scholarly journals THE NATURE OF THE FACTORS WHICH DETERMINE THE SEQUENCE OF GROWTH-CYCLES AND ITS RELATIONSHIP TO THE DIFFERENTIATION OF TISSUES

1929 ◽  
Vol 12 (3) ◽  
pp. 329-344
Author(s):  
T. Brailsford Robertson
Keyword(s):  
Chemical Method ◽  
Nuclear Material ◽  
Growth Cycle ◽  
White Mouse ◽  
Predominant Role ◽  
Growth Cycles ◽  
Velocity Constant ◽  
Multicellular Animal ◽  
Growing Period ◽  
Growth Of Animals

1. It has previously been shown by the author and many others that growth, in animals and plants, is an autocatalysed process. In animals it is usual to find that growth occurs in several superimposed autocatalytic cycles. In many cases, in plants and animals, especially if the cycle is one which occupies a large proportion of the growing period, it is found that the velocity-constant of the autocatalysed monomolecular formula falls off as growth proceeds, at first rapidly and later more slowly. 2. It has previously been shown by the author that the fall of the velocity-constant of growth, in the white mouse, is directly proportional to the fall of the nucleo-cytoplasmic ratio, determined by the chemical method of Le Breton and Schaeffer. If we assume this relationship to be generally applicable to the growth of animals and plants, then the following additional conclusions may be deduced, without calling in the aid of any other assumption:— 3. The increase of cytoplasm in any given cycle of growth is proportional to the concurrent increase of nuclear material. 4. The growth of cytoplasm takes place in accordance with a monomolecular formula in which the velocity-constant varies directly as the mass of the nucleus. If we superadd to these facts and deductions the hypothesis that each growth-cycle represents the growth of a separate group of cells within the animal, then the additional conclusions follow:— 5. That the cells which participate in the growth composing any cycle have initially lower nucleo-cytoplasmic ratios than the cells which participated in the preceding cycles. 6. That cells of large nucleo-cytoplasmic ratios in a multicellular animal inhibit the growth of cells which possess smaller ratios. 7. These conclusions collectively imply that the nucleus plays a predominant role in determining the development of the cell in which it resides.

scholarly journals THE ANALYSIS OF THE GROWTH OF THE NORMAL WHITE MOUSE INTO ITS CONSTITUENT PROCESSES

1926 ◽  
Vol 8 (5) ◽  
pp. 463-507 ◽  
Author(s):  
T. Brailsford Robertson
Keyword(s):  
Growth Velocity ◽  
Maximum Growth ◽  
Growth Cycle ◽  
White Mouse ◽  
Growth Cycles ◽  
Velocity Constant ◽  
The Third ◽  
Loss Of Weight ◽  
Males And Females ◽  
Autocatalytic Growth

1. The several growth-cycles which are distinguishable in the growth of an animal or plant are mutually independent in that they do not share a common catalyser. 2. The growth of the white mouse has been shown to consist of three autocatalytic processes and one "linear process" of weight-accretion. The parameters of these processes have been evaluated for one strain and generation of mice. 3. The first and most extensive autocatalytic process is asymmetrical, being defined by an equation of the type: See PDF for Equation The second and third cycles, which are more rapid and do not begin to affect the growth of the animal until a later stage of development, are symmetrical, being defined by equations of the type: See PDF for Equation 4. The amplitude of the first autocatalytic growth-cycle in the mouse is almost the same in males and females, but the moment of maximum growth-velocity in the female anticipates that in the male, the velocity constant is smaller in the female, and the asymmetry estimated by the magnitude of the constant B, is greater in the female than in the male. 5. The amplitude of the second cycle is almost the same in males and females, but data are as yet lacking which would enable us to ascertain whether the velocity-constant and moments of maximum growth-velocity in this cycle differ in the two sexes or not. 6. The amplitude of the third cycle is much less in the female than in the male, and this difference of amplitude almost wholly accounts for the difference of adult weight in the two sexes. The velocity-constant of the third cycle is, however, greater in the female than in the male. Maximum growth velocity due to this cycle is attained at very nearly the same age in both sexes. 7. The origin of asymmetry in autocatalytic growth-processes is discussed. It is pointed out that asymmetry might originate in a progressive diminution of the velocity-constant. If this is the origin of the asymmetry of the first growth-cycle in the mouse, then it is shown that the velocity constant of autocatalysis in this cycle must be very nearly proportional to the nucleo-cytoplasmic ratio, as estimated by the chemical method of Le Breton and Schaeffer. 8. It is pointed out that no reliable measure of senescent loss of weight is available at present. It is shown that removal or decay of those conditions which initially maintain the separability of the growth-cycles which collectively constitute the growth of the white mouse would necessarily result in loss of weight.

