Cuticular sclerotization in insects – A critical review

Sugumaran, Manickam

doi:10.1016/bs.aiip.2022.02.001

Cited by 12 publications

(39 citation statements)

References 259 publications

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“…[23] Cuticle hydration is tightly correlated with its sclerotization level, i.e., the incorporation of catechol derivatives that cross-link the matrix and render it hydrophobic. [24,25,26] To visualize the sclerotization level within the cornea, we used Mallory staining. This histological triple stain is sensitive to sclerotization and is typically used to differentiate between cuticle layers: unsclerotized cuticle (e.g., endocuticle) is stained blue, whereas sclerotization, as found in mesocuticle and muscle attachment sites, leads to intense magenta coloration.…”

Section: Resultsmentioning

confidence: 99%

Gradients of Orientation, Composition, and Hydration of Proteins for Efficient Light Collection by the Cornea of the Horseshoe Crab

et al. 2022

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The lateral eyes of the horseshoe crab, Limulus polyphemus, are the largest compound eyes within recent Arthropoda. The cornea of these eyes contains hundreds of inward projecting elongated cuticular cones and concentrate light onto proximal photoreceptor cells. Although this visual system has been extensively studied before, the precise mechanism allowing vision has remained controversial. Correlating high‐resolution quantitative refractive index (RI) mapping and structural analysis, it is demonstrated how gradients of RI in the cornea stem from structural and compositional gradients in the cornea. In particular, these RI variations result from the chitin‐protein fibers architecture, heterogeneity in protein composition, and bromine doping, as well as spatial variation in water content resulting from matrix cross‐linking on the one hand and cuticle porosity on the other hand. Combining the realistic cornea structure and measured RI gradients with full‐wave optical modeling and ray tracing, it is revealed that the light collection mechanism switches from refraction‐based graded index (GRIN) optics at normal light incidence to combined GRIN and total internal reflection mechanism at high incident angles. The optical properties of the cornea are governed by different mechanisms at different hierarchical levels, demonstrating the remarkable versatility of arthropod cuticle.

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Section: Resultsmentioning

confidence: 99%

Gradients of Orientation, Composition, and Hydration of Proteins for Efficient Light Collection by the Cornea of the Horseshoe Crab

et al. 2022

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“…The slow production of cuticle over the course of several days, however, is surprising, and the adaptive value of a thicker spermathecal wall at this late stage is unknown. Moreover, the process of building up the spermathecal wall does not seem to be correlated with its increasing sclerotization that is the crosslinking of structural proteins and chitin to form hard and coloured cuticles (Sugumaran, 2022). According to Higgins (1983), the sclerotization process in T. clavipes is triggered by mating and is not a function of female age, since she reports that females show sclerotized spermathecae only after mating.…”

Section: Discussionmentioning

confidence: 99%

Sperm storage organs change with female age and mating history in the Golden Silk spider Trichonephila clavipes (Araneae: Araneidae)

Land,

Christenson,

Uhl

2024

Journal of Zoology

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Female sperm storage organs in arthropods are used as taxonomic characters since it is assumed that they do not change after maturation. However, in the Golden Silk spider, Trichonephila clavipes, the shape and sclerotization of the spermathecae change with a mating event. Moreover, mating in T. clavipes consists of several hundred copulations, but the male transfers all sperm during the first insertion of each pedipalp. Given this puzzling mating behaviour, we hypothesize that multiple copulations serve purposes other than sperm transfer and uptake, such as further altering the morphology of the storage site and/or transferring substances other than sperm. We compared virgin female T. clavipes with females after two copulations, one for each spermatheca, and after ad‐libitum mating. Each treatment consisted of two sub‐treatments in which the state of the sperm storage organs was inspected after a short (1–3 days) or a long (11 days) time interval after the female's final moult. The size of the spermathecae increased twofold in all mating treatments compared to virgin females. The thickness of the spermathecal wall increased significantly with time in all treatments similarly. The spermathecal epithelium, which releases secretion into the lumen of the spermathecae, seems most active in virgin females during the time when mating would normally occur and turns less active after mating and with age. The spermathecae contain secretion produced by the female before mating; and after mating, sperm and another secretion transferred by the male. The numerous sperm‐less matings in the ad‐libitum treatment resulted in male secretion in the copulatory ducts of the female genitalia, likely impeding sperm transfer by subsequent males. Out study shows that female genitalia can change considerably after having reached maturity and suggests that sperm‐less matings evolved in the context of sperm competition.

