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  • 1
    Electronic Resource
    Electronic Resource
    Respiratory Studies on the Giant Amoeba Pelomyxa palustris (1981)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 28 (1981), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . The large fresh-water microaerobic amoeba Pelomyxa palustris does not contain mitochondria, but three types of bacterial endosymbionts are always present. Thus, it is of interest in the discussion of the possible origin of mitochondria from primitive prokaryotes. Gas exchanges (O2, CO2) and concentration of endosymbionts were determined in individual amoebae, in which the life cycle stage was noted. Grey type (stationary phase) amoebae had a lower O2 uptake and lower endosymbiont concentration than light type (growth phase) amoebae, and highest O2 uptake was found in centrifugal pieces of light type Pelomyxa, centrifuged in vivo, which contained nearly all of the endosymbionts. In light type amoebae, the respiratory activity was independent of O2 concentration between 1 and 21%, and, when compared on the basis of dry weight and protein, of the same order as that of other free-living protozoa. The R.Q. was slightly higher than 1, indicating that glycolysis does not play a significant role in energy metabolism. It is concluded that P. palustris is fully aerobic, and suggestions are presented as to the role of the endosymbionts in its respiratory metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1981.tb05316.x
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of oxygen deficiency on survival and glycogen content of Chironomus anthracinus (Diptera, Chironomidae) under laboratory and field conditions (1995)
    Springer
    Hydrobiologia 297 (1995), S. 187-200 
    Details
    ISSN: 1573-5117
    Keywords: Chironomus anthracinus ; oxygen deficiency ; anaerobic metabolism ; glycogen content ; Lake Esrom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Growth and glycogen content of Chironomus anthracinus in Lake Esrom, Denmark was examined during summer stratification in 1992 and 1993. Simultaneously, effects of oxygen deficiency on glycogen utilization and survival were experimentally studied. The population consisted of almost fullgrown 4th instar larvae in 1992 and 2nd and 3rd instar larvae in 1993. Growth rate and glycogen content changed as hypolimnetic oxygen deficiency increased. During a 1st phase of stratification dry weight and glycogen content increased (2nd and 3rd instars) or was almost constant (4th instar) but decreased significantly during the following 2nd phase. This change from growth to degrowth and utilization of endogenous glycogen reserves correlated with a change in the thickness of the microxic layer (〈0.2 mg O2 1−1) above the sediment surface. The layer increased from 2–3 m in phase 1 to 4–5 m in phase 2, and we suggest that this deteriorated the oxygen conditions and resulted in a change in larval energy metabolism from fully aerobic during the 1st phase to partly anaerobic in the 2nd phase. During the 2nd phase larval metabolism was estimated at less than 20% of normoxic rate. Experimental exposure of the larvae to anoxia indicated highly different survival of young larvae (2nd and 3rd instars) and older larvae (large 4th instars). The morality of young larvae was 50% after three days in anoxia at 10 °C, whereas only 25% of the older larvae had died after 3–4 weeks under similar conditions. Extending the treatment, however, resulted in increased death rate of the 4th instar larvae with only 10% surviving after seven weeks. The anaerobic metabolism of 4th instar larvae as estimated from glycogen degradation at 10 °C was 5% of normoxia in the interval from 0–5 days but 1.5% in the interval from 20–25 days. It is concluded that survival of C. anthracinus in anoxia is very limited, but traces of oxygen in the environment allowing for faint aerobic metabolism prolong the survival time of the larvae from a few days (2nd and 3rd instars) or a few weeks (4th instar) to probably 3–4 months.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019284
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  • 3
    Electronic Resource
    Electronic Resource
    The role of glycogen during the ontogenesis of Chironomus anthracinus (Chironomidae, Diptera) (1996)
    Springer
    Hydrobiologia 318 (1996), S. 51-59 
    Details
    ISSN: 1573-5117
