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February 24th, 2011

Zamuro Negro

Arleene Fabrega Conte/ Wildlife and Bird Hazard / Technical Cooperation Project ICAO/AAC

Aeleene Fabrega Conte discovered the presence of a Black vulture (Coragyps atratus) showing a deformity or alteration in its peak. She presumes that the cause of this genetic malformation is the result of the environmental contamination which is being investigated in that area.

The contamination

The contamination consists, basically, in the generation of waste in an environment that exceeds the disposal capacity. Therefore, it is not a matter of what products are introduced, but the quantity. The proliferation of these wastes is a serious imbalance in the biological system, to such an extent, that could make impossible life of existing species. Water, air and soil are the main environments contaminated.

The Water

Water is a scarce resource, but essential for society and nature, since all living beings are constituted, in a higher percentage, of water. Of all the water in the planet, only a small part is usable for society and greatest part of nature.
Water is a resource which provides energy and life. The peculiar form of human life in large cities, short of water, and production techniques are large consumers of water, requiring the creation of large infrastructure such as dams and water distribution pipes, both air and groundwater. Even, water can be transferred between river basins.
From all available, an 80% of water is used in irrigated agriculture, which is slightly contaminated, depending on the chemical fertilizers that have been used. A 14% of water is used by the industry, which is highly contaminated. And the remaining 6% is used by the city, which is also heavily contaminated once it has been used. Regularly, part of the available water is lost because of bad pipes. You can lose up to 40% of damming.
The water in the cities and industries, and in some cases in agriculture, is contaminated by hard degradable products, such as oils or detergents. These products are discharged into rivers, thus decreasing the proportion of oxygen. Some products may act directly as poison for some species that live in the water, or use it, is the case of mercury and other heavy metals contamination. These products are deposited in the soil, through the water, and become part of the food chain and human consumption.
Pollutants reach other areas through the rivers. Due to the size of contamination whole seas has been seriously harmed, endangering its ecological balance as well as their environment and the entire planet.

The Air

Air pollution is very easy. The real problem begins with the massive use of fossil fuels and the automotive industry. Cities are places where concentrations of pollutant particles are particularly high, together with large industrial centers. The winds pattern expands particles around the globe, but it is in the industrialized countries where higher incidence of air pollution is found. These particles (CO2, SO2) are precipitated, mixed with rain water, forming hydrochloric and sulfuric acid, and giving rise to acid rain, which have pernicious effects on biocoenosis, by providing water not suitable for living beings consumption. The consequences of air pollution on global climate are to be determined, for if, on one hand, it seems that it reduces the brightness of the sun, and on the other hand, appears to increase the greenhouse effect. The series of studies in this regard are still too short to reach to definitive conclusions, although it appears to point to the effect of global climate warming. Or at least, if it is not the cause it seems to accelerate the process.

The Soil

Land use is another feature of human intervention in the environment, as from the provision of space for their exclusive use, as well as cities, industry, communications or agriculture, to its general degradation through colloidal contamination by acid rain or use of nitrogenous chemical fertilizers in agriculture.
In agriculture, the cultivation of a single species makes almost lose the nutrients which are necessary for its growth, and also hinder the development of other species, thus decreasing the variety of plants.
In addition, deforestation and fires favor the loss of soil, especially if it is inherited from ancient ecological conditions, in an unrecoverable way. Soil erosion, which is subjected by the disappearance of vegetation cover is widespread throughout the world, but especially in the ecological traffic regions.
The society, in conclusion, impacts on the landscape, transforming and changing its operation to obtain the necessary resources to allow economic development, but without stripping the environment until its disappearance. The way and speed with which those resources are extracted is causing the imbalance.
The Contamination with chemical particles and heavy metals from air and water makes mutations of up to 60% more than usual, affecting DNA.

BIOACCUMULATION

For many years, humans have used substances or chemical compositions for pest control, but in recent times pesticides-also known as pesticides or biocides, have achieved a high degree of efficiency, most of them as a result of chemical synthesis.
In this section you will find the necessary information to know the importance of the use of pesticides, their effects on health and its impact on environment and bioaccumulation processes as well as alternatives to reduce their use. With the increasing demand for food to serve a human population that multiplies rapidly, pesticides have been reported undeniable benefits. Health also has been benefited by them. It would be hard to imagine the modern world without pesticides that had kept under control the Anopheles or Aedes mosquito, that transmit malaria, yellow fever and dengue.
Not even think about having food if the screw-worm or locust could not be controlled by biocides.
Apart from being used for our benefit, biocides have had other applications. In the last wars some countries have used herbicides in order to remove the leaves of plants covering jungles and forests of the combat zones, thereby facilitating the location of the 'enemies'. The result was that significant areas of forests in Vietnam or in the former Yugoslavia were lost.
Herbicides have another application:  eliminate the herbs in farmlands that compete for the soil and the nutrients with the cultivated plants. However, they are difficult to implement and their effects can not be taken under strict control and can damage the other plants.
As a result of significant technology development in the synthesis of these insecticides, they can be used almost anywhere, by anyone and at not very high prices. This has led to a widespread use and we will describe the adverse effects that have caused.
Among the most common pesticides are insecticides. The best known are DDT (dichlorodiphenyltrichloroethane) and Dieldrin. Although its use has been banned in some industrialized nations, the third world uses them abundantly, and our country occupies an important place.

1. They kill more organisms of other species than those that want to fight.
2. After several applications, they select damaged species, leaving only the strongest and resilient, therefore after a time they seem ineffective because the species they want to attack is not sensitive to this insecticide.
3. By decreasing the effectiveness of an insecticide, there is a tendency to use it in larger quantities and thus increase its contamination effects.
 4. Kill predators or natural enemies of the pest you want to exterminate, what makes the ecosystems become unbalanced and remove the only organisms capable of fighting the scourge without contaminating the environment.
5. Pest natural 'enemies' are always fewer in number than them, and when attacked by pesticides, tend to disappear quickly.
6. The most effective pesticides are generally very stable, i.e. they do not degrade easily or quickly in the environment. Thus, persist in the environment long periods of time and its effects are also long-term.
7. They can not be metabolized and, conversely, being fat soluble, are stored in adipose tissue of many other organisms producing what is known as "biological expansion" or "bioaccumulation".

A mutation is an alteration or change in the genetic information of a living being and therefore it will produce a change in one or more characteristics that occur suddenly and spontaneously and can be transmitted, inherited, or none of them, to descendants. The genetic unit that is able to mutate is the gene, which is the unit of hereditary information that is part of DNA.

Mutations

Concept
Types of mutations: genetic, structural and numerical.
Lethal genes
Biological significance of mutations
Natural and artificial selection
Through meiosis, there will be variability in a population. The variability can be continuous when changes are smooth or discontinuous when the change is abrupt, with no intermediate phenotypes, these are mutations.
The mutations affect the genotype and are therefore heritable. Lead to measurable variations in the characteristics of a species. This definition was given by Hugo de Vrier in 1901.

Mutations are important because they will form a basis of the evolutionary process. There are three types of mutations: chromosome, genomic or karyotypic and genetic.

Chromosomal mutations
Take place when the number of chromosomes changes or when structural changes occur in the chromosomes. They can be:

Deletions: loss of a piece of chromosome. This can be lethal in homozygosity, because it involves the loss of many genes.

Duplication: is a chromosome segment that appears repeatedly. Duplication is usually done in tandem (by couples). This tandem repeat supports many possibilities, an inverse repeat, displaced or both.

Translocation: the fragment of a chromosome attaches to another non homologous chromosome. If it joins to a homologous it would cause a recombination.

Inversion: a fragment of the chromosome changes direction within the same chromosome. This may cross over the centromere.

Genomic or karyotype mutations

They are changes in the number of chromosomes, which are typical of the species. Such mutations are also called chromosomal aberrations or variations. There are two types:

Polyploidy: the haploid chromosome number is repeated more than twice. This occurs when there is no meiosis. Individuals with an odd number of chromosomes will be sterile.
Polyploidy is more common in plants than in animals, in addition it is usually good for plants, because this allows getting varieties that are much more productive or resistant.

Aneuploidy: has a spare chromosome or a chromosome is missing in the species chromosome set. In meiosis, a pair of homologous chromosomes won’t separate and thus we have an extra chromosome (trisomy) in a series and one less chromosome in the other (monosomy).

Trisomy Disorders

Down syndrome or mongolism: is accompanied by a mental and physical retardation and this is because the individual has 47 chromosomes. Extra chromosome appears in pair 21. It occurs in a 0.15% of the population and when pregnant women are over 40 years the possibility increases to 1 or 2%.

Klinefelter syndrome:  affects only males. Has a frequency of 0.2%. Affect sex chromosomes. The individual has 44 autosomes and will be XXY. It's going to be male, but sterile, has mammary glands, small testes and not a very proportional skeletal development.

Duplo Y or XYY syndrome: it is a variant of the Klinefelter syndrome. Males are XYY and are characterized by being very violent.

Monosomy

Turner Syndrome:  Women with 45 chromosomes. They are X0. Have one X chromosome instead of the usual two sex chromosomes. This syndrome has low frequency in the general population.

Gene Mutation

Is a permanent change in the DNA sequence that makes up a gene. These changes are not observable.
A gene mutation is called a mutant and this is transmitted to the next generation. The parental gene is a wild-type. These mutations have very low frequency of occurrence, but vary according to species.

There are three types of mutations:

Regressive: produces negative effects or even death. Example:  lethal genes in the homozygous states.
Progressive: produces a positive effect.
Silent: they are neither positive nor negative.

In a haplont, mutations are always expressed.

The mutations are important in cancer research, because a cell may mutate into a single base and become cancerous. Not only the substitution of a base, but also the deletion or insertion of a new base, because if the sequence changes the proteins that are synthesized are different in the three cases.
Natural selection and the environment will determine that a favorable mutation remains, since it would eliminate the less fit .
Humans use artificial selection. This consists in selecting individuals with desirable characteristics.
Para aumentar la frecuencia de mutación de un gen existen los agentes mutagénicos lo que hacen es cambiar la composición química de los nucleótidos o provocar un mal funcionamiento de los procesos enzimáticos. Pueden ser:
To increase the frequency of a gene mutation of a gene mutagenesis exist they do is change the chemical composition of nucleotides or cause a malfunction of enzymatic processes. Can be:
The Mutagenic Agents increase the frequency of a gene mutation. They change the chemical composition of nucleotides or cause a malfunction of enzymatic processes. These agents can be:

Environmental:  temperature, age ...
Chemicals: nitrous acid, acrinina, formaldehyde.
Radiation: ultraviolet (thymine dimers), X-rays,, cathode ...

With these agents we can cause experimental mutations, which are often harmful. They are also used in genetic engineering, because we can modify genes.

Biological significance of mutations

Evolution
Mutations are one of the evolutionary mechanisms. Their existence require the prior existence of variability among individuals in a population, which is the evolutionary unit (species evolves, not individuals)
The variability is obtained with recombination and mutations, which are going to allow the appearance of new genes. When doing it, we increase the biological phantom for the evolution.
Beneficial mutations are usually inadvertent at a first moment but will be noted very slowly by natural selection. The mutated gene will be replacing the wild-type gene.
Evolutionarily the most important mutations are those that act repeatedly on a same gene, favoring them with faster changes.
The importance is shown during the adaptation of a species to new surroundings.

There are cases in which the selective pressure is big , therefore will favor the survival of those individuals that have that mutation because they will adapt much better.

Artificial selection
A characteristic lasts in a species because humans decide, but by natural selection that mutation would disappear. Due to genetic engineering, humans can induce the evolution in any sense.