ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

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Intracellular pH and energy metabolism in the highly stenothermal Antarctic bivalve Limopsis marionensis as a function of ambient temperature (1999)

Pörtner, H. O. ; Peck, L. ; Zielinski, S. ; [et al.]

Springer

Polar biology 22 (1999), S. 17-30

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ISSN: 1432-2056

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Changes in oxygen consumption, ammonia excretion and in the acid-base and energy status of various tissues were investigated in the cold stenothermal Antarctic bivalve, Limopsis marionensis, and compared to similar data in the limpet, Nacella concinna, for an assessment of thermal sensitivity. Oxygen consumption of L. marionensis varied between −1.5 and 2°C with a Q 10 of 2.2. Ammonia excretion could only be detected in animals exposed to elevated temperature for periods in excess of 45 days and close to death and it is interpreted as the onset of protein and amino acid catabolism with starvation under temperature stress. In L. marionensis any change in temperature as well as starvation stress at constant temperature induced a decrease in phospho-l-arginine and ATP levels. However, only temperature stress resulted in a drop in the Gibb's free energy change of ATP hydrolysis. Intracellular pH rose in all tissues during upward or downward temperature changes of only 1.5 or 2°C for 24 h with a concomitant trend to accumulate succinate and acetate in the tissues. These changes are seen to reflect disturbances of the tissue acid-base and energy status with any under- or overshoot in aerobic metabolic rate during a temperature decrease or increase. Elevated temperature at 2°C during 2 weeks of incubation resulted in continued net ATP depletion, at low levels of ATP free energy. This indicates long-term stress, which was also mirrored in the inability to establish a new steady-state mean rate of oxygen consumption. Incubation at even higher temperatures of 4 and 7°C led to an aggravation of energetic stress and transition to an intracellular acidosis, as well as a fall in oxygen consumption. In N. concinna a drop in energy levels was also visible at 2°C but was compensated for during long-term incubation. In conclusion, L. marionensis will be able to compensate for a temperature change only in a very narrow range whereas the thermal tolerance window is much wider in N. concinna. The inability of the metabolic rate to rise continually and the concomitant transition to anaerobic metabolism and long-term energetic stress characterize the upper critical temperature. Stenothermality is discussed, not only as reflecting the permanent and very stable low temperature in the natural environment, but also regarding dif- ferences in the level of activity and aerobic scope.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003000050386

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2

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Population genetics of the Antarctic heteronemertean Parbolasia corrugatus from the South Orkney Islands (1998)

Rogers, A. D. ; Clarke, A. ; Peck, L. S.

Springer

Marine biology 131 (1998), S. 1-13

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ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract An allozyme survey, using starch-gel electrophoresis, was carried out on eight populations of the Antarctic nemertean worm Parborlasia corrugatus (McIntosh, 1876) collected from locations around the South Orkney Islands, Antarctica. These populations were separated by distances in the order of tens of kilometres. Genetic variation was estimated over 22 enzyme loci for all populations examined, giving an observed heterozygosity of 0.142. This was much lower than the expected heterozygosity (H e = 0.201), and it was found that there was a significant deficiency of het‐erozygotes across four enzyme loci ( p ≤ 0.01). A more detailed examination of this deficiency of heterozygotes was undertaken for the six populations and six variable enzyme loci for which the most complete data sets existed. A significant deficiency of heterozygotes was found at the enzyme locus Odh-1 for four of the six populations examined ( p ≤ 0.01). Mean F is (0.240) indicated a significant ( p ≤ 0.01) within-population component of the heterozygote deficiency estimated for the six populations sampled, and this was mainly due to the␣Ap-1, Odh-1 and Pgm-1 loci. The mean F st value (0.036) was also significant ( p ≤ 0.01), indicating a degree of genetic differentiation between populations. The observed levels of genetic differentiation between populations of P. corrugatus and the significant heterozygote deficiencies were unexpected, because this species has been reported to have a long-lived planktotrophic larva. It is hypothesised that recruitment of P. corrugatus in the South Orkney Islands originates from genetically distinct populations located in the Weddell Sea and to the west of the Antarctic Peninsula. Shifts in the relative position of the Weddell Sea Front, Weddell–Scotia Confluence and Scotia Front, relative to the South Orkney Islands, provide a mechanism for variation in the origin of recruits over time.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002270050290

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3

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Reproductive patterns in the Antarctic brachiopod Liothyrella uva (1998)

Meidlinger, K. ; Tyler, P. A. ; Peck, L. S.

