Acetazolamide inhibits the recovery from triethyl tin intoxication: Putative role of carbonic anhydrase in dehydration of central myelin

The vacuolar degeneration of central myelin was produced in Sprague-Dawley rats by oral administration of triethyl tin. The wet weight of brain stems which seems to reflect the degree of accumulation of water increased during the administration of the toxin, whereas the activity of 2, 3-cyclic nucleotide 3-phosphodiesterase altered less remarkably. When TET was withdrawn from the drinking water, the rats showed a dramatic clinical improvement along with reduction in wet weight of brain stems. Treatment with acetazolamide following TET inhibited the clinical improvement and reduction in wet weight of brain stems. The present results indicates that central myelin has plasticity in recovering from the vacuolar degeneration by removing the accumulated fluid and carbonic anhydrase is possibly involved in the dehydration, of myelin in such a recovery phase.     

Division and gametophytic tissue formation from protoplasts of young sporophytes in fern Lygodium japonicum

Protoplasts isolated enzymatically from juvenile leaflets of sporophytes in fern Lyqodium japonicum were inoculated in a MS medium containing NAA 2.7 m, BAP 2.2 m, 0.6 M mannitol, and 0.05 M sucrose. Cell division took place within 8 days of culture initiation, and after 30 days cell-clusters with 10–15 cells were observed. When the cell-clusters were transferred into fresh hormone-free medium containing no mannitol, they developed rhizoids and protonema-like regenerants. About 2 months later, cordate prothallia developed bearing both antheridia and archegonia.Abbreviations MS Murashige and Skoog (1962) - NAA naphthalene acetic acid - BAP 6-benzylaminopurine     

Growth analysis ofQuercus serrata seedlings withinMiscanthus sinensis grass canopies differing in light availability

The effects of different light regimes on the survival, growth and morphology ofQuercus serrata seedlings were studied in canopies ofMiscanthus sinensis. The seedlings of various ages (0–3 yr) were grown in three light regimes: under a denseM. sinensis canopy (TG plot) receiving 2.5%–8.7% of full sunlight, under a relatively sparse canopy (SG plot) receiving 3.8%–16.1% of light and in an adjacent open site (NG plot). There was a little difference in the survival ofQ. serrata seedlings among the three plots. Height and diameter of stem and total leaf area of the seedlings were significantly lower in the shadier plots. However, the first (bottom) flush of the stem was significantly longer in the TG plot than in the NG and SG plots. Total dry weights of individual 1- and 2-yr-oldQ. serrata seedlings in the TG plot were reduced to about one-twelfth of those in the NG plot. Although the relative proportion in dry weight of each organ did not differ significantly among the plots, leaf area ratio, specific leaf area and stem height per unit dry weight were significantly higher in shadier plots. The leaf area per unit stem height was increased considerably in the sunnier plots.     

Types,rates, origin and expressivity of chromosome mutations involving 13q14 in retinoblastoma patients

Summary A cytogenetic survey of 200 retinoblastoma (Rb) patients revealed that approximately 8.5% of the fresh germinal mutations were microscopically detectable chromosome mutations, either interstitial deletions or rearrangements, involving 13q14. They showed a strong bias toward paternal origin, indicating a significant contribution of errors in paternal meiotic processes. The incidence of patients with Rb due to such chromosome mutations was estimated to be 1.9 x 10^-6 of live births. Age-specific incidence of Rb tumors suggested that the Rb mutations by such chromosomal mechanisms had a lower carcinogenic potential, as indicated by the later onset of disease, than other Rb mutations of germinal origin.     

Electron microscopic observations on the formation of elastic fibres in cultures of aortic medial cells and adventitial cells

The formation of elastic fibres was observed in the cultured cells derived from the tunica media and the tunica adventitia of mouse aorta. Bundles of myofilaments with dense bodies were abundantly observed in the cytoplasm of the cultured medial cells, and numerous bundles of microfibrillar components were present in the intercellular spaces. Fine granules of approximately 50 nm in diameter were observed in the bundles of microfibrillar components. It was supposed that these fine granules of elastin fused with each other and formed elastic aggregates and then formed large elastic clumps. Numerous bundles of microfibrillar components were also present in the intercellular spaces of the cultured adventitial cells. Elastic aggregates were scarcely observed in the bundles of microfibrillar components. However, large elastic clumps as observed in the medial cell culture could not be found in the adventitial cell culture. It is suggested that the formation of large elastic clumps might be related to the sheet structures or lamellae of elastic fibres in the tunica media.     

