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471.
472.
The parthenogenetic Marmorkrebs (marbled crayfish) produces genetically uniform offspring 总被引:1,自引:0,他引:1
Genetically identical animals are very much in demand as laboratory objects because they allow conclusions about environmental
and epigenetic effects on development, structures, and behavior. Furthermore, questions about the relative fitness of various
genotypes can be addressed. However, genetically identical animals are relatively rare, in particular, organisms that combine
a high reproduction rate and a complex organization. Based on its exclusively parthenogenetic reproduction mode, it has been
suggested that the Marmorkrebs (Crustacea, Decapoda, Astacida), a recently discovered crayfish, is an excellent candidate
for research addressing the aforementioned questions. However, until now, a study using molecular markers that clearly proves
the genetic uniformity of the offspring has been lacking. Here, with this first molecular study, we show that this crayfish
indeed produces genetically uniform clones. We tested this with 19 related individuals of various generations of a Marmorkrebs
population by means of six different microsatellite markers. We found that all examined specimens were identical in their
allelic composition. Furthermore, half of the analyzed loci were heterozygous. These results and the absence of meioses in
previous histological studies of the ovaries lead us to conclude the Marmorkrebs propagates apomictically. Thus, a genetically
uniform organism with complex morphology, development, and behavior is now available for various laboratory studies. 相似文献
473.
Aske Skovmand Bosselmann Klaus Dons Thomas Oberthur Carsten Smith Olsen Anders Ræbild Herman Usma 《Agriculture, ecosystems & environment》2009,129(1-3):253-260
Production of coffee, especially by small holders, is often associated with various forms of shade management. To analyse the effects of shade on physical coffee quality and on sensorial cup quality of Coffea arabica L. cv. Caturra KMC, a study was carried out with 94 plots on 16 farms in two municipalities, Timaná and Oporapa, located at elevations from 1272 to 1730 masl. in Huila, Colombia. The study was designed with emphasis on shade cover variation within each of the two study areas, while minimizing the variability of environment, agronomic management other than shade, and post-harvest processing. 46 samples of shade coffee and 46 samples of sun coffee were evaluated for physical and sensorial attributes using three professional coffee cuppers (assessors). A principal component analysis including all quality and environmental variables showed that sensory attributes were influenced negatively by shade, and that physical attributes were influenced positively by altitude. A mixed linear model, with coffee cupper and farm as random variables, revealed different shade effects on coffee quality in the two areas. In Oporapa, situated at high altitudes, shade had a negative effect on fragrance, acidity, body, sweetness and preference of the beverage, while no effect was found on the physical quality. In Timaná, situated at lower altitudes, shade did not have a significant effect on sensorial attributes, but significantly reduced the number of small beans. At high altitudes with low temperatures and no nutrient or water deficits, shade trees may thus have a partly adverse effect on C. arabica cv. Caturra resulting in reduced sensory quality. The occurrence of berry borer (Hypothenemus hampei) was lower at high altitudes and higher under shade. Future studies on shade and coffee quality should focus on the interaction between physical and chemical characteristics of beans. 相似文献
474.
Chunyan Liu Jirko Holst Zhisheng Yao Nicolas Brüggemann Klaus Butterbach-Bahl Shenghui Han Xingguo Han Xunhua Zheng 《Agriculture, ecosystems & environment》2009,134(1-2):136-142
We investigated nitric oxide (NO) fluxes at a summer and a winter sheepfold in the Baiyinxile livestock farm, near Xilinhot, Inner Mongolia, which are a typical feature of the regional husbandry. Using a manual static opaque chamber/chemiluminescence measuring system, we intermittently observed fluxes in the summer sheepfold between May 28th and September 26th 2005 and in both winter and summer sheepfolds between March 8th and October 18th 2006. During these periods, mean NO emissions (±S.E., in terms of mass of nitrogen) were 124.0 ± 28.7, 134.6 ± 23.3 (summer sheepfold) and 214.4 ± 79.6 μg NO–N m−2 h−1 (winter sheepfold), respectively, and thus, three magnitudes higher than observed steppe NO emissions in the same region. The NO fluxes were not significantly different between the 2 years, but in summer they were much higher than in spring (p < 0.05). Temperature and moisture of the faeces layer significantly regulated the NO fluxes (p < 0.01). The direct NO emission factor (EF) for faeces and urine excreted in the sheepfolds was 0.7 g NO–Nemitted kg−1 Nexcreted, which was almost 37 times lower than a recently reported N2O EF. We estimated the total NO emission from the sheepfolds of the Baiyinxile livestock farm to be 1.82 ± 0.43 tons NO–N year−1, which accounts to approximately 12.3% of the total NO emission from this steppe region. With the rapid increase of livestock numbers, sheepfold NO emissions may further increase and contribute to high N deposition in confined areas around sheepfolds. 相似文献
475.
