bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of glacial cycles and tectonics on natural subsidence in the Po Plain (Northern Italy): Insights from 14C ages
Authors: Carminati E. , Martinelli G. , Severi P.
Published: October 2003

Samples rich in organic matter were collected from boreholes in the southern part of the Po Plain (Italy), a rapidly subsiding sedimentary basin. New 14C dates, obtained from these samples, and 14C data from the literature allowed for the evaluation of the rates of natural subsidence in the area. These range from 0 to 5 mm/yr. Most areas show rates around 1 and 2 mm/yr. The obtained subsidence rates are comparable with burial rates obtained from archaeological data. These data are interpreted in terms of long‐term (related to tectonics and geodynamics) and short‐term (glacial cycle) processes. It is concluded that approximately 50% of the subsidence rates are related to tectonics, geodynamics and sediment load/compaction while the other half is controlled by ice melting. The effects of the glacial cycle through time are discussed. It is shown that the southeastern Po Plain generally behaves as a far‐field area in relation to the high‐latitude ice caps. Deviations from this behavior observed in the northeastern part of the Po Plain are tentatively interpreted as the effects of ice formation and melting in the Alps during the last glacial cycle.
Field comparison of network Sun photometers
Authors: McArthur L. J. Bruce , Halliwell David H. , Niebergall Ormanda J. , O'Neill Norm T. , Slusser James R. , Wehrli Christoph
Published: October 2003

Measurements of aerosol optical depth have become more numerous since the mid‐1990s with the onset of commercially available, high‐quality, low‐maintenance automatic instrumentation. The development of several networks for aerosol measurements, and the next day availability of preliminary data for some, have further enhanced interest in the products this type of measurement can provide. With several networks operating globally and others operating either regionally or continentally within North America the comparability of the data emanating from the various archive centers is an important issue. The Bratt's Lake Observatory operates four separate types of Sun photometers in conjunction with three different networks: Aerosols in Canada, Global Atmosphere Watch, and the U.S. Department of Agriculture UV‐B Monitoring Program. Data collected during the summer of 2001, following the protocols established by the networks and the Meteorological Service of Canada, were analyzed to determine the comparability among these networks. As the instruments and conversion algorithms are similar to other networks from around the globe, it is believed that the results of this comparison can be transferred, at least in part, to other operational networks. The results of the 3‐month study indicate that the data obtained from the networks that operate direct‐pointing instruments are very comparable, being within ±0.01 of an optical depth for instantaneous measurements during cloud‐free line‐of‐sight conditions. Over the length of the comparison the root mean square difference of aerosol optical depth at 500 nm between the direct sun‐pointing instruments was 0.0069. The rotating shadowband instruments did not perform as well. These results indicate that the data from well‐maintained networks of direct sun‐pointing photometers can provide data of the quality necessary to compare stations from across the globe.
Neogene to ongoing normal faulting in the inner western Alps: A major evolution of the late alpine tectonics
Authors: Sue Christian , Tricart Pierre
Published: October 2003

Widespread brittle extension occurs in the internal zones of the southwestern Alps, forming a dense fault network, which overprints the compressional structures. The extension has been followed by transcurrent motions. In terms of paleostress this extension is radial to the belt close to the Crustal Penninic Front and multidirectional in the eastern part of the internal zones. The paleostress field of the strike‐slip phase is coherent with the extensional one and compatible with dextral shear along longitudinal faults. Globally, we propose that the internal zones of the southwestern Alps underwent a single Neogene transtensive tectonic regime. To strengthen our structural results, the current tectonics has been analyzed using seismotectonic tools. This approach allowed the recognition of several active faults. Moreover, the ongoing tectonics is coherent with the observed brittle deformation. The fault network controls the present‐day seismicity. The combined seismotectonic and structural approaches give coherency and continuity from the Neogene to ongoing extensional tectonics in the southwestern Alps. In the framework of the whole western Alps a synthesis of our results with neotectonic‐related data allowed us to provide an accurate map of the Neogene to present kinematics of the belt. Extension, which appears as a major feature of the internal zones, has been coeval with the propagation of thrusts in the outer zones during Neogene times. The geodynamic processes, which rule this major tectonic evolution of the belt, remain a matter of debate.
The Paleozoic to Mesozoic carbon cycle revisited: The carbon isotopic composition of terrestrial organic matter
Authors: Strauss Harald , Peters‐Kottig Wolfgang
Published: October 2003

Two thousand one hundred forty‐eight carbon isotope values for terrestrial organic matter (plant fossils, coal, bulk terrestrial organic matter) provide a proxy record for temporal changes in the global carbon cycle. δ13CTOM, δ13Ccarb, and δ13CCO2 allow a full evaluation of carbon transfer in the atmosphere‐ocean system as well as between the marine and the terrestrial realm. The temporal evolution of δ13CTOM parallels respective data sets from marine carbonate carbon, thus reflecting the linkage between both reservoirs via atmospheric carbon dioxide. On the basis of a comparison between measured and predicted isotope records for δ13CTOM, changes in the carbon isotopic fractionation associated with plant metabolism are discernible. This contradicts the notion of an invariable carbon isotopic fractionation associated with C3 plant metabolism. In light of results from current plant growth experiments, these changes are viewed as dependent on the atmospheric O2/CO2. Hence δ13CTOM might serve as a proxy signal for atmospheric composition.
Near surface westerly wind jet in the Atlantic ITCZ
Authors: Grodsky Semyon A. , Carton James A. , Nigam Sumant
Published: October 2003

