Peritrich Ciliate Research Articles

FOULING OF THE CARIDEAN SHRIMP, LYSMATA WURDEMANNI (GIBBES, 1850) BY THE BARNACLE, BALANUS IMPROVISUS DARWIN, 1854 AND OTHER EPIBIONTS

Epibiotic growth was found on several specimens of the shrimp, Lysmata wurdemanni collected along a rocky groin in Galveston, Texas. Bryozoan (Membranipora sp.) and peritrich ciliate (family Epistylididae) colonies were found on a few individuals, while the barnacle, Balanus improvisus was encrusted upon most of the fouled shrimp. The majority of barnacles were attached to the dorsolateral surfaces of the carapace and abdomen. Fouling by barnacles is hypothesized to occur with a decrease in salinity, while the pattern of barnacle attachment is likely affected by the grooming ability of this caridean shrimp.

Planeticovorticella finleyi n.g., n.sp. (Peritrichia, Vorticellidae), a planktonic ciliate with a polymorphic life cycle

Abstract. Free‐swimming trophonts of a sessiline peritrich ciliate were discovered in plankton samples from the Rhode River, Maryland, and main‐stem Chesapeake Bay. Cultures revealed that the species comprises both free trophonts that swim with their peristomial cilia and sessile trophonts that attach to substrates with a contractile, helically‐twisted talk. Trophonts with a short, rigid stalk or no definite stalk also were seen in culture. Binary fission of free‐swimming trophonts usually produced a pair of trophonts attached scopula to scopula by a short, rigid stalk. These persisted for some time as distinctive, spinning doublets before their stalks broke and they separated. Binary fission of free‐swimming trophonts also yielded trophont‐telotroch pairs that stayed together for only a short time. Telotrochs from these pairs were presumably the source of attached trophonts. Conjugation occurred in both free and attached trophonts. Formation of microconjugants involved at least 2 successive divisions of a trophont. Possession of a helically‐twisted, contractile stalk placed the peritrich in the family Vorticellidae, but its unique combination of life‐cycle stages marks it as a new genus and species, Planeticovorticella, finleyi The morphology and life cycle of P. finleyi raise questions about the present classification of sessiline peritrichs and suggest that it may be at least partly artificial. Stalkless planktonic peritrichs that swim with their oral cilia as do trophonts of P. finleyi may have evolved from sessile ancestors by an alteration in the life cycle that created unstable clusters of trophonts on a single parental stalk. Free‐swimming trophonts would originate from breakup of these clusters.

Monitoring protozoa and metazoa biofilm communities for assessing wastewater quality impact and reactor up-scaling effects

The succession of biofilm communities with special emphasis on ciliates, rotifers, and nematodes was monitored for half a year and compared to different operating conditions in order to evaluate plant performance and effect of up-scaling lab scale to large scale reactors. Ciliates and metazoa are able to rapidly change their communities as a reaction to changed plant operating conditions as has been proven true by comparing lab scale and pilot scale reactors. Even slight operational changes are causing major shifts in biofilm communities. Nematodes and rotifers in lab scale and large scale reactors seem to be in competition with peritrich ciliates. In both lab scale and pilot scale systems ciliates of the subclass Peritrichia proved to be dominant and thus to play an important role in both the species composition of the biofilm biocenosis and biofilm structure. Interpretation of biocenosis composition changes for large scale reactors is much more complex than for lab scale reactors. This conflicts with up-scaling of lab scale results to full scale reactors.

First record of Lagenophrys dennisi (Ciliophora: Peritrichia) on the exoskeleton of crayfish Cambarellus patzcuarensis.

