Physa Sp Research Articles

Interactions between two functionally distinct aquatic invertebrate herbivores complicate ecosystem- and population-level resilience.

Resilience, the capacity for a system to bounce-back after a perturbation, is critical for conservation and restoration efforts. Different functional traits have differential effects on system-level resilience. We test this experimentally in a lab system consisting of algae consumed by zooplankton, snails, or both, using an eutrophication event as a perturbation. We examined seston settlement load, chlorophyll-a and ammonium concentration as gauges of resilience. We find that Daphnia magna increased our measures of resilience. But this effect is not consistent across ecosystem measures; in fact, D. magna increased the difference between disturbed and undisturbed treatments in seston settlement loads. We have some evidence of shifting reproductive strategy in response to perturbation in D. magna and in the presence of Physa sp. These shifts correspond with altered population levels in D. magna, suggesting feedback loops between the herbivore species. While these results suggest only an ambiguous connection between functional traits to ecosystem resilience, they point to the difficulties in establishing such a link: indirect effects of one species on reproduction of another and different scales of response among components of the system, are just two examples that may compromise the power of simple predictions.

A latest Cretaceous gastropod fauna from the Jiaolai Basin of East Asia

A non-marine gastropod fauna from the continuous uppermost Campanian to Maastrichtian deposits of the Jiaolai Basin (eastern North China) was studied. Four species attributed to four genera and an undetermined species were described, including Truncatella jiaozhouensis sp. nov., ?Pomatiopsidae gen. et sp. indet., ?Hydrobia datangensis Yü, 1977, Valvata jiaolaiensis sp. nov., and Physa sp. Among them, two new species were established. The finding of ?Hydrobia datangensis is consistent with a Late Cretaceous age as previously inferred from the charophyte flora. Available sedimentological data of the gastropod-bearing beds combined with a gastropod taphonomical study suggest that all five species lived in shallow lakes, whereas ?Pomatiopsidae gen. et sp. indet. also inhabited floodplains. Furthermore, extant Truncatella species are either fully terrestrial or dwell amphibiously in the supralittoral zone in temperate to tropical regions, usually close to the water line, as well as near freshwater of river estuaries. Therefore, Truncatella jiaozhouensis sp. nov. supposedly has lived in the surrounding shorelines of the shallow lake.

An Inventory of Springsnails (Pyrgulopsis spp.) in and Adjacent to the Spring Mountains, Nevada

Springsnails (genus Pyrgulopsis, hereafter pyrgs) are small freshwater aquatic gastropods that occur in isolated springs in western North America. Pyrgs are species of conservation concern, but patterns of occupancy and speciation are complex. We investigated patterns of occurrence for pyrgs in the Spring Mountains, Clark County, Nevada. We were primarily concerned with identifying springs containing the species P. deaconi, the Spring Mountains pyrg, and P. turbatrix, the southeast Nevada pyrg. We identified species through genetic analysis of the COI-1 mitochondrial region and examined patterns of genetic structure. We located aquatic gastropods in 26 springs and analyzed 420 aquatic gastropods, of which 392 were pyrgs, the remainder representing an unknown species of Physa. Of the 26 springs, 25 contained pyrgs and 5 contained Physa sp. For pyrgs, at COI-1 we identified a total of 29 haplotypes that formed 6 distinct monophyletic groups. Five of the 6 groups were consistent with pyrgs previously identified: P. bacchus, P. deaconi, P. fausta, P. turbatrix, and an unknown species which had been identified previously in the Grapevine Springs. The sixth group, found in 2 springs, does not match any reference specimen and is genetically divergent from the other 5 groups. It is most closely related to P. micrococcus. Prior to this study, P. bacchus had not been located in the Spring Mountains. Both P. deaconi and P. turbatrix were located in multiple springs on both the east and west sides of the Spring Mountains, even though the Las Vegas Valley (east) and Pahrump Valley (west) are hydrologically distinct. At the scale of the hydrologic basin, genetic structure was not discernable; haplotype divergence did not align with basin boundaries and the most common haplotype for P. turbatrix occurred on both the east and west sides of the Spring Mountains. While there was little evidence for genetic structuring at the hydrologic-basin level, there was good evidence for structuring at the level of the individual spring. All told, 79% (23/29) of pyrg haplotypes were unique to specific springs, suggesting that pyrg diversity primarily occurs at the level of the individual spring.

