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Scientific Reports Mar 2022Biogenic amorphous calcium carbonate (ACC) is typically metastable and can rapidly transform through aging, dehydration, and/or heating to crystalline calcium carbonate....
Biogenic amorphous calcium carbonate (ACC) is typically metastable and can rapidly transform through aging, dehydration, and/or heating to crystalline calcium carbonate. Gaining insight into its structure and properties is typically hampered by its tendency to crystallize over short time periods once isolated from the host organism, and also by the small quantities that are usually available for study. Here we describe an exceptionally stable hydrated ACC (HACC) precipitated by the cosmopolitan slime mold Fuligo septica (L.) F.H. Wigg. (1780). A single slime mold can precipitate up to a gram of HACC over the course of one night. Powder x-ray diffraction (XRD) patterns, transmission electron microscopy images, infrared absorption spectra, together with the lack of optical birefringence are consistent with an amorphous material. XRD simulations, supported by thermogravimetric and evolved gas analysis data, are consistent with an intimate association of organic matter with ~ 1-nm-sized ACC units that have monohydrocalcite- and calcite-like nano-structural properties. It is postulated that this association imparts the extreme stability of the slime mold HACC by inhibiting loss of HO and subsequent crystallization. The composition, structure, and thermal behavior of the HACC precipitated by F. septica collected over 8000 km apart and in markedly different environments, suggests a common structure, as well as similar biochemical and biomineralization mechanisms.
Topics: Animals; Calcium Carbonate; Chemical Phenomena; Crystallization; Dogs; Myxomycetes; Physarida; X-Ray Diffraction
PubMed: 35256681
DOI: 10.1038/s41598-022-07648-9 -
Philosophical Transactions of the Royal... Jun 2019Learning and memory are indisputably key features of animal success. Using information about past experiences is critical for optimal decision-making in a fluctuating...
Learning and memory are indisputably key features of animal success. Using information about past experiences is critical for optimal decision-making in a fluctuating environment. Those abilities are usually believed to be limited to organisms with a nervous system, precluding their existence in non-neural organisms. However, recent studies showed that the slime mould Physarum polycephalum, despite being unicellular, displays habituation, a simple form of learning. In this paper, we studied the possible substrate of both short- and long-term habituation in slime moulds. We habituated slime moulds to sodium, a known repellent, using a 6 day training and turned them into a dormant state named sclerotia. Those slime moulds were then revived and tested for habituation. We showed that information acquired during the training was preserved through the dormant stage as slime moulds still showed habituation after a one-month dormancy period. Chemical analyses indicated a continuous uptake of sodium during the process of habituation and showed that sodium was retained throughout the dormant stage. Lastly, we showed that memory inception via constrained absorption of sodium for 2 h elicited habituation. Our results suggest that slime moulds absorbed the repellent and used it as a 'circulating memory'. This article is part of the theme issue 'Liquid brains, solid brains: How distributed cognitive architectures process information'.
Topics: Biological Transport; Decision Making; Learning; Memory; Physarum polycephalum; Sodium
PubMed: 31006372
DOI: 10.1098/rstb.2018.0368 -
Plasmodium development in the myxomycete Physarum polycephalum: genetic control and cellular events.Microbiology (Reading, England) Oct 1995
Review
Topics: Animals; Cell Cycle; Cell Differentiation; Eukaryotic Cells; Gene Expression; Mating Factor; Mutation; Peptides; Physarum polycephalum
PubMed: 7581996
DOI: 10.1099/13500872-141-10-2355 -
Molecules (Basel, Switzerland) Oct 2016Group I introns in nuclear ribosomal RNA of eukaryotic microorganisms are processed by splicing or circularization. The latter results in formation of full-length...
