bluuebunny/crossref_metadata_2025 huggingface dataset:
Innocuous skin cooling modulates perception and neurophysiological correlates of brief CO2 laser stimuli in humans
Authors: Nahra Hicham , Plaghki Léon
Published: December 2004

The present study examined the influence of innocuous skin cooling on the perception and neurophysiological correlates of brief noxious CO2 laser stimuli. In nine normal subjects, brief CO2 laser pulses of four different intensities (duration 50 ms; diameter 5 mm; intensity range 5.8–10.6 mJ/mm2) were delivered at random every 5–10 s on the dorsum of the hand. Innocuous skin cooling was performed by a thermode (20 °C; 3 × 3 cm) with a central hole for the laser test stimuli. Quality and intensity (VAS) of perceptions, reaction times and laser evoked potentials (LEPs) were examined. Signal detection theory analysis was performed to evaluate discrimination performance and decision criterion. During innocuous skin cooling, detection threshold increased from 4.8 − 1.81 to 8.2 − 1.05 mJ/mm2 and pain threshold from 8.7 − 1.53 to 13.5 − 1.57 mJ/mm2. proportion of detected stimuli decreased from 87% to 48% and pain reports from 42% to 10%. The well localized ‘pricking’ sensation mediated by Aδ‐nociceptors almost vanished. The intensity of sensations (VAS scores) was considerably reduced. Sensory discriminative performance was significantly depressed but decision criterion remained unchanged. Reaction times were delayed. The late‐LEPs, correlates of Aδ‐nociceptor activations, were also significantly depressed while the ultra‐late LEPs, correlates of C‐nociceptors, were not affected.

Taken together, these results strongly suggest that innocuous skin cooling interfered with the sensory processing of laser heat stimuli and more prominently with those related to Aδ‐nociceptive input.
Online Diaries: Towards a Structural Approach
Authors: SERFATY VIVIANE
Published: December 2004

Online diaries are at once thoroughly familiar and intensely new. Their publication on the Internet may be seen as upholding a long tradition in self-representational writing even as information technology modifies the forms and functions of such texts. Studying online diaries from a literary standpoint may therefore shed light on the development of new forms of writing, and contribute to assessing the extent of this transformation and its meaning. At the same time, viewing online diaries as primary sources may afford insight into the mores of ordinary people in contemporary America. Focusing on anonymous American diarists makes it possible to explore how this contemporary social practice reflects the transformations of the heartland in present-day America, how ordinary women and men, average Americans, make sense of their society and can be seen as representative of American culture, while at the same time engaging in the most personal kind of writing.
Hydrothermal exploration and astrobiology: oases for life in distant oceans?
Authors: German Christopher R.
Published: December 2004

High-temperature submarine hydrothermal fields on Earth's mid-ocean ridges play host to exotic ecosystems with fauna previously unknown to science. Because these systems draw significant energy from chemosynthesis rather than photosynthesis, it has been postulated that the study of such systems could have relevance to the origins of life and, hence, astrobiology. A major flaw to that argument, however, is that modern basalt-hosted submarine vents are too oxidizing and lack the abundant free hydrogen required to drive abiotic organic synthesis and/or the energy yielding reactions that the most primitive anaerobic thermophiles isolated from submarine vent-sites apparently require. Here, however, the progress over the past decade in which systematic search strategies have been used to identify previously overlooked venting on the slow-spreading Mid-Atlantic Ridge and the ultra-slow spreading Arctic and SW Indian Ridges is described. Preliminary identification of fault-controlled venting in a number of these sites has led to the discovery of at least two high-temperature hydrothermal fields hosted in ultramafic rocks which emit complex organic molecules in their greater than 360 °C vent-fluids. Whether these concentrations represent de novo organic synthesis within the hydrothermal cell remains open to debate but it is probable that many more such sites exist throughout the Atlantic, Arctic and SW Indian Oceans. One particularly intriguing example is the Gakkel Ridge, which crosses the floor of the Arctic Ocean. On-going collaborations between oceanographers and astrobiologists are actively seeking to develop a new class of free-swimming autonomous underwater vehicle, equipped with appropriate chemical sensors, to conduct long-range missions that will seek out, locate and investigate new sites of hydrothermal venting at the bottom of this, and other, ice-covered oceans.
On panspermia and the survivability of micrometre-sized meteoroids within the Earth's atmosphere
Authors: Coulson S.G.
Published: December 2004

A prediction of panspermia is that organic material should be abundant throughout the universe. The recovery of micrometre-sized biotic particles at altitudes of around 40 km above the Earth is a key indicator of the validity of panspermia. A common criticism of experiments to capture atmospheric particles is that the particles could have originated from the Earth. Theoretical models of the variation of temperature with altitude above the Earth show that 10 μm diameter particles can withstand rapid deceleration without significant ablation. Experimental evidence shows that small particles containing bacteria can survive the temperature regimes imposed by entry into the Earth's lower atmosphere. This is an important step in demonstrating that life on Earth did not evolve in isolation from the remainder of the universe.
Raman spectroscopy of senescing snow algae: pigmentation changes in an Antarctic cold desert extremophile
Authors: Edwards Howell G.M. , de Oliveira Luiz F.C. , Cockell Charles S. , Ellis-Evans J. Cynan , Wynn-Williams David D.
Published: December 2004

