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Integrative and Comparative Biology Oct 2022Many organisms utilize group aggregation as a method for survival. The freshwater oligochaete, Lumbriculus variegatus (California blackworms) form tightly entangled...
Many organisms utilize group aggregation as a method for survival. The freshwater oligochaete, Lumbriculus variegatus (California blackworms) form tightly entangled structures, or worm "blobs", that have adapted to survive in extremely low levels of dissolved oxygen (DO). Individual blackworms adapt to hypoxic environments through respiration via their mucous body wall and posterior ciliated hindgut, which they wave above them. However, the change in collective behavior at different levels of DO is not known. Using a closed-loop respirometer with flow, we discover that the relative tail reaching activity flux in low DO is ∼75x higher than in the high-DO condition. Additionally, when flow rate is increased to suspend the worm blobs upward, we find that the average exposed surface area of a blob in low DO is ∼1.4x higher than in high DO. Furthermore, we observe emergent properties that arise when a worm blob is exposed to extreme DO levels. We demonstrate that internal mechanical stress is generated when worm blobs are exposed to high DO levels, allowing them to be physically lifted off from the bottom of a conical container using a serrated endpiece. Our results demonstrate how both collective behavior and the emergent generation of internal mechanical stress in worm blobs change to accommodate differing levels of oxygen. From an engineering perspective, this could be used to model and simulate swarm robots, self-assembly structures, or soft material entanglements.
Topics: Animals; Oligochaeta; Oxygen
PubMed: 35689658
DOI: 10.1093/icb/icac089 -
PeerJ 2022The invasive Asian earthworms, and , have been successful in entering North American forests in recent decades, with significant damage to both soils and above-ground...
The invasive Asian earthworms, and , have been successful in entering North American forests in recent decades, with significant damage to both soils and above-ground environments. This success could be driven in part by a polyploid genetic system and parthenogenetic reproduction, often suggested as benefits for invasive species. Therefore, we assessed the genetic population structure, genetic diversity, and reproductive system of both species using morphological traits and panels of microsatellite markers. A total of 216 and 196 from six sites in Vermont USA were analyzed. Although all worms were morphologically hermaphroditic, all the lacked the male pore (the structure allowing pass of sperm between individuals), and only 19% of the possessed the male pore. All earthworms were triploid (scored for three alleles for at least 1 locus, and usually several), and was a mix of triploid and diploid individuals. Notable was the high proportion (80%) of earthworms that were diploid at one site. There was clearly clonal reproduction, with identical seven- locus genotypes observed for earthworms from each site, with as many as 45 individuals with the identical genotype at one site. However, the earthworms were also genetically diverse, with 14 genotypes observed for and 54 for , and with many singleton genotypes (a single individual). Most genotypes (71% for and 92% for ) were found at a single site. The greatest number of genotypes was found at a commercial nursery where fully 23/26 earthworms were singleton genotypes. As expected for the pattern of private clone alleles at sites, several measures of geographic genetic differentiation were positive, and as expected for triploid systems, an AMOVA analysis showed high within-individual genetic diversity. The paradox of clear clonal reproduction, but with a great number of genotypes for each species, and the mix of triploid and diploid individuals could be explained if the worms have been sexually reproductive, with the switch to the uniparental system only recently (or even if sexual reproduction is episodic). Last, a large number of microsatellite loci were recovered for each species and there sequence and suggested PCR primers are provided for free use by other researchers.
Topics: Animals; Male; Oligochaeta; Triploidy; Semen; Genitalia; Genetic Structures
PubMed: 35855901
DOI: 10.7717/peerj.13622 -
ELife Nov 2022Volume electron microscopy (EM) is a time-consuming process - often requiring weeks or months of continuous acquisition for large samples. In order to compare the...
Volume electron microscopy (EM) is a time-consuming process - often requiring weeks or months of continuous acquisition for large samples. In order to compare the ultrastructure of a number of individuals or conditions, acquisition times must therefore be reduced. For resin-embedded samples, one solution is to selectively target smaller regions of interest by trimming with an ultramicrotome. This is a difficult and labour-intensive process, requiring manual positioning of the diamond knife and sample, and much time and training to master. Here, we have developed a semi-automated workflow for targeting with a modified ultramicrotome. We adapted two recent commercial systems to add motors for each rotational axis (and also each translational axis for one system), allowing precise and automated movement. We also developed a user-friendly software to convert X-ray images of resin-embedded samples into angles and cutting depths for the ultramicrotome. This is provided as an open-source Fiji plugin called Crosshair. This workflow is demonstrated by targeting regions of interest in a series of samples.
Topics: Animals; Humans; Microscopy, Electron, Scanning; Microtomy; Software; Polychaeta; Fiji
PubMed: 36378502
DOI: 10.7554/eLife.80899 -
Genes May 2022Grouper aquaculture is rapidly expanding in both tropical and subtropical regions. The presence of marine leeches (; previously named ) infesting cultured groupers,...
