Lack of interactions between fire ant control products and white grubs (Coleoptera: Scarabaeidae) in turfgrass

Insecticides are widely used to manage turfgrass pest such as white grubs (Coleoptera: Scarabaeidae). Red imported fire ants, Solenopsis invicta (Buren) are important predators and pests in managed turfgrass. We tested the susceptibility of white grub life stages (adults, egg, and larvae) to predation by S. invicta and determined if insecticides applied for control of S. invicta would result in locally greater white grub populations. Field trials over 2 yr evaluated bifenthrin, fipronil, and hydramethylnon applied to large and small scale turfgrass plots for impacts on fire ant foraging and white grub populations. Coincident with these trials, adults, larvae, and eggs of common scarab species were evaluated for susceptibility to predation by S. invicta under field conditions. Field trials with insecticides failed to show a significant increase in white grub populations resulting from treatment of turfgrass for fire ants. This, in part, may be because of a lack of predation of S. invicta on adult and larval scarabs. Egg predation was greatest at 70% but < 20% of adults and larvae were attacked in a 24 h test. Contrary to other studies, results presented here suggest that fire ants and fire ant control products applied to turfgrass have a minimal impact on white grub populations.     

P2X (purinergic) receptor redistribution in rabbit aorta following injury to endothelial cells and cholesterol feeding

The redistribution of purinergic P2X receptor subunits (P2X₁ to P2X₇) within the rabbit aorta wall three weeks after endothelial balloon injury/cholesterol feeding was examined. P2X₁ receptor cluster density was elevated in the media following balloon injury/cholesterol feeding by about 30% and these clusters appeared on smooth muscle cells throughout the greatly expanded neointima but they did not change significantly on the endothelial cells following balloon injury. P2X₄ clusters were found in high density throughout the media and in very high density in the enlarged neointima following balloon injury, particularly on the endothelial cells where the density increased about 10-fold after balloon injury. P2X₅ clusters were found in high density in the media of normal aorta but with little change following balloon injury. P2X₃, P2X₆ and P2X₇ cluster density was low in normal aorta and remained unchanged following balloon injury. All receptor subunits were found on endothelial cells. It is suggested that the release of ATP from damaged endothelial cells and from smooth muscle cells sufficient to activate P2X₄ receptors may contribute to neointimal proliferation.     

Changes in the distribution of different subtypes of P2X receptor clusters on smooth muscle cells in relation to nerve varicosities in the pregnant rat urinary bladder

Clusters of purinergic receptor subunits, about 1 μm diameter, are found on the smooth muscle cell membrane beneath junctional varicosities in the detrusor muscle of the rat urinary bladder. We have examined the extent of redistribution of the six different subunit clusters, P2X₁ to P2X₆, with respect to junctional varicosities during pregnancy, as it is known that the detrusor muscle undergoes changes in purinergic innervation during this period. Before pregnancy, clusters at junctional varicosities are principally composed of the subtypes P2X₁, P2X₂, P2X₃ and P2X₅. However this subtype distribution changes dramatically during pregnancy, such that by day 14 of pregnancy, the extent of P2X₁, P2X₂, P2X₃ and P2X₅ junctional clusters has decreased by more than 80% whereas the extent of P2X₄ and P2X₆ junctional clusters has increased by more than 80%. These changes were confirmed with Western blots for different subtypes. It is suggested that the changes in the purinergic innervation of the detrusor muscle during pregnancy reflect changes in the P2X subtypes found on the smooth muscle membrane beneath junctional varicosities.     

Eusociality Shapes Convergent Patterns of Molecular Evolution across Mitochondrial Genomes of Snapping Shrimps

Eusociality is a highly conspicuous and ecologically impactful behavioral syndrome that has evolved independently across multiple animal lineages. So far, comparative genomic analyses of advanced sociality have been mostly limited to insects. Here, we study the only clade of animals known to exhibit eusociality in the marine realm—lineages of socially diverse snapping shrimps in the genus Synalpheus. To investigate the molecular impact of sociality, we assembled the mitochondrial genomes of eight Synalpheus species that represent three independent origins of eusociality and analyzed patterns of molecular evolution in protein-coding genes. Synonymous substitution rates are lower and potential signals of relaxed purifying selection are higher in eusocial relative to noneusocial taxa. Our results suggest that mitochondrial genome evolution was shaped by eusociality-linked traits—extended generation times and reduced effective population sizes that are hallmarks of advanced animal societies. This is the first direct evidence of eusociality impacting genome evolution in marine taxa. Our results also strongly support the idea that eusociality can shape genome evolution through profound changes in life history and demography.     

