Adaptation strategies of copepods (superfamily Centropagoidea) in the White Sea (66°N)

Seasonal dynamics of major biochemical features were studied for three abundant egg-diapausing copepods Acartia bifilosa, Centropages hamatus and Temora longicornis, in the White Sea (66°N), between June 2002 and September 2002. Dry weight (DW) and prosome length varied from 0.54 μg ind⁻¹ and 0.163 ± 0.012 mm (A. bifilosa, CI) to 9.58 ± 0.72 μg ind⁻¹ and 1.135 ± 0.167 mm (C. hamatus, females). C_org and N_org content reached up to 5.91 ± 0.44 and 1.23 ± 0.09 μg ind⁻¹ (C. hamatus, females). Protein and lipid content varied greatly from 31.8 to 67.3% DW and from 8.7 to 42.6% DW, respectively. These species show somewhat different biology compared to species at lower latitudes. The copepods use lipid stores to survive during short-term food shortage (e.g. in autumn) and successfully complete their life cycle. In the isolated White Sea during last post-glacial period, species probably evolved some special biochemical features (especially wax esters presence). Food quality demands and long ice coverage are possible factors limiting early development of species in spring.     

Nature of light requirement for the flowering of Chenopodium rubrum L. (Ecotype 60° 47′N)

It has been shown that induction of flowering in Chenopodium rubrum L. (ecotype 60° 47 N) seedlings in BCJ light conditions is intensity dependent (Cumming, 1969, Canad. J. Bot. 47, 1247–1250) and that, this intensity dependence is not based on photosynthesis (Sawhney and Cumming, 1971, Can. J. Bot. 49, 2133–2137). Since BCJ light emits a high proportion of energy in the far-red, and the High Energy Reaction (HER) has its action maxima in the far-red and blue regions of the spectrum, we tested the involvement of HER in the light induction of flowering in C. rubrum. Our results show that optimum intensities of blue light are effective in inducing flowering in C. rubrum. Red light exposure does not lead to flower induction. We suggest the HER may be involved in the flower induction of C. rubrum in light. However, when high energy in blue and/or farred is provided in presence of energy between 500–700 nm wavebands, there is no flowering in C. rubrum. We suggest that flower inducing activity of HER may be counteracted by flower inhibitory action of red wavebands.This paper constitutes a part of a Ph. D. thesis submitted to the University of Western Ontario, London, Ontario     

Nature of light requirement for the flowering of Chenopodium rubrum L. (Ecotype 60° 47′ N)

Seedlings of C. rubrum were irradiated with different light qualities and intensities following a single inductive dark period. Our results show that relatively low intensity white light (35–100 ft. c.) does not support flower development while high intensity white light (650–800 ft. c.) permits 100% flowering. We have shown that the low intensity light inhibiton of flower development is not due to suboptimal photosynthesis. Relatively low intensities of light rich in far-red or blue wavebands sustains optimum flower development, whereas red light is totally ineffective in this respect. Considering that the intensity dependent High Energy Reaction (HER) has its action maxima in the blue and far-red we propose that HER may be positively involved in the flower development of C. rubrum. Our study further suggests that there may be some flower inhibitory component at play in relatively low intensity white light conditions and HER may be required to counteract this flower inhibitory effect.Abbreviations SD short day plant - HER High Energy Reaction - P_FR far-red absorbing form of phytochrome - P_R red absorbing form of phytochrome - L.I.I. low intensity incandescent white light - H.I.I. high intensity incandescent white light - L.I.F. low intensity fluorescent white light - H.I.F. high intensity fluorescent white light - GA₃ gibbrellic acid This paper constitutes a part of a Ph.D. thesis submitted to the University of Western Ontario, London, Ontario.     

