DEVELOPMENTAL CHANGES OF CHOLINESTERASES AND MONOAMINE OXIDASE IN CHICK EMBRYO SPINAL AND SYMPATHETIC GANGLIA

Abstract— Total cholinesterase, acetylcholinesterase, (AChE) and monoamine oxidase (MAO) activity and protein content were determined throughout the embryonic life of the chick in spinal and sympathetic ganglia. The greatest part of total cholinesterase activity was due to AChE.
AChE and MAO activity increased in both spinal and sympathetic ganglia very similarly from the 6th to the 12th day of incubation; from this day on a significant divergence occurred, mainly owing to a steady fall in spinal ganglion AChE, which decreased to approximately one tenth of the maximum value. The ratio of MAO activity in sympathetic and spinal ganglia increased from the 8th day onwards and approached 5·0 at hatching. The ratio between sympathetic and spinal ganglia, for AChE, choline acetylase (ChAc) and MAO activity, suggests a relationship between the maturation of the synapse in the sympathetic ganglia and the maximal activity of these enzymes.     

CHOLINE ACETYLTRANSFERASE (ChAc) ACTIVITY IN DEVELOPING CHICK OPTIC CENTRES AND THE EFFECTS OF MONOLATERAL REMOVAL OF RETINA AT AN EARLY EMBRYONIC STAGE AND AT HATCHING

The choline acetyltransferase (ChAc) activity was measured in the optic centres of chick embryos after early removal of the optic cup and of young chicks after monolateral extirpation of the right eyeball after hatching. The contralateral optic lobes were thus deprived of their complement of retinal fibres. The following results were obtained: in chick embryos the ChAc was slightly lower in the deafferented lobe between the 10th and the 14th day of incubation; between the 14th and the 17th day a critical fall in activity was observed leading to a significant ChAc loss of 71 per cent. In eye deprived chicks no significant change in total ChAc activity occurred during the first postoperative month; significant changes were found only in the second month. The results reached so far suggest that removal of retinal fibres does not cause short term changes in optic centre ChAc in either the embryo or the chick. ChAc contained in nerve cell bodies seems independent of synapses and its behaviour is interpreted as a reflection of metabolic disturbance of the centre.     

Neurofilament immunoreactivity and acetylcholinesterase activity in the developing sympathetic tissues of the rat.

In this study, the ontogenetic appearance of three neuronal markers, tyrosine hydroxylase (TH), neurofilament (NF) proteins and acetylcholinesterase (AChE), have been compared in the neural tube and derivatives of the neural crest with special consideration on developing rat sympathetic tissues. The tree markers appeared for the first time on embryonic day E 12.5. At this age, NF immunoreactivity was located in the cells on the ventro- and dorsolateral edges of the neural tube, i.e., in the regions where the cells had reached the postmitotic stage. In addition, on day E 12.5, NF-immunoreactive fibers were located in the dorsal and ventral roots and the spinal and sympathetic ganglia. This suggests rapid extension of neurites. In contrast to NF, AChE first appeared on day E 12.5 in cell somata of spinal and sympathetic ganglia and only after that in axons. Thus, it can be considered as a marker of differentiating neuronal cell bodies. In the developing sympathoadrenal cells, TH is expressed before NF and AChE. However, the migrating TH immunoreactive sympathetic cells are constantly followed by NF immunoreactive fibers, suggesting that sympathetic tissues may receive innervation from preganglionic axons at the very beginning of their ontogeny. During the later development, all sympathetic tissues contain two major cell groups: 1) one with a moderate TH immunoreactivity, NF immunoreactivity and AChE activity and 2) the other with an intense TH immunoreactivity but lacking NF immunoreactivity or AChE activity. The former includes principal neurons, neuron-like cells of the paraganglia and noradrenaline cells of the adrenal medullae, and the latter includes ganglionic small intensely fluorescent (SIF) cells, paraganglionic cells and medullary adrenaline cells.     

