Molecular phylogeny of trematodes in Family Heterophyidae based on mitochondrial cytochrome c oxidase subunit I (mCOI)

OBJECTIVE@#To analyze a phylogenetic tree for understanding the molecular systematic of trematode in Family Heterophyidae, which are highly distributed in Thailand.@*METHODS@#Based on thirteen sequences of mitochondrial cytochrome c oxidase subunit I (mCOI) gene from six genera of heterophyid trematodes, viz. Haplorchis, Stellantchasmus, Centrocestus, Metagonimus, Pygidopsis, and Haplorchoides were aligned automatically using the Clustal × 2.0 program. A phylogenetic tree was constructed by maximum likeinghood (ML) and neighbor-joining (NJ) methods, with 1 000 bootstrap using the 5.0 program.@*RESULTS@#The phylogenetic relationship from both methods was similar and separated into three groups consisting of Haplorchoides pumilio group, Haplorchoides taichui group and another heterophyid genera.@*CONCLUSIONS@#The sequence data of mtCOI can be used to investigate the phylogenetic relationships of trematodes at the genus level. Each clade of different genera of heterophyid trematodes can be separated into sister groups that correlated with the morphological characteristic, kind of secondary intermediate host and geographic distribution.

Metacercariae of Centrocestus formosanus (Trematoda: Heterophyidae) in Australoheros facetus (Pisces: Cichlidae) in Brazil / Metacercárias de Centrocestus formosanus (Trematoda: Heterophyidae) em Australoheros facetus (Pisces: Cichlidae) no Brasil

Heterophyid metacercariae were found in the gills of Australoheros facetus (Jenyns, 1842) collected from the Pampulha reservoir, Belo Horizonte, Minas Gerais, Brazil, between February and April 2010. The cysts were counted and used to perform experimental studies (artificial excystment and infection of mice). Fifty specimens of A. facetus were analyzed and it was found that the prevalence of infection was 100% and mean infection intensity was 134 metacercariae/fish (range: 4-2,510). Significant positive correlations were seen between total fish length and intensity of infection; between fish weight and intensity of infection, and between parasite density and fish length. Morphological analyses on metacercariae and adult parasites obtained from experimentally infected mice made it possible to identify Centrocestus formosanus (Nishigori, 1924). This is the first report of C. formosanus in A. facetus in Brazil.

Metacercárias de Heterophyidae foram encontradas nas brânquias de Australoheros facetus (Jenyns, 1842) coletados na represa da Pampulha, Belo Horizonte, Minas Gerais, Brasil, entre fevereiro e abril de 2010. Os cistos obtidos foram contados e utilizados em estudos experimentais (desencistamento artificial e infecção de camundongos). Cinquenta exemplares de A. facetus foram analisados, sendo verificada prevalência de infecção de 100% e intensidade média de infecção de 134 metacercárias/peixe (variando entre 4 e 2510). Verificou-se correlação positiva entre a intensidade de infecção e comprimento total dos peixes; entre a intensidade de infecção e o peso dos peixes e entre a densidade parasitária e o comprimento total. A análise morfológica das metacercárias e dos parasitos adultos obtidos em camundongos experimentalmente infectados permitiu a identificação de Centrocestus formosanus (Nishigori, 1924). Este é o primeiro relato de C. formosanus em A. facetus no Brasil.

The life history of Pygidiopsis macrostomum Travassos, 1928 (Digenea: Heterophyidae)

The life history of the trematode Pygidiopsis macrostomum Travassos, 1928 is described for the first time. Rediae and cercariae were obtained from naturally infected snails Heleobia australis (d´Orbigny), a new first intermediate host. Metacercariae were found encysted in the mesenteries of three naturally infected guppies, Phalloptychus januarius (Hensel), Jenynsia multidentata (Jenyns) (new host records) and Poecilia vivipara Bloch and Schneider. Experimental infections were successfully completed in the intermediate hosts H. australis and Poe. vivipara reared in the laboratory and hamsters Mesocricetus auratus Waterhouse were utilised as a definitive host.

