Figure 4.

Composition of related gene expression in the B. schroederi cuticle

A. Diagram model of the transverse section through the midbody of B. schroederi. B. Cuticle of B. schroederi is magnified from (A) to illustrate its structure and biosynthesis. The cuticle includes the surface coat (I), epicuticle (II), and the cortical (III), medial (VI), and basal layers (V), and its composition is mostly made up of collagens and cuticlins. Cuticlins are enzymatically polymerized to constrict the seam cell-derived cuticle and form the distinctive cuticular alae, which are predominant in the outermost cortical layers; while collagens are synthesized through a multistep process that includes prolyl 4-hydroxylation, procollagen registration and trimerization, transport from the endoplasmic reticulum, and procollagen processing and cross-linking, which results in construction of the major component of the extracellular matrix of the epicuticle and the cortical, medial, and basal layers of the nematode cuticle. Transcriptome analysis showed significantly (corrected P value ≤ 0.05; fold change ≥ 2) differential expression of the genes involved in the biosynthesis of cuticle collagens and cuticlins during the development of B. schroederi. For expression levels of genes related to biosynthesis of collagens, the four color boxes from left to right representing four stages (Egg, L2, L5, and Adult) were used to indicate expression levels, with pink and cyan indicating high and low deviation from the consensus profile, respectively.