BIOLOGY: Why Didn’t Darwin Discover Mendel’s Laws?

BIOLOGY: Why Didn’t Darwin Discover Mendel’s Laws?: search feed Darwin’s commitment to quantitative variation as the raw material of evolution meant he could not see the logic of inherita...

BIOLOGY: Why Didn’t Darwin Discover Mendel’s Laws?

BIOLOGY: Why Didn’t Darwin Discover Mendel’s Laws?: search feed Darwin’s commitment to quantitative variation as the raw material of evolution meant he could not see the logic of inherita...

BIOLOGY: Why Didn’t Darwin Discover Mendel’s Laws?

BIOLOGY: Why Didn’t Darwin Discover Mendel’s Laws?: search feed Darwin’s commitment to quantitative variation as the raw material of evolution meant he could not see the logic of inherita...

Genetics is the study of how living things receive common traits from previous generations.

These traits are described by the genetic information carried by a molecule called DNA. The instructions for constructing and operating an organism are contained in the organism's DNA. Every living thing on earth has DNA in its cells. A gene is a hereditary unit consisting of DNA that occupies a spot on a chromosome and determines a characteristic in an organism. Genes are passed on from parent to child and are believed by many to be an important part of what decides looks and behavior. Darwin’s theory of natural selection laid the groundwork for evolutionary theory. However, it was the emergence of the field of genetics, pioneered by Gregor Mendel (1822-1884), that provided the missing information on how evolution works in practice. Mendel’s experiments with peas led him to realise that heredity in sexual reproduction works by the mixing of separate factors, not by the blending of inherited characters. This combination of Darwin's theory and our current understanding of heredity led to the birth of the scientific area called "population genetics.".

Molecular "Motor" Drives Rotavirus Replication

In the May 16 issue of the journal Nature, Baylor's Dr. B.V. Venkataram Prasad and graduate student Hariharan Jayaram and their collaborators for the first time described the atomic structure of this protein that may provide some mechanistic insights into how it either drives viral genome replication or packaging during the assembly of the new viral particles within the cell.

Identifying these kinds of targets that can be used in developing anti-viral drugs may become particularly important in rotavirus since the first vaccine against rotavirus was pulled from the market in late 1999, said Prasad, a professor in the department of biochemistry and molecular biology.

Proteins similar to NSP2 exist in all kinds of double-stranded RNA viruses. They are perhaps the central piece around which the replication machinery of the virus is constructed. That machinery makes one strand of RNA, which provides a template to make a matching strand resulting in the production of the double-strand that contains the virus’ genetic code, he said. That enables the virus to produce many copies of itself that can go on to infect more cells and eventually cause diarrhea. Interfering with the action of a protein like NSP2 could stop the virus in its tracks, said Prasad.

Prasad and Jayaram, of Baylor's program in structural and computational biology and molecular physics, collaborated with Dr. Zenobia Taraporewala and Dr. John T. Patton, of the National Institute of Allergy and Infectious Diseases, on the project.

New path of origin for macrophages

Macrophages play a key role in the immune response, protecting organisms against infection and regulating the development of inflammation in tissue. Macrophages differ depending on where they are located and which tasks they perform. A scientist at TUM has been investigating whether these different types of cells have the same origin – and has come up with some surprising results. His findings reveal that there are two distinct macrophage cell lines that continue into adult life and that these two lineages have different origins. The research was recently published in Science magazine.


The organs of vertebrates, including of course humans and other mammals, are made of a multitude of highly specialized cells that are built by embryonic stem cells. This is also true for cells of the immune system. Until recently, it was thought that all macrophages were created from hematopoietic (blood) stem cells. However, some of these immune cells had also been found to exist in the yolk sac prior to the appearance of stem cells. For a long time, the existence of these extraembryonic macrophages was a puzzle to scientists.

During a sabbatical at King's College in London, Dr. Christian Schulz, internist at the Deutsches Herzzentrum (German Heart Center) of the Technische Universität München, and his research colleagues set about investigating the development of macrophages in mice. To determine the extent to which macrophages can develop independently of embryonic stem cells, the scientists carried out experiments on mice without the "myb" growth factor, which plays an important role in cell growth and is thus crucial to the formation of blood stem cells. "To our surprise, we found that macrophages in the yolk sac also develop without myb. This enabled us to close in on a cell line that can develop independently of stem cells," explains Christian Schulz.