Discovery of genes for ginsenoside biosynthesis by analysis of ginseng expressed sequence tags.

Expressed sequence tags (ESTs) provide a valuable tool that can be used to identify genes in secondary metabolite biosynthesis. Ginseng (Panax ginseng C.A Meyer) is a medicinal plant that accumulates ginsenosides in roots. We sequenced 11,636 ESTs from five ginseng libraries in order to create a gene resource for biosynthesis of ginsenosides, which are thought to be the major active component in roots. Only 59% of the ginseng ESTs exhibited significant homology to previously known polypeptide sequences. Stress- and pathogen-response proteins were most abundant in 4-year-old ginseng roots. ESTs involved in ginsenoside biosynthesis were identified by a keyword search of BLASTX results and a domain search of ginseng ESTs. We identified 4 oxidosqualene cyclase candidates involved in the cyclization reaction of 2,3-oxidosqualene, 9 nine cytochrome P450 and 12 glycosyltransferse candidates, which may be involved in modification of the triterpene backbone.

Genetically determined variation in the azygos vein in the mouse.

The normal mouse is expected to have a single and left-sided azygos vein that develops from the paired embryonic cardinal venous system and drains most of the right and left thoracic walls into the left anterior vena cava. During routine autopsies of adult mice, most individuals of the C57BL/6J strain were found to have this pattern but a distribution of different azygos venous patterns was found in the WB/ReJ strain. In WB/ReJ the patterns varied from a single unpaired vein on the right side that connected to the right anterior vena cava through bilaterally symmetrical and paired veins to the expected unpaired vein on the left side. A classification scheme for the observed patterns of azygos veins was developed and the frequency distributions of C57BL/6J and WB/ReJ mice in these classes were compared. The strain difference in the azygos venous system between C57BL/6J and WB/ReJ can be interpreted as a genetically determined threshold trait of development. Beginning with a paired and symmetrical cardinal venous system, the C57BL/6J genotype shifts to a left-sided azygos pattern but the WB/ReJ genotype remains with a more bilateral azygos pattern. Genetic study of this azygos trait will be useful for the study of lateral asymmetries in mammalian development and for the interpretation of venous heterotaxies (anomalous placement of veins) in the mouse that are found in association with mutations such as situs inversus viscerum (iv) and dominant hemimelia (Dh).