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281.
Nadiah Pardede Kristensen Jacob Johansson Niclas Jonzén Henrik G. Smith 《Evolutionary ecology》2018,32(5):509-528
It is generally expected that, in environments with pronounced seasonal resource peaks, birds’ reproductive success will be maximised when nestlings’ peak food demand coincides with the timing of high food availability. However in certain birds that stay resident over winter, earlier breeding leads juveniles to join the winter flock earlier, which by the prior residence effect increases their success in breeding territory competition. This trade-off between reproduction and competition may explain why, in certain species, breeding phenology is earlier and asynchronous with the resource. This study extends a previous model of the evolution of breeding phenology in a single habitat type to a landscape with two habitat types: ‘early’ and ‘late’ resource phenology. The offspring’s natal habitat type has a carryover effect upon their competitive ability regardless of which habitat type they settle in to potentially breed. We find that, when the difference in resource phenology between habitats is small (weak carryover effect), breeding phenology in the late habitat evolves to occur earlier and more asynchronously than in the early habitat, to compensate for the competitive disadvantage to juveniles raised there. However if the difference is large (strong carryover effect), then the reproductive cost of earlier breeding outweighs the benefit of the compensation, so instead breeding phenology in the late habitat evolves to become more synchronous with the resource. Recruitment is generally asymmetric, from early to late habitat type. However if the early habitat is less frequent in the landscape or produces fewer offspring, then the asymmetry is reduced, and if there is some natal habitat-type fidelity, then recruitment can have an insular pattern, i.e. most recruits to each habitat type come from that same habitat type. We detail the different scenarios in which the different recruitment patterns are predicted, and we propose that they have implications for local adaptation. 相似文献
282.
Vitaly A Selivanov Pedro Vizán Faustino Mollinedo Teresa WM Fan Paul WN Lee Marta Cascante 《BMC systems biology》2010,4(1):135
Background
Metabolic flux profiling based on the analysis of distribution of stable isotope tracer in metabolites is an important method widely used in cancer research to understand the regulation of cell metabolism and elaborate new therapeutic strategies. Recently, we developed software Isodyn, which extends the methodology of kinetic modeling to the analysis of isotopic isomer distribution for the evaluation of cellular metabolic flux profile under relevant conditions. This tool can be applied to reveal the metabolic effect of proapoptotic drug edelfosine in leukemia Jurkat cell line, uncovering the mechanisms of induction of apoptosis in cancer cells. 相似文献283.
Kuvalekar Aniket Pawar Pankaj Khare Ankita Gandhe Kanchanganga Harsulkar Abhay 《Plant Cell, Tissue and Organ Culture》2008,94(1):101-104
Ravenelia esculenta Naras. and Thirum. is a rust, pathogenic to Acacia eburnea Willd. The infection leads to hypertrophy changing the morphology with bizarre shapes of plant organs. Healthy and infected
tissues were subjected to extraction of IAA and indole derivatives and were estimated by spectrophotometric methods. The hypertrophy
produced was presumed to be due to increase in the indole-3-acetic acid (IAA) content in the infected tissue, however, the
amount of IAA in infected tissues decreased with the progression of disease. Concomitantly, the infected tissue showed the
presence of a novel, slow migrating, indole derivative on TLC. Cultured shoot tips of Withania somnifera were dosed with the methanolic extract of the infected hypertrophied tissue (MEHT) (0.25, 0.5, 0.75, 1.00 and 1.25 mg/l).
The stimulation in shoot growth along with profuse rooting was observed in a dose dependent manner with maximum at 1.00 and
1.25 mg/l concentration. 相似文献
284.
