Taurine-like Immunoreactivity Research Articles

Early development, pattern, and reorganization of the planula nervous system in Aurelia (Cnidaria, Scyphozoa)

We examined the development of the nervous system in Aurelia (Cnidaria, Scyphozoa) from the early planula to the polyp stage using confocal and transmission electron microscopy. Fluorescently labeled anti-FMRFamide, antitaurine, and antityrosinated tubulin antibodies were used to visualize the nervous system. The first detectable FMRFamide-like immunoreactivity occurs in a narrow circumferential belt toward the anterior/aboral end of the ectoderm in the early planula. As the planula matures, the FMRFamide-immunoreactive cells send horizontal processes (i.e., neurites) basally along the longitudinal axis. Neurites extend both anteriorly/aborally and posteriorly/orally, but the preference is for anterior neurite extension, and neurites converge to form a plexus at the aboral/anterior end at the base of the ectoderm. In the mature planula, a subset of cells in the apical organ at the anterior/aboral pole begins to show FMRFamide-like and taurine-like immunoreactivity, suggesting a sensory function of the apical organ. During metamorphosis, FMRFamide-like immunoreactivity diminishes in the ectoderm but begins to occur in the degenerating primary endoderm, indicating that degenerating FMRFamide-immunoreactive neurons are taken up by the primary endoderm. FMRFamide-like expression reappears in the ectoderm of the oral disc and the tentacle anlagen of the growing polyp, indicating metamorphosis-associated restructuring of the nervous system. These observations are discussed in the context of metazoan nervous system evolution.

Modulation of taurine release by metabotropic receptors in the developing hippocampus.

Taurine abounds in the hippocampus14, particularly in the immature hippocampus26, and taurine-like immunoreactivity has been located in hippocampal interneurons, pyramidal neurons and dentate granule cells15. Taurine inhibits the firing of hippocampal pyramidal neurons, increases membrane chloride conductance and causes hyperpolarization20. In the hippocampus, the taurine-synthesizing enzyme cysteine sulphinate decarboxylase has also been identified in pyramidal basket interneurons20. Taurine has been held to have a special role in immature brain tissue12,21. Besides being an osmoregulator and neuromodulator it seems to be essential for the development and survival of neural cells29. The excitatory glutamatergic innervation in the hippocampus is modulated by inhibitory GABA-releasing interneurons8. These mechanisms could also regulate taurine release. Ionotropic glutamate receptors modify taurine release in the hippocampus16,25, as do GABAA receptors in the cerebral cortex and cerebellum24. The hippocampal innervation also includes a large family of metabotropic glutamate receptors (mGluRs) coupled to second messenger systems via GTP-binding proteins. At least eight subtypes of them have been cloned, divided into three major groups based on pharmacology, second-messenger coupling and sequence homology6,22. Metabotropic GABAB receptors, which initiate slow inhibition via Gprotein-coupled action on Ca2+ and K+ channels18, also exist in the hippocampus7. We have now characterized the regulation of taurine release

A Spatiotemporal Wave of Turnover and Functional Maturation of Olfactory Receptor Neurons in the Spiny LobsterPanulirus argus

Olfactory receptor neurons (ORNs) of crustaceans are housed in aesthetasc sensilla that are located on the lateral flagellum of the antennule. We used young adult spiny lobsters to examine turnover of aesthetascs and functional maturation of their ORNs after molting. The proliferation zone for new aesthetascs is located in the proximal part of the aesthetasc-bearing region and progressively moves along a distoproximal axis. Older aesthetascs are lost in the distal part of the aesthetasc-bearing region. As a result, an aesthetasc may be shed three to six molts after it differentiates. Taurine-like immunoreactivity is elevated in ORNs of aesthetascs that have yet to emerge on the cuticular surface and thereafter decreases gradually and asynchronously. ORNs from the distalmost-developing aesthetascs lose taurine-like immunoreactivity immediately before sensillar emergence, whereas ORNs from the most proximal and lateral new aesthetascs retain taurine-like immunoreactivity throughout the intermolt stage after sensillar emergence. Furthermore, taurine-like immunoreactivity is inversely correlated with odor responsiveness. These results suggest that taurine-like immunoreactivity reveals immature ORNs and that their functional maturation is not synchronized with molting and may not be completed until many weeks after sensillar emergence. Our data suggest successive spatiotemporal waves of birth, differentiation and functional maturation, and death of ORNs.

