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Discrimination of Oribotritia species by oil gland chemistry (Acari, Oribatida).

Raspotnig G, Leutgeb V, Krisper G, Leis HJ - Exp. Appl. Acarol. (2011)

Bottom Line: In addition a reduced set of "Astigmata compounds" (sensu Sakata and Norton in Int J Acarol 27:281-291, 2001)--namely the two monoterpenes neral and geranial--could be detected in extracts of O. banksi nevertheless indicating the classification of euphthiracaroids within the (monophyletic) group of "Astigmata compounds-bearing"-Oribatida.These compounds are considered to be apomorphically reduced in all Austrian species.Our findings emphasize the potential of chemosystematics using oil gland secretion profiles in the discrimination of morphologically very similar, syntopically living or even cryptic oribatid species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Zoology, Karl-Franzens-University, Universitätsplatz 2, 8010, Graz, Austria. guenther.raspotnig@uni-graz.at

ABSTRACT
The chemical composition of secretions from opisthonotal (oil) glands in four species of the oribatid mite genus Oribotritia (Mixonomata, Euphthiracaroidea, Oribotritiidae) was compared by means of gas chromatography--mass spectrometry. The secretions of all, O. banksi (from North America) and three Austrian oribotritiids (O. berlesei, O. hermanni, O. storkani), are shown to be based on certain unusual compounds, the iridoid monoterpenes chrysomelidial and epi-chrysomelidial and the diterpene β-springene. These components probably represent general chemical characteristics of oribotriid oil glands. Their relative abundance in the secretions along with further components (mainly saturated and unsaturated C(13)-, C(15)-, C(17)-hydrocarbons, and the tentatively identified octadecadienal) led to well-distinguishable, species-specific oil gland secretions profiles. In addition a reduced set of "Astigmata compounds" (sensu Sakata and Norton in Int J Acarol 27:281-291, 2001)--namely the two monoterpenes neral and geranial--could be detected in extracts of O. banksi nevertheless indicating the classification of euphthiracaroids within the (monophyletic) group of "Astigmata compounds-bearing"-Oribatida. These compounds are considered to be apomorphically reduced in all Austrian species. Our findings emphasize the potential of chemosystematics using oil gland secretion profiles in the discrimination of morphologically very similar, syntopically living or even cryptic oribatid species.

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Typical chromatographic profiles of oil gland secretion from individual extracts of different Oribotritia species. Peak A (neral)*, peak B (geranial)*, peak C (tridecene), peak D (tridecane), peak E (epi-chrysomeldial), peak F (chrysomelidial), peak G (pentadecene), peak H (pentadecane), peak I (6,9-heptadecadiene), peak J (8-heptadecene), peak K (β-springene), peak L (octadecadienal). Astigmatid compounds are marked with an asterisk. Double bond positions in tridecene (component C) and pentadecene (component G) were not identified; component L (octadecadienal) was only tentatively identified based on a structural proposal from the NIST library. Peaks “x” mark a cluster of small monoterpenes (all with M = 136) which inconsistently were found in some of the extracts
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Fig1: Typical chromatographic profiles of oil gland secretion from individual extracts of different Oribotritia species. Peak A (neral)*, peak B (geranial)*, peak C (tridecene), peak D (tridecane), peak E (epi-chrysomeldial), peak F (chrysomelidial), peak G (pentadecene), peak H (pentadecane), peak I (6,9-heptadecadiene), peak J (8-heptadecene), peak K (β-springene), peak L (octadecadienal). Astigmatid compounds are marked with an asterisk. Double bond positions in tridecene (component C) and pentadecene (component G) were not identified; component L (octadecadienal) was only tentatively identified based on a structural proposal from the NIST library. Peaks “x” mark a cluster of small monoterpenes (all with M = 136) which inconsistently were found in some of the extracts

