Spectral absorption coefficient of phytoplankton and its relation to chlorophyll a and remote sensing reflectance in coastal waters of southern China

The spectral absorption coefficient of phytoplankton in coastal waters of southern China is investigated. Large variations in the absorption coefficient of phytoplankton are found. The absorption coefficient of phytoplankton at 443 nm ranged from 0. 006 m- 1 to 0. 484 m - 1, with an average value of 0. 067 m - 1. The chlorophyll-specific absorption coefficient of phytoplankton is also a bio-optical varito pigment composition of phytoplankton and package effect. The chlorophyll-specific absorption coefficient of phytoplankton decreases with the increasing of chlorophyll a concentration. This relationship can be described by a power law function, with the parameters and the coefficient of determination r2 as functions of wavelength, but the parameters describing the relationships in present study differed from that in Case 1 waters, thus the regional adjustment of model parameters was of particular significance for improving the accuracy of bio-optical algorithms for estimation of Chl-a concentration and primary production from remotely sensed data. Regression analysis of reflectance (R rs) ratio and absorption coefficient of phytoplankton (a ph) indicates a close correlation between them, which means that it is possible to retrieve absorption coefficient of phytoplankton using ocean color remote sensing data in optically complex coastal waters.     

Single-and multiple-scattering properties of ice crystals in 1.38 μm wavelength and its potential applications in satellite remote sensing

An improved ray-optics theory and Mie theory for single scattering and the adding-dou-bling method for multiple scattering are used to study the relationship between the radiation in the wavelengths of 1.38, 3.979, 6.5, and 11.03 μm and the microphysics of cirrus clouds. It is shown that the strong 1.38 μm water vapor band in the near-IR region is superior to the other three IR channels used in current operational satellites and has potential possibility of remote sensing of microphysical and optical properties of cirrus clouds.     

Progress and prospects of studies on Polymyxa graminis and its transmitted cereal viruses in China

Polymyxa graminis is a eukaryotic obligate biotrophic parasite of plant roots that belongs to a poorly studied discrete taxonomic unit informally called “plasmodiophorids”. P. graminis is nonpathogenic, but has the ability to acquire and transmit nine plant viruses which belong to genera Bymovirus and Furovirus and cause serious diseases in cereal crop species and also result in significant yield reductions in China and elsewhere. Genus Bymovirus contains barley yellow mosaic virus (BaYMV), barley mild mosaic virus (BaMMV), wheat yellow mosaic virus (WYMV), wheat spindle streak mosaic virus (WSSMV), and oat mosaic virus (OMV), and genus Furovirus contains soil-borne wheat mosaic virus (SBWMV), oat golden stripe virus (OGSV), and newly identified Chinese wheat mosaic virus (CWMV) and soil-borne cereal mosaic virus (SBCMV). All these viruses have been sequenced and their worldwide distributions have been studied. The viruses are protected by the environment within P. graminis resting spores that may remain dormant but viable for decades (probably until a suitable host plant is encountered). Spontaneous deletion mutants of SBWMV, OGSV and OMV are detected, and these deletion mutants are not transmissible by the fungus. The persistent, soil-borne nature of these diseases makes the use of virus-resistant crop varieties currently the only practical and environmentally friendly means to control them, and a large number of disease resistant germplasms have been screened.     

Change of bacterial community in the Malan Ice Core and its relation to climate and environment

In order to understand the relationship between the community structure of bacteria in ice core and the past climate and environment, we initiated the study on the microorganisms in the three selected ice samples from the Malan ice core drilled from the Tibetan Plateau. The 16S ribosomal DNA (rDNA) molecules were directly amplified from the melt water samples, and three 16S rDNA clone libraries were established. Among 94 positive clones, eleven clones with unique restriction pattern were used for partial sequence and compared with eight reported sequences from the same ice core. The phylotypes were divided into 5 groups: alpha, beta, gamma proteobacteria; CFB, and other eubacteria group. Among them, there were many “typical Malan glacial bacteria“ pertaining to psychrophilies and new bacteria found in the ice core. At a longer time scale, the concentration distribution of “typical Malan glacial bacteria“ with depth showed negative correlation with temperature variations and was coincident with dirty layer. It implied the influence of temperature on the microbial record through impact on the concentrations of the “typical Malan glacial bacteria“. In addition, the nutrition contained in ice was another important factor controlling the distribution of microbial population in ice core section. Moreover, the result displayed an apparent layer distribution of bacterial community in the ice core section, which reflected the microbial response to the past climatic and environmental conditions at the time of deposition.     