A light and electron microscopic study of taurine-like immunoreactivity in the main olfactory bulb of frogs

The distribution of taurine in the frog olfactory bulb was studied using light and electron microscopic immunohistochemical techniques. At the light microscopic level, taurine-like immunoreactivity (taurine-LI) was found in (i) fibers coursing from the olfactory nerve layer to the glomerular layer, (ii) cell bodies and processes primarily located in the caudal part of the granule cell layer (GCL), and (iii) puncta outlining unstained somata of mitral cells and cells in the GCL. In consecutive sections processed for taurine or GABA, numerous cells of the caudal GCL displayed taurine-LI and GABA-like immunoreactivity (GABA-LI). A bimodal distribution of the cross-sectional cell area for GABA-LI cells implied their morphological diversity, and the peak for larger GABA-LI cells coincided with the maximum for taurine-LI cells. At the electron microscopic level, single immunogold labeling showed that GABA-LI, but not taurine-LI, is present in granule cells, whereas both taurine-LI and GABA-LI were localized in a ‘non-granule’ type of cell. The double labeling procedure demonstrated coexistence of taurine-LI and GABA-LI in neurons of a ‘non-granule’ type. These cells had some ultrastructural features typical of short axon cells in the GCL of the mammalian olfactory bulb and were tentatively considered as short axon-like cells. Results suggest that, in the frog olfactory bulb, taurine is contained in primary olfactory afferents and short axon-like cells of the GCL co-localizing GABA and taurine.

Synaptic Vesicular Localization and Exocytosis ofl-Aspartate in Excitatory Nerve Terminals: A Quantitative Immunogold Analysis in Rat Hippocampus

To elucidate the role of aspartate as a signal molecule in the brain, its localization and those of related amino acids were examined by light and electron microscopic quantitative immunocytochemistry using antibodies specifically recognizing the aldehyde-fixed amino acids. Rat hippocampal slices were incubated at physiological and depolarizing [K+] before glutaraldehyde fixation. At normal [K+], aspartate-like and glutamate-like immunoreactivities were colocalized in nerve terminals forming asymmetrical synapses on spines in stratum radiatum of CA1 and the inner molecular layer of fascia dentata (i.e., excitatory afferents from CA3 and hilus, respectively). During K+ depolarization there was a loss of aspartate and glutamate from these terminals. Simultaneously the immunoreactivities strongly increased in glial cells. These changes were Ca2+-dependent and tetanus toxin-sensitive and did not comprise taurine-like immunoreactivity. Adding glutamine at CSF concentration prevented the loss of aspartate and glutamate and revealed an enhancement of aspartate in the terminals at moderate depolarization. In hippocampi from animals perfused with glutaraldehyde during insulin-induced hypoglycemia (to combine a strong aspartate signal with good ultrastructure) aspartate was colocalized with glutamate in excitatory terminals in stratum radiatum of CA1. The synaptic vesicle-to-cytoplasmic matrix ratios of immunogold particle density were similar for aspartate and glutamate, significantly higher than those observed for glutamine or taurine. Similar results were obtained in normoglycemic animals, although the nerve terminal contents of aspartate were lower. The results indicate that aspartate can be concentrated in synaptic vesicles and subject to sustained exocytotic release from the same nerve endings that contain and release glutamate.

Cell-damaging conditions release more taurine than excitatory amino acids from the immature hippocampus.