A suite of satellite data are used to study the near surface westerly winds developing during peak months (July–September) of the West African monsoon in the Atlantic Intertropical Convergence Zone. These new data show that the westerlies appear in the form of a westerly jet. During peak years the daily near‐surface westerly wind speed may exceed 10 ms−1. The amplitude of the jet displays substantial decadal and interannual variability that corresponds to rainfall in the West African Sahel and the frequency of African Easterly Waves. Observations and ocean model simulations show that the jet acts to cool SST through entrainment and latent heat loss and to intensify the North Equatorial Countercurrent by increasing the southward oceanic pressure gradient.
Cloud‐to‐ground lightning enhancement over Southern Louisiana
Authors: Steiger Scott M. , Orville Richard E.
Published: October 2003

Fourteen years (1989–2002) of cloud‐to‐ground (CG) lightning data show a significant enhancement of lightning associated with Lake Charles and Baton Rouge, Louisiana. A peak density value of 7 flashes km−2 yr−1 exists on the western side of the Lake Charles urban area. A comparison of the Louisiana CG flash density distribution with the locations of PM10 (particulate matter less than 10 μm in diameter) sources strongly suggests that pollution plays a key role in lightning enhancement. Urban and sea breeze effects can be neglected. The values of median peak negative current show a sharp difference between land and the Gulf of Mexico; inland values are near 24 kA, while over the Gulf waters immediately offshore are over 30 kA. This observation, along with a relative minimum of negative peak current from the mouth of the Mississippi River southeastward seems to support the hypothesis that the underlying surface characteristics influence the calculated negative current distribution.
Relating pore fabric geometry to acoustic and permeability anisotropy in Crab Orchard Sandstone: A laboratory study using magnetic ferrofluid
Authors: Benson Philip M. , Meredith Philip G. , Platzman Ellen S.
Published: October 2003

Pore fabric anisotropy is a common feature of many sedimentary rocks. In this paper we report results from a comparative study on the anisotropy of a porous sandstone (Crab Orchard) using anisotropy of magnetic susceptibility (AMS), acoustic wave velocity and fluid permeability techniques. Initially, we characterise the anisotropic pore fabric geometry by impregnating the sandstone with magnetic ferro‐fluid and measuring its AMS. The results are used to guide subsequent measurements of the anisotropy of acoustic wave velocity and fluid permeability. These three independent measures of anisotropy are then directly compared. Results show strong positive correlation between the principal directions given from the AMS, velocity anisotropy and permeability anisotropy. Permeability parallel to the macroscopic crossbedding observed in the sandstone is 240% higher than that normal to it. P and S‐wave velocity anisotropy and AMS show mean values of 19.1%, 4.8% and 3.8% respectively, reflecting the disparate physical properties measured.
NAO impact towards the springtime snow disappearance in the western Eurasian continent
Authors: Hori M. E. , Yasunari T.
Published: October 2003

The atmospheric control over the disappearance of snow in western Eurasia and its relationship to the North Atlantic Oscillation (NAO) are investigated. While the NAO has a strong effect on the lower tropospheric temperature in the region, its ability to force control over the snow extent is confined to western Europe in January and February. Successive composite differences and heat budget analysis reveals a northeastward propagation of snow cover anomaly maintained by an anomalous zonal heat advection related to the NAO from January to March, and the intrusion of warm climatological southerly maintaining the snow anomaly until April.
Measures of resolution in global body wave tomography
Authors: Boschi L.
Published: October 2003

The resolution of tomographic images is most often evaluated through synthetic tests: the inversion algorithm used to derive the image itself is applied to a synthetic data set having the same source‐station geometry of the real one, but theoretical travel times computed from a chosen “input model” (e.g., a checkerboard). The similarity between input model and solution of the synthetic test, used as a measure of resolution, has the major shortcoming of depending on the choice of the input model. Conversely, the similarity of the “model resolution matrix” to the identity matrix is a rigorous measure of resolution that does not depend on any input model, but has the drawback of being computationally heavy. In the past decade, several authors have devised complicated algorithms for the approximate or iterative derivation of . I show here that parallel Cholesky factorization of ( being the matrix that identifies the linear inverse problem), feasible on shared‐memory multiprocessor servers, provides an efficient way of determining both least squares solutions and resolution matrices in global tomography. I apply this procedure in an evaluation of the resolution of mantle structure from a global P‐wave travel time data set.
Evidence for an additional Heinrich event between H5 and H6 in the Labrador Sea
Authors: Rashid Harunur , Hesse Reinhard , Piper David J. W.
Published: October 2003

