Elucidating the identity of Anisakis larvae from a broad range of marine fishes from the Yellow Sea, China, using a combined electrophoretic‐sequencing approach

Abstract

Larval nematodes were collected from marine fishes from the Yellow Sea, China. Specimens (n=1731) of Anisakis type I from 311 fishes (representing 40 species) were each identified based on morphological characters. From the genomic DNA from individual specimens, a region of nuclear ribosomal DNA was amplified by PCR, followed by digestion with restriction endonuclease HinfI, TaqI or HhaI. Subsequently, the ITS-1 and ITS-2 regions of selected samples were sequenced. The results revealed three species of Anisakis, namely Anisakis pegreffii (n=1709), A. typica (n=3) and a genotype (n=19) proposed, also based on comparison with previous studies, to be a "hybrid" between A. pegreffii and A. simplex sensu stricto. Thus, A. pegreffii was the dominant species, accounting for 98.7% of the total number of specimens examined herein. This is the first report of A. typica and the "hybrid" genotype from fishes from the Yellow Sea. This study provides important basic information on Anisakis in this region and suggests that the genus Anisakis has substantial host and geographical distributions.

Infection levels and diversity of anisakid nematodes in blackspot seabream, Pagellus bogaraveo, from Portuguese waters

“…Fragments in italics might not be visible in the gel the species A. pegreffii, the distance ranged between 0.001 and 0.006. The two consistent differences that have been reported between A. simplex s.s. and A. pegreffii in positions 280 and 296 of the ITS-1 regions, T in A. simplex s.s. and C in A. pegreffii (Abollo et al 2003;Ceballos-Mendiola et al 2010;Du et al 2010), were also detected in our sequences. However, a hybrid sequence (JN005768), which had a C at position 280 but a T at position 296 of the ITS-1 region, is reported here for the first time.…”

“…At the moment, it is not clear whether A. simplex s.s. and A. pegreffii are in the process of speciation, or if they have been geographically separated in the past, but have secondarily come into contact and, in the absence of barriers, behave as a single species when in sympatry, as suggested by Martín-Sánchez et al (2005). Furthermore, the occurrence of hybrids in very distant geographical regions, such as China (Du et al 2010), suggests that this may be a worldwide occurrence whenever A. simplex s.s. and A. pegreffii occur in sympatry.…”

Morphological and molecular identification of Hysterothylacium longilabrum sp. nov. (Nematoda: Anisakidae) and larvae of different stages from marine fishes in the South China Sea

“…During a helminthological survey of Chinese marine fishes from May 2005 to June 2011, large numbers of larvae and adults of ascaridoid nematodes were collected from marine fishes in the Yellow Sea, East China Sea, Taiwan Strait and South China Sea. The results of systematic evaluations of some of this material have already been published (Zhang et al 2007;Li et al 2007aLi et al , b, c, 2008Li et al , 2011Li et al , 2012Du et al 2010). In the present paper, a new species Hysterothylacium longilabrum sp.…”

Morphological and molecular evidence for a new species of the genus Raphidascaris (Nematoda: Anisakidae) from marine fishes from the South China Sea

“…Recently, molecular technique utilizing the internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) as genetic marker has proven to be particularly useful for the accurate identification of ascaridoid nematodes at the species level, eggs, larvae, and adults (Zhang et al 2007;Zhu et al 2007;Du et al 2010;Fang et al 2010;Testini et al 2011). In this paper, a new species, Raphidascaris (Ichthyascaris) longispicula sp.…”