Morphologic and genetic identification of Diphyllobothrium nihonkaiense in Korea - PubMed (original) (raw)

Morphologic and genetic identification of Diphyllobothrium nihonkaiense in Korea

Hyeong-Kyu Jeon et al. Korean J Parasitol. 2009 Dec.

Abstract

Diphyllobothrium nihonkaiense was first described by Yamane in 1986 but the taxonomical features have been obscure due to lack of critical morphologic criteria in its larval and adult stages. In Korea, this tapeworm had long been known as Diphyllobothrium latum. In this study, we observed 62 specimens collected from Korean residents and analyzed them by morphological features and nucleotide sequences of mitochondrial cox1 gene as well as the ITS1 region. Adult tapeworms were examined after carmine or trichrome stain. Longitudinal sections of the gravid proglottids showed an obtuse angle of about 150 degree between the cirrus sac and seminal vesicle. This angle is known as a major differential point compared with that of D. latum. Nucleotide sequence differences between D. latum and the specimens from Koreans represented 17.3% in mitochondrial DNA cox1 gene. Sequence divergence of ITS1 among 4 Korean isolates was 0.3% and similarity was 99.7% with D. nihonkaiense and D. klebanovskii. All of the Korean specimens analyzed in this study were identified as being D. nihonkaiense (n = 62). We propose its Korean name as "Dong-hae-gin-chon-chung" which means 'long tapeworm of the East Sea' for this newly analyzed diphyllobothriid tapeworm in Korea.

Keywords: Diphyllobothrium latum; Diphyllobothrium nihonkaiense; Korea; distribution; genetic identification.

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Figures

Fig. 1

Gravid proglottids and an egg of Diphyllobothrium nihonkaiense. (A) Whole mounted specimens of a proglottid showing the uterus and cirrus sac (× 25), (B) A SEM photo of the eggshell showing shallow pits and opercular structure (× 3,000), (C, D) Longitudinal sections of a mature proglottid showing the cirrus sac (CS), seminal vesicle (SV), and uterus (U) (C: H-E stain, D: trichrome stain).

Fig. 2

A phylogenetic tree of diphyllobothriid tapeworms based on partial cox1 sequences inferred from neighbor-joining (NJ) analysis. Numbers on branches indicate the bootstrap supporting values based on the 3,000 replicates. There were 335 bps corresponding to positions 735-1107 of the cox1 gene.

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Morphologic and genetic identification of Diphyllobothrium nihonkaiense in Korea - PubMed (original) (raw)