Recent Examination for Assessing Epidemiological Status of Schistosoma Mansoni in Plaine Orety, Urban Area of Libreville, Gabon, Central Africa

Schistosoma mansoni epidemiology is very uncertain in Gabon despite its wide distribution in Sub-Saharan African whereas knowledge of schistosomiasis endemicity setting has important implications for the national policy controls. To date only two cases of S. mansoni were diagnosed by the Department of Parasitology-Mycology (DPM), Libreville-Gabon between 1995 and 2009 and both came from Plaine Orety, an urban area of Libreville. As the result of this finding a survey that we report results here was conducted to determine the epidemiological status of S. mansoni in this site. Parasitological and malacological surveys were conducted prospectively from January to May 2012. Parasitological survey included people living in Plaine Orety (Libreville) area at least three months and aged from two years upwards. Stool examination was performed using Kato-Katz technique and malacological investigations were conducted in all the streams of this area for the same period to identify the intermediate snail host of S. mansoni. A total of 495 people were examined, of them 4 cases (0.81%) were identified positive to S. mansoni with no significant influence of sex or age group (p>0.05). Infected peoples said they never went out of the country but stayed in other regions of the country, i.e. Kango, Ovan, Lambarene, Port-Gentil, Bitam and Fougamou. No intermediate snail host of human schistosomes has been identified in the whole surveyed water sites of Plaine Orety. Freshwater snails identified are: Lymnea sp, Physa sp, Melanoides sp and Indoplanorbis exustus (intermediate snail host of cattle schistosomes in India). The finding of this study illustrate existing indigenous cases of S. mansoni in Libreville (Gabon) even if local active transmission area remains to be elucidate because of the absence of intermediate snail host Biomphalaria.

Moluscos límnicos como hospedeiros de trematódeos digenéticos de uma região metropolitana da ilha do Maranhão, Brasil

Este estudo se trata do primeiro levantamento malacológico de água doce e de larvas de trematódeos associadas, sem restrição, somente às espécies transmissoras da esquistossomose na região metropolitana da ilha do Maranhão. Dessa forma, objetivou-se caracterizar a diversidade de moluscos límnicos e de sua helmintofauna em ambientes com aspectos ecológicos variados. Os espécimes de gastrópodes foram coletados mensalmente no município de São Luís (MA), entre o período de novembro de 2014 a junho de 2015, em quatro pontos de coleta (P1 – lêntico e impactado, P2- lótico e impactado, P3 – lótico e alterado, P4 – lótico e conservado). Para cada local foram registrados o pH e Oxigênio Dissolvido, além de análise de Coliformes Totais e Escherichia coli. Foi coletado um total de 4112 moluscos límnicos, classificados como se segue: Biomphalaria glabrata Say, 1818 (62,86%), B. straminea Dunker, 1848 (24,71%), Pomacea sp. Perry, 1810 (7,91%), Physa sp. Draparnaud, 1801 (3,41%) e Drepanotrema sp. Crosse & Fischer, 1880 (1,11%). Destes, B. glabrata apresentou-se positivo para cercárias de Schistosoma mansoni e exemplares de Physa sp. e Pomacea sp. estavam infectados com xifidiocercárias. Houve correlação positiva e significativa em relação à pluviometria e a quantidade de moluscos (p<0,05). A maior abundância de espécimes foi registrada em áreas impactadas, bem como maior grau de parasitismo. A ocorrência de xifidiocercária representa o primeiro relato para a região metropolitana da ilha do Maranhão.

Trophic interactions in an austral temperate ephemeral pond inferred using stable isotope analysis

Ephemeral ponds are vulnerable aquatic habitats which are difficult to protect given their dynamic nature and sensitivity to degradation during dry periods. Little information is available on these habitats in austral regions, with almost no information on food-web structure and complexity. The study aimed to assess trophic interactions among dominant organisms in an ephemeral pond food web, and investigate the importance of autochthonous and allochthonous carbon, using 13C and 15N isotopes. Results of the investigation suggest that the food web comprised four trophic levels, with the top predators being Notonectids (Notonecta sp.) and diving beetles (Cybister tripunctatus (Olivier)). Intermediary trophic levels comprised zooplankton (daphniids and copepodids), macroinvertebrates (e.g. micronectids and molluscs) and tadpoles. Generalist feeders dominated the higher trophic levels (>3) with specialists comprising the lower trophic levels (≤3). The consumers preferred autochthonous fine particulate organic matter, epiphyton and submerged macrophyte organic matter sources over allochthonous sources. Autochthonous organic matter was transferred to the food web via zooplankton and select macroinvertebrates including Micronecta sp. and Physa sp. The food-web structure within the pond appeared to reflect the secondary stage of trophic structural complexity in the evolution of ephemeral ponds over the course of their hydro-period.

