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111.
The green alga Parietochloris incisa contains a significant amount of the nutritionally valuable polyunsaturated fatty acid and arachidonic acid (AA) and is being considered for mass cultivation for commercial AA production. This study was primarily aimed to define a practical medium formulation that can be used in commercial mass cultivation that will contribute to a substantial increase in the AA productivity of P. incisa with concomitant reduction of nutritional cost. The effect of nutrient limitation on growth and AA content of this microalga was explored in a batch culture in outdoor conditions using a vertical tubular photobioreactor. The study was conducted in two parts: the first was primarily focused on the effect of different nitrogen concentration on growth and AA content and the second part compares nitrogen deprivation, combination of nitrogen and phosphorus deprivation, and combined overall nutrient limitations at different levels of deprivation under low and high population densities. Since complete nitrogen deprivation hampers lipid and AA accumulation of P. incisa, thus, a critical value of nitrogen supply that will activate AA accumulation must be elucidated under specific growth conditions. Under the present experimental conditions, 0.5?g(-1) sodium nitrate obtained a higher AA productivity and volumetric yield relative to the nitrogen-deprived culture corresponding to 36.32?mg?L(-1)?day(-1) and 523.19?mg?L(-1). The combined nitrogen and phosphorus limitation seemed to enhance AA productivity better than nitrogen deprivation alone. The effect of overall nutrient limitation indicates that acute nutrient deficiency can trigger rapid lipid and AA syntheses. The effect of light as a consequence of culture cell density was also discussed. This study therefore shows that the nutrient cost can be greatly reduced by adjusting the nutrient levels and culture density to induce AA accumulation in P. incisa. 相似文献
112.
Hunt T Atherton-Watson HC Axford J Collingwood SP Coote KJ Cox B Czarnecki S Danahay H Devereux N Howsham C Hunt P Paddock V Paisley D Young A 《Bioorganic & medicinal chemistry letters》2012,22(2):929-932
We report the identification of a novel series of human epithelial sodium channel (ENaC) blockers that are structurally distinct from the pyrazinoyl guanidine chemotype found in prototypical ENaC blockers such as amiloride. Following a rational design hypothesis a series of quaternary amines were prepared and evaluated for their ability to block ion transport via ENaC in human bronchial epithelial cells (HBECs). Compound 11 has an IC(50) of 200nM and is efficacious in the Guinea-pig tracheal potential difference (TPD) model of ENaC blockade with an ED(50) of 44μgkg(-1) at 1h. As such, pyrazinoyl quaternary amines represent the first examples of a promising new class of human ENaC blockers. 相似文献
113.
Hazel J. Hunt Nicholas C. Ray George Hynd Jon Sutton Mohammed Sajad Elizabeth O’Connor Shahadat Ahmed Peter Lockey Steve Daly Gerry Buckley Robin D. Clark Robert Roe Christine Blasey Joe Belanoff 《Bioorganic & medicinal chemistry letters》2012,22(24):7376-7380
We report the optimization of a series of non-steroidal GR antagonists that led to the identification of compound 7. This compound is efficacious when dosed orally in an olanzapine-induced weight gain model in rats. 相似文献
114.
Hazel J. Nichols Neil R. Jordan Gabriel A. Jamie Michael A. Cant Joseph I. Hoffman 《Molecular ecology》2012,21(21):5348-5362
The relatedness structure of animal populations is thought to be a critically important factor underlying the evolution of mating systems and social behaviours. While previous work has shown that population structure is shaped by many biological processes, few studies have investigated how these factors vary over time. Consequently, we explored the fine‐scale spatiotemporal genetic structure of an intensively studied population of cooperatively breeding banded mongooses (Mungos mungo) over a 10‐year period. Overall population structure was strong (average FST = 0.129) but groups with spatially overlapping territories were not more genetically similar to one another than noncontiguous groups. Instead, genetic differentiation was associated with historical group‐fission (budding) events, with new groups diverging from their parent groups over time. Within groups, relatedness was high within but not between the sexes, although the latter increased over time since group formation due to group founders being replaced by philopatric young. This trend was not mirrored by a decrease in average offspring heterozygosity over time, suggesting that close inbreeding may often be avoided, even when immigration into established groups is virtually absent and opportunities for extra‐group matings are rare. Fine‐scale spatiotemporal population structure could have important implications in social species, where relatedness between interacting individuals is a vital component in the evolution of patterns of inbreeding avoidance, reproductive skew and kin‐selected helping and harming. 相似文献
115.
Although rarely acknowledged, our understanding of how competition is modulated by environmental drivers is severely hampered by our dependence on indirect measurements of outcomes, rather than the process of competition. To overcome this, we made direct measurements of plant competition for soil nitrogen (N). Using isotope pool-dilution, we examined the interactive effects of soil resource limitation and climatic severity between two common grassland species. Pool-dilution estimates the uptake of total N over a defined time period, rather than simply the uptake of 15N label, as used in most other tracer experiments. Competitive uptake of N was determined by its available form (NO3
− or NH4
+). Soil N availability had a greater effect than the climatic conditions (location) under which plants grew. The results did not entirely support either of the main current theories relating the role of competition to environmental conditions. We found no evidence for Tilman''s theory that competition for soil nutrients is stronger at low, compared with high nutrient levels and partial support for Grime''s theory that competition for soil nutrients is greater under potentially more productive conditions. These results provide novel insights by demonstrating the dynamic nature of plant resource competition. 相似文献
116.