    Keywords: Chironomus anthracinus ; ontogenesis ; glycogen ; ecdysis ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Large fluctuations in glycogen content were found in larvae, pupae and adults of Chironomus anthracinus (Zetterstedt) from the profundal zone of Lake Esrom, Denmark. In 2nd, 3rd and 4th instar larvae the glycogen concentration (expressed as percentage of dry weight) increased during periods of aerobic conditions to a maximum of 25%, but decreased in periods of hypoxia longer than two months to 10–12% in young larvae. A further decrease to about 5% took place, when moulting from 2nd to 3rd or from 3rd to 4th instar occurred after overturn. Prior to pupation the glycogen concentration was restored to 26–28%. The glycogen concentration approximated 22% in young pupae, but decreased during the pupal stage and newly hatched adults contained 12–15%. Finally, the glycogen store of both males and females was further reduced during the swarming period. Thus, glycogen seems to be an important energy source (1) during periods with hypoxic conditions, (2) during periods with high internal energy requirement such as ecdyses and metamorphosis, and (3) during the non-feeding adult life stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014131
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  • 4
    Electronic Resource
    Electronic Resource
    Energy metabolism of Chironomus anthracinus (Diptera: Chironomidae) from the profundal zone of Lake Esrom, Denmark, as a function of body size, temperature and oxygen concentration (1994)
    Springer
    Hydrobiologia 294 (1994), S. 43-50 
    Details
    ISSN: 1573-5117
    Keywords: Chironomus anthracinus ; oxygen consumption ; respiratory quotient ; energy production ; glycogen ; profundal zone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The profundal zone of Lake Esrom, Denmark has a dense population of Chironomus anthracinus, which survives 2–4 months of oxygen depletion each summer during stratification. The metabolism of 3rd and 4th instar larvae was examined in regard to variation in biomass and temperature. Respiration at air saturation was described by a curvilinear multiple regression relating oxygen consumption to individual AFDW and temperature. At 10 °C and varying oxygen regimes the O2 consumption and CO2 production of 4th instar larvae were almost unaltered from saturation to about 3 mg O2 l−1, but decreased steeply below this level. The respiratory quotient increased from 0.82 at saturation to about 3.4 at oxygen concentrations near 0.5 mg O2 l−1. This implied a shift from aerobic to partially anaerobic metabolism. At 0.5 mg O2 l−1 the total energy production equalled 20% of the rate at saturation of which more than one third was accounted for by anaerobic degradation of glycogen. This corresponded to a daily loss of 12 µg mg AFDW−1 or approximately 5% of the body reserves. At unchanged metabolic rate the glycogen store would last three weeks, but long term oxygen deficiency causes a further suppression of the energy metabolism in C. anthracinus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017624
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  • 5
    Electronic Resource
    Electronic Resource
    The respiration of common benthic invertebrate species from the shallow littoral zone of Lake Esrom, Denmark (1990)
    Springer
    Hydrobiologia 199 (1990), S. 117-130 
    Details
    ISSN: 1573-5117
    Keywords: respiration ; invertebrates ; benthos ; littoral ; Lake Esrom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To enable estimation of the total assimilation of benthic populations, we measured the oxygen consumption of macroinvertebrates from the littoral zone of a eutrophic lake. The animals were collected all the year round, and their respiration was measured at field temperatures using a closed-bottle method. Multiple regressions relating the rate of oxygen consumption to temperature and body size were established for 22 taxa, including data derived from the literature for meiofaunal groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00005604
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  • 6
    Electronic Resource
    Electronic Resource
    Survival and energy metabolism in an oxygen deficient environment. Field and laboratory studies on the bottom fauna from the profundal zone of Lake Esrom, Denmark (2000)
    Springer
    Hydrobiologia 432 (2000), S. 173-188 
    Details
    ISSN: 1573-5117
