresis is a condition in which the kidneys filter too much bodily fluid leading to an increase in urine production, this quickly results in dehydration. Frequent urination and excessive drinking are both common signs of chocolate poisoning in dogs.
The increases in heart rate are due to an increase in intracellular calcium levels. This occurs by increasing cellular calcium entry and inhibiting intracellular sequestration of calcium by the sarcoplasmic reticulum of striated muscle. This increases the strength and contractility of skeletal and cardiac muscle. Methylxanthines also compete for benzodiazepine receptors within the CNS and inhibit phosphodiesterase, this results in increased levels of cyclic adenosine monophosphate (cyclic AMP), which again, leads to an increased heart rate. Theobromine and caffeine may also increase circulating levels of epinephrine and norepinephrine, which are neurotransmitters which also act as hormones. They increase blood pressure by causing vasoconstriction, increasing cardiac output.
The length of time these harmful compounds will stay in the body causing damaging effects depends on how much the dog has eaten, the concentration of cacao in the chocolate, and the size of the dog. The half-lives of theobromine and caffeine in dogs 17.5 hours and 4.5 hours respectively. A half-life refers to the amount of time it takes for a quantity of substance to reduce to half its initial value. This means that it can take a few days for the substance to be fully eliminated from the dog’s system.
BIOLOGICALLY RELEVANT – LVI COOLEST dog competition
SHINIEST HAIR + KINDEST SMILE
Norton & Ostro, Celeste O.
CELEBRITY LOOKALIKE
Dixie, Rosie E.
MOST NONCHALANT Buddy, Caroline S.
rabbits are also intolerant to chocolate! (not that these are rabbits)
BEST DOGS + Best Kept Pet x6
Winnie & Ludo, Sophia D.
OVERALL CUTEST Fudge, Cristabel V.
MOST MAJESTIC
Muttley, Lucy F
Discovering Diabetes
AMY LUKAMA & ANNABELLE WONG, YEAR 8
Have you ever wondered why some people take injections in between meals? Or have you ever wondered why some people wear devices on their body all the time? What even is this common disease? In this article, we will dive deeper into what diabetes is and what eWects it can bring.
Diabetes is a chronic disease that aWects the way your body turns food into energy. There are two main types of diabetes: Type 1 and Type 2. Type 1 diabetes is an autoimmune disease which means that your body's immune system uses anti islet cells antibodies to attack and destroy the beta cells, which are a major type of cell within the islets of Langerhans in your pancreas (located below and behind your stomach) that produce insulin. Type 2 diabetes is a condition in which your body either does not produce enough insulin or cannot utilise insulin properly due to your insulin receptors not working. Insulin receptors are needed to bind with insulin, which allows glucose to enter your cells for energy. Diabetes is usually caused by (but not limited to) unhealthy diets, obesity, high blood pressure or genetics (although that only applies to Type 2).
TYPE 1 DIABETES
TYPE 2 DIABETES
Now you’re probably wondering, what even is insulin and why is it so important? Insulin is a hormone that is needed to send glucose from the bloodstream into the cells of the body, where it can be used for energy and respiration. Insulin is usually produced by the pancreas when a spike in sugar levels occurs in your body, which happens after eating meals, etc. Without enough insulin, your body is unable to use sugar to provide the energy it needs for everyday tasks. This causes hormones that break down fat and muscle to be released for the body to release fuel, which produces acids called ketones. Ketones make you feel sick and light-headed and can lead to weight loss.
Diabetes can be managed in diWerent ways to ensure the patient’s health in the long term. This can be achieved through injecting insulin, regular stress/body checkups or just by having a healthy lifestyle and diet. Checking up on one’s mental wellbeing can prevent cardiovascular diseases and improves your mental health. Ideally, a diabetic person would want to have a balanced nutritious diet that is low in sugars but also rich in fibre as it helps stabilise sugar levels. Regular exercise like having a walk or a jog, strength training or pilates can improve insulin sensitivity and overall fitness.
Puzzle page!
