We are able to insert the gene directly into the immature gonads. Using a small, sharp knife, Chen makes a small hole in the exoskeleton of an immature crayfish near its thorax, where the testes and ovaries are located. The new gene then appears in the eggs or sperm, making injection unnecessary. Chen's past efforts have included transferring genes in finfish and mollusks. In an earlier project sponsored by Maryland Sea Grant, Chen and Yonathan Zohar, University of Maryland Center for Marine Biotechnology director, cloned genes for striped bass gonadotropin releasing hormone, a hormone that regulates reproduction in this fish.
Genetic engineering is by no means limited to animals.
Don Cheney, Northeastern University biology associate professor, and Subash Minocha, University of New Hampshire plant biology professor, have both been working on genetic manipulation in macroalgae. Minocha says there is much yet to be accomplished in genetic engineering for the algae, as the practice is in its infancy. His lab has succeeded in using an electric shock technique to transplant a bacterial gene into two species of algae, Porphyra and Ulva spp., both consumed as food. Cheney has used bioengineering techniques such as protoplast fusion to induce genetic variation in several seaweeds, including nori, thereby developing new strains. His lab was successful in producing a fast-growing polyploid strain of Porphyra, which is excellent for growing nori on nets.