Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Biomphalaria”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed1996

Schistosoma mansoni: the ultrastructure of larval morphogenesis in Biomphalaria glabrata and of associated host-parasite interactions.

An electron microscopic study has been carried out to describe the transformation of the miracidium of S. mansoni into the mother sporocysts in the susceptible B. glabrata and the associated host-parasite interactions. The miracidium enters the snail host without morphological alterations. Within 3 hr after entering, all the ciliary epidermal plates of the miracidium are discarded. A new tegument is quickly formed by 5 hr postinfection by the expansion of epidermal ridges. The rapid formation of the new tegument reflects the participation of membrane-bound vesicles in the ridge cytons. The membranes of these vesicles become the new tegument membranes with the discharge of their electron-dense contents into the snail tissues. The vesicular contents discharged into the tissues apparently prevent snail amoebocytes (phagocytes) from attachment to the parasite tegument and thus prevent their interference with the further development of the postmiracidium. If a postmiracidium fails to mobilize membrane-bound vesicles in the formation of tegument, the parasite becomes surrounded by closely attached concentric layers of fibroblasts formed by amoebocytes and histiocytes within 24 hr. The membrane-bound vesicles are present in small numbers in the ridge cytons of the miracidium and become numerous in the postmiracidium stage and with many migrate to the ridges through connecting bridges within 24 hr. By 3 days postinfection when extensive microvilli have formed on the tegument the vesicles have disappeared and are replaced by mitochondria, ribosomes and complex carbohydrate particles. Many fibroblasts in the snail connective tissues have phagocytic capacities and are regarded as snail tissue histiocytes or fixed amoebocytes that eventually may become hypertrophic and detached.

Animals↗
PubMedDate not supplied

[Host parasite relationship among 3 Schistosoma mansoni and 6 Biomphalaria glabrata strains from epidemic and no epidemic Venezuelan areas is studied].

Six lots of 18 B. glabrata from: La Victoria, Turmero, Cagua in Aragua state; Caserío El 25 in Carabobo state, Chabasquén in Portuguesa state and Humocaro Bajo in Lara state, were experimentally infected with miracidia of SM, C5 and C6 strains of Schistosoma mansoni (18 snails/Schistosoma mansoni strain). The averages of the intramolluscal period (IMP) obtained for the S. mansoni strains were very similar and comprised between 35.4 and 36.1 days. No significative statistical differences in the IMP were found according to the S. mansoni strain and the size of snails: < 7 mm and > 7 mm. However, significative statistical differences in the IMP were found, in relation to the B. glabrata strain and between the snails classified in two groups according to the S. mansoni dose (5 miracidia/snail and 10 miracidia/snail). The higher percentages of infection (PI) were found for the following parasite-snail combinations: C6-Cas. El 25 (80.7%), SM-La Victoria (73.1%) and C5-Cagua (62%). No significative statistical differences were found for the PI a) between the snail classified in two groups according to the size (< 7 mm and > 7 mm), b) in relation to the miracidium dosification (5 and 10 miracidia/snail and c) in accord to the S. mansoni strain. However, significative statistical differences were found for the PI obtained with different strains of the snail.

Analysis of Variance↗
PubMed2001

Dynamic of cercarial production of Schistosoma mansoni in Biomphalaria alexandrina.

The susceptibility of B. alexandrina to infection with S. mansoni miracidia varies due to biological & ecological parameters. In case of snail infection in less than 4 or 5 months productivity doubled between 1 and 2 miracidium, but with more than 2 miracidia with practically no increase in productivity. In more than 5 months, there no was discernible difference in productivity between monomiracidial and polymiracidial infections. The production of cercariae was characterized by very irregular daily emissions and by the alternation of periods of high and low emissions, which gave rise to a production rhythm.

Animals↗
PubMed2001

Effect of double infection with Schistosoma mansoni and Echinostoma liei on some physiological parameters of Biomphalaria alexandrina.

The survival rate and fecundity of B. alexandrina were greatly influenced when exposed to either S. mansoni or E. liei miracidia. The snails exhibited much lower survival rate and fecundity when double exposed to both S. mansoni and E. liei miracidia than single exposure and control snails. The results indicated a disruption in the snail metabolism due to exposure to S. mansoni and E. liei miracidia and this effect was more pronounced in case of double exposure to the two parasites. Protein concentrations in hemolymph and tissues significantly reduced in all exposed snail groups than in the control group. A significant elevation in the levels of aspartate aminotransferase (ASAT) and alanine aminotransferase (Asat) enzymes was recorded in hemolymph and tissues of exposed snail than unexposed (control snails). The ASAT/ALAT ratios in tissue and hemolymph of single-exposed and unexposed B. alexandrina did not exceed 1, while it increased up to 1.18 in hemolymph of double exposed snails. There were significant increases in the levels of acid and alkaline phosphatases enzymes in exposed snails.

Acid Phosphatase↗