Back ground knowledge

The mutation breeder is a fancier who dirived his often profound knowlegde from praxis. Articles about genetics in the bird magazine are skipped because they are just theory. Sometimes it is useful for mutation breeder to have some background knowledge of genetics. I tried to write some pages without usage of jargon. For whom how is interested in the basics of this hobby, who want to know what a mutation really is and how changed attributes are transferred to the next generation, more information is given in this pages.

Developing of new colour varieties The mutation breeder is busy in a field, that world wide is taken interest in. This is caused by the discovering of DNA. The mutation breeder is directly in terms with processes, that are increasing the variability in the bird species. Today there are about thirty different colour varieties of one species: the Bourke. Without the activity of fancier there would be only one colour variety, the wildtype. A conservative estimation is that there are about five hundred colour varieties of parakeets and parrots. A number that is increasing every year. One of the processes the fancier is busy with preserving of mutations.

Mutations arise haphazardly. The mutation breeder is caring for the preservation of these mutations. Mostly mutations are not functional. The Bourke has a perfect camouflage suit. Klaus Immelmann writes: "In freedom the Bourke is extremely inconspicuous. He is noticed only when he flies away just before your feet" Imagine that a lutino mutation takes place in the wild. The camouflage pattern on the breast and wings is due to the melanin in the cortex. When this disappears the camouflage is gone. The bright red head and yellow back get the attention of prey birds. Only in captivity this colour variety is preserved. Mr. Van Riet, breeder in Haalsteren (Holland) and many other breeders were preserving this beautiful but not useful colour variety.

This web-site describes processes with regard to one species, the Bourke’s parakeet. But the genetic processes are the same in all bird species, in all living beings, inclusive mankind.


DNA

Mutation as a transformation of the DNA


We speak a lot about mutations, but what is a mutation really? To understand this we have to know what DNA is. In the last decade DNA is in the news several times. Everybody heard or read something about DNA. Par example examination of DNA is used to to find out relation between people. In birds the examination of feathers is used to find out the sex. Every cell of the body is containing DNA. It is possible to find DNA in old bones. Every cell of the body has DNA. (Abbreviation of de oxy ribo nucleic acid). DNA is about microscopic little structures in the kernel of the cell.

When a new house is build a contractor works together with an architect. These architect makes a project plan, a document with sketches and designs. This project of a new house is part of the planning phase. Then comes the realisation phase. When the new project plan is controlled and approved the contractor is working with of a lot of building designs, full of details. These contractor cares for the realisation of the job with all kind of skilled labourers, bricklayers, carpenters, electricians and house painters. They all get a copy of their part of the plan. He is co-ordinating and controlling the buildings process. But the skilled labourers are building the house. They are using raw materials like wood, bricks and cement. They are realising the plan. Others are supervisors to inspect the building activities


DNA, a construction plan for an organism

We can look upon DNA as an information packet. This information packet is situated in the kernel of the cell.
This contains all the information what is necessary to develop an organism systematically. This information is used to ‘build a new house” or for the“ upkeep and renovation”.

How we can imagine such a design, such an information packet? DNA we can imagine as a rope ladder with many steps. This rope ladder is twisted like a telephone cord, to long to tidy away and therefore winded like a spiral. See fig.1. A rope ladder has number of steps. Every step is brought to view in fig. 1 as three horizontal lines.

The same ladder is brought to view in figure 2 more schematic. Every line (fig.1) is a code of two characters. These form a pair (fig.2). A-T, T-A, G-C, C-G, are some of these pairs. Together three of this code pairs are forming a step of the ladder. The letters are forming a fixed pair. Three pairs are forming a gene.


The characters used are not chosen at random. They are the abbreviations of four chemicals. Amino acids. A = Adenine, T = Thymine, G = Guanine and C = Cytosine. The characters are forming regular pairs. For instance C-G or G-C. In fig.2 there are vertical stripes on both sides. These represent the ropes of the ladder.

In fact these are ribosomes. This ribosomes form the structure of the ladder and his strength But they have a very important other function. They play an important role in making copies of the information. This is needed when the organism grow but also in maintaining and repairing.
The whole DNA ladder is immense long , millions of code pairs, but is so narrow, we can't imagine. The DNA ladder is rolled up in the kernel of a cell. The very complicated three-dimensional structure of the DNA was discovered when scans were made with the newest kinds of electron microscope.


Chromosomes, parts of the building plan

The whole DNA ladder is divided in parts. These are the chromosomes. Chromosomes are the recognisable parts of the total DNA ladder. There are parts of this ladder, in between the chromosomes, what are seen as junk, rubbish. It is not clear of this parts are containing useful information.
Chromosomes are the important designs of the organism. Every chromosome is divided in a number of genes.


Genes

Together the three pairs of characters are forming a gene. This genes are carriers of the genetic characteristics. Each gene or a combination of genes determines a genetic quality. In a bird species, in every living organism. Every gene has his own place on the chromosome. Biologists are trying to find out the place of a genetic quality. They want to localise the place (locus) This they do to study faults in the DNA. The lutino Bourke, born in Halsterern has a DNA fault. The inheritance of the lutino was sex-linked. So the fault was to be found at the sex-chromosome.

Every gene has three letter pairs. In one gene three mutations can take place. Not more.

Summary: The DNA is a grandiose design of live, applied to a specific species. It is an information packet for the development of this species. The DNA is divided in chromosomes. These are sub divided in genes. These are build up by three pairs of characters.
To the whole information packet only four different characters are used. The development plan of all living creatures, the DNA, is composed by only four characters, and can held maximum 64 (4 x 4 x 4) different combinations


Building up an organism

When a house is to be build materials are needed. Concrete, bricks, wood and other building materials. An organism needs chemicals for growth and functioning. Some are found in the diet, some are made in the organism itself. The labour is done by proteins.

In the lessons of biology we learned that there are three important materials. This are the building materials of the bird also :


1. Albumen (proteins) for the building of bone structures and feathers, and the regulation of the different processes in the organism. Some examples are: keratin ( building material of feathers), tyrosinase ( production of black and brown pigment), haemoglobin ( transport of the oxygen in the blood)
2. Carbon hydroxide for energy
3. Fat for storing of energy and cell membrane

Proteins are very important for the major subjects of this web-site, the growth of feathers, the colouring of the plumage. In the DNA the information is stored needed to build the proteins. Carbon hydroxide and fat are not made in the body, but taken from the food and worked up. The albumen (proteins) are made in the organism and are very specific for this organism. Because they are specific, it is possible to sort out the relation between bird species. Biochemical research is one of the methods. On the base of this kind of research they studied the relationship between bird species. They found that the Bourke and the Neophema are not related.

Mutations: Change of a gene means change of a part of the information packet, the DNA. Because of this the original plan and the execution of the plan is changed.

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Copyright 2004 by Bob Fregeres

E-mail: fregeres@bourkes-parakeet.nl

1/8/04