Growth and cell wall changes in rice coleoptiles

A fractionation of non-cellulosic sugars of Oryza sativa L. coleoptile cell walls was carried out and the composition of each fraction was studied during coleoptile growth.Percentages of fractions extracted with boiling water and with oxalate (pectic substances) were almost constant throughout development. An increase in the K II hemicellulosic fraction (extracted with 24% KOH) content, and a decrease in the K I hemicellulosic fraction (extracted with 10% KOH) were detected, when coleoptile growth finished.The percentage of glucose content in the K I hemicellulosic fraction was highest in young coleoptiles and lowest in old ones. Furthermore, a highly significant linear relationship between amounts of glucose and growth rate was obtained, while a inverse relationship between the amount of xylose and arabinose and growth rate was attained.Abreviations GLC gas liquid chromatography - IAA indole-3-acetic-acid - TFA trifluoroacetic acid - T_o minimum stress-relaxation time     

Effect of prostaglandins E1 and F2 alpha on neuromuscular transmission in the frog sartorius muscle.

End plate potentials (e.p.p.s.) and miniature end plate potentials (m.e.p.p.s.) were recorded intracellularly at the neuromuscular junction of the frog sartorius muscle. Addition of as little as 8.5 x10(-8)M PGE1 reduced the mean m.e.p.p. frequency. The mean amplitude of m.e.p.p.s was not changed, the mean amplitude of the e.p.p.s and the quantum content of the transmitter released by a nerve impulse was slightly reduced. A decrease in mean m.e.p.p. frequency was also seen in response to the administration of 8.5 x 10(-8)M PG2 alpha. The mean amplitude of e.p.p.s and m.e.p.p.s and the quantum content remained unchanged. The possible presynaptic mode of action of PGs in the preparation of discussed.     

Age-related changes in the tissue content of total iodine, its hormonal and nonhormonal compounds and their metabolic course

By the spectrophotometric method the age changes of total iodine content, its hormonal and non-hormonal compounds in rats and men tissues (muscles, liver, kidney, heart, lungs, brain, spleen and blood) have been studied. It was established that the total iodine content decreased at the expense of the protein-bound iodine concentration and also of the butyl-alcohol extractable iodine. The exchange of thyroid hormones intensity lowered.     

Nutritional regulation of differentiation and synthesis of an exocytoplasmic deoxyriboendonuclease in Streptomyces antibioticus

Streptomyces antibioticus produces a cell-wall-located deoxyriboendonuclease (DNAase) the synthesis of which in submerged and surface cultures is related to the growth rate. DNAase synthesis always preceded aerial mycelium formation in surface cultures. Production of aerial mycelium began at the end of exponential growth or in the early stationary phase; it was absent in cultures grown on nutrient agar/glucose or in media with a high concentration of casein hydrolysate. These nutritional conditions also impaired production of the DNAase. External DNA substrates were not degraded by mycelium producing the DNAase. These observations lead us to suggest a role for the enzyme in the developmental cycle of S. antibioticus.     

Shape transitions and shape stability of giant phospholipid vesicles in pure water induced by area-to-volume changes.

Shape transformations of vesicles of dimyristoylphosphatidylcholine (= DMPC) and palmitoyloleylphosphatidylcholine (= POPC) in ion-free water were induced by changing the area-to-volume ratio via temperature variations. Depending on the pretreatment we find several types of shape changes for DMPC (in pure water) at increasing area-to-volume ratio: (a) budding transitions leading to the formation of a chain of vesicles at further increase of the area-to-volume ratio, (b) discocyte-stomatocyte transitions, (c) reentrant dumbbell-pear-dumbbell transitions, and (d) spontaneous blebbing and/or tether formation of spherical vesicles. Beside these transitions a more exotic dumbbell-discocyte transition (e) was found which proceeded via local instabilities. Pears, discocytes, and stomatocytes are stable with respect to small temperature variations unless the excess area is close to values corresponding to limiting shapes of budded vesicles where temperature variations of less than or equal to 0.1 degree C lead to spontaneous budding to the inside or the outside. For POPC we observed only budding transitions to the inside leading either to chains of vesicles or to distributions of equally sized daughter vesicles protruding to the inside of the vesicle. Preliminary experiments concerning the effect of solutes are also reported. The first three types of shape transitions can be explained in terms of the bilayer coupling model assuming small differences in thermal expansivities of the two monolayers. This does not hold for the observed instabilities close to the limiting shapes.     

Taurine release associated to volume regulation in rabbit lymphocytes.

