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  • Articles  (43)
  • Blackwell Publishing Ltd  (43)
  • 2005-2009
  • 1990-1994  (25)
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  • 1955-1959  (3)
  • 1925-1929
  • Biology  (43)
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  • Articles  (43)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 4 (1957), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. The endogenous development of the life cycle of Eimeria alabamensis Christensen, 1941, occurs in the nucleus of the intestinal cells of cattle. Calves were killed at various intervals after inoculation with infective oöcysts to study the endogenous cycle. Excysted sporozoites were found in the contents or scrapings from the walls of rumen, omasum, small intestine, cecum, and colon. They were found in the cytoplasm of intestinal epithelium at 2 days. Schizonts were found in the nuclei beginning at 2 days, but the number was low by the 8th day. Merozoite numbers usually ranged between 16 and 32. Some host nuclei contained as many as 48 or more, but these appeared to be the result of more than one schizont merging in the same host nucleus. Merozoites were slender, spindle-shaped bodies while still in the schizont walls, but were short with bluntly rounded tips when found in intracellular spaces and crypts. Gametocytes were found as early as the 4th day. Most of the stages of gametogenesis were limited to the lowest third of the small intestine, but in heavy infections some were also found in the cecum and upper colon. Microgametocytes were multinucleate and were more densely stained than the uninucleate macrogametocytes. The ratio of macrogametocytes to microgametocytes in 100 gametes was 78: 22. Oöcysis with “shells” were found in sections of the lower 20 feet of the ileum on the 6th day, which coincided with the shortest prepatent period reported previously. As many as three schizonts or microgametocytes or four or five macrogametocytes or oöcysts could be found in the same host nucleus. The variations in shape of the oöcysts appeared to be dependent on the number of oöcysts crowded into each nucleus.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 36 (1989), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 13C-nuciear magnetic resonance (NMR) spectroscopy was used to investigate the products of glycerol and acetate metabolism released by Leishmania braziliensis panamensis promastigotes and also to examine the interaction of each of these substrates with glucose or alanine. The NMR data were supplemented by measurements of the rates of oxygen consumption and substrate utilization, and of 14CO2 production from 14C-labeIed substrate. Cells incubated with [2-13C]glycerol released acetate, succinate and D-lactate in addition to CO2. Cells incubated with acetate released only CO2. More succinate C-2/C-3 than C-l/C-4 was released from both [2-13C]glycerol and [2-13C]glucose, indicating that succinate was formed predominantly by CO2 fixation followed by reverse flux through part of the Krebs cycle. Some redistribution of the position of labeling was also seen in alanine and pyruvate, suggesting cycling through pyruvate/oxaloacetate/phosphoenolpyruvate. Cells incubated with combinations of 2 substrates consumed oxygen at the same rate as cells incubated with 1 or no substrate, even though the total substrate utilization had increased. When promastigotes were incubated with both glycerol and glucose, the rate of glucose consumption was unchanged but glycerol consumption decreased about 50%, and the rate of 14CO2 production from [l,(3)-14C]glycerol decreased about 60%. Alanine did not affect the rates of consumption of glucose or glycerol, but decreased 14CO2 production from these substrates by increasing flow of label into alanine. Although glucose decreased alanine consumption by 70%, it increased the rate of 14CO2 production from [U-14C]- and [l-14C]alanine by about 20%. This is consistent with rapid equilibration of alanine with pyruvate derived from glucose and yet little decrease in the specific activity of the large alanine pool.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 6 (1959), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Differences in temperature-tolerance, generation time, nutritional requirements, osmoresistance, pigment production, and sensitivity to high hydrogen or hydroxyl ion concentration have been observed among varieties, and among mating types within varieties of Tetrahymena pyriformis. The usefulness of these differences to taxonomists and geneticists is discussed.The nutrition of a temperature-tolerant strain, mating type II, variety 1, was given special attention and a chemicallydefined medium devised to support rapid growth at 35d̀ C. At 40d̀, growth in this medium failed, but was good in a crude medium. Temperature factors are suggested. Permeability of this ciliate, as inferred by utilization of nucleotides, was high.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 6 (1959), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. In cattle fed a high-starch diet, species of Entodinium and Diplodinium ingested associated ruminal bacteria. Stained preparations of diluted rumen contents showed Entodinium caudatum, E. minimum, E. dubardi, (syn. E. simplex), E. longinucleatum, E. bursa, E. nanellum, E. exiguum, and E. vorax contained gram-positive diplococci. Starch grains with adherent gram-positive diplococci were observed within Entodinium spp. Diplodinium ecaudatum forma ecaudatum, D. ecaudatum forma caudatum, D. neglectum and an unidentified species of Diplodinium also ingested ruminal diplococci. Bacteria were isolated from mixed species of Entodinium by washing and culturing the protozoa in a starch feed-extract agar medium. The strains isolated from the ciliates were gram-positive diplococci, 0.8 times 1–1.5 μm, which attached themselves to starch granules and were able to digest the starch. Conclusive evidence of bacterial ingestion by the oligotrichs was obtained by providing the bacterial cultures to Entodinium species (E. dubardi and E. minimum) which had been starved 24 hr. Gram-stained preparations showed the ciliates readily ingested the bacteria. The amylolytic cocci utilized by Entodinium spp. were identified as Streptococcus bovis.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Continuous cultivation of Plasmodium falciparum presently requires the nutritionally complex medium, RPMI 1640. A basal medium of KCl, NaCl, Na2HPO4, Ca(NO3)2, MgSO4, glucose, reduced glutathione, HEPES buffer, hypoxanthine, phenol red (in RPMI 1640 concentrations), and 10% (v/v) exhaustively dialyzed pooled human serum was used to determine which vitamins and amino acids had to be exogenously supplied for continuous cultivation. Supplementation of basal medium with calcium pantothenate, cystine, glutamate, glutamine, isoleucine, methionine, proline, and tyrosine was necessary for continuous growth. This semi-defined minimal medium supported continuous growth of four isolates of P. falciparum at rates slightly less than those obtained with RPMI 1640. Adding any other vitamin or amino acid did not improve growth. Incorporation of several non-essential amino acids, particularly phenylalanine and leucine, into proteins was markedly enhanced in the minimal medium compared to RPMI 1640.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of immunogenetics 19 (1992), S. 0 
