Microhabitat Differences in the Benthic Substrata Affect Parasitism in a Pulmonate Snail Host, Helisoma anceps

2016 ◽  
Vol 102 (3) ◽  
pp. 306 ◽  
Author(s):  
Michael R. Zimmermann ◽  
Kyle E. Luth ◽  
Gerald W. Esch
Keyword(s):  
Snail Host ◽  
Pulmonate Snail ◽  
Helisoma Anceps

Uptake and assimilation of short chain carboxylic acids by Biomphalaria glabrata (Say), the freshwater pulmonate snail host of Schistosoma mansoni (Sambon)

1984 ◽  
Vol 222 (1229) ◽  
pp. 447-476 ◽  
Keyword(s):  
Carboxylic Acids ◽  
High Performance ◽  
Biomphalaria Glabrata ◽  
Food Supplement ◽  
Snail Host ◽  
The Body ◽  
Short Chain ◽  
Pulmonate Snail ◽  
Interstitial Waters ◽  
Freshwater Pulmonate Snail

The use of radiolabelling and high performance liquid chromatography (h. p. l. c. ) has shown that the freshwater pulmonate snail Biomphalaria glabrata can achieve a net uptake of short chain carboxylic acid (C 2 -C 4 ) from the medium, and also metabolize them. This appears to be the first time that this phenomenon has been reported for a freshwater invertebrate. The uptake characteristics for acetate and butanoate conform to the Michaelis-Menten model. The transport constants,V max (in micromole equivalents per gram of wet mass per hour) and K s (in micromoles per litre) for acetate (1005 and 2.29 respectively) and butanoate (129 and 1.29 respectively) are similar to those obtained by other workers for marine, detritivorous, polychaete worms. Evidence is given that the carboxylic acids are transported through the body wall, and not taken up to any significant extent by microorganisms or absorbed on the surface mucus. The acids are metabolized by the snail after accumulation, as shown by the appearance of label in respiratory CO 2 and the decline in the mass-specific accumulation rates (m. s. a. r. ), in micromole equivalents per gram of mass per hour, to an asymptote during the course of a 4 h incubation period. Differences in m.s.a.r. values for [1- 14 C]- and [2- 14 C]acetate probably reflect the different fates of the two carbons during metabolism. The m. s. a. r. values are influenced by the metabolic state of the snails. Thus they increase in response to food deprivation and decrease under anoxic conditions. However, as snails continue to accumulate acetate from the medium, even when well fed, or ‘preloaded ’ with acetate, it is clear that this acid is not being used solely as a food supplement. Estimates of the contributions that C 2 and C 4 acids might make to the basal metabolism of the snails have been made using the following param eters: (i) the range of concentrations of these acids in microhabitats, such as the interstitial waters in surface sediments, and an experimentally decayed macrophyte, Lemna paucicostata (ii) transport constants of the carboxylic acids taken up by the snails; (iii) the respiration rates of the snails. It was calculated that the acetate in interstitial waters can contribute only a negligible amount (less than 6%) of the snail’s basal metabolic rate (b. m. r. ). However, if the snails encountered the concentrations of 2250 μm and 400 μm of acetate and butanoate respectively found in supernatant from laboratory decaying Lemna , then each acid could provide more than 50% of the snails’ b. m. r. The significance of these results to the behavioural and chemical ecology of the snails is discussed.

Effect of Parasitism on the Growth Rate of the Pulmonate Snail Helisoma anceps

1991 ◽  
Vol 77 (6) ◽  
pp. 937 ◽  
Author(s):  
Jacqueline Fernandez ◽  
Gerald W. Esch
Keyword(s):  
Growth Rate ◽  
Pulmonate Snail ◽  
Helisoma Anceps

Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

1989 ◽  
Vol 47 ◽  
pp. 962-963
Author(s):  
Betty Ruth Jones ◽  
Steve Chi-Tang Pan
Keyword(s):  
Nervous System ◽  
Life Cycle ◽  
Schistosoma Mansoni ◽  
Snail Host ◽  
Complex Life Cycle ◽  
Rational Approach ◽  
Effective Control ◽  
The Social ◽  
Social And Economic Development ◽  
Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

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