Marzetti E Lees HA Manini TM Buford TW Aranda JM Calvani R Capuani G Marsiske M Lott DJ Vandenborne K Bernabei R Pahor M Leeuwenburgh C Wohlgemuth SE 《PloS one》2012,7(2):e32829
Background
Preclinical studies strongly suggest that accelerated apoptosis in skeletal myocytes may be involved in the pathogenesis of sarcopenia. However, evidence in humans is sparse. In the present study, we investigated whether apoptotic signaling in the skeletal muscle was associated with indices of muscle mass and function in older persons.Methodology/Principal Findings
Community-dwelling older adults were categorized into high-functioning (HF) or low-functioning (LF) groups according to their short physical performance battery (SPPB) summary score. Participants underwent an isokinetic knee extensor strength test and 3-dimensional magnetic resonance imaging of the thigh. Vastus lateralis muscle samples were obtained by percutaneous needle biopsy and assayed for the expression of a set of apoptotic signaling proteins. Age, sex, number of comorbid conditions and medications as well as knee extensor strength were not different between groups. HF participants displayed greater thigh muscle volume compared with LF persons. Multivariate partial least squares (PLS) regressions showed significant correlations between caspase-dependent apoptotic signaling proteins and the muscular percentage of thigh volume (R2 = 0.78; Q2 = 0.61) as well as gait speed (R2 = 0.81; Q2 = 0.56). Significant variables in the PLS model of percent muscle volume were active caspase-8, cleaved caspase-3, cytosolic cytochrome c and mitochondrial Bak. The regression model of gait speed was mainly described by cleaved caspase-3 and mitochondrial Bax and Bak. PLS predictive apoptotic variables did not differ between functional groups. No correlation was determined between apoptotic signaling proteins and muscle strength or quality (strength per unit volume).Conclusions/Significance
Data from this exploratory study show for the first time that apoptotic signaling is correlated with indices of muscle mass and function in a cohort of community-dwelling older persons. Future larger-scale studies are needed to corroborate these preliminary findings and determine if down-regulation of apoptotic signaling in skeletal myocytes will provide improvements in the muscle mass and functional status of older persons. 相似文献117.
Turner RM Lloyd-Jones M Anumba DO Smith GC Spiegelhalter DJ Squires H Stevens JW Sweeting MJ Urbaniak SJ Webster R Thompson SG 《PloS one》2012,7(2):e30711
Background
To estimate the effectiveness of routine antenatal anti-D prophylaxis for preventing sensitisation in pregnant Rhesus negative women, and to explore whether this depends on the treatment regimen adopted.Methods
Ten studies identified in a previous systematic literature search were included. Potential sources of bias were systematically identified using bias checklists, and their impact and uncertainty were quantified using expert opinion. Study results were adjusted for biases and combined, first in a random-effects meta-analysis and then in a random-effects meta-regression analysis.Results
In a conventional meta-analysis, the pooled odds ratio for sensitisation was estimated as 0.25 (95% CI 0.18, 0.36), comparing routine antenatal anti-D prophylaxis to control, with some heterogeneity (I 2 = 19%). However, this naïve analysis ignores substantial differences in study quality and design. After adjusting for these, the pooled odds ratio for sensitisation was estimated as 0.31 (95% CI 0.17, 0.56), with no evidence of heterogeneity (I 2 = 0%). A meta-regression analysis was performed, which used the data available from the ten anti-D prophylaxis studies to inform us about the relative effectiveness of three licensed treatments. This gave an 83% probability that a dose of 1250 IU at 28 and 34 weeks is most effective and a 76% probability that a single dose of 1500 IU at 28–30 weeks is least effective.Conclusion
There is strong evidence for the effectiveness of routine antenatal anti-D prophylaxis for prevention of sensitisation, in support of the policy of offering routine prophylaxis to all non-sensitised pregnant Rhesus negative women. All three licensed dose regimens are expected to be effective. 相似文献118.
Amy N. Spiegel E. Margaret Evans Brandy Frazier Ashley Hazel Medha Tare Wendy Gram Judy Diamond 《Evolution》2012,5(1):43-61
We examined whether a single visit to an evolution exhibition contributed to conceptual change in adult (n?=?30), youth, and child (n?=?34) museum visitors?? reasoning about evolution. The exhibition included seven current research projects in evolutionary science, each focused on a different organism. To frame this study, we integrated a developmental model of visitors?? understanding of evolution, which incorporates visitors?? intuitive beliefs, with a model of free-choice learning that includes personal, sociocultural, and contextual variables. Using pre- and post-measures, we assessed how visitors?? causal explanations about biological change, drawn from three reasoning patterns (evolutionary, intuitive, and creationist), were modified as a result of visiting the exhibition. Whatever their age, background beliefs, or prior intuitive reasoning patterns, visitors significantly increased their use of explanations from the evolutionary reasoning pattern across all measures and extended this reasoning across diverse organisms. Visitors also increased their use of one intuitive reasoning pattern, need-based (goal-directed) explanations, which, we argue, may be a step toward evolutionary reasoning. Nonetheless, visitors continued to use mixed reasoning (endorsing all three reasoning patterns) in explaining biological change. The personal, socio-cultural, and contextual variables were found to be related to these reasoning patterns in predictable ways. These findings are used to examine the structure of visitors?? reasoning patterns and those aspects of the exhibition that may have contributed to the gains in museum visitors?? understanding of evolution. 相似文献
119.
120.
Summary The first occurrence of the genus Metarungia Baden (Acanthaceae) in west Africa is recorded with the discovery of an isolated population of the widespread eastern African taxon M. pubinervia (T. Anderson) Baden in eastern Nigeria. The conservation status of this species is discussed. 相似文献