Anti-necrosis potential of polyphenols against snake venoms

Polyphenols from the extracts of Areca catechu L. and Quercus infectoria Oliv. inhibited phospholipase A₂, proteases, hyaluronidase and L-amino acid oxidase of Naja naja kaouthia Lesson (NK) and Calloselasma rhodostoma Kuhl (CR) venoms by in vitro tests. Both extracts inhibited the hemorrhagic activity of CR venom and the dermonecrotic activity of NK venom by in vivo tests. The inhibitory activity of plant polyphenols against local tissue necrosis induced by snake venoms may be caused by inhibition of inflammatory reactions, hemorrhage, and necrosis. The result implies the therapeutic potential of plant polyphenols against necrosis in snakebite victims.     

Predicting species’ range limits from functional traits for the tree flora of North America

Using functional traits to explain species’ range limits is a promising approach in functional biogeography. It replaces the idiosyncrasy of species-specific climate ranges with a generic trait-based predictive framework. In addition, it has the potential to shed light on specific filter mechanisms creating large-scale vegetation patterns. However, its application to a continental flora, spanning large climate gradients, has been hampered by a lack of trait data. Here, we explore whether five key plant functional traits (seed mass, wood density, specific leaf area (SLA), maximum height, and longevity of a tree)—indicative of life history, mechanical, and physiological adaptations—explain the climate ranges of 250 North American tree species distributed from the boreal to the subtropics. Although the relationship between traits and the median climate across a species range is weak, quantile regressions revealed strong effects on range limits. Wood density and seed mass were strongly related to the lower but not upper temperature range limits of species. Maximum height affects the species range limits in both dry and humid climates, whereas SLA and longevity do not show clear relationships. These results allow the definition and delineation of climatic “no-go areas” for North American tree species based on key traits. As some of these key traits serve as important parameters in recent vegetation models, the implementation of trait-based climatic constraints has the potential to predict both range shifts and ecosystem consequences on a more functional basis. Moreover, for future trait-based vegetation models our results provide a benchmark for model evaluation.In 1895 the Danish plant ecologist Eugen Warming defined for the first time the objectives of a functional plant biogeography, when he expressed the need “to investigate the problems concerning the economy of plants, the demands that they make on their environment, and the means that they use to use the surrounding conditions….” He already envisioned how to tackle this: “This subject leads us into deep morphological, anatomical, and physiological investigations; […] it is very difficult, yet very alluring; but only in few cases can its problems be satisfactorily solved at the present time” (1).Since Warming’s days plant science has progressed beyond the study of just a “few cases.” For more than a century now, botanists and plant ecologists have collected data on morphological, anatomical, and physiological traits (2, 3), and have mapped the distributions of tens of thousands of plant species (e.g., Global Biodiversity Information Facility, www.gbif.org). In addition, climatologists and soil scientists have provided us with high-resolution global maps of the plant’s surrounding condition. With this it has now become feasible to analyze the functional underpinnings of plant distributions for entire regional floras across large-scale environmental gradients (4). It is well established that on regional and global scales, climate determines the distribution not only of plant species but also of form and function (5, 6) because it constitutes the overall physical constraint under which plants must establish and reproduce, before biotic interactions may modulate plant fitness. Plants have evolved a multitude of adaptations to climatic constraints, which are expressed in the diversity of their functional traits. These allow them to tolerate climate extremes such as summer drought or low winter temperatures. In other words, the climate range occupied by plants should be predictable from their functional traits.Current species distribution models (SDMs) (7) use correlations between current climate and species distributions, so-called climate envelopes. Even modern dynamic global vegetation models (DGVMs) (8) capable of representing carbon acquisition, water balance, and competitive interactions of plant functional types (PFTs) in great mechanistic detail, still incorporate empirical climate envelopes to constrain PFT distributions. This obvious lack of mechanism is an important limitation when such models are used to predict vegetation shifts under future climate scenarios, especially under novel combinations of climate variables (8). Here, we introduce a unique approach—the “double quantile” approach (Fig. 1 and see Linking Traits to Climate Ranges)—that allows us to predict species distribution limits from functional plant traits. Although still empirical at heart, this approach has distinct advantages: (i) The very nature of the traits emerging as suitable predictors of species distribution limits sheds light on the biological mechanisms. Accordingly, below we are able to put forward concrete hypotheses of the biological underpinnings of trait–climate limit relationships. (ii) Functional traits serve as a common currency across species and thus provide the basis for assimilating the behavior of many species into a single generic predictive framework. (iii) Because this approach replaces idiosyncrasy by generality, the handshake with process-oriented models is greatly facilitated as will be discussed below.Open in a separate windowFig. 1.(A) Species are distributed along climatic gradients and occupy species-specific climate ranges, which can be characterized by three measures: the upper limit (red squares), the lower limit (blue squares), and the median (black squares) for which the highest species’ occurrence probability is suggested. (B) To explore the response of the climate range measures to traits, we related them separately against the traits using linear quantile regression analysis. We estimated the upper quantiles for the upper limits, the lower quantiles for the lower limits, and the median quantile for the median; a solid line indicates a slope significantly different from zero (increasing or decreasing) and a dotted line represents a nonsignificant slope. The area between the outermost regression lines represents the possible climate range species can occupy across their trait values whereas areas outside these lines describe no-go areas. (C) We distinguish three types of response patterns: (i) one-sided constraint, i.e., significant slope at only one limit (the upper or the lower one); (ii) two-sided constraint with reverse slopes at both limits; and (iii) constant shift with aligned slopes at both limits.Here, we explore the potential of five functional traits—specific leaf area (SLA), wood density, maximum height, seed mass, and tree longevity—to explain the climate range limits and mean climate preferences of 250 North American tree species covering a temperature gradient from the boreal to the subtropics and a gradient from 65 to 3,000 mm of annual precipitation. Although there has been a first attempt to incorporate trait information in SDMs (9), we present here a unique study using plant functional traits to predict their limiting effect on species’ climate ranges at a taxonomic and climatic scale relevant for DGVMs. We chose to present the relationship between traits and species climate range limits from a trait perspective to highlight their potential for predicting species’ climate niches as a holistic measure of plant performance in response to climate. Unlike previous studies, our double quantile approach places an emphasis on the responses of species-specific climate ranges at the potentially stressful ends of climate gradients, where strong effects of functional traits on range limits can be expected.

