Morphometric study of a Brazilian strain of Carchesium polypinum (Ciliophora: Peritrichia) attached to Pomacea figulina (Mollusca: Gastropoda), with notes on a high infestation

SHORT COMMUNICATION

Morphometric study of a Brazilian strain of Carchesium polypinum (Ciliophora: Peritrichia) attached to Pomacea figulina (Mollusca: Gastropoda), with notes on a high infestation

Roberto Júnio P. Dias^I,1; Adalgisa F. Cabral^I; Isabel C. V. Siqueira-Castro^II; Inácio D. da Silva-Neto^II & Marta D'Agosto^I

^ILaboratório de Protozoologia, Programa de Pós-graduação em Ciências Biológicas, Comportamento e Biologia Animal, Universidade Federal de Juiz de Fora. 36036-900 Juiz de Fora, Minas Gerais, Brazil

^IILaboratório de Protistologia, Departamento de Zoologia, Universidade Federal do Rio de Janeiro. 21941-590 Rio de Janeiro, Rio de Janeiro, Brazil

ABSTRACT

During an ecological study of the epibiotic relationship between ciliate protists and Pomacea figulina (Spix, 1827) (Gastropoda, Ampullariidae), originating from an urban stream in southeast Brazil, a high infestation by the peritrich ciliate Carchesium polypinum (Linnaeus, 1758) Ehrenberg, 1830 (Ciliophora, Peritrichia) associated to the shell of one mollusc among 23 was observed. We provided a morphological and morphometric study of C. polypinum using observations of specimens in vivo, after protargol staining, and examined using scanning electron microscopy. The Brazilian-population of C. polypinum is characterized by: size of zooid in vivo 89 µm x 57 µm on average; colony regularly dichotomously branched with usually up to 40 zooids; macronucleus usually J-shaped; single contractile vacuole located in the upper third of body; myoneme not continuous throughout the colony; stalks contract despite the discontinuity of their individual myonemes; polykinety comprises three peniculi, each consisting of three kineties. The high infestation showed here could be related to the preference for eutrophic environments showed by C. polypinum and suggested that ciliate epibionts may be ecologically important in aquatic habitats.

Key words: Ampullariidae; epibiosis; gastropod; morphology; peritrichs.

The peritrich ciliate Carchesium polypinum (Linnaeus, 1758) Ehrenberg, 1830 is commonly found in freshwater ecosystems and is a good indicator of poor water quality (WEI et al. 2004). Ciliates of the genus Carchesium live in colonies containing zooids, contractile stalks and free-swimming telotrochs (ZAGON 1971) and have high colonization rates in eutrophic ecosystems (KUSUOKA & WATANABE 1989). They generally do not display host specificity and could be found on seaweeds, emerged and submersed macrophytes, and attached to different groups of aquatic invertebrates (FOISSNER et al 1992, COOK et al. 1998, MAYÉN-ESTRADA & ALADRO-LUBEL 2002), including the gastropod Pomacea figulina (Spix, 1827) (DIAS et al. 2008). In addition to colonize living hosts, they also attach to inert substrates and have been recorded in diverse lotic systems associated to sediment (KUSUOKA & WATANABE 1989, SOLA et al. 1996, MADONI & BASSANINI 1999, MADONI 2005, MADONI & BRAGHIROLI 2007).

Prosobranch molluscs in the Ampullariidae family are widely distributed in subtropical and tropical regions, freshwater ecosystems, preferentially inhabiting still waters in lotic systems. Molluscs in the genus Pomacea also tolerate organic pollution (THIENGO 1995), and are promising indicators of water quality (COLER et al. 2005). This condition increases the ecological opportunity for colonization by peritrich ciliates which present a high preference for eutrophic environments.

During an ecological study on the epibiont ciliate community and prosobranch molluscs Pomacea figulina (Gastropoda: Ampullariidae) (DIAS et al. 2008), collected in an urban stream, a high infestation of the peritrich ciliate Carchesium polypinum (Ciliophora, Peritirchia) associated to the shell of one mollusc, out of 23, was analyzed. The gastropod (5.0 x 4.6 cm) was collected from a sampling station (21°46'38.1"S, 43°24'0.4"W) in São Pedro stream, at an urban area of Juiz de Fora, Minas Gerais, southeast of Brazil. Water samples were collected and fixed with 10% formaldehyde (5 ml) to quantify the bacterial density (HOBBIE et al. 1977), and to assess chlorophyll concentration (5 ml) (APHA 1992). Water temperature, conductivity, pH and dissolved oxygen data were measured with portable equipment. In the laboratory, the mollusc was scrubbed with a blader on Petri dishes containing previously filtered water collected from the same place. The ciliates were observed in vivo through bright field and differential interference contrast microscopy, stained using the protargol technique (DIECKMANN 1995), and prepared for scanning electron microscopy (SILVA-NETO 1994). Examinations of in vivo and prepared slides were made with an Olympus BX51 bright field microscopy while the biometric analyses were performed using Image Pro-Plus 5.0 software. The ciliates were then identified according to ZAGON & SMALL (1970), ESTEBAN & FERNÁNDEZ-GALIANO (1989), and FOISSNER et al. (1992). The mollusc was sent to the Malacology Sector, Instituto Oswaldo Cruz, and identified by Dr Silvana Thiengo.

