Myo-inositol accelerates the metamorphosis from megalopa to crablet of Scylla paramamosain by modulating cuticle decomposition and reconstruction

The mud crab Scylla paramamosain is a key species in China due to its high nutritional value and great economic worth and has grown in popularity.Myo-inositol can modulate versatile physiological functions in aquatic animals.In the present study,S.paramamosain megalopa were given graded concentrations of myo-inositol(0,1,2,4,and 8 ppm)by water immersion to explore how their metamorphosis would be affected.The results showed that supplementing with myo-inositol remarkably increased transformation and survival rate from megalopa to crablet by at least 1.16 and 1.26 times,respectively.To decipher the molecular mechanism of how myo-inositol increases metamorphosis and survival rate,we further performed transcriptome-based gene expression profiling of both megalopa and crablet treated with myo-inositol.The integrative transcriptome analyses predicted that the differentially expressed genes(DEGs)were significantly enriched in chitinase activity,structural constituent of cuticle,and chitin binding,which are associated with the decomposition and reconstruction of cuticle.qPCR results confirmed that myo-inositol mediated gene expression levels of the above cuticle-related pathways.Considering the importance of the cuticle in exoskeleton formation and molting,it can be concluded that myo-inositol-induced changes in the cuticle decomposition and reconstruction might have accelerated the transformation from megalopa to crablet of S.paramamosain.Besides,numerous DEGs were significantly enriched in protein digestion and absorption,amino sugar and nucleotide sugar metabolism.It implies that myo-inositol may improve survival by regulating energy or nutrient absorption.Additionally,the accelerated metamorphosis by myo-inositol may improve survival from megalopa to crablet of S.paramamosain.Overall,this study will provide the first insights into the underlying molecular mechanisms by which myo-inositol increases metamorphosis and survival.

Long-term(42 years)effect of thinning on soil CO_(2)emission in a mixed broadleaved-Korean pine(Pinus koraiensis)forest in Northeast China

Thinning is an important forest management practice that has great potential to influence regional soil carbon storage and dynamics.The present study measured soil respiration(RS,the efflux of CO2 emitted)and its two components(heterotrophic(RH)and autotrophic(RA)respiration)from soil 42 years after thinning in comparison to un-thinning(control).Autotrophic respiration was significantly greater in the thinning plot,approximately 44%higher compared to the control,while both RSand RHwere slightly,but not significantly,higher in the thinning plot.Higher fine root biomass might have contributed to the higher RAin the thinning plot.Both RSand RHshowed clear soil temperature-dependent seasonal patterns,whereas RAwas less responsive to changes in temperature,especially within one specific season.The annual and season-specific temperature sensitivities of RSand RHwere lower in the thinning plot,specifically during the mid-growing season.Furthermore,variations in the season-specific temperature sensitivity of RSand RHwere less intense in the thinning plot.We conclude that forest thinning can reduce the temperature sensitivity of RSand RHduring the mid-growing season and increase soil CO2 emission in the long term.