Rotifer Philodina Research Articles

湖沼の水圏生態系に及ぼす界面活性剤のマイクロコズムシステムを用いた影響評価

Microcosm system was applied to assess effect of surfactants on aquatic ecosystem. Surfactants such as LAS and Soap were added to an aquatic flask-size microcosm consisting of four species of bacteria as decomposer, one species of ciliate protozoa (Cyclidium glaucoma), two rotifers (Philodina sp. and Lepadella sp.) and one aquatic oligochaete (Aeolosoma hemprichi) as predator, and a green alga (Chlorella sp.) and a filamentous blue-green alga (Tolypothrix sp.) as producer. In the system, NOEC (no observed effect concentration) of LAS was below 1.5mg·l-1, whereas soap was below 30mg·l-1. Microcosm test is a pertinent tool to assess the effect of surfactant on ecosystem because microcosm test makes it possible to evaluate the effect of surfactant from a viewpoint of the interaction of microorganisms, material cycle and energy flow. With these respects, microcosm test is useful environmental assessment method which can reflect aquatic ecosystem.

The reproductive strategies of two Antarctic rotifers

The bdelloid rotifers Philodina gregaria Murray and Adineta grandis Murray were both cultured through three generations. The results suggested the following models for calculation purposes: (1) that individual Adineta grandis live for 40 days and, at death, give rise to five offspring; (2) that individual Philodina gregaria live for 89 days, producing 18 young at three‐day intervals, the first on day 36 and the last on day 87 (the animal dying two days later).Mathematical expressions for population growth were formulated, from these models, and used to interpret the field observations obtained from a shallow pool on Signy Island (60°43′ S, 45°38′ W) during the course of an Antarctic summer.Midway through the summer, two seals crawled through the pool and upset the continuity of the field study. This natural catastrophe not only provided an interesting insight into the recovery of such habitats but provided an opportunity to test further the hypotheses formulated in the culture experiments.

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

1. The presence of acetylcholine in the culture medium was found to result in egg retention in the bdelloid rotifer Philodina acuticornis in a dose-dependent fashion, with no other discernible physiological effect. When six to eight eggs accumulate, the animals distend, burst and die. No other cholinergic agonist has been shown to produce a similar effect. 2. The antagonistic effect of six anticholinergic drugs and five acetylcholinesterase-inhibitor insecticides was investigated on egg retention. All compounds were found to inhibit this phenomenon to varying degrees, but on the basis of their EC 50 neuromuscular blockers appear to be most active in inhibiting egg retention. 3. We suggest, therefore, that egg retention is caused by a spasm or increased tone of the cloacal sphincter rather than a paralysis of muscles needed in the peristaltic expulsion of the egg. 4. Five acetylcholine-esterase inhibitory insecticides also inhibit egg retention.

Fine structure of the female genital apparatus of Philodina (Rotifera, Bdelloidea)

The organization of the female genital apparatus of the bdelloid rotifer Philodina roseola was analyzed by light and electron microscopy. It differs from that of the monogononts in several respects: the gonad is paired; in each gonad, the follicular layer completely surrounds the syncytial vitellarium and the cluster of ovocytes; the cytoplasmic bridges between the vitellarium and the immature ovocytes exist but are much narrower; a specialized junction (5–8 nm intercellular space) is established between the follicular layer and the whole area of the germo-vitellarium complex. Preliminary observations about the movements of organelles during ovogenesis were made at an ultrastructural level.

α-Tocopherol increases lifespan in the rotifer Philodina

The addition of α-tocopherol (vitamin E) to the culture medium at a concentration of 10 −4 was found to significantly extend the average lifespan of the rotifer Philodina. The oily α-tocopherol was solubilized in Tween-80 so that it would dissolve in the aqueous culture medium. Tween-80 alone had no effect on the lifespan or fecundity of the rotifers. Addition of α-tocopherol also caused a significant increase in the number of offspring per rotifer.

