Texas Gas Resources Corp. said yesterday that it has set up a special trust to isolate a barge-owning subsidiary from the rest of the company to enable CSX Corp. to acquire Texas Gas without prior approval of the Interstate Commerce Commission.

CSX, the giant Richmond-based railroad, has made a friendly offer of $52 a share for Texas Gas stock in an effort to prevent a hostile, $45-a-share bid by Coastal Corp.

Because the ICC must approve a railroad's acquisition of any water carrier, Texas Gas had to isolate the barge-owning subsidiary in a special "voting trust agreeement" from CSX control should CSX win the bidding war.

BRL SIGNS DEAL: Bethesda Research Laboratories Inc. has signed an agreement calling for a merger of the Gaithersburg-based genetic engineering supply firm into a subsidiary of Dexter Corp. of Windsor, Conn., the two companies announced yesterday, completing a transaction that had been expected for several months.

Under a reorganization plan that was approved as part of the agreement, BRL will be merged into Gibco Corp., a supplier of special products for biotechnology research. The merger agreement includes plans for a public offering, but Dexter will continue to own between 50 and 55 percent of the new company.

The agreement is subject to, among other things, approval by the shareholders of BRL at a meeting in late July.

Dexter Corp. is a Fortune 500 company that produces specialty materials. Founded in 1776, it is the oldest company listed on the New York Stock Exchange.