This newscard is an excerpt of the original article published in The Hindu.

Note: It appears to be too much biological. And suddenly out of our ease of understanding.

What is Ribo Nucleic Acid (RNA)?

• RNA is an important biological macromolecule that is present in all biological cells.
• It is principally involved in the synthesis of proteins, carrying the messenger instructions from DNA, which itself contains the genetic instructions required for the development and maintenance of life.
• In some viruses, RNA, rather than DNA, carries genetic information.
• The type of RNA dictates the function that this molecule will have within the cell.
• Aside from the coding region of messenger RNA (mRNA) molecules that will be translated into proteins, other cellular RNA elements are involved in different processes.

What are RNA Origami?

• RNA origami is the nanoscale folding of RNA, enabling the RNA to create particular shapes to organize these molecules.
• It is an attempt to generate complex human-made RNA-based devices.
• They are stable in cells, interact with other biomolecules, including other RNA and proteins, and enable unique applications, particularly in the context of gene regulation.

Why are they used?

So far there have been two approaches in RNA origami and both attempt to regulate the production of protein.

(1) To achieve precise control of protein production

• Self-inhibiting protein expression cassettes were made by installing a strong binding site for the expressed protein in its own gene.
• Afterwards, RNA origami decorated with the same protein-binding sites was expressed in large excess.
• In this way, the RNA origami serves as a protein-sponge that sequesters proteins in the cell and allows expression of the self-inhibited protein.
• This approach helped to regulate several proteins simultaneously and turn on enzymatic pathways for improved product yields.

(2) Using for gene editing

• The RNA origamis were integrated in the small RNAs that guide CRISPR-Cas9 enzyme to target specific sequences in the DNA genome.
• Its scaffolds were decorated with protein-binding sites capable of recruiting transcription factors.
• By targeting the RNA scaffolds to promoter regions, the transcription factors activated gene expression.
• Researchers have shown that the expression strength can be tuned by the orienting the scaffold and level of transcription factors recruited.
• These multi-enzyme pathways could be controlled for high-yield production of the anti-cancer drug violacein.

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A team of researchers at the IIT — Guwahati has developed an edible coating using marine alga that coated on vegetables and fruits, substantially extends their shelf-life.

Dunaliella tertiolecta: The Edible coating

• The team used a mix of an extract of a marine microalga called Dunaliella tertiolecta and polysaccharides to produce it.
• The microalga is known for its antioxidant properties and has various bioactive compounds such as carotenoids and proteins.
• It is also used to produce algal oil, a non-animal source of omega-3 fatty acid and is considered a good source of biofuel.
• After the oil is extracted, the residue is usually discarded.
• The researchers used extracts from this residue in formulating their film, in combination with chitosan, which is a carbohydrate.
• It also has antimicrobial and antifungal properties and can be made into an edible film.

Benefits of this Edible coating

• The films displayed superior antioxidant activity, thermal stability, mechanical strength, total phenolic content and water vapour barrier property.
• They also had excellent UV-Vis light-blocking properties.
• The researchers also tested the biosafety of these coatings.

Why is it viable?

• The new coatings can be mass-produced.
• They are very stable to light, heat, and temperature up to 40C, edible, and can be safely eaten as part of the product formulation and do not add unfavourable properties to it.
• They retain texture, colour, appearance, flavour and nutritional value.
• The material can be either directly coated on the vegetables and fruits or made into a vegetable storage pouch.
• In both cases, the shelf-life of the vegetables can be extended.
• It is a simple dip coating technique with no significant cost added to the post-harvest processing.

Economic significance of Edible coating

• According to the Indian Council of Agricultural Research, between 4.6 and 15.9 per cent of fruits and vegetables go waste post-harvest, partly due to poor storage conditions.
• In fact, post-harvest loss in certain produce items like potato, onion, and tomato could even be as high as 19%, which results in high prices for this highly consumed commodity.

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A team of scientists from Australia have found that babies at risk of the mysterious Sudden Infant Death Syndrome, or SIDS, generally have low levels of an enzyme called butyrylcholinesterase (BChE) in their blood.

What is SIDS?

• Sudden Infant Death Syndrome refers to the sudden and unexpected death of an otherwise healthy infant under the age of one, generally while they are sleeping.
• Most SIDS-related deaths occur in infants between the age of 1-4 months.
• According to the NHS website, parents can reduce the risk of SIDS by not smoking while pregnant or after the baby is born and ensuring that the baby is placed on their back when they sleep.
• Some health experts have said that it is associated with issues in the part of an infant’s brain that controls breathing and waking up.