Neurofilament immunoreactivity and acetylcholinesterase activity in the developing sympathetic tissues of the rat

Summary In this study, the ontogenetic appearance of three neuronal markers, tyrosine hydroxylase (TH), neurofilament (NF) proteins and acetylcholinesterase (AChE), have been compared in the neural tube and derivatives of the neural crest with special consideration on developing rat sympathetic tissues. The tree markers appeared for the first time on embryonic day E 12.5. At this age, NF immunoreactivity was located in the cells on the ventro- and dorsolateral edges of the neural tube, i.e., in the regions where the cells had reached the postmitotic stage. In addition, on day E 12.5, NF-immunoreactive fibers were located in the dorsal and ventral roots and the spinal and sympathetic ganglia. This suggests rapid extension of neurites. In contrast to NF, AChE first appeared on day E 12.5 in cell somata of spinal and sympathetic ganglia ond only after that in axons. Thus, it can be considered as a marker of differentiating neuronal cell bodies. In the developing sympathoadrenal cells, TH is expressed before NF and AChE. However, the migrating TH immunoreactive sympathetic cells are constantly followed by NF immunoreactive fibers, suggesting that sympathetic tissues may receive innervation from preganglionic axons at the very beginning of their ontogeny. During the later development, all sympathetic tissues contain two major cell groups: 1) one with a moderate TH immunoreactivity, NF immunoreactivity and AChE activity and 2) the other with an intense TH immunoreactivity but lacking NF immunoreactivity or AChE activity. The former includes principal neurons, neuron-like cells of the paraganglia and noradrenaline cells of the adrenal medullae, and the latter includes ganglionic small intensely fluorescent (SIF) cells, paraganglionic cells and medullary adrenaline cells.     

A histochemical study of the distribution of choline acetyltransferase and acetylcholinesterase activity in sensory ganglia and nerve roots of the bullfrog

Synopsis Histochemical techniques were employed for the localization of choline acetyltransferase (ChAc; EC 2.3.1.6.), acetylcholinesterase (AChE; EC 3.1.1.7) and cholinesterase (ChE; EC 3.1.1.8) activities in dorsal and ventral roots and dorsal root ganglia of the bullfrog. AChE activity was present in most of the neuronal elements of dorsal root ganglia, in some nerve fibres in the dorsal roots, and in all nerve fibres in ventral roots. ChE activity in dorsal root ganglia and in the dorsal roots was confined to non-neuronal elements. No ChE activity was demonstrable in the ventral roots. ChAc activity was localized in many neurons of the dorsal root ganglia and in some nerve fibres of the dorsal roots; however, none of the ventral root fibres were visibly reactive. Some supportive cells of the dorsal roots and ganglia contained small amounts of ChAc activity. Except for the ventral roots, the histochemical distribution of AChE and ChAc activity was similar. The results of solubility studies indicated that under the histochemical conditions, approximately 50% of the ChAc remained bound to the dorsal roots and ganglia, whereas more than 90% of the ChAc in the ventral roots was soluble. This would account for the lack of reactivity in ventral root fibres. Differences in ChAc solubility are discussed in relation to the interpretation of histochemical data and in relation to the concept of multiple forms of ChAc. The results of this study indicate that at least one-third of the neurons of the dorsal root ganglia contain significant levels of the enzymes involved in both the synthesis and hydrolysis of acetylcholine.     

Regional and subcellular distribution of choline acetyltransferase in the brain of rats

