A comprehensive survey of the literature on the use of rotifers as bio-indicators water quality has been made in this article. Brachionus angularis, Trichocerca cylindrica, Polyurthra euryptera, Pompholyx sulcata, Rotaria rotatoria, Filinia longiseta have been designated as indicators of heavy pollution (Eutrophy). Ascomorpha ovalis, Asplanchna herricki, Synchaeta grandis, Ploesoma hudsoni, Anuraeopsis fissa, Monostyla bulla and M. hamata are indicators of fresh and clean waters (Oligotrophy) while a variety of rotifers including Brachionus, Keratella spec, are inhabitants of moderately clean (mesotrophy) waters. However, more and more knowledge regarding morphological variations and physiological conditions of rotifers should be studied and then they can be used as better indicators of environmental quality.

Rotifers as Indicators of Water Quality

1. A zebrafish M2 muscarinic acetylcholine receptor (mAChR) gene was cloned. It encodes 495 amino acids in a single exon. The derived amino acid sequence is 73.5% identical to its human homologue. 2. Competitive binding studies of the zebrafish M2 receptor and [(3)H]-NMS gave negative log dissociation constants (pK(i)) for each antagonist as follows: atropine (9.16)>himbacine (8.05)>/=4-DAMP (7.83)>AF-DX 116 (7.26)>/=pirenzepine (7.18)>/=tropicamide (6.97)>/=methoctramine (6.82)>/=p-F-HHSiD (6.67)>carbachol (5.20). The antagonist affinity profile correlated with the profile of the human M2 receptor, except for pirenzepine. 3. Reverse transcription polymerase chain reaction and Southern blotting analysis demonstrated that the M2 mAChR mRNA levels increased during the segmentation period (12 h post-fertilization; h.p.f.) in zebrafish. By whole-mount in situ hybridization, the M2 mAChR was first detectable in the heart, vagus motor ganglion, and vagus sensory ganglion at 30, 48 and 60 h.p.f., respectively. 4. The muscarinic receptor that mediates carbachol (CCh)-induced bradycardia was functionally mature at 72 h.p.f. The effect of CCh-induced bradycardia was antagonized by several muscarinic receptor antagonists with the order of potency (pIC(50) values): atropine (6.76)>methoctramine (6.47)>himbacine (6.10)>4-DAMP (5.72)>AF-DX 116 (4.77), however, not by pirenzepine, p-F-HHSiD, or tropicamide (<10 micro M). 5. The effect of CCh-induced bradycardia was abolished completely before 56 h.p.f. by M2 RNA interference, and the bradycardia effect gradually recovered after 72 h.p.f. The basal heart rate was increased in embryos injected with M2 mAChR morpholino antisense oligonucleotide (M2 MO) and the effect of CCh-induced bradycardia was abolished by M2 MO in a dose-dependent manner. In conclusion, the results suggest that the M2 mAChR inhibit basal heart rate in zebrafish embryo and the M2 mAChR mediates the CCh-induced bradycardia.

https://bpspubs.onlinelibrary.wiley.com/doi/pdf/10.1038/sj.bjp.0704930

Zebrafish M2 muscarinic acetylcholine receptor: cloning, pharmacological characterization, expression patterns and roles in embryonic bradycardia.

The swimming behaviour of Brachionus calyciflorus (rotifer) under toxic stress. II. Comparative sensitivity of various behavioural criteria

Cholinergic modulation of spontaneous activity in rat dorsal cochlear nucleus

The phylum Rotifera or Rotatoria comprises of approximately 2000 species of unsegmented, bilaterally symmetrical, pseudocoelomates, possessing two distinctive features. First, at the apical end (head), there is a ciliated region called the corona, which is used in locomotion and food gathering. In adults of some forms, ciliation is lacking and the corona is a funnel or bowl shaped structure, at the bottom of which is the mouth. Second, a muscular pharynx, the mastax, possessing a complex set of hard jaws called trophi, is present in all rotifers. Although rotifers are often confused with ciliated protozoans and gastrotrichs by beginning students, those organisms do not possess trophi and their ciliation is not distributed in the same way as in rotifers. Collectively, this phylum is widely distributed; it is found in all freshwater habitats at densities generally ranging up to about 1,000 individuals/L. However, rotifers occasionally become abundant if sufficient food is available. In general, rotifers are not as diverse or as abundant in marine environments as micro crustaceans, but they occur in many near shore marine communities and occasionally comprise the dominant portion of the biomass.

8 – phylum rotifera

Rotifer neuropharmacology--II. Synergistic effect of acetylcholine on local anesthetic activity in Brachionus calyciflorus (Rotifera, Aschelminthes).

The quantitative composition of the rotifer fauna of seven interconnected lakes located in southern California was studied in a preliminary investigation. The lakes are fed by reclaimed sewage, and the water quality increases rapidly from the first lake, barely able to support life, to a series of lovely lakes stocked with fish and utilized for recreation. The Shannon index of rotifer population diversity showed an appropriate increase. Up to 24 – 28 different rotifer taxa in each lake provided a rich community dominated by Brachionids, Keratella and Trichocerca. The diversity and quantity of the rotifer association then declined again in the last lake. Comparison of the lakes using the Bray and Curtis index of similarity and cluster analysis supported the picture of a lake-chain evolution, a biotic development showing a maximum curve.

Correlation of rotifer associations in a chain of lakes fed by reclaimed sewage

Rotifer neuropharmacology--I. Cholinergic drug effects on oviposition of Philodina acuticornis (Rotifera, Aschelminthes).

Nine lakes in Mont Tremblant Provincial Park were investigated during summer and fall. Data on lake morphometry and water chemistry are tabulated. Most lakes were oligotrophic, some were dystrophic bog lakes. They contain a rich rotifer fauna and some very rare species, which are described in detail.

Canadian rotifers ii. parc mont tremblant, quebec

Two new rotifer species, Lecane (Monostyla) aliger n.sp. and Proales pugio n.sp. are described from the Bahama Islands, Florida and California, and their autecology outlined. Some other rare rotifers are discussed which also prefer subtropical conditions. They are: Epiphanes clavulata, Epiphanes brachionus spinosus, Lecane crepida and Proalides tentaculatus tentaculatus. The existence of subtropical rotifer associations is discussed and supported by ecological data.

Thomas Nogrady

Papers

Rotifer neuropharmacology--II. Synergistic effect of acetylcholine on local anesthetic activity in Brachionus calyciflorus (Rotifera, Aschelminthes).

Correlation of rotifer associations in a chain of lakes fed by reclaimed sewage

Rotifer neuropharmacology--I. Cholinergic drug effects on oviposition of Philodina acuticornis (Rotifera, Aschelminthes).

Canadian rotifers ii. parc mont tremblant, quebec

Some new and rare warmwater rotifers