An additional Heinrich ice‐rafting event is identified between Heinrich events 5 and 6 in eight cores from the Labrador Sea and the northwest Atlantic Ocean. It is characterized by sediment rich in detrital carbonate (40% CaCO3) with high concentration of floating dropstones, high coarse‐fraction (% > 150 μm) content, and has a sharp contact with the underlying but grades into the overlying hemipelagic sediment. It also shows lighter δ18ONpl values, indicating freshening due to iceberg rafting and/or meltwater discharge. This event is correlated with Dansgaard‐Oeschger event 14 and interpreted as an additional Heinrich event, H5a. The thickness of H5a in the Labrador Sea reaches up to 220 cm. This additional Heinrich event has also been reported in cores PS2644 and SO82‐5 from the northern North Atlantic. With the recognition of H5a the temporal spacing between Heinrich events 1 to 6 becomes more uniform (∼7 ka).
Which abiotic factors limit vegetative growth in a vascular epiphyte?
Authors: Laube S. , Zotz G.
Published: October 2003

Vegetative growth in vascular epiphytes is assumed to be severely limited by intermittent supply of water and nutrients, but experimental evidence for this notion is meagre. The effects of water, nutrient supply and light on growth were studied in an epiphytic bromeliad, Vriesea sanguinolenta Cogn. & Marchal (syn. Werauhia sanguinolenta) in a large forest gap in a lowland forest of Panama, in a full‐factorial design. To investigate ontogenetic drift, three plant‐size classes (≈5, 15 and 35 cm leaf length) were included in the experiment.

Water supply had the strongest influence on growth, but the magnitude of this effect differed considerably among size classes. Nutrient supply affected growth only in small and intermediate‐sized plants. More light (60% of direct irradiation) tended to decrease growth rates compared to 30% irradiation.

Small plants showed by far the highest potential to adjust their relative growth rate (RGR) in response to favourable growing conditions.

Despite these size‐related differences, absolute RGRs were extremely low compared to studies with other plant groups, confirming the notion that vascular epiphytes are inherently slow‐growing plants.
Environmental, genetic, and seed mass effects on winged seed production in the heteromorphic Spergularia marina (Caryophyllaceae)
Authors: Mazer S. J. , Lowry D. E.
Published: October 2003

Spergularia marina (L.) Grieseb. is a cosmopolitan, autogamous herb that produces winged and unwinged seeds. In Europe, large‐seeded populations tend to produce a higher proportion of winged seeds than small‐seeded populations.

This pattern has prompted speculation that winged seeds evolved because they increase the dispersability of large‐seeded genotypes. Alternatively, winged seed production may be an adaptive plastic response to stress, resulting in increased dispersal. A third hypothesis is that wing production is favoured among maternal plants with high fecundity because it reduces postdispersal sibling competition.

We present the results of a greenhouse experiment conducted to test these hypotheses using California genotypes of S. marina. Twenty‐four maternal families (N = 230 plants) were replicated across three nutrient treatments. Within treatments, large‐seeded fruits, individuals and families tended to produce a higher proportion of winged seeds than small‐seeded ones. We found no evidence that winged seeds are induced by stress or high fecundity.

These results are consistent with evidence that winged seed production in S. marina is positively associated with the evolution of mean seed mass, representing an adaptation that enhances the dispersability of large seeds. The low frequency of winged seeds in the population sampled here suggests that the heteromorphism may not be an important current adaptation in small‐seeded populations of S. marina.
Hydraulic lift in a neotropical savanna
Authors: Moreira M. Z. , Scholz F. G. , Bucci S. J. , Sternberg L. S. , Goldstein G. , Meinzer F. C. , Franco A. C.
Published: October 2003

We report hydraulic lift in the savanna vegetation of central Brazil (Cerrado). Both heat‐pulse measurements and isotopic (deuterium) labelling were used to determine whether hydraulic lift occurred in two common species, and whether neighbouring small shrubs and trees were utilizing this water.

Both techniques showed water uptake by tap‐roots and reverse flow of water in lateral roots. Roots transferred hydraulically lifted water to the soil, and small shrubs and trees neighbouring the labelled individuals were labelled by deuterated water.

Isotopic mass‐balance equations and sap‐flow measurements showed that water taken up by the central tap‐root in each individual constituted only a small percentage of total flux of water through the treated plants. Mass‐balance equations also indicated that small shrubs and trees neighbouring the treated plants utilized only a few thousandths of a per cent of the label.

The small proportion of water uptake by the tap‐root of these two species may be limiting hydraulic lift in this system, unless sinker roots descending from lateral roots contribute to hydraulic lift.
Parental foraging effort and offspring growth in Adélie Penguins: does working hard improve reproductive success?
Authors: Takahashi A. , Watanuki Y. , Sato K. , Kato A. , Arai N. , Nishikawa J. , Naito Y.
Published: October 2003

Studying variability of parental foraging and provisioning behaviour in relation to reproductive success is fundamental to improving understanding of regulation of reproductive effort in animals. The hypothesis that parents with higher foraging effort have higher offspring growth rates was tested in chick‐provisioning Adélie Penguins in Antarctica over five consecutive years.

Time spent diving per day, an index of foraging effort, varied among male and female parents, and among pairs. These daily interindividual or interpair differences in time spent diving appeared to be consistent over the 2‐week study period within each breeding season.

Frequency of meals delivered by parents was positively correlated with their brood growth rate. Meal frequency was, however, independent of the amount of time spent diving per day by parents and the time spent diving did not affect brood growth rates.