Lagenophrys dennisi, a peritrich ciliate, was observed attached to the exoskeleton of the crayfish Cambarellus patzcuarensis in Lake Pátzcuaro, Michoacán, Mexico. Lagenophrys dennisi presents a hemispheroidal, suboval or oval lorica in dorsal view, the distinctive lorica aperture consists of a pair of lips highly arched, unthickened, and smooth. Comparison of morphometric characters of the ciliate with previous records is made. Structures such as a "V"-shaped lorica suture, collar ridges, and myoneme are proposed for species identification. An anterior crescentic thickening on the dorsal surface of the lorica was observed under the scanning electron microscope. Lagenophryids were associated with 11 of 13 body parts with antennules and rostrum showing the highest prevalence. Lagenophrys dennisi was also found attached to submerged glass slides. This study represents the first record of L. dennisi on C. patzcuarensis and the first record of its presence in Mexico.

Mobiline peritrich riders on Australian calanoid copepods.

Calanoid copepods from billabongs near Wodonga, Victoria, Australia were found to be infested with a disc-shaped mobiline peritrich ciliate belonging to the genus Trichodina. Biometrical data, including mean body diameter (43.6m), mean adhesive disc diameter (35.9m), mean denticle ring diameter (20.1m), modal denticle number (17), modal number of radial pins per denticle (9), and denticle shape and dimensions, indicate that the species is T. diaptomi Basson & Van As (1991). This is the first record of T. diaptomi from Australasia. Adults of Boeckella fluvialis and B. minuta were infected, but adult Calamoecia lucasi were not. Levels of infestation were higher on B. fluvialis (67.5% of females, 54.5% of males) than B. minuta (47.4% of females, 33.3% of males). Mean numbers of Trichodina per adult B. fluvialis were 7.68 (range 0‐78) for females and 4.06 (range 0‐43) for males, and differed significantly between sexes. Although calanoid copepods were present in the plankton from January to early December 1991, Trichodinainfestations occurred during October and November only, peaking during late November just before the copepods disappeared from the plankton. Whether the infestation was a cause of the copepod decline, developed because the copepods were rendered susceptible to infection by some other cause, or was determined by physical and/or chemical environmental factors is unknown.

Periphyton and sphagnicolous protists of dystrophic bog lakes (Brandenburg, Germany): I. Annual cycles, distribution and comparison to other lakes

The periphyton of acid, dystrophic bogs was investigated. Glass-slides were exposed in four different bog lakes about 100 km north of Berlin, Germany, in order to examine the species composition and the annual cycle of the protist community. The annual cycles of the periphyton in bog lakes were comparable to those in other mesotrophic lakes: During the winter months small heterotrophic flagellates (HF) dominated the periphyton community. Besides that bacterivorous ciliates were present as typical pioneer species. At the end of the ice covering, almost exclusively unicellular green algae colonized the slides. In May high abundances of ciliates and choanoflagellates were observed. At the same time, a maximum of species was reached. From August to October peritrich ciliates significantly contributed to the periphyton. Their number decreased when early frosts occurred. The four investigated bog lakes exhibit very similar species compositions, almost all of the species were present in each of the four lakes. Differences were only distinct concerning the dominance of some protistan groups. The largest deflections, however, occurred not between two lakes, but between two habitats within one lake: The upper 30 cm of the Sphagnum mat comprise two very different protistan communities, determined by a strong vertical zoning. Due to the different light and nutrient conditions, the slides of the upper region exhibited a denser colonization, mainly consisting of autotrophic cryptomonads and vagile ciliates. In contrast to this, the slides of the deeper region were mainly colonized by heterotrophic flagellates and sessile peritrich ciliates.

