秦岭细鳞鲑代谢及低氧耐受能力对温度驯化的响应

为考察秦岭细鳞鲑（Brachymystax lenok tsinlingensis）代谢及低氧耐受能力对温度驯化的响应,将实验鱼于6℃、12℃和18℃下驯化4周后,采用密闭式呼吸代谢测定仪对其静止代谢率（Resting metabolic rate,RMR）和临界氧压（Critical oxygen press,P_crit）等参数进行测定。结果发现,RMR随驯化温度升高而升高,在6-12℃、12-18℃温度内,RMR的Q₁₀值分别为2.59和2.77,表明该物种对温度的敏感性较高;P_crit值随驯化温度升高而升高且与RMR显著正相关,在驯化温度范围内（6-18℃）,P_crit提升了76.2%。研究结果提示:秦岭细鳞鲑应对低氧环境的生理可塑性较差,在高温下RMR增加可能是导致其低氧耐受能力降低的内在机制之一。     

THE SPECIFICITY AND SULFHYDRYL SENSITIVITY OF THE INOSITOL TRANSPORT SYSTEM OF THE CENTRAL NERVOUS SYSTEM

Abstract— The transport of two cyclohexitol stereoisomers, myo-inositol (inositol) and scyllo-inositol (scyllitol), from blood into the CNS in vivo and into the choroid plexus in vitro was studied. In vitro , the uptake of [³H]scyllitol or [³H]inositol by choroid plexuses, isolated from rabbits and incubated in artificial CSF, was measured. Both scyllitol and inositol inhibited [³H]scyllitol or [³H]inositol accumulation by the choroid plexus. Inositol competitively inhibited [³H]scyllitol accumulation and both isomers had a comparable affinity (K_t= 0.1 m m ) for the single cyclohexitol accumulation system. The other 6 stereoisomers tested had an order of magnitude less affinity for the cyclohexitol accumulation system of choroid plexus. Thiol reagents that penetrate cells inhibited inositol accumulation by choroid plexus more effectively than nonpenetrating thiol reagents. In vivo , in unanesthetized rabbits. the transport of unmetabolized [³H]inositol from blood into CSF, choroid plexus and brain was readily saturated by increasing the plasma levels of myo-inositol but not by the stereoisomer d -chiroinositol. Similarly, the transport of unmetabolized [³H]scyllitol into CSF, brain and choroid plexus was readily saturated by increasing the plasma levels of myo-inositol. Beside documenting the stereospecificity and thiol reagent sensitivity of the inositol transport mechanism of the choroid plexus, these results provide further evidence that the choroid plexus is a locus for cyclohexitol transport between blood and CSF. Moreover, they show that scyllitol, which, like inositol, is present at a higher concentration in brain than plasma, can be transported from blood into CSF and brain by the same system that transports inositol.     

THE NEUROENDOCRINE SYSTEM AND STOMATOGASTRIC NERVOUS SYSTEM OF THE ADULT TSETSE FLY GLOSSINA MORSITANS

The brain of Glossina morsitans Westwood contains four groups of neurosecretory cells which are stainable with chrome haematozylin and phloxin. The axons of these cells form a pair of nervi corporis cardiaci which pass posteriorly from the brain and innervate the corpora cardiaca and corpus allatum before uniting with a small ganglion posterior to the corpora cardiaca. This ganglion is considered to represent the fusion of the fusion of the hypocerebral and ventricular ganglia which remain separate in other insects.
There is no frontal ganglion in the adult Glossina and the recurrent nerve fuses with one of the nervi corporis cardiaci immediately behind the brain. The oesophageal nerves arising from the fused hypocerebral and ventricular ganglia innervate the oesophagus in the anterior part of the thorax, the proventriculus and the posterior extension of the oesophagus close to the crop. These nerves possess both sensory and motor nerve endings. The differences which exist between Glossina and other cyclorrhaphous Diptera with respect to their neuroendocrine/stomatogastric system are noted and considered in terms of the control of neuroendocrine function.     

