Details of Photosynthesis Coming to Light

first_img1Amuntz, Drory and Nelson, “The structure of a plant photosystem I supercomplex at 3.4-angstrom resolution,” Nature 447, 58-63 (3 May 2007) | doi:10.1038/nature05687.2Skourtis and Beratan, “Photosynthesis from the Protein’s Perspective,” Science, 4 May 2007: Vol. 316. no. 5825, pp. 703-704, doi: 10.1126/science.1142330.3The second paper also spoke of the efficient use of quantum mechanical properties of light: “The experimental data reported by Wang et al. also encourage renewed theoretical attention to the early events in photosynthesis.  Models that include quantized nuclear dynamics seem particularly important, because high-frequency quantum modes influence fast electron transfer, producing nonexponential kinetics and unusual temperature dependence.”4“Wang et al. suggest that the slow protein dynamics discussed above may help to overcome reaction barriers produced by membrane potentials or by environmental factors that perturb the photosynthetic reaction center and potentially slow down the electron-transfer rate.  Thus, protein motion could overcome reaction barriers produced by cellular factors that might otherwise perturb the electron-transfer kinetics.”Those who studied high school biology decades ago can revel in these facts about photosynthesis that are now coming to light (pardon the pun).  At the time, our teachers and professors saw light going in, and sugars coming out, but were nearly clueless about what magic was going on inside.  The black box is now opening, and we’re finding out that highly efficient molecular machines were there all along.  So that’s how it’s done!(Visited 14 times, 1 visits today)FacebookTwitterPinterestSave分享0 New tools of science are unveiling the secrets of what was long a “black box” in biology: photosynthesis.  A paper in Nature last week1 described the structure of the plant PhotoSystem I complex (PSI) in near-atomic resolution.  Next day, a paper in Science2 described some of the protein interactions that occur when plants turn light into energy for work.  Both papers praised the exceptional efficiency of “the most efficient nano-photochemical machine in nature.”    As is common in the scientific literature, the paper in Nature used engineering language when discussing photosynthesis.  It referred to the “reaction centre” as a “light-harvesting complex” and to certain parts as “antennas.”  The authors used the root efficient eight times in the paper: for example, “This highly efficient nano-photoelectric machine is expected to interact with other proteins in a regulated and efficient manner” – there are two instances in the same sentence.  The paper ended:The complexity of PSI belies its efficiency: almost every photon absorbed by the PSI complex is used to drive electron transport.  It is remarkable that PSI exhibits a quantum yield of nearly 1 (refs 47, 48), and every captured photon is eventually trapped and results in electron translocation.  The structural information on the proteins, the cofactors and their interactions that is described in this work provides a step towards understanding how the unprecedented high quantum-yield of PSI in light capturing and electron transfer is achieved.The authors only referred to evolution once: “The two principal subunits of the reaction centre, PsaA and PsaB, share similarities in their amino acid sequences and constitute a pseudosymmetric structure that evolved from an ancient homodimeric assembly.”  Yet this was stated dogmatically without any explanation of how that could have occurred.    The paper in Science explored photosynthesis from the protein’s perspective.  The authors of this paper also spoke of the “efficient transfer of electrons across biomembranes” and the “high efficiency of the reaction (an electron is transferred for each photon absorbed)” – i.e., there is no loss or waste of input.    The authors discussed how certain protein parts physically move in response to their inputs.  These movements among the chlorophylls and other parts modulate the speed of the downstream reactions.  Rather than quote their jargon about biomechanics and biomolecular dynamics, let’s attempt an analogy that suggested itself from one of the illustrations: it’s like catching eggs dropping out of the sky into a soft, gentle net, where they can be safely transported to the kitchen.  Those who prefer the original jargon can see the footnote.4last_img read more