—Homogenates of corpus striatum, cerebral cortex and hypothalamus excised from rat brain were fractionated on discontinuous Ficoll and sucrose density gradients, and the distribution of choline acetyltransferase (ChAc) in the mitochondrial and synaptosomal fractions was determined. In the hypothalamic and cortical regions the fractions enriched in synaptosomes showed much higher activity of ChAc than those containing mainly mitochondria. On the other hand, the corpus striatum showed an equal distribution of ChAc activity in those two fractions. The localization of ChAc was also studied in the postnuclear supernatants obtained from three brain regions, using continuous sucrose density gradients. The distribution of ChAc was compared to that of monoamine oxidase (MAO), potassium and protein. When the pellets obtained from the fractions collected from the gradient were suspended in sucrose, the peak of ChAc activity was close to that of MAO in all three brain regions. When 0.1 mm EDTA +1% butanol was used in order to liberate the occluded form of ChAc, the maximum liberation occurred in lighter fractions, resulting in a shift of the activity peak toward the top of the gradient. This was found with fractions from hypothalamic and cortical regions. In the striatum, the liberated ChAc remained in the same fractions as the occluded enzyme. The results indicate that ChAc is liberated only in those fractions where it is present in synaptosomes. In agreement with the results on the discontinuous gradients this occurs in particles of lower density than mitochondria in cortex and hypo-thalamus, but in particles of similar density to mitochondria in the corpus striatum, indicating regional differences in the distribution of ChAc in the brain. K+ containing particles centrifuged in less dense fractions than those containing ChAc, indicating that synaptosomes are heterogeneous with respect to these two marker substances.     

A MICRO-SCALE PROCEDURE FOR THE PREPARATION OF SUBCELLULAR FRACTIONS FROM INDIVIDUAL AUTONOMIC GANGLIA

Abstract— A microscale modification for the preparation of subcellular fractions employing milligram and submilligram amounts of neuronal tissue (brain nuclei and autonomic ganglia) is described.
Electron microscope characterization and enzymic studies were carried out on the six subcellular fractions of sympathetic ganglia of cat thus prepared.
The synaptosomal preparations obtained from individual ganglia were poorer in their nerve ending content than those obtained from brain by previous investigators. The highest RSA for AChE was found in layer L₂ which was rich in membranes and vesicle components. ChAc activity was also highly concentrated in layers L₂ and L₃ (membranes, nerve ending-like particles, mitochondria and 'ghosts'). MAO activity was particularly high in the layers L₄ and L₅ which contained a large number of mitochondria. Layer L₁ (membrane fragments) and particularly layer L₆ which contained mainly collagen fibres, were low in activity of all three enzymes.
After preganglionic denervation, both ChAc and AChE activities were significantly reduced in the purest nerve ending fraction, L₃ while MAO activity was practically unchanged.     

Factors regulating development of an embryonic mouse sympathetic ganglion.

Embryonic development of the mouse superior cervical ganglion (SCG) is defined in vivo and in vitro using morphologic, morphometric, and biochemical approaches. Catecholamine fluorescence was present in the SCG on Day 14 of gestation and underwent characteristic changes in distribution among neurons between this time and adulthood. During prenatal ontogeny, choline acetyltransferase (ChAc) activity increased 2-fold, while tyrosine hydroxylase (T-OH) activity rose 30-fold and total protein increased 4-fold. Ganglionic explants from 14-day embryos extended neurites and exhibited specific biochemical development in medium without added nerve growth factor (NGF). However, the addition of NGF further stimulated neuronal development: Ganglia exhibited significant increases in ChAc and T-OH activities and in total protein compared to controls grown in medium without added NGF. The presence of target submandibular gland radically altered development of T-OH activity in cultured sympathetic ganglia. By 5 days in culture, ganglia grown with target tissue, even in the presence of anti-NGF, exhibited a 10- to 15-fold increase in T-OH activity compared to zero-time controls, and a 2-fold increase over ganglia grown alone or with nontarget tissue. Ganglia grown with target salivary glands showed a correspondingly greater elaboration and directionality of nerve fiber outgrowth, even in the presence of anti-NGF.     

Activating effect of substance P on nerve tissue in culture

The effect of substance P on explant development was investigated in organotypic cultures of rat sympathetic ganglia and spinal cord. The pattern of evolution, cellular composition, and dimensions of the growth zone were evaluated on the basis ofin vivo observations. It was found that this peptide exercises a significant growth-promoting effect at a concentrations of 10^–5–10^–12 M for sympathetic ganglia and 10^–5–10^–14 M for spinal cord culture. The growth zone of sympathetic ganglia measured 1.3–1.6 times the control level by the 14th day of culture at all effective concentrations. The area of outgrowth of spinal cord explants increased 2.0–5.2 fold by the sixth day of culture and peak response was recorded at concentrations of 10^–5 and 10^–12 M. This effect resembled response to opioid peptides [1, 3]. The likely physiological significance of regulatory peptides for the processes of nerve tissue development and regeneration is discussed in the light of these findings, together with the part played by the nociceptive/antinociceptive system in processes of histogenesis and repair.Institute of Experimental Cardiology, All-Union Cardiologic Research Center, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 18, No. 5, pp. 610–615, September–October, 1986.     

