海豚组织中多氯联苯（PCBs）气相色谱测定的改良方法研究

研究和建立了一种测定海豚体内不同组织中多氯联苯(PCBs)前处理的改良方法,即将海豚组织分为低脂样品和高脂样品,分别经萃取、净化、浓缩等处理后,用Agilent6890N型气相色谱仪、63Ni放射源ECD检测器测定,采用保留时间定性和峰面积外标法定量。结果显示,加标回收率为75.8%~119.2%,精密度为5.6%~11.2%,方法检出限为0.126~0.642ng.g-1,说明该方法的准确性、可重复性符合海洋生物体痕量有机污染物分析要求。海豚组织样品的实际测定结果表明,该方法适合海豚体内PCBs含量的分析测定。     

渔业环境三氯杀螨醇的污染与危害

中国是世界上最大的水产品生产国和重要的输出国,国家政策的支持以及生产技术的提高有力拓展了水产行业的发展前景。然而,随着对外贸易的扩展和人们对食品安全的重视,许多国家对水产品中药物残留规定了严格的限量,同时也更加关注渔业环境质量的改善和提高。对于相关的基础研究,几十年来一直是国内外研究的热点。作为滴滴涕替代产品的三氯杀螨醇,自问世以来就受到了许多学者极大的关注。三氯杀螨醇对啮齿动物的毒性较低,杀螨效果好,促进了农作物的丰收。然而,其对水生生物的毒性很强,环境残留和多种危害日渐显现。文章评述了三氯杀螨醇的水环境行为、生物效应及其对水产品安全的影响,并指出今后应加强研究的方向和重点。     

Flavonoid distribution during the development of leaves, flowers, stems, and roots of Rosmarinus officinalis. postulation of a biosynthetic pathway

The distribution of seven flavonoids, eriocitrin, luteolin 3'-O-beta-d-glucuronide, hesperidin, diosmin, isoscutellarein 7-O-glucoside, hispidulin 7-O-glucoside, and genkwanin, has been studied in Rosmarinus officinalis leaves, flowers, stems, and roots during plant growth. The maximum level reached by luteolin 3'-O-beta-d-glucuronide in leaves during June-August suggests the existence of a delay between the activation of the enzymes involved in the flavanone and flavone biosynthesis. The presence of hesperidin and diosmin in the vascular system is significant, and hesperidin shows even higher levels than the phenolic diterpenes and rosmarinic acid. The distribution of flavonoids observed in R. officinalis suggests a functional and structural relationship between phytoregulators and flavonoids, where flavonoids would be "protectors" of the activity of phytoregulators. A hypothesis for the general pathway of biosynthesis of these compounds in plants of the family Labiatae is proposed.     

Experimental test of the impacts of feral hogs on forest dynamics and processes in the southeastern US

The foraging activities of nonindigenous feral hogs (Sus scrofa) create widespread, conspicuous soil disturbances. Hogs may impact forest regeneration dynamics through both direct effects, such as consumption of seeds, or indirectly via changes in disturbance frequency or intensity. Because they incorporate litter and live plant material into the soil, hogs may also influence ground cover and soil nutrient concentrations. We investigated the impacts of exotic feral hogs in a mixed pine-hardwood forest in the Big Thicket National Preserve (Texas, USA) where they are abundant. We established sixteen 10 m × 10 m plots and fenced eight of them to exclude feral hogs for 7 years. Excluding hogs increased the diversity of woody plants in the understory. Large seeded (>250 mg) species known to be preferred forage of feral hogs all responded positively to hog exclusion, thus consumption of Carya (hickory nuts), Quercus (acorns), and Nyssa seeds (tupelo) by hogs may be causing this pattern. The only exotic woody species, Sapium sebiferum (Chinese tallow tree), was more than twice as abundant with hogs present, perhaps as a response to increased disturbance. Hogs increased the amount of bare soil by decreasing the amounts of plant cover and surface litter. Plots with hogs present had lower soil C:N, possibly due to accelerated rates of nitrogen mineralization. These results demonstrate that hogs may influence future overstory composition and reduce tree diversity in this forest. Management of hogs may be desirable in this and other forests where large-seeded species are an important component of the ecosystem. Further, by accelerating litter breakdown and elevating nitrogen in the soil, hogs have the potential to impact local vegetation composition via nitrogen inputs as well.     

Fire severity as a key factor in post-fire regeneration of Pinus pinaster (Ait.) in Central Portugal

Context

Mediterranean pine woodlands are strongly affected by wildfires; however, there are knowledge gaps in the role of fire severity on Pinus pinaster Ait. regeneration.

Objectives

The principal questions were: (a) does post-fire regeneration of Maritime Pine differ where canopies were consumed to a low vs. high degree and (b) which factors, besides fire severity, could explain these differences.