Differential regulation by dexamethasone of glucocorticoid receptor messenger RNA concentrations in neuronal cultures derived from fetal rat hypothalamus and cerebral cortex

1. Differential regulation, by dexamethasone, of glucocorticoid receptor gene expression was studied in three different neuronal cultures derived from hypothalamus amygdala, and cerebral cortex. 2. Cellular glucocorticoid receptor (GR) mRNA concentration was measured by hybridization using a 32P-labeled RNA probe complementary to a 2.2-kb fragment of the glucocorticoid receptor mRNA. Changes in the amount of GR mRNA were evaluated in relation to the content of beta-actin mRNA. 3. In cells derived from either hypothalamus or cerebral cortex, we observed a complex pattern of GR mRNA concentrations which were characterized by cyclic variations of GR mRNA content during continuous treatment with dexamethasone for up to 72 hr. 4. In contrast to cells derived from the hypothalamus where a persistent 30-40% reduction in GR mRNA levels was seen for up to a least 72 hr, we observed, in cells derived from the cerebral cortex, a sustained increased (1.4-fold) of the GR mRNA at this same time interval.     

NMR study of a 34-residue N-terminal fragment of the parathyroid-hormone-related protein secreted during humoral hypercalcemia of malignancy

The proton resonances of the biologically active peptide parathyroid-hormone-related protein (residues 1-34) were assigned using one-dimensional spin-decoupling techniques, two-dimensional correlated spectroscopy and by comparing the spectra of the peptides 1-20, 1-25, 1-29, 7-34 and 15-34. The conformation of 1-34 was determined using one- and two-dimensional nuclear Overhauser enhancement spectroscopy in the rotating frame. Amide proton temperature coefficients, vicinal coupling constants and circular dichroic spectra helped reveal a surprisingly compact structure with residues 3-9 forming alpha-helix, type-I beta-turns between residues 10-13 and 16-19 and several interactions between the N-terminal residues and the C-terminal residues. Of these latter, the strongest appeared to be between Asp-10 and Phe-22. One peptide surface in the deduced model presents multiple positive charges, while the opposite surface has a hydrophobic character possibly functioning to exclude water from the binding interface and enhancing the binding constant.     

S-(4-bromo-2,3-dioxobutyl)-CoA labels two distinct sites on citrate synthase

The chemical nature of the inactivation of citrate synthase by S-(4-bromo-2,3-dioxobutyl)-CoA, an active site-directed irreversible inhibitor, has been investigated. Active site-directed inactivation leads to derivatization of either Lys22 by epsilon-amino Schiff base formation or Glu363 by apparent alkylation of the gamma-carboxyl group, respectively. Lys22 is labeled in the tight (catalytic) form of the enzyme while Glu363 is labeled in the open (product release) form. Glu363 and Lys22 are both located at or near the entrance to an active site in the crystal structure of citrate synthase (Remington, S., Wiegand, G., and Huber, R. (1982) J. Mol. Biol. 158, 111-152). Glu363 is in the sequence of the protomer forming the active site while Lys22 is in the sequence of the other polypeptide in the homodimer. Labeling in this region appears to inactivate the enzyme by preventing access of substrates to the active site. A distinct and separate labeling process involves derivatization of Asn192 in the tight (catalytic) form and Ser198 and/or Ser199 in the open (product release) form at a locus far removed from the active site. Labeling at the second site may simply identify chemically reactive residues, or it may identify the binding site for long chain acyl-CoA, which has been identified as a possible allosteric negative effector of citrate synthase (Caggiano, A. V., and Powell, G. L. (1979) J. Biol. Chem. 254, 2800-2806). This second labeling process apparently inactivates the enzyme by interfering with catalytically essential conformational changes.