💥Join UPSC 2027,2028 Mentorship (August Batch) + XFactor Notes & Microthemes PDF
Talk to Mentor

Civilsdaily

Login

Subject: Science and Technology

  • PCR Test for Diagnosis of the COVID-19

     

    The diagnosis of COVID-19 can be done with the Polymerase Chain Reaction (PCR) Test which is explained as under:

    The PCR Test

    • It uses a technique that creates copies of a segment of DNA. ‘Polymerase’ refers to the enzymes that make the copies of DNA.
    • Kary Mullis, the American biochemist who invented the PCR technique, was awarded the Nobel Prize for Chemistry in 1993.
    • The ‘chain reaction’ is how the DNA fragments are copied, exponentially — one is copied into two, the two are copied into four, and so on.
    • However, SARS-COV-2 is a virus made of RNA, which needs to be converted into DNA. For this, the technique includes a process called reverse transcription.
    • A ‘reverse transcriptase’ enzyme converts the RNA into DNA. Copies of the DNA are then made and amplified.
    • A fluorescent DNA binding dye called the “probe” shows the presence of the virus. The test also distinguishes SARS-COV-2 from other viruses.

    Various Stages:

    1) Collection and transport

    • Testing centre takes swabs from nasal cavities and back of the throat (pharynx), and puts samples in a “virus transport medium”, which contains balanced salts and albumin to prevent the virus from disintegrating.
    • Sample is then transported in cold storage to the testing lab.

    2) Extraction of viral RNA

    • Coronaviruses have large single-stranded RNA genomes.
    • Testing lab extracts the RNA from the samples, using commercially available kits.

    3) Putting THE RNA in THE PCR mix

    • Extracted RNA is added to a polymerase chain reaction (PCR) mix.
    • This includes the ‘master mix’, which contains a ‘reverse transcriptase’ enzyme that converts the RNA into DNA.
    • Master Mix contains Taq polymerase, the enzyme that creates copies of the DNA, nucleotides, as well as other elements such as magnesium — an ion of which is needed to amplify the DNA.
    • The PCR mix also contains ‘reagents’ such as ‘primers’ and ‘probes’.
    • Primers are particular strands of DNA that are designed to bind with the DNA that is to be copied; probes are used to detect the specific sequence in the DNA sample.
    • Finally, the PCR mix consists of a “housekeeping” gene — a normal human gene (RNAse P) that is used to ensure that samples were properly collected, and RNA extracted.

    4) Amplification of the viral DNA

    • Sample, in its PCR mix, is put into tubes or plates, which are then put in a thermal cycler machine that is used to conduct the PCR process.
    • First, the RNA is converted into DNA. Then the process of copying the genes starts.
    • The thermal cycler heats and cools the mixture with the sample, alternating between three temperatures — for melting the DNA to separate the two strands.
    • The thermal cycler runs 30-40 such cycles in order to amplify the DNA to check for the virus.

    5) Testing against controls

    • Amplified DNA is tested against a positive control, which usually consists of genes of the virus cloned into plasmid, and a negative control, which is a ‘known’ sample that has tested negative for the virus earlier.
    • RNase P should show amplification, positive control should be positive, negative control should be negative, and then whatever result you get for the specimen, is the correct result.
    • In order for a test to be valid before the result is released, certain ‘validity criteria’ have to be met.
    • If the housekeeping gene (RNase P) is positive, positive control is positive, negative control is negative, and the sample does not show any PCR positive result, the sample is declared negative.
    • If the PCR result is positive, the patient has COVID-19.

  • Epidemics that have hit India since 1900

    India has witnessed widespread illnesses and virus outbreaks in parts of the country, including the SARS outbreak between 2002 and 2004. However, statistics show that they were nowhere as widespread as the COVID-19 that has now reached almost every part of the country and almost every country in the world.

    What is an Epidemic?

    • The WHO defines epidemics as “the occurrence in a community or region of cases of an illness, specific health-related behaviour, or other health-related events clearly in excess of normal expectancy.
    • The community or region and the period in which the cases occur are specified precisely.
    • The number of cases indicating the presence of an epidemic varies according to the agent, size, and type of population exposed, previous experience or lack of exposure to the disease, and time and place of occurrence.
    • Epidemics are characterized by the rapid spread of the specific disease across a large number of people within a short period of time.

