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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Respiration of Tetrahymena pyriformis W, grown in Proteose peptone-glucose medium, was determined by Warburg's direct and indirect methods. The Qo2 varied inversely with cell concentration under exogenous conditions (cells in conditioned medium, i.e., one which had supported growth) as determined by both methods, and under endogenous conditions (washed cells suspended in salts solution) when determined by the indirect method. Endogenous respiration, measured by the direct method, was low but independent of cell concentration.Respiration, determined by the direct method, was little affected by lowered O2 availability, but varied directly with nutrient availability. The inhibitor, malonate, which also stimulates respiration at greater dilutions, inhibited respiration at 10−2M when present with low cell concentrations, but stimulated at high cell concentrations.The reduced respiration at higher cell concentrations is thought less due to lack of O2 than to CO2 accumulation and competition for nutrients. Consideration of these variables is essential in comparing data from the literature.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. The effect of 10 detergents on the inhibitory activity of neomycin was tested against Ochromonas danica. All 4 anionic detergents used were synergistic with neomycin. Evidence is presented that the synergisms were due to the effect of the detergents on the cell membrane. In the presence of Tergitol 7, O. danica is more susceptible to changes in osmotic pressure by increasing concentrations of KCl.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Speculations regarding the mode of transmission of monocystid parasites of earthworms over a period of more than 100 years have never been tested experimentally under controlled conditions. In order to do so a stock of infectionfree Eisenia foetida (Sav.) was raised from cocoons and experimental infections were induced in this host using sporocysts of the gregarine parasites Apolocystis elongata Phillips & Mackinnon 1946, and Nematocystis elmassiani (Hesse, 1909). Experimental infections were obtained by feeding to uninfected worms sporocysts obtained directly from infected host worms. This proved that the intervention of a vector is not a necessary condition of infection. Infections could not be induced by injecting sporocysts through the body wall into the body cavity. Infections are thus probably acquired in nature by the ingestion of sporocysts. Sporocysts do not leave the body of the host by being passed from coelom to lumen of the gut, nor do they pass directly to the exterior through apertures of the body wall. There was no evidence of parasitic autotomy. It is therefore concluded that death and decay of the host is the normal method of dissemination of sporocysts. Sporocysts were not infective after drying in air for three weeks. Other sporocysts lost potency after storage in moist conditions for several months. Infections involving the organisms specified were sporadic and unpredictable; modifying factors, such as variations in host susceptibility and latency in infection, appeared to be operating.
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  • 4
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. All zoologists are affected by provisions in the very recently published International Code of Zoological Nomenclature, the first revised edition of these important rules to appear in over 50 years. Common nomenclatural practices, often malpractices, of protozoologists and parasitologists who work primarily in taxonomic fields are revealed and discussed in light of recommendations and mandatory regulations to be found in the new Code. Some errors have been due solely to carelessness; others have involved misinterpretations of various directives; still others have involved cases not adequately covered by the old Règles. Certain mistakes of the past cannot be changed; but others are to be rectified upon discovery, according to mandates in articles of the new Code. Practical applications of the rules of nomenclature are stressed, and examples are taken from actual situations found to exist throughout all major taxa of the phylum Protozoa.Because of the value of such discussion in both new and revisory work in protozoan systematics, the following major topics are given special consideration: matters of orthography, the original spelling of names and their justified or unjustified emendation; authorships and dates of names, who is responsible and when, and how such data are properly cited; mandatory dates in the new Code, and their effect on both already established names and names not yet proposed; the principles of priority and conservation or continuity, and how the rules attempt to satisfy proponents of both of these diametrically opposed “laws”; the concepts of synonymy and homonymy, and proper methods of treating names which have become involved in such situations; family-group names, and the several special nomenclatural problems they present to protozoan taxonomists; the major problem of types, and the peculiar position of protozoologists with regard to the type concept, especially type-specimens for categories in the species-group; miscellaneous considerations, several unrelated but significant topics not appropriate for inclusion in preceding sections of the paper.
