Ethylene and growth control in the fringed waterlily (Nymphoides peltata): Stimulation of cell division and interaction with buoyant tension in petioles

The effect of ethylene on petiole growth of the Fringed Waterlily (Nymphoides peltata (S.G. Gmelin) O. Kuntze) changes during leaf ontogeny. During early development (before expansion of laminae), ethylene causes an increase in both cell number and cell size; later in development, promotion of rapid cell expansion is the dominant effect. The early effects may contribute to the accommodation of new leaves to water columns of different depth. The later effects on cell expansion only are shown to contribute to the rapid accommodation of floating leaves when changes in water level submerge the laminae. This kind of accommodation results from an interaction between accumulated ethylene, which increases wall extensibility, and the tension in petioles due to natural buoyancy which, it is suggested, supplements the driving force for cell expansion. Cell age (position) within a petiole and age of the whole petiole influence the growth response to ethylene alone and the amount of extra growth produced by applying tension when ethylene is present. In young petioles, apical cells are highly sensitive to ethylene and tension causes little further growth; older cells in both immature and mature petioles show little response to ethylene unless the petiole is under tension. Young (but not mature) petioles respond slowly to applied tension even in the absence of ethylene. It is concluded that as cells age the driving force for expansion limits increasingly their capacity to respond to the wall-loosening effects of ethylene. Dual sensitivity to ethylene and buoyant tension facilitates rapid accommodation responses but sensitivity of young petioles to tension alone may exclude Nymphoides from habitats where current velocity is appreciable.     

Anion secretion by the isolated rabbit pancreas

The isolated rabbit pancreas secretes a fluid containing chloride and bicarbonate in about equal concentrations. Replacement of bicarbonate by acetate, phosphate or isethionate, replacement of Na⁺ by Li⁺ and addition of ouabain to the bathing medium of the pancreas inhibit the secretion of fluid, chloride and bicarbonate in a similar fashion and by maximally 100%. Replacement of chloride by isethionate inhibits fluid secretion by maximally 50%, chloride secretion by 90% and bicarbonate secretion by 20%. It is concluded that fluid secretion is based on a Na⁺-gradient-dependent bicarbonate influx or proton efflux in the ductular cell, and that the secretion of chloride is secondary to that of bicarbonate.     

Exfoliative cytology in the evaluation of interferon treatment of cervical intraepithelial neoplasia

Local interferon injection in four patients with cervical intraepithelial neoplasia (CIN) regularly elicited progressive regression of the lesions. The response was observed with exfoliative cytology after each injection, guided by colposcopic examination. The cytologic changes showed a cytocidal effect mainly on the dyskaryotic cells, preceded by cellular degeneration not unlike that of nonspecific inflammation and accompanied by an increase in neutrophil infiltration. The cytologic response was closely correlated with partial or complete clinical regression based on the absence of viable or degenerated dyskaryotic cells in the cervical smears. Three patients showed complete clinical regression after treatment. One patient showed recurrent viable dyskaryotic cells when the dosage was reduced, and treatment was suspended temporarily although her lesion had regressed completely after five injections. Clinical recurrence was noted one week after viable dyskaryotic cells reappeared in her smears. These observations suggest that cytology may be a useful means of monitoring interferon treatment in CIN.     

Microscopic anatomy of the ovary ofAlouatta caraya

The microscopic structure of theAlouatta caraya ovary is studied in different ages and reproductive stages. The most significant feature seems to be the presence in adult ovaries of abundant glandular interstitial tissue which occupies both the cortex and medulla. It seems to be derived from the theca interna of atretic follicles. Discrete luteinized masses are present in the medulla in all the ovaries observed. Invaginations of the surface epithelium are seen only in infant and juvenile ovaries. The development of cystic follicles seems to be a common pathway of atresia.     

