Proteomics CASE STUDY

Question 1

Who is cited for this study

Answer 1

Scott et al, 2020

Question 2

Title of study

Answer 2

Exotic foods reveal contact between South Asia and the Near East during the second millennium BC

Question 3

Extraction sample size

Answer 3

• Total protein was extracted from the dental calculus of 14 individuals
• Dietary proteins were identified in 5 individuals and consisted of 19 proteins from 5 plants of known importance: wheat, sesame, soybean, banana, and turmeric

Question 4

Wheat protein identification

Answer 4

• Wheat proteins were identified in a single invidual
• 2 proteins supported by 3 peptides
• And a major gluten protein supported by 3 peptides

Question 5

Importance of wheat protein identification

Answer 5

• Wheat was an expected find
• Had been a stable crop in the Levant since the 7th Millennium BCE
• Microfossils found in Bronze Age Levant

Question 6

Sesame protein identification

Answer 6

• Sesame proteins identified in 3 individuals
• 2 proteins supported by 29 peptides

Question 7

Importance of sesame protein identification

Answer 7

• Important new find
• Not entirely unexpected
• Nonlocal domesticate from South Asia
• Spread to West Asia during bronze age
• Arrival in Levant is less understood
• Found robust evidence for multiple sesame seeds in the study which suggests that by the second millennium BCE sesame had become a stable oil bearing crop in the Levant

Question 8

Soybean protein identification

Answer 8

• Identified in a single individual
• 2 proteins supported by 29 peptides

Question 9

Importance of soybean protein identification

Answer 9

• Unexpected
• Soybean cultivation unknown in the region before C20th BCE
• Soybean’s domestication centre was in central China as early as 7000 - 6500 BCE
• Major oil plaant
• Oil could’ve been transported far distances
• Difficult to differentiate plant oils through lipid analysis
• By identifying strong evidence of soybean seed proteins in dental calculus, we confirm the individual had likely access to soybean oil

Question 10

Banana protein identification

Answer 10

• Identified an enzyme important in fruit ripening
• Single individual
• Protein supported by 2 peptides, one of which is highly specific to banana

Question 11

Importance of banana protein identification

Answer 11

• Domesticated during 5th millennium in New Guinea
• But reconstructing intervening cultivation was difficult
• Banana fruit is highly perishable, domesticated bananas are seedless
• Study’s identification lends support for either the banana being present in the Levant by the first millennium BCE, or a mobile individaul who consumed banana before elsewhere before being buried in Tel Erani

Question 12

Turmeric protein identification

Answer 12

• Found in a single individual
• Supported by 3 peptides

Question 13

Importance of Turmeric protein identificaton

Answer 13

• Turmeric starch grains have been identified in both cattle dental calculus and pottery dating back to 2600-2200 BCE
• In Near East its earliest reference is from 7th Century BCE
• Protein identified in the same individual who was found to have soybean rpotein
• Individual was buried in a wealthy collective tomb containing exotic goods
• Either well connected with trading activities or may have been a merchant/trader themselves
• May have consumed foods seasoned with turmeric or prepared with soy oil in the Levant, South Asia, or elsewhere