scholarly journals Changes in alfalfa cell wall structure during vegetation

2014 ◽  
Vol 59 (3) ◽  
pp. 275-286
Author(s):  
Aleksa Bozickovic ◽  
Goran Grubic ◽  
Nenad Djordjevic ◽  
Bojan Stojanovic
Keyword(s):  
Cell Wall ◽  
Crude Protein ◽  
Growth Cycle ◽  
Wall Structure ◽  
Growth Cycles ◽  
Growing Period ◽  
Acid Detergent Lignin ◽  
Constant Content ◽  
Acid Detergent Fibre ◽  
Daily Changes

The investigation was done on 141 samples of one alfalfa cultivar, collected from the same location during the first three growth cycles: spring growth, the first and the second regrowth. Within each growth cycle, sampling was done during the whole growing period, commencing when plant height was below 150 mm and continuing until plants were bearing ripe seeds. On all collected samples the following cell wall characteristics were determined: neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent insoluble crude protein (NDICP), acid detergent insoluble crude protein (ADICP). Cellulose and hemicellulose were detected on the base of the mentioned chemical parameters. Significantly lower (p<0.01) content of aNDF, ADF, ADL, ADICP and cellulose is found in the second regrowth, while there were no significant differences between the other two growth cycles. Except in NDICP and ADICP, the increase in all accompanying components of the cell wall was observed, and expressed in average daily changes. There was no consistent trend in NDICP and ADICP. During the spring growth from late bud to full-bloom stage the ?plateau? was observed. The plateau was represented as almost constant content of aNDF, ADF, ADL and cellulose. The correlations between all components of the cell wall were shown. The equation aNDF = 36.713 + 1.181 ? ADF is recommended for conversion of ADF into aNDF in alfalfa.

scholarly journals Effects of feeding antibiotics to growing and breeding mice

1969 ◽  
Vol 3 (1) ◽  
pp. 1-6
Author(s):  
J. O. L. King
Keyword(s):  
Litter Size ◽  
Tap Water ◽  
Laboratory Strain ◽  
White Mouse ◽  
Early Age ◽  
Growing Period

Mice of two strains (a laboratory strain of white mouse and a fancy strain of coloured mouse) were fed on a proprietary cubed diet and were given to drink tap water, or water containing 26 mg per litre of one of the following antibiotics: chortetracycline hydrochloride, ampicillin, or tylosin tartrate. In the first experiment growing mice were given these diets for 8 weeks from 4 weeks of age. Ampicillin produced weight increases in both strains (significant in the white mice), chlortetracycline produced an increase in the coloured mice and a reduction in the white mice, while tylosin reduced weight increases in both strains. The results of fortnightly weighings of the control mice and those receiving ampicillin showed that in the coloured mice the effect was marked at an early age, while in the white mice it tended to spread over the growing period. In a second experiment with breeding mice, using does of both strains, ampicillin increased litter size in both strains (significantly in the case of the coloured mice), chlortetracycline increased litter size in the white mice only, and tylosin did so in the coloured mice only. All three antibiotics increased litter birth weights in coloured mice (ampicillin significantly), but reduced them in white mice. Weight increases from birth to weaning of selected groups of 8 mice showed that antibiotics had little effect in the white mice, and that ampicillin and tylosin improved the rate of gain in the coloured mice (ampicillin significantly).

