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Extant symbioses illustrate endosymbiosis is a driving force for evolution and diversification. In the ciliate Paramecium bursaria, the endosymbiotic alga Chlorella variabilis in perialgal vacuole localizes beneath the host cell cortex by adhesion between the perialgal vacuole membrane and host mitochondria. We investigated whether host mitochondria are also affected by algal endosymbiosis. Transmission electron microscopy of host cells showed fewer mitochondria beneath the algae-bearing host cell cortex than that of alga-free cells. To compare the density and distribution of host mitochondria with or without symbiotic algae, we developed a monoclonal antibody against Paramecium mitochondria. Immunofluorescence microscopy with the monoclonal antibody showed that the mitochondrial density of the algae-bearing P. bursaria was significantly lower than that of the alga-free cells. The total cell protein concentration of alga-free P. bursaria cells was approximately 1.8-fold higher than that of algae-bearing cells, and the protein content of mitochondria was significantly higher in alga-free cells than that in the algae-bearing cells. These results corresponded with those obtained by transmission electron and immunofluorescence microscopies. This paper shows that endosymbiotic algae affect reduced mitochondrial number in the host P. bursaria significantly. [ABSTRACT FROM AUTHOR]

The effect of adrenaline in various concentrations and dopamine at a concentration of 10–10 mol/mL on the behavior of Paramecium caudatum was studied. It is shown that adrenaline reduces motor activity and changes the movement strategy of these protozoans; a dose-dependent behavioral response on the drug concentration was observed. This effect can be explained by the presence of adrenaline receptors located on the surface of the cell membrane. To study the direct effect of adrenaline on alpha and beta adrenergic receptors, the effect of non-selective adrenoblockers nicergoline and timolol is considered in this paper. At the same time, dopamine at a concentration of 10–10 mol/mL does not have a significant effect on the nature and magnitude of motor activity during the entire registration time, since this organism does not have receptors for this mediator. The proposed method makes it possible to quickly and objectively assess the nature of the effects of various pharmaceuticals acting on the catecholamine system. [ABSTRACT FROM AUTHOR]

Ocean internal waves appear as irregular bright and dark stripes on synthetic aperture radar (SAR) remote sensing images. Ocean internal waves detection in SAR images consequently constituted a difficult and popular research topic. In this paper, ocean internal waves are detected in SAR images by employing the faster regions with convolutional neural network features (Faster R-CNN) framework; for this purpose, 888 internal wave samples are utilized to train the convolutional network and identify internal waves. The experimental results demonstrate a 94.78% recognition rate for internal waves, and the average detection speed is 0.22 s/image. In addition, the detection results of internal wave samples under different conditions are analyzed. This paper lays a foundation for detecting ocean internal waves using convolutional neural networks. [ABSTRACT FROM AUTHOR]

