Daily Current Affairs (MCQ's) | 10-03-2023

Q1. Which of the following is the most apt definition of the Environmental DNA (eDNA)?

a. It is set of DNA from various species that defines an ecosystem

b. It is ancient DNA that helps in fossil studies like for one dinosaurs

c. It is DNA sample of indicator species of an ecosystem

d. It is organismal DNA that can be found in the environment

Answer (d)

Explanation:

Environmental DNA (eDNA) is organismal DNA that can be found in the

environment. Environmental DNA originates from cellular material shed by organisms (via skin, excrement, etc.) into aquatic or terrestrial environments that can be sampled and monitored using new molecular methods. Such methodology is important for the early detection of invasive species as well as the detection of rare and cryptic species.

Environmental DNA (eDNA) is nuclear or mitochondrial DNA that is released from an organism into the environment. Sources of eDNA include secreted feces, mucous, and gametes; shed skin and hair; and carcasses. eDNA can be detected in cellular or extracellular (dissolved DNA) form.

In aquatic environments, eDNA is diluted and distributed by currents and other hydrological processes (fig. 1), but it only lasts about 7–21 days, depending on environmental conditions (Dejean and others, 2011). Exposure to UVB radiation, acidity, heat, and endo- and exonucleases can degrade eDNA.

Q2. Which of the following is/are possible applications of environmental DNA (eDNA)?

1. Detect the presence of human remains

2. Study of ancient life

3. Early detection of invasive species

4. Biodiversity assessments

5. Detection of rare and cryptic species

Select the correct option from codes given below

a. 3 and 4 only

b. 1, 3 and 4 only

c. 2, 3, 4 and 5 only

d. 1, 2, 3, 4 and 5

Answer (d)

Explanation:

All of The Above Are Application Of The eDNA

A new study, led by geologist and glacier expert Kurt Kjær, has discovered ancient environmental DNA (eDNA) that describes the rich plant and animal presence in the Kap København Formation in Peary Land of northern Greenland – now a polar desert. This DNA dates back to an astounding two million years ago.

The DNA record shows a high-latitude forest ecosystem with mixed vegetation of trees including poplar, birch, and thuja, and a variety of Arctic boreal shrubs and herbs too, many of which had not previously been detected at the site from macrofossil and pollen records.

The new discovery confirms the presence of mitochondrial DNA from animals including mastodons (now extinct), reindeer, rodents and geese. All of these are ancestral to their present-day relatives.

Improved Detection of Native Species

Protocols using eDNA may allow for rapid, cost-effective, and standardized collection of data about species distribution and relative abundance. For small, rare, secretive, and other species that are difficult to detect, eDNA provides an attractive alternative for aquatic inventory and monitoring programs. Increasing evidence demonstrates improved species detection and catch-per-unit effort compared with electrofishing, snorkeling, and other current field methods. Thus, detection of species using eDNA may improve biodiversity assessments and provide information about status, distribution, and habitat requirements for lesser-known species.

Early Detection of Invasive Species

eDNA may also be an effective tool for early detection of aquatic invasive species. Application of eDNA methods for invasive species monitoring may include periodically collecting water samples and screening them for several invasive species at once. Boat-ballast water, a source of introduction for many invasive species including mollusks, also could be sampled. Some intensive eradication programs for invasive species fail when a few surviving individuals recolonize the ecosystem. eDNA methods may provide a means of confirming eradication of all invaders.

Other Applications:

Scientists have now hit upon the idea of collecting this environmental DNA, or eDNA, in the depths of the seas to identify what lives there — a simpler method than having to go down there to study.

Stories are seeping out of scientific journals about how scientists are using eDNA to survey biodiversity in rivers, lakes and oceans. Apart from giving a biodiversity picture, such study could also yield early clues to invasive species. Such methodology is important for the early detection of invasive species as well as the detection of rare and cryptic species.

eDNA can also reveal the presence of human remains. Scientists have collected samples of seawater from the vicinity of a plane wreck — the American aircraft was shot down near Japan during the Second World War — to look for floating eDNA.

Q3. Which of the following organisms's increased population will cause significantly more greenhouse gas emission?

a. Mangroves

b. Whales

c. Termites

d. Sea otters

Answer (c)

Explanation:

How termite behavior is linked to a warming world: Findings of a new study The study revealed that as the Earth gets warmer, termites will rapidly spread across the world. This could, in turn, lead to a further rise in global temperatures.

