Maternal Transfer and Protective Role of the Alternative Complement Components in Zebrafish Danio rerio

Embryos of most fish develop externally and are exposed to an aquatic environment full of potential pathogens, whereas they have little or only limited ability to mount an efficient and protective response. How fish embryos survive pathogenic attacks remains poorly defined. Here we demonstrate that the maternal immunization of female zebrafish with formalin-killed Aeromonas hydrophila causes a significant increase in C3 and Bf contents in the mother, a corresponding rise in the offspring, and induces a remarkable increase in the hemolytic activities in both the mother and offspring. In addition, the embryos derived from the immunized mother are significantly more tolerant to A. hydrophila challenge than those from the unimmunized fish, and blocking C3 and Bf activities by injection of the antibodies against C3 and Bf into the embryos render them more susceptible to A. hydrophila. These results clearly show that the protection of zebrafish embryos against A. hydrophila can be achieved by the maternally-transferred immunity of the complement system operating via the alternative pathway. This appears to be the first report providing in vivo evidences for the protective role of the alternative complement components in the early embryos of zebrafish, paving the way for insights into the in vivo function of other maternally-transferred factors in fish.     

The binding of folyl polyglutamates by hemoglobin

Pteroyl polyglutamates bind to hemoglobin with an affinity which leaves only a minor fraction of red cell folate in the free state. This could serve as a regulating mechanism for protein synthesis in the differentiating erythroblast.     

Effect of paclobutrazol on accumulation of organic acids and total phenols in apple wood

Apple trees (Malus domestica Borkh Spartan grafted on MM 106 rootstock) planted in 1976 in an orchard at Beltsville, Maryland, were treated with paclobutrazol (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-1,2,4-triazol-1-yl-pentan-3-ol) using a foliage spray in 1982 and by trunk banding in 1983. Paclobutrazol did not inhibit shoot growth in 1983; however, shoot growth was significantly retarded in 1984. Increases in organic acids, including succinic, malic, citric, and quinic, and also in total phenols, occurred in wood produced in 1983 on paclobutrazol-treated trees when growth was not inhibited and in wood produced in 1984 when growth was inhibited. The organic acid content of both paclobutrazol-treated and untreated wood tended to decrease from the winter dormant period through growth resumption in the spring. However, the content of total phenols remained nearly the same throughout this sampling period.Mention of a trademark, proprietary product or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.