Rotifer Philodina Research Articles

Preliminary investigation of effects of copper on a terrestrial population of the antarctic rotifer Philodina sp.

Terrestrial microinvertebrates in Antarctica are potentially exposed to contaminants due to the concentration of human activity on ice-free areas of the continent. As such, knowledge of the response of Antarctic microinvertebrates to contaminants is important to determine the extent of anthropogenic impacts. Antarctic Philodina sp. were extracted from soils and mosses at Casey station, East Antarctica and exposed to aqueous Cu for 96 h. The Philodina sp. was sensitive to excess Cu, with concentrations of 36 μg L−1 Cu (48 h) and 24 μg L−1 Cu (96 h) inhibiting activity by 50%. This is the first study to be published describing the ecotoxicologically derived sensitivity of a rotifer from a terrestrial population to metals, and an Antarctic rotifer to contaminants. It is also the first study to utilise bdelloid rotifer cryptobiosis (chemobiosis) as a sublethal ecotoxicological endpoint. This preliminary investigation highlights the need for further research into the responses of terrestrial Antarctic microinvertebrates to contaminants.

Report of rotifer-ciliate-gastropod hyperepibiosis found on snail (Mollusca) from Goa, India

Here we report a rotifer-ciliate-gastropod hyperepibiosis in freshwater canal, Goa, India. A rotifer Philodina cf. megalotrocha Ehrenberg, 1832 was found attached on the colony of Epistylis plicatilis Ehrenberg, 1838 which was epibiont on gastropod Pomacea bridgesi (Reeve, 1856) . This is first report of a member of Epistylis as an epibiont on Pomacea bridgesi.

A rapid, simple screening toxicity test using desiccated bdelloid rotifers: Rotifer Activity Inhibition Test (RAIT).

A protocol for an ultra-rapid screening toxicity test is described using the rotifer Philodina acuticornis/roseola. The test can be executed in 30 min starting from the rehydration of desiccated life stages called tuns. Philodina tuns remain viable for years when maintained dry and at low temperature. They are very useful for conducting toxicity tests because the test animals do not require cultivation and are available to initiate tests anytime and anywhere. The swimming/crawling activity of rehydrated Philodina tuns is used as an endpoint to compare activity in control dilution water with inhibition of activity in an environmental sample. The Rotifer Activity Inhibition Test (RAIT) estimates toxicity semi-quantitatively using four toxicity categories: non-toxic, slightly toxic, very toxic, and 100% toxic. As proof of principle, RAIT has been tested on environmental samples from a variety of habitats and RAIT results have been compared with those obtained from traditional toxicity tests with bacteria, algae, Daphnia, and fish. Broad congruence between the effect signals of the rapid RAIT screening test and traditional assays has been found for river surface waters, industrial wastewaters, and sludge leachates from waste water treatment plants. Rotifers are an important group of animals in aquatic and soil food webs, and RAIT is a welcome new method for simple, ultra-rapid, and low-cost toxicity screening with a representative of this ecologically important group.

Radiolysis of carbamazepine by electron beam: Roles of transient reactive species and biotoxicity of final reaction solutions on rotifer Philodina sp.

Electron beam (EB) has proven to be an effective advanced oxidation reduction process (AORP) to degrade the psychiatric drug carbamazepine (CBZ); however, the degradation mechanism and the toxicity of the final reaction solutions to aquatic microorganisms needed further investigation. In this study, CBZ was eventually degraded and even mineralized by EB treatment, where the degradation of CBZ followed the pseudo-first-order kinetics with R2 > 0.98. Acidic conditions, presence of an additional oxidant (2.5 mmol L−1 H2O2), and O2/air-saturated conditions improved the degradation efficiency of CBZ, as well as the radiation chemical yield (G-value defined as the efficiency of the irradiation process). Concentrations of transient reactive species (TRS) caused by EB were quantified under different conditions at doses of 0.956 and 3.17 kGy, and the apparent quantum yield of CBZ degradation was in the order of OH > H > eaq−. However, the contribution of these species to CBZ degradation was in the order of OH > eaq− >H due to the generation of only a small amount of H. Findings regarding the changes of in CBZ degradation intermediates, short-chain fatty acids (SCFAs), and total organic carbon showed that CBZ can gradually be mineralized into CO2/CO32−, H2O, and NH3/NH4+ by the EB process. Additionally, an excellent rotifer survival rate after 5-day culturing in the reaction solutions resulting from 5-kGy treatment indicated that EB can be a safe AORP to mineralize CBZ in solution. These findings provide scientific proof for the EB being an effective AORP for removal of psychiatric drugs from aqueous solutions, laying the foundation for future remediation research.