Mentions: Under the given chromatographic conditions, a total of 12 different components could be separated from all 48 extracts (peaks A-L in Fig. 1). All components have already been familiar to us from previous studies (e.g., Raspotnig et al. 2008), and were tentatively identified by their EI-mass spectra (peak A: neral; peak B: geranial; peak C: tridecene; peak D: tridecane; peak E: epi-chrysomelidial = (3S, 8R)-chrysomelidial; peak F: chrysomelidial = (3S,8S)-chrysomelidial; peak G: pentadecene; peak H: pentadecane; peak I: 6,9-heptadecadiene; peak J: 8-heptadecene; peak K: β-springene; peak L: octadecadienal). In most cases, a final identification by comparison of retention times to authentic samples was possible (see Table 2), particularly true for neral, geranial, both chrysomelidials and the saturated hydrocarbons (tri- and pentadecane). The position of double bonds in unsaturated hydrocarbons was only determined for the major hydrocarbon compound, a doubly-unsaturated C17-hydrocarbon, namely 6,9-heptadecadiene (peak I). Due to low quantities, double bond positions could not be specified for the tri- and pentadecene (peaks C and G). The C17:1-hydrocarbon (peak J) appeared to be 8-heptadecene, based on mass spectral characteristics and on the comparison of retention times and to an extract of Platynothrus peltifer, another oribatid mite which is known to contain the authentic compound (Raspotnig et al. 2005b). Peaks K and L were tentatively identified as β-springene and octadecadienal, respectively, based on mass spectral comparison only. However, at least the identification of β-springene is strongly supported by mass spectral comparisons to spectra from the NIST-library and from literature (Burger et al. 1978; Waterhouse et al. 1996; Schulz et al. 2003; Howard et al. 2003; Bertsch et al. 2004; Cruz-Lopez et al. 2005). Components E and F, epi-chrysomelidial and chrysomelidial, appeared to be poorly separable under the given chromatographic conditions and eluted closely together (RT of peak E = 13.32 min; RT of peak F = 13.36 min). Thus, in each of the extracts, their identity was additionally checked by a close look at the relation of fragment ions at m/z 148 and m/z 138 in the EI mass spectra. In chrysomelidial, the intensity of the fragment at m/z 148 characteristically exceeds the ion at m/z 138; in epi-chrysomelidial, the opposite is the case (see Raspotnig et al. 2008). A short overview on all analytical data along with some diagnostic mass spectrometric characters is given in Table 2.Fig. 1


Discrimination of Oribotritia species by oil gland chemistry (Acari, Oribatida).

Raspotnig G, Leutgeb V, Krisper G, Leis HJ - Exp. Appl. Acarol. (2011)

Typical chromatographic profiles of oil gland secretion from individual extracts of different Oribotritia species. Peak A (neral)*, peak B (geranial)*, peak C (tridecene), peak D (tridecane), peak E (epi-chrysomeldial), peak F (chrysomelidial), peak G (pentadecene), peak H (pentadecane), peak I (6,9-heptadecadiene), peak J (8-heptadecene), peak K (β-springene), peak L (octadecadienal). Astigmatid compounds are marked with an asterisk. Double bond positions in tridecene (component C) and pentadecene (component G) were not identified; component L (octadecadienal) was only tentatively identified based on a structural proposal from the NIST library. Peaks “x” mark a cluster of small monoterpenes (all with M = 136) which inconsistently were found in some of the extracts
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105237&req=5

