Intake of Erythrocytes Required for Reproductive Development of Female Schistosoma japonicum

Abstract

The reproductive development and maturation of female schistosomes are crucial since their released eggs are responsible for the host immunopathology and transmission of schistosomiasis. However, little is known about the nutrients required by female Schistosoma japonicum during its sexual maturation. We evaluated the promoting effect of several nutrients (calf serum, red blood cells (RBCs), ATP and hypoxanthine) on the reproductive development of pre-adult females at 18 days post infection (dpi) from mixed infections and at 50 dpi from unisexual infections of laboratory mice in basic medium RPMI-1640. We found RBCs, rather than other nutrients, promoted the female sexual maturation and egg production with significant morphological changes. In 27% of females (18 dpi) from mixed infections that paired with males in vitro on day 14, vitelline glands could be positively stained by Fast Blue B; and in 35% of females (50 dpi) from unisexual infections on day 21, mature vitelline cells were observed. Infertile eggs were detected among both groups. To analyze which component of mouse RBCs possesses the stimulating effect, RBCs were fractionated and included in media. However, the RBC fractions failed to stimulate development of the female reproductive organs. In addition, bovine hemoglobin hydrolysate, digested by neutral protease, was found to exhibit the promoting activity instead of untreated bovine hemoglobin. The other protein hydrolysate, lactalbumin hydrolysate, exhibited a similar effect with bovine hemoglobin hydrolysate. Using quantitative RT-PCR, we found the expression levels of four reproduction-related genes were significantly stimulated by RBCs. These data indicate that RBCs provide essential nutrients for the sexual maturation of female S. japonicum and that the protein component of RBCs appeared to constitute the key nutrient. These findings would improve laboratory culture of pre-adult schistosomes to adult worms in medium with well-defined components, which is important to investigate the function of genes related to female sexual maturation.

Systematically improved in vitro culture conditions reveal new insights into the reproductive biology of the human parasite Schistosoma mansoni

“…ImageJ was used to quantify egg size, autofluorescence, and number of nuclei from images of eggs acquired on a Nikon A1+ laser scanning confocal microscope (Nikon, Tokyo, Japan). Like previously described diazo salts [55,56], Fast Blue BB strongly labeled the polyphenol-rich vitelline droplets of mature vitellocytes and could be visualized by bright-field microscopy as a deep red stain. Fast Blue BB could also be visualized by confocal microscopy by excitation with a 561-nm laser.…”

Dynamic transcriptomes identify biogenic amines and insect-like hormonal regulation for mediating reproduction in Schistosoma japonicum

“…For Fast Blue B staining, female worms were fixed in 70% ethanol for ≥24 h. After staining with filtered 1% (w/v) Fast Blue B solution, they were dehydrated through an ethanol gradient from 70 to 100%, and then mounted in neutral balsam (Sinopharm Chemical Reagent Co., Ltd, China) 66 . Staining of vitelline cells was evaluated using light microscopy (Nikon NI-SS, Japan).…”

Hematological Implications of Schistosomiasis: Experimental and Clinical Review

“…Schistosomes are exclusive blood feeders, and it is estimated that female S. mansoni worms can ingests approximately 330000 erythrocytes per hour and the ingested red cells are lysed in the gastrodermis to enable the parasites to digest hemoglobin 21 . RBCs provide essential nutrients for the sexual maturation of female S. japonicum 22 . The impact of schistosomiasis on the hematological profile was reported in experimental animals [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] and clinically in human 39-58 but none of them detailed the effect of this devastating disease on all blood cells collectively.…”