Organic trace minerals improve eggshell quality by improving the eggshell ultrastructure of laying hens during the late laying period

The objective of this study was to investigate the effects of low inclusion levels of organic trace minerals (iron, copper, manganese, and zinc) on performance, eggshell quality, serum hormone levels, and enzyme activities of laying hens during the late laying period. A total of 405 healthy hens (HY-Line White, 50-week-old) were randomly divided into 3 treatments, with 9 replications per treatment and 15 birds per replication. The dietary treatments included a basal diet supplemented with inorganic trace minerals at commercial levels (CON), a basal diet supplemented with inorganic trace minerals at 1/3 commercial levels (ITM), and a basal diet supplemented with proteinated trace minerals at 1/3 commercial levels (TRT). The trial lasted 56 D (8 wk). Compared with the CON group, the ITM group showed decrease in (P < 0.05) egg production, eggshell strength, eggshell palisade layer, palisade layer ratio, serum estrogen, luteinizing hormone, glycosaminoglycan concentration, and carbonic anhydrase activity and increase in (P < 0.05) egg loss and mammillary layer ratio. However, the TRT group almost kept all the indices close to the CON group (P > 0.05). Furthermore, hens fed with low inclusion levels of organic trace minerals had smaller mammillary knobs (P < 0.05) than those in the CON and ITM groups. In conclusion, hens fed with low inclusion levels of proteinated trace minerals had better performance and eggshell strength than those fed with identical levels of inorganic compounds; organic trace minerals improved eggshell quality by improving the eggshell ultrastructure of laying hens during the late laying period.

[HarpinPss elicited early defense responses of tobacco cells and involvement of calcium]

HarpinPss can induce hypersensitive reaction (HR) in tobacco leaves. As superoxide dismutase can inhibit but catalase can not inhibit the development of HR induced by harpinPss, superoxide anion is required for this response. HarpinPss can also induce the release of active oxygen and extracellular alkalinization, two early defence responses in tobacco suspension culture. Diphenylene iodoium, can completely inhibit the induction of HR in tobacco leaves, and the release of active oxygen in the suspension culture system, superoxide anion in these system may be produced by the activation of NADPH oxidase. Ethyleneglycol-bis (beta-aminoethyl) N, N, N'N'-tetraacetic acid (EGTA) can inhibit the development of harpinPss-induced HR and these two early defence responses in suspension culture system. Adding Ca2+ into the medium again, these responses can return to normal level in a short time. Lanthanum chloride, verapamil, neomycin, U-73122, and LiCl can also inhibit these harpinPss-induced responses. Therefore, the influx of Ca2+ mediated by calcium channel and the release of Ca2+ from internal Ca2+ pool may be involved in the two early defense responses induced by harpinPss. Cycloheximide and actinomycin D have no effect on the release of active oxygen but can inhibit harpinPss-induced HR even added them in the intermediate process for inducing HR. It indicates superoxide is just a trigger for HR, and HR is a more complex process that needs the sustained expression of some genes.

[Involvement of anion channel in signal transduction of early defense responses elicited by harpinPss in tobacco]

No matter when anion channel inhibitors, DIDS (4, 4'-diisothiocyanatostilbene-2, 2'-disulfonic acid) and A9C (anthracene-9-carboxylic acid) added (before, at the same time of or after harpinPss treatment), they can inhibit harpinPss-induced hypersensitive response in tobacco seedlings and release of active oxygen and extracellular alkalinization in tobacco suspension cells. DIDS and A9C also inhibit harpinPss-induced Ca2+ influx. In all these cases, DIDS is more efficient than A9C. It is postulated that anion channel positively regulates calcium channel in plasma membrane, and harpinPss may function through signal transduction mediated by anion channel and calcium channel to regulate cellular Ca2+ concentration and defense responses.