Topic
Glochidium
About: Glochidium is a research topic. Over the lifetime, 64 publications have been published within this topic receiving 1065 citations.
Papers published on a yearly basis
Papers
TL;DR: The sensitivity of glochidial stages of unionid mussels was evaluated in a series of exposures to aqueous copper as mentioned in this paper, showing that released glochidia of all species were sensitive to copper at comparatively low concentrations.
Abstract: The sensitivity of glochidial stages of unionid mussels was evaluated in a series of exposures to aqueous copper. Glochidia held within marsupia of gravid Villosa iris exhibited no observable effect following a 30-d copper exposure at levels up to 19.1 {micro}g Cu/L. Similarly, transformation of encapsulated glochidia of Actinonaias pectoroso, Pyganodon grandis (Say, 1829), and V. iris to the juvenile stage was unaffected by 12- to 20-d copper exposures of largemouth bass, Micropterus salmoides (Lacepede), at levels up to 200 {micro}g Cu/L. In contrast, released glochidia of all species were sensitive to copper at comparatively low concentrations. The median lethal concentrations (24-h) for Lampsilis fasciola (Rafinesque, 1820) ranged from 26 to 48 {micro}g Cu/L, from 36 to 89 {micro}g Cu/L for V. iris, from 37 to 81 {micro}g Cu/L for Medionidus conradicus, from 42 to 132 {micro}g Cu/L for A. pectorosa, and from 46 to 347 {micro}g Cu/L for P. grandis. Copper sensitivity varied with changes in test conditions, including length of exposure, water temperature, and water hardness. Although sensitivity of released glochidia to copper was comparable to previously reported values for juvenile mussels, the juveniles may be at greater risk given their residency in benthic sediments where toxicants suchmore » as metals may be sequestered at high levels. An evaluation of this risk is an urgent priority for further research.« less
87 citations
TL;DR: Encystment is not the result of cell proliferation, but is accomplished by a mass movement of cells from the adjoining regions, advancing by their own activities and directed over the exposed valves by thigmotaxis.
Abstract: Mechanical stimulation of the larval glochidium induces non-selective, automatic closure upon the impinging gill or fin. The valves largely cleave the soft tissues encountered, but merely clasp such tough elements as blood vessels and fin rays which lie deeper. As a result, part of the glochidium is buried in host substance.The glochidium is then covered by host tissue which advances from all sides, primarily for the purpose of closing the wound. Encystment is not the result of cell proliferation. On the contrary, it is accomplished by a mass movement of cells from the adjoining regions, advancing by their own activities and directed over the exposed valves by thigmotaxis. A compensatory period of mitosis may appear subsequent to encystment, apparently to replace cells lost to the cyst by emigration.Fin cysts are largely epithelial in structure. Glochidia which attach to gill filaments lie embedded in cellular connective tissue, roofed over with an epithelial canopy.Shortly after encystment is completed t...
67 citations
TL;DR: The development of the parasitic glochidium larva of Anodonta cygnea L. is outlined, with reference to earlier studies on unionid larvae, and a comparison is made between the mature glochidia of the three genera, Andonta, Unio, and Margaritifera.
Abstract: The development of the parasitic glochidium larva of Anodonta cygnea L. is outlined, with reference to earlier studies on unionid larvae, and a comparison is made between the mature glochidia of the three genera, Anodonta, Unio, and Margaritifera.
The glochidium of Anodonta cygnea is anatomically and morphologically specialized in connection with its parasitic existence. The specialized structures are described, and their significance discussed.
59 citations
TL;DR: The hypotheses of other authors that acetylcholinesterase (AChE) is involved in the control of many essential functions, such as frontal ciliaryActivity of gill epithelium, temperature resistance, ciliary activity for transport of suspended particulate, valve opening and embryo development, suggest that the high catalytic efficiency of the invasive species may endow it with a competitive advantage over the endemic species.
Abstract: To address the potential role of cholinesterase enzymes in the invasive capacity of species, the present study investigated ChE activity in the invasive freshwater bivalve Anodonta woodiana (Lea, 1834) comparing it with that of the indigenous species, Anodonta sp. (Linnaeus, 1758). The invasive capacity of pests has often been linked to their ecological plasticity and high intrinsic genetic variability; however the role played by molecular and cellular mechanisms, generally known as an organism's response to pollution, is unclear. Different substrates and selective ChE enzyme inhibitors were investigated in digestive gland, foot, gonad, adductor muscle and gill tissues while sensitivity to four organophosphate (OP) insecticides was investigated in vitro only in adductor muscle. The invasive species (A. woodiana) showed significantly greater (at least one order of magnitude) ChE activity than the endemic species (Anodonta sp.) (p<0.05) using acetylthiocholine (ASCh) as substrate and the activity was more widely distributed in tissues involved in movement (adductor muscle and foot), respiration, feeding (gills) and reproduction (gonads). Moreover, only the invasive species, A. woodiana, showed detectable ChE (vs. ASCh) activity in gill tissue. No substrate specificity was observed in any tissue of either species as already described for other bivalve species. ChE activity was not inhibited by Iso-OMPA but showed high sensitivity to BW248c51 and eserine. Both species showed moderate to low sensitivities in vitro to OP insecticides in the range 10(-7)-10(-2) M. Calculated IC(50) for fenitrothion and chlorpyrifos was in the range 10(-6)-10(-3) M in muscle of A. woodiana while a higher inhibition was observed for fenitrothion (10(-7) M) and lower for chlorpyrifos (10(-2) M) in the indigenous species Anodonta sp. Similar IC(50) of 10(-5)-10(-6) M were observed for DFP and azamethiphos in both species. The hypotheses of other authors that acetylcholinesterase (AChE) is involved in the control of many essential functions, such as frontal ciliary activity of gill epithelium, temperature resistance, ciliary activity for transport of suspended particulate, valve opening and embryo development, suggest that the high catalytic efficiency of the invasive species may endow it with a competitive advantage over the endemic species. In view of the peculiar reproductive strategy of these mussels, higher ChE vs. ASCh activity in gonads of the invasive species could also favour glochidium production and embryo development under a wider range of environmental conditions.
55 citations
TL;DR: It is described how the alleged intrageneric glochidial variation in Pseudodon, and in the other genera of the Gonideinae reported to have asymmetrical glochidia, challenge the resolved convergence of asymmetricalglochidia.
54 citations
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Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2019 | 2 |
| 2018 | 1 |
| 2017 | 2 |
| 2015 | 3 |
| 2014 | 3 |