Combined line-cross and half-sib QTL analysis of crosses between outbred lines

Data from an F 2 cross between breeds of livestock are typically analysed by least squares line-cross or half-sib models to detect quantitative trait loci (QTL) that differ between or segregate within breeds. These models can also be combined to increase power to detect QTL, while maintaining the computational efficiency of least squares. Tests between models allow QTL to be characterized into those that are fixed (LC QTL), or segregating at similar (HS QTL) or different (CB QTL) frequencies in parental breeds. To evaluate power of the combined model, data wih various differences in QTL allele frequencies (FD) between parental breeds were simulated. Use of all models increased power to detect QTL. The line-cross model was the most powerful model to detect QTL for FD>0.6. The combined and half-sib models had similar power for FD<0.4. The proportion of detected QTL declared as LC QTL decreased with FD. The opposite was observed for HS QTL. The proportion of CB QTL decreased as FD deviated from 0.5. Accuracy of map position tended to be greatest for CB QTL. Models were applied to a cross of Berkshire and Yorkshire pig breeds and revealed 160 (40) QTL at the 5% chromosome (genome)-wise level for the 39 growth, carcass composition and quality traits, of which 72, 54, and 34 were declared as LC, HS and CB QTL. Fourteen CB QTL were detected only by the combined model. Thus, the combined model can increase power to detect QTL and mapping accuracy and enable characterization of QTL that segregate within breeds.     

Effect of farm management practices in the Bt toxin production by Bt cotton: evidence from farm fields in China

Based on farm field plot level survey data and laboratory test, we examine the determinants of the expression of Bt toxin in China’s Bt cotton production. The results show that the expression of Bt toxin differs significantly among varieties. Even for the same variety the expression of Bt toxin also varies substantially among villages and among farmers in the same village. Econometric analyses show that after controlling for the effects of varieties and locations (or villages), farm management, particular applications of phosphate and potash fertilizers, and manure, has significant positive effects on Bt toxin expression in farmer’s fields. In contrast to previous studies which showed that nitrogen fertilizer has a positive impact on expression of Bt toxin, this study shows that nitrogen fertilizer has no significant impact on expression of Bt toxin in farmer’s fields. On the other hand, the expression of Bt toxin has a positive relationship with phosphate fertilizer, potash fertilizer and manure application.     

Biochar-Induced Priming Effects in Young and Old Poplar Plantation Soils

The priming effect (PE) induced by biochar provides a basis for evaluating its carbon (C) sequestration potential in soils. A 60 days’ laboratory incubation was conducted, which involved the amendment of biochar (1% of soil mass) produced from rice straw at 300ºC (B300) and 500ºC (B500) to young (Y) and old (O) poplar plantation soils, with the aim of studying the responses of biochar-induced PEs to poplar plantation ages. This incubation included six treatments: Y + CK (control), Y + B300, Y + B500, O + CK, O + B300, and O + B500. Carbon dioxide (CO₂) emissions were significantly increased (p < 0.05) in the B300 amended soils, while it was decreased in the B500 amended soils compared to the CK. The primed CO₂ emissions were 2.35 times higher in the Y + B300 than the O + B300 treatments, which was measured to be 18.6 and 5.56 mg C·kg^-1 with relative PEs of 12.4% and 3.35%, respectively. However, there was little difference between the primed CO2 emissions in Y + B500 and O + B500 treatments, which were measured to be -24.9 and -29.6 mg·C·kg^-1 with relative PEs of -16.6% and -17.8%, respectively. Dissolved organic carbon (DOC) was significantly lower in the young poplar plantation soil than that in the old poplar plantation soil regardless of biochar amendment throughout the incubation, indicating greater C-limit of soil microorganisms in the young poplar plantation soil. Using ¹³C isotope tracing, neither B300 nor B500 decreased native soil-derived DOC, which indicated that the negative B500-induced PEs were not due to a reduction in the availability of native soil-derived C. In conclusion, the response of biochar-induced PEs to poplar plantation age depends on biochar types while soil available C indirectly affects biocharinduced PEs. Further studies should focus on how the interactive effects between soil C availability and microbial community impacts biochar-induced PEs.     

Correction to: Strong phosphorus (P)-zinc (Zn) interactions in a calcareous soil-alfalfa system suggest that rational P fertilization should be considered for Zn biofortification on Zn-deficient soils and phytoremediation of Zn-contaminated soils

Plant and Soil - A Correction to this paper has been published: https://doi.org/10.1007/s11104-021-04966-1     

漆酶空间结构、反应机理及应用

漆酶 (EC 1.10.3.2) 属于多铜氧化酶家族,可以催化氧化酚类和芳香类化合物,利用自由基反应机理完成4个电子的转移,并将分子氧还原成水。漆酶具有非常保守的拓扑学结构,结合作者自身工作实践,对漆酶结构与功能的最新研究进展进行综述,其中对漆酶的三维结构、活性中心、催化机理研究和最新的应用进展作重点阐述。     

Precipitation of calcium, magnesium, strontium and barium in tissues of four acacia species (leguminosae: mimosoideae)

Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory.     

