Hair

The institute's scientists aim to reveal the lines of communication in which the dialogue of the embryonic development takes place, and thus find out who helps the cancerous growth

Flies and humans share quite a few biological systems. For example, the genes that determine the arrangement of the hairs responsible for sensing movement, found on the body of the fruit fly (Drosophila), are similar to the genes in vertebrates that are responsible, among other things, for the arrangement of hair cells in the inner ear. These hairs play a central role in sensing sound waves.

"This surprising connection is due to the fact that nature developed most of the basic genes, necessary for development, only once," says Dr. Lilach Gilboa from the Department of Biological Control at the Weizmann Institute of Science. One use of this similarity is that scientists interested in the causes of certain types of deafness, caused by abnormal development of sensory hairs in the ear, can base their research on information from studies of the development of sensory hairs in flies.

Decoding the genome of the fruit fly, which was completed a few years ago, gave scientists a new and powerful research tool: hundreds of mutant strains of fruit flies, in each of which a different gene was disabled. "Through studies that include about two hundred different strains of mutant flies, we can examine the role of the various genes in the development of the organ being studied - and get an answer within two months," says Dr. Gilboa.

The organ she studies is the ovary of fruit fly larvae. Her research combines advanced methods from the field of genetic engineering with direct observations of cells in their natural environment. These experiments are performed in the living body, and make it possible to observe the effects of genetic changes occurring in certain cells both on the behavior of these cells and on the reaction of their neighboring cells. These studies will allow her to reveal the basic principles governing the normal development of whole organs. From these studies it is possible to reach insights that cannot be obtained through the study of individual cells, because there are biological processes, such as determining the size of cell populations within an organ, which are determined by communication between many cells and not at the level of the individual cell. Her other studies deal with the stem cells in the ovary. The goal of these studies is to better understand how this population of cells is maintained in the ovary. Such an understanding may help, in the future, to improve the effectiveness of medical treatments through stem cell transplantation.

During embryonic development, the cells go through processes of differentiation, during which the cells "specialize" in the activities unique to the various tissues. One of the main questions that preoccupy Dr. Gilboa is related to the incarnations of the embryonic "father cell", through the processes of development and differentiation, to the adult cell. How does one type of cell become another type? And on the other hand, how do embryonic cells manage to maintain the embryonic features, stop the differentiation processes, and prevent their development into sorted cells? During the development of the egg cells, which Dr. Gilboa studies, the parent cells called "primordial germ cells" migrate to special areas in the ovaries, where they become reproductive stem cells. Dr. Gilboa and the members of her research group investigate the differences between these two developmental stages in the life of the reproductive cell.

Although the two types of cells are similar in that they inhibit the differentiation processes, there is a fundamental difference in the way they divide: the primordial germ cells divide symmetrically (that is, create two identical daughter cells), while reproductive stem cells divide asymmetrically, so that one of the two daughter cells that are formed by division differentiates, while the other remains a stem cell. These differences in division properties are determined by the environment in which the two types of cells are found. This environment includes cells that assist the reproductive cells in controlling various aspects of their development - therefore much attention is paid to the development of the assisting cells and the mutual relations between them and the reproductive cells.

How do these helper cells develop? What roles do they play in the life of the developing germ cell? It turns out that the process in which a reproductive stem cell is created involves well-orchestrated teamwork, and Dr. Gilboa monitors the messages that pass between different types of helper cells, as well as between the embryonic cells themselves, which direct their development. Through genetic scanning, Dr. Gilboa was able to identify about 30 genes involved in the development of the ovary. Many of these genes are responsible for cell control that helps reproductive cells in various aspects, including cell division and preventing differentiation.

Defective control of cell differentiation and division is closely related to cancer development. Dr. Gilboa believes that malfunctions in the transmission of messages between the helper cells and the stem cells in the fruit fly ovaries may indicate the causes of the development of cancerous tumors.

Some of the genes identified in the genetic scan have corresponding human genes, which are known to be associated with the development of cancer in various organs. Many of the genes that participate in the processes of normal embryonic development may cause the development of cancer when there is a malfunction in their normal activity, so that the growth of a cancerous tumor can actually be considered as a defective developmental process that is out of control. Cancer cells also have lines of communication with the immediate environment, which cause the environment to support them. Therefore, uncovering the lines of communication responsible for the dialogue that accompanies the normal development process will help scientists understand how certain cells help the cancer grow.

Another question that preoccupies Dr. Gilboa is how the developing larvae maintain a normal supply of primordial germ cells and reproductive stem cells, and regulate their quantity so that it does not exceed the desired number. This question concerns the fundamental principle of every living being - maintaining the internal balance (homeostasis). In her research, Dr. Gilboa identified a repeated feeding mechanism that helps maintain the correct amount of both types of cells. A better understanding of how the amount of different cells is controlled may give researchers clues to solving one of the great mysteries of developmental science - how organ size is determined.

"In addition," says Gilboa, "this understanding may be essential for planning effective treatments using stem cells." To date, scientists have not been able to realize the medical potential of stem cells, and in most cases the transplanted cells die. Dr. Gilboa believes that one of the reasons for this is the mechanisms that regulate the size of the organ and the identity of its cells. If the scientists manage to understand how to "redirect" those mechanisms, they may be able to overcome the barrier, thereby improving the chances of the transplanted stem cells being absorbed by the patient's body.

personal

Dr. Lilach Gilboa was born in Netanya and grew up in Hofit. She always knew she would be involved in science, and chose to study at Tel Aviv University to combine courses in the humanities, in addition to scientific research. She is particularly interested in the history of science, and in her spare time, between managing the laboratory and managing family life, she likes to read books in the field.

After post-doctoral research at the New York University School of Medicine, she returned to Israel and joined, as a senior researcher, the Department of Biological Control at the Weizmann Institute of Science. "The Weizmann Institute of Science allowed me to return to Israel without compromising the level of my scientific research. In the meantime, I am very satisfied - they gave me all the means I needed for research, so its success depends, at the moment, only on me."