氮素水平对茶树新梢叶片代谢谱及其昼夜变化的影响

茶树叶片中含有丰富的代谢产物,氨基酸、茶多酚和咖啡碱是决定茶叶品质的重要成分。本文结合基于1H-核磁共振(1H-NMR)的代谢组学非靶标分析与通过高效液相色谱法进行的定量靶标分析两种方法,比较白天和夜晚所取不同施氮水平的茶树新梢第2叶的代谢产物差异,探讨了基于1H-NMR的代谢组学研究方法应用于茶叶品质成分形成机理研究的可行性。结果表明,白天和夜晚所取茶树新梢第2叶代谢组差异较大,可以显著分离,区分两个样本的主要组分为茶氨酸、葡萄糖和蔗糖,而不同施氮水平下茶树新梢第2叶代谢组没有显著差异。高效液相色谱定量分析的结果表明,施氮水平对主要游离氨基酸组分和儿茶素组分均有影响,且存在昼夜差别。     

Use of NMR spectroscopy to study transformations of nitrogenous substances during incubation of peat

Abstract. Samples of peat were incubated with ¹⁵N-labelled ammonium sulphate, urea, wheat straw and glycine and divided into six size fractions of solid components and a water-soluble fraction. The fractions were analysed by NMR spectroscopy to study the formation of humic substances and rind how fertilizer nitrogen is immobilized in peaty soils. After six months' incubation about half of the ammonium sulphate nitrogen was still present as ammonium in the soluble fraction, the urea had been entirely metabolized to ammonium and various organic compounds, about half the straw had been decomposed to ammonium and amino acid or peptide materials, and most of the glycine had been transformed to ammonium, amide and aliphatic amine.     

Reference points for predators will progress ecosystem‐based management of fisheries

Ecosystem‐based management of fisheries aims to allow sustainable use of fished stocks while keeping impacts upon ecosystems within safe ecological limits. Both the FAO Code of Conduct for Responsible Fisheries and the Aichi Biodiversity Targets promote these aims. We evaluate implementation of ecosystem‐based management in six case‐study fisheries in which potential indirect impacts upon bird or mammal predators of fished stocks are well publicized and well studied. In particular, we consider the components needed to enable management strategies to respond to information from predator monitoring. Although such information is available in all case‐studies, only one has a reference point defining safe ecological limits for predators and none has a method to adjust fishing activities in response to estimates of the state of the predator population. Reference points for predators have been developed outside the fisheries management context, but adoption by fisheries managers is hindered a lack of clarity about management objectives and uncertainty about how fishing affects predator dynamics. This also hinders the development of adjustment methods because these generally require information on the state of ecosystem variables relative to reference points. Nonetheless, most of the case‐studies include precautionary measures to limit impacts on predators. These measures are not used tactically and therefore risk excessive restrictions on sustainable use. Adoption of predator reference points to inform tactical adjustment of precautionary measures would be an appropriate next step towards ecosystem‐based management.     

Thoughts towards a philosophy of nature conservation

This essay examines some basic issues underlying the philosophy of nature conservation. It distinguishes between economic and cultural reasons for conserving wildlife and its habitat, and deals largely with the latter. Nature conservation reflects and supports a spectrum of public interest ranging from deep science to simple perception, and has a rightful place in education. It is seen as an activity conducive to civilised living, through its ability to give an abiding sense of purpose, and harmony of relationships, both with environment and other people. Concern for wildlife is consistent with concern over the world-wide ills of human society, for it can help to promote a way of life in which there is greater understanding and control over the irrational and animalistic aspects of our existence. For many people it gives the foundation for a much-needed ethic. The question of whether we conserve wildlife and habitat because of its right to existence poses one of the ultimate philosophical problems, and can only be answered in terms of a personal credo.