A recent study has found that termites decompose wood at a much higher rate in warmer conditions. For every 10 degrees Celsius increase in temperature, their decomposition activity goes up by almost seven times, it added.

Published in Science, the study also revealed that as the Earth gets warmer, termites will rapidly spread across the world. This could, in turn, lead to a further rise in global temperatures, because these small insects while consuming deadwood release carbon into the atmosphere.

Termites and dead wood It’s well-known that trees play a significant role in the global carbon cycle. They absorb carbon dioxide through the process of photosynthesis and help in keeping the atmospheric temperature low.

As a tree grows older, certain parts of it die and become dead wood, which is eventually decomposed by microbes and insects like termites. The decaying of dead wood results in the release of not only a variety of nutrients but also carbon.

According to the study, termites release carbon from dead wood in the form of carbon dioxide and methane, two of the most important greenhouse gasses. So, an increase in termite population and their faster decomposing activity can cause more greenhouse emissions, resulting in a hotter planet.

Whales | Deep Sea Climate Solution

As Earth’s largest mammal, whales absorb an average of 33 tons of CO2 each throughout their lifetimes. When they die, their carcasses fall to the bottom of the ocean and remain there for centuries, keeping that stored carbon out of the atmosphere. Even their excrement goes to work! Whale droppings act as a fertilizer for phytoplankton, which pulls ten gigatons of carbon from the atmosphere into the deep ocean each year. Unfortunately, whale populations have dramatically declined due to pollution and hunting. If whale populations were allowed to return to around 4-5 million, a massive 1.7 billion tons of carbon could be captured each year.

Sea Otters | Guardians Of Kelp Forests

One of the most adored species on our planet, sea otters act as guardians of underwater kelp forests. Kelp forests are one the most efficient absorbers of CO2, using carbon from the atmosphere to grow leafy structures below the surface. Yet, these forests are particularly delicious if you are a sea urchin. If left unchecked, these small, spiky marine animals multiply rapidly, sweeping across the ocean floor and devouring entire stands of kelp. As keystone predators, sea otters keep these urchin populations in check. A study found that kelp forests guarded by sea otters can absorb 12 times more carbon dioxide than those without. An estimated carbon capture value of $200-400 million annually is provided by sea otters.

Q4. Consider the following statements with regard to the

‘Organ on a chip’ model

1. These are small devices containing human cells that are used to mimic the environment in human organs

2. It is one of the experimental alternatives to animals to test new drugs

3. This model are also being used to grow human organs for safe transplantation

4. However these models are less human relevant than animal models like mice

Which of the above statements is/are correct?

a. 1 and 2 only

b. 3 and 4 only

c. 2, 3 and 4 only

d. 1, 2, 3 and 4

Answer (a)

Explanation:

‘Organ on a chip’: The new lab setup scientists are using instead of animals to test new drugs

• The recent U.S. Food and Drug Administration Modernization Act 2.0 brought cheer to animal rights activists and drug developers alike. By approving the Act, the US government green-lit computer-based and experimental alternatives to animals to test new drugs.

• The move is expected to boost the research and development of organ chips – small devices containing human cells that are used to mimic the environment in human organs, including blood flow and breathing movements, serving as synthetic environments in which to test new drugs.

• For more than a decade, scientists, pharmaceutical companies, and animal activists have been pushing regulators to include synthetic setups that mimic human diseases, in addition to using animals, as drug testbeds, with arguments rooted in science, commerce, and ethics.

Alternative route to quick and cheap clinical trials:

• As of today, fewer than 10% of new drugs complete preclinical studies and fewer than 50% of these eventually enter the market. Some researchers believe that the use of animal models in preclinical studies could be to blame for this enormous failure rate.

• The current scientific consensus is that animals mimic some human diseases well but not others. In cases where they can’t mimic a condition, a new drug that seems promising in preclinical studies is almost certainly bound to fail in human clinical trials.

• These challenges have led scientists to look for alternative models that mimic human diseases. One such is the organ-on-chip model, which has garnered a lot of attention in the last decade.

• Donald E. Ingber, a professor of bioengineering and director of the Wyss Institute at Harvard University, and his colleagues developed the first human organ-on-chip model in 2010. It was a ‘lung on a chip’ that mimicked biochemical aspects of the lung and its breathing motions.

