We studied the effect of pH （pH 5, 6, 7 and 8） on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay （BHB）, Artem...We studied the effect of pH （pH 5, 6, 7 and 8） on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay （BHB）, Artemiafranciscana from San Francisco Bay, and A. franciscana artificially produced in salt ponds in Vietnam. The latter was included as a potential inoculum for biological management of salt ponds. The hatching percentage of cysts after 24 h and the survival rate of the tested Artemia strains were significantly reduced when exposed to a culture medium at pH 5 for 18 d （P〈0.05）. The tolerance of Artemia to 48 h acid exposure varied with developmental stage, increasing in the following order： juvenile, nauplii, pre-adult, with maximum tolerance in adults. All strains of Artemia tested could not reproduce at pH 5. At pH levels from pH 6-8, a higher pH generally resulted in a shorter brood interval and enhanced ovoviviparity. Hence, we suggest that brine acidification has a negative impact on Artemia populations in the Bohai Bay saltworks. Inoculation of Artemia with either local parthenogenetic Artemia or exotic A. franeiscana should be feasible at pH 7-8.展开更多
The brine shrimp Artemia is often abundantly found in hypersaline environments.The larvae(‘nauplii’)hatching from its dormant embryos(‘cysts’)are a crucial live food item for the larval stages of fish and shrimp i...The brine shrimp Artemia is often abundantly found in hypersaline environments.The larvae(‘nauplii’)hatching from its dormant embryos(‘cysts’)are a crucial live food item for the larval stages of fish and shrimp in aquaculture展开更多
Vibrio anguillarum, an important bacterial fish pathogen, expresses a variety of virulence factors contributing to its ability to cause vibriosis in fish. Many virulence factors of this pathogen remain however unknown...Vibrio anguillarum, an important bacterial fish pathogen, expresses a variety of virulence factors contributing to its ability to cause vibriosis in fish. Many virulence factors of this pathogen remain however unknown. For example, a type IV pilus system was previously reported to be potentially involved in the virulence of this bacterium but no experimental evidence was reported yet. In this study, complete genome sequencing of V. anguillarum strain VIB15, shown to be highly virulent towards sea bass (Dicen- trarchus labrax L.) larvae, revealed the presence of a PilA pilin. A V. anguillarum VIB15 pilA mutant was constructed and the pathogenicity of this mutant was assessed in a gnotobiotic sea bass system developed for virulence screening. Our results suggest that the V. anguillarum pilA gene is not crucial for virulence towards sea bass larvae. Possibly, another type IV pilus system identified in V. anguillarum, showing homology to the mannose-sensitive hemagglutinin pilin of Vibrio cholerae, may complement the pilA mutation. Alternatively, the type IV pilus system has a role in infection of juvenile or adult fish, rather than in the larval phase. As such, further research is required to unravel the potential role of type IV pili in V. anguillarum virulence.展开更多
基金Supported by the International Cooperation Research Program of the Ministry of Science&Technology of China(No.2010DFA32300)the Pilot Project for International Cooperation"Aquaculture in Hebei and Shandong Provinces"funded by the Province of East-Flanders,Belgiumthe Nature Science Foundation of Tianjin(No.13JCZDJC28700)
文摘We studied the effect of pH （pH 5, 6, 7 and 8） on the hatching percentage, survival and reproduction of Artemia strains in Bohai Bay salt ponds. Strains included parthenogenetic Artemia from Bohai Bay （BHB）, Artemiafranciscana from San Francisco Bay, and A. franciscana artificially produced in salt ponds in Vietnam. The latter was included as a potential inoculum for biological management of salt ponds. The hatching percentage of cysts after 24 h and the survival rate of the tested Artemia strains were significantly reduced when exposed to a culture medium at pH 5 for 18 d （P〈0.05）. The tolerance of Artemia to 48 h acid exposure varied with developmental stage, increasing in the following order： juvenile, nauplii, pre-adult, with maximum tolerance in adults. All strains of Artemia tested could not reproduce at pH 5. At pH levels from pH 6-8, a higher pH generally resulted in a shorter brood interval and enhanced ovoviviparity. Hence, we suggest that brine acidification has a negative impact on Artemia populations in the Bohai Bay saltworks. Inoculation of Artemia with either local parthenogenetic Artemia or exotic A. franeiscana should be feasible at pH 7-8.
文摘The brine shrimp Artemia is often abundantly found in hypersaline environments.The larvae(‘nauplii’)hatching from its dormant embryos(‘cysts’)are a crucial live food item for the larval stages of fish and shrimp in aquaculture
文摘Vibrio anguillarum, an important bacterial fish pathogen, expresses a variety of virulence factors contributing to its ability to cause vibriosis in fish. Many virulence factors of this pathogen remain however unknown. For example, a type IV pilus system was previously reported to be potentially involved in the virulence of this bacterium but no experimental evidence was reported yet. In this study, complete genome sequencing of V. anguillarum strain VIB15, shown to be highly virulent towards sea bass (Dicen- trarchus labrax L.) larvae, revealed the presence of a PilA pilin. A V. anguillarum VIB15 pilA mutant was constructed and the pathogenicity of this mutant was assessed in a gnotobiotic sea bass system developed for virulence screening. Our results suggest that the V. anguillarum pilA gene is not crucial for virulence towards sea bass larvae. Possibly, another type IV pilus system identified in V. anguillarum, showing homology to the mannose-sensitive hemagglutinin pilin of Vibrio cholerae, may complement the pilA mutation. Alternatively, the type IV pilus system has a role in infection of juvenile or adult fish, rather than in the larval phase. As such, further research is required to unravel the potential role of type IV pili in V. anguillarum virulence.
