Otolith characteristics and age determination of an endemic Ptychobarbus dipogon (Regan, 1905) (Cyprinidae: Schizothoracinae) in the Yarlung Tsangpo River, Tibet

We describe the microincrements, checks and annuli in the lapilli of the schizothoracine Ptychobarbus dipogon, an endemic species of the Tibetan plateau. We collected samples in the Yarlung Tsangpo River and its tributaries on a monthly basis (from April 2004 to August 2006). We describe the shape features of the three pairs of otoliths and document the full trajectory of lapillus development. We found that five to seven checks were clearly visible in the opaque zone of the first annulus. The pattern of 21-23 daily growth increments within each check might be explained as a lunar-induced deposition. We counted between 137 and 154 increments within the first annulus. Annuli appeared as a sequence of gradually declining increment widths, whereas false rings were characterized by abrupt checks. Our oldest estimates were 23(+)years for males and 44(+) for females. The time of annulus completion was clearly between March and April each year using monthly marginal increments analysis. We consider the factors responsible for daily increment formation as an endogenous circadian rhythm. Environmental information, such as strong sunlight and cold water temperatures in the Tibetan Plateau, could reinforce the endogenous daily cycle. Our results provided important data addressing the ecology and population dynamics of P. dipogon.

Detection of microcystins in environmental samples using surface plasmon resonance biosensor

An indirect inhibitive surface plasmon resonance (SPR) immunoassay was developed for the microcystins (MCs) detection. The bioconjugate of MC-LR and bovine serum albumin (BSA) was immobilized on a CM5 sensor chip. A serial premixture of MC-LR standards (or samples) and monoclonal antibody (mAb) were injected over the functional sensor surface, and the subsequent specific immunoreaction was monitored on the BIAcore 3000 biosensor and generated a signal with an increasing intensity in response to the decreasing MCs concentration. The developed SPR immunoassay has a wide quantitative range in 1-100 mu g L-1. Although not as sensitive as conventional enzyme-linked immunosorbent assay (ELISA), the SPR biosensor offered unique advantages: (I) the sensor chip could be reusable without any significant loss in its binding activity after 50 assay-regeneration cycles, (2) one single assay could be accomplished in 50 min (including 30-min preincubation and 20-min BIAcore analysis), and (3) this method did not require multiple steps. The SPR biosensor was also used to detect MCs in environmental samples, and the results compared well with those obtained by ELISA. We conclude that the SPR biosensor offers outstanding advantages for the MCs detection and may be further developed as a field-portable sensor for real-time monitoring of MCs on site in the near future. (C) 2009 Published by Elsevier B.V.

Rapid quantification of total microcystins in cyanobacterial samples by periodate-permanganate oxidation and reversed-phase liquid chromatography

Microcystins (MCs) comprise a family of more than 80 related cyclic hepatotoxic heptapeptides. Oxidation of MCs causes cleavage of the chemically unique C-20 beta-amino acid (2S, 3S, 8S, 9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (Adda) amino to form 2-methyl-3-methoxy-4-phenylbutanoic acid (MMPB), which has been exploited to enable analysis of the entire family. In the present study, the reaction conditions (e.g. concentration of the reactants. temperature and pH) used in the production of MMPB by oxidation of cyanobacterial samples with permanganate-periodate were optimized through a series of well-controlled batch experiments. The oxidation product (MMPB) was then directly analyzed by high-performance liquid chromatography with diode array detection. The results of this study provided insight into the influence of reaction conditions on the yield of MMPB. Specifically, the optimal conditions, including a high dose of permanganate (>= 50 mM) in saturated periodate solution at ambient temperature under alkaline conditions (pH similar to 9) over 1-4 h were proposed, as indicated by a MMPB yield of greater than 85%. The technique developed here was applied to determine the total concentration of MCs in cyanobacterial bloom samples, and indicated that the MMPB technique was a highly sensitive and accurate method of quantifying total MCs. Additionally, these results will aid in development of a highly effective analytical method for detection of MMPB as an oxidation product for evaluation of total MCs in a wide range of environmental sample matrices, including natural waters, soils (sediments) and animal tissues. (C) 2009 Elsevier B.V. All rights reserved.

Control of lunar and martian dust - Experimental insights from artificial and natural cyanobacterial and algal crusts in the desert of Inner Mongolia, China

Studies on the colonization of environmentally extreme ground surfaces were conducted in a Mars-like desert area of Inner Mongolia, People's Republic of China, with microalgae and cyanobacteria. We collected and mass-cultured cyanobacterial strains from these regions and investigated their ability to form desert crusts artificially. These crusts had the capacity to resist sand wind erosion after just 15 days of growth. Similar to the surface of some Chinese deserts, the surface of Mars is characterized by a layer of fine dust, which will challenge future human exploration activities, particularly in confined spaces that will include greenhouses and habitats. We discuss the use of such crusts for the local control of desert sands in enclosed spaces on Mars. These experiments suggest innovative new directions in the applied use of microbe-mineral interactions to advance the human exploration and settlement of space.

