TALEN-Mediated Gene Editing of slc24a5 (Solute Carrier Family 24, Member 5) in Kawakawa, Euthynnus affinis

Enhancing the color and stress tolerance of cherry shrimp (Neocaridina davidi var. red) using astaxanthin and Bidens Pilosa

This study aimed to evaluate the effects of different concentrations of astaxanthin and Bidens Pilosa compound feed additives on the color and hypoxia tolerance of cherry shrimp (Neocaridina davidi var. red). Color parameters were assessed using CIELAB color space, and differential gene expression related to color and stress was analyzed using reverse transcription quantitative polymerase chain reaction (RT-qPCR) to understand the gene regulatory mechanisms affecting color expression and stability. Over a 56-day rearing period, the feed additives AX100 (astaxanthin 100 mg/kg) and AX100+BP (astaxanthin 100 mg/kg + B. pilosa 5 g/kg) significantly reduced the color difference values compared to the standard sample (ΔE*ab), indicating notable color boosting effects. This included a reduction in lightness (L*), a decrease in color hue angle (h*) with AX100, and an increase in redness (a*) and chroma (C*) with AX100+BP. We further designed 22 color-related gene primers, 16 of which amplified the target fragment. Six gene sets exhibited significant differences among all feed treatment groups and were correlated with color expression. After 9 hours of hypoxic stress, body color remained stable in the feed additive groups, especially in the AX100 + BP and AX200 + BP (astaxanthin 200 mg/kg + B. pilosa 5 g/kg) groups, with color differences before and after hypoxic stress remaining below the discernible threshold of the human eye, indicating optimal color stability. Additionally, the CAT gene, among the stress-related genes that successfully amplified, showed significant differences among feed treatment groups and correlated with color stability based on color difference values. In conclusion, the composite addition of 100 mg/kg astaxanthin and 5 g/kg Bidens pilosa (AX100 + BP) was identified as the most effective treatment. This formulation significantly enhanced cherry shrimp color, evidenced by improved parameters such as decreased lightness and increased redness. Moreover, AX100 + BP demonstrated superior color stability under hypoxic conditions, with ΔE*ab values remaining below the discernible threshold of the human eye, highlighting its potential for maintaining optimal color during transportation. Offering a basis for enhancing the commercial value and reducing the sale risks of cherry shrimp.

Updated Overview of TALEN Construction Systems

Transcription activator-like effector (TALE) nuclease (TALEN) is the second-generation genome editing tool consisting of TALE protein containing customizable DNA-binding repeats and nuclease domain of FokI enzyme. Each DNA-binding repeat recognizes one base of double-strand DNA, and functional TALEN can be created by a simple modular assembly of these repeats. To easily and efficiently assemble the highly repetitive DNA-binding repeat arrays, various construction systems such as Golden Gate assembly, serial ligation, and ligation-independent cloning have been reported. In this chapter, we summarize the updated situation of these systems and publicly available reagents and protocols, enabling optimal selection of best suited systems for every researcher who wants to utilize TALENs in various research fields.

Efficient Artificial Fertilization and Ovulated Egg Preservation in Kawakawa Euthynnus affinis

Artificial fertilization of cultured fish is essential for seed production using breeding techniques. However, in tuna species, the success rate of artificial fertilization is tremendously low. In this study, it was reported that the adequate procedure for ovulated egg collection and storage for artificial fertilization in kawakawa Euthynnus affinis. The collection of ovulated eggs was attempted using new techniques that disrupt only spawning activity without discontinuing ovulation. The available time to use ovulated eggs was also examined by assessing the optimal preservation process and temperature. As a result, artificial fertilization was effectively executed by assessing spawning time and thoroughly extracting ovulated eggs immediately after ovulation, with a success rate of 70% and an ovulation rate of 51.7%. Ovulated eggs could be stored with small quantities of ovarian fluid to sustain fertility. However, fertility was better preserved with Hanks’ solution. Ovulated eggs with high productivity were achieved 3 h after egg extraction when maintained in Hanks’ solution at 20 °C, leading to a supply of one-cell stage embryo for microinjection treatment constantly by continuously executing artificial fertilization. This systematic procedure permitted selective breeding by 1:1 mating between top-quality parental fish and applying several developmental engineering techniques to kawakawa breeding.