Immediate and heritable costs of desiccation on the life history of the bdelloid rotifer Philodina roseola

The long-term persistence of the ‘ancient asexual’ bdelloid rotifers, a clade of small aquatic invertebrates, is often tied to their ability to enter anhydrobiosis. This ability has both clear benefits (e.g. survival of desiccating conditions), but offers considerable costs (e.g. subsequent repair of the genome as well as physiological and metabolic costs to re-establish the phenotype). Despite these costs, several studies show that the time spent dry is effectively ignored with respect to life expectancy (the Sleeping Beauty hypothesis) and that reconstruction of the genome after a desiccation event might even be necessary to repair mistakes accumulated in it from obligate parthenogenesis while the animals were active. We propose that this genomic repair might not derive exclusively because desiccation per se, but could also result from genetic exchange that appears to occur between individuals during this time. By comparing individuals of Philodina roseola Ehrenberg, 1832 desiccated in groups versus individually, we document costs to desiccation in the isolated treatment group that impact negatively on lifespan and reproduction. In addition, comparing both groups with continuously active individuals reveals no strong evidence for the Sleeping Beauty hypothesis in this species nor any decline in fitness over a six-month period for the latter group. Finally, many treatment effects are at least partly heritable and were found in the untreated F1 generations. In particular, individuals desiccated in groups and their offspring could both reproduce faster than the offspring of continuously active individuals. Thus, our results offer additional support for the hypothesis of genetic exchange occurring during desiccation events in P. roseola and highlight the importance of considering this factor, and desiccation in general, in explaining bdelloid fitness. Moreover, our results provide additional context for understanding how the genetic information of bdelloids is ultimately shaped.

Evidence Supporting the Uptake and Genomic Incorporation of Environmental DNA in the "Ancient Asexual" Bdelloid Rotifer Philodina roseola.

Increasing evidence suggests that bdelloid rotifers regularly undergo horizontal gene transfer, apparently as a surrogate mechanism of genetic exchange in the absence of true sexual reproduction, in part because of their ability to withstand desiccation. We provide empirical support for this latter hypothesis using the bdelloid Philodina roseola, which we demonstrate to readily internalize environmental DNA in contrast to a representative monogonont rotifer (Brachionus rubens), which, like other monogononts, is facultative sexual and cannot withstand desiccation. In addition, environmental DNA that was more similar to the host DNA was retained more often and for a longer period of time. Indirect evidence (increased variance in the reproductive output of the untreated F1 generation) suggests that environmental DNA can be incorporated into the genome during desiccation and is thus heritable. Our observed fitness effects agree with sexual theory and also occurred when the animals were desiccated in groups (thereby acting as DNA donors), but not individually, indicating the mechanism could occur in nature. Thus, although DNA uptake and its genomic incorporation appears proximally related to anhydrobiosis in bdelloids, it might also facilitate accidental genetic exchange with closely related taxa, thereby maintaining higher levels of genetic diversity than is otherwise expected for this group of “ancient asexuals”.

Development and validation of a chronic Pb bioavailability model for the freshwater rotifer Brachionus calyciflorus.