A Method for the Synchronous Induction of Large Numbers of Telotrochs in Vorticella convallaria by Monocalcium Phosphate at Low pH

ABSTRACT We have devised a two step method for the synchronous induction of telotrochs in the peritrich ciliate, Vorticella convallaria. The method is easy, reliable, and allows us to study the earliest events of telotroch formation at the ultrastructural, biochemical, and molecular levels. The steps involved are: (1) excising the cell body from the stalk in a large population (7.4 times 104 cells) of EDTA‐treated, attached cells by the application of monocalcium phosphate monohydrate solution at pH 3.2, (2) rinsing and suspending the isolated cell bodies in inorganic medium. Within 90 min, 80% of the population forms telotrochs. Analysis of factors that are important for maximum stalk excision and transformation shows that the population must not be older than 2 d and the most effective concentration of monocalcium phosphate is 4.8 mM for a 20 min exposure. The most effective monocalcium phosphate is in the monohydrated form. A pH value of 3.2, produced by the addition of hydrochloric acid in the presence or absence of calcium is not sufficient to initiate stalk excision and telotroch formation. This observation leads us to conclude that stalk excision is dependent on monocalcium phosphate or its hydrolysis products.

Reproductive biology of a deposit-feeding amphipod, Casco bigelowi , with extended parental care

The reproductive traits of a deposit-feeding amphipod that engages in extended parental care were examined. At the study site in Lowes Cove, Maine, USA, Casco bigelowi (Blake, 1929) occurred in highest densities in soft sediments just below mean low water (MLW). During most months, the sex ratio was ≃1. Many females hosted males in their burrows throughout the summer, but after fertilization of females in September, all adult males disappeared from the study area. In October almost 80% of the females were ovigerous, and in November about the same percentage was parental, i.e. caring for juveniles in their burrows. The females produced only one brood each in late fall which they accommodated in their burrows for 2 mo or longer. The average number of juveniles per female was ∼20 in November, and continuously decreased until January. Juveniles reached sizes >10 mm length in the maternal burrows. In early December the first juveniles were found in their own burrows, but major recruitment took place in late December and January. It is concluded that for C. bigelowi, the delay of recruitment into the winter months with low predation pressure and the large offspring size at this time are major advantages gained by extended parental care. C. bigelowi is host to the peritrich ciliate Cothurnia sp. on its gills, and during the summer months >70% of all amphipods had ciliates on their gills. Juveniles still living in their mother's burrows showed infestation rates similar to that of the parent; those of highly infested mothers were more heavily infested than those of “clean” mothers. Facilitated epibiont transmission during intimate and long-lasting (2␣mo) parent–offspring associations may be a consequence of extended parental care.

A new genus and two new species of marine peritrichous ciliates (Protozoa, Ciliophora, Peritrichida) from Qingdao, China

Abstract This paper deals with descriptions of a new genus and two new species of marine peritrichs, Pseudovorticella longa nov. spec. and Zoothamnopsis mengi nov. gen., nov. spec. Both organisms were collected from eutrophic waters (mollusca-breeding and shrimp-farming ponds) off the coast of Qingdao, China. Their morphology, infraciliature and silverline system were studied and investigated from living and silver-stained organisms. The new genus Zoothamnopsis has all the characteristics of the well-known genus Zoothamnium but with a reticulate silverline system like that of Pseudovorticella. Zoothamnopsis mengi nov. spec. is a medium-sized form with dichotomously branched stalk and one apically located contractile vacuole; C-shaped macronucleus is horizontally located; zooids in vivo are about 50–70 × 20–30 μm. Number of silverlines: from oral area to aboral ciliary wreath ca. 76–87; AbW to scopula 30–36. The new species Pseudovorticella longa measures 30–45 × 15–25 μm and is unique by having a dorsally located contractile vacuole, smooth cell surface and very fine pellicular striations, asymmetrical elongated body shape and a long, strongly twisted macronucleus. Number of silverlines: from oral area to aboral ciliary wreath: 42–47; AbW to scopula: 10–12.

Trichodina ctenophorii n. sp., a novel symbiont of ctenophores of the northern coast of the Gulf of Mexico.