The FT-Raman spectra are described of green and red snow algae, Chlamydomona, involved in the colonization of exposed surfaces of the McLeod Glacier, Jane Col, Signy Island, situated at the northern edge of the Weddell Sea, Antarctica. The protective biochemicals produced by these extremophilic algae give rise to the so-called watermelon snow of Alpine regions. The red colour of the senescent algae is shown to derive from the accumulation of carotenoids and a deficiency of chlorophyll believed to arise from UV-radiation induced breakdown into phaecophytin. A comparison of the Raman spectra of young (green) and old (red) algae is effected and possible bio-markers for spectral detection on extraterrestrial icy moons and planets are identified.
Biologically–induced elemental variations in Antarctic sandstones: a potential test for Martian micro-organisms
Authors: Blackhurst Rebecca L. , Jarvis Kym , Grady Monica M.
Published: December 2004

Lichen-dominated cryptoendolithic communities from the Dry Valleys of Antarctica have been the subject of much research over recent years owing to their potential as analogues of Martian life forms. Their ability to mobilize iron compounds and organize themselves into distinct coloured biotic zones suggests that they may alter the chemistry of their host rock. By conducting a major, minor and trace element study utilizing inductively coupled plasma atomic emission spectroscopy (ICP-AES) and mass spectrometry (ICP-MS) techniques, we have been investigating the relationship between the microbes and the chemistry of the sandstones. Different layers within a suite of sandstones collected from six localities in the Dry Valleys have been analysed to establish if or how the microbes influence or directly affect the chemical composition of the rocks. Background petrographic studies have shown significant differences in mineralogical maturity between rocks colonized by the communities and those that are not, and the chemistry results have shown significant elemental disparity between colonized and uncolonized rocks. By obtaining accurate percentages of the minerals present in each sample the differences in elemental concentrations could be construed to be caused by the differences in mineralogy between samples. The nature and extent of the concentration differences has led to the conclusion that either the cryptoendolith communities are able to alter their host rock by the solubilization and mobilization of elements that are then subsequently removed or that the organisms are simple opportunists that can only successfully colonize rocks that provide the ideal substrate, being mineralogically mature with ample pore space and less concentrated in the elements tested for.
How do multiple environmental cycles in combination determine reproductive timing in marine organisms? A model and test
Authors: Yamahira K.
Published: December 2004

Each of the multiple environmental cycles – the light–dark, tidal, semilunar, lunar and seasonal cycles – may have an independent, specific effect on reproductive timings of marine organisms and can alone or in combination produce a variety of temporal reproductive patterns. Assuming that each ecological interaction with these fluctuating environmental cycles generates a unique functional relationship between a component of fitness and the timing of reproduction, a model is proposed that predicts that all fitness components are multiplicative and therefore the reproductive timing is entrained or driven by a cycle(s) having a sharp functional curve of the relevant fitness component.

According to this model, many of the reproductive patterns, ranging from diel to lunar, commonly seen in marine organisms were explained by changing relative kurtosis among functional curves of fitness components. Each curve could also differ in its optimum and skewness, making various intermediates and modifications possible.

As a model system for the model to be applied, intraspecific variation in the timing of spawning by a puffer, Takifugu niphobles (Jordan & Snyder) was examined. The patterns of daily variation in a day's spawning time within a population and geographical variation in spawning days among populations indicated that (1) the semilunar cycle (i.e. spring–neap tide cycle) has no direct influence on spawning days, (2) a combination between the functional curves of the fitness components associated with the light–dark and tidal cycles produce an apparent biweekly, semilunar spawning rhythm, (3) the curves may be skewed toward earlier and later times, respectively, and (4) their form may differ among populations.

This model approach argues that to understand the ecology and evolution of temporal patterns of reproduction, one must properly decouple and evaluate the form of the functional curve of a fitness component associated with each of the multiple environmental cycles.
Arsenic trioxide is effective in the treatment of multiple myeloma in SCID mice
Authors: Rousselot Philippe , Larghero Jérôme , Labaume Sylvaine , Poupon Joël , Chopin Martine , Dosquet Christine , Marolleau Jean‐Pierre , Janin Anne , Brouet Jean‐Claude , Fermand Jean‐Paul
Published: December 2004

Objectives : Pharmacological concentrations of arsenic trioxide (ATO) and organic arsenic melarsoprol induce apoptosis in malignant plasma cells. In an attempt to further document the interest of the arsenic in vivo, we treated severe combined immunodeficient (SCID) mice transplanted with human myeloma cells by ATO or melarsoprol.

Methods : Fifty‐two SCID mice were irradiated before intraperitoneal (i.p.) injection of plasma cells from five myeloma patients. Engraftment was assessed by serial measurement of the human monoclonal immunoglobulin G (HuMIgG) concentration in mouse serum. Treatment with ATO (10 μg/g i.p. 5 d a week), melarsoprol (30 μg/g i.p. 5 d a week) or phosphate buffer saline was started when a sustained growth of the tumor cells was demonstrated.

