Preparative thin-layer and column chromatography of prostaglandins

Chromatographic methods are used to identify various monounsaturated PGs (prostaglandins). TLC (thin-layer chromatography) and column chromatography are described in detail. These systems were developed specifically for separating epimers of PGE1 and PGF1, but they are useful in separating some of the known natural PGs as well. A table presents information on identification of the various PGs with neutral silica and acidic silica. The results of these laboratory experiments indicate that 1 ug-1g of PG can be purified by chromatographic methods with little or no loss due to irreversible adsorption or rearrangement if proper precautions and solvent systems are used. TLC seems to be useful in distinguishing diastereomers of PGs. Relative mobilities of the various hydroxy diastereomers are not changed by the solvent systems or by esterification.     

Electron microscopic observations on iron-labelled secondary lysosomes in renal tubules in mice

Summary Labelling of renal tubule cytosomes with electron dense iron granules can be attained by daily intramuscular injections to mice of an iron sorbitol citric-acid compound in a total of approximately 50 mg Fe⁺⁺⁺/100 g of body weight. The labelled cytosomes correspond to secondary lysosomes and represent heterolysosomes or ambilysosomes. The evidence suggests that tubule and lysosome function are undisturbed by the labelling procedure. The use of this method for fine structural studies of the interaction between secondary lysosomes and other cytoplasmic organelles and elements is indicated.Microbodies do not incorporate administered Fe⁺⁺⁺. The morphological observations support the opinion that these bodies are formed in specialized portions of the smooth surfaced endoplasmic reticulum of proximal tubule cells.Supported in part by grants from the Swedish Medical Research Council (Projects No. K 67-12x-1006-2, B 67-12x-1006-02K, K 68-12x-1006-03, and B 69-12x-1006-04A). The assistance of Miss Silwa Mengarelli and Miss Britt-Marie Pettersson is gratefully acknowledged.     

Application of a Theory for Circumnutations to Geotropic Movements

From a previously published theory (Israelsson and Johnsson 1967) for circumnutations in Helianthus annuus it is possible to predict the geotropical curvatures of the hypocotyls. This extension of the theory is given in the present paper and some geotropical experiments are performed and discussed. The agreement between the theory and the experiments has been verified in the case of gravitational stimulation during relatively short stimulation periods, in the case of continuous gravitational stimulation, etc. Restrictions in the proposed model are discussed.     

Adrenergic nerves in the pars intermedia of the pituitary in the toad,Bufo arenarum

Summary By means of a highly sensitive and specific histochemical method for the demonstration of certain biogenic monoamines a plexus of nerves containing a primary catecholamine has been demonstrated in the pars intermedia of the toad, Bufo arenarum. These nerves are restricted in distribution to the part of the gland which contains colloid vesicles (stored MSH ?) in the cells. The view is put forward, based on the results of pharmacological and surgical experiments, that the adrenergic nerves inhibit the release of the MSH from the pars intermedia. The origin of the nerves in the brain is unknown, but experiments with lesions have shown that it is not to be found in the nucleus periventricularis arcuatus.The research reported in this document has been sponsored by the Swedish Medical Research Council and by the Swedish Natural Science Research Council.Research fellow of the Commission of Scientific Research of the Province of Buenos Aires, Argentina.     

In Vivo Substitution of Choline for Sodium Evokes a Selective Osmoinsensitive Increase of Extracellular Taurine in the Rat Hippocampus

Recent investigations have demonstrated that taurine and phosphoethanolamine (PEA) are the amino acids most sensitive to microdialysis-perfusion with reduced concentrations of NaCl. The aim of the present work was to assess the importance of Na+ deficiency in evoking this response. Further, the previously described selectivity of replacement of Cl- with acetate with respect to amino acid release was reinvestigated. The hippocampus of urethane-anesthetized rats was dialyzed with Krebs-Ringer bicarbonate buffer, and amino acid concentrations of the perfusate were determined. Choline chloride was then stepwise substituted for NaCl, and, in some cases, mannitol (122 mM) was included in low sodium-containing media. In other experiments, NaCl was replaced with sodium acetate. The dialysate levels of taurine increased selectively in response to Na+ substitution. The elevation of taurine was linearly related to the increase in choline chloride, and maximal levels amounted to 335% of basal levels. The increase in extracellular taurine was not inhibited by perfusion with medium made hyperosmotic with mannitol. Replacement of Cl- with acetate stimulated the release of taurine to 652% of resting levels. In addition, PEA levels increased to 250% of control concentration. Other amino acids were unaffected by Cl- substitution. The results show that taurine transport is considerably more sensitive to Na+ depletion than glutamate transport, which also is known to be Na+ dependent. The taurine increase evoked by low Na+ is not caused by cellular swelling as it was unaffected by hyperosmolar medium. Finally, substitution of acetate for Cl- causes a specific elevation of extracellular taurine and PEA, possibly as a result of cytotoxic edema.     

Armaments and ornaments: an evolutionary explanation of traits of dual Utility

Secondary sexual characters in many species function both in male-male competition and as cues for female choice. Based on a literature compilation of existing knowledge of traits with this dual function, we propose that they commonly arise through intersexual selection processes and serve as honest signals to other males regarding fighting ability or dominance. Faking these traits, here called armaments, (i.e. weapons and status badges) is difficult, as they are constantly put to trial in male-male contests. Females that subsequently utilize them as indicators of male phenotypic quality when selecting a partner will benefit by acquiring males of higher quality to father their offspring. Thus, evolution of armaments through male-male competition is seen as a usually initiating process, whereas female choice later may assume a role as an additional selective factor. The reverse, that males use information from traits evolved through female choice, is, however, also possible. The traditional view of independently evolved and temporarily unordered intra- and intersexual selection processes fails to explain dual trait functions. Moreover, our model may more satisfyingly than traditional ones explain how trait honesty and trait genetic variance are maintained: theoretical and empirical evidence suggests that such honesty and variation are more easily maintained under male-male competition than under female choice.     

Molecular analysis of theArabidopsis pattern formation geneGNOM: gene structure and intragenic complementation

TheGNOM gene is required for pattern formation along the main body axis of the embryo in the flowering plantArabidopsis thaliana. Mutations in theGNOM gene alter the asymmetric division of the zygote and interfere with the formation of distinct apical-basal regions in the developing embryo. We have isolated theGNOM gene by positional cloning, characterised its structure and determined the molecular lesions in mutant alleles. Although the predicted 163 kDa GNOM protein has a conserved domain in common with the yeast secretory protein Sec7p, it is most closely related in size and overall similarity to the product of the yeastYEC2 gene, which is not essential for cell viability. Four fully complementinggnom alleles carry missense mutations in conserved regions, seven partially complementing alleles have premature stop codon mutations and two non-complementing alleles have splice-site lesions. Our results suggest that the GNOM protein acts as a complex of identical subunits and that partial complementation may involve low levels of full-length protein generated by inefficient translational read-through.Communicated by H. Saedler