Galactose-1-phosphate uridylyltransferase (GALT) catalyzes the reversible conversion of glucose-1-phosphate and UDP-galactose to galactose-1-phosphate and UDP-glucose. This enzyme is also responsible for one of the biochemical steps that produce the precursors of agar and agarose. In this study, we report the molecular cloning and sequence analyses of a cDNA encoding GALT, from Gracilaria changii (B. M. Xia et I. A. Abbott) I. A. Abbott, J. Zhang et B. M. Xia, which constitutes a genus of seaweeds that supply more than 60% of the world's agar and agarose. We have subcloned this cDNA into a bacterial expression cloning vector and characterized the enzyme activities of its recombinant proteins in vitro. The GcGALT gene was shown to be up-regulated by salinity stresses. The abundance of transcripts encoding GcGALT was the highest in G. changii, followed by Gracilaria edulis and Gracilaria salicornia in a descending order, corresponding to their respective agar contents. Our findings indicated that GALT could be one of the components that determines the agar yield in Gracilaria species.
A 46 day old female Chinese infant was referred for fail-ure to thrive, jaundice, hepatomegaly and bilateral cataracts. She had vomiting,blood stained stools and severe unconjugated hyperbilirubinaemia soon after birth. The jaundice persisted. At one month of age, pale stools, firm hepatomegaly and bilateral cataracts were noted. Radionuclide hepatobiliary scintigraphy per-formed at another hospital excluded biliary atresia. Investigations showed cholestasis but a negative sero-logical screening for congenital infections. A presump-tive diagnosis of galactosaemia was made and the infant was started on lactose free formula. A deficient red blood cell galactose- 1 -phosphate uridyltransferase (GALT) activity was demonstrated later. Review eight months after the initial diagnosis showed a thriving infant with no jaundice, but persisting cataracts and firm enlarged liver. A high index of clinical suspicion, labo-ratory confirmation of a deficient GALT activity and prompt withdrawal of lactose from diet are necessary to avoid any delay in diagnosis and management of this condition.