The identification of trihydroxyeicosatrienoic acids as products from the incubation of arachidonic acid with washed blood platelets

Arachidonic acid is converted by washed platelets from man, horse and dog into a mixture of 8, 9, 12-trihydroxyeicosa-5, 10, 14-trienoic acid and 8, 11, 12-trihydroxyeicosa-5, 9, 14-trienoic acid (termed 8, 9, 12-THETA and 8, 11, 12-THETA respectively and THETA collectively). Gas chromatographic — mass spectrometric evidence of structure is discussed.     

SIALYLTRANSFERASES IN RAT BRAIN: REACTION KINETICS, PRODUCT ANALYSES, AND MULTIPLICITIES OF ENZYME SPECIES

Abstract— The incorporation of NeuNAc from CMP-NeuNAc into endogenous glycolipids and glyco-proteins, and exogenously added GM_1a (monosialoganglioside) and desialylated fetuin (DS-fetuin) was studied with particulate preparations from 11 to 15 day old rat cerebra. The apparent +K++_m values of the enzyme systems for the different substrates, assayed with 0.5 mg enzyme protein, were: CMP-NeuNAc, 0.13 mm (same with endogenous and exogenous glycolipid and glycoprotein substrates); GM_1a, 0.20 mm ; DS-fetuin, 0.15 mm (or 1.2 mm in terms of acceptor sites). The activities, expressed as nmoles NeuNAc incorporated per 0.5 mg enzyme protein per 30 min incubation at 37°C and pH 6.3, were 0.094, 0.039, 0.17 and 0.64 with the endogenous glycolipids, endogenous glycoproteins, exogenous GM_1a and exogenous DS-fetuin, respectively. Incorporation into endogenous glycolipids was mainly in GM₃, while exogenously added GM_1a was converted to GD_1a. Incorporation into endogenous glycoproteins yields about 20 sialoglycopolypeptides on SDS-polyacrylamide gel electrophoresis. Neura-minidase pretreatment of the particulate enzyme preparation decreased sialylation of the higher molecule weight polypeptides but increased sialylation of the lower molecule weight species. The sialyltransferase activity with the endogenous glycolipid substrates was more heat resistant than the activities with exogenous GM_1a. Since more than 60% of the endogenous glycolipid activity was due to the conversion of lactosylceramide to GM₃, the sialyltransferase responsible for this reaction appears to be different from the one that acts on GM_1a. This was supported by the observation that exogenously added GM_1a did not diminish the incorporation of NeuNAc into endogenous lactosylceramide. These two glycolipid sialyltransferase activities were distinguishable from the glycoprotein sialyltransferase activity since exogenous DS-fetuin did not compete with either the endogenous or the exogenous glycolipids for CMP-NeuNAc.     

SIALYLTRANSFERASES IN RAT BRAIN: INTRACELLULAR LOCALIZATION AND SOME MEMBRANE PROPERTIES

Abstract— Total rat cerebral homogenate, with nuclei removed, yielded sialyltransferase activity peaks that were distinct from the protein distribution profile in a continuous sucrose density gradient. Marker enzyme studies and electron microscopic examinations on the gradient fractions suggested that most of the sialyltransferase activities were not associated with the synaptosomes.
The sialyltransferases appeared to be localized in the smooth microsomal membranes and the Golgi complex derivatives. The sialyltransferase activities were stimulated by non-ionic detergent mixture, Triton CF-54/Tween 80 (2/1, w/w), the effect being much more pronounced with exogenous substrates. The stimulatory effect was dependent on detergent concentration. With 1 mg detergent mixture per mg enzyme protein, the percent increases in enzyme activities with the different substrates were: endogenous glycolipids, 100; endogenous glycoproteins, 50; exogenous GM_1a, 700; exogenous DS-fetuin, 230. The action of the nonionic detergents appears to be on a hydrophobic segment of the enzyme molecule, bearing the active site, which is buried in the membrane lipid bilayer. This was substantiated by the partial trypsin resistance of the sialyltransferase activities and the abolition of that resistance when trypsiniza-tion was performed in the presence of nonionic detergents. Furthermore, the sialyltransferase activities were markedly inhibited by organic solvents; and these inhibitory effects were inversely proportional to the solvent dielectric constants.