Mutual influence of forests and pastures on the seedbanks in the Eastern Amazon

The objective of this study was to compare the floristic composition and species diversity existing in the seedbanks of forests and pastures. The seedbanks were sampled in three forest and three pastures areas in a community of smallholder farmers, in Pará state, Brazil. Seedling emergence in a glasshouse was used to quantify and identify the seeds. The total densities and diversity of the seedbanks were not significantly different among the pastures and forests, but the floristic composition was different. The herbaceous species predominated in both the pastures and the forests, but in the forest the abundance of shrub and tree was higher than herb. The seed density of several pioneer woody species was higher in the forests and the density of several herbaceous species was greater in the pastures. The influence of the forest species on the pastures and of the pastures species on the forests is a result of the initial process of human occupation and illustrates a dynamic that can lead to both the conservation of forest species and the spread of weed species. Actions should be carried out to avoid disturbance in the forests and improve biodiversity preservation in rural areas.     

草原保护和建设是内蒙古长期坚持的绿色工程

总结了内蒙古 2 0年来草原建设和保护的经验、技术 ,探讨了发展的条件和对策 ,为面向2 1世纪农业技术的发展提供了理论依据和参考     

Isolation and selection of suitable reference genes for real-time PCR analyses in the skeletal muscle of the fine flounder in response to nutritional status: assessment and normalization of gene expression of growth-related genes

In the present study, different reference genes were isolated, and their stability in the skeletal muscle of fine flounder subjected to different nutritional states was assessed using geNorm and NormFinder. The combinations between 18S and ActB; Fau and 18S; and Fau and Tubb were chosen as the most stable gene combinations in feeding, long-term fasting and refeeding, and short-term refeeding conditions, respectively. In all periods, ActB was identified as the single least stable gene. Subsequently, the expression of the myosin heavy chain (MYH) and the insulin-like growth factor-I receptor (IGF-IR) was assessed. A large variation in MYH and IGF-IR expression was found depending on the reference gene that was chosen for normalizing the expression of both genes. Using the most stable reference genes, mRNA levels of MYH decreased and IGF-IR increased during fasting, with both returning to basal levels during refeeding. However, the drop in mRNA levels for IGF-IR occurred during short-term refeeding, in contrast with the observed events in the expression of MYH, which occurred during long-term refeeding. The present study highlights the vast differences incurred when using unsuitable versus suitable reference genes for normalizing gene expression, pointing out that normalization without proper validation could result in a bias of gene expression.     

Structure elucidation and anticancer activity of 7-oxostaurosporine derivatives from the Brazilian endemic tunicate Eudistoma vannamei

The present study reports the identification of two new staurosporine derivatives, 2-hydroxy-7-oxostaurosporine (1) and 3-hydroxy-7-oxostaurosporine (2), obtained from mid-polar fractions of an aqueous methanol extract of the tunicate Eudistoma vannamei, endemic to the northeast coast of Brazil. The mixture of 1 and 2 displayed IC₅₀ values in the nM range and was up to 14 times more cytotoxic than staurosporine across a panel of tumor cell lines, as evaluated using the MTT assay.     

Palyosulfonoceramides A and B: Unique Sulfonylated Ceramides from the Brazilian Zoanthids Palythoa caribaeorum and Protopalyhtoa variabilis

The zoanthids Palythoa caribaeorum and Protopalythoa variabilis are among the most abundant marine species along the Brazilian coast. We now report the isolation and structure elucidation of two unprecedented sulfonylated ceramides, palyosulfonoceramide A (1) and palyosulfonoceramide B (2) from specimens collected off Brazil’s northeastern coast. The structures of 1 and 2 were established using a combination of NMR analyses, including: evaluation of ¹H, ¹³C, ¹H–¹H COSY, ¹H–¹³C HSQC, ¹H–¹³C HMBC, and ¹H–¹⁵N HMBC NMR spectra, high-resolution mass spectrometry and chemical degradation. In addition, we also isolated the corresponding known ceramides, N-((2S,3R,4E,8E)-1,3-dihydroxyoctadeca-4,8-dien-2-yl)-hexadecanamide (3) and N-((2S,3R,4E)-1,3-dihydroxyoctadeca-4-en-2-yl)-hexadecanamide (4), which provided further support for the assignments of 1 and 2.     

