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.     

Feeding characteristics of two tintinnid ciliate species on phytoplankton including harmful species: effects of prey size on ingestion rates and selectivity

The feeding abilities of two tintinnid ciliates, Favella ehrenbergii and Favella taraikaensis, on 10 species of flagellates including harmful marine algae were examined under single prey conditions, and selective feeding of F. taraikaensis on two species of algae of different sizes was investigated under mixed prey conditions. Ingestion rates calculated from the rate of increases of auto-fluorescent particles inside food vacuoles in individuals ranged from 0.5 to 22.1 cells ind(-1) h(-1) for F. ehrenbergii and from 0.8 to 44.9 cells ind(-1) h(-1) for F. taraikaensis on nine species of prey algae. Significant ingestion rates of both Favella species could not be detected on Heterosigma akashiwo, although some individuals of both species were observed ingesting H. akashiwo in the initial incubation period. The relationship between prey cell volume and ingestion rate could be expressed mathematically for both Favella species, indicating that it is possible to estimate the potential feeding activity of each Favella species on specific algae using an equation, and may be applicable to evaluate the food value of prey alga for both Favella species. When F. taraikensis was fed mixtures of H. circularisquama and Pavlova lutheri, significant ingestion rates of H. circularisquama by F. taraikaensis could not be measured when H. circularisquama accounted for less than 20% of the other prey biomass. However, clear selectivity for H. circularisquama was observed when H. circularisquama reached and exceeded 34% of the other prey biomass. Under mixed prey conditions, it is likely that the selectivity of F. taraikaensis is stronger for larger prey compared to prey algae with a size near the lower limit on which F. taraikaensis can feed.     

Molecular phylogeny of tintinnid ciliates (tintinnida, ciliophora)

We investigated the phylogeny of tintinnids (Ciliophora, Tintinnida) with 62 new SSU-rDNA sequences from single cells of 32 marine and freshwater species in 20 genera, including the first SSU-rDNA sequences for Amphorides, Climacocylis, Codonaria, Cyttarocylis, Parundella, Petalotricha, Undella and Xystonella, and 23 ITS sequences of 17 species in 15 genera. SSU-rDNA phylogenies suggested a basal position for Eutintinnus, distant to other Tintinnidae. We propose Eutintinnidae fam. nov. for this divergent genus, keeping the family Tintinnidae for Amphorellopsis, Amphorides and Steenstrupiella. Tintinnopsis species branched in at least two separate groups and, unexpectedly, Climacocylis branched among Tintinnopsis sensu stricto species. Tintinnopsis does not belong to the family Codonellidae, which is restricted to Codonella, Codonaria, and also Dictyocysta (formerly in the family Dictyocystidae). The oceanic genus Undella branched close to an undescribed freshwater species. Metacylis, Rhabdonella and Cyttarocylis formed a well supported clade with several Tintinnopsis species at a basal position. Petalotricha ampulla and Cyttarocylis cassis SSU-rDNA and ITS sequences were identical or almost identical. Therefore, we propose Cyttarocylis ampulla comb. nov. for them. Intensive use of single-cell isolation and sequencing revealed unexpected complexity in the evolutionary history of these relatively well-studied ciliates. Notably, the diversity of freshwater forms suggests multiple marine-freshwater invasions.     

Glycomics-based analysis of chicken red blood cells provides insight into the selectivity of the viral agglutination assay

Agglutination of red blood cells (RBCs), including chicken RBCs (cRBCs), has been used extensively to estimate viral titer, to screen glycan-receptor binding preference, and to assess the protective response of vaccines. Although this assay enjoys widespread use, some virus strains do not agglutinate RBCs. To address these underlying issues and to increase the usefulness of cRBCs as tools for studying viruses, such as influenza, we analyzed the cell surface N-glycans of cRBCs. On the basis of the results obtained from complementary analytical strategies, including MS, 1D and 2D-NMR spectroscopy, exoglycosidase digestions, and HPLC profiling, we report the major glycan structures present on cRBCs. By comparing the glycan structures of cBRCs with those of representative human upper respiratory cells, we offer a possible explanation for the fact that certain influenza strains do not agglutinate cRBCs, using specific human-adapted influenza hemagglutinins as examples. Finally, recent understanding of the role of various glycan structures in high affinity binding to influenza hemagglutinins provides context to our findings. These results illustrate that the field of glycomics can provide important information with respect to the experimental systems used to characterize, detect and study viruses.     

