Although vocal signals including human languages are composed of a finite number of acoustic elements, complex and diverse vocal patterns can be created from combinations of these elements, linked together by syntactic rules. To enable such syntactic vocal behaviors, neural systems must extract the sequence patterns from auditory information and establish syntactic rules to generate motor commands for vocal organs. However, the neural basis of syntactic processing of learned vocal signals remains largely unknown. Here we report that the basal ganglia projecting premotor neurons (HVC X neurons) in Bengalese finches represent syntactic rules that generate variable song sequences. When vocalizing an alternative transition segment between song elements called syllables, sparse burst spikes of HVC X neurons code the identity of a specific syllable type or a specific transition direction among the alternative trajectories. When vocalizing a variable repetition sequence of the same syllable, HVC X neurons not only signal the initiation and termination of the repetition sequence but also indicate the progress and state-of-completeness of the repetition. These different types of syntactic information are frequently integrated within the activity of single HVC X neurons, suggesting that syntactic attributes of the individual neurons are not programmed as a basic cellular subtype in advance but acquired in the course of vocal learning and maturation. Furthermore, some auditory-vocal mirroring type HVC X neurons display transition selectivity in the auditory phase, much as they do in the vocal phase, suggesting that these songbirds may extract syntactic rules from auditory experience and apply them to form their own vocal behaviors.

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Plant alkaloids, one of the largest groups of natural products, provide many pharmacologically active compounds. Several genes in the biosynthetic pathways for scopolamine, nicotine, and berberine have been cloned, making the metabolic engineering of these alkaloids possible. Expression of two branching-point enzymes was engineered: putrescine N-methyltransferase (PMT) in transgenic plants of Atropa belladonna and Nicotiana sylvestris and (S)-scoulerine 9-Omethyltransferase (SMT) in cultured cells of Coptis japonica and Eschscholzia californica. Overexpression of PMT increased the nicotine content in N. sylvestris, whereas suppression of endogenous PMT activity severely decreased the nicotine content and induced abnormal morphologies. Ectopic expression of SMT caused the accumulation of benzylisoquinoline alkaloids in E. californica. The prospects and limitations of engineering plant alkaloid metabolism are discussed.berberine ͉ nicotine ͉ polyamine ͉ sanguinarine ͉ scopolamine H igher plants constitute one of our most important natural resources. They provide not only foodstuffs, fibers, and woods, but many chemicals, such as oils, flavorings, dyes, and pharmaceuticals. Although plants are renewable resources, some species are becoming more difficult to obtain in sufficient amounts to meet increasing demands. Destruction of natural habitats and technical difficulties in cultivation also are driving the drastic reductions in plant availability. For example, it is claimed that the demand for paclitaxel, a potent anticancer compound, could endanger forests of Taxus brevifolia (Pacific yew) because of the low paclitaxel content (40-100 mg͞kg of bark) in and slow growth of the trees (1).For many natural chemicals it is possible to synthesize alternatives from petroleum, coal, or both. The economic limitations of chemical synthesis and the pollution that accompanies this type of chemical synthesis, however, have led to the development of cell culture and molecular engineering of plants for the production of important and commodity chemicals. Plant cell and organ culture offer promising alternatives for the production of chemicals because totipotency enables plant cells and organs to produce useful secondary metabolites in vitro (2). Cell culture is also advantageous in that useful metabolites are obtained under a controlled environment, independent of climatic changes and soil conditions. In addition, the products are free of microbe and insect contamination. Fermentation technology also can be used to produce desired metabolites and can be optimized to maintain high and stable yields of known quality by cellular and molecular breeding techniques to further improve productivity and quality. After extensive empirical trials, some metabolites are now being produced by large-scale cell culture (e.g., shikonin and berberine; ref. 2), but the numbers of compounds that are producible commercially by cell culture technology are still very few. The main limitations are low productivity and the necessity of the down-stream pr...

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Quantitative serial measurement of HOAs and forward light scatter showed that the temporal reduction in optical quality may be attributed mainly to increased HOAs after instillation of highly viscous 0.3% sodium hyaluronate ophthalmic solution and to increased forward light scatter after instillation of 2% rebamipide ophthalmic suspension in healthy subjects.

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In Fuchs' endothelial corneal dystrophy, the corneal endothelium is damaged more severely in the center and paracentral zones than in the peripheral zone, and peripheral measurement can objectively grade the disease. In the peripheral zones, the inferotemporal endothelium is damaged more severely. These findings might provide a new understanding of the disease mechanisms.

Compared to normal eyes, aqueous-deficient dry eyes show significant regional differences in tear film stability and meibomian glands. Considering these regional differences, the overall observation of the ocular surface, including both upper and lower eyelids, will aid clinicians in understanding this condition better.