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  • Küçük Resim
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    Characterization of tongue worm (Pentastomida) chitin supports ?- rather than ?-chitin
    (Elsevier GmbH, 2019) Greven, Hartmut; Kaya, Murat; Junker, Kerstin; Akyüz, Lalehan; Amemiya, Chris T.
    The higher order relationships of the Pentastomida have historically been tenuous. In one early and influential study, analysis of extracted chitin implicated that pentastomids possess ?-chitin, a paradoxical finding given that the ? allomorph is found uniformly in the cuticles of all arthropods and is considered as an apomorphic character of the Ecdysozoa. This result was further used to support the idea that the enigmatic pentastomids might be a wholly independent clade. More recent studies, however, firmly place the pentastomids within the Ecdysozoa, suggesting that the state of its chitin should be re-examined. In this study, we extracted high-quality chitin from the pentastomid, Leiperia cincinnalis, and carried out diagnostic analyses. Fourier Transform Infrared Spectroscopy (FT-IR) and ThermoGravimetric Analysis (TGA) demonstrated the conspicuous features of ?-chitin but not ?-chitin. Furthermore, transmission electron microscopy (TEM) of the cuticle of the anterior part of a specimen revealed nanofibres organized largely in a parallel configuration and scanning electron microscopy (SEM) of isolated cuticular chitin exhibited well-defined chitin bundles, these observations being more consistent with the known characteristics of ?-chitin. Collectively, our analyses demonstrate the clear existence of ?-chitin in a pentastomid and clarify a contentious issue using modern methods of analysis.
  • Küçük Resim
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    On chemistry of ?-chitin
    (ELSEVIER SCI, 2017) Kaya, Murat; Mujtaba, Muhammad; Ehrlich, Hermann; Salaberria, Asier; Baran, Talat; Amemiya, Chris T.; Galli, Roberta; Akyüz, Lalehan
    The biological material, chitin, is present in nature in three allomorphic forms: alpha, beta and gamma. Whereas most studies have dealt with alpha- and beta-chitin, only few investigations have focused on gamma-chitin, whose structural and physicochemical properties have not been well delineated. In this study, chitin obtained for the first time from the cocoon of the moth (Orgyia dubia) was subjected to extensive physicochemical analyses and examined, in parallel, with alpha-chitin from exoskeleton of a freshwater crab and 5-chitin from cuttlebone of the common cuttlefish. Our results, which are supported by13C CP-MAS NMR, XRD, FT-IR, Raman spectroscopy, TGA, DSC, SEM, AFM, chitinase digestive test and elemental analysis, verify the authenticity of beta-chitin. Further, quantum chemical calculations were conducted on all three allomorphic forms, and, together with our physicochemical analyses, demonstrate that gamma-chitin is distinct, yet closer in structure to alpha-chitin than beta-chitin.