Regulation of invertase activity and growth in rice (Oryza) coleoptile sections by gibberellic acid and sucrose

Changes in invertase activity and growth were examined in excised rice coleoptile sections which were treated with water, gibberellic acid (GA3), sucrose, and GA3 + sucrose. Invertase activity with all treatments rises in parallel during the first 6 h. Between 6 and 12 h, the GA3 and GA3 + sucrose treatment causes the invertase activity to increase at a faster rate than the respective water and sucrose controls. For all treatments, the peak invertase activity occurs at 12 h; it then declines rapidly between 12 and 24 h. After this, the enzyme activity becomes stable by 36 h for sucrose and GA3 + sucrose treatments. In contrast, in water and GA3 treatments, the enzyme activity continues to decrease up to 48 h, then attains a steady state level. With water, GA3, sucrose, and GA3 + sucrose, there is a close correlation between the time of maximal invertase activity and the time of maximal growth rate (12 h), and the kinetics for promotion of both processes are essentially the same. This study indicates that both GA3 and sucrose may be involved in regulating levels of invertase and that invertase activity is closely associated with growth in rice coleoptile sections.

Download Full-text

Effect of Organic Solvents on the Yield of Solvent-Tolerant Pseudomonas putida S12

Applied and Environmental Microbiology ◽

10.1128/aem.65.6.2631-2635.1999 ◽

1999 ◽

Vol 65 (6) ◽

pp. 2631-2635 ◽

Cited By ~ 70

Author(s):

Sonja Isken ◽

Antoine Derks ◽

Petra F. G. Wolffs ◽

Jan A. M. de Bont

Keyword(s):

Growth Rate ◽

Pseudomonas Putida ◽

Organic Solvents ◽

Critical Concentration ◽

Bacterial Membrane ◽

Maximal Growth ◽

Wild Type ◽

Active Efflux ◽

Maximal Growth Rate ◽

Solvent Tolerant

ABSTRACT Solvent-tolerant microorganisms are useful in biotransformations with whole cells in two-phase solvent-water systems. The results presented here describe the effects that organic solvents have on the growth of these organisms. The maximal growth rate of Pseudomonas putida S12, 0.8 h−1, was not affected by toluene in batch cultures, but in chemostat cultures the solvent decreased the maximal growth rate by nearly 50%. Toluene, ethylbenzene, propylbenzene, xylene, hexane, and cyclohexane reduced the biomass yield, and this effect depended on the concentration of the solvent in the bacterial membrane and not on its chemical structure. The dose response to solvents in terms of yield was linear up to an approximately 200 mM concentration of solvent in the bacterial membrane, both in the wild type and in a mutant lacking an active efflux system for toluene. Above this critical concentration the yield of the wild type remained constant at 0.2 g of protein/g of glucose with increasing concentrations of toluene. The reduction of the yield in the presence of solvents is due to a maintenance higher by a factor of three or four as well as to a decrease of the maximum growth yield by 33%. Therefore, energy-consuming adaptation processes as well as the uncoupling effect of the solvents reduce the yield of the tolerant cells.

Download Full-text

Osteosarcoma Developed in the Period of Maximal Growth Rate Have Inferior Prognosis

Journal of Pediatric Hematology/Oncology ◽

10.1097/mph.0b013e318168e7dc ◽

2008 ◽

Vol 30 (6) ◽

pp. 419-424 ◽

Cited By ~ 10

Author(s):

Jun Ah Lee ◽

Min Suk Kim ◽

Dong Ho Kim ◽

Jung Sub Lim ◽

Kyung Duk Park ◽

...

Keyword(s):

Growth Rate ◽

Maximal Growth ◽

Maximal Growth Rate

Download Full-text

Effect of Salt Stress on Mutation and Genetic Architecture for Fitness Components in Saccharomyces cerevisiae

G3 Genes|Genome|Genetics ◽

10.1534/g3.120.401593 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3831-3842

Author(s):

Christopher Kozela ◽

Mark O. Johnston

Keyword(s):

Saccharomyces Cerevisiae ◽

Growth Rate ◽

Salt Stress ◽

Mutation Rate ◽

Genetic Architecture ◽

Maximal Growth ◽

Fitness Components ◽

Environmental Variance ◽

Maximal Growth Rate ◽

Mutational Variance

Mutations shape genetic architecture and thus influence the evolvability, adaptation and diversification of populations. Mutations may have different and even opposite effects on separate fitness components, and their rate of origin, distribution of effects and variance-covariance structure may depend on environmental quality. We performed an approximately 1,500-generation mutation-accumulation (MA) study in diploids of the yeast Saccharomyces cerevisiae in stressful (high-salt) and normal environments (50 lines each) to investigate the rate of input of mutational variation (Vm) as well as the mutation rate and distribution of effects on diploid and haploid fitness components, assayed in the normal environment. All four fitness components in both MA treatments exhibited statistically significant mutational variance and mutational heritability. Compared to normal-MA, salt stress increased the mutational variance in growth rate by more than sevenfold in haploids derived from the MA lines. This increase was not detected in diploid growth rate, suggesting masking of mutations in the heterozygous state. The genetic architecture arising from mutation (M-matrix) differed between normal and salt conditions. Salt stress also increased environmental variance in three fitness components, consistent with a reduction in canalization. Maximum-likelihood analysis indicated that stress increased the genomic mutation rate by approximately twofold for maximal growth rate and sporulation rate in diploids and for viability in haploids, and by tenfold for maximal growth rate in haploids, but large confidence intervals precluded distinguishing these values between MA environments. We discuss correlations between fitness components in diploids and haploids and compare the correlations between the two MA environmental treatments.