Morphologies and elemental compositions of calcium crystals in phyllodes and branchlets of Acacia robeorum (Leguminosae: Mimosoideae)

Background and Aims

Formation of calcium oxalate crystals is common in the plant kingdom, but biogenic formation of calcium sulfate crystals in plants is rare. We investigated the morphologies and elemental compositions of crystals found in phyllodes and branchlets of Acacia robeorum, a desert shrub of north-western Australia.

Methods

Morphologies of crystals in phyllodes and branchlets of A. robeorum were studied using scanning electron microscopy (SEM), and elemental compositions of the crystals were identified by energy-dispersive X-ray spectroscopy. Distributional patterns of the crystals were studied using optical microscopy together with SEM.

Key Results

According to the elemental compositions, the crystals were classified into three groups: (1) calcium oxalate; (2) calcium sulfate, which is a possible mixture of calcium sulfate and calcium oxalate with calcium sulfate being the major component; and (3) calcium sulfate · magnesium oxalate, presumably mixtures of calcium sulfate, calcium oxalate, magnesium oxalate and silica. The crystals were of various morphologies, including prisms, raphides, styloids, druses, crystal sand, spheres and clusters. Both calcium oxalate and calcium sulfate crystals were observed in almost all tissues, including mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex; calcium sulfate · magnesium oxalate crystals were only found in mesophyll and parenchyma cells in phyllodes.

Conclusions

The formation of most crystals was biologically induced, as confirmed by studying the crystals formed in the phyllodes from seedlings grown in a glasshouse. The crystals may have functions in removing excess calcium, magnesium and sulfur, protecting the plants against herbivory, and detoxifying aluminium and heavy metals.     

长岛自然保护区生态系统维护的条件价值评估

长岛自然保护区是典型的海岛自然保护区,迅速发展的捕捞业、养殖业和旅游业不可避免地引起环境污染和资源过度利用等问题,使长岛生态系统可持续发展面临严峻挑战。采用支付卡式的条件价值法,调查并估算了2013年居民和游客对维护长岛自然保护区生态系统的支付意愿,并与2008年的研究结果比较以检验条件价值法的可靠性。结果显示,2013年居民和游客人均最大支付意愿分别为203.77和257.26元/a,分别比2008年增长了7.9%和21.7%。两次支付意愿调查结果的相同点在于居民或游客对各个投标额愿意支付的人数比例在不同年份分布趋势基本一致,不同点在于愿意支付的人数比例明显增加。前者体现在居民对各个投标额的选择比较集中,而游客的选择比较分散;后者表现为居民和游客愿意支付的人数比例增长率分别为20.5%和19.1%。结果表明,采用条件价值法评估长岛自然保护区居民和游客对生态系统维护的支付意愿结果可靠,其评估结果主要受经济收入和环境保护意识的影响。因此,当地政府应在发展经济的基础上,加强对生态环境保护的宣传和教育。     

城郊公路两侧主要森林类型铅含量及分布规律

对南京城郊３１２国道两侧主要森林类型林木不同器官中Ｐｂ含量和分布规律的研究表明,不同树种、同一树种不同器官中Ｐｂ含量有明显差异．火炬松对Ｐｂ污染的净化能力强于杉木、栎树．汽车尾气排放的Ｐｂ污染影响范围在离公路两侧１００ｍ以内,主要在４０ｍ以内范围．有林地土壤由于有林木及林下植被的覆盖,其Ｐｂ含量（尤其是表层０～２０ｃｍ范围内）明显降低,说明林分可有效地降低土壤中Ｐｂ的污染程度．林木不同器官对Ｐｂ尘的吸附率在１８０％～２８１％之间,以叶片吸附能力最强;不同树种比较,以松树吸附率为高     

Involvement of gecko SNAP25b in spinal cord regeneration by promoting outgrowth and elongation of neurites

SNARE complex mediates cellular membrane fusion events essential for neurotransmitter release and synaptogenesis. SNAP25, a member of the SNARE proteins, plays critical roles during the development of the central nervous system via regulation by alternative splicing and protein kinase phosphorylation. To date, little information is available regarding the protein in the spinal cord regeneration, especially for the postnatal highly expressed isoform SNAP25b. In the present study, we characterized gecko SNAP25b, which shared high identity with those of other vertebrates. Expression of gecko SNAP25b was temporally upregulated in both neurons of spinal cord and forming ependymal tube following tail amputation, coinciding with the occurrence of regenerate re-innervation. Overexpression of gecko wild type SNAP25b in the SH-SY5Y and undifferentiated PC12 cells promoted the elongation and outgrowth of neurites, while mutant constructs at Serine¹⁸⁷ resulted in differential effects for which S187A had a promoting role. Knockdown of endogenous SNAP25b affected the formation of neurites, which could be rescued by overexpression of SNAP25b. FM1-43 staining revealed that transfection of S187E mutant construct reduced the recruitment of vesicles. In addition, transfection of gecko SNAP25b in the astrocyte, which is absent from neuronal specific VAMP2, was capable of enhancing process elongation, indicating a potential for various alternative protein combinations. Taken together, our data suggest that gecko SNAP25b is involved in spinal cord regeneration by promoting outgrowth and elongation of neurites in a more extensive protein binding manner.