Luminescent hyperbolic metasurfaces.

When engineered on scales much smaller than the operating wavelength, metal-semiconductor nanostructures exhibit properties unobtainable in nature. Namely, a uniaxial optical metamaterial described by a hyperbolic dispersion relation can simultaneously behave as a reflective metal and an absorptive or emissive semiconductor for electromagnetic waves with orthogonal linear polarization states. Using an unconventional multilayer architecture, we demonstrate luminescent hyperbolic metasurfaces, wherein distributed semiconducting quantum wells display extreme absorption and emission polarization anisotropy. Through normally incident micro-photoluminescence measurements, we observe absorption anisotropies greater than a factor of 10 and degree-of-linear polarization of emission >0.9. We observe the modification of emission spectra and, by incorporating wavelength-scale gratings, show a controlled reduction of polarization anisotropy. We verify hyperbolic dispersion with numerical simulations that model the metasurface as a composite nanoscale structure and according to the effective medium approximation. Finally, we experimentally demonstrate >350% emission intensity enhancement relative to the bare semiconducting quantum wells.

Characterization of protein kinase A and protein kinase C phosphorylation of the N-methyl-D-aspartate receptor NR1 subunit using phosphorylation site-specific antibodies.

Modulation of N-methyl-D-aspartate receptors in the brain by protein phosphorylation may play a central role in the regulation of synaptic plasticity. To examine the phosphorylation of the NR1 subunit of N-methyl-D-aspartate receptors in situ, we have generated several polyclonal antibodies that recognize the NR1 subunit only when specific serine residues are phosphorylated. Using these antibodies, we demonstrate that protein kinase C (PKC) phosphorylates serine residues 890 and 896 and cAMP-dependent protein kinase (PKA) phosphorylates serine residue 897 of the NR1 subunit. Activation of PKC and PKA together lead to the simultaneous phosphorylation of neighboring serine residues 896 and 897. Phosphorylation of serine 890 by PKC results in the dispersion of surface-associated clusters of the NR1 subunit expressed in fibroblasts, while phosphorylation of serine 896 and 897 has no effect on the subcellular distribution of NR1. The PKC-induced redistribution of the NR1 subunit in cells occurs within minutes of serine 890 phosphorylation and reverses upon dephosphorylation. These results demonstrate that PKA and PKC phosphorylate distinct residues within a small region of the NR1 subunit and differentially affect the subcellular distribution of the NR1 subunit.

Primary structure of two neuropeptide hormones with adipokinetic and hypotrehalosemic activity isolated from the corpora cardiaca of horse flies (Diptera).

The primary structures of two neuropeptides, Tabanus atratus adipokinetic hormone (Taa-AKH) and Tabanus atratus hypotrehalosemic hormone (Taa-HoTH), from the corpora cardiaca of horse flies (Diptera: Tabanidae) have been determined. Amino acid sequences of Taa-AKH (less than Glu-Leu-Thr-Phe-Thr-Pro-Gly-Trp-NH2) and Taa-HoTH (less than Glu-Leu-Thr-Phe-Thr-Pro-Gly-Trp-Gly-Tyr-NH2) (where less than Glu = pyroglutamic acid) were determined by automated gas-phase Edman degradation of the peptides deblocked by pyroglutamate aminopeptidase and by fast atom bombardment mass spectrometry. The hormones were synthesized, and the natural and synthetic peptides exhibited identical chromatographic, spectroscopic, and biological properties. When assayed in adult face fly males, Taa-AKH and Taa-HoTH demonstrated hyperlipemic activity, in addition, Taa-HoTH also demonstrated a significant hypotrehalosemic activity.

Identification of a neuropeptide hormone that regulates sex pheromone production in female moths.

A pheromone biosynthesis activating neuropeptide (PBAN) hormone that controls sex pheromone production in female moths was identified from the brain-subesophageal ganglion complexes of the adult corn earworm, Heliothis zea. PBAN has 33 amino acid residues and a molecular weight of 3900. Its amino acid sequence has no significant homology with any of the fully characterized peptide hormones. The synthetic peptide, at a dose of between 2 and 4 picomoles, induced production of a normal quantity of sex pheromone in ligated H. zea females. The peptide also induced pheromone production in six other species of moths, thus indicating that this or similar peptides may be responsible for the regulation of pheromone production in moths.

Isolation and primary structure of a neuropeptide hormone from Heliothis zea with hypertrehalosemic and adipokinetic activities.

A neuropeptide was isolated from the corpora cardiaca of the corn earworm moth Heliothis zea, and purified by sequential gradient elution in three reversed phase-high performance liquid chromatographic steps. The primary structure, pGlu-Leu-Thr-Phe-Ser-Ser-Gly-Trp-Gly-Asn-NH2 was determined by automated gas-phase Edman degradation of the peptide deblocked with pyroglutamate aminopeptidase, and confirmed by fast atom bombardment mass spectrometry. The hormone was synthesized and the natural and synthetic peptides had identical chromatographic and spectroscopic properties. Both natural and synthetic hormones caused the elevation of trehalose and lipid levels in the hemolymph of adult H. zea males.

Isolation and primary structure of a peptide from the corpora cardiaca of Heliothis zea with adipokinetic activity.

An adipokinetic hormone was isolated from the corpora cardiaca of the corn ear worm moth, Heliothis zea, and purified by reversed phase high performance liquid chromatography. The primary structure, pGlu-Leu-Thr-Phe-Thr-Ser-Ser-Trp-Gly-NH2, was determined by automated gas-phase Edman degradation of the peptide deblocked with pyroglutamic aminopeptidase, and by fast atom bombardment mass spectrometry. The hormone was synthesized and the natural and synthetic material had identical chromatographic, spectroscopic, and biological properties. The peptide was found to have lipid mobilizing activity in H. zea adults.

The covalent protein structure of insecticyanin, a blue biliprotein from the hemolymph of the tobacco hornworm, Manduca sexta L.

The amino acid sequence has been determined for the insecticyanin from the hemolymph of the fifth instar larvae of the tobacco hornworm, Manduca sexta. The apoprotein is a single polypeptide chain of 189 amino acids, molecular weight 21,378, containing two disulfide bridges, 9-119 and 42-176. The sequence analysis was performed by automated Edman degradation of reduced and carboxymethylated insecticyanin and fragments generated therefrom by cyanogen bromide, trypsin, chymotrypsin, and Staphylococcus aureus proteinase. Most of the peptides were purified by reverse-phase high-performance liquid chromatography. A purification procedure for the isolation of insecticyanin in high yields and a simple method of determining disulfide linkages are also reported.