1800" to 2000'C. The sarnples stayed at that temperature for 10 to 20 m n before belng quenched by the cuttng off of power to the furnace. The quench rate was measured to be -500'C per second The samples were subsequently decompressed at a rate of 2 to 3 GPaihour. 17. NMR spectra descrlbed here were collected with a Varan Unity spectrometer operating at 9 L T was a MAS probe from Doty Scentfic (Coumba, SC), wlth 3.5-mm rotors commonly splnning at 9.3 kHz (unless otherwise specifed). To make 27AI analyss as straightforward as possible, a small tip angle ( i n I 6 ) was used in all cases. ' "a and "Al NMR was done w t h the use of delay tmes on the order of 1 s, wlth a spectral band width of 2 MHz. For2"S1 NMR. a smaller spectral band width was used because of the mited chemical shft range in Si; however much longer delay tlmes were used (70 s) because o i the possibility of havng long relaxaton tlmesfor Si speces even w t h a small paramagnetic dopant (Gd20,) [A. Abragam. Principles of Nuclear Magnetism (Oxford Unv. Press, New York, 1961)). We subtracted a 27Al background from the probe by colectng data on an empty rotor under condtions identical to those under whlch the glass samples were run. There was no probe background ~n the 23Na and 23S1 spectra; however, the Si3N, rotors gave a characteristc resonance at -L8.8 ppm relative to tetramethyl silane at 0 ppm with spinnlng sdebands in the sllcon NMR Thls was used as an internal chemical shift cabratlon for '%i NMR. To reference the chemcal sh~ft of ' % l a and "AI, a liquid sample of 1 M NaC (0 ppm) and 1 M ACI, (0 ppm) was run before each spectrum, respectvely. 18. We prepared the ?9S~enriched Ab5,NTS5, by fusing sto~chometr~c amounts of 92%-abeed 29Si0, glass (Cambridge Isotope Laboratory. Andover, MA) with sodium carbonate (Na,CO,), alumnum oxlde (A120s). and 0.1 weght percent gadolnium oxide (Gd20,) at 1200'C for 2 hours. Glass was formed upon removal of the Pt crucble containing the mixed iqud components from the furnace. We did not chemically analyze the sample because of the expense of labeled material and the proven nature of the synthesis process. Gd20s was added to shorten the spin-lattlce relaation time of SI. This sample. along wlth unlabeled glass made under the same conditions, was then sealed In Pt capsules for use in the hlgh-pressure multl-anvl quenchng descrlbed in (76).

Dean L. Olson (first row, right) completed his Ph.D. degree in Analytical Chemistry from the University of Illinois in 1994. He then joined the academic research group of Professor Sweedler performing the first high-resolution and sensitivity studies with nanoliter-volume NMR microcoils. He also conducted the first experiments using high-resolution NMR as a detector for capillary electrophoresis. He is now employed at MRM Corp. (Savoy, IL) conducting research toward the commercial development and application of capillarybased NMR probes. Andrew G. Webb (second row, right) received his Ph.D. degree in Medicinal Chemistry from the University of Cambridge in 1990 under Professor Laurie Hall. He was a postdoctoral researcher in the Department of Radiology at the University of Florida before joining the faculty in the Department of Electrical and Computer Engineering at the University of Illinois at Urbana−Champaign.He is currently an Associate Professor, with a full appointment in The Beckman Institute for Advanced Science and Technology. His research areas include the design of microcoils for NMR of mass-limited samples, the use of MRI temperature mapping for hyperthermia, and human brain mapping using functional MRI. Jonathan V. Sweedler (second row, left) received his Ph.D. degree in Analytical Chemistry from the University of Arizona in 1989 under Professor M. Bonner Denton and then spent 3 years at Stanford with Professors Richard Zare and Richard Scheller developing new methods to study neurotransmitters in individual neurons. He is currently a Professor of Chemistry, Neuroscience, and of the Beckman Institute for Advanced Science and Technology at the University of Illinois. His current research interests are twofold: first, he is developing information-rich methods with improved mass sensitivity for nanoliter-volume samples, including microcoil NMR, mass spectrometric imaging, and capillary-scale separations. In addition, he applies these techniques to understanding the role of neurotransmitter and neuropeptide co-transmission and the regulation of behavior in well-defined neuronal networks of opisthobranch molluscs.

