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The Science of the Total Environment Jun 2024Microplastics (MP) have become a well-known and widely investigated environmental pollutant. Despite the huge amount of new studies investigating the potential threat...
Microplastics (MP) have become a well-known and widely investigated environmental pollutant. Despite the huge amount of new studies investigating the potential threat posed by MP, the possible uptake and trophic transfer in lower trophic levels of freshwater ecosystems remains understudied. This study aims to investigate the internalization and potential trophic transfer of fluorescent polystyrene (PS) beads (0.5 μm, 3.6 × 10 particles/mL; 6 μm, 2.1 × 10 particles/mL) and fragments (<30 μm, 5 × 10 particles/mL) in three unicellular eukaryotes. This study focuses on the size-dependent uptake of MP by two freshwater Ciliophora, Tetrahymena pyriformis, Paramecium caudatum and one Amoebozoa, Amoeba proteus, serving also as predator for experiments on potential trophic transfer. Size-dependent uptake of MP in all three unicellular eukaryotes was shown. P. caudatum is able to take up MP fragments up to 27.7 μm, while T. pyriformis ingests particles up to 10 μm. In A. proteus, small MP (PS and PS) were taken up via pinocytosis and were detected in the cytoplasm for up to 14 days after exposure. Large PS-MP (PS) were detected in A. proteus only after predation on MP-fed Ciliophora. These results indicate that A. proteus ingests larger MP via predation on Ciliophora (PS), which would not be taken up otherwise. This study shows trophic transfer of MP at the base of the aquatic food web and serves as basis to study the impact of MP in freshwater ecosystems.
Topics: Microplastics; Water Pollutants, Chemical; Food Chain; Polystyrenes; Fresh Water; Environmental Monitoring; Tetrahymena pyriformis; Amoeba; Paramecium caudatum; Particle Size
PubMed: 38621530
DOI: 10.1016/j.scitotenv.2024.172470 -
PLoS Biology Apr 2024Exploring the mechanisms that underpin symbiosis requires an understanding of how these complex interactions are maintained in diverse model systems. The ciliate...
Exploring the mechanisms that underpin symbiosis requires an understanding of how these complex interactions are maintained in diverse model systems. The ciliate protist, Paramecium bursaria, offers a valuable insight into how emergent endosymbiotic interactions have evolved.
Topics: Paramecium; Chlorella; Symbiosis; Ciliophora
PubMed: 38573881
DOI: 10.1371/journal.pbio.3002563 -
Cell Reports Apr 2024In the ciliate Paramecium, precise excision of numerous internal eliminated sequences (IESs) from the somatic genome is essential at each sexual cycle. DNA...
In the ciliate Paramecium, precise excision of numerous internal eliminated sequences (IESs) from the somatic genome is essential at each sexual cycle. DNA double-strands breaks (DSBs) introduced by the PiggyMac endonuclease are repaired in a highly concerted manner by the non-homologous end joining (NHEJ) pathway, illustrated by complete inhibition of DNA cleavage when Ku70/80 proteins are missing. We show that expression of a DNA-binding-deficient Ku70 mutant (Ku70-6E) permits DNA cleavage but leads to the accumulation of unrepaired DSBs. We uncoupled DNA cleavage and repair by co-expressing wild-type and mutant Ku70. High-throughput sequencing of the developing macronucleus genome in these conditions identifies the presence of extremities healed by de novo telomere addition and numerous translocations between IES-flanking sequences. Coupling the two steps of IES excision ensures that both extremities are held together throughout the process, suggesting that DSB repair proteins are essential for assembly of a synaptic precleavage complex.
Topics: Paramecium; DNA Cleavage; DNA Breaks, Double-Stranded; Genome, Protozoan; Ku Autoantigen; DNA Repair; Protozoan Proteins; DNA End-Joining Repair
PubMed: 38547127
DOI: 10.1016/j.celrep.2024.114001 -
Microorganisms Mar 2024The process of sexual reproduction in eukaryotes starts when gametes from two different sexes encounter each other. , a unicellular eukaryote, undergoes conjugation and...
The process of sexual reproduction in eukaryotes starts when gametes from two different sexes encounter each other. , a unicellular eukaryote, undergoes conjugation and uses a gametic nucleus to enter the sexual reproductive process. The molecules responsible for recognizing mating partners, hypothetically called mating-type substances, are still unclear. We have identified an O-type mating substance polypeptide and its gene sequence using protein chemistry, molecular genetics, immunofluorescence, RNA interference, and microinjection. The O-type substance is a polypeptide found in the ciliary membranes, located from the head to the ventral side of cells. The O-type substance has a kinase-like domain in its N-terminal part located outside the cell and four EF-hand motifs that bind calcium ions in its C-terminal part located inside the cell. RNA interference and immunofluorescence revealed that this polypeptide positively correlated with the expression of mating reactivity. Microinjection of an expression vector incorporating the OPc-MSP gene () induced additional O mating type in the recipient clones of different mating types or syngen. Phylogenetic analysis indicates that this gene is widely present in eukaryotes and exhibits high homology among closely related species. The OPc-MSP () gene had nine silent mutations compared to the complementary mating type of the E homologue gene.