High concentrations of excitatory amino acids are neurotoxic and overstimulation of their receptors contributes to neuronal death during cerebral ischemia35. Excitatory amino acids are released from neural structures from adult animals during hypoxia and ischemia1,7,20,23. Oxygen-derived free radicals formed in hypoxic brain tissue also induce release of excitatory amino acids22 and thus contribute to ischemia-induced neuronal damage4. Of the various brain areas, the hippocampus is particularly vulnerable to ischemic injury25. In the newborn, however, the hippocampus is relatively well spared after hypoxia and ischemia3,5. The major part of excitatory innervation in the hippocampus is glutamatergic. Taurine also abounds in the hippocampus11 and taurine-like immunore-activity has been located in hippocampal interneurons, pyramidal neurons and dentate granule cells15. This inhibitory amino acid seems to be essential for the development and survival of neural cells8,34. We have now assessed the simultaneous release of endogenous excitatory amino acids, glutamate and aspartate, together with taurine, in the above cell-damaging conditions in hippocampal slices prepared from immature mice.

Immunoreactivity for taurine in the cochlea: its abundance in supporting cells

Taurine is the second most abundant free amino acid in the brain where its osmoregulatory function is well established. Taurine-deprived kittens show retinal pathology leading to blindness. In the inner ear, taurine has been reported to be the most abundant free amino acid although its role in inner ear function is not known. Immunohistochemistry was employed here to investigate the localisation of taurine in normal cochleae of the guinea pig compared with two different conditions: experimentally induced endolymphatic hydrops and after oral administration of glycerol. In normal cochleae, by light microscopy, taurine-like immunoreaction was never observed in the sensory outer hair cells and appeared absent from the inner hair cells. In contrast taurine-like immunolabeling was found to be present in all supporting tissue with the striking exception of the tectorial membrane and the outer pillar cell which had no or little taurine immunoreactivity respectively. In early experimental endolymphatic hydrops, the distribution of taurine-like immunoreactivity appeared similar to that observed for normal cochleae. In long-term hydrops, degenerated outer hair cells were replaced by the swelling of the phalangeal process of the Deiters' cells which became highly immunoreactive to taurine. After glycerol administration, the tectorial membrane became more tightly bound to the apical surface of the sensory hair cells and distinctly immunoreactive to taurine. The localisation of taurine in the organ of Corti shown here is consistent with taurine being involved in the maintenance of osmotic equilibrium in the normal and perhaps also in the restructuration of the pathological organ of Corti.

Immunocytochemical demonstration of taurine in the retina and pineal organ of the pigeon.

Taurine-like immunoreactivity (TLI) is found in the pigeon retina at high levels within cones, in select cells of the inner nuclear layer and in sublaminae of the inner plexiform layer. At the ultrastructural level a high density of immuno-gold particles in visualized in the ellipsoid, but not in the paraboloid area of the inner segment. It is present in perikarya and the presynaptic endings of cones, but not in postsynaptic cell processes. The immuno-gold particles are not associated directly with the synaptic vesicles. In the pineal organ TLI was confined to the so-called dark pinealocytes which are surrounded by only family stained light pinealocytes. Clusters of protein A-gold particles are located in the ergastoplasm between polyribosomes adjacent to fibrous proteins and in chains along filamentous structures. Granules, vesicles and membrane whorls, which originate from modified cilia remain unlabeled. The results are discussed on the basis of previous findings; a direct or indirect functional relationship of taurine to ATP-dependent processes is suggested.

Immunocytochemical demonstration of taurine in the retina and pineal organof the pigeon

Taurine-like immunoreactivity (TLI) is found in the pigeon retina at high levels within cones, in select cells of the inner nuclear layer and in sublaminae of the inner plexiform layer. At the ultrastructural level a high density of immuno-gold particles is visualized in the ellipsoid, but not in the paraboloid area of the inner segment. It is present in perikarya and the presynaptic endings of cones, but not in postsynaptic cell processes. The immuno-gold particles are not associated directly with the synaptic vesicles. In the pineal organ TLI was confined to the so-called dark pinealocytes which are surrounded by only faintly stained light pinealocytes. Clusters of protein A-gold particles are located in the ergastoplasm between polyribosomes adjacent to fibrous proteins and in chains along filamentous structures. Granules, vesicles and membrane whorls, which originate from modified cilia remain unlabeled. The results are discussed on the basis of previous findings; a direct or indirect functional relationship of taurine to ATP-dependent processes is suggested.

