Obtaining high-quality nucleic acid extracted from seaweeds is notoriously difficult due to contamination with polysaccharides and polyphenolic compounds after cell disruption. Specific methods need to be employed for RNA isolation in different seaweed species, and therefore studies of the thiamine biosynthesis pathway have been limited. Two selected Malaysian species which are highly abundant and underutilized, namely Gracilaria sp. and Padina sp., representing the red and brown seaweeds, respectively, were collected to develop optimized total RNA extraction methods. Prior to that, DNA was extracted, and amplification of the 18S rRNA gene and the THIC gene (encoding the first enzyme in the pyrimidine branch of the thiamine biosynthesis pathway) from the DNA template was successful in Gracilaria sp. only. RNA was then extracted from both seaweeds using three different existing methods, with some modifications, using cetyltrimethylammonium bromide, guanidine thiocyanate and sodium dodecyl sulphate. Methods I and III proved to be efficient for Padina sp. and Gracilaria sp., respectively, for the extraction of highly purified RNA, with A260/A280 values of 2.0 and 1.8. However, amplification of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase and the THIC gene was successful in only Gracilaria sp. cDNA derived from extracted RNA. Further modifications are required to improve the exploitation of nucleic acids from brown seaweeds, which has been proven to be difficult. This work should pave the way for molecular studies of seaweeds generally and for the elucidation, specifically, of the thiamine biosynthesis pathway.
(1) The effect has been studied of the oral administration of supplementary thiamine on the thiamine content of milk from sixteen women, whose initial thiamine content was low ; and of the parenteral administration of thiamine to ten women, some of whom initially showed mild, clinical symptoms of beriberi.
(2) The response in the milk content of thiamine to supplementary thiamine, administered either orally or by injection, showed marked variation in different women. While comparatively small doses taken by mouth evoked a marked response in some women, fairly large doses administered by injection failed to produce much response in others.
(3) In some women, a marked increase in the thiamine content of their milk occurred soon after the administration of thiamine, either orally or parenterally. In others, the response was slow and meagre.
(4) The highest thiamine level obtained in a sample of milk was 38.9 ug./100 ml., after the injection, twice daily, of 20 mg. thiamine for six days — a total intake of 240 mg. of thiamine parenterally. The initial milk thiamine level in this case was 2.3 ug./100 ml., but had increased to 16.2ug./100 ml., by the supply of a good diet alone, before the course of injections was commenced.
(5) It would appear, that, in cases where the thiamine content of the milk is low, initial parenteral administration of thiamine must be supplemented by a continued intake of additional thiamine, if a satisfactory level of thiamine in the milk is to be maintained.