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    Characterisation of chitin in the cuticle of a velvet worm (Onychophora)
    (Tubitak, 2019) Greven, Hartmut; Kaya, Murat; Sargın, İdris; Baran, Talat; Kristensen, Reinhardt Mobjerg; Sorensen, Martin Vinther
    We characterize the trunk cuticle of velvet worms of the Peripatoides novaezealandiae-group (Onychophora) using SEM, TEM, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). TEM and SEM revealed a relatively uniform organization of the delicate cuticle that is covered by numerous bristled and nonbristled papillae with ribbed scales arranged in transverse rows. The cuticle consists of a very thin multilayered epicuticle of varying appearance followed by the largely fibrous procuticle. The irregularly arranged nanofibres of isolated cuticular chitin seen by SEM are considered as bundles of chitin fibres. FT-IR and TGA showed that the chitin is of the ?-type. This confirms and broadens the single previous study in which the presence of ?-chitin in a velvet worm was demonstrated with a single analysis (X-ray diffraction).
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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.
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    The presence of ?-chitin in Tardigrada with comments on chitin in the Ecdysozoa
    (Elsevier GmbH, 2016) Greven, Hartmut; Kaya, Murat; Baran, Talat
    We used Fourier Transform Infrared Spectroscopy (FT-IR) to characterize for the first time chitin in the cuticle of a eutardigrade (Macrobiotus cf. hufelandi). Analysis of the isolated cuticles of single individuals and comparison with commercial ?-chitin isolated from shrimp shell and ?-chitin from squid pen revealed that the amide I band was split into two peaks characteristic for ?-chitin. In the current literature cuticles containing ?-chitin are considered as an apomorphic character of the Ecdysozoa (Cycloneuralia, Panarthropoda). This is a plausible assumption, although ?-chitin has been unequivocally demonstrated only in the cuticle of the Panarthropoda, i.e. Onychophora, Tardigrada (this article) and Arthropoda, and in the Priapulida (Cycloneuralia), whereas chitin in the cuticle of the other cycloneuralian taxa either was not further specified or appears to be absent.
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    The presence of alpha-chitin in Tardigrada with comments on chitin in the Ecdysozoa
    (Elsevier, 2016) Greven, Hartmut; Kaya, Murat; Baran, Talat
    We used Fourier Transform Infrared Spectroscopy (FT-IR) to characterize for the first time chitin in the cuticle of a eutardigrade (Macrobiotus cf. hufelandi). Analysis of the isolated cuticles of single individuals and comparison with commercial alpha-chitin isolated from shrimp shell and beta-chitin from squid pen revealed that the amide I band was split into two peaks characteristic for alpha-chitin. In the current literature cuticles containing alpha-chitin are considered as an apomorphic character of the Ecdysozoa (Cycloneuralia, Panarthropoda). This is a plausible assumption, although alpha-chitin has been unequivocally demonstrated only in the cuticle of the Panarthropoda, i.e. Onychophora, Tardigrada (this article) and Arthropoda, and in the Priapulida (Cycloneuralia), whereas chitin in the cuticle of the other cycloneuralian taxa either was not further specified or appears to be absent. (C) 2016 Elsevier GmbH. All rights reserved.