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Keskin Bekir - One of the best experts on this subject based on the ideXlab platform.

Lingafelter, Steven W. - One of the best experts on this subject based on the ideXlab platform.

Bai Ming - One of the best experts on this subject based on the ideXlab platform.

Yasuyuki Arakane - One of the best experts on this subject based on the ideXlab platform.

  • Cuticle formation and pigmentation in beetles
    Current opinion in insect science, 2016
    Co-Authors: Mi Young Noh, Subbaratnam Muthukrishnan, Karl J. Kramer, Yasuyuki Arakane
    Abstract:

    Adult beetles (Coleoptera) are covered primarily by a hard exoskeleton or cuticle. For example, the beetle Elytron is a cuticle-rich highly modified forewing structure that shields the underlying hindwing and dorsal body surface from a variety of harmful environmental factors by acting as an armor plate. The Elytron comes in a variety of colors and shapes depending on the coleopteran species. As in many other insect species, the cuticular tanning pathway begins with tyrosine and is responsible for production of a variety of melanin-like and other types of pigments. Tanning metabolism involves quinones and quinone methides, which also act as protein cross-linking agents for cuticle sclerotization. Electron microscopic analyses of rigid cuticles of the red flour beetle, Tribolium castaneum, have revealed not only numerous horizontal chitin-protein laminae but also vertically oriented columnar structures called pore canal fibers. This structural architecture together with tyrosine metabolism for cuticle tanning is likely to contribute to the rigidity and coloration of the beetle exoskeleton.

  • Tribolium castaneum RR-1 cuticular protein TcCPR4 is required for formation of pore canals in rigid cuticle.
    PLoS genetics, 2015
    Co-Authors: Mi Young Noh, Subbaratnam Muthukrishnan, Karl J. Kramer, Yasuyuki Arakane
    Abstract:

    Insect cuticle is composed mainly of structural proteins and the polysaccharide chitin. The CPR family is the largest family of cuticle proteins (CPs), which can be further divided into three subgroups based on the presence of one of the three presumptive chitin-binding sequence motifs denoted as Rebers-Riddiford (R&R) consensus sequence motifs RR-1, RR-2 and RR-3. The TcCPR27 protein containing the RR-2 motif is one of the most abundant CPs present both in the horizontal laminae and in vertical pore canals in the procuticle of rigid cuticle found in the Elytron of the red flour beetle, Tribolium castaneum. Depletion of TcCPR27 by RNA interference (RNAi) causes both unorganized laminae and pore canals, resulting in malformation and weakening of the Elytron. In this study, we investigated the function(s) of another CP, TcCPR4, which contains the RR-1 motif and is easily extractable from elytra after RNAi to deplete the level of TcCPR27. Transcript levels of the TcCPR4 gene are dramatically increased in 3 d-old pupae when adult cuticle synthesis begins. Immunohistochemical studies revealed that TcCPR4 protein is present in the rigid cuticles of the dorsal Elytron, ventral abdomen and leg but not in the flexible cuticles of the hindwing and dorsal abdomen of adult T. castaneum. Immunogold labeling and transmission electron microscopic analyses revealed that TcCPR4 is predominantly localized in pore canals and regions around the apical plasma membrane protrusions into the procuticle of rigid adult cuticles. RNAi for TcCPR4 resulted in an abnormal shape of the pore canals with amorphous pore canal fibers (PCFs) in their lumen. These results support the hypothesis that TcCPR4 is required for achieving proper morphology of the vertical pore canals and PCFs that contribute to the assembly of a cuticle that is both lightweight and rigid.

Nabozhenko Maxim - One of the best experts on this subject based on the ideXlab platform.