Neuropeptides play critical roles in synaptic signaling in all nervous systems. Unlike classical neurotransmitters, peptidergic neurotransmitters are encoded as preproproteins that are posttranslationally processed to yield bioactive neuropeptides. To identify novel peptidergic neurotransmitters, the Caenorhabditis elegans genome was searched for predicted proteins with the structural hallmarks of neuropeptide preproproteins. Thirty-two C. elegans neuropeptide-like protein (nlp) genes were identified. The nlp genes define at least 11 families of putative neuropeptides with unique motifs; similar expressed sequence tags were identified in other invertebrate species for all 11 families. Six of these families are defined by putative bioactive motifs (FAFA, GGxYamide, MRxamide, LQFamide, LxDxamide, and GGARAF); the remaining five families are related to allatostatin, myomodulin, buccalin͞drosul-fakinin, orcokinin, and APGWamide neuropeptides (MGL͞Famide, FRPamide, MSFamide, GFxGF, and YGGWamide families, respectively). Most C. elegans nlp gene expression is in neurons. The C. elegans nlp genes and similar genes encoding putative neuropeptides in other species are likely to play diverse roles in nervous system function. C hemical signaling via neurotransmitters is critical for synaptic transmission of information between neurons. Neuropeptides are the most varied and numerous type of neurotransmitters. Invertebrate neuropeptides are thought primarily to modulate synaptic function of classical small-molecule neurotransmitters by means of seven transmembrane domain receptors. However, the recent identification of a FMRFamide-gated sodium channel from Helix lucorum suggests that they may also act as fast transmitters (1). In mammals, neuropeptides and their receptors are implicated in behaviors including feeding and sleep (2-5). Despite their clear roles in synaptic signaling and behavior, neuropeptide functions are still not understood.Biochemical isolation of neuropeptides has been relatively successful in several invertebrate systems, including Lymnaea stagnalis, Drosophila melanogaster, and Aplysia californica (6-8), and has led to the identification of several invertebrate neuropeptide families. In the nematode Caenorhabditis elegans, 23 FMRFamide-related proteins (FaRP) neuropeptide genes, designated flp-1 to flp-23 (FMRFamide-like proteins), have been identified (9). Only flp-1 has been characterized at the functional level. Animals lacking flp-1 have abnormal behavior, including uncoordinated movement and hyperactivity (10). The only other C. elegans non-flp neuropeptide genes that have been identified are the 37 insulin-like genes (11, 12).Dense-core synaptic vesicles are prevalent in presynaptic terminals of C. elegans neurons that are neither FaRP immunoreactive nor catecholaminergic (13), suggesting that nonFaRP neuropeptides are present. Additionally, about 130 genes encoding putative neuropeptide receptors were identified in the C. elegans genome (14). This large number of receptors is much higher than the...

Anterior corneal wavefront aberrations varied greatly among subjects and increased slightly with aging. All corneas had positive 4th-order SAs, and the values did not change with aging. A moderate to high degree of mirror symmetry existed between right and left eyes.

Neuropeptides have diverse roles in the function and development of the nervous system. With the completion of the sequencing of the C. elegans genome, rapid identification of nematode neuropeptide genes is possible. To date, 41 C. elegans neuropeptide genes have been identified. Of these genes, 20 genes, named flp (FMRFamide-like peptide) genes, encode FMRFamide-related proteins (FaRPs). Deletion of one of the flp genes, flp-1, results in several behavioral defects, suggesting that at least one flp gene is not functionally redundant with other flp genes. Twenty-one genes, named neuropeptide-like protein (nlp) genes, encode peptides distinct from the FaRP family. The predicted nlp-1 and nlp-2 neuropeptides have modest similarity to buccalin and myomodulin, respectively. Cellular expression patterns and genetic analysis of flp and nlp genes suggest that neuropeptides in nematodes also have widespread and varied roles in nervous system function.

This is the first study of the ICON learning system in undergraduate medical education, a platform designed to facilitate collaboration outside of the classroom. Data on user perceptions and system utilization suggest that both faculty and students chose to adopt this online learning system as a means for collaboration. The study also outlines future avenues for research in assessing novel online technologies.