PHYSIOLOGICAL CHARACTERIZATION OF ADAPTIVE CLONES IN EVOLVING POPULATIONS OF THE YEAST, SACCHAROMYCES CEREVISIAE

Genetics ◽  
1985 ◽  
Vol 110 (2) ◽  
pp. 173-185
Author(s):  
Julian Adams ◽  
Charlotte Paquin ◽  
Paul W Oeller ◽  
Lester W Lee
Keyword(s):  
Glucose Uptake ◽  
Continuous Culture ◽  
Growth Parameters ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Yeast Saccharomyces Cerevisiae ◽  
Adaptive Mutations ◽  
Physiological Characterization ◽  
Evolving Populations

ABSTRACT Populations of a diploid strain of S. cerevisiae were grown in glucose-limited continuous culture for more than 260 generations. A series of seven sequential adaptive changes were identified by monitoring the frequency of cycloheximide resistance in these populations. Samples were taken from the continuous cultures following each adaptive shift and characterized physiologically to determine (1) the range of phenotypes that can be selected in a precisely defined constant environment and (2) the order and predictability of the occurrence of the adaptive mutations in evolving populations. The clones were characterized with respect to the growth parameters, maximum growth rate, saturation coefficient and yield, as well as for changes in cell size and geometry and rate of glucose uptake. The maximum growth rates of the seven adaptive clones were very similar, but in contrast the saturation coefficients differed substantially. Surprisingly, not all clones showed reductions in the saturation coefficients, in comparison to the immediately preceding clones, as would be predicted from classical continuous culture kinetics. In addition, yield estimates first increased and then decreased for later isolated adaptive clones. In general, the results suggest epistatic interactions between the adaptive clones, consistent with earlier published results. The rate of glucose uptake, as measured by 14Cxylose uptake, increased dramatically after the selection and fixation of seven adaptive clones. Progressive decreases in cell volume and changes in cell geometry, resulting in increased surface area to volume ratios, were also observed in the adaptive clones, but these changes were not always seen in other haploid and diploid yeast populations evolving under the same conditions. Such changes may be easily explainable in terms of the characteristics of the glucose-limited environment. The significance of the results to the evolution of microorganisms under nutrient-limiting conditions is discussed.

Isolation and Physiological Characterization of Thiothrix sp.

1994 ◽  
Vol 29 (7) ◽  
pp. 261-269 ◽  
Author(s):  
V. Tandoi ◽  
N. Caravaglio ◽  
D. Di Dio Balsamo ◽  
M. Majone ◽  
M. C. Tomei
Keyword(s):  
Growth Yield ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Yield Coefficient ◽  
Simultaneous Presence ◽  
Mixotrophic Growth ◽  
Physiological Characterization ◽  
South Italy ◽  
Mixotrophic Conditions

Thiothrix CT3 was isolated in pure culture by micromanipulation technique. The growth of this microorganism was analyzed in autotrophic, heterotrophic and mixotrophic conditions, in a bicarbonate-containing mineral medium supplemented with thiosulphate and/or acetate. Thiothrix CT3 was able to grow in all the conditions examined: the maximum growth rates estimated were 1.8, 2.5 and 2.5 d−1 respectively. The capacity of this organism to grow autotrophically, as supposed by Winogradsky in 1888, is a strong advantage over the other bacteria present in activated sludge, when sulphides are produced or carried by the sewer. Both the maximum growth rate and growth yield coefficient shown during heterotrophic and mixotrophic growth were comparable, indicating that the simultaneous presence of two substrates (acetate and a reduced sulphur compound) does not give it any particular advantage. The strong presence of Thiothrix spp. in many plants located in South Italy can be explained by the wide nutritional versatility of this filamentous bacterium.

scholarly journals Efficacy of Experimental Mouth Rinses on Caries-Related Biofilms in vitro

2021 ◽  
Vol 2 ◽  
Author(s):  
Josiana Steiger ◽  
Olivier Braissant ◽  
Tuomas Waltimo ◽  
Monika Astasov-Frauenhoffer
Keyword(s):  
Growth Rate ◽  
Antimicrobial Agents ◽  
Growth Parameters ◽  
Screening Method ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Screening Process ◽  
Mouth Rinses ◽  
Amine Fluoride

