Fig 1.
Pictures of typical Biomphalaria habitat in Guangdong.
(A) River in the Xinzhou road. (B) Xixiang River and collecting snails. (C) Guanlan river and citizens playing with water. (D) Donghu park and citizens playing with water. (E) and (F) Biomphalaria snails in the field. (G) Captured Biomphalaria snails with RBS and BBS.
Fig 2.
The distribution of B. straminea in Dongguan, Shenzhen, Huizhou Puning and Hong Kong Cities.
Major cities and all investigated sites (positive and negative for B. straminea) were marked on the map. Green dots: negative sites; Red squares: sites found B. straminea. This map was created using ArcGIS.
Fig 3.
Fast expanding and distribution of red B. straminea studies in Shenzhen.
(A) maps of RBS in Guangdong province and Hong Kong area in China. (B) 2015 (C) 2016 (D) 2018. Red area indicates occurrence of RBS and relates to the highest density in district. These maps were created using ArcGIS.
Fig 4.
Density shifts in wild populations of red B. straminea in Guangdong province.
(A) Relation between density and latitude. (B) Relation between density and longitude. (C) Density changes since 2014. (D) Density changes since 2016.
Fig 5.
Morphological and phylogenetic features of B. straminea collected in fields and kept in laboratory.
(A) Picture of B. straminea snails, upper: black colored snail; down: red colored snail. (B) Example of PCR amplifying S. mansoni specific 18S rRNA sequence extracted from field captured B. straminea (Lane 1–4), laboratorial cultured B. straminea (Lane 5), negative control (Lane 6) and adult worms of S. mansoni (Lane 7). Lane 8: 210 bp marker. (C) Neighbour-joining tree constructed based on K2P+G model for 18S rRNA sequences of B. straminea samples collected from different sites in south China. (D) Neighbor-joining tree constructed based on K2P+G model for cox1 sequences of B. straminea samples collected from different sites in South China.
Fig 6.
Biological features of BBS and RBS.
(A) Configuration and size of wild Biomphalaria snails. (B) Prostate diverticula of field-captured Biomphalaria snails. (C) Growth rates between BBS and RBS reared in lab.
Fig 7.
Phylogenetic relationship of B. straminea species collected from field.
(A) Hybridization results of RBS and BBS. (B) Genes differentiated in melanin synthetic pathway of BBS comparing to F2RBS in transcriptomes, 0/5: 0 out of 5 tyrosine hydroxylase were up-regulated; 5/48: 5 out of 48 tyrosinase were up-regulated. Numbers in box behind represent the folds of up-regulation. (C) RT-PCR results of 10 different genes with tyrosinase (TYR) domain in BBS comparing to RBS.
Fig 8.
The susceptibility of B. straminea to S. mansoni.
(A) Selection procedures of susceptible RBS. (B) Positive rates of B. glabrata, different generations (F0, F1, F2) of RBS and BBS infected by S. mansoni. (C) Cercariae (top), adult worms (middle) and HE stained pathological sections (mice liver) (down) of S. mansoni derived from both B. straminea and B. glabrata. (D) Analysis of differentiated expressed genes (DEGs) involved in the complementary system of BBS (black B. straminea) when comparing to F2RBS (F2 generation of selected red B. straminea). Left panel, expression levels (Log2FC) of DEGs involved in complementary system of BBS when comparing to RBS in transcriptome. Right panel, RT-PCR results of DEGs involved in complementary system of BBS when comparing to F2RBS. FREM: fibrinogen-related molecule. Bio-1: biomphalysin like protein 1, BPI-2: bactericidal permeability-increasing protein 2, Bio-2: biomphalysin like protein 2, MPEP: macrophage expressed protein.