A FRET-Based Method for Measurement of Yeast Septin Filament Formation In Vitro

A FRET-Based Method for Measurement of Yeast Septin Filament Formation In Vitro

OCORRÊNCIA DE MOLUSCOS DO GÊNERO Biomphalaria EM PARQUES DA CIDADE DE BELO HORIZONTE, MINAS GERAIS, BRASIL

Until recently, schistosomiasis was considered the most prevalent endemic disease among populations in rural areas, especially in the northeastern and southeastern states of Brazil, and therefore classified as a “rural endemic disease.” Recent studies have shown that the epidemiology of this disease is changing by transmission in the outskirts of and even within large urban centers. The city of Belo Horizonte has 71 parks, 55 of which are open to the public. Of these 31 (43.6%) have one or more water collections. The objective of this study was to carry out a malacological survey, among the water collections in these 31 parks of Belo Horizonte. In 11 parks a total number of 551 snails of the genus Biomphalaria, intermediate host of Schistosoma mansoni, were collected. In addition, specimens of the genus Drepanotrema sp, Pomacea sp, Melanoides sp, Physa sp and Lymnaea sp, the latter an intermediate host of the parasite, which causes fascioliasis, were found. All specimens of the genus Biomphalaria were negative for S. mansoni cercariae. However, considering the potential contamination of the environment with human feces containing S. mansoni eggs in combination with the presence of intermediate hosts, these findings serve as an alert for a possible installation of schistosomiasis transmission in the municipal parks of the city of Belo Horizonte.

Microstructural characterization of shell components in the mollusc Physa sp.

Shells of the freshwater, pulmonate snail Physa (Mollusca, Gasteropoda), ranging from 0.5 to 10 mm in length, were studied using scanning microscopy, x-ray analysis, and infrared spectroscopy. Results obtained suggest that the shell is composed of aragonite, which occurs in several distinct crystalline forms. A selective distribution of crystalline forms (hexagonal plates, prisms, rhombohedra, and spherulites) occurred along specific sites of the shell. A variable distribution of the forms was also detected in adult shells and in protoconchs of developing embryos. Qualitative elemental analysis, using an energy-dispersive spectrometer, corroborates the presence of calcium, phosphorus and sulphur ions.

Effects of various larval digeneans on the calcium carbonate content of the shells of Helisoma trivolvis, Biomphalaria glabrata, and Physa sp.

The calcium carbonate concentrations in the shells of Helisoma trivolvis and Physa sp. naturally infected with larval trematodes and Biomphalaria glabrata experimentally infected with larval trematodes were analyzed quantitatively. The larval trematode-snail relationships studied were H. trivolvis infected with larval Echinostoma trivolvis and Physa sp. infected with various larval digeneans, and B. glabrata infected with Echinostoma caproni or Schistosoma mansoni. The calcium carbonate concentrations of the shells of infected snails and uninfected cohorts and of the water in which the snails were maintained were determined by ion exchange chromatography. No significant differences in the calcium carbonate concentrations of shells of infected versus uninfected snails were found. The shells of B. glabrata infected with E. caproni contained significantly less calcium carbonate than the shells of uninfected B. glabrata. The hypercalcification hypothesis, i.e., larval trematodes induce an increase in the calcium concentrations in the shells of their snail hosts, was not upheld in any of the snail-larval digenean systems studied herein.

Malacological survey of the Soledade lake hydrographic basin, in Ouro Branco (Minas Gerais, Brazil)

A malacological survey was carried out at the Soledade Lake, in Ouro Branco, State of Minas Gerais, for the period 1986-1991. A total amount of 46,579 mollusks was collected, and among them seven species corresponding to five families could be found, as follows: 39,176 specimens of Biomphalaria tenagophila; 1,296 B. glabrata; 7 Drepanotrema cimex; 2,527 Physa sp; 417 Lymnaea sp; 92 Pomacea hastrum, and 3,064 specimens of Melanoides tuberculata (Melanniidae = Thiaridae) were collected from March/1990 onwards. Four specimens of B. tenagophila were found to be positive for Schistosoma mansoni.

