Regarding to genetic information that we have at disposal, nowadays, we can be sure that once existed one common antecessor for fish and tetrapodes who had a genome (composed by master genes Hox and switch genetic material called CsB) prepared to express, progressively, new elements that allowed the development of extremities. In blog Divulgation (34) we mentioned that the apparition of articulated extremities, into pectoral fins of coelacanth, 416 million years ago, and of tiktaalik fossil of sarcaopterigean fish 380 million years ago, it is related to the existence of some genetic switches called CsB which are also presents in other fishes ( zebra fish, manta ray ) in amphibious ( frog ), reptile, birds ( chicken ) and mammals (  mouse ).

Genetic material is so identical that mouse CsB activates genetic expression in the external edge of zebra fish fin, and zebra fish CsB, the same as manta ray one, they are able to activate genetic expression of scaphoide bone, trapezium, trapezoide and phalanxes of mouse extremities. In conclusion, even there is an evolutive distance of 400 million years, genetic switches to control gen expression in mouse fingers, they are not only present in fish, also fish versions can activate the genetic expression in mouse embryos.

Regardless of this cross, between genetic switches CsB between fish and mammals, it is true that this is a consequence of something more primitive yet: The genome of common antecessor should have  a designed previous program, when good conditions took place, to become the formation of origin cartilage of extremities articulations, front and back of tetrapodes, including mammals. This fact has been proved by reaching that overstimulation of master gen hox13 of the fins in zebra fish embryos allows the development of similar structures to the extremities of tetrapodes. This evolution that, in nature needed up to twenty-five million years, may be observed in laboratory in a period of 24 hours during the development of zebra fish embryo. However the expression of one gen moreover than programming requires, most of the times, of an external stimulation coming from nutrition.

In blog Divulgation (26) called “Importance of pronutrients and nutragenics in genetic expression of animal cells”, we mentioned that: “ The presence of some nutrients, of vegetal origin, is in the genetic expression that has origined new animal cells and organs with a basic metabolism linked to those substances called pronutrients” and after we said that “ in reptile, birds and mammals, some of these pronutrients should be given to embryo in very early status ( equal to primitive patterns in evolution scale ) for the appropiate genetic expression of determined organs.

Following this way of thinking we should be able to link the presence of one pronutrient, in the coast brown alga of 500 to 400 million years ago seas, with the expressin of one gen that gave rise to the extremities of tetrapodes from the fins of coast fish, allowing, this way, the possibility to begin colonization of dry land.

In fact, fossil registers of  brown alga, from Macrocistis, Fucus, Laminaria and Seytosiphon types, show great abundance of them in coast zones and it has been proved that those alga present, actually, high contents in iodized products and calcitriol.

It has been discovered that iodine and calcitriol regulate the expression of several genes which codify the enzymes called demetilase histones, with the function to modify specific aminoacids, which play a key role in the epigenetic regulation of  Hoxd 10-13 genes, a base to generation of extremities. It is possible that some predecessor alga existed (590 to 540 million years) previous to brown alga and pronutrient substances predecessor to calcitriol and iodized compounds to cause or produce the process. Actual knowledges place the relationship between coast alga and iodized compounds and calcitriol, and between these ones and the overstimulation of Hox genes through CsB switches.

If this process is true we must find evidences, of this relationship, in the actual amphybious which have a metamorphosis based on the development of back extremities in a later phase after hatching. In fact, iodized products regulate the development of metamorphosis in frog tadpoles and at the same time there’s a relationship between iodized products and calcitriol in bones development.

This way we can link the existence of big quantities of brown alga ( or their predecessors depending on fossil registers ) rich in iodized products and calcitriol ( or their botanic predecessors ) in seas of 600 to 400 years ago coinciding, in evolution time, with the expression of genes existing in the genoma of common antecessors of fish and tetrapodes. That’s why the big importance of iodized pronutrients ans calcitriol in metabolism of cartilage and bone cells.