Results : Seventeen mice developed the human tumor. A significant decrease in HuMIgG amounts was observed in three of five mice of the ATO group, including two that achieved an apparent complete remission persisting up to 5 months after ATO discontinuation. In these mice, no human plasma cells were detected in tissue samples collected postmortem. Soluble human interleukin‐6 receptor amount, measured in mice sera as a surrogate marker of the plasma cell proliferation, varied in parallel with HuMIgG concentration. A significant difference in survival was observed between control and ATO treated mice (113 and 158 d, respectively; P = 0.01) whereas no difference could be evidenced in control and melarsoprol groups.

Conclusion : Present study confirms in vivo the in vitro effects of ATO on myeloma cells. Delayed relapses were observed suggesting that prolonged or maintenance therapy has to be considered in future clinical trials. Whether or not this will translate into clinically relevant effect of the drug in myeloma patients deserves further consideration.
Trends in clinical management of women with von Willebrand disease: a survey of 75 women enrolled in haemophilia treatment centres in the United States
Authors: Kirtava A , Crudder S , Dilley A , Lally C , Evatt B
Published: December 2004

Summary.  Objective:  To assess the management of women with von Willebrand disease( vWD) in an Heamophilia Treatment Center (HTC) setting.

Methods:  A total of 75 women with vWd who were registered in HTCs in the United States participated in this study. A telephone interview elicited information about symptoms pertaining to bleeding disorders, diagnostic issues, referral patterns, treatment modalities before and after the enrollment in the HTC, HTC services provided, and satisfaction with care in the HTC.

Results:  Menorrhagia was the most commonly reported symptom (84%). The average time from the first symptom until clinician recognition was 16 years (range 0‐39). In HTC, DDAVP was the most commonly used drug (31%). Of the 75 women, 71 reported a strong positive opinion and satisfaction about their care in the HTCs.

Discussion:  Women with VWD were typically diagnosed with the condition well into adulthood, in spite of the fact that majority of them experienced several bleeding symptoms beginning in early childhood. In general an HTC setting is appropriate for management of women with bleeding disorders. Diagnosis, treatment and education provided in the HTCs were viewed positively by those surveyed.
Nectin‐dependent localization of synaptic scaffolding molecule (S‐SCAM) at the puncta adherentia junctions formed between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the mouse hippocampus
Authors: Yamada Akio , Irie Kenji , Deguchi‐Tawarada Maki , Ohtsuka Toshihisa , Takai Yoshimi
Published: December 2004

Background:  Two types of intercellular junctions, synaptic junctions (SJs) and puncta adherentia junctions (PAs), are observed at the synapses between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the hippocampus. SJs are associated with active zones and postsynaptic densities (PSDs) where neurotransmission occurs, whereas PAs are not associated with either of them. We have found that the nectin‐afadin unit as well as the N‐cadherin‐catenin unit localizes at the PAs and that both the units cooperatively organize the PAs. Nectins are Ca2+‐independent Ig‐like cell‐cell adhesion molecules and afadin is a nectin‐ and actin filament‐binding protein that connects nectins to the actin cytoskeleton. Synaptic scaffolding molecule (S‐SCAM) is a neural scaffolding protein which interacts with many proteins including neuroligin, NMDA receptors, neural plakophilin‐related armadillo‐repeat protein/δ‐catenin, a GDP/GTP exchange protein for Rap1 small G protein (PDZ‐Rap‐GEP), and β‐catenin. S‐SCAM has been suggested to be a component of PSDs, but its precise localization at the synapses remains unknown.

Results:  S‐SCAM was not concentrated at the PSDs but highly concentrated and co‐localized with nectins at both the sides of the PAs formed between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the adult mouse hippocampus. S‐SCAM co‐localized with nectin‐1 at the primitive synapses where the SJs and the PAs were not morphologically differentiated, and they co‐localized during the maturation of the SJs and the PAs. Nectin‐1 had a potency to recruit S‐SCAM to the nectin‐1‐based cell‐cell adhesion sites formed in cadherin‐deficient L cells as a model system. This recruitment was dependent on the C‐terminal PDZ domain‐binding motif of nectin‐1 which is necessary for the binding of afadin, suggesting that nectins recruit S‐SCAM through afadin. Consistently, S‐SCAM was co‐immunoprecipitated with afadin by the anti‐S‐SCAM antibody from the mouse brain, but S‐SCAM did not directly bind afadin.

Conclusion:  These results indicate that S‐SCAM localizes at the PAs in the CA3 area of the hippocampus in a nectin‐dependent manner and suggest that S‐SCAM serves as a scaffolding molecule at the PAs after maturation of the synapses and at the SJs during the maturation.
The effects of the net fishery closure on angling catch in the River Hvítá, Iceland
Authors: Einarsson S. M. , Gudbergsson G.
Published: December 2004