Analgesia and plasma beta-endorphin-like immunoactivity in compound 48/80-induced hypovolemia of the rats

The effects of subcutaneous (s.c.) administration of compound 48/80 (a well known histamine liberator) on latency to thermoalgesic stimulus, hematocrit (Hct) and plasma levels of beta-endorphin-like immunoreactivity (beta-END-LI) were investigated in male rats. The s.c. administration of compound 48/80 in doses ranging from 0.5 to 5.0 mg/kg into the rats produced significant analgesia in the hot plate test and increased Hct in a dose-dependent manner. Concomitant variation was observed between the analgesia and the increase of Hct. This analgesic effect, but not the increase of Hct, was diminished by pretreatment with the opiate receptor antagonist, naloxone (5 mg/kg, s.c.). A significant increase of plasma beta-END-LI was observed by s.c. injection of compound 48/80. Together with a previous finding that compound 48/80 induced-hypovolemia increases the renin release from kidney and then causes water intake in the rats, it is suggested that s.c. administration of compound 48/80 induced analgesia mediated through stimulation of an opioid system, may be closely related to stimulation of the renin-angiotensin system.     

Levels of IAA, Cytokinins, ABA and Ethylene in Rice Plants as Affected by a Gibberellin Biosynthesis Inhibitor, Uniconazole-P.

Effects of uniconazole-P, a triazole-type growth retardant,on endogenous levels of IAA, cytokinins, ABA and ethylene inrice seedlings were investigated. Endogenous levels of IAA andABA were similar between control and uniconazole-P-treated riceshoots. Evolution of ethylene was promoted slightly, being 1.8times greater under 0.3 ppm uniconazole-P treatment than thatof control. The most obvious effect was the increase of trans-Zand trans-RZ in shoots. Shoots treated with uniconazole-P (10mg/m² nursery box) contained 3.4 times and 3 times more trans-Zand trans-RZ than control, respectively. No significant differencesof cytokinin levels were recognized in roots except for cis-RZ.The increase of ethylene and active forms of cytokinins, andthe decrease of gibberellin in the shoots may be the basis forphysiological phenomena caused by uniconazole-P, namely thepromotion of flowering in woody plants and the enhancement offemaleness in cucumber. (Received September 9, 1987; Accepted October 20, 1987)     

Temperature dependence of the structure of aggregates of tobacco mosaic virus protein at pH 7.2. Static synchrotron small-angle X-ray scattering

The small-angle X-ray scattering (SAXS) method using a synchrotron radiation source was applied to the study of the self-aggregation process of tobacco mosaic virus protein (TMVP) at a concentration of 5.0 or 12.0 mg ml-1 in 50 mM or 100 mM-phosphate buffer (ionic strengths approx. 0.1 and 0.2, respectively) at pH 7.2 in the temperature region of 4.8 to 25.0 degrees C. This paper presents the results of static measurements of SAXS. Sedimentation velocity experiments were performed simultaneously under the same conditions. These results are qualitatively parallel to those of the SAXS measurements, although the size of stacked disks derived from the SAXS measurements is larger than that derived from the sedimentation experiments, suggesting a change in the equilibrium conditions in the centrifugal field. Qualitative analysis of the SAXS data with model simulation calculations implies that the aggregation of TMVP consists of two steps: (1) the aggregation of A-protein comprising a few subunits to form double-layered disks; and (2) the random polymerization of double-layered disks by disk-stacking. Increase in temperature, ionic strength or protein concentration induced TMVP to polymerize to form a double-layered disk or a quadruple-layered short rod with consumption of A-proteins, accompanied by a small number of multi-layered short rods. The SAXS results indicate that the A-protein and the multilayered short rods are polydisperse with respect to size and shape, i.e. the mixture of A-protein, double-layered disks and multi-layered short rods coexists in the equilibrium state without pressure-induced partial dissociation of TMPV as observed during normal ultracentrifugation, and even under solution conditions in which the formation of double-layered disks or higher-order aggregates is favored.     

Effects of microsite light availability on the survival and growth of oak seedlings within a grassland

Effects of microsite light availability on the growth and survival of transplantedQuercus serrata Thunb. seedlings in aMiscanthus sinensis Anderss. grass canopy were investigated by a “plant's eye view” approach. Diffuse site factors, i.e., the fractional transmissions of diffuse photosynthetic photon flux density, were estimated at 15 cm aboveground in 108 microsites where the seedlings grew. Microsite diffuse site factors were significantly different between surviving and dead seedlings during the experiment period from April to October (F_[1,14]=10.9, P<0.01). Relative growth rate of dry weight for individual seedlings positively depended on the diffuse site factors (r²=0.482, P<0.001 in May; r²=0.312, P<0.001 in October). Only 16 seedlings produced their second stem flush within the grass canopy. The ratio of height to dry weight of the second stem flush was significantly higher for the seedlings grew in shady microsites than for those in less shady microsites (r²=0,471, P<0.01 in May). This study suggests that the microsite heterogeneity of light availability is one of the important factors affecting the establishment of tree seedlings in patchy grasslands.