Pinus sylvestris L., Die gemeine Kiefer     

Dr. Peter Karl Schott 《European Journal of Forest Research》1904,26(8-9):436-449

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Pyrene and nile red fluorescence probes for in‐situ study of polarity and viscosity of soil organic coatings implicated in soil water repellency     

Helen M. Balshaw  Peter Douglas  Matthew L. Davies  Stefan H. Doerr 《European Journal of Soil Science》2020,71(5):868-879

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System for quasi‐continuous simultaneous measurement of oxygen diffusion rate and redox potential in soil     

Ren Reiser  Viktor Stadelmann  Peter Weisskopf  Lina Grahm  Thomas Keller 《植物养料与土壤学杂志》2020,183(3):316-326

Oxygen diffusion rate (ODR) and redox potential (E_H) are quantitative indices representing oxygen availability and redox status in soils, which is valuable information for better understanding causes and effects of soil aeration. Because these indices are spatially and temporally highly variable, continuous measurements and adequate numbers of repetitions are essential for accurate in situ monitoring. Here, we present a new, fully automated recording system for in situ measurements where ODR and E_H are measured at the same platinum electrode. The conflict between electrode polarization for ODR and the resulting biased E_H readings is solved by reducing the polarization time and introducing a recovery interval between two consecutive measurement cycles. The shorter polarization time ensures accurate E_H readings. It also results in moderately overestimated ODR readings, but this can be corrected before data analysis. The recovery interval restricts temporal resolution of the E_H‐ODR data pairs to 8 h. We illustrate the use of the system with measurements in a field experiment in Zürich, Switzerland. ODR curves at different depths ran roughly parallel to the corresponding curves of O₂ concentration in soil air but ODR was much more sensitive to precipitation. Low ODR was a necessary but not a sufficient condition for declining E_H. E_H ran parallel to O₂ concentration in soil air rather than to ODR. The fully automated system allows for time series of replicate measurements in multifactorial field studies with reasonable labor requirements. It may be particularly suitable for studies examining the effects of soil tillage, compaction, and irrigation, where structure‐related soil properties such as porosity, gas permeability, and soil aeration play a dominant role.  相似文献   

Regional and local scale variations in soil organic carbon stocks in West Greenland     

Philipp Gries  Karsten Schmidt  Thomas Scholten  Peter Kühn 《植物养料与土壤学杂志》2020,183(3):292-305

The soil organic carbon (SOC) pool of the Northern Hemisphere contains about half of the global SOC stored in soils. As the Arctic is exceptionally sensitive to global warming, temperature rise and prolonged summer lead to deeper thawing of permafrost‐affected soils and might contribute to increasing greenhouse gas emissions progressively. To assess the overall feedback of soil organic carbon stocks (SOCS) to global warming in permafrost‐affected regions the spatial variation in SOCS at different environmental scales is of great interest. However, sparse and unequally distributed soil data sets at various scales in such regions result in highly uncertain estimations of SOCS of the Northern Hemisphere and here particularly in Greenland. The objectives of this study are to compare and evaluate three controlling factors for SOCS distribution (vegetation, landscape, aspect) at two different scales (local, regional). The regional scale reflects the different environmental conditions between the two study areas at the coast and the ice margin. On the local scale, characteristics of each controlling factor in form of defined units (vegetation units, landscape units, aspect units) are used to describe the variation in the SOCS over short distances within each study area, where the variation in SOCS is high. On a regional scale, we investigate the variation in SOCS by comparing the same units between the study areas. The results show for both study areas that SOCS are with 8 kg m^?2 in the uppermost 25 cm and 16 kg m^?2 in the first 100 cm of the soil, i.e., 3 to 6 kg m^?2 (37.5%) higher than existing large scale estimations of SOCS in West Greenland. Our approach allows to rank the scale‐dependent importance of the controlling factors within and between the study areas. However, vegetation and aspect better explain variations in SOCS than landscape units. Therefore, we recommend vegetation and aspect for determining the variation in SOCS in West Greenland on both scales.  相似文献   

Rassen der gemeinen Kiefer     

Peter Karl Schott 《Forstwissenschaftliches Centralblatt》1907,29(4):199-218

Ohne Zusammenfassung  相似文献   

New lease of life for Darwin's giant tortoises,Galápagos Islands     

Peter F.R. Jackson 《Biological conservation》1974,6(1):63-64

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Papyrus from ‘Ra I’ crosses Atlantic Ocean to Norway     

Thor Heyerdahl  Peter B. Jones 《Biological conservation》1974,6(1):60

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THRESHOLD: An international centre for environmental renewal     

James L. Aldrich  Peter H. Freeman  John P. Milton 《Biological conservation》1973,5(1):5-6

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Direct actions of serotonin on gonadotropin-II and growth hormone release from goldfish pituitary cells: interactions with gonadotropin-releasing hormone and dopamine and further evaluation of serotonin receptor specificity     