Group I introns in nuclear ribosomal RNA of eukaryotic microorganisms are processed by splicing or circularization. The latter results in formation of full-length circular introns without ligation of the exons and has been proposed to be active in intron mobility. We applied qRT-PCR to estimate the copy number of circular intron RNA from the myxomycete . In exponentially growing amoebae, the circular introns are nuclear and found in 70 copies per cell. During heat-shock, the circular form is up-regulated to more than 500 copies per cell. The intron harbours two ribozymes that have the potential to linearize the circle. To understand the structural features that maintain circle integrity, we performed chemical and enzymatic probing of the splicing ribozyme combined with molecular modeling to arrive at models of the inactive circular form and its active linear counterpart. We show that the two forms have the same overall structure but differ in key parts, including the catalytic core element P7 and the junctions at which reactions take place. These differences explain the relative stability of the circular species, demonstrate how it is prone to react with a target molecule for circle integration and thus supports the notion that the circular form is a biologically significant molecule possibly with a role in intron mobility.
Topics: Heat-Shock Response; Introns; Myxomycetes; RNA, Catalytic
PubMed: 27809244
DOI: 10.3390/molecules21111451 -
Proceedings of the National Academy of... Sep 2021
Topics: Physarum polycephalum
PubMed: 34470820
DOI: 10.1073/pnas.2105928118 -
Distribution characteristics and diversity of myxomycetes in three parallel rivers in Yunnan, China.PloS One 2024Three Parallel Rivers is one of the world's biodiversity hotspots. However, the research on myxomycetes diversity is scarce in this area. Random sampling was used to...
Three Parallel Rivers is one of the world's biodiversity hotspots. However, the research on myxomycetes diversity is scarce in this area. Random sampling was used to investigate myxomycetes' diversity and distribution characteristics in this area. One hundred and seventeen species, including three varieties, were obtained, belonging to 28 genera, nine families, and six orders, with Arcyria cinerea and Physarum viride being the dominant species. Moreover, four species and one variety were first reported in China. Twenty-six species and one variety were first reported in Yunnan Province. The species' most commonly utilized substrate for fruiting bodies was decaying wood, and Cribraria was the dominant genus. The species diversity was most abundant in mixed broadleaf-conifer forests. Species similarity between coniferous and broad-leaved forests was much higher than the pairwise comparison of other forest types. NMDS analysis shows that substrate and forest types had insignificant effects on myxomycetes communities, while river valley had a significant effect. The myxomycetes community similarity between river valleys is unrelated to geographical proximity.
Topics: Humans; Myxomycetes; Rivers; China; Forests; Biodiversity; Tracheophyta; Trees
PubMed: 38165993
DOI: 10.1371/journal.pone.0293260 -
European Journal of Biochemistry Jan 19791. During synchronous growth of the acellular slime mould Physarum polycephalum the free amino pool had two maxima, one of 650 units [nmol/plasmodium dry weight (mg)] at...
1. During synchronous growth of the acellular slime mould Physarum polycephalum the free amino pool had two maxima, one of 650 units [nmol/plasmodium dry weight (mg)] at metaphase and the other of 780 units in mid G2 with minima of 550 units before and after mitosis. 2. Proline formed 20--25% of the total pool with aspartic acid, glutamic acid, threonine, valine, leucine, lysine and arginine making up 55% of the pool. 3. The fluctuation of proline during the mitotic cycle was quite different from that of the other amino acids and was transiently very low during telophase.
Topics: Amino Acids; Cell Cycle; Mitosis; Physarum; Proline; Time Factors
PubMed: 436826
DOI: 10.1111/j.1432-1033.1979.tb12802.x -
Proceedings of the National Academy of... Oct 1997The Mycetozoa include the cellular (dictyostelid), acellular (myxogastrid), and protostelid slime molds. However, available molecular data are in disagreement on both... (Comparative Study)
Comparative Study
The Mycetozoa include the cellular (dictyostelid), acellular (myxogastrid), and protostelid slime molds. However, available molecular data are in disagreement on both the monophyly and phylogenetic position of the group. Ribosomal RNA trees show the myxogastrid and dictyostelid slime molds as unrelated early branching lineages, but actin and beta-tubulin trees place them together as a single coherent (monophyletic) group, closely related to the animal-fungal clade. We have sequenced the elongation factor-1alpha genes from one member of each division of the Mycetozoa, including Dictyostelium discoideum, for which cDNA sequences were previously available. Phylogenetic analyses of these sequences strongly support a monophyletic Mycetozoa, with the myxogastrid and dictyostelid slime molds most closely related to each other. All phylogenetic methods used also place this coherent Mycetozoan assemblage as emerging among the multicellular eukaryotes, tentatively supported as more closely related to animals + fungi than are green plants. With our data there are now three proteins that consistently support a monophyletic Mycetozoa and at least four that place these taxa within the "crown" of the eukaryote tree. We suggest that ribosomal RNA data should be more closely examined with regard to these questions, and we emphasize the importance of developing multiple sequence data sets.