    Epidemics in India

    • Many Indian citizens born at the start of the 21st century have not fully witnessed or experienced circumstances surrounding the mass outbreak of epidemics.
    • This is not to say however, that as a nation, India is completely unfamiliar with dealing with epidemics and public health crises, some with exceptional success such as:

    1915-1926⁠ — Encephalitis lethargica

    • Encephalitis lethargica, also known as ‘lethargic encephalitis’ was a type of epidemic encephalitis that spread around the world between 1915 and 1926.
    • The disease was characterized by increasing languor, apathy, drowsiness and lethargy and by 1919, had spread across Europe, the US, Canada, Central America and India.
    • It was also called encephalitis A and Economo encephalitis or disease.
    • Approximately 1.5 million people are believed to have died due to this disease.

    1918-1920 — Spanish flu

    • This epidemic was a viral infectious disease caused due to a deadly strain of avian influenza.
    • The spread of this virus was largely due to World War I which caused mass mobilization of troops whose travels helped spread this infectious disease.
    • In India, approximately 10-20 million people died due to the Spanish flu that was brought to the region a century ago, by Indian soldiers who were part of the war.

    1961–1975 — Cholera pandemic

    • Vibrio cholerae, one type of bacterium, has caused seven cholera pandemics since 1817.
    • In 1961, the El Tor strain of the Vibrio cholerae bacterium caused the seventh cholera pandemic when it was identified as having emerged in Makassar, Indonesia.
    • In a span of less than five years, the virus spread to other parts of Southeast Asia and South Asia, having reached Bangladesh in 1963 and India in 1964.

    1974 — Smallpox epidemic

    • According to WHO, smallpox was officially eradicated in 1980. The infectious disease was caused by either of the two virus variants Variola major and Variola minor.
    • Although the origins of the disease are unknown, it appears to have existed in the 3rd century BCE.
    • This disease has a history of occurring in outbreaks around the world and it is not clear when it was first observed in India. India was free of smallpox by March 1977.

    1994 — Plague in Surat

    • In September 1994, pneumonic plague hit Surat, causing people to flee the city in large numbers. Rumours and misinformation led to people hoarding essential supplies and widespread panic.
    • This mass migration contributed to the spread of the disease to other parts of the country. Within weeks, reports emerged of at least 1,000 cases of patients afflicted with the disease and 50 deaths.

    2002-2004 — SARS

    • SARS was the first severe and readily transmissible new disease to have emerged in the 21st century.
    • In April 2003, India recorded its first case of SARS, severe acute respiratory syndrome, that was traced to Foshan, China.
    • Similar to COVID-19, the causative agent of SARS was a type of coronavirus, named SARS CoV that was known for its frequent mutations and spread through close person-to-person contact and through coughing and sneezing by infected people.

    2014-2015 — Swine flu outbreak

    • In the last few months of 2014, reports emerged of the outbreak of the H1N1 virus, one type of influenza virus, with states like Gujarat, Rajasthan, Delhi, Maharashtra and Telangana being the worst affected.
    • By March 2015, according to India’s Health Ministry, approximately 33,000 cases had been reported across the country and 2,000 people had died.

    2018 — Nipah virus outbreak

    • In May 2018, a viral infection attributed to fruit bats was traced in the state of Kerala, caused by the Nipah virus that had caused illness and deaths.
    • The spread of the outbreak remained largely within the state of Kerala, due to efforts by the local government and various community leaders who worked in collaboration to prevent its spread even inside the state.
    • Between May and June 2018, at least 17 people died of Nipah virus and by June, the outbreak was declared to have been completely contained.

  • What is Herd Immunity?

    As Europe was declared the epicentre of the novel coronavirus outbreak last week, Britain announced a different strategy to tackle the situation. Officials said that Britain would contain the spread of the virus but would not suppress it completely to build up a degree of ‘herd immunity’.

