12 research outputs found
Identification of morphological and chemical markers of dry- and wet-season conditions in female Anopheles gambiae mosquitoes
BACKGROUND: Increased understanding of the dry-season survival mechanisms of Anopheles gambiae in semi-arid regions could benefit vector control efforts by identifying weak links in the transmission cycle of malaria. In this study, we examined the effect of photoperiod and relative humidity on morphologic and chemical traits known to control water loss in mosquitoes. METHODS: Anopheles gambiae body size (indexed by wing length), mesothoracic spiracle size, and cuticular hydrocarbon composition (both standardized by body size) were examined in mosquitoes raised from eggs exposed to short photoperiod and low relative humidity, simulating the dry season, or long photoperiod and high relative humidity, simulating the wet-season. RESULTS: Mosquitoes exposed to short photoperiod exhibited larger body size and larger mesothoracic spiracle length than mosquitoes exposed to long photoperiod. Mosquitoes exposed to short photoperiod and low relative humidity exhibited greater total cuticular hydrocarbon amount than mosquitoes exposed to long photoperiod and high relative humidity. In addition, total cuticular hydrocarbon amount increased with age and was higher in mated females. Mean n-alkane retention time (a measure of cuticular hydrocarbon chain length) was lower in mosquitoes exposed to short photoperiod and low relative humidity, and increased with age. Individual cuticular hydrocarbon peaks were examined, and several cuticular hydrocarbons were identified as potential biomarkers of dry- and wet-season conditions, age, and insemination status. CONCLUSIONS: Results from this study indicate that morphological and chemical changes underlie aestivation of Anopheles gambiae and may serve as biomarkers of aestivation
Zirconium tetraazamacrocycle complexes display extraordinary stability and provide a new strategy for zirconium-89-based radiopharmaceutical development
89 Zr–Tetraazamacrocycle complexes display extraordinary stability
Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry identification of water-soluble atmospheric organic matter in polluted fog waters (invited)
The detailed molecular composition of water-soluble atmospheric organic matter (AOM) contained in fog water was studied by use of electrospray ionization ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. We identified hundreds of individual molecular masses in the range of 100-400 u as negative quasi-molecular ions. In our fog water samples, we found a high degree of complexity across the mass range of 100 to 400 u and in some cases our mass range extended up to 1000 u. The detected negative organic ions were multifunctional compounds which included C, H, N, O, and S elements. We observed organic nitrogen (CHNO), organic sulfur (CHOS), and organic nitrooxy-sulfate compounds (CHNOS) as well as many masses with only CHO elemental composition. Analysis of the double bond equivalents (DBE), the number of rings plus the number of double bonds to carbon, suggests that these compound structures range from highly aliphatic to aromatic with DBE values of 1-11. The compounds ranged in their extent of oxidation with oxygen to carbon ratios from 0.2 to 2 with an average value of 0.43. Several CH2 and C3H4O2 series of compounds were identified in this AOM. The high extent of CH2 homologous series of compounds likely originates from primary components that have become oxidized. Over 400 C3H4O2 series (sometimes referred to as oligomers) were also found. Overall, approximately 80% of the CHO and CHNO compounds can be linked through C3H4O2 series. The series appear to represent atmospheric processing of primary and secondary compounds. However, they may also result coincidentally by atomic valence of these elements and the very high number of ions detected in these AOM samples. In general, the isolated water-soluble components identified here are amphiphilic, thus they contain both hydrophilic oxygenated functional groups and hydrophobic aliphatic and aromatic structural moieties. Results and implications from our analysis of several samples of polluted fog water will be presented
Water-soluble atmospheric organic matter in fog: Exact masses and chemical formula identification by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry
The detailed molecular composition of water-soluble atmospheric organic matter (AOM) contained in fog water was studied by use of electrospray ionization ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. We identified 1368 individual molecular masses in the range of 100−400 Da from negative-ion spectra obtained after reversed-phase extraction with a hydrophilic solid phase sorbent. The detected organic anions are multifunctional with a variety of oxygenated functional groups. We observe organic nitrogen, organic sulfur, and organic nitrogen−sulfur compounds as well as many species with only C, H, and O elemental composition. Analysis of the double bond equivalents (DBE = the number of rings plus the number of double bonds to carbon) suggests that these compound structures range from highly aliphatic to aromatic with DBE values of 1−11. The compounds range in their extent of oxidation with oxygen to carbon ratios from 0.2 to 2 with an average value of 0.43. Several homologous series of compounds and multifunctional oligomers were identified in this AOM. The high extent of homologous series of compounds likely originates from primary components that have become oxidized. The multifunctional oligomers appear to represent atmospheric processing of primary and secondary compounds. The isolated water-soluble components identified here are amphiphilic, meaning that they contain both hydrophilic oxygenated functional groups and hydrophobic aliphatic and aromatic structural moieties. Despite the high number of compounds with very high oxygen content, 60% of assigned chemical formulas have measured organic mass-to-organic carbon ratios ≤2.25 (ranging from 1.25 to 3.5). Because the results reported here are not quantitative, an average ratio cannot be determined
