INTERNALIZATION OF GAP JUNCTIONS BETWEEN NEURON AND GLIAL CELL AND FORMATION OF ANNULAR LAMELLAR BODIES IN CHINESE LEECH Whitmania pigra

This paper reveals the formation of annular lamellar body (ALB) in the ganglion of leech by means of in situ fixation and the lanthanum nitrate tracer technique. This formation involves both wrapping and internalization of the gap junctions between glial processes themselves, as well as between neuron and glial process. The results indicate that there is probably an active process of internalization of membrane structures involving gap junctions between neuron and glial cell in the central nervous system in leech. The functions of ALB are discussed.     

THE PROJECTION LINKAGE BETWEEN THE SPINAL DORSAL HORN NEURONS AND BOTH THE SOLITARY TRACT AND DORSAL COLUMN NUCLEI

Electrical stimulation of the solitary tract nucleus (SN) and dorsal column nuclei (DCN)as well as microelectrode recording from the lumbal spinal dorsal horn have been used tofind and identify the axonal projection of and the afferent innervation on the spinal neuronsof pentobarbital- anesthetized rats. A total of 92 neurons was recorded and identified mainly in laminae Ⅲ-Ⅴ of the lumbarspinal dorsal horn. Of them, 38 neurons were activated antidromically from stimulation ofboth the SN and DCN. The other 54 neurons responded synaptically to both the SN andDCN stimulations. The initial antidromic responses of 8 neurons in the first group werefollowed by one or more responses synaptically driven from the SN and/or DCN stimulation.Conduction velocities were in the range of A delta fibers, but faster in the antidromicresponses and slower in the synaptic responses. These results indicate that (i) some spinal neurons issue branched axons of larger-sizedA delta fibers and double project to both the SN and D     

THE PROPERTY OF PERIPHERAL INPUT OF PROJECTION NEURONS IN THE SPINAL CORD DORSAL HORN

Antidromic and orthodromic responses of the projection neurons in the dorsal horn ofthe spinal cord have been recorded by a glass microelectrode in anesthetized and paralyz-ed cats. Furthermore, the effect of cervical segment antidromic stimulation to orthodromicresponse of the projection neurons has been observed by way of conditioning-test stimulation. Among all the spinocervical tract neurons (SCT), the dorsal column postsynaptic neu-rons (DCPS) and the spinocervical tract-dorsal column postsynaptic neurons (SCT-DCPS),which were identified by cervical segment antidromic stimulation, 46% are low-thresholdmechanoreceptive (LTM) and 54% are wide-dynamic-range (WDR) neurons. Most LTMneurons can evoke the same response to both 10 times (10 T) and 50 times (50 T) the thresh-old stimulation on the peroneal nerve. Most WDR neurons to 50 T intensity stimulation arestronger than the 10 T stimulation. Under the antidromic-cervical segment conditioningstimulation, the amount of orthodromic-discharging in most WD     

THE ATTACHMENTS OF PHYCOBILINS TO CYSTEINYL RESIDUES

The attachments of phycobilins to cysteinyl residues have been worked out through the reactions of phycoerytbrobilin dimethyl ester and phycocyanobilin dimethyl ester with cysteine methyl ester and reduced glutathione dimethyl ester respectively. A series of model compounds which carry the same conjugative skeletons as the chromophores in phycobillproteins have been purified anti identified. These compounds are characterized with strong fluorescence emission and circular dichroism effects which appeared weaker for the common bilinoid chromophores. Analyses of the circular dichroism effects of these compounds indicated that the major reaction products of phycobilins with cysteine methyl ester and reduced glutathione dimethyl ester carried the same stereochemical configuration as the chromophores in phvcobilinoroteins     

THE PARAMETER KERNELS FOR THE LINEAR INVERSION OF THE FREE OSCILLATION OF THE EARTH (Ⅰ)

In the linear inversion of the radial variation of the parameters of the Earth by usingthe observed frequencies of various normal modes of free oscillation of the earth, it is neces-sary to know the values of the kernels of the parameters ρ, μ and λ. This paper describesthe methods of the derivation of the formulas of these kernels. This is the first part of thepaper in which only the toroidal oscillations are considered. They are much simpler thanthose of the spheroidal ones, that we will consider in the second part of the paper. The data of the two types of oscillations are equally important in the solution of theinversion problem, and should be employed simultaneously, and we know that the toroidaloscillations are much simpler than the spheroidal ones, it seems wise to divide the whole programof the inversion problem into steps: first, by employing the toroidal data to correct the twoparameters ρ and μ in the mantle, then by using the spheroidal data to correct the remain-ing parameters, i.e. th     

THE EVOLUTION OF MODERN OYSTER BIOHERMS AND THE ECOLOGICAL CHARACTER AND THE PALEOEN-VIRONMENTAL SIGNIFICANCE

In this paper, the morphology, sedimentary structure, bioherm--building mollusk assem-blages and their growing and piling-up models of modern oyster bioherms in the estuariesof the Zimaigou and Xiaoqing Rivers are described and expounded, the environmentalconditions for the development of oyster bioherms, such as the dynamical geomorphicbackground, water depth, hydrodynamic factors and ecological conditions in the estuaries,are analyzed, the relationship of the successively seaward migrating of oyster biohermswith average annual sea-level changes and the erosion--accretion processes in the estuariesare probed and explained, and the geological significance of oyster bioherms in the studyof Quaternary marine environmental evolution is presented.     