• In 2014, members of Wyss Institute launched a start-up called Emulate Inc. to commercialize their technology. The group has since created several different chips, including of the bone marrow, epithelial barrier, lung, gut, kidney, and vagina. The researchers used liver chips to evaluate the toxic effects of 27 drugs known to be either safe or cause liver injury in humans. Apart from organs, researchers are also trying to mimic different disease states using chips.

More Human-Relevant Than Animal Models:

• All these researchers agree that these models are great tools to mimic human organs and their diseases. Since we use human cells in these organ-on-chip models, they are more human-relevant than animal models. Moreover, they are free from ethical issues associated with [the use of] animal models

Q5. Which of the methods are being used in cancer treatment?

1. Proton beam therapy (PBT)
2. Surgery
3. Radiotherapy
4. Immunotherapy
5. CAR T-cell therapy

Select the correct option from codes given below

a. 2 and 3 only
b. 2, 3 and 4 only
c. 1, 2 and 3 only
d. 1, 2, 3, 4 and 5

Answer (d)

Explanation:
Why CAR T-cell therapy is cancer treatment’s next moonshot
The three major forms of treatment for any cancer are surgery (removing the cancer), radiotherapy (delivering ionizing radiation to the tumor), and systemic therapy (administering medicines that act on the tumor). Surgery and radiotherapy have been refined significantly over time – whereas advances in systemic therapy have been unparalleled. A new development on this front, currently holding the attention of many researchers worldwide, is CAR T-cell therapy.
 
Chemo and immunotherapy Systemic therapy’s earliest form was chemotherapy: when administered, it preferentially acts on cancer cells because of the latter’s rapid, unregulated growth and poor healing mechanisms. Chemotherapeutic drugs have modest response rates and significant side-effects as they affect numerous cell types in the body.

The next stage in its evolution was targeted agents, a.k.a. immunotherapy: the drugs bind to specific targets on the cancer or in the immune cells that help the tumor grow or spread. This method often has fewer side-effects as the impact on non-tumour cells is limited. However, it is effective only against tumors that express these targets.

What are CAR T-cells?

Chimeric antigen receptor (CAR) T-cell therapies represent a quantum leap in the sophistication of cancer treatment. Unlike chemotherapy or immunotherapy, which require mass-produced injectable or oral medication, CAR T-cell therapies use a patient’s own cells. They are modified in the laboratory to activate T-cells, a component of immune cells, to attack tumors.

These modified cells are then infused back into the patient’s bloodstream after conditioning them to multiply more effectively.

The cells are even more specific than targeted agents and directly activate the patient’s immune system against cancer, making the treatment more clinically effective. This is why they’re called ‘living drugs’.

How Does It Work?

In CAR T-cell therapy, the patient’s blood is drawn to harvest T-cells – immune cells that play a major role in destroying tumor cells. Researchers modify these cells in the laboratory so that they express specific proteins on their surface, known as chimeric antigen receptors (CAR): they have an affinity for proteins on the surface of tumor cells. This modification in the cellular structure allows CAR T-cells to effectively bind to the tumor and destroy it.
 
Conventional chemotherapy or immunotherapy comprises molecules that bind to the tumor or block chemical pathways that allow the tumor to grow or multiply – but don’t directly affect the immune system. The final step in the tumor’s destruction involves its clearance by the patient’s immune system.

When there are abnormalities in the immune system or when the tumor finds a way to evade it, the cancer resists these drugs. In CAR T-cell therapy, the immune system is activated when the modified T-cells are reintroduced into the body, which allows a gradual and sustained tumor kill as these cells multiply.

Where Is It Used?

As of today, CAR T-cell therapy has been approved for leukaemias (cancers arising from the cells that produce white blood cells) and lymphomas (arising from the lymphatic system). These cancers occur through unregulated reproduction of a single clone of cells: following the cancerous transformation of a single type of cell, it produces millions of identical copies. As a result, the target for CAR T-cells is consistent and reliable.

CAR T-cell therapy is also presently used among patients with cancers that have returned after an initial successful treatment or which haven’t responded to previous combinations of chemotherapy or immunotherapy.

Proton Beam Therapy (PBT)

Unlike radiation which uses X-rays, PBT uses protons to tackle cancer. While radiation can prove toxic to the whole body, protons can destroy cancer cells precisely by targeting tumors, thus saving adjoining organs. Cancer patients in India face twin challenges when it comes to accessing proton beam therapy (PBT): there are not enough facilities offering the treatment, and the cost can run into tens of lakhs of rupees.

The PBT is considered a viable alternative to radiation for treating solid tumors, especially for head and neck cancers.