PYRIDOXINE DEFICIENCY AND DEVELOPMENT OF THE CENTRAL NERVOUS SYSTEM IN THE RAT

Pyridoxine (vitamin B₆) deficiency was produced in rats during the period of development of the central nervous system. The levels of pyridoxal phosphate and y-amino-butyric acid in whole brains of these rats were determined, together with the activities of glutamate decarboxylase (EC 4.1.1.15) and γ-aminobutyrate aminotransferase (EC 2.6.1.19). The lowered contents of pyridoxal phosphate and γ-aminobutyrate in the brains confirmed the existence of pyridoxine deficiency. The activity of the glutamate decarboxylase holo-enzyme was decreased, whereas the activity of the apoenzyme was increased. However, there appeared to be no difference in the activity of γ-aminobutyrate aminotransferase. Concomitantly, some electrophysiological parameters, such as EEG and auditory evoked potentials, were analysed. The EEG of pyridoxine-deficient animals showed spike activity, presumably indicative of the existence of seizures in many of the deficient rats. Evoked potentials presented abnormalities in their latency, wave form and response to repetitive stimuli, but the extent to which they were affected depended upon the intensity of the deficiency.     

SYNAPSES IN THE CENTRAL NERVOUS SYSTEM

A number of different synapses have been described in the medulla, cerebellar cortex, and cerebral cortex of the rat. All of these possess the same fundamental fine structure as follows: 1. Close apposition of the limiting membranes of presynaptic and postsynaptic cells without any protoplasmic continuity across the synapse. The two apposed membranes are separated by a cleft about 200 A wide, and display localized regions of thickening and increased density. 2. The presynaptic expansion of the axon, the end-foot or bouton terminal, contains a collection of mitochondria and clusters of small vesicles about 200 to 650 A in diameter. Although the significance of these structures in the physiology of the synapse is still unknown, two suggestions are made: that the mitochondria, by means of the relation between their enzymatic activity and ion transport, participate in the electrical phenomena about the synapse; and that the small synaptic vesicles provide the morphological representation of the prejunctional, subcellular units of neurohumoral discharge at the synapse demanded by physiological evidence.     

THE CERIANTHAR1AN NERVOUS SYSTEM

Evidence supporting the presence of nerve cells in the columnand tentacles of Pacliycerianthiis is described. G. F. Gwilliamhas shown that electrical stimuli can be transmitted to theectodermal muscle by the intact epithelium and subepithelialnetwork of the ectoderm of the column. In these preparationsthe ectodermal muscle, mesogloea, and endoderm were cut. Incontrast, preparations in which the ectodermal muscle has beenleft intact and the epithelium and subepithelial network cutdo not show such transmission. The author and Gwilliam have independently used different silverstain methods to demonstrate large cells, piobably nerve cells,with cell bodies in the base of the epithelium and with fibersrunning into the subepithelial network. The author has foundsimilar bipolar cells in the tentacles and column by using macerationtechniques. These cells are compared with other cell types foundin the tentacles.     

ERGOTHIONEINE IN THE CENTRAL NERVOUS SYSTEM

Abstract— Further investigations have been made into ergothioneine in the brains of several mammalian species, and the distribution of ergothioneine in the brain of the ox is described. It has not been possible to confirm many of the findings of earlier workers and the results do not appear to support their conclusion that ergothioneine is identical with the cerebellar factor.     

DISTRIBUTION OF SERUM PROTEINS AND BETA-TRACE PROTEIN WITHIN THE NERVOUS SYSTEM

Abstract— The concentration of beta-trace protein, a low molecular weight water-soluble protein, was significantly higher in cerebral and cerebellar white matter than in grey matter. A similar distribution was found for transferrin. The concentrations of gamma-trace protein and pre-albumin were almost constant in cerebral and cerebellar white and grey matter. A different distribution was shown for albumin, beta_lc/beta_lA globulins, and the immunoglobulins G, A and M, with the highest concentrations mostly encountered in the highly vascularized basal ganglia and grey matter, and the lowest concentrations in white matter. Thus, different parameters, hitherto unknown determine the distribution within the central nervous system of various proteins-those which originate from serum, and beta-trace protein which originates mainly from the central nervous system.
The amounts of the different proteins were higher in the choroid plexus than in brain tissue, with the exception of gamma-trace protein.
Foetal brains contained increasing concentrations of beta-trace protein and of transferrin with age.
Femoral nerve contained lower concentrations of beta-trace protein and gamma-trace protein, and higher concentrations of the other proteins, than the central nervous system.