Nuclear and mitochondrial genetic markers highly conserved between Chinese and Philippine Schistosoma japonicum

Effects of praziquantel and artesunate on the tegument of adult Schistosoma mekongi harboured in mice

Oligonucleotide microarray analysis of strain- and gender-associated gene expression in the human blood fluke, Schistosoma japonicum.

Electrophoretically-detected allozyme variation is described in strains of Schistosoma japonicum (4 Philippine strains), S. mekongi (Laos), and an undescribed anthropophilic S. japonicum-like schistosome from Peninsular Malaysia. Result, together with those reported previously for 8 other strains (S. japonicum, China, Formosa, Japan, Philippines; S. mekongi, 2 substrains; Malaysian schistosome, 2 strains) permit a composite genetic characterization of 15 strains of Asian schistosomes at 9-18 presumptive loci. The proportion of polymorphic loci (P) and the mean heterozygosity per locus (H) were zero in all strains. Although this was expected for strains that had been in laboratory culture for up to 50 years, we expected to detect variation in strains based on 10-50 recently field-collected infected snails. We expected S. japonicum to be as variable as S. mansoni (P = 0.13 (0-0.33), H = 0.04, 18 loci, 22 strains) as it is believed to reproduce sexually, has an evolutionary history of several million years, inhabits a wide geographic range, coevolved with a genetically variable intermediate snail host, and has a diversity of mammalian hosts. No differences were detected between the 5 S. japonicum strains from Leyte and Luzon (Philippines), between the 3 S. mekongi strains, or between the 3 Malaysian schistosome strains; these groups and the remaining S. japonicum strains representing Mindoro (Philippines), China, Formosa, and Japan each have distinctive multilocus electromorphic patterns. Nei's genetic distances (D) were calculated to estimate interstrain and interspecific divergence. Interstrain genetic distances in S. japonicum averaged greater than 0.3; much higher than those reported previously for S. mansoni (D = 0.06, D(max) = 0.24). S. japonicum (Mindoro) was moderately differentiated from the Leyte-Luzon strains (D = 0.29, 12 loci). Estimates of the S. japonicum China-Philippine distance (D greater than 0.4, 11 loci) are high for conspecific populations and further studies of the still poorly characterized Chinese parasite may reveal that these are, in fact, separate species. S. japonicum is shown to be only distantly related to S. mekongi and the Malaysian schistosome (D greater than 1); the latter is closely related to, but genetically quite distinct from, S. mekongi (D = 0.61 +/- 0.275, 11 loci) and warrants recognition as a new species. The medical significance of the isogenic nature of the Asian schistosome strains and their evolutionary divergence are discussed.

Genetic variation and differentiation of three Schistosoma species from the Philippines, Laos, and Peninsular Malaysia.

Schistosoma japonicum infection in the pig as a model for human schistosomiasis japonica

Comparison of the surface morphology of adult Schistosoma japonicum (Chinese, Philippine and Indonesian strains) by scanning electron microscopy

The surface topography of the tegument of adult Schistosoma mekongi was studied by scanning electron microscopy (SEM). In comparison to other species of human schistosomes the male tegument lacks tubercles and, except in the gynecophoral canal, also lacks spines; instead the surface is composed chiefly of trabeculae of highly perforated ridges which give it the ‘spongy’ appearance. In addition, there are 3 kinds of papillae interspersed on the surface among the ridges. The first is a doughnut-shaped papilla with a central crater which is most abundant on the ventral surface of the anterior part, on the floor of the gynecophoral canal and on the dorsal-lateral aspect of the tail. The second is a pleomorphic papilla with irregular shape and size, which is scattered throughout the dorso-lateral aspect of the middle part of the body. The third type of papilla has a uniform hemispherical shape, possesses a cilium projecting from its apex and probably corresponds to the ‘sensory papilla’ found in other species. The tegument of the female differs from that of the male by having numerous short spines over the whole surface; however, the pleomorphic papillae are much fewer in number and the ridges are much less developed than those of the male tegument; complex trabeculae are absent.

Scanning electron microscopic study of the tegumental surface of adult Schistosoma mekongi.

The surface of adult Schistosoma japonicum-like (Malaysian) was studied by scanning electron microscopy. The basic pattern of surface microtopography is similar to other strains of S. japonicum as previously reported. However, among male member there are some unique differences in the types, number and distribution of surface papillae and morphology of ridges. Three kinds of papillae were observed: (1) the large fungiform papillae (3.5-4 micron in diameter, most without cilia) are more numerous than in other strains of S. japonicum, they concentrate on the lateral aspect of the anterior and middle parts close to the edge of the gynecophoral canal, and on the dorso-lateral aspect of the posterior part towards the tail tip; (2) the small hemispherical papillae (1.5-2 micron in diameter, all bearing cilia) are especially numerous in the suckers, the gynecophoral canal and parts of the tegument around the suckers and close to the tail tip; on the rest of the surface they are evenly distributed; (3) the cratered papillae (3-4 micron in diameter, about half having cilia) are more numerous than on other strains, they concentrate on the lateral aspect of the middle part and on the edges of the gynecophoral canal. The surface ridges (about 0.2-0.3 micron in width) are tall, highly branching and perforated; they are most developed in the middle part. Spines were observed only in the suckers and the gynecophoral canals. In contrast to the male, the female has numerous spines on all parts of the surface except the most anterior, where a large number of long cilia were observed. All three kinds of papillae were present; fungiform papillae are more numerous than in females of other strains; they concentrate on the latero-dorsal aspect of middle and posterior parts, and around the excretory pore. Ridges are much less developed than in the male and are prominent only in the middle part.

P. Vongpayabal

Papers

Comparison of the surface morphology of adult Schistosoma japonicum (Chinese, Philippine and Indonesian strains) by scanning electron microscopy

Scanning electron microscopic study of the tegumental surface of adult Schistosoma mekongi.

Microtopography of the surface of adult Schistosoma japonicum-like (Malaysian) as observed by scanning electron microscopy.