Epicotyl, petiole, and cotyledon explants derived from 14-d-old seedlings of Albizia odoratissima were cultured on Murashige and Skoog (MS) basal medium supplemented with different concentrations of either 6-benzylaminopurine
(BAP) solely or in combination with 0.5 μM naphthalene-3-acetic acid (NAA). The percentage of shoot regeneration and the number
of shoots regenerated varied significantly depending on the type of explants used, the concentration of plant growth regulators,
and the orientation of explants on the culture medium. The best response in terms of the percentage of shoot regeneration
was obtained from epicotyls cultured horizontally on MS medium supplemented with 5 μM BAP, whereas the highest number of shoots
per responding explant was recorded on medium containing 2.5 μM BAP and 0.5 μM NAA. Successful rooting was achieved by placing
the microshoots onto MS medium containing 25 μM indole-3-butyric acid (IBA) for 24 h first, then transferring to the same
medium without IBA. Of the various substrates tested, vermiculite was the best for plant acclimatization, as 75% of the plants
survived and became established. 相似文献
285.
Attached media reactors are used for enhancement of wastewater treatment processes including anaerobic condition. Selection of a suitable biofilm carrier is a compelling method to improve anaerobic digestion systems. This study investigates the performance of four fibrous biofilms installed in batch biogas reactors for treatment of cow manure. BioCords HS1, HS2, LS1, and LS2 are manufactured by Bishop Water Technologies, ON, Canada. Effluents and attached growth media were analyzed after batch experiment; methane production, methane yield, transfer efficiencies, organic and solid removal efficiencies, pH, and attached volatile suspended solid (VSS) were measured; VSS attached to biofilms mainly correlated with the specific surface area of each biofilm. Additionally, SEM (scanning electron microscopy) was used for further understanding of biofilm formation process for BioCords and the dissimilarity in their performance. The results indicated that BioCord LS2 had positive impact on achieving higher methane production and removal efficiencies compared to other support media utilized in batch reactors. It was also demonstrated from the experiment that BioCord LS2 potentially could generate higher methane production than conventional batch bioreactor. 相似文献
286.
This study explored a consumer-resource model including reproductive and nonreproductive subpopulations of the consumer to
consider whether resource-dependent reproductive adjustment by the consumer would stabilize consumer-resource dynamics. The
model assumed that decreasing (increasing) resource availability caused reproductive suppression (facilitation), and that
the reproductive consumer had a higher mortality rate than the nonreproductive one (i.e., a trade-off between reproduction
and survival). The model predicted that the variability would be reduced when the consumer had a strong tendency to suppress
reproduction in response to low resource availability or when the cost of reproduction was high, although consumer extinction
became more likely. Furthermore, when the consumer-resource dynamics converged to limit cycles, reproductive adjustment enhanced
the long-term average of the consumer density. It was also predicted that if reproductive suppression enhanced resource consumption
efficiency (i.e., a trade-off between reproduction and foraging), then it would destabilize the system by canceling the stabilizing
effect of the reproductive adjustment itself. These results suggest that it is necessary not only to identify the costs of
reproduction, but also to quantify the changes in individual-level performances due to reproduction in order to understand
the ecological consequences of reproductive adjustment. 相似文献
287.
Cold adaptation in the phytopathogenic fungi causing snow molds 总被引:1,自引:0,他引:1
Snow molds are psychrophilic or psychrotrophic fungal pathogens of forage crops, winter cereals, and conifer seedlings. These
fungi can grow and attack dormant plants at low temperatures under snow cover. In this review, we describe the biodiversity
and physiological and biochemical characteristics of snow molds that belong to various taxa. Cold tolerance is one of the
important factors related to their geographic distribution, because snow molds develop mycelia under snow cover and because
they should produce intra- and extracellular enzymes active at low temperatures for growth and infection. Basidiomycetous
snow molds produce extracellular antifreeze proteins. Their physiological significance is to keep the extracellular environment
unfrozen. The psychrophilic ascomycete Sclerotia borealis shows normal mycelial growth under frozen conditions, which is faster than that on unfrozen media at optimal growth temperature.
This fungus does not produce extracellular antifreeze proteins, but osmotic stress tolerance enables the fungus to grow at
subzero temperatures. In conclusion, different taxa of snow molds have different strategies to adapt under snow cover. 相似文献
288.
