Modular cis-regulatory logic of yellow gene expression in silkmoth larvae.

Colour patterns in butterflies and moths are crucial traits for adaptation. Previous investigations have highlighted genes responsible for pigmentation (ie yellow and ebony). However, the mechanisms by which these genes are regulated in lepidopteran insects remain poorly understood. To elucidate this, molecular studies involving dipterans have largely analysed the cis-regulatory regions of pigmentation genes and have revealed cis-regulatory modularity. Here, we used well-developed transgenic techniques in Bombyx mori and demonstrated that cis-regulatory modularity controls tissue-specific expression of the yellow gene. We first identified which body parts are regulated by the yellow gene via black pigmentation. We then isolated three discrete regulatory elements driving tissue-specific gene expression in three regions of B. mori larvae. Finally, we found that there is no apparent sequence conservation of cis-regulatory regions between B. mori and Drosophila melanogaster, and no expression driven by the regulatory regions of one species when introduced into the other species. Therefore, the trans-regulatory landscapes of the yellow gene differ significantly between the two taxa. The results of this study confirm that lepidopteran species use cis-regulatory modules to control gene expression related to pigmentation, and represent a powerful cadre of transgenic tools for studying evolutionary developmental mechanisms.

Relationship between development of fibrosis and hemodynamic changes of the pancreas in dogs.

Studies were conducted to investigate the relationship between development of fibrosis and hemodynamic changes in the pancreas in dogs. The basal blood flow rate in the atrophied, fibrotic pancreas was preserved at almost the same level as in the normal pancreas. Fibrotic pancreas responded to VIP with increased blood flow, but not to administration of secretin. On the other hand, normal pancreas showed a brisk increase of blood flow in response to both of these agents. Our findings suggest that direct arterial acinar blood flow per gram of acini decreases prominently, whereas direct arterial flow to the islets per gram of islet is well maintained after the development of pancreatic fibrosis. It is also suggested that secretin acts indirectly by stimulating metabolic activity of the acinar cells with a secondary increase in blood flow, whereas VIP has a direct effect on the pancreatic vasculature.