Synergism between Gibberellin and Auxin in the Growth of Intact Tomato

Gibberellin A_4&7 was more effective than gibberellic acid in increasing shoot elongation when applied to the apex of intact Lycopersicum esculentum seedlings of Tiny Tim, a dwarf cultivar, and Winsall, a tall cultivar. After 14 days, gibberellic acid and gibberellin A_4&7 stimulated growth of the dwarf more than the tall tomato. In tall tomato the application of indole-3-acetic acid alone (6.1 μg/plant) showed an inhibitory growth effect, but when applied with 17.5 μg per plant of gibberellic acid, it had a synergistic effect at 7 days but not at 14 days. When the auxin concentration was reduced to 0.61 μg per plant a synergistic effect was observed on tall plants at 7 and 14 days between indole-3-acetic acid and gibberellic acid. Application of gibberellin A_4&7 with auxin did not give a synergistic response in tall or dwarf tomato.     

Synergism between Chlorhexidine and Sulphadiazine

Chlorhexidine and sulphadiazine react synergistically against strains of Pseudomonas. Proteus and Staphylococcus , with high factors of synergy. The impermeability of these strains to sulphadiazine is destroyed by low concentrations of chlorhexidine, permitting the accumulation of sulphadiazine which then inhibits protein synthesis. The combination of these drugs is bactericidal.     

Phene Synergism between Root Hair Length and Basal Root Growth Angle for Phosphorus Acquisition