Download Full-text

Relationship of Intracellular Potassium to Asexual Reproduction in Hydra

Journal of Experimental Biology ◽

10.1242/jeb.69.1.45 ◽

1977 ◽

Vol 69 (1) ◽

pp. 45-51

Author(s):

LEONARD G. EPP ◽

DANIEL C. KOBLICK

Keyword(s):

Growth Rate ◽

Steady State ◽

Culture Medium ◽

External Medium ◽

State Level ◽

Maximum Effect ◽

Steady State Level ◽

Intracellular Potassium ◽

External Potassium ◽

Relationship Of

Removal of potassium from Hydra culture medium produces a decrease in intracellular potassium and a parallel decrease in asexual growth rate. Rubidium and caesium are ineffective as substitutes for potassium in the maintenance of growth rate. Increases in intracellular potassium parallel increases in growth rate up to a level somewhat below the normal steady-state level of intracellular potassium. The full potassium requirement for maximum effect on budding can be acquired from food or external medium. High levels of external potassium suppress budding but do not alter intracellular potassium levels.

Download Full-text

Scaling behaviour of the maximal growth rate in the Rosensweig instability

EPL (Europhysics Letters) ◽

10.1209/epl/i2001-00419-1 ◽

2001 ◽

Vol 55 (3) ◽

pp. 327-333 ◽

Cited By ~ 9

Author(s):

A Lange

Keyword(s):

Growth Rate ◽

Maximal Growth ◽

Scaling Behaviour ◽

Rosensweig Instability ◽

Maximal Growth Rate

Download Full-text

Sensitivity of Saccharomyces cerevisiae to tannic acid is due to iron deprivation

Canadian Journal of Microbiology ◽

10.1139/w01-006 ◽

2001 ◽

Vol 47 (4) ◽

pp. 290-293 ◽

Cited By ~ 10

Author(s):

T Wauters ◽

D Iserentant ◽

H Verachtert

Keyword(s):

Saccharomyces Cerevisiae ◽

Fatty Acids ◽

Growth Rate ◽

Tannic Acid ◽

Unsaturated Fatty Acids ◽

Acid Resistance ◽

Maximal Growth ◽

Wild Type ◽

Iron Deprivation ◽

Maximal Growth Rate

Tannic acid inhibited the growth of the yeast Saccharomyces cerevisiae. Growth medium supplementation with more nitrogen or metal ions showed that only iron ions could restore the maximal growth rate of S. cerevisiae. Tannic acid resistant mutants were previously isolated by screening for tannic acid resistance and were all cytoplasmic petite mutants. While the wild type was very sensitive to iron deprivation conditions when grown in aerobic conditions, the mutants, whether grown aerobically or anaerobically, showed the same growth rate under iron-limited conditions as under iron-repleted conditions. Also, the wild type grown anaerobically was not affected by iron-limited conditions. Cytoplasmic petite mutants obtained by ethidium bromide mutagenesis behaved like the other mutants. During iron limitation, the wild type showed a reduced oxygen uptake rate. Maximal growth rate of the wild type in iron-limited conditions could be restored by the addition to the media of unsaturated fatty acids and sterol. Iron deprivation caused by tannic acid may thus affect the synthesis of a functional respiratory chain as well as the synthesis of unsaturated fatty acids and (or) sterol.Key words: Saccharomyces cerevisiae, tannic acid resistance, iron deprivation, cytoplasmic petite mutant.

Download Full-text

New Types of Dissipative Streaming Instabilities

10.5772/intechopen.98901 ◽

2021 ◽

Author(s):

Eduard V. Rostomyan

Keyword(s):

Growth Rate ◽

Initial Perturbation ◽

Classical Problem ◽

Negative Energy ◽

Plasma Waveguide ◽

Limiting Current ◽

Maximal Growth ◽

Weak Beam ◽

Beam Plasma ◽

Maximal Growth Rate

Two new, previously unknown types of dissipative streaming instabilities (DSI) are substantiated. They follow from new approach, which allows solving in general form the classical problem of an initial perturbation development for streaming instabilities (SI). SI is caused by relative motion of the streams of plasma components. With an increase in level of dissipation SI transforms into a DSI. The transformation occurs because dissipation serves as a channel for energy removal for the growth of the negative energy wave of the stream. Until recently, only one type of DSI was known. Its maximal growth rate depends on the beam density nb and the collision frequency ν in the plasma as ∼nb/ν. All types of conventional beam-plasma instabilities (Cherenkov, cyclotron, etc.) transform into it. The solution of the problem of the initial perturbation development in systems with weak beam-plasma coupling leads to a new type of DSI. With an increase in the level of dissipation, the instability in these systems transforms to the new DSI. Its maximal growth rate is ∼nb/ν. The second new DSI develops in beam-plasma waveguide with over-limiting current of e-beam. Its growth rate ∼nb/ν. In addition, the solutions of abovementioned problem provide much information about SI and DSI, significant part of which is unavailable by other methods.

Download Full-text