Nelumbonaceae:Systematic position and species diversification revealed by the complete chloroplast genome

<正>Nelumbonaceae is a morphologically unique family of angiosperms and was traditionally placed in Nymphaeales;more recently,it was placed in Proteales based on molecular data,or in an order of its own,Nelumbonales. To determine the systematic position of the family and to date the divergence time of the family and the divergence time of its two intercontinentally disjunct species,we sequenced the entire chloroplast genome of Nelumbo lutea and most of the chloroplast genes of,N.nucifera.We carried out phylogenetic and molecular dating analyses of the two species and representatives of 47 other plant families,representing the major lineages of angiosperms, using 83 plastid genes.The N.lutea genome was 163 510 bp long,with a total of 130 coding genes and an overall GC content of 38%.No significant structural differences among the genomes of N.lutea,Nymphaea alba, and Platanus occidentalis were observed.The phylogenetic relationships based on the 83 plastid genes revealed a close relationship between Nelumbonaceae and Platanaceae.The divergence times were estimated to be 109 Ma between the two families and 1.5 Ma between the two Nelumbo species.The estimated time was only slightly longer than the age of known Nelumbo fossils,suggesting morphological stasis within Nelumbonaceae.We conclude that Nelumbonaceae holds a position in or close to Proteales.We further conclude that the two species of Nelumbo diverged recently from a common ancestor and do not represent ancient relicts on different continents.     

北京市天敌昆虫产业的发展现状与对策

环境、生态和食品安全问题使以释放天敌为主的生物防治措施在有害生物综合治理中的重要性日益提升,为天敌产品提供了重要市场机遇,天敌的产业化正成为使传统植物保护工作优化升级的新型产业。本文综述了北京市天敌昆虫产业化发展的现状,分析了天敌昆虫产业的发展优势及存在的问题,并提出了今后发展应采取的对策。     

Cloning and ontogenetic expression of the uncoupling protein 1 gene <Emphasis Type="Italic">UCP1</Emphasis> in sheep

The uncoupling protein 1 (UCP1) is an indicator of brown adipocytes and is involved in the control of body temperature and regulation of energy balance. It abundantly expresses in newborns and has important functions in adults. However, little information was known on UCP1 gene expression in young and adolescent sheep. In this study, we cloned and identified the full-length DNA and cDNA sequences of the ovine UCP1 gene, which were 6659 bp and 1621 bp, respectively, and predicted the location of the gene on chromosome 17. Forty-eight animals with an equal number of males and females each for both Guangling Large Tail sheep (GLT) and Small Tail sheep Han (STH) sheep were used to study the ontogenetic expression of UCP1 mRNA in eight adipose tissues by quantitative real-time polymerase chain reaction (PCR). The results showed that the mRNA was expressed in all tissues studied and at all stages from 2 to 12 months of age. Nevertheless, the mRNA in perirenal fat was expressed significantly higher than that in other tissues and lower in superficial fat than in deep deposits. The highest expression was observed in animals at 2 months of age and then decreased gradually with age. Global expression in GLT was significantly higher than that in STH. Interactions between tissue and breed and age also influenced the mRNA expression significantly. In addition, the mRNA expression was associated with the single nucleotide polymorphism (SNP) haplotypes detected in the cDNA of the gene.     

Regulation Mechanisms of Stomatal Oscillation

Stomata function as the gates between the plant and the atmospheric environment. Stomatal movement, including stomatal opening and closing, controls CO2 absorption as the raw material for photosynthesis and water loss through transpiration. How to reduce water loss and maintain enough CO2 absorption has been an interesting research topic for some time. Simple stomatal opening may elevate CO2 absorption, but, in the meantime, promote the water loss, whereas simple closing of stomatal pores may reduce both water loss and CO2 absorption, resulting in impairment of plant photosynthesis. Both processes are not economical to the plant. As a special rhythmic stomatal movement that usually occurs at smaller stomatal apertures, stomatal oscillation can keep CO2 absorption at a sufficient level and reduce water loss at the same time, suggesting a potential improvement in water use efficiency. Stomatal oscillation is usually found after a sudden change in one environmental factor in relatively constant environments. Many environmental stimuli can induce stomatal oscillation. It appears that, at the physiological level, feedback controls are involved in stomatal oscillation. At the cellular level, possibly two different patterns exist： （i） a quicker responsive pattern; and （ii） a slower response. Both involve water potential changes and water channel regulation, but the mechanisms of regulation of the two patterns are different. Some evidence suggests that the regulation of water channels may play a vital and primary role in stomatal oscillation. The present review summarizes studies on stomatal oscillation and concludes with some discussion regarding the mechanisms of regulation of stomatal oscillation.     

Lake Level Changes Recorded by Tree Rings of Lakeshore Shrubs： A Case Study at the Lake West-Juyan, Inner Mongolia, China

Variation in water resources is a main factor influencing ecohydrological processes and sustainable development in arid regions. Lake level changes are a useful indicator of the variability in water resources. However, observational records of changes in lake levels are usually too short to give an understanding of the long-term variability. In the present study, we investigated the tree rings of shrubs growing on the lakeshore of Lake West-Juyan, the terminus of the Heihe River in western China, and found that Lake West-Juyan had undergone degradation three times over the past 200 years. The lake level decreased from 904.3 to 896.8 m above sea level （a.s.1.） during the period 1800-1900, to 892.0 m a.s.1, from around 1900 to the late 1950s, and the lake dried out in 1963. The trend for changes in lake levels, which was represented by the composite chronology of three beach bars, showed that the phases of increasing lake levels over the past 150 years were during the periods 1852-1871, 1932-1952, 1973-1982, and 1995-1999. Comparison with the history of regional economic development showed that human activity has played an important role in regulating the water resources of the lower reaches of the Heihe watershed over the past 200 years.     

Hydrogen sulfide and rhizobia synergistically regulate nitrogen (N) assimilation and remobilization during N deficiency-induced senescence in soybean

Hydrogen sulfide (H₂S) is emerging as an important signalling molecule that regulates plant growth and abiotic stress responses. However, the roles of H₂S in symbiotic nitrogen (N) assimilation and remobilization have not been characterized. Therefore, we examined how H₂S influences the soybean (Glycine max)/rhizobia interaction in terms of symbiotic N fixation and mobilization during N deficiency-induced senescence. H₂S enhanced biomass accumulation and delayed leaf senescence through effects on nodule numbers, leaf chlorophyll contents, leaf N resorption efficiency, and the N contents in different tissues. Moreover, grain numbers and yield were regulated by H₂S and rhizobia, together with N accumulation in the organs, and N use efficiency. The synergistic effects of H₂S and rhizobia were also demonstrated by effects on the enzyme activities, protein abundances, and gene expressions associated with N metabolism, and senescence-associated genes (SAGs) expression in soybeans grown under conditions of N deficiency. Taken together, these results show that H₂S and rhizobia accelerate N assimilation and remobilization by regulation of the expression of SAGs during N deficiency-induced senescence. Thus, H₂S enhances the vegetative and reproductive growth of soybean, presumably through interactions with rhizobia under conditions of N deficiency.