Fig1: Typical chromatographic profiles of oil gland secretion from individual extracts of different Oribotritia species. Peak A (neral)*, peak B (geranial)*, peak C (tridecene), peak D (tridecane), peak E (epi-chrysomeldial), peak F (chrysomelidial), peak G (pentadecene), peak H (pentadecane), peak I (6,9-heptadecadiene), peak J (8-heptadecene), peak K (β-springene), peak L (octadecadienal). Astigmatid compounds are marked with an asterisk. Double bond positions in tridecene (component C) and pentadecene (component G) were not identified; component L (octadecadienal) was only tentatively identified based on a structural proposal from the NIST library. Peaks “x” mark a cluster of small monoterpenes (all with M = 136) which inconsistently were found in some of the extracts
Mentions: Under the given chromatographic conditions, a total of 12 different components could be separated from all 48 extracts (peaks A-L in Fig. 1). All components have already been familiar to us from previous studies (e.g., Raspotnig et al. 2008), and were tentatively identified by their EI-mass spectra (peak A: neral; peak B: geranial; peak C: tridecene; peak D: tridecane; peak E: epi-chrysomelidial = (3S, 8R)-chrysomelidial; peak F: chrysomelidial = (3S,8S)-chrysomelidial; peak G: pentadecene; peak H: pentadecane; peak I: 6,9-heptadecadiene; peak J: 8-heptadecene; peak K: β-springene; peak L: octadecadienal). In most cases, a final identification by comparison of retention times to authentic samples was possible (see Table 2), particularly true for neral, geranial, both chrysomelidials and the saturated hydrocarbons (tri- and pentadecane). The position of double bonds in unsaturated hydrocarbons was only determined for the major hydrocarbon compound, a doubly-unsaturated C17-hydrocarbon, namely 6,9-heptadecadiene (peak I). Due to low quantities, double bond positions could not be specified for the tri- and pentadecene (peaks C and G). The C17:1-hydrocarbon (peak J) appeared to be 8-heptadecene, based on mass spectral characteristics and on the comparison of retention times and to an extract of Platynothrus peltifer, another oribatid mite which is known to contain the authentic compound (Raspotnig et al. 2005b). Peaks K and L were tentatively identified as β-springene and octadecadienal, respectively, based on mass spectral comparison only. However, at least the identification of β-springene is strongly supported by mass spectral comparisons to spectra from the NIST-library and from literature (Burger et al. 1978; Waterhouse et al. 1996; Schulz et al. 2003; Howard et al. 2003; Bertsch et al. 2004; Cruz-Lopez et al. 2005). Components E and F, epi-chrysomelidial and chrysomelidial, appeared to be poorly separable under the given chromatographic conditions and eluted closely together (RT of peak E = 13.32 min; RT of peak F = 13.36 min). Thus, in each of the extracts, their identity was additionally checked by a close look at the relation of fragment ions at m/z 148 and m/z 138 in the EI mass spectra. In chrysomelidial, the intensity of the fragment at m/z 148 characteristically exceeds the ion at m/z 138; in epi-chrysomelidial, the opposite is the case (see Raspotnig et al. 2008). A short overview on all analytical data along with some diagnostic mass spectrometric characters is given in Table 2.Fig. 1

Bottom Line: In addition a reduced set of "Astigmata compounds" (sensu Sakata and Norton in Int J Acarol 27:281-291, 2001)--namely the two monoterpenes neral and geranial--could be detected in extracts of O. banksi nevertheless indicating the classification of euphthiracaroids within the (monophyletic) group of "Astigmata compounds-bearing"-Oribatida.These compounds are considered to be apomorphically reduced in all Austrian species.Our findings emphasize the potential of chemosystematics using oil gland secretion profiles in the discrimination of morphologically very similar, syntopically living or even cryptic oribatid species.

View Article: PubMed Central - PubMed

Affiliation: Institute of Zoology, Karl-Franzens-University, Universitätsplatz 2, 8010, Graz, Austria. guenther.raspotnig@uni-graz.at

ABSTRACT
The chemical composition of secretions from opisthonotal (oil) glands in four species of the oribatid mite genus Oribotritia (Mixonomata, Euphthiracaroidea, Oribotritiidae) was compared by means of gas chromatography--mass spectrometry. The secretions of all, O. banksi (from North America) and three Austrian oribotritiids (O. berlesei, O. hermanni, O. storkani), are shown to be based on certain unusual compounds, the iridoid monoterpenes chrysomelidial and epi-chrysomelidial and the diterpene β-springene. These components probably represent general chemical characteristics of oribotriid oil glands. Their relative abundance in the secretions along with further components (mainly saturated and unsaturated C(13)-, C(15)-, C(17)-hydrocarbons, and the tentatively identified octadecadienal) led to well-distinguishable, species-specific oil gland secretions profiles. In addition a reduced set of "Astigmata compounds" (sensu Sakata and Norton in Int J Acarol 27:281-291, 2001)--namely the two monoterpenes neral and geranial--could be detected in extracts of O. banksi nevertheless indicating the classification of euphthiracaroids within the (monophyletic) group of "Astigmata compounds-bearing"-Oribatida. These compounds are considered to be apomorphically reduced in all Austrian species. Our findings emphasize the potential of chemosystematics using oil gland secretion profiles in the discrimination of morphologically very similar, syntopically living or even cryptic oribatid species.

Show MeSH