Twenty year contrast of non-native parrotfeather distribution and abundance in an unregulated river

Hydrobiologia - Efficient management of invasive species benefits from understanding patterns of persistence and change over time. In this study, we compare distribution and abundance of the...     

Gas chromatography column as an ambient‐temperature volatile trap

Open‐tube volatile traps have largely been shunned in favor of solid adsorbent containing traps for the collection of volatile pheromones and attractants. Solid adsorbents require large solvent rinses and glass capillaries can be difficult to maneuver for the collection of volatiles from small or hard‐to‐reach odor sources. A gas chromatograph (GC) column (DB‐1), an open‐tube glass capillary, and a SuperQ^®‐containing capillary were compared for their collection efficiencies from rubber septa and live calling insects. All three traps captured similar ratios of test compounds from septa at airflows >10 ml per min. Eluting analytes from a packed adsorbent, SuperQ, required at least 30× more solvent than was required to collect all the pheromone from the open‐tube glass capillaries, and the GC column enjoyed an additional three‐fold reduced solvent volume compared to the glass capillary. Thus, analytes could be eluted from the GC‐column trap and directly analyzed on GC without solvent evaporation. We placed glass wool ‘plugs’ in both GC columns and glass capillaries and found no volatiles in these plugs, indicating that breakthrough did not occur during 1‐h collections at 25 ml per min. We demonstrate here that at ambient laboratory temperatures, a DB‐1 GC column effectively collects Oriental fruit moth sex pheromone volatiles from a rubber septum and live pheromone‐releasing moths. Release ratios of pheromone from rubber septa are consistent with earlier reports from static air systems, whereas the release ratio of the (Z)‐8‐dodecenyl alcohol (Z8‐12:OH) from female Grapholita molesta Busck (Lepidoptera: Tortricidae) differed from published results and is likely due to different collection methods or moth‐strain origin.     

Dissecting the complete lipoprotein biogenesis pathway in Streptomyces scabies

Following translocation, bacterial lipoproteins are lipidated by lipoprotein diacylglycerol transferase (Lgt) and cleaved of their signal peptides by lipoprotein signal peptidase (Lsp). In Gram-negative bacteria and mycobacteria, lipoproteins are further lipidated by lipoprotein N-acyl transferase (Lnt), to give triacylated lipoproteins. Streptomyces are unusual amongst Gram-positive bacteria because they export large numbers of lipoproteins via the twin arginine protein transport (Tat) pathway. Furthermore, some Streptomyces species encode two Lgt homologues and all Streptomyces species encode two homologues of Lnt. Here we characterize lipoprotein biogenesis in the plant pathogen Streptomyces scabies and report that lgt and lsp mutants are defective in growth and development while only moderately affected in virulence. Lipoproteins are lost from the membrane in an S. scabies lgt mutant but restored by expression of Streptomyces coelicolor lgt1 or lgt2 confirming that both encode functional Lgt enzymes. Furthermore, lipoproteins are N-acylated in Streptomyces with efficient N-acylation dependent on Lnt1 and Lnt2. However, deletion of lnt1 and lnt2 has no effect on growth, development or virulence. We thus present a detailed study of lipoprotein biogenesis in Streptomyces, the first study of Lnt function in a monoderm bacterium and the first study of bacterial lipoproteins as virulence factors in a plant pathogen.     

Requirements for mammalian carboxylesterase inhibition by substituted ethane-1,2-diones

Carboxylesterases (CE) are ubiquitous enzymes found in both human and animal tissues and are responsible for the metabolism of xenobiotics. This includes numerous natural products, as well as a many clinically used drugs. Hence, the activity of these agents is likely dependent upon the levels and location of CE expression. We have recently identified benzil is a potent inhibitor of mammalian CEs, and in this study, we have assessed the ability of analogues of this compound to inhibit these enzymes. Three different classes of molecules were assayed: one containing different atoms vicinal to the carbonyl carbon atom and the benzene ring [PhXC(O)C(O)XPh, where X=CH?, CHBr, N, S, or O]; a second containing a panel of alkyl 1,2-diones demonstrating increasing alkyl chain length; and a third consisting of a series of 1-phenyl-2-alkyl-1,2-diones. In general, with the former series of molecules, heteroatoms resulted in either loss of inhibitory potency (when X=N), or conversion of the compounds into substrates for the enzymes (when X=S or O). However, the inclusion of a brominated methylene atom resulted in potent CE inhibition. Subsequent analysis with the alkyl diones [RC(O)C(O)R, where R ranged from CH? to C?H??] and 1-phenyl-2-alkyl-1,2-diones [PhC(O)C(O)R where R ranged from CH? to C?H??], demonstrated that the potency of enzyme inhibition directly correlated with the hydrophobicity (clogP) of the molecules. We conclude from these studies that that the inhibitory power of these 1,2-dione derivatives depends primarily upon the hydrophobicity of the R group, but also on the electrophilicity of the carbonyl group.     

Advancing cervical cancer prevention initiatives in resource-constrained settings: insights from the Cervical Cancer Prevention Program in Zambia

Groesbeck Parham and colleagues describe their Cervical Cancer Prevention Program in Zambia, which has provided services to over 58,000 women over the past five years, and share lessons learned from the program's implementation and integration with existing HIV/AIDS programs.     

Hypoxic alligator embryos: chronic hypoxia, catecholamine levels and autonomic responses of in ovo alligators

Hypoxia is a naturally occurring environmental challenge for embryonic reptiles, and this is the first study to investigate the impact of chronic hypoxia on the in ovo development of autonomic cardiovascular regulation and circulating catecholamine levels in a reptile. We measured heart rate (f(H)) and chorioallantoic arterial blood pressure (MAP) in normoxic ('N21') and hypoxic-incubated ('H10'; 10% O(2)) American alligator embryos (Alligator mississippiensis) at 70, 80 and 90% of development. Embryonic alligator responses to adrenergic blockade with propranolol and phentolamine were very similar to previously reported responses of embryonic chicken, and demonstrated that embryonic alligator has α and β-adrenergic tone over the final third of development. However, adrenergic tone originates entirely from circulating catecholamines and is not altered by chronic hypoxic incubation, as neither cholinergic blockade with atropine nor ganglionic blockade with hexamethonium altered baseline cardiovascular variables in N21 or H10 embryos. In addition, both atropine and hexamethonium injection did not alter the generally depressive effects of acute hypoxia - bradycardia and hypotension. However, H10 embryos showed significantly higher levels of noradrenaline and adrenaline at 70% of development, as well as higher noradrenaline at 80% of development, suggesting that circulating catecholamines reach maximal levels earlier in incubation for H10 embryos, compared to N21 embryos. Chronically elevated levels of catecholamines may alter the normal balance between α and β-adrenoreceptors in H10 alligator embryos, causing chronic bradycardia and hypotension of H10 embryos measured in normoxia.     

Natural variation in life history and aging phenotypes is associated with mitochondrial DNA deletion frequency in Caenorhabditis briggsae

Background  

Mutations that impair mitochondrial functioning are associated with a variety of metabolic and age-related disorders. A barrier to rigorous tests of the role of mitochondrial dysfunction in aging processes has been the lack of model systems with relevant, naturally occurring mitochondrial genetic variation. Toward the goal of developing such a model system, we studied natural variation in life history, metabolic, and aging phenotypes as it relates to levels of a naturally-occurring heteroplasmic mitochondrial ND5 deletion recently discovered to segregate among wild populations of the soil nematode, Caenorhabditis briggsae. The normal product of ND5 is a central component of the mitochondrial electron transport chain and integral to cellular energy metabolism.