Growth and photosynthesis of Chlamydomonas …
" Growth and photosynthesis of Chlamydomonas reinhardtii as a function of CO2 concentration "
KEGG PATHWAY: Photosynthesis - Chlamydomonas …
The Molecular Biology of Chloroplasts and Mitochondria in Chlamydomonas provides a comprehensive coverage of chloroplast and mitochondrial biogenesis and function. The book presents the current status of research on the molecular genetics of chloroplast gene expression. It describes the intricate cooperative interplay between the chloroplast and nuclear compartments which underlies the assembly of the photosynthetic apparatus. It also shows the power of chloroplast reverse genetics which has been used with considerable success to investigate structure-function relationships in several photosynthetic complexes. The book is intended for a wide audience, but is specifically designed for advanced undergraduate and graduate students and researchers in the fields of biochemistry, molecular biology, physiology, biophysics, plant biology, phycology and biotechnology.
Our novel findings on the negative effects on green algal growth by the estrogen EE2 motivates further studies. In this study we have examined the effects on growth and photosynthesis in C. reinhardtii caused by the addition of EE2, but it would be important to also examine other estrogenic substances as well as other algae. Clearly, release of the estrogen EE2 in the waste water stream poses a potential problem not only with reduced removal of CO2 from the atmosphere but also a reduced growth rate which would have implications for the aquatic food web. Finally, these results indicate potential problems in using algae as a method to efficiently remove the inorganic nutrient load in waste water.
Does Chlamydomonas photosynthesis? | Yahoo Answers
Changes in photosynthetic Vmax () and changes in K0.5 () for the cultures without and with added CA inhibitors were calculated from Ci-response curves with data fitted to the Michaelis-Menten equation. There is no observable estrogen effect on Vmax in the absence of CA inhibitors (control) or with the addition of AZ which inhibits CA activity in the periplasmic space (). This indicates that the maximum capacity for the assimilation of CO2 was unaffected by the inhibition of CAs of the CCM. However, in the presence of EZ, which inhibits CA activity both in the periplasmic space as well as in the chloroplast, a 30–35% reduction with little apparent changes between the different culture conditions was observed in Vmax compared to the controls ().
Doubling times for the EE2-exposed cultures were determined for the batch and turbidostat grown cultures, respectively (, ). As expected from previous experiments , the cells grown in batch cultures had higher doubling times than in the turbidostats. However, batch cultures were used to establish whether or not there was an effect on growth at all by EE2 as well as at which concentration the effect would become detectable. The turbidostat cultures were used to continuously provide cells growing at their maximum growth rate, μmax, for further experiments. It was shown that the growth rate was negatively affected at the lowest EE2 concentration tested, resulting in a change in doubling time from 22.7 h in the control to 26.6 h at 10 pM which is a significant increase by 17% (). Doubling times increased by further increasing the concentration of EE2 up to a concentration of 100 pM. At the highest concentration tested, 10 µM, the doubling time was 26% higher than in the control. Clearly, growth is negatively affected by EE2 additions.
2006/11/12 · Does Chlamydomonas photosynthesis
Many chemical compounds released into our environment can be classified as endocrine disrupters (EDs), substances that have the capacity to adversely alter animal endocrine functions leading to changes in growth, reproduction, development or behavior . Often the substances are diffusely entering the environment but in other cases the source is well known as, for example, from waste water. The primary synthetic estrogen in typical oral contraceptives used by more than 100 million women worldwide is the sterol 17α-Ethynylestradiol (EE2). Up to 80% of the EE2 consumed is excreted as un-metabolized conjugates in urine. The bioaccumulation of EE2 in waste water plants has been shown to impact aquatic life with the main focus being on fish . The contribution of EE2 to the total amount of excreted estrogens is only about 1% but this compound is considerably more persistent in sewage effluents as compared to the naturally occurring hormones such as 17β-Estradiol (E2) and estrone (E1) . In in vivo studies in fish, EE2 was shown to be 11-130 times more potent than E2, which in turn was 2.3–3.2 times more potent than E1 (, –, see for a review). EE2 is also considered to be more hydrophobic . Removal of estrogens from sludge in sewage treatment plants is dependent on temperature, where warm summer temperatures would successfully eliminate EE2 . However, many areas at northern European latitudes have comparatively short summer seasons and in remote areas in e.g. Sweden, the typical sewage treatment is performed by open oxidation ponds which results in lower EE2 removal/degradation during a large part of the year , .
It is well known that estrogenic compounds affect development of fertilized eggs of many species of birds, fish and amphibians through disrupted activity of carbonic anhydrase (CA). The most potent activity comes from the most commonly occurring synthetic sterol, 17α-Ethynylestradiol (EE2). Less is known about the responses of aquatic phytoplankton to these compounds. Here we show for the first time that, in comparision to the control, the addition of 7 µM EE2 reduced the growth rate of the green alga Chlamydomonas reinhardtii by 68% for cells grown at high CO2. When cells were grown in ambient air (low Ci) with a fully activated carbon concentrating mechanism through the induction of CA activity, the growth rates were reduced by as much as 119%. A reduced growth rate could be observed at EE2 concentrations as low as 10 pM. This was accompanied by a reduced maximum capacity for electron transport in photosystem II as determined by a lower FV/FM for low Ci-grown cells, which indicates the involvement of CAH3, a CA specifically located in the thylakoid lumen involved in proton pumping across the thylakoid membranes. These results were in agreement with an observed reduction in the chloroplastic affinity for Ci as shown by a strong increase in the Michaelis-Menten K0.5 for HCO3−. In itself, a lowering of the growth rate of a green alga by addition of the sterol EE2 warrants further investigation into the potential environmental impact by the release of treated waste water.
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Chlamydomonas: Chlamydomonas, genus of single-celled green algae found in soil and freshwater.
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As expected, a higher Michaelis-Menten constant, K0.5, was observed in the high-Ci grown cells (control) which indicates a lower affinity for CO2 both in the absence or presence of EE2 during growth (). A lower K0.5 was observed in cells from the low-Ci grown cultures which reflects an inducible higher affinity of the CAs for CO2 through activation of the CCM . The Ci induced difference disappeared by the addition of AZ such that the K0.5 of low-Ci grown cells increased to the level of what the high-Ci grown cells displayed without the addition of AZ (). However, there is a pronounced and stronger effect on K0.5 for EE2-grown cells with EZ added (). The K0.5 increased to a level that was approximately 50% higher for the EE2-grown cells as compared to cells grown in the absence of EE2 regardless of if they were grown at low or high Ci (). This indicates that the chloroplastic CA activity is most sensitive to the effects of EE2.
Apr 30, 2008 · This a video of an Amoeba
You will be able to see a picture of reproduction in the next slide.
Asexual reproduction is when the nucleus divides to produce up to 16 offspring cells, breaking the parent cell wall, each cell develops flagella and secrete an enzyme that breaks down the parent cell wall by which they can escape.
Movement of the Amoeba is shown
Photosynthesis is normally effected in green plants, as chlamydomonas's is a green algae.
Chlamydomonas's have two types of reproduction called sexual reproduction and asexual reproduction, sexual reproduction is when 2 isogamates of different mating types are contacted with each other toward flagella ends, both gametes unite to form a diploid.
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