Limnology of Bird Pond, Ross Island, Antarctica

Abstract The physical, chemical and biological properties of Bird Pond, Cape Bird, Ross Island, Antarctica (77° 13’ 10” S, 166° 28’ 30” E), were investigated at weekly intervals for 2 months in the summer of 1970–71. The above properties were also investigated over a 24‐h period. Salinity and temperature tolerance of the rotifer Philodina gregaria were investigated in the laboratory at Cape Bird. Bird Pond is characterised by a high conductivity and chloride ion concentration, and an alkaline pH. It has a water temperature as high as 15°c in mid summer, with the bottom water temperature often 3°c higher than the surface temperature. Diurnal measurements suggest a vertical movement of phytoplankton during a 24‐h period. P. gregaria survives ionic concentrations up to 250 000 g.m‐3 Na+ + Cl‐, and water temperatures up to 32°c.

EVALUATION OF PHILODINA ACUTICORNIS (ROTIFERA) AS A BIOASSAY ORGANISM FOR HEAVY METALS1

ABSTRACT: A technique for using the rotifer Philodina acuticornis as a bioassay organism is described. The rotifer was exposed to a range of concentrations for each of 14 toxicants. The effects of the heavy metals cadmium, chromium, cobalt, copper, lead, mercury, nickel, silver and zinc were studied. Based upon 96 hours exposure in soft water the sensitivity of the rotifer to the metals from the most toxic to least toxic was: cadmium, mercury and copper, zinc, silver, nickel (chloride), chromium, nickel (sulfate), lead and colbalt. In hard water with 96 hours exposure the most to least toxic respectively were: cadmium, copper, mercury, chromium and lead. The 48 hour EC50 value suggests that zinc will follow mercury in relative toxicity when Philodina is tested in hard water. In a comparison of the toxicity of the chloride and sulfate salts of cadmium, nickel and zinc in soft water cadmium sulfate and zinc sulfate were more toxic after 96 hours; nickelous chloride was more toxic than nickelous sulfate. Increased water hardness decreased the toxicity of the heavy metals studied. The results suggest that this rotifer may be more sensitive than the bluegill sunfish to the salts of cadmium, copper, nickel, zinc and chromium and less sensitive to lead. Data for cobalt, silver and mercury were not available. Philodina was extremely tolerant of ammonium chloride and phenol. The feasibility and economics of using an inexpensive, readily cultured and available organism such as Philodina acuticornis as a bioassay organism were discussed.

Age-related changes in ultrastructure and histochemistry of rotiferan organs

Age-related ultrastructural and histochemical changes of the vitellarium, stomach, and dorsal gastric gland were studied in the rotifer Philodina acuticornis odiosa Milne. Changes in all organs were quantitative, rather than qualitative, alterations of organelle populations. The appearance of age pigment or membranous elements and ultrastructural changes of mitochondria were not observed. The most significant changes were increases in the number of inclusion bodies and free ribosomes, of which the latter was not quantitated. Inclusion bodies increased approximately 30-fold in the gastric gland and vitellarium, and approximately 2-fold in the stomach. The histochemical studies showed an age-related increase in acid phosphatase activity in the three organs which was generally well correlated with the increase in inclusion bodies, while there was no age-related increase in lipid content. Results are discussed in relation to current investigations of aging.

The rotifer jaw: A scanning and transmission electron microscope study: I. The trophi of Philodina acuticornis odiosa

The trophi of the rotifer Philodina acuticornis odiosa have been studied by a variety of morphological techniques designed to elucidate the complex structure and function of this unusual hard tissue. The scanning electron microscope has been found to be valuable in supplementing observations on thin sections in addition to providing a unique three-dimensional impression of the entire trophi. In contrast to classical concepts, the jaws appear to be composed of intimately associated, essentially fused, components rather than distinct and separate parts which articulate together. Histochemical evidence suggests that the substance of the jaw is composed of acid mucopolysaccharide material and that a mineralized component, probably calcium, may reside in dense granules peripheral to the main body of the jaws.

