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991.
The pike, Esox lucius Linnaeus, is a predatory fish that supports important fisheries and could substantially impact prey populations around the
temperate northern hemisphere. Consumption of prey by pike is most readily estimated using the energy budget to calculate
food intake indirectly using estimates of growth rate and metabolism. Resting metabolic rate, R
s, is a particularly important component of such calculations. Here, the available estimates of R
s are reviewed and compared. Scaling coefficients for variation with body mass are consistent between the two studies in which
they have been derived (0.81, 0.82). However, the effect of temperature on R
s markedly varies among studies (Q
10 from 1.73 to 4.80). There is substantial variation in R
s (twofold to fourfold) among studies when temperature and fish size are accounted for. This variation is shown to have a large
effect on energy budget calculations of energy intake and to be sufficient to account for imbalances in published budgets.
These effects depend on age of pike and season; in one energy budget model, a 50% reduction in R
s resulted in decrease of 19–42% in estimated energy intake of pike. Potential causes of among-study variation in R
s are discussed and it is recommended that standard techniques by applied in the future to differentiate between genuine biological
variation among populations and experimental factors.
Guest editors: J. M. Farrell, C. Skov, M. Mingelbier, T. Margenau & J. E. Cooper
International Pike Symposium: Merging Knowledge of Ecology, Biology, and Management for a Circumpolar Species 相似文献
992.
Shenghao Liu Xiaohang Huang Chenlin Liu Bailin Cong Guang Han 《Journal of applied phycology》2008,20(1):29-34
Whole-cell patch-clamp techniques were used to study ion channels of a marine alga. High quality protoplasts suitable for
electrophysiological studies were isolated from the green marine alga, Ulva pertusa, using enzyme mixtures consisting of cellulase and abalone power and identified by calcofluor fluorescence. The vitality
of protoplasts varied depending on the alga growth stage, and those isolated from younger tissue in March maintained a high
vitality with high sealing success rate compared with protoplasts isolated from mature or non-growing plants in August or
November. In the whole-cell configuration, large inward currents were elicited by negative voltage pulses. The voltage-dependent
component was predominantly carried by Cl−, as confirmed by the use of the Cl− channel inhibitor DIDS and reversal potential of current-voltage plots. This evidence suggests that hyperpolarization-activated
Cl− permeable channels are responsible for the influx of Cl− into U. pertusa cells. Voltage-dependent outward currents were also recorded in several protoplasts, and their properties need further investigation. 相似文献
993.
Huang X Li Q Zhang Y Lü Q Guo L Huang L He Z 《Cellular and molecular neurobiology》2008,28(4):559-568
1. The neuroprotective effect of cactus polysaccharide (CP) on oxygen and glucose deprivation (OGD) and reoxygenation (REO)-induced
damage in the cortical and hippocampal slices of rat brain was investigated. 2. Cell viability was evaluated by using the
2, 3, 5-triphenyl tetrazolium chloride (TTC) method. The fluorescence of propidium iodide (PI) staining was used for quantification
of cellular survival, and lactate dehydrogenase (LDH) activity in incubation medium was assessed by LDH assay to evaluate
the degree of injury. 3. The OGD ischemic condition significantly decreased cellular viability and increased LDH release in
the incubation medium. CP (0.2 mg/l∼2 mg/l) protected brain slices from OGD injury in a dosage dependent manner as demonstrated
by increased A 490 value of TTC, decreased PI intensity and LDH release. At the above concentration, CP also prevented the increase of nitric
oxide (NO) content and inducible nitric oxide synthase (iNOS) activity induced by OGD. 4. CP can protect the brain slices
(cortical and hippocampus) against injury induced by OGD. Its neuroprotective effect may be partly mediated by the NO/iNOS
system induced by OGD insult.
Xianju Huang and Qin Li have contributed equally to this article. 相似文献
994.
The diversity of heterotrophic bacterial isolates of three commercial and two homemade composts was studied. The commercial
composts were produced from poultry litter (PC), sewage sludge (SC), municipal solid waste (MC), and homemade composts (thermal
compost [DC] and vermicompost [VC]) from food wastes. The taxonomic and physiological diversity of the heterotrophic culturable
bacteria was assessed using phenotypic and genotypic characterization and the analysis of the partial 16S rRNA gene sequence.
Composts DC and SC presented the higher genotypic diversity, as could be inferred from the number of distinct genotypic patterns
observed, 28 and 21, respectively. Gram-positive bacteria, mainly Firmicutes, were predominant in all the composts. Some organisms related with taxa rarely reported in composts, as Rhodanobacter spathiphylli, Moraxella osloensis, Lysobacter, Corynebacterium, Pigmentiphaga kullae, and new taxa were also isolated. The highest relative proportion of isolates able to degrade starch was found in compost
SC (>70%), to degrade gelatine in compost DC (>70%), to degrade Tween 80 in compost PC (>90%), and to degrade poly-epsilon-caprolactones
in compost DC (>80%). Compost MC presented the lowest relative proportions of isolates able to degrade starch (<25%), gelatine
(<20%), and poly-epsilon-caprolactone (<40%). When compared with the others, the homemade composts presented higher relative
proportions of Gram-positive isolates able to inhibit the target organisms Staphylococcus aureus, Enterococcus
faecalis, Escherichia coli, or Pseudomonas aeruginosa. In compost MC, none of the Gram-positive isolates was able to inhibit those targets. 相似文献
995.