Springer

Marine biology 132 (1998), S. 153-162

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ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The reproductive cycle of the Antarctic articulate brachiopod Liothyrella uva (Broderip, 1833) is described from monthly samples collected between September 1985 and July 1987 from a population at Signy Island, Antarctica. Spermatogenesis and oogenesis are described for the first time in this species. Surface dried-tissue masses for a standard individual (41 mm shell length) were calculated for the digestive diverticula, gut, lophophore and gonad from monthly dissections of 15 brachiopods. Seasonal patterns, with summer peaks, were observed in the digestive diverticula and gut. The lophophore and gonad masses did not exhibit seasonal trends. Females showed a sharp decrease in proportion of large oocytes between October and November in 1986, suggesting spawning during this period. There was no similar decrease during the same period in 1985. Mean percent spermatozoa measurements revealed a large increase in November 1985 and a rapid decline in December 1985. This suggested a large spawning event for males in 1985 which was not repeated the following year. These data indicate large inter-annual differences in reproductive activity as well as differences between males and females. They also suggest the possibility of sperm storage by females. Brood characteristics were also highly variable. The smallest brooding female was 31.5 mm in length. Some females brooded more than one developmental stage simultaneously, and variation in brood size (numbers of embryos or larvae held in the lophophore) and brood composition between individuals was high. All samples collected throughout the 2 yr period contained some females with broods. The data suggest that the reproductive strategy of L. uva is highly plastic, and that there may be three reproductive periodicities on seasonal, annual and inter-annual time scales.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002270050381

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4

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trans-Carbonyl(pentafluorophenyl-C)bis[(pentafluorophenyl)diphenylphosphine-P]iridium(I) (1998)

Fawcett, J. ; Hope, E. G. ; Peck, L. A.

Oxford [u.a.] : International Union of Crystallography (IUCr)

Acta crystallographica 54 (1998), S. 1752-1753

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ISSN: 1600-5759

Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001

Topics: Chemistry and Pharmacology , Geosciences , Physics

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1107/S0108270198008063

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5

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A pelagic bryozoan from Antarctica (1995)

Peck, L. S. ; Hayward, P. J. ; Spencer-Jones, M. E.

Springer

Marine biology 123 (1995), S. 757-762

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ISSN: 1432-1793

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Spherical or sub-spherical bryozoan colonies were collected from the surface waters of a coastal polynya in the southeastern Weddell Sea near Halley Station in February 1992. These are the first truly pelagic marine bryozoan colones yet recorded. The collection site is the edge of the Brunt ice shelf, which is between 150 and 250 m thick in this area, and the depth of water to the seabed is ∼-400 m. The colonies were hollow, composed of a single layer of autozooids, and appeared complete and undamaged. They were between 5.0 and 23.0 mm in diameter, were brownish in colour in life, and pale yellowish brown after preservation. Light and scanning electron microscope investigations of the colonies indicated that they belonged to the genus Alcyonidium, and they are here compared with A. flabelliforme Kirkpatrick, a known antarctic benthic species. Both a pelagic existence and hollow spherical colony form are new attributes for the phylum Bryozoa. However, because of the plasticity of form of species belonging to the genus Alcyonidium, these is not enough evidence for the introduction of a new species at this time. The colonies found may represent a previously undescribed juvenile stage of a known Alcyonidium species. It is postulated that these colonies may obtain nutrition from the often abundant populations of ice algae present in the lower layers of permanent sea-ice.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00349118

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6

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Thermal sensitivity of mitochondrial function in the Antarctic Notothenioid Lepidonotothen nudifrons (1999)

Hardewig, I. ; Pörtner, H. O. ; Peck, L. S.

Springer

Journal of comparative physiology 169 (1999), S. 597-604

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ISSN: 1432-136X

Keywords: Key words Antarctic fish ; Temperature ; Mitochondrial respiration ; Proton leakage ; Isocitrate dehydrogenase

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract The thermal sensitivity of mitochondrial function was investigated in the stenothermal Antarctic fish Lepidonotothen nudifrons. State 3 respiration increases with increasing temperature between 0 °C and 18 °C with a Q 10 of 2.43–2.63. State 4 respiration in the presence of oligomycin, an inhibitor of mitochondrial ATP synthase, quantifies the leakage of protons through the inner mitochondrial membrane, which causes oxygen consumption without concomitant ATP production. This parameter shows an unusually high Q 10 of 4.21 ± 0.42 (0–18 °C), which indicates that proton leakage does not depend merely on ion diffusion but is an enzyme-catalysed process. The differential thermal sensitivity of oxidative phosphorylation (=state 3) and proton leakage (=state 4 in the presence of oligomycin) leads to progressive uncoupling of the mitochondria and decreased efficiency of oxidative phosphorylation under in vivo conditions if the body temperature of L. nudifrons increases.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s003600050260

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