Functional Traits: Selection and Relevance.

The five traits represent key functions defining plant strategy axes related to the fundamental tradeoffs of resource acquisition and reproduction (10, 11) and are thus indicative of life history, mechanical, and physiological mechanisms. Furthermore, some of these traits are frequently used as parameters in DGVMs (2). Because these traits vary across climatic gradients (12, 13), they are ideally suited to gain insight into processes shaping tree distributions at continental scales and at the same time to improve predictions on ecosystem functions under climate change. SLA is a key trait of the leaf economic spectrum (14) and defines a species’ resource use strategy from acquisitive to conservative. It is related to growth rate under different climatic conditions (15) and reflects tradeoffs in species’ shade and drought tolerances (16). Wood density is related to the efficiency and safety of water transport (17) and represents a tradeoff between mechanical strength and vertical growth. It is strongly correlated with growth and mortality rates (12). Maximum height describes the maximum recorded height of a species and quantifies species’ carbon gain strategy via light capture (18); it is related to successional status, shade tolerance and responds to gradients in precipitation on a global scale (19). Seed mass correlates positively with seedling survival rates under hazardous conditions during seedling establishment (11) and negatively with dispersal distance and the number of seeds produced per unit energy invested (20). Maximum tree longevity determines species responses to disturbance (21), compensates for reduced fecundity or juvenile survival (22), and relates to defensive investment (23).

Linking Traits to Climate Ranges.

