The investigation of membrane binding by amphibian peptide agonists of CCK2R using (31)P and (2)H solid-state NMR

It has been proposed that some neuropeptides may be anchored to the cell membranes prior to attaching to the adjacent active sites of transmembrane receptors. The three amphibian skin neuropeptides signiferin 1 [RLCIPYIIPC(OH)] (smooth muscle active and immunomodulator), riparin 1.1 [[RLCIPVIFPC(OH)] (immunomodulator) and rothein 1 [SVSNIPESIGF(OH)] (immunomodulator) act via CCK2 transmembrane receptors. A combination of (31)P and (2)H solid state NMR studies of each of these three peptides in eukaryotic phospholipid models at 25°C shows that rothein 1 does not interact with the membrane at all. In contrast, both of the cyclic disulfides signiferin 1 and riparin 1.1 interact with phospholipid head groups and partially penetrate into the upper leaflet of the model bilayer, but to different extents. These interactions are not sufficiently effective to cause disruption of the lipid bilayer since the peptides are not antimicrobial, anticancer, antifungal nor active against enveloped viruses.

Histidine-containing host-defence skin peptides of anurans bind Cu2+. An electrospray ionisation mass spectrometry and computational modelling study

Anuran peptides which contain His, including caerin 1.8 (GLFKVLGSVAKHLLPHVVPVIAEKL-NH(2)), caerin 1.2 (GLLGVLGSVAKHVLPHVVPVIAEHL-NH(2)), Ala(15) maculatin 1.1 (GLFGVLAKVAAHVVAIEHF-NH(2)), fallaxidin 4.1 (GLLSFLPKVIGHLIHPPS-OH), riparin 5.1 (IVSYPDDAGEHAHKMG-NH(2)) and signiferin 2.1 (IIGHLIKTALGMLGL-NH(2)), all form MMet(2+) and (M + Met(2+)-2H(+))(2+) cluster ions (where Met is Cu, Mg and Zn) following electrospray ionisation (ESI) in a Waters QTOF 2 mass spectrometer. Peaks due to Cu(II) complexes are always the most abundant relative to other metal complexes. Information concerning metal(2+) connectivity in a complex has been obtained (at least in part) using b and y fragmentation data from ESI collision-induced dissociation tandem mass spectrometry (CID MS/MS). Theoretical calculations, using AMBER version 10, show that MCu(2+) complexes with the membrane active caerin 1.8, Ala(15) maculatin 1.1 and fallaxidin 4.1 are four-coordinate and approximating square planar, with ligands including His and Lys, together with the carbonyl oxygens of particular backbone amide groups. When binding can occur through two His, or one His and one Lys, the His/Lys ligand structure is the more stable for the studied systems. The three-dimensional (3D) structures of the complexes are always different from the previously determined structures of the uncomplexed model peptides (using 2D nuclear magnetic resonance (NMR) spectroscopy in membrane-mimicking solvents like trifluoroethanol/water).

Skin peptide and cDNA profiling of Australian anurans: genus and species identification and evolutionary trends

Host defense peptides of 35 species of Australian frogs from the hylids Cyclorana and Litoria, and the myobatrachids Crinia, Limnodynastes and Uperoleia have been identified. The biological activities of the majority of these peptides have been determined and include hormones, neuropeptides, opioids, immunomodulators, membrane active peptides [including antimicrobial, anticancer, antiviral (enveloped viruses like HIV and Herpes) and antifungal peptides], neuronal nitric oxide synthase inhibitors, pheromones and individual peptides with other specific activities. The host defense peptide skin profile can be diagnostic at both the species and higher taxonomic levels; for example, species of Crinia, Litoria and Uperoleia each produce quite different types of peptides. Species of Cyclorana and Limnodynastes are more difficult to characterize by skin peptides alone: species of both genera produce similar peptides with no apparent activity. The skin peptide profiles of frogs from the genera Crinia, Litoria and Uperoleia may be used together with morphological and cognate methods, to differentiate between sub-species and even different population clusters of the same species. Nucleotide sequencing of cDNAs of precursors (pre-pro peptides) of bioactive peptides from the skin glands of various species of the genus Litoria show that the majority of these peptides originated from a single ancestor gene before the break away of Australia from Gondwana. The exceptions are the caerulein neuropeptides {e.g. caerulein [pEQDY(SO(3)H)TGWMDF(NH(2))]} which have a different origin to that of other Litoria peptides. Disulfide containing peptides from skin glands of species of Crinia show a different evolutionary route to peptides from species of Litoria.

