Question

Q4. It is now known that different species have evolved Lineage - Specific microbiomes. Discuss the interoky between gastrointestinal Microbiomes and species evolution using a named example (40%) and how dysbiosis can lead to fatal conditions (30%). Vour answer should include how the develop ment of animal models can be used to investigate the role of microbiome (301). ? O different species have evolved lineage - Specific microbiomes © discuss intero lay between gastrointestinal microbiomes and species evolution using a named example (3) How the development of animal models can be used to investigate the role of microbiome?

Answer 1

1. Shared evolutionary traits are important for both hosts and microbiota. It has been observed that germ-free mice can be colonized by bacteria from a wide range of environments. However, more closely related bacteria colonize more effectively in mice than unrelated bacteria. For example, mice colonized with gut microbiota from humans unable to develop complete intestinal immunity. Human microbiota colonized in mice is more prone to infection compared to mice with native microbiota. The specificity of the host affects colonization dynamics for specific microbial lineages.

2. A number of studies indicate that microbiome plays a crucial role in fitness, selection, and evolution of species. Owing to diverse dietary requirements or biogeography, many vertebrates species have evolved diverse gastrointestinal traits (GIT). These traits defined by specific host species microbiome signatures. For example, gastrointestinal traits of chicken are inhabited by diverse microbiome which includes bacteria, methanogenic archaea, fungi, and viruses. Microbiome of chicken secretes certain enzymes which are important for the degradation of dietary polysaccharides which serve as nutrition for the chicken. Chicken lacks the genes for glycoside hydrolase (GH), polysaccharide lyase (PL), and carbohydrate esterase (CE) enzymes that are required for polysaccharides degradation. Further chicken microbiome, contains genes for antibiotic resistance, iron scavenging, types III and IV secretion, adhesion, invasion and intracellular resistance. Presence of these genes in chicken GIT, limit the colonization of zoonotic pathogens and hence increase the fitness of chicken by providing the resistance against infection.

3. It has been demonstrated by various researchers that microbiome plays an important role in human health and many diseases. Due to the significance of the microbiome role in human health, there is a growing interest in finding suitable animal models to study the role of microbiota in disease. The animal study can provide proof of concept studies pertaining to the role of microbiota in diseases. For example, if we proposed that altered microbiota leads to Alzheimer's disease. We should have an animal model where the proposed microbiota can be colonized and can examine the development or progression of Alzheimer's disease.