Oxygen-binding characteristics of the haemolymph of the freshwater snailBulinus (Physopsis) globosus

Ecology of freshwater snails in south-western Nigeria. I: Distribution and habitat preferences

“…Thus, the pulmonates G. costulatus, B. globosus, L. natalensis and P. waterloti which possess vascularised mantles with which they can acquire atmospheric oxygen for respiration were most frequently encountered in organically polluted water bodies. In the case of B. globosus, this is not surprising since it has been shown (Van Aardt & Frey, 1981) that the oxygen retention capacity of its haemoglobin like that of Biomphalaria sudanica (Jones, 1964) is very high thus making it well suited for life in water bodies having low oxygen concentrations. Observations by Van Emden et al (1974) that B. glabrata can survive an exposure of LC 100 24 h to detergents for up to 20 h and that biodegradable products of detergents in concentrations of up to 100 mg 1-' have no influence on its mortality would appear to account for the high frequency of occurrence of the closely related B. pfeifferi during the present study in water bodies polluted with soaps and detergents.…”

Effects of buffer composition, pH and temperature on oxygen binding by planorbid snail haemoglobins

“…The snail buffer used for most of the experiments closely resembles the haemolymph of snails regarding the ionic strength and electrolyte composition (Van Aardt & Coertze 1981). When using this buffer the P 50 value at 25°C and at a pH of 8,0, which is the normal pH of the haemolymph (Van Aardt & Frey 1981) is between 5,3 and 6,3 mmHg for each of the three species namely B. glabrata, B. africanus and B. tropicus (Table 2).…”

“…Determinations of the molecular masses of planorbid haemoglobins (Figueiredo, Gomez, Heneine, Santos & Hargreaves 1973;Almeida & Neves 1974;Wood & Mosby 1975;Afonso, Arrieta & Neves 1976;Nacimento, Daniel & Heneine 1982) show a sedimentation COefficient, S20•W• between 34,8 and 35,0 and a molecular mass of 1,65 x 10 6 ± 0,04. Functional studies on the haemoglobins of planorbid snails with the aid of tonometric devices (Jones 1964;Figueiredo et al 1973;Wood & Mosby 1975;Terwilliger, Terwilliger, Bonaventura & Bonaventura 1977;Van Aardt & Frey 1981;Nacimento et al 1982;Terwilliger & Terwilliger 1982) show that the Bohr-effect is absent or weakly developed with a high affinity of the molecule for oxygen and a value for the Hill coefficient, n, of between 1,08 and 3,4. Lapennas, Colacino & Bonaventura (1981) pointed out that thin-layer methods for the study of haemoglobin-oxygen binding offer many advantages over classic tonometric methods -the most important being speed, small sample size and gentle treatment of the sample.…”