作物分枝的分子调控研究进展

分枝的数量及角度是决定作物株型的重要农艺性状。有效分枝数决定着作物的穗数或荚果数,进而决定着作物的产量;而分枝角度与光合效率、种植密度和抗病性密切相关,不仅影响作物的产量,也会影响作物的品质。由于分枝在作物生产中具有十分重要的作用,吸引了越来越多的研究者的注意,多个与分枝性状相关的关键基因被鉴定,分枝数目调控的分子机制研究取得了重要进展。过去的研究表明作物分枝受严格的遗传调控,同时也受环境条件的影响。综述了与作物分枝性状相关的基因克隆、表达、功能和分子调控机理方面的研究进展,以及环境因素对分枝的影响,探讨分枝调控在作物品种改良中的应用。     

Mathematica numerical simulation of peristaltic biophysical transport of a fractional viscoelastic fluid through an inclined cylindrical tube

This paper studies the peristaltic transport of a viscoelastic fluid (with the fractional second-grade model) through an inclined cylindrical tube. The wall of the tube is modelled as a sinusoidal wave. The flow analysis is presented under the assumptions of long wave length and low Reynolds number. Caputo's definition of fractional derivative is used to formulate the fractional differentiation. Analytical solutions are developed for the normalized momentum equations. Expressions are also derived for the pressure, frictional force, and the relationship between the flow rate and pressure gradient. Mathematica numerical computations are then performed. The results are plotted and analysed for different values of fractional parameter, material constant, inclination angle, Reynolds number, Froude number and peristaltic wave amplitude. It is found that fractional parameter and Froude number resist the flow pattern while material constant, Reynolds number, inclination of angle and amplitude aid the peristaltic flow. Furthermore, frictional force and pressure demonstrate the opposite behaviour under the influence of the relevant parameters emerging in the equations of motion. The study has applications in uretral biophysics, and also potential use in peristaltic pumping of petroleum viscoelastic bio-surfactants in chemical engineering and astronautical applications involving conveyance of non-Newtonian fluids (e.g. lubricants) against gravity and in conduits with deformable walls.     

Selective burning of forest vegetation in Canton Ticino (southern Switzerland)

Abstract

Detailed knowledge of factors controlling fire regime is a prerequisite for efficient fire management. We analyzed the fire selectivity of given forest vegetation classes both in terms of fire frequency and fire size for the present fire regime (1982–2005) in Canton Ticino (southern Switzerland). To this end, we investigated the dataset in four categories (all fires, anthropogenic winter fires, anthropogenic summer fires, and natural summer fires) and performed 1000 random Monte Carlo simulations on frequency and size. Anthropogenic winter and summer fires have a similar selectivity, occurring mostly at low elevations in chestnut stands, broadleaved forests, and in the first 50 m from the forest edge. In winter half of the fires in chestnut stands are significantly larger than 1.0 ha and the average burnt area in some coniferous forests tends to be high. Lightning fires seem to occur more frequently in spruce stands and less often in the summer‐humid chestnut and beech stands and the 50–100 m buffer area. In beech forests, in mixed forests, and in the spruce stands affected by natural fire in summer, the fires tend to be small in size. The selectivity observed, especially the selectivity of anthropogenic fires in terms of fire frequency, seems to be also related to geographical parameters such as altitude and aspect, and to anthropogenic characteristics such as closeness to roads or buildings.     

