Comparative biochemistry and physiology. C, Comparative pharmacology and toxicology最新文献

1. Ten peptides that showed an inhibitory effect on phasic contraction of the ABRM of Mytilus were isolated from the ganglia of the African giant snail, Achatina fulica. 2. Seven of the peptides were shown to be hexapeptides having -Pro-Xaa-Phe-Val-NH2 as a common structure, which was previously shown to be a characteristic of Mytilus inhibitory peptides (MIPs). 3. The remaining three were pentadecapeptides, each of which consisted of two MIP-related hexapeptides linked by -Gly-Arg-Arg-.

1. Vestibuloocular reflex and optokinetic eye movement response are ocular reflexes conjointly subserving stability of retinal images. 2. These reflexes exhibit marked adaptability under sustained imposition of retinal errors. 3. Comparative studies in various vertebrate species reveal the importance of this adaptability as fundamental neural function based on plasticity of cerebellar synapses.

Myelin proteins in mammalian peripheral nerve were studied comparatively. 1. While each content of P1 and P2 in the myelin varied among species, additional content of P1 and P2 are relatively constant. 2. The antigenic determinants of P2 for induction of experimental allergic neuritis were reported. 3. Amino acid sequence analysis of P0 revealed that P0 is conserved across species and belongs to the immunoglobulin superfamily. 4. The characteristic carbohydrate chain of P0 containing sulfate and sialic acid showed a positive reaction to the molecule-related immunity and adhesion. 5. Molecular architecture of the myelin is discussed.

1. Studies on the central nervous system related to lens accommodation in cat and monkey were reviewed. 2. During the last decade, a considerable amount of neurophysiological data on the peripheral innervation of the ciliary muscle, properties of parasympathetic oculomotor neurons and mesencephalic reticular neurons have accumulated. 3. Neurophysiological and anatomical evidence supporting the contribution of the cerebellum to lens accommodation has been obtained. 4. Recently, cerebral cortical neurons in the parieto-occipital cortex with activities related to lens accommodation were found in cat and monkey.

1. The second-messengers system of bradykinin (BK) receptors was examined in NG108-15 neuroblastoma x glioma hybrid cells. 2. An application of BK induced an immediate outward (K+) current and acetylcholine (ACh) release, which are generated through inositol 1,4,5-trisphosphate (InsP3)-dependent Ca2+ ions. 3. Application of phorbol dibutyrate (a protein kinase C activator) produced a voltage-dependent inward current and inhibited another K+ (M)-current. 4. A similar current response has been produced by ACh in NG108-15 cells transfected with rodent muscarinic ACh receptor I and III subtype genes. 5. These results suggest a dual and time-dependent role for these two intracellular messengers in the control of neuronal signalling by BK and ACh.

1. Phebrol (sodium 2,5-dichloro-4-bromophenol), a synthetic molluscicide against Oncomelania nosophora, showed a dual effect on rat liver submitochondria, acting as an uncoupler at low concentrations (approximately 10 microM) and an inhibitor of succinate-cytochrome c reductase at high concentrations. 2. Phebrol also inhibited the enzymes responsible for succinate-fumarate conversion, i.e. the succinate-cytochrome c reductase, fumarate reductase and NADH-cytochrome c reductase of the mitochondrial fraction from Biomphalaria glabrata. 3. Kinetic inhibition studies showed succinate-cytochrome c reductase of B. glabrata and O. nosophora to be more sensitive than that of rat liver toward phebrol. 4. Phebrol accumulated in whole tissues of B. glabrata and O. nosophora and had significant effects on the production of succinate, fumarate and malate by these snails. 5. On the basis of these results, the possible sites of inhibition by phebrol of snail respiratory chains are proposed.

1. The bioconcentration factors (BCF) of both chemicals via gill intake of goldfish reached plateaux after 21 days of exposure. The average BCF values of Bu3SnCl and Ph3SnCl (N = 2) were 1976 and 1384, respectively, after 21-28 days of exposure. 2. The BCF values by oral intake of goldfish reached plateaux after 28 days for Bu3SnCl but did not for Ph3SnCl. The BCF values of Bu3SnCl and Ph3SnCl were 0.04 and 0.10, respectively, after 35 days. 3. The order of the BCF values via gill intake was reversed compared with that by oral intake. Further, the contamination of freshwater fish by these compounds was discussed using the results of these experiments.

1. Monoamine oxidase (MAO) activity in the brain and peripheral tissues of newborn ground squirrel, as well as its evolution during postnatal development were studied. 2. Monoamine oxidase activity in the brain stem and liver, at the day of birth is significantly higher (P less than 0.01; P less than 0.005) than in adults. 3. After that, enzyme activity decreases, but at the 25th day, e.g. at the day of the opening of the eyes, still remains significantly above the adult's value (P less than 0.01). 4. The results indicate some species specificity concerning the level and the evolution of cerebral and hepatic MAO activity as compared to the rats.

1. Myelin is an important structure for facilitating the conduction of impulses along the axons both in the central nervous system (CNS) and peripheral nervous system (PNS). 2. Myelin basic protein (MBP) is a major protein in CNS myelin. 3. MBP is expressed specifically in the nervous system. 4. The MBP gene has been cloned and characterized. 5. Two mutant mice, Shiverer (shi) and myelin-deficient (mld. shimid), are autosomal recessive mutants that show severe symptoms such as intentional tremor. They have been found to have a mutation in the MBP gene that results in poor myelination in the central nervous system. 6. It was found that rearrangement within the MBP gene results in low expression of the gene. 7. In Shiverer, the MBP gene is partially deleted (from exons 3 to 7), and in mld, the gene is duplicated tandemly and a large portion of the duplication is inverted upstream of the intact copy. 8. In mld, anti-sense RNA complementary to exons 3-7, which correspond to the inverted segment, was detected by RNase protection studies, and presumed to be responsible for the reduced expressions of MBP. 9. The mechanism of gene rearrangement in MBP was also characterized. 10. This article reviews the recent progress in the study of the MBP gene, especially the rearrangement of the gene and its expression in mutant mice.