Differential grazing by Acartia tonsa on a dinoflagellate and a tintinnid

The calanoid copepod, Acartia tonsa Dana, ingests both the dinoflagellate,Heterocapsa triquetra (Ehrenberg) Stein, and the tintinnid ciliate,Favella sp. In laboratory experiments its ingestion rate increaseswith increasing dinoflagellate density to a maximum at     

A preliminary study of tintinnid diversity in the NW Mediterranean Sea

Tintinnid diversity in surface waters was investigated in the Bay of Villefranche in March, before the formation of the seasonal thermocline, and in May, following water column stratification. Tintinnid abundance was much greater in March (500 cells l^-1), corresponding to a bloom of Stensomella nivalis compared to May (30 cells l^-1). Nonetheless, high numbers of species were encountered on both dates: 32 in March and 39 in May, respectively. Diversity was higher (H2.5) for the May date with low tintinnid concentrations. We examined taxonomic diversity and morphological diversity. Variance of lorica length was correlated with taxonomic diversity, in contrast to variance of lorica diameter, which was nearly invariant. We suggest that either species with similar lorica diameters exploit different prey items or competition for prey items is not the dominant factor in structuring tintinnid communities.      

Breeding pelagic copepods

Summary A cultivation technique has been developed to breed marine pelagic copepods for experimental purposes. Heterotrophic dinoflagellates occurring in the copepod cultures prevent the cultures from fouling due to sedimentation of autotrophic algae, administered daily from continuous cultures. The dinoflagellates keep themselves well in suspension, consume any excess of algae and dead organic material, and, importantly, appear to be an excellent food for the copepods (KLEIN BRETELER, 1980).At presentPseudocalanus elongatus, Acartia clausi, Centropages hamatus andTemora longicornis have been bred through 10, 11, 33, and 35 filial generations, respectively, and are still breeding continuously. Growth rate and isochronal development were dependent on both the concentration of food and the presence of dinoflagellates.     

Deep pelagic biology

The deep pelagic habitat is a vast volume of cold, dark water where food is scarce and bioluminescence is the principal source of light and communication. Understanding the adaptations that allow animals to successfully inhabit this daunting realm has been a difficult challenge because investigators have had to conduct their work remotely. Research in the deep water column is going through an essential transformation from indirect to direct methods as undersea vehicles provide unprecedented access, new capabilities, and new perspectives. Traditional methods have accurately documented the meso- and macro-scale zoogeographic patterns of micronekton and zooplankton, as well as their distribution and migration patterns in the vertical plane. The new in situ technologies have enabled advances in studies of behavior, physiology, and in particular, the role of gelatinous animals in deep pelagic ecology. These discoveries reveal a deep-water fauna that is complex and diverse and still very poorly known.     

长山群岛海域真核微藻粒级结构及扇贝摄食选择性

采用高通量测序-分子鉴定分级技术于2019年对长山群岛全海域真核微藻粒级结构进行了研究。结果发现,春季以中（47%）、小粒级（41%）为主,夏季以小（39%）、大粒级（38%）为主,秋季以大粒级（60%）为主,春、夏、秋季小、中、大粒级微藻比例为42：47：11、39：23：38、22：18：60。小粒级微藻优势种为细小微胞藻（Micromonas pusilla）、融合微胞藻（Micromonas commoda）和金牛微球藻（Ostreococcus tauri）,中粒级微藻优势种为剧毒卡尔藻（Karlodinium veneficum）、大粒级微藻优势种为柔弱几内亚藻（Guinardia delicatula）、平野亚历山大藻（Alexandrium hiranoi）、多纹膝沟藻（Gonyaulax polygramma）,综合整个真核微藻群落,春季由中粒径的剧毒卡尔藻占据优势（23.9%）,夏季由大粒径的平野亚历山大藻占据优势（29.4%）,秋季由大粒径的多纹膝沟藻占据优势（66.8%）,有毒甲藻在该海域中占有绝对优势,贝毒累积风险较高,小粒径微藻中金牛微球藻和抑食金球藻曾在渤海引发褐潮,潜在威胁该海域贝类养殖业。虾夷扇贝对小粒级和大粒级微藻的选择性较低,对中粒级微藻的选择性较高,尤其对水体中优势种剧毒卡尔藻一直表现出主动选择。光学需氧量、无机氮、溶解氧、石油类及部分重金属Cd、As、Hg影响着整个长山群岛海域真核微藻粒级结构时空演变。     

Particle agglutination assays to identify fibronectin and collagen cell surface receptors and lectins in Aeromonas and Vibrio species

A rapid particle agglutination assay (PAA) utilizing latex beads coated with connective tissue and serum proteins was evaluated for its ability to identify fibronectin, collagen (types I and IV), fibrinogen, and transferrin cell surface receptors on Vibrio and Aeromonas strains isolated from diseased fish, human infections, and the environment. Similar tests were performed to screen for cell surface lectins. Vibrio as well as Aeromonas strains were found to bind connective tissue proteins (collagen types I, II, and IV and fibronectin), serum proteins (i.e., fibrinogen), and glycoproteins (bovine submaxillary mucin, hog gastric mucin, orosomucoid, and fetuin) immobilized on the latex particles. The specificity of the agglutination reaction was studied by particle agglutination inhibition assays performed by preincubating bacterial suspensions in solutions containing either gelatin (for the various connective tissue protein PAA reagents) or sialic acid-rich glycoproteins (for the various glycoprotein PAA reagents). Expression of cell surface receptors for connective tissue proteins was found to depend on culture methods.     

