Biomphalaria glabrata: exposure to different amounts of calcium carbonate influencing growth, sexual maturation and pearls formation

O cálcio desempenha um papel fundamental na vida dos caramujos, regulando diferentes processoscomo motilidade, crescimento e divisão celular. O cálcio influencia diretamente o crescimento da concha, fecundidade, oviposição, mortalidade, metabolismo interno e homeostase. O objetivo deste trabalho foi descrever a formação de pérolas em Biomphalaria glabrata expostos a diferentes quantidades de carbonato de cálcio em condições de laboratório. As pérolas foram observadas na glândula digestiva e no intestino no grupo de caramujos expostos a 20 e 60 mg /L de carbonatode cálcio após 45 dias. Os resultados mostram que os caramujos produzem pérolas como um reservatório de cálcio antes de atingirem a maturidade sexual.

Avaliação biométrica de Biomphalaria spp. (Preston,1910) no município de Juiz de Fora, MG / Biometric evaluation of Biomphalaria spp. (Preston,1910) in Juiz de Fora Municipality, Brazil

As dimensões corporais são medidas utilizadas para a identificação e caracterização dos indivíduos das mais variadas espécies e podem ser avaliadas em indivíduos parsitados ou não quanto às respostas somáticas específicas. Este estudo trata da avliação biométrica de 1.129 moluscos do gênero Biomphalaria, coletados no município de Juiz de Fora, Minas Gerais, no ano de 2004. Foram coletados: 360 espécimes de B. straminea e analisados 215; 255 espécimes de B. peregrina e analisados 196; 1.550 espécimes de B. tenagophila (espécie mais prevalente na região) e analisados 718. Os moluscos capturados foram secos, pesados e medidos vivos; os moluscos mortos foram desprezados. As variáveis peso e diâmetro foram avaliadas por espécie e de forma independente e correlacionada. Estatisticamente, os estudos das variáveis diâmetro e peso revelaram que as menores médias biométricas foram evidenciadas pela espécie B. peregrina, seguida por B. straminea. Todas as espécies apresentaram diâmetro máximo das conchas cerca de 50por cento mais baixo do que os maiores diâmetros descritos na literatura. Verificou-se forte correlação positiva entre as variáveis peso (massa corpórea) e diâmetro (tamanho da concha) nas três espécies de Biomphalaria analisadas, o que fornece sólida base para se estabelecer consistente correlação direta entre estes parâmetros.

The Afro-American Biomphalariae

The reports on the occurrence of African planorbids in South America and of South American species in Africa and Asia are reviewed.

Identification of Biomphalaria havanensis and Biomphalaria obstructa populations from Cuba using polymerase chain reaction and restriction fragment length polymorphism of the ribosomal RNA intergenic spacer

In Cuba, several Biomphalaria species have been reported such as B. orbignyi, B. schrammi, B. helophila, B. havanensis and B. peregrina; only the latter three are considered as potential hosts of Schistosoma mansoni. The specific identification of Biomphalaria species is based on anatomical and morphological characters of genital organs and shells. The correct identification of these snails is complicated by the high variation in these characters, similarity among species and in some cases by the small size of the snails. In this paper, we reported the classical morphological identification, the use of PCR and RFLP analysis of the internal transcribed spacer region of the ribosomal RNA genes for molecular identification of seven snail populations from different localities in Cuba. Using morphological and molecular analysis, we showed that among the studied Cuban Biomphalaria populations only B. havanensis and B. obstructa species were found

Relación hospedador parásito entre cepas de schistosoma mansoni y seis cepas de biomphalaria glabrata de áreas endémicas venezolanas / Host parasite relationship among 3 schistosoma mansoni strains and 6 biomphalaria glabrata strains from endemic and non endemic 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 withmiracidia of SM, C5 and C6 strains of Schistosoma mansoni (18 snails/Schistosoma mansoni strain). The averages od 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 strains 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 classifiel in two groups according to the S. mansoni dose (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 percent), SM-La Victoria (73.1 percent) and C5-Cagua (62 percent). No significative statistical differences were found for the PI a) between the snail classifiel 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

Contribution to the histology of Biomphalaria glabrata / Contribuiçäo à histologia da Biomphalaria glabrata

A combination of histological techniques applied to the study of Biomphalaria glabrata yielded some interesting new data about the histology of this snail, a major intermediate host of Schistosoma mansoni in Brazil. Three kinds of pigments were identified: a ark pigment which bleached following oxidation with potassium permanganate; a lipofuchsin like, diastase-resistant PAS-positive pigment and an iron-containing pigment, probably related to hemosiderin. Calcium was detected in small deposits within the connective tissue and forming a dense core inside the chitinous radular teeth. The presence of fibrils, staining with sirius-red and birefringence under polarized light strongly suggest primitive collagen tissue. The radular apparatus appeared as a storing site for glycogen, while abundant Alcian-blue positive material (proteoglycans) was extremely concentrated in the radular sac