Gallery: South African rhythm in Soweto

first_imgCompiled and photographed by Bongani Nkosi The hearty rhythm of South African music and dance is best experienced on the streets of Soweto, the country’s largest and most famous township. The skilled, lithe movements of pantsula dancers, traditional tribal displays and impeccably timed brass band parades are just some of the attractions that are delighting streams of tourists and local spectators alike.Click on a thumbnail for a larger low-resolution image, or right-click on the link below each thumbnail to download a high-resolution image.   • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image  • Download high-resolution image MORE GALLERIESlast_img read more

Stellenbosch wine tourism campaign goes global

first_img4 March 2014South Africa’s Stellenbosch Wine Routes will be making its debut at the 2014 International Tourism Bourse (ITB) Berlin on Wednesday as part of the global launch of its wine tourism marketing campaign, the “Stellenbosch Experience”.Stellenbosch Wine Routes will join forces with South African Tourism, Western Cape tourism and investment agency Wesgro, and Tripadvisor in showcasing wine tourism in Stellenbosch and the broader Western Cape.“The potential of wine tourism in South Africa is huge, and Stellenbosch and the Western Cape at large are perfectly placed to attract more wine tourists to our country, but then a far greater and more aligned effort is needed on a global scale,” Stellenbosch Wine Routes CEO Annareth Bolton said in a statement last week.The Stellenbosch Wine Experience campaign is a partnership between Stellenbosch Wine Routes and Stellenbosch 360, a cultural tourist route encompassing Stellenbosch, Dwarsrivier and Franschhoek. By launching at the ITB, the campaign aims to expand the region’s wine tourism footprint abroad.“We are thrilled about this collaboration and cannot wait to introduce Stellenbosch as the ultimate wine tourism destination in terms of quality, authenticity and value-for-money experiences to the world,” Bolton said.“With this campaign, we aim for maximum international recognition, making use of primarily digital marketing to showcase the wealth of our wine tourism offering and our passion and pride to the world. ITB offers the perfect platform for us to share just why Stellenbosch is South Africa’s wine tourism capital and benefit from the leading think-tank of the global tourism industry.“Recent research by Tourism New Zealand found that 13% of all international travellers visit wineries and embark on wine tourism related activities annually. These travellers spend more on average than other leisure travellers and stay longer,” Bolton said, adding: “It is no wonder that destinations like New Zealand are focusing a lot more on wine tourism promotions.”Other campaign elements include an enhanced digital presence across all social media networks and an innovative wine tourism blogger campaign with top international and national travel, lifestyle and food bloggers, between April and September.Stellenbosch Wine Routes, a co-ordinated network of wineries in the Stellenbosch area, was established in 1971, making it the oldest wine route in the country.SAinfo reporterlast_img read more

Soybeans, China, and the rest of the world: Changing of the guard?