This study assessed the efficacy of tin and Polyethylenglycol (PEG-3) tallow aminopropylamine in different concentrations on Streptococcus mutans (S. mutans) biofilms to establish a new screening process for different antimicrobial agents and to gain more information on the antibacterial effects of these agents on cariogenic biofilms. Isothermal microcalorimetry (IMC) was used to determine differences in two growth parameters: lag time and growth rate; additionally, reduction in active biofilms was calculated. Experimental mouth rinses with 400 and 800 ppm tin derived from stannous fluoride (SnF2) revealed results (43.4 and 49.9% active biofilm reduction, respectively) similar to meridol mouth rinse (400 ppm tin combined with 1,567 ppm PEG-3 tallow aminopropylamine; 55.3% active biofilm reduction) (p > 0.05), while no growth of S. mutans biofilms was detected during 72 h for samples treated with an experimental rinse containing 1,600 ppm tin (100% active biofilm reduction). Only the highest concentration (12,536 ppm) of rinses containing PEG-3 tallow aminopropylamine derived from amine fluoride (AmF) revealed comparable results to meridol (57.5% reduction in active biofilm). Lower concentrations of PEG-3 tallow aminopropylamine showed reductions of 16.9% for 3,134 ppm and 33.5% for 6,268 ppm. Maximum growth rate was significantly lower for all the samples containing SnF2 than for the samples containing control biofilms (p < 0.05); no differences were found between the control and all the PEG-3 tallow aminopropylamine (p > 0.05). The growth parameters showed high reproducibility rates within the treated groups of biofilms and for the controls; thus, the screening method provided reliable results.

scholarly journals Sex-specific growth of nestlings of the Whiskered Tern Chlidonias hybrida, a species with sexual size dimorphism and female brood desertion

2021 ◽  
Author(s):  
Agata Banach ◽  
Grzegorz Neubauer ◽  
Adam Flis ◽  
Mateusz Ledwoń
Keyword(s):  
Growth Rate ◽  
Body Mass ◽  
Sexual Size Dimorphism ◽  
Growth Parameters ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Head Length ◽  
Whiskered Tern ◽  
Total Head ◽  
Chlidonias Hybrida

AbstractThe growth of a nestling during the first few weeks after hatching is crucial for its further life and is sensitive to the conditions experienced during this period. Among species exhibiting Sexual Size Dimorphism (SSD), one of the most important factors influencing growth parameters is the sex of the hatchlings. In this study, we tested whether sex and other factors (hatching date, egg volume, brood size and sex ratio in the brood) were related to sex on growth parameters in Whiskered Tern (Chlidonias hybrida) chicks. In this species, males are 3%–10% larger than females when adult. At hatching, only the total head length was greater in males than females, but values close to fledging were greater for most of the measured parameters (3%—tarsus, 4%—total head length, 13%—body mass). Moreover, the maximum body mass growth rate was higher in males but females entered the rapid growth phase somewhat earlier and achieved the final total head length sooner. Nestling growth was also significantly correlated with brood size and hatching date, though mostly negatively (e.g. lower tarsus and total head length asymptote, lower maximum growth rate and growth rate constant of total head length in bigger and later clutches). The occurrence of SSD during the nestling period and higher maximum growth rate of body mass in males indicates that the costs of raising sons may be higher than of raising daughters. However, we did not find evidence of either sex-biased nestling mortality or skewed sex ratio.

Comparison of Enrichment Broths for the Recovery of Healthy and Heat-Injured Salmonella Typhimurium on Raw Duck Wings

2013 ◽  
Vol 76 (11) ◽  
pp. 1963-1968 ◽  
Author(s):  
QIANWANG ZHENG ◽  
CAROLINE BUSTANDI ◽  
YISHAN YANG ◽  
KEITH R. SCHNEIDER ◽  
HYUN-GYUN YUK
Keyword(s):  
Growth Rate ◽  
Salmonella Typhimurium ◽  
Doubling Time ◽  
Growth Parameters ◽  
False Negative ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Detection Methods ◽  
Lag Phase ◽  
Peptone Water