Influences of calcium deficiency and cerium on the conversion efficiency of light energy of spinach 总被引:2,自引:0,他引:2
Chloroplast absorbs light energy and transforms it into electron energy, and then converts it into active chemical energy and stable chemical energy. In the present paper, we investigated the effects of Ce(3+), which has the most significant catalytic effects and similar characteristics with Ca(2+), on light energy conversion of spinach chloroplasts under Ca(2+)-deficient stress. The results illuminated that the Hill reaction activity, electron flow both photosystems and photophosphorylation rate of spinach chloroplasts reduced significantly under Ca(2+)-deficient condition, and activities of Mg(2+)-ATPase and Ca(2+)-ATPase on the thylakoid membrane were severely inhibited. Meanwhile, the activity of Rubisco, which is the key enzyme of photosynthetic carbon assimilation, was also prohibited. However, Ce(3+) decreased the inhibition of calcium deprivation the electron transport rate, the oxygen evolution rate, the cyclic and noncyclic photophosphorylation, the activities of Mg(2+)-ATPase, Ca(2+)-ATPase and Rubisco of spinach chloroplasts. All above implied that Ca(2+)-depletion could disturb light energy conversion of chloroplasts strongly, which could be reversed by Ce(3+). 相似文献
996.
Intracellular toxic effects of the dequalinium-induced protofibrils of alpha-synuclein have been investigated with the yeast system expressing alpha-synuclein-GFP fusion protein in single copy, which appears in the green halo around the plasma membrane. Intracellular responses of the green fluorescent protein were analyzed as the cells were treated with dequalinium (DQ) and lactacystin. Yeast cells expressing alpha-synuclein-GFP were susceptible to both compounds in alpha-synuclein-dependent manner. Upon DQ treatment, the green halo became smeared throughout the cytoplasm while lactacystin induced a few discrete green dots, reflecting intracellular formation of the protofibrils and the protein inclusions, respectively. The DQ-treated yeast cells were intensely stained with the nucleic acid stains of cell-permeable Hoechst 33342 and cell-impermeable propidium imidione, indicating that nucleus has been disrupted in addition to plasma membrane destabilization. Those DQ-treated yeast cells, however, still contained active mitochondria identified with MitoTracker Red. Therefore, the DQ-induced protofibrillar state of alpha-synuclein-GFP has been suggested to cause the nuclear damage either independently or in combination with the membrane destabilization without affecting mitochondria. 相似文献
997.
Leibing A 《Culture, medicine and psychiatry》2008,32(2):177-193
When, in the 1980s, Alzheimer's disease became a disease of major public concern, 'personhood' also became an important, related topic of discussion. Those in caring professions (psychology, social work, etc.) and caregiver groups advocated for the 'person within' who was getting lost in a forgetful body and in a reductionist biomedical system. This essay aims to critically approach the dualism of this kind of argument by focusing on the moral positioning of claims such as personhood or biomedical reductionism. 相似文献
998.
Jin B Wang L Wang J Teng NJ He XD Mu XJ Wang YL 《Plant biology (Stuttgart, Germany)》2010,12(6):853-862
The formation and ecological roles of sterile flowers in flowering plants are interesting issues in floral biology and evolution. Here, we investigated the morphological and anatomical characteristics of both fertile and sterile flowers of Viburnum macrocephalum f. keteleeri, a self-incompatible and insect-pollinated shrub, during different developmental stages of flowers. In addition, pollinator visitation rates and fruit set were determined in intact inflorescences and those with sterile flowers removed. The results indicate that sterile and fertile flowers were developmentally similar during early developmental stages, and that development of the flower types diverged about 15 days before flowering. In addition, pollinator visitation rates, number of pollen grains on stigmas and fruit set were significantly higher in inflorescences with sterile flowers than those without sterile flowers. The results suggest that sterile flowers of this species evolved from fertile flowers under long-term selective pressure, and play a crucial role in enhancing reproductive success through effectively attracting pollinators to the plant and thus enhancing fruit set. 相似文献
999.
1000.
Genotoxic air pollution is ubiquitous in urban and industrial areas. A variety of studies has linked human exposure to air
pollution with a number of different somatic cell endpoints including cancer. However, the potential for inducing mutations
in the human germline remains unclear. Sentinel animal studies of germline mutations at tandem-repeat loci (specifically minisatellites
and expanded simple tandem repeats) have recently provided proof of principle that germline mutations can be induced in vertebrates
(birds and mice) by air pollution under ambient conditions. Although humans may also be susceptible to induced germline mutations
in polluted areas, uncertainties regarding causative agents, doses, and mutational mechanisms at repetitive DNA loci currently
preclude extrapolation from animal data to the evaluation of human risk. Nevertheless, several recent studies have linked
air pollution exposure to DNA damage in human sperm, indicating that our germ cells are not impervious to the genotoxic effects
of air pollution. Thus, both sentinel animal and human studies have raised the possibility that ambient air pollution may
increase human germline mutation rates, especially at repetitive DNA loci. Given that some human genetic conditions appear
to be modulated by length mutations at tandem-repeat loci (e.g. HRAS1 cancers, type 1 diabetes, etc.), there is an urgent need for extensive study in this area. Research should be primarily focused
upon: (1) the direct measurement of mutation frequencies at repetitive DNA loci in human male germ cells as a function of
air pollution exposure, (2) large-scale epidemiology studies of inherited disorders and tandem-repeat associated genetic conditions
and air pollution, and (3) the characterization of mutational mechanisms at hypervariable tandem-repeat loci.
相似文献
Christopher M. SomersEmail: |