Food supply as a factor in the survival of frozen and thawed rotifers

Summary The provision of an adequate food supply (bacteria) after freezing and thawing the rotifer Philodina is shown to increase the percentage survival. Furthermore, variations in the survival statistics as a function of cooling rate appear to be minimized by the addition of food after thawing. Both glyceerol and DMSO provide high levels of cryoprotection, DMSO being slightly more effective. Recovery of close to 100% of a population can be achieved with proper attention to pretreatment, cooling, and thawing procedures.

Studies on the survival of the rotifer philodina after freezing and thawing

Summary The survival of the rotifer Philodina after freezing and thawing has been examined under a variety of experimental conditions. Particular emphasis was placed on obtaining maximum survival by employing the most advantageous combination of protective additive concentration and cooling rate. Glycerol is an effective cryoprotective agent in this system at concentrations as low as 1% and exerts a maximum protective influence at a concentration of 2 to 3%. Glycerol solutions in the range of 5 to 10% result in somewhat anomalous survival curves as a function of cooling rate, although survival at these concentrations is moderately high at the extremes of the “slow cooling” range. Treatment of rotifers with a 20% glycerol solution results in death; thus, it is possible that sublethal toxic effects play a role at lower glycerol concentrations. Cooling rate optima appear in the region of 3 to 5°C per min with deviations occurring at high levels of glycerolation. Survivals of the order of 50 to 60% can be routinely achieved by employing the most suitable pretreatment and cooling rate. Animals frozen in this manner have been stored up to 20 days at liquid nitrogen temperatures without a noticeable decline in viability. In addition to manifesting normal swimming and feeding habits, survivors of freezing appear to enjoy a normal life span and reproductive capacity.

73. Studies on the survival of the rotifer Philodina after freezing and thawing : James K. Koehler (Department of biological structure, university of Washington, Seattle, Washington)

73. Studies on the survival of the rotifer Philodina after freezing and thawing : James K. Koehler (Department of biological structure, university of Washington, Seattle, Washington)

Fine structure of the cilia of rotifers.

The fine structure of the coronal cilia of the rotifer Philodina citrina has been studied in detail. Specimens were fixed with OsO(4) and embedded in butyl-methyl methacrylate, Epon 812, or Vestopal and sectioned with a Porter-Blum microtome. The details of structure of the rootlets, basal bodies, basal plates, and free cilia are described. The general structure of the rotifer ciliary apparatus conforms well to that established for other species. One of the main observations is the difference in structure of the peripheral filaments in the opposing halves of a cross-section of the free cilium. Also, in longitudinal sections evidence is offered for the existence of a helical structure in the peripheral filaments.

Absence of a Lansing effect in Drosophila subobscura.

LANSING1 has conducted experiments to show the effect of maternal age on the length of life of the parthenogenetic rotifer Philodina citrina. The median length of life of the ‘wild’ strain of this species was 21–24 days, and maximum length and the adult rate of egg production were reached on the sixth day of life. A strain was bred from this wild strain consisting of rotifers hatched in each generation from eggs laid on the fourth day of parental life. Other strains were established, with parental ages in each generation of eleven and of sixteen days. In the fourth-day strain, the mean expectation of life increased over several generations, and the age of attaining the adult rate of egg production was delayed. In the eleventh- and sixteenth-day strains, there was a rapid decrease in the mean expectation of life, the strains reaching extinction in five and three generations respectively. According to Lansing, longevity progressively declines in any strain which is maintained in each generation from eggs laid on or after the sixth day of life. Results similar to those given by Philodina were also obtained by Lansing with Euchlanis triquetra.

The effects of desiccation on the rotifer Philodina roseola

Journal of Experimental ZoologyVolume 6, Issue 2 p. 207-263 Article The effects of desiccation on the rotifer Philodina roseola Merkel Henry Jacobs, Merkel Henry JacobsSearch for more papers by this author Merkel Henry Jacobs, Merkel Henry JacobsSearch for more papers by this author First published: February 1909 https://doi.org/10.1002/jez.1400060203Citations: 26AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume6, Issue2February 1909Pages 207-263 RelatedInformation