S: AR – https://www.annualreviews.org/doi/abs/10.1146/annurev.genet.37.110801.143820 (last access: 11 November 2020); T. Gilat – https://www.sciencedirect.com/science/article/abs/pii/S0016508572800805 (last access: 11 November 2020).
N: 1. It is formed by the latin prefix lacto- which means “milk” and -ase used to form the names of enzimes.
2. Enzyme found in the small intestine of mammals that catalyzes the breakdown of lactose (milk sugar) into the simple sugars glucose and galactose.
3. Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation (−13910*T) explains the distribution of the phenotype, whereas several mutations are associated with it in Africa and the Middle East.
4. Without this enzyme, mammals are unable to break down and thus use lactose, and since milk is the essential component of young mammals’ diet, lactase activity is fundamental to the early development of most mammals.
5. There is often confusion between lactase and ß-galactosidase. This is due to the similarity of thematic field, but lactase is specific to humans and ß-galactosidase is an enzyme that is not exclusive to humans.
S: 1. Wiktionary – https://en.wiktionary.org/wiki/-ase#English ; MW – https://www.merriam-webster.com/dictionary/lactase (last access: 12 November 2020). 2. EncBrit – https://www.britannica.com/science/lactase (last access: 14 November 2020). 3&4. RS – https://royalsocietypublishing.org/doi/full/10.1098/rstb.2010.0268 (last access: 12 November 2020). 5. NCBI – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3575911/ (last access: 14 November 2020).