Nerve growth-promoting activity in the chick embryo: quantitative aspects

Nerve growth-promoting activity in organ extracts from the chick embryo was titrated using ganglia explanted to a collagen gel. Fibre outgrowth responses evoked in ciliary, sympathetic and spinal ganglia were well correlated. At embryonic day 8, 66% of the activity was localized in the yolk sac, 19% to the chorioallantois and the remaining 15% was widespread in the embryo. At day 18, total activity had increased 27-fold, the carcass now accounting for 90%. In parallel, the embryo extracts also promoted survival and neurite extension in dissociated ganglionic neurons seeded at low density in the gel. It is suggested that the observed effects are due to one active substance widely distributed in the embryo and increasing in amount during development. The substance has a molecular weight of over 10,000 and is distinct from nerve growth factor (NGF). A function of it may be to regulate axonal growth and survival of autonomic and sensory neurons.     

The development of the neurons of the glossopharyngeal (IX) and vagal (X) sensory ganglia in chick embryos

The timetable of cell generation, neuronal death and neuron numbers in the fused proximal glossopharyngeal (IX) and vagal (X) ganglion and distal IX and X ganglia were studied in normal and nerve growth factor (NGF) treated chick embryos. 3H-thymidine was injected between the 3rd and 7th days of incubation and embryos sacrificed on the 11th day. Neurons in the distal IX and X ganglia were generated between the 2nd and 5th days of incubation, the peak mitotic activity occurring on the 4th and 3rd days, respectively. Neurons of the proximal IX and X ganglion were generated between the 4th and 7th days, with maximum neuron generation on the 5th day of incubation. Counts of neurons in the 3 ganglia between the 5th and 18th days of incubation showed a maximum of 22,000 on the 8th day in the proximal IX and X ganglion and this decreased to 12,000 by the 13th day. In the distal IX ganglion, the neuron number decreased by 44% from 4,500 on the 6th day to 2,500 by the 11th day. A similar decrease of 43% was found in the distal X ganglion, the neuron number falling from 11,500 on the 7th day to 6,500 by the 11th day of incubation. Neuronal cell death in these ganglia extended from the 5th to the 12th day of incubation, maximum cell death occurring at or after the cessation of mitotic activity. NGF administration from the 5th to the 11th day of incubation did not have a measurable effect on the neurons of proximal IX and X and distal IX ganglia, but increased neuronal survival by 30% in the distal X ganglion.(ABSTRACT TRUNCATED AT 250 WORDS)     

光叶楮扦插生根的吲哚乙酸氧化酶、多酚氧化酶、过氧化物酶活性变化研究

对光叶楮扦插生根过程中吲哚乙酸氧化酶（IAAO）、多酚氧化酶（PPO）、过氧化物酶（POD）3种酶进行了动态跟踪分析。结果表明：IAAO活性在扦插初期逐渐上升,第10d上升到高峰,之后下降再上升,第30d达到新高峰,然后迅速下降;前25d POD活性变化规律与IAAO相似,但30d以后活性一直上升;PPO活性在扦插前期缓慢上升,第20d上升到了最高点,此后变化不大。还研究了IAAO、PPO、POD与不定根的发生和发展关系,认为光叶楮扦插生根可分为愈伤组织形成期、根诱导期和根的伸长期3个阶段,愈伤组织形成期3种酶活性都呈上升趋势,根诱导期IAAO和POD的活性达到高峰;而根伸长期IAAO和POD活性下降,PPO活性上升。     