The localization of taurine-like immunoreactivity in the organ of Corti: a semiquantitative, post-embedding immuno-electron microscopic analysis in the rat with some observations in the guinea pig

The cellular and subcellular localization of taurine in the organ of Corti was examined by means of postembedding immunocytochemistry. Supporting cells, including border cells, inner phalaneal cells. Deiters cells, pillar cells, and Bo¨ttcher cells are enriched in taurine-like immunoreactivity, contrasting sharply with inner and outer hair cells which did not show noteworthy immunolabelling. Immunogold cytochemistry indicated an even distribution of taurine throughout the cytoplasm and karyoplasm of the labelled supporting cells. Rats and guinea pigs showed similar labelling patterns. The present immunocytochemical findings indicate that supporting cells are the plausible sources of the reported potassium-induced taurine release in the cochlea. The distribution of taurine in the organ of Corti is not compatible with a transmitter or neuromodulatory action of this amino acid, but rather suggests an involvement in osmoregulatory functions.

Taurine immunoreactivity in the rat supraoptic nucleus: prominent localization in glial cells.

Taurine is an inhibitory amino acid that hyperpolarizes magnocellular neurosecretory neurons. To determine which cell types in the rat supraoptic nucleus contain taurine, we used a monoclonal antibody raised against a taurine conjugate. Preembedding immunocytochemistry was carried out at the light and electron microscopic levels using diaminobenzidine and gold-substituted silver-intensified peroxidase as markers. We report the presence of taurine in all cellular compartments of the supraoptic nucleus, except axons, with variable labeling intensities among the different compartments. Few cell bodies of magnocellular neurons were immunoreactive, but many distal dendrites and some proximal ones showed weak-to-moderate levels of immunoreactivity. Strong immunoreactivity was found over glial cell bodies and their processes, in particular in the ventral glial lamina of the supraoptic nucleus. Large astrocytic processes labeled with the taurine antibody included the endfeet participating in the glial limitans around capillaries and at the ventral surface of the hypothalamus. Other types of immunoreactive astrocytic profiles were found scattered within the neuropil where these processes participated in different interactions with the neuronal elements of the supraoptic nucleus. Immunoreactive glial expansions, sometimes even the main process of the glial cell, engulfed axonal boutons. Other labeled glial processes were found between two magnocellular perikarya or closely apposed to the membrane of axonal boutons contacting the neuronal cell bodies. The frequent finding of closely apposed glial and dendritic elements bearing different levels of taurine-like immunoreactivity suggests that exchange of taurine between those two compartments may occur. We propose that taurine could be released from supraoptic glia by a small decrease in osmolarity or by receptor-mediated mechanisms during conditions of low hormonal (vasopressin and/or oxytocin) needs. Such released taurine could then act on presynaptic or postsynaptic sites, or both, to exert its neuromodulatory actions.

Sensory neuron development revealed by taurine immunocytochemistry in the honeybee

The formation of ommatidia in the compound eyes and sensilla on the antennae of the honeybee was followed and the development of their sensory neurons was traced using an antiserum against taurine as a marker. Taurine-like immunoreactivity (Tau-IR) is expressed in sensory neurons of several modalities, namely visual, olfactory, gustatory, and mechanosensory. Staining intensity is very high in the larva and in the first half of the pupal stage and gradually decreases towards the end of metamorphosis. In the photoreceptor cells of the compound eyes, Tau-IR can be detected from the fifth larval instar onwards, prior to differentiation of other components of the ommatidium. Already in the midstage larvae, when the antennal primordia of the adult still lie within the peripodial cavity, a few presumably mechanosensory neurons are labelled in the pedicellus of the developing antenna. The majority of the antennal sensory neurons which are located on the flagellum start to exhibit Tau-IR upon pupation, long before any cuticular specializations such as sensory hairs or plates are detectable. All known types of antennal sensilla were identified and it could be shown that all of them are innervated by Tau-IR sensory neurons. Thus, taurine immunocytochemistry can be applied as a useful label for developing sensory neurons. Functional implications of taurine during development are discussed.

