ISSN:1094-9313    

DOI:10.1159/000154678

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:1094-9313    

DOI:10.1159/000154680

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The neuron has been studied for over a hundred years, yet our knowledge of the functional morphology of this cell type remains incomplete. There are several features of neurons that are of interest to the structural neurobiologist, including neuronal shape, synapses, gap junctions, neurotransmitters and other organelles. One of the major reasons that neurons have been intractable to thorough structural analysis derives from their shape. The extreme length of some neurons makes a complete description of their structural features at the ultra-structural level a herculean if not impractical task. The problem is compounded when one attempts to image collections of neurons or the entire nervous system. In recent years our understanding of neuronal structure has rapidly increased with the emergence of new imaging technologies. Several technical approaches are currently being used to elucidate the structural basis for neuronal function, including conventional light microscopy, immunohistochemistry, immunofluorescence, confocal microscopy, conventional transmission electron microscopy, high-voltage electron microscopy, stereomicroscopy and three-dimensional reconstruction techniques. One small subset of the nervous system that is amenable to both structural and physiological studies is the taste bud, a small collection of cells found primarily in the tongue, whose primary function is the detection of aqueous chemical stimuli. Much has been learned about the functional morphology of taste buds during the last decade, in part as a result of the application of many of the imaging techniques mentioned above, both singly and in combination.

ISSN:1094-9313    

DOI:10.1159/000154681

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The study of gene expression has been greatly facilitated by many recent advances in the technology of in situ hybridization histochemistry. The purpose of this report is to familiarize investigators with the basic principles of this technique and illustrate its potential with chosen examples in the field of neurobiology. A further goal is to provide insight into the specific options available in the selection of probes for use in non-radioactive (e.g. enzyme histochemical) detection of messenger RNA. Since many species differences should be apparent at the level of gene expression, this technology has considerable potential to aid in comparative studies of the nervous system.

ISSN:1094-9313    

DOI:10.1159/000154682

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The alternative splicing of messenger RNA (mRNA) precursors represents a common mechanism for increasing the flexibility of eukaryotic gene expression by the generation of structurally distinct, developmentally regulated and tissue-specific protein isoforms. The calcitonin/calcitonin-gene-related peptide (CGRP) primary RNA transcript undergoes tissue-specific alternative processing, resulting in the differential production of calcitonin mRNA in thyroid C cells and CGRP mRNA in neurons of the central and peripheral nervous systems. The calcitonin/CGRP gene provides an excellent model for examining the regulation of cell-specific alternative RNA processing events in complex transcription units expressed within the neuroendocrine system. Initial studies attempting to delineate the biochemical events involved in the regulation of these cellular processes have taken advantage of a number of molecular biological techniques including expression of the calcitonin/CGRP transcription unit in transgenic mice, tissue culture model systems that mimic the alternative RNA processing choices made by tissues in vivo and the development of in vitro splicing systems. It is anticipated that combinations of these experimental approaches will allow the definition of biochemical processes and the isolation of the cellular machinery involved in the regulation of cell-specific RNA processing events.

ISSN:1094-9313    

DOI:10.1159/000154683

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The control of gene expression is critical to the proper development of all organisms. Genetic control at the posttranslational level is an important system of such regulation. Recent developments in the understanding of the proteases involved in the endoproteolytic cleavage of prohormones to produce active hormones have begun to provide insight into the tissue-and developmental-specific events of posttranslational processing. This review will discuss the development of our understanding of the action and regulation of these proteases, including KEX2, furin and the prohormone-converting enzymes, PC1 and PC2.

ISSN:1094-9313    

DOI:10.1159/000154684

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Within the last few years, an increasing number of neuropeptide receptors have been structurally and functionally characterized. The analysis of these receptors, along with a precise understanding of their pharmacology and signal transduction pathways, has been facilitated by the use of molecular genetic techniques. This review will highlight some of the techniques currently being used to study neuropeptide receptors. Methods for isolation of complementary DNA clones for receptors, analysis of receptor messenger RNA expression and characterization of cloned receptors expressed in cultured cells are reviewed. In addition, a genetic approach for the analysis of neuropeptide receptor function in the context of a whole mammalian organism is discussed.

ISSN:1094-9313    

DOI:10.1159/000154685

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Enkephalins, dynorphins and β-endorphin are endogenous opiate-like substances that are differentially distributed among vertebrate taxa. Enkephalins have the widest distribution, and the proenkephalin gene would appear to represent the ancestral opioid gene. This review will consider the following hypothesis: the evolution of the opioids occurred as a result of two duplications of the proenkephalin gene. In this hypothesis, the first duplication event would have given rise to the proopiomelanocortin gene, the precursor for β-endorphin, and the second duplication event would have given rise to the prodynorphin gen

ISSN:1094-9313    

DOI:10.1159/000154686

出版商:S. Karger AG    

年代:1993

数据来源: Karger