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Morphological and morphometric differentiation of dorsal-spined first stage larvae of lungworms (Nematoda: Protostrongylidae) infecting muskoxen (Ovibos moschatus) in the central Canadian Arctic.

Kafle P, Lejeune M, Verocai GG, Hoberg EP, Kutz SJ - Int J Parasitol Parasites Wildl (2015)

Bottom Line: The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA.Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic.Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.

ABSTRACT
Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are the two most common protostrongylid nematodes infecting muskoxen in the North American Arctic and Subarctic. First stage larvae (L1) of these lungworms have considerable morphological similarity that makes their differential diagnosis very difficult. Using light microscopy, we studied in detail the L1 of these two species and identified the key differences in morphological and morphometric attributes. Thirty L1 of each species from naturally infected muskox were heat-killed and then assessed for morphological and morphometric features that could be used for species-level differentiation. Key differentiating features include: length and morphology of the tail extension, curvature of the body, ventral post-anal transverse cuticular striations, and total body length. A laboratory guide for differentiation of L1 based on these species-specific characters was prepared and used by an experienced observer to identify an additional 35 L1 extracted from a different set of fecal samples from free-ranging muskoxen with mixed infections. The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA. Accuracy of morphological identification was 100 percent, reflecting the reliability of the proposed guide for differentiation. Using the guide, three minimally trained lab assistants each fixed and accurately identified 10 of 10 randomly selected L1. Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic. Studies enabling species-level parasite identification are also critical for defining biodiversity, detecting mixed infections, and understanding host-parasite interactions. Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings.

No MeSH data available.


Related in: MedlinePlus

Laboratory guide for the differentiation of L1 of U. pallikuukensis and V. eleguneniensis. The guide is based on key morphological features supported by morphometric data of heat killed L1. These features were characteristic of each of the species as visible under 400 × magnification.
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fig2: Laboratory guide for the differentiation of L1 of U. pallikuukensis and V. eleguneniensis. The guide is based on key morphological features supported by morphometric data of heat killed L1. These features were characteristic of each of the species as visible under 400 × magnification.

Mentions: The most consistent and remarkable differences occurred in the caudal region of the body, primarily on the ventral aspect of the tail (region posterior to anus) (Fig. 1). The tail region of both the species has the same general structure. The tail extension of both U. pallikuukensis and V. eleguneniensis, like other protostrongylids, has three distinct cuticular folds, proximal, middle and distal with a dorsal spine originating at the base of the tail extension (Hoberg et al., 1995, 2005; Carreno and Hoberg, 1999). On detailed observation of the tail extension, U. pallikuukensis has a long and slender tail spike (tip of the tail) (Fig. 2A), whereas the tail spike of V. eleguneniensis is relatively shorter and angled ventrally giving a “vulture beak” appearance (Fig. 2B). These features were consistently characteristic across all L1 examined of each of the species and were identified as the primary character for differentiation. Similarly, the degree of ventral curving of the distal one third portion of heat killed L1 was also identified as one of the characteristic differences. The distal one third of V. eleguneniensis is more tightly curved than U. pallikuukensis (Fig. 2C and D). The third consistent feature was the difference in the appearance of surface cuticle anterior and posterior to the anus. The post-anal ventral cuticular surface in U. pallikuukensis has prominent transverse striations (Fig. 2E); this is not apparent in specimens of V. eleguneniensis (Fig. 2F). The other morphological feature that generally differed was the appearance of the intestinal granules. The intestinal granules appeared rougher and larger in V. eleguneniensis than in U. pallikuukensis. This feature, although seen in most of the larvae, was not appreciable in 100% of the larvae, so it could potentially be used only in support of the other identification characters.


Morphological and morphometric differentiation of dorsal-spined first stage larvae of lungworms (Nematoda: Protostrongylidae) infecting muskoxen (Ovibos moschatus) in the central Canadian Arctic.

Kafle P, Lejeune M, Verocai GG, Hoberg EP, Kutz SJ - Int J Parasitol Parasites Wildl (2015)

Laboratory guide for the differentiation of L1 of U. pallikuukensis and V. eleguneniensis. The guide is based on key morphological features supported by morphometric data of heat killed L1. These features were characteristic of each of the species as visible under 400 × magnification.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487832&req=5

fig2: Laboratory guide for the differentiation of L1 of U. pallikuukensis and V. eleguneniensis. The guide is based on key morphological features supported by morphometric data of heat killed L1. These features were characteristic of each of the species as visible under 400 × magnification.
Mentions: The most consistent and remarkable differences occurred in the caudal region of the body, primarily on the ventral aspect of the tail (region posterior to anus) (Fig. 1). The tail region of both the species has the same general structure. The tail extension of both U. pallikuukensis and V. eleguneniensis, like other protostrongylids, has three distinct cuticular folds, proximal, middle and distal with a dorsal spine originating at the base of the tail extension (Hoberg et al., 1995, 2005; Carreno and Hoberg, 1999). On detailed observation of the tail extension, U. pallikuukensis has a long and slender tail spike (tip of the tail) (Fig. 2A), whereas the tail spike of V. eleguneniensis is relatively shorter and angled ventrally giving a “vulture beak” appearance (Fig. 2B). These features were consistently characteristic across all L1 examined of each of the species and were identified as the primary character for differentiation. Similarly, the degree of ventral curving of the distal one third portion of heat killed L1 was also identified as one of the characteristic differences. The distal one third of V. eleguneniensis is more tightly curved than U. pallikuukensis (Fig. 2C and D). The third consistent feature was the difference in the appearance of surface cuticle anterior and posterior to the anus. The post-anal ventral cuticular surface in U. pallikuukensis has prominent transverse striations (Fig. 2E); this is not apparent in specimens of V. eleguneniensis (Fig. 2F). The other morphological feature that generally differed was the appearance of the intestinal granules. The intestinal granules appeared rougher and larger in V. eleguneniensis than in U. pallikuukensis. This feature, although seen in most of the larvae, was not appreciable in 100% of the larvae, so it could potentially be used only in support of the other identification characters.

Bottom Line: The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA.Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic.Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.

ABSTRACT
Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are the two most common protostrongylid nematodes infecting muskoxen in the North American Arctic and Subarctic. First stage larvae (L1) of these lungworms have considerable morphological similarity that makes their differential diagnosis very difficult. Using light microscopy, we studied in detail the L1 of these two species and identified the key differences in morphological and morphometric attributes. Thirty L1 of each species from naturally infected muskox were heat-killed and then assessed for morphological and morphometric features that could be used for species-level differentiation. Key differentiating features include: length and morphology of the tail extension, curvature of the body, ventral post-anal transverse cuticular striations, and total body length. A laboratory guide for differentiation of L1 based on these species-specific characters was prepared and used by an experienced observer to identify an additional 35 L1 extracted from a different set of fecal samples from free-ranging muskoxen with mixed infections. The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA. Accuracy of morphological identification was 100 percent, reflecting the reliability of the proposed guide for differentiation. Using the guide, three minimally trained lab assistants each fixed and accurately identified 10 of 10 randomly selected L1. Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic. Studies enabling species-level parasite identification are also critical for defining biodiversity, detecting mixed infections, and understanding host-parasite interactions. Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings.

No MeSH data available.


Related in: MedlinePlus