scholarly journals Seasonal variation in the net growth rate of the cyanobacterium Cylindrospermopsis raciborskii in a shallow artificial pond in northern Taiwan

2013 ◽  
Vol 8 (2) ◽  
pp. 68-73 ◽  
Author(s):  
Yoshimasa Yamamoto ◽  
Fuh-Kwo Shiah ◽  
Shih-Chieh Hsu
Keyword(s):  
Growth Rate ◽  
Seasonal Variation ◽  
Cylindrospermopsis Raciborskii ◽  
Artificial Pond ◽  
Net Growth Rate ◽  
Northern Taiwan

Shear Loss Characteristics of an Aerobic Biofilm

1992 ◽  
Vol 26 (3-4) ◽  
pp. 595-600 ◽  
Author(s):  
S. M. Rao Bhamidimarri ◽  
T. T. See
Keyword(s):  
Growth Rate ◽  
Shear Stress ◽  
Film Thickness ◽  
Removal Rate ◽  
Surface Growth ◽  
Phenol Removal ◽  
Concentric Cylinder ◽  
Substrate Utilisation ◽  
Utilisation Rate ◽  
Net Growth Rate

Growth and shear loss characteristics of phenol utilizing biofilm were studied in a concentric cylinder bioreactor. The net accumulation of the biofilm and the substrate utilisation were measured as a function of torque. Uniform biofilms were obtained up to a thickness of around 300 microns, beyond which the surface growth was non-uniform. The substrate utilisation rate, however, reached a constant value beyond film thickness of 50 to 100 microns depending on the operational torque. The maximum phenol removal rate was achieved at a shear stress of 3.5 Nm-2. The effect of shear stress on net growth rate was found to be described byand a zero net growth was obtained at a shear stress of 18.7 Nm-2.

scholarly journals Effects of light intensity and temperature on Cylindrospermopsis raciborskii (Cyanobacteria) with straight and coiled trichomes: growth rate and morphology

2012 ◽  
Vol 72 (2) ◽  
pp. 343-351 ◽  
Author(s):  
MC. Bittencourt-Oliveira ◽  
B. Buch ◽  
TC. Hereman ◽  
JDT. Arruda-Neto ◽  
AN. Moura ◽  
...  
Keyword(s):  
Growth Rate ◽  
Light Intensity ◽  
Morphological Changes ◽  
Population Control ◽  
Distinct Species ◽  
Cylindrospermopsis Raciborskii ◽  
Climatic Chamber ◽  
Light Intensities ◽  
Different Temperatures ◽  
Lower Temperature

Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju (Ordem Nostocales) is one of the most troublesome bloom-forming species in Brazil. Understanding the population dynamics of the different morphotypes of C. raciborskii (straight and coiled) could assist in the prediction of favourable conditions for the proliferation of this potentially toxin-producing species. The aim of the present study was to assess the effects of two different light intensities and temperatures on the growth rate and morphology of the trichomes of the straight and coiled morphotypes. For such, two non-toxin producing strains of C. raciborskii were used - one with a coiled trichome (ITEP31) and another with a straight trichome (ITEP28). The strains were cultured in BG-11 medium in a climatic chamber under controlled conditions. Two light intensities (30 and 90 µmol.m-2.s-1 ) were combined at temperatures of 21 and 31 °C and the growth rate and morphological changes were analysed. The morphotypes responded differently to the different temperatures and light intensities. Both strains exhibited faster growth velocities when submitted to higher light intensity and temperature. The lower temperature and higher luminosity hampered the development of both strains. Variations in cellular morphology and an absence of akinetes in both strains were related to the lower temperature (21 °C). The coiled morphotype demonstrated considerable phenotype plasticity, changing the morphology of trichome throughout its growth curve. Although molecular analysis does not sustain the separation of the morphotypes as distinct species, their different eco-physiological responses should be considered further knowledge of extreme importance for the population control of these potentially toxic organisms.