Evidence for the extreme overestimation of choline acetyltransferase in human sperm, human seminal plasma and rat heart: a case of mistaking carnitine acetyltransferase for choline acetyltransferase

Detection of choline acetyltransferase (ChAc) in a number of non-neuronal tissues has been extremely overestimated. There are two major types of errors encountered. Type 1 error occurs when endogenous substrates (e.g. L-carnitine) are acetylated by acetyltransferase enzymes (e.g. carnitine acetyltransferase ( CarAc ) ) yielding an acetylated product mistaken for acetylcholine (AcCh). In the past, human sperm and human seminal plasma putative ChAc activity has been extremely overestimated due to Type 1 error. This study demonstrates (1) an endogenous acetyltransferase and substrate activity in human sperm and human seminal plasma forming an acetylated product that is not AcCh but probably acetylcarnitine ( AcCar ); (2) that the addition of 5 mM choline substrate does not significantly increase acetyltransferase activity; (3) that boiled seminal plasma contains an endogenous acetyltransferase substrate which is not choline, but probably L-carnitine. Type 2 error occurs when endogenous carnitine acetyltransferase synthesizes true AcCh, resulting in mistaken evidence for ChAc. This is demonstrated by the fact that the choline substrate Km-value for the neuronal or true ChAc from mouse brain is 0.73 +/- 0.06 mM while the Km-value of choline substrate for purified CarAc from pigeon breast muscle is 108 +/- 4 mM. Type 2 error has occurred for the estimation of putative ChAc in rat heart. The rat heart ChAc was measured in previous studies utilizing a concentration of 30 mM choline substrate. While saturation of neuronal ChAc is observed at 2-5 mM choline, saturation of the rat heart CarAc enzyme is not reached until over 800 mM. Purified CarAc significantly synthesizes AcCh at 30 mM choline. Thus, putative ChAc has been greatly overestimated in the scientific literature for mammalian sperm, human seminal plasma and rat heart.     

Sensory,motor, and postganglionic sympathetic neurons forming the ulnar and radial nerves of two macaque species: Macaca nemestrina and Macaca fascicularis

The motor, sensory, and postganglionic sympathetic neurons forming the left ulnar and right radial nerves of long-tailed macaques (Macaca fascicularis) and pigtailed macaques (Macaca nemestrina) were localized by the horseradish peroxidase method of tracing neuronal connections. The ulnar and radial motoneurons formed a longitudinal column of variable extent in the lateral part of the ventral horn. In most animals, the ulnar motoneurons extended between the caudal ends of the C7 and T1 segments; the radial motoneurons extended between the rostral level of the C4 and the middle part of T1 segments. Although there were areas of overlap in the spinal distribution of ulnar and radial motoneurons, the ulnar motoneurons were located more dorsally and dorsolaterally than were the radial motoneurons. In most animals, labelled sensory neurons whose axons run with the ulnar nerve occurred in the C8–T4 dorsal root ganglia, and those whose axons run with the radial nerve occurred in the C5–T3 ganglia. The radial sympathetic neurons were distributed in stellate through T7 paravertebral sympathetic ganglia, and the ulnar sympathetic neurons were distributed in stellate through T4 paravertebral sympathetic ganglia. Though the motor, sensory, and sympathetic neurons forming the ulnar and radial nerves had wide segmental distributions, all showed peak frequencies in two segments. The cross-sectional areas of the motor, sensory, and postganglionic sympathetic neurons forming the radial and ulnar nerves were measured in the animal that showed the greatest amount of labelling for each nerve. The ulnar and radial motoneurons had a similar range of sizes, with cross-sectional areas between 120 and 2,160 μm². Most were smaller than 900 μm². The sensory neurons forming the ulnar and radial nerves also displayed a similar range of sizes, measuring between 120 and 3,360 μm² in cross-sectional area. Most neurons measured between 201 and 800 μm². The ulnar sympathetic neurons measured between 120 and 840 μm², and the radial neurons between 120 and 2,120 μm². In both cases, most neurons measured between 120 and 600 μm². The mean cross-sectional area for the radial sympathetic neurons was, however, larger than that for the ulnar sympathetic neurons.     