Heterophyid metacercarial infections in brackish water fishes from Jinju-man (Bay), Kyongsangnam-do, Korea

Heterophyid metacercarial infections in brackish water fishes, i.e., perch, shad, mullet, redlip mullet, and goby, of Jinju-man (Bay), Kyongsangnam-do, Korea, were investigated using a digestion technique. Among 45 perch (Lateolabrax japonicus), the metacercariae of Heterophyopsis continua were found in 55.6% (18.5 metacercariae per fish), Stictodora spp. in 28.9% (3.6), and Metagonimus takahashii in 6.7% (17.0). The metacercariae of H. continua were detected in 23 (65.7%) of 35 shad (Konosirus punctatus). Among 15 mullet (Mugil cephalus), the metacercariae of Pygidiopsis summa were found in 100% (105.9 metacercariae per fish), Heterophyes nocens in 40.0% (8.5), H. continua in 13.3%, and Stictodora spp. in 6.7%. Among 12 redlip mullet (Chelon haematocheilus), the metacercariae of P. summa were detected in 91.7% (1,299 metacercariae per fish), H. nocens in 16.7%, and Stictodora spp. in 16.7%. Among 35 gobies (Acanthogobius flavimanus), the metacercariae of Stictodora spp. were found in 82.9% (44.5 metacercariae per fish), and H. continua in 25.7% (2.8). The adult flukes recovered from a cat experimentally infected with metacercariae from perches were compatible with M. takahashii. The results confirm that the estuarine fish in Jinju-man (Bay) are heavily infected with heterophyid metacercariae. Furthermore, it was found for the first time that the perch acts as a second intermediate host for M. takahashii.

Sequence comparisons of 28S ribosomal DNA and mitochondrial cytochrome c oxidase subunit I of Metagonimus yokogawai, M. takahashii and M. miyatai

We compared the DNA sequences of the genus Metagonimus: M. yokogawai, M. takahashii, and M. miyatai. We obtained 28S D1 ribosomal DNA (rDNA) and mitochondrial cytochrome c oxidase subunit I (mtCOI) fragments from the adult worms by PCR, that were cloned and sequenced. Phylogenetic relationships inferred from the nucleotide sequences of the 28S D1 rDNA and mtCOI gene. M. takahashii and M. yokogawai are placed in the same clade supported by DNA sequence and phylogenic tree analysis in 28S D1 rDNA and mtCOI gene region. The above findings tell us that M. takahashii is closer to M. yokogawai than to M. miyatai genetically. This phylogenetic data also support the nomination of M. miyatai as a separate species.

Surface ultrastructure of Pygidiopsis summa (Digenea: Heterophyidae) adult flukes

A scanning electron microscopic study was performed on the surface ultrastructure of Pygidiopsis summa (Digenea: Heterophyidae) adults. Metacercariae were collected from gills and muscles of mullets (Mugil cephalus) caught in a known endemic area, and adult flukes were harvested from dogs after 8 weeks of experimental infection. The worm was calabash form with its posterior part broader than the anterior part. Tegumental spines were densely distributed over the body surface, except on the suckers and genital apparatus, and around the excretory pore. Well differentiated spines were observed on the anterior half of the body, with 14-16 tips ventrally, and 19-20 tips dorsally. On the oral sucker, three pairs of type I sensory papillae (uni-ciliated knob-like swellings) and one pair of type II sensory papillae (aciliated round-swellings) were observed on the anterior and posterior parts of the lip, respectively. On the lip of the ventral sucker, one pair of type II sensory papillae was distributed only on its posterior part. Sperms were seen emerging from or entering into the genital apparatus. The results showed that the surface ultrastructure of P. summa was unique among the heterophyid trematodes, especially in digitation of tegumental spines and in distribution of sensory papillae on oral and ventral suckers.