*Health scan: Small worm could explain human fertilization*

The results of the Israeli-French research will be useful in understanding processes such as fertilization or the formation of muscle fibers.

By JUDY SIEGEL-ITZKOVICH
Photograph of cells 370 (photo credit: (Hebrew University)
Photograph of cells 370
(photo credit: (Hebrew University)
Ten years of research on the tiny roundworm has resulted in Israeli-French research that solved for the first time the structure of a protein responsible for “cell-cell fusion.” The discoveries, recently published in the scientific journal Cell, will be useful for future research designed to understand processes such as fertilization or the formation of muscle fibers.
Scientists from Haifa’s Technion-Israel Institute of Technology and the Pasteur Institute in France have discovered the atomic structure of a protein present on the cell surface and responsible for the fusion process, as well as the mechanism that allows this melding to occur. Prof. Benjamin Podbilewicz from the Technion’s Shulich faculty of fiology, in collaboration with Prof. Félix Rey from the Pasteur Institute, focused their research on the EFF-1 protein from a tiny roundworm known as Caenorhabditis elegans, which serves as a convenient research model for a variety of biological processes.
“The atomic structure of this protein (but not the sequence) in the roundworm is similar to that of proteins that do the same thing – membrane fusion – in enveloped viruses,” explained Podbilewicz. He describes the way in which an enveloped virus penetrates the body: “The cell ‘swallows’ it and then the membrane of the virus fuses with the membrane of the organelle [specialized lipid-enveloped structure within a living cell that swallowed it]. As a result, the genetic material of the virus enters the cell and assumes control over it.”
“We also discovered the differences by which the viral protein fuses with the cell membrane, and the way the EFF-1 protein carries out this process,” added Podbilewicz.
“The viral protein, which has no partner in the targeted cells, must do all the work on its own and is endowed with a unique mechanism for this purpose. Conversely, when the roundworm cells fuse with each other, each cell expresses its fusion proteins on the surface. Here, the fusion proteins (EFF-1) of both cells ‘hug’ each other and create a kind of zipper connecting the cells together.”
The discoveries, they said, will have implications for research aimed at understanding cell-cell fusion processes in the human body. These processes play a critical role in fertilization (the fusion between sperm and ovum) and in developmental processes taking place in organs such as in muscle and bone.
GENE MUTATION MAKES IT RISKIER TO EAT SALAMI
A common genetic variant that affects one in three people apparently increases significantly the risk of colorectal cancer from the consumption of processed meat, according to study just published in PLOS Genetics. The study of over 18,000 people from North America, Australia and Europe represents the first large-scale genome-wide analysis of genetic variants and dietary patterns that may help explain more of the risk factors for colorectal cancer.
Dr. Jane Figueiredo at the Keck School of Medicine of the University of Southern California explained that eating processed meat is associated with an increased risk of colorectal cancer. For a third of the general population who carry this genetic variant, the risk of eating processed meat is even higher than those who do not.
The study population totaled 9,287 patients with colorectal cancer and a control group of similar size who did not have cancer. Scientists systematically searched 2.7 million mutations to identify those that are associated with the consumption of meat, fiber, fruits and vegetables. A significant interaction between the genetic variant rs4143094 and processed meat consumption was detected. This variant is located on the same chromosome 10 region that includes GATA3, a transcription factor gene previously linked to several forms of cancer.
Colorectal cancer is a multi-factorial disease attributed to both genetic causes and lifestyle factors, including diet. About 30 known genetic susceptibility alleles for colorectal cancer have been pinpointed throughout the genome. How specific foods affect the activities of genes has not been established but represents an important area of research for prevention.
“The possibility that genetic variants may modify an individual’s risk for disease based on diet has not been thoroughly investigated but represents an important new insight into disease development,” said lead study statistician Dr. Li Hsu. “Diet is a modifiable