Spontaneous spatiotemporal waves of gene expression from biological clocks in the leaf

The circadian clocks that drive daily rhythms in animals are tightly coupled among the cells of some tissues. The coupling profoundly affects cellular rhythmicity and is central to contemporary understanding of circadian physiology and behavior. In contrast, studies of the clock in plant cells have largely ignored intercellular coupling, which is reported to be very weak or absent. We used luciferase reporter gene imaging to monitor circadian rhythms in leaves of Arabidopsis thaliana plants, achieving resolution close to the cellular level. Leaves grown without environmental cycles for up to 3 wk reproducibly showed spatiotemporal waves of gene expression consistent with intercellular coupling, using several reporter genes. Within individual leaves, different regions differed in phase by up to 17 h. A broad range of patterns was observed among leaves, rather than a common spatial distribution of circadian properties. Leaves exposed to light-dark cycles always had fully synchronized rhythms, which could desynchronize rapidly. After 4 d in constant light, some leaves were as desynchronized as leaves grown without any rhythmic input. Applying light-dark cycles to such a leaf resulted in full synchronization within 2-4 d. Thus, the rhythms of all cells were coupled to external light-dark cycles far more strongly than the cellular clocks were coupled to each other. Spontaneous desynchronization under constant conditions was limited, consistent with weak intercellular coupling among heterogeneous clocks. Both the weakness of coupling and the heterogeneity among cells are relevant to interpret molecular studies and to understand the physiological functions of the plant circadian clock.     

Community-wide convergent evolution in insect adaptation to toxic cardenolides by substitutions in the Na,K-ATPase

The extent of convergent molecular evolution is largely unknown, yet is critical to understanding the genetics of adaptation. Target site insensitivity to cardenolides is a prime candidate for studying molecular convergence because herbivores in six orders of insects have specialized on these plant poisons, which gain their toxicity by blocking an essential transmembrane carrier, the sodium pump (Na,K-ATPase). We investigated gene sequences of the Na,K-ATPase α-subunit in 18 insects feeding on cardenolide-containing plants (spanning 15 genera and four orders) to screen for amino acid substitutions that might lower sensitivity to cardenolides. The replacement N122H that was previously shown to confer resistance in the monarch butterfly (Danaus plexippus) and Chrysochus leaf beetles was found in four additional species, Oncopeltus fasciatus and Lygaeus kalmii (Heteroptera, Lygaeidae), Labidomera clivicollis (Coleoptera, Chrysomelidae), and Liriomyza asclepiadis (Diptera, Agromyzidae). Thus, across 300 Myr of insect divergence, specialization on cardenolide-containing plants resulted in molecular convergence for an adaptation likely involved in coevolution. Our screen revealed a number of other substitutions connected to cardenolide binding in mammals. We confirmed that some of the particular substitutions provide resistance to cardenolides by introducing five distinct constructs of the Drosophila melanogaster gene into susceptible eucaryotic cells under an ouabain selection regime. These functional assays demonstrate that combined substitutions of Q(111) and N(122) are synergistic, with greater than twofold higher resistance than either substitution alone and >12-fold resistance over the wild type. Thus, even across deep phylogenetic branches, evolutionary degrees of freedom seem to be limited by physiological constraints, such that the same molecular substitutions confer adaptation.     

Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia

Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m(2) of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites, a coniferophyte, or Sigillaria, a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.     

共生真菌对植物抗旱性的影响及机制研究进展

共生真菌分布广泛,与植物形成共生体。研究表明,某些共生真菌可以增强植物对生物胁迫和非生物胁迫,包括干旱、高温、矿物质失调和高盐的耐受性,从而使被内生真菌感染的植株比未感染植株对有限的资源更具竞争力而且生长得更好。植物共生真菌可以通过多样化途径来增强植物体的抗性机能,其提高抗旱性的机制主要表现在营养物质的吸收、植物的保护系统、激素调节、水解酶、水分代谢、相关基因表达、植物防御信号途径等方面。总结共生真菌提高植物耐旱性的机制研究进展,以使读者能全面、及时地了解这一领域的研究动态。     

基于污水流行病学的广州和珠海4种心血管药物消费量的估算研究

目的了解广州和珠海城市污水处理厂进水中的4种心血管药物浓度,并对其消费量进行估算。方法分别于2017年5月9至22日(春季)和9月27日至10月12日(秋季)采集广州1座污水厂进水水样,2017年1月23日至2月5日(冬季)采集珠海1座污水厂进水水样,采用固相萃取-液相色谱-串联质谱法检测美托洛尔(MET)、阿替洛尔(ATE)、吉非罗齐(GFB)、苯扎贝特(BZB)的浓度,应用污水流行病学方法估算4种心血管药物在广州和珠海的消费量。结果 4种心血管药物均有检出,浓度范围在未检出~889.73 ng/L之间,检出率在14.29%~100%之间。在4种心血管药物中,以MET和BZB浓度较高,其最高浓度分别达733.71和889.73 ng/L。与珠海市比较,广州市污水厂进水中MET、BZB、GFB的浓度较高,差异均有统计学意义(P<0.01);而ATE的浓度无明显差异。不论在广州市还是珠海市,MET的消费量均远高于BZB、GFB、ATE,4种药物在两城市的消费模式均为MET>BZB>GFB>ATE。与珠海市比较,广州市MET、BZB、GFB消费量较高,差异均有统计学意义(P<0.01);而ATE的消费量无明显差异。不论是春季还是秋季,MET均为消费量最高的药物,ATE均为消费量最低的药物。与春季比较,秋季ATE的消费量较低,差异有统计学意义(P<0.01);而MET、BZB、GFB无明显改变。结论不同地区的心血管药物消费存在较大差异,广州市的MET、BZB、GFB、ATE消费量高于珠海。     

