Thursday, May 31, 2012

Blue-green algae release chemicals that cause some amphibian deformities

Blue-green algae release chemical suspected in some amphibian deformities
Retinoic acid levels high in waterways rich in cyanobacteria blooms
Wednesday, May 30th, 2012

Harmless as they may look, some of the microbes called cyanobacteria have the power to dose waterways with a range of chemicals that might cause deformities in frogs or other vertebrate wildlife.

Cyanobacteria, also called blue-green algae, could be an underappreciated but widespread source of compounds called retinoic acids in waterways, says environmental toxicologist Jianying Hu of Peking University. Out of 24 kinds of cyanobacteria grown in a lab, 13 produced some kind of retinoic acid or retinoic acid cousin, Hu and her colleagues report online May 29 in the Proceedings of the National Academy of Sciences.

Retinoic acids, formed from vitamin A, help sculpt developing body parts in vertebrates. Researchers puzzling over clusters of deformed frogs first highlighted in the 1990s have considered retinoic acids as one of several possible villains.

Hu and colleagues also analyzed samples from China’s third largest freshwater lake, Taihu Lake, which is rich in cyanobacteria blooms. The lake carries high concentrations of retinoic acids, the researchers found.

The new work “opens up a new area of potential research,” says plankton ecologist Karl Havens,
who directs the Florida Sea Grant College Program in Gainesville. “I will be interested now to see if the compounds are found in other lakes with cyanobacteria blooms, or even if they continue to be documented in this lake,” he says.

The retinoic acid concentration found in Taihu Lake — up to 20 nanograms per liter — was 10,000 times what Kunimitsu Kaya of the University of Tsukuba in Japan and his colleagues have found in Japanese lakes. Last year Kaya reported cyanobacteria making a retinoic acid cousin (7-hydroxy retinoic acid); he says he finds it plausible that blooms create such extreme conditions in Taihu. Scum there probably blocks sunlight that otherwise would break down some of the very potent retinoic acids.

There’s not enough information yet to link cyanobacteria to high rates of amphibian deformities, says ecologist Andrew Blaustein of Oregon State University in Corvallis. He and other researchers have proposed a variety of other possible contributing menaces, including UV radiation and trematode parasites.

Parasites, a leading hypothesis for the cause of some limb abnormalities, certainly don’t explain all the cases, says disease ecologist Pieter Johnson of the University of Colorado Boulder. The new paper “may be a useful step forward in helping to explain abnormalities in wetlands without the parasite.

Sunday, May 27, 2012

Diatoms and Nualgi - Paper published

A paper on Diatoms based on work by Mr M Thomas Kiran Chief Technology Office of Kadambari Consultants Pvt Ltd is published in Botanica Marina journal -

Culture medium optimization and lipid profiling of Cylindrotheca, a lipid- and polyunsaturated fatty acid-rich pennate diatom and potential source of eicosapentaenoic acid

Suman, Keerthi 1,a / Kiran, Thomas 1,a  1 / Sarma, Nittala S. 2
1Department of Botany, Andhra University, Visakhapatnam 530003, Andhra Pradesh, India
2Department of Marine Chemistry, School of Chemistry, Andhra University, Visakhapatnam 530003, Andhra Pradesh, India
aThe first two authors made equal contributions to the manuscript.
Corresponding author
Citation Information: . Volume 55, Issue 3, Pages 289–299, ISSN (Online) 1437-4323, ISSN (Print) 0006-8055, DOI: 10.1515/bot-2011-0076, May 2012
Publication History:
Received: 06/08/2011;
Accepted: 28/03/2012;
Published Online: 15/06/2012


Cylindrotheca, an epipelic benthic pennate diatom, holds promise as a nutraceutical source and may be useful for aquaculture. Experiments were done on two Cylindrotheca species, Cylindrotheca fusiformis (UTEX 2084) andC. closterium, which was isolated from seawater collected offshore from Visakhapatnam, India. C. closteriumwas identified through microscopy and rDNA typing. Type and concentration of nutrient components in the culture medium that promoted best growth and highest lipid accumulation were identified. Lipid content was gravimetrically estimated. For relative comparison of the effects of different culture media on lipid content, we made estimations through rapid in situ screening method using Nile red staining and spectrofluorimetry. The fatty acid profile of lipid was obtained through gas chromatography-mass spectroscopy. Nualgi, a commercially available micronutrient ready-mix with elements adsorbed as nanoparticles on a modified silica sol, was found to significantly boost growth in bothCylindrotheca species when used in lieu of a conventional micronutrient mix prepared from eight compounds. Among the three nitrogen sources tested – sodium nitrate (NaNO3), urea, and ammonium chloride (NH4Cl) – best growth of C. fusiformis occurred on nitrate and urea, while NH4Cl was best for C. closterium. Lipid productivity was much higher in cultures supplied with NH4Cl for both Cylindrotheca species and compensated for lower biomass in C. fusiformis. Mixotrophy with glycerol or sodium acetate resulted in no significant increase in growth over photoautotrophy. Both Cylindrothecaspecies were lipid rich; lipid constituted 18–27% of dry biomass in the medium with NaNO3. Among total fatty acids, polyunsaturated fatty acids constituted <40%, eicosapentaenoic acid 25%, and arachidonic acid ∼8% and ∼4% in C. fusiformis and C. closterium, respectively. NH4Cl, phosphate, and Nualgi micronutrient ready-mix in concentrations optimal for each strain contribute to a good culture medium for Cylindrotheca.