Peritrich ciliates of the genus Trichodina are internal or external symbionts of invertebrate and vertebrate hosts. We describe here Trichodina ctenophorii n. sp., a symbiont of Mnemiopsis mccraydii and Beroë ovata (Phylum Ctenophora). The morphology of fixed and living specimens is revealed by silver impregnation, scanning electron microscopy, and differential interference microscopy. Distinguishing features of Trichodina ctenophorii include a denticular morphology composed of falcate, blunt-tipped blades, and long, straight thorns, with five pins per denticle. Trichodina ctenophorii is found only on the comb plates of these ctenophores. To the best of our knowledge, this is the first report of a trichodinid from the Gulf of Mexico and the first associated with ctenophores.

Cellular Contraction Precedes Membrane Depolarization in Vorticella Convallaria

Application of a mechanical stimulus to the cell body of the peritrich ciliate Vorticella convallaria evoked an all-or-nothing membrane depolarization, the large pulse. This was always accompanied by an all-or-nothing cellular contraction, and simultaneous recordings of the two events revealed that the large pulse was always preceded by the cellular contraction. A smaller graded membrane depolarization (the medium pulse) was sometimes produced in response to a weaker mechanical stimulus. The medium pulse was accompanied by a small, graded, localized contraction of the cell body and was occasionally followed by a large pulse. When a large pulse occurred during a medium pulse, it reached the same peak level as that of a large pulse evoked without a preceding medium pulse. When a medium pulse occurred during a medium pulse, summation of the two pulses was observed. Sustained contraction causes V. convallaria to become rounded, and in this state a mechanical stimulus stronger than that used to evoke the large pulse evoked a graded depolarizing mechanoreceptor potential in the cell. We conclude that both the large and medium pulses are caused by an inward receptor current that is activated mechanically following contraction of the cell body. A localized contraction evokes a small mechanoreceptor current, causing a medium pulse. An all-or-nothing contraction evokes a saturated, all-or-nothing mechanoreceptor current, causing a large pulse.

An all-or-nothing rise in cytosolic

The peritrich ciliate Vorticella sp. exhibits cellular contraction of an all-or-nothing type in response to a mechanical stimulus. Many authors have suggested that the contraction may be controlled by the cytosolic level of Ca2+, since glycerol-extracted Vorticella contracts when Ca2+ is added to the external solution. However, no direct evidence for the increase in cytosolic [Ca2+] has yet been obtained in living Vorticella. In the present study, by injecting a fluorescent Ca2+ indicator into living Vorticella and monitoring the cytosolic [Ca2+] with a confocal microscope, we have demonstrated that a mechanical stimulus evoked an all-or-nothing rise in cytosolic [Ca2+] (Ca2+ 'spike'). The onset of the Ca2+ spike was similar in its time course to that of cellular contraction. Since the Ca2+ spike was recorded in a Ca2+-deprived solution containing 1 mmol l-1 EGTA, we concluded that release of Ca2+ from intracellular Ca2+ storage site(s) is responsible for the Ca2+ spike.

Chemical modification of amino acid residues in glycerinated Vorticella stalk and Ca(2+)-induced contractility.

The glycerinated stalk of the peritrich ciliate Vorticella, was treated with various reagents to chemically modify the amino acid residues. The influences of these modifcations on spasmoneme contractility were investigated. First, it was confirmed that the spasmoneme contraction is not inhibited by alteration of SH groups. It was also demonstrated that chemical modification of methionine and tryptophan residues abolishes spasmoneme contractility. The reagents used for chemical modification were N-bromosuccinimide (NBS), chloramine T, and 2-hydroxy-5-nitrobenzyl bromide (HNBB), which abolished spasmoneme contractility at concentrations of 40-50 microM, 200-300 microM, and 4 mM, respectively. These results suggest that, along with Ca2+ binding proteins, there are other as yet to be identified proteins involved in contractility.

