Kenjiro Kawashima

Molecular phylogeographic studies on Paragonimus westermani in Asia

The lung fluke, Paragonimus westermani (Kerbert, 1878), is widely distributed in Asia, and exhibits much variation in its biological properties. Previous phylogenetic studies using DNA sequences have demonstrated that samples from north-east Asia form a tight group distinct from samples from south Asia (Philippines, Thailand, Malaysia). Among countries from the latter region, considerable molecular diversity was observed. This was investigated further using additional DNA sequences (partial mitochondrial cytochrome c oxidase subunit 1 (COI) and the second internal transcribed spacer of the nuclear ribosomal gene repeat (ITS2)) from additional samples of P. westermani. Phylogenies inferred from these again found three or four groups within P. westermani, depending on the method of analysis. Populations of P. westermani from north-east Asia use snail hosts of the family Pleuroceridae and differ in other biological properties from populations in south Asia (that use snail hosts of the family Thiaridae). It is considered that the populations we sampled can be divided into two species, one in north-east Asia and the other in south Asia.

Electrophoretic evidence of a hybrid origin for tetraploidParagonimus westermani discovered in northeastern China

1 Department of Parasitology, Kochi Medical School, Nankoku City, Kochi 783, Japan z Department of Parasitology, Beijin Medical University, Beijing 100034, P. R. China 3 Department of Parasitology, School of Medicine, Fukuoka University, Fukuoka City, Fukuoka 814-01, Japan 4 Laboratory of Biology, St. Marys Junior College, Tsubuku-Honmachi, Kurume City, Fukuoka 830, Japan 5 Laboratory Animal Research Center, Tottori University School of Medicine, Yonago City, Tottori 683, Japan 6 Department of Parasitology, National Institute of Health, Kamiosaki, Shinagawa-ku, Tokyo 141, Japan 7 Department of Parasitology, National Institute of Health, 5 Nokbun-Dong Eunpyung-ku, Seoul, 122-020, Korea s School of Health Sciences, Kyushu University, Fukuoka City, Fukuoka 812, Japan

Tetraploids of the lung flukeParagonimus westermani found in China

Two groups ofParagonimus westermani (Tematoda: Platyhelminthes) exist in nature: diploids and triploids. Generally, these two groups live allopatrically, but in Kuandian, Liaoning Province, in the Republic of China, they live sympatrically. In our Chinese experiment onParagonimus we used metacercariae ofP. westermani, which we collected in Kuandian, Xigutai, and performed a cytological analysis. The results were as follows: (1) theP. westermani in Xigutai lived sympatrically as diploids and triploids; (2) all of the small metacercariae were diploids; (3) the large metacercariae were in large proportion triploids; (4) we found one tetraploid specimen in both the medium and the large metacercariae — this was the first time tetraploid lung flukes were discovered; (5) the somatic chromosomes of the tetraploids were different in numbers (4n=44), but we could not find any difference in the karyotype of haploid sets and that of the diploids and the triploids; (6) unlike the triploids, during their meiosis the tetraploids produced a chromosome pairing, and we found a tendency of the large chromosomes to become quadrivalent; and (7) also unlike the triploids, a great number of spermatids were found in the tetraploid testes. Because of these findings, we can consider tetraploids to be autotetraploids, and these are probably produced by the fertilization of diploids and triploids. We also think that the gametes of tetraploids have a fertilization capability.

The origin of the triploid in Paragonimus westermani on the basis of variable regions in the mitochondrial DNA

Triploid, parthenogenetic forms of the lungfluke, Paragonimus westermani, occur in Japan, Korea and China. The origin(s) of triploidy has been debated over the years. Sequences of two regions in the mitochondrial DNA, i.e. partial lrRNA (16S), and a portion of the non-coding region, were obtained from natural populations of P. westermani. All triploid individuals (Japan, Korea, China) and a single tetraploid individual (China) had identical sequences in the 16S region studied. Some sequence variation was observed among diploids, with those from Taiwan being distinct from the remainder. Both neighbour joining and parsimony trees using the 16S region placed diploid individuals from southwestern Japan close to the triploids and the tetraploid. The fragment amplified from the mitochondrial non-coding region showed dimorphism. One form (type A) consisted of 239 bp comprising two identical tracts of 70 bp separated by a tract of 93 bp. The second form (Type B) consisted of only a single 70 bp tract. All diploid individuals from Taiwan, China and Korea possessed type A, while those from Japan were polymorphic; individuals from Oita and Hyogo had type B, those from Chiba had type A, but both types were found in Mie. On the other hand, all of the triploid individuals and two tetraploid individuals possessed type B. Both the form present in the non-coding region and the 16S sequence suggest an affinity between a south-eastern group of diploid populations in Japan and the triploid form. A possible mechanism responsible for the origin of the triploid is discussed.

Reciprocal translocation between the long arms of chromosomes four and six of Paragonimus westermani from the Philippines.

C-banding patterns have been observed in 14 specimens of Paragonimus westermani from Jaro, Leyte, the Philippines. One of them showed mutations of 2 chromosomes in spreads. Comparative analysis of C-banding patterns between the individual and standard type clarified that the mutant resulted from a reciprocal translocation between the long arms of chromosomes 4 and 6.

The cercarial emergence of Schistosoma japonicum from Oncomelania quadrasi under outdoor conditions in the Philippines

The cercarial emergence of Schistosoma japonicum from Oncomelania quadrasi was observed under outdoor conditions in Leyte, Philippines. Nocturnal periodicity of the emergence within 24 hours was recognized. Peak emergence usually occurs between 18:00 and 20:00 and occasionally between 8:00 and 10:00. The peaks were usually synchronized with a sudden lowering of water temperature and light intensity and occasionally with their increase. As the nocturnal periodicity of the emergence was observed in the dark and outdoors, it was suggested that emergence might be dependent on temperature, which is secondarily influenced by photoperiodicity and light intensity.

Electrophoretic analysis of a natural population of the Thai Paragonimus heterotremus and its genetic relationship to the three Japanese species P. miyazaki, P. ohirai and P. westermani.

A total of 18 enzymes (encoded by 20 loci) fromParagonimus heterotremus collected at a local area in Saraburi, Thailand, were electrophoretically compared with those from the three Japanese speciesP. ohirai, P. miyazakii andP. westermani using horizontal starchgel electrophoresis. Relative genetic distances between these species were quantified. The ThaiP. heterotremus was found to be most closely related toP. miyazaki and rather distantly related toP. westermani. On the other hand, among the three Japanese species, the closest relationship was observed betweenP. miyazakii andP. ohirai.

Multiple larval tick infestation of man. A case of infesting larvae seeming to be pustules with a red halo.

A 53‐year‐old Japanese male forest officer suffered from pains which seemed to be insect bites. Examination revealed a patient with more than 10 pustule‐like lesions which subsequently proved to be larval A. testudinarium infestations. All the ticks were removed with a pair of forceps. The remaining erythematous lesions were treated with 0.25% hydrocortisone clotamiton ointment. Pains disappeared soon. A diagnosis of tick infestation should be made before the tick is removed, in order to prevent severe effects from allowing the mouth parts of the tick to remain, which occasionally results in inflammation and granulation tissue formation, and also to make a good preparation of the tick for correct identification.