RESUMO
Taeniids tapeworms are hermaphroditic helminths that gradually develop testis and ovaries in their reproductive units. The larval stage of the tapeworms named cysticercus is a vesicle that contains the scolex and proliferates asexually in the abdominal cavity of mice. Once in the host, they evaginate, attach to the gut and develop into an adult organism, the tapeworm. We have previously reported reported that T. crassiceps ORF and solium cysticerci transform steroid precursors to androgens and estrogens. Taenia crassiceps WFU cysticerci can also synthesize corticosteroids. The aim of the present work is to investigate the relationship between steroid synthesis ability and the developmental stage of the parasite T. crassiceps WFU. To this purpose, cysticerci were obtained from the abdominal cavity of female mice, manually separated in invaginated (IC) and evaginated parasites (EC) and preincubated for 24â¯h in DMEM plus antibiotics/antimycotics. Next step consisted in incubation for different periods in the fresh media added with tritiated androstenedione (3H-A4) or progesterone (3H-P4) and incubated for different periods. Taenia crassiceps WFU tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were pre-cultured in DMEM plus FBS and antibiotics, and then incubated without FBS for different time periods, in the presence of 3H-A4 or 3H-P4. At the end of the experiments the media from cysticerci and tapeworms were analyzed by thin layer chromatography. Results showed that testosterone synthesis was significantly higher in the evaginated cysticerci and increased with time in culture. The invaginated and evaginated cysticerci also synthesized small quantities of 17ß-estradiol (E2) and estrone. The evaginated cysticerci synthesized twice more 3H-deoxycorticosterone (3H-DOC) than the invaginated parasites, the production increased significantly with time in culture. Taenia crassiceps WFU tapeworms synthesized significant quantities of 3H-testosterone and small amounts of estrone after only 3â¯h of culture in the presence of 3H-A4. The tapeworms also transformed 3H-P4 to 3H-DOC and increased its synthesis after 24â¯h in culture. In summary, our data show the pathways that T. crassiceps WFU cysticerci use to synthesize sexual steroids in both larval developmental stages and reveals the steroidogenic capacity of the tapeworms.
Assuntos
Parasitos/crescimento & desenvolvimento , Esteroides/metabolismo , Androstenodiona/metabolismo , Animais , Cysticercus , Feminino , Camundongos , TaeniaRESUMO
We studied the cyst production of 340 asymptomatic carriers with single or mixed infections of Entamoeba histolytica/Entamoeba dispar, Endolimax nana and Entamoeba coli. It was found that the main source of transmission was a small group of 37 (10.9%) carriers who produced 70.2% of all cysts. Gender was an important factor for cyst production of Ent. histolytica/Ent. dispar, since males produced 6-fold more cysts than females. Females produced 'large' (13-15 microns) Ent. histolytica/Ent. dispar cysts and males small (10-12 microns) cysts when concentration was > 2000 cysts/g. When concentration was < 2000 cysts/g, cysts were the same size for both sexes (11.6 +/- 0.3 microns). In Ent. coli infections, an inverse relationship between the number and size of cyst was found for both sexes. Cysts of End. nana were not affected by gender or cyst concentration. Following cyst production by a carrier infected with Ent. coli and Ent. histolytica for 28 days, we identified synchronized cycles of cyst production for both species. Altogether, these data suggest that cyst-mediated transmission is a highly regulated process in which synchronization among different species and gender of the host have an important role in transmission.
Assuntos
Amebíase/transmissão , Doenças do Colo/parasitologia , Endolimax , Entamoeba histolytica , Enteropatias Parasitárias/transmissão , Animais , Entamebíase/transmissão , Fezes/parasitologia , Feminino , Seguimentos , Humanos , Masculino , Caracteres SexuaisRESUMO
Formalin fixation is the most common storage, transportation and preservation method for stool samples. However, fixation dramatically reduces our ability to extract from stool samples DNA that is a suitable template for polymerase chain reaction (PCR)-based diagnostic tests. In this study we evaluated the effects of formalin concentration and of the time stored in fixative on the success of PCR amplification. We found that the deleterious effects of formalin are both time and concentration dependent and may result from fragmentation of fixed DNA during its purification.