An ultrastructural investigation of Leishmania donovani infection in genetically resistant and susceptible mouse strains

1985 ◽  
Vol 31 (3) ◽  
pp. 256-260
Author(s):  
Peter R. Weldon ◽  
Patricia A. L. Kongshavn
Keyword(s):  
Growth Rate ◽  
Infected Cell ◽  
Kupffer Cells ◽  
Leishmania Donovani ◽  
Ultrastructural Level ◽  
Natural Resistance ◽  
Mouse Strains ◽  
Susceptible Mouse ◽  
Susceptible Allele ◽  
Net Growth Rate

Natural resistance to the growth of Leishmania donovani in mice is controlled by a gene (Lsh) which is expressed, in an unknown fashion, in macrophages. Early net growth rate of the parasite is much higher in mice strains bearing the susceptible allele (Lshs) than in resistant (Lshr) mice. Intracellular events occurring in the Kupffer cells during this period have been studied at the ultrastructural level. It was found that the number of dividing amastigotes per thin section of infected cell was approximately 10-fold greater in susceptible (B10.A SgSn) than in resistant (A/J) strains of mice, both 7 and 14 days following infection. These findings support the hypothesis that high natural resistance to leishmaniasis (Lshr) is expressed as a microbistatic effect, exerted within the parasitized macrophage of the host.

scholarly journals Net growth rate of continuum heterogeneous biofilms with inhibition kinetics

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Elio Emilio Gonzo ◽  
Stefan Wuertz ◽  
Veronica B. Rajal
Keyword(s):  
Growth Rate ◽  
Inhibition Kinetics ◽  
Net Growth Rate

scholarly journals The population control bill, 2021: exploring newer perspectives

2021 ◽  
Vol 10 (9) ◽  
pp. 3668
Author(s):  
Prerana Nagabhushana ◽  
Avir Sarkar
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Reproductive Rights ◽  
Population Control ◽  
World Population ◽  
Population Explosion ◽  
Population Policies ◽  
The World ◽  
Net Growth Rate ◽  
Do So

As we observe the World Population Day on 11th July, the current population stands at roughly 7.9 billion in 2021, with India bagging the second place at 1.39 billion. The net growth rate stands at 1.1% or 83 million per year and the projected world population by 2050 is estimated to be 9.7 billion. These figures are alarming to us-the millennials, who grew up writing ominous essays on ‘population explosion’ at school. Governments across the world, historically Romania to more recently China, have adopted population policies to control the rate of population growth to cater to their advantage-either economically or politically. Some of them directly against reproductive rights- to decide freely and responsibly the number, spacing and timing of their children and to be able to do so without discrimination, coercion and violence.

scholarly journals Modulation of ecdysal cyst and toxin dynamics of two <i>Alexandrium</i> (Dinophyceae) species under small-scale turbulence

2007 ◽  
Vol 4 (4) ◽  
pp. 559-567 ◽  
Author(s):  
L. Bolli ◽  
G. Llaveria ◽  
E. Garcés ◽  
Ò. Guadayol ◽  
K. van Lenning ◽  
...  
Keyword(s):  
Growth Rate ◽  
Toxin Production ◽  
Thin Layers ◽  
Small Scale ◽  
Alexandrium Minutum ◽  
Cell Numbers ◽  
Cyst Production ◽  
Net Growth Rate ◽  
Scale Turbulence ◽  
Orbital Shaker

Abstract. Some dinoflagellate species have shown different physiological responses to certain turbulent conditions. Here we investigate how two levels of turbulent kinetic energy dissipation rates (ε = 0.4 and 27 cm² s−3) affect the PSP toxins and ecdysal cyst dynamics of two bloom forming species, Alexandrium minutum and A. catenella. The most striking responses were observed at the high ε generated by an orbital shaker. In the cultures of the two species shaken for more than 4 days, the cellular GTX(1+4) toxin contents were significantly lower than in the still control cultures. In A. minutum this trend was also observed in the C(1+2) toxin content. For the two species, inhibition of ecdysal cyst production occurred during the period of exposure of the cultures to stirring (4 or more days) at any time during their growth curve. Recovery of cyst abundances was always observed when turbulence stopped. When shaking persisted for more than 4 days, the net growth rate significantly decreased in A. minutum (from 0.25±0.01 day−1 to 0.19±0.02 day−1) and the final cell numbers were lower (ca. 55.4%) than in the still control cultures. In A. catenella, the net growth rate was not markedly modified by turbulence although under long exposure to shaking, the cultures entered earlier in the stationary phase and the final cell numbers were significantly lower (ca. 23%) than in the control flasks. The described responses were not observed in the experiments performed at the low turbulence intensities with an orbital grid system, where the population development was favoured. In those conditions, cells appeared to escape from the zone of the influence of the grids and concentrated in calmer thin layers either at the top or at the bottom of the containers. This ecophysiological study provides new evidences about the sensitivity to high levels of small-scale turbulence by two life cycle related processes, toxin production and encystment, in dinoflagellates. This can contribute to the understanding of the dynamics of those organisms in nature.

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