Plants perform a wonder that has attracted the admiration of scholars from ancient Egypt, Greece and Rome to modern times: the ability to reproduce mathematically perfect patterns. This ability, called phyllotaxis, can be described mathematically with the Fibonacci Series and the Golden Angle. The beautiful spirals in sunflowers, artichokes, cacti, dandelion heads and other plants continue to fascinate children and adults today, but those are not the only examples. Leaves on a stem can emerge in phyllotactic patterns like a spiral staircase, and depending on the environment, plants can switch patterns at different stages in development. Scientists have learned a lot about the players in the phyllotaxis game, but still do not understand the script. The details of how genes and proteins produce the patterns remain elusive. In Current Biology,1 French biologists Jean-Christophe Palauqui and Patrick Laufs recounted some of the theories that have tried to explain phyllotaxis. Scientists know that the plant hormone auxin becomes concentrated in the shoot meristem where new organ primordia emerge, and that the PIN1 auxin transporter is able to polarize the localization of auxin. New work reported in the same issue of Current Biology implicates the PLETHORA (PLT) gene family, known to be active with root formation, with the processes going on in the meristem. Tinkering with the players can enhance or inhibit pattern formation. Just how these players interact, though, is not well understood. It’s not a simple case of gene turning on protein turning on hormone; each of the players signal each other back and forth in a complex choreography. In addition, the PLT genes seem able to stimulate mechanical forces in the primordia by the way they regulate PIN1 polarity and hence auxin distribution. There are also time delays between gene expression and downstream effects, such as 4 hours from the time PLT genes activate to the time PIN1 transcript levels are seen to increase. But then, auxin level can also feed back to regulate PIN1 expression. It appears, therefore, that the intra-player signaling is indirect and complex. The authors stated that the bewildering interactions of these players keeps biologists busy: “Elucidating the mechanism underlying PLT-mediated control of phyllotaxis will be challenging and likely depend on quantitative descriptions and modeling of PLT expression, PIN1 levels and polarization, auxin distribution, growth and mechanics,” they said. Even if these problems are solved with mechanistic theories some day, questions may still remain about how a seed with no phyllotaxis results in a mature plant with it. And beyond that, philosophers of aesthetics may continue to ponder how plants – and many other phenomena in nature unrelated to them, like spiral galaxies, hurricanes, conch shells, and the cochlea in the human ear – reproduce “divine proportions” that humans find beautiful (see article by Fred Willson at ICR and the 11/20/2003 entry). 1. Jean-Christophe Palauqui, Patrick Laufs, “Phyllotaxis: In Search of the Golden Angle,” Current Biology, Volume 21, Issue 13, R502-R504, 12 July 2011, DOI 10.1016/j.cub.2011.05.054. Explaining the mechanics of something does not explain its origin. You can understand how a robot on an assembly line works, and describe its structures and functions with flowcharts, equations and blueprints. That knowledge will not explain why it produces a Mercedes. Wikipedia trivializes the explanation as a consequence of natural selection, claiming that the solution was found within a decade of Darwin by Wilhelm Hofmeister. “Questions remain about the details,” the entry oversimplifies. If that were true, the scientists publishing in this week’s Current Biology would not remain baffled by it. The devil is often in the details. Hofmeister knew nothing of PIN1 and PLT, let alone the genetic code. His simplistic model of competing mechanical forces is so 1896; it cannot satisfy observers today, with our newer knowledge of genetic codes, proteins, and cell signals. If evolutionists do some day get all the mechanics worked out, the questions stated above will still remain. Considering that not all plants employ phyllotaxis, and that the patterns seem unnecessary for survival, unguided evolution reduces to an empty hand-waving story that “amazing stuff happens sometimes.” The same criticism can be leveled at any explanation employing impersonal, material causes. Take a deeper look at that sunflower. Here is a natural wonder that calls out for better science, deeper philosophy, and perhaps most of all, sound theology.(Visited 38 times, 1 visits today)FacebookTwitterPinterestSave分享0
