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PubMed1981

An isoenzyme marker possibly associated with the susceptibility of Biomphalaria glabrata populations to Schistosoma mansoni.

Nine laboratory populations and one field population of the snail host Biomphalaria glabrata were compared with respect to their electrophoretic patterns for acid phosphatase (AcP) and with their susceptibility to Schistosoma mansoni infection. A strong correlation (r = 0.98) was noted between the frequency of the isoenzymes AcP2-S and Acp2-F observed in the populations and the level of snail susceptibility as determined by bioassay. The isoenzyme AcP2-S was associated with susceptibility, AcP2-F with the refractory state. Breeding experiments between refractory and susceptible snails demonstrated that the refractory state was dominant and all F1 snails exhibited the AcP2-F isoenzyme and proved refractory to infection.

Acid Phosphatase↗
PubMed1983

Altered feeding response as a cause for the altered heartbeat rate and locomotor activity of Schistosoma mansoni-infected biomphalaria glabrata.

Biomphalaria glabrata infected with Schistosoma mansoni for 33 days fed more often than uninfected snails. Whereas uninfected snails had nocturnal increases in feeding, snails with a 33-day-old infection of S. mansoni fed as often during the day as in the night. Using direct observation and film analysis, we found that feeding increased the heartbeat rate and locomotor activity of B. glabrata. When snails were allowed to feed ad lib., infected snails had higher heartbeat rates than uninfected snails both during the day (P less than 0.01) and the night (P less than 0.001). However, when the snails were deprived of food for 24 hr, infected snails had slightly higher heartbeat rates than uninfected snails only during the day (P less than 0.05). There was no difference between the heartbeat rates of feeding, infected snails and the heartbeat rates of uninfected snails that were starved for 8 hr, and then allowed to feed. Uninfected snails had nocturnal increases in heartbeat rate regardless of feeding schedule, but infected snails had greater nighttime heartbeat rate than daytime heartbeat rate only when they were not allowed to feed. Infected snails had less nocturnal locomotor activity than uninfected snails when feeding, but there was no difference between the locomotor activity of infected and uninfected snails when the snails were deprived of food for 24 hr. Absence of food also resulted in an increased nighttime to daytime ratio of locomotor activity of infected snails. These results suggest that the increased heartbeat rate and altered rhythms of heartbeat rate and locomotor activity in B. glabrata infected with S. mansoni for 33 days were caused by the altered feeding response of these snails.

Animals↗
PubMed1983

Effects of alterations in the heartbeat rate and locomotor activity of Schistosoma mansoni-infected Biomphalaria glabrata on cercarial emergence.

During a 27-hr period of food deprivation, Biomphalaria glabrata infected with Schistosoma mansoni had lower heartbeat rates and locomotor activities than did controls that were feeding ad lib. However, there was no difference between the cercarial emergence from control and experimental snails either before, during, or after the period of food deprivation. No correlation was found between the locomotor activity of the snail and the number of cercariae emerging from the snail in continuous light. Our results indicated that the emergence of S. mansoni cercariae from B. glabrata was not affected by the heartbeat rate or locomotor activity of the snail. The factors controlling the rhythm of S. mansoni cercarial emergence from B. glabrata may be independent of the snail.

Animals↗
PubMed1983

Chronic exposure of the eggs and adults of Biomphalaria glabrata (Say) to the molluscicide, nicotinanilide.

Some effects of chronic, low-dosage treatment of Biomphalaria glabrata eggs and adults with nicotinanilide, are reported. The susceptibility of eggs decreased with age. The development and hatching of 0-1 day old eggs could be prevented by continuous exposure to 0.0005-0.001 mg/l-1 whereas prehatch stages had a susceptibility similar to that of adult snails (0.1-0.2 mg/l-1). The possible use of slow-release formulations of nicotinanilide in the control of field populations of snails and schistosomiasis transmission is discussed.

Aging↗
PubMed1983

Lysosomal enzyme activities in susceptible and refractory strains of Biomphalaria glabrata during the course of infection with Schistosoma mansoni.