Observations on the Activity and Life History of the Scavenging Isopod Natatolana borealisLilljeborg (Isopoda: Cirolanidae) from Loch Fyne, Scotland

The activity and life history of the cirolanid isopod Natatolana borealisLilljeborg has been studied using (primarily) fish-baited traps deployed at a deep-water station (190 m) in Loch Fyne, Scotland. A voracious scavenger, it burrows into soft mud, emerging to feed when suitable food odours are detected in the water. Isopods were attracted significantly to baited vs. non-baited traps. Underwater video observations revealed that most animals were active in the vicinity of traps, that capture efficiency was low, but retention complete. Only traps on the sea-bed captured mancas or juveniles in any numbers. Any seasonal pattern in catch rate through the year was confounded by high variability. Only one (manca-)brooding female was ever caught in a trap (in April). It is assumed that brooding females desist from feeding. The sex ratio of isopods in most trap collections was thus significantly male dominated. Mancas were trapped during February to August. Growth rate was slowest in adults and was similar for males and females. The maximum growth rate occurred during autumn associated with the seasonal cycle in bottom water temperatures. Longevity was estimated (by following peaks in the size–frequency distributions with time) to be c. 2·5 years, with sexual maturity (based on oostegites/spurred appendix masculinae) achieved after c. 19 months. Semelparity is suggested. A low incidence of an unnamed epicaridean parasite is reported from the Clyde population. Natatolana borealisalso carried peritrich ciliate epizoites on their antennae. Possible predators are swimming crabs and gadid fish, e.g. whiting and cod.

Ciliate bacterivory in epilimnetic waters

Simultanous measurements of bacterial production (3~-thymidine incorporation) and ciliate bacterivory (uptake of fluorescently labeled bacteria, FLB) were carried out on samples from the epilimnion of 17 lakes in eastern Norway. On average, bacteria equivalent to 19% (range: 0.8 to 62%) of the bacterial production were consumed by ciliates. The most important bacterivorous ciliates were small (c30 pm) oligotrichs; Halteria grandinella and Strobilidium spp. These ciliate taxa were found to have average clearance rates of 183 and 103 nl cell-' h-' respectively, corresponding to specific clearance rates of 0.5 and 0.9 X 10' cell volumes h-' In addition, Vorticella sp., a peritrich ciliate that was attached to colonies of the cyanophyte Anabaena flos-aquae, was found to be important in several lakes. On average, these 3 ciliate taxa alone accounted for >80% of total ciliate bacterivory. Speciesspecific clearance rates did not vary much between lakes, indicating that the ciliates were always food limited. These results confirm other recent studies, showing that pelagic ciliates can be significant grazers on bacterioplankton.

Taxonomic Characterization of Pseudohaplocaulus infravacuolatus nov. spec. and Vorticella chlorellata Stiller 1940, Epiplanktonic Peritrichs (Ciliophora, Peritrichia) Attached to Coenobia of Anabaena (Cyanophyta), Including a Redescription of V chlorostigma (Ehrenberg, 1831)

AbstractPseudohaplocaulus infravacuolatus nov. spec. and Vorticella chlorellata Stiller, 1940. two peritrich ciliates attached to planktonic coenobia of Anabaena sp. (Cyanophyta). were investigated using live observation, silver impregnation, and scanning electron microscopy. Pseudohaplocaulus infravacuolatus differs from its nearest relative, P. anabaenae (Stiller, 1940). mainly by the location of the anterior contractile vacuole. Vorticella chlorellata has symbiotic green algae. a J‐shaped macronucleus. and a single, ventral contractile vacuole. The number of silverlines is very close to that of V. picta, but distinctly different from that of V. chlorostigma (Ehrenberg, 1931), an other green Vorticella, redescribed for the first time. Vorticella rhabdostyloides Kellicott, 1885 is recognized as a distinct species, but transferred to Haplocaulus: H. rhabdostyloides (Kellicott, 1885) nov. comb. Likewise, Vorticella fasciculuta Müller, 1773 is considered a distinct species and transferred to Pseudovorticella: P.fasciculata (Müller, 1773) nov. comb.

