Transient expression of lacZ in particle bombarded Gracilaria changii (Gracilariales, Rhodophyta)

Using a Biolistic PDS 1000/He system, healthy thalli of Gracilaria changii were bombarded with gold particles coated with plasmid DNA containing the lacZ reporter gene. Transient expression of lacZ was observed in bombarded thalli under the rupture-disc pressures of 4482, 6206, 7584 and 8963 KPa, two days after bombardment. Although G. changii exhibits a slight blue background, positive expression and the background colour can be clearly differentiated. The results indicate that lacZ could be a useful reporter gene and that SV40 promoter could be an effective promoter for Gracilaria transformation.

A simple method is presented for obtaining a large number of monospores in the thallus of Porphyra yezoensis. The method implies two principles: induction of monosporangium formation by allantoin, and liberation of monospores from the cell wall by mild homogenization. The induction of monosporangium formation was accomplished by culturing wild thalli in nutrient-enriched seawater with 10 mM of allantoin for approximately 3 weeks. This high concentration (10 mM) of allantoin suppressed the growth of the thalli compared with lower concentrations (0-1 mM). Thalli cultured for 3 weeks were mildly homogenized with a glass homogenizer and the monospore solution was obtained by filtering with a nylon mesh. The monospores grew normally to thalli. This technique of monospore acquisition is a simple and useful method for the propagation and breeding of P. yezoensis thalli.