Regrowth and flowering in sweet orange after pruning

1973 ◽  
Vol 24 (1) ◽  
pp. 101 ◽  
Author(s):  
GI Moss
Keyword(s):  
Sweet Orange ◽  
Practical Investigations ◽  
Growth Cycle ◽  
Growth Cycles ◽  
The Third ◽  
Second Growth ◽  
Subsequent Flowering ◽  
Orange Trees ◽  
Practical Implications ◽  
Cool Conditions

Sweet orange trees, cv. Late Valencia, 6 m in height were moderately pruned in the spring of 1969, up to 8 % of the canopy being removed. Over 2 years, three or four growth cycles were completed. The amount of regrowth was correlated with the size of the first growth cycle flush after pruning, and this was correlated with the diameter of the pruned branch. No flowers were found on regrowths 1 year after pruning; only 75% of regrowths produced flowers 2 years after pruning, and only 50 % produced fruit. Small plants (rooted cuttings) were used to investigate pruning responses in the phytotron. Low temperatures (18/13�C) immediately after pruning for 8 weeks resulted in smaller first growth cycle flushes after pruning, and even after transfer to warm (27/22�) conditions the original height was not regained after three growth cycles. Plants that received cool conditions after the first or second growth cycles regained their original height after the third growth cycle. The amount of regrowth was correlated with the length of the first growth cycle flushes, which was correlated with the original height of the plants and the height after pruning. Flowers could not be induced on the old wood after pruning or on the first growth cycle flushes, and only few flowers were formed in the second growth cycle flushes. Many inflorescences were produced on third growth cycle flushes following inductive conditions (18/13�C) for 8 weeks. Light pruning of less vigorous plants did not inhibit subsequent flowering. The practical implications of this work are discussed. Moderate pruning will remove part of two crops, not one, because of the inability of regrowth flushes to flower until several growth cycles have formed. The tree relatively quickly replaces the growth removed, and this depends on the vigour of the first growth cycle flushes after pruning. Pruning in autumn or winter would be expected to result in less vigorous regrowth. Our lack of knowledge on the pruning responses of orange trees is emphasized, with suggestions for future practical investigations.

scholarly journals ANALYSIS OF ECONOMIC GROWTH CYCLES’ SYMMETRY IN THE MAIN ECONOMIC SECTORS OF EURO AREA COUNTRIES

Ekonomika ◽  
2012 ◽  
Vol 91 (4) ◽  
Author(s):  
Brigita Šidlauskaitė ◽  
Norbertas Balčiūnas
Keyword(s):  
Economic Growth ◽  
Monetary Policy ◽  
Euro Area ◽  
Value Added ◽  
Growth Cycle ◽  
The European Union ◽  
Economic Sectors ◽  
Growth Cycles ◽  
The Common ◽  
Optimum Currency

Abstract. With the European Union integration growing deeper and Euro area countries having the common currency, excluding possibility of a national monetary policy, academic society has raised a debate on economic stabilization opportunities in individual Euro area countries in case the common monetary policy would prove to be adverse. According to the optimum currency area theory, one of the necessary conditions for the successful functioning of the monetary union is the homogeneity of its countries. The possible economic shocks could have a different impact on the economy of individual Euro area countries in the presence of significant differences in their economy structure. Applying the Hodrick–Prescott method, this study identifies and analyses economic growth cycles in the main economic sectors of the Euro area countries. The results suggest that not all economic growth cycles of the Euro area countries sufficiently correlate with the Euro area average, and one of the predetermining factors is the differences in the economic structure.Key words: asymmetry of economic growth cycle, Euro area, value added structure

Anaerobic Detoxification of a Chemi-Thermomechanical Pulp Effluent by Two Acclimating Sludges

1994 ◽  
Vol 29 (4) ◽  
pp. 471-486 ◽  
Author(s):  
Alain Patoine ◽  
Raynald Côté ◽  
Marcel Paquet
Keyword(s):  
Acid Concentration ◽  
Resin Acid ◽  
Granular Sludge ◽  
Growth Cycle ◽  
Bacterial Degradation ◽  
Thermomechanical Pulp ◽  
Batch Reactors ◽  
Toxic Substances ◽  
Growth Cycles ◽  
Major Toxicity

