Egg incubation and plasma proteome alterations in response to brood care in maternal crayfish (Procambarus clarkii)

Abstract

Little information is available on differences between maternally and artificially incubated eggs in the economically important crayfish Procambarus clarkii. Brood care in this species is expected to exert effects on the eggs. In this work, we evaluated the hatching rates of artificially incubated eggs, without brood care, compared to those maternally incubated through different development stages. We also examined whether the maternal-offspring connections in ovigerous females were related to embryonic development at the physiological level based on comparative proteomic analysis. The experiments led to two key results. First, hatching rates increased continuously throughout the nine distinct development phases when detaching maternally incubated eggs from the mothers' pleopods individually. Further, a critical period of artificially incubated eggs was observed around the gastrula stage, with the hatching rate ranging from approx. 24% to 45%. Second, blood plasma proteome profiles differed significantly between ovigerous females and aborted females during the gastrula stage (p < 0.05). Of the identified 27 differentially expressed proteins, 23 were significantly up-regulated, whereas four were down-regulated (p < 0.05). Functions of DEPs were linked to the binding, regulation, and immune response, particularly in two strongly expressed PGDH-like and CAT-like proteins (fold-change>3.0). These results suggested that the dynamic changes of plasma proteins in ovigerous females might be related to early isolated egg anti-infectivity and hence affect the hatching success. Yet, the mechanisms behind the encountered relationships need further exploration. In summary, we presented the first evidence of proteomic changes in ovigerous female plasma, revealing that brood care in P. clarkii may include more than physical behavior