The univariate effects of Ca, pH, and dissolved organic carbon (DOC) on chronic (48-h) Pb toxicity to the freshwater rotifer Brachionus calyciflorus were investigated. High pH (8.2) and higher concentrations of DOC were protective against filtered Pb toxicity, whereas Ca was not. However, expressed as the free Pb2+ ion, Pb2+ toxicity increased with increasing DOC concentration, indicating that Pb-fulvic acid (FA) complexes may be bioavailable and may contribute to toxicity. Two different bioavailability models were developed. The pH effect was modeled as a single-site competition effect by H+ (log KHBL = 7.14). In the first model, only this H+ effect was considered; in a second model, a log-linear fulvic acid bioavailability effect (SFA = 0.602) was also incorporated. Both models predicted chronic Pb toxicity for most waters used for model development within a 2-fold error. To validate the predictive capacities of the models, chronic Pb toxicity to B. calyciflorus was tested in 5 natural waters and a reference water. Both models consistently underestimated Pb toxicity in the natural waters, as a result of a shift in rotifer sensitivity to Pb between the development and the validation test series. However, optimizing the intrinsic sensitivity in the models specific for the validation test series resulted in reasonable predictions of Pb toxicity in the natural waters. The second, more complex model predicted chronic Pb toxicity most accurately. The protective effects of water chemistry on Pb toxicity to Brachionus are comparable to those observed for Ceriodaphnia. However, the developed Brachionus models were not able to accurately predict chronic Pb toxicity to the rotifer Philodina rapida. It remains unclear why the influence of water chemistry on chronic Pb toxicity appears to be different between 2 rotifer species. Environ Toxicol Chem 2016;35:2977-2986. © 2016 SETAC.

Life cycle traits of Philodina roseola Ehrenberg, 1830 (Rotifera, Bdelloidea), a model organism for bioassays.

This paper describes experimental results on the life cycle of the rotifer Philodina roseola cultured in the laboratory. Detailed information on life-cycle parameters of a certain species provides a deep understanding and contributes to a better knowledge of the role of the species in the community, besides providing data that are basic to other ecological investigations such as secondary production estimates and knowledge for applications such as its utilization as test-organism in ecotoxicological studies. The average duration of embryonic development of P. roseola was 23.88 h, the age at maturity of primipara was 3.5 days and the maximum lifespan was 23 days. The average size of the rotifer neonate was 198.77 µm, the mean size of primipara was 395.56 µm and for adults 429.96 µm. The average fecundity was 1.22 eggs per female per day and the mean number of eggs produced per female during the entire life was 22.33. The deceleration of somatic growth from the start of the reproductive stage represents a trade-off between growth and reproduction that is often seen in micrometazoans. The life history of P. roseola follows the strategy of other bdelloid species characterized by a rapid pre-reproductive development and canalization of most assimilated energy to reproduction after reaching maturity. The differences observed in total fecundity and longevity between our P. roseola cultures and those from previous studies were probably due to differences of intrinsic adaptation of this species ecotypes to the conditions of their natural environments.

Mutualistic association of rotifer Philodina roseola with the branchiuran fish ectoparasite Argulus bengalensis at its embryonic stage.

Several rotifers including Philodina spp. are well known to make commensal and parasitic associations with different animals. The present investigation was carried out to decipher the relationship of Philodina roseola with a piscine ectoparasite Argulus bengalensis in its embryonic stage. Mechanical removal of the symbiont P. roseola from the argulid egg strips resulted in the complete (100%) failure in hatching. Several P. roseola individuals were found to feed on the solidified jelly coat of the eggs enabling the larvae to emerge under both laboratory and field conditions. Under the laboratory condition, the experimental removal of P. roseola did not affect the embryonic development, but it rendered the jelly coat intact; therefore, the larvae were unable to make hatching furrow and subsequently died. The results of our experiments thus prove this service-resource relationship to be a mutualism. Although the association is facultative for P. roseola, it is obligatory for Argulus spp. An act of intervention in this relationship thus offers a promising control of argulosis.

The toxicity of carbofuran to the freshwater rotifer, Philodina roseola.

In this study, the effects of exposing the rotifer Philodina roseola to the pesticide carbofuran were investigated. Its range of sensitivity to potassium dichromate, the acute toxicity of active ingredient carbofuran and of carbofuran dosed as its commercial form, Furadan(®) 350 SC were determined. Chronic toxicity of carbofuran dosed as Furadan(®) 350 SC on P. roseola survival and fecundity were also studied. The sensitivity of P. roseola to K2Cr2O7 ranged from 29.52 to 64.67mgL(-1), averaging 47.10mgL(-1). The 48-h EC50 were 13.36±2.63mgL(-1) for carbofuran and 89.32±6.52mgL(-1) for commercial form. Chronic toxicity tests showed that the survival of this rotifer was not affected by the carbofuran dosed as Furadan(®) 350 SC at the concentrations tested and that at 1.56 and 3.12mgL(-1) their fecundity was higher than in the absence of this commercial product, characterizing the hormesis phenomenon. The sensitivity profile of several species to carbofuran indicated that P. roseola is more susceptible to this pesticide than the fish Clarias batrachus, the bacterium Vibrio fischeri, the protozoan Paramecium caudatum and the rotifer Brachionus calyciflorus, although the acute toxicity of carbofuran dosed as Furadan(®) 350 SC to P. roseola is much lower than that of active ingredient carbofuran. The results also imply that the exacerbated use of pesticides and the constant, accelerated expansion of agricultural activity will make aquatic non-target species even more vulnerable. Furthermore, the relevant role of benthic organisms in aquatic environments justifies the inclusion of P. roseola and other benthic species in toxicity screening for risk assessment, regarding this environmental compartment.