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“…Variation azmong taxa in exoskeleton amino acid content likely relates to different structures and functions of exoskeleton among arthropods (Zhao et al, 2019). Proteins are involved in sclerotization, or hardening, of insect exoskeleton and different proteins with different amino acid balances could contribute to relatively harder versus more flexible exoskeletons (Andersen, 1979(Andersen, , 2010(Andersen, , 2011Sugumaran, 2022;Zhao et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…Some amino acids may be more important for sclerotization than others. For example, tyrosine plays a key role in the initiation of sclerotization through the synthesis of acyldopamine molecules and subsequent localization of quinones (Andersen, 2010;Arakane et al, 2016), and adduction within the chitin matrix then depends on the availability and charge of amino acid side chains and isomers (Andersen, 2008(Andersen, , 2010Sugumaran, 2022). Tyrosine-derived quinones form adducts with exposed histidine, lysine, glycine, alanine isomers, and tyrosine on the surface of cuticular proteins, but the dominant composition and configuration of adducts varies across taxa (Andersen, 2007(Andersen, , 2008Andersen & Roepstorff, 2007).…”

Section: Discussionmentioning

confidence: 99%

Variation among arthropod taxa in the amino acid content of exoskeleton and digestible tissue

Reeves

Herzog

Barnes

et al. 2023

Ecology and Evolution

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Arthropod consumption provides amino acids to invertebrates and vertebrates alike, but not all amino acids in arthropods may be digestible as some are bound in the exoskeleton. Consumers may not be able to digest exoskeleton in significant amounts or avoid it entirely (e.g., extraoral digestion). Hence, measures that do not separate digestible amino acids from those in exoskeleton may not accurately represent the amino acids available to consumers. Additionally, arthropods are taxonomically diverse, and it remains unclear if taxonomic differences also reflect differences in amino acid availability. Thus, we tested: (1) if there were consistent differences in the content and balance of amino acids between the digestible tissue and exoskeleton of arthropods and (2) if arthropod Orders differ in amino acid content and balance. We measured the amino acid content (mg/100 mg dry mass) and balance (mg/100 mg protein) of whole bodies and exoskeleton of a variety of arthropods using acid hydrolysis.Overall, there was higher amino acid content in digestible tissue. There were also significant differences in the amino acid balance of proteins in digestible tissue and exoskeleton. Amino acid content and balance also varied among Orders; digestible tissues of Hemiptera contained more of some essential amino acids than other Orders. These results demonstrate that arthropod taxa vary in amino acid content, which could have implications for prey choice by insectivores. In addition, exoskeleton and digestible tissue content differ in arthropods, which means that whole body amino acid content of an arthropod is not necessarily a predictor of amino acid intake of a predator that feeds on that arthropod.

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Cuticular sclerotization in insects – A critical review

Cited by 12 publications

References 259 publications

Gradients of Orientation, Composition, and Hydration of Proteins for Efficient Light Collection by the Cornea of the Horseshoe Crab

Gradients of Orientation, Composition, and Hydration of Proteins for Efficient Light Collection by the Cornea of the Horseshoe Crab

Sperm storage organs change with female age and mating history in the Golden Silk spider Trichonephila clavipes (Araneae: Araneidae)

Variation among arthropod taxa in the amino acid content of exoskeleton and digestible tissue

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