first_imgShare Facebook Twitter Google + LinkedIn Pinterest Strong import demand is largely credited with soybean’s relatively high current price, especially in the face of a U.S. soybean yield that currently is a record by 3.4 bushels per acre. China remains the largest source of growth in world soybean imports measured in bushels, but its projected growth rate for the 2016 crop year is smaller than the growth rate for the rest of the world. If this projection holds, it will be the first time China has not had a higher growth rate since it became a continuous soybean importer in the mid-1990s.This study begins with the 1995 crop year and ends with the current projections for the 2016 crop year. Since 1995, China has been a net importer of soybeans. PerspectiveOver the past 20 years, China’s annual imports of soybeans exploded from essentially zero to 3.2 billion bushels currently projected for the 2016 crop year. Its share of world soybean imports grew from 2% to 63%. In contrast, soybean imports by the rest of the world flat lined at 1.3 billion bushels between the 1997 and 2012 crop years. Since 2012, growth has reemerged, with new records set in each crop year starting with 2014. Soybean imports by the rest of the world are currently projected to be 39% higher during the 2016 versus 2012 crop year. Growth pathChina’s percent growth rate in soybean imports has consistently trended lower. Annual average change over five years is used to smooth individual year fluctuations. China’s downward trend in part reflects math. Because economic constraints exist, it is easier for measures of economic activity to have a higher percent change when the measure has a lower than a higher value. More interesting is that the 2016 crop year could be a pivot point. If current projections are realized, the percent growth rate in soybean imports will be smaller for China than the rest of the world for the first time since China emerged as a consistent importer of soybeans. For the world as a whole, the growth in soybeans import is now faster than at any time since the early 2000s.Notwithstanding the Importance of the preceding point, it is equally important to note that, because of its dominant size in the world soybean import market, China remains the dominant actor in terms of the growth in physical quantity of soybean imports. For example, since 2012, China’s imports of soybeans measured in million bushels have increased twice as much as imports by the rest of the world.In terms of countries besides China with the highest growth in soybean imports measured in million bushels since 2012, it is a diverse, worldwide collection of countries. About the only common denominator is that they are not among the countries with the highest per capita income.Summary observations are:China’s growth rate for soybean imports is slowing.The 2016 crop year could be a pivot year. If current projections hold, percent growth in soybean imports will be lower for China than the rest of world for the first time since China emerged as a consistent importer of soybeans in 1995.Although China remains dominant in terms of annual growth in physical quantity of soybean imports, the preceding point clearly implies that it is no longer sufficient to simply follow China to understand demand growth for soybeans. A worldwide perspective is needed.Growth in soybean imports by the rest of world since 2012 underscores the important role of price in demand growth, in this case the decline in prices since 2012.Moreover, the double digit growth in China’s demand for soybean imports until recent years was likely a factor in the non-growth in soybean imports by the rest of the world between 1997 and 2012 as China’s growth crowded out growth by other countries.Reemergence of growth in soybean imports by the world outside of China is a positive price factor going forward. However, price is a function of the growth in both supply and demand. Thus, as for the last half century, a key question for world grain and oilseed markets is whether demand for soybeans grows faster than the yield of soybeans? If the answer is yes, the price of soybeans must be high enough relative to other crops to pull more acres into soybean production.last_img read more

Now, Punjab farmers to protest

first_imgAs Mandsaur in Madhya Pradesh remained on the boil two days after five farmers were killed in police firing, Punjab farmers have announced a protest for June 12 to highlight their plight.Seven farmers’ unions met at Moga on Thursday and took the decision.The demands of the unions included immediate farm loan waiver and implementation of the Swaminathan Commission’s report, which recommended that the minimum support prices for crops be fixed at 50% more than the weighted average cost of production. The meeting also condemned the “unprovoked” police firing on the agitating farmers in Madhya Pradesh and demanded action against the accused. “The Congress party came to power in Punjab by promising farmers loan waiver. The party should keep its word. Farmer suicides are rising in the State, so the government should act fast. We want all loans, whether private or government, taken by farmers and labourers waived immediately,” Surjit Singh, president of the Bharatiya Kisan Union (Krantikari), told The Hindu.“We will stage a demonstration in all district headquarters on June 12 and submit a memorandum to the Deputy Commissioners,” Mr. Singh said. Chief Minister Captain Amarinder Singh on Wednesday said while his government was committed to farm loan waiver, the Centre should come up with a holistic policy to address the problem.last_img read more