Between 1991 and 2000, angling associations on the tributaries of the River Hvítá leased net fishery rights in the Hvítá mainstem, with the aim of eliminating net fishery harvest and improving the rod catch. The rod catch and net catch in the Hvítá system were significantly correlated (r = 0.94; P < 0.001) over the 10‐year period prior to (1981–1990) closure of the net fishery. The rod fishery in the tributaries of the River Hvítá was also significantly correlated to the rod fishery in selected groups of rivers in west (r = 0.80; P < 0.01) and north (r = 0.73; P < 0.05) before the closure. Significant increases (P < 0.01) were observed in rod catches in the Hvítá tributaries between 1991 and 2000 after the closure, while rod catches in control regions decreased. Based on evaluation of rod catch trends before and after the closure, it was estimated that the net fishery lease increased rod catches in the tributaries between 1773 and 2175 fish (28–35%). The increase in rod catches also suggested that the rod fishery may be taking 39–52% of the estimated previous net catch. The high price paid annually for the net fishery lease just to eliminate net fishing (€135 000) reflects the high value of rod caught salmon compared with salmon caught by the net fishery.
Lipids, buoyancy and the seasonal vertical migration of Calanus finmarchicus
Authors: Visser A.W. , Jónasdóttir S.H.
Published: December 2004

The copepod Calanus finmarchicus remains in diapause for up to 5 months in the cold (<0.5°C) deep (>700 m) waters of the Faroe–Shetland Channel of the north‐western approaches to the North Sea. While in diapause, C. finmarchicus has a high lipid content, up to 76% of dry weight, mostly in the form of wax esters. The question we address here is how copepods with such a high content of buoyant lipids can remain in diapause at depth for an extended period of time? The corollary to this is how this lipid content hinders and/or assists the copepods in their seasonal vertical migration? Part of the answer is due to the physical properties of wax esters. These have a thermal expansion and compressibility higher than that of sea water. Thus, depending on their relative composition (i.e. wax esters/water/protein/chitin), a copepod that is positively buoyant in warm surface waters can become neutrally buoyant in cold deep water. We develop a simple three component physical model of a copepod to explore how and where they attain neutral buoyancy, how the lipid content can aid in their ascent, and what fraction of the lipids can be utilized in ascent in gonad/egg formation while maintaining observed ascent rates. As well as being an energy reserve, the results show that rather than being a barrier to vertical migration, wax esters serve as an important regulator of buoyancy.
Climate fluctuations and the spring invasion of the North Sea by Calanus finmarchicus
Authors: Heath M.R. , Backhaus J.O. , Richardson K. , McKenzie E. , Slagstad D. , Beare D. , Dunn J. , Fraser J.G. , Gallego A. , Hainbucher D. , Hay S. , Jónasdóttir S. , Madden H. , Mardaljevic J. , Schacht A.
Published: December 2004

The population of Calanus finmarchicus in the North Sea is replenished each spring by invasion from an overwintering stock located beyond the shelf edge. A combination of field observations, statistical analysis of Continuous Plankton Recorder (CPR) data, and particle tracking model simulations, was used to investigate the processes involved in the cross‐shelf invasion. The results showed that the main source of overwintering animals entering the North Sea in the spring is at depths of greater than 600 m in the Faroe–Shetland Channel, where concentrations of up to 620 m−3 are found in association with the overflow of Norwegian Sea Deep Water (NSDW) across the Iceland–Scotland Ridge. The input of this water mass to the Faroe–Shetland Channel, and hence the supply of overwintering C. finmarchicus, has declined since the late 1960s due to changes in convective processes in the Greenland Sea. Beginning in February, animals start to emerge from the overwintering state and migrate to the surface waters, where their transport into the North Sea is mainly determined by the incidence of north‐westerly winds that have declined since the 1960s. Together, these two factors explain a high proportion of the 30‐year trends in spring abundance in the North Sea as measured by the CPR survey. Both the regional winds and the NSDW overflow are connected to the North Atlantic Oscillation Index (NAO), which is an atmospheric climate index, but with different time scales of response. Thus, interannual fluctuations in the NAO can cause immediate changes in the incidence of north‐westerly winds without leading to corresponding changes in C. finmarchicus abundance in the North Sea, because the NSDW overflow responds over longer (decadal) time scales.
Interannual variability of the ecosystem of the Kii Channel, the Inland Sea of Japan, as influenced by bottom intrusion of cold and nutrient‐rich water from the Pacific Ocean, and a recent trend of warming and oligotrophication
Authors: Ozaki Koji , Uye Shin‐Ichi , Kusumoto Teruichi , Hagino Tetsuo
Published: December 2004

Interannual variability of the ecosystem of the Kii Channel, productive shelf water on the Pacific side of south‐western Japan, was analysed based on physicochemical environmental variables and abundance of major zooplankton taxa collected monthly for 12 yr from 1987 to 1999. The Kii Channel experienced both short‐term (i.e. 3–4 yr) cyclical changes and a long‐term (i.e. decadal) environmental trend. The short‐term variability was primarily associated with year‐to‐year differences in intrusion of subsurface, cold nutrient‐rich water along the bottom of the Kii Channel from the Pacific Ocean. When this bottom intrusion was intense, the Kii Channel experienced a cold, new production‐dominated ecosystem. The bottom intrusion, however, has become less intense in recent years, because of the closer proximity of the Kuroshio flow axis to the Kii Channel. Hence, there was a consistent trend towards warming and a regenerated production‐dominated ecosystem. In accordance with such environmental changes, the zooplankton community shifted towards more oceanic conditions; major herbivorous calanoids (i.e. Calanus sinicus, Paracalanus parvus (s.l.), Clausocalanus spp. and Acartia omorii) decreased, while carnivores (i.e. hydromedusae and Sagitta spp.) increased. The amount of total fish catch also decreased, while the catch of subtropical species increased. These findings lead us to conclude that the bottom intrusion from the Pacific Ocean plays a key role in determining the biological production in the Kii Channel.
Late winter larval mesopelagic fish assemblage in the Kuroshio waters of the western North Pacific
Authors: Sassa Chiyuki , Kawaguchi Kouichi , Mori Ken
Published: December 2004

