Molecular Molecular PhylogenyPhylogeny

course: Sequence Informationcourse: Sequence InformationStudentsStudents: : Razick Ahmed SabryRazick Ahmed SabryMehio Wissam Mehio Wissam Lydakis ApostolosLydakis ApostolosSathyanara TejashwariSathyanara Tejashwari

Introduction – Growth Introduction – Growth hormonehormone

Growth hormone (or somatotropin) is a protein hormone of about 190 amino acids

Synthesized and secreted by cells called somatotrophs.

A major participant in control of several complex physiologic processes, including growth and metabolism.

Also of considerable interest as a drug used in both humans and animals.

Methods of PhylogenyMethods of Phylogeny Maximum ParsimonyMaximum Parsimony: Optimal tree is the one : Optimal tree is the one

with the fewest mutations.with the fewest mutations.

Maximum LikelihoodMaximum Likelihood: Assigns probabilities to : Assigns probabilities to mutations. The optimal tree is the one with mutations. The optimal tree is the one with highest probability.highest probability.

Distance MatrixDistance Matrix: The optimal tree is the one : The optimal tree is the one resulting from the least number of inter-species resulting from the least number of inter-species distance and evolution.distance and evolution.

ApproachApproach 1

Trying to prove Trying to prove ((ApproachApproach 1)

Evolution of pituitary growth hormone (GH) in Evolution of pituitary growth hormone (GH) in mammals has generally been very slow but with short mammals has generally been very slow but with short bursts of rapid change in the evolution of some groups. bursts of rapid change in the evolution of some groups. Such a period of Such a period of rapid changerapid change occurred in the evolution occurred in the evolution of GH in of GH in primates or a primateprimates or a primate ancestorancestor and gave rise and gave rise to the marked species specificity of human GH. By to the marked species specificity of human GH. By cloning and sequencing of GH genes from a cloning and sequencing of GH genes from a prosimian,prosimian, the the slow lorisslow loris ( (Nycticebus pygmaeusNycticebus pygmaeus), and a ), and a New World New World monkeymonkey, the , the marmosetmarmoset, (, (Callithrix jacchusCallithrix jacchus)it has been )it has been shown that …shown that …

prosimian GH is similar in sequence to pig prosimian GH is similar in sequence to pig GH while marmoset GH resembles human GH while marmoset GH resembles human

GH GH

ApproachApproach 1 , Strategy Research already done suggests the Research already done suggests the

following facts,following facts, “ “The period of rapid change in The period of rapid change in

sequence for GH during primate sequence for GH during primate evolution occurred evolution occurred after the after the separation of lines leading to separation of lines leading to prosimiansprosimians and higher primatesand higher primates and and before divergence of lineages for New before divergence of lineages for New World monkeys and Old World World monkeys and Old World monkeys/apesmonkeys/apes.”.”

Our results of ApproachApproach 1

Mammals

Prosimians and higher primates

New world monkey

Old world monkey

Human

Other mammals

ApproachApproach 1 , results suggests

Mammals

Prosimians and higher primates

New world monkey

Old world monkey

Other mammals

Conclusion from Approach 1

Human

ApproachApproach 2

Distance MatrixDistance Matrix

Maximum ParsimonyMaximum Parsimony

Maximum LikelihoodMaximum Likelihood

Biological InterpretationBiological Interpretation It is obvious from the previous results that the human GH is It is obvious from the previous results that the human GH is

different from that of the rabbit, pig, elephant, dog, cat, and different from that of the rabbit, pig, elephant, dog, cat, and alpaca. The trees suggest that the primates have a different alpaca. The trees suggest that the primates have a different GH than that of the other mammals. This hypothesis was GH than that of the other mammals. This hypothesis was proved by when lab experiments showed that only human proved by when lab experiments showed that only human and primate growth hormone have significant effects in and primate growth hormone have significant effects in humans, which suggests that the receptor for GH has also humans, which suggests that the receptor for GH has also mutated in primates.mutated in primates.

It is noteworthy that GH tends to be similar among species It is noteworthy that GH tends to be similar among species that have similar looks, sizes, and body functions.that have similar looks, sizes, and body functions.

Some studies showed that the “Slow Loris” constitutes the Some studies showed that the “Slow Loris” constitutes the turning point of the evolution of GH among mammals, but turning point of the evolution of GH among mammals, but the sequencing we conducted showed nothing of that, in the sequencing we conducted showed nothing of that, in fact the Slow Loris tended to show similarity withfact the Slow Loris tended to show similarity with

ConclusionConclusion Somewhere along the line of evolution of Somewhere along the line of evolution of

mammals there is a sharp mutation in GH, which mammals there is a sharp mutation in GH, which led to the formation of primates. The latter led to the formation of primates. The latter evolved more and more to yield up species like evolved more and more to yield up species like chimpanzee and homo sapiens.chimpanzee and homo sapiens.

MacacaMacaca

Back to Tree

CallithrixCallithrix

Back to Tree

Slow LorisSlow Loris

Back to Tree