In zebrafish, ovulated oocytes contain both maternal cortisol and the mRNA for the glucocorticoid receptor (gr), which is spread as granular structures throughout the ooplasm. At 0.2 hpf, this transcript is relocated in the blastodisc area and partitioned among blastomeres. At 6–8 hpf, it is replaced by zygotic transcript. We used morpholinos to block translation of both maternal and zygotic gr transcripts, and a missplicing morpholino to block post-transcriptionally the zygotic transcript alone. Only knockdown of translation produced an increase of apoptosis and subsequent craniofacial and caudal deformities with severe malformations of neural, vascular, and visceral organs in embryos and 5-dpf larvae. Such defects were rescued with trout gr2 mRNA. Microarray analysis revealed that 114 and 37 highly expressed transcripts were up- and down-regulated, respectively, by maternal Gr protein deficiency in 5-hpf embryos. These results indicate that the maternal gr transcript and protein participate in the maternal programming of zebrafish development. Developmental Dynamics 240:874–889, 2011.

Antimicrobials are commonly used to prevent and treat disease in the ornamental fish industry. However, the indiscriminate and comprehensive overuse of unregulated antimicrobials without appropriate diagnostic examination could contribute to the development of antimicrobial-resistant strains of bacterial pathogens. Moreover, human infections caused by pathogens transmitted from fish or the aquatic environment are quite common. The frequent detection of antimicrobial resistance in ornamental fish and their environments are inevitable so as to decrease the transfer of antimicrobial-resistant bacteria from aquatic sources to other environments. This study evaluated the prevalence of common bacteria species and the antimicrobial susceptibility profile in ornamental fish that were sold in an ornamental fish shop in Chiang Mai, Thailand. Aeromonas spp. were the most dominant of the isolated species from the ornamental fish samples and accounted for 68.09% of the total. Other species detected included Vibrio spp., Pseudomonas spp., and Citrobacter spp. A high percentage of resistance to amoxicillin (93.75%), oxytetracycline (79.69%), and erythromycin (75.00%) was observed among the Aeromonas spp. The antimicrobial resistance information for ornamental fish is very limited, and the results from this study indicate that the Aeromonas spp. are highly resistant to several important antibiotics. The results suggest that additional steps should be taken to educate store owners to reduce the indiscriminate use of these antibiotics to decrease the antimicrobial resistance in ornamental fish to potentially improve public health.