What was going on when I was born?

Federal regulators, in a move to reduce the losses of the two Federal deposit insurance funds, voted tentatively today to limit the availability of insurance on deposits placed by brokers, but ran into unexpected - and potentially fatal - opposition from the Treasury Department. Although the target of the curb appears to be the growing corps of financial middlemen known as money brokers, Wall Street executives said that the action, if it becomes final, would make it all but impossible for stockbrokers to offer their customers federally insured money market accounts. In separate but coordinated actions, both the Federal Deposit Insurance Corporation and the Federal Home Loan Bank Board proposed regulations that, if made final, would deny insurance to deposits in excess of $100,000 placed by any broker at any one insured bank or savings association. The bank board manages the Federal Savings and Loan Insurance Corporation, which insures deposits at savings associations.

The simple little sea urchin with its bristly coat is providing important new insights into one of nature's best-kept secrets: how a single fertilized egg cell gives rise to the millions of specialized cells that compose an adult organism. Using advanced techniques of molecular biology, scientists have recently learned, to their surprise, that in terms of the diversity of genetic information actually put into action, a ''simple'' fertilized egg is far more complex than any cell in the adult animal. This probably holds true for human beings as well as sea urchins, they believe. Moreover, genetic products inherited through the egg - and therefore from the mother alone - exert powerful control over embryonic development. Biologists have also observed, for the first time, that some genes turn on rapidly as an embryo develops, other genes turn off slowly and some continue to be used throughout embryonic life. Thus, the patterns of gene activity that underlie the building of the embryo are complex and of more kinds than one.

In the last four days the nation's nuclear energy industry has been rocked by what many analysts say are two stunning and potentially destructive precedents. First, a nuclear power plant was scrapped nearer to completion and with more money invested in it than ever before. Second, the Federal Government for the first time denied a utility permission to operate a newly completed nuclear plant. Last Friday, a Federal Nuclear Regulatory Commission licensing board told the Commonwealth Edison Company that it could not operate the nearly completed $3.35 billion Byron Nuclear Power Station near Rockford, Ill., because of inadequate quality controls during its construction.

France announced today that it had reached an arms sales agreement of about $4.5 billion to provide Saudi Arabia a mobile system of antiaircraft missiles for the protection of its oilfields and other important ground installations. The order, worth nearly 40 billion francs, is the largest France hasever received from an arms customer, the Government said. Far larger was the $8.5 billion American sale of Awacs radar planes to Saudi Arabia, which was approved by the Senate in 1981. The order for the French air defense system was signed Jan. 11 by Defense Minister Charles Hernu and his Saudi counterpart, Prince Sultan, after a year and a half of negotiations.

WITH a national debate now raging over the quality of American education, high schools in New York City have developed an ''Academic Index'' to measure educational excellence through an objective formula. The index rates individual schools on the basis of such factors as the number of students who take and pass Regents Examinations and the number who take difficult courses in basic academic subjects. ''Numbers drive a school system, and the index is a way to rate schools,'' said Aaron N. Maloff, the Senior Superintendent for High School Curriculum and Instruction, who developed the system. ''More important, it is a diagnostic tool that focuses clearly on the components of a school and helps it to become better.'' The new approach differs from the usual method of judging schools by the performance of their students on standardized tests. Mr. Maloff said the new technique could be readily adapted by any school system ''with access to an external test such as the Regents Examinations.''

A new investment vehicle, tried previously with only limited success, is now being offered to the holders of Exxon and General Motors stock. The Americus Shareowner Service Corporation said yesterday that it has filed, with the Securities and Exchange Commission, proposals to establish two unit trusts, one for Exxon Corporation shares and one for shares of the General Motors Corporation. Each trust will have 10 million units and will allow holders to, in effect, divide Exxon and G.M. shares into conservative and speculative components. Holders will be able to exchange their common shares, on a one-for-one basis, for a trust unit of the respective company. There is a sales charge for the transaction.

They are the consummate image- makers. From soap flakes to Presidential candidates, advertising agencies have sold it all, with ever-increasing sophistication. Yet until lately, Madison Avenue had an image problem on Wall Street. The stocks of the agencies were considered unreliable. Assets went up and down as accounts shifted from one shop to another, and employees came and went along with the accounts. Financial management had a reputation of being weak.

The Marble Hill nuclear plant is being abandoned because of a huge rise in costs, Public Service of Indiana announced. The half- completed project, on which $2.5 billion has already been spent, is the costliest ever dropped. (Page A1.) The abandonment of Marble Hill, together with Friday's denial of an operating license to the Byron plant near Rockford, Ill., has stunned the nuclear energy industry. (D1.) Many other nuclear power plant projects around the country are in trouble as well. (D17.) Mobil sought an I.R.S. opinion on a plan to gain big tax savings by setting up a special company, or royalty trust, whose shares would go to stockholders. Oil industry officials said the move, if approved, may be emulated by other major oil companies, and is likely to cause wide concern in Congress. (D1.)

Secretary of State George P. Shultz said today that United States efforts to work out a political settlement in Lebanon with the Syrians had failed so far. In a news conference in London before flying here this morning, Mr. Shultz was asked for an appraisal of the long talks the United States special envoy, Donald Rumsfeld, held Friday with President Hafez al-Assad of Syria. Until today American officials had declined to discuss the Rumsfeld mission publicly. Mr. Shultz said bluntly, ''As of now, i

Victor Posner, the financier, yesterday proposed a leveraged buyout of the Royal Crown Companies at $40 a share in cash, only hours after the company announced an agreement with its own managers to take it private at $37 a share. The actions were the latest in a running battle between Royal Crown's management and Mr. Posner, who owns 27 percent of the Atlanta-based company, one of the last small, independent soft-drink makers. Mr. Posner said his offer to Royal Crown's shareholders is contingent on the cancellation of a sale of two million preferred shares by the company to the management group. The group, which already owned 18 percent of the company, bought the preferred shares yesterday for $10 million, or about $5 a share. The shares carry three votes apiece, giving the management group voting control of the company. Typically, preferred shares have no voting power.

Because of poor management, many employees do not work a full day in the subway car maintenance and cleaning shops of the Metropolitan Transportation Authority, the M.T.A. inspector general said in a report issued yesterday. The inspector general, Sidney Schwartz, who is independent of the authority and reports to the Governor's office, based his findings on unannounced visits last fall to facilities of the Transit Authority, the Long Island Rail Road and the Staten Island Rapid Transit Operating Authority. In one case, the report said, nearly half the shop's employees stopped working two hours early. In another, the report said, only one member of a seven-member crew was working.

The Public Service Company of Indiana announced yesterday that it was abandoning a half-finished nuclear power plant on which $2.5 billion has already been spent. It said it had to give up the project, known as Marble Hill, because of an overwhelming increase in costs and a lack of money to finish construction. This is the most expensive nuclear project ever to be abandoned. It is also the most serious setback for the troubled nuclear power industry, which has seen more than 100 plant cancellations in recent years, since the accident at Three Mile Island near Harrisburg, Pa., in March 1979.