Development of an efficient bioreactor system for delivering foreign proteins secreted from liver into eggs with a vitellogenin signal in medaka Oryzias latipes

In this study, we developed a novel bioreactor system to deliver and accumulate foreign proteins in eggs using medaka fish Oryzias latipes with the aid of a partial sequence of vitellogenin (Vtg). In teleost fish, Vtg, the hepatically generated precursor of egg yolk proteins, is secreted into the bloodstream and then taken up into eggs. We predicted in silico a probable region (Vtg signal) of Vtg that mediates transportation of proteins from the liver into eggs. Then, we established two transgenic lines expressing the fused proteins including the Vtg signal and each reporter gene, enhanced green fluorescent protein (EGFP) or firefly luciferase (LUC)-fused EGFP, in the liver driven by a liver-specific choriogeninH (chgH) promoter. Each reporter signal was detected from the fertilized eggs spawned by the transgenic females, showing successful transportation of the proteins into the eggs with the Vtg signal. This is the first report demonstrating that the Vtg signal has capability to deliver exogenous proteins into eggs. Because Vtg is a highly conserved protein among most of oviparous organisms, our findings hold promise for establishing bioreactor systems viable in a wide range of organisms.

     

An astacin-like protease, alveolin, is released from cortical vesicles and induces changes in egg envelope proteins during fertilization of medaka (Oryzias latipes) eggs

Upon fertilization, two major protein groups, ZI-1,2 and ZI-3, composing the egg envelope are polymerized to insoluble forms via temporary formation of 132 kDa and 61–62 kDa intermediate proteins. We have shown that an astacin-like protease, `alveolin' is released from cortical vesicles into the perivitelline space after egg activation and induces initiation of the polymerization of egg envelope proteins. To clarify initial reactions of the polymerization, the primary structure of the 132 kDa protein was analyzed.     

Correction to: Comparison of biomass estimates from multiple stratification approaches in a swept area method for Pacific saury Cololabis saira in the western North Pacific

Fisheries Science - A correction to this paper has been published: https://doi.org/10.1007/s12562-021-01506-9     

A technical guide to develop a statistically valid fish-based index in compliance with the water framework directive: an evaluation for Turkish freshwaters

Fish are considered as reliable indicators of environmental quality and during the last decades several fish-based indices have been developed to assess the ecological status of water bodies in compliance with the water framework directive. The high number of fish species with a high degree of endemism, lack of knowledge on ecological requirements of certain fish species, absence of a complete dataset for reference conditions, and great variation among freshwater types complicate the development of fish-based indices for Turkish freshwaters. However, this is still possible using statistical approaches. This paper presents a practical guide which is mainly based on the recent approaches that have frequently been used in other countries worldwide. Data collection, metric selection and scoring, ecological quality ratio (EQR) calculation and validation steps are described and discussed with respect to the limitations and available data for Turkish freshwaters. The guide documented here, with minor adjustments, has a potential to be adopted as a fish-based assessment approach for the ecological status in freshwaters in Turkey and adjacent countries.