4 June 2012South Africa’s Bafana Bafana scraped a 1-1 draw against lower-ranked Ethiopia in their first 2014 Fifa World Cup qualifier in Rustenburg, North West province on Sunday, thanks to a last-gasp goal by Katlego Mphela.Ethiopia are currently 138th in the world rankings, compared to South Africa’s 67th.A small crowd, including a strong Ethiopian representation, was on hand for the match, and the visitors’ supporters walked away by far the happier group of fans.Bright startBafana started brightly enough as Anele Ngconga brought a save out of the Ethiopian goalkeeper in the first minute.There was an early opportunity for the Premier Soccer League’s top goal scorer, Siyabonga Nomvethe, after a defensive error by Ethiopia, but he chose to square the ball rather than shoot when there was no support in the middle.The home side enjoyed the lion’s share of possession, but the East Africans stood firm and kept most of South Africa’s attempts on goal to shots from distance.There was a moment of concern for the visitors when a free-kick taken by Mphela was spilled by goalkeeper Sisay Bancha Basa, but he was able to regain control of the ball under pressure from two South African players.Sucker punchBafana Bafana were in the driving seat, but found themselves floored by a sucker punch in the 28th minute when the Ethiopians took the lead. Saladin Said dispossessed Tsepo Masilela and let fly with a powerful strike that rattled the underside of the South African crossbar and flashed into the net.Masilela’s day became even worse just five minutes later when was forced from the field by an injury, with Punch Masenamela replacing him.Just a minute before the break, Said fired narrowly wide with a powerful shot.With South Africa behind by a goal at half-time, Mosimane opted to replace midfielder Reneilwe Letsholonyane with Oupa Manyisa.Numbers behind the ballEthiopia worked hard after the break to get numbers behind the ball on defence, which made Bafana’s attempts to break down their defence more difficult, but they nonetheless managed to create a number of opportunities. However, the finishing was invariably wide of the mark.Captain Steven Pienaar and Mphela created a good chance 20 minutes into the second half, but the goalie was able to deny Mphela, saving the striker’s header with a out-stretched leg.Defender Morgan Gould got onto the end of a corner, but headed high of the mark.GoalAt last, in the 77th minute, South Africa managed to equalise. After Mphela picked up a pass on the left, he created a little space and then curled a right-footed shot beautifully around the goalkeeper into the far corner to make it Bafana Bafana 1, Ethiopia 1.Buoyed by the goal, the home side pushed hard for victory, and only a couple of minutes later Pienaar had a gilt-edged chance to put South Africa ahead when he received a pass from the left. He was right in the middle of the goal box, with plenty of time to finish, but fired miserably wide and high with a side-footed effort.A long range effort from Manyisa passed high over the bar with just four minutes remaining on the clock as Bafana desperately sought a winner.Extra five minutesWith regulation time up, an extra five minutes were added and Bafana furiously chased a second goal, but it was not to be.A free kick in a favourable position was taken by Mphela, but his shot was blocked, while Masanemela came close, but was just wide with another attempt.Finishing problemThe last time Bafana won a game was in August 2011, when they beat Burkina Faso 3-0 in a friendly. The last time they won a competitive match was in March 2011, when they edged Egypt 1-0 in Johannesburg after a last-gasp goal by Katlego Mphela.Again, it was South Africa’s finishing that left much to be desired. Coach Pitso Mosimane, however, afterwards refused to take the blame.Talking to Kickoff Magazine, Mosimane said: “How do I sort out the finishing [problem] of South African football? Siyabonga Nomvete is the only one who scored [many goals in the PSL], and I had him in the field. He scored 20 goals and he is here.“You can’t say this team doesn’t create chances, hey. Let’s play fair! I only have the players for seven days.”Mosimane blamed South African football’s development programmes, saying: “Whether I am here or not, they will miss the chances. Let’s be shrewd on our development programmes.”Bafana next face Botswana on 9 June in Gabarone in their second 2014 Fifa World Cup qualifier. It may be that playing away from home will take some pressure off Bafana, but the bottom line is they need to win.Would you like to use this article in your publication or on your website? See: Using SAinfo material
A Dalit man on September 26 staged a sit-in along with his four children at the Siddharth Nagar district magistrate’s office, protesting against the alleged ouster of his children from the school for his inability to pay fees.The father, Shiv Kumar, told reporters that the Saraswati Shishu Vidya Mandir at Shohratgarh area in Siddharth Nagar ousted his children, Viraj (4), Yuvraj (8), Jyoti (10) and Chanchal (14) on August 30 for not paying the school fees. He said the school principal even made casteist remarks against him when he met him to explain his inability to pay the fees.“I also went to the police but my they did not register my complaint,” he said, adding he also wrote to the district magistrate and to Basic Education Minister Satish Dwivedi apprising them of the cancellation of his children’s admission from the school.“If my children do not get justice, I will sit on fast unto death,” he saidAsked about the incident, Basic Education Minister Satish Dwivedi told reporters that he would speak to the district magistrate on the issue and take requisite action, if the school administration is found guilty.