• Cloned Genetic Code 



Could Mean Year-Round Soft-Shell 

 Crab Dinners 



Soft-shell crabs, a popular seafood 

 delicacy, might soon be more than just 

 a spring and summer treat. A team of 

 Mississippi-Alabama Sea Grant 

 researchers has successfully cloned 

 the genetic code for the blue crab's 

 molt-inhibiting hormone (MIH). 

 Decreased MIH levels trigger the 

 crabs molting process. Crabs molt, or 

 shed their shells, to grow. For a few 

 hours after shedding, the crustaceans 

 are soft and can be eaten whole. 



The results have the potential to 

 revolutionize the soft-shell crab 

 industry. To date, the industry has been 

 seasonal and limited by the availability 

 of harvesting crabs in the molt stage. 

 Forcing crabs to molt on command 

 could produce an abundant, year-round 

 and controllable supply of soft-shell 

 crabs for the seafood industry and 

 consumers. 



First, the researchers built a high- 

 tech genetic library of cloned DNA 

 material. Then they successfully cloned 

 the MIH gene material. By replicating 

 the material, the scientists can begin 

 experimenting with ways to block the 

 release of MIH in the crab, thus 

 allowing it to molt. 



To successfully clone large 

 quantities of MIH cheaply and effi- 

 ciently, researchers have inserted MIH- 

 gene codes into insect cells to take 

 advantage of their DNA replicating 

 machinery. Using this biotechnology 

 research, crab shedders may soon be 

 able to molt crabs on demand, rocketing 

 the soft-shell industry. 



• Volkswagen Bug Takes 

 a Dive for Science 



A gleaming white 1969 

 Volkswagen Beetle was deliberately 

 dropped beneath the waves of Lake Erie 

 in June to prove a point. When the car is 

 pulled from the lake bottom in late fall, 

 it should have a new exterior — a thick 



coat of zebra mussels. The encrusted 

 car will then become a major museum 

 exhibit that demonstrates the cata- 

 strophic effects of this nonnative 

 species in the Great Lakes. 



The American Museum of Natural 

 History in New York City will show- 

 case the car in an exhibit on endangered 

 and introduced species to open in 

 March. Project organizers anticipate 

 that the "Bug" will be covered in zebra 

 mussel colonies an inch and a half 

 thick. Ohio Sea Grant scientists and 

 researchers at Ohio State University's 

 Stone Laboratory will film and docu- 

 ment the car's transformation in the 

 coming months. 



The zebra mussel is an example of 

 a nonindigenous species with no 

 effective predators. Since first appear- 

 ing in Lake St. Clair in 1986, the 

 mollusks have spread into 19 U.S. 

 states. They have clogged navigation 

 systems, water treatment and industrial 

 plants and marinas as far north as 

 Canada's Hudson Bay and as far south 

 as the Gulf of Mexico. 



• Measuring the Health 

 of Coastal Ecosystems 



A University of Delaware Sea 

 Grant researcher has developed a new 

 sensor — a solid-state gold amalgam 



microelectrode — that scientists can 

 insert into marine waters and sediments 

 to simultaneously measure dissolved 

 oxygen, iron, manganese, hydrogen 

 sulfide and iodine. The concentrations 

 of these highly reactive chemicals and 

 metals can serve as indicators of the 

 environmental health of salt marshes, 

 harbors, bays and other marine habitats. 



Microelectrodes are not new to the 

 scientific community. But previously 

 these needlelike sensors could charac- 

 terize only gaseous compounds, and 

 typically only one gas could be mea- 

 sured per electrode. In addition to its 

 ability to measure a number of chemi- 

 cals and metals simultaneously, the 

 microelectrode can perform its analyses 

 to the submillimeter level. 



The glass-encased device contains 

 a gold wire plated with mercury. When 

 the probe is inserted into salt marsh 

 sediments, the chemicals in the sedi- 

 ments react with the mercury, creating 

 a current directly proportional to the 

 chemicals' concentrations. An attached 

 monitor records the readings. 



The scientist also hopes to test the 

 sensor's use on a remotely operated 

 vehicle, which could further minimize 

 disruption to the environment during 

 sampling while maximizing the quality 

 of the data gathered. □ 



COASTWATCH 25 