Hai-Nan Su Bin-Bin Xie Xiu-Lan Chen Jin-Xia Wang Xi-Ying Zhang Bai-Cheng Zhou Yu-Zhong Zhang 《Journal of applied phycology》2010,22(1):65-70
Allophycocyanin (APC) is a minor component of phycobiliproteins in cyanobacteria and red algae. This paper describes a simple
and inexpensive extracting method for isolating APC from Spirulina (Arthrospira) platensis with high efficiency. The crude phycobiliprotein extract was pretreated by ammonium sulfate fractionation. Then, by adding
hydroxylapatite into crude phycobiliprotein extract dissolved in 20 mM phosphate buffer (pH 7.0), APC was selectively adsorbed
by hydroxylapatite but C-phycocyanin (C-PC) was not. The hydroxylapatite was collected and APC was extracted from the crude
phycobiliprotein extract. Then, the enriched APC was washed off from the hydroxylapatite using 100 mM phosphate buffer (pH 7.0).
In this simple extracting method it was easy to remove C-PC and isolate APC in large amounts. The absorbance ratio A
650/A
280 of extracted APC reached 2.0. The recovery yield was 70%, representing 4.61 mg · g−1 wet weight. The extracted APC could be further purified by a simple anion-exchange chromatography with a pH gradient from
5.6 to 4.0. The absorbance ratio A
650/A
280 of the purified APC reached 5.0, and the overall recovery yield was 43%, representing 2.83 mg · g−1 wet weight. Its purity was confirmed by native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE. 相似文献
289.
B. Akbar John B. R. Nelson Hassan I. Sheikh S. G. Cheung Yusli Wardiatno Bisnu Prasad Dash Keiji Tsuchiya Yumiko Iwasaki Siddhartha Pati 《Biodiversity and Conservation》2018,27(14):3573-3598
Horseshoe crabs are the only extant xiphosurans and are believed to be morphologically unchanged for more than 200 million years. Of the four extant species namely, Limulus polyphemus, Tachypleus tridentatus, Tapinauchenius gigas and Carcinoscorpius rotundicauda, the latter three are found in Asian waters. Recent evidences showed that Asian horseshoe crabs are facing serious threats such as degradation of their spawning grounds and habitat, environmental pollution, overexploitation as a culinary delicacy and biomedical bleeding practices. Baseline data on the distribution and existing population of the wild horseshoe crabs remain poorly known in several Asian regions. Several studies have clearly revealed that pressure due to over-fishing of wild stock has increased tremendously in the last decade. Due to an increase in demand for Tachypleus Amebocyte Lysate (TAL) analogous to Limulus Amebocyte Lysate (LAL) in the United States, there is an urgent need to comprehensively address their fishing and conservation measures in the Asian region. This review addresses the overall studies on three species of Asian horseshoe crabs in relation to their fishing practices, local exploitation of their wild stock either for human consumption (or) by biomedical industries. The authors have structured the discussion on an international scale to address the existing problems in fishing and conservation of horseshoe crabs. Since no specific regulatory force or legislative protection act or a policy to preserve their natural stock are available to this date, this paper strongly recommends representative countries to include horseshoe crabs under their wildlife protection act to avoid further unsustainable exploitation of their wild populations. 相似文献
290.
Nine white-rot fungal strains were screened for biodecolourization of brilliant green, cresol red, crystal violet, congo red
and orange II. Dichomitus squalens, Phlebia fascicularia and P. floridensis decolourized all of the dyes on solid agar medium and possessed better decolourization ability than Phanerochaete chrysosporium when tested in nitrogen-limited broth medium. Journal of Industrial Microbiology & Biotechnology (2002) 28, 201–203 DOI: 10.1038/sj/jim/7000222
Received 12 July 2001/ Accepted in revised form 22 October 2001 相似文献