The localization of acetylcholinesterase activity in the spinal ganglia of the adult fowl studied by electron microscope histochemistry

Summary AChE activity was localized in spinal ganglia of adult fowls at the electron microscope level using Karnovsky’s method. Controls with BW 284 C 51 were carried out. In the neuronal bodies, AChE activity was evident within the rough-surfaced cisternae of the endoplasmic reticulum, including the perinuclear cisterna and the subsurface cisternae, and sometimes in the innermost cisternae of the Golgi complex. AChE activity was also demonstrated along the axolemma and associated with smooth-surfaced vesicles and tubules in the initial segment of the axon, in all the ganglionic myelinated fibers examined by serial section analysis and in more than half of the ganglionic unmyelinated fibers examined by this method. In the myelinated fibers the reaction product appeared more abundant at the level of the nodes of Ranvier than in the internodal segments. Both in the myelinated and unmyelinated fibers a considerable quantitative variability of reaction product was observed among the various sections of the same fiber. These results were compared with those previously obtained in the spinal ganglia of the chick embryo using the same histochemical method. This research was supported by a grant of the National Research Council (C.N.R.), Italy, and of the Deutsche Forschungsgemeinschaft (DFG), Federal Republic of Germany. 1 AChE=acetylcholinesterase (=true or specific cholinesterase); ACh=acetylcholine; ChAc=choline acetylase (=choline acetyltransferase).     

Specificity of nerve fibre 'attraction' to autonomic effector organs in tissue culture.

Explants of atrium, vas deferens and lung from 5-day-old rats were grown between, and 1–2 mm from, a row each of sympathetic ganglia and spinal cord explants. After 5 days the amount of sympathetic nerve fibre growth in cultures with atrium or vas deferens (but not lung) was greater than in controls and directed towards the tissues. In contrast, in cultures with atrium, vas deferens and lung, the direction and amount of nerve growth from spinal cord explants was not significantly different from controls. Further, when sympathetic ganglia were grown between, and 1–2 mm from, a row each of atrium and ventricle explants, the total amount of nerve growth was increased and directed mainly towards the atrium. The results are discussed in relation to the hypothesis that normally densely innervated autonomic effector organs contain higher levels of Nerve Growth Factor than tissues which become more sparsely innervated, and that this allows nerve fibres from sympathetic ganglia (but not NGF-insensitive spinal cord) to distinguish between different tissues from a distance.     

Sources of porcine longissimus dorsi muscle (LDM) innervation as revealed by retrograde neuronal tract-tracing

The aim of the present study was to establish the origin of the motor, autonomic and sensory innervation of the L1-L2 segment of the porcine longissimus dorsi muscle (LDM), in order to provide morphological basis for further studies focusing on this neural pathway under experimental conditions, e.g. phototerapy and/or lateral electrical surface stimulation. To reach the goal of the study, multiple injections of the fluorescent neuronal tracer Fast Blue (FB) were made into the LDM region between the spinal processes of the vertebrae L1 and L2. The spinal cord (Th13-S1 segments) as well as the sensory and autonomic ganglia of interest, i.e., dorsal root (DRG) and sympathetic chain ganglia from corresponding spinal cord levels were collected three weeks later. FB-positive (FB+) motoneurons were observed exclusively within the nucleus ventromedialis at L1 and L2 spinal cord level, forming the most ventro-medially arranged cell column within this nucleus. Primary sensory and sympathetic chain neurons were found in appropriate ipsilateral ganglia at Th15-L3 levels. The vast majority of retrogradely traced neurons (virtually all motoneurons, approximately 76% of sensory and 99.4% of sympathetic chain ganglia neurons) was found at the L1 and L2 levels. The morphometric evaluation of FB-labeled DRG neurons showed that the majority of them (approximately 66%) belonged to the class of small-diameter perikarya (10-30 microm in diameter), whereas those of medium size (30-80 microm in diameter) and of large diameter (more than 80 microm) constituted 22.6% and 11.5% of all DRG neurons, respectively. The results of the present study demonstrated that the nerve terminals supplying porcine LDM originated from different levels of the spinal cord, dorsal root and sympathetic chain ganglia. Thus, the study has revealed sources and morphological characteristic of somatic, autonomic and spinal afferent neurons supplying porcine LDM, simultaneously pointing out the characteristic features of their distribution pattern.     

