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Studies on the Effects of Elevated CO₂ and UV-B on the Growth and Photosynthesis of Nostoc Commune

Author: HongDeng
Tutor: ZhouZhuQing；LiYunGuang
School: Huazhong Agricultural University
Course: Cell Biology
Keywords: CO2 UV-B Ordinary Nostoc Grow Photosynthesis
CLC: Q945
Type: Master's thesis
Year: 2011
Downloads: 51
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Abstract

Terrestrial nitrogen-fixing cyanobacteria are some of the most extreme environments and nitrogen source nutritional deficiencies major primary producers in the ecosystem and how environmental changes affect future productivity and nitrogenase activity will have a significant impact on these ecosystems. Global Environment suffering tremendous changes, C02 increased UV-B enhancement will exist for a long period of time, how their terrestrial cyanobacteria, and worthy of attention. The subject in a widely distributed terrestrial nitrogen-fixing blue-green algae - ordinary Nostoc (Nostoc commune) as experimental materials, indoor research doubled CO2 and UV-B enhanced their growth, biochemical composition and photosynthetic physiology and related photosynthetic gene expression the impact. To understand the in future C02 increased UV-B enhanced environment, nitrogen-fixing cyanobacteria biomass How will change, and explaining its possible causes from the biochemical, physiological and gene expression. In addition, the article also carried out on the biological effects and filtering methods of artificial UV light sources in the UV-A and UV-C. The main results are as follows: (1) potassium chromate solution concentration and pH influence of UV-B and UV-A and UV-C absorption. 0.4mM (pH 8), potassium chromate solution can also effectively filter out the UV light source in the UV-A and UV-C, and to maintain the permeability to UV-B high. With homemade quartz vessel (35 cm long, 1 cm wide and 20 cm high) filled with potassium chromate solution was filtered UV light source, and can be quickly and accurately study the biological effects of UV-B, and can be repeated several times to take advantage of and convenient economy. (2) whether it is 350 or 1500μLL-1CO2 concentration, low doses of UV-B radiation (9KJm-2d-1) on ordinary rosary algae per unit volume of dry weight, said the growth had no significant effect; while high doses of UV-B radiation (20 KJm-2 d-1), a significant inhibition of growth, and the degree of inhibition with elevated C02 concentration. The same level of UV-B radiation, high concentrations of CO2 (1500μL-1) significantly promote the growth of the ordinary Nostoc, promote the degree increases with increasing UV-B intensity. High concentrations of CO2 and high doses of UV-B ordinary Nostoc growth is still better than the ordinary Nostoc in atmospheric CO2 and UV-B radiation treatment, which shows that in the case of future atmospheric CO2 concentration, pure UV -B enhancement may not make ordinary Nostoc existing biomass decreased. Under different UV-B and C02, ordinary Nostoc per unit dry weight of chlorophyll content per unit volume of the dry weight of the trend is similar. That high doses of UV-B radiation significantly reduced the chlorophyll content per unit dry weight of ordinary Nostoc, high concentrations of C02 increased ordinary Nostoc unit dry weight chlorophyll content. UV-B radiation induced ordinary Nostoc triphenylimidazole amino acids (MAAs), a large number of synthesis. Ordinary Nostoc unit dry weight MAAs content increases with the intensity of the UV-B irradiation time extended gradually increased steadily. High doses of UV-B radiation, C02 concentrations increased significantly promote the synthesis of MAAs, low doses of UV-B, the role is not obvious. (3) UV-B radiation significantly inhibit ordinary Nostoc Fv / Fm, and the degree of inhibition is enhanced with the increase in the intensity of the UV-B. However, as the prolonged incubation time, the suppression degree becomes gradually smaller, and ultimately returned to the control level. The same level of UV-B radiation, high concentrations of C02 significantly improve ordinary Nostoc Fv / Fm. High doses of UV-B radiation in the early development stage, reducing the ordinary rosary algae maximum rate of photosynthesis, the efficiency of photosynthesis, respiration rate, inorganic carbon saturated maximum photosynthetic rate, increasing the light saturation point and light compensation point. High concentrations of C02 increased light-saturated rate of photosynthesis, the efficiency of photosynthesis, respiration rate, but reduce the light saturation point and light compensation point. (4) ntca gene in cultured second and eight days relative to the first day of a significant reduction, especially in the eighth day of training, regardless of enriched CO2 or not, UV-B radiation significantly promoted the expression of ntca. The treatment groups ntca genes in the eighth day the expression of differences, psb and rbcL similar differences. psb and rbcL gene expression changes with the culture of the time change, the overall similar to ntca gene. In short, C02 and UV-B affects ordinary Nostoc growth, physiology and gene expression.

Studies on the Effects of Elevated CO2 and UV-B on the Growth and Photosynthesis of Nostoc Commune

Abstract

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Studies on the Effects of Elevated CO₂ and UV-B on the Growth and Photosynthesis of Nostoc Commune