Mycoplasma-latex agglutination reaction

Morton, Harry E. (University of Pennsylvania, Philadelphia). Mycoplasma-latex agglutination reaction. J. Bacteriol. 92:1196-1205. 1966.-The building up of Mycoplasma cell mass through adsorption to carrier particles as a method for enhancing the agglutination reaction to identify Mycoplasma is described. Mycoplasma cells of human, avian, swine, goat, sewage, and tissue-culture origin were adsorbed to latex particles (0.81 mu) and then were agglutinated by immune sera. The adsorption was demonstrated by electron microscopy. Either the cells or their antibodies, depending on which came into contact with the latex particles first, were adsorbed. The test, completed in less than 2 hr, consisted of serially diluting immune sera with buffered saline, adding the antigen, incubating in a water bath, centrifuging, and reading the reaction under 50 x microscope magnification. The antigen in each reaction tube, representing the growth from about 1.6 ml of culture, was estimated to contain 23 mug of protein (approximately one-tenth the amount of Mycoplasma cells needed for a direct agglutination reaction). In the sera from rabbits undergoing immunization with Mycoplasma antigens, the presence of anti-Mycoplasma antibodies was detected much sooner in the Mycoplasma-latex agglutination reaction test than in the agar-gel diffusion reaction and the growth inhibition tests. Four different lots of latex particles showed excellent uniformity of behavior and stability during storage and testing.     

Particle agglutination assays to identify fibronectin and collagen cell surface receptors and lectins in Aeromonas and Vibrio species.

A rapid particle agglutination assay (PAA) utilizing latex beads coated with connective tissue and serum proteins was evaluated for its ability to identify fibronectin, collagen (types I and IV), fibrinogen, and transferrin cell surface receptors on Vibrio and Aeromonas strains isolated from diseased fish, human infections, and the environment. Similar tests were performed to screen for cell surface lectins. Vibrio as well as Aeromonas strains were found to bind connective tissue proteins (collagen types I, II, and IV and fibronectin), serum proteins (i.e., fibrinogen), and glycoproteins (bovine submaxillary mucin, hog gastric mucin, orosomucoid, and fetuin) immobilized on the latex particles. The specificity of the agglutination reaction was studied by particle agglutination inhibition assays performed by preincubating bacterial suspensions in solutions containing either gelatin (for the various connective tissue protein PAA reagents) or sialic acid-rich glycoproteins (for the various glycoprotein PAA reagents). Expression of cell surface receptors for connective tissue proteins was found to depend on culture methods.     

Organisation in the pelagic ecosystem

A continuous, steady-state theory has been developed for the abundance of organisms in the pelagic ecosystem as a function of their body weight. It is based on accepted relationships for the weight-dependence of metabolism and growth, in a context where individual organisms are assigned to one of a series of size classes for which the nominal weights increase in a geometric progression. Analysis of the biomass flow in such a representation leads to the conclusion that, in the steady state, the total biomass in any given size class decreases in a regular manner with increasing size. Explicitly,b(w ₂)/b(w ₁)~(w ₂/w ₁)^0.22, whereb(w ₂) andb(w ₁) are the total biomasses in the size classes characterised by weightsw ₂ andw ₁, respectively. The exponent (–0.22) represents a balance between catabolism and anabolism, based on published reviews concerning the revelant parameters. This result agrees favourably with data collected by other workers in the subtropical oceans. The theory can be used to draw conclusions about the functional dynamics of the pelagic ecosystem, such as community respiration and rate of biomass flow.     

High-resolution vertical profiles of pelagic tunicates

The objectives of our research were to obtain high-resolutionvertical profiles of the abundance of pelagic tunicates andto relate their distribution to physical and biological variables.The abundance of doholids (Tunicata: Thaliacea) from near thesurface to near the seafloor was determined by obtaining continuousvideotape recording from a descending submersible. These verticalprofiles, accompanied by temperature and fluorescence measurements,revealed (i) pronounced changes in dololiolid concentrationwithin 2 m depth intervals, and (ii) two general modes of verticaldistribution, one characterized by a peak in abundance in thethennocline and the second by a more or less even distributionthroughout much of the water column. This in situ approach canprovide estimates of zooplankton abundance in near real-time