Effects of the Zebra Mussel (Dreissena polymorpha Pallas) on Protozoa and Phytoplankton from Saginaw Bay, Lake Huron

Direct effects of the grazing activities of the zebra mussel, Dreissena polymorpha, on the natural assemblage of planktonic protozoa and algae from Saginaw Bay, Lake Huron, were studied in September and October 1994. Water and mussels collected from two eutrophic sites were incubated in an outdoor “natural light” incubator at ambient temperature for 24 hours. Experiments were conducted in 4-L bottles with screened (40 or 53-μm net) or unscreened water and with and without mussels. Despite relatively high growth rates of protozoa on both dates, mussels lowered protozoan numbers by 70–80% and reduced the species richness of the protozoan community by 30–50%. Large heterotrophic flagellates were reduced up to 100% while peritrichous ciliates attached to the colonies of blue-greens were reduced only by 50%. Dreissena selectively removed nanoplanktonic Cryptomonas and Cyclotella, but had no significant effect on the predominant phytoplankton species, Microcystis. Overall, Dreissena clearance rates were low in the presence of this cyanophyte species. We conclude that zebra mussels, in regions where they are abundant, can cause significant changes in composition of both the protozoan and phytoplankton communities.

Planktivore effects on zooplankton epibiont communities: Epibiont pigmentation effects

We observed the development of epibiont communities on freshwater crustacean zooplankton from 12 July–31 August 1991 in three ponds: one with planktivorous fish, a second with planktivorous larval salamanders, and a third with planktivorous fish added midway through the sampling period. Prevalence, on zooplankton, of pigmented euglenoid epibionts (Colacium vesiculosum), alone and with unpigmented peritrich ciliates (Vorticella campanula and Epistylis sp.), was significantly reduced by the addition of planktivorous fish in the third pond, while the prevalence of peritrich ciliates alone was not. Neither of the ponds with unaltered planktivore regimes showed a similar pattern of change in prevalence of pigmented and unpigmented epibionts on zooplankton. The relative loss of pigmented euglenoid epibionts, after planktivore addition, suggests that epibiont color or contrast may increase the susceptibility of their substrate organisms to planktivores.

Colonization of non-living surfaces in streams by peritrich ciliates

Cleaned stones or glass slides placed in streams were quickly colonized by vorticellids and Carchesium, whose numbers increased for about 2 weeks before falling to a steady level by about 4 weeks. Platycola populations developed more slowly, but tended to become dominant after 3 or 4 weeks. The populations of peritrichs on surfaces already coated with 'periphyton' remained at low levels, even after the surface had been disturbed by removal to a new site. Stone surfaces carried higher peritrich populations than glass slides, though Platycola colonized grooves on glass slides to almost twice the density found on the smooth glass surface. Surface irregularities appear to enhance attachment. It is suggested that in general the densities of peritrich colonization are determined by available settlement sites, available food, and predation.

The effect of peritrich ciliates on the production of Acartia hudsonica in Long Island Sound

We studied the effects of attached peritrich ciliates on the fitness of natural populations of Acartia hudsonica (Pinhey) in Stony Brook Harbor, Long Island Sound. Ciliate infection occurred during late spring, and ciliate load (No. ind.−1) was not related to copepod age, stage, or body size. Simulated in situ experiments conducted throughout the period of abundance of A. hudsonica showed that egg production rate (No. d−1) was positively correlated to ambient water temperature, but negatively correlated to ciliate load. Salinity and the concentration of total or >8–10 µm Chl a were not significant in explaining the variation in egg production rate. Egg hatching success (%) was not influenced by the infection status (presence or absence) of the female. Infected nauplii had lower survival rates (d−1) compared to uninfected nauplii, but their developmental rates (molts d−1) were not significantly different.Significantly slower average sinking rates were found for infected adults compared to uninfected adults. Slower sinking rates for infected copepods may have been due to an increase in surface area which increased drag. Infected adults with slower sinking rates may be more susceptible to predation. Our findings show that peritrich ciliates can play a role in the seasonal decline and future recruitment of A. hudsonica.