Rabbit lymphocytes exposed to hyposmotic media first swell and then recover their initial volume within 6 min. During volume recovery, free amino acids (FAA) decrease from 451.1 to 208 nmoles/mg protein. Taurine was the dominating FAA, accounting for 70% of the FAA pool. The time course of 3H-taurine release induced by hyposmolarity followed that of volume recovery. Efflux of 3H-taurine in an 8 min period was 17.8% (of total labeled taurine accumulated during loading) in an isosmotic medium. Reducing osmolarity to 0.87, 0.75, 0.62, and 0.5 increased this release to 24.8%, 38.1%, 56.4% and 70.9%, respectively. The volume-sensitive release of 3H-taurine was unaffected by omission of external Na+ or Ca++ and was reduced by 23% in the absence of Cl-. It was unaffected by agents disrupting the cytoskeleton or by tetraethylammonium, barium, quinidine, and gadolinium, but was 26% reduced by DIDS. Taurine release was inhibited at 4 degrees C, but was unchanged at 15 degrees C or 25 degrees C. An involvement of FAA, particularly taurine, in lymphocyte volume regulation is suggested.     

Protection against acute paraquat toxicity by ambroxol

An expression vector for G-CSF, pASLB3-3, was constructed and introduced into Namalwa KJM-1 cells (Hosoi et al., 1988), and cells resistant to 100 nM of methotrexate (MTX) were obtained. Among them, the highest producer, clone SC57, was selected and the productivity of this clone was further characterized. The maximal production of G-CSF was at the most 1.8 g/ml/day using a 25 cm² tissue culture flask, even though the cell number was above 7×10⁵ cells/ml. The limiting factors at high density were analyzed as the deficiency of nutrients, such as glucose, cysteine and serine, and pH control. The depression of specific G-CSF productivity per cell under the batch culture conditions was overcome by using a perfusion culture system, Biofermenter^TM (Sato, 1983) with modifications of nutrients supplementation by a dialysis membrane and/or dissolved oxygen (DO) supplementation by microsilicone fibers. ITPSGF medium was modified to elevate concentrations of amino acids and glucose by 2.0- and 2.5-times, respectively. Under the control of pH at 7.4 and DO at 3 ppm, the specific G-CSF productivity was not depressed even at high cell density (above 1×10⁷ cells/ml), and the amount of G-CSF reached 41 g/ml. These results indicated the possibility of finding the optimum culture conditions for the production of recombinant proteins by Namalwa KJM-1 cells.Abbreviations ABTS 2,2-Azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid - BSA Bovine Serum Albumin - BSA-PBS Phosphate-buffered Saline without Ca²⁺ and Mg²⁺ containing Bovine Serum Albumin - dhfr Dihydrofolate Reductase - DO Dissolved Oxygen - G-CSF Granulocyte Colony-stimulating Factor - HEPES 4-(2-Hydroxyethyl)-1-piperazineethansulfonic Acid - IFN Interferon - MTX Methotrexate - PBS(-) Phosphate-buffered saline without Ca²⁺ and Mg²⁺ - Tween-PBS Phosphate-buffered saline without Ca²⁺ and Mg²⁺ containing 0.05% of Tween 20     

Benthic-pelagic flux rates on mussel beds: tunnel and tidal flume methodology compared

Material flux rates in an intertidal mussel bed were measured synchronously over two tidal cycles in June 1989 with Benthic Ecosystem Tunnels and a double lane flume. The tunnels enclosed the near bottom water, whereas the flume canalized the total water column. One tunnel was set up in a mussel bed and another one in an adjacent sand bottom as a control. The flume enclosed a mussel lane and a sand lane. In the tunnel and in the flume the mussel bed revealed ammonium and phosphate discharge. At the same time, phytoplankton, dominated byPhyaeocystis globosa, was taken up intensively. These flux rates showed the same tendency but they were higher in the flume than in the tunnel. Different tendencies and flux rates for oxygen and particulate organic matter (POC, PN) were found in flume and tunnel. These differences demonstrate the importance of water column processes regarding the material exchange of a mussel bed. Tunnels enclose smaller bodies of water and are therefore expected to detect even small effects of the benthos on the passing water. In flumes, benthic influence may be diluted over the entire water column but conditions are more natural. The use of flumes is restricted to shallow waters while tunnels have the potential to be used at any depth.     

Total Thyroxine and Free Thyroxine Index in Plasma of Dairy Cows in Relation To Strength of Heat

Total thyroxine (TT4) and free thyroxine index (FT4I) were measured in peripheral plasma of cows. The samples were collected at the time of insemination from 66 cows showing pronounced signs of the heat and from 56 cows showing weak or silent heat. Neither TT4 or FT4I in plasma differed significantly between the two categories of oestrous cows.