植物竞争对3种移植树苗生长的影响

在植物幼苗生长过程中,总是受到包括地下根竞争在内的各种竞争影响。植物间的竞争主要同有效光辐射、水分和各种营养相关。当外来植物侵入森林群落时,可能受到群落中其它植物竞争的影响。该文通过移植尾叶桉(Eucalyptus urophylla)、大叶相思(Acacia auriculaeformis)两种外来种和本地种荷木(Schima superba)幼苗,挖沟排除根竞争和砍树创造林窗来排除地上竞争的野外实验,研究植物竞争对幼苗生长的影响。有根竞争时,荷木、尾叶桉和大叶相思幼苗的生物量和净初级生产力均小于没有根竞争时,可见地下根竞争对3种幼苗生长有抑制性影响。尾叶桉、大叶相思和荷木3种幼苗受到的总竞争强度分别是0.357 9、0.338 3和0.198 9,受到的地下根竞争强度则分别是0.104 3、0.053 04和0.118 8,受到的地上竞争强度则分别是0.285 1、0.277 0和0.090 85。尾叶桉和大叶相思两种幼苗受到的总竞争强度间的差异不显著,但都显著大于荷木;3种幼苗受到的地上竞争强度间的差异同总竞争强度情况相似;尾叶桉和荷木两种幼苗受到的地下根竞争强度间的差异不显著,但都显著大于大叶相思。地上竞争对阳性树种尾叶桉和大叶相思两种幼苗的生长影响大,而地下根竞争则对耐阴性强的荷木幼苗影响大。尾叶桉和大叶相思两种外来种幼苗受到的总竞争强度均大于本地种荷木幼苗,这反映了这两种外来树种侵入次生林这样的群落受到竞争影响大。     

医学实验中常见设计类型的辨析及统计方法的合理选用

目的帮助医学研究工作者提高对常见统计应用识别能力,提高对统计学的正确利用率。方法：明确阐述秒种常见医学实验设计类型的异同点和应用场合,揭示常见统计应用错误的实质和危害性。结果：给出不适合用ｔ检验取代方差分析的充足理由和正确运用统计学的基本要领。结论：要提高实际工作者的统计学应用水平。需要经常对其进行统计培养,积极引导与统计学工作者开展科研协作。     

MEDIUM OPTIMIZATION OF ANTIFUNGAL ACTIVITY PRODUCTION BY Bacillus amyloliquefaciens USING STATISTICAL EXPERIMENTAL DESIGN

In order to overproduce biofungicides agents by Bacillus amyloliquefaciens BLB371, a suitable culture medium was optimized using response surface methodology. Plackett–Burman design and central composite design were employed for experimental design and analysis of the results. Peptone, sucrose, and yeast extract were found to significantly influence antifungal activity production and their optimal concentrations were, respectively, 20 g/L, 25 g/L, and 4.5 g/L. The corresponding biofungicide production was 250 AU/mL, corresponding to 56% improvement in antifungal components production over a previously used medium (160 AU/mL). Moreover, our results indicated that a deficiency of the minerals CuSO₄, FeCl₃ · 6H₂O, Na₂MoO₄, KI, ZnSO₄ · 7H₂O, H₃BO₃, and C₆H₈O₇ in the optimized culture medium was not crucial for biofungicides production by Bacillus amyloliquefaciens BLB371, which is interesting from a practical point of view, particularly for low-cost production and use of the biofungicide for the control of agricultural fungal pests.     

COMPARISON OF INTRASPECIFIC COMPETITION BETWEEN ERUPTIVE AND LATENT AUCHENORRHYCHA (HOMOPTERA) SPECIES ON RICE: SOGATELLA FURCIFERA (DELPHACIDAE) VERSUS RECILIA DORSALIS (DELTOCEPHALIDAE)*