Morphological analyses revealed that a single species of a colonial peritrich Carchesium polypinum colonized P. figulina collected in São Pedro stream (Figs 1-3). The overall morphology of the Brazilian strain of C. polypinum described in the present study is very similar to the species studied by ZAGON (1970, 1971), ZAGON & SMALL (1970), CURDS et al. (1983), ESTEBAN & FERNÁNDEZ-GALIANO (1989), FOISSNER et al. (1992), so we considered both conspecific. We provided a morphometric characterization of the species based on 10 characters measured from living individuals and nine characters measured from protargol-stained specimens (Tab. I).

 

The colonies of C. polypinum are branched with inverted bell-shaped zooids arranged on the branches. The colonial assemblage has a main stalk that is joined to the substratum by a fixing disc. The colonies had usually up to 40 zooids. The zooids are found in symmetrical dichotomous colonies. Colonies range in length from 700 µm to 2 mm. Zooids in vivo from 76.9 to 110.6 µm in length, and between 35.6 and 83.6 µm in width. The size of impregnated zooids varied between 45.0-57.1 µm in length and 36.4-55.9 µm in width. The length of the zooid decreased by 42% when stained. Cytoplasm slightly greyish, usually containing several large bronwish food vacuoles (7-20 µm in diameter). A single contractile vacuole located in the upper third of body. Macronucleus J-shaped that usually descended to a region just aboral to the telotroch band. The macronucleus is large and occupies a significant proportion of the body volume. The micronucleus was located close to the J-shaped macronucleus. The peristomial disc in vivo is 50.1-107.8 µm wide and 5.0-20.8 µm thick. Located on the side opposite to the peristome is the lateral stalk, which in non-contracted specimens measured 10.8-17.4 µm in width. The lateral stalk surface had irregular folds as showed by scanning electron microscopy. The myoneme is not continuous throughout the colony. The stalks contract despite the discontinuity of their individual myonemes. Myoneme ranges from 1.2-4.9 µm in width, presenting fibers that extended anteriorly within the zooid, from the scopula to central part of the cell body. The myoneme stains heavily with silver, but the remainder of the stalk is transparent. As observed in other peritrichs, the infraciliature of the zooid of C. polypinum is formed by the oral infraciliature and the aboral ciliary wreath. The aboral ciliary wreath (trochal band) is constituted by a ridge of kinetosomes placed in two staggered rows surrounding the posterior end of the organism. The distance between the trochal band and the scopula is 9.2-17.6 µm. However, these numbers probably are smaller than the actual values because contraction is initiated by silver-impregnation. The oral infraciliature is well developed in this species. The oral apparatus is usual for peritrichs. The haplokinety and polykinety circle about one turn around the peristomial disc and make a further turn after plunging into the infundibulum. The polykinety comprises three peniculi (oral polykinetids) in the lower half of infundibulum, each consisting of three kineties. The oral polykinety 1 (P1) is paralleled at its point of separation by a second triple row of kinetossomes. The posterior ends of the three kineties of P1 terminate at slightly different levels. The oral polykinetid 2 (P2) appears to begin at a slight angle and from a single point presents a short distance from P1, turns slightly, and can then be clearly seen as three distinct ciliated rows of kinetossomes. P2 is interposed between oral polykinetids 1 and 3. The oral polykinetids 3 (P3), presents three short rows of kinetosomes, and appears approximately in the aboral one-third of the infundibulum (Figs 4-17, Tab. I).

The Brazilian strain of C. polypinum is similar to the population described by FOISSNER et al. (1992) in terms of body length (77-110 µm vs. 80-140 µm), number and position of contractile vacuoles, shape of macronucleus, number of zooids, and the oral infraciliature. As demonstrated by recent papers, the infraciliature revealed with silver impregnation is highly species-specific, especially the structure of infundibular polykineties in the oral apparatus, playing an essential role in the determination of species (CLAMP 1990, JI & SONG 2004, JI et al. 2005). Several published reports describe the morphology of the colony and zooids of C. polypinum (KAHL 1935, LOM 1964, CURDS 1969, ZAGON 1970, 1971, ZAGON & SMALL 1970, CURDS et al. 1983, ESTEBAN & FERNÁNDEZ-GALIANO 1989, FOISSNER et al. 1992), however, few morphometric characters were included in these studies. In the present study, we provide a characterization of the species based on new morphometric characters as used by UTZ (2007).