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The three macroinvertebrate taxa, Potamothrix hammoniensis, Chironomus anthracinus and Pisidium spp. are permanent inhabitants of the regularly microxic/anoxic profundal zone in Lake Esrom. In situ and laboratory studies (10 °C) of metabolism (aerobic and anaerobic) and anaerobic survival in P. hammoniensis and Pisidium spp. are compared with previous results from C. anthracinus. The late summer microxic conditions in the lake lasts 2–2 $$ - \frac{1}{2}$$ months, during which the three taxa display metabolic and behavioral strategies in order to survive. All three are respiratory oxy-regulators with critical oxygen levels at 1 mg O2 l−1 (P. hammoniensis and Pisidium spp.) or 2–3 mg O2 l−1 (C. anthracinus). The lethal time (LD50) in experimental anoxia follows a similar trend, with 150–170 days of survival in P. hammoniensis and Pisidium spp., compared to 2–5 weeks in C. anthracinus. The glycogen stores are almost (C. anthracinus) or fully exploited (P. hammoniensis and Pisidium spp.) during anaerobis and the animals finally enter a state of quiescence or dormancy. During the late phase of anoxia, their metabolism is down at (C. anthracinus) or below (P. hammoniensis and Pisidium spp.) 1% of normoxic metabolism. The populations in the lake behave rather similar in so far that the energy gain from anaerobic degradation of glycogen maximizes 1% of normoxic conditions regardless of species. Also, in Pisidium this appears to be the only energy source during dormancy. However, as previously presented in case of C. anthracinus, P. hammoniensis maintain a partly aerobic metabolism constituting 44% of normoxia during the microxic period, compared to the 12–19% obtained by C. anthracinus. It is thus demonstrated that P. hammoniensis and Pisidium spp. possess a remarkable ability to survive in situ severe oxygen depletion. P. hammoniensis can benefit from the presence of merely traces of oxygen, whereas C. anthracinus with poorer anaerobic survival is strongly dependent on minute oxygen supplies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004098910718
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  • 7
    Electronic Resource
    Electronic Resource
    Population dynamics and energy budget of Marionina southerni (Cernosvitov) (Enchytraeidae, Oligochaeta) in the shallow littoral of Lake Esrom, Denmark (1994)
    Springer
    Hydrobiologia 278 (1994), S. 291-301 
    Details
    ISSN: 1573-5117
    Keywords: Enchytraeidae ; population dynamics ; production ; respiration ; energy budget ; Lake Esrom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Marionina southerni (Cernosvitov) was numerically the dominant oligochaete in a shallow, strongly exposed surf zone locality (0–1 m depth) in the mesotrophic Lake Esrom. It comprised 21,500 ind m−2 or nearly 50% of the total oligochaete community, which otherwise was dominated by Nais spp. and the lumbriculid Stylodrilus heringianus Claparède. M. southerni appears to have a 1-y life cycle. Individual biomass ranged from 3 to 48 µg ash free dry weight. Annual net production at the site was 5.1 kcal m−2 (size-frequency method) with a P/B ratio of 2.5. This is about 0.5% of the estimated mean zoobenthic production in the littoral zone from 0 to 2 m depth in Lake Esrom. At 5° C M. southerni showed a constant oxygen uptake down to 25% oxygen saturation, but practically no regulatory respiration was found at 20 °C. In the field M. southerni was never found in sediment with less than 60% oxygen saturation. The annual community respiration of M. southerni was 14.2 kcal m−2, and annual assimilation thus made up 19.3 kcal m−2 with a net production efficiency of 26.5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00142338
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  • 8
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    The role of glycogen during the ontogenesis of Chironomus anthracinus (Chironomidae, Diptera) (1996)
    Springer
    Details
    Publication Date: 1996-01-01
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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  • 9
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    Effects of oxygen deficiency on survival and glycogen content of Chironomus anthracinus (Diptera, Chironomidae) under laboratory and field conditions (1995)
    Springer
    Details
    Publication Date: 1995-02-01
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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  • 10
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    The respiration of common benthic invertebrate species from the shallow littoral zone of Lake Esrom, Denmark (1990)
    Springer
    Details
    Publication Date: 1990-07-01
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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