Scanning Electron Microscopy of Tintinnopsis parva: Studies on Particle Accumulation and the Striae*

SYNOPSIS. Lorica building was studied experimentally for Tintinnopsis parva Merkle, an agglutinated tintinnid. This species incorporated either siliceous or Ca-rich particles. Evidence of agglutination was seen within 30 min after the addition of particles to cultures of the protozoa. Fully agglutinated loricae were produced by the proter; partially incrusted loricae attributed to an opisthe were also recovered. The cytoplasmic evaginations of unknown function called striae were seen in the scanning electron microscope in better relief than ever before. They may provide the mechanism whereby the enclosed capsules are brought into contact with prey organisms.     

Neustonic Marine Craspedomonadales (Choanofiagellates) from Washington and California

SYNOPSIS. Neustonic choanoflagellates can be found in marine tide pools in the San Juan Islands, Washington, and on the Monterey Peninsula, California. Several marine photo-synthetic Chrysophyceae (in the Pedinellaceae), which also occur in these regions, have a basic structure so similar to choanoflagellates that this family is placed in the Craspedomonadales. In pointing out this relationship, the derivation of the Craspedomonadales from pigmented Chrysophyceae is strongly indicated.
In addition to the naked choanoflagellates, which are placed in the Codonosigaceae, these organisms produce loricae of two different types: 1) loricae possibly of cellulose and without visible structure in the light microscope (Salpingoecaceae), 2) loricae composed of silica strands, sometimes forming a mesh with large open spaces (Acanthoecaceae). Members of the latter family seem to be confined to a marine environment and are a prominent part of this investigation. Examination of several species with the electron microscope has revealed interesting details of lorica morphology that are not visible with the light microscope.
Several new combinations of taxa are proposed in addition to new taxa, including 4 new species of Salpingoeca , 3 new species of Diploeca and 4 new species of Pleurasiga. Three new genera are described, Ellisiella gen. nov., Acanthoecopsis gen. nov., and Sportelloeca gen. nov.     

Agglutinated loricae of some Baltic and Antarctic Tintinnina species (Ciliophora)

The abundance and species composition of diatoms adhering tothe loricae of four agglutinated Tintinnina species, Laackmanniellanaviculaefera, Codonellopsis gaussi, Cd.balechi and Tintinnopsislobiancoi, were determined. Diatoms from the Fragdariopsis group,F.cylindrus and F.pseudonana, dominated on tintinnid loricaefrom the Antarctic waters, whilst Thalassiosira spp. were predominanton loricae from the Baltic Sea. Although tintinnids utilizeddiatoms in the environment, it is not a rule that they use onlythese which are dominant. Our results suggest that certain diatomsare actively selected and agglutinated by particular tintinnidspecies.     

2013年夏威夷东南部海区表层砂壳纤毛虫的群落结构和分布特征

鉴于东太平洋热带海区表层砂壳纤毛虫和其他微型浮游动物的群落结构资料几乎空白, 我们于2013年8月14日至9月18日在夏威夷东南部海区的23个站位采样调查了表层砂壳纤毛虫群落。23个站位共采集到砂壳纤毛虫22属36种, 均为透明壳种类。各站砂壳纤毛虫种丰富度范围为15-21种, 总丰度范围为4,730-23,693个/m³, 生物量范围为9.60-88.61 μg C/m³。本海区主要优势种为镯形囊坎虫(Ascampbelliella armilla)、斯廷细瓮虫(Steenstrupiella steenstrupii)、薄壳真铃虫(Eutintinnus tenuis)和纤弱细瓮虫(Steenstrupiella gracilis), 这4种主要优势种的口径范围不同。     

Rasterelektronenmikroskopische und biometrische Untersuchungen über die Variabilität der Form, Struktur und Größe des Gehäuses einiger limnischer Tintinnina (Protozoa, Ciliophora)

The loricae of the fresh-water Tintinnina Codonella cratera, Tinitinnidium fluviatile , and Tintinnopsis cylindrata were investigated for their variability in shape, structure, and size, using scanning electron microscopy and variance analysis. The intrastrain variability of length and width of the loricae is significantly smaller than the interstrain variability. The shells are shorter in autumn than in spring. The lorica of C. cratera consists of biogenic and non-biogenic flakes, irregularly cemented by a substance which is released from the organism. Building of the shell is not restricted to the time of binary fission. T. fluviatile and T. cylindrata have soft and sticky loricae which are heavily agglutinated by various biogenic and non-biogenic particles. The material used for lorica-building and/or agglutination depends on environment and season. There is a relationship between the structure of the lorica and the degree of eutrophication in the lake. The significance of these findings for paleolimnology and taxonomy and the function of the lorica in fresh-water Tintinnina are discussed.     