PubMed: 38543639
DOI: 10.3390/microorganisms12030588 -
Journal of Ayub Medical College,... 2023A group of eukaryotic organisms that are either free-living or parasitic and feed on organic matter, such as microorganisms or organic detritus. This group is referred...
BACKGROUND
A group of eukaryotic organisms that are either free-living or parasitic and feed on organic matter, such as microorganisms or organic detritus. This group is referred to as a polyphyletic classification. They can be found in a wide variety of patterns and sizes, ranging from an amoeba, which can vary its shape, to a paramecium, which has a fixed shape and a complicated structure. The objective was to find out the occurrence of Entamoeba gingivalis and Trichomonas among Dental Patients visiting the Periodontology Department Dental Section, Sandeman, Provincial Hospital Quetta.
METHODS
The study design was randomized cross-sectional and conducted in the Department of Periodontology Dental Section, Sandeman Provincial Hospital Quetta, from March 2022 to February 2023. A total of 110 known cases of periodontitis and gingivitis were recruited in this study, and further to laboratory work the bacterial biofilm samples were collected from both gingivitis and periodontitis patients. The dental plaque was placed on individual glass microscope slides and a drop of saline and mixed and covered with a coverslip. The wet smear was examined immediately under 40X, and the objective for the presence and absence of motile amoebae or flagellated protozoa was recorded. .
RESULTS
out of 110 known cases of periodontitis and gingivitis 91 (83%) patients were males and 19 (17%) were females among 110 patients, 40 (36%) patients were periodontitis and 70 (64%) patients were gingivitis. Among 40 (36%) periodontitis patients 3(7.5%) were Entamoeba gingivalis and 4(10%) were Trichomonas Tenax while 70 (64%) cases of Gingivitis 20 (28%) of Entamoeba gingivalis and 1(1%) Trichomonas tenax was recorded. No patient had both species of protozoa were seen in this study.
CONCLUSION
The results of this study revealed the frequency of occurrence of E. gingivalis and T. tenax and the state of periodontitis and gingivitis. The prevalence of E. gingivalis was higher than T. tenax. We recommended further research with a higher number of patients and may use more advanced and reliable laboratory techniques such as PCR and electron microscopy.
Topics: Male; Female; Humans; Trichomonas; Entamoeba; Cross-Sectional Studies; Gingivitis; Periodontitis
PubMed: 38406902
DOI: 10.55519/JAMC-S4-12660 -
Communications Biology Feb 2024Unicellular eukaryotes represent tremendous evolutionary diversity. However, the molecular mechanisms underlying this diversity remain largely unexplored, partly due to...
Application of RNA interference and protein localization to investigate housekeeping and developmentally regulated genes in the emerging model protozoan Paramecium caudatum.
Unicellular eukaryotes represent tremendous evolutionary diversity. However, the molecular mechanisms underlying this diversity remain largely unexplored, partly due to a limitation of genetic tools to only a few model species. Paramecium caudatum is a well-known unicellular eukaryote with an unexpectedly large germline genome, of which only two percent is retained in the somatic genome following sexual processes, revealing extensive DNA elimination. However, further progress in understanding the molecular mechanisms governing this process is hampered by a lack of suitable genetic tools. Here, we report the successful application of gene knockdown and protein localization methods to interrogate the function of both housekeeping and developmentally regulated genes in P. caudatum. Using these methods, we achieved the expected phenotypes upon RNAi by feeding, and determined the localization of these proteins by microinjection of fusion constructs containing fluorescent protein or antibody tags. Lastly, we used these methods to reveal that P. caudatum PiggyMac, a domesticated piggyBac transposase, is essential for sexual development, and is likely to be an active transposase directly involved in DNA cleavage. The application of these methods lays the groundwork for future studies of gene function in P. caudatum and can be used to answer important biological questions in the future.
Topics: Paramecium caudatum; RNA Interference; Genome; Transposases; Household Work
PubMed: 38374195
DOI: 10.1038/s42003-024-05906-2 -
Communicative & Integrative Biology 2024I summarize my recent theorizing on orientation and navigation across life. Organisms use navigational servomechanisms working with oscillators to get to goals....
I summarize my recent theorizing on orientation and navigation across life. Organisms use navigational servomechanisms working with oscillators to get to goals. Navigational servomechanisms track errors from the best direction of travel and initiate action to correct the error. They work with endogenously generated action patterns, oscillations produced by oscillators, to adjust the course of travel. The theme applies to all scales of life from micrometers to thousands of kilometers. Servomechanisms and oscillators also characterize some other domains of cognition.
