Congruence between theory and practice: reduced contamination rate following phenotypic pre-selection within the Breeding without Breeding framework

Wind-pollinated seed orchards are often subjected to pollen intrusion from outside pollen sources. When wind-pollinated seed orchards seed are used to establish progeny trials, the offspring is expected to harbour varying proportion sired by outside sources. Theoretically the magnitude of selection differential between the orchard's population and the contaminant pollen sources will affect the proportion of offspring resulting from outside pollen sources matings. If phenotypic pre-selection is implemented through selecting the top phenotypically ranked individuals from these progeny trials, then it is expected that the proportion of individuals sired by outside pollen sources will be lower within the pre-selected vs. unselected individuals. Here, we present empirical data from two Scots pine progeny trials supporting these theoretical expectations. The observed reduced contamination rate among fingerprinted elite offspring was 3.9 and 4.2%, suggesting a significant reduction in comparison to reported contamination rates between 21 and 70% in Scots pine. Results provide support to the proposed phenotypic pre-selection during the implementation of Breeding without Breeding scheme.     

A conceptual model of the role of excess energy in the maintenance of a riffle–pool sequence

There is much debate over the role of hydraulic ‘reversal’ in the maintenance of riffle–pool sequences in gravel-bed channels. It is, however, generally acknowledged that the pool has the greatest maximum energy during flood flows allowing scour and pool maintenance. Little emphasis has been placed on the reversal period in many previous studies despite its potential importance being noted in the seminal study of Keller [Geol. Soc. Am. Bull. 82 (1971) 753]. This is potentially significant, as reversal may only occur for short periods at the peak of flood hydrographs; hence, the hydraulic argument behind riffle–pool maintenance is based around what is often a marginal energy excess in the pool for a very short period of time. This study uses the magnitude frequency concept of Wolman and Miller [J. Geol. 68 (1960) 54] and applies it to an investigation of the temporal dominance in morphologic unit stream power between a series of four pools and three riffles derived from measured flow and calculated energy slopes on the upland gravel-bed River Rede, Northumberland. The geomorphologically effective flow regime is used to define temporal balances between riffle and pool energy levels. The geomorphic work carried out by riffles and pools, as described by the excess stream power (Ω−Ω_c) capable of transporting the bed sediments, displayed a broad balance for the upstream four units before reducing significantly at pool 3 and rising again for the subsequent two units which appear particularly energetic. These findings contrast with hydraulic theories of riffle–pool maintenance, e.g., Keller [Geol. Soc. Am. Bull. 82 (1971) 753]. For sediments to be transferred through a riffle–pool sequence whilst maintaining a quasi-equilibrium form, the pools should carry out the same amount of work as the riffle upstream in order for it not to fill with sediment. Although stream power reversal did occur for some riffle–pool units, the magnitude and longevity of the reversal did not balance the energy exerted at riffle locations. Armouring and shallow gravel depth at riffle 3 appear to indicate scouring in response to high excess stream power found in this area. However, there was no evidence of sub-dominant pools 3 and 4 filling in response to low stream power.     

Quantification of Aluminum-Induced Changes in Wheat Root Architecture by X-ray Microcomputed Tomography

Root architectural traits are of fundamental importance for plant performance, especially under unfavorable soil conditions. This study examined the effect of aluminum (Al) toxicity in different growing media (nutrient solutions and soil) on root architecture of two wheat (Triticum aestivum L.) cultivars with different Al tolerances. Seedlings were grown in acidic and limed soil and in two contrasting nutrient solutions. Root systems of soil-grown plants were scanned using x-ray microcomputed tomography (µCT) while that of nutrient solution–grown plants were assesses using WinRhizo, 3 and 5 days after planting (DAP), respectively. Aluminum caused significant reduction of all examined root traits (number of seminal roots, root length, length of the longest seminal root, root surface area, and root volume). Growth in acidic soil caused significant reduction in root length, length of the longest seminal root, and root surface area at 5 DAP. Soil-grown plants produced a larger root system compared to plants grown in nutrient solutions. Aluminum toxicity–induced differences of root traits were also found between different nutrient solutions. Beside the well-known reduction of root length, Al toxicity had a profound effect on other root architectural traits. X-ray µCT has revealed root architectural changes under specific conditions of acidic, Al-toxic soil. Differences obtained in Al-induced effects on root architecture between different nutrient solutions as well as between different growing systems emphasize the need for further study of root architecture, especially under specific conditions of Al toxicity in acidic soils.     

辣椒诱导再生及黄瓜花叶病毒外壳蛋白基因转化研究初报

用MS+5mg6BA+0.1mgIBA诱导辣椒子叶外植体分化出叶状体.用MS+3mg6BA+0.2mgIBA诱导出茎芽.再用MS+0.2mgIAA诱导生根,从而得到完整的小植株.直接以子叶外植体为受体,以Ti质粒为载体将CMVcp(黄瓜花叶病毒外壳蛋白)基因转化进辣椒,经再生性培养获得了转基因小植株.     

Early systemic inflammatory response in mice after a single oral gavage with live Escherichia coli is evidenced by increased TNF-alpha and nitric oxide production

Twenty-four female BALB/c mice were orally inoculated with 10(8) CFU Escherichia coli ATCC 25922 and euthanized 2.5, 7, 13 and 25 h post-inoculation. The levels of organ nitric oxide (NO) and plasma endotoxin, TNF-alpha and nitrite/nitrate (NO(x)) were compared to those found in sham-inoculated mice, to evaluate systemic host-response to a low-level oral exposure to Gram-negative bacteria. Organ bacterial culture and immunohistochemistry for iNOS were performed on lungs, liver, kidneys and brain from all mice. Organ NO and plasma TNF-alpha levels were higher in E. coli-inoculated animals, but no differences were detected in plasma endotoxin levels, NO(x) or iNOS immunostaining for any of the animal groups. Single oral gavage with live E. coli stimulates an early systemic immune response in clinically healthy mice as evidenced by increased plasma TNF-alpha and organ NO levels, but bacteremia and endotoxemia are not related to this inflammatory response.