Riddles
They named me fish, but they were wrong. I have lungs, yet swim lifelong. I give live birth, I form strong ties, Use sonar just to analyse. I leap with joy, I form a pod Not scaled or gilled just oddly shod. What am I?
I eat the light and breed in dark, Too small to see, too vast to mark. Without me, all the oceans die Yet most don’t know I even lie. I breathe for you and birth the breeze, I build the storm, I calm the seas. Who am I, countless, still unknown, The smallest god you've ever known? What am I?
The background image is a school of Indian Ocean oriental sweetlips. They are native to the Indian Ocean and western Pacific Ocean. The name ‘sweetlips’ comes from their small mouths and teeth compared to their thicker, fleshy lips
What did the shark plead in the murder case? Not gill-ty!
Where do killer whales go to get braces? The orca- dontist!
What kind of sharks do you find at construction sites? Hammerheads!
Why are fish so easy to weigh? Because they have their own scales!
Bobtail squid
Animal of the Issue
The humble TARDIGRADE
Also known as ‘water bears’ or ‘moss piglets’
Tardigrades are microscopic (usually around 1mm in length), eight-legged animals that have been on earth for over half a billion years and are found in a wide variety of environments all over the world, however, they thrive in moist environments such as damp moss or underwater sediment. Alternative environments they have been found in include sand dunes, mountaintops, tropical rainforests, the deep sea and the Antarctic. They have achieved fame through their incredible resilience and seemingly indestructible nature.
Tardigrades have been known to survive:
à Low temperatures of 0.05 Kelvins (-272.95 ºC, essentially absolute zero) and high temperatures of 150 ºC
à Pressures of 40,000 kilopascals
à The burning UV radiation of space
à Being shot from a high-speed gun (travelling at roughly 900m per second and at the impact of 1.14 gigapascals of pressure
à Being stored in a freezer for 30 years (as you do)
à The vacuum of space! The use of tardigrades in space, first proposed in 1964 because of their extreme tolerance to UV radiation, began in 2007 with the FOTON-M3 mission in low Earth orbit, where they were exposed to space’s vacuum for 10 days and reanimated, just by rehydration, back on Earth. Subsequent mortality was high, but many were able to produce viable embryos before they died.
Despite these impressive stats, it’s worth noting that tardigrades are not technically classed as “extremophiles because they don’t thrive in harsh conditions – they simply survive. These robust little creatures have been on Earth for roughly 600 million years –preceding the dinosaurs by around 400. In fact, tardigrades have survived all 5 mass extinction events, and it is thought that they could be around long after humanity has died out. In 2017, researchers from Oxford and Harvard Universities decided to test how resilient diierent forms of life were to potential astrophysical events – things like asteroids, supernova blasts and gamma ray bursts. Of course, humans stood no chance. But who stuck around? Tardigrades.
But how do they survive so well?
Though tardigrades can be found in moss and lichens, they are still – as per their evolutionary history – truly an aquatic animal. They require a film of water to surround their bodies to allow them to take in oxygen and expel carbon dioxide. Without this, they start to dry out, stop metabolising, and curl up into a desiccated form known as a tun state (a tun is a type of large barrel, which is what they end up looking like). The incredible thing is that with the tiniest bit of water, they immediately bounce back into their original metabolising state. The bottom half of the chart shows three states of cryptobiosis, in which metabolism is suspended to almost undetectable levels of <0.01% of normal –an act usually diagnostic of death. While there isn’t enough space in this entire magazine to fully explain all terms relevant to this, tardigrades are an extremely interesting scientific rabbit hole that we highly recommend going down independently!
How diet and medication can affect the gut -mind connection and in turn the early development of children
VICTORIA STEFAK, YEAR 11
The gut-brain connection refers to how the central nervous system and gastrointestinal tract work together1 . This communication occurs through nerves and neurotransmitters such as dopamine, gammaaminobutyric acid (short for GABA) and serotonin which are produced by gut microbes2. Dopamine helps with emotional regulation, while3 GABA is produced by Lactobacillus and Bifidobacterium, regulates excitation inhibition balance in the brain and modulates immune responses4. Although serotonin does not cross the blood-brain barrier, it influences immune function and brain signaling5. Disruptions in the gut microbiome, caused by factors like stress, medication, nutrition and lifestyle choices, can lead to obesity, inflammatory bowel disease, allergies and neurodevelopmental disorders6. In children, these factors, three of which I will discuss in this essay – diet, mode of birth and antibiotics - play a crucial role in shaping this connection.
