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  • The Y chromosome unveiled | Scientia News

    Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link The Y chromosome unveiled Completing the human genome puzzle with the missing piece A brief history of the Human Genome Project The Human Genome Project is one of the most important biomedical research projects of the 20th Century. It aimed to sequence all the human genome and DNA, and by 2003, the Human Genome Project had generated the first sequence of the human genome, accounting for over 90% of the information. By 2022, the sequence was finalised, but it only contained information about the female genome, with two X chromosomes. The Y chromosome was missing as it contains many repetitive sequences that are not transcribed to messenger RNA, making it difficult to assemble it fully. However, due to advancements in sequencing technology, a new study in 2023 published in Nature aimed to, for the first time, assemble complete sequences of multiple human Y chromosomes from 43 unrelated males around the world. Sanger DNA sequencing method DNA sequencing is a method used to determine the exact order of DNA bases (adenine, thymine, cytosine, and guanine) within a DNA molecule. Due to the aim of the Human Genome Project (to sequence all of the DNA), many methods were experimented with, leading to scientists ultimately refining, improving and using the Sanger DNA sequencing method. This method is the most accurate method for sequencing small fragments of DNA. It involves using patient DNA in a polymerase chain reaction (PCR). A mix of normal bases and chain-terminating bases is added. Chain-terminating bases stop DNA growth, creating fragments of different lengths, each ending in a terminator. The DNA fragments are separated by size through capillary gel electrophoresis. Each terminator base (adenine, thymine, cytosine, and guanine) has a different fluorescent tag. The fragments appear in order of length, and their fluorescent tags are recorded. This information is used to create a chromatograph, which is compared to a reference to identify variants, allowing DNA analysis. Analysis of the Y chromosome In 2023, a study published in Nature assembled complete sequences of multiple human Y chromosomes from 43 unrelated males around the world. The study discovered a high level of structural variation across the Y chromosomes, which was unexpected. The analysis showed a high level of diversity of the Y chromosome, and it is the beginning of the exploration of male genetic diversity. The study highlights that the information gained can be used in various fields of biomedicine, such as to gain more insight into the function and evolution of the human genome and to understand more about Y chromosome variants. This discovery can also lead to improved genetic testing accuracy and targeted treatments for personalised medicine. Written by Naoshin Haque Project Gallery

  • An introduction to epigenetics | Scientia News

    Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link An introduction to epigenetics Unveiling the dance between genes and the environment In recent times, a new area of genetics termed epigenetics has emerged. It seeks to uncover the relationship between our genes and environment. At the core of this novel field is the principle that gene expression can be altered without modifications to the DNA sequence itself. Epigenetic changes to DNA involve the addition of methyl or acetyl groups. Methyl groups decrease gene expression by making DNA more tightly bound around histones, forming heterochromatin, whereas acetyl groups do the opposite; they increase gene expression by loosening histone-bound DNA, forming euchromatin. The addition of these chemical groups to DNA is mediated by enzymes that act on signals our bodies receive from our environment such as diet, stressors, and exercise. Epigenetic mechanisms of gene regulation have gained notoriety in the scientific community as it is suggested that these changes can be passed down to future generations through germline cells. This means that our grandparents’ diets can influence whether we develop diabetes or not. This neo-Lamarckian concept of evolution challenges the current Darwinian understanding of evolutionary genetics where phenotypic traits are believed to emerge due to genetic mutations and natural selection. Understanding epigenetic modifications opens new doors for potential clinical therapies as by modifying harmful epigenetic changes, we may be able to treat various diseases. This field also highlights the importance of a healthy lifestyle, proper nutrition, and avoiding stressors like smoking and radiation, not only for us but for future generations as well. A noteworthy study on exercise A study conducted by Sailani et al.1 delves into the effects of lifelong exercise on DNA methylation patterns in genes related to metabolism, skeletal muscle properties, and myogenesis. They used two groups with different levels of physical activity. Individuals from one group reported being physically active by playing various sports and engaging in other forms of activity such as cycling, hiking, running, and swimming; the other group were reported to be physically inactive but healthy. The active group exhibited promoter hypomethylation in genes related to insulin sensitivity, muscle repair and development, and mitochondrial respiratory complexes. Compared to the inactive individuals, a significant increase in hypomethylation was seen in 714 promoters in the active group. Bearing in mind that the inactive group were healthy despite being inactive, this significant difference in methylation pattern is remarkable to see and hits home the gravity of epigenetic influence in our lives. As a result of hypomethylation, these genes would have a higher rate of expression in the active individuals. An example of one such gene is GYG2 which codes for the glycogenin 2 enzyme involved in glycogen synthesis. With enhanced glycogen synthesis we can expect to see improved physical performance and recovery in the active individuals. Along with improved skeletal muscle properties and metabolic profiles, we can assume that the active group will have a higher life expectancy and quality of life than the inactive group. As we can see, epigenetics holds a lot of promise for the future of genetic research. By understanding the extent to which epigenetic modifications affect our lives, we can take measures to encourage positive changes to our genomes for greater health, happiness, and vitality. Written by Malintha Hewa Batage Related articles: How epigenetic modifications give the queen bee her crown / Complex disease I- schizophrenia Project Gallery