Prevalence of SIDS

• SIDS, also known as ‘cot death’, has claimed the lives of thousands of children across the West.
• US estimates that about 3,400 babies die suddenly and unexpectedly every year.
• Meanwhile, the United Kingdom reports about 200 such deaths annually.

What does the new study say?

• The study assessed whether there was something inherently different in babies that succumbed to SIDS.
• The researchers compared dried blood samples from 655 healthy babies, 26 babies who died due to SIDS and 41 babies who died of other causes.
• The team found that around nine of ten babies who died from SIDS had lower levels of BChE enzymes than the babies in the other two groups.

What is the BChE (Butyrylcholinesterase) enzyme responsible for?

• These enzymes are responsible for sending out signals that make a baby wake up, turn her head, or gasp for breath.
• It is part of the autonomic system, and controls function like blood pressure and breathing.

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Recent work by researchers at the National Centre of Biological Sciences, Bengaluru, has thrown light on what stimulates the synapses (connection of nerve cells) to form.

What are Synapses?

• Neurons, or nerve cells, in the brain connect by means of junctions known as synapses through which they transmit signals.
• There are two types of synapses – chemical and electrical:

(1) Chemical Synapse

• In this, there is a space of about 20 nanometres between two neurons, and the way they communicate is this: One neuron converts electrical signal into chemical signals.
• This chemical is released into the synaptic space and the receiving neuron converts the chemical signal back into an electrical signal.

(2) Electrical synapse

• In these synapses, the two neurons have a physical connection and the conversion of electrical to chemical need not occur, and they communicate directly.
• Electrical synapses are like a physical wire, communication is faster but they are also fewer in number.

Observing these synapses

• Researchers from TIFR-National Centre of Biological Sciences, Bengaluru, have chosen Zebrafish as a model organism to study this process.
• Zebrafish are transparent and neuron development in larval zebrafish can be observed from day to day by injecting a dye or by engineering the fish to express fluorescent proteins.
• It was observed that electrical synapses are formed before chemical synapses, they are like a blueprint in which neurons make a handshake. This results in the making of chemical synapses.
• Research on organisms such as leeches showed that if you remove electrical synapses, the chemical synapses do not form.
• However, the mechanism of how it happens in higher organisms such as vertebrates was not known.

What induces these synapses?

• The group observed that knocking out a particular protein known as the gap junction delta 2b (gjd2b) in the cerebellum of zebrafish affected levels of the enzyme CaMKII.
• Levels of CaMKII were seen to increase in the Purkinje neurons in the cerebellum.
• These neurons and the cerebellum itself control coordination of movements in the organism.

Why study this?

• In humans for example, excess abuse of alcohol leads to damage of these cells, which results in lack of coordination in movement.
• The cerebellum shows an evolutionary continuity in all vertebrates, so, too, the Purkinje neurons.
• Even though fish and humans diverged from a common ancestor about 500 million years ago, the cerebellum has been evolutionarily conserved.
• While zebrafish have about 300-400 Purkinje neurons, humans have thousands of these.

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The Indian SARS-CoV-2 Consortium on Genomics (INSACOG) has sequenced about 1,00,000 samples.

What is INSACOG?

• INSACOG is a consortium of 10 labs and 18 satellite labs across India tasked with scanning COVID samples from patients and finding the variants that has led to spike in transmission.
• The institutes involved include the laboratories of the Department of Biotechnology, Council of Scientific and Industrial Research, Indian Council of Medical Research, and the Health Ministry.
• Its work began in January 2020, by sequencing all samples with a history of travel from the U.K. and a proportion of positive samples in the community.

Tasks of INSACOG

• The NCDC is tasked with coordinating collections of samples from the States as well as correlating disease with certain mutations.
• It is mainly involved in genomic sequencing which is done by isolating the genetic material of the coronavirus samples.
• It is also tasked with tracking certain combinations of mutations that become more widespread in India.

What has it found so far?

• The INSACOG sequenced about 1,00,000 samples as of early December 2021 when this data was last made publicly available.
• The bulk of its effort has been focussed on identifying international ‘variants of concern’ (VoC) that are marked out by the WHO as being particularly infectious or pathogenic.
• International travellers who arrive in India and test positive are the ones whose samples usually get sent to INSACOG for determining the genomic variant.

Why is genome sequencing useful?