Multi-linear regression analysis, preliminary biotic ligand modeling, and cross species comparison of the effects of water chemistry on chronic lead toxicity in invertebrates

The current study examined the chronic toxicity of lead (Pb) to three invertebrate species: the cladoceran Ceriodaphnia dubia, the snail Lymnaea stagnalis and the rotifer Philodina rapida. The test media consisted of natural waters from across North America, varying in pertinent water chemistry parameters including dissolved organic carbon (DOC), calcium, pH and total CO2. Chronic toxicity was assessed using reproductive endpoints for C. dubia and P. rapida while growth was assessed for L. stagnalis, with chronic toxicity varying markedly according to water chemistry. A multi-linear regression (MLR) approach was used to identify the relative importance of individual water chemistry components in predicting chronic Pb toxicity for each species. DOC was an integral component of MLR models for C. dubia and L. stagnalis, but surprisingly had no predictive impact on chronic Pb toxicity for P. rapida. Furthermore, sodium and total CO2 were also identified as important factors affecting C. dubia toxicity; no other factors were predictive for L. stagnalis. The Pb toxicity of P. rapida was predicted by calcium and pH. The predictive power of the C. dubia and L. stagnalis MLR models was generally similar to that of the current C. dubia BLM, with R2 values of 0.55 and 0.82 for the respective MLR models, compared to 0.45 and 0.79 for the respective BLMs. In contrast the BLM poorly predicted P. rapida toxicity (R2=0.19), as compared to the MLR (R2=0.92). The cross species variability in the effects of water chemistry, especially with respect to rotifers, suggests that cross species modeling of invertebrate chronic Pb toxicity using a C. dubia model may not always be appropriate.

Effect of increasing salinity on the acute toxicity of a commercial endosulfan formulation to the bdelloid rotifer Philodina acuticornis odiosa

Pesticides, such as endosulfan, can enter surface waters such as lakes and rivers, potentially posing an ecological risk. Rotifers are a dominant zooplankton species in many inland freshwater lakes in Australia; such lakes can also experience increased salinities. Acute toxicity tests (24 h) were conducted to determine the toxicity of a commercial formaulation of endosulfan to the freshwater rotifer Philodina sp. and to investigate the influence of increasing salinity on endosulfan toxicity. Rotifers were found to be relatively tolerant to endosulfan with an EC50 of 1.75 mg L−1 (a.i.), with results also suggesting that there are no interactive effects of salinity on endosulfan toxicity.

Utilization of a new bdelloid rotifer (Philodina acuticornis odiosa) assay to evaluate the effect of salinity on the toxicity of chlorothalonil

Acute (24 h) toxicity tests were conducted to determine the toxicity of the fungicide chlorothalonil towards the freshwater bdelloid rotifer (Philodina acuticornis odiosa). Since rotifers are the dominant zooplankton species in many inland freshwater lakes in Australia, the influence of salinity on chlorothalonil toxicty was also assessed. The rotifers used in this study appeared to be reasonably tolerant to changes in salinity, with little mortality observed at 3760 µS cm−1, increasing thereafter at higher salinity. The bdelloid rotifers were, however, found to be highly sensitive to chlorothalonil (24 h LC50, 3.2 µg L−1) with results also suggesting that as salinity increases, so does toxicity (e.g., 24 h LC50 at 5000 µS cm−1, 0.5 µg L−1).