Particle selectivity of pelagic tintinnid agglutination

Scanning electron microscopic observation reveals that several agglutinated, pelagic tintinnid taxa apparently possess a capability of incorporating specific mineral grains, such as monospecific coccoliths, for their loricae. Since the ocean water generally contains other coccolith taxa, as well as diatoms and clays, it seems possible that the tintinnids can single out a particular coccolithophore species from the variety of suspended matter for their loricae-building.     

Developmental studies on the loricate choanoflagellate Stephanoeca diplocostata Ellis. III. Growth and turnover of silica,preliminary observations

Growth, turnover of silica and lorica morphology of Stephanoeca diplocostata Ellis have been investigated in batch cultures at 20 °C. Mean cell doubling times for separate experiments ranged from 9.1–13.8 h. During exponential growth, uptake of reactive silicate progressed steadily and throughout this phase the average amount of biogenic silicon per cell was 2.1 pg. Once growth declined, net dissolution of silica from loricae became apparent and progressed steadily throughout the stationary and death phases. The minor difference in solubility between loricae of living cells and costal strips cleaned with acid indicates that even if an organic component is associated with the silica of costal strips it does not inhibit silica dissolution. The first effects of silica dissolution on cells as revealed by electron microscopy are limited to corrosion on the surfaces and the hollowing out of the centres of costal strips but ultimately a consistent pattern of lorica disintegration occurs.     

Tintinnid agglutination of coccoliths: A selective or random process?

This study suggests that tintinnids are not strongly selective when agglutinating coccoliths from their environment. If selectivity does occur it may be due to the possibility that tintinnids exclude, for their loricae building, coccoliths above a certain size limit.     

厦门沿海的砂壳纤毛虫(原生动物, 纤毛门, 砂壳目)

对厦门沿海6个代表性站位砂壳纤毛虫进行了为期1年的采集, 共分离鉴定了27种砂壳纤毛虫, 其中拟铃虫属Tintinnopsis 20种, 薄铃虫属Leprotintinnus 3种, 类铃虫属Codonellopsis 2种, 领细壳虫属Stenosemella 1种以及网纹虫属Favella 1种。对该5属27种砂壳纤毛虫进行形态学描述, 并提供了显微照片, 其中侧胀拟铃虫Tintinnopsis ventricosoides Meunier, 1910为中国新记录种。     

Intraspecific variability in Antarctic tintinnids: the Cymatocylis affinis/convallaria species group

Analyses of the morphometry of 630 loricae belonging to thedescribed species Cymatocylis affinis and Cymatocylis convallariaretrieved from 21 samples collected in the Weddel Sea (6O–73?S)strongly suggest that both taxa, including the four formae intowhich C.affinis was originally divided, are members of a singlespecies. The only feature which varies significantly and consistentlyamong the samples surveyed is the total length of the lorica,lowest average lengths being positively correlated with lowestabsolute abundances of this tintinnid in the waters sampled.This relationship points to some unfavorable factor(s) whichaffects both tintinnid reproduction/ survival and growth; thedata analysed suggest that drops in the availability of foodmight be responsible for the size (and abundance) variationsobserved.     

Phylogenetic position of a rare loricated green alga, Cephalomonas granulata N. L. Higinb. (Volvocales, Chlorophyceae)

Cephalomonas ( Cp .) granulata N. L. Higinb. (Volvocales, Chlorophyceae), a rare volvocalean phytoflagellate, has recently been isolated from a paddy field in Japan and examined by light and fluorescence microscopy. The vegetative cells of Cp . granulata have granulate loricae and a characteristic mushroom-like shape with a hemispherical to spherical anterior part and narrower posterior part. Cp . granulata has been classified among the Phacotaceae along with other loricated genera. However, its phylogenetic position has not been investigated using molecular phylogeny. To evaluate the phylogenetic position of Cephalomonas , the 18S r RNA gene sequence of the Japanese strain was determined. The phylogenetic analyses revealed that Cp . granulata was not closely related to other loricated taxa with known phylogenetic affinities, such as Phacotaceae sensu stricto ( Phacotus , Pteromonas , and Wislouchiella ) and Dysmorphococcus globosus . This indicates at least three independent origins of loricae within the Volvocales.     

