查看更多>>摘要：The morphology and phylogeny of two new species of pleurostomatid ciliates, Amphilepus weishanensis sp. nov. and A. parapleurosigma sp. nov., collected from Lake Weishan in northern China, were studied using live observation, protargol staining and phylogenetic analyses based on small subunit ribosomal DNA (SSU rDNA) sequence data. In both species, extrusomes form an apical group and contractile vacuoles are distributed along both the dorsal and the ventral margin. Amphileptus weishanensis sp. nov. is characterized by its body size (560-780 x 60-100 lm in vivo) and the possession of five left and 56-61 right somatic kineties, filiform extrusomes and 3-9 macronuclear nodules. Amphileptus parapleurosigma sp. nov. is characterized by possessing 4-6 left and 19-24 right somatic kineties and clavate extrusomes. The SSU rDNA sequences differ among ten similar species by 3-60 bp. Phylogenetic analyses based on the SSU rDNA sequences indicate that the family Amphileptidae is monophyletic while Amphileptus is paraphyletic with Pseudoamphileptus nesting within this genus. (C) 2021 Elsevier GmbH. All rights reserved.
查看更多>>摘要：The formation of double-strand breaks in DNA represents a serious stress for all types of organisms and requires a precisely regulated and organized DNA damage response (DDR) to maintain genetic information and genome integrity. Chlamydomonas reinhardtii possesses the characteristics of both plants and animals and is therefore suitable for the identification of novel genes connected to a wide spectrum of metabolic pathways, including DDR. One very effective tool for the detection and subsequent characterization of new mutants in C. reinhardtii is insertional mutagenesis. We isolated several insertion mutants sensitive to DNA-damaging agents that had disrupted or completely deleted genes with putative functions in the DDR. In most of the analysed mutants, we identified various changes at both ends and even inside the inserted cassette. Using recent information from databases, we were also able to supplement the characteristics of the previously described mutant with a pleiotropic phenotype. In addition, we confirmed the effectiveness of hairpin-PCR as a strategy for the identification of insertion flanking sites and as a tool for the detection of changes at the site of insertion, thus enabling a better understanding of insertion events.(c) 2021 Elsevier GmbH. All rights reserved.
查看更多>>摘要：Zinc finger MYND-type containing 10 (ZMYND10) or BLU is a putative tumor suppressor that inhibits the proliferation of nasopharyngeal carcinoma cells by regulating the cell cycle. On the other hand, some recent studies have also found that ZMYND10 is a ciliary protein that is essential for ciliary structure and function and is mutated in primary ciliary dyskinesia (PCD). Our recent study shows that ZMYND10 is essential for ciliary growth and structure in Paramecium tetraurelia. The results in the current work continually reveal that depletion of ZMYND10 interrupted the process of amitotic macronucleus division in Paramecium. Immunostaining showed that the microtubular backbone of dividing macronucleus disintegrated in cells without ZMYND10. Furthermore, a transcriptomic analysis and RT-qPCR revealed the differential expression of some genes, including DYHA, DYHB, kinesin, kinesin-like proteins and Ran-GTP in ZMYND10-depleted cells, in accordance with their roles in regulating cilia and macronucleus division. (C)& nbsp;2022 Elsevier GmbH. All rights reserved.
查看更多>>摘要：Charles Atwood Kofoid was a scientist of considerable stature and a key figure in the development of protistology in the United States of America during first half of the 20th century. Today he is known mainly for his detailed taxonomic monographs on protists of the marine plankton, specifically dinoflagellates and tintinnid ciliates. Lesser known today is the wide range of Kofoid's work in protistology. Little known is his responsibility for one of the great mistakes of protistology: the existence of a protistan nervous system, the "neuromortorium". Largely unknown is Kofoid's enthusiastic involvement in the eugenics movement. Here, following a brief biography, I will provide a review of Kofoid's enduring contribution to protistology, "the good", then the story of the neuromotorium, "the bad", and finally an account of Kofoid's implication in the eugenics movement, "the ugly". (c) 2022 Elsevier GmbH. All rights reserved.
查看更多>>摘要：Heterotrophic protists play a crucial role in plant growth promotion via nutrient cycling and shift in microbial community composition in the soil ecosystem. Selective predation pressure by protists contributes to the evaluation of plant beneficial traits in rhizospheric bacteria. However, not always all plant growth-promoting bacterial (PGPB) strains are benefitted by predation. This study aimed to examine the predatory effect of Acanthamoeba sp genotype T4 on a range of PGPB strains and their combined impact on early rice seedling growth. Acanthamoeba sp isolated from rice rhizosphere soils were used to assess predation against several PGPB such as Pseudomonas, Bacillus, Enterobacter, Morganella, Stenotrophomonas, Providencia, and Lysinibacillus on Nutrient Yeast Extract agar (NYE) plate. The controlled experiment on the germinated rice seeds (Oryza sativa L.) grown in Petri dishes containing each PGPB strain and Acanthamoeba sp was performed to evaluate the combined impact on plant performance. The PGPB-Acanthamoeba combined treatments in Petri dishes showed significant rice seedling growth compared to PGPB alone, non-PGPB and control. Our results indicated the positive but different impact of Acanthamoeba sp with different PGPB species on early rice plant growth. Further in-depth research should be carried out with diverse protists and PGPB species to assess which protist species can be linked to enhancement of indigenous soil PGPB for improved plant growth.(C)2021 Elsevier GmbH. All rights reserved.