    Herd Immunity

    • Herd immunity is when a large number of people are vaccinated against a disease, lowering the chances of others being infected by it.
    • When a sufficient percentage of a population is vaccinated, it slows the spread of disease.
    • It is also referred to as community immunity or herd protection.
    • The decline of disease incidence is greater than the proportion of individuals immunized because vaccination reduces the spread of an infectious agent by reducing the amount and/or duration of pathogen shedding by vaccines, retarding transmission.
    • The approach requires those exposed to the virus to build natural immunity and stop the human-to-human transmission. This will subsequently halt its spread.

    Can it work?

    • Globally, this strategy has been criticized.
    • COVID-19 is a new virus to which no one has immunity. More people are susceptible to infection.
    • The goal seems to have been delaying urgent action to allow an epidemic to infect large numbers of people.
    • To combat COVID-19, there is an urgent need to implement social distancing and closure policies.

  • Role of Glucose in Regulating Liver Functions

    A study by researchers from the Tata Institute of Fundamental Research, Mumbai (TIFR) has revealed that glucose in the body controls the function of SIRT1 enzymes directly.

    What is SIRT1?

    • SIRT1 is an enzyme that deacetylates (removal of acetyl) proteins which contribute to cellular regulation.
    • A shortage or absence of the control by glucose may lead to a diabetic-like state, while excess feeding and sustained low levels of SIRT1 can lead to obesity and enhanced ageing.
    • This information is expected to tackle lifestyle disorders and ageing-related diseases.

    How do they function?

    • In normal healthy individuals, SIRT1 protein levels are known to increase during fasting and decrease during the feed, which is essential to maintain a balance between glucose and fat metabolism.
    • The glucose controls the functions of a protein SIRT1 which in turn maintains everyday feed-fast cycles and is also associated with longevity.
    • The feed-fast cycle is a basic pattern and the metabolism-related to this is largely taken care of by the liver.
    • Thus, the study shows that both over-activation and under-activation of SIRT1 can lead to diseases.
    • Glucose puts a check on the activity of SIRT1 in the fed state. In the absence of this check, SIRT1 activity increases and results in hyperglycemia in a fasted state, mimicking diabetic state.
    • The constant feeding or high-calorie intake that leads to a sustained reduction in the levels of SIRT1 by glucose which is associated with ageing and obesity.

  • Social Distancing and Flattening the Curve

    The last two days, a number of states in India have enforced measures aimed at reducing public gatherings. This is called “social distancing”.

    How does social distancing work?

    • To stem the speed of the coronavirus spread so that healthcare systems can handle the influx, experts are advising people to avoid mass gatherings.
    • Offices, schools, concerts, conferences, sports events, weddings, and the like have been shut or cancelled around the world, including in a number of Indian states.
    • An advisory by the US Centers for Disease Control recommends social distancing measures such as: reducing the frequency of large gatherings and limiting the number of attendees; limiting inter-school interactions; and considering distance or e-learning in some settings.

    What is the objective of such restrictions?

    • Compared to deadlier diseases such as bird flu, or H5N1, coronavirus is not as fatal —which ironically also makes it more difficult to contain.
    • With milder symptoms, the infected are more likely to be active and still spreading the virus.
    • For example, more than half the cases aboard a cruise ship that has docked in California did not exhibit any symptoms.
    • In a briefing on March 11, WHO officials said, “Action must be taken to prevent transmission at the community level to reduce the epidemic to manageable clusters.”
    • The main question for governments is to reduce the impact of the virus by flattening the trajectory of cases from a sharp bell curve to an elongated speed-bump-like curve.
    • This is being called “flattening the curve”. How does ‘flattening the curve’ help?
    • Limiting community transmission is the best way to flatten the curve.

    What was the curve like in China?

    • The numbers show that the virus spread within Hubei exponentially but plateaued in other provinces.
    • Some say it’s because many of these countries learnt from the 2003 SARS epidemic.
    • Just as Chinese provinces outside of Hubei effectively stemmed the spread in February, three other countries —South Korea, Italy, and Iran — were not able to flatten the curve.

    Flattening The Curve

    • In epidemiology, the idea of slowing a virus’ spread so that fewer people need to seek treatment at any given time is known as “flattening the curve.”
    • It explains why so many countries are implementing “social distancing” guidelines — including a “lockdown” order that affects 1.3 billion people in India, even though COVID-19 outbreaks in various places might not yet seem severe.

    What is the curve?

