Behavior of the lower organisms, by H. S. Jennings.

Jennings, H. S.

doi:10.5962/bhl.title.4123

Cited by 190 publications

(190 citation statements)

References 8 publications

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“…Gelei in 1935 also described the immobilizing action of Ni 2+ salts upon Paramecium caudatum. The avoiding reaction, which is also typical for ciliates and characterized by reversal of ciliary beat and swimming backwards, pivoting, circling and turning to the aboral side of the body and forward movement to the new direction, was clearly described by Jennings (1906). Kuźnicki revealed immobilization of Paramecium caudatum and defined this immobilization as short reversions at intervals of several seconds.…”

Section: Discussionmentioning

confidence: 99%

Acute Toxicity of Metals: Nickel and Zinc to Paramecium Bursaria and Its Endosymbionts

Zagata¹,

Kopańska²,

Greczek-Stachura³

et al. 2015

J microb biotech food sci

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Paramecium bursaria is an unicellular organism, widely distributed in the freshwater environment, where heavy metals are common contaminants. The ciliates, also including Paramecium bursaria, are a very abundant group in aquatic ecosystems, what makes them effective biological indicators of water pollutants. Paramecium bursaria is the only Paramecium which has evolved a mutualistic relationship with algae and it harbors these endosymbionts in its own cytoplasm. The algae are also very effective bioindicators of some pollutants because of their ability to biosorption and bioaccumulation of heavy metals. The aim of this study was to determine the acute toxicity of two metals’ compounds: nickel chloride (NiCl2) and zinc chloride (ZnCl2) to Paramecium bursaria and its endosymbionts. The ciliates were incubated in solutions with 5x10-8 to 5x10-2g/dm3 of NiCl2 and with 5x10-8 to 5x10-2g/dm3 of ZnCl2, at the temperature of 180C, in the light/dark conditions (12L/12D). Microscopic observations of cell divisions rate, cell shape changes as well as the swimming behavior, were conducted after 24, 48, 72 and 120 hours of incubation in the tested solutions and were compared to the control sample. Microscopic observations revealed the lethal doses for both compounds, for nickel chloride 5x10-5g/dm3 and for zinc chloride 5x10-3. These observations also revealed that in lesser concentrations than the lethal one, the slowdown and characteristic movements occur after metal addition. The PEA measurements of Fv/Fm parameter were carried out within 4 days, the first one after 24 hours of incubations. The results of this investigation has given us a view of a fluorescence efficiency by revealing that both compounds solutions can have the stimulating effect on Photosystem II, because the lowest fluorescence efficiency was measured in control samples.

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Section: Discussionmentioning

confidence: 99%

Acute Toxicity of Metals: Nickel and Zinc to Paramecium Bursaria and Its Endosymbionts

Zagata¹,

Kopańska²,

Greczek-Stachura³

et al. 2015

J microb biotech food sci

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“…The supernatant from the initial centrifugation was assayed for peroxidase (EC 1.11.1.7) similar to the procedure described by Jennings et al (17). The reaction mixture consisted of 1.5 ml of 0.05 M citrate-phosphate buffer (pH 6), 0.10 ml of 0.06 M H202, 0.1 ml of 0.01 M guaiacol, and 0.05 ml of enzyme.…”

Section: Materials and Methods2mentioning

confidence: 99%

Regulation of Lignin Formation in Reed Canarygrass in Relation to Disease Resistance

Vance

Sherwood

1976

Plant Physiol.

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(28,32) in our laboratory has implicated localized lignin formation in the leaf epidermal cell walls as a general mechanism of resistance of reed canarygrass (Phalaris arundinacea). When leaf discs were inoculated with fungi which infect other plants, but do not infect reed canarygrass, the outer epidermal walls beneath the sites of penetration became enlarged by localized appositional growth (32). The fungi did not penetrate the modified wall. Histochemical tests showed that the appositional growth and the nearby epidermal wall became lignified (28). Conversely, when inoculated leaf discs were incubated on cycloheximide solutions, instead of water, the appositional wall growth was inhibited (32), there was no evidence of localized lignification, and the fungi penetrated and colonized the epidermis (28, 32).Lignin, a major constituent of vascular tissue in woody and herbaceous plants (3,24, 34), provides an effective barrier to growth of many plant pathogenic fungi (19). Lignins are complex polymers composed primarily of phenylpropanoid units derived from phenylalanine and tyrosine via nonoxidative deamination to cinnamic acids (9,27 This paper deals with experiments involving lignin content and the activity of key enzymes in lignin biosynthesis in healthy and inoculated tissue. It also involves the effect of cycloheximide on lignin content and enzymes and discusses the results in relation to disease resistance. MATERIALS AND METHODS2Production of Inoculum. Conidia of Helminthosporium avenae Eidam were obtained from cultures maintained on V-8 juice agar for 7 to 14 days in continuous light at 25 C. Cultures were flooded with distilled H20 and spores were released by scraping the surface of the culture with a needle. The spore suspension was filtered through four layers of cheesecloth, and the concentration of spores was adjusted to 2.5 x 105 spores/ml after counting with a hemacytometer. The spore suspension was made to 0.1% v/v with Tween 20 surfactant.Preparation of Plant Tissue and Inoculation. Reed canarygrass clone 6049 (22) was used. Nine pieces of sod, 25 cm2, were transplanted from the field into a glasshouse bed of peatmossvermiculite. The plants were watered and fertilized frequently to maintain vigorous growth.Leaf discs (8-mm diameter) were cut with a cork borer from unblemished fully expanded leaves and floated on water or aqueous solutions of cycloheximide (25 ,ug/ml) in Petri dishes. The upper surface of discs was thoroughly sprayed with inoculum, or a 0.05-ml drop of inoculum was pipetted directly onto the discs. Dishes were kept on a laboratory table under prevailing light and temperature (20-24 C).Preparation of Ceil-free Extracts. Cell-free extracts of the leaf discs were obtained 18 hr after inoculation by grinding the discs in liquid N2 and extracting twice with 0.1 M-sodium phosphate buffer, pH 7.5 (2 ml/g of tissue). The resultant slurry was centrifuged at 15,000g for 20 min, and the pellet was discarded. The supernatant was treated with solid (NH4)2SO4 to 80% saturation. The precipitate ...

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“…Jennings (1907), in his elegant analysis of the behaviour of the starfish Asterias forreri, re-emphasized the part played by the central nervous system in the control of the movements of the podia. In furtherance of this view, Mangold (1908Mangold ( ,1921 was able, by cutting the nerve tracts in the neighbourhood of the tube feet so as to isolate them from the various parts of the central and peripheral nervous system in turn, to evaluate in a general way the functions of these various parts in the establishment and maintenance of co-ordination.…”

Section: Introductionmentioning

confidence: 99%