The distribution and abundance of the lysosomal enzyme markers, acid phosphatase (AP), peroxidase (PO), and nonspecific esterase (NE), within circulating blood cells (hemocytes) were examined in a schistosome-susceptible (PR albino M-line) and a resistant (10-R2) strain of Biomphalaria glabrata during the course of infection with Schistosoma mansoni. The dynamics of serum (cell-free hemolymph) AP activities and total hemocyte numbers in infected snails also were investigated. Hemocyte subpopulations, as determined by these enzyme markers, responded differently to parasite infection between snail strains. Generally, the hemocyte subpopulations within PR albino snails remained largely unchanged, whereas the same subpopulations in 10-R2 snails fluctuated considerably. The distribution of AP in the hemocytes of 10-R2 snails decreased by 1 hr postexposure (PE) to the parasite and remained low through 12 hr before increasing to control values at 24 hr and 2 wk PE. In comparison, PO activity increased by 1 hr PE and peaked at 12 hr before dropping to 0 hr values by 2 wk PE. The NE activity exhibited still another pattern with the percentage of NE-positive cells decreasing from 0 to 12 hr PE followed by a recovery to 0-hr values by 24 hr. The abundance of these hemocyte enzymes followed a similar pattern to that of their distribution, although some differences were observed. Serum AP values varied little in PR albino snails except for a significant increase at 2 wk PE, indicating a possible response to tissue damage resulting from migrating daughter sporocysts.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1984

Equations for describing growth of the schistosome host snail Biomphalaria glabrata.

Biomphalaria glabrata and Stagnicola palustris were raised in aquaria under crowded and uncrowded conditions. Measurements of greatest shell diameter were taken at regular intervals. Von Bertalanffy and logistic growth curves were fitted by least squares and maximum likelihood methods. The resulting parameter estimates produced better fits for the logistic equation than for the von Bertalanffy equation.

Animals↗
PubMed1982

Properties of glycogen synthase and phosphorylase from Biomphalaria glabrata (mollusca).

Glycogen synthase and phosphorylase were characterized from the cephalopedal region of the snail, Biomphalaria glabrata. Glycogen synthase exhibited increases and decreases in its activity ratio (-G6P/+G6P) under conditions that are known to cause conversion of the two forms of the enzyme from mammalian systems, implying that the snail's synthase also possesses interconvertible forms. Each form had a distinct pH optimum, with the G6P-independent form (synthase alpha) exhibiting maximum activity at pH 7.4, whereas the G6P-dependent form (synthase beta) had optimal activity at pH 8.3. Both synthase alpha and beta displayed classical Michaelis-Menten kinetics for the substrates UDP-glucose and glycogen, and the beta form displayed sigmoidal kinetics for its modulator, G6P. Only UDP-glucose could function as a glucosyl donor in the synthase-catalyzed reaction. ADP, GDP, UDP, and ATP were all competitive inhibitors of synthase alpha, although at varying degrees of efficiency. Glycogen phosphorylase also demonstrated interconversion of its two forms (alpha and beta), as evidenced by changes in its activity ratio (-AMP/+AMP). AMP elicited hyperbolic kinetics from this enzyme. Concentrations of KF above 20 mM were found to inhibit glycogen synthase alpha while stimulating phosphorylase beta, thus causing erroneous activity ratios for both enzymes.

Animals↗
PubMedDate not supplied

[Report on the collection of nests of Biomphalaria spp in the laboratory].

A simple method for counting, observing and collecting eggs of three Biomphalaria species kept under culture is reported. The advantages of the method in statistical studies and in the case the nest is to be isolated in order to follow its behavior according to age, etc., are exposed.

Animals↗
PubMed1982

Ultrastructure of encapsulation of Schistosoma mansoni mother sporocysts by hemocytes of juveniles of the 10-R2 strain of Biomphalaria glabrata.

Dynamic aspects of the cellular responses of juvenile (2-3 mm shell diameter) 10-R2 strain Biomphalaria glabrata to newly penetrated Schistosoma mansoni (NIH-Sm-PR-1 strain) were studied at the ultrastructural level. As early as 3 hr postexposure (PE), host hemocytes had contacted the parasite's surface and by 7.5 hr, had phagocytosed sporocyst microvilli and small pieces of underlying tegument. Most sporocysts observed at 24 hr PE lacked tegumental cytoplasm, and germinal cells and other internal structures showed extensive pathological changes. By 48 hr, capsules were filled with hemocytes containing numerous, large phagosomes, and only scattered remnants of sporocyst material remained. Capsules were difficult to find at 4 days PE, suggesting that hemocytes participating in the encapsulation response had dispersed. Hemocytes responsible for the rapid and consistent destruction of S. mansoni sporocysts in the head-foot region typically formed extensive pseudopodia and contained large numbers of lysosomelike bodies, characteristics associated with granulocytes of B. glabrata. No evidence was found to suggest that hemocytes were lysed, or formed multinuclear syncytia, during the encapsulation response.

