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1.
5种珍稀食药用真菌活性提取物对果蝇寿命影响的研究 总被引:4,自引:0,他引:4
探讨了松茸、栎金钱菌、蜂窝菌、云芝、杏鲍菇活性提取物对果蝇寿命的影响,分别用这5种食药用真菌活性提取物各以5、20g/L的剂量加入培养基中培养果蝇,观察其对果蝇寿命的影响.结果表明,松茸、栎金钱菌、蜂窝菌、云芝、杏鲍菇的活性提取物能显著延长果蝇的平均寿命和半数死亡时间,其平均寿命延长率分别达23.96%、53.22%、23.09%、32.58%、20%.这提示松茸、栎金钱菌、蜂窝菌、云芝、杏鲍菇都具有良好的延寿效果. 相似文献
2.
Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groups 总被引:36,自引:0,他引:36
Peter B. Reich Michael B. Walters David S. Ellsworth James M. Vose John C. Volin Charles Gresham William D. Bowman 《Oecologia》1998,114(4):471-482
Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf
dark respiration rate (R
d) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic
capacity (A
max). However, it is not known whether such scaling, if it exists, is similar among disparate biomes and plant functional types.
We tested this idea by examining the interspecific relationships between R
d measured at a standard temperature and leaf life-span, N, SLA and A
max for 69 species from four functional groups (forbs, broad-leafed trees and shrubs, and needle-leafed conifers) in six biomes
traversing the Americas: alpine tundra/subalpine forest, Colorado; cold temperate forest/grassland, Wisconsin; cool temperate
forest, North Carolina; desert/shrubland, New Mexico; subtropical forest, South Carolina; and tropical rain forest, Amazonas,
Venezuela. Area-based R
d was positively related to area-based leaf N within functional groups and for all species pooled, but not when comparing among
species within any site. At all sites, mass-based R
d (R
d-mass) decreased sharply with increasing leaf life-span and was positively related to SLA and mass-based A
max and leaf N (leaf N
mass). These intra-biome relationships were similar in shape and slope among sites, where in each case we compared species belonging
to different plant functional groups. Significant R
d-mass−N
mass relationships were observed in all functional groups (pooled across sites), but the relationships differed, with higher R
d at any given leaf N in functional groups (such as forbs) with higher SLA and shorter leaf life-span. Regardless of biome
or functional group, R
d-mass was well predicted by all combinations of leaf life-span, N
mass and/or SLA (r
2≥ 0.79, P < 0.0001). At any given SLA, R
d-mass rises with increasing N
mass and/or decreasing leaf life-span; and at any level of N
mass, R
d-mass rises with increasing SLA and/or decreasing leaf life-span. The relationships between R
d and leaf traits observed in this study support the idea of a global set of predictable interrelationships between key leaf
morphological, chemical and metabolic traits.
Received: 23 May 1997 / Accepted: 16 December 1997 相似文献
3.
端粒、端粒酶与细胞寿命及癌症的关系 总被引:1,自引:0,他引:1
关于端粒、端粒酶与细胞寿命及癌症的关系的研究目前已成为分子生物学、基础医学等多个学科共同关注的热点之一,且近几年来的研究工作有了长足的进展。本文综述了多年来此方面在基础理论研究和癌症诊治应用上的主要成果。 相似文献
4.
Abstract.
- 1 Seed beetles (Coleoptera: Bruchidae) are commonly used to study the influence of reproduction on life-span and senescence. To study the physiological trade-off between reproduction and mortality, many experiments rely on manipulating access to oviposition substrates to manipulate the reproductive rate of females.
- 2 The presence of host seeds, independent of reproduction, results in increased mortality of female Cullosobruchus muculutus. This influence on mortality varies between two host seed species, suggesting a role of either allelochemicals or energetic costs associated with behaviour on hosts.
- 3 The influence of host seeds on survivorship, independent of reproduction, confounds the interpretation of cost-of-reproduction studies with seed beetles. This complication must thus be considered in the design and interpretation of life-history studies of seed beetles and other insects.
5.
Summary Five demographical factors influencing the sex ratio of a population are classically considered. The influence of two of them is dependent on the longevity of individuals in the population. The effect of differential age at maturity between males and females is higher for animals with low annual survival, whereas the effect of differential annual survival between males and females is higher for animals with high annual survival. Such a conclusion applied to turtles, which are long life-span animals, allows us to retain differential survival between sexes as a major factor influencing the population sex ratio. 相似文献
6.
The lifeform and the biological production of pure stands ofEichhornia azurea Kunth in three lakes in tropical Brazil were studied. The lifeform ofE. azurea is termed ‘semi-emergent’, because the plant has well developed trailing stems just under the water, and the aerial lamina
emerges with the thick petiole. The density of shoot apices was 9.9, 17.2 and 17.1 m−2 in Lake Dom Helvecio, Lake Jacaré and Lake Carioca, respectively. The mean daily increment of the apical shoot biomass was
between 1.8 and 4.8 g m−2 day−1. The mean leaf life-span in Lake Dom Helvecio, Lake Jacaré and Lake Carioca was estimated to be 78, 49 and 64 days in the
wet season and 73, 70 and 73 days in the dry season, respectively. The stem life-span was estimated to be about 28 months.
