Evaluation of potential health risks to Eastern Elliptio (Elliptio complanata) (Mollusca: Bivalvia: Unionida: Unionidae) and implications for sympatric endangered freshwater mussel species

Conservation efforts for freshwater musselspecies require identification and evaluationof potential health risks to populations. Sampling large numbers of individual mussels,however, could damage the small, fragile,extant populations of imperiled mussel species. In this study, a small sample size was designedto reduce lethal sampling, costs, andenvironmental disruption, while still allowing95% confidence in detecting health risks of25% or greater prevalence in the population. Health assessments were conducted on twentyspecimens of the Eastern Elliptio, Elliptio complanata, collected from two NorthCarolina sites as part of a survey to evaluatepotential disease threats to mussels in theregion. Bacteriological sampling of thegastrointestinal tracts yielded 18 aerobicbacterial species, of which Aeromonashydrophila (55.0%), Enterobacter spp.(40.0%), and Bacillus spp.(30.0%) were predominant. Histologicallesions of internal organs included mild tomoderate digestive gland atrophy andinflammation in one mussel, and mild tomoderate parasitism in several individuals. Adistinct difference in parasite prevalence wasevident between infections in E.complanata from the two collection sites. Thetrematode metacercaria of Homalometronarmatum and what appears to be three gillciliate species, the most abundant beingtentatively identified as the scyphidiidperitrich Mantoscyphidia sp., were foundin mussels from one site only. This studydemonstrates a comprehensive diagnosticapproach incorporating multiple modalities toassess the health status of mussel populations,while minimizing the sample size required toobtain valuable information. Furthermore, thisstudy provides baseline health data of E.complanata at two sites in south-central NorthCarolina and suggests the potential usefulnessof E. complanata as an environmentalbioindicator of health risks to sympatricthreatened freshwater mussel populations.     

Morphological and Molecular Characterization of a New Protist Family, Sandmanniellidae n. fam. (Ciliophora, Colpodea), with Description of Sandmanniella terricola n. g., n. sp. from the Chobe Floodplain in Botswana

ABSTRACT. Sandmanniella terricola n. g., n. sp. was discovered in soil from the Chobe floodplain, Botswana, southern Africa. Its morphology and 18S rDNA gene sequence were studied with standard methods. Sandmanniella terricola is very likely an adversity strategist because it reaches peak abundances 6–12 h after rewetting the soil and maintains trophic food vacuoles with undigested bacteria in the resting cyst, a highly specific feature suggested as an indicator for an adversity life strategy. Possibly, the energy of the stored food vacuoles is used for reproduction and support of the cyst wall. Morphologically, Sandmanniella terricola is inconspicuous, having a size of only 50 × 40 μm and a simple, ellipsoidal shape. The main characteristics of the genus are a colpodid silverline pattern; a perioral cilia condensation; a flat, dish-shaped oral cavity, in the centre of which originates a long, conical oral basket resembling that of certain nassulid ciliates; and a vertically oriented left oral polykinetid composed of brick-shaped adoral organelles. This unique mixture of features and the gene sequence trees, where Sandmanniella shows an isolated position, suggest establishing a new family, the Sandmanniellidae n. fam., possibly related to the families Colpodidae or Bryophryidae. The curious oral basket provides some support for the hypothesis of a common ancestor of colpodid and nassulid ciliates.     

Effect of the rumen ciliates Entodinium caudatum,Epidinium ecaudatum and Eudiplodinium maggii,and combinations thereof,on ruminal fermentation and total tract digestion in sheep

The quantitative importance of individual ciliate species and their interaction in the rumen is still unclear. The present study was performed to test whether there are species differences in the influence on ruminal fermentation in vivo and if combinations of ciliates act additive in that respect. Six adult wethers fed a hay-concentrate diet were defaunated, then refaunated either with Entodinium caudatum (EC), Epidinium ecaudatum (EE) or Eudiplodinium maggii (EM) alone, then progressively with all possible species combinations. Feed, faeces, urine, ruminal fluid and gas were sampled for eight days always after at least 21 days of adaptation. With a linear mixed model, accounting for the 2 × 2 × 2 full factorial study design, mean marginal effect sizes, i.e., the magnitude of change in variables as caused by the presence of each ciliate species or of combinations of them, were estimated. The apparent digestibility of organic matter and neutral detergent fibre remained unaffected. The apparent N digestibility increased by 0.054 with EM (0.716 with defaunation). Ruminal ammonia increased by 1.6, 4.0 and 8.7 mmol/l in the presence of EM, EC and EE, respectively, compared to defaunation (6.9 mmol/l). In the EM + EE combination, ruminal ammonia was lower than would have been expected from an additive effect. With EE, total short-chain fatty acids increased by 23 mmol/l (100 mmol/l with defaunation), but not when EE was combined with EM. The acetate-to-propionate ratio decreased by 0.73 units in the presence of EE (4.0 with defaunation), but only when EE was the sole ciliate species in the rumen. In the presence of any ciliate species, the 16S rDNA copies of total Bacteria and major fibrolytic species decreased to 0.52- and 0.22-fold values, respectively of that found without protozoa. Total Archaea were unaffected; however, Methanobacteriales copies increased 1.44-fold with EC. The CH₄-to-CO₂ ratio of ruminal gas decreased by 0.036 with EM and 0.051 with EE (0.454 with defaunation). In conclusion, individual ciliates affected ruminal fermentation differently and, when different species were combined, sometimes in a non-additive manner. From the ciliates investigated, EE affected ruminal fermentation most and might play a dominant role in mixed ciliate populations.     

