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41.
GUILLAUME TCHERKEZ RUDI SCHÄUFELE SALVADOR NOGUÉS CLÉMENT PIEL ARNOUD BOOM GARY LANIGAN CÉCILE BARBAROUX CATARINA MATA SLIMAN ELHANI DEBBIE HEMMING CHRISTINA MAGUAS DAN YAKIR FRANZ W. BADECK HOWARD GRIFFITHS HANS SCHNYDER JALEH GHASHGHAIE 《Plant, cell & environment》2010,33(6):900-913
While there is currently intense effort to examine the 13C signal of CO2 evolved in the dark, less is known on the isotope composition of day‐respired CO2. This lack of knowledge stems from technical difficulties to measure the pure respiratory isotopic signal: day respiration is mixed up with photorespiration, and there is no obvious way to separate photosynthetic fractionation (pure ci/ca effect) from respiratory effect (production of CO2 with a different δ13C value from that of net‐fixed CO2) at the ecosystem level. Here, we took advantage of new simple equations, and applied them to sunflower canopies grown under low and high [CO2]. We show that whole mesocosm‐respired CO2 is slightly 13C depleted in the light at the mesocosm level (by 0.2–0.8‰), while it is slightly 13C enriched in darkness (by 1.5–3.2‰). The turnover of the respiratory carbon pool after labelling appears similar in the light and in the dark, and accordingly, a hierarchical clustering analysis shows a close correlation between the 13C abundance in day‐ and night‐evolved CO2. We conclude that the carbon source for respiration is similar in the dark and in the light, but the metabolic pathways associated with CO2 production may change, thereby explaining the different 12C/13C respiratory fractionations in the light and in the dark. 相似文献
42.
HANS‐PETER SCHULTZE DIRK FUCHS SAMUEL GIERSCH CHRISTINA IFRIM WOLFGANG STINNESBECK 《Palaeontology》2010,53(3):689-694
Abstract: The supposed vestige of a cephalopod gladius from Turonian platy limestones at Vallecillo, north‐east Mexico, named Palaeoctopus pelagicus by Fuchs et al. in 2008, is reinterpreted and shown to be a gular plate of a coelacanth fish, possibly of the genus Megacoelacanthus. In addition to the gular plate, two extrascapulars and fin rays of all fins are preserved on one slab and its counterpart. This is the first record of a coelacanth from these lower Turonian strata at Vallecillo, which are rich in fish. 相似文献
43.
KENNETH P. SEVERIN JERE H. LIPPS 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1989,22(1):1-12
Severin, Kenneth P. & Lipps, Jere H. 1989 01 15: The weight-volume relationship of the test of Alveolinella quoyi: Implications for the taphonomy of large fusiform foraminifera. Lethaia , Vol. 22, pp. 1–12. Oslo. ISSN 0024–1164.
Alveolinella quoyi , the largest living fusiform foraminifer, can be used to infer the paleobiology of extinct fusulinids and alveolinids. We measured test plus organic material weight, test weight, and test volume for A. quoyi , allowing the calculation of test density under various conditions. Tests have an average of 43% chamber space, and an average density of 1.5 gcm-3 . Living individuals can only fill an average of 39% of their chamber space with protoplasm. If they fill the remaining space with sea water, average effective test density is 0.953 gcm-3 , if the space is filled with a gas the density is 0.671 gcm-3 . Living individuals can withstand current velocities of 3–4 m sec-1 , velocities greater than commonly occur in A. quoyi's habitat. Dead tests have lower effective densities than many carbonate sedimentary particles (0.508 g cm-3 if the chamber space is gas filled, 0.953 g cm-3 if it is sea water filled), making their settling velocities slow relative to similarly shaped and sized particles. Their large size and high traction velocities (>0.2m sec-1 ) makes them unaffected by gentle currents which can remove 100–200 μ sized particles from the sediment. Their low settling velocity will tend to concentrate A. quoyi tests during subsequent resuspension, creating a layer of tests near the sediment-water interface. Concentrations of extinct fusiform foraminifera may have formed in a similar manner. □ Lorger foraminifera, test weight, test volume, test density, taphonomy . 相似文献
Alveolinella quoyi , the largest living fusiform foraminifer, can be used to infer the paleobiology of extinct fusulinids and alveolinids. We measured test plus organic material weight, test weight, and test volume for A. quoyi , allowing the calculation of test density under various conditions. Tests have an average of 43% chamber space, and an average density of 1.5 gcm
44.
NIKOS T. PAPADOPOULOS JAMES R. CAREY PABLO LIEDO HANS‐GEORG MÜLLER DAMLA SENTÜRK 《Physiological Entomology》2009,34(3):238-245
Abstract. Aggressive behaviour occurring in intrasexual competition is an important trait for animal fitness. Although female intrasexual aggression is reported in several insect species, little is known about female competition and aggressive interactions in polygynous male lekking species. The interactions of female Mediterranean fruit flies, Ceratitis capitata (a male lekking species), with other females and mating pairs under laboratory conditions are investigated. Mature, unmated (virgin) females are aggressive against each other and against mating pairs, whereas immature females are not. Female aggression against other females decreases dramatically after mating; however, mated females maintain aggression against mating pairs. In addition, higher intrasexual aggression rates are observed for mature, virgin females than for virgin males of the same age. The results show that female aggressiveness is virginity related, suggesting female competition for mates. These findings have important implications for understanding the physiological aspects of a complex social behaviour such as aggression and should stimulate further research on female agonistic behaviour in male lekking mating systems. 相似文献
45.
