A quadratic approach to allometry yields promising results for the study of growth

Julian Huxley (1924) came to the conclusion that intra-specific growth usually follows a sequence of power curves. So Huxley claimed that during growth sudden changes in the growth rate can occur. The restudy of his material, however, reveals that his observations closely follow single quadratic curves. As a result the intra-specific allometry studied by Huxley is comparable to ontogenetic allometry. The quadratic factor of the quadratic equations obtained, represents the growth rate; it shows the constant increase (positive factor) or decrease (minus factor) of one of the measurements for a constant increase in the other measurement with which it is compared. The quadratic factor explains the entire growth process and is the same for the smaller (younger) and larger (older) specimens. It could probably permit the prediction of the shape of larger and/or smaller animals not yet found, or give a clue to some evolutionary changes. By using the quadratic parabola there is no need to postulate “sudden changes in the growth curve” and so it appears that Huxley’s power curve can be abandoned.

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Effect of Fractal-Like Aggregation on Radiative Properties and Specific Growth Rate of Chlorella

Proceedings of the 15th International Heat Transfer Conference ◽

10.1615/ihtc15.rad.009531 ◽

2014 ◽

Author(s):

Zhen-Zong He ◽

Hong Qi ◽

Qin Chen ◽

Ya-Tao Ren ◽

Li-Ming Ruan

Keyword(s):

Growth Rate ◽

Specific Growth Rate ◽

Specific Growth ◽

Radiative Properties

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Effects of Mucin, Haemoglobin and Collagen on the Maximum Specific Growth Rate, Biomass and Hydrolytic Enzyme Production ofPorphyromonas gingivalisin Continuous Culture

Microbial Ecology in Health and Disease ◽

10.3402/mehd.v4i5.7714 ◽

1991 ◽

Vol 4 (5) ◽

Author(s):

T. Minhas ◽

J. Greenman ◽

A. G. Schaffer

Keyword(s):

Growth Rate ◽

Specific Growth Rate ◽

Continuous Culture ◽

Enzyme Production ◽

Specific Growth ◽

Hydrolytic Enzyme ◽

Maximum Specific Growth Rate

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Oscillating conditions for influencing the composition of mixed biological cultures

Water Science & Technology ◽

10.2166/wst.1998.0640 ◽

1998 ◽

Vol 37 (4-5) ◽

pp. 259-262 ◽

Cited By ~ 2

Author(s):

Bjarne R. Horntvedt ◽

Morten Rambekk ◽

Rune Bakke

Keyword(s):

Growth Rate ◽

Specific Growth ◽

Heterotrophic Bacteria ◽

Bacterial Species ◽

Rate Reduction ◽

Similar Strategy ◽

Sinusoidal Oscillations ◽

Specific Growth Rates ◽

Rate Limiting ◽

Concentration Levels

This paper presents a strategy in which mixed biological cultures are exposed to oscillating concentration levels, to improve the potential for coexistence of desired bacterial species. A mechanistic mathematical model is constructed to investigate and illustrate this strategy. This paper is focused on competition between nitrifying, denitrifying and aerobic heterotrophic bacteria in a CSTR with sludge recycle. For nitrifying and aerobic heterotrophic cultures, the effect of sinusoidal oscillations in DO levels with an amplitude of 1.0 mg/l is a 16% specific growth rate reduction compared to that at a constant DO level. The denitrifiers growth rate is increased by an average of 59%, compared to the constant DO level situation. A similar strategy has been tested in a pilot plant. It is concluded that the influence on specific growth rates is a function of the amplitude of the oscillations. The effects are greatest when concentrations fluctuate around the half saturation concentration of the rate limiting component(s).

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Understanding the Interaction Effects between Dietary Lipid Content and Rearing Temperature on Growth Performance, Feed Utilization, and Fat Deposition of Sea Bass (Dicentrarchus labrax)

Animals ◽

10.3390/ani11020392 ◽

2021 ◽

Vol 11 (2) ◽

pp. 392

Author(s):

Lydia Katsika ◽

Mario Huesca Flores ◽

Yannis Kotzamanis ◽

Alicia Estevez ◽

Stavros Chatzifotis

Keyword(s):