Implementing a spatial model of Urban Carrying Capacity Load Number (UCCLN) to monitor the environmental loads of urban ecosystems. Case study: Tehran metropolis

The non-linear, unexpected and severe responses of ecosystems to the environmental changes crossing ecological thresholds or environmental limits, necessitate the regular monitoring of the human-induced pressures to the urban ecosystems. The present study aims to introduce a spatial decision support system for sustainable environmental planning and management of urban ecosystems by establishing an Urban Carrying Capacity Load Number model (UCCLN) based on carrying capacity concepts and sustainability principles .This model, by applying 30 temporal and spatial indicators continuously monitors the environmental loads on the urban ecosystems. Environmental load was represented by load number index. It was calculated in each zone of study area (urban districts). Geographical Information System (GIS) was used to establish UCCLN model and Spatial Decision Support System (SDSS). The study area was Tehran metropolis, the capital of Iran. The results showed that none of the 115 urban districts of Tehran had optimal Total Load Number (TLN) ranging from (10 to100); 7 districts (6%) had low-to-medium range of TLN (TLN = 100–200); 11 districts (9.5%) had medium-to-high range (TLN = 200–300); 57 districts (49.5%) had high-to-very high range (TLN = 300–400); 40 districts (34.7%) had the TLN range of very high-to-critical (TLN = 400–500); and none of them had the TLN of 500. Furthermore, the results revealed that Tehran has already overshot its ecological thresholds. Not only most of the 30 indicators of environmental pressure in most of the districts (85%) had high DCC and LN scores, but also most of the 115 districts obtained high DCC, and as a result LN scores. The need for developing more efficient urban planning and management strategies to cope with the increasing environmental loads in the study area is inevitable.     

Proteomics in translational cancer research: biomarker discovery for clinical applications

This special focus issue of Expert Review of Proteomics invites key opinion leaders to report their recent findings and views on the important topic of translating potential proteomic biomarkers to clinically useful, regulator-approved biomarkers: a challenging journey. The issue also highlights the difficulties associated with and the way forward in the discovery of proteomic cancer biomarkers for clinical applications, as well as presenting recent original research in the field.     

Plant functional traits and community assembly along interacting gradients of productivity and fragmentation

Quantifying the association of plant functional traits to environmental gradients is a promising approach for understanding and projecting community responses to land use and climatic changes. Although habitat fragmentation and climate are expected to affect plant communities interactively, there is a lack of empirical studies addressing trait associations to fragmentation in different climatic regimes.In this study, we analyse data on the key functional traits: specific leaf area (SLA), plant height, seed mass and seed number. First, we assess the evidence for the community assembly mechanisms habitat filtering and competition at different spatial scales, using several null-models and a comprehensive set of community-level trait convergence and divergence indices. Second, we analyse the association of community-mean traits with patch area and connectivity along a south–north productivity gradient.We found clear evidence for trait convergence due to habitat filtering. In contrast, the evidence for trait divergence due to competition fundamentally depended on the null-model used. When the null-model controlled for habitat filtering, there was only evidence for trait divergence at the smallest sampling scale (0.25 m × 0.25 m). All traits varied significantly along the S–N productivity gradient. While plant height and SLA were consistently associated with fragmentation, the association of seed mass and seed number with fragmentation changed along the S–N gradient.Our findings indicate trait convergence due to drought stress in the arid sites and due to higher productivity in the mesic sites. The association of plant traits to fragmentation is likely driven by increased colonization ability in small and/or isolated patches (plant height, seed number) or increased persistence ability in isolated patches (seed mass).Our study provides the first empirical test of trait associations with fragmentation along a productivity gradient. We conclude that it is crucial to study the interactive effects of different ecological drivers on plant functional traits.     

Sub‐lethal effects of monoterpenes on reproduction by mountain pine beetles

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Systematic biases in DNA copy number originate from isolation procedures

Background

The ability to accurately detect DNA copy number variation in both a sensitive and quantitative manner is important in many research areas. However, genome-wide DNA copy number analyses are complicated by variations in detection signal.

Results

While GC content has been used to correct for this, here we show that coverage biases are tissue-specific and independent of the detection method as demonstrated by next-generation sequencing and array CGH. Moreover, we show that DNA isolation stringency affects the degree of equimolar coverage and that the observed biases coincide with chromatin characteristics like gene expression, genomic isochores, and replication timing.

Conclusion

These results indicate that chromatin organization is a main determinant for differential DNA retrieval. These findings are highly relevant for germline and somatic DNA copy number variation analyses.