The larval mesopelagic fish assemblage and its distribution patterns were investigated in the Kuroshio region off southern Japan in late winter. A total of 8690 fish larvae was collected, 85.8% of which were mesopelagic fish larvae. Mesopelagic fish larvae were significantly more abundant in the area east of the Kuroshio axis than west of the Kuroshio axis (660.6 versus 194.5 ind 10 m−2). Sigmops gracile, Bathylagus ochotensis, Notoscopelus japonicus, Diaphus slender type and Myctophum asperum were the five most abundant larvae and accounted for 16.9, 16.4, 15.2, 13.9 and 9.3% of the total catch in numbers, respectively. We conclude that these larvae were transported by the Kuroshio Current to the more productive transition waters, where they spend their juvenile stage from spring to early summer. The possibility of expatriation and southward long‐distance spawning migrations of N. japonicus and B. ochotensis are discussed, based on the geographic distribution patterns of their larvae, juveniles and adults.
Impact of freshwater input and wind on landings of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in shelf waters surrounding the Ebre (Ebro) River delta (north‐western Mediterranean)
Authors: Lloret J. , Palomera I. , Salat J. , Sole I.
Published: December 2004

Time series analyses (Box–Jenkins models) were used to study the influence of river runoff and wind mixing index on the productivity of the two most abundant species of small pelagic fish exploited in waters surrounding the Ebre (Ebro) River continental shelf (north‐western Mediterranean): anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus). River flow and wind were selected because they are known to enhance fertilization and local planktonic production, thus being crucial for the survival of fish larvae. Time series of the two environmental variables and landings of the two species were analysed to extract the trend and seasonality. All series displayed important seasonal and interannual fluctuations. In the long term, landings of anchovy declined while those of sardine increased. At the seasonal scale, landings of anchovy peaked during spring/summer while those of sardine peaked during spring and autumn. Seasonality in landings of anchovy was stronger than in sardine. Concerning the environmental series, monthly average Ebre runoff showed a progressive decline from 1960 until the late 1980s, and the wind mixing index was highest during 1994–96. Within the annual cycle, the minimum river flow occurs from July to October and the wind mixing peaks in winter (December–April, excluding January). The results of the analyses showed a significant correlation between monthly landings of anchovy and freshwater input of the Ebre River during the spawning season of this species (April–August), with a time lag of 12 months. In contrast, monthly landings of sardine were significantly positively correlated with the wind mixing index during the spawning season of this species (November–March), with a lag of 18 months. The results provide evidence of the influence of riverine inputs and wind mixing on the productivity of small pelagic fish in the north‐western Mediterranean. The time lags obtained in the relationships stress the importance of river runoff and wind mixing for the early stages of anchovy and sardine, respectively, and their impact on recruitment.
Effects of sediment resuspension on phytoplankton production: teasing apart the influences of light, nutrients and algal entrainment
Authors: Schallenberg Marc , Burns Carolyn W.
Published: December 2004

1. Wind‐induced sediment resuspension can affect planktonic primary productivity by influencing light penetration and nutrient availability, and by contributing meroplankton (algae resuspended from the lake bed) to the water column. We established relationships between sediment resuspension, light and nutrient availability to phytoplankton in a shallow lake on four occasions.

2. The effects of additions of surficial sediments and nutrients on the productivity of phytoplankton communities were measured in 300 mL gas‐tight bottles attached to rotating plankton wheels and exposed to a light gradient, in 24 h incubations at in situ temperatures.

3. While sediment resuspension always increased primary productivity, resuspension released phytoplankton from nutrient limitation in only two of the four experiments because the amount of available nitrogen and phosphorus entrained from the sediments was small compared with typical baseline levels in the water column. In contrast, chlorophyll a entrainment was substantial compared with baseline water column concentrations and the contribution of meroplankton to primary production was important at times, especially when seasonal irradiance in the lake was high.

4. Comparison of the in situ light climate with the threshold of light‐limitation of the phytoplankton indicated that phytoplankton in the lake were only likely to be light‐limited at times of extreme turbidity (e.g. >200 nephelometric turbidity units), particularly when these occur in winter. Therefore, resuspension influenced phytoplankton production mainly via effects on available nutrients and by entraining algae. The importance of each of these varied in time.

5. The partitioning of primary productivity between the water column and sediments in shallow lakes greatly influences the outcome of resuspension events for water column primary productivity.
Mechanisms regulating zooplankton populations in a high‐mountain lake
Authors: Winder Monika , Bürgi Hans Rudolf , Spaak Piet
Published: December 2004

SUMMARY 1. We studied the seasonal succession of phyto‐ and zooplankton and the potential impact of predation by salmonids on zooplankton population dynamics in a high‐mountain Swiss lake.