• Understanding mutations: The purpose of genome sequencing is to understand the role of certain mutations in increasing the virus’s infectivity.
• Immune response: Some mutations have also been linked to immune escape, or the virus’s ability to evade antibodies, and this has consequences for vaccines.
• Effectiveness of vaccines: Labs across the world, including many in India, have been studying if the vaccines developed so far are effective against such mutant strains of the virus.
• Evolution of viruses: Studies such as this have shown that Omicron, for instance, has evolved to evade antibodies much better than the Alpha or Delta variant. This prompted the push towards booster doses.

How is it done?

• Genomic sequencing is done by isolating the genetic material (RNA) of the coronavirus samples.
• RNA consists of millions of nucleotide bases and genomic sequencing is about identifying and comparing the sequence in a given sample to a reference sample.
• Changes in the sequence are clues to mutations that show that the virus may have undergone distinct changes at some key locations.
• There are several approaches to genome sequencing — whole genome sequencing, next-generation sequencing — that have different advantages.
• It has now evolved to a stage where large sequencers can process even thousands of samples simultaneously.

Various challenges that INSACOG faces

• Geographical variations: Given that COVID-19 is spreading, mutating and showing geographical variations, the original aim of the group was to sequence at least 5% of COVID-19 samples.
• Shortage of funds: But only 1% has been achieved yet, primarily due to a shortage of funds, insufficient reagents and tools necessary to rapidly scale up.
• Red-tapism: The INSACOG, in spite of being peopled by expert scientists, is ultimately within the Central government’s communication structure.
• Infrastructure lacunae: Not all INSACOG labs have the same quality of equipment and manpower and therefore a surge or spike in some cities can mean difficulties in processing.

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To meet the demand of oxygen supply in the country during the peak of pandemic, the Defence Research and Development Organisation (DRDO) had chartered the Air India to import ‘Zeolite’ from different countries.

What are Zeolites?

• Zeolites are highly porous, 3-dimensional meshes of silica and alumina.
• In nature, they occur where volcanic outflows have met water.
• Synthetic zeolites have proven to be a big and low-cost boon.

Uses in Oxygen Concentrator

• One biomedical device that has entered our lexicon during the pandemic is the oxygen concentrator.
• This device has brought down the scale of oxygen purification from industrial-size plants to the volumes needed for a single person.
• At the heart of this technology are synthetic frameworks of silica and alumina with nanometer-sized pores that are rigid and inflexible.
• Beads of one such material, zeolite 13X, about a millimeter in diameter, are packed into two cylindrical columns in an oxygen concentrator.

How does it work?

• Zeolite performs the chemistry of separating oxygen from nitrogen in air.
• Being highly porous, zeolite beads have a surface area of about 500 square meters per gram.
• At high pressures in the column, nitrogen is in a tight embrace, chemically speaking, with the zeolite.
• Interaction between the negatively charged zeolite and the asymmetric nucleus (quadrupole moment) of nitrogen causes it to be preferentially adsorbed on the surface of the zeolite.
• Oxygen remains free, and is thus enriched.
• Once nitrogen is captured, what flows out from the column is 90%-plus oxygen.
• After this, lowering the pressure in the column releases the nitrogen, which is flushed out, and the cycle is repeated with fresh air.

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The U.S. Nuclear Regulatory Commission (NRC) decisively upheld the Linear No-Threshold (LNT) model to prescribe radiation safety standards, ending the protracted controversy on the topic.

What is the LNT Model?

• The LNT is a dose-response model used in radiation protection to estimate stochastic health effects such as radiation-induced cancer, genetic mutations etc. on the human body due to exposure to ionizing radiation.
• The LNT model states that biological effects such as cancer and hereditary effects due to exposure to ionising radiation increase as a linear function of dose, without threshold.
• It provides a sound regulatory basis for minimizing the risk of unnecessary radiation exposure to both members of the public and radiation workers.

Why in news?

• LNT model continues to provide a sound basis for a conservative radiation protection regulatory framework that protects both the public and occupational workers.
• The model helps the agencies to regulate radiation exposures to diverse categories of licensees, from commercial nuclear power plants to individual industrial radiographers and nuclear medical practices.
• There are also studies and findings that support the continued use of the LNT model, including those by national and international authoritative scientific advisory bodies.

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Some researchers would use satellites to study the elusive milky sea phenomenon.

What is the Milky Sea?

• Milky seas, also called mareel, is a luminous phenomenon in the ocean in which large areas of seawater appear to glow translucently (in varying shades of blue).
• Such occurrences glow brightly enough at night to be visible from satellites orbiting Earth.
• They are a rare nocturnal phenomenon in which the ocean’s surface emits a steady bright glow.

