Comparison of genetic diversity and population structure between two Schistosoma japonicum isolates—the field and the laboratory

Abstract

Schistosomiasis japonicum is one of the most important human parasitic diseases, and a number of studies have recently elucidated the difference in biological characteristics of S. japonicum among different parasite isolates, for example, between the field and the laboratory isolates. Therefore, the understanding of underlying genetic mechanism is of both theoretical and practical importance. In this study, we used six microsatellite markers to assess genetic diversity, population structure, and the bottleneck effect (a sharp reduction in population size) of two parasite populations, one field and one laboratory. A total of 136 S. japonicum cercariae from the field and 86 from the laboratory, which were genetically unique within single snails, were analyzed. The results showed bigger numbers of alleles and higher allelic richness in the field parasite population than in the laboratory indicating lower genetic diversity in the laboratory parasites. A bottleneck effect was detected in the laboratory population. When the field and laboratory isolates were combined, there was a clear distinction between two parasite populations using the software Structure. These genetic differences may partially explain the previously observed contrasted biological traits.

Creating outbred and inbred populations in haplodiploids to measure adaptive responses in the laboratory

“…Another reason is that laboratory populations often do not harbor sufficient variability to produce representative responses. Indeed, some studies have shown that laboratory populations have lower genetic variability than natural populations (Bian, Gao, Lamberton, & Lu, 2015;Norris, Shurtleff, Touré, & Lanzaro, 2001;Stohler, Curtis, & Minchella, 2004), possibly due to bottlenecks during the establishment and maintenance of the population, or to the long-term adaptation to the same environment, that is, the laboratory conditions (Aguilar et al, 2005;Matos, Rose, Pité, Rego, & Avelar, 2000;Santos et al, 2012;Stohler et al, 2004). However, the lack of representativity of laboratory populations may also be related with the origin and the procedures involved in the creation of such populations (Berthier et al, 2010).…”

“…However, the lack of representativity of laboratory populations may also be related with the origin and the procedures involved in the creation of such populations (Berthier et al, 2010). Natural populations of the same species may be genetically differentiated and/or harbor different genetic compositions, shaped by different geographic and environmental factors (Aguilar et al, 2005;Bian et al, 2015;Langley et al, 2012;Nunes, Neumeier, & Schlotterer, 2008). Thus, laboratory populations founded by individuals collected from a single-field population may not produce representative responses, even if the sample size is enough for the sample to be representative of that population.…”

Exploring molecular variation in Schistosoma japonicum in China

“…Although previous mitochondrial and microsatellite DNA studies 22 23 27 41 42 had provided some insight into population variation in S. japonicum , nucleotide variation was limited 24 25 26 43 , often resulting in relationships with limited statistical support. In this study, our initial aim was to assess the utility of large mitochondrial and nuclear genomic sequence data sets to explore molecular variation within and among populations of S. japonicum .…”

“…Previous population studies of S. japonicum have been limited to relatively small numbers of genetic loci, largely due to a lack of comprehensive genomic sequence data sets for this blood fluke. For instance, microsatellite, mitochondrial (mt) and enzymatic markers were used to reveal genetic variation among isolates of S. japonicum from various regions in China and surrounding, coastal islands 21 22 23 24 25 26 , or to identify genetic bottlenecks in laboratory strains of this parasite 27 . Although these observational studies have been informative, none of them tightly linked genotype to biological traits of the parasite, such as infectivity, pathogenicity and/or immunogenicity.…”