Left-lateral shear deformation found in southern part of the Gaoligong range in west Yunnan and its tectonic implications

LocatedinthesouthwestborderareaofChina ,theGaoligongrangeisauniquegeologicandgeomor phologicfeature ,withitssnow cappedsummitele vatedupto 35 88mabovesealevel.ItgoesupnorthalongtheNuRivertoeasternTibet ,joiningupwiththeBoshulalingrange ,anddownsouthtotheareaofLongling ,whereitdescendsrapidlyandsplitsupintoseverallowandlinearridges .RespectivelytothewestandeastoftherangearetheTengchongandBaoshanblocks ,themainpartofwhich ,anarrowbeltofin tensivelydeformedmetamorphicrocksnamedGaoligongGroup …     

Main seagrass beds and threats to their habitats in the coastal sea of South China

The distribution, species, biomass, productivity of main seagrasses and their suffered main threats are introduced and discussed in this paper based on the field surveys in the offshore areas of Guangdong, Guangxi and Hainan provinces. The seagrass beds distributed mainly in Liusha Bay, Donghai Island and Hailing Island of Guangdong Province; Hepu and Pearl Bay of Guangxi Zhuang Autonomous Region; Li＇an Bay, Xincun Bay, Longwan Bay and Sanya Bay of Hainan Province and so on. The total area of seagrass beds in the coastal sea of South China is about 2400 ha. There are about 8 species, such as Halophila ovalis, Halodule uninervis, Halophila beccarii, Zostera japonica, Enhalus acoroides, Thalassia hemperichii, Ruppia martime and Cymodocea rotundata. These seagrasses have high biomass and productivity. However, they are subjected to some threats resulting from artificial and natural factors, especially anthropogenic causes, such as culture of shrimps and fishes, shellfish collection, fishing by means of poisons, electric power and explosives as well as trawling, artificial pollution, dredging channels, and typhoons natural disaster.     

Induction of nicotine in tobacco by herbivory and its relation to glucose oxidase activity in the labial gland of three noctuid caterpillars

Tobacco Nicotiana tabacum L. is a host plant ofHelicoverpa armigera (Huibner), Helicoverpa assulta Guenee and Spodoptera litura (Fabricius) (Lepidoptera, Noctuidae). The difference in leaf nicotine response to the feeding by these three larvae and the mechanical simulation of their feeding was examined by HPLC. Results indicated that nicotine induction was suppressed by H. armigera and H. assulta larvae feeding or by simulated damage treated with their labial glands extracts. The production of nicotine was also suppressed by the glucose oxidase from Aspergillus niger when it was treated on mechanically wounded leaf area. On the contrary, the nicotine production was stimulated by S. litura larva feeding or by simulated damage treated with its labial gland extract. Heat denature can not counteract the stimulation effect of the S. litura labial gland extracts to tobacco nicotine production. The glucose oxidase activity was detected in labial gland extracts of both H. armigera and H. assulta, but the activity in H. armigera was significantly higher than that in H. assulta. No glucose oxidase activity was detected in labial gland extracts of S. litura. It is shown that the glucose oxidase activity in labial glands of caterpillars plays an important role in the nicotine response to herbivory. The glucose oxidase was mainly contained in the labial gland of H. armigera larva, and had the highest activity at pH 7.0. D-Glucose was the optimal substrate of the glucose oxidase. Labial gland glucose oxidase activities varied daily during larval development with high activities found when larvae were actively feeding.     

