In vitro regeneration of Gaillardia pulchella Foug.

Young leaf and internodal stem segments of Gaillardia pulchella, collected from wild species re-established in the greenhouse, were used to initiate callus on Murashige & Skoog medium supplemented with NAA (2.0 mgl⁻¹) and BA (0.4 mgl⁻¹). Callus formed after 10 to 14 days in the dark. Cultures were transferred to fresh medium and placed under lighted conditions where shoot formation occurred approximately 14 to 30 days after initiation. Callus sub-cultured at 14 to 21-day intervals continued to produce primordia for several weeks. Flowers were produced by regenerated shoots maintained on MS medium, but roots did not develop until the plantlets were transferred to soil conditions.     

Regeneration of plants from callus and embryos of ‘Royal’ apricot

Immature embryos of apricot (Prunus armeniaca L.) cv. Royal with a PF index of 25–100 were used to regenerate plants in vitro using two methods. In the first case, callus was initiated on MS medium with 4.5 M 2, 4-D plus 0.44 M BA and regeneration of shoots from the callus occurred on MS medium with 4.4 M BA plus 1.0 M 2, 4-D. In the second case, adventitious buds were directly regenerated from the cotyledons on MS medium with 4.4 M BA plus 1.0 M 2, 4-D.Abbreviations BA 6-benzyladenine - IBA dole-3-butyric acid - NAA -naphthylacetic acid - 2, 4-D 2, 4-dichlorophenoxyacetic acid - PF (embryo length/seed length) x 100     

Morphogenic potential of mechanically isolated single cells from Digitalis obscura L. callus

Calli from hypocotyl and root explants of Digitalis obscura L. showed regeneration of adventitious shoots, roots and embryos when transferred to Murashige & Skoog medium supplemented with cytokinins alone or in combination with auxins. Optimum shoot-bud formation was achieved in the presence of IAA and BA, while roots mainly appeared either in absence of growth regulators or with IAA and Kn. Embryo formation took place only in those combinations that included Kn. Embryo development was influenced by the type of auxin, and precocious germination occurred in media with NAA. Mechanically isolated cells from hypocotyl- and root-derived calli were plated in MS medium supplemented with several IAA and BA combinations. Single cells were able to proliferate forming callus within 20–30 days in culture. In order to induce organogenesis, calli were transferred to various regeneration media. Shoot-bud differentiation efficiency depended on both callus origin and medium initially used for cell culture, best results being obtained in calli grown from hypocotyl-derived cells cultured in the presence of casein hydrolysate. A further subculture to medium containing coconut milk and lower concentrations of NH₄NO₃ and sucrose promoted shoot development. Rooting was readily achieved upon transferring shoots onto half-strength MS medium. Plantlets were ultimately established in soil.Abbreviations BA benzyladenine - BM basal medium - CH casein hydrolysate - CM coconut milk - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indoleacetic acid - Kn kinetin - MS Murashige & Skoog - NAA naphthaleneacetic acid     

Regeneration of plants from hypocotyl protoplasts of rapessed (Brassica napus L. var. oleifera) cultivars

Protoplast cultures were prepared from hypocotyls of ten spring rapeseed cultivars. Protoplasts from all genotypes tested formed calli, and shoots were regenerated from calli of nine of the genotypes at frequencies varying from 15 to 76%. The regenerating cultivars fell into a high regenerating group (>60% and a low regenerating group <25%).     

Growth and shoot formation in protoplast-derived calli of Brassica oleracea ssp. acephala and ssp. capitata

The effect of media components and environmental factors on growth and organogenesis of protoplast-derived calli of curly kale and cabbage were tested. Optimal growth (fresh weight increase of calli, shoots and roots) was found at 60 mM sucrose. Lower sucrose concentrations (3–30 mM) were favourable for shoot formation. Nitrate concentrations from 23 to 100 mM in combination with 8 or 21 mM ammonium were optimal for shoot formation. However, growth was reduced by high (100 mM) nitrate concentration. The effects of various organic nitrogen compounds at 0.5 and 2 mM were tested. Glutamine did not influence shoot formation and barely growth. Proline at 0.5 mM stimulated growth of cabbage calli but decreased growth of curly kale calli, and at 2 mM, proline also inhibited shoot production. Adenine sulphate decreased growth of cabbage calli at 0.5 mM, and at 2 mM shoot production was also reduced. Spermidine and spermine inhibited both growth and differentiation. Putrescine resulted in about 50% higher fresh weights, and also increased the number of calli producing shoots by about 35%. More calli produced shoots in white light than in blue or red light or in darkness. The length of the photoperiod or intensity of light was not critical for shoot production.     

In vitro propagation of green-foliaged Dracaena fragrans Ker.

Callus tissue was induced in young stem segments cultured on MS based media supplemented with 0.25–0.5 mg l^-1 2, 4-D. Shoots were differentiated on media containing 0.5–1.0 mg l^-1 BA and 0.5–2.0 mg l^-1 IBA or 0.1–0.2 mg l^-1 NAA. The same media were suitable for shoot multiplication. Shoot elongation and rooting were strongly inhibited by BA and stimulated by auxins IBA and NAA. Medium containing 0.5 mg l^-1 IBA was optimal for rooting. Root elongation was stimulated by light and inhibited in darkness. Transfer of rooted plantlets to outdoor conditions was feasible and special hardening procedures were not required. Among more than 5000 plants produced by this procedure only 9 off-type plants with variegated leaves were found.     