Predator-prey behavior and its effect on rotifer survival in associations of Mesocyclops edax,Asplanchna girodi,Polyarthra vulgaris,and Keratella cochlearis

Summary The predatory copepod Mesocyclops edax preys effectively on the rotifers Asplanchna girodi and Polyarthra vulgaris but not on the rotifer Keratella cochlearis. It readily captures individuals of this latter species but usually releases them unharmed, being unable to remove the soft parts within their loricae. The predatory A. girodi regularly eats K. cochlearis but cannot catch P. vulgaris. When P. vulgaris is contacted by the corona of A. girodi, it immediately escapes by elevating its paddles and jumping away a distance up to about ten times its own body length. In experimental communities of these predator and prey species the survival of Polyarthra and Keratella is significantly affected by the species of predator present and by predator-prey interaction between the two predators when both are present.Supported by National Science Foundation research grant DEB 76-09768 and Public Health Service career development award KO4-GM 70557 to J.J.G.     

Three-dimensional images of choanoflagellate loricae

Choanoflagellates are unicellular filter-feeding protozoa distributed universally in aquatic habitats. Cells are ovoid in shape with a single anterior flagellum encircled by a funnel-shaped collar of microvilli. Movement of the flagellum creates water currents from which food particles are entrapped on the outer surface of the collar and ingested by pseudopodia. One group of marine choanoflagellates has evolved an elaborate basket-like exoskeleton, the lorica, comprising two layers of siliceous costae made up of costal strips. A computer graphic model has been developed for generating three-dimensional images of choanoflagellate loricae based on a universal set of 'rules' derived from electron microscopical observations. This model has proved seminal in understanding how complex costal patterns can be assembled in a single continuous movement. The lorica, which provides a rigid framework around the cell, is multifunctional. It resists the locomotory forces generated by flagellar movement, directs and enhances water flow over the collar and, for planktonic species, contributes towards maintaining cells in suspension. Since the functional morphology of choanoflagellate cells is so effective and has been highly conserved within the group, the ecological and evolutionary radiation of choanoflagellates is almost entirely dependent on the ability of the external coverings, particularly the lorica, to diversify.     

Molecular diversity of the syndinean genus Euduboscquella based on single-cell PCR analysis

The genus Euduboscquella is one of a few described genera within the syndinean dinoflagellates, an enigmatic lineage with abundant diversity in marine environmental clone libraries based on small subunit (SSU) rRNA. The region composed of the SSU through to the partial large subunit (LSU) rRNA was determined from 40 individual tintinnid ciliate loricae infected with Euduboscquella sampled from eight surface water sites in the Northern Hemisphere, producing seven distinct SSU sequences. The corresponding host SSU rRNA region was also amplified from eight host species. The SSU tree of Euduboscquella and syndinean group I sequences from environmental clones had seven well-supported clades and one poorly supported clade across data sets from 57 to 692 total sequences. The genus Euduboscquella consistently formed a supported monophyletic clade within a single subclade of group I sequences. For most parasites with identical SSU sequences, the more variable internal transcribed spacer (ITS) to LSU rRNA regions were polymorphic at 3 to 10 sites. However, in E. cachoni there was variation between ITS to LSU copies at up to 20 sites within an individual, while in a parasite of Tintinnopsis spp., variation between different individuals ranged up to 19 polymorphic sites. However, applying the compensatory base change model to the ITS2 sequences suggested no compensatory changes within or between individuals with the same SSU sequence, while one to four compensatory changes between individuals with similar but not identical SSU sequences were found. Comparisons between host and parasite phylogenies do not suggest a simple pattern of host or parasite specificity.     

Evidence for a lacustrine faunal refuge in the Larsemann Hills, East Antarctica, during the Last Glacial Maximum

Aim  There is no previous direct evidence for the occurrence of lacustrine refuges for invertebrate fauna in Antarctica spanning the Last Glacial Maximum (LGM). In the absence of verified LGM lacustrine refuges many species are believed to result from Holocene dispersal from sub-Antarctic islands and continents further north. If freshwater lake environments were present throughout the LGM, extant freshwater species may have been associated with Antarctica prior to this glacial period. This study looked at faunal microfossils in a sediment core from an Antarctic freshwater lake. This lake is unusual in that, unlike most Antarctic lakes, the sediment record extends to c . 130,000 yr bp , i.e. prior to the LGM.
Location  Lake Reid, Larsemann Hills, East Antarctica (76°23' E; 69°23' S).
Methods  Palaeofaunal communities in Lake Reid were identified through examination of faunal microfossils in a sediment core that extended to c . 130,000 yr bp .
Results  Ephippia and mandibles from the cladoceran Daphniopsis studeri and loricae of the rotifer Notholca sp. were found at all depths in the sediment, indicating that these two species have been present in the lake for up to 130,000 years. Copepod mandibles were also present in the older section of the core, yet were absent from the most recent sediments, indicating extinction of this species from Lake Reid during the LGM.
Main conclusion  The presence of D. studeri and Notholca sp. microfossils throughout the entire Lake Reid core is the first direct evidence of a glacial lacustrine refugium for invertebrate animals in Antarctica, and indicates the presence of a relict fauna on the Antarctic continent.     