Morphological and Molecular Description of Three New Species of the Cyrtophorid Genus Chlamydodon (Ciliophora,Cyrtophoria)

This study investigates the morphology and molecular characteristics of three new cyrtophorid ciliates isolated from China seas: Chlamydodon salinus n. sp., Chlamydodon caudatus n. sp., and Chlamydodon paramnemosyne n. sp. Of these, C. salinus n. sp. differs from its congeners through a combination of body size, a cross‐striated band that is not continuous, the presence of 30–34 somatic kineties, 11–15 nematodesmal rods, and 13 contractile vacuoles. Chlamydodon caudatus n. sp., meanwhile, is characterized by having a conspicuous tail, a continuous cross‐striated band, 34–40 somatic kineties, about 15 contractile vacuoles, and 20–24 nematodesmal rods. Compared with other Chlamydodon species, the third new one, C. paramnemosyne n. sp., could be identified by its continuous cross‐striated band, 16–18 somatic kineties, 5 contractile vacuoles, and 9–12 nematodesmal rods. Based on the sequence of the small subunit (SSU) rRNA gene, the phylogeny of these three new species was analyzed, indicating that they all clustered with other congeners to form a monophyletic assemblage. Based on previous studies and the present work, a brief revision of the genus Chlamydodon is supplied, and a key to aid the identification of Chlamydodon species is given.     

Phylogeny and Establishment of a New Ciliate Family,Wilbertomorphidae fam. nov. (Ciliophora,Karyorelictea), a Highly Specialized Taxon Represented by Wilbertomorpha colpoda gen. nov., spec. nov.

The morphology and molecular phylogeny of a new marine interstitial karyorelictean ciliate, Wilbertomorpha colpoda gen. nov., spec. nov., isolated from a sandy beach at Qingdao, China, are investigated. The ciliature is mainly on the right surface with the left surface barren except for a single marginal kinety, which is typical of the order Loxodida. Nevertheless, other morphological features, such as the highly reduced buccal structure, the absence of a buccal cavity and the presence of extremely specialized cortical granules, prevent its assignation to any known family. Furthermore, the secondary structure of the variable region 2 of the SSU rRNA gene is unique among loxodids. Thus, we establish a new family, Wilbertomorphidae fam. nov. for the genus Wilbertomorpha. Phylogenetic analyses based on SSU rRNA gene sequence data suggest that this taxon is a sister group to the family Geleiidae which belongs to the order Protoheterotrichida. However, morphologically Wilbertomorpha bears a much stronger resemblance to Loxodidae which belongs to the order Loxodida. Based on these findings, we tentatively place Wilbertomorphidae nov. fam. incertae sedis within Karyorelictea.     

五种缘毛类纤毛虫遗传关系的ISSR研究

应用ISSR分子标记揭示了5种缘毛类纤毛虫(Carchesium polypinum,Epistylis chrysemydis,E.plicatilis,E.urceolata和Vorticella campanula)的遗传关系.从34个引物中筛选到13个多态性高的引物进行研究.得到的遗传距离(0.666 7～1.000 0)显示ISSR技术具有较高的分辨率.依据构建的UPGMA聚类树,V.campanula首先和其他种类分开;C.polypinum和E.chrysemydis聚在了一起;在3种Epistylis纤毛虫中,E.plicatilis和E.urceolata聚在了一起.对比由核糖体小亚基RNA基因序列构建的系统发育树,发现:1)ISSR引物在缘毛类纤毛虫基因组中可以得到多态扩增;2)C.polypinum与Epistylis的关系近于V.campanula,在缘毛类纤毛虫分类中,单生或群居是重要的系统发育特征;3)E.plicatilis和E.urceolata的关系近于E.chrysemydis.在Epistylis属纤毛虫中,柄的中空与否是一个有用的系统发育和分类特征.本研究表明ISSR方法在纤毛虫相近和相似种遗传关系研究中是一种新的有用方法.     

Rheotaxis In Uronychia Setigera (Ciliata, Hypotrichida)

ABSTRACT. The behavior of populations of Uronychia setigera (Ciliata, Hypotrichida) exposed to water currents flowing at increasing velocities (300, 400, 500, 900, 1,700 μm/s) was analyzed using two techniques: 1) the ethogram and 2) the numerical indices recently proposed to measure the development in space and time of tracks of ciliates. Beyond a certain threshold value of the water velocity (˜ 300 μm/s), this species shows a definite positive rheotaxis, only if it moves in a more or less direct contact with the substrate. No rheotactic swimming ever occurs. Rheotaxis is a gradual, adaptive behavior: the higher the velocity of the current, the stronger the degree of the rheotactic response, as demonstrated by the increasing significance of the polar distribution of the tracks. Beyond 500 μm/s the water flow is so strong that it affects the locomotion of U. setigera continuously and strongly inducing this species to perform a new behavioral pattern, the Fast Backward Bidimensional Swimming. Under stressing water currents it reacts at first by creeping along straighter trajectories and then with faster locomotion, in such a way that its reaction is to a certain extent proportional to the drag of the currents. the rheotaxis of U. setigera is discussed as an adaptive response.     