Grouper aquaculture is rapidly expanding in both tropical and subtropical regions. The presence of marine leeches (; previously named ) infesting cultured groupers, however, can have a fatal effect on grouper aquaculture production and cause significant economic loss. Understanding the marine leech's population structure is therefore important to determine its possible distributional origin and distributional mechanisms, which will help monitor and mitigate the infestation. In this study, a total of 84 marine leeches collected from cultured hybrid groupers spp. in Brunei Darussalam, Malaysia and Indonesia were identified as , based on morphological and mitochondrial cytochrome c oxidase subunit I gene sequence analyses. These leech samples, together with additional sequences from the GenBank database, were grouped into four genetically distinct haplogroups: (1) Asia Pacific, (2) Borneo, (3) Surabaya and (4) Iran. The four populations were found to be highly diverged from each other. The results also suggested that the samples from the Asia Pacific population could be dispersed and transported from Indonesia.
Topics: Animals; Aquaculture; Asia; Genetics, Population; Leeches; Phylogeny
PubMed: 35741718
DOI: 10.3390/genes13060956 -
Indian Pediatrics Jun 2022
Topics: Animals; Foreign Bodies; Humans; Leeches; Trachea
PubMed: 35695149
DOI: No ID Found -
Ecotoxicology and Environmental Safety Jan 2022The increasing production and applications of graphene oxide (GO) inevitably lead to its entry into the environment. However, its potential toxicity to soil...
The increasing production and applications of graphene oxide (GO) inevitably lead to its entry into the environment. However, its potential toxicity to soil invertebrates is not yet completely known. Herein, the harmful effects of GO on the growth, survival, reproduction, and ultrastructure of earthworms were thoroughly evaluated through acute and chronic toxicity experiments. In the acute toxicity experiments, earthworms were exposed to different concentrations of GO using two test methods: filter paper contact test and natural soil contact test. The lethal concentrations (LC) for GO at 24-h and 48-h exposure were 2.52 and 2.36 mg mL, respectively, in the filter paper contact test and the LC on day 14 was 68.8 g kg in the natural soil test. Histopathological observation demonstrated that serious skin and intestinal damage occurred with increasing GO concentrations. In the chronic toxicity test, earthworm growth rate and reproduction were investigated after exposure to 0, 5, 10, 20 and 30 g kg GO in natural soil for 28 and 56 d. Earthworm growth was significantly inhibited after 7, 14, 21 and 28 d of GO exposure. The effect was more significant with increasing GO concentrations and exposure days. Moreover, GO exposure significantly decreased the reproductive capacity of earthworms. When earthworms were exposed to 20 g kg GO for 56 d, the number and hatching rate of cocoons and the number of juveniles decreased by approximately half compared with the control. These findings indicate the potential health risk of GO to E. fetida under high concentrations and long exposure times in soil. Thus, the potential risks associated with the application of GO should receive considerable attention. This study can provide valuable information for assessing the toxicity of carbon nanomaterials in terrestrial ecosystems.
Topics: Animals; Ecosystem; Graphite; Oligochaeta; Soil; Soil Pollutants
PubMed: 34915218
DOI: 10.1016/j.ecoenv.2021.113076 -
ELife Dec 2022Cells form networks in animal tissues through synaptic, chemical, and adhesive links. Invertebrate muscle cells often connect to other cells through desmosomes, adhesive...
Cells form networks in animal tissues through synaptic, chemical, and adhesive links. Invertebrate muscle cells often connect to other cells through desmosomes, adhesive junctions anchored by intermediate filaments. To study desmosomal networks, we skeletonised 853 muscle cells and their desmosomal partners in volume electron microscopy data covering an entire larva of the annelid . Muscle cells adhere to each other, to epithelial, glial, ciliated, and bristle-producing cells and to the basal lamina, forming a desmosomal connectome of over 2000 cells. The aciculae - chitin rods that form an endoskeleton in the segmental appendages - are highly connected hubs in this network. This agrees with the many degrees of freedom of their movement, as revealed by video microscopy. Mapping motoneuron synapses to the desmosomal connectome allowed us to infer the extent of tissue influenced by motoneurons. Our work shows how cellular-level maps of synaptic and adherent force networks can elucidate body mechanics.
Topics: Animals; Connectome; Larva; Annelida; Polychaeta; Muscles
PubMed: 36537659
DOI: 10.7554/eLife.71231 -
Combined toxic effects of dioxin-like PCB77 with Fe-based nanoparticles in earthworm Eisenia fetida.The Science of the Total Environment Apr 2021Iron-based nanomaterials hold promise for in situ remediation of persistent halogenated contaminants such as dioxin-like polychlorinated biphenyls, however, their...