    • The “curve” researchers are talking about refers to the projected number of people who will contract COVID-19 over a period of time.
    • To be clear, this is not a hard prediction of how many people will definitely be infected, but a theoretical number that’s used to model the virus’ spread. Here’s what one looks like:

    • The curve takes on different shapes, depending on the virus’s infection rate.
    • It could be a steep curve, in which the virus spreads exponentially (that is, case counts keep doubling at a consistent rate), and the total number of cases skyrockets to its peak within a few weeks.
    • Infection curves with a steep rise also have a steep fall; after the virus infects pretty much everyone who can be infected, case numbers begin to drop exponentially, too.
    • The faster the infection curve rises, the quicker the local health care system gets overloaded beyond its capacity to treat people.
    • As we’re seeing in Maharashtra or Ahmedabad, more and more new patients may be forced to go without ICU beds, and more and more hospitals may run out of the basic supplies they need to respond to the outbreak.
    • A flatter curve, on the other hand, assumes the same number of people ultimately get infected, but over a longer period of time.
    • A slower infection rate means a less stressed health care system, fewer hospital visits on any given day and fewer sick people being turned away.

  • What is a Pandemic and various other terms?

    What is the news: The World Health Organization (WHO) has declared the COVID-19 outbreak a pandemic.

    What is a pandemic?

    • Simply put, a pandemic is a measure of the spread of a disease.
    • When a new disease spreads over a vast geographical area covering several countries and continents, and most people do not have immunity against it, the outbreak is termed a pandemic.
    • It implies a higher level of concern than an epidemic, which the US Centers for Disease and Control Prevention (CDC) define as the spread of a disease in a localised area or country.
    • There is no fixed number of cases or deaths that determine when an outbreak becomes a pandemic.
    • The Ebola virus, which killed thousands in West Africa, is an epidemic as it is yet to mark its presence on other continents.
    • Other outbreaks caused by coronaviruses such as MERS (2012) and SARS (2002), which spread to 27 and 26 countries respectively, were not labelled pandemics because they were eventually contained.

    Which outbreaks have been declared pandemics in the past?

    • A major example is the Spanish flu outbreak of 1918, which killed between 20-50 million.
    • Cholera pandemics have been declared multiple times between 1817 and 1975.
    • In 1968, a pandemic was declared for H3N2 that caused about a million deaths.
    • The last pandemic declared by the WHO was in 2009, for H1N1.

    Does the declaration change the approach to the disease?

    • Describing the situation as pandemic does not change WHO’s assessment of the risk posed by the virus. However, the categorization as a pandemic can lead to more government attention.
    • The categorization by WHO indicates the risk of disease for countries to take preventive measures.
    • It will help improve funding by international organisations to combat coronavirus.

    Difference Between Endemic, Epidemic, Outbreak and Pandemic:

    • AN EPIDEMIC is a disease that affects a large number of people within a community, population, or region.
    • A PANDEMIC is an epidemic that’s spread over multiple countries or continents.
    • ENDEMIC is something that belongs to a particular people or country.
    • AN OUTBREAK is a greater-than-anticipated increase in the number of endemic cases. It can also be a single case in a new area. If it’s not quickly controlled, an outbreak can become an epidemic.

    Epidemic vs. Pandemic

    • A simple way to know the difference between an epidemic and a pandemic is to remember the “P” in the pandemic, which means a pandemic has a passport. A pandemic is an epidemic that travels.

    Epidemic vs. Endemic

    • An epidemic is actively spreading; new cases of the disease substantially exceed what is expected.
    • More broadly, it’s used to describe any problem that’s out of control, such as “the opioid epidemic.”
    • An epidemic is often localized to a region, but the number of those infected in that region is significantly higher than normal.
    • For example, when COVID-19 was limited to Wuhan, China, it was an epidemic. The geographical spread turned it into a pandemic.
    • Endemics, on the other hand, are a constant presence in a specific location.
    • Malaria is endemic to parts of Africa. Ice is endemic to Antarctica.