Particle availability controls agglutination in pelagic tintinnids in the Southern Ocean

Mechanisms of particle selectivity controlling agglutination within the agglomerated tintinnid genus Stenosemella spp. Jörgensen were studied during two iron fertilisation experiments (EisenEx and EIFEX) conducted in the Southern Ocean in austral spring 2000 and late austral summer to early autumn 2004. Representative SEM pictures of Stenosemella spp. loricae were taken on the day of fertilisation, during the middle and at the end of both experiments. Whereas during EisenEx particles used for agglutination were unambiguously dominated by coccoliths of Emiliania huxleyi (Lohmann) Hay & Mohle, agglutinated particles during EIFEX mainly consisted of broken diatom frustules (BF) of heavily silicified species. This observation is supported by the ratio of E. huxleyi (Eh)/BF abundances in the water column during both experiments. During EisenEx we observed an Eh/BF ratio which was an order-of-magnitude higher compared to the EIFEX experiment. Thus, our results clearly indicated that particle availability seems to be the driving mechanism in the agglutination of Southern Ocean tintinnids. Furthermore, possible implications for the vertical flux of agglutinated biogenic particles to deep ocean waters and sediments are discussed.     

Lagenophrys anticthos N. Sp. and L. aegleae Mouchet-Bennati, 1932 (Ciliophora,Peritricha, Lagenophryidae), Ectocommensals of South American Crustaceans1

ABSTRACT. Lagenophrys anticthos n. sp. resembles L. aegleae Mouchet-Bennati; however, the two species are distinguished from one another by differences in the structure of the lorica aperture. Similarities in the shape of the lorica and macronucleus indicate a close phylogenetic relationship between L. anticthos and L. aegleae. The size of L. anticthos varies greatly within a population, and it is unclear whether this can be attributed to genetic differences or to environmental factors. In L. anticthos, variation in the form of the lips of the lorica aperture is correlated with variation in size. The brown, iron-rich incrustations observed around the loricae of L. aegleae by an earlier worker were not seen, indicating that the incrustations do not play a role in the symbiosis between L. aegleae and its host as was previously thought.     

Seasonal Changes in Lorica Sizes and the Species of Tintinnida in the New York Bight*

SYNOPSIS. Tintinnida of the New York Bight (a bend in the coastline) were identified during the 1-year period August 1973–August 1974. Recurring genera included Stenosemella and Tintinnopsis; seasonal genera were mainly the hyaline Favella, Metacylis, and Helicostomella; exotic or unusual genera included Parafavella and Ptychocylis. Large size differences in loricae were found seasonally, related apparently, to water temperature.     

PHACOTUS LENTICULARIS (CHLAMYDOMONADALES,PHACOTACEAE) ZOOSPORES REQUIRE EXTERNAL SUPERSATURATION OF CALCIUM CARBONATE FOR CALCIFICATION IN CULTURE1,2

In nature, zoospores of the chlamydophycean genus Phacotus Perty usually have a calcified lorica. The only cultured species, Phacotus lenticularis (Ehrenberg) Stein, did not readily calcify in artificial media. To overcome this deficiency, we developed an artificial culture medium (N-HS) in which Phacotus lenticularis formed mineralized loricae, as under natural conditions. Calcification of Phacotus (strain Krienitz 91/1) was achieved in a medium containing the ionic concentrations found in natural habitats (i.e. Lake Haussee and Lake Stechlin), hard-water lakes of the Baltic Lake District (Germany). The N-HS medium contained extremely low phosphate concentrations and high calcium and magnesium concentrations compared with common culture media, but the concentrations were similar to those in the lakes. Calcium carbonate in N-HS medium was dissolved up to the saturation concentration (saturation index = 1). Supersaturation was achieved by the addition of ultra-alkaline compounds (Na₂S_iO₃ or NaOH). The medium with the highest super-saturation had a saturation index of 118 and was extremely supersaturated with respect to calcium carbonate. In that medium and in modified media with less of the sodium compounds (lower supersaturations), calcification of zoospores was observed. To determine the effects of sodium and silicon compounds on calcification, various other silicon and sodium compounds were tested but were shown to be ineffective. In conclusion, calcification of Phacotus lenticularis depends directly on the degree of calcium carbonate supersaturation of the medium, but the fundamental mineralization pattern does not. Our study shows that calcification in Phacotus lenticularis can be triggered and controlled by supersaturation of calcium carbonate.