Jharkhand teacher held for 2017 FB post

first_imgA government college teacher has been arrested here for allegedly writing an “objectionable post” on Facebook two years ago in support of a beef party in Chennai, the police said on Sunday. Jeetrai Hansda, a contractual faculty member at Jamshedpur Co-operative College, was arrested from a village in the Sakchi area of Jamshedpur on Saturday night, an officer said, adding that the teacher had been evading arrest. “Hansda has been booked under various sections of the IPC and the IT Act, and the process to forward him to judicial custody is currently under way,” Rajeev Singh, the officer-in-charge of the Sakchi police station, said. The teacher, a resident of Parsudih here, had allegedly written a post in support of a beef party organised by the IIT-Madras students, prompting the Akhil Bharatiya Vishwa Parishad (ABVP), the student’s wing of the RSS, to file a complaint against him, the officer said. The beef fest was organised at IIT-Madras in 2017 in protest against the restrictions imposed on cattle trade by the Union government. The student’s union had demanded the sacking of Mr. Hansda. The post was then deleted, the officer added. Asked for a reaction, Kolhan University Vice-Chancellor Shukla Mohanty said Mr. Hansda was a guest faculty member at the Graduate School College for Women when he posted the message on Facebook. He was later absorbed as a contractual teacher in the women’s college.Show-cause notice “A show-cause notice was served on Mr. Hansda after receiving a complaint about his objectionable Facebook post, He then apologised,” Mr. Mohanty said, adding that Mr. Hansda had joined as a contractual faculty member at the Co-operative College recently.last_img read more

Limiting TNT import Smith top priority for GInebra ahead of Game 2, says Brownlee

first_imgLacson: SEA Games fund put in foundation like ‘Napoles case’ MOST READ “Number one, we gotta get hold of Smith better. You know, he’s not playing his minutes, but when he’s in there, he’s pretty much unstoppable,” Brownlee, who led the Kings with 24 points, 14 rebounds and six assists, said.“With Smith being a dominant force in the paint, the guy’s been active as well. Mainly, we have to find some type of way to get Smith. You know, keep him off the offensive rebounds. But also other guys, like Williams and some of the guards, too.”Smith grabbed 11 of TNT’s 21 offensive rebounds in the game. The KaTropa got 25 second chance points.ADVERTISEMENT Robredo: True leaders perform well despite having ‘uninspiring’ boss PLAY LIST 02:49Robredo: True leaders perform well despite having ‘uninspiring’ boss02:42PH underwater hockey team aims to make waves in SEA Games01:44Philippines marks anniversary of massacre with calls for justice01:19Fire erupts in Barangay Tatalon in Quezon City01:07Trump talks impeachment while meeting NCAA athletes02:49World-class track facilities installed at NCC for SEA Games World’s 50 Best Restaurants launches new drinking and dining guide View comments Heart Evangelista admits she’s pregnant… with chicken WATCH: Firefighters rescue baby seal found in parking garage Sports Related Videospowered by AdSparcRead Next What ‘missteps’?center_img Don’t miss out on the latest news and information. LATEST STORIES Cayetano dares Lacson, Drilon to take lie-detector test: Wala akong kinita sa SEA Games Joshua Smith on his slow start: I was holding back 1 dead in Cavite blast, fire Heart Evangelista admits she’s pregnant… with chicken PBA IMAGESBarangay Ginebra’s adjustments heading into Game 2 revolve around TNT import Joshua Smith.Justin Brownlee said figuring out how to limit Smith should be one of the Gin Kings’ main priorities in practice after the former Georgetown Hoyas slotman powered the KaTropa to a win with a game-high 35 points in the semifinals opener Sunday night.ADVERTISEMENT “He’s a dominant force in the paint, so we have to maybe do something different, maybe something, I don’t know. But we go to practice tomorrow (Monday). Coach Tim (Cone) will have something for us. We’re going to look forward to that,” Brownlee said after Ginebra’s 100-94 loss at Mall of Asia Arena.The Gin Kings threw two to three defenders at the 6-foot-8, 300-pound Smith.FEATURED STORIESSPORTSSEA Games: Biñan football stadium stands out in preparedness, completionSPORTSPrivate companies step in to help SEA Games hostingSPORTSMalditas save PH from shutoutIt appeared as if Ginebra’s defensive game plan was working in the first two quarters where Smith scored only six points, but the second half showed the Gin Kings had no answer for him.Smith scored 29 points after halftime, including 18 in the third quarter. He also finished with 13 rebounds and four assists in less than 29 minutes off the bench.last_img read more