Differential subcellular distribution of glutamate and taurine in primary olfactory neurones.

Taurine and glutamate are widely distributed amino acids in the mammalian brain, including the olfactory bulb where their functions have not been fully elucidated. This study investigated the precise cellular distribution of taurine and glutamate in the nerve layer and the glomeruli of the olfactory bulb, using semiquantitative immunocytochemistry at the electron microscopic level. The results show that both amino acids are present at higher concentrations in primary olfactory neurones than in the postsynaptic dendrites. Glutamate is also enriched in terminals vs axons of the primary olfactory neurones. This suggests that glutamate acts as a neurotransmitter at the primary synapse in the olfactory system. An opposite concentration gradient is found for taurine, with a higher level of taurine-like immunoreactivity in axons than in terminals of primary olfactory neurones. Further studies are required before conclusions can be drawn about the function of taurine in these neurones.

Immunocytochemical localization of amino acid neurotransmitter candidates in the ventral horn of the cat spinal cord: a light microscopic study.

The distribution of immunoreactivities to six amino acids, possibly related to synaptic function, was investigated in the motor nucleus of the cat L7 spinal cord (laminae VII and IX) using a postembedding peroxidase-antiperoxidase technique. Consecutive 0.5 micron transverse sections of plastic-embedded tissue were incubated with antisera raised against protein-glutaraldehyde conjugates of gamma-aminobutyric acid (GABA), glycine, aspartate, glutamate, homocysteate, and taurine. This method allowed localization of the different immunoreactivities in individual cell profiles. The results showed that all these amino acids, except homocysteate, could be clearly detected in either neuronal or glial elements in the ventral horn. In cell bodies of neurons in lamina VII, immunoreactivity was observed for aspartate, glutamate, GABA, and glycine. Adjacent section analysis revealed that combinations of immunoreactivity for glycine/glutamate/aspartate, GABA/glycine/glutamate/aspartate and glutamate/aspartate, respectively, may occur in one and the same cell. In the motor nuclei (lamina IX), immunoreactivity to amino acids was observed in two types of neuron. Large cells, probably representing alpha-motoneurons, were harboring immunoreactivity to both glutamate and aspartate, while a few small neurons in this area displayed a colocalization of glycine, glutamate, and aspartate. Dendrites and axons in the motor nuclei contained glycine/glutamate/aspartate, GABA/glycine/glutamate/aspartate, and glutamate/aspartate immunoreactivities. In both laminae VII and IX, taurine-like immunoreactivity was absent in neuronal cell bodies, but highly concentrated in perivascular cells and small cells with a morphology resembling that of glial cells. A punctate immunolabeling, in all probability representing labeling of nerve terminals, could be demonstrated in the ventral horn for GABA, glycine, and glutamate, but not with certainty for aspartate or taurine. A quantitative estimate of the covering of cell bodies of alpha-motoneuron size by immunoreactive puncta revealed that glycine immunoreactive terminal-like structures were most abundant (covering 26-42% of the somatic membrane), while glutamate immunoreactive terminals were seen least frequently (5-9% covering). GABA-immunoreactive terminals covered from 10 to 24% of the soma surface.(ABSTRACT TRUNCATED AT 400 WORDS)

Taurine-like immunoreactivity in octopaminergic neurones of the cockroach, Periplaneta americana (L.).

Taurine (2-aminoethanesulphonic acid) is reported to interact with the octopaminergic system. The distribution of taurine-like immunoreactivity (-LIR) in relation to octopamine-like immunoreactive dorsal unpaired median (DUM) neurones was investigated with the aim of revealing possible colocalization of these two neuromediators. The specificity of the anti-taurine serum used was demonstrated by dot blot immunoassay and by use of preabsorption controls. There was no crossreactivity with octopamine. The specificity of the octopamine antiserum employed has been described elsewhere. Taurine-LIR could be demonstrated in large dorso-median cells in the suboesophageal and the mesothoracic ganglion as well as in the abdominal ganglia. In addition taurine-LIR is distributed in numerous other regions of the ganglia. A comparison of the immunostaining for taurine and octopamine indicates that several of the taurine-like immunoreactive (-LI) neurones are probably members of the octopamine-immunoreactive DUM cell population. These taurine-LI neurones resemble octopamine-LI DUM cells in soma position and size as well as in the projections of their primary neurites. Colocalization of octopamine-LIR and taurine-LIR within the same neuronal element could be shown by alternate immunostaining of consecutive sections. It is probable that all octopamine-LI DUM neurones also exhibit taurine-LIR, and the possible physiological significance of this coexistence is discussed.