Abstract A comparison of the effects of intraspecific competition between the white‐backed planthopper (WBPH) Sogatella furcifera (Horvath) and the zigzag leaihopper (ZLH) Recilia dorsalis (Motschulsky), as representatives of eruptive and latent Auchenorrhycha (Homoptera) species on rice, was carried out in the laboratory. Crowding during the nymphal stage extended the duration of development of WBPH but not of ZLH. The nymphal survival rate of WBPH, sex ratio, preoviposition period and fecundity of both species were however not affected. The brachypterous percentage of WBPH and nymphal survival of ZLH were significantly reduced under high nymphal density. Crowding during the adult stage reduced fecundity and longevity significantly of both species. Fecundity and longevity were further reduced when combined with high densities during the nymphal stage. Age‐specific life table analysis showed that the integrated effect of crowding on ZLH is stronger than on WBPH. The mechanism of eruptive and latent species' response to crowding during nymph and adult stages is not clearly expressed as a significant difference in fecundity. It is better described as the variation in the intrinsic rate of increase (r_m). Therefore the construction of an age‐specific life table is helpful, and perhaps necessary, to understand these effects. The results showed that the main ecological characteristics of ZLH, as a latent species were its longer immature period, lower total fecundity and decreased and retailed rate of oviposition, hence the lower r_m, as compared with WBPH.     

常发性害虫白背飞虱与潜在性害虫电光叶蝉的种内竞争效应比较(英文)

实验室研究表明若虫期拥挤显著延长了白背飞虱Sogatellafurcifera的发育历期 ,但电光叶蝉Reciliadorsalis的历期受影响不显著 ;白背飞虱的若虫存活率、两种的性比、产卵前期和繁殖力不显著。若虫期高密度下的白背飞虱短翅率、电光叶蝉的若虫存活率显著降低。繁殖力和成虫寿命在成虫期也拥挤的条件下将进一步受到影响。特定年龄生命表分析表明拥挤对白背飞虱的综合影响程度比对电光叶蝉小。常发性、潜在性昆虫对若虫期、成虫期拥挤的反应并不总是如文献中所言表现为繁殖力的差异 ,本研究表明内禀增长力可较完整地描绘这种反应。白背飞虱作为一常发性昆虫与潜在性昆虫电光叶蝉的生态学特性的差异表现在 :未成熟期短、繁殖力和产出卵速率均高 ,因而内禀增长力也高。     

A Generalization of the GMANOVA-Model

It is shown that in some experimental designs the MANOVA- and the GMANOVA-model are too restrictive either to yield all hypothesis tests of interest or to reflect all known features of the design. An extension of these models is derived by relating the response vectors with the unknown model parameters by linear equations which may be completely different for each of the p components of the response vector and for each of the n independent vectors. For situations, in which a Wishart-distributed estimator for the underlying common covariance matrix is attainable, a test for any s-dimensional linear hypothesis on the model parameters is derived.     

Marine reserves: size and age do matter

Marine reserves are widely used throughout the world to prevent overfishing and conserve biodiversity, but uncertainties remain about their optimal design. The effects of marine reserves are heterogeneous. Despite theoretical findings, empirical studies have previously found no effect of size on the effectiveness of marine reserves in protecting commercial fish stocks. Using 58 datasets from 19 European marine reserves, we show that reserve size and age do matter: Increasing the size of the no-take zone increases the density of commercial fishes within the reserve compared with outside; whereas the size of the buffer zone has the opposite effect. Moreover, positive effects of marine reserve on commercial fish species and species richness are linked to the time elapsed since the establishment of the protection scheme. The reserve size-dependency of the response to protection has strong implications for the spatial management of coastal areas because marine reserves are used for spatial zoning.     

Optimization of ultrasound-assisted aqueous two-phase system extraction of polyphenolic compounds from Aronia melanocarpa pomace by response surface methodology

Aronia melanocarpa berries are abundant in polyphenolic compounds. After juice production, the pomace of pressed berries still contains a substantial amount of polyphenolic compounds. For efficient utilization of A. melanocarpa berries and the enhancement of polyphenolic compound yields in Aronia melanocarpa pomace (AMP), total phenolics (TP) and total flavonoids (TF) from AMP were extracted, using ultrasound-assisted aqueous two-phase system (UAE-ATPS) extraction method. First, the influences of ammonium sulfate concentration, ethanol–water ratio, ultrasonic time, and ultrasonic power on TP and TF yields were investigated. On this basis, process variables such as ammonium sulfate concentration (0.30–0.35?g?mL^?1), ethanol–water ratio (0.6–0.8), ultrasonic time (40–60?min), and ultrasonic power (175–225?W) were further optimized by implementing Box–Benhnken design with response surface methodology. The experimental results showed that optimal extraction conditions of TP from AMP were as follows: ammonium sulfate concentration of 0.324?g?mL^?1, ethanol–water ratio of 0.69, ultrasonic time of 52?min, and ultrasonic power of 200?W. Meanwhile, ammonium sulfate concentration of 0.320?g?mL^?1, ethanol–water ratio of 0.71, ultrasonic time of 50?min, and ultrasonic power of 200?W were determined as optimum extraction conditions of TF in AMP. Experimental validation was performed, where TP and TF yields reached 68.15?±?1.04 and 11.67?±?0.63?mg?g^?1, respectively. Close agreement was found between experimental and predicted values. Overall, the present results demonstrated that ultrasound-assisted aqueous two-phase system extraction method was successfully used to extract total phenolics and flavonoids in A. melanocarpa pomace.     