The first three years of a child’s life are critical for the development microbiome7, neurodevelopment, immune function and nutrient metabolism, although the exact timing can vary by sex. Over this period of time, microbiomes are primarily composed of Lactobacillus, Staphylococcus and Bifidobacterium cells8 Neuroimmune cells communicate with metabolites and gut microbes, influencing the blood-brain barrier formation. Around 86 billion neurons develop and 100 trillion connections are made9 . Between ages one and two, microbial diversity rapidly increases and by age three, the infant microbiome stabilises into an adult-like composition, similar to that of family members 10. To support this process, both the mother and infant's diet are crucial. Both overnutrition and malnutrition can impair brain development, leading to cognitive issues later on in life11 . Maternal microbes cross the placenta and influence fetal circulation, acting as metabolic regulators that break down foods to produce essential fatty acids, amino acids and vitamins needed for immunity and fetal growth12 Optimal growth of the fetus occurs in the third trimester when maternal metabolism peaks13 . A poor maternal diet, such as one lacking in folate, can lead to cognitive deficits, heightened stress responses, neurological abnormalities and behavioural issues in the child14. Furthermore, metabolic disruptions like gestational diabetes, can similarly harm the foetus15 . Additionally, maternal infections have been linked to disorders such as autism and schizophrenia16 .
After birth, infants are usually fed breast milk or formula milk. Breastfed infants receive bacteria and prebiotic human milk oligosaccharides (HMOs) that support immune and cognitive development17. This results in a more diverse microbiome similar to that of adults, compared to formula-fed infants. Formulafed infants often have a faster growing of the microbiome and are more likely to have bacteria such as Roseburia, Clostridium, Enterococcus and Anaerostipes, which which are associated with inflammation and metabolic disorders18 . At around six months19 , infants are gradually weaned off milk and introduced to solid foods. However, if introduced too early, they can cause immune dysregulation and inflammation. High-fiber diet increases the diversity of bacteria and promotes the growth of beneficial bacteria20 while carbohydrates reduces bacteria like Bifidobacteria and fatty acids21. The source, concentration and amino source, concentration, and amino acid balance of protein are key factors that influence the composition and function of gut microbes22. Vitamins and minerals help in the metabolism of neurotransmitters and how neurones produce and use energy to function23 .
Mode of birth is also responsible in shaping the gut microbiome. Babies born vaginally recieve maternal microbes, which help establish a diverse microbiome24 . In contrast, those born via cesarean section are exposed to skin and environmental bacteria which can affect cognitive function and reduce levels of Bifidobacterium25. Additionally, antibiotics given to pregnant women, such as intrapartum antibiotic prophylaxis (IAP) which is commonly used in cesarean sections26, can negatively influence the infant’s microbiome by the umbilical cord. They lower intestinal bacterial diversity and further reduce Bifidobacterium levels27. While these microbiome differences can last for a long time, they can be reversed by administering a prebiotic mixture to the infant28 .
On a broader scale, early exposure to general medications such as acid suppressants, antidepressants and steroid hormones during pregnancy, childbirth and infancy can alter the gut microbiome29. This disruption can lead to inflammations, metabolic diseases and an increase in genes that influence antibiotic resistance such as Enterobacteriaceae30, making children more susceptible to infections. Additionally, excess antibiotics leads to dysbiosis which is where where important bacteria species decrease and pathogenic microbes increase31 and an underdevelopment of the microbiome, increasing the risk of conditions such as obesity, asthma and allergies. Preventative strategies such as dietary therapy, probiotics, prebiotics and vagus nerve stimulation can help restore the microbiome balance and support the development of the child.