Dataset linking free polyunsaturated fatty acid concentrations in erythrocytes with chronic pain conditions in adults
Circulating polyunsaturated fatty acids (PUFAs) and lipid mediators were extracted from human red blood cells and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method encompassed 13 different PUFAs and lipid mediators, however, due to instrument capability only five were confidently quantified (EPA, ALA, AA, DHA, and LA). The extraction focused on free polyunsaturated fatty acids since they have a strong correlation with health in humans. The study design was a secondary analysis of the OPPERA-2 study of chronic overlapping pain conditions in adults. The data included are: a) raw LC-MS/MS data (.raw); b) processed data (.xlsx) including chromatographic peak area for each compound and a concentration (ng/mL) based on external calibration with internal standardization using pure analytical grade standards and heavy-isotope labeled internal standards; c) study participant demographics and phenotypes (.xlsx). This dataset consisting of circulating PUFA quantities measured in 605 humans has been made publicly available for analysis and interpretation
Investigations of Analyte-Specific Response Saturation and Dynamic Range Limitations in Atmospheric Pressure Ionization Mass Spectrometry
With this study, we investigated
why some small molecules demonstrate
narrow dynamic ranges in electrospray ionization-mass spectrometry
(ESI-MS) and sought to establish conditions under which the dynamic
range could be extended. Working curves were compared for eight flavonoids
and two alkaloids using ESI, atmospheric pressure chemical ionization
(APCI), and heated electrospray ionization (HESI) sources. Relative
to reserpine, the flavonoids exhibited narrower linear dynamic ranges
with ESI-MS, primarily due to saturation in response at relatively
low concentrations. Saturation was overcome by switching from ESI
to APCI, and our experiments utilizing a combination HESI/APCI source
suggest that this is due in part to the ability of APCI to protonate
neutral quercetin molecules in the gas phase. Thermodynamic equilibrium
calculations indicate that quercetin should be fully protonated in
solution, and thus, it appears that some factor inherent in the ESI
process favors the formation of neutral quercetin at high concentration.
The flavonoid saturation concentration was increased with HESI as
compared to ESI, suggesting that inefficient transfer of ions to the
gas phase can also contribute to saturation in ESI-MS response. In
support of this conclusion, increasing auxiliary gas pressure or switching
to a more volatile spray solvent also increased the ESI dynamic range.
Among the sources investigated herein, the HESI source achieved the
best analytical performance (widest linear dynamic range, lowest LOD),
but the APCI source was less subject to saturation in response at
high concentration
High-Resolution MS, MS/MS, and UV Database of Fungal Secondary Metabolites as a Dereplication Protocol for Bioactive Natural Products
A major problem in the discovery
of new biologically active compounds
from natural products is the reisolation of known compounds. Such
reisolations waste time and resources, distracting chemists from more
promising leads. To address this problem, dereplication strategies
are needed that enable crude extracts to be screened for the presence
of known compounds before isolation efforts are initiated. In a project
to identify anticancer drug leads from filamentous fungi, a significant
dereplication challenge arises, as the taxonomy of the source materials
is rarely known, and, thus, the literature cannot be probed to identify
likely known compounds. An ultraperformance liquid chromatography–photodiode
array–high-resolution tandem mass spectrometric (UPLC-PDA-HRMS-MS/MS)
method was developed for dereplication of fungal secondary metabolites
in crude culture extracts. A database was constructed by recording
HRMS and MS/MS spectra of fungal metabolites, utilizing both positive-
and negative-ionization modes. Additional details, such as UV-absorption
maxima and retention times, were also recorded. Small-scale cultures
that showed cytotoxic activities were dereplicated before engaging
in the scale-up or purification processes. Using these methods, approximately
50% of the cytotoxic extracts could be eliminated from further study
after the confident identification of known compounds. The specific
attributes of this dereplication methodology include a focus on bioactive
secondary metabolites from fungi, the use of a 10 min chromatographic
method, and the inclusion of both HRMS and MS/MS data
CB2-Selective Cannabinoid Receptor Ligands: Synthesis, Pharmacological Evaluation, and Molecular Modeling Investigation of 1,8-Naphthyridin-2(1<i>H</i>)‑one-3-carboxamides
We
have recently identified 1,8-naphthyridin-2Â(1<i>H</i>)-one-3-carboxamide
as a new scaffold very suitable for the development
of new CB2 receptor potent and selective ligands. In this paper we
describe a number of additional derivatives in which the same central
scaffold has been variously functionalized in position 1 or 6. All
new compounds showed high selectivity and affinity in the nanomolar
range for the CB2 receptor. Furthermore, we found that their functional
activity is controlled by the presence of the substituents at position
C-6 of the naphthyridine scaffold. In fact, the introduction of substituents
in this position determined a functionality switch from agonist to
antagonists/inverse agonists. Finally, docking studies showed that
the difference between the pharmacology of these ligands may be in
the ability/inability to block the Toggle Switch W6.48(258) (χ1 <i>g+</i> → <i>trans</i>) transition