This paper investigates the control of multi-agent systems inspired by chemotaxis of microorganisms. Chemotaxis is a biological phenomenon wherein organisms in an environment are attracted to food but move away from toxins. The problem addressed here is a formation control problem, i.e., a design problem of distributed controllers wherein the relative positions of agents become the desired positions with the progression of time. To solve this problem, we introduce a performance index that quantifies the achieved degree of a desired formation, and decompose it into local indices that can be embedded in the distributed controllers. Based on this, we propose formation controllers inspired by chemotaxis of Escherichia coli (E. coli), where each agent moves with the aim of increasing the corresponding local performance index using the chemotaxis controller of E. coli. In addition, to improve the accuracy of the resulting formation, we present Paramecium caudatum (P. caudatum)-type formation controllers by replacing the chemotaxis controller of E. coli used above with that of P. caudatum. The effectiveness is demonstrated by a comparison with the E. coli-type formation controllers via numerical simulation. This result implies that various chemotaxis controllers can be used in our method and the performance of the resulting controllers can be improved by choosing an appropriate chemotaxis controller. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are essential for the viability of cells, while excess levels can be lethal by damaging proteins and nucleic acids. It is imperative to identify and elucidate the various cellular functions for which ROS molecules have a role. In this paper, the role of ROS in the regulation of ultradian rhythms in the ciliated protozoan Paramecium tetraurelia is examined. The frequency of spontaneous behavioral responses in Parameciun display a well-established ultradian rhythm with a periodicity of approximately 50–60 min. The artificial elevation of cytoplasmic ROS concentrations is shown to completely eliminate the rhythm in a reversible manner. Furthermore, the use of RNA interference techniques to knockdown the expression of superoxide dismutase, an enzyme that scavenges excess cytoplasmic ROS, also eliminates the ultradian rhythm. These data indicate that the concentration of ROS plays a role in the generation of the ultradian rhythm. A hypothesis is proposed for the generation of this ultradian rhythm that incorporates a role for ROS. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Some Paramecium species are common research objects in various fields of science. • At the same time, the biodiversity structure of the others is almost unknown. • Here we present a molecular analysis of 60 Cypriostomum strains. • Three main clades has been revealed, each one with internal sub-clusters. • Their occurence reflects a separation into morphospecies and cryptic species. Abstract Although some Paramecium species are suitable research objects in many areas of life sciences, the biodiversity structure of other species is almost unknown. In the current survey, we present a molecular analysis of 60 Cypriostomum strains, which for the first time allows for the study of intra- and interspecific relationships within that subgenus, as well as the assessment of the biogeography patterns of its morphospecies. Analysis of COI mtDNA variation revealed three main clades (separated from each other by approximately 130 nucleotide substitutions), each one with internal sub-clusters (differing by 30 to 70 substitutions – a similar range found between P. aurelia cryptic species and P. bursaria syngens). The first clade is represented exclusively by P. polycaryum ; the second one includes only four strains identified as P. calkinsi. The third cluster seems to be paraphyletic, as it includes P. nephridiatum , P. woodruffi , and Eucandidatus P. hungarianum. Some strains, previously identified as P. calkinsi , had COI sequences identical or very similar to P. nephridiatum ones. Morphological reinvestigation of several such strains revealed common morphological features with P. nephridiatum. The paper contains new information concerning speciation within particular species, i.e. existence of cryptic species within P. polycaryum (three) and in P. nephridiatum (six). [ABSTRACT FROM AUTHOR]

This study investigated the interaction of inorganic aqueous Eu(III), Pb(II), and U(VI) with Paramecium sp., a representative single-celled protozoan that lives in freshwater. Living and prekilled Paramecium cells were tested. The prekilled cells were killed with a fixative. After 24 h exposure of the cells to inorganic aqueous solutions containing Eu(III) or U(VI), analyses by microparticle-induced X-ray emission with a focused beam (<1 μm) did not detect Eu and U in the living cells, whereas Eu and U were detected in the prekilled cells. Size exclusion chromatography coupled with on-line ultraviolet–visible detection and elemental detection by inductively coupled plasma mass spectrometry of the aqueous phases collected after the living cell experiments revealed that a fraction of the Eu, Pb, and U in the aqueous phase bound to a large ( ca . 250 kDa) Paramecium biomolecule and formed a metal-organic complex. The characteristics of the biomolecule were consistent with those of the soluble glycoproteins covering the surfaces of Paramecium cells. These results show that Paramecium cells transform inorganic aqueous Eu, Pb, and U to organic complexes. This paper discusses the relation between this novel complexation and the sorption of these heavy elements on Paramecium cells. [ABSTRACT FROM AUTHOR]

There are a wide range of student emotions in academic settings, but apart from emotions such as interest and well-being, disgust is a negative emotion which might be relevant in biology education, for instance, during dissection or when encountering living animals. This paper addresses the issue of situational disgust during a course at the university using living animals and prepared mounts. The course covers a wide range of organisms from protists (e.g.Paramecium) through invertebrates to vertebrates and uses many methods (e.g. microscopy, dissection, and behavioral observations) and specific content (anatomy, structure, and behavior). The dissection of the trout was rated as most disgusting, followed by working with living woodlice, living earthworms, and living snails. The least disgusting lessons were those dealing with microscopy, mammalian skulls, honeybee dance, and bird flight. Based on animals, macro-invertebrates were rated as most disgusting and mammals as least disgusting. Concerning methods, observing through a microscope was perceived as being least disgusting, followed by experiments without animals, then followed by experiments with living animals and, most disgusting, dissection. Disgust was correlated negatively with interest, well-being, and competence but positively with pressure and boredom. Thus, low disgust is related to high interest, well-being, and competence, while higher disgust is related to higher pressure and boredom. The results show a need for measuring situational disgust in addition to survey studies. They also suggest that perceived disgust negatively affects intrinsic motivation. This has implications for biology teaching, because carrying out dissections or experiencing living animals in the classroom may have a detrimental effect on motivation. [ABSTRACT FROM AUTHOR]

