High Cyanobacterial Abundance in Three Northeastern Gulf of Mexico Estuaries

Aquatic phytoplankton comprise a wide variety of taxa spanning more than 2 orders of magnitude in size, yet studies of estuarine phytoplankton often overlook the picoplankton, particularly chroococcoid cyanobacteria (cf. Synechococcus). Three Gulf of Mexico estuaries (Apalachicola Bay, FL; Pensacola Bay, FL; Weeks Bay, AL) were sampled during summer and fall 2001 to quantify cyanobacterial abundance, to examine how cyanobacterial abundance varied with hydrographic and nutrient distributions, and to estimate the contribution of cyanobacteria to the bulk phytoplankton community. Cyanobacterial abundances in all 3 estuaries were high, averaging 0.59 ± 0.76 X 109 L–1 in Apalachicola Bay, 1.7 ± 1.2 X 109 L–1 in Pensacola Bay and 2.4 ± 1.9 X 109 L–1 in Weeks Bay (mean ± standard deviation). Peak abundances typically occurred in the oligohaline zone (low salinity estuarine zone) during the summer. Freshwater sites had nearly undetectable abundances, and marine sites had abundances several-fold lower than the oligohaline zone. When converted to equivalent chlorophyll a concentrations, cyanobacteria comprised a large fraction of the total phytoplankton biomass, at times approaching 100% in all 3 systems. These observations clearly indicate a cyanobacterial community of estuarine origin that can make up a large proportion of phytoplankton biomass

Effect of intramuscular methadone on pharmacokinetic data and thermal and mechanical nociceptive thresholds in the cat

Objectives The aim of the study was to assess simultaneous pharmacokinetics and thermal and mechanical antinociception after intramuscular methadone (0.6 mg/kg) in 10 cats. Methods Thermal and mechanical threshold (TT and MT, respectively) testing and blood collection were conducted at baseline and up to 24 h after administration. Methadone plasma concentrations were determined by liquid chromatography–tandem mass spectrometry and pharmacokinetic parameters were estimated by a non-compartmental method. TT and MT were analysed using ANOVA ( P &lt;0.05). Time of maximum plasma concentration (Tmax), time of onset of antinociception and time of reaching cut-out threshold (TT 55°C; MT 30 Newtons [N]) were determined. Results TT and MT increased above baseline from 20–240 mins and 5–40 mins, respectively, after intramuscular (IM) administration ( P &lt;0.005). Mean maximum delta T (measured as TT minus baseline threshold) was 7.9°C (95% confidence interval [CI] 4.3–11.6) at 60 mins and mean maximum delta F (measured as MT minus baseline threshold) was 4.2 (95% CI 1.6–6.7) N at 45 mins. IM methadone concentration–time data decreased curvilinearly, and gave a clearance estimate of mean 9.1 ml/kg/min (range 5.2–15.7) with median Tmax at 20 mins (range 5–360 mins). Conclusions and relevance IM data followed classical disposition and elimination in all cats. Plasma concentrations after IM administration were associated with an antinociceptive effect, including negative hysteresis. These data can be used for devising dosing schedules for methadone in clinical feline practice. </jats:sec

Feasibility and systems definition study for Microwave Multi-Application Payload (MMAP)

Work completed on three Shuttle/Spacelab experiments is examined: the Adaptive Multibeam Phased Array Antenna (AMPA) Experiment, Electromagnetic Environment Experiment (EEE) and Millimeter Wave Communications Experiment (MWCE). Results included the definition of operating modes, sequence of operation, radii of operation about several ground stations, signal format, foot prints of typical orbits and preliminary definition of ground and user terminals. Conceptual hardware designs, Spacelab interfaces, data handling methods, experiment testing and verification studies were included. The MWCE-MOD I was defined conceptually for a steerable high gain antenna

Regulation of plasmid-encoded isoprene metabolism in Rhodococcus, a representative of an important link in the global isoprene cycle

