scholarly journals Development and population growth of Hydra viridissima Pallas, 1766 (Cnidaria, Hydrozoa) in the laboratory

2008 ◽  
Vol 68 (2) ◽  
pp. 379-383 ◽  
Author(s):  
FC. Massaro ◽  
O. Rocha
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Generation Time ◽  
Doubling Time ◽  
Test Organism ◽  
Laboratory Culture ◽  
Individual Growth ◽  
Population Doubling ◽  
Population Doubling Time ◽  
The Individual

Hydras, the most representative freshwater Cnidaria, are of common occurrence in bodies of water in every continent except Antarctica. This study was planned with the aim of maintaining a population of Hydra viridissima in laboratory culture to enable the determination of the individual and population growth-rates of this species, as well as its population doubling time and generation time, with a view to employing these common animals as test-organisms in ecotoxicological assays. The organisms were maintained in reconstituted water at 20 ± 2 °C, illuminated at 800 lux with a photoperiod of 12 hours light: 12 hours dark, and were fed on neonates of the cladoceran Ceriodaphnia silvestrii (3 or 4 neonates per hydra, 3 times a week). The individual growth-rate (k) of the species was 0.43, the maximum length of the column 2.53 mm and the generation time 6.6 ± 1.5 days on average. The hydra population showed an intrinsic growth-rate (r) of 0.0468, according to the fitted curve, and a doubling time of 14.8 ± 2.63 days. Hydra viridissima is easy to grow in the laboratory and performs well in the conditions used in this study. It is thus a promising candidate test-organism for ecotoxicological studies.

Creating our Future — Some Concerns of an Environmentalist

1994 ◽  
Vol 1 (1) ◽  
pp. 83-86
Author(s):  
George Lewis
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Rapid Growth ◽  
Human Population ◽  
Doubling Time ◽  
Gold Coast ◽  
Population Doubling ◽  
Western World ◽  
Population Doubling Time ◽  
The Media

Australia is often described as having the fastest human population growth in the western world at 1.4 per cent per annum (ABS 1993). Queensland's growth rate in comparison is 2.52 per cent while the Gold Coast is currently experiencing 6.1 per cent which is equivalent to a population doubling time of 11 years. While such rapid growth is lauded in the media and discussed in glowing terms by economists, engineers and entrepreneurs, there are many others who in recent years have queried the wisdom of such rapidly increasing growth. In 1992 a group calling themselves The Union of Concerned Scientists, ‘comprising 1575 scientists from 69 countries, including a majority of Nobel laureates’ (Caswell 1) issued a ‘Warning to Humanity’ regarding the accelerating damage threatening humanity's global support systems. According to this group, ‘no more than one or a few decades remain before the chance to avert the threats we now confront will be lost and the prospects for humanity immeasurably diminished’. They refer specifically to over-consumption, poverty and spiralling populations: all of which we have in south-east Queensland.

scholarly journals Linking lineage and population observables in biological branching processes

2019 ◽  
Author(s):  
Reinaldo García-García ◽  
Arthur Genthon ◽  
David Lacoste
Keyword(s):  
Population Dynamics ◽  
Generation Time ◽  
Doubling Time ◽  
Branching Processes ◽  
Underlying Mechanism ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Division Rate ◽  
Fluctuation Theorems ◽  
The Mean

Using a population dynamics inspired by an ensemble of growing cells, a set of fluctuation theorems linking observables measured at the lineage and population levels are derived. One of these relations implies inequalities comparing the population doubling time with the mean generation time at the lineage or population levels. We argue that testing these inequalities provides useful insights into the underlying mechanism controlling the division rate in such branching processes.

scholarly journals Morphological and functional characteristics of cell culture derived from the mouse nail unit

2017 ◽  
Vol 5 (1) ◽  
pp. 62-66
Author(s):  
O. Kalmukova ◽  
A. Ustymenko ◽  
T. Lutsenko ◽  
P. Klymenko ◽  
V. Kyryk
Keyword(s):  
Cell Culture ◽  
Growth Rate ◽  
Doubling Time ◽  
Cultured Cells ◽  
Primary Cultures ◽  
Population Doubling ◽  
Synthetic Activity ◽  
Population Doubling Time ◽  
Proliferative Potential