Dynamics of sustainable grazing fauna and effect on performance of gas biofilter

The inherent operational problems of biofilters such as a pressure drop increase and nutrient limitations were managed in a toluene-removing gas biofilter with a sustainable grazing fauna consisting of micrometazoa and ciliate protozoa. Dynamic populations of predatory nematodes (Caenorhabditis sp.), rotifers (Philodina sp.), tardigrades (Echiniscus sp.) and fly larvae represented the micrometazoa community in the filter bed. Colpoda inflata, Euplotes harpa and Acineria sp. constituted the grazing ciliate community. The spatiotemporal distribution and abundance of the grazing fauna depends on physicochemical conditions and interspecies interactions in the biofilter. Of the micro metazoa, Caenorhabditis and Philodina tolerated wide concentration ranges for toluene (0.75-2.63 g m(-3)) and CO(2) (0.92-6.08 g m(-3)) and maintained stable populations of 3.4-4.7 x 10(3) and 5.8-7.65 x 10(4) g medium(-1), respectively. The grazing fauna supported a stable toluene-degrading bacterial community composed of four Pseudomonas spp. Under a maximum toluene load of 120.72 g m(-3) h(-1), at steady-state conditions 80% toluene removal was achieved in the biofilter. Of the grazing organisms, owing to their reproductive cycle and feeding behaviour, fly larvae were not suited for application in the biofilter. Meanwhile, organisms such as nematodes, rotifers and ciliates capable of tolerating a wide pollutant concentration range and maintaining a sustainable population are ideal candidates for application in biofilter technology.

Toxicity of the quinalphos metabolite 2‐hydroxyquinoxaline: Growth inhibition, induction of oxidative stress, and genotoxicity in test organisms

The quinalphos metabolite 2-hydroxyquinoxaline (HQO), previously shown to photocatalytically destroy antioxidant vitamins and biogenic amines in vitro, was tested for toxicity in several small aquatic organisms and for mutagenicity in Salmonella typhimurium. In the rotifer Philodina acuticornis, HQO caused the disappearance of large individuals and increased hydroperoxide concentration. The latter effect was not only observed in animals kept in a light/dark cycle, but also in constant darkness, indicating that HQO can assume a reactive state and/or form reactive intermediates under the influence of either light or redox-active metabolites, in particular, free radicals. Cell proliferation was inhibited in the ciliate Paramecium bursaria. In the dinoflagellate Lingulodinium polyedrum, which allows early detection of cellular stress on the basis of bioluminescence measurements, strong rises in light emission became apparent on the 2nd day of exposure to HQO and continued until cells died between 12 and 18 days of treatment. Oxidative damage of protein by HQO was demonstrated by measuring protein carbonyl in L. polyedrumin vivo as well as in light-exposed bovine serum albumin in vitro. In an Ames test of mutagenicity, HQO proved to be genotoxic in both light- and dark-exposed bacteria. HQO appears as a source of secondary quinalphos toxicity, which deserves further attention.

Mitochondrial medicine: neuroprotection and life extension by the new amphiphilic nitrone LPBNAH1 acting as a highly potent antioxidant agent

The search for effective treatments that prevent oxidative stress associated with premature ageing and neurodegenerative diseases is an important area of neurochemical research. As age- and disease-related oxidative stress is frequently associated with mitochondrial dysfunction, amphiphilic antioxidant agents of high stability and selectivity that target these organelles can provide on-site protection. Such an amphiphilic nitrone protected human neuroblastoma cells at low micromolar concentrations against oxidative damage and death induced by exposure to the beta-amyloid peptide, hydrogen peroxide and 3-hydroxykynurenine. Daily administration of the antioxidant at a concentration of only 5 mum significantly increased the lifespan of the individually cultured rotifer Philodina acuticornis odiosa Milne. This compound is unique in its exceptional anti-ageing efficacy, being one order of magnitude more potent than any other compound previously tested on rotifers. The nitrone protected these aquatic animals against the lethal toxicity of hydrogen peroxide and doxorubicin and greatly enhanced their survival when co-administered with these oxidotoxins. These findings indicate that amphiphilic antioxidants have a great potential as neuroprotective agents in preventing the death of cells and organisms exposed to enhanced oxidative stress and damage.