Why do they glow?

• Luminous bacteria cause the particles they colonize to glow.
• The purpose of this glow could be to attract fish that eat them.
• These bacteria thrive in the guts of fishes, so when their populations get too big for their main food supply, a fish’s stomach makes a great second option.

How do they occur?

• It is typically caused by Noctiluca scintillans (popularly known as “sea sparkle”), a dinoflagellate that glows when disturbed and is found in oceans throughout much of the world.
• Once their population gets large enough – about 100 million individual cells per millilitre of water – a sort of internal biological switch is flipped and they all start glowing steadily.

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A technique used by animals such as dolphins, whales, and bats to navigate their surroundings can also be used by blind people to get around better and have greater independence and well-being, researchers at Durham University in the UK have shown.

What is Echolocation?

• Echolocation, also called biosonar, is a biological sonar used by several animal species.
• Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them.
• They use these echoes to locate and identify the objects.

What has the new study found?

• The same technique can help blind people locate still objects by producing clicking sounds from their mouth and hands.
• The researchers organized a 10-week training programme, in which 12 blind and 14 sighted volunteers aged between 21 and 79 were taught click-based echolocation.
• The volunteers were trained in distinguishing between the size of objects, orientation perception and virtual navigation.
• At the end of the training, the participants had been able to improve their ability to navigate using clicking noises either from one’s mouth, walking cane taps or footsteps.

Researchers from London have found that eye colour in Asians with different shades of brown is genetically similar to eye colour in Europeans ranging from dark brown to light blue.

Human Eye Colour

• Human eye colour ranges from black, brown to blue, green, and even red.
• Eye colour is primarily determined by melanin abundance within the iris pigment epithelium, which is greater in brown than in blue eyes.
• There are two forms of melanin – eumelanin and pheomelanin – and the ratio of the two within the iris as well as light absorption and scattering by extracellular components are additional factors that give irises their colour.
• Absolute melanin quantity and the eumelanin–pheomelanin ratio is higher in brown irises, while blue or green irises have very little of both pigments and relatively more pheomelanin.

Try this PYQ:

Q.Recently, LASIK (Lasser Assisted In Situ Keratomileusis) procedure is being made popular for vision correction. Which one of the following statements in this context is not correct?

(a) LASIK procedure is used to correct refractive errors of the eye

(b) It is a procedure that permanently changes the shapes of the cornea

(c) It reduces a person’s dependence on glasses or contact lenses

(d) It is a procedure that can be done on the person of any age

What has the research found?

• Previously a dozen genes (mainly HERC2 and OCA2) were found to influence eye colour.
• The researchers have now identified 50 new genes for eye colour.
• Genetic analysis of nearly 0.2 million people across Europe and Asia helped the researchers to identify the new genes.
• The findings collectively explain over 53% of eye colour variation using common single-nucleotide polymorphisms.

Outcome of the research

• Overall, the study outcomes demonstrate that the genetic complexity of human eye colour considerably exceeds previous knowledge and expectations.
• These findings will help improve our understanding of eye diseases such as pigmentary glaucoma and ocular albinism where pigment levels play a role.

An improvement in a Machine Learning (ML) model, called ‘federated learning’, is said to enable companies to develop new ways of collecting anonymous data without compromising their privacy.

Data privacy is the right of a citizen to have control over how personal information is collected and used. Data protection is a subset Right of Privacy under Article 21 of the Indian Constitution.

What is ‘federated learning’?

• Federated learning is an ML method used to train an algorithm across multiple decentralised devices or servers holding data samples.
• It doesn’t exchange data with the devices, meaning there is no central dataset or server that stores the information.
• Standard ML models require all data to be centralised in a single server. Implementation of federated learning eliminates the need for maintaining a storage hub.
• The term was first introduced in a 2016 Google study titled ‘Communication-efficient learning of deep networks from decentralized data.’
• Google emphasised mobile phones and tablets, stating that modern devices contain special features like speech recognition and image models that can store large amounts of data.
• Since then, Google has used the technique is various products, including Gboard, which provides text and phrase suggestions to the keyboard.

How this works

• Federated learning aims to train an algorithm, like deep neural networks, on multiple local datasets contained in local nodes, without explicitly exchanging data.
• The general principle involves simply exchanging parameters between these nodes. Parameters include a number of federated learning rounds, the total number of nodes, and learning rate.
• The distinct advantage of the model is its ability to reduce privacy and security risks by limiting the attack surface to only the device, rather than the device and the cloud, Google stated in the study.