Diagnostic fragmentations of adducts formed between carbanions and carbon disulfide in the gas phase. A joint experimental and theoretical study

Selected carbanions react with carbon disulfide in a modified LCQ ion trap mass spectrometer to form adducts, which when collisionally activated, decompose by processes which in some cases identify the structures of the original carbanions. For example (i) C(6)H(5)(-) + CS(2)--> C(6)H(5)CS(2)(-)--> C(6)H(5)S(-) + CS, occurs through a 3-membered ring ipso transition state, and (ii) the reaction between C(6)H(5)CH(2)(-) and CS(2) gives an adduct which loses H(2)S, whereas the adduct(s) formed between o-CH(3)C(6)H(5)(-) and CS(2) loses H(2)S and CS. Finally, it is shown that decarboxylation of C(6)H(5)CH(2)CH(2)CO(2)(-) produces the beta-phenylethyl anion (PhCH(2)CH(2)(-)), and that this thermalized anion reacts with CS(2) to form C(6)H(5)CH(2)CH(2)CS(2)(-) which when energized fragments specifically by the process C(6)H(5)CH(2)CH(2)CS(2)(-)--> C(6)H(5)CH(2)(-)CHC(S)SH --> [(C(6)H(5)CH(2)CH[double bond, length as m-dash]C[double bond, length as m-dash]S) (-)SH] --> C(6)H(5)CH(2)CCS(-) + H(2)S. Experimental findings of processes (ii) and (iii) were aided by deuterium labelling studies, and all reaction profiles were studied by theoretical calculations at the UCCSD(T)/6-31+G(d,p)//B3LYP/6-31+G(d,p) level of theory unless indicated to the contrary.

National culture and flight deck automation: results of a multination survey

Attitudes regarding flight deck automation were surveyed in a sample of 5,879 airline pilots from 12 nations. The average difference in endorsement levels across 11 items for pilots flying automated aircraft in 12 nations was 53%, reflecting significant national differences in attitudes on all items, with the largest differences observed for preference and enthusiasm for automation. The range of agreement across nations was on average four times larger than the range of agreement across different airlines within the same nation, and roughly six times larger than the range across pilots of standard and pilots of automated aircraft. Patterns of response are described in terms of dimensions of national culture. Implications of the results for development of safety cultures and culturally sensitive training are discussed.

A remote method for simultaneous measurement of corneal thickness and curvature at a single point

Advances in refractive surgery have been limited by the measurement technology for determining corneal thickness and curvature. A measurement technique is needed that can provide a detailed corneal thickness and curvature model without contacting the cornea or obstructing the view of the surgeon or surgical equipment. The authors present preliminary results of a method to remotely measure the thickness and curvature of the human cornea at a single point. The method combines ray tracing and interferometry to estimate thickness and curvature in two orthogonal planes in an area less than 100 microns in diameter. This technique has been successfully used to provide very accurate estimates of several thin-shelled test objects. Based upon these results, recommendations are given for further improvement of the technique and extension to a multipoint cornea-modeling system.

Mechanism of action of estrogen on intramembranous bone formation: regulation of osteoblast differentiation and activity

Dynamic bone histomorphometry, [3H]thymidine radioautography, and Northern analysis for bone matrix proteins and insulin-like growth factor-I (IGF-I) were performed in calvariae of ovariectomized (OVX) and estrogen-treated OVX rats. Treatment of OVX rats with diethylstilbestrol (DES) for 2 weeks reduced the periosteal mineral apposition rate, osteoblast number, and osteoblast size in calvarial periosteum. DES treatment also reduced the number of preosteoblasts in the S phase of the cell cycle, suggesting that the decrease in osteoblast number was due in part to inhibition of proliferation of osteoprogenitor cells. One week after ovariectomy, there were small increases in mRNA levels for pre pro-alpha 2 (I) subunit of type I collagen (collagen), osteocalcin, and osteonectin and a large increase in the mRNA level for IGF-I. DES treatment resulted in rapid decreases (3 h) in the mRNA levels for osteonectin, osteocalcin, and IGF-I. In contrast, mRNA levels for collagen were virtually unchanged after short term DES treatment. Uterus and liver served as positive and negative control tissues, respectively, for the effects of DES on IGF-I mRNA levels in OVX rats; mRNA levels were increased in uterus and decreased in liver after hormone treatment. We conclude from these studies that estrogen reduces periosteal bone formation by inhibiting both the differentiation and activity of osteoblasts. Furthermore, down-regulation of mRNA levels for IGF-I and bone matrix proteins precedes the changes in dynamic bone histomorphometry.