An in vitro study of the effect of some dietary components on calculus formation: regulation of calcium phosphate precipitation

OBJECTIVE: We studied the effects of food components on the in vitro formation of calcium phosphate precipitates. MATERIALS AND METHODS: The effects of food components, such as starch, soybean flour, fish meal, rapeseed oil, and coconut oil, on calcium phosphate precipitation were studied using a pH drop method. RESULTS: Although the addition of starch had no effect on the rate of precipitation of amorphous calcium phosphate (ACP), it increased both the rate of transformation of ACP to hydroxyapatite (HAP) and the induction time (i.e. time for the initiation of transformation of ACP to HAP to occur); this was irrespective of the heat treatment of the starch. Amylopectin (insoluble constituent of starch) was effective in increasing the rate of HAP transformation, but amylose (soluble constituent of starch) was not. Oil specimen obtained from rapeseed (400 microl ml(-1)) increased the entire reaction of calcium phosphate precipitation, but that from coconut did not. Protein food, such as soybean flour and fish meal, decreased the rate of transformation of ACP to HAP and increased the induction time, while they had no effect on the rate of ACP precipitation. CONCLUSION: These results suggest that carbohydrate and oil (both are staple diets for the humans) enhance oral calcification (dental calculus formation or re-mineralization of tooth enamel), while side dishes of protein food would decrease it.     

壮药红根草的基原调查和生药学研究

目的对壮药红根草进行了基原调查和生药学鉴定研究。方法查阅本草文献对红根草原植物记载及附图,野外调查红根草药材的原植物来源,通过产地药农收集红根草药材原植物标本,核对药材原植物标本,咨询分类专家,对红根草的原植物形态、药材性状、显微特征、薄层色谱等进行了研究。结果目前产地及市场红根草药材原植物来源是唇形科植物黄埔鼠尾草S. prionitis带根的全草,采用建立的方法能够有效鉴别红根草药材。结论为更好地制定红根草新的药材质量标准和药厂红根草药材收购提供依据。     

植物内源激素检测方法新进展

植物内源激素是植物体内产生的一类小分子化合物,在极低的浓度下就能发挥多种生理作用,调控植物生长发育的每一过程。植物内源激素在植物体内含量极低、性质不稳定,其定量检测一直是当前研究的热点和难点。随着分析技术的进步及新仪器的出现,植物内源激素的提取和纯化技术及检测方法也在不断更新。目前,有机溶剂提取、固相萃取柱纯化是常用的提取和纯化步骤,检测方法主要包括生物鉴定法、理化检测法和免疫检测法3大类,其中理化检测是最常用方法。本文对近几年植物内源激素提取、纯化和检测方法 3个方面的新进展进行综述,以期为植物内源激素的深入研究提供参考。     

Efficient protocol for rapid Aloe vera micropropagation

Context: Aloe vera Linn. (Liliaceae) is a medicinal plant and has a number of curative properties. Vegetative propagation has not enough potential for supplying market demand. However, via in vitro propagation makes possible the mass production of Aloe plants.

Objective: The current study was conducted to investigate growth regulators’ effects on proliferation of A. vera.

Materials and methods: In this study, for comparison of plant growth regulators’ effects on proliferation, the shoot tips and auxiliary buds of A. vera were cultured in the Murashige and Skoog (MS) medium. Rooted plantlets were transferred to garden soil, compost, and sand in the proportion of 1:1:1, respectively, after hardening.

Results: The maximum number of shoots was obtained on the medium supplemented with 1?mg/L IAA?+?4?mg/L BAP and 0.2?mg/L IAA?+?0.8?BAP mg/L. Rooting was also achieved in the same media composition proliferation of shoot. The acclimatized plants showed 100% of survival. The regenerated plants looked healthy, and they were morphologically similar to that of stock plants.

Conclusion: These results suggest that in vitro culture may be used as a technique for rapid propagation of A. vera.     

EPR Spectroscopy as a Tool to Characterize the Maturity Degree of Humic Acids

The major indicator of soil fertility and productivity are humic acids (HAs) arising from decomposition of organic matter. The structure and properties of HAs depend, among others climate factors, on soil and anthropogenic factors, i.e., methods of soil management. The purpose of the research undertaken in this paper is to study humic acids resulting from the decomposition of crop residues of wheat (Triticum aestivum L.) and plant material of thuja (Thuja plicata D.Don.ex. Lamb) using electron paramagnetic resonance (EPR) spectroscopy. In the present paper, we report EPR studies carried out on two types of HAs extracted from forest soil and incubated samples of plant material (mixture of wheat straw and roots), both without soil and mixed with soil. EPR signals obtained from these samples were subjected to numerical analysis, which showed that the EPR spectra of each sample could be deconvoluted into Lorentzian and Gaussian components. It can be shown that the origin of HAs has a significant impact on the parameters of their EPR spectra. The parameters of EPR spectra of humic acids depend strongly on their origin. The HA samples isolated from forest soils are characterized by higher spin concentration and lower peak-to-peak width of EPR spectra in comparison to those of HAs incubated from plant material.