Inhibition of an abdominal proprioceptive reflex in crayfish

Summary Stimulation of the tonic muscle receptor organs inProcambarus clarkii results in reflex activation of the superficial extensors. This pathway is inhibited by activity in the lateral giant fibers and both medial giants. A labile synapse in the same pathway works synergistically with the giant fiber-mediated inhibition to prevent maladaptive activation of the superficial extensors during escape behavior. Evidence did not support the notion of giant fiber-mediated peripheral inhibition (via the accessory nerve) of MRO activity.This work was supported by NIH grant NS 02944 (to D. Kennedy). I would like to thank Drs. Kennedy, Wine, and the members of the Kennedy laboratory for their help and support.     

Strategy in drug reseabch. Synthesis and study of the psogestational and ovulation inhibitory activity of a series of 11β-substituted-17α-ethynyl-4-estren-17β-ols

Using the strategy based on the Hansch method which analyses effects of substituents on biological activity in terms of their hydrophobic, electronic and steric effects we selectively synthesised a series of 11β-substituted-17α-ethynyl-4-estren-17β-ols that combine ease of synthesis with good discrimination between these factors aiming at finding the compounds with optimum biological activity in that series. The compounds were tested quantitatively in the Clauberg test (rabbit) and the ovulation inhibition test (rat). The differences in biological activity could reasonably be correlated with two steric effects introduced by the 11β-substituent. These were a change in the overall shape of the 11β-substituent and the angular methyl group, and direct steric hindrance of the steroid-receptor protein binding. Some exceptions were found possibly due to metabolic conversion of these compounds to the corresponding 11β-substituted-17α-ethynyl-l,5,5(10)-estratriene-5, 17β-diols.     

Alkaloids of Papaver bracteatum: 14-β-hydroxycodeinone, 14-β-hydroxycodeine and N-methylcorydaldine

Three new alkaloids have been identified from Papaver bracteatum, 14-β-hydroxycodeinone, 14-β-hydroxycodeine and N-methylcorydaldine. The presence of alpinigenine was also confirmed.     

Effect of light treatment and endogenous growth hormones on {alpha}-and {beta}-amylase activities in cotyledons of Phaseolus vulgaris L.

The influence of light and endogenous plant-growth regulatorson the evolution of - and ß-amylases in cotyledonsof Phaseolus vulgaris L. was investigated. Both enzymes, whichare not present in ungerminated seeds, appear during germinationof intact seedlings or incubation of excised cotyledons. -Amylaseactivity decreases upon exposure to light. This inhibition iscorrelated with a drastic increase in chlorophyll content anda change in the endogenous gibberellin-inhibitor balance. ß-Amylaseactivity was not affected by light treatment but was by thepresence of endogenous cytokinins. (Received February 3, 1977; )     

Effect of ethylene on the endogenous cytokinin and gibberellin levels in tuberizing potatoes

High concentrations of 2-chloroethylphosphonic acid inhibited tuberization on aged potato tubers (Solanum tuberosum) that had been predisposed to the little tuber disorder. As a result of this treatment sprouts developed which contained relatively high levels of endogenous gibberellins and which elongated normally. The endogenous cytokinin levels in the different treatments did not change appreciably. It is suggested that tuberization is prevented by ethylene either as a direct inhibition of cell division or that it prevents the endogenous cytokinins from functioning. Irrespective of the mode of action of ethylene, cell division apparently is the primary process affected, the result being that storage tissue required for the accumulation of starch is not formed.     

A new type of cytocentrifuge,the valve-centrifuge

Summary A new type of cytocentrifuge has been developed in which the sedimentation process of the cells onto the slides is separated from the draining of the sedimentation fluid. This is realised by electrically controlled valves which can be closed and opened while the centrifuge is running. Sedimentation is carried out with closed valves, draining of adhering medium with open valves.The preparations, freed of adhering medium by the centrifugal force can be taken out and the cells can be fixed. Alternatively the valves can be closed again and fixative can be introduced through a central well, the cells still being under the influence of the centrifugal force. With subsequent draining of the fixative and introduction of washing and staining solutions through the central well, the whole process from sedimentation to staining can be carried out in the running centrifuge. The process seems well suited for complete automation.Using dilution series from a suspension of human buffy coat cells counted in a Buerker chamber, the cell counts in the centrifuge preparations showed virtually total recovery of cells, with no apparent selection or specific distribution of cell types. Draining of the sedimentation and fixative fluids at a slow rate was found to be vital for optimal recovery of cells. The morphology of different cell types sedimented on the slide was excellent. The flattening of nuclei through gravity was studied by cytophotometry of Feulgen-stained leucocytes. The nuclear area of these cells was found to be approximately double that from cells in identically stained classical smears. With this type of valve-centrifuge a quantitative and unbiased recovery of uniformly spread and flattened cells on coverslips or slides may be obtained, thus making the procedure well suited to automated analysis based on cytophotometric principles and morphometric pattern recognition.     