Distribution of pelagic Ostracoda (Crustacea) inhabiting the waters around Svalbard (Arctic Ocean: 76°36–81°50N)

Although, pelagic Ostracoda are locally abundant component of the mesozooplankton in the waters around Svalbard, the group remains poorly characterised both taxonomically and ecologically. Herein, the spatial and vertical variations in abundances and species composition of the pelagic Ostracoda assemblages are examined and related to the water masses. The study is based on a series of zooplankton samples collected with a multinet plankton sampler (MPS; HydroBios, Kiel), consisting of five nets fitted with a 180-μm mesh net. Samples were collected from deep stations (i.e., with bottom depths >300 m) around Svalbard and included localities influenced by the West Spitsbergen Current and the East Spitsbergen Current and to the north of Svalbard, between years 2001 and 2006. Throughout all the samples studied Discoconchoecia elegans was the numerically dominant species. The other species found were Boroecia maxima, Boroecia borealis, Obtusoecia obtusata, and a rare novel Boroecia species. Analyses of the pelagic Ostracoda assemblages showed that their variability was predominantly influenced by four factors: water temperature, geographical position, bottom depth and season. The highest densities of D. elegans were correlated with salinities >35 PSU whereas B. maxima distribution was dependent on latitude. Highest concentrations of B. borealis were determined by longitude. Abundances of O. obtusata were positively correlated with warmer water temperatures. Thus this work suggests that halocyprids have the potential to be good indicators of environmental changes associated with shifts in climate at high latitudes in the North Atlantic.     

Binuclear metal complexes. 59. Synthesis and magnetism of dicopper(II) and copper(II)-nickel(II) complexes with N,N′-ethylenedisalicylamidatocuprate(II)

The complexes [Cu(samen)Cu(L)] and [Cu(samen)Ni(L)₂] (Lbpy, phen) have been synthesized by the reaction of sodium N,N′-ethylenedisalicylamidatocuprate(II) pentahydrate (Na₂- [Cu(samen)]·5H₂O), a divalent metal ion, and 2,2′- dipyridyl or 1,10-phenanthroline. Cryomagnetic data for the CuCu complexes did not fit the Bleaney- Bowers equation; but the data did fit a modified Bleaney-Bowers equation

with a large negative J and a significant negative θ, suggesting that a considerable magnetic interaction operates between essentially planar [Cu(samen)Cu(L)] molecules. The magnetisms of the CuNi complexes were well interpreted in terms of the susceptibility equation based on the Heisenberg model. An antiferromagnetic spin-exchange interaction (J= −13∼−14 cm⁻¹) was suggested between the metal ions.     

Microbial metabolism of aromatic nitriles. Enzymology of C–N cleavage by Nocardia sp. (Rhodochrous group) N.C.I.B. 11216

1. An organism utilizing benzonitrile as sole carbon and nitrogen source was isolated by the enrichment-culture technique and identified as a Nocardia sp. of the rhodochrous group. 2. Respiration studies indicate that nitrile degradation proceeds through benzoic acid and catechol. 3. Cell-free extracts of benzonitrile-grown cells contain an enzyme that catalyses the conversion of benzonitrile directly into benzoic acid without intermediate formation of benzamide. 4. This nitrilase enzyme was purified by DEAE-cellulose chromatography and gel filtration on Sephadex G-100 in the presence and absence of substrate. The purity of the enzyme was confirmed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and isoelectric focusing on polyacrylamide gel. 5. The enzyme shows a time-dependent substrate-activation process in which the substrate catalyses the association of inactive subunits of mol.wt. 45000 to form the polymeric 12-unit active enzyme of mol.wt. 560000. The time required for complete association is highly dependent on the concentration of the enzyme, temperature and pH. 6. The associated enzyme has a pH optimum of 8.0 and K(m) with benzonitrile as substrate of 4mm. The activation energy of the reaction as deduced from the Arrhenius plot is 51.8kJ/mol. 7. Enzyme activity is inhibited by thiol-specific reagents and several metal ions. 8. Studies with different substrates indicate that the nitrilase is specific for nitrile groups directly attached to the benzene ring. Various substituents in the ring are compatible with activity, though ortho-substitution, except by fluorine, renders the nitrile invulnerable to attack. 9. The environmental implications of these findings and the possible significance of the enzyme in the regulation of metabolism are discussed.     