Mixotrophic ciliates in an Andean lake: dependence on light and prey of an Ophrydium naumanni population

1. Planktonic ciliates were examined during a spring–summer period (November 1998–April 1999) in the ultraoligotrophic Lake Moreno Oeste (41°5' S and 71°33' W, 758 m a.s.l), which belongs to the Nahuel Huapi System (Patagonia, Argentina). The lake is deep ( Z _max=90 m) and warm monomictic.
2. Sampling was performed at a mid-lake station, where vertical profiles of temperature and light were measured in situ , and samples for bacteria and ciliates enumeration were taken throughout the water column.
3. The peritrich Ophrydium naumanni , a freshwater pelagic ciliate with endosymbiotic Chlorella , was the dominant ciliate in the lake.
4.  Ophrydium naumanni and autotrophic picoplankton exhibit a clear coincidence in their vertical distribution ( P  < 0.05), preferring levels at or near the 1% of surface photosynthetically active radiation (PAR) irradiance. Both may have the same light requirements, or the coincidence may reflect a trophic relationship.
5. Dependence on light and prey by O. naumanni were studied using field experiments, in which we analysed ciliate grazing on bacteria, and in laboratory experiments, in which we compared particle uptake under dark and light conditions.
6.  Ophrydium naumanni was able to ingest particles [latex microspheres and fluorescently labelled bacteria (FLB)] in field and laboratory experiment, indicating that it has the potential to affect bacteria population of Lake Moreno Oeste.
7. Ciliate particle ingestion was observed to be dependent on light availability because under dark conditions, the ingestion was lowered ( P  < 0.05).     

Morphological redescriptions of four marine ciliates (Ciliophora: Cyrtophorida: Dysteriidae) from Qingdao, China

The morphology and infraciliature of four marine cyrtophorid ciliates isolated from Qingdao, China, were investigated. Based on the present work and on previous data, improved diagnoses for three rarely known species are provided: (1) Mirodysteria decora; small-sized marine Mirodysteria about 35–60 × 25–35 μm in vivo, oval in outline; body surface with two or three conspicuous dorsal spines and one caudal spine; three right kineties, the rightmost one extending dorso-apically; left frontal kineties reduced, each consisting of three basal bodies only; podite subcaudally positioned; two ventrally located contractile vacuoles. (2) Dysteria legumen; body oval with two longitudinal grooves on different plates; six right kineties, the rightmost two of which extend dorso-apically; two left frontal kineties and two ventrally located contractile vacuoles. (3) Dysteria proraefrons; body about 60 × 35 μm in vivo; six right kineties, the two rightmost of which extend dorso-apically and the leftmost one is considerably shortened; three left frontal kineties; two ventrally located contractile vacuoles. A population of D. derouxi with eight or nine right kineties is also briefly described. The current investigation further demonstrates high diversity and cosmopolitan distribution of this highly specialized group of benthic ciliates.     

Spathidium seppelti foissneri nov. subspec., Spathidium simplinucleatum nov. stat., and Dileptus americanus Kahl, 1931, one new and two poorly known soil gymnostome ciliates from soils of Slovakia

The morphology and infraciliature of three soil gymnostome ciliates, Spathidium seppelti foissneri nov. subspec., Spathidium simplinucleatum nov. stat., and Dileptus americanus, collected from Slovakia, were investigated using live observation and protargol impregnation. S. seppelti foissneri is distinguished from its congeners by a combination of characters including: distinctly spatulate shape with convex oral bulge; 25 ellipsoidal, scattered macronuclear nodules; an average of 23 ciliary rows, 3 anteriorly differentiated to form a dorsal brush occupying 25% of the body length; and rod-shaped to slightly ellipsoidal extrusomes measuring about 5 x 0.5 microm. S. simplinucleatum is about 110 x 50 microm in vivo, characterized by solid, concave oral bulge, with the impression of doubled oral bulge in right side, macronuclear tortuous strand, usually 30 ciliary rows, 3 anteriorly differentiated to form a dorsal brush, and about 7 microm long rod-shaped extrusomes. S. simplinucleatum is highly variable in body size and length of monokinetidal bristle tail. Dileptus americanus is about 300 x 50 microm in vivo and differs from its congeners by a combination of characters including two macronuclear segments with a single micronucleus in between, two contractile vacuoles in dorsal side of trunk, two size types of rod-shaped extrusomes, a proboscis which occupies about 37% of body length, circular oral opening, and an average of 22 ciliary rows, of which up to 4 are differentiated to form a dorsal brush.