查看更多>>摘要：Karyorelictids are a group of ciliates inhabiting marine and freshwater biotopes and possessing a non-dividing macronucleus. We describe a new freshwater species based on morphology and the 18S rRNA gene sequence data. Loxodes tziscaensis n. sp. can be easily distinguished from other Loxodes species by the arrangement of the nuclear apparatus and features of the buccal and somatic ciliature. The current proposed 18S rRNA phylogeny of Loxodes, including seven Loxodes species, shows two morphologically well-supported groups. Group A (L. rostrum, type species; L. vorax and L. tziscaensis n. sp.) includes species with a single nuclear group (two macronuclei and one micronucleus), in contrast to species of group B, which possess more than one nuclear group (L. striatus, L. magnus, L. kahli, L. penardi, and L. rex). We propose that the last common ancestor of Loxodes was a marine Remanella-like species possessing a single nuclear group. The division and differentiation of the micronucleus into a new macronucleus and the retention of the old macronuclei, independently of cell division, may have been two crucial processes during the evolution and diversification of Loxodes species with one nuclear group into species with multiple nuclear groups.(c) 2021 Elsevier GmbH. All rights reserved.
查看更多>>摘要：The genus Deuteramoeba is one of the six amoebae genera belonging to the best-known amoeba family - Amoebidae (Amoebozoa, Tubulinea), containing such a popular species as Amoeba proteus. However, members of other genera of the family Amoebidae are much less known, and most of the studies of their morphology and ultrastructure date back to the 1970s and 1980s. Since these "classical " species are believed to be "well studied ", their morphology and fine structure rarely become a subject of re-investigation. The absence of modern morphological data may be critical when molecular data of the type strain are not available, and the only way to identify a species is by morphological comparison. For this paper, we performed an ultrastructural study of the strain CCAP 1586/1 - the type strain of the species Deuteramoeba mycophaga. Our study revealed new details of the nuclear structure, including a peripheral layer of filaments and a heterogeneous nucleolus, and provided new data on the cytoplasmic inclusions of this species. We performed a whole-genome amplification of the DNA from a single amoeba cell followed by NGS sequencing and searched for genetic evidence for the presence of a putative nuclear parasite detected in 2017, but found no evidence for the presence of Opisthosporidia. (C) 2021 Elsevier GmbH. All rights reserved.
查看更多>>摘要：The spatial and temporal planktonic ciliate community structure of a large shallow eutrophic lake was described in detail based on a monthly monitoring campaign over 2 years using the quantitative protargol stain approach. We found that there was a large variety and low constancy of ciliate plankton and a clear advantage of several small species. Balanion plancton-icum, Rimostrombidium brachykinetum, and Urotricha farcta contributed 19.7%, 13.4%, and 10.7% to the total abundance, respectively. The ciliate community was significantly varied in different lake regions of different eutrophication levels, and the distribution of some of the main species, especially prostomatids and scuticociliatids, might be closely related to the nutrient level of the lake regions. The seasonal dynamics of ciliate taxa with similar functional feeding habits across regions at different trophic levels are more convergent than those of species with very different functions, and the top-down effect (clado-cerans, rotifers), nutrition, and water temperature were the key factors shaping ciliate community structure. The results of this study accentuate the important effects of species functional diversity on community differences and may improve our knowledge of ciliate diversity and functional ecology in shallow eutrophic lakes.(c) 2021 Published by Elsevier GmbH.
Gomaa, FatmaUtter, Daniel R.Loo, WesleyLahr, Daniel J. G....
14页
查看更多>>摘要：Research on protist-bacteria interactions is increasingly relevant as these associations are now known to play important roles in ecosystem and human health. Free-living amoebae are abundant in all environments and are frequent hosts for bacterial endosymbionts including pathogenic bacteria. However, to date, only a small fraction of these symbionts have been identified, while the structure and composition of the total symbiotic bacterial communities still remains largely unknown. Here, we use the testate amoeba Arcella spp. as model organisms to investigate the specificity and diversity of Arcella- associated microbial communities. High-throughput amplicon sequencing from the V4 region of the 16S rRNA gene revealed high diversity in the bacterial communities associated with the wild Arcella spp. To investigate the specificity of the associated bacterial community with greater precision, we investigated the bacterial communities of two lab-cultured Arcella species, A. hemispherica and A. intermedia, grown in two different media types. Our results suggest that Arcella-bacteria associations are species-specific, and that the associated bacterial community of lab-cultured Arcella spp. remains distinct from that of the surrounding media. Further, each host Arcella species could be distinguished based on its bacterial composition. Our findings provide insight into the understanding of eukaryotic-bacterial symbiosis.(c) 2021 The Author(s). Published by Elsevier GmbH. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
Li, Zhen-WeiLiao, Hung-EnRenta, Person PesonaChen, Yi-Min...
11页
查看更多>>摘要：The current study investigated the potential functions of amoeboid cell formation and migration in a thraustochytrid strain, Aurantiochytrium limacinum BL10. Our results showed that: (1) When the surface of an agar plate was inoculated with BL10, amoeboid cells mainly emerged on the periphery of isolated colonies. The amoeboid cells then migrated outwards to form small vegetative cell clusters, which favored rapid colony expansion. In addition, amoeboid cells were capable of self recognition (i.e. they were able to distinguish BL10 from other thraustochytrid species), and could choose whether to evade (self colonies) or approach (non-self colonies). These observations indicated that amoeboid cells were employed by BL10 to help colonize empty territories and to outcompete other thraustochytrid species in previously colonized territories. (2) When the agar medium was soft, amoeboid cells were able to penetrate the surface and migrate throughout, thereby allowing BL10 to colonize the interior of the solid matrix. This finding suggested that amoeboid cell formation and migration may help Aurantiochytrium colonize the interior of solid matrices to obtain additional nutrients and spatial resources. The mechanisms underlying the regulation of amoeboid cell formation and migration as well as the extraordinary microbial social behaviors of BL10 are also discussed in this article. (C) 2021 Elsevier GmbH. All rights reserved.
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