Structure Response of Preadsorbed Saliva Pellicle to the Interaction between Dairy and Saliva Protein.

Using the surface characterization techniques of quartz crystal microbalance with dissipation, atomic force microscopy, and scanning electron microscopy, the structure of the salivary pellicle was investigated before and after it was exposed to dairy proteins, including micellar casein, skim milk, whey protein isolate (WPI), and a mixture of skim milk and WPI. We have shown that the hydration, viscoelasticity, and adsorbed proteinaceous mass of a preadsorbed salivary pellicle on a PDMS surface are greatly affected by the type of dairy protein. After interaction with whey protein, the preadsorbed saliva pellicle becomes softer. However, exposure of the saliva pellicle to micellar casein causes the pellicle to partially collapse, which results in a thinner and more rigid surface layer. This structure change correlates with the measured lubrication behavior when the saliva pellicle is exposed to dairy proteins. While previous studies suggest that whey protein is the main component in milk to interact with salivary proteins, our study indicates interactions with casein are more important. The knowledge gained here provides insights into the mechanisms by which different components of dairy foods and beverages contribute to mouthfeel and texture perception, as well as influence oral hygiene.

Plants impact cellular immunity of caterpillars to an entomovirus.

BACKGROUND: Tri-trophic interactions among plants, insect herbivores and entomopathogens are one of the hot topics in ecology. Although plants have been shown to impact the interactions between herbivores and entomopathogens, it is still unclear how plants affect the cellular immunity of herbivores to entomopathogens. RESULTS: The number of hemocytes and the proportion of two main cell types (granular hemocytes and plasmatocytes), plasmatocyte-spreading rate, apoptosis rate, two Spodoptera exigua caspase (SeCasp-1, SeCasp-5) activities and gene expressions were all higher and the activities and gene expression of S. exigua inhibitor of apoptosis protein (SeIAP) were lower in nucleopolyhedrovirus (NPV)-infected caterpillars fed Ipomoea aquatica than those fed other plants or artificial diet. Scanning electron microscopy images were consistent with molecular patterns of immune responses. CONCLUSION: This study suggests that host plants affect the immune responses of herbivores to entomopathogens by manipulating the composition, morphology and apoptosis of herbivore hemocytes, which sheds light on the mechanisms that allow host plants to influence multi-trophic interactions. © 2021 Society of Chemical Industry.