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. 相似文献
Soil samples were collected from 7 sites in the up-, mid-and down-reach along and nearby the wastewater irrigation channel, western Shenyang of China. The concentrations of selected pollutants (mineral oil, PAHs - polycycle aromatic hydrocarbons and Cd) were determined by UV spectrometer, HPLC and AAS (atomic adsorption spectrometer) spectrometer, respectively. Toxicity effects of soils were evaluated by seedling emergence test with root length of wheat as the end-point and by earthworms test with the mortality rate and inhibition rates of body weight as endpoints. Results showed accumulation of pollutants for most soils with concentration of 200.2 mg.kg−1∼1600 mg.kg−1 for mineral oil, 0.33 mg.kg−1∼1.81 mg.kg−1 for Cd and 900.16 mg.kg−1 ∼ 2737.91 mg.kg−1 for PAHs. The inhibition rates of root elongation were from −20% up to 40 %, and mortality rates of earthworms ranged from 0%∼40% from the exposure period of two weeks to eight weeks by sampling interval of two weeks, the inhibition rates of earthworm growth were from −19.36% to 34.53%, showing effects of stimulation at 2 weeks to an increasing effects of inhibition at 4, 6 and 8 weeks, respectively. Mortality rates correlated with the loss of body weight of earthworms.
This study indicated the potential risk of pollutants of environmental low content in soil by the determination of selected chemicals combined with toxicity indexes.
The role of Epstein-Barr virus (EBV) early antigen diffuse component (EA-D) and its relationship with EBV DNA polymerase in EBV genome-carrying cells are unclear, EBV-specified DNA polymerase was purified in a sequential manner from Raji cells treated with phorbol-12,13-dibutyrate and n-butyrate by phosphocellulose, DEAE-cellulose, double-stranded DNA-cellulose, and blue Sepharose column chromatography. Four polypeptides with molecular masses of 110,000, 100,000, 55,000, and 49,000 daltons were found to be associated with EBV-specified DNA polymerase activity. A monoclonal antibody which could neutralize the EBV DNA polymerase activity was prepared and found to recognize 55,000- and 49,000-dalton polypeptides. An EA-D monoclonal antibody, R3 (G. R. Pearson, V. Vorman, B. Chase, T. Sculley, M. Hummel, and E. Kieff, J. Virol. 47:183-201, 1983), was also able to recognize these same two polypeptides associated with EBV DNA polymerase activity. It was concluded that EBV EA-D polypeptides, as identified by R3 monoclonal antibody, are critical components of EBV DNA polymerase. 相似文献
Before 1985 some 54 Ordovician agnostidspecies and subspecies had been described fromChina.They were assigned to the following ele-ven genera and subgenera:Geragnostus,Trinodus,Pseudagnostus,Corrugatagnostus,Pseudoperonop-sis,Girvanagnostus,Geragnostella,Peziziopsis,Sphaeragnostus,Leiagnostus and Micragnostus.Most of them were based on inadequate materialand the range of morphological variation in theseforms largely unknown.After comparison,thepresent author tentatively retain 43 of the 54 spe-cies pendingfu rther material becoming available.They are now reassigned to the following ninegenera:Geragnostus,Arthrorhachis,Corrugatag- 相似文献
A new gel filtration method was developed for purification of R-type lipopolysaccharides (lipooligosaccharides) from some nonenteric gram-negative bacteria, including Neisseria meningitidis, Haemophilus influenzae, and Bordetella pertussis. These wild-type lipooligosaccharides are poorly extractable by the phenol-chloroform-ether extraction method of C. Galanos, O. Luderitz, and O. Westphal [1969) Eur. J. Biochem. 9, 245-249) and therefore a new procedure was developed for their isolation. The lipooligosaccharides (LOS) were first extracted by hot phenol-water, treated with RNase, then disaggregated in deoxycholic acid, and purified by gel filtration on Sephadex G-75. By comparison the conventional hot phenol-water purification method using repeated ultracentrifugations yielded less LOS. The yield of LOS by gel filtration was 30 to 108% higher and the purity was better. 相似文献