2. A comparison of patterns in the abundance, body length, fecundity and age structure in the Daphnia galeata population strongly suggests that trout predation had little impact on the population and was not the cause for a decline in summer.

3. The dominance in the lake of adult trout that feed mainly on benthic prey may buffer the effect of predation on the larger zooplankton. Further, the relatively high amount of phytoplankton after spring thaw could be important for sustaining the Daphnia population under moderate fish predation.

4. Partial correlation analyses proved circumstantial evidence for both exploitative and interference competition between some zooplankton taxa. D. galeata depressed performance of other plankton species through exploitative competition.

5. Our study shows that the impact of fish on zooplankton in high‐mountain lakes depends strongly on food web structure and trophic state of the lake. Where fish predation is weak, invertebrate predation combined with competition for food may be responsible for the dominance of large‐bodied zooplankton species.
Marked recent increases of colonial scaled chrysophytes in boreal lakes: implications for the management of taste and odour events
Authors: Paterson Andrew M. , Cumming Brian F. , Smol John P. , Hall Roland I.
Published: December 2004

1. Lake managers suspect that taste and odour‐causing algal blooms are increasing in frequency and intensity, although long‐term monitoring records are scarce, and a number of critical scientific and management questions remain unanswered.

2. In nutrient‐poor lakes and reservoirs, these events are caused primarily by sporadic outbreaks of some chrysophyte algae, which leave identifiable markers in lake sediments. We examine the siliceous remains of these organisms in more than fifty boreal lakes at broad temporal and spatial scales.

3. Colonial scaled chrysophytes, including the taste and odour‐causing Synura petersenii, have increased markedly in more that 90% of the lakes examined since pre‐industrial times.

4. Detailed stratigraphic analyses of two lakes show a rise in the abundance of colonial taxa in the 1930s to 1950s, with a sharp increase over the past two decades.

5. An examination of biogenic silica and biological ratios in Crosson Lake, Ontario, Canada, indicate that these changes represent true increases in the absolute abundance of colonial chrysophytes.

6. Rapid increases over the past two decades indicate that these trends are the result of one or more anthropogenic stressors that are operating at a broad, regional scale.
Strategic size changes of internal organs and muscle tissue in the Bar‐tailed Godwit during fat storage on a spring stopover site
Authors: Landys‐Ciannelli M. M. , Piersma T. , Jukema J.
Published: December 2004

In several migrant bird species it has now been established that refuelling is typified not only by fat deposition, but also by changes in lean body protein. The body composition of a long‐distance migratory shorebird, the Bar‐tailed Godwit Limosa lapponica taymyrensis, was examined on a stopover site in spring to evaluate changes in lean dry mass of organ and muscle tissue over the period of refuelling.

It was hypothesized that tissues which support long‐distance flight would hypertrophy and reach peak size towards the end of refuelling, i.e. immediately before the 4500‐km bout of flight to Arctic breeding grounds. In contrast, it was hypothesized that tissues involved in digestion would initially hypertrophy, but then atrophy during the final stages of stopover, so that wing loading during long‐distance flight would be minimized.

Flight muscles of godwits steadily increased in lean dry mass during refuelling and reached peak size in birds preparing to depart the stopover site – possibly in an effort to maximize power output.

In contrast, the lean dry mass of stomach, liver, kidneys and intestines of godwits increased only during the early stages of refuelling, indicating a quick initial growth of organs involved in the support of refuelling activities. Additionally, in birds readying for departure, the intestines no longer differed in size from those of recent arrivals, suggesting a reduction in size of digestive tissues prior to flight.

Such changes in body composition appear consistent with those found in another shorebird and in a grebe preparing for a bout of migratory flight, suggesting a common pattern in allocation of lean body mass in at least some migratory species during fuelling.
The implications of food hardness for diet in bats
Authors: Aguirre L. F. , Herrel A. , Van Damme R. , MatThysen E.
Published: December 2004

Neotropical bat communities are characterized by a broad species diversity, which can be achieved and maintained only through partitioning of the available resources.

Here patterns of trophic resource utilization within a single neotropical savanna bat community are investigated. Moreover, the physical properties of food items (i.e. hardness), its variation with food size, and whether food hardness differs between items consumed by the bats in this community are investigated experimentally.

The results show that food hardness increases with the size of the food item, and that distinct differences exist in the amount of force needed to crush different food items (beetles vs other insects vs fruits).

Using previously published data on bite forces from species in the same community it is explored whether food hardness may play a role in shaping the diets of the bats in the community. The combined data on bite forces and food hardness indicate that food hardness can both directly and indirectly limit dietary diversity in bats.

The results also indicate that dietary specialization may potentially result in a decrease in trophic breadth for some species through its effect on bite performance.
A forensic approach to understanding diet and habitat use from stable isotope analysis of (avian) claw material
Authors: Bearhop S. , Furness R. W. , Hilton G. M. , Votier S. C. , Waldron S.
Published: December 2004

The potential of using stable isotope signatures of avian claws in order to infer diet and habitat use was investigated.