Modification of a viral satellite DNA-based gene silencing vector and its application to leaf or flower color change in Petunia hybrida

Gene silencing conserved in plants and animals is mediated by mechanisms that involve sequence- specific RNA degradation[1,2]. Gene silencing has been proven to play an important role in the study of gene function. Recently, a procedure known as virus ind…     

Twenty-five years of change in scleractinian coral communities of Daya Bay （northern South China Sea） and its response to the 2008 AD extreme cold climate event

Coral reefs worldwide are becoming increasingly and detrimentally impacted upon by a variety of factors including significant climate changes, such as global warming and increased El Nino-Southern Oscillation activity. Generally, the persistence of coral reefs, especially at low-latitudes, is governed, in part, by sea surface temperatures not exceeding the critical limit （-30℃） at which mass mortality can occur. Thus, it is thought that corals living at high-latitudes （i.e., currently cooler sea surface temperatures） will likely respond more favourably to hypothesized future temperature increases than corals living at low-latitudes （i.e., currently warmer sea surface temperatures）. Consequently, high-latitude coral communities may have the potential to act as regions of refugia for many coral species in the face of potential future global warming. The Daya Bay （22°31′--22°50′N）, northern South China Sea, contains several high-latitude non-reefal coral communities and represents one of the most northerly distributions of scleractinian corals within the region. Significantly, Daya Bay has experienced dramatic warming in both air and sea surface temperatures throughout the past 50 years. In this paper, we analyze 25 years of change in the Daya Bay coral communities, based both on historic surveys and our latest 2006--2008 regional ecological surveys. Our results suggest that, contrary to predictions, there have been significant declines in coral cover within the Daya Bay during the past 25 years （i.e., 76.6% coral cover in 1983/1984 to only 15.3% coral cover by 2008）. Such changes also reflect a significant shift in the most abundant coral species, from Acropora pruinosa to Favites abdita. Most of the modern coral communities became established between 15 and 30 years ago, corresponding to a period of increased winter sea surface temperature. However, very few colonies have become established within the last 15 years, despite a more intense period of warming. By taking into account additional factors, we hypothesize that direct anthropogenic impacts, rather than climatic events, have both restricted the development, and drove the decline, of Daya Bay coral communities in the last 15 years. The Daya Bay has also been subjected to occasional extreme cold events during the past 50 years, with the most recent occurring in early 2008 （13 January-13 February）. During the 2008 cold event, the lowest air temperature reaches only 6.6℃, and the mean sea surface temperature for February fall to 〈 14℃, including six continuous days at 12.3℃. Significantly, the sea surface temperatures fall below the hypothesized critical lower temperature threshold （-13℃） that commonly leads to mass mortality in scleractinian coral communities. Surprisingly, our coral community surveys, conducted both before （August 2007） and after （late February 2008） the extreme 2008 cold event, demonstrate that the Daya Bay coral ecosystems are barely impacted upon during the cold period. Those observations suggest that the Daya Bay scleractinian coral communities have developed adaptations to low sea surface temperatures. Overall, our data support the hypothesis that high-latitude coral communities, such as Daya Bay, have the potential to act as areas of refugia for scleractinian corals in the advent of potential future global warming.     

Opening of the Tethys in southwest China and its significance to the breakup of East Gondwanaland in late Paleozoic:Evidence from SHRIMP U-Pb zircon analyses for the Garzêophiolite block

SHRIMP U-Pb zircon analyses for a gabbro sample from the Garzê ophiolite block yielded a mean²⁰⁶Pb/²³⁸U age of 292 ±4 Ma, which indicated that the spreading time of the Garzê-Litang Tethys was most likely at the earliest Permian. Combined with previous studies, we suggest that the opening of the Tethys in southwest China was derived from breakup of the East Gondwanaland in the late Paleozoic.     

