The time course of molecular acclimation to seawater in a euryhaline fish

The Arabian pupfish, Aphanius dispar, is a euryhaline fish inhabiting both inland nearly-freshwater desert ponds and highly saline Red Sea coastal lagoons of the Arabian Peninsula. Desert ponds and coastal lagoons, located respectively upstream and at the mouths of dry riverbeds (“wadies”), have been found to potentially become connected during periods of intense rainfall, which could allow the fish to migrate between these different habitats. Flash floods would therefore flush Arabian pupfish out to sea, requiring a rapid acclimation to a greater than 40 ppt change in salinity. To investigate the molecular pathways of salinity acclimation during such events, a Red Sea coastal lagoon and a desert pond population were sampled, with the latter exposed to a rapid increase in water salinity. Changes in branchial gene expression were investigated via genome-wide transcriptome measurements over time from 6 h to 21 days. The two natural populations displayed basal differences in genes related to ion transport, osmoregulation and immune system functions. These mechanisms were also differentially regulated in seawater transferred fish, revealing their crucial role in long-term adaptation. Other processes were only transiently activated shortly after the salinity exposure, including cellular stress response mechanisms, such as molecular chaperone synthesis and apoptosis. Tissue remodelling processes were also identified as transient, but took place later in the timeline, suggesting their importance to long-term acclimation as they likely equip the fish with lasting adaptations to their new environment. The alterations in branchial functional pathways displayed by Arabian pupfish in response to salinity increases are diverse. These reveal a large toolkit of molecular processes important for adaptation to hyperosmolarity that allow for successful colonization to a wide variety of different habitats.

The time course of molecular acclimation to seawater in a euryhaline fish

The Arabian pupfish, Aphanius dispar, is a euryhaline fish inhabiting both inland nearly-freshwater desert ponds and highly saline Red Sea coastal lagoons of the Arabian Peninsula. Red Sea populations have been found to receive migrants from desert ponds that are flushed out to sea during flash floods, requiring rapid acclimation to a greater than 40 ppt change in salinity. To investigate the molecular pathways of salinity acclimation during such colonization events, a Red Sea coastal lagoon and a desert pond population were sampled, with the latter exposed to a rapid increase in water salinity. Changes in branchial gene expression were investigated via genome-wide transcriptome measurements over time from 6 hours to 21 days. The two natural populations displayed basal differences in genes related to ion transport, osmoregulation and immune system functions. These mechanisms were also differentially regulated in seawater transferred fish, revealing their crucial role in long-term adaptation. Other processes were only transiently activated shortly after the salinity exposure, including cellular stress response mechanisms, such as molecular chaperone synthesis and apoptosis. Tissue remodeling processes were also identified as transient, but took place later in the timeline, suggesting their importance to long-term acclimation as they likely equip the fish with lasting adaptations to their new environment. The alterations in branchial functional pathways displayed by Arabian pupfish in response to salinity increases are diverse. These reveal a large toolkit of molecular processes important for adaptation to hyperosmolarity that allow for successful colonization to a wide variety of different habitats.

Effectiveness of Bromelain and Papain Enzymes in Hatching Media with Different Salinity on the Hatching Success of Tilapia (Oreochromis niloticus) Eggs

Tilapia is euryhaline fish which is commonly cultivated in former shrimp ponds, and belongs to mouthbreeders. The purpose of this study was to determine the hatching success of Tilapia eggs outside the mother's mouth, which was carried out in the salinity medium added with bromelain and papain enzymes. The research method was factorial CRD with enzyme (factor A) and salinity (factor B), with three replications. The research was conducted at the Fish Cultivation laboratory of the Faculty of Fisheries and Marine Sciences, Brawijaya University in January-February 2020. The results showed that papain had more effect on hatchability (93.77%), while the salinity of 5 ppt was the salinity that produced the highest hatchability (93.89%). Moreover, the hatchability was also influenced by the interaction between the enzyme and salinity, namely papain enzyme with a salinity of 5 ppt (98.89%). Meanwhile, bromelain had more effect on the survival of larvae (87.86%), and the salinity that produced the highest survival rate was at 5 ppt (85.75%), but the interaction between enzyme and salinity did not have an effect on the survival of larvae.

PROFIL OSMOTIK GELONDONGAN IKAN BANDENG (Chanos chanos Forsskal) SELAMA PROSES KULTIVASI DI TAMBAK BANDENG DESA WONOREJO KABUPATEN KENDAL

Milkfish is euryhaline fish that can live in wide range salinity, so it will affect with osmoregulation processes. This research aimed to examine the osmotic response of milkfish fingerling during cultivation processes in brackishwater ponds at Wonorejo Village district of Kendal. The research was conducted on July-October 2016. The cultivation process of milkfish fingerling has been cultured for 60 days in 2000 m2 brackishwater pond. The initial density of milkfish larvae was 100 individuals /m2 with a lenght size of 10 mm on average and 15 days old. Samples of milkfish fingerling were taken on the 20th, 40th and 60th days, the number of samples was 3 individuals every size. The measurement result of blood osmolarity was 460, 05 to 490.10 mOsm / l H2O higher than media osmolarity 38,98 – 194,5 mOsm/l H2O. The osmotic response of milkfish fingerling were hyperosmotic to the hypotonic environment and osmoregulator fish.