Why need such technology?

• Smart home devices like speakers and smartwatches collect and share data with other devices and systems over the network.
• These Internet of Things (IoT) devices are equipped with sensors and software that store a user’s private information like body measurements and location.
• This large chunk of stored data is used by the device makers to improve their products and services.

Applications

• Federated learning is said to have application in healthcare, where hospitals and pharmaceutical companies can exchange data for treating diseases without sharing private clinical information.

Union Health Ministry will soon roll out the FELUDA paper strip test for SARS-CoV-2 diagnosis.

Try this PYQ:

Q.What is Cas9 protein that is often mentioned in news?

(a) A molecular scissors used in targeted gene editing

(b) A biosensor used in the accurate detection of pathogens in patients

(c) A gene that makes plants pest-resistant

(d) A herbicidal substance synthesized in genetically modified crops

FELUDA test

• FELUDA is the acronym for FNCAS9 Editor Linked Uniform Detection Assay.
• It uses indigenously developed CRISPR gene-editing technology to identify and target the genetic material of SARS-CoV2, the virus that causes Covid-19.
• According to CSIR, the test matches accuracy levels of RT-PCR tests, considered the gold standard in the diagnosis of Covid-19, has a quicker turnaround time and requires less expensive equipment.
• It is also the world’s first diagnostic test to deploy a specially adapted Cas9 protein to successfully detect the virus.

How does it work?

• The Feluda test is similar to a pregnancy test strip that will just change colour upon detection of the virus and can be used in a simple pathological lab.
• The Cas9 protein is bar-coded to interact with the SARS-CoV2 sequence in the patient’s genetic material.
• The Cas9-SARS-CoV2 complex is then put on the paper strip, where using two lines (one control, one test) makes it possible to determine if the test sample was infected.

Back2Basics: CRISPR technology

• CRISPR is a short form for Clustered Regularly Interspaced Short Palindromic Repeats.
• It is a gene-editing technology and finds its use in correcting genetic defects and treating and preventing the spread of diseases.
• The technology can detect specific sequences of DNA within a gene and uses an enzyme functioning as molecular scissors to snip it.
• It also allows researchers to easily alter DNA sequences and modify gene function.
• Moreover, the technology can also be configured for detection of multiple other pathogens in the future.

These days, there are diverse opinions rising regarding the legalization of CBD oil in India after recent controversy rose after the alleged suicide of an actor.

What is CBD oil?

• CBD oil is an extract from the cannabis plant.
• The two main active substances in it are cannabidiol or CBD and delta-9 tetrahydrocannabinol, or THC.
• The high that is caused by the consumption of cannabis is due to THC.
• CBD, however, does not cause a “high” or any form of intoxication.
• CBD oil is made by extracting CBD from the cannabis plant, then diluting it with a carrier oil like coconut or hemp seed oil.

What are the effects of Cannabidiol?

• Cannabidiol has effects on the brain, preventing the breakdown of a chemical that aggravates the pain and affects mood, and mental function. It can reduce pain and anxiety.
• It also reduces psychotic symptoms associated with conditions such as schizophrenia as well as epilepsy.

Is it legal in India?

• The Narcotic Drugs and Psychotropic Substances Act, 1985 (NDPS Act) outlaws the recreational use of cannabis.
• The NDPS Act, however, does not apply to the leaves and seeds of cannabis plants. In case the CBD is extracted from the leaves of the cannabis, then technically it is not illegal.
• CBD oil manufactured under a licence issued by the Drugs and Cosmetics Act, 1940 can be legally used.
• However, the use of cannabis as a medicine is not much prevalent in India.

Now try this PYQ:

Q. Widespread resistance of malarial parasite to drugs like chloroquine has prompted attempts to develop a malarial vaccine to combat malaria. Why is it difficult to develop an effective malaria vaccine?

A) Malaria is caused by several species of Plasmodium

B) Man does not develop immunity to malaria during natural infection

C) Vaccines can be developed only against bacteria

D) Man is only an intermediate host and not the definitive host

Recently, a rare biological phenomenon called Gynandromorphism was observed in dragonflies at Kole wetlands of Kerala.

Gynandromorphism is a core biology concept. We can expect a prelims question in a rare scenario.