Comparative study of the planktonic communities of three lakes of contrasting trophic status at Hope Bay (Antarctic Peninsula)

Three water bodies of contrasting trophic status located at Hope Bay (Antarctic Peninsula) were studied during the summer of 1999, analysing all of their planktonic communities (zooplankton, phytoplankton and bacterioplankton) and their main limnological features. Important differences associated with their trophic conditions were found among lakes. At one extreme of the gradient, in the most oligotrophic lake (Lake Chico), the nektobenthic copepod Boeckella poppei and the rotifer Philodina gregaria were dominant in the open waters, and copepods presented a single reproductive event (univoltine life cycle); phytoplankton exhibited the lowest densities, dominated by nanoplanktonic Chrysophyceae and picocyanobacteria. In the meso-eutrophic Lake Boeckella, B. poppei, the dominant zooplankter, exhibited a multivoltine life cycle; phytoplankton were mainly represented by nanoplanktonic species of Volvocales, alternating with flagellate Chrysophyceae, and a great abundance of picocyanobacteria. In the hypertrophic Pingüi Pond, zooplankters were exclusively represented by bdelloid rotifers and ciliates; phytoplankton samples included some strictly planktonic species (Volvocales), a great proportion of picocyanobacteria and many typically benthic species (oscillatorians and diatoms) due to the shallowness of the water body. Bacterioplankton densities did not show important differences among lakes, but fluctuations, probably associated with a top-down control, were observed in the hypertrophic pond. This paper constitutes the first survey concerning all the planktonic compartments of water bodies of different trophic status at Hope Bay, describing the relative contributions of autotrophic and heterotrophic components to their food webs.

Non-vertebrate melatonin.

Melatonin has been detected in bacteria, eukaryotic unicells, macroalgae, plants, fungi and various taxa of invertebrates. Although precise determinations are missing in many of these organisms and the roles of melatonin are still unknown, investigations in some species allow more detailed conclusions. Non-vertebrate melatonin is not necessarily circadian, and if so, not always peaking at night, although nocturnal maxima are frequently found. In the cases under study, the major biosynthetic pathway is identical with that of vertebrates. Mimicking of photoperiodic responses and concentration changes upon temperature decreases have been studied in more detail only in dinoflagellates. In plants, an involvement in photoperiodism seems conceivable but requires further support. No stimulation of flowering has been demonstrated to date. A participation in antioxidative protection might be possible in many aerobic non-vertebrates, although evidence for a contribution at physiological levels is mostly missing. Protection from stress by oxidotoxins or/and extensions of lifespan have been shown in very different organisms, such as the dinoflagellate Lingulodinium, the ciliate Paramecium, the rotifer Philodina and Drosophila. Melatonin can be taken up from the food, findings with possible implications in ecophysiology as well as for human nutrition and, with regard to high levels in medicinal plants, also in pharmacology.

微生物活性助剤を添加した生物処理反応槽に出現する微小動物相の特徴

Acomparative study of construction and function of microfauna (protozoa and metazoa) communities in biological domestic wastewater treatment reactors with and without a microorganism activator (Saponin) was carried out. It was showed that the addition of Saponin did not change the construction of microfauna communities, but promoted the growth of microfauna, especially attached rotifer that was famous as useful metazoa in biological treatments. The variation of species of metazoa was smaller than that of protozoa. When water temperatures dropped in the range of 10-13°C, the growth of protozoa highly decreased, but the growth of metazoa increased, showed that metazoa was highly tolerant to low temperatures than protozoa. The biomass of a special group of microfauna with the habits of attached living and SS feeding in the reactor with Saponin was the highest in microfauna communities and remarkably higher than that in the reactor without Saponin. Moreover, rotifer Philodina sp. was the most prosperous in all species of that special group. Statistical analysis showed the close connection between biomass of attached microfauna with the habit of suspended particle feeding and effluent SS concentrations, indicating these microfauna played an important and useful role in the removal of suspended solids.

Variable Outcomes of Protist-Rotifer Competition in Laboratory Microcosms

A laboratory experiment examined competition for bacterial food between a protist and a rotifer. The experiment utilized a randomized 2 x 2 factorial design (+/0 rotifer sp., +/0 protist sp.). When grown monospecifically, the rotifer Philodina sp. and the protist Paramecium multimicronucleatum were similar in terms of mean efficiency of bacterial grazing in batch culture. When cultured together, the identity of the dominant species varied: Philodina dominated 3 of 5 replicates, while Paramecium dominated the remaining 2 replicates. The variable competitive outcome is predicted by variation in mean grazing efficiency when each species is raised alone.