Consequences of neural tube and notochord excision on the development of the peripheral nervous system in the chick embryo

Notochordectomy and neuralectomy were carried out either in one- or in two-step experiments on the chick embryo. The aim of this operation was to study the influence of the axial organs (notochord and neural tube) on the development of the ganglia of the peripheral nervous system. The neural crest cells from which most peripheral ganglion cells arise were labeled through the quail-chick marker system and their fate was followed under various experimental conditions. It appeared that the development of the dorsal root and sympathetic ganglia depends on survival and differentiation of somite-derived structures. In the absence of neural tube and notochord, somitic cells die rapidly, and so do the neural crest cells that are present in the somitic mesenchyme at that time. In contrast, those crest cells which can reach the mesenchymal wall of the aorta, the suprarenal glands, or the gut survive and develop normally into nerve and paraganglion cells. Differentiation of the neural crest- and placode-derived sensory ganglia of the head which develop in the cephalic mesenchyme is not affected by removal of notochord and encephalic vesicles. These results show that the peripheral ganglia are differentially sensitive to the presence of the neural tube and the notochord. Among the various ganglia of the peripheral nervous system, spinal and sympathetic ganglia are the only ones which require the presence of these axial structures. The neural tube allows both the spinal and the sympathetic ganglia to develop in the absence of the notochord. In contrast, if the notochord is left in situ and the neural tube removed, the spinal ganglia fail to differentiate and only sympathetic ganglia can develop.     

树鼩实验感染基孔肯雅病毒的研究

选用3株基孔肯雅病毒人工感染成年树鼩,进行了病毒血症、抗体动态变化、内脏组织病理改变和病毒在宿主体内定位的研究。结果表明,感染树鼩能产生2～6天的病毒血症。血凝抑制(Hi)抗体第6天产生,第30～50天达高峰:中和(NT)抗体在第10天产生,第30～40天达高峰,二者相关性非常显著(P<0.01)。补体结合(CF)抗体第14天产生,第40～50天为高峰,以后逐渐下降。第8～12天能在其脑、肺、肝、脾和肾等组织查到病毒,经病理检查这些内脏组织呈炎性改变和出血倾向,表明该病毒能侵袭树鼩各主要脏器。试验认为树鼩对基孔肯雅病毒敏感。     

SEPARATION OF APPARENT MULTIPLE FORMS OF HUMAN BRAIN CHOLINE ACETYLTRANSFERASE BY ISOELECTRIC FOCUSING

Abstract— Choline acetyltransferase (acetyl-CoA: choline O -acetyl transferase; EC 2.3.1.6; ChAc) purified from human brain (basal ganglia) and sciatic nerve were separated into apparent multiple enzyme forms by the method of isoelectric focusing (pH gradient 3-10) on acrylamide gel. A preparative separation of enzyme forms of human brain was accomplished by the column method, by using a sucrose gradient. When each separated form was re-electrofocused, only a portion of the ChAc activity was observed in its original pH region while more than one-half of the recovered activity for each fraction appeared at pH 7.8-8. Gel filtration and kinetic studies of separated forms indicated that the more acidic forms might be aggregates, while more basic forms might be configurational isomers. Human ChAc of sciatic nerve did not exhibit acidic forms on electrofocusing, but otherwise yielded an electrofocusing profile similar to that of human brain. ChAc of rabbit brain and sciatic nerve each exhibited only a single form at pH 7.1 ± 0.2. Although ChAc differs among species, the enzyme of brain and sciatic nerve of the same species cannot be clearly distinguished by electrofocusing.