A.O.L. Wong  C.K. Murphy  J.P. Chang  C.M. Neumann  A. Lo  R.E. Peter 《Fish physiology and biochemistry》1998,19(1):23-34

In this study, the direct actions of serotonin (5HT) on gonadotropin (GTH)-II and growth hormone (GH) release in the goldfish were tested at the pituitary cell level. 5HT (10 nM - 10 µM) stimulated GTH-II but inhibited GH release from perifused goldfish pituitary cells in a dose-dependent manner. The minimal effective dose of 5HT tested to suppress basal GH secretion (10 nM) was 10-fold lower than that to stimulate GTH-II release (100 nM). The GTH-II releasing effect of 5HT was abolished by repeated 5HT treatment (10 µM) whereas the corresponding inhibition on GH release was unaffected. These results suggest that 5HT receptors on goldfish gonadotrophs and somatotrophs exhibit intrinsic differences in terms of sensitivity to stimulation and resistance to desensitization. Salmon GTH-releasing hormone (sGnRH, 100 nM) stimulated GTH-II and GH release from goldfish pituitary cells. The GTH-II releasing action of sGnRH was unaffected by simultaneous treatment of 5HT (1 µM). However, the corresponding GH response to sGnRH (100 nM) was inhibited. In the goldfish, dopamine is known to stimulate GH release through activation of pituitary D1 receptors. In the present study, the GH-releasing action of dopamine (1 µM) and the D1 agonist SKF38393 (1 µM) was significantly reduced by 5HT (1 µM). To examine the receptor specificity of 5HT action, the effects of 5HT1 and 5HT2 analogs on GTH-II and GH release were tested in goldfish pituitary cells. The 5HT1 agonist 8OH DPAT (0.1 and 1µM) and 5HT2 agonist methyl 5HT (0.1 1µM) mimicked the GTH-II releasing effect of 5HT. The 5HT1 agonist 8OH DPAT (0.1 and 1µM) also stimulated GH release but the 5HT2 agonist methyl 5HT (0.1 and 1µM) was inhibitory to basal GH secretion. In addition, 5HT (1µM) -stimulated GTH-II release was abolished by the 5HT1 antagonist methiothepin (10µM) and 5HT2 antagonist mianserin (10µM). Similarly, the inhibitory action of 5HT (1µM) on basal GH release was blocked by the 5HT2 antagonist mianserin (10µM). The 5HT1 antagonist methiothepin (10µM) was not effective in this regard. These results, taken together, indicate that 5HT exerts its regulatory actions on GTH-II and GH release in the goldfish directly at the pituitary cell level, probably through interactions with other regulators including sGnRH and dopamine. The GTH-II releasing action of 5HT is mediated through 5HT2 and possibly 5HT1 receptors. The inhibition of 5HT on basal GH release is mediated through 5HT2 receptors only. Apparently, 5HT1 receptors are not involved in this inhibitory action. In this study, a paradoxical stimulatory component of 5HT on GH release by activating 5HT1 receptors is also implicated.  相似文献   

Immunostimulatory effects of dietary poly‐β‐hydroxybutyrate in European sea bass postlarvae          下载免费PDF全文

Andrea Franke  Catriona Clemmesen  Peter De Schryver  Linsey Garcia‐Gonzalez  Joanna J Miest  Olivia Roth 《Aquaculture Research》2017,48(12):5707-5717

The stable production of high‐quality fry in marine aquaculture is still hampered by unpredictable mortality caused by infectious diseases during larval rearing. Consequently, the development of new biocontrol agents is crucial for a viable aquaculture industry. The bacterial energy storage compound poly‐β‐hydroxybutyrate (PHB) has been shown to exhibit beneficial properties on aquatic organisms such as enhanced survival, growth, disease resistance and a controlling effect on the gastrointestinal microbiota. However, the effect of PHB on the developing immune system of fish larvae has so far not been investigated. In this study, the effect of feeding PHB‐enriched Artemia nauplii on survival, growth and immune response in European sea bass (Dicentrarchus labrax) postlarvae was examined. Amorphous PHB was administered to 28‐day‐old sea bass postlarvae over a period of 10 days. The survival and growth performance were monitored, and the expression of 29 genes involved in immunity, growth, metabolism and stress‐response was measured. While the expression of the insulin‐like growth factor 1 (igf1), an indicator of relative growth, was upregulated in response to feeding PHB, the larval survival and growth performance remained unaffected. After 10 days of PHB treatment, the expression of the antimicrobial peptides dicentracin (dic) and hepcidin (hep) as well as mhc class IIa and mhc class IIb was elevated in the PHB fed postlarvae. This indicates that PHB is capable of stimulating the immune system of fish early life stages, which may be the cause of the increased resistance to diseases and robustness observed in previous studies.  相似文献