PubMed: 38173690
DOI: 10.1080/19420889.2023.2293268 -
Aquatic Toxicology (Amsterdam,... Feb 2024Biodiversity loss resulting from environmental pollution is a global concern. While interspecific interactions are central to ecology, the impact of environmental...
Biodiversity loss resulting from environmental pollution is a global concern. While interspecific interactions are central to ecology, the impact of environmental pollution on predator-prey interactions and its ecological consequences, such as extinction and biodiversity loss, remain unclear. To investigate the effects of antibiotic exposure on predation strength and the resulting ecological consequence, the Didinium-Paramecium was utilized as a predator-prey model and exposed to nitrofurazone or erythromycin, two common pollutants, respectively. Initially, we determined prey population growth dynamics, body size, and predator numerical-functional responses. Subsequently, these above parameters were integrated into a mathematical model of predator-prey predation. Then both the long time-series data and phase portraits obtained through model simulation were used to estimate interaction strength and to predict the outcome of predator-prey coexistence. Our results revealed that exposure to either antibiotic significantly reduced prey population growth parameters (e.g., μ and K) while increasing individual body size. The combined effects of antibiotic exposure and predation pressure on population growth inhibition or body size promotion were variable, mostly additive, with a few cases of synergy and extremely rare antagonism, depending on antibiotic exposure concentration. As antibiotic exposure concentration increased, the predator r generally declined, while functional responses varied depending on specific parameters, implying a decrease in predator-prey interaction strength. Analyses of phase portrait features showed that the population oscillation amplitude decreased with increasing antibiotic exposure concentrations, the cycle length of adjacent peaks increased, and prey extinction occurred earlier. In conclusion, antibiotic exposure reduced both predator and prey fitness, underlying the reason antibiotics reduces the strength of predator-prey interaction. Despite the indirect benefits of prey gain from this, the presence of predators can expedite the process of prey extinction caused by antibiotic exposure.
Topics: Animals; Anti-Bacterial Agents; Water Pollutants, Chemical; Population Dynamics; Population Growth; Biodiversity; Predatory Behavior; Food Chain
PubMed: 38160499
DOI: 10.1016/j.aquatox.2023.106814 -
Life Science Alliance Feb 2024Chromosome (SMC) proteins are a large family of ATPases that play important roles in the organization and dynamics of chromatin. They are central regulators of...
Chromosome (SMC) proteins are a large family of ATPases that play important roles in the organization and dynamics of chromatin. They are central regulators of chromosome dynamics and the core component of condensin. DNA elimination during zygotic somatic genome development is a characteristic feature of ciliated protozoa such as This process occurs after meiosis, mitosis, karyogamy, and another mitosis, which result in the formation of a new germline and somatic nuclei. The series of nuclear divisions implies an important role of SMC proteins in sexual development. The relationship between DNA elimination and SMC has not yet been described. Here, we applied RNA interference, genome sequencing, mRNA sequencing, immunofluorescence, and mass spectrometry to investigate the roles of SMC components in DNA elimination. Our results show that SMC4-2 is required for genome rearrangement, whereas SMC4-1 is not. Functional diversification of SMC4 in Paramecium led to a formation of two paralogues where SMC4-2 acquired a novel, development-specific function and differs from SMC4-1. Moreover, our study suggests a competitive relationship between these two proteins.
Topics: Paramecium; Cell Cycle Proteins; Chromosomes; DNA; Meiosis
PubMed: 38056908
DOI: 10.26508/lsa.202302281 -
Annual Review of Genetics Nov 2023The ciliate genus served as one of the first model systems in microbial eukaryotic genetics, contributing much to the early understanding of phenomena as diverse as... (Review)
Review
The ciliate genus served as one of the first model systems in microbial eukaryotic genetics, contributing much to the early understanding of phenomena as diverse as genome rearrangement, cryptic speciation, cytoplasmic inheritance, and endosymbiosis, as well as more recently to the evolution of mating types, introns, and roles of small RNAs in DNA processing. Substantial progress has recently been made in the area of comparative and population genomics. species combine some of the lowest known mutation rates with some of the largest known effective populations, along with likely very high recombination rates, thereby harboring a population-genetic environment that promotes an exceptionally efficient capacity for selection. As a consequence, the genomes are extraordinarily streamlined, with very small intergenic regions combined with small numbers of tiny introns. The subject of the bulk of research, the ancient species complex, is descended from two whole-genome duplication events that retain high degrees of synteny, thereby providing an exceptional platform for studying the fates of duplicate genes. Despite having a common ancestor dating to several hundred million years ago, the known descendant species are morphologically indistinguishable, raising significant questions about the common view that gene duplications lead to the origins of evolutionary novelties.
Topics: Paramecium; Evolution, Molecular; Genomics; Genome; Mutation Rate
PubMed: 38012024
DOI: 10.1146/annurev-genet-071819-104035