Human exposure to ultraviolet radiation at the Antipodes – a comparison between an Antarctic (67°S) and Arctic (75°N) location

. We used ultraviolet radiation dosimeters to investigate human exposure at two polar latitudes with a 24-h photoperiod: at Rothera Station (UK) (67°S) and at a field camp in the Haughton impact structure in the Canadian High Arctic (75°N). Mean personal UV radiation exposure in the Antarctic location was 4.3 times greater than that in the Arctic location, even in the absence of ozone depletion. More than zenith angle accounted for the higher UV exposure. Widespread snow and ice covers, and probably less atmospheric pollution, caused higher personal exposures. Although the mean exposures were higher in the Antarctic location, the mean exposure ratio in the Antarctic (0.20ǂ.09) was similar to the value measured in the Arctic (0.27ǂ.09) on clear days. We use the Antarctic ratio to provide quantitative estimates of UV-radiation exposure for workers at the Geographical South Pole for the winter solstice under a constant 24-h photoperiod. Exposure ratios can be used to translate measurements of UV radiation by horizontally fixed spectroradiometers into estimates of the mean exposures expected in populations at polar latitudes, although variations between individuals are large. The data have implications for determining the UV exposures of indigenous high-latitude populations.     

Characterization of Family D DNA polymerase from Thermococcus sp. 9°N

Accurate DNA replication is essential for maintenance of every genome. All archaeal genomes except Crenarchaea, encode for a member of Family B (polB) and Family D (polD) DNA polymerases. Gene deletion studies in Thermococcus kodakaraensis and Methanococcus maripaludis show that polD is the only essential DNA polymerase in these organisms. Thus, polD may be the primary replicative DNA polymerase for both leading and lagging strand synthesis. To understand this unique archaeal enzyme, we report the biochemical characterization of a heterodimeric polD from Thermococcus. PolD contains both DNA polymerase and proofreading 3′–5′ exonuclease activities to ensure efficient and accurate genome duplication. The polD incorporation fidelity was determined for the first time. Despite containing 3′–5′ exonuclease proofreading activity, polD has a relatively high error rate (95 × 10^?5) compared to polB (19 × 10^?5) and at least 10-fold higher than the polB DNA polymerases from yeast (polε and polδ) or Escherichia coli DNA polIII holoenzyme. The implications of polD fidelity and biochemical properties in leading and lagging strand synthesis are discussed.     

Latitudinal shifts of forest and savanna in N. W. Africa during the Brunhes chron: further marine palynological results from site M 16415 (9°;N 19°W)

Palynological data of the marine core M 16415-2 show latitudinal shifts of the northern fringe of the tropical rain forest in north-west Africa during the last 700 ka. Savanna and dry open forest expanded southwards and tropical rain forest expanded northwards during dry and humid periods, respectively. Until 220 ka B.P., the tropical rain forest probably kept its zonal character in West Africa during glacials and interglacials. It is only during the last two glacial periods that the rain forest possibly fragmented into refugia. Throughout the Brunhes chron, pollen and spore transport was mainly by trade winds.     

To the 100th anniversary of N.I. Shapiro (1906–1987)

Chronicle

To the 100th anniversary of N.I. Shapiro (1906–1987)     

具喙田菁在中纬度(28～35°N)地区的光周期现象观察及其应用(简报)

具喙田菁的花期随着日照时数的减少而提前;诱导开花的短日照处理天数随着日照长度的缩短而减少;相同日照时数条件下,花期因温度升高而提前。本文据此提出中纬度地区最适短日照时数为每天11小时,处理58天。7月上旬开花,9月初种籽成熟。     

肋果沙棘(Hippophae neurocarpa S.W.Liu et T.N.He)自然种群的风媒传粉特征

野外调查了青藏高原特有植物肋果沙棘的花期物候、开花式样以及风媒传粉特征,对其花粉生活力、柱头可授性及单花花粉量进行了检测.结果表明,肋果沙棘有许多适应风媒传粉的特征:雌雄异株,花小,无花冠,先叶开放,雄花萼片纵裂形成对流的"风洞",花粉近球形,单花花粉量大;雌花柱头细长捻状,伸出萼筒,授粉面大,密布乳突.花粉生活力可以持续16.5 d,柱头可授性为10～20d.肋果沙棘传粉多发生在昼夜温差大的5月中下旬,在多变的气候条件下,种群花期可持续约12～25d,但在晴朗的天气条件下具有爆发性的集中开花机制,是对恶劣条件的适应.重力玻片法检测表明,离花粉源15m左右远的地点花粉密度最大,135m仍能接收到花粉,夜间接收到的花粉数量也很可观,这些研究结果表明,该植物集中在有利的晴朗天气昼夜进行长距离的风媒散粉,能较好地适应青藏高原的复杂环境.     