Rates of body mass loss of breeding pairs were positively correlated with brood growth rates.

Our results did not support the hypothesis that parents with higher foraging effort have higher offspring growth rates. It is suggested that parental allocation of resources obtained during foraging, rather than the degree of foraging effort, is the more important process determining offspring growth rates in Adélie Penguins.
Cross‐generation effects due to cold exposure in Drosophila serrata
Authors: Magiafoglou A. , Hoffmann A. A.
Published: October 2003

Environmental variation experienced in the parental and grandparental generation can affect progeny phenotype, performance and response to selection. Here the effects of parental and grandparental exposure to a non‐lethal cold shock are considered in Drosophila serrata Malloch. Development time, viability and early age productivity were measured in flies originating from border and central locations in the distribution of this species that had been held under two separate laboratory maintenance schedules.

Cross‐generation effects were detected for several traits. Development time usually decreased following maternal and/or grandmaternal cold exposure. Parental cold exposure negatively influenced viability while grandparental effects on viability were negligible. Early female productivity showed opposing responses depending on generation; maternal cold exposure increased progeny productivity while grandmaternal exposure decreased it. Male parental and grandparental exposure to cold shock decreased male productivity, although this pattern may have been partly confounded by size effects.

Population effects, reflecting geographical origin, were limited to development time, while selective background effects were demonstrated for most traits. The influence these factors had on the expression of cross‐generation effects was negligible, given interactions with treatment were not evident. These responses suggest that environmental variation experienced in preceding generations can influence progeny phenotype in a manner that is complex and difficult to predict.
The growth strategy of an alpine beetle: maximization or individual growth adjustment in relation to seasonal time horizons?
Authors: Margraf N. , Gotthard K. , Rahier M.
Published: October 2003

Life‐history theory typically predicts that juvenile growth rate should be maximized and consequently juvenile period minimized. However, in several examples it has been shown that insect larvae do not always grow as fast as they can and this has been explained by costs of high growth rate, typically higher juvenile mortality rate. Hence, some insect larvae have the ability to adaptively adjust growth rate to catch up if development is delayed.

The presence of such ability was tested for in the alpine beetle Oreina elongata Suffrian. In this species, the favourable period for development is relatively short and of unpredictable length, and individuals are chemically defended against predation; factors that could affect the balance between the benefits and costs of high growth rate.

Here it is shown that when time stressed, O. elongata larvae were able to increase growth rate, accelerate development and reach the normal final weight.

Hence, individual growth rate adjustment was present in a situation where its adaptive value appeared to be relatively weak, which supports the notion that flexible growth strategies are a common phenomenon in temperate insects.
Mortality in seedling populations of Silver Birch: genotypic variation and herbivore effects
Authors: Prittinen K. , Pusenius J. , Koivunoro K. , Rousi M. , Roininen H.
Published: October 2003

Variation among mature plants reflects mortality that has occurred during the seedling phase. Our earlier studies have shown variation in resistance to insect and vole herbivory among Silver Birch genotypes that represent variation in a naturally regenerated birch stand. The aim of this study was to examine whether seedling mortality varied among these genotypes, and whether insect and field vole herbivory affected mortality. The 20 genotypes studied competed with each other in dense stands, which were randomly assigned to insect and vole exposure and fertilization treatments.

Insect herbivory and fertilization increased mortality significantly (by 98 and 68%, respectively). The fertilization effect was probably due to accelerated self‐thinning among fast‐growing seedlings. Although vole browsing removed considerable biomass, it did not affect seedling mortality.

Mortality was context‐dependent. The genotypes differed both in their overall mortality and in their response to insect herbivory. However, the effect of insects on a genotype depended more on its success in competition than on its resistance: even small amounts of feeding were detrimental to short, shaded seedlings, while taller seedlings in the canopy were affected less, although they were eaten more.

It is concluded that moderate levels of insect herbivory can increase seedling mortality considerably. Furthermore, herbivory can change the genetic structure of birch populations through selective mortality, which in dense stands is dependent on competitive traits.
Carotenoid concentration and coloration of American Kestrels (Falco sparverius) disrupted by experimental exposure to PCBs
Authors: Bortolotti Gary R. , Fernie Kimberly J. , Smits Judit E.
Published: October 2003

Bright coloration in birds is typically a sexually selected trait. Expression of such traits is sensitive to environmental factors, so they can function as bioindicators of environmental contamination. Of particular value may be carotenoid‐based coloration because it is commonly used as a social signal and these pigments have important health functions.

American Kestrels (Falco sparverius) in captivity were exposed to dietary PCBs in March. Colour and plasma carotenoids of exposed and control birds were evaluated at pairing and courtship in April, and in winter in December. Juveniles produced by these birds (exposed to PCBs only in ovo) were examined at fledging and in winter.

The brightly coloured ceres and lores were evaluated by comparison to colour charts and quantified using digital photographs, and plasma carotenoid concentrations were quantified by spectrophotometry.

During breeding, PCB‐exposed kestrels differed from controls for both colour and carotenoids, although the nature of effects was sex‐specific. Carotenoids of juveniles were not related to treatment at fledging.