Animals↗
PubMed1982

Further characterization of acquired resistance in Biomphalaria glabrata.

The albino strain of Biomphalaria glabrata is capable of developing an acquired resistance to echinostomes that is relatively specific, i.e., strong against Echinostoma lindoense, challenged by the homologous species, moderate or weak against closely related E. paraensei and E. liei, and nonexistent against Paryphostomum segregatum and Schistosoma mansoni. The present results show that acquired resistance induced by E. paraensei is much stronger against the heterologous E. lindoense than against the homologous species. These observations indicate that although the response of snails with acquired resistance to a challenge exposure is relatively specific, the stimuli for inducing that resistance may be nonspecific.

Animals↗
PubMed1982

Case reports on control of Biomphalaria pfeifferi snails with Phytolacca dodecandra berries.

Three case reports are given on the control of Biomphalaria pfeifferi, the intermediate snailhost of Schistosoma mansoni, occurring in the highlands of Ethiopia. Control was effected by applying Phytolacca dodecandra berry suspensions on two different rivers. A method of application by siphoning the suspension into the river is described. Both rivers were densely populated with B. pfeifferi, but with only 2.5-3.5 kg of berries their presence could be reduced to almost nil. Except for fish, the water fauna was not affected. However, 4 weeks after treatment fish were again present.

Animals↗
PubMedDate not supplied

[Life cycle of Clinostomum golvani n. sp. (Trematoda : Clinostomidae) a larval parasite of Biomphalaria glabrata, the snail vector of Schistosoma mansoni in Guadeloupe (author's transl)].

The life cycle of a new species of Clinostomidae, Clinostomum golvani, described in Guadeloupe (French West Indies). The first intermediate host is the snail vector of Schistosoma mansoni in this island, Biomphalaria glabrata, which can be sterilized by this parasite. Poecilia reticulata (guppy) serves as the second intermediate host. Adult worms were obtained under experimental conditions from Butorides virescens (the definitive host in nature), Nycticorax nycticorax and Ardea purpurea. The adult worm closely resembles Clinostomum complanatum but the larval stages (rediae and cercaria) show several differences. The chaetotaxic description of a cercaria of Clinostomidae is given for the first time.

Animals↗
PubMed1978

Differential susceptibility of Biomphalaria tenagophila populations to infection with a strain of Schistosoma mansoni.

Experiments to determine the susceptibility of Biomphalaria tenagophila from 20 localities over the species range exposed to a strain of Schistosoma mansoni showed widely varying infection rates, from 0% to 91.5%, this latter having been observed in a sample from an area where the natural infection rate of B. tenagophila has been the highest in the country. Comparison with similar studies involving B. glabrata seems to indicate that a process of adaptation between S. mansoni and B. tenagophila is evolving, the 2 organisms having reached a high degree of compatibility in a few areas. The present results point to the possibility of expansion of schistosomiasis to a wide South American area where B. tenagophila occurs.

Adaptation, Biological↗
PubMed1981

Schistosoma mansoni, NIH-SM-PR-2 strain, in susceptible and nonsusceptible stocks of Biomphalaria glabrata: comparative histology.

Of 10 inbred stocks of Biomphalaria glabrata examined, eight were susceptible to the NIH-Sm-PR-1 strain (PR-1) of Schistosoma mansoni, whereas only three were susceptible to the NIH-Sm-PR-2 strain (PR-2). By employing a histological ranking system based on parasite development and host tissue response, we have observed a range of nonsusceptibility among stocks nonsusceptible to PR-2. In three nonsusceptible stocks, sporocysts were rapidly surrounded by host amebocytes and were destroyed within a few days. However, in four other nonsusceptible stocks, sporocysts were surrounded by only a minimal host reaction and some sporocysts persisted for at least 3 weeks. Nondevelopment of sporocysts in these four stocks may result from biochemical unsuitability or a weak from of resistance in the host. Parasite development and host tissue response also varied among three stocks of snails that were susceptible to PR-2. In two susceptible stocks, most PR-2 sporocysts developed normally, and the small proportion that underwent degeneration elicited no host cellular response within the first week of infection. However, in a third susceptible stock, most sporocysts were surrounded by a minimal host reaction and very few appeared to develop normally.

