Context:
Researchers in China, proposed a model to explain how different combinations of mutations give rise to the different colours of the cocoons.
Silk:
- Silk is reeled from cocoons of the silk moth and they based on feed they are classified.
- Silk (the queen of fibres), was domesticated by humans more than 5,000 years ago in China, from the wild moth.
- Wild silks – muga, tasar, and eri silks
- Obtained from moth species namely Antheraea assama, Antheraea mylitta, and Samia cynthia ricini.
- Mulberry silks – They have long, fine, and smooth threads.
- Non-mulberry silks – They have shorter, coarser, and harder threads.
| Mulberry Silk | ||
| Ancestral Species | Domesticated Species | |
| Spread | China, Korea, Japan, & Russia | All around the world including India |
| Size | Small | Larger |
| Fibre length | Small | Longer, up to 900 metres |
| Cocoon colour | Brown-yellow | Yellow-red, gold, flesh, pink, pale green, deep green or white. |
| Flying ability | Exists | Lost |
| Pigmentation | Observed | Lost |
India is the world’s 2nd largest producer of raw silk after China and non-mulberry silks comprise about 30% of all silk produced in India.
Silk Colour:
- Mulberry leaves have colouring chemical compounds called carotenoids and flavonoids which are absorbed by silkworms when they feed it.
- The absorbed chemicals are transported to the silk glands, where they are bound to the silk protein.
- Currently, domesticated cocoons possess water soluble colour that gradually fade away and so silk colours are derived from chemical compounds made by the mulberry leaves.
- The differently coloured cocoons arise from mutations in genes responsible for the uptake, transport, and modification of carotenoids and flavonoids.
Source: The Hindu
Previous Year Question
With reference to “Gucchi” sometimes mentioned in the news, consider the following statements:
1. It is a fungus.
2. It grows in some Himalayan forest areas.
3. It is commercially cultivated in the Himalayan foothills of north-eastern India.
Which of the statements given above is/are correct?
[UPSC Civil Services Exam – 2022 Prelims]
(a) 1 only
(b) 3 only
(c) 1 and 2
(d) 2 and 3
Answer: (c)
