4.3 Desiccation-adaptive mechanisms of C. japonica
Comparative genomics can provide insights into the unique adaptive
plasticity of marine species (Han et al., 2021; Xu et al., 2021). In the
present study, we hypothesized the adaptive mechanisms of desiccation
tolerance based on comparative genomics. Previous studies suggested that
crustaceans may continuously undergo the double stress of dehydration
and hypoxia in a drought environment. Specifically, desiccation disrupts
the internal osmotic pressure and metabolic capacity of crustaceans
(Haupt et al., 2006; Carlson and Rowe, 2009). Moreover, desiccation can
reduce the oxygen-binding ability of hemoglobin and result in hypoxic
stress in crustaceans (Omori et al., 1998; Allen et al., 2012). The
prolonged disruption of the respiratory mechanism may further impair the
immune function of crustaceans and eventually lead to death (Madenjian
et al., 1987). Additionally, the activity of the antioxidant enzyme
system directly determines the desiccation tolerance of crustaceans
(Jiang et al., 2014). Based on the annotation information, the
desiccation-adaptive mechanisms ofC.
japonica was supported by the marked expansion of gene families or the
positive selection of genes related to metabolism rate, oxygen supply,
oxidative stress, and various transporters.