Growth Rate ◽

Body Weight ◽

Specific Growth ◽

Dicentrarchus Labrax ◽

Sea Bass ◽

Dietary Lipid ◽

Lipid Levels ◽

Final Body Weight ◽

Temperature Regimes ◽

Fish Group

This study was conducted to elucidate the interaction effects of temperature and dietary lipid levels (2 × 2 factorial experiment) on the growth performance, muscle, and liver composition in adult farmed European sea bass (Dicentrarchus labrax). Two groups of fish (190 g; 60 fish per group) were distributed in 12 tanks in triplicates and kept at two different temperature regimes; one starting at 23 °C and then changed to 17 °C for 61 days, and the other starting at 17 °C and then changed to 23 °C for 39 days. Two commercial diets containing both ~44% crude protein but incorporating different dietary lipid levels, 16.5% (D16) and 20.0% (D20) (dry matter (DM)), were fed to the fish to apparent satiation; the type of diet fed to each fish group remained constant throughout the experiment. Final body weight, weight gain, and specific growth rate were significantly higher for the fish group held at 23 °C compared to the fish group at 17 °C (before the temperature changes), while the dietary fat content did not have any profound effect in both groups. Furthermore, the different temperature regimes did not affect muscle or liver composition, but, on the contrary, dietary lipids affected hepatosomatic, perivisceral fat, and visceral indexes. Feed conversion ratio and specific growth rate were not affected by the dietary lipid level. An interaction of temperature and dietary lipid content was observed in daily feed consumption (DFC) and final body weight (FBW).

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Effects of cofD gene knock-out on the methanogenesis of Methanobrevibacter ruminantium

AMB Express ◽

10.1186/s13568-021-01236-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jian Ma ◽

Xueying Wang ◽

Ting Zhou ◽

Rui Hu ◽

Huawei Zou ◽

...

Keyword(s):

Growth Rate ◽

Specific Growth ◽

Production Capacity ◽

Maximum Amount ◽

Logarithmic Phase ◽

Wild Type ◽

Knock Out ◽

Maximum Biomass ◽

Reproductive Ability ◽

Methanobrevibacter Ruminantium

AbstractThis study aimed to investigate the effects of cofD gene knock-out on the synthesis of coenzyme F420 and production of methane in Methanobrevibacter ruminantium (M. ruminantium). The experiment successfully constructed a cofD gene knock-out M. ruminantium via homologous recombination technology. The results showed that the logarithmic phase of mutant M. ruminantium (12 h) was lower than the wild-type (24 h). The maximum biomass and specific growth rate of mutant M. ruminantium were significantly lower (P < 0.05) than those of wild-type, and the maximum biomass of mutant M. ruminantium was approximately half of the wild-type; meanwhile, the proliferation was reduced. The synthesis amount of coenzyme F420 of M. ruminantium was significantly decreased (P < 0.05) after the cofD gene knock-out. Moreover, the maximum amount of H2 consumed and CH4 produced by mutant were 14 and 2% of wild-type M. ruminantium respectively. In conclusion, cofD gene knock-out induced the decreased growth rate and reproductive ability of M. ruminantium. Subsequently, the synthesis of coenzyme F420 was decreased. Ultimately, the production capacity of CH4 in M. ruminantium was reduced. Our research provides evidence that cofD gene plays an indispensable role in the regulation of coenzyme F420 synthesis and CH4 production in M. ruminantium.

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CONTINUOUS CULTURE OF BRUCELLA ABORTUS S.19

Canadian Journal of Microbiology ◽

10.1139/m61-059 ◽

1961 ◽

Vol 7 (4) ◽

pp. 491-505 ◽

Cited By ~ 12

Author(s):

Andreas H. W. Hauschild ◽

Hilliard Pivnick

Keyword(s):

Growth Rate ◽

Continuous Culture ◽

Dilution Rate ◽

Brucella Abortus ◽

Specific Growth ◽

Limiting Factor ◽

Continuous Growth ◽

Viable Cells ◽

Metabolic Products ◽

Growth Of Bacteria

An apparatus is described for the continuous growth of bacteria. Brucella abortus S.19 has been grown in continuous culture for periods up to 3 weeks with populations up to 2 × 1011viable cells per ml and without the establishment of nonsmooth variants.Concentrations between 3 × 109and 2 × 1011cells per ml could be maintained as a function of the dilution rate without the requirement of a known limiting factor in the medium. In a series of steady-state conditions, the specific growth rate increased steadily up to 0.28 hour−1with decreasing population levels.Incidence of mutants was governed by the dilution rate and could also be reduced by various chelating substances.In continuous growth combined with continuous dialysis, population levels were approximately twice those obtained in continuous growth without dialysis. The effect of dialysis appears to be the continuous removal of growth-limiting metabolic products.

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