Popular words: strongest Idol Mermaid most cattle series avian flu symptoms
From the appearance, the people in general are symmetrical, obviously, this kind of symmetry should be aesthetic appearance of a necessary condition, however, this kind of symmetry, didn't do it inside and out, because people offal is not symmetrical. Such as heart, liver, and other distribution in the body of one side, while at the same time distribution in lung though, but still left on both sides of asymmetric, only the kidney, ovarian, and so few organs in General is the symmetrical distribution. This asymmetry is what?
If you are considering starting from fertilized eggs during development, then the issue becomes all the more strange. Because the Zygote itself is a completely symmetrical spherical body and then it symmetrically divided into two successive divisions to form a spherical cell aggregates. So when the embryo in its appearance remain symmetrical, its internal began to appear around the asymmetry of? the asymmetry of the mechanism also?
To get the answer to this question, the only step by step back embryonic development from a single fertilized eggs, to the emergence of asymmetric shape. As in the original Zygote Division stage, keep progeny cells are consistent, that is, the child cells either form, structure, or components, in particular contain the proteins are the same. We know that life's basic feature widget is protein, if there is a difference between the two cells, then contain the protein must have type differences. While a cell which contains protein, simply by its corresponding gene contains DNA sequence information is cell protein processing reading internal, and then translated into a protein's amino acid sequence information, which ultimately makes gene expression and production. So the difference between proteins must be derived from the differences in gene expression, that is, if two offspring cells, they are the expression of genes, will lead to its protein factories production of proteins, thus determining their structural and functional differences emerged.
Obviously, for a start up global symmetry of embryos, sure there exists a crucial developmental steps so that the descendants of the fetal left cell, gene expression differences, thereby further makes the whole embryo occurs around of morphological and structural asymmetry. Therefore, to study the problem in a way, is from early embryos is still at the beginning of the period left-symmetric, monitoring of left and right sides of cells used to assemble the protein mRNA sequence and the corresponding protein products, and see when the variance, then allows find causes this difference is what is the source of the gene.
Now researchers have found that some genes, they are only one side of the early embryo was valid expression, and then they are encoded proteins can act as a key signaling molecule that induced the edge of the embryonic growth out of its symmetric position different morphological structure. Researchers in the chicken embryo development process, discovered the first asymmetric shh expression of genes, encoding a protein expression is a very important signal protein molecules. Subsequently, also in chicken embryos inside found another seven genes that are involved in the chicken embryo development of non-symmetric. Progress is more important, the eight genes and their encoded proteins are closely related, we can say that their role is part of the buckle. And chicken embryo development of asymmetric is composed of a series of genes and their encoded proteins interact and control results.
Researchers through human intervention these genes to start the program, you can effectively change the location of the cardiac growth or direction.
In addition, there are other more genes are involved in the development of non-symmetric.
In addition to chicken, in other vertebrate body is a similar asymmetry growth control mechanism? now researchers in mice and amphibians of embryonic development, have found a similar mechanism of asymmetric developmental regulation. Therefore, we should be able to estimate, such a mechanism must also exist in humans.
However, even if we have been able to go back to the genes that are still only partially answered the question. If Inquisitor ask so, earliest gene expression of non-symmetric and who commands under? we hardly know what is what determines the heart have to grow on the left.
Recommended articles: most Visual impact of life
Fun, television and video in 25 of the most
Intel's fear in the heart of the vibrant heart of China
Paul · Allenby Gates will spend money
A mysterious vanishing treasure (map)
No comments:
Post a Comment