二穗短柄草叶绿体RNA编辑位点的预测及其鉴定

RNA编辑是陆生植物叶绿体转录后基因表达调控的一种重要方式。为进一步探讨单子叶植物RNA编辑功能及其发生机制,本研究通过生物信息学方法,对二穗短柄草叶绿体的81个蛋白编码基因的RNA编辑位点进行了预测和鉴定分析,结果发现78个基因存在编辑位点,共检测到176个编辑位点,都是C到U的转换。其中ndhB最多,为14个编辑位点。为验证预测结果,利用blast工具比对了NCBI的二穗短柄草EST数据库,最终确定存在于17个基因中的34个编辑位点是真实存在的,其中19个为沉默编辑,15个为有效编辑。与5个不同单子叶禾本科物种18个蛋白编码基因的RNA编辑位点的比较发现,在rpoB-206位点,只有二穗短柄草发生了编辑,且只有ndhD-295(293)为部分编辑位点。     

Effect of salinity on nitrogen metabolism in wheat

Objectives of our studies were to quantify effects of salinity on growth and nitrogen metabolism of wheat and to measure variation in response of different cultivars, hybrids, and classes. Methods and criteria for identifying resistance to salinity in wheat, particularly effects on nitrogen metabolism also were tested. Variation in response to salinity was measured by subjecting seedlings of six wheats to one control treatment (‐0.1 bars) and two stress treatments (‐3.5 and ‐10.4 bars) from NaCl, MgSO₄, and MgCl₂ in hydroponic solutions. Both stress treatments retarded growth; wheats significantly varied at ‐3.5 bars but not at ‐10.4 bars. Stress decreased root and shoot nitrate N and total N contents. Studies with one wheat cultivar showed that salinity decreased activity of nitrate reductase enzyme and stimulated accumulation of proline. Salinity more adversely affected vegetative stages than reproductive stages of plants grown to maturity. We concluded that salinity affected wheat by both osmotic effects and antagonism of nitrate metabolism from chloride. Absolute growth and relative growth at different stress levels were superior to differences in nitrogen metabolism as selection criteria for salinity tolerance.     

Irrigation and Zn fertilizer management improves Zn phyto‐availability in various rice production systems

Zinc (Zn) is an important micronutrient for rice (Oryza sativa L.) production and its deficiency has been observed in various production systems. High grain Zn concentration is equally important for high rice yield and human health. In this work, the effects of Zn fertilization on seedling growth, grain yield, grain Zn concentration, and their association with root traits were studied under alternate wetting and drying (AWD), aerobic rice (AR), system of rice intensification (SRI), and continuous flooding (CF). Zinc fertilization (15 kg ha^?1) improved nursery seedlings chlorophyll and Zn concentrations, root length, and number of roots with highest values observed in CF. At harvesting, maximum plant height, panicle length, total and panicle bearing tillers, and kernel yield were found with Zn addition in AWD and CF rice systems. Mid season drainage provided at maximum tillering and Zn fertilization increased its concentration in leaves, culms, panicles, and grains under CF and AR at physiological maturity. Most of Zn applied was allocated into culms and panicles, nevertheless, a significant increase in grain Zn concentration was also observed in all production systems. Association of leaf Zn with grain Zn concentration was stronger than with culm and panicle Zn. The results indicate that Zn application after rice nursery transplanting is more important for grain Zn enrichment in all rice systems than for increase in grain yield in all systems except AWD where grain yield was also increased. More grain yield in CF and AWD as compared to SRI and AR can also be attributed to decreased spikelet sterility and to better Zn phyto‐availability in these rice systems at physiological maturity.     

典型黑土区坡耕地退化程度诊断与评价

为了对黑土区坡耕地退化程度进行全面、综合、客观的诊断与评价,通过文献计量法和频度分析法对国内外耕地退化评价文献内的高频指标进行了统计分析,建立了适用于东北典型黑土区坡耕地退化程度诊断与评价的指标体系(TIS)。同时以拜泉县为研究区域,通过聚类分析建立了土壤退化程度诊断与评价最小指标集(MIS)。结果表明:(1)TIS共包括物理、化学、生物和侵蚀特征因子4类共11项指标:腐殖质层厚度、黏粒含量、有机质含量、pH值、坡度、垄坡角、沟壑密度、容重、水稳性大团聚体含量、土壤阳离子交换量和作物产量,其中前6项指标组成了MIS。(2)研究区未退化土壤占12%,轻度退化土壤占12%,中度及以上退化土壤占76%。坡度可能是影响研究区土壤退化的主要因素之一,坡度与垄坡角之间存在协同关系。此外,施用农药、化肥以及连作导致土壤酸化问题突出。     