Iron-based nanomaterials hold promise for in situ remediation of persistent halogenated contaminants such as dioxin-like polychlorinated biphenyls, however, their complex interactions and joint toxicity toward beneficial soil biological functions remain unknown. This study examined the effects of nano-zero valent iron (nZVI) on the physiological and morphological changes, on the bioaccumulation of co-existed dioxin-like 3,3',4,4'-tetrachloro-biphenyls (PCB77), and the joint toxicity of nZVI and PCB77 in earthworms Eisenia fetida. An orthogonally designed experiment was conducted through the exposure of E. fetida to the combined and separate nZVI and PCB77 at various concentrations in soil for 28 days (nZVI at the levels of g-Fe/kg-soil and PCB77 at the levels of mg-PCB/kg-soil). Results indicated that both nZVI and PCB77 inhibited the growth and reproduction of earthworms, and the combined exposure resulted in a synergistic effect. The addition of 10 g/kg nZVI decreased the contents of PCB77 and significantly increased the accumulation of PCB77 to a level ranging 14-97 mg/kg in earthworms in a nZVI dose dependent manner. The observed synergism might relate to the aggravated damage of earthworm epidermis in the presence of nZVI. PCB77 and nZVI at their corresponding high levels (10 mg/kg and 10 g/kg) induced oxidative stress and lipid peroxidation in the earthworms through the increased levels of reactive oxygen species and the subsequent inhibition of antioxidant enzymes including superoxide dismutase and catalase. Further metabolomics analyses revealed that the normal glutamic acid metabolism and tricarboxylic acid cycle were disturbed in earthworms exposed to the combined treatment of 10 mg/kg PCB77 and 10 g/kg nZVI. Our findings suggested that earthworms as a sentinel species could be readily employed in toxicity and tolerance studies to succeed the safe applications of nZVI and interestingly earthworms themselves also hold promise for vermiremediation owing to the high bioaccumulation potential of PCBs from contaminated soils.
Topics: Animals; Dioxins; Nanoparticles; Oligochaeta; Soil; Soil Pollutants
PubMed: 33418254
DOI: 10.1016/j.scitotenv.2020.144347 -
International Journal of Molecular... Mar 2020Echiura is one of the most intriguing major subgroups of phylum Annelida because, unlike most other annelids, echiuran adults lack metameric body segmentation. lives in...
Echiura is one of the most intriguing major subgroups of phylum Annelida because, unlike most other annelids, echiuran adults lack metameric body segmentation. lives in U-shape burrows of soft sediments. Little is known about the molecular mechanisms underlying the development of . Herein, we overviewed the developmental process from zygote to juvenile using immunohistochemistry and F-actin staining for the nervous and muscular systems, respectively. Through F-actin staining, we found that muscle fibers began to form in the trochophore phase and that muscles for feeding were produced first. Subsequently, in the segmentation larval stage, the transversal muscle was formed in the shape of a ring in an anterior-to-posterior direction with segment formation, as well as a ventromedian muscle for the formation of a ventral nerve cord. After that, many muscle fibers were produced along the entire body and formed the worm-shaped larva. Finally, we investigated the spatiotemporal expression of , , , and genes found in . During embryonic development, the striated and smooth muscle genes were co-expressed in the same region. However, the adult body wall muscles showed differential gene expression of each muscle layer. The results of this study will provide the basis for the understanding of muscle differentiation in Echiura.
Topics: Actins; Animals; Annelida; Muscle Development; Muscles; Nervous System; Transcriptome
PubMed: 32225111
DOI: 10.3390/ijms21072306 -
PloS One 2022Earthworm action and feeding have an important impact on a variety of microorganisms in the soil. However, the effects of the earthworm on Beauveria bassiana, a common...
Earthworm action and feeding have an important impact on a variety of microorganisms in the soil. However, the effects of the earthworm on Beauveria bassiana, a common entomopathogenic fungus in the biological control of pests, have been little studied. In this study, the epigeic earthworm species Eisenia fetida (Savigny) was selected to evaluate its impact on B. bassiana TST05 including its distribution in soil and its pathogenicity to target insects. By testing B. bassiana TST05 distribution, biomass in soil, viable spore germination rate, and pathogenicity to insect larvae after passing through the earthworm gut, the results showed that the activity and feeding of E. fetida promoted the B. bassiana TST05 diffusing downwards in the soil, while decreasing active fungal spores. After passing through the earthworm gut and excretion, the living B. bassiana individuals still had activity and pathogenicity to insects. The germination rate of the viable fungal spores was 15.09% and the infection rate to the insect larvae of Atrijuglans hetaohei Yang reached 62.35%, 80.95% and 100% after infection at 7 d, 10 d, and 14 d, respectively. The results showed that action and feeding of earthworms promoted the distribution of B. bassiana TST05 in soil, but decreased B. bassiana viable spores. This study is important for understanding the interaction between earthworms and B. bassiana in soil and for guiding the scientific application of B. bassiana in the biological control of pests.
Topics: Animals; Beauveria; Humans; Insecta; Oligochaeta; Pest Control, Biological; Soil; Spores, Fungal; Virulence
PubMed: 36227877
DOI: 10.1371/journal.pone.0275826