In winter, PCB‐exposure resulted in patterns of colour/carotenoid variation opposite to controls; exposed adult males were duller, and juveniles of both sexes were brighter, than controls. PCB juveniles had higher plasma levels of carotenoids. Sexual dimorphism was apparent in colour and carotenoids of control adults, but not for PCB‐exposed birds.

Our results are consistent with endocrine disruption. Modulation of both colour and carotenoids may have serious consequences to social behaviour and health.
Gender differences in lifespan and mortality rates in two seed beetle species
Authors: Fox C. W. , Dublin L. , Pollitt S. J.
Published: October 2003

In most animals, females live longer than males, and large individuals live longer than small individuals. We examine both gender and body size effects on adult lifespan in two species of seed beetles (Callosobruchus maculatus and Stator limbatus), and test whether body size differences between males and females can explain gender‐differences in mortality rates and lifespan.

In both species, the effect of age on mortality rate was best described by a logistic mortality curve. C. maculatus females have a higher initial mortality rate than males, while males have a much higher rate of increase of the mortality rate with increasing age. In contrast, S. limbatus males had a higher initial mortality rate (opposite to the pattern seen in C. maculatus) but males and females did not differ in the rate of increase of mortality with increasing age.

Body size was positively correlated with lifespan in both species, but it explained very little of the variance in lifespan (R2 < 0·09 for both species) and did not explain the gender difference.

Lifespan was heritable for both genders of both populations (h2 between 0·19 and 0·55), and the shape of the mortality curves varied among families within both species.
Distribution, status and ecology of the mainland slender‐tailed treeshrew Dendrogale murina
Authors: TIMMINS R. J. , DUCKWORTH J. W. , ROBSON C. R. , WALSTON J. L.
Published: October 2003

1. The few historical records of Dendrogale murina are from southern Vietnam, South‐east Thailand and probably Cambodia. Recent records extend its range considerably further north in Vietnam, into Laos, and provide the first certain Cambodian localities. Its occurrence within its range is patchy, and while in some areas (Cat Tien National Park, Vietnam, and a part of Mondulkiri Province, Cambodia) it is clearly common, elsewhere records are infrequent. Dendrogale murina seems to be relatively easy to observe, so the documented range for Laos, Vietnam and Thailand probably approximates to the real range. Cambodia has not been surveyed extensively enough to propose a provisional distribution.

2. There is no obvious ecological correlate of species occurrence: most sites have extensive bamboo, but various other similar sites surveyed within its range lack records. Most records come from evergreen forest (at varying stages of degradation) but D. murina has also been found in mixed deciduous forest, extensive secondary bamboo lacking any dicotyledonous canopy, and in streamside tangles amid rocky savannah. Records range from the plains up to 1500 m altitude.

3. The species mainly uses the under‐ and mid‐storeys, but also enters the canopy. It is active at least throughout the daylight hours; nocturnal activity has not been assessed. Although the ecological needs are poorly understood, there is no reason to believe that D. murina is at any special risk and it is unlikely to meet any IUCN global threat criteria.
Field metabolic rate and body water turnover of the red fox Vulpes vulpes in Australia
Authors: WINSTANLEY ROY K. , BUTTEMER WILLIAM A. , SAUNDERS GLEN
Published: October 2003

We measured the daily energy expenditure of free‐living red foxes Vulpes vulpes occupying a temperate region of New South Wales, Australia. Field metabolic rate (FMR) and body water turnover were estimated using doubly labelled water. In autumn, male body mass ranged from 5 to 6.1 kg (mean 5.6 kg) and their FMRs averaged 2328 kJ/day. Female body mass in autumn ranged from 4.9 to 6.6 kg (mean 5.4 kg) and their FMRs averaged 1681 kJ/day. Body water influx for males and females was 314 and 251 mL/day, respectively. Body composition of each fox was analysed after the field measurements and revealed a significant correlation between body water content, as estimated from tritiated water space, and body lipids (r2 = 0.72). This supports the use of body water determination as a potentially non‐destructive method to gauge body condition.
Eavesdropping on the echolocation and social calls of bats
Authors: FENTON M. B.
Published: October 2003

1. Comparisons of original calls and their echoes allow echolocating microchiropteran bats to collect information about their surroundings. Echolocation calls are also a source of information for other animals. A spectacular example is the hearing‐based defence of many species of insects that use echolocation calls to detect marauding bats. The role of echolocation calls remains unknown for bats that eat other bats.

2. Other eavesdroppers, biologists, regularly monitor echolocation calls to collect information about the distribution and patterns of habitat use of echolocating bats. People monitoring echolocation calls have discovered cryptic species of bats.

3. Vocal communication in bats involves social calls that serve only in communication, as well as echolocation calls that influence the behaviour of conspecifics and others. There is evidence of individual‐ and colony‐specific social and echolocation calls.