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  • 5
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. By an automatic electronic technique—the Flying Spot Particle Resolver—the effect of a wide range of concentrations of vitamin B12 on the size and growth of the B12-dependent Euglena gracilis was studied. Rate of cell growth was directly proportional, and cell size inversely proportional, to B12 concentration. Gross B12 depletion resulted in gigantism and prolongation of generation times.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. The plastid system of “normal”Euglena gracilis strain Z was found to be extremely unstable. Under normal culture conditions in the light about 1 or 2% of the cells were found to have lost spontaneously the capacity to green on further culturing. Cells treated with streptomycin, heat or U.V. all lost the capacity to green on further culturing. Bleached cells whether appearing spontaneously or by induction with streptomycin, heat, or U.V. light, were all found to possess within them organelles which were identified as proplastids.The proplastids of some “bleached” strains were capable of synthesizing porphyrins when grown in a standard culture medium. Others synthesized porphyrins only after the addition of delta-aminolevulinic acid to their medium, while proplastids of still other strains could not synthesize porphyrins from this precursor. Normal cells when grown in total darkness were found to possess proplastids morphologically identical with those of the bleached strains. Upon exposure to light the proplastids enlarged and greened. In cells which grew under continuous light the plastid system appeared as an interconnected system of tubules. Cells maintained on a schedule of 12-hour light and 12-hour dark had plastids which were detached from each other.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. A procedure is described which allows quantitative evaluation of the rate of dye uptake by phagotrophic activity of Tetrahymena. A fixation solution which retains integrity of vacuolar membranes for at least 7 hr, and of the pellicular membrane for about 3 hr, is also described.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Euglena and Chlamydomonas were cultured in an organic medium in the dark and at several light intensities (15, 60 and 150 ft-c) at temperatures from 20d̀ to 35d̀C. Below 32.5d̀, growth of Euglena was independent of light. Chlamydomonas was light dependent at all temperatures where growth occurred; there was no growth in the dark, at 15 ft-c, or at temperatures above 32.5d̀. At 35d̀, growth of Euglena became inversely light dependent; the higher the illumination, the poorer the growth. Multinucleated, giant euglenas were found at 35d̀, a greater percent of abnormal cells appearing at the higher light intensities. Monsters were not observed in Chlamydomonas.To explain the growth-inhibiting, monster-inducing effect of elevated temperatures on Euglena, it is postulated that a dark-formed thermosensitive protein, essential for normal cell division, is denatured. Light may increase the effect of heat on chlorophyll and the chloroplast, possibly by being converted to intraplastidic heat through the plastid carotenoids, thus having some indirect synergistic role in the phenomenon.
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  • 9
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. In a chemically-defined medium Tetrahymena setifera HZ-1 required a sterol, an alcohol, eleven amino acids, a purine, a pyrimidine, and six B-complex vitamins. The sterol requirement was met by a variety of 3β-OH, C27-C29 sterols including cholesterol and stigmasterol, but not by precursors of cholesterol which precede desmosterol or Δ7-cholestenol. Some combinations of long-chain fatty acids with a synthetic dipalmitoyl phosphorylethanolamine partly substituted for sterol. Ethyl and methyl alcohols (but not a variety of other alcohols and organic acids) satisfied the alcohol requirement.
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  • 10
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Tritrichomonas foetus survived much better on extended storage at -95 than at -28d̀C following slow freezing in the presence of 1.0 M glycerol. There was no significant difference between these temperatures in survival up to 8 days, but thereafter the protozoa continued to die off slowly at -28d̀, whereas their numbers remained essentially constant at -95d̀ for 128 to 256 days. The trichomonads' motility was much better after storage at -95d̀ than after storage at -28d̀, and fresh cultures could be initiated from the former much more readily.Other constituents of the suspending medium besides glycerol affect the survival of the protozoa upon freezing. Survival was much better when the protozoa were frozen in the original Diamond's trypticase-yeast extract-maltose-cysteine-ascorbic acid-serum medium in which they had been grown than when they were frozen in physiological salt solution or in fresh Diamond's medium. There was no significant difference between survival in the latter two suspending media. The speed and time of centrifugation needed to remove the trichomonads from the medium in which they had been grown had no effect on their survival upon subsequent freezing. Presumably some product or products of the trichomonads' metabolism have an additional protective action which supplements that of glycerol.When frozen in the original Diamond's medium in which they had been grown plus 1.0 M glycerol, an average of 15% of the trichomonads were alive after 128 days' storage at -28d̀ and an average of 38% were alive at -95d̀C. When frozen in physiological salt solution plus 1.0 M glycerol, these percentages were 8% and 12% respectively.
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