ISOLATION AND CHARACTERIZATION OF THE SPECIFIC PEPTIDES FROM RABBIT BLASTOCYST AT PERI-IMPLANTATION STAGE WITH EMPHASIS ON THEIR PHYSIOLOGICAL SIGNIFICANCE RELEVANT TO THE MECHANISM OF IMPLANTATION

The secrctory materials from the uterine flushings of the pregnant, non-pregnant and pseudopreg-nant rabbits were analysed by the method of SDS-polyacrylamide gel electrophoresis. The results demon-strated that there are three specific peptides in the pregnant uterine flushings with molecular weightsof 3000, 4500 and 6000. No correspondent peptides were found in non-pregnant and pseudopregnantuterine flushings. The peptides were also isolated and identified from the blastocystic fluid. At least 4peaks of small peptides were shown by high pressure liquid chromatography. The range of their isoelec-trophoretic points is between pH 4.0-5.5 Concavalin A (Con A) affinitive electrophoresis indicated thatthey are glycopeptides in nature. The LH-RH A is able to exert inhibitory effects on the synthesis ofthese peptides. Their possible physiological function has been discussed.     

HEAT FLOW ON THE QINGHAI-XIZANG(TIBETAN) PLATEAU AND THE MODELING OF THE TECTONO-THERMAL EVOLUTION

Thirteen observed heat flow values in combination with relevant geological and geophysical information are employed in the current paper to conduct a model study by means of direct inversion. The modeling demonstrates the tectono-thermal evolution of the Tibetan Plateau during the last 40 Ma since the continent-continent collision. The authors stress the fact that the tectonic deformations of terranes are usually the inducing factors for the deep-seated thermal activities in the crust and upper mantle. On this basis a series of kinematic equations of 3-D deformations of terranes in forms of shortening-thickening-uplifting-erosion-mass sliding were deduced using the principle of plate kinematics. These equations are further used as systematically defined initial and boundary conditions for simulating the integrated processes of tectono-thermal evolution, The results of the model study suggest that there exist sharp differences in the tectono-thermal evolution between the old northern terranes and the new     

THE CATALYTIC EFFECTS OF OXYGEN AND AMINES IN THE REDOX-INITIATED DIMERIZATION OF N-VINYLCARBAZOLE*

The redox reaction between N-vinylcarbazole (NVC) and various oxidants including Ce(Ⅳ), Fe(Ⅲ)and benzoylperoxide in methanol proceeds via the initial formation of the NVC N-cation radical which in turn leads to the formation of the NVC cyclic dimer, trans-1,2-dicarbazylcyclobutane. Molecular oxygen and a few arylamines are able to accelerate the rate of the formation and increase the yield of the dimer. The mechanism of this process and the functions of oxygen and arylamines are presented as follows: The participation of molecular oxygen is to facilitate the dissociation of the resulting reduced metal ion and the NVC N-cation radical ion pair or charge transfer complex, thereby releasing the free NVC N-cation radical and increase the rate of the formation and yield of the dimer. The arylamine in this reaction between NVC and oxidants can be viewed as electron transfer agent between NVC and the oxidant. Because the amines are present in small amount relative to the oxidants and can be regenerated in pr     

Orientational Recognition and Low-Resistance Passing (LRP) Regulation of Segmental Re-innervation by Central Neurons in Leeches

Re-innervation of sensory and motor neurons on a defined area of the body wall was studied in two species of leeches, Whitmania pigra and Hirudo medicinalis, as a model of segmental animals. Following isolation and rotation of a tube of body wall, the mechanical sensory and annular erection (AE) motor neurons re-innervated the body wall, at a rate of approximately 3. 8 -8. 4 μm/h. The patterns of re-innerva-tion by pairs of neurons on each side of a ganglion were bilaterally symmetric. The repairs are synchronous for the sensory and motor neurons which are of different functions but in a same ganglion. The gap junctions are widely spread in leech between neurons and glia cells, as well as among the neurons and glia cells themselves. Therefore, it is proposed that the nervous system repair is regulated by a low-resistance pathway. In the xenotransplantation experiments, neurons recognized target tissues before the immuno-recognition and rejection.     

Internalization of gap junctions between neuron and glial cell and formation of annular lamellar bodies in Chinese leech Whitmania pigra

This paper reveals the formation of annular lamellar body (ALB) in the ganglion of leech by means of in situ fixation and the lanthanum nitrate tracer technique. This formation involves both wrapping and internalization of the gap junctions between glial processes themselves, as well as between neuron and glial process. The results indicate that there is probably an active process of internalization of membrane structures involving gap junctions between neuron and glial cell in the central nervous system in leech. The functions of ALB are discussed.     