4. The long age‐spans of bats and the propensity of some species to roost in groups combine with conspicuousness of echolocation calls to set the stage for the discovery of more behavioural interactions mediated by individual‐specific echolocation calls. In the echolocation of microchiropteran bats, signals can serve multiple functions, both for producers and listeners.
Burrowing rodents as ecosystem engineers: the ecology and management of plateau zokors Myospalax fontanierii in alpine meadow ecosystems on the Tibetan Plateau
Authors: ZHANG YANMING , ZHANG ZHIBIN , LIU JIKE
Published: October 2003

1. Plateau zokors, Myospalax fontanierii, are the only subterranean herbivores on the Tibetan plateau of China. Although the population biology of plateau zokors has been studied for many years, the interactions between zokors and plants, especially for the maintenance and structure of ecological communities, have been poorly recognized. In the past, plateau zokors have been traditionally viewed as pests, competitors with cattle, and agents of soil erosion, thus eradication programmes have been carried out by local governments and farmers. Zokors are also widely and heavily exploited for their use in traditional Chinese medicine.

2. Like other fossorial animals, such as pocket gophers Geomys spp. and prairie dogs Cynomys spp. in similar ecosystems, zokors may act to increase local environmental heterogeneity at the landscape level, aid in the formation, aeration and mixing of soil, and enhance infiltration of water into the soil thus curtailing erosion. The changes that zokors cause in the physical environment, vegetation and soil clearly affect the herbivore food web. Equally, plateau zokors also provide a significant food source for many avian and mammalian predators on the plateau. Zokor control leading to depletion of prey and secondary poisoning may therefore present problems for populations of numerous other animals.

3. We highlight the important role plateau zokors play in the Tibetan plateau ecosystem. Plateau zokors should be managed in concert with other comprehensive rangeland treatments to ensure the ecological equilibrium and preservation of native biodiversity, as well as the long‐term sustainable use of pastureland by domestic livestock.
Temperature and humidity in badger Meles meles setts
Authors: MOORE JUDE A. H. , ROPER TIMOTHY J.
Published: October 2003

1. Temperature and relative humidity were measured within 12 badger Meles meles setts over periods ranging from 24 hours to 1 year.

2. Relative humidity was 100% within all setts at all times of year. Mean daily, monthly and annual within‐sett temperature ranges were 0.37°C, 1.5°C and 10.7°C, respectively, and were significantly less than the corresponding ambient temperature ranges of 8.9°C, 19.0°C and 24.1°C.

3. There was no evidence that the temperature regime of main setts differed from that of outlier setts. Within a single large main sett, temperatures taken simultaneously at different sampling points differed by up to 2.5°C. The temperature of nest chambers that were occupied by a badger was, on average, 2.4°C higher than in unoccupied chambers.

4. We conclude that: (i) variation in within‐sett temperature and humidity is not sufficient to explain the complex way in which badgers use the setts available to them; and (ii) the environmental conditions within badger setts are such as would be expected to favour the survival of bovine tuberculosis Mycobacterium bovis bacilli.
Mixed species groups in mammals
Authors: STENSLAND EVA , ANGERBJÖRN ANDERS , BERGGREN PER
Published: October 2003

1. Mixed species groups have long been noted in birds, but they also occur among different species of mammals ranging from closely related species to species from different orders. Mixed species groups of mammals occur in many different habitats, e.g. ungulates on the savannah, primates in various types of forests and cetaceans in the oceans. Mixed species groups are very different in their duration, frequency, predominant activity and structure depending on the species interacting and the habitat they occur in.

2. Functional explanations for mixed species groups usually fall within two categories: foraging advantages and predator avoidance. However, there could also be other social and reproductive advantages of mixed species groups that could contribute to their formation and stability. The advantages do not have to be equally distributed between the participating species and can also vary according to season and the presence of predators.

3. It is important that all investigators of mixed species groups take their studies one step further after the naturalistic description and test the function and benefits of mixed species groups in order to give more strength to their conclusions. In this paper we review and discuss the function of mixed species groups in mammals and suggest an approach on how to investigate the function of such groups.
Ecology, status and conservation of short‐beaked common dolphinsDelphinus delphisin the Mediterranean Sea
Authors: BEARZI GIOVANNI , REEVES RANDALL R. , NOTARBARTOLO‐DI‐SCIARA GIUSEPPE , POLITI ELENA , CAÑADAS ANA , FRANTZIS ALEXANDROS , MUSSI BARBARA
Published: October 2003

1. The recent decline in the Mediterranean population of short‐beaked common dolphinsDelphinus  delphis  has  been  the  subject of scientific controversy  and  political  indifference. Research on these animals has been very limited and there has been no large‐scale, systematic effort to assess and monitor their abundance and distribution. The consequent lack of data has prevented a good understanding of historical and ongoing trends.

2. Nonetheless, literature and osteological collections confirm that common dolphins were widespread and abundant in much of the Mediterranean Sea until the late 1960s and that their decline occurred relatively quickly. Today, common dolphins remain relatively abundant only in the westernmost portion of the basin (Alboràn Sea), with sparse records off Algeria and Tunisia, concentrations around the Maltese islands and in parts of the Aegean Sea, and relict groups in the south‐eastern Tyrrhenian and eastern Ionian Seas. Otherwise, these dolphins are rare in, or completely absent from, Mediterranean areas where information is available.

3. Circumstantial evidence and qualitative judgements by the authors suggest that the following factors may have contributed to the decline of common dolphins: reduced availability of prey caused by overfishing and habitat degradation; contamination by xenobiotic chemicals resulting in immunosuppression and reproductive impairment; environmental changes such as increased water temperatures affecting ecosystem dynamics; and incidental mortality in fishing gear, especially gillnets. The cumulative importance of these factors is poorly understood, and as a result, few conservation measures have been implemented.