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The aim of the study was to determine whether C5 deficiency in the mouse is associated with resistance to the development of secondary amyloidosis. Chronic inflammation was induced in the F2 progeny, derived from matings between amyloid-susceptible and amyloid-resistance mice, by daily injections of azocasein for thirty days. Using a restriction fragment length polymorphism generated by digestion of genomic DNA with the restriction enzyme HindIII, C5 sufficient and deficient DNA can be clearly differentiated. Eight mice were found to be C5 sufficient, 32 were heterozygotes and 14 were found to be C5 deficient. Grading of the splenic amyloid load from negative to 4+ was performed after staining tissue squashes with Congo red and viewing them under a polarizing microscope. Seventeen mice were noted to have negative to trace, 18 had moderate (1+-2+) and 19 had heavy (3 H+-4+) amyloid deposition. There was no correlation between splenic amyloid load and C5 deficiency. Based on these results it is clear that C5 deficiency and resistance to secondary amyloidosis are not associated.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 21 (1989), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. Mean motion and near-bed flows in streams and rivers can be described using a classification derived from fairly simple field measurements. Our proposed classification is ecologically useful because it incorporates the combined effects of velocity, depth and substrate roughness to provide a means of quantifying the flow regimes occurring within the microhabitats of stream benthos.2. Mean motion is characterized by the Reynolds number and the Froude number. Both are easily calculated, and because they are dimensionless they provide a means of comparing flows at different sites.3. Five categories of near-bed flows (i.e. the flow microenvironments of stream benthos) are recognized. Flow may be hydraulically smooth or hydraulically rough and the latter category is subdivided further into: chaotic flow, wake interference flow, isolated roughness flow and skimming flow. Hydraulically smooth flows occur in sections of a river bed with fine sediments (e.g. sands, muds and clays). over flat sheets of bedrock, or in association with the flat blades of submerged macrophytes. Hydraulically rough flows occur where the substrate elements are larger (e. g. pebbles, cobbles and boulders) and are a function of substrate roughness and the depth of flow relative to the height of the roughness elements. Chaotic flows and wake interference flows predominate in riffles whilst isolated roughness flows and skimming flows are more likely to be a feature of runs.4. Conventional stream sampling methods (e.g. the Surber and box or cylinder samplers) may collect across several different flow microhabitats. Our classification should enable different flow microenvironments to be recognized and so sampled more appropriately which, in turn, may reduce apparent clumping and the wide confidence intervals of benthic population estimates. Because our classification identifies ‘patches’ within the flow regime associated with the stream bed it enables stream ecologists to generate testable hypotheses regarding the distribution and abundance of benthic species in response to flow.5. Our classification identifies spatial patterns in the flow regimes associated with the stream bed. Temporal patterns have not been identified: however, predictable changes in spatial patterns will resuh from temporal changes in stream discharge.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 9 (1993), S. 0 
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 17 (1994), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Field experiments were conducted in St Paul, MN, USA, to test the hypothesis that early season declines in the red:far-red ratio (R:FR) associated with FR reflection from neighbouring leaves have a role in regulating barley development. Treatment plants were grown adjacent to densely sown border rows of barley. The borders functioned to reflect far-red (FR), which reduced R:FR within the treatment plant light environment without shading treatment plants. Barriers were set in the soil to minimize root interactions between treatment plants and borders. Treatment plants were spaced either 2 or 16 cm apart. The presence of borders significantly increased shoot leaf and internode lengths at both plant spacings. Leaf sheath length data suggest that interactions between 2 cm spaced treatment plants enhanced plant responsiveness to the presence of borders. Border treatments shortened the period of vegetative growth prior to initiation of main shoot floral primordia. Bordered plants formed fewer main shoot leaves, initiated internode elongation at a lower node, and had slightly earlier heading dates than unbordered controls. Leaf appearance rate was not influenced by border treatments. We conclude that barley shoot development is photomorphogenically modulated by R:FR. Early season shifts in R:FR could have a significant influence on shoot development given that barley has the capacity to detect and developmentally respond to declines in R:FR associated with FR reflection from neighbours.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 12 (1989), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A freeze-fixation technique was used to examine the distribution of ice crystals and the pattern of freezing in peach flower buds. In dormant buds, ice crystals formed at localized sites within the bud axis and scales. Ice crystal formation disrupted tissues and mechanical injury from repetitive freezethaw cycles was apparent. There was evidence of ice formation in the floral organs of dormant buds exposed to −25°C but none observed in buds exposed to either −5 or −10°C. The distribution of ice crystals was different in deacclimated buds. In addition to large ice crystals within the subtending bud axis and scales, evidence of large crystals within the developing floral organs was noted. These crystals were most prominent in the lower portions of the developing flower and peduncle, and caused a separation of the epidermal layer from adjacent cells. The distribution of ice crystals within both dormant and deacclimated peach flower buds corroborated the results of previous thermal analysis experiments.
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