Differential response of pea (Pisum sativum) to Orobanche crenata, Orobanche foetida and Phelipanche aegyptiaca

Several broomrape species including Orobanche crenata, Orobanche foetida and Phelipanche aegyptiaca are reported to infect various grain and forage legumes in the Mediterranean and West Asia. Pea (Pisum sativum) is severely damaged by O. crenata, but there are no reports on O. foetida or P. aegyptiaca infection. We report here that pea can induce high germination of seeds of O. crenata, O. foetida and P. aegyptiaca but only O. crenata success infecting pea roots and developing further. Some differences in levels of infection by O. crenata were observed among pea accessions what can be exploited in pea resistance breeding programmes. On the contrary, all pea accessions studied were highly resistant to infection by both O. foetida and P. aegyptiaca, preventing any tubercle attachment and development. This makes pea a promising candidate as trap crop for O. foetida and P. aegyptiaca seed bank demise in infested soils.     

基于PSR模型的都市近郊乡村旅游社区参与模式研究——以重庆市璧山县为例

[目的]完善旅游社区参与模式研究,为相似区域乡村旅游社区参与模式的构建提供借鉴.[方法]以重庆市璧山县为研究对象,分析都市近郊乡村旅游社区参与的特点,并通过该类区域PSR模型的分析,探讨不同游憩带适宜的乡村旅游社区参与模式.[结果]通过充分考虑PSR模型下的区域特点,分别总结出城市游憩圈带、近程游憩带和远程游憩带的游憩地配置模式、社区参与模式及社区发展核心.[结论]乡村旅游社区开发模式的选择应当依托区域要素,构建合理发展机制,避免各种经济、文化冲突.     

Does the Use of Chitosan Contribute to Oxalate Kidney Stone Formation?

Chitosan is widely used in the biomedical field due its chemical and pharmacological properties. However, intake of chitosan results in renal tissue accumulation of chitosan and promotes an increase in calcium excretion. On the other hand, the effect of chitosan on the formation of calcium oxalate crystals (CaOx) has not been described. In this work, we evaluated the antioxidant capacity of chitosan and its interference in the formation of CaOx crystals in vitro. Here, the chitosan obtained commercially had its identity confirmed by nuclear magnetic resonance and infrared spectroscopy. In several tests, this chitosan showed low or no antioxidant activity. However, it also showed excellent copper-chelating activity. In vitro, chitosan acted as an inducer mainly of monohydrate CaOx crystal formation, which is more prevalent in patients with urolithiasis. We also observed that chitosan modifies the morphology and size of these crystals, as well as changes the surface charge of the crystals, making them even more positive, which can facilitate the interaction of these crystals with renal cells. Chitosan greatly influences the formation of crystals in vitro, and in vivo analyses should be conducted to assess the risk of using chitosan.     

A set of standard area diagrams to assess severity of frogeye leaf spot on soybean

European Journal of Plant Pathology - A set of standard area diagrams (SADs) was developed and validated to aid visual assessment of severity of frogeye leaf spot (FLS) caused by Cercospora sojina....     

Weed seed germination and the light environment: Implications for weed management

Light regulates dormancy termination and the subsequent germination in many weed species. Under field conditions, the light environment of the seeds, which is perceived mainly by photoreceptors of the phytochrome family, provides essential information for cueing germination in the proper environmental situation. The light environment's spectral composition and irradiance allow weed seeds to sense their position in the soil profile, the presence of a leaf canopy capturing light and other resources and the occurrence of soil cultivation. From an agronomical point of view, the control of germination by light represents a potentially useful step in the life cycle of weeds for developing effective control practices. The goal of this article is to place current knowledge regarding photoreceptors, physiological and molecular bases of seed responses to light and their ecological implications within the context of weed management in agricultural systems. With that final objective, the authors intend to show how a better understanding of the way in which the light environment regulates dormancy termination and the subsequent germination of weed seeds could be used to develop more accurate control practices and to improve weed management strategies.