4. This paper reviews current knowledge and suggests priorities for action aimed at identifying and mitigating the main threats to common dolphins in the Mediterranean, with the ultimate goal of restoring the species’ favourable conservation status in the region.
Distribution of the Clymene dolphin Stenella clymene
Authors: FERTL DAGMAR , JEFFERSON THOMAS A. , MORENO IGNACIO B. , ZERBINI ALEXANDRE N. , MULLIN KEITH D.
Published: October 2003

1. The Clymene dolphin Stenella clymene is found in tropical and warm temperate waters of both the North and South Atlantic Oceans. Confusion surrounding the identifying characteristics of this species has contributed to a general lack of knowledge of this species.

2. We collected and verified a total of 195 records (109 sightings, 67 strandings, and 19 captures) of Clymene dolphins. Twenty‐five per cent (n = 49) of these records were previously unpublished. Rejected records are discussed in order to clarify the literature.

3. The northernmost locations for the Clymene dolphin are 39°17′N, 74°35′W (NJ, USA) and 19°1.9′N, 16°13.5′W (113 km north of Nouakchott, Mauritania). The southernmost locations are 29°58′S, 50°07′W (Tramandaí, Rio Grande do Sul, Brazil) and 3°40′S, 18°5′W (off Ascension Island).

4. Clymene dolphins were found in waters with bottom depths ranging from 44 to 4500 m (mean = 1870 m; SE = 110 m; median = 1675 m; n = 94). A single sighting reported at a location with a bottom depth of 44 m is considered to be atypical, as this species has an otherwise exclusively oceanic distribution.

5. Group sizes ranged from at least one individual in a mixed‐species school of spinner dolphins Stenella longirostris to a group of an estimated 1000 animals (mean = 76.1; SE = 11; median = 47; n = 105). Stranding group size ranged from 1 to 46 individuals (n = 67), with single individuals being most common (n = 60). There is information available for seven mass strandings, all of which occurred in the south‐eastern USA.
Human haemoglobin
Authors: Shikama Keiji , Matsuoka Ariki
Published: October 2003

This review summarizes the most recent state of haemoglobin (Hb) research based on the literature and our own results. In particular, an attempt is made to form a unified picture for haemoglobin function by reconciling the cooperative oxygen binding with the stabilization of the bound dioxygen in aqueous solvent. The HbA molecule contains two types of αβ contacts. One type is the α1β2 or α2β1 contacts, called sliding contacts, and these are strongly associated with the cooperative binding of O2 to the α2β2 tetramer. The other type is the α1β1 or α2β2 contacts, called packing contacts, but whose role in Hb function was not clear until quite recently. However, detailed pH‐dependence studies of the autoxidation rate of HbO2 have revealed that the α1β1 and α2β2 interfaces are used for controlling the stability of the bound O2. When the α1β1 or α2β2 contact is formed, the β chain is subjected to a conformational constraint which causes the distal (E7) histidine to be tilted slightly away from the bound dioxygen, preventing the proton‐catalysed nucleophilic displacement of O2– from the FeO2 by an entering water molecule. This is one of the most characteristic features of HbO2 stability. Finally we discuss the role of the α1β1 or α2β2 contacts by providing some examples of unstable haemoglobin mutants. These pathological mutations are found mostly on the β chain, especially in the α1β1 contact regions. In this way, HbA seems to differentiate two types of αβ contacts for its functional properties.
ATP N‐glycosidase – a novel ATP‐converting activity from a marine sponge Axinella polypoides
Authors: Reintamm Tõnu , Lopp Annika , Kuusksalu Anne , Pehk Tõnis , Kelve Merike
Published: October 2003

A novel nucleosidase enzymatic activity was discovered in the marine sponge Axinella polypoides. This enzyme, designated as ATP N‐glycosidase, converts adenosine‐5′‐triphosphate into adenine and ribose‐5‐triphosphate. The crude extract of A. polypoides was capable of hydrolysing 25 µmol ATP·min−1 per g wet weight of sponge. The catalytic activity of a sponge crude extract per mg total protein is comparable with specific activities of purified plant adenosine and bacterial AMP nucleosidases. The preferred substrate for the novel enzyme is ATP but any compound containing adenosine‐5′‐diphosphoryl fragment is also cleaved. The biochemical properties (Km, Kip, environmental requirements) of ATP N‐glycosidase show similarities with previously described adenine‐specific nucleosidases; however, the pattern of its biochemical characteristics does not match with that of any of those enzymes.
Characterization of eIF3k
Authors: Mayeur Greg L. , Fraser Christopher S. , Peiretti Franck , Block Karen L. , Hershey John W. B.
Published: October 2003

