Effects of Water Quality on Hypoxia in the Gulf of Mexico

In many aquatic systems, incidences of low oxygen (hypoxia) waters have been causally linked to increased nutrient concentrations. The Mississippi River accounts for approximately 80-90% of the freshwater inflow to the Gulf of Mexico; water quality in the Mississippi River should serve as a indicator of conditions in the Gulf. Near its mouth, the Mississippi River splits, with approximately one-third of its discharge diverted into the Atchafalaya River. A review of the literature (primarily peer reviewed journals and technical publications) suggests that the Mississippi River waters enriches the Gulf of Mexico and this enrichment has increased in recent years. However, 21 years of data collected and published by the United States Geological Survey indicates no change in total phosphorus. Nitrogen values for the Mississippi River have increased (concomitantly with a decline in nitrogen values in the Atchafalaya River). There is good evidence that hypoxic areas in the Gulf of Mexico have increased following the 1993 flooding of the central midwestern United States. The timing and intensity of river discharge into the Mississippi River apparently controls the duration and extent of hypoxia within the Gulf of Mexico

The Distribution of Ceratia Over the Mid-Atlantic Bight

The distribution and concentration of Ceratium species, between Cape Hatteras, North Carolina and Long Island, New York ls discussed in relation to specific physical factors and the development of a phytoplankton bloom. The progression of high Ceratium counts Is discussed for the Bight areas of New York, Delaware, and the Chesapeake Bay (April through June). The concentration of Ceratium species declined after June, with highest concentrations along the New York and Delaware coast-lines. Coastal regions (less than 12 km from shore) were associated with high concentrations of several species. Path and regression analysis were used to relate physical factors and cell concen­tration. Multiple regression analysis explained more variation in cell concentration than path analysis

Controlling formation of metal ion adducts and enhancing sensitivity in Liquid Chromatography Mass Spectrometry

Formation of metal ion adducts in mass spectrometry, particularly in electrospray ionization liquid chromatography mass spectrometry (ESI-LC-MS), is a nightmare scenario for an analyst dealing with quantitative analysis. We have studied in detail the metal adduct formation and concluded  that the use of fluorinated alkanoic acids along with formic acid and volatile ammonium salts was extremely useful in suppressing metal adduct formation in positive ion mode of ESI-LC-MS. The extremely high electronegativity of fluorine atom and unique electrostatic nature of C—F bond coupled with stereo-electronic interactions with neighboring bonds or lone pairs enables the polyfluorinated alkanoic acids in trapping highly electropositive ions (Na+, K+) thereby letting proton do its job efficiently. Addition of formic acid, trifluoroacetic acid, heptafluorobutyric acid and ammonium acetate was found to be extremely effective in controlling metal ion adducts and producing [M+H]+ ions almost exclusively resulting in significant increase in the sensitivity. This technique has been successfully used in our laboratory for the estimation of targeted and nontargeted analysis of pesticides, marine toxins, drugs and pharmaceuticals etc. in various matrices including environmental waters using liquid chromatography-time of flight mass spectrometer operated in all ion acquisition mode and triple quadruples (QQQ) in multiple reaction monitoring (MRM) mode

Targeted and non-targeted analysis of organic compounds of moderate polarity in water using liquid chromatography-time of flight mass spectrometry in all ion mode with particular reference to analysis of pesticides

We have developed a novel yet efficient method for the multi residue analysis of organic compounds of diverse polarities in water using Liquid Chromatography-Time of Flight mass spectrometry (LC-MS-TOF) equipped with a jet stream Electrospray ionization (ESI) source. Use of three different fragmentor voltages (low, medium and high) enabled the qualitative and quantitative analysis of a diverse range of targeted organic compounds in environmental waters. No prior optimization of compounds being quantified was required, the limiting factors were ionization behaviour of compounds under conditions of ESI and good chromatography. Same data file could be subjected to repeated post-run data analysis to figure out the presence of non-targeted compounds, including designer drugs if any. The technique has been illustrated with reference to a group of pesticides having diverse chromatographic and ionization behaviours. The optimized Solid Phase Extraction (SPE)  followed by method validation yielded a robust yet simple quantitative method for a group of fourteen pesticides. We were able to achieve quantitation at 10 ng/L or lower depending upon ionization behaviour of substrates against the usual regulatory requirement of 1000 ng/L. The method was used for targeted and non-targeted detection of pesticides in Nueces estuary waters, TX, USA, and several untargeted pesticides, pharmaceuticals and personal care products were identified

Effects of climate change on metabolite accumulation in freshwater and marine cyanobacteria

