European Stars and Stripes (Newspaper) - May 5, 1992, Darmstadt, Hesse                                Unlocking the mysteries fertilization by Boyce Rensberger the Washington Post the Way a sperm gets into an egg scientists have found is rather like the Way a virus infects a cell. It is also like the Way Snake venom acts on blood. Those Are two of the conclusions that have emerged from research on the remarkable ways sperm and egg interact at fertilization. During most of their existences As separate cells the sperm and the egg protect themselves by maintaining Tough outer membranes. And yet when the two meet each readily surrenders to the other. As easily As two soap bubbles pop into one the membranes of egg and sperm fuse and their contents merge launching the embryonic development of a new organism. Generations of researchers have studied the phenomenon of fertilization hoping to learn enough to help couples who wish to prevent it and those who strive against Odds to achieve it. Now scientists in California and Connecticut have discovered a key part of the mechanism. Their work raises the possibility of developing a contraceptive that probably would have no other effect on the Man or the woman than to Block the key molecular linkage that must occur Between sperm and egg before fertilization takes place. The findings Are also said to be a step toward understanding a leading cause of infertility a inability of the sperm to form the link that gains it Access to the egg. What the new research shows is that each sperm carries a special two part apparatus on its surface each part consisting of one protein molecule. One part can recognize a specific receptor molecule on the egg and bind to it. Once this happens the second part of the apparatus is engaged to make the cells join. Exactly How this fusion happens is not Clear but somehow the membranes of the egg and sperm Are opened in a Way spreaders action line when boy meets girl t a a the Union of Sfier and egg is a precisely choreographed event mediated by special protein molecules on the surface of each cell. When sperms reach the egg they release enzymes that break up a surrounding Cloud of escort cells and then soften the egg s jell Lihe coating. The diagram Here begins with the first sperm that has wriggled through the coating to touch the egg s membrane. Okey molecules that cause fertilization Are All Over the egg s membrane and on the Back of the sperm s head. When a sperm penetrates the a is coating its surface proteins find those of the egg. Pm receptor othe Alpha molecule is like one carried by Many viruses to help them invade cells. The shaded portion of the Beta molecule is much the same As a molecule in Snake venom that binds to blood platelets preventing blood clotting. A the sperm s fertilization apparatus consists of two associated molecules called Alpha and Beta. First the Beta part finds and binds to a receptor on the egg. This brings the Alpha part into position to make the membranes fuse. The True shapes of the molecules Are not known yet the diagram is purely schematic. A membranes Are double layers of molecules that stick readily to one another. Membrane fusion shown Here in hypothetical schematic is thought to be used in fertilization and virus invasion of cells. Perfectly controlled that the open Edge of one is sealed to the open Edge of the other. Without spilling anything the contents of both cells Are brought together inside a single membrane. Quot we Are years away from any practical application Quot said Judith m. White who led the research at the University of California at san Francisco and published it in the current nature with Carl p. Blobel tyra g. Wolfsberg and Christoph w. Turck of a Csc and two colleagues at the University of Connecticut. A what s interesting right now though Quot she said Quot is that this mechanism appears to be similar to others in nature. This is a Motif we be heard  for example the protein molecule that makes sperm and egg membranes fuse appears to be similar to the protein that Many viruses carry on their surfaces. The resemblance is Apt because both sperms and viruses Are vehicles for delivering a cargo of genes into a cell. Quot what really surprised us though Quot White said Quot was that we also found a definite relationship to Snake  when the Dan sequence of the second key sperm protein was fed into a computer and compared to All other known Dan sequences Only one proved similar a a component of the venom of pit vipers. The business end of the molecule that binds to the egg receptor is structurally similar to a Snake venom molecule already known to bind to blood platelets preventing them from sticking together to make blood clot. White suspects snakes May have evolved their venom molecule by modifying a copy of their sperm egg binding Gene. Some version of the molecule might someday be made into a medically useful anti coagulant drug. Meanwhile the research has improved understanding of the process of fertilization which is thought to happen something like this an egg comes from the ovary into the fallopian tube a the usual site of fertilization a surrounded by two protective barriers in addition to its the Washington Post membrane. Outside the membrane is a gelatinous coating called the Zona pellucid. And outside that is a mass of Small escort cells. When the first sperms meet the egg they release enzymes that dissolve the Bonds holding the escort cells together. When the Zona is eventually exposed the first of two molecular bindings must take place. On the sperm surface is a protein called ph-20 that binds to proteins in the Zona. Quot the function of ph-20 seems to be to keep the sperm in the Zona pellucid Quot said Diana g. Myles of the University of Connecticut health Center in Farmington a co author of the nature report with Paul Primakoff also at Connecticut. Quot otherwise they would probably just swim  Milos and Primakoff have used this protein to make an experimental contraceptive vaccine that worked in both male and female Guinea pigs. When they injected quantities of the protein into both sexes both developed antibodies that could bind to ph-20.ssb does not qualify for Ira rollover it the military draw Down and the voluntary separation plans and incentives have recently commanded great attention in the Media and Are of interest to Many service members. Under both of the plans a the special separation Benefit and the voluntary separation incentive a the payments Are apparently fully taxable. However under the sub Lump sum payment can the amount received be considered a partial pension distribution the Way the amount is calculated would certainly indicate that it is exactly that. If it can be considered As such can it then be Quot rolled Over Quot into a rollover individual retirement account for example in order to shelter it from taxes if not perhaps that is the reason the sen ices appear to be so Quot generous Quot knowing that it will immediately be Able to collect 25 percent of every payment. Carl m. Johnson Kaiserslautern Germa Nyle Regina m. Deanehan internal Revenue service department of the Treasury Washington replies a rollover is a tax free distribution of Cash or other assets from one retirement plan to another retirement plan. The rollover must be made by the 60th Day after the Date the distribution from a retirement plan is received. To qualify for tax free treatment the distribution must come from a plan that qualifies under provisions of the internal Revenue code such As a pension plan profit sharing plan or an individual retirement account. A voluntary separation payment is not considered to be a distribution from a qualified retirement plan and therefore May not be Quot rolled Over Quot into an Ira. The entire amount of the voluntary separation payment would be taxable in the year  write us readers action line is the readers Quot court of last resort Quot striving to answer some of the questions about life overseas in a military environment or questions about policies and guidelines when other avenues for answers Are not readily available. If you have a question and Don t know where to turn for the answer write to readers action line co the stars and stripes unit 29480, Apo a 09211. All letters must be signed and preference will be Given to those seeking information of general interest to our readers. Page 16 b the stars and stripes tuesday May 5, 1992