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At least 793 records · Page 44Linked to original sources
PubMed1982

Effects of starvation and infection with Schistosoma mansoni on the release rate of free amino acids (FAA) by Biomphalaria glabrata.

1. The elimination of dissolved free amino acids (FAA) by individual snails during a period of 2 hr was measured. The FAA concentration in the hemolymph and in the homogenate also was determined. 2. For uninfected, normally fed snails a daily FAA production of 0.7 +/- 0.25 mumol glycine equivalents/g live wt was found. With snails starving for 7 days the daily FAA release rate fell to a mean value of 0.44 +/- 0.19 mumol glycine equivalents/g live wt. Infection with Schistosoma mansoni, however, induced higher FAA loss with an average of 1.72 +/- 1.07 mumol glycine equivalents/g live wt/day. 3. The FAA concentration in the homogenate of both starved and infected B. glabrata was significantly reduced by comparison to the levels found for normally fed snails. 4. A clear drop in FAA concentration was found in the hemolymph of starved and infected snails, respectively. 5. The FAA concentrations in the hemolymph and the homogenate of parasite-bearing snails does not differ significantly from the results found for starved snails. By contrast, the FAA release of infected B. glabrata significantly increased in comparison to that of the starved snails.

Amino Acids↗
PubMed1983

Purine metabolism in Biomphalaria glabrata under starvation and infection with Schistosoma mansoni.

Purine content and its alterations during a starvation period of 29 days and an infection period of 52 days were studied. During starvation the amount of uric acid increased from 2.11 +/- 0.95 mg/g dry wt in control snails to a maximum of 6.73 +/- 3.99 mg/g dry wt on day 29 of starvation for uric acid and from 4.73 +/- 2.10 mg/g dry wt in control snails to a maximum of 11.29 +/- 3.48 mg/g dry wt on day 23 of starvation for guanine. During infection there was an increase with both uric acid and guanine to maximum on day 40 post infection (7.17 +/- 3.51 mg/g dry wt for uric acid, 14.83 +/- 4.53 mg/g dry wt for guanine) and a decrease afterwards. Of all the snails' organs tested, only in the kidney were purines detectable, but it was impossible to find excreted purines.

Animals↗
PubMed1992

Proteinase inhibitory activity in the plasma of a mollusc: evidence for the presence of alpha-macroglobulin in Biomphalaria glabrata.

1. A methylamine-sensitive inhibitor was present in the plasma of B. glabrata. 2. This inhibitor decreased trypsin activity against a protein substrate, however trypsin retained activity against a low molecular weight substrate in the presence of the inhibitor. 3. Snail plasma protected trypsin from inhibition by soybean trypsin inhibitor. 4. The results give evidence for an alpha-macroglobulin proteinase inhibitor in the plasma of this gastropod mollusc.

Animals↗
PubMed2006

Effect of Angiostrongylus vasorum infection on Biomphalaria tenagophila susceptibility to Schistosoma mansoni.

Concomitant infection with different parasites may be a helpful laboratorial strategy leading to the better understanding of the mechanisms used by the internal defense system (IDS) of Gastropoda to deal with helminth infection, such as Schistosoma mansoni. This work reports the effect of co-infection of Angiostrongylus vasorum and S. mansoni in hemocyte activity and in the outcome of infection. The simultaneous infection resulted in an increase of snail susceptibility to S. mansoni. In contrast, snails infected with both parasites, 15 days apart, did not show differences in the susceptibility compared to a single parasite infection. The increased susceptibility was measured by the significantly higher number of migrating sporocysts, higher percentage of snails shedding cercariae, higher number of cercariae shed and higher mortality in the experimental group that were simultaneously infected with A. vasorum and S. mansoni, when compared to snails infected only with S. mansoni. Snails simultaneously infected with A. vasorum and S. mansoni showed lower hemocyte activation during the first few days of infection, compared to activation induced only by A. vasorum infection. Between 5 and 15 days post-infection (dpi), granulocyte number and nitric oxide (NO) contents of simultaneously infected snails were lower than the S. mansoni-infected snails. Based on the results, we suggest that differences in the level of hemocyte response could explain the increased S. mansoni susceptibility observed in snails simultaneously infected with both parasites. However, when S. mansoni infection occurred after A. vasorum larvae are completely encapsulated, the response against S. mansoni was not altered, and therefore there were no differences in the susceptibility level.

Angiostrongylus↗
PubMed2001

Use of satellite remote sensing and geographic information systems to model the distribution and abundance of snail intermediate hosts in Africa: a preliminary model for Biomphalaria pfeifferi in Ethiopia.

Geographic information system (GIS) risk models for the snail-borne diseases caused by Schistosoma spp. and Fasciola spp. have recently been developed based on climate and satellite-retrieved data on temperature and vegetation coverage. By using these models, it was possible to describe a relationship between vegetation index (Normalized Differences Vegetation Index (NDVI)), land surface temperature (T(max)) and disease prevalence, but little reference was made to the distribution of the corresponding intermediate host snail. Presence of the intermediate host snail is a key factor determining distribution of the disease in sub-Saharan Africa and a good snail distribution mode would probably mirror the endemic area of schistosomiasis. In the present analysis, it was shown that snail distribution data corresponds with schistosomiasis prevalence data in relation to a forecast model based on NDVI and T(max) data derived from the Advanced Very High Resolution Radiometer (AVHRR) onboard the National Oceanic and Atmospheric Administration satellite series. The 'best fit' model included NDVI values from 125 to 145 and a T(max) data range of 10-32 degrees C. This model included 92.3, 90.4 and 94.6% of the positive snail sample sites in GIS query overlay areas extracted from annual, dry season and wet season composite maps, respectively. For other sites in Africa, other NDVI and T(max) ranges may be more appropriate, depending on the species of snail present, a topic that will be examined in further studies.

Africa↗
PubMed2002

Toxicity of lapachol and isolapachol and their potassium salts against Biomphalaria glabrata, Schistosoma mansoni cercariae, Artemia salina and Tilapia nilotica.

The toxicity of soluble derivatives (potassium salt) of lapachol and isolapachol in different stages of the life cycle of Schistosoma mansoni is evaluated. The potassium salts of isolapachol and lapachol showed significant molluscicidal activity against the adult snail (LC90<7 ppm) and snail egg masses (LC90<3 ppm). Cercaricidal assays revealed strong activities for both compounds. Lethality assays against brine shrimp eggs (Artemia salina Leach) indicated very high toxicity for the potassium salt of isolapachol (LC90=1.54 ppm), differently from the potassium salt of lapachol that can be considered non toxic (LC90=176.3 ppm). The same tendency is observed with piscicidal activity, for which the isolapachol salt has showed higher toxicity. The obtained selectivity ratios concerning LC50 and LC90 for lapachol, in relation to Tilapia nilotica lethality assay are 2.33 and 1.26, respectively. Despite the piscicidal toxicity, the use of the salt of lapachol can be recommended for field tests in Schistosomiasis, with caution.

Animals↗