Global climate change and anthropogenic nutrient inputs are responsible for increased frequency of cyanobac- terial blooms that potentially contain 55 classes of bioactive metabolites. This study investigated the effects of CO2 availability and concomittant pH levels on two cyanobacteria that produce microcystins: a marine cf. Syne- chocystis sp. and a freshwater Microcystis aeruginosa. Cyanobacterial strains were semi-continuously cultured in mesotrophic growth media at pH 7.5, 7.8, 8.2, and 8.5 via a combination of CO2 addition and control of alkalinity. The cell concentration between treatments was not significantly different and nutrient availability was not lim- ited. Concentration of most known cyanobacterial bioactive metabolites in both cyanobacterial strains increased as CO2 increased. At pH 7.8, bioactive metabolite intracellular concentration in M. aeruginosa and Synechocystis was 1.5 and 1.2 times greater than the other three treatments, respectively. Intracellular concentration of mi- croginin in M. aeruginosa at pH 7.5 was reduced by 90% compared to the other three treatments. Intracellular concentration of microcyclamide-bistratamide B was lower in M. aeruginosa and higher in Synechocystis at ele- vated CO2 concentration. M. aeruginosa products were more diverse metabolites than Synechocystis. The diversity of accumulated metabolites in M. aeruginosa increased as CO2 increased, whereas the metabolite diversity in Syne- chocystis decreased as pH decreased. Overall, intracellular concentration of bioactive metabolites was higher at greater CO2 concentrations; marine and freshwater cyanobacteria had different allocation products when exposed to differing CO2 environments

A Comparison of Salinity Effects from Hurricanes Dolly (2008) and Alex (2010) in a Texas Lagoon System

A comparison of salinity effects from hurricanes Dolly (2008) and Alex (2010) in a Texas lagoon system.Hurricanes are not uncommon along the Gulf of Mexico coast, but there are few studies of the effects they have on coastal embayments. Hurricanes Dolly (2008) and Alex (2010) were both Category 2 storms affecting the Lower Laguna Madre (LLM) of Texas. Surveys were performed to assess poststorm water quality after landfall of both storms at up to 18 sample stations. The main difference between storm effects was salinity reduction because of stormwater input from the watershed. Effects from Hurricane Dolly were of short duration and small magnitude, whereas the effects from Hurricane Alex were extensive and lasted more than a month. Differences in spatial patterns in salinity were significantly more pronounced across the LLM than were temporal differences. Precipitation of 50–100 cm caused stormwater discharge to exceed 1000 m s−1 to the LLM during the Alex event and depressed salinity over more than three-fourths (ca. 500 km2) of the estuary for 2 months. Storm-related effects on water-column physiochemistry were persistently lowest near freshwater drains (Arroyo Colorado). Salinity remained less than 5 for more than 2 months during the Alex freshet. Freshwater input from Hurricane Dolly was relatively minor because the storm precipitation was largely restricted to the small Arroyo Colorado watershed. Effects from Alex were delayed but were greater because of the bulk of the precipitation falling in the Rio Grande/Rio Bravo drainage basin in México. The greatest impact from that freshwater disturbance was the loss of seagrasses after prolonged exposure to hyposalinity. Hurricanes Dolly and Alex both affected the LLM but with contrasting impacts that reflected spatial and meteorological differences between the two storms

Tricholides A and B and Unnarmicin D: New Hybrid PKS-NRPS Macrocycles Isolated from an Environmental Collection of Trichodesmium thiebautii

Bioassay-guided isolation of the lipophilic extract of Trichodesmium thiebautii bloom material led to the purification and structure characterization of two new hybrid polyketide-non-ribosomal peptide (PKS-NRPS) macrocyclic compounds, tricholides A and B (1 and 2). A third macrocyclic compound, unnarmicin D (3), was identified as a new depsipeptide in the unnarmicin family, given its structural similarity to the existing compounds in this group. The planar structures of 1–3 were determined using 1D and 2D NMR spectra and complementary spectroscopic and spectrometric procedures. The absolute configurations of the amino acid components of 1–3 were determined via acid hydrolysis, derivitization with Marfey’s reagent and HPLC-UV comparison to authentic amino acid standards. The absolute configuration of the 3-hydroxydodecanoic acid moiety in 3 was determined using a modified Mosher’s esterification procedure on a linear derivative of tricharmicin (4) and additionally by a comparison of 13C NMR shifts of 3 to known depsipeptides with β-hydroxy acid subunits. Tricholide B (2) showed moderate cytotoxicity to Neuro-2A murine neuroblastoma cells (EC50: 14.5 ± 6.2 μM)

The transcriptome of Euglena gracilis reveals unexpected metabolic capabilities for carbohydrate and natural product biochemistry

Euglena gracilis is a highly complex alga belonging to the green plant line that shows characteristics of both plants and animals, while in evolutionary terms it is most closely related to the protozoan parasites Trypanosoma and Leishmania. This well-studied organism has long been known as a rich source of vitamins A, C and E, as well as amino acids that are essential for the human diet. Here we present de novo transcriptome sequencing and preliminary analysis, providing a basis for the molecular and functional genomics studies that will be required to direct metabolic engineering efforts aimed at enhancing the quality and quantity of high value products from E. gracilis. The transcriptome contains over 30?000 protein-encoding genes, supporting metabolic pathways for lipids, amino acids, carbohydrates and vitamins, along with capabilities for polyketide and non-ribosomal peptide biosynthesis. The metabolic and environmental robustness of Euglena is supported by a substantial capacity for responding to biotic and abiotic stress: it has the capacity to deploy three separate pathways for vitamin C (ascorbate) production, as well as producing vitamin E (?-tocopherol) and, in addition to glutathione, the redox-active thiols nor-trypanothione and ovothiol