An improved nanoliter-volume NMR probe design places the microcoil and capillary at the magic angle (57.7 degrees) with respect to the external magnetic field. Using an NMR probe which requires a total sample volume of just 200 nL, high-resolution 300-MHz 1H-NMR spectra (line width, 0.6 Hz) are presented of 10 mM alpha-bag cell peptide for an observe quantity of 45 ng (50 pmol in 5 nL). For the volume of sample inside the microcoil (the observe volume, Vobs), the 3 sigma limit of detection (LOD) is 9 ng (10 pmol, 2mM) for data obtained in 15 h. To reduce the data acquisition time, a probe with a greater Vobs is developed. As an example of a rapid, mass-limited analysis, a concentration corresponding to 400 ng of menthol dissolved in Vobs = 31 nL (82.6 mM) yields a spectrum in 9 min (LOD = 6.9 ng, 44 pmol, 1.4 mM). To illustrate improvements in concentration sensitivity, a spectrum is acquired in 45 min for 400 ng of menthol dissolved in a total sample volume of 200 nL (12.8 mM). Compared to a commercial nanoprobe for the same mass of menthol, these two examples reduce data acquisition time by at least 95%. Both model compounds demonstrate substantially improved concentration LODs compared to those obtained in previous high-resolution, microcoil NMR work. These advances illustrate the utility of enhanced sensitivity provided by NMR microcoils applied to nanoliter volumes of mass-limited samples.

The first Aplysia californica insulin gene is characterized and its proteolytic processing from prohormone to final peptides elucidated using a combination of biochemical and mass spectrometric methods. Aplysia insulin (AI) is one of the largest insulins found, with a molecular weight of 9146 Da, and an extended A chain compared with other invertebrate and vertebrate insulins. The AI prohormone produces a series of C peptides and also a unique N-terminally acetylated D peptide. AI-producing cells are restricted to the central region of the cerebral ganglia mostly within the F and C clusters, and AI is transported to neurohemal release sites located on the upper labial and anterior tentacular nerves. The expression of AI mRNA decreases when the animal is deprived of food, and injections of AI reduce hemolymph glucose levels, suggesting that the function of insulin-regulating metabolism has been conserved.

We use a multidisciplinary approach to identify, map, and characterize the bioactivity of modulatory neuropeptides in the circuitry that generates feeding behavior in Aplysia. Matrixassisted laser desorption/ionization time-of-flight mass spectrometry of the cerebral-buccal connective (CBC), a nerve containing axons of many interneurons that control feeding behavior of Aplysia, was used to identify neuropeptides that may participate in generation and shaping of feeding motor programs. Using this functionally oriented search, we identified a novel family of peptides that we call the feeding circuitactivating peptides (FCAPs). Two peptides with masses identical to those observed in the CBCs (molecular weight 1387 and 1433) were purified from buccal ganglia and partially sequenced using mass spectrometry. The amino acid sequence was then used to clone the FCAP precursor, which encodes multiple copies of eight different FCAPs. The two FCAPs present in highest copy number correspond to those observed in the CBC. The distribution of FCAP expression was mapped using Northern analysis, whole-mount in situ hybridization, and immunocytochemistry. Consistent with our initial findings, FCAP-immunopositive axons were observed in the CBC. Furthermore, we found that FCAP was present in some cerebralbuccal and buccal-cerebral interneurons. As their name suggests, FCAPs are capable of initiating rhythmic feeding motor programs and are the first neuropeptides with such activity in this circuit. The actions of FCAPs suggest that these peptides may contribute to the induction and maintenance of foodinduced arousal. FCAPs were also localized to several other neuronal systems, suggesting that FCAPs may play a role in the regulation of multiple behaviors.