Try this question from CSP 2013:

Q.Improper handling and storage of cereal grains and oilseeds result in the production of toxins known as aflatoxins which are not generally destroyed by normal cooking process. Aflatoxins are produced by

(a) Bacteria (b) Protozoa (c) Moulds (d) Viruses

Gynandromorphism

• Gynandromorphs are individual animals that have both genetically male and female tissues and often have observable male and female characteristics.
• They may be bilateral, appearing to divide down the middle into male and female sides, or they may be mosaic, with patches characteristic of one sex appearing in a body part characteristic of the other sex.
• Gynandromorphs occur in insects, spiders, crustaceans, and other arthropods as well as in birds, but they are extremely rare, and discovering one in the field or in the laboratory is a major event.
• Estimating how frequently they occur is difficult because they usually go unnoticed in species where sexual dimorphism is less pronounced.
• Gynandromorphs have been reported in mosquitoes, fruit flies, and in other insects, but they are most dramatic in those butterfly species in which the male and female wing colours and patterns are dramatically different.

‘Truenat’, a diagnostic machine used to test drug-resistant TB has now been approved by Indian Council of Medical Research (ICMR) for conducting Covid-19 tests.

Truenat

• The Truenat TB test is a new molecular test that can diagnosis TB in one hour as well as testing for resistance to the drug rifampicin.
• This test for TB uses a sputum sample taken from each patient.
• It is a small battery operated device which requires minimal training and is usable even in smaller settings such as the Primary Health Centre.
• It uses a chip-based technology and takes just up to 60 minutes for a test, screening or confirmatory.

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.

Men outnumbered women by 37 million in the 2011 Census of India, but among those over the age of 60, there were more than 1 million more women than men. In general, men live shorter lives than women worldwide. This is due to the chromosomal differences between the two, points’ new study.

What are Chromosomes?

• The human body is made up of cells, and in the centre of each cell is the nucleus. Chromosomes, which are located inside the nucleus, are structures that hold the genes.
• It is the genes that determine the various traits of an individual including eye colour, blood type — and sex.
• The human cell has 23 pairs of chromosomes. One pair is of the sex chromosomes, named X and Y, which determine whether an individual is male or female.
• A female has two X chromosomes (XX) while a male has one X and one Y (XY).

Unguarded X hypothesis

• This hypothesis suggests that the Y chromosome in XY is less able to to protect an individual from harmful genes expressed on the X chromosome.
• In a male, as the Y chromosome is smaller than the X chromosome, it is unable to “hide” an X chromosome that carries harmful mutations, which may later expose the individual to health threats.
• On the other hand, the hypothesis goes, there is no such problem in a pair of X chromosomes (XX) in a female.
• If one of the X chromosomes has genes that have suffered mutations, then the other X chromosome, which is healthy, can stand in for the first, so that the harmful genes are not expressed.
• This maximizes the length of life, according to the hypothesis. And this is what the UNSW researchers set out to examine.

Testing the hypothesis

• In a statement issued by UNSW, PhD student and study first author Zoe Xirocostas said the
• Unguarded X hypothesis appears to stack up, after examining the lifespan data available on a wide range of animal species.
• Researchers studied lifespan data in not just primates but mammals and birds, but also reptiles, fish, amphibians, arachnids, cockroaches, grasshoppers, beetles, butterflies and moths among others.
• It was found that across that broad range of species, the heterogametic sex (XY in humans) does tend to die earlier than the homogametic sex (XX in humans).

Researchers at Tel Aviv University have discovered a non-oxygen breathing animal, which significantly changes one of science’s assumptions about the animal world — that all animals use aerobic respiration and therefore, oxygen.

Henneguya Salminicola

• The organism is Henneguya salminicola, a fewer-than-10-celled microscopic parasite that lives in salmon muscle.
• It relies on anaerobic respiration (through which cells extract energy without using oxygen).
• In the case of this non-oxygen breathing organism, evolution turned it into a simpler organism that shed “unnecessary genes” responsible for aerobic respiration.
• Other organisms such as fungi and amoebas that are found in anaerobic environments lost the ability to breathe over time.
• The new study shows that the same can happen in the case of animals, too.

What is Aerobic respiration?

• Animals, including humans, need energy to perform the various tasks that are essential for survival.
• Aerobic respiration is one such chemical reaction through which organisms take in oxygen and release carbon dioxide into the atmosphere.
• Through this mechanism, energy is transferred to cells, which can use it for multiple purposes — for instance, to burn food.
• Mitochondria is the “powerhouse” of the cell, which captures oxygen to make energy — its absence in the H. salminicola genome indicates that the parasite does not breathe oxygen.