Behavior of Biomphalaria glabrata Say 1818 (Gastropoda: Planorbidae) - I. Morphophysiology of the mantle cavity

Using longitudinal and transverse anatomical sections, we observed that the three cristae of the mantle of Biomphalaria glabrata (renal, rectal and dorsolateral cristae) divide the mantle cavity into three chambers which we designated air or pulmonary chamber, water inflow chamber and water outflow chamber. Using videotape filming, we observed the inflow and outflow of air and water into and from the mantle cavity and we related their probable functions such as flotation, oxygen reservoir and transport, excreta circulation and elimination, water skeleton, and modification of specific weight. To determine whether the air bubble may function as a physical gill in this species we submitted three groups of snails to different systems in which water contained the same level of dissolved oxygen whereas the gas phases were atmospheric air, pure nitrogen or pure oxygen. We observed the following parameters: time of permanence on the surface, time of immersion, and frequency at which the snails reached the surface. These results did not demonstrate a physical gill function; morphological analysis of the mantle cavity indicates this possibility.

Planorbis meridaensis Preston, 1907 (Gastropoda: Planorbidae), a synonym of Biomphalaria prona (Martens, 1873)

Biomphalaria prona from Lake Valencia, Venezuela (type locality) has a polymorphic shell wich in the great majority of specimens is wider, with fewer rapidly expanding whorls, the outer one subcarinate on the left side and more or less strongly deflected leftward. Besides those modal forms there are little frequent variants characterized by narrower shell with less rapidly expanding, regularly curved whorls directed forward. Recent studies have shown that such variants constitute the predominant shell phenotype in extralacustrine populations, but are anatomically and biochemically indistinguishable from the modal class of the Lake. In the present paper it is demonstrated that the nominal species Planorbis meridaensis Preston, 1907, from Mérida, Venezuela, is identical with B. prona (Martens, 1873) of wich it must be considered a junior synonym

Biomphalaria prona (Gastropoda: Planorbidae): a morphological and biochemical study

Two samples of Biomphalaria prona (Martens, 1873) from Lake Valencia (type locality) and seven from other Venezuelan localities were studied morphologically (shell and reproductive system) and biochemically (allozyme electrophoresis). In spite of marked differences in shell characters, all of them proved indistinguishable under the anatomic and biochemical criteria. So far B. prona has been considered an endemic species, restricted to Lake Valencia. It is now demonstrated that the extralacustrine populations refered to Biomphalaria havanensis (Pfeiffer, 1839) by several authors correspond in shell characters to an extreme variant of B. prona from the Lake and really belong to the last*mentioned species. They may be regarded as the result of a process of directional selection favoring a shell phenotype other than those making up the modal class in the Lake.

Biomphalaria kuhniana Clessin, 1883, planorbid mollusc from South America

A validade de Biomphalaria Kuhniana (Clessin, 1883) é confirmada pelo estudo morfológico de espécimes do Suriname (localidade tipo) e da área de Tucuruí (rio Tocantins, Estado do Pará, Brasil), em comparaçäo com B. straminea (Dunker, 1848), e por experiências de cruzamento que revelaram completo isolamento reprodutivo entre as duas espécies. A concha adulta de Kuhniana é menor (cerca de 7,5 mm) que a de straminea (11 mm a 16.5 mm). As duas espécies distinguem-se anatomicamente pelo grau de enrugamento da parede vaginal (pouco desenvolvido em kuhniana, conspícuo em straminea), pelo número e aspecto dos divertículos prostáticos (em kuhniana 4 a 9, mais curtos e menos ramificados; em straminea 9 a 18, mais longos e mais ramificados), pelo número de camadas musculares na parte média do pênis (duas kuhniana, três em straminea), e pelo percurso do segmento distal do espermiduto, geralmente direto ou ligeiramente ondulado em kuhniana, mais ou menos enroscado em straminea. As diferenças entre B. kuhniana e B. intermedia (Paraense & Deslandes, 1962) säo menos acentuadas. Na intermedia a concha atinge cerca de 12 mm de diâmetro, a próstata tem 7 a 15 divertículos, há duas camadas musculares na parte média do pênis e a parede vaginal apresenta um enrugamento mais ou menos desenvolvido (ou às vezes uma simples dilataçäo) à esquerda do canal da espermateca e uma bolsa rudimentar à direita do canal. Em vista da grande semelhança morfológica entre B. straminea, B. kuhniana e B. intermedia, é proposto o agrupamento das três espécies no complexo Biomphalaria straminea