Purification and characterization of hementin, a fibrinogenolytic protease from the leech Haementeria ghilianii

The fibrinogenolytic enzyme hementin, present in extracts of the posterior salivary glands of the giant leech Haementeria ghilianii, was isolated by ultrafiltration, high-performance ion-exchange chromatography and subsequent reversed-phase liquid chromatography. Approximately 100 micrograms (1 nmol) of hementin, present at less than 0.5% in the crude leech salivary extract, was brought to about 90% purity in three steps. Hementin migrated at an Mr of about 73,000 on non-reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and at 82,000 on reducing SDS-PAGE. The amino terminal sequence was determined to be TTLTE-PEPDL. The amino terminal sequences of two inactive proteins that partially coeluted with hementin in the first chromatographic step were also determined.     

Effect of O-glycosylation and tyrosine sulfation of leech-derived peptides on binding and inhibitory activity against thrombin

Synthesis of sulfated and unsulfated (glyco)peptide fragments of Hirudin P6 (a potent anticoagulant from the leech Hirudinaria manillensis) is described. The effect of O-glycosylation and tyrosine sulfation on thrombin binding and peptidolytic activity was investigated, together with the inhibition of fibrinogen cleavage.     

A new strategy for neurochemical photodelivery: metal-ligand heterolytic cleavage

A new strategy to build caged-compounds is presented. The approach is based on heterolytic photocleavage of a metal-ligand bond in a coordination compound. A ruthenium polypyridine complex, containing the neurocompound 4-amino pyridine (4AP) is used as the core of the phototrigger. The biomolecule is released by irradiation with visible light (>480 nm). The liberated 4AP promotes the activation of a leech neuron by means of blocking its K+ channels. The syntesis, characterization, and the inherent advantages of this method are discussed.     

Enzymatic synthesis of 7-deoxy-N-acetylneuraminic acid and 7-O-methyl-N-acetylneuraminic acid

7-Deoxy-N-acetylneuraminic Acid and 7-O-methyl-N-acetylneuraminic acid were synthesized through the sialic acid aldolase-catalyzed aldol addition reactions of 4-deoxy-N-acetyl-D-mannosamine and 4-O-methyl-N-acetyl-D-mannosamine, respectively, with pyruvate. The obtained sialic acids will be used as probes for the investigation of the unusual mechanism of a novel sialidase from leech.     

Development and validation of a stability-indicating method for determination of free sterols in the Asian medicinal leech Hirudo manillensis

A rapid, simple, sensitive, selective, precise and robust thin-layer chromatography densitometric method for the determination of free sterols in leech was developed and validated on silica gel layer using carbon tetrachloride-methanol-formic acid (9.5:1.5:0.55, v/v/v). Spectrodensitometric scanning was carried using a Camag TLC scanner III at 366 nm after spraying 2% methanolic sulphuric acid, which gave compact spots for cholesterol (R(F) = 0.35 ± 0.02). The regression analysis data for calibration plot implied a good linear relationship (r(2) = 0.99958) between response and concentration over the range 100-600 ng per spot with respect to peak area. The limits of detection and quantification were found to be 13.8 ± 0.51 and 45.01 ± 1.29 ng per spot, respectively. Validation was in accordance to the International Conference on Harmonization guidelines. Cholesterol was subjected to forced stress conditions of oxidation, hydrolysis and heat. Degradation products resulting from the forced stress did not interfere with detection because the degradant peaks were well separated from the cholesterol peak. The densitometric method can be regarded as stability-indicating and can be used for quality control assay of cholesterol in leech extract.     

Total Synthesis of Homogeneous Variants of Hirudin P6: A Post‐Translationally Modified Anti‐Thrombotic Leech‐Derived Protein

Hirudin P6 is a leech‐derived anti‐thrombotic protein which possesses two post‐translational modifications, O‐glycosylation and tyrosine sulfation. In this study we report the ligation‐based synthesis of a library of hirudin P6 proteins possessing homogeneous glycosylation and sulfation modifications. The nature of the modifications incorporated was shown to have a drastic effect on inhibition against both the fibrinogenolytic and amidolytic activities of thrombin and thus highlights a potential means for attenuating the biological activity of the protein.     

Visualization of Intra‐neuronal Motor Protein Transport through Upconversion Microscopy

Cargo transport along axons, a physiological process mediated by motor proteins, is essential for neuronal function and survival. A current limitation in the study of axonal transport is the lack of a robust imaging technique with a high spatiotemporal resolution to visualize and quantify the movement of motor proteins in real‐time and in different depth planes. Herein, we present a dynamic imaging technique that fully exploits the characteristics of upconversion nanoparticles. This technique can be used as a microscopic probe for the quantitative in situ tracking of retrograde transport neurons with single‐particle resolution in multilayered cultures. This study may provide a powerful tool to reveal dynamic neuronal activity and intra‐axonal transport function as well as any associated neurodegenerative diseases resulting from mutation or impairment in the axonal transport machinery.