Nail unit is a complex anatomical structure that is capable of rapid growth and regeneration throughout the life. Such significant reparative potential is associated with the presence different types of stem and progenitor cells, whose biology remains one of the fundamental issues today. Taking into account the active search for new stem cell sources for cell therapy, the view of the nail unit as a potential site for the localization of undifferentiated cells with stem potency is topical problem.Purpose. The study was conducted with an objective to establish the morphological, morphometric and proliferative characteristics of cultured cells isolated from the mouse nail unit.Materials and methods. Primary cultures of cells were obtained from tissue sampling, which included areas of the proximal nail fold, nail matrix and onychodermis of the FVB mouse nail organ. Cells were cultured in DMEM:F12 medium with 15 % fetal bovine serum during 6 passages. We determined the colony-forming activity, the population growth rate and doubling time, measured the area of cells, nuclei, and calculated the nuclear-cytoplasmic ratio. For cell morphology analysis, we used staining with Bemer’s hematoxylin and eosin, Heidenhain’s iron hematoxylin and May-Grünwald stain.Results. According to the morphological analysis in vitro the cells from mouse nail unit are heterogeneous with high synthetic activity and a low nuclear-cytoplasmic ratio – the features characteristic of the low-differentiated cells. The population doubling time of the culture was 80 ± 6.5 hours on average, the fastest growing cells were at the 4th passage (63 ± 7 hours). The specific growth rate for cell culture is low (0.01 ± 0.0007).The colony forming efficiency at the 5th passage was only 4 %. A significant number of colonies was small with large poorly proliferative cells, which may indicate a production of large numbers of transitional progenitor cells.Conclusion. The obtained cell culture from the mouse nail unit according to the analysis of their morphology, morphometry and proliferative potential is heterogeneous and requires the further development of pure culture technologies for the detailed characterization of separate subpopulations of cells.

Paradoxically slow preadipocyte replication and differentiation in corpulent rats

1990 ◽  
Vol 258 (2) ◽  
pp. E368-E376 ◽  
Author(s):  
G. Shillabeer ◽  
J. M. Forden ◽  
J. C. Russell ◽  
D. C. Lau
Keyword(s):  
Adipose Tissue ◽  
Doubling Time ◽  
Tissue Growth ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Sprague Dawley ◽  
Induced Differentiation ◽  
Sd Rats

We have investigated the in vitro rate of replication and differentiation of preadipocytes derived from lean (+/+) and obese (cp/cp) male JCR:LA-corpulent (cp) rats in an attempt to identify mechanisms that regulate adipose tissue growth. Cp/cp rats were twofold heavier than age-matched lean rats by 9-10 mo. Cp/cp-derived preadipocytes demonstrated an inherently slower rate of replication than +/+ preadipocytes (population doubling time: cp/cp 52.3 +/- 9.6 h vs. +/+ 19.7 +/- 1.6 h), although the preadipocyte pool in the cp/cp was significantly greater. Cp/cp preadipocytes were resistant to hormonally induced differentiation (19.9 +/- 9.4% of cells accumulated lipid) but differentiated when cocultured with mature adipocytes to the same extent as preadipocytes derived from Sprague-Dawley (SD) rats (cp/cp 48.4 +/- 15.2% vs. SD 52.2 +/- 11.9%). In contrast, SD preadipocytes did not differentiate in response to mature adipocytes from +/+ rats (13.8 +/- 5.2%). Our observations suggest that preadipocyte replication and maturation may not be controlled in a coordinated manner.

Demography of an Estuarine Amphipod (Gammarus lawrencianus) Experimentally Selected for High "r": A Model of the Genetic Effects of Environmental Change

1981 ◽  
Vol 38 (9) ◽  
pp. 1120-1127 ◽  
Author(s):  
R. W. Doyle ◽  
W. Hunte
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Life History Strategy ◽  
Intrinsic Rate ◽  
Individual Growth ◽  
Population Growth Rates ◽  
Phenotypic Correlations ◽  
Demographic Traits ◽  
Marine Crustacean ◽  
Individual Growth Rate

The estuarine amphipod Gammarus lawrencianus was subjected to prolonged selection (3 years; 26 generations) for high population growth rates. The demography of the selected population was studied in detail and compared under laboratory conditions with animals derived from a control (wild) population collected in the same area 3 years later. In the lab-adapted population the intrinsic rate of population growth r increased by 72% as the result of changes in age at maturation, survivorship, and fecundity. The variance of these traits decreased and Crow's (1958) index of total selection (variance of fitness/mean fitness squared) is proposed as a quantitative and operational measure of genetic adaptation to a changed environment. Possible limitations on adaptation were investigated by examining the correlations among demographic traits within the lab-adapted population. Some phenotypic correlations were determined directly and others by an indirect technique using information from full siblings. Individual growth rate was negatively correlated both with survival and fecundity. Individual growth rate and age at sexual maturity were also negatively correlated. Negative phenotypic correlations between traits may indicate limitations on long-term adaptation. We conclude that significant evolutionary changes in the demographic traits of this (and presumably other) marine crustacean can occur within a time scale of interest to ecologists and aquaculturalists.Key words: adaptation, amphipod, aquaculture, Crustacea, evolution, Gammarus, genetics, life history, strategy

Impact of temperature and dissolved oxygen level on the population dynamics of naidids and their reproduction in biological activated carbon filters: a life table demographic study