Evidence that thyroglobulin contains nonidentical half molecule subunits

Bovine thyroglobulin was extracted from unfrozen glands, purified by sucrose gradient centrifugation, and fractionated into a narrow range in iodine content by RbCl isopycnic centrifugation. The subunit composition of these preparations was studied by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The extent of dissociation of 19 S into 12 S half-molecules followed the known relationship with iodine, i.e. decreased dissociability of 19 S with increased iodine content. The undissociated 19 S band always consisted of three closely spaced, equidistant bands. Reduction of the disulfide bonds of thyroglobulin by mercaptoethanol in SDS solution resulted in the formation of two major and one minor components (S, F, and A). The concentration of A was always less than 10% of the total. The ratio of S to F was, however, about equal in thyroglobulin preparations which ranged in iodine content from 0.2 to 1%. The final ratios were obtained before all the disulfides were reduced. The relative mobilitis of S, F, and A, decreased with increasing extent of reduction. Fully reduced S and F, but not A, migrated slower than unreduced 12 S. The three reduced alkylated polypeptides were purified by preparative SDS-polyacrylamide gel electrophoresis and their molecular weights were determined by sedimentation equilibrium in 8 M urea. Their Mw and Mz values agreed closely with that of the unreduced 12 S half-molecule subunit, thus indicating that reduction of the disulfide bonds changes the shape but not the molecular weights of the subunits.     

Long-term survey data (1965-1972) on the occurrence of Anisakis larvae (Nematoda: Ascaridida) in herring, Clupea harengus L., from the North Sea

The occurrence of larval Anisakis in North Sea herring was examined during the period 1965-1972 using a sampling method which yielded comparable data for all eight years. Data on abundance of infestation in several herring stocks pointed to remarkable fluctuations over the study period with an increase in the period 1966-1968 followed by a decrease in the period 1968-1972. Of various hypotheses that may explain this situation, it is concluded that changes in the migration behaviour of the herring may be responsible. Other data and statistics are discussed with special reference to variations in infestation level in different samples and to the occurrence of adult nematodes in marine mammals.     

Increase in acid phosphatase activity in the fat body during larval and pharate pupal development in Calliphora erythrocephala

Biochemical evidence was obtained for an increase in acid phosphatase activity in the larval fat body of Calliphora erythrocephala during larval and pharate pupal instars. This observation is in conflict with published data indicating a decreasing enzyme activity in late third stage larvae. Centrifugation and filtration studies showed that the pH of the homogenisation medium has a strong influence on the solubilisation of acid phosphatase and its distribution in homogenate components. Differences in biochemical techniques including the pH value may explain the discrepancy between the published results and the present findings.The observed increase in acid phosphatase activity is related to the activity of the lysosomal system in the period immediately preceding pupal-adult apolysis.     

REGIONAL LEVELS OF GABA IN THE BRAIN: RAPID SEMIAUTOMATED ASSAY AND PREVENTION OF POSTMORTEM INCREASE BY 3-MERCAPTO-PROPIONIC ACID

Abstract— A simple and rapid semiautomated assay for GABA in central nervous tissue is described. The method is based on a simple manual procedure of isolating GABA from tissue extracts on small CM Sepharose Cl 6B columns, followed by an automated fluorimetric detection (continuous flow system) with o -phthalaldehyde (OPA) and β-mercapto-ethanol (β-ME) at an alkaline pH. GABA is separated from other compounds that fluoresce in our detection system. By using low concentration of OPA and β-ME and allowing only a short reaction time with these reagents, the detection is specific towards GABA. The detection limit of the assay is 1 nmol.
A procedure is described for the prevention of postmortem GABA increase in rat and mouse brain by intravenous injection of 3-mercapto-propionic acid (1.2 nmol/kg) 2min before decapitating the animal. This treatment and microwave irradiation result in similar GABA levels in mouse brain and substantia nigra tissue from rat brain. We found a great conformity in regional GABA levels in the rat and the mouse brain.