BARBARA ZIMMERMANN PETTER WABAKKEN HÅKAN SAND HANS C. PEDERSEN OLOF LIBERG 《The Journal of wildlife management》2007,71(4):1177-1182
Abstract: To estimate wolf (Canis lupus) kill rates from fine-scale movement patterns, we followed adult wolves in 3 territories of the Scandinavian wolf population using Global Positioning Systems (GPS) during the winters of 2001–2003. The resulting 6 datasets of 62–84 study days gave a total of 8,747 hourly GPS positions. We visited clusters of positions in the field on average 8.8 days after positioning and found moose (Alces alces) killed by wolves during the study period on 74 (8%) of the 953 clusters. The number of positions and visits to a cluster, their interaction, and the proportion of afternoon positions were significant fixed effects in mixed logistic-regression models predicting the probability of a cluster containing a wolf-killed moose. The models, however, displayed a poor goodness-of-fit and were not a suitable tool for estimating kill rates from positioning data alone. They might be used to reduce fieldwork by excluding unlikely clusters, although the reduction was not substantial. We discuss proximate factors (i.e., human disturbance and access to prey) as well as ultimate factors (i.e., social organization, intra-guild dominance, and litter size) as potential causes of the observed high temporal and spatial variation in prey-handling. For similar future kill-rate studies, we recommend increasing field efforts and shortening positioning intervals. 相似文献
46.
PETTER WABAKKEN HÅKAN SAND ILPO KOJOLA BARBARA ZIMMERMANN JON M. ARNEMO HANS C. PEDERSEN OLOF LIBERG 《The Journal of wildlife management》2007,71(5):1631-1634
Abstract: We document a new record dispersal for wolves worldwide. The natal straight-line dispersal distance of a Global Positioning System-collared female wolf from the Scandinavian population was 1,092 km from southeast Norway to northeast Finland, with a multistage actual travel distance of >10,000 km. Natural gene flow to the isolated, inbred Scandinavian wolf population may occur if survival of dispersers is improved. 相似文献
47.
Phosphorus recycling in photorespiration maintains high photosynthetic capacity in woody species 下载免费PDF全文
DAVID S. ELLSWORTH KRISTINE Y. CROUS HANS LAMBERS JULIA COOKE 《Plant, cell & environment》2015,38(6):1142-1156
Leaf photosynthetic CO2 responses can provide insight into how major nutrients, such as phosphorus (P), constrain leaf CO2 assimilation rates (Anet). However, triose‐phosphate limitations are rarely employed in the classic photosynthesis model and it is uncertain as to what extent these limitations occur in field situations. In contrast to predictions from biochemical theory of photosynthesis, we found consistent evidence in the field of lower Anet in high [CO2] and low [O2] than at ambient [O2]. For 10 species of trees and shrubs across a range of soil P availability in Australia, none of them showed a positive response of Anet at saturating [CO2] (i.e. Amax) to 2 kPa O2. Three species showed >20% reductions in Amax in low [O2], a phenomenon potentially explained by orthophosphate (Pi) savings during photorespiration. These species, with largest photosynthetic capacity and Pi > 2 mmol P m?2, rely the most on additional Pi made available from photorespiration rather than species growing in P‐impoverished soils. The results suggest that rarely used adjustments to a biochemical photosynthesis model are useful for predicting Amax and give insight into the biochemical limitations of photosynthesis rates at a range of leaf P concentrations. Phosphate limitations to photosynthetic capacity are likely more common in the field than previously considered. 相似文献
48.
49.
MARC DE HERT DAN COHEN JULIO BOBES MARCELO CETKOVICH‐BAKMAS STEFAN LEUCHT DAVID M. NDETEI JOHN W. NEWCOMER RICHARD UWAKWE ITSUO ASAI HANS‐JURGEN MÖLLER SHIV GAUTAM JOHAN DETRAUX CHRISTOPH U. CORRELL 《World psychiatry》2011,10(2):138-151
Physical disorders are, compared to the general population, more prevalent
in people with severe mental illness (SMI). Although this excess morbidity
and mortality is largely due to modifiable lifestyle risk factors, the screening
and assessment of physical health aspects remains poor, even in developed
countries. Moreover, specific patient, provider, treatment and system factors
act as barriers to the recognition and to the management of physical diseases
in people with SMI. Psychiatrists can play a pivotal role in the improvement
of the physical health of these patients by expanding their task from clinical
psychiatric care to the monitoring and treatment of crucial physical parameters.
At a system level, actions are not easy to realize, especially for developing
countries. However, at an individual level, even simple and very basic monitoring
and treatment actions, undertaken by the treating clinician, can already improve
the problem of suboptimal medical care in this population. Adhering to monitoring
and treatment guidelines will result in a substantial enhancement of physical
health outcomes. Furthermore, psychiatrists can help educate and motivate
people with SMI to address their suboptimal lifestyle, including smoking,
unhealthy diet and lack of exercise. The adoption of the recommendations presented
in this paper across health care systems throughout the world will contribute
to a significant improvement in the medical and related psychiatric health
outcomes of patients with SMI. 相似文献
50.