Invertebrate Host-Parasite Relationships: Convergent Evolution of a Tropomyosin Epitope Between Schistosoma Sp, Fasciola hepatica, and Certain Pulmonate Snails

Monoclonal antibodies (mAb) directed against Schistosoma mansoni tropomyosin isoform, SMTM (Xu et al. Experimental Parasitology69, 373-392, 1989), were used to test for cross-reactivity with Biomphalaria glabrata antigens. One mAb (1F10) recognized antigens of 39, 41, and 80 kDa in a snail head/foot antigen preparation but not a hepatopancreas antigen preparation, Another mAb (1C1) cross-reacted with a 39-kDa antigen in the head/foot extract but not in the hepatopancreas extract. Epitope mapping revealed the 1F10 epitope to be between amino acids 135 and 188 of both Bg39 (Dissous et al. Molecular and Biochemical Parasitology43, 245-256, 1990) and BgTMII (Weston and Kemp, Experimental Parasitology76, 358-370, 1993), while the 1C1 epitope was located between amino acids 189 and 213 of BgTMII. Various invertebrate species, including members from Trematoda, Pulmonata, Annelida, and Arthropoda, were tested for cross-reactivity with the monoclonal antibodies. While the 1F10 mAb displayed broad invertebrate cross-reactivity, the 1C1 mAb cross-reactivity was restricted to schistosomes, F. hepatica, and the pulmonate snails B. glabrata and Physa sp.

Present geographic distribution of intermediate mollusk hosts of Schistosoma mansoni in Belo horizonte, Minas Gerais, Brazil

Procedeu-se ao levantamento malacológico do município de Belo Horizonte, MG, com o objetivo de avaliar a distribuição, densidade e taxa de infecção dos moluscos hospedeiros intermediários do Schistosoma mansoni. Foram coletadas 3.261 Biomphalaria glabrata em 1979-81, das quais 100 (3,1%) estavam infectadas com S. mansoni. Registrou-se a existência de 36 criadouros (35,0%) de B. glabrata em 102 locais pesquisados, sendo 23 na bacia hidrográfica de Pampulha e 13 na do ribeirão do Arrudas. Foram encontrados 2 criadouros de B. tenagophila e 2 de B. straminea. Registrou-se também a presenca de exemplares de Pomacea haustrum, Physa sp e Drepanotrema cimex. Compararam-se os dados obtidos atualmente com os publicados em 1967. Houve reducao de mais de 50% no número de criadouros de B.glabrata, principalmente em decorrencias da expansão e progresso da cidade. Na zona periférica a esquistossomose continua endêmica, havendo necessidade de novas obras de saneamento básico para se conseguir o controle da doença.

Vesiculation and Loss of the Plasma Membrane along the Midpiece of Physa Sp. Spermatozoon

The Physidae are among the advanced families of the freshwater snails having very extensive and elaborate genital ducts. To achieve cross fertilization the spermatozoon must travel a long distance along a tortuous path through the oviduct and its secretions. The concept that spermatozoon structure is related to the physiological demands of the fertilization environment has been stated previously (1). The present paper describes a specialized structure associated with the plasma membrane and the loss of the plasma membrane along the midpiece of Physa spermatozoa.In early Physa spermatids, plasma membrane vesiculation is observed concurrently with cellular and nuclear condensation. The midpiece exhibits coiling and folding within the boundaries of the plasma membrane as it develops (Fig. 1). Fig. 2 shows a later stage of maturation in which the plasma membrane becomes closely associated with the midpiece and undergoes extensive vesiculation. The surface of the midpiece is a microtubular sheath.

<I>Lymnm tmnmtula</I>および<I>Physa</I> sp.への肝蛭ミラキディウム感染試験

Lymnaea truncatula is one of the oldest snails ever known as intermediate host of Fasciola hepatica in Europe. It has been clarified tha tthe intermediate host present in Japan is L. ollula. Recently, L. truncatula and Physa acuta have been found in the northern and the southwestern part of Japan, respectively. Higashi verified experimentally that the latter might have a role as an intermediate host.The present authors tried to induce experimental infection with miracidia of liver flukes (Fasciola sp.) in two species of snails, L. truncatula and Physa sp., which had been collected from a stream in Taki County, Hyogo Prefecture, Japan.L. truncatula was examined for possibility of acting as snail vector for liver flukes. No development of larvae was seen, except an aberrant development which was observed when the snail was exposed to miracidia of liver flukes within 6 or 7 days after the infection. It is clear that the Japanese L. truncatula is identical with no species of snails in Europe from a biological point of view, thouth it is very close to the snail in Europe morphologically.Experimental infection was carried out twice with a very large number of miracidia of Physa sp. As a result, no development of miracidia or sporocysts was seen in the snail at either time.The above-mentioned results indicate that no larvae of liver flukes invading L. truncatula and Physa sp. could develop in to rediae or cercariae in the field.

Trichodina sp. (Ciliata) from the Kidney of a Pulmonate Snail, Physa sp.

Trichodina sp. (Ciliata) from the Kidney of a Pulmonate Snail, Physa sp.