Highly significant relationships observed between stable carbon and nitrogen isotope ratios (δ13C, δ15N) in the claws and body feathers of resident birds were expected since it was predicted that they were synthesized in the same habitat and approximately the same time of year.

Likewise the non‐significant relationships observed between δ13C and δ15N in the claws and tertial feathers of neotropical migrant birds were also predicted since the claws were synthesized in the wintering area and the tertials in the breeding area.

The growth rates measured in the claws of five species of palearctic passerines provide evidence that this tissue should integrate dietary and habitat information over a medium temporal scale (probably weeks to months).

It is suggested that claws may offer a unique combination of attributes to the isotope ecologist: they are non‐invasively sampled; metabolically inert but grow continuously, and are therefore a more flexible tool than feathers.

It is also suggested that that the stable isotope signatures in the claws of mammals and reptiles may provide similar information.
Variation in coral photosynthesis, respiration and growth characteristics in contrasting light microhabitats: an analogue to plants in forest gaps and understoreys?
Authors: Anthony K. R. N. , Hoegh‐Guldberg O.
Published: December 2004

The often complex architecture of coral reefs forms a diversity of light microhabitats. Analogous to patterns in forest plants, light variation may drive strategies for efficient light utilization and metabolism in corals.

We investigated the spatial distribution of light regimes in a spur‐and‐groove reef environment and examine the photophysiology of the coral Montipora monasteriata (Forskål 1775), a species with a wide habitat distribution. Specifically, we examined the variation in tissue and skeletal thickness, and photosynthetic and metabolic responses among contrasting light microhabitats.

Daily irradiances reaching corals in caves and under overhangs were 1–5 and 30–40% of those in open habitats at similar depth (3–5 m), respectively. Daily rates of net photosynthesis of corals in cave habitats approximated zero, suggesting more than two orders of magnitude variation in scope for growth across habitats.

Three mechanisms of photoadaptation or acclimation were observed in cave and overhang habitats: (1) a 20–50% thinner tissue layer and 40–60% thinner skeletal plates, maximizing light interception per unit mass; (2) a two‐ to threefold higher photosynthetic efficiency per unit biomass; and (3) low rates of dark respiration.

Specimens from open and cave habitats displayed a high capacity to acclimate to downshifts or upshifts in irradiance, respectively. However, specimens in caves displayed limited acclimation to further irradiance reduction, indicating that these live near their irradiance limit.

Analogous to patterns for some plant species in forest gaps, the morphological plasticity and physiological flexibility of M. monasteriata enable it to occupy light habitats that vary by more than two orders of magnitude.
Mammalian Mcm2/4/6/7 complex forms a toroidal structure
Authors: Yabuta Norikazu , Kajimura Naoko , Mayanagi Kouta , Sato Michio , Gotow Takahito , Uchiyama Yasuo , Ishimi Yukio , Nojima Hiroshi
Published: December 2004

Background: The Mcm proteins are a family of six homologous proteins (Mcm2–7) that play an important role in DNA replication. They form Mcm4/6/7 and Mcm2/4/6/7 complexes, but their structures are not known.

Results: We found that the human Mcm2/4/6/7 tetramer forms a toroidal structure, with a central cavity about 3–4 nm in diameter. Observations were made using electron microscopy, employing the image analysis of single particles. The most predominant averaged image displayed a toroid harbouring four bulges forming corners, one of which was larger than the others. This structure was very similar to the mouse Mcm2/4/6/7 tetramer that was independently prepared and analysed by electron microscopy. These toroidal structures are distinct from that of the Mcm4/6/7 hexamer, which was also examined by electron microscopy. GST(glutathione S‐transferase)‐pull down and two hybrid experiments suggest that a putative Mcm6‐Mcm6 hinge contributes to the formation of the Mcm7/4/6/6/4/7 heterohexamer.

Conclusions: The Mcm2/4/6/7 tetramer forms a toroidal structure that is distinct from that of the Mcm4/6/7 hexamer in size and shape.
Suppression of spontaneous and hydrogen peroxide‐induced mutations by a MutT‐type nucleotide pool sanitization enzyme, the Escherichia coli Orf135 protein
Authors: Kamiya Hiroyuki , Iida Emiko , Murata‐Kamiya Naoko , Yamamoto Yoshihiro , Miki Takeyoshi , Harashima Hideyoshi
Published: December 2004

Background:  We recently found that the Escherichia coli Orf135 protein, a MutT‐type enzyme, hydrolysed 2‐hydroxy‐dATP (2‐OH‐dATP), and less efficiently, 8‐hydroxy‐dGTP.

Results:  In this study, we examined the effects of the absence of the orf135 gene. Frequencies of spontaneous and H2O2‐induced mutations were two‐ to three‐fold higher in the orf135‐ strain than in the wild‐type strain. These mutations include various mutations involving a G:C→T:A transversion, the same type of mutation elicited by 2‐OH‐dATP. Over‐expression of the Orf135 protein suppressed mutations even in the wild‐type strain, as well as in the orf135‐ strain.