    Endemic vs. Outbreak

    • Going one step farther, an endemic can lead to an outbreak, and an outbreak can happen anywhere.
    • Last summer’s dengue fever outbreak in Hawaii is as an example. Dengue fever is endemic to certain regions of Africa, Central and South America, and the Caribbean. Mosquitoes in these areas carry dengue fever and transmit it from person to person.
    • But in 2019 there was an outbreak of dengue fever in Hawaii, where the disease is not endemic. It’s believed an infected person visited the Big Island and was bitten by mosquitoes there.
    • The insects then transferred the disease to other individuals they bit, which created an outbreak.

    You can see why it’s so easy to confuse these terms. They’re all related to one another and there’s a natural ebb and flow between them as treatments become available and measures for control are put in place — or as flare-ups occur and disease begins to spread.

  • Genome sequencing of Coronavirus

    Scientists across the world are trying to develop a line of treatment and a possible vaccine for COVID-19. However, with the most optimistic timelines we don’t see a line of treatment or vaccine arriving before next year.

    Genome sequencing of Coronavirus

    • A global effort is on to collect and analyse the genetic composition of the new virus, which would be key to developing a cure and a vaccine.
    • Genome sequence is the unique code of genetic material of any organism, and determines the characteristic of any organism.
    • Whole genome sequencing is the process of determining the complete DNA sequence of an organism’s genome at a single time.
    • The gene composition of novel coronavirus, for instance, is different from that of the influenza virus. Every organism has a unique genome sequence.
    • Laboratories in various countries have been isolating and sharing the genome sequences of the virus on an international platform.

    Why are so many genome sequences being isolated?

    • When viruses multiply, or reproduce, there is a copying mechanism that transfers the gene information to the next generation.
    • However, no copying mechanism is perfect. When the virus multiplies, there will be small changes, which are called mutations.
    • These mutations accumulate over time, and after prolonged periods, are responsible for evolution into new organisms.
    • Within a single reproduction, the changes are extremely minor. More than 95 per cent of the gene structure remains the same.

    How it helps scientists?

    • However, the small changes that occur are crucial to understanding the nature and behaviour of the organism.
    • In this case, for example, the small changes could provide scientists with information about the origin, transmission, and impact of the virus on the patient.
    • It could also hold clues to the differing effects the virus could have on patients with different health parameters.

    How many genome sequences are required?

    • India has far fewer positive cases compared to China, South Korea, Iran, Italy, or even the US.
    • Patients who have been infected with the virus in similar conditions are unlikely to show any significant changes in the genome sequences.
    • Patients with existing medical conditions could be other candidates from where genome sequences of this virus could be isolated.
    • This could help scientists to look for clues to possible impact of virus amidst those existing medical conditions.

    Currently, what is the most effective medication?

    • As of now, there is none such. Right now, drugs are being repurposed, meaning old drugs for similar diseases are being checked for their efficacy against COVID-19.
    • These drugs, if they work, will require clinical trials, and then can be made widely available for people.
    • In most cases, symptomatic treatment for fever, body ache, and cough will be sufficient. More severe cases will require oxygen and respiratory support.

  • [pib] ARI-516 Grape Variety

     

    Pune’s Agharkar Research Institute (ARI), an autonomous institute of the DST has developed a hybrid variety of grapes which is resistant to fungal diseases, high yielding and has excellent juice quality.

    ARI-516

    • The hybrid variety ARI-516 has been developed by interbreeding of two species from the same genus — Catawba variety of Vitis labrusca and Beauty seedless variety of Vitis vinifera.
    • It is a result of collaboration between Maharashtra Association for the Cultivation of Science (MACS) and ARCI and can benefit farmers, the processing industry and consumers.
    • This variety of grapes is resistant to fungal diseases, high yielding and has excellent juice quality.
    • The fungal resistance of ARI-516 has been derived from Catawba, which is an American grape variety.

    Commercial benefits

    • It is also suitable for preparation of juice, raisin, jam and red wine and farmers are enthusiastically adopting the variety.
    • It has superior quality fruits and higher yield per unit area.
    • An early ripening hybrid, it matures in 110 – 120 days after pruning.
    • Being moderately resistant to a majority of fungal diseases, its cost of production is lower.