Metabolic correlates to glycerol biosynthesis in a freeze-avoiding insect,Epiblema scudderiana

Summary The course of glycerol biosynthesis, initiated by exposure to –4°C, was monitored in larvae of the goldenrod gall moth,Epiblema scudderiana, and accompanying changes in the levels of intermediates of glycolysis, adenylates, glycogen, glucose, fructose-2,6-bisphosphate, and fermentative end products were characterized. Production of cryoprotectant was initiated within 6 h after a switch from +16° to –4°C, with halfmaximal levels reached in 30 h and maximal content, 450–500 mol/g wet weight, achieved after 4 days. Changes in the levels of intermediates of the synthetic pathway within 2 h at –4°C indicated that the regulatory sites involved glycogen phosphorylase, phosphofructokinase, and glycerol-3-phosphatase. A rapid increase in fructose-2,6-bisphosphate, an activator of phosphofructokinase and inhibitor of fructose-1,6-bisphosphatase, appeared to have a role in maintaining flux in the direction of glycerol biosynthesis. Analysis of metabolite changes as glycerol production slowed suggested that the inhibitory restriction of the regulatory enzymes was slightly out of phase. Inhibition at the glycerol-3-phosphatase locus apparently occurred first and resulted in a build-up of glycolytic intermediates and an overflow accumulation of glucose. Glucose inhibition of phosphorylase, stimulating the conversion of the activea to the inactiveb forms, appears to be the mechanism that shuts off phosphorylase function, counteracting the effects of low temperature that are the basis of the initial enzyme activation. Equivalent experiments carried out under a nitrogen gas atmosphere suggested that the metabolic make-up of the larvae in autumn is one that obligately routes carbohydrate flux through the hexose monophosphate shunt. The consequence of this is that fermentative ATP production during anoxia is linked to the accumulation of large amounts of glycerol as the only means of maintaining redox balance.Abbreviations G6P glucose-6-phosphate - F6P fructose-6-phosphate - F1, 6P fructose-1,6-bisphosphate - F2,6P ₂ fructose-2,6-bisphosphate - G3P grycerol-3-phosphate - DHAP dinydroxyacetonephosphate - GAP glyceraldehyde-3-phosphate - PEP phosphoenolpyruvate - PFK phosphofructokinase - FBPase fructose-1,6-bisphosphatase - PK pyruvate kinase     

Periodic electric field as a biopolymer conformation switch: a possible mechanism

A theoretical model is proposed to describe the influence of a periodic electric field (PEF) upon a biopolymer. The biopolymer is treated as a classical mechanical system consisting of subsystems (molecular groups) which interact with each other through potential forces. The PEF is treated as a periodic driving force applied to a molecular group. The energy dissipation is considered using the model of fluid (viscous) friction. Arguments for the non-linear character of the friction-velocity dependence caused by the non-Newtonian rheology of a viscous medium are formulated.A forced molecular-group motion is investigated for the situation of a small driving-force period, with oscillations overdamped and a driving force consisting of more than one harmonic. As a result, it is established that the motion always gets to a terminal stage when only a small-scale vibration about some point, X ^*, takes place. The terminal motion is preceded by a transient characterized by the presence of a directional velocity component and so by a drift along a potential profile. the drift goes on until a barrier is met which has a sufficiently large steepness (the barrier height is not important). As a result, the point X ^* may happen to be remote from the conformation potential local minimum (conformational state). The physical reasons for the drift are described.If we consider the small-scale vibration about X ^* in the framework of the hierarchy of scales for intramolecular mobility, it can be regarded as an equilibrium mobility, whereas the drift can be regarded as a functionally important motion, and X ^* as a new conformational state which is realizable only in the presence of the PEF. It may be concluded, as the result of a consistent treatment and neglecting the small-scale vibration, that the conformational potential is modified by adding a linear term (in the one-dimensional case). In this connection, the set of conformational states can both deform (deviation of the positions of minima and their relative depth) and rearrange qualitatively (some minima can vanish and/or new minima can appear). In particular, the transition from one conformation to another one may happen due to rearrangement.     

云南呈贡梁王山现代花粉雨的研究

本文通过对云南呈贡梁王山5块表土分析,初步研究了主要植物花粉的百分含量与其植物覆盖率之间的数量关系,并用校正系数R值表示。按照R值的大小,分为两组:R>1属于超代表性,包括有松、桤木、马桑、蒿和部分蕨类植物;R<1属于低代表性,包括有油杉、栲和石栎、滇青冈、栎、铁仔。在分析松粉分布特征基础上,认为昆明地区西风急流对松粉的传播是主要因素。     

Acute phase response to recombinant interleukin-6 and macrophage- and fibroblast-derived crude cytokine preparations in primary cultures of mouse hepatocytes

A number of acute phase proteins were determined by electroimmunoassay in media from CBA mouse hepatocytes cultured for 2 days with human recombinant IFN beta 2/IL-6, as well as with conditioned media from LPS-stimulated rat macrophages, and of murine L fibroblasts. It was found that human recombinant IL-6 caused three-fold increase in secretion of fibrinogen, while haptoglobin, complement C3 and transferrin were increased respectively, to 168 per cent, 151 per cent, and 145 per cent of the control. DEX(10(-7) M) in DMEM supplemented with 5 per cent FCS, enhanced the IL-6 effect on the three positive acute phase proteins. IL-6 elevated haptoglobin mRNA in mouse hepatocytes to a degree comparable with the concentration of the protein in the culture medium. The effect of conditioned media from murine fibroblasts and peritoneal rat macrophages was generally similar to that of recombinant IL-6. However, both natural preparations of the cytokines caused decrease in albumin and alpha-1-proteinase inhibitor secretion.