Conclusions:  The mutator phenotype of bacteria lacking the Orf135 protein suggests that this protein is involved in the suppression of mutations induced by oxidized deoxynucleotides in vivo and that various MutT‐type enzymes contribute to nucleotide pool sanitization.
Modelling of GPR waves for lossy media obeying a complex power law of frequency for dielectric permittivity
Authors: Bano Maksim
Published: December 2004

The attenuation of ground‐penetrating radar (GPR) energy in the subsurface decreases and shifts the amplitude spectrum of the radar pulse to lower frequencies (absorption) with increasing traveltime and causes also a distortion of wavelet phase (dispersion). The attenuation is often expressed by the quality factor Q. For GPR studies, Q can be estimated from the ratio of the real part to the imaginary part of the dielectric permittivity.

We consider a complex power function of frequency for the dielectric permittivity, and show that this dielectric response corresponds to a frequency‐independent‐Q or simply a constant‐Q model. The phase velocity (dispersion relationship) and the absorption coefficient of electromagnetic waves also obey a frequency power law. This approach is easy to use in the frequency domain and the wave propagation can be described by two parameters only, for example Q and the phase velocity at an arbitrary reference frequency. This simplicity makes it practical for any inversion technique. Furthermore, by using the Hilbert transform relating the velocity and the absorption coefficient (which obeys a frequency power law), we find the same dispersion relationship for the phase velocity. Both approaches are valid for a constant value of Q over a restricted frequency‐bandwidth, and are applicable in a material that is assumed to have no instantaneous dielectric response.

Many GPR profiles acquired in a dry aeolian environment have shown a strong reflectivity inside dunes. Changes in water content are believed to be the origin of this reflectivity. We model the radar reflections from the bottom of a dry aeolian dune using the 1D wavelet modelling method. We discuss the choice of the reference wavelet in this modelling approach. A trial‐and‐error match of modelled and observed data was performed to estimate the optimum set of parameters characterizing the materials composing the site. Additionally, by combining the complex refractive index method (CRIM) and/or Topp equations for the bulk permittivity (dielectric constant) of moist sandy soils with a frequency power law for the dielectric response, we introduce them into the expression for the reflection coefficient. Using this method, we can estimate the water content and explain its effect on the reflection coefficient and on wavelet modelling.
Canopy duration has little influence on annual carbon storage in the deciduous broad leaf forest
Authors: WHITE MICHAEL A. , NEMANI RAMAKRISHNA R.
Published: December 2004

Vegetation phenology, the study of the timing and length of the terrestrial growing season and its connection to climate, is increasingly important in integrated Earth system science. Phenological variability is an excellent barometer of short‐ and long‐term climatic variability, strongly influences surface meteorology, and may influence the carbon cycle. Here, using the 1895–1993 Vegetation/Ecosystem Modelling and Analysis dataset and the Biome‐BGC terrestrial ecosystem model, we investigated the relationship between phenological metrics and annual net ecosystem exchange (NEE) of carbon. For the 1167 deciduous broad leaf forest pixels, we found that NEE was extremely weakly related to canopy duration (days from leaf appearance to complete leaf fall). Longer canopy duration, did, however, sequester more carbon if warm season precipitation was above average. Carbon uptake period (number of days with net CO2 uptake from the atmosphere), which integrates the influence of all ecosystem states and processes, was strongly related to NEE. Results from the Harvard Forest eddy‐covariance site supported our findings. Such dramatically different results from two definitions of ‘growing season length’ highlight the potential for confusion among the many disciplines engaged in phenological research.
Climatic effects on litter decomposition from arctic tundra to tropical rainforest
Authors: LISKI JARI , NISSINEN ARI , ERHARD MARKUS , TASKINEN OLLI
Published: December 2004

Climatic effects on the decomposition rates of various litter types in different environments must be known to predict how climatic changes would affect key functions of terrestrial ecosystems, such as nutrient and carbon cycling and plant growth. We developed regression models of the climatic effects on the first‐year mass loss of Scots pine needle litter in boreal and temperate forests across Europe (34 sites), and tested the applicability of these models for other litter types in different ecosystems from arctic tundra to tropical rainforest in Canada (average three year mass loss of 11 litter types at 18 sites), the USA and Central America (four litter types at 26 sites).

A temperature variable (annual mean temperature, effective temperature sum or its logarithm) combined with a summer drought indicator (precipitation minus potential evapotranspiration between May and September) explained the first‐year mass loss of the Scots pine needle litter across Europe with a higher R2 value than actual evapotranspiration (0.68–0.74 vs. 0.51) and with less systematic error for any sub‐region. The model with temperature sum and the summer drought indicator appeared best suited to the other litter types and environments. It predicted the climatic effects on the decomposition rates in North and Central America with least systematic error and highest R2 values (0.72–0.80). Compared with Europe, the decomposition rate was significantly less sensitive to annual mean temperature in Canada, and to changes in actual evapotranspiration in the USA and Central America.

A simple model distinguishing temperature and drought effects was able to explain the majority of climatic effects on the decomposition rates of the various litter types tested in the varying environments over the large geographical areas. Actual evapotranspiration summarizing the temperature and drought effects was not as general climatic predictor of the decomposition rate.