Neurotransmitters in the nervous system of Macoma balthica (Bivalvia)

The distribution of histamine-, octopamine-, gamma-aminobutyric acid- (GABA) and taurine-like immunoreactivity in the bivalve mollusc Macoma balthica was studied immunocytochemically with antisera produced in rabbits. Histamine levels in the ganglia and whole animals were also measured by high-performance liquid chromatography using a postcolumn derivatization method. Immunoreactivity for these substances, except for taurine, is found in the central nervous system of this species. The most extensive neuronal system is revealed with the antiserum against histamine. All the main ganglia contain histamine-immunoreactive cell bodies, and a dense network of nerve fibers is seen in the ganglia and nerve roots. Histamine-immunoreactive nerve fibers project to the mantle edge, lips and oesophagus. The basal part of the inhalant siphon is rich in histamine-immunoreactive fibers. Unlike histamine, octopamine- and GABA-like immunoreactivities are restricted to the central nervous system. Taurine-like immunoreactivity is not found in the nervous system of this species. In the nervous system, histamine-immunoreactive cell bodies and fibers are more numerous than those that are octopamine- and GABA-immunoreactive. The distribution of these substances in the ganglia is different. GABA-immunoreactive cells are typically smaller than most of the histamine- and octapamine-immunoreactive cells. Most GABA- and octopamine-immunoreactive cells and fibers are located in the pedal ganglion. Histamine is distributed more evenly in the ganglia and nerve roots. The biochemical measurements of histamine correlate well with the immunohistochemical findings and confirm the predominant location of the amine in the nervous tissue. These results suggest that histamine is more widespread than some other putative transmitters, and support the concept that histamine may have an important role in many physiological processes in molluscs.

Visualization of taurine, GABA and glutamate in developing feline cerebellum by immunohistochemistry

The localization of taurine, GABA and glutamate in developing feline cerebellum was performed using antibodies raised against the amino acids conjugated to bovine serum albumin with glutaraldehyde. Distinct patterns of immunostaining were observed for each of the amino acids. Taurine-like immunoreactivity reached a peak at 4 weeks after birth, as did GABA-like immunoreactivity, whereas glutamate-like immunoreactivity was greatest in the mature cerebellum. Purkinje cells are all taurine-positive in cerebellum from neonatal animals, whereas in the mature cerebellum they appear to contain only GABA and glutamate, with virtually no taurine, in contrast to observations reported with rodent cerebellum. Ultrastructural studies and immunogold labelling visualized by electron microscopy show that the band of taurine-like immunoreactivity observed in newborn feline cerebellum is localized within dendrites, axons and glial processes. Granule cells migrating through this region also show prominent taurine-like immunoreactivity.

Neuronal-glial exchange of taurine during hypo-osmotic stress: A combined immunocytochemical and biochemical analysis in rat cerebellar cortex