Studies emphasizing genetic variation within-species are needed to determine whether C. polypinum collected from different sites around the world could be considered a single genetic unit. For example, GENTEKAKI & LYNN (2009) concluded that colonies of C. polypinum isolated from different locations in the Grand River basin in Southwestern Ontario, Canada, probably are not a single morphospecies as previously thought.

The only snail infested by the peritrich ciliate Carchesium polypinum (Linnaeus, 1758) Ehrenberg, 1830 (Ciliophora, Peritrichia) observed in this study was collected near to the entrance of domestic sewage in the stream suggesting that the organic pollution level could be the cause of this high infestation. Direct discharge of domestic sewage into the water causes an elevation in the concentration of phosphates and other nutrients, increasing the density of bacteria, the main food for peritrich ciliates (PRIMC 1988). The high infestation showed here could be related to the preference for eutrophic environments showed by C. polypinum. The autecological data recorded for C. polypinum in the present study and in previous studies as revised by FOISSNER et al. (1992) are presented in table II. This observed infestation demonstrates that ciliate epibionts may be ecologically important in aquatic habitats and their relative biomass should be taken into consideration when benthic ciliates, in a given habitat, are assessed.

ACKNOWLEDGEMENTS

We would like to thank Silvana Thiengo (FIOCRUZ) for the identification of the snail, Sthefane D'ávila (UFJF) for making the schematic ink drawings, and Laura Utz for English revision. We also acknowledge the suggestions made by the editor. This study was financially supported by FAPEMIG and PROPESQ/UFJF.

LITERATURE CITED

Submitted: 26.II.2009; Accepted: 23.II.2010.