  • Motivating the Mind | Scientia News

    Facebook X (Twitter) WhatsApp LinkedIn Pinterest Copy link Motivating the Mind MIT scientists found reward sensitivity varies by socioeconomic status Behaviour is believed by many, including the famous psychologist B.F. Skinner, to be reinforced by rewards and the degree to which an individual is motivated by rewards is called reward sensitivity. Another common view is that behaviour is influenced by the environment, nowadays including socioeconomic status (SES). People with low SES encounter fewer rewards in their environment, which could affect their behaviour toward pursuing rewards due to their scarcity- Farah 2017. Thus, a study by Decker (2024) investigates the effect of low SES on reward sensitivity in adolescents through a gambling task, using fMRI technology to measure response times, choices and activity in the striatum – the reward centre of the brain. The researchers hypothesised that response times to immediate rewards, average reward rates and striatal activity would differ for participants from high compared to low SES backgrounds. See Figure 1 . The study involved 114 adolescents whose SES was measured using parental education and income. The participants partook in a gambling task involving guessing if numbers were higher or lower than 5, the outcomes of which were pre-determined to create blocks with reward abundance and reward scarcity. Low and high SES background teenagers gave faster responses and switched guesses when the rewards were given more often. Also, immediate rewards made the participants repeat prior choices and slowed response times. In line with the hypothesis, fewer adolescents with lower SES slowed down after rare rewards. Moreover, it was found that lower SES is linked with fewer differences between reward and loss activation in the striatum, indicating experience-based plasticity in the brain. See Figure 2 . Therefore, the research by Decker (2024) has numerous implications for the real world. As adolescents with lower SES displayed reduced behavioural and neural responses to rewards and, according to behaviourism, rewards are essential to learning, attention and motivation, it can be assumed that SES plays a role in the inequality in many cognitive abilities. This critically impacts the understanding of socioeconomic differences in academic achievement, decision-making and emotional well-being, especially if we consider that differences in SES contribute to prejudice based on ingroups and outgroups. Interventions to enhance motivation and engagement with rewarding activities could help buffer against the detrimental impacts of low SES environments on cognitive and mental health outcomes. Overall, this research highlights the need to address systemic inequities that limit exposure to enriching experiences and opportunities during formative developmental periods. Written by Aleksandra Lib REFERENCES Decker, A. L., Meisler, S. L., Hubbard, N. A., Bauer, C. C., Leonard, J., Grotzinger, H., Giebler M. A., Torres Y C., Imhof A., Romeo R. & Gabrieli, J. D. (2024). Striatal and Behavioral Responses to Reward Vary by Socioeconomic Status in Adolescents. The Journal of Neuroscience: the Official Journal of the Society for Neuroscience, 44(11). Farah, M. J. (2017). The neuroscience of socioeconomic status: Correlates, causes, and consequences. Neuron, 96(1), 56-71. Project Gallery

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