Mammalian translation initiation factor 3 (eIF3) is a multisubunit complex containing at least 12 subunits with an apparent aggregate mass of ≈ 700 kDa. eIF3 binds to the 40S ribosomal subunit, promotes the binding of methionyl‐tRNAi and mRNA, and interacts with several other initiation factors to form the 40S initiation complex. Human cDNAs encoding 11 of the 12 subunits have been isolated previously; here we report the cloning and characterization of a twelfth subunit, a 28‐kDa protein named eIF3k. Evidence that eIF3k is present in the eIF3 complex was obtained. A monoclonal anti‐eIF3a (p170) Ig coimmunoprecipitates eIF3k with the eIF3 complex. Affinity purification of histidine‐tagged eIF3k from transiently transfected COS cells copurifies other eIF3 subunits. eIF3k colocalizes with eIF3 on 40S ribosomal subunits. eIF3k coexpressed with five other ‘core’ eIF3 subunits in baculovirus‐infected insect cells, forms a stable, immunoprecipitatable, complex with the ‘core’. eIF3k interacts directly with eIF3c, eIF3g and eIF3j by glutathione S‐transferase pull‐down assays. Sequences homologous with eIF3k are found in the genomes of Caenorhabitis elegans, Arabidopsis thaliana and Drosophila melanogaster, and a homologous protein has been reported to be present in wheat eIF3. Its ubiquitous expression in human tissues, yet its apparent absence in Saccharomyces cerevisiae and Schizosaccharomyces pombe, suggest a unique regulatory role for eIF3k in higher organisms. The studies of eIF3k complete the characterization of mammalian eIF3 subunits.
Activated transglutaminase from Streptomyces mobaraensis is processed by a tripeptidyl aminopeptidase in the final step
Authors: Zotzel Jens , Pasternack Ralf , Pelzer Christiane , Ziegert Dagmar , Mainusch Martina , Fuchsbauer Hans‐Lothar
Published: October 2003

Transglutaminase (TGase) from Streptomyces mobaraensis is secreted as a precursor protein which is completely activated by the endoprotease TAMEP, a member of the M4 protease family [Zotzel, J., Keller, P. & Fuchsbauer, H.‐L. (2003) Eur. J. Biochem. 270, 3214–3222]. In contrast with the mature enzyme, TAMEP‐activated TGase exhibits an additional N‐terminal tetrapeptide (Phe‐Arg‐Ala‐Pro) suggesting truncation, at least, by a second protease. We have now isolated from the culture broth of submerged colonies a tripeptidyl aminopeptidase (SM‐TAP) that is able to remove the remaining tetrapeptide. The 53‐kDa peptidase was purified by ion‐exchange and phenyl‐Sepharose chromatography and subsequently characterized. Its proteolytic activity was highest against chromophoric tripeptides at pH 7 in the presence of 2 mm CaCl2. EDTA and EGTA (10 mm) both diminished the proteolytic activity by half. Complete inhibition was only achieved with 1 mm phenylmethanesulfonyl fluoride, suggesting that SM‐TAP is a serine protease. Alignment of the N‐terminal sequence confirmed its close relation to the Streptomyces TAPs. That removal of Phe‐Arg‐Ala‐Pro from TAMEP‐activated TGase by SM‐TAP occurs in a single step was confirmed by experiments using various TGase fragments and synthetic peptides. SM‐TAP was also capable of generating the mature N‐terminus by cleavage of RAP‐TGase. However, AP‐TGase remained unchanged. As SM‐TAP activity against chromophoric amino acids such as Pro‐pNA or Phe‐pNA could not be detected, the tetrapeptide of TAMEP‐activated TGase must be removed without formation of an intermediate.
Characterization of the 16S rRNA‐ and membrane‐binding domains of Streptococcus pneumoniae Era GTPase
Authors: Hang Julie Q. , Zhao Genshi
Published: October 2003

Era is a highly conserved GTPase essential for bacterial growth. The N‐terminal part of Era contains a conserved GTPase domain, whereas the C‐terminal part of the protein contains an RNA‐ and membrane‐binding domain, the KH domain. To investigate whether the binding of Era to 16S rRNA and membrane requires its GTPase activity and whether the GTPase domain is essential for these activities, the N‐ and C‐terminal parts of the Streptococcus pneumoniae Era – Era‐N (amino acids 1–185) and Era‐C (amino acids 141–299), respectively – were expressed and purified. Era‐C, which had completely lost GTPase activity, bound to the cytoplasmic membrane and 16S rRNA. In contrast, Era‐N, which retained GTPase activity, failed to bind to RNA or membrane. These results therefore indicate that the binding of Era to RNA and membrane does not require the GTPase activity of the protein and that the RNA‐binding domain is an independent, functional domain. The physiological effects of the overexpression of Era‐C were assessed. The Escherichia coli cells overexpressing Era and Era‐N exhibited the same growth rate as wild‐type E. coli cells. In contrast, the E. coli cells overexpressing Era‐C exhibited a reduced growth rate, indicating that the overexpression of Era‐C inhibits cell growth. Furthermore, overexpression of era‐N and era‐C resulted in morphological changes. Finally, purified Era and Era‐C were able to bind to poly(U) RNA, and the binding of Era to poly(U) RNA was significantly inhibited by liposome, as the amount of Era bound to the RNA decreased proportionally with the increase of liposome in the assay. Therefore, this study provides the first biochemical evidence that both binding sites are overlapping. Together, these results indicate that the RNA‐ and membrane‐binding domain of Era is a separate, functional entity and does not require the GTPase activity or the GTPase domain of the protein for activity.