The gut-brain connection is extremely vulnerable during the early years of a child, particularly to factors such as diet, mode of birth, and antibiotic exposure. They can have a significant role in neurodevelopment, immune function, and overall health. Disruptions to the microbiome, whether through poor maternal nutrition, cesarean delivery, or excessive use of antibiotics can lead to cognitive issues, inflammation, and increased susceptibility to diseases. However, interventions like prebiotics, dietary therapy and vagus nerve stimulation could restore microbiomes and support child development.
Understanding the gut-brain connection early in life is essential for achieving long-term health.
Bibliography
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2. Bhatia, N. Y., Jalgaonkar, M. P., Hargude, A. B., Sherje, A. P., Oza, M. J., & Doshi, G. M. (2023). Gut-brain axis and neurological disorders How microbiomes affect our mental health. CNS Neurological Disorders Drug Targets, 22(7), 1008–1030. https://doi.org/10.2174/1871527321666220822172039
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4. Chao, Y. X., Gulam, M. Y., Chia, N. S. J., Feng, L., Rotzschke, O., & Tan, E. K. (2020). Gut-brain axis: Potential factors involved in the pathogenesis of Parkinson's disease. Frontiers in Neurology, 11, 849. https://doi.org/10.3389/fneur.2020.00849
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9. Huang, H., Jiang, J., Wang, X., Jiang, K., & Cao, H. (2024). Exposure to prescribed medication in early life and impacts on gut microbiota and disease development. EClinicalMedicine, 68, 102428. https://doi.org/10.1016/j.eclinm.2024.102428
10. Inchingolo, F., Inchingolo, A. D., Palumbo, I., Trilli, I., Guglielmo, M., Mancini, A., Palermo, A., Inchingolo, A. M., & Dip alma, G. (2024). The impact of Cesarean section delivery on intestinal microbiota: Mechanisms, consequences, and perspectives A systematic review. International Journal of Molecular Sciences, 25(2), 1055. https://doi.org/10.3390/ijms25021055
11. Jardon, K. M., Canfora, E. E., Goossens, G. H., & Blaak, E. E. (2022). Dietary macronutrients and the gut microbiome: A precision nutrition approach to improve cardiometabolic health. Gut, 71(6), 1214–1226. https://doi.org/10.1136/gutjnl-2020-323715
12. Laue, H. E., Coker, M. O., & Madan, J. C. (2022). The developing microbiome from birth to 3 years: The gut-brain axis and neurodevelopmental outcomes. Frontiers in Pediatrics, 10, 815885. https://doi.org/10.3389/fped.2022.815885
13. Meyer, U., Feldon, J., & Dammann, O. (2011). Schizophrenia and autism: Both shared and disorder-specific pathogenesis via perinatal inflammation? Pediatric Research, 69(5 Pt 2), 26R–33R. https://doi.org/10.1203/PDR.0b013e318212c196
14. Miko, E., Csaszar, A., Bodis, J., & Kovacs, K. (2022). The maternal-fetal gut microbiota axis: Physiological changes, dietary influence, and modulation possibilities. Life (Basel), 12(3), 424. https://doi.org/10.3390/life12030424
15. Morreal, C., Giaroni, C., Baj, A., Folgori, L., Barcellini, L., Dhami, A., Agosti, M., & Bresesti, I. (2023). Effects of peri natal antibiotic exposure and neonatal gut microbiota. Antibiotics (Basel), 12(2), 258. https://doi.org/10.3390/antibiotics12020258
16. Pedroza Matute, S., & Iyavoo, S. (2023). Exploring the gut microbiota: Lifestyle choices, disease associations, and personal genomics. Frontiers in Nutrition, 10, 1225120. https://doi.org/10.3389/fnut.2023.1225120
17. Ronan, V., Yeasin, R., & Claud, E. C. (2021). Childhood development and the microbiome The intestinal microbiota in maintenance of health and development of disease during childhood development. Gastroenterology, 160(2), 495–506. https://doi.org/10.1053/j.gastro.2020.08.065