A 3-Year Adaptation Study of Three Distinct Grapevine Cultivars under Midwestern Field Conditions

Simultaneous responses of American (Concord), European (Pinot Noir), and American-European hybrid (Traminette) cultivars to seasonal and diurnal variation in field environmental conditions were assessed to propose suitable cultivars for potential use for selection and breeding in grapevines in dry areas. ‘Pinot Noir’ had higher gas exchange parameters, higher water potential, and chlorophyll fluorescence, while ‘Concord’ had the lowest values in all three seasons and experienced moderate stress by the end of each season. The dry conditions in 2005 caused water potential to decline sharply compared to values recorded in 2004 and 2006. ‘Pinot Noir’ and ‘Traminette’ exhibited a mild stress, while ‘Concord’ exhibited a moderate stress in 2006. Photosynthetic rate decreased slightly during the summer with a slight recovery at the beginning of September, and did not differ across the seasons among cultivars. Stomatal conductance followed the same pattern. However, in both 2004 and 2005, stomatal conductance dropped sharply late in the season because of frequently occurring high temperatures that were greater than 32 °C. Maximum morning values of Fv/Fm were within the optimal range. The study suggests the presence of marginal photoinhibition during mid-summer in Concord cultivars, because no full recovery of photochemical efficiency early in the evening was observed. The European cultivar (Pinot Noir) and the American-European hybrid (Traminette) are more adapted to field conditions in Kansas than Concord cultivars. However, high cold-mortality of Pinot Noir due to high sensitivity to cold winter temperature makes the hybrid cultivars the most suitable cultivar for Midwest regions with relatively cold winters.     

Copolymerization of benzyl methacrylate and a methacrylate bearing benzophenoxy and hydroxyl side groups: Monomer reactivity ratios,thermal studies and dielectric measurements

Statistical copolymers of 2-hydroxy-3-benzophenoxy propyl methacrylate (HBPPMA) and benzyl methacrylate (BzMA) in different feed ratios were synthesized by free radical copolymerization method at 60 °C in presence of AIBN initiator. The compositions of copolymer were estimated from ¹H-NMR technique. The monomer reactivity ratios of HBPPMA and BzMA were calculated as r₁ (r_HBPPMA)=0.51±0.076 and r₂ (r_BzMA)=1.07±0.140 for Kelen-Tüdos method, and was estimated as r₁=0.37±0.0006 and r₂=0.64±0.0485 according to Fineman Ross equation. The average values estimated from the two methods showed that monomer reactivity ratio of benzyl methacrylate was a slightly high in comparison to HBPPMA. The copolymer system showed an azeotropic point, which is equal to M _BzMA =m _BzMA =0.43. DSC measurements showed that the T_g’s of poly(HBPPMA) and poly(BzMA) were 84 °C and 73 °C, respectively. The T_g in the copolymer system decreased with increase in benzyl methacrylate content. The decomposition temperature of poly(BzMA) and poly(HBPPMA) occurs in a single stage at about 207 °C and 260 °C, respectively. Those of HBPPMA-BzMA copolymer systems are between decomposition temperatures of two homopolymers. The dielectric constant, dielectric loss factor and electrical conductivity were investigated depend on the frequency of the copolymers. The highest dielectric constants depending on all the studied frequencies were recorded for the poly(HBPPMA) and the copolymer containing the highest HBPPMA unit. The dielectric constant for P(HBPPMA) and P(BzMA) at 1 kHz are 6.56 and 3.22, respectively. Also, those of copolymer systems were estimated between these two values. Similarly, poly(HBPPMA) and copolymers, which are prepared under the same conditions show the dissipation factor and conductivity as well.     