Abstract Detoxification of a chemi-thermomechanical pulp effluent (CTMP) was examined by monitoring toxicity and resin acid concentration during treatment in batch reactors. Two treatments were carried out — one performed with an industrial granular sludge and the other with a municipal anaerobic digester sludge. The two sludges were acclimated to the CTMP effluent by successive 6-day suspended growth cycles on fresh effluent. In both cases, several growth cycles showed resin acid and toxicity increases, probably caused by resin acid desorption from bacterial cell walls to the aqueous phase. Detoxification of the effluent was achieved with both sludges during the last growth cycle. Since measurements were performed on filtered samples, the observed decreases of toxicity and resin acid concentration may be the result of bacterial degradation or of adsorption of toxic substances on particulate matter. Major increases of resin acid were associated with major toxicity increases within one given growth cycle.

Relationships between size of stream insects and current velocity

1978 ◽  
Vol 56 (2) ◽  
pp. 178-186 ◽  
Author(s):  
William P. Kovalak
Keyword(s):  
Life History ◽  
Habitat Selection ◽  
Dry Weight ◽  
Growth Cycle ◽  
Head Width ◽  
Differential Growth ◽  
Growth Cycles ◽  
Frequency Distributions ◽  
Stream Insects ◽  
History Of

Size frequency distributions and dry weight – head width relationships for six insect species from two habitats with differing current velocities in the Pigeon River, Michigan, were compared. Early in their growth cycles, Ephemerella subvaria, Ephemerella lata, Rhithrogena jejuna, and Glossosoma nigrior generally were larger at the slow station, but near the end of the growth cycles they generally were larger at the fast station. For Paraleptophlebia mollis, early in the growth cycle size differences between stations were small but near the end of the growth cycles nymphs were larger at the fast station, whereas nymphs of Ephemerella deficiens were slightly larger at the slow station throughout the growth cycle. Larger size at the slow station probably was due to differential growth whereas larger size at the fast station probably was due to differential habitat selection controlled by oxygen requirements.There were no significant differences in dry weight – head width relationships between habitats or between sexes. Sex ratios generally were similar at the two stations and did not deviate appreciably from 50:50.The life history of each species is briefly described.

Growth of loblolly pine rooted cuttings compared with seedlings

1987 ◽  
Vol 17 (2) ◽  
pp. 157-164 ◽  
Author(s):  
G. S. Foster ◽  
C. C. Lambeth ◽  
M. S. Greenwood
Keyword(s):  
Loblolly Pine ◽  
Confounding Factor ◽  
Growth Cycle ◽  
Early Years ◽  
Rooted Cuttings ◽  
Rooted Cutting ◽  
Growth Cycles ◽  
Age Related ◽  
The Family ◽  
Number Of Branches

Growth and morphology of loblolly pine (Pinustaeda L.) rooted cuttings were compared with that for seedlings after several years in the field in two experiments. Experiment 1 included rooted cuttings from 1- and 5-year-old ortets and seedlings from the same five families and experiment 2 compared rooted cuttings from 4-year-old ortets with seedlings from the same 15 families. Significant age-related effects on the growth of the rooted cuttings, even with as little as 4 years difference in ortet age, were observed. Height, DBH, and number of growth cycles, but not number of branches per unit of height or per growth cycle, differed significantly between the two cutting sources. Size and condition of the rooted cuttings and seedlings at the time of planting influenced their growth for several years afterward and could be a confounding factor in comparisons among propagule types. In experiment 1 cuttings outgrew seedlings, while in experiment 2 the reverse occurred. Considering both experiments, growth in the early years seems to be related more to condition of the propagule rather than asexual or sexual origin when unconfounded with age. The family rank correlations between propagation types for the same trait were always positive but were significant for only part of the traits, while the correlations among traits for the same propagation type were generally, but not always, lower for rooted cuttings than seedlings. This effect was pronounced in the first few years after field planting and was likely the result of plant quality (variability induced by the rooting and conditioning system) rather than propagation type; nonetheless, there is cause for concern when using early field data from rooted cutting trials to rank family performance.

Nucleic acid and protein content during the growth cycle of Pseudomonas fluorescens, Methanomonas methanica and of a sporing bacillus

1963 ◽  
Vol 157 (969) ◽  
pp. 574-586 ◽  
Keyword(s):  
Amino Acids ◽  
Protein Content ◽  
Pseudomonas Fluorescens ◽  
Cell Size ◽  
Growth Medium ◽  
Bacillus Coagulans ◽  
Growth Cycle ◽  
Growth Cycles ◽  
Protein Mass ◽  
Pass Through

The variations in the cell size and in the RNA, DNA and protein content during the growth cycles of Pseudomonas fluorescens, Methanomonas methanica and of a sporing bacillus (‘ C ’) which has some of the characteristics of Bacillus coagulans (Hammer), are reported. The results are discussed in terms of those obtained previously with Bacterium lactis aerogenes ( Aerobacter aerogenes ). The most striking behaviour is found in the DNA /mass which not only remains relatively constant during the major part of the growth cycle of all the strains, but varies little from strain to strain. With Ps. fluorescens the cell size is nearly constant during the growth cycle so that here DNA /cell is also relatively constant. With M. methanica and with ' C ' the cell size passes through a maximum early in the cycle. The addition of a complete mixture of amino acids to the growth medium speeds up the rate of growth of Ps. fluorescens : the cell size and the DNA /cell now pass through maxima, but DNA /mass is hardly affected although the maxima in RNA /mass and protein/mass are augmented. This pattern of behaviour of DNA /mass is also seen with Bact. lactis aerogenes when supplements such as amino acids, vitamins or metabolites are added to the growth medium. Here again, although the levels of the cell size, RNA /mass and protein/mass, were affected to varying degrees, DNA /mass was practically normal. In the unsupplemented medium the levels of RNA /mass and protein/mass for Ps. fluorescens , M. methanica and ‘ C ' agree more closely with the equilibrium (continuous culture) levels for Bact. lactis aerogenes than with the values obtained during a growth cycle.

Wool growth cycles in Soay sheep

1971 ◽  
Vol 76 (1) ◽  
pp. 183-197 ◽  
Author(s):  
M. L. Ryder
Keyword(s):  
Annual Cycle ◽  
Growth Cycle ◽  
Control Mechanisms ◽  
Growth Cycles ◽  
Soay Sheep ◽  
Wool Growth ◽  
The One ◽  
Two Peaks ◽  
Actual Loss ◽  
Skin Samples

SUMMARYThe wool growth cycle in six rams and eight ewes was studied by taking monthly coat and skin samples for 3 years from each. Coat length was measured, and the percentage of inactive follicles was noted as well as the percentage of medullated fibres.In the spring moult ‘mainland’ sheep (stock removed from St Kilda 60 years ago) cast less completely than ‘St Kilda sheep’ (Soays removed more recently from St Kilda). Mainland rams cast less than the ewes, but St Kilda rams began casting earlier, and completed casting more quickly than the ewes. Despite differences between years in the rate of casting, similarities in the pattern of casting were observed between years in the same animal, and between parent and offspring.This apparent annual cycle was confirmed by graphs of follicle inactivity which showed that most inactivity occurred from September to March in the rams, and from October to April in the ewes. It was possible to fit sin and cos waves of 12-month duration to the graphs and further analysis revealed superimposed a 6-month cycle in one group, and a 4-month cycle in another group, which were associated with subsidiary peaks of inactivity in the summer. There were suggestions of a cycle about 2 months in length throughout the year, and sin waves of this duration could be fitted to the data from one of the groups of ewes. Possible control mechanisms for the annual and shorter cycles are discussed.Peaks of follicle inactivity were frequently followed by troughs in coat length which suggested actual loss of the longest fibres.Medullation was absent or minimal from December to March, and there were two peaks during the period of maximum medullation, that in the spring being greater than the one in the autumn.

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