Methods

Pine recruitment was monitored from 2 to 36?months after a summer wildfire in 18 25?m² plots, equally divided over two fire severity classes based on crown consumption. Besides the degree of crown consumption, three quantitative fire severity indices as well as post-fire site conditions, seed input and understory vegetation recovery were measured.

Results

Pine seedling densities were consistently higher in the plots with low than high crown consumption but due to marked spatial variability, they were only significantly different at two out of the eight sampling occasions. This variability could be explained by a quantitative index based on the diameter of twigs, as well as by seed input and post-fire site conditions (ash and litter cover).

Conclusion

Fire severity was found to strongly affect the pine recruitment following wildfire, using both a qualitative visual severity index and a quantitative, more labour-intensive one.     

Quantification of phenolic compounds in olive oil mill wastewater by artificial neural network/laccase biosensor

In this paper is considered a new computerized approach to the determination of concentrations of phenolic compounds (caffeic acid and catechol). An integrated artificial neural network (ANN)/laccase biosensor is designed. The data collected (current signals) from amperometric detection of the laccase biosensor were transferred into an ANN trained computer for modeling and prediction of output. Such an integrated ANN/laccase biosensor system is capable of the prediction of caffeic acid and catechol concentrations of olive oil mill wastewater, based on the created models and patterns, without any previous knowledge of this phenomenon. The predicted results using the ANN were compared with the amperometric detection of phenolic compounds obtained at a laccase biosensor in olive oil wastewater of the 2004-2005 harvest season. The difference between the real and the predicted values was <0.5%. biosensor; olive oil mill wastewater; chemical analysis; phenolic compounds.     

Treatment of metastatic melanoma B16F10 by the flavonoids tangeretin, rutin, and diosmin

Melanoma is one of the most frequently metastasizing malignant neoplasias. This study examines an experimental model of pulmonary metastasis and the B16F10 cell subline, highly metastatic in the lung. Antimetastatic effects of the flavonoids tangeretin, rutin, and diosmin were analyzed, and at the same time an analysis of the metastatic activity of ethanol was performed, considered to be necessary because it is used as a vehicle for administering the flavonoids. Lentini's model, which complements the macroscopic evaluation of nodule numbers by using a stereoscopic microscope and image analysis at the microscopic level, was used. The greatest reduction in the number of metastatic nodules (52%) was obtained with diosmin; similarly, the percentages of implantation, growth index, and invasion index (79.40, 67.44, and 45.23%, respectively), were all compared with those of the ethanol group, considered to be an effective control group. Rutin- and tangeretin-treated groups also showed reductions of the same index compared with the ethanol group. It would seem that structural factors would better explain these results and the antimetastatic activity of each flavonoid and the respective metabolites.     

Flavanol content and antioxidant activity in winery byproducts

Proanthocyanidins, particularly those coming from wine and grape products, have became of interest to nutritionists. Particular attention is currently being paid to the exploitation of this kind of grape byproducts for obtaining bio-active phenolic compounds with potential application as food antioxidants and preventive agents against cancer and other diseases. In this work, the flavanol composition of various winery byproducts submitted to different degrees of industrial exploitation has been studied and their antioxidant activity determined using two different methods (TBARS and TEAC) to evaluate their interest as suitable sources for the preparation of flavanol-rich antioxidant extracts. All the byproducts studied were still good flavanol sources no matter their exploitation degree. An important conclusion was that dried grape seeds, obtained as an end byproduct after the color extraction and alcohol distillation of the wine pomace, still kept important flavanol concentrations and significant antioxidant activity, even if they were submitted to high temperatures. These byproducts can be considered a cheap source for the extraction of antioxidant flavanols, which can be used as dietary supplements or in the production of phytochemicals.     

云南省马铃薯引种史、传播路线及其影响

马铃薯是外来作物,其引入和传播在解决云南明清时期以来的社会、经济、文化和宗教问题上具有重要作用.通过考据发现,马铃薯传入中国和云南省的时间及主要路线,以及传入后在云南的传播路线.传入和传播路线主要为;(1)1615年后由印度经印—缅—滇通道传入滇西,并广泛种植于迪庆、丽江、大理和怒江州,此细胞质类型为W/α型;(2)1...     

Estimating the sustainable harvesting and the stable diameter distribution of European beech with projection matrix models

We present a projection matrix model to estimate the sustainable harvest rates and the stable diameter distributions of three qualities of European beech in the Spanish province of Navarre. Considering a period of 10 years and the diameter growth, trees were grouped into five classes: (0,10), (10,20), (20,30), (30,40) and over 40 cm. The transition probabilities were calculated assuming an approximation by splines to the diameter growth curves and uniform distributions for the diameters in each class. A condition for sustainable harvesting, leading to reach in each harvest the stable diameter distribution, was introduced. The results obtained suggest that, for each projection and depending on the quality, harvest rates in the range 18.8–37.5% for recruitments in the range 200–840 stems/ha, may be sustained without risk of a population reduction. Finally, the stable diameter distributions in relation to the recruitment were also obtained for each quality.