Animals↗
PubMed1981

Selective interference with granulocyte function induced by Echinostoma paraensei (Trematoda) larvae in Biomphalaria glabrata (Mollusca).

Various trematode larvae can interfere with the host snail's resistance to the same or unrelated trematode species, chiefly, it appears by interference with the function of the host's granulocytes. In Biomphalaria glabrata infected with the trematodes, Echinostoma paraensei, granulocytes lose their ability to encapsulate the larvae of trematodes to which the hosts were previously resistant. However, the granulocytes in these snails retain their ability to encapsulate injected latex spheres, or larvae of the metastrongyle nematode, Angiostrongylus malaysiensis, and to phagocytose epidermal plates cast off by miracidia of the trematode, Schistosoma mansoni. Cellular infiltration in injured preputial tissue of the snail also was not suppressed by the presence of E. paraensei larvae. Interference with the granulocyte function in B. glabrata induced by E. paraensei infection therefore appears to be a selective phenomenon.

Angiostrongylus↗
PubMed1980

Macrophagelike hemocytes of resistant Biomphalaria glabrata are cytotoxic for sporocysts of Schistosoma mansoni in vitro.

When Schistosoma mansoni miracidia penetrate resistant individuals of the intermediate host snail Biomphalaria glabrata, the sporocyst is encapsulated by hemocytes (macrophagelike cells of the snail circulation) and killed. In our in vitro model the same fate requires only sporocysts and snail hemolymph. However, when cultured in plasma alone (cell-free hemolymph), sporocysts remain viable for more than 3 days, regardless of whether the plasma is from susceptible or resistant snails. When hemolymph is used from susceptible snails, the sporocysts retain a normal healthy appearance. Furthermore, the parasite appears to express an offensive response to the hemocytes of susceptible snails. Ultrastructural study reveals that resistant-strain hemocytes destroy the parasite tegument; within 24 hr the sporocyst is damaged severely throughout. This cell-mediated, internal, defensive response of an invertebrate host closely resembles antibody-dependent, cell-mediated damage to schistosomula in mammalian hosts.

Animals↗
PubMed1980

Echinostome cercarial penetration and metacercarial encystment as mortality factors for a second intermediate host, Biomphalaria glabrata.

Cercarial penetration and metacercarial encystment of Echinostoma liei in Biomphalaria glabrata caused high mortality of juvenile snails (3-8 mm in diameter) after 4 to 6 days of continuous exposure to about 150 cercariae per snail per day. Larger snails (10-13 mm) withstood cercarial penetration longer, significant mortality appearing 16 days after exposure. Life-table analysis showed that the snail mortality rate per age interval increased with increasing exposure to echinostome penetration. Single exposures of 3- and 6-mm snails to 500 cercariae caused 97% mortality for the former and 84% for the latter within 2 days. Snails surviving the first 2 days did not suffer further mortality when infected with as many as 488 metacercariae. Thus, mortality seems to result from penetration and early stages of encystment, rather than the presence of large numbers of metacercariae in the pericardial region. Growth of 3-mm snails exposed to 10 or 100 cercariae and of 6-mm snails to 500 cercariae was significantly less than the growth of unexposed controls after 20 days. Cercariae rapidly located the snails, 90% penetrating within 1 hr when individual, 6-mm snails were exposed to 100 cercariae in 5 ml of water. The high rate of cercarial penetration needed to cause snail mortality suggests that echinostome penetration and encystment will not cause much mortality of snail intermediate hosts in nature unless the density of echinostome cercariae is high.

Animals↗
PubMedDate not supplied

[Cellular immunity in mollusk hosts of schistosomes. Primary results regarding Biomphalaria glabrata].

Cell culture are obtained from the saccular part of the kidney of Biomphalaria glabrata in a medium derived from Schneider drosophilia medium. Two types of cells migrate from the explant: numerous amoebocytes and some fibroblasts. Migration of amoebocytes appears to be regular. These amoebocytes are able to encapsulate and destroy particules and dead miracidiums. Amoebocytes from incompatible snails rapidly surround miracidiums and early larvae (primary sporocysts) whereas compatible miracidiums develop without amoebocyte reaction.

Animals↗