SPATIAL AND TEMPORAL EXPRESSION PATTERN OF BOMBYX FORK HEAD SGF-1 GENE IN EMBRYOGENESIS

The embryonic expression of Bombyx fkh/SGF-1 gene has been analysed us ing in situ hybridization and immunohistochemistry. Both transcripts a nd protein were first detected in the most anterior and posterior regi ons at the time of germ anlage formation, and were successively expres sed in the foregut and hindgut at later stages. A weaker expression wa s also detected in the elongated midgut. By the time embryo retraction was finished transcripts and protein were also detectable in the inva ginated whole silk glands, and after the blastokinesis stage the produ cts were restricted to the middle and posterior sill; glands achieving a state required for the SGF-I distribution for later stages. Express ion could also be detected in the central and peripheral nervous syste ms. From these observations, we propose that Bombyx Fkh/SGF-1 may play a pole in organogenesis processes such as those of the gut, silk glan ds, and nervous systems, act as a region specific homeotic gene, and i n spite of clear embryonic developmental differences between Drosophil a and Bombyx, two terminals may be determined by region specific genes such as Bombyx fkh/SGF-1 as opposed to segmental development.