Emissions of biogenic volatile organic compounds (VOCs) form an important part of the global carbon cycle, comprising a significant proportion of net ecosystem productivity. They impact atmospheric chemistry and contribute directly and indirectly to greenhouse gases. Isoprene, emitted largely from plants, comprises one third of total VOCs, yet in contrast to methane, which is released in similar quantities, we know little of its biodegradation. Here, we report the genome of an isoprene degrading isolate, Rhodococcus sp. AD45, and, using mutagenesis shows that a plasmid-encoded soluble di-iron centre isoprene monooxygenase (IsoMO) is essential for isoprene metabolism. Using RNA sequencing (RNAseq) to analyse cells exposed to isoprene or epoxyisoprene in a substrate-switch time-course experiment, we show that transcripts from 22 contiguous genes, including those encoding IsoMO, were highly upregulated, becoming among the most abundant in the cell and comprising over 25% of the entire transcriptome. Analysis of gene transcription in the wild type and an IsoMO-disrupted mutant strain showed that epoxyisoprene, or a subsequent product of isoprene metabolism, rather than isoprene itself, was the inducing molecule. We provide a foundation of molecular data for future research on the environmental biological consumption of this important, climate-active compound

Benthic Nutrient Flux in a Small Estuary in Northwestern Florida (USA)

Benthic nutrient fluxes of ammonium (NH4+), nitrite/nitrate (NO2- + NO3-), phosphate (PO4-3), and dissolved silica (DSi) were measured in Escambia Bay, an estuary within the larger Pensacola Bay system of northwestern Florida (USA). Our study occurred during a severe drought which reduced riverine inputs to Escambia Bay. Laboratory incubations of field-collected cores were conducted on 8 dates between June and October 2000 to estimate nutrient flux, and cores were collected from locations exhibiting a range of sediment organic matter content. NH4+ flux ranged from – 48.1 to 110.4 μmol m-2 h-1, but the mean flux was 14.6 μmol m-2 h-1. Dissolved silica (DSi) fluxes were also variable (-109. 3 to 145.3 μmol m-2 h-1), but the mean net flux (9.3 μmol m-2 h-1) was from the sediment to the water column. Bay sediment fluxes for NO2-+ NO3- and PO4-3 were less variable during this period (– 7.93 to 28.73 and – 1.74 to 3.29 μmol m-2 h-1 for NO2-+ NO3- and PO4-3, respectively). Low NH4+ fluxes were similar to published estimates from lagoonal Gulf of Mexico (GOM) estuaries, possibly due to the reduced freshwater input. Diminished regeneration of phosphate relative to inorganic nitrogen observed during the study period was consistent with previous research in Pensacola Bay suggesting phytoplankton phosphorus limitation. Finally, the estimated residence time of Escambia Bay and the mean turnover times for NH4+ and NO2-+ NO3- suggested that benthic flux significantly influenced nitrogen concentrations in overlying water

The biosynthetic gene cluster for the anticancer drug bleomycin from \u3ci\u3eStreptomyces verticillus\u3c/i\u3e ATCC15003 as a model for hybrid peptide–polyketide natural product biosynthesis

The hybrid peptide–polyketide backbone of bleomycin (BLM) is assembled by the BLM megasynthetase that consists of both nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) modules. BlmIX/BlmVIII/BlmVII constitute a natural hybrid NRPS/PKS/NRPS system, serving as a model for both hybrid NRPS/PKS and PKS/NRPS systems. Sequence analysis and functional comparison of domains and modules of BlmIX/BlmVIII/BlmVII with those of nonhybrid NRPS and PKS systems suggest that (1) the same catalytic sites appear to be conserved in both hybrid NRPS–PKS and nonhybrid NRPS or PKS systems, with the exception of the KS domains in the hybrid NRPS/PKS systems that are unique; (2) specific interpolypeptide linkers may play a critical role in intermodular communication to facilitate transfer of the growing intermediates between the interacting NRPS and/or PKS modules; and (3) posttranslational modification of the BLM megasynthetase has been accomplished by a single PPTase with a broad substrate specificity toward the apo forms of both acyl carrier proteins (ACPs) and peptidyl carrier proteins (PCPs)

Long-term and trans-generational effects of neonatal experience on sheep behaviour

Early life experiences can have profound long-term, and sometimes trans-generational, effects on individual phenotypes. However, there is a relative paucity of knowledge about effects on pain sensitivity, even though these may impact on an individual's health and welfare, particularly in farm animals exposed to painful husbandry procedures. Here, we tested in sheep whether neonatal painful and non-painful challenges can alter pain sensitivity in adult life, and also in the next generation. Ewes exposed to tail-docking or a simulated mild infection (lipopolysaccharide (LPS)) on days 3–4 of life showed higher levels of pain-related behaviour when giving birth as adults compared with control animals. LPS-treated ewes also gave birth to lambs who showed decreased pain sensitivity in standardized tests during days 2–3 of life. Our results demonstrate long-term and trans-generational effects of neonatal experience on pain responses in a commercially important species and suggest that variations in early life management can have important implications for animal health and welfare