Water Deficit in Pea Root Tips: Effects on the Cell Cycle and on the Production of Dehydrin-like Proteins

Dehydrin-like proteins have been detected in nuclei and cytoplasmof meristematic root tip cells from pea seedlings subjectedto slow dehydration at 90% relative humidity for 48 h or more.Evidence was gained from Western blotting and immunocytochemicalexperiments using an antibody raised against the conserved domainof dehydrin proteins. Flow cytometer analysis has shown thatcycling cells of root tip meristems from dehydrated seedlingsare mostly arrested in G2 phase. Other stress treatments thoughtto involve water depletion (osmotic stress, cold treatment)or to modulate cell response to water deficit (abscisic acid)gave less clear-cut results with all treatments lowering theproportion of cells entering the S phase, but without a definiteand persistent arrest in any preferential phase of the cycle.Possible interrelationships between G2 arrest and dehydrin productionare discussed. Cell cycle; dehydrins; flow cytometry; nuclei; pea; Pisum sativum L.; water stress     

Phylogenetic Study of Organic Anion Transfer from Plasma into the Liver

THE discovery of two intracellular proteins, Y and Z, with the unique property of binding certain organic anions, may help to account for the selective and rapid transfer of bilirubin and various dyes, drugs, steroids and metabolites from plasma into the liver, which is known to occur among mammals^1–3. In the rat, from which they were first isolated³, Y and Z have been shown to possess the following characteristics, (i) They selectively bind organic anions, such as bilirubin, sulphobromophthalein (BSP) and indocyanine green, in vivo and in vitro³, (ii) The principal organic anion binding protein, Y, is present predominantly in the liver^3,4, (iii) The concentration of Y increases after administration of phenobarbital, DDT and other drugs and concomitantly the rate of organic anion transfer into the liver is increased⁵. Furthermore, in the newborn monkey, the concentration of Y and the transfer into the liver of BSP, as measured by plasma disappearance rates, are both low and subsequently increase⁶. We report here the results of a phylogenetic study involving various vertebrates. These results further support the theory that Y and Z are intracellular acceptors which facilitate the transfer of certain organic anions from plasma into the liver.     

Redescription of Laomedea exigua M. Sars, a hydroid new to Scandinavia, with comments on its nematocysts, life cycle and feeding movements

The little-known hydroid Laomedea exigua M. Sars, 1857, is recorded for the first time from Scandinavian waters. The species is redescribed and the life cycle, lacking a medusa stage, is confirmed by rearing. The nematocysts are diagnostic of the species. Tentacles and hypostome co-operate in capturing prey.