ISSUE FOCUS 46 FEED & ADDITIVE MAGAZINE September 2023 Heat shock proteins (Hsps) are essential for cell homeostasis and therefore, animal health. Despite their name, Hsps are for an animals’ response to a wide range of stressors other than heat including pathogens, nutritional stress and even exercise. Using cactus extract, we can modulate the Hsp response, bolster disease resistance and enhance bird productivity. Harnessing heat shock protein responses: IT’S ABOUT MORE THAN HEAT STRESS Reginaldo Teixeira Filho Natturo Agronegócios, Brazil David Harrington teamTWO Solutions, Denmark Charles Saliba Nutri Biotech Services, Malta HEAT SHOCK PROTEINS AND THEIR DISCOVERY The concept of biological molecules related to genetic responses to thermal stresses were first shown in the early 1960’s by Ritossa in Drosophila busckii. In 1962, he observed that temperature shocks induced changes in both the metabolic activities and puffing patterns of the salivary gland chromosomes of Drosophila larvae (Ritossa, 1962). The puffs indicated that genes were being activated in that region of the genome and the encoded proteins synthesised. Ritossa further identified the puffing pattern in response to other stressors such as endotoxins and hypoxia. Later work by other researchers identified the main group of proteins corresponding to the individual puffs, calling them “heat shock proteins” (Hsps). It was later demonstrated that Hsps, in particular members of the Hps60 and Hsp70 families, were exceptionally well conserved across organisms. For example, Hsp70 in humans is 99% identical to the mouse (Mus muscularis), 74% identical to D. melanogaster and 44% identical to Escherichia coli (Desai et al., 2010). HSP CLASSIFICATION Currently, Hsps are classified based on their molecular masses into the following major groups: small heat shock proteins (sHsps) family (molecular masses 10-30 kDa); Hsp40 family (40 kDa); Hsp60 (or chaperonins) (molecular mass close to 60 kDa); Hsp70 family (70 kDa); Hsp90 family (83-90 kDa); and Hsp100/110 family (≥ 100 kDa). Each family can also include homologues with similar or slightly different functions which
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