    Back2Basics

    Grape production in India

    • India ranks twelfth in the world in terms of grape production.
    • About 78% of grape production in India is utilized for consumption, 17-20 % for raisin production, 1.5 % for wine and 0.5 % for juice.
    • Maharashtra leads in the production of grapes in India with a share of 81.22 %. A negligible share of grapes is used for juice production.
    • A majority of farmers in Maharashtra cultivate ‘Thompson seedless’ and its clones for table purpose or raisin making.

  • How plants dissipate excess sunlight as heat?

    Photosynthesis is a life-sustaining process by which plants store solar energy as sugar molecules. However if sunlight is in excess it can lead to leaves being dehydrated and damaged.

    What is Photosynthesis?

    • Photosynthesis is the process used by plants, algae and certain bacteria to harness energy from sunlight and turn it into chemical energy.
    • There are two types of photosynthetic processes: oxygenic photosynthesis and anoxygenic photosynthesis.
    • The general principles of anoxygenic and oxygenic photosynthesis are very similar, but oxygenic photosynthesis is the most common and is seen in plants, algae and cyanobacteria.
    • During oxygenic photosynthesis, light energy transfers electrons from water (H2O) to carbon dioxide (CO2), to produce carbohydrates.
    • Ultimately, oxygen is produced along with carbohydrates. Oxygenic photosynthesis is written as follows:

    6CO2 + 12H2O + Light Energy → C6H12O6 + 6O2 + 6H2O

    Here, six molecules of carbon dioxide (CO2) combine with 12 molecules of water (H2O) using light energy. The end result is the formation of a single carbohydrate molecule (C6H12O6, or glucose) along with six molecules each of breathable oxygen and water.

    How do plants dissipate heat?

    • To prevent such damage, plants dissipate extra light as heat.
    • While this was known there has been a debate over the past several decades over how plants actually do so.
    • Now for the first time researchers have directly observed one of the possible mechanisms through which plants dissipate extra sunlight.
    • The new research has been able to determine–by using a highly sensitive type of spectroscopy–that excess energy is transferred from the pigment chlorophyll, which gives leaves their green colour, to other pigments called carotenoids.
    • The carotenoids then release the energy as heat. After the carotenoids accept excess energy, most of it is released as heat, thus preventing damage to the cells.

    Why does plant dissipate light?

    • During photosynthesis, light-harvesting complexes play two seemingly contradictory roles.
    • They absorb energy to drive water-splitting and photosynthesis, but at the same time, when there’s too much energy, they have to also be able to get rid of it.
    • Plants quickly adapt to changes in sunlight intensity. Even in very sunny conditions, only 30 per cent available sunlight is converted into sugar, and the rest is released as heat.
    • The excess energy, if not released, leads to the creation of free radicals that can damage proteins and other important cellular molecules.

    Significance of the research

    • So far, it had been difficult to observe the heat dissipation phenomenon, given that it occurs on a very fast time scale, in femtoseconds or quadrillionths of a second.
    • Using the new technique, researchers could observe that chlorophylls absorb red light and carotenoids absorb blue and green light, thus being able to monitor energy transfer.

  • N95 Mask

    In a new mandate to curb unnecessary demand, the Maharashtra Food and Drug Administration said that chemists cannot sell N95 masks without a doctor’s prescription. The FDA also warned that serious action would be taken against those who are found selling masks at high prices or hoarding them.

    Why such a move?

    • Personal Protective Equipment (PPE) kits and N95 masks are being sold at very high prices in medical shops. The State has received many complaints about the same.
    • It has also been found that many are making bulk purchases and hording PPE kits and N95 masks.
    • Since the COVID-19 outbreak in China, shortage of PPE gear and masks has been reported from across the world.
    • While the Indian government has currently banned exports of N95 masks, the manufacturers are focussed on making other surgical marks to get good returns from exports.

    N95 mask

    • A disposable N95 mask (respirator) is a safety device that covers the nose and mouth and helps protect the wearer from breathing in some hazardous substances.
    • An N95 respirator is designed to achieve a very close facial fit and very efficient filtration of airborne particles.
    • The ‘N95’ designation means that when subjected to careful testing, the respirator blocks at least 95 percent of very small (0.3 micron) test particles.
    • If properly fitted, the filtration capabilities of N95 respirators exceed those of face masks. However, even a properly fitted N95 respirator does not completely eliminate the risk of illness or death.