This study was performed to optimize Salmonella Typhimurium recovery from raw duck wings with five nonselective broths (buffered peptone water, tryptic soy broth, lactose broth, universal preenrichment broth, nutrient broth) and four selective broths (selenite broth, BAX System MP media [MP], Salmonella AD media [AD], ONE broth-Salmonella [OB]). Healthy or heat-injured (50 and 85% injury) cells were inoculated at a level of 102, 101, or 100 CFU/25 g on raw duck wings. Growth was modeled using DMfit with four growth parameters: lag-phase duration, maximum growth rate, doubling time, and maximum population density. Most enrichments were able to recover Salmonella Typhimurium to greater than 6 log CFU/ml. AD, MP, and OB had significantly (P < 0.05) higher maximum growth rate (0.9 to 1.0/h) and lower doubling time (0.7 to 0.8 h). Buffered peptone water, AD, MP, and OB recovered healthy and 50%-injured cells at low inoculum levels to more than 6.0 log CFU/ml; OB achieved the greatest recovery (7.6 and 7.9 log CFU/ml), following 24 h of incubation. The 85%-injured cells at 100 and 101 CFU/25 g, however, were only recovered in OB, reaching 7.3 and 7.5 log CFU/ml, respectively. These results suggest that OB may be an appropriate enrichment broth for the recovery of Salmonella Typhimurium from raw duck wings in standard diagnostic tests or other rapid detection methods, to avoid false-negative results.

A model of individual variation in the food conversion efficiency and other growth parameters of grazing beef cattle in the tropics

1988 ◽  
Vol 39 (5) ◽  
pp. 943 ◽  
Author(s):  
S Saithanoo ◽  
ME Goddard
Keyword(s):  
Growth Rate ◽  
Heat Stress ◽  
Genetic Correlation ◽  
Individual Variation ◽  
Growth Parameters ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Tropical Pastures ◽  
Maintenance Requirement ◽  
Mature Size

Methods to genetically improve gross food efficiency (GFE) in cattle usually rely on a high genetic correlation between GFE and growth rate. Estimating this genetic correlation for cattle grazing tropical pastures is extremely difficult, so a model of individual variation in growth has been developed based on component traits which are known to affect growth rate. The model assumes that there is individual variation in mature size, maintenance requirement, intake to maintenance ratio, and susceptibility to heat stress and to tick and worm infestation. Nutritional level is assumed to interact with maintenance requirement, so that under good nutrition a high level of maintenance requirement maximises growth rate, whereas under a low level of nutrition a low maintenance requirement leads to maximum growth rate. The model predicts that in the presence of environmental stress the correlation between growth rate and mature size is only about 0.5, and there is no correlation between mature size and GFE. Growth rate and GFE are correlated with resistance to parasite and heat stress and to intake:maintenance ratio. Consequently growth rate and GFE are highly correlated, especially under stressful environmental conditions. The model predicts that growth rate in one environment will be highly genetically correlated with growth rate in other similar environments.

Optimisation of Epitaxial Layer Growth by Schottky Diodes Electrical Characterization

2006 ◽  
Vol 527-529 ◽  
pp. 199-202 ◽  
Author(s):  
Francesco La Via ◽  
G. Galvagno ◽  
A. Firrincieli ◽  
Fabrizio Roccaforte ◽  
Salvatore di Franco ◽  
...  
Keyword(s):  
Epitaxial Layer ◽  
Growth Parameters ◽  
Schottky Diodes ◽  
Electrical Characterization ◽  
Maximum Growth ◽  
Deposition Process ◽  
Maximum Growth Rate ◽  
Layer Growth ◽  
Epitaxial Layers ◽  
Dilution Ratio

The influence of the epitaxial layer growth parameters on the electrical characteristics of Schottky diodes has been studied in detail. Several diodes were manufactured on different epitaxial layers grown with different Si/H2 ratio and hence with different growth rates. From the electrical characterization a maximum silicon dilution ratio can be fixed at 0.04 %. This limit fixes also a maximum growth rate that can be obtained in the epitaxial growth, with this process, at about 8 μm/h. Several epitaxial layers have been grown, using this dilution ratio, with different temperatures (1550÷1650 °C). At 1600 °C the best compromise between the direct and the reverse characteristics has been found. With this process the yield decreases from 90% for a Schottky diode area of 0.25 mm2 to 61% for the 2 mm2 diodes. Optimizing the deposition process to reduce the defects introduced by the epitaxial process, yield of the order of 80% can be reached on 1 mm2 diodes.

