How Cells Thread a Needle

first_imgYour challenge today is to invent a machine that can push a wet noodle through a straw.  It can’t pull it.  First it has to grab the end, then push it through without breaking it.  Oh, and there’s a catch; the straw has a plug at the far end and a constriction inside.  Give up?  Maybe you should watch how cells do it.  The mechanism was described by Anastassios Economou in Nature this week.1    Cells have to do this kind of thing all the time, so they have specialized machinery for the task.  The wet noodles are protein chains in their unfolded state.  The straws are narrow channels through membranes that are normally in a plugged configuration.  Just outside the straw entrance are several precisely-fitted proteins that first attract the chain and cradle it gently between two halves that swivel shut.  As one half tilts, it causes the constriction in the tunnel to open up.  The two parts then fit together like hands, and use a powered motor to gently send the noodle through.    Economou included a schematic diagram of the five-part mechanism that pushes the proteins through.  (He included a couple of stylized hands to show how the delicate grasping and pushing is done.)  Here’s the caption:This simplified representation is based on both earlier studies and the new findings.  In this cut-away view of the membrane, the SecA motor lies flat against the cytoplasmic side of the SecY channel (yellow), and consists of a two-domain ATP-powered engine (light and dark blue) and two ‘business-end’ domains (green and magenta; depicted as hands).  a, Initially, the channel pore is sealed by both a constriction halfway through it and a mobile plug domain (not shown) near its exit.  The pre-protein-binding domain of the motor (magenta) is in the open state, exposing an elongated corridor that connects to the entrance of the channel.  This open state is seen in structures of the isolated motor.  b, Swivelling this domain around its stem would allow it to embrace a secretory protein chain.  At this stage, a finger (green) from the second hand of SecA might be in close contact with the chain.  c, When ATP (not shown) is present, the engine conformation changes and the finger could move upwards, pushing or dragging the protein chain into the pore.  This motion, or other conformational changes, leads to the opening of the pore.Details of this mechanism have only recently come to light.  It appears that the machinery puts a gentle stretch on the chain a few links at a time.  Think how earthworms stretch and compress to move through their underground tunnels.  The scientists believe that the SecA-SecY machinery uses a similar technique to propel the protein chains through the channel.  For really long chains, the machinery can repeat the cycle over and over.    Economou described how difficult it is to observe these nanoscopic machines at work.  “Solving structures of membrane proteins is not a trivial pursuit,” he said.  There are many questions and projects remaining.  The ultimate one, mentioned in his final sentence, is “determining the dynamics of this astonishing cellular nanomachine.”1.  Anastassios Economou, “Structural biology: Clamour for a kiss,” Nature 455, 879-880 (16 October 2008) | doi:10.1038/455879a.Evolution was not mentioned in this paper.  The scientists studied this process in those highly-evolved, large, complex animals known as… bacteria.    OK, Charlie’s got a problem here.  There are half a dozen protein machines involved in this process.  They rotate, swivel and fit together in precise contact.  They are driven by ATP fuel pellets.  The machines must apply the energy precisely for function: in the right direction, in the right amount, at the right time.  Could chance produce such a complex machine?  (Bacteria, in the evolutionary fable, are among the earliest and simplest life-forms to “appear” on the early earth.)    Do the math.  SecA contains 802 amino acid residues; SecY contains 436.  Our online book calculated that getting a 400-unit protein chain by chance would be one