A novel chemiluminescent immunoassay for microcystin (MC) detection based on gold nanoparticles label and its application to MC analysis in aquatic environmental samples

A novel chemiluminescent immunoassay method based on gold nanoparticles was developed for the detection of microcystins (MCs). The immunoassay included three main steps: indirect competitive immunoreaction, oxidative dissolution of gold nanoparticles, and indirect determination for MCs with Au3+-catalysed luminol chemiluminesent system. The method has a wide working range (0.05-10 mu g L-1, r(2) = 0.9914), the limit of detection was determined to be 0.024 mu g L-1, which is much lower than the World Health Organization's proposed guidelines (1 mu g L-1) for drinking-water. The proposed method was applied to MC analysis in natural water and fish tissue samples, and most results in the proposed method were in agreement with the conventional indirect competitive enzyme-linked immunosorbent assay method, which indicated that the new chemiluminescent immunoassay was sensitive, reliable, and suitable for MC analysis in natural water and fish tissue samples.

Taxonomic notes on water bloom forming Microcystis species (Cyanophyta) from China - An example from samples of the Dianchi Lake

Ten common species of Microcystis, based on the examination of water samples from the Dianchi Lake, Yunnan, China, were morphologically described, and their taxonomy was also discussed. They are Microcystis aeruginosa, M botrys, M firma, M flos-aquae, M ichthyoblabe, M novacekii, M pseudofilamentosa, M smithii, M viridis and M wesenbergii. Taxonomic status of other Microcystis species reported in China was also evaluated.

Detection of hepatotoxic Microcystis strains by PCR with intact cells from both culture and environmental samples

Microcystins are small hepatotoxic peptides produced by a number of cyanobacteria. They are synthesized non-ribosomally by multifunctional enzyme complex synthetases encoded by the mcy genes. Primers deduced from mcy genes were designed to discriminate between toxic microcystin-producing strains and non-toxic strains. Thus, PCR-mediated detection of mcy genes could be a simple and efficient means to identify potentially harmful genotypes among cyanobacterial populations in bodies of water. We surveyed the distribution of the mcyB gene in different Microcystis strains isolated from Chinese bodies of water and confirmed that PCR can be reliably used to identify toxic strains. By omitting any DNA purification steps, the modified PCR protocol can greatly simplify the process. Cyanobacterial cells enriched from cultures, field samples, or even sediment samples could be used in the PCR assay. This method proved sensitive enough to detect mcyB genes in samples with less than 2,000 Microcystis cells per ml. Its accuracy, specificity and applicability were confirmed by sequencing selected DNA amplicons, as well as by HPLC, ELISA and mouse bioassay as controls for toxin production of every strain used.

Peak identification for PCDD/Fs in environmental samples at different temperature programs

A method has been developed for peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at different temperature programs. Their retention behaviours are predicted on the basis of an identification database of retention values (A, B) of gas chromatography. By the retention times of C-13 labelled 2,3,7,8-substituted PCDD/F internal standards, the retentions of all PCDDs and PCDFs can be calculated. After comparison with the retentions of practical environmental samples, the predicted values have been proved to be very accurate. (C) 2000 Elsevier Science Ltd. All rights reserved.

A new enzyme immunoassay for PCDD/F TEQ screening in environmental samples: Comparison to micro-EROD assay and to chemical analysis

A new Enzyme ImmunoAssay (EIA) for PCDD/F TEQ measurement in extracts of environmental samples was described. The bioassay TEQ which derived from EIA and EROD were compared with each other and with results from chemical analysis. For all environmental samples, the EROD-TEQ is higher than the value from chemical analysis. However, the EIA-TEQ is much more identical with the value from chemical analysis. Our results indicate that the EIA assay is a complementary method to the EROD assay and should be useful as a rapid and sensitive screening tool for environmental samples in many situations. (C) 1999 Elsevier Science Ltd. All rights reserved

Comparative extraction of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F-s) from a variety of solid samples

Extraction experiments with spiking of C-13(12)-PCDD/Fs were performed with a variety of PCDD/Fs contaminated samples. The extraction recovery of PCDD/Fs was mainly influenced by PCDD/Fs concentration and the sample matrix. Generally, the first soxhlet extraction with toluene has suitable recovery. From the selected samples, only FAMS4 and 5 which are fly ashes with high concentration, the recovery of the first soxhlet extraction with 24 hr. is low, but PCDD/Fs were almost completely removed after 72 hr. Copyright (C) 1996 Elsevier Science Ltd

Computer assisted peak recognition for polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in environmental samples

A software has been developed for the peak recognition of 136 polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) after high resolution gas chromatography coupled with mass spectrometry (HRGC/HRMS). Based on the retention times of C-13 labelled 2,3,7,8-substituted PCDD/F internal standards, the retention times of all PCDD and PCDF can be calibrated automatically and accurately. Therefore, it is very convenient to identify the peaks by comparing the retention of samples and the calibrated retention times of their chromatograms. Hence, this approach is very significant because it is impossible to obtain always a standard chromatogram and PCDD/F analysis are very expensive and time consuming. The calibration results can be transferred to Excel for calculation. The approach is a first step to store costly and environmentally relevant data for future application.