18. Roza, S. J., van Batenburg-Eddes, T., Steegers, E. A. P., et al. (2010). Maternal folic acid supplement use in early pregnancy and child behavioural pro blems: The Generation R Study. British Journal of Nutrition, 103(3), 445–452. https://doi.org/10.1017/S0007114509991954
19. Sánchez, C., Fente, C., Regal, P., Lamas, A., & Lorenzo, M. P. (2021). Human milk oligosaccharides (HMOs) and infant microbiota: A scoping review. Foods, 10(6), 1429. https://doi.org/10.3390/foods10061429
20. Shennon, I., Wilson, B. C., Behling, A. H., Portlock, T., Haque, R., Forrester, T., Nelson, C. A., O'Sullivan, J. M.; M4EFaD consortium. (2024). The infant gut microbiome and cognitive development in malnutrition. Clinical Nutrition, 43(5), 1181–1189. https://doi.org/10.1016/j.clnu.2024.03.029
21. Tardy, A. L., Pouteau, E., Marquez, D., Yilmaz, C., & Scholey, A. (2020). Vitamins and minerals for energy, fatigue and cognition: A narrative review of the biochemical and clinical evidence. Nutrients, 12(1), 228. https://doi.org/10.3390/nu12010228
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The amazing world of sea slugs
DR THORNE
Sea slugs, or nudibranchs, are a poorly appreciated but beautiful group of marine invertebrates with over 3000 species (1). They are found all around the world from the polar regions to the tropics and there are approximately 108 species in UK waters (2).
Despite being related to the familiar slugs and snails, they have a wide variety in body shape, particularly the gills, and display a beautiful and vivid array of colours. In many, these colours are a warning to predators as they are frequently toxic or distasteful, sometimes utilising the toxins or other chemicals found in their prey, such as sea anemones and sponges.
Although they are so widely distributed and relatively easily found, more people are unfamiliar with nudibranchs as most are just a few centimetres in size. However, if you look closely when you are next snorkelling on holiday or rock-pooling in the UK, you may well see one of these charming little creatures.
References
1. https://ocean.si.edu/ocean-life/invertebrates/collage-nudibranch- colors 21/02/2025
2. http://www.seaslug.org.uk/nudibranchs/intronud.html 21/02/2025
Nembrotha kubaryana which can grow up to 12cm in length https://www.nhm.ac.uk/discover/nudibranchspsychedelic-thieves- of-the-sea.html (21/02/2025)
Nembrotha lineolata https://ilovenudis.com/blogs/nudibranchsaround-the-world/nudibranchs- of-japan (21/02/2025)
The violet sea slug which is found in rocky areas of the UK. https://www.mcsuk.org/news/sea-slugs-a-rainbowof-life-in- our-seas/ (21/02/2025)
The blue dragon sea slug
https://www.nhm.ac.uk/discover/nudibranchspsychedelic-thieves- of-the-sea.html (21/02/2025)
Puzzle SOLUTIONS
What am I?
A dolphin, phytoplankton
CREDITS
You have just finished reading the very first edition of Biology Magazine! We hope you enjoyed reading it as much as we enjoyed putting it together.
Our aim with this magazine is to spark curiosity no matter your age or interests. That being said, feel free to email us if you have any ideas or want to contribute to future editions in any way! Thank you for reading , and we’re excited to share more with you in magazines to come.
We would like to give special thanks to:
à our brilliant authors – Lucy Francis-Jones, Amy Lukama, Annabelle Wong, Victoria Stefak and Dr Thorne
à Mr Ellott for directing the logistics of the magazine
à Mr Dibsdall for overseeing its release
à Mr West and Mrs Maskell for providing technological assistance
à Font Adviser Ginevra Maria Chiara D’Avanzo
à A ssistant to the Font Adviser Iris Whiteley
à Font Analyst Marta Entrecanales
à tCPF Annie Wilson, CGM Emilia Harvey and OKicial Chief Jokester Chiara ChisenhaleMarsh
See you next time!
Isabella Ooms de Calonje & Daisy Marsden, Lower Sixth