Création du genre Californiella N.gen. (Rhodophycophyta) et révision du genre DasyporellaStolley, 1893 (Dasycladales)

The genus Dasyporella was created by Stolley in 1893. Later, two different species were assigned to this genus under the same specific name Dasyporella norvegica. One of them was misinterpreted by Johnson & Konishi (1959) which introduced a confusion in the genus definition. The revision of the genus Dasyporella was therefore necessary and the study of new specimens belonging to the misinterpreted species have led to the creation of a new genus: Californiella. This new genus clarifies the concept of Dasyporella with the reinstatement of its original definition.     

Leptothorax (Mychothorax) kutteri N. Sp., eine sozialparasitische ameise (Hymenoptera,formicidæ)

Résumé Leptothorax (Mychothorax) kutteri n. sp. est décrit. La nouvelle espèce n'a pas d'ouvrières. Elle vit comme parasite dans des nids polygynes deLeptothorax (Mychothorax) acervorum Fabr. à côté des femelles fertilisées de cette espèce. Les colonies mixtes produisent des sexués des deux espèces. La nouvelle espèce n'a pas de spécialisations dans sa morphologie externe par comparaison avecL. acervorum. L'origine probable d'un tel parasite dans des espèces polygynes est discutée.

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Summary Leptothorax (Mychothorax) kutteri n. sp. is described. The new species is living as a workerless social parasite in polygynous nests ofLeptothorax (Mychothorax) acervorum Fabr. together with fertilized females of this species. Sexuals of both species are bred in the mixed colonies. The new species shows no morphological specialisation in comparison withL. acervorum. The probable origin of such a social parasite in polygynous ant species is discussed.

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Zusammenfassung Leptothorax (Mychothorax) kutteri n. sp. wird beschrieben. Die neue Art lebt sozialparasitisch in polygynen Nestern vonLeptothorax (Mychothorax) acervorum Fabr. neben begatteten dieser Art.L. kutteri ist arbeiterlos. In den gemischten Nestern werden Geschlechtstiere beider Arten aufgezogen. Die neue Art weist im äusseren Körperbau keine Spezialisierung gegenüber,L. acervorum auf. Die vermutliche Entstehung eines solchen Sozialparasiten in polygynen Ameisenarten wird diskutiert.

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Vorstand: Prof. Dr.K. Gösswald.     

Arctic cyanobacteria and limnological properties of their environment: Bylot Island, Northwest Territories, Canada (73°N, 80°W)

Cyanobacteria were a major constituent of phototrophic communities in the lakes, ponds and streams of Bylot Island, in the Canadian high Arctic. The waters spanned a range of temperatures (1.8–16.8°C in late July), pH regimes (6.2–9.2) and conductivities (1.5–1700 μS cm⁻¹) but nutrient concentrations were consistently low (< 1 μg dissolved reactive P l⁻¹ at all sites; < 10 μg NO₃-N l⁻¹ at most sites). Picoplanktonic species (Synechococcus spp.) were often the numerical dominants in the plankton, and periphytic filamentous species (Oscillatoriaceae) commonly formed thick (5–50 mm) benthic mats. Bloom-forming species of cyanobacteria were either absent or poorly represented even in Chla-rich ponds. The total community biomass ranged from 0.1 to 29.8 μg Chla l⁻¹ in the plankton and from 1.1 to 34.8 μg Chla cm⁻² in the benthos. The in vivo absorbance characteristics of isolates from these environments indicated a genetically diverse range of species in each group of Arctic cyanobacteria. Growth versus irradiance relationships were determined for each of the isolates and similarly revealed large genetic differences (maximum growth rates from 0.17 to 0.61 day⁻¹), even between morphologically identical taxa. A comparison of nutrients, pigment concentrations and species composition underscores the strong similarities between freshwater ecosystems in the north and south polar zones. Received: 3 June 1996 / Accepted: 3 November 1996