Rat cerebellar Purkinje cells show a high level of taurine-like immunoreactivity. Light-microscopic immunocytochemisty indicated that the level of taurine in these cells was substantially decreased in animals that had survived for 4 h after an intraperitoneal injection of distilled water. This treatment resulted in a 15–20% reduction in plasma osmolality. The changes in the Purkinje cells were accompanied by an increased immunolabeling of neighboring glial cells (Golgi epithelial cells). The changes in both cell types were reversed in animals whose plasma osmolality had been normalized by injections of hypertonic saline 4 h after the water loading. Adjacent sections incubated with a GABA antiserum did not exhibit any overt changes in response to the hypo-osmotic stress. Quantitative electron-microscopic analysis of ultrathin sections subjected to postembedding immunogold cytochemistry indicated that the Purkinje cells had lost 50–60% of their taurine contents after water loading and that the loss affected all intracellular compartments, including mitochondria and cytoplasmic matrix. The loss of taurine immunoreactivity from Purkinje cells was accompanied by an estimated 70–80% increase in the contents of immunoreactive taurine in adjacent glial cells. Biochemical recordings of tissue amino acids in a parallel series of animals revealed a 12% reduction in cerebellar taurine contents 4 h after water loading (value corrected for changes in specific gravity). This reduction had progressed to 32% after 8 h and was only partly prevented by normalization of plasma osmolality. The tissue levels of GABA and several other amino acids showed a decrease similar to that of taurine, while glutamine displayed a considerable increase after water loading. Our findings indicate that acute reductions in plasma osmolality cause a flux of taurine from Purkinje cells to glia, and that this flux is reversed upon normalization of plasma osmolality. These changes are superimposed on a decrease in the biochemically recorded tissue level of taurine. Unlike the cellular redistribution, this decrease was not reversible within the time frame of the present study, and it was not specific for taurine. Cellular redistribution of taurine may represent a rapid adjustment to osmotic perturbations in vivo. In addition, it may reflect a higher priority for neuronal compared with glial volume regulation.

Distribution of taurine-like immunoreactivity in the mouse liver during ontogeny and after carbon tetrachloride or phenobarbital intoxication.

The ontogenic pattern of development of taurine-like immunoreactivity (TLI) was studied in the mouse liver. The effect on adult mice of carbon tetrachloride or phenobarbital treatment was also examined. Light-microscopically, granules of TLI were first found in the liver from 17-day-old embryos, diffusely distributed throughout the lobules. These positive granules increased with age, were most numerous in the two-week-old mouse, and were notably decreased in the central region of some lobules in the three-week-old mouse. In mature mice, hepatocytes containing TLI-positive granules were distributed unevenly in each liver lobule, and were located predominantly in the peripheral region. Electron-microscopically, TLI was observed in small vesicles in the cytoplasm of hepatocytes and was found mainly in the cisternal lumen of smooth-surfaced endoplasmic reticulum. Some taurine-positive vesicles surrounding the reticulum seemed to associate with the protoplasm. Similar positive vesicles were often located near the bile canaliculi. In carbon tetrachloride-intoxicated mature mice, TLI was no longer limited to the peripheral region of lobules; hepatocytes situated in the central region of lobules also contained intense TLI. In mice injected with a small and repeated dose of phenobarbital, the distribution pattern of TLI was similar to that in the untreated group. However, in mice injected with a large dose of phenobarbital, TLI was markedly increased, especially in the central region of lobules. The results demonstrate that the distribution pattern of TLI in mouse liver changes during development, and that the pattern in mature mice is affected by intoxication with carbon tetrachloride or a toxic dose of phenobarbital.

Distribution of taurine in the rat cerebellum and insect brain: application of a new antiserum against carbodiimide-conjugated taurine.

The production, specificity and application of an antiserum against taurine conjugated to succinylated ovalbumin by means of 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide is reported. The antiserum was produced in rabbits. The carbodiimide was used also as a tissue fixative. The development of the antibody titre was followed by dot-blot tests on nitrocellulose filters using different amino acid conjugates and with immunohistochemical reaction in the rat and insect brain. Blocking controls were also used. Taurine antiserum, sufficiently specific and sensitive, developed after the fourth booster injection, after which the antiserum was characterized. In the insect brain, intense taurine-like immunoreactivity was observed in the photoreceptors, in the Kenyon cells and the neuropile of the mushroom bodies, in the lower part of the central body and in the antennal lobes. In the rat carebellum, intense taurine-like immunoreactivity was seen in the Purkinje cells. Immunoreaction was seen also in small cells most probably corresponding to the basket cells. The use of the carbodiimide in the production of antisera against taurine provides a parallel method for comparison of the distribution of taurine-like immunoreactivity obtained with antisera made against conjugates prepared with aldehydes.