Topics: Amino Acid Sequence; Animals; Biological Evolution; Cloning, Molecular; Dictyostelium; Evolution, Molecular; Fungal Proteins; Genes, Fungal; Introns; Molecular Sequence Data; Myxomycetes; Peptide Elongation Factor 1; Peptide Elongation Factors; Phylogeny; Physarum; Polymerase Chain Reaction; Reproducibility of Results; Sequence Analysis, DNA; Sequence Homology, Amino Acid
PubMed: 9342353
DOI: 10.1073/pnas.94.22.12007 -
The Journal of Cell Biology Jan 1976The metaphase spindle of haploid Dictyostelium discoideum (n = 7) is 2 mum long. It consists of some 20 microtubules which seem continuous between the spindle pole...
The metaphase spindle of haploid Dictyostelium discoideum (n = 7) is 2 mum long. It consists of some 20 microtubules which seem continuous between the spindle pole bodies and there are about 20 chromosomal microtubules at each end of the spindle. During anaphase the central spindle elongates and the chromosomal microtubules shorten. The spindle length and structure at this stage suggests that lengthening is caused by elongation as well as parallel sliding of the nonchromosomal microtubules. The nuclear envelope remains mostly intact during mitosis, and nuclear separation through medial constriction takes place when the spindle is 6 mum long. Cytokinesis occurs when the spindle is 10 mum long. At that time the kinetochores double in size. During interphase, the spindle pole body separates from the nucleus to a distance of 0.7 mum, and it returns at the onset of the next prophase when it becomes functionally double, thereby starting the formation of a central spindle. When comparing mitosis in the cellular slime molds Polysphondylium violaceum and D. discoideum, several similarities and some differences are apparent.
Topics: Cell Division; Cell Nucleus; Dictyostelium; Microscopy, Electron; Microtubules; Myxomycetes
PubMed: 942722
DOI: 10.1083/jcb.68.1.113 -
ELife Mar 2023Veins in vascular networks, such as in blood vasculature or leaf networks, continuously reorganize, grow or shrink, to minimize energy dissipation. Flow shear stress on...
Veins in vascular networks, such as in blood vasculature or leaf networks, continuously reorganize, grow or shrink, to minimize energy dissipation. Flow shear stress on vein walls has been set forth as the local driver for a vein's continuous adaptation. Yet, shear feedback alone cannot account for the observed diversity of vein dynamics - a puzzle made harder by scarce spatiotemporal data. Here, we resolve network-wide vein dynamics and shear rate during spontaneous reorganization in the prototypical vascular networks of . Our experiments reveal a plethora of vein dynamics (stable, growing, shrinking) where the role of shear is ambiguous. Quantitative analysis of our data reveals that (a) shear rate indeed feeds back on vein radius, yet, with a time delay of 1-3 min. Further, we reconcile the experimentally observed disparate vein fates by developing a model for vein adaptation within a network and accounting for the observed time delay. The model reveals that (b) vein fate is determined by parameters - local pressure or relative vein resistance - which integrate the entire network's architecture, as they result from global conservation of fluid volume. Finally, we observe avalanches of network reorganization events that cause entire clusters of veins to vanish. Such avalanches are consistent with network architecture integrating parameters governing vein fate as vein connections continuously change. As the network architecture integrating parameters intrinsically arise from laminar fluid flow in veins, we expect our findings to play a role across flow-based vascular networks.
Topics: Veins; Physarum polycephalum
PubMed: 36916885
DOI: 10.7554/eLife.78100