Shallow basal root growth angle (BRGA) increases phosphorus acquisition efficiency by enhancing topsoil foraging because in most soils, phosphorus is concentrated in the topsoil. Root hair length and density (RHL/D) increase phosphorus acquisition by expanding the soil volume subject to phosphorus depletion through diffusion. We hypothesized that shallow BRGA and large RHL/D are synergetic for phosphorus acquisition, meaning that their combined effect is greater than the sum of their individual effects. To evaluate this hypothesis, phosphorus acquisition in the field in Mozambique was compared among recombinant inbred lines of common bean (Phaseolus vulgaris) having four distinct root phenotypes: long root hairs and shallow basal roots, long root hairs and deep basal roots, short root hairs and shallow basal roots, and short root hairs and deep basal roots. The results revealed substantial synergism between BRGA and RHL/D. Compared with short-haired, deep-rooted phenotypes, long root hairs increased shoot biomass under phosphorus stress by 89%, while shallow roots increased shoot biomass by 58%. Genotypes with both long root hairs and shallow roots had 298% greater biomass accumulation than short-haired, deep-rooted phenotypes. Therefore, the utility of shallow basal roots and long root hairs for phosphorus acquisition in combination is twice as large as their additive effects. We conclude that the anatomical phene of long, dense root hairs and the architectural phene of shallower basal root growth are synergetic for phosphorus acquisition. Phene synergism may be common in plant biology and can have substantial importance for plant fitness, as shown here.Suboptimal phosphorus availability is a primary limitation to plant growth in terrestrial ecosystems (Vance et al., 2003). Large areas of tropical and subtropical soils in Africa, Latin America, and Asia have phosphorus availability limited by low total phosphorus content as well as high phosphorus fixation (Sanchez and Uehara, 1980). The use of phosphorus fertilizer to correct phosphorus deficiency is only a partial solution, since phosphorus fertilizers are costly, nonrenewable, potentially harmful to the environment, and often marginally effective in tropical soils because of immobilization by the soil (Cathcart, 1980). Therefore, the development of crop cultivars with enhanced ability to acquire phosphorus is an important strategy to increase agricultural productivity in low-input agroecosystems and to reduce input requirements in intensive agriculture (Vance et al., 2003; Gahoonia and Nielsen, 2004; Lambers et al., 2006; Lynch, 2007, 2011).Several root phenes (i.e. basic units of the phenotype; Serebrovsky, 1925; Lynch, 2011; for discussion, see York et al., 2013) enhance phosphorus acquisition, including root architectural phenes for topsoil foraging (Lynch and Brown, 2001), such as shallow root growth angles (Liao et al., 2004; Ho et al., 2005), increased basal root whorl number (Lynch and Brown, 2012; Miguel et al., 2013), and adventitious rooting (Miller et al., 2003); phenes to enhance soil exploitation, including root hair length and density (RHL/D; Bates and Lynch, 2000a, 2000b, 2001; Ma et al., 2001a; Gahoonia and Nielsen, 2004; Yan et al., 2004) and phosphorus-solubilizing root exudates (Ryan et al., 2001); mycorrhizal symbioses (Smith and Read, 2008); and phenes that reduce the metabolic cost of soil exploration (Lynch and Ho, 2005), such as root etiolation and root cortical aerenchyma (Fan et al., 2003; Postma and Lynch, 2010, 2011). It is probable that interactions among these phenes are important in determining the phosphorus acquisition of integrated phenotypes. Results from the structural-functional model SimRoot indicate that RHL/D, the distance from the root tip to the first appearance of root hairs, and the pattern of root hair-bearing epidermal cells (trichoblasts) among non-hair-bearing cells (atrichoblasts) are synergetic for phosphorus acquisition in Arabidopsis (Arabidopsis thaliana; Ma et al., 2001b). Another SimRoot study showed that on low-phosphorus soils, the utility of root cortical aerenchyma in maize (Zea mays) may be 2.9 times greater in plants with increased lateral branching density than in plants with normal branching (Postma and Lynch, 2011). Morphological, anatomical, symbiotic, and biochemical phenes expressed by root axes should have significant synergies with architectural phenes, since architectural phenes determine the position of root axes in time and space and, therefore, the soil domain in which spatially localized phenes are expressed (Lynch, 2011).Phosphorus availability is greater in the topsoil, with a steep decline with depth. Therefore, root architectural phenes that increase topsoil foraging can improve phosphorus acquisition (Lynch and Brown, 2001). Root shallowness regulated by basal root growth angle (BRGA) has been demonstrated to be of particular importance for topsoil foraging (Bonser et al., 1996; Liao et al., 2001; Rubio et al., 2001; Ho et al., 2005). These studies show that common bean (Phaseolus vulgaris) genotypes with smaller BRGA (i.e. shallower roots) have better performance in low-phosphorus soils. Shallow root distribution is also important for phosphorus acquisition in maize (Zhu et al., 2005).RHL/D are also important for phosphorus acquisition (Bates and Lynch, 2000a, 2000b, 2001; Gahoonia and Nielsen, 2004). Since phosphorus mobility in soil is governed by diffusion rather than mass flow, phosphorus uptake by roots is limited by localized phosphorus depletion in the rhizosphere (Barber, 1995). Long root hairs extend the phosphorus depletion zone surrounding the root, thereby increasing the total amount of phosphorus accessible by the roots and phosphorus acquisition. In many plant species, the length and density of root hairs increase in response to low phosphorus availability (Bates and Lynch, 1996; Ma et al., 2001a). Increased RHL/D increases phosphorus accumulation in Arabidopsis growing in low-phosphorus conditions (Bates and Lynch, 2000a, 2000b), and mutants lacking root hairs have reduced phosphorus acquisition (Bates and Lynch, 2000b; Gahoonia et al., 2001). Species that develop more and/or longer root hairs (e.g. Lolium perenne) are more efficient in accessing inorganic phosphorus from soils and thus show greater growth response to phosphorus fertilization than species that lack these traits (e.g. Podocarpus totara). Genotypic variation for root hairs is associated with increased phosphorus acquisition in several species, including barley (Hordeum vulgare; Gahoonia and Nielsen, 2004), common bean (Miguel, 2004; Yan et al., 2004), and maize (Zhu et al., 2010).We hypothesize that the utilities of BRGA and RHL/D for phosphorus acquisition are synergetic. Root hairs will be more valuable for phosphorus acquisition if located in surface soil horizons by arising from roots with a shallow growth angle; shallow roots will have greater benefit for phosphorus acquisition if they have long and dense hairs. Therefore, genotypes possessing long, dense root hairs on shallow roots should have greater phosphorus acquisition than genotypes with either long root hairs on deep roots or short root hairs on shallow roots. We expect the combined benefit of long root hairs and shallow root growth angles to exceed the sum of their individual effects, since they permit greater exploitation of soil strata with the greatest phosphorus availability.In this study, we evaluated the potential synergism between the architectural phene of BRGA and the morphological phene of RHL/D for phosphorus acquisition by comparison of contrasting phenotypes of common bean growing in a weathered tropical soil.     