We derive a tree species’ climate range from its natural geographic distribution (24). We use a set of eight bioclimatic variables (Methods) which represent dominant climatic gradients over North America and are widely used in climatic niche modeling (7, 25). To define a species’ climate range (Fig. 1A) we estimate for each bioclimatic variable the lower (5th quantile) and upper limits (95th quantile) and the median (50th quantile) across a species’ distribution range. Using linear quantile regression analysis (26), we regress across all species the three species-specific range measures against each of the five traits separately estimating the lower (10th, 5th), the upper (90th, 95th) and median (50th) regression quantiles, respectively (Fig. 1B). Thus, the 50th quantile regression lines fit to the medians (black line and squares in Fig. 1B) and describe how the mean realized climate niche depends on the trait values. The lower and upper quantile regression lines fit to the lower and upper limits (blue line and squares and red line and squares, respectively). In this double quantile approach, the outer regression lines enclose an area corresponding to the climate range the pool of 250 North American tree species can occupy across the range of their trait values (Fig. 1B). At the same time it identifies “no-go areas” which cannot be occupied by trees with a given trait value. The delineated areas can attain three possible shapes: (i) the area is wedge-shaped when there is a one-sided constraint, i.e., only one outer quantile represents a climatic extreme requiring a trait adaptation. (ii) The area has the form of an acute-angled triangle, when there is a two-sided constraint leading to reverse responses of the outer quantiles. Both triangular shapes, i and ii, imply that the possible climate range of the species pool changes with a given trait value (see Fig. 1C for examples). (iii) The area can have a rhomboid shape when the two-sided constraints are aligned. This implies a shift in the mean climate preference, but no change in the potential climate range per trait value.     

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.     

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.     

Human-modified temperatures induce species changes: Joint attribution

Average global surface-air temperature is increasing. Contention exists over relative contributions by natural and anthropogenic forcings. Ecological studies attribute plant and animal changes to observed warming. Until now, temperature-species connections have not been statistically attributed directly to anthropogenic climatic change. Using modeled climatic variables and observed species data, which are independent of thermometer records and paleoclimatic proxies, we demonstrate statistically significant "joint attribution," a two-step linkage: human activities contribute significantly to temperature changes and human-changed temperatures are associated with discernible changes in plant and animal traits. Additionally, our analyses provide independent testing of grid-box-scale temperature projections from a general circulation model (HadCM3).     

Leucoxenols A and B,two new phenolics from Bornean medicinal plant Syzygium leucoxylon

The medicinal plant, Syzygium leucoxylon or commonly known as Obah found in North Borneo was considered as traditional medicine by local committee. Two new phenolics, leucoxenols A (1) and B (2) were isolated and identified as major secondary metabolites from the leaves of S. leucoxylon. Their chemical structures were elucidated based on spectroscopic data such as NMR and HRESIMS. Furthermore, these compounds were active against selected strains of fungi.     

Modulatory effects of Saussurea lappa root aqueous extract against ethephon‐induced kidney toxicity in male rats

Ethephon (2‐chloroethyl phosphonic acid) is a plant growth promoter used to control the plant growth process by liberating ethylene and stimulating the production of endogenous ethylene. Medicinal plants are sources of novel drug discovery targets. Costus (Saussurea lappa) has been used as traditional Chinese medicine. The current study was conducted to examine the possible modifying effects of costus (S. lappa) root aqueous extract against kidney toxicity induced by ethephon in male rats. A total of 50 adult male rats were divided into five groups (first, control; second, costus; third, ethephon; fourth, posttreated ethephon with costus; fifth, ethephon self‐healing). There is a significant increase in the serum levels of urea, creatinine, potassium ions, chloride ions, kidney injury, DNA damage, and proliferating cell nuclear antigen expressions in treated rats with ethephon when compared to the control group. In contrast, the treated rats with ethephon revealed a significant decrease in the levels of sodium ions and an insignificant decrease in the calcium ions. Saussurea lappa extract modified these alterations when compared to the control group. As a result, costus root extract significantly reduced rat kidney toxicity after ethephon administration. We recommend costus to be included in diet for its valuable effects, and also producers and consumers should become more aware about the toxic effects of ethephon.