Comprehensive News Analysis - 26 March 2017

• What Classical theorist thought of?

The phenomenon of niche construction in evolutionary biology has been mooted to be highly important but neglected in evolutionary biology theory. Not just that, it has been termed a concept at par with natural selection.

• Guiding light:

Five Indian evolutionary biologists connected to Evolutionary & Organismal Biology Unit of JNCASR, Bengaluru, have set out to show that this is not so.

Apart from citing instances of the concept’s use in earlier papers, they also argue that incorporating the phenomenon does not involve a major reworking of Standard Evolutionary Theory (SET).

• The Debate:

Over the last two decades, niche construction – the phenomenon by which evolving organisms modify their environment, which in turn increases or decreases their own survival rate – has become much talked about in the literature. Proponents of this theory have argued that it has been neglected in the Standard Evolutionary Theory, which therefore needs a major overhauling. This has been debunked in the paper by the authors.

• A new Domain

The foundational debates within evolutionary biology for the past 15 years have been dominated by scientists from North America and Western Europe.

One of the contentions of the authors is that contrary to the claims that Niche Construction has been neglected in the Standard Evolutionary Theory, they show in the paper that it has been considered by many authors to explain phenomena, even before the term “niche construction” was coined.

Examples:

1. Experimental study done by Borash and others in 1998: The experiment involved breeding larvae of fruit fly, Drosophila melanogaster, in an environment where food was reduced and presence of nitrogenous waste was increased. It was observed that even within one generation the larvae that formed early became heavy feeders and the late developers grew to become waste tolerant. Thus, within one generation, they were able to observe the effect of environment that was altered by the organism (the heavy feeders depleting the environment of food for the late developers). They found that it introduced the above polymorphism – separation into heavy feeders and waste tolerant types.
2. Proponents of niche construction use the following examples often: The use of lactose to feed adult humans – which is believed to have evolved along with cattle husbandry – and the high incidence of sickle cell anaemia in populations where there is a prevalence of malaria, due to yam cultivation

The writers expose the cases by referring to references of the above cases as of now having been utilized inside the traditional hypothesis itself.

3. Indians find a new bacterial target for drug development 

What’s in news?

• Indian researchers have found a new target that can potentially be used for developing new antibiotics that will be effective against many bacteria.
• The new target is made of two proteins(GroEL-PrkC complex), which form a complex that is responsible for the formation of biofilm, that perform very important functions and are critical for bacterial ability to successfully infect humans.
• Till now, all attention has been on developing antibiotics that target disease-causing bacteria and not the biofilm itself.

What is a Biofilm?         

• Biofilm as a biological shield: Bacteria form biofilms, a kind of matrix, during infection in plants and animals. The biofilm shields the bacteria from antibiotics and helps bacteria survive harsh conditions such as extreme temperature or stress.

How bacterial infection can be prevented?

• Target molecular signaling event that leads to synthesis of biofilms in bacteria.

How biofilms are formed?

• Bacteria have sensors on the surface which senses some signal and helps in biofilm formation.
• PrkC a protein senses some signal and transmits it from outside to inside the cell. This signal goes to other proteins like GroEL. PrkC adds phosphate group (phosphorylate) to different proteins. The mystery to biofilm formation lies with one chaperone protein called GroEL. The addition of phosphate to this tiny machine initiates a course of events within bacterial cells leading to complex biofilm formation.(Not required to read-just understand the basic concept)
• When PrkC protein is deleted, Bacillus bacteria are unable to form biofilm
• GroEL-PrkC complex could be a target for developing new antibiotic that will be effective against many bacterial pathogens such as the ones that cause MRSA, TB and pneumonia. One strategy to tackle drug resistant bacteria will be to develop multi-drug regimen that combines traditional antibiotics with candidate drugs that can block bacterial signalling and prevent biofilm formation.

D. GS4 Related

Nothing here for today!!!

Question 1: Choose the correct statement with reference to Biofilms.

Question 2: Consider the following statement: