TO BE OR NOT TO BE VERY LETAL, THAT IS THE QUESTION.

"There is enough in the world for everyone's need, but not enough for everyone's greed". 

Frank Buchman

An example of genetic conflict has been studied in Oryctolagus cuniculus (rabbits) that they are infected with myxomatosis virus, whose virulence level will be important to transfer from one host to another.This virus causes lumps around the head and genitals. It then may progress to acute conjunctivitis and possibly blindness; however, this also may be the first indication of the disease. The rabbits become listless, lose appetite, and develop a fever. 

Secondary bacterial infections occur in most cases which cause pneumonia and purulent inflammation of the lungs. In cases where the rabbit has little or no resistance, death may take place rapidly, often in as little as 48 hours.

When the genetic variability is high and each host is infested by different strains viruses, natural selection will favor the virus that they are able to reproduce more quickly. Rapid proliferation of the virus involves a greater utilization of the resources of the host, causing a negative effect faster and direct about the rabbit, so the competition between viruses within a host selects a greater virulence.

However, if the host dies prematurely and viruses don't have the time required for transmission to other hosts, most of the virus die and the "beneficial" fitness will not proliferate.Thus, natural selection will favor lower virulence levels that allow efficient transmission the virus to other hosts. So, selection individual level favors those who get maximize their reproductive rate, but there would a selection at the group level that favor a decrease in the replication rate because this character makes the virus have a more efficient dispersion to other hosts. 

In conclusion, the virus most efficient are those having average levels of virulence.

Soler, Manuel. "¿A qué nivel actúa la selección natural?" Departamento de biología animal y ecología.    Facultad de Ciencias. Universidad de Granada.

Carlos María Rodríguez López

MYTHS, A PILLAR OF INSPIRATION FOR THE SCIENCE.

Myths are, as everybody knows, stories, tales which relate prodigious events starred by gods, heroes, and monsters, supernatural creatures whose role is to entertain and explain natural events and moral lessons in a simple way.

What not many people know is that these myths are used in some occasions to explain not only magical or supernatural phenomenon, but also scientific facts that can be quantified and proved. This is the case of the Greek myth of Medea and Jason, tale in which Medea, full of hatred against her husband, Jason, ends with the lives of her children in order to prevent them from having descendants.

This bloody and tragic story and, in particular, its leading role, Medea, has been used almost three thousand years after its birth to baptize a curious group of genes, genes Medea (acronym for Maternal Effect Dominant Embryonic Arrest). These selfish genomic elements were discovered in 1992 by the investigators Richard W. Beeman and Michael J. Wade in Yellow Mealworm colonies (Tribolium castaneum), and they supposed a revolution because they were the only deathly maternal genetic factor.

As it has been pointed out, genes Medea follow a type of inheritance known as maternal effect, in which the phenotype of descendants is determined by genotype of the mother due to the present genetic factors in the cytoplasm of the ovule, which have been encoded by maternal genes. This general inheritance scheme, however, turns up a notch in the Yellow Mealworm because the substances that are present in the ovule that have been synthesized by the mother genome act like a “poison” for the descendants causing defects in the development patterns and finally the death, as long as they don´t inherit from any of their parents a copy of this gene Medea, which acts as an antidote erasing the negative effects of maternal factors, which paradoxically have been produced by the same genes. This particular and also destructive inheritance gives away the relation between myth and science, making it clear how genes are the pure representative of the witch Medea, who didn´t hesitate to kill her descendants when she found out theta they were not really her children.

In addition to this singular inheritance pattern, it is important to highlight a feature that we have mentioned before, the double function of genes Medea, which behave as “poison” and “antidote” at the same time. This dualism has a strong functional relevance, since it makes it possible to guarantee the presence of these genes in the following generation, giving expression to the “selfish” character of these elements, which perpetuate although thay don´t provide any selective advantage to their host. In this way, the offspring which comes from a female heterozygote will be carrier of a copy of these genes.

Different investigations of these researchers have observed that this group of genes is not only limited to T. Castaneum colonies, but it can also be found in T. confusum, what have led them to ask about the way of appearance of these elements in the genome; something which is not completely clear yet, making it possible to be a kind of transposon, according to some researchers.

Nowadays genes Medea are, due to their way of inheritance and peculiarities, a line of study to be able to control some diseases transmitted by insects, like malaria or dengue fever.

References:

• Beeman, R.W., Friesen, K. S. , Denell, R. E., 1992. Maternal-Effect Selfish Genes in Flour Beetles. Science vol. 256.
• Beeman, R.W. , Wade, M. J. , 1994. The Population Dynamics of Maternal-Effect Selfish Genes. Genetics Society of America.

Andrés Tabernilla García.