In this paper we assess the role of the protein MKS1 (Meckel syndrome type 1) in the cortical membrane mechanics of the ciliated protist Paramecium. This protein is known to be crucial in the process of cilium formation, and we investigate its putative role in membrane--cytoskeleton attachment. Therefore, we compare cells where the gene coding for MKS1 is silenced to wild-type cells. We found that scanning electron microscopy observation of the cell surface reveals a cup-like structure in wild-type cells that is lost in silenced cells. Since this structure is based on the underlying cytoskeleton, one hypothesis to explain this observation is a disruption of membrane attachment to the cytoskeleton in the absence of MKS1 that should affect plasma membrane mechanics. We test this by probing the mechanics of wild-type and silenced cells by micropipette aspiration. Strikingly, we observe [ABSTRACT FROM AUTHOR]

Paramecium tetraurelia displays a behavioral response to environmental stimuli that involves changes in the direction and speed of swimming. This paper demonstrates that there are periodic variations in the frequency of behavioral responses of individual cells. The frequency of the backward swimming response undergoes repeated oscillations with a period (tau) between 40 and 50 minutes; these oscillations are only slightly affected by the temperature at which the cells have been grown. These data indicate the presence of an ultradian clock that underlies this cellular process. However, growing cells in the presence of low concentrations of LiCl perturbs the ultradian rhythm, with the periodicity being reduced to approximately 11 minutes. The LiCl effect is seen within 10-45 minutes, depending on the concentration of LiCl used, and is completely reversible. In order to determine if the LiCl effect was due to a depletion of inositol, cells were grown in 10 mM myo-inositol for 24 hours prior to the addition of LiCl. It was found that the presence of excess inositol inhibited the perturbation of the periodicity caused by the LiCl. These results signify that Paramecium tetraurelia possesses an endogenous ultradian clock that influences the strength of the behavioral response, and the inositol signaling pathway is most likely involved in the generation of the ultradian rhythm. Therefore, the Paramecium behavioral response is an excellent model system for elucidation of the molecular mechanisms underlying the ultradian rhythms. [ABSTRACT FROM AUTHOR]

Tandem stop codons are extra stop codons hypothesized to be present downstream of genes to act as a backup in case of read-through of the real stop codon. Although seemingly absent from Escherichia coli, recent studies have confirmed the presence of such codons in yeast. In this paper we will analyze the genomes of two ciliate species— Paramecium tetraurelia and Tetrahymena thermophila—that reassign the stop codons TAA and TAG to glutamine, for the presence of tandem stop codons. We show that there are more tandem stop codons downstream of both Paramecium and Tetrahymena genes than expected by chance given the base composition of the downstream regions. This excess of tandem stop codons is larger in Tetrahymena and Paramecium than in yeast. We propose that this might be caused by a higher frequency of stop codon read-through in these species than in yeast, possibly because of a leaky termination machinery resulting from stop codon reassignment. [ABSTRACT FROM AUTHOR]

Abstract: Symbiotic Chlorella F36-ZK isolated from Paramecium bursaria F36 lacks nitrate reductase activity and has constitutive amino acid transport systems. Divalent cations generally accelerate amino acid uptake and Ca2+ affects membrane permeability and H+-ATPase activity. However, Ser uptake by F36-ZK was decreased by divalent cations, especially Ca2+, and the cation had no effect on membrane permeability or H+-ATPase activity. Extracellular Ca2+ contributed to inhibit Ser uptake. The cation selectively inhibited uptake of Ser, Ala and Gln, which are transported via the same system, but not Arg. Based on kinetic analysis of Ser transport, inhibition was noncompetitive, i.e., Ca2+ affected only the V max of Ser uptake. Calcium ions were found in symbiotic Chlorella cells associated with their host by transmission electron microscopy using an oxalate-pyroantimonate method, suggesting the transfer of Ca2+ during symbiosis. From these results obtained in this paper, we discuss the role of divalent cations on amino acid transport in the Paramecium symbiosis. [Copyright &y& Elsevier]

