Analysis of molecular advantages in offspring of large-sized Chinese mitten crabs based on reproductive lineage

This study comprehensively analyzed gene expression differences between offsprings from varying parental sizes in the Chinese mitten crab (Eriocheir sinensis) during two early-life stages (fertilized eggs and megalopae) and corresponding their parental reproductive organs (testes, accessory glands, and ovaries). The mean ± SD (N=30) wet weights for the larger-sized male and female parental groups were 358.93 ± 4.93 g and 255.82 ± 3.45 g, respectively; For the smaller-sized groups were 142.55 ± 4.52 g and 93.97 ± 3.98 g. The findings indicate that offspring developmental advantages are predominantly inherited maternally, while resistance to stress and flavor advantages are primarily passed on from the paternal side.

In detail, it was observed that the ovaries of larger-sized female crabs expressed numerous genes related to hormone synthesis and metabolism, such as CYP15A1 and CYP3A4, which are involved in the biosynthesis and metabolism of juvenile hormones. Moreover, these genes play a crucial role in regulating the molting and metamorphosis processes, as well as the development of certain sensory abilities such as visual and tactile senses in the crabs, thereby aiding offspring in exhibiting superior physiological and structural characteristics during growth and development phases.

In terms of resistance to stress, our research identified that genes associated with oxidoreductase activity, such as ALDH3A2 and PTGR2, were significantly upregulated in the testes and accessory glands of larger-sized male crabs. These genes are involved in key biochemical pathways that defend against external stressors and pathogenic invasions, providing enhanced resistance foundations for the offspring. Additionally, our findings on flavor traits revealed that genes like GLUL and AGXT2, which were involved in lipid, carbohydrate, and amino acid metabolism, were highly expressed in the accessory glands of larger-sized crabs. These genes enhance the crabs' flavor by improving the synthesis and breakdown of key flavor components, contributing to a richer taste profile.

This study systematically explores the potential molecular-level advantages of larger-sized offspring in development, stress resistance, and flavor, comparing these to the molecular characteristics of the reproductive organs and summarizing the genetic patterns that may suggest these advantages.