Stable Pseudohyphal Growth in Budding Yeast Induced by Synergism between Septin Defects and Altered MAP-kinase Signaling

Upon nutrient limitation, budding yeasts like Saccharomyces cerevisiae can be induced to adopt alternate filament-like growth patterns called diploid pseudohyphal or invasive haploid growth. Here, we report a novel constitutive pseudohyphal growth state, sharing some characteristics with classic forms of filamentous growth, but differing in crucial aspects of morphology, growth conditions and genetic regulation. The constitutive pseudohyphal state is observed in fus3 mutants containing various septin assembly defects, which we refer to as sadF growth (septin assembly defect induced filamentation) to distinguish it from classic filamentation pathways. Similar to other filamentous states, sadF cultures comprise aggregated chains of highly elongated cells. Unlike the classic pathways, sadF growth occurs in liquid rich media, requiring neither starvation nor the key pseudohyphal proteins, Flo8p and Flo11p. Moreover sadF growth occurs in haploid strains of S288C genetic background, which normally cannot undergo pseudohyphal growth. The sadF cells undergo highly polarized bud growth during prolonged G2 delays dependent on Swe1p. They contain septin structures distinct from classical pseudo-hyphae and FM4-64 labeling at actively growing tips similar to the Spitzenkörper observed in true hyphal growth. The sadF growth state is induced by synergism between Kss1p-dependent signaling and septin assembly defects; mild disruption of mitotic septins activates Kss1p-dependent gene expression, which exacerbates the septin defects, leading to hyper-activation of Kss1p. Unlike classical pseudo-hyphal growth, sadF signaling requires Ste5, Ste4 and Ste18, the scaffold protein and G-protein β and γ subunits from the pheromone response pathway, respectively. A swe1 mutation largely abolished signaling, breaking the positive feedback that leads to amplification of sadF signaling. Taken together, our findings show that budding yeast can access a stable constitutive pseudohyphal growth state with very few genetic and regulatory changes.     

Synergism between cysteine and alkylating agents

Contrary to expectation, l-cysteine did not protect Escherichia coli from the lethal action of two monofunctional alkylating agents (nitrosomethylurethane and methylmethane sulfonate). The antibacterial action of these compounds was actually greatly enhanced by l-cysteine. This synergistic effect was also exhibited, to some extent, by d-cysteine but not by homocysteine, S-methylcysteine, or serine. The synergistic action between methylating agents and l-cysteine was not due to the formation of S-methylcysteine. l-Cysteine had no effect on the bacteriostatic action of ethylmethane sulfonate.     

Growth Hormone Release Inhibiting Hormone in Acromegaly

Growth hormone release inhibiting hormone (GHRIH) was administered by constant infusion over 75 minutes to eight acromegalic patients at different doses. 100 to 1,000 μg were equally effective in reducing circulating growth hormone (GH) levels; 25 μg lowered GH levels in only five patients, and at this dose the extent of the fall was smaller than from doses of 100 μg or more. 10 μg was ineffective. Injection of single doses of 500 μg by intravenous, subcutaneous, and intramuscular routes caused only small and transient reductions in GH levels, though the effect was improved by injecting the hormone intramuscularly in 2 ml of 16% gelatin. Injection of a suspension of 4 mg GHRIH in 1 ml of arachis oil lowered growth hormone levels for between three and four hours.In four acromegalic patients an oral 50-g glucose tolerance test was performed during a continuous infusion of either saline or 1,000 μg GHRIH. The “paradoxical” rise in growth hormone seen in these patients during the saline infusion was suppressed by GHRIH. The blood glucose responses were, moreover, modified by GHRIH in that the peak was delayed and occurred at the end of the infusion in each case. A “normal” glucose tolerance curve was converted to a “diabetic” type of response in two patients. This effect could be accounted for by the inhibition of insulin secretion known to occur with large doses of GHRIH.We speculate that acromegaly may be primarily a hypothalmic disease due to deficiency of GHRIH resulting in excessive secretion of growth hormone from the pituitary and adenoma formation due to inappropriate and prolonged stimulation of the pituitary.     

Synergism between the canine left and right hemidiaphragms.