It has been reported that Paramecium proliferates faster when cultured under microgravity in orbit, and slower when cultured under hypergravity. This shows that the proliferation rate of Paramecium affected by gravity. The effect of gravity on Paramecium proliferation has been argued to be direct in a paper with an axenic culture under hypergravity. To clear up uncertainties with regard to the effect of gravity, Paramecium tetraurelia was cultured axenically under hypergravity (20 × g) and the time course of the proliferation was investigated quantitatively by a new non-invasive method, laser-beam optical slice, for measuring the cell density. This method includes optical slicing a part of the culture and computer-aided counting of cells in the sliced volume. The effects of hypergravity were assessed by comparing the kinetic parameters of proliferation that were obtained through a numerical analysis based on the logistic growth equation. Cells grown under 20 × g conditions had a significantly lower proliferation rate, and had a lower population density at the stationary phase. The lowered proliferation rate continued as long as cells were exposed to hypergravity (> one month). Hypergravity reduced the cell size of Paramecium. The long and short axes of the cell became shorter at 20 x g than those of control cells, which indicates a decrease in volume of the cell grown under hypergravity and is consistent with the reported increase in cell volume under microgravity. The reduced proliferation rate implies changes in biological time defined by fission age. In fact the length of autogamy immaturity decreased by measure of clock time, whereas it remained unchanged by measure of fission age. [ABSTRACT FROM AUTHOR]

Since the cell structure or biophysical reaction includes in the interaction between ultrasound and living matter. When multi-cell creature is exposed to ultrasound, this reaction will lead the biological effect becomes complex. Therefore, in this paper, a single cell creature is chosen to study the biological effects induced by ultrasound exposure. The paramecium, which possesses many features typical of higher-order animal cells, was considered an appropriate choice for this study. The ability shown by ultrasound in promoting and/or accelerating many reactions has been shown to be a useful field. The growth phase of paramecium by using the ultrasound irradiation is an important parameter in this study. In our experiment, the exponential and stationary phases were employed.Three important factors must be taken into account when an ultrasonic biological reaction is investigated: the medium system, the bubbles'' field, and the acoustic field. The medium system involves the physical parameters of the medium field. The bubbles'' field includes the reacting bubble size of the liquid and the resonance frequency of the reaction bubbles. The oscillation of the cells in response to the ultrasound radiation is simulated using Rayleigh–Plesset''s bubble activation theory. The resonance frequency of the unicellular creature is then calculated. The acoustic field is about using the diffuse field theory of Sabine to create a uniform sound field for the radiation experiment.The resonance frequency of the paramecium vacuole is among 0.54–1.09 MHz. When the 0.25 and 0.5 MHz frequencies of ultrasound was irradiated in the stationary phase of the paramecium, the relative growth rate was about 20% lower than that of unexposed sample. Therefore, the phenomenon of inhibition and destruction appeared during irradiation. The exponential phase of the paramecium samples appear to be different when irradiated with 1 MHz ultrasound. As can be seen in the results, the maximum relative growth rate was increasing 18% with 1 MHz ultrasound exposure. [Copyright &y& Elsevier]

Centrins are highly conserved, ubiquitous cytoskeletal components which belong to the EF-hand superfamily of Ca2+-modulated proteins. We report here the molecular characterization of new members of the centrin family, Paramecium centrins. Previous studies described the organization of the infraciliary lattice (ICL), the innermost cortical cytoskeletal network of Paramecium, and showed that it was composed of a set of low-molecular-mass, Ca2+-binding polypeptides [Garreau de Loubresse, N., Klotz, C., Vigues, B., Rutin, J & Beisson, J. (1991) Biol. Cell 71, 217-225]. In this paper we show that these polypeptides are recognized by specific anti-centrin polyclonal antibodies. Their microsequences revealed four distinct N-termini. For one of them, ICL1, N-terminal and internal peptide sequences were used for PCR amplification and cloning of a DNA fragment containing a complete centrin coding sequence. The deduced amino acid sequence presents about 50% identify with those of centrins from other species. Further molecular analysis allowed us to identify two additional closely related, co-expressed ICL1 genes, providing the first example of a centrin multigenic family in a microorganism. [ABSTRACT FROM AUTHOR]

Paper punch-out dots soaked in isopropyl alcohol will move about randomly when placed flat on the surface of water, superficially resembling swimming movements of single-celled protists. This exercise is a hands-on and dynamic activity to generate discussion on the generally accepted characteristics of living things. [ABSTRACT FROM AUTHOR]