Opening of the Tethys in southwest China and its significance to the breakup of East Gondwanaland in late Paleozoic:Evidence from SHRIMP U-Pb zircon analyses for the Garzêophiolite block

The orogeny in the Sanjiang area in southwest Chinahas traditionally been considered as the product of theevolution of the Tethys in the late Paleozoic to the earlyMesozoic, and strongly affected by India-Asia collision inthe Cenozoic. Geological mappings showed that the San-jiang area contains four tectonic mélanges, named theGarzê-Litang, Jinshajiang-Ailaoshan, Lancangjiang-Men-glian-Changning and Dingqing-Basu ophiolite mélanges,associated with the Yidun, Jomda-Weixi, Suiba-Nanzu…     

Marinamide, a novel alkaloid and its methyl ester produced by the application of mixed fermentation technique to two mangrove endophytic fungi from the South China Sea

For a long time, terrestrial microorganisms are abundant natural pharmaceutical resource for human, but it becomes more and more difficult to find new species and microorganisms with special functions from land as the research goes on. Consequently, the s…     

Molecular characterization of GmNHX2, a Na＋/H＋ antiporter gene homolog from soybean,and its heterolosous expression to improve salt tolerance in Arabidopsis

Na＋/H＋ antiporters have been well documented to enhance plant salt tolerance by regulating cellular ion homeostasis. Here, a putative Na＋/H＋ antiporter gene homolog GmNHX2 from soybean was cloned and predicted to encode a protein of 534 amino acids with 10 putative transmembrane domains. GmNHX2 was expressed in all soybean plant tissues but enriched in roots and its expression was induced by NaCI and polyethylene glycol （PEG） treatments. GmNHX2 exhibits greater sequence similarity with LeNHX2 and AtNHX6 than that of AtNHX1 and AtSOS1. Although phylogenetic analysis clustered GmNHX2 with organellar （tonoplast and vesicles） antiporters, the GmNHX2-EGFP （enhanced green fluorescent protein） fusion protein was possibly localized in the plasma membrane or organelle membrane of transgenic plant cells, Furthermore, transgenic Arabidopsis plants expressing GmNHX2 were more tolerant to high NaCl concentrations during germination and seedling stages when compared with wild-type plants. These results suggest that GmNHX2 is a membrane Na＋/H＋ antiporter and may function to regulate ion homeostasis under salt stress.     

A study on responses of soil erosion and sediment yield to closing cultivation on sloping land in a small catchment using ^137Cs technique in the Rolling Loess Plateau, China

By comparison of volumes and ^137Cs Contents of the deposited sediments before and after 1993,changes of specific sediment yields and relative sediment contributions from the gully area and from the inter gully area after closing cultivation on the later area on a small catchment of Zhaojia Gully,in the Rolling Loess Plateau,are analyzed in this paper.Closing cultivation in a large scale has not resulted in decrease but increase of specific sediment yield and the relative sediment contribution of the inter-gully area,and in increase of the sediment yield and the contribution of the gully area,for a short term.The mean specific sediment yield of 29650 t km^-2a^-1 of 1994-1996 in the catchment was 2.2 times the average value of 13413 t km^-2 a^-1 for a long term.The specific sediment yield of the inter-gully area decreased from the 14335t km^-2a^-1 in 1994 to 7034 t km^-2 a^-1 in 1995 and 3517 t km^-1a^-1 in 1996 which was much greater than the value of 21118 t km^-2 a^-1 before 1993.The relative sediment contribution from the inter-gully area decreased form 23% in 1994 to 15% in 1995 and 6% in 1996,while the contribution from the gully area increased form 77% in 1994 to 85% in 1995 and 94% in 1996.It is suggested that compacting of ploughed soils resulted in increasing of the erosion resistance but in decreasing of the precipitation infiltration,therefore,the soil erosion reduced but the runoff amount increased on the inter-gully area.Increase of delivering runoff from the inter-gully area to the gully area should result in activeness of gully erosion and mass movements,consequently,in increase of the total sediment yield from the catchment.