Klaus Jung Karin Kaletta Helmut Segner Gerrit Schüürmann 《Environmental science and pollution research international》1999,6(2):72-76
A stable isotope15N-nitrogen test (ESIMA = Ecotoxicological Stable Isotope Metabolic Assay) was developed to assess biological effects and the
potential toxicological hazard of chemicals and contaminated environmental samples on plant metabolism. The assay measures
the effect of toxicants on the incorporation of a15N labelled tracer into the total nitrogen fraction (both the nonprotein and protein fraction) of plants. Segments ofPisum arvense epicotyls are used as test substrates because of their high metabolic activity. The plant material is incubated under standardised
conditions for two hours; subsequently15N incorporation is analysed by determining the15N abundance (15N atom-%) in the epicotyl segments.
The effects of toxicants are evaluated by comparing the15N incorporation rates of control tissue and epicotyl segments exposed to individual chemicals or complex environmental samples.
The specificity and sensitivity of effects as indicated by ESIMA were compared with effects as measured by two established
ecotoxicological bioassays, the pollen tube growth test using pollen ofNicotiana sylvestris and the bacterial luminescence inhibition test using pollen ofPhotobacterium phosphoreum. The results of the study clearly indicate the suitability of ESIMA for assessing toxic impacts on plant nitrogen metabolism.
Prof. Dr. habil. Hans Faust dedicated to his 70th birthday. 相似文献
476.
Karl-Werner Schramm Petra Marth Alexander Wolf Klaus Hahn Konstantin Oxynos Johannes Schmitzer Antonius Kettrup 《Environmental Sciences Europe》1999,11(5):277-280
Measured partition coefficients (KLM/L) related to lipid-concentrations between the muscle (CML) and liver (CLL) tissue of two fish species (Abramis brama, Zoarces viviparus) exhibit nominal values of unity according the relationship KLM/L=CML/CLL=1 for persistent compounds such as highly chlorinated PCB and values above one for degradable compounds for example chlorinated cyclohexanes or DDT. The corresponding theory is presented. The relationship holds for samples for single fish as well as for pooled samples. 相似文献
477.
478.
Klaus Peschke Peter Friedrich Uwe Kaiser Stephan Franke Wittko Francke 《Chemoecology》1999,9(2):47-54
Summary. In the rove beetle Aleochara curtula, a male specific sternal gland is described. Isopropyl (Z9)-hexadecenoate has been identified by GC/MS of surface and sternal gland extracts as a male specific compound. Its emission
in the air was demonstrated by closed-loopstripping-analyses. In field experiments, conspecific males and females were attracted
by the odor of carrion, caged males from laboratory cultures, and by the synthetic ester. Isopropyl (Z9)-hexadecenoate or live males, combined with fresh carrion attract more beetles than a fresh carcass alone. Isopropyl hexadecanoate
as a minor compound was not attractive. The term “aggregation” pheromone and the ecological significance of attracting females
to a fresh carcass allowing early copulation and egg-deposition are discussed.
Received 20 August 1998; accepted 15 January 1999. 相似文献
479.
Kate Arnold Yvonne Pohlner Klaus Zuberbühler 《Behavioral ecology and sociobiology》2008,62(4):549-559
Some non-human primates produce acoustically distinct alarm calls to different predators, such as eagles or leopards. Recipients
respond to these calls as if they have seen the actual predator, which has led to the notion of functionally referential alarm
calls. However, in a previous study with free-ranging putty-nosed monkeys (Cercopithecus nictitans martini), we demonstrated that callers produced two acoustically distinct alarm calls to eagle shrieks and leopard growls, but both
alarm calls were given to both predators. We can think of two basic explanations for this surprising result, a methodological
and theoretical one. Firstly, acoustic predator models may not always be suitable to test alarm call behaviour in primates,
sometimes causing uncharacteristic behaviour. Secondly, referential alarm calling may not be a universal feature of primate
alarm call systems. Considering the methodological and theoretical importance of these possibilities, we conducted a follow-up
study using life-sized leopard, eagle, and human models on the same population and compared the resulting vocal responses
to those given to acoustic predator models. We compared the alarm call series given to each of these predator model types
and found a considerable degree of consistency suggesting that the mode of presentation did not affect anti-predator calling
strategies. However, evidence for audience effects on calling behaviour was inconclusive. While it appears that predator class
is reliably encoded by different call series types irrespective of the mode of presentation, observations of these same call
series given in non-predatory contexts indicate that predator class is unlikely to be the relevant organising principle underlying
the alarm-calling behaviour in this species. We conclude by offering an alternative, non-referential, account of the alarm-calling
system exhibited by this species.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
480.