Editorial responsibility: Marcus V. Domingues

• APHA. 1992. Standards methods for the examination of water and wastewater. Washington, D.C., American Public Health Association, 17^th ed.
• CLAMP, J.C. 1990. Redescription of three species of Lagenophrys (Ciliophora: Peritrichia: Lagenophryidae) and a new North American species of Lagenophrys from hypogean amphipods. Transactions of the American Microscopical Society 109 (1): 1-31.
• COLER, R.A.; R.R. COLER; E.K.G. FELIZARDO & T. WATANABE. 2005. Applying weight grain in Pomacea lineata (Spix, 1827) (Mollusca: Prosobranchia) as a measure of herbicide toxicity. Brazilian Journal of Biology 65 (4): 617-623.
• COOK, J.A.; J.C. CHUBB & J. VELTKAMP. 1998. Epibionts of Asellus aquaticus (L.) (Crustacea, Isopoda): an SEM study. Freshwater Biology 39: 423-438.
• CURDS, C.R. 1969. An illustrated Key to the British Freshwater Ciliated Protozoa Commonly Found in Activated-Sludge Process London, Ministry of Technology, H.M.S.O.
• CURDS, C.R.; H.A. GATES & M.C.L. ROBERTS. 1983. British and Other Freshwater Ciliated Protozoa. Cambridge. Linnean Society of London, Part II.
• DIAS, R.J.P.; S. D'AVILA; H. WIELOCH & M.D'AGOSTO. 2008. Protozoan ciliate epibionts on the freshwater apple snail Pomacea figulina (Spix, 1827) (Gastropoda, Ampullariidae) in an urban stream of southeast Brazil. Journal of Natural History 42 (19): 1409-1420.
• DIECKMANN, J. 1995. An improved protargol impregnation for ciliates yielding reproducile results. European Journal of Protistology 31: 372-382.
• ESTEBAN, G. & D. FERNÁNDEZ-GALIANO. 1989. Morphology and morphogenesis in Carchesium polypinum (Ciliophora: Peritrichida). Transactions of the American Microscopical Society 108 (4): 345-353.
• FOISSNER, W.; H. BERGER & F. KOHMANN. 1992. Taxonomische und ökologische revision der ciliaten des saprobiensystems - Band II: Peritrichia, Heterotrichida, Odontostomatida. Munich, Informationsberichte des Bayer Landesamtes für Wasserwirtschaft.
• GENTEKAKI, E. & D.H. LYNN. 2009. High genetic diversity but no population structure of the peritrichous ciliate Carchesium polypinum in the Grand River basin (North America) inferred from nuclear and mitochondrial markers. Applied Environmental Microbiology 75 (10): 3187-3195.
• HOBBIE J.E.; R.J. DALEY; S. JASPER. 1977. Use of nuclepore filters for counting bacteria by fluorescence microscopy. Applied Environmental Microbiology 33: 1225-1228.
• JI, D. & W. SONG. 2004. Notes on a new marine peritrichous ciliate (Ciliophora: Peritrichida), Zoothamnopsis sinica n. sp. from north China, with reconsideration of Zoothamnium maximum Song, 1986. Acta Protozoologica 43 (1): 61-71.
• JI, D.; W. SONG; K.A.S. AL-RASHEID & P. SUN. 2005. Description of Zoothamnium foissneri n. sp. and redescription of Z. duplicatum Kahl, 1933 and Z. mucedo Entz, 1884, three species of marine peritrichous ciliates. European Journal of Protistology 41 (1): 45-56.
• KAHL, A. 1935. Urtiere oder Protozoa I. Wimpertiere oder Ciliata (Infusoria). 4. Peritricha und Chonotricha, p. 651-886. In: F. DAHL (Ed.). Die Tierwelt Deutschlands. Jena, Gustav Fischer.
• KUSUOKA, Y. & Y. WATANABE. 1989. Distinction of emigration by telotroch formation and death by predation in peritrich ciliates: SEM observation on the remaining stalks ends. Microbiology Ecology 62: 7-12.
• LOM, J. 1964. The morphology and morphogenesis of the buccal ciliary organelles in some peritrichous ciliates. Archiv für Protistenkunde 107: 131-162.
• MADONI, P. 2005. Ciliated protozoan cominities and saprobic evaluation of water quality in the hilly zone of some tributaries of Po River (northern Italy). Hydrobiologia 541: 55-69.
• MADONI, P. & S. BARGHIROLI. 2007. Changes in the ciliate assemblage along a fluvial system related to physical, chemical and geomorphologic characteristics. European Journal of Protistology 43: 67-75.
• MADONI, P. & N. BASSANINI. 1999. Longitudinal changes in the ciliate protozoa communities along a fluvial system polluted by organic matter. European Journal of Protistology 35: 391-402.
• MAYÉN-ESTRADA, R. & M.A. ALADRO-LUBEL. 2002. Distribution and Prevalence of 15 species of epibiont petrich ciliates on the crayfish Camabarellus patzcuarensis Villalobos, 1943 in lake Pátzcuaro, Michoacán, México. Crustaceana 74 (11): 1213-1224.
• PRIMC, B. 1988. Trophic relationships of ciliated Protozoa developed under different saprobic conditions in the periphyton of the Sava River. Verhandlungen Internationale Vereiningen Limnologie 26:1116-1119.
• SILVA-NETO, I.D. 1994. Observations sur é ultrastructure du cilié heterotriche Licnophora auerbachi Cohn, 1866, epibionte de l'etoile de mer. Annales des Sciences Naturelles, Zoologie et Biologie Animale, 2: 49-62
• SOLA, A.; J.F. LONGÁS; SERRANO S. & A. GUINEA. 1996. Influence of environmental characteristics on the distribution of ciliates in the River Henares (Central Spain). Hydrobiologia 32 (4): 237-252.
• THIENGO, S.C. 1995. Família Pilidae p50-69. In: Tópicos em mala-cologia médica. F.S. Barbosa (Ed.). Rio de Janeiro, Editora Fiocruz.
• UTZ, L.R.P. 2007. First record of Epistylis plicatilis (Ciliophora: Peritrichia) attached to Pomacea canaliculata (Mollusca: Gastropoda) in Southern Brazil. Zootaxa 1454: 49-57.
• WEI, M.; Y. YUNE; Y. SHEN & X. ZHANG. 2004. Intraespecific phylogeography of Carchesium polypinum (Peritrichia, Ciliophora) from China, inferred from 18s-ITS1-5.8S ribosomal DNA. Life Science 47 (1): 11-17.
• ZAGON, I.S. 1970. Carchesium polypinum: cytostructure after protargol silver deposition. Transactions of the American Microscopical Society 89 (3): 450-468.
• ZAGON, I.S. 1971. Scanning electron microscope observation on some life history stages of Carchesium polypinum (Ciliata, Peritrichia). Journal of Protozoology 18 (2): 328-332.
• ZAGON, I.S. & E.B. SMALL. 1970. Carchesium polypinum: somatic and buccal structure analysis after protargol staining. Transactions of the American Microscopical Society 89: 443-449.

Publication Dates

• Publication in this collection
  12 July 2010
• Date of issue
  June 2010

History

• Received
  26 Feb 2009
• Accepted
  23 Feb 2010