Maturation of White Sucker, Catostomus commersoni, Populations in Ontario

1994 ◽  
Vol 51 (9) ◽  
pp. 2066-2076 ◽  
Author(s):  
Y. Chen ◽  
H. H. Harvey
Keyword(s):  
Growth Rate ◽  
Robust Regression ◽  
Growth Parameters ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Population Variation ◽  
Linear Regression Method ◽  
White Sucker ◽  
Catostomus Commersoni ◽  
Fitting Length

White sucker, Catostomus commersoni, were sampled from 13 Ontario lakes. Two growth parameters (growth rate in length as dL/dt at age t0 and age at maximum growth rate in weight as dW/dt) were estimated by fitting length- and weight-at-age data to the two reparameterized von Bertalanffy growth functions for each of 13 populations. Two maturation parameters (length and age at 50% maturity, ML and MA) were estimated using the linear regression method for both sexes. Two regression approaches were used in analyzing experimental data: a traditional geometric means (GM) method and a two-step procedure of robust regression analysis which includes applying the least median squares method to identify possible outliers and applying the GM method to data exclusive of the defined outliers. Great among-population variation in the estimated growth and maturation parameters was observed for both female and male white sucker. White sucker growing faster at young ages tended to mature earlier. High population density might result in white sucker having slower growth rates in their earlier ages and larger MA's. This study indicated that maturation of white sucker is food dependent, and early growth rate is an important factor in determining the timing of maturity.

scholarly journals Characterization of Listeria monocytogenes Originating from the Spanish Meat-Processing Chain

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 542 ◽  
Author(s):  
Rosa Capita ◽  
Amanda Felices-Mercado ◽  
Camino García-Fernández ◽  
Carlos Alonso-Calleja
Keyword(s):  
Listeria Monocytogenes ◽  
Clinical Importance ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Meat Processing ◽  
Hygiene Practices ◽  
Adhesion Ability ◽  
Listeria Ivanovii ◽  
Good Hygiene

Using agglutination techniques, 118 Listeria monocytogenes isolates from red meat and poultry were serotyped. Strains were ascribed to the serotypes 4b/4e (44.1% of the strains), 1/2 (a, b or c; 28.0%), 4c (6.8%), 4d/4e (5.9%) and 3 (a, b or c; 2.5%). Among these are the serotypes most frequently involved in cases of human listeriosis. The susceptibility of 72 strains to 26 antibiotics of clinical importance was determined by disc diffusion (Clinical and Laboratory Standards Institute; CLSI). High levels of resistance were observed to cefoxitin (77.8% of the strains showed resistance), cefotaxime (62.5%), cefepime (73.6%), and nalidixic acid (97.2%), nitrofurantoin (51.4%) and oxacillin (93.1%). Less than 3% of the strains showed resistance to the antibiotic classes used in human listeriosis therapy (i.e., ampicillin, gentamicin, rifampicin, chloramphenicol, enrofloxacin, vancomycin, trimethoprim-sulfamethoxazole, erythromycin, and tetracycline). The influence of species and serotype on the growth kinetics (modified Gompertz equation) and on the adhesion ability (crystal violet staining) of nine isolates of L. monocytogenes (serotypes 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, and 4d), and one strain of Listeria ivanovii were investigated. The maximum growth rate (ΔOD420-580/h) varied between 0.073 ± 0.018 (L. monocytogenes 1/2a) and 0.396 ± 0.026 (L. monocytogenes 4b). The isolates of L. monocytogenes belonging to serotypes 3a and 4a, as well as L. ivanovii, showed a greater (p < 0.05) biofilm-forming ability than did the remaining strains, including those that belong to the serotypes commonly implied in human listeriosis (1/2a, 1/2b, 1/2c and 4b). The need for training in good hygiene practices during the handling of meat and poultry is highlighted to reduce the risk of human listeriosis.

CHARACTERIZATION Of Bi-BASED WHISKERS BY THE METHOD OF Al2O3-SEEDED GLASSY QUENCHED PLATELETS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4497-4501 ◽  
Author(s):  
S. KISHIDA ◽  
H. UEMOTO
Keyword(s):  
Full Width Half Maximum ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Previous Method ◽  
Full Width ◽  
Temperature Transition ◽  
High Quality ◽  
Maximum Value ◽  
Good Crystallinity

We prepared the Bi 2 Sr 2 Ca n-1 Cu n O y (Bi-based) whiskers by the method of Al 2 O 3-seeded by the method was about 3 times larger than that by the previous method glassy quenched platelets (ASGQP). The maximum growth rate of the whiskers obtained without any Al 2 O 3 seeding. From the resistance-temperature (R-T) characteristics, we found that the temperature transition widths of the Bi-2212 and the Bi-2223 phases were about 2K and 4K, respectively. In addition, the whiskers showed that the FWHM (full-width-half-maximum) value of the (0010) XRD peak was less than 0.06°. The critical current density of the whiskers was more than 104 A/cm 2 at 60K and 0T. The results indicate that the whiskers grown by the ASGQP method have good crystallinity and high quality.

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