Milk fat globule-EGF factor 8 (MFG-E8) is a divalent-binding secretory protein possessing an Arg-Gly-Asp (RGD) motif and a phosphatidylserine (PS)-binding motif. This protein has been shown to be involved in mammary gland development and morphogenesis. Integrin-binding activity is necessary for these MFG-E8-dependent cell processes. Although the target cells and molecules of MFG-E8 in the cellular microenvironment are important to understand its physiological function, its localization is largely unclear. Here, we found that mouse MFG-E8 localized to the basal lamina of the mammary gland during involution. In a model system of mammary COMMA-1D cells, exogenously and endogenously expressed MFG-E8 was deposited in the extracellular matrix (ECM) with membranous particles dependently on the PS-binding motifs in the discoidin domains that were essential for association ability to extracellular vesicles (EVs). These data showed the basal MFG-E8 localization mechanism in which EVs served as a scaffold. Such an immobilized MFG-E8 associating with cell substrata but not soluble one in the culture media promoted integrin-dependent suppression of β-casein expression. These results suggest that MFG-E8 requires EVs to transduce cellular signals from the basolateral side of the adhesion cells by accumulating in ECM.

In order to analyze the capturing mechanism of pot traps, fish behavior was observed in and around a trap using an underwater TV system. The behavior pattern was classified as follows: (1) ap pearing in the camera view, (2) swimming towards the entrance, (3) entering inside the funnel, (4) eat ing the bait, (5) going backward foward the funnel, (6) passing through the inner opening, (7) swim ming out of the camera view. During the 1,150 min of observed period, total numbers of appearances were 131 times, enter ing inside the funnel 57 times and capture 3 times, respectively. The puffer swan backward from the funnel by paddling the pectral fins foward the snout of the fish. The capturing mechanism of the fish trap seemed to be affected by the freedom of swimming behavior of puffer fish inside of the funnel.