Stigmatellin Y – An anti-biofilm compound from Bacillus subtilis BR4 possibly interferes in PQS–PqsR mediated quorum sensing system in Pseudomonas aeruginosa

Hitherto this is the first report pertaining to production of biofilm inhibitory compound(s) (BIC) from Bacillus subtilis BR4 against Pseudomonas aeruginosa (ATCC 27853) coupled with production optimization. In order to achieve this, combinations of media components were formulated by employing statistical tools such as Plackett–Burman analysis and central composite rotatable design (CCRD). It was evident that at 35 ml L^?1 glycerol and 3.8 g L^?1 casamino acid, anti-biofilm activity and production of extracellular protein significantly increased by 1.5-fold and 1.2-fold, respectively. These results corroborate that the combination of glycerol and casamino acid plays a key role in the production of BIC. Further, metabolic profiling of BIC was carried out using liquid chromatography/tandem mass spectrometry (LC–MS/MS) based on m/z value. The presence of Stigmatellin Y was predicted with monoisotopic neutral mass of 484.2825 Da. In support of optimization study, higher production of BIC was confirmed in the optimized-media-grown BR4 (OPT-BR4) than in the ideal-media-grown BR4 (ID-BR4) by LC–MS/MS analysis. PqsR in P. aeruginosa is a potential target for anti-virulent therapy. Molecular docking study has revealed that Stigmatellin Y interacts with PqsR in the similar orientation like a cognate signal (PQS) and synthetic inhibitor. In addition, Stigmatellin Y was found to exhibit interaction with four more amino acid residues of PqsR to establish strong affinity. Stigmatellin Y thus might play a role of competitor for PQS to distract PQS–PqsR mediated communication in P. aeruginosa. The present investigation thus paves new avenues to develop anti-Pseudomonas virulent therapy.     

Optimization of growing conditions for pigments production from microalga Navicula incerta using response surface methodology and its antioxidant capacity

Navicula incerta is a marine microalga distributed in Baja California, México, commonly used in aquaculture nutrition, and has been extended to human food, biomedical, and pharmaceutical industries due to its high biological activity. Therefore, the study aimed to optimize culture conditions to produce antioxidant pigments. A central composite experimental design and response surface methodology (RSM) was employed to analyze the best culture conditions. The medium (nitrogen-deficient concentrations), salinity (PSU = Practical Salinity Unity [g/kg]), age of culture (days), and solvent extraction (ethanol, methanol, and acetone) were the factors used for the experiment. Chlorophyll a (Chl a) and total carotenoids (T-Car), determined spectroscopically, were used as the response variables. The antioxidant capacity was evaluated by DPPH^? and ABTS^?+ radical inhibition, FRAP, and anti-hemolytic activity. According to the overlay plots, the optimum growth conditions for Chl a and T-Car production were the following conditions: medium = 0.44 mol·L^-1 of NaNO₃, salinity = 40 PSU, age of culture: 3.5 days, and solvent = methanol. The pigment extracts obtained in these optimized conditions had high antioxidant activity in ABTS^?+ (86.2–92.1% of inhibition) and anti-hemolytic activity (81.8–96.7% of hemolysis inhibition). Low inhibition (33–35%) was observed in DPPH^?. The highest value of FRAP (766.03 ± 16.62 μmol TE/g) was observed in the acetonic extract. The results demonstrated that RSM could obtain an extract with high antioxidant capacity with potential applications in the biomedical and pharmaceutical industry, which encourages the use of natural resources for chemoprevention of chronic-degenerative pathologies.