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In Dino Veritas! Hox Genes and Surroundings

Finally, after two years of work, I can announce:

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In the previous PaleoStoria we talked about how Hox genes and their number varies between different groups of animals and how they are important for the organizations from the body.
But what are these Hox genes, in detail? and why it is interesting to know their function and their distribution in the body? These two questions will try to answer the post today.

Have you ever wondered why most animals have similar body proportions and arrangements? because we, the rat, Tuna and argagosta (for example), we have placed before all of a mouth and an anus located on the back? why do not the contract? we have both a front and a rear portion, our bodies grow in similar positions, between the mouth and anus, the tail in these animals is behind the anal cavity, etc. .. So, all these animals seem to have a very similar body plan and apparently sorted same instructions, why? is that really so?

The answer is yes, it really is, all these animals have the same body plan of organization inherent in their DNA during their embryonic development makes each What grows in the right way, and that the right way is the same for most animals (as well as for all those mentioned above).
Among the many things that make this development is organized to implement, there are also our Hox genes, of which we speak, albeit more general, more dettagglio. I omit other factors because it would require relatively complex genetic bases and it is not my goal to talk about these things.

The discovery of Hox genes is the result (as a lot of other discoveries in genetics) the numerous studies conducted by researchers on a small animal, a fruit fly that responds all'altisonante name Drosophila melanogaster. This small creature, definitely one of the most studied animals in the laboratory, has a physical structure similar to that of most other animals with bilateral symmetry, a digestive system full of appendages, etc., and above all the great advantage to reproduce very quickly, so you can quickly provide various generations to study (as well as many "patients" can expose to a variety of experiments).
Thanks to the study of embryonic development of these insects, researchers have found that sometimes changes occur at the genetic level, such that some individuals are born "deformed", for example, antennae instead of eyes, or with a pair of wings more, or without some body parts, etc..

The question is obvious, because some parts of the body grow where they should not grow? because instead of eyes grow antennas? What sets which parts of the body should grow and where?

Through a series of techniques that allow visualization of the chromosome, the researchers were able to DETECTION area of \u200b\u200bthe chromosome responsible for these mutations and found that in Drosophila there are eight genes that develop mutations, arranged side by side to 'internal lunghisime one of the two helices that make up its DNA. In a surprising (but perhaps not much), these genes are despotic in a well organized, with genes that determine the changes of the head accompanied by one that determines the central portion of the body, then those who contribute to the organization of the back. The arrangement of these genes on the filament reflects the real position of the body parts in the animal developed. Amazing is not it?
These eight genes of Drosophila are our dear Hox genes .
And, listen, listen, Hoxx these genes are found in any animal with a body!
Bingo! We now know that

tuti in the body of the animals with a cover there is a sequence (more or less long) of Hox genes, which play a key role in the organization of the body. Different versions of the same genes operate the layout front - back of the body almost all animals, from octopus to the fly, the horse on eel. If you go to touch the Hox genes, the plant body is changed unexpectedly: we remove a gene in the Drosophila antenna and these will not form, or they will be created improperly. In this way we can change at will (!) The body system of any animal of which we can change the Hox genes.

Hox genes determine addition, the proportions of the various parts of the body, are active in the development of organs, tissues, limbs, skeleton, genitals, etc. ..

As we saw earlier, different animals have different numbers of Hox genes. 2 Hox genes are present in cnidarians, around 4 (but do not yet know well) in Acoelomorpha (remember the previous post on the bilateral symmetry?), 8 the Drosophila and other insects, and 39 we and other mammals.

And if you look carefully, the 39 Hox genes are not our merely modifications of the eight Drosophila Hox genes, as these are a different version of the 4 genes of the Hox Acoelomorpha and so on.

Despite the difference in complexity then, animals have traces of a very strong they are intrinsically linked, as they show us exactly the Hox genes. Probably, mutations and duplications in the kit breeding of animals with a set of Hox genes is still poorly developed, as might be the common ancestor of metazoans, would lead then to develop that complexity (or, if we look at the Hox genes, quel'ordine wonderfully willing) we now come in the animal world. In the previous