Starch content in the current years' stem ranged from 24 to 118 mg g−1 dry matter with fluctuations, the amplitude of which decreased with age. The differences for most of the growth parameters,
such as density of shoot apices, daily increment of biomass and leaf life-span, between dry and wet season are smaller than
those among the three lakes. Both the decrease in daily dry matter production and the increase in leaf life-span occurred
in order from Lake Dom Helvecio to Lake Jacaré and Lake Carioca. The low productivity ofE. azurea is considered to be related to a low leaf area index, a long time interval for the emergence of new leaves, long leaf life-span
and a low capacity for branching. 相似文献
7.
本实验通过研究爬沙虫提取液对果蝇繁殖力及寿命的影响,证实爬沙虫提取液具有增强果蝇的繁殖力和提高雌性果蝇寿命的作用。采用乙醚麻醉法,收集8 h内羽化的成虫,选择个体大小相近的雌雄果蝇,在不同爬沙虫浓度的培养基中培养,统计各组第一子代(first filial generation,F1)果蝇成体的数目及果蝇体重。收集各培养基中果蝇,区分雌雄,在原浓度爬沙虫培养基中培养,每日观察果蝇死亡数,直至全部死亡。结果表明:与对照组比较,各爬沙虫处理组子代果蝇雄体数目均显著增加(P<0.05),2.500%组的子代果蝇雌体数目差异显著(P<0.05)。各爬沙虫处理组刚羽化的果蝇体重极显著高于对照组(P<0.01)。2.500%剂量组果蝇雌体平均寿命极显著增加(P<0.01)。本研究为更好地利用爬沙虫的药用价值提供了参考依据。 相似文献
8.
Curtis D. Holder 《Journal of Biogeography》2000,27(2):311-318
Aim Past studies have investigated differences in leaf life‐spans between deciduous and evergreen species. Environmental controls such as light, temperature, and nutrient and moisture availability explain differences in leaf life‐spans between species. This study examined intraspecific leaf life‐spans across climate and nutrient gradients within the geographical range of Pinus palustris Engelm (longleaf pine) and Pinus elliottii Mill. (slash pine). Location Five study areas in the southeastern United States were selected along the north–south geographical range of Pinus elliottii and Pinus palustris. Methods Leaf life‐span was calculated based on stand inventories and annual litterfall totals for each site, and allometric relationships between d.b.h. and foliar biomass. Results Leaf life‐span of P. elliottii ranged from 1.28 to 1.95 years between sites. Leaf life‐span of P.palustris varied by nearly a factor of 5 between the study site with the lowest and highest value (0.58–2.49 years). anova indicated that leaf life‐spans of P. elliottii were not significantly different among sites. In contrast, anova indicated a significant difference for P. palustris leaf life‐spans among sites (P < 0.05). The Tukey multiple comparisons tests showed that 2 study areas were the only pair of P. palustris sites with a significant difference in leaf life‐spans. Main conclusions The geographical variation in leaf life‐spans between two species illustrates the different phenotypic responses to environmental controls. The variation in leaf life‐spans by individuals of P. palustris across a geographical range illustrated in this study suggests that P. palustris may exhibit a greater phenotypic plasticity than P. elliottii. 相似文献
9.
Samuel E. Schriner Ani Abrahamyan Agnesa Avanessian Irvin Bussel Steven Maler Maral Gazarian 《Free radical research》2013,47(9):836-843
The root extract from Rhodiola rosea has been reported to have numerous health benefits in human and animal studies. Its molecular mechanism is currently unknown; however, it has been suggested to act as an antioxidant. This study found that a formulation of R. rosea extract, SHR-5, from the Swedish Herbal Institute (SHI) could extend both mean (24% in both sexes) and maximum (16% in males and 31% in females) life span in Drosophila melanogaster when compared to controls. It also found that it lowered mitochondrial superoxide levels and afforded elevated protection against the superoxide generator paraquat in both sexes. The extract SHR-5 did not alter the activities of the major antioxidant enzymes, the superoxide dismutases or catalase, nor did it afford protection against H2O2 or soluble iron. These results present a decrease in endogenous superoxide levels as a possible mode of action for the root extract of R. rosea. 相似文献
10.
The aim of this study was to investigate the toxic effects of aluminum (A1) on the model organism-Drosophila melanogaster. The study is especially concerned with the effects of aluminum on the fruit fly's development, life span, and circadian rhythm in rest and activity. Flies were exposed to aluminum in concentrations from 40 to 280 mg/kg in rearing media or the flies were raised on control medium. Moreover, the life span of insects exposed to aluminum containing 40, 120, or 240 mg/kg of A1 in the medium, only during their larval development, during the whole life cycle and only in their adult life was tested. To check if aluminum and aging cause changes in D. melanogaster behavior, the locomotor activity of flies at different ages was recorded. Results showed that aluminum is toxic in concentrations above 160 mg/kg in the rearing medium. Depending on A1 concentration and time of exposure, the life span of the flies was shortened. At intermediate concentrations (120 mg/kg), however, A1 had a stimulating effect on males increasing their life span and level of locomotor activity. At higher concentration the aluminum exposure increased or decreased the level of locomotor activity ofD. melanogaster depending on age of flies. In addition, in the oldest insects reared on aluminum supplemented media and in mid-aged flies reared on the highest concentration of A1 the daily rhythm of activity was disrupted. 相似文献