不同土壤条件下灰枣叶片与果实营养品质的相关性

【目的】研究不同土壤条件(沙土、沙壤土和粘土)下,成龄灰枣树果实膨大期叶片营养成分与果实成熟期果实营养成分和品质之间相关性,为不同土壤类型下有效提升灰枣果品提供理论依据。【方法】以盛果期灰枣树作为试材,测定其在果实膨大期叶片和成熟期果实中的P、K、Ca、Mg含量,以及果实VC、可滴定酸、可溶性糖、糖酸比和可溶性固形物含量等品质指标。【结果】三种土壤相比,沙土的叶片Ca含量和果实糖酸比均最高,分别为(24.381±1.830) g/kg、725.167±95.195,叶片K和Mg含量,果实P和K含量,果实可溶性糖和可溶性固形物含量均中等,其余测定指标均较低;沙壤土的叶片K含量、果实Ca和可滴定酸含量均最高,分别为(37.385±2.478) g/kg、(0.654±0.043) g/kg、(0.107±0.006)%,叶片P和Ca含量,果实Mg含量和果实VC含量均中等,其余测定指标均较低;粘土的叶片P和Mg含量,果实P、K和Mg含量,果实VC、可溶性糖和可溶性固形物含量均最高,分别为(2.622±0.134) g/kg、(7.125±0.484) g/kg、(1.168±0.061) g/kg、(11.327±0.528) g/kg、(0.422±0.015) g/kg、(15.182±2.763) mg/100 g、(70.875±3.230)%和(71.179±3.233)%,果实Ca含量、可滴定酸含量和糖酸比均中等,其余测定指标均较低。3种土壤类型条件下灰枣果实中P、K、Ca、Mg、VC、可滴定酸、可溶性糖、可溶性固形物含量上均存在一定的差异,但在果实营养品质指标与叶片营养元素含量间的相关性基本相似,其中沙土、沙壤土和粘土灰枣叶片中P含量与果实VC含量间均有显著正相关性,相关性系数依次为0.798、0.928和0.869。【结论】灰枣叶片中的营养元素含量与果实营养品质指标间呈现一定相关性,在土壤不同类型条件下的施肥管理中,应根据土壤肥力情况制定科学合理的施肥方案,才能达到增产优质目的。     

Current status and prospects of farming the giant river prawn Macrobrachium rosenbergii (De Man) in Bangladesh

Giant river prawn (Macrobrachium rosenbergii) farming plays an important role in the economy of Bangladesh. Presently, it is cultured in around 50 000 ha area with total annual production of 23 240 t. Traditional extensive prawn farming has been expanding over the last three decades through the introduction and adoption of improved culture systems, such as culture of prawn‐carps, prawn‐shrimp‐fish and prawn‐fish‐rice as concurrent and rotational systems. Efforts for the development of improved techniques on broodstock management, seed production and rearing and grow‐out of prawn have been made over the last decade. The outcomes are low‐cost feed for broodstock, production of post‐larvae in net cages (hapa), all‐male prawn culture, periphyton based prawn‐tilapia culture, C/N based prawn culture, organic prawn farming, prawn‐mola culture and prawn‐carp‐mola polyculture. Despite the development of culture technologies, a number of challenges for sustainable development of prawn farming need to be overcome to realize the potentials of this promising sector. Good aquaculture practises at all levels and application of measures for quality control and food safety would ensure sustainable development of prawn farming in Bangladesh.     

Toxicity and electrophysiological effects of Spilanthes amella Murr. extracts on Periplaneta americana L.

The potential insecticidal activity of Spilanthes acmella Murr. (Compositae) extracts was assessed in this study. The extracts were shown to be toxic against adults of American cockroach, Periplaneta americana L. The active component in S. acmella extract was isolated and identified as N-isobutyl-2,6,8-decatrienamide (spilanthol). The results from topical application of spilanthol show that it has a high acute toxicity and spilanthol was the most potent compound when compared to three conventional insecticides. The potency was found to be 1.3, 2.6 and 3.8 times more toxic than carbaryl, bioresmethrin and lindane, respectively. Electrophysiological studies indicated immediate hyperexcitation followed by complete inhibition of the cockroach cercal nerve activity.     

(Z)-12-Hydroxyoctadec-9-enoic acid in Sesbania aculeata seed oil

On the basis of various industrial importances of hydroxyl fatty acids we have investigated Sesbania aculeata seed oil. The most interesting finding is the presence of a hydroxyolefinic fatty acid (9.24%) along with other usual fatty acids such as lauric (2.51%), myristic (0.37%), palmitic (10.94%), palmitoleic (3.54%), stearic (4.02%), oleic (17.10%), linoleic (45.92%), linolenic (5.29%), arachidic (0.03%) and behenic (1.04%). The structure of this hydroxy fatty acid was established on the basis of spectral data (IR, ¹H NMR, ¹³C NMR, MS) and chemical (catalytic hydrogenation, oxidative degradation) methods as (Z)-12-hydroxyoctadec-9-enoic (ricinoleic) acid.