Wednesday, May 9, 2012

Decline in Diatoms in Oceans UXBRIDGE, Canada, May 8, 2012 (IPS) - Without major reductions in the use of fossil fuels, sunlight is to kill an unknown number of ocean phytoplankton, the planet's most important organism, a new study reports this week. Not only are phytoplankton, also known as marine algae, a vital component in the ocean's food chain, they generate at least half of the oxygen we breathe. In the not so distant future, sunlight, the very source of life for phytoplankton, will likely begin to kill them because of the ocean's increasing acidity, researchers from China and Germany have learned. "There's a synergistic effect between increased ocean acidity and natural light," says Ulf Riebesell of the Helmholtz Centre for Ocean Research in Kiel, Germany. Riebesell added that it was also possible "phytoplankton could adapt". Researchers were surprised to discover that diatoms, one of the most important and abundant types of phytoplankton, fared very badly during shipboard experiments conducted by co-author Kunshan Gao, from the State Key Laboratory of Marine Environmental Science at Xiamen University, Xiamen China. Previous experiments in labs like Riebesell's found that diatoms actually did better in high-acid seawater, unlike most other shell- forming plankton. Burning fossil fuels has made the oceans about 30 percent more acidic researchers discovered less than 10 years ago. Oceans absorb one third of the carbon dioxide (CO2) emitted from using fossil fuels. The good news is this has slowed the rate of global warming. The bad news is oceans are now more acidic and it will get worse as more CO2 is emitted. This is basic, well-understood ocean chemistry. Gao and his team made several trips into the South China Sea taking samples from surface waters where phytoplankton are found. While still on the research vessel, those samples were made as acidic as the oceans are likely to be in 2100 without major emissions reductions (800-1000 parts per million compared to current 392 ppm). As expected under these conditions, certain types of plankton like coccolithophores did not do well but surprisingly, diatom productivity also declined. One possible reason was the much brighter natural light on the ship versus that in science labs, Riebsell and Gao suspected. Followup lab experiments with lights mimicking the intensity of natural light in the subtropical zone of the South China Sea confirmed that the combination of high-acid sea water and light intensity was more than diatoms could handle. Riebsell speculates that diatoms stressed by high-acid conditions can't cope with the energy they receive from sunlight at the same time. Their study was published May 6 in Nature Climate Change. "We don't know at what point the combination of a certain level of ocean acidity and sunlight leads to the decline of diatoms," he said. This is just one of many recent studies finding negative impacts as the oceans become more and more acidic. By 2040, most of the Arctic Ocean will be too acidic for shell- forming species including most plankton. Significant areas of the Antarctic Ocean will be similarly affected, oceanographer Carol Turley from Plymouth Marine Laboratory in the UK previously told IPS. The cold waters of the polar regions allow more CO2 to be absorbed faster, turning the oceans more acidic sooner. The oceans haven't seen a rapid change like this in 60 million years, said Turley. She warned that global warming is also raising water temperatures and reducing the amount of oxygen in seawater in some regions. This is another potentially dangerous combination. "Our research suggests the impact of oceanic acidification upon marine plankton could be more serious than previously thought," said John Beardall from the School of Biological Sciences at Monash University. Beardall and colleagues from several research centres calculate that without major reductions in CO2 emissions, ocean acidity will have a significant impact on phytoplankton before 2100. Their findings were also recently published in Nature Climate Change. It's not just plankton. The large and continuing decline of oysters, both wild and farmed, in the Pacific Northwest have now been linked to increased ocean acidity. Scientists have shown that oyster larvae have difficulty building shells in corrosive waters, according to a study in the journal Limnology and Oceanography published last month. "For the oceans, the Pacific Oyster larvae are the canaries in the coal mines for ocean acidification," said Richard Feely, a co-author of the study and senior scientist at the National Oceanic and Atmospheric Administration. Fish and other species are showing changes in their growth, behaviour and reproduction, according to other research. Not only are the oceans big, covering 70 percent of the planet, they are complex. Recent work by the Scripps Institution of Oceanography at San Diego reveals there is huge variability in ocean acidity levels. That makes "global predictions of the impacts of ocean acidification a big challenge," said Jennifer Smith, a marine biologist with Scripps. The only prediction Riebesell is willing to make is about the high likelihood of a major decline in the ocean's biodiversity (number and types of living things) if rates of fossil fuel emissions continue. Roughly 80 percent of all life is found in the oceans. "Changes in the oceans are happening too fast for most species to cope," he said. "It's clear we are conducting a giant experiment on the planet and we don't know what we are doing."