Expansion of the lung during inspiration results from the coordinated contraction of the diaphragm and several groups of rib cage muscles, and we have previously shown that the changes in intrathoracic pressure generated by the latter are essentially additive. In the present studies, we have assessed the interaction between the right and left hemidiaphragms in anesthetized dogs by comparing the changes in airway opening pressure (DeltaPao) obtained during simultaneous stimulation of the two phrenic nerves (measured DeltaPao) to the sum of the DeltaPao values produced by their separate stimulation (predicted DeltaPao). The measured DeltaPao was invariably greater than the predicted DeltaPao, and the ratio between these two values increased gradually as the stimulation frequency was increased; the ratio was 1.10 +/- 0.01 (P < 0.05) for a frequency of 10 Hz, whereas for a frequency of 50 Hz it amounted to 1.49 +/- 0.05 (P < 0.001). This interaction remained unchanged after the rib cage was stiffened and its compliance was made linear, thus indicating that the load against which the diaphragm works is not a major determinant. However, radiographic measurements showed that stimulation of one phrenic nerve extends the inactive hemidiaphragm toward the sagittal midplane and reduces the caudal displacement of the central portion of the diaphragmatic dome. As a result, the volume swept by the contracting hemidiaphragm is smaller than the volume it displaces when the contralateral hemidiaphragm also contracts. These observations indicate that 1) the left and right hemidiaphragms have a synergistic, rather than additive, interaction on the lung; 2) this synergism operates already during quiet breathing and increases in magnitude when respiratory drive is greater; and 3) this synergism is primarily related to the configuration of the muscle.     

同株奇异变形杆菌存在不同生长状态

揭示同株奇异变形杆菌存在多种不同的生长状态。通过环形接种、点种传代、革兰染色和鞭毛染色等方法观察同株奇异变形杆菌的形态学变化。同株奇异变形杆菌的生长速度、迁徙能力、生长形态及鞭毛形态发生变化。同株奇异变形杆菌存在不同的生长形态。     

Synergism between Ultrasonic Waves and Hydrogen Peroxide in the Killing of Micro-organisms

The lethal effect on different micro-organisms of ultrasonic waves and hydrogen peroxide separately and in combination was examined. Ultrasonic waves were able to disintegrate Fusobacterium nucleatum within 3 min and to kill Veillonella parvula after 15 min and Streptoccus sanguis after 20 min; 20 vols H₂O₂ (6% w/v) killed V. parvula, Strep. sanguis and Staphylococcus aureus after 5 min treatment, and Clostridium sporogenes spores after 25 min. Sonication of Cl. sporogenes spores, Bacillus cereus spores and Candida albicans in 20 vols H₂O₂, using an ultrasonic probe, was lethal to the organisms after 15, 10 and 10 min, respectively. The latter 2 organisms were not killed by 30 min exposure to either agent separately. Similar results were obtained when an ultrasonic tank was used for sonication.     

Physiological Mechanism of Eichhornia crassipes in Inhibiting the Growth of Microcytisaeruginosa

Russian Journal of Plant Physiology - Water hyacinth (Eichhornia crassipes (Mart.) Solms), an invasive plant, is used to control algae-polluted water, but the mechanism among which is not clear. In...     

Synergism between substrate and non-substrate thiols in peroxidase-oxidase reactions

Cysteamine and reduced glutathione were shown to act synergistically as peroxidase-oxidase substrates as measured by oxygen consumption and Nitro Blue Tetrazolium reduction. Cysteine methyl ester could be substituted for cysteamine and N-acetylcysteine and penicillamine could be substituted for glutathione. The involvement of reduced oxygen species and the effects of pH and chloride were studied. A possible mechanism of peroxidase-oxidase oxidation of cysteamine and glutathione is proposed. These studies show that peroxidase oxidase reactions can occur with close to physiological concentrations of peroxidase and thiols.     

Cell Wall Growth During Differentiation of Proteus Swarmers

This paper describes the process by which the cell wall of Proteus mirabilis, as measured by the presence of the O antigen, develops during the differentiation of swarmers from short cells on an agar surface. The sequence was followed by fluorescent-antibody staining, with both the direct and reverse methods. When the organisms were labeled with fluorescent antibody by the direct method, they showed a progressive diminution of the marker along the cell surface and some increase in the length of the bacteria. However, the label had become completely diluted out before typical swarmers developed. When the bacteria were exposed initially to unlabeled antibody by the reverse technique, and then incubated with fluorescent antibody, they showed a progressive increase both in the intensity of the label along their entire periphery and in cellular length, culminating in the formation of swarmers. It is concluded that in P. mirabilis, as in the few other gram-negative bacteria examined so far, cell wall synthesis takes place diffusely, i.e., by intercalation of new with old components along the length of the cell wall.