2019 ◽  
Vol 19 (5) ◽  
pp. 1363-1370
Author(s):  
Xiao-Bao Nie ◽  
Yu-Qing Wu ◽  
Yuan-Nan Long ◽  
Chang-Bo Jiang ◽  
Li Kong
Keyword(s):  
Population Dynamics ◽  
Drinking Water ◽  
Activated Carbon ◽  
Life Table ◽  
Doubling Time ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Biological Activated Carbon ◽  
Water Plant ◽  
Water Plants

Abstract Aquatic macro-organisms, such as naidids, propagate excessively in biological activated carbon (BAC) filters. This has become a troublesome problem for drinking water plants. For successful control of naidid contamination risk, it is necessary to determine the population dynamics under different environmental conditions within drinking water plants, with special emphasis on BAC filters. In this study, field studies of naidid distribution in a drinking water plant were conducted, and the effects of temperature and dissolved oxygen (DO) on naidid population dynamics were investigated using the life table method. The results indicated that naidid pollution in the water plant occurred seasonally and was induced by the excessive propagation of naidids in the BAC filters. Increased temperature and DO increased the naidid intrinsic rate of natural increase and decreased the naidid population doubling time. The life table method was also used to acquire the reproductive parameters of naidids in BAC filters based on simulative experiments. These results indicated that naidids can reproduce asexually in BAC filters, and the population doubling time was 12.60 days.

Adult human aortic smooth muscle cells in culture produce active TGF-beta

1993 ◽  
Vol 265 (2) ◽  
pp. C571-C576 ◽  
Author(s):  
H. L. Kirschenlohr ◽  
J. C. Metcalfe ◽  
P. L. Weissberg ◽  
D. J. Grainger
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Doubling Time ◽  
Muscle Cells ◽  
Lung Epithelial Cells ◽  
Population Doubling ◽  
Population Doubling Time ◽  
Tgf Beta ◽  
Adult Human

Vascular smooth muscle cells (VSMC) from adult human aortas proliferated in culture in response to fetal calf serum (FCS) with a population doubling time of 70-85 h compared with 35 +/- 5 h for VSMC derived from adult rat aortas. Medium conditioned on cultures prepared from aortas from three different donors and mixed 1:1 with fresh Dulbecco's modified Eagle's medium plus 20% FCS [human conditioned medium (HCM)] reduced the rate of proliferation of rat VSMC by 46 +/- 6% (n = 3) after 48 h compared with cells in fresh medium. HCM did not reduce the proportion (> 65%) of rat VSMC that entered DNA synthesis but delayed entry into mitosis by at least 18 h. This effect was similar to previous observations of the action of transforming growth factor-beta (TGF-beta) on rat VSMC (G. K. Owens, A. A. Geisterfer, Y. W. Yang, and A. Komoriya. J. Cell Biol. 107: 771-780, 1988). A TGF-beta assay using DNA synthesis in mink lung epithelial cells confirmed that human, but not rat, VSMC in culture secrete active TGF-beta. Addition of a neutralizing antibody to TGF-beta to human VSMC in the presence of 20% FCS decreased the population doubling time from 74 +/- 3 to 46 +/- 6 h (n = 3). These observations demonstrate that the long population doubling time of human VSMC is due to the production of active TGF-beta and to an inhibitory autocrine loop.

Influence of growth and survival costs of reproduction on Atlantic cod, Gadus morhua, population growth rate

1999 ◽  
Vol 56 (9) ◽  
pp. 1612-1623 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Environmental Stochasticity ◽  
Individual Growth ◽  
Growth And Survival ◽  
Individual Growth Rate ◽  
Age Structured ◽  
Reproductive Rates

A stochastic, age-structured life history model was used to examine how age at maturity (theta), pre- (Zimm) and postreproductive (Zmat) mortality, and postreproductive growth rate can affect maximum reproductive rates of fish at low population size. Simulations suggest that annual (r) and per-generation (R0) metrics of population growth for Newfoundland's northern Grand Bank Atlantic cod, Gadus morhua, are primarily influenced by changes to mortality prior to and following reproduction. At observed weights at age and Zmat = 0.2, r ranged between 0.135 and 0.164 for cod maturing at between 4 and 7 years. Incremental increases in either Zimm or Zmat of 0.1 were associated with 0.03-0.05 reductions in r. To effect similar reductions, individual growth rate would have to decline by approximately one half. At observed weights at age, increases in Zmat from 0.20 to 0.45 increased the probability of negative per-generation growth from 3 to 26% for cod maturing at 4 years and from 6 to 46% for cod maturing at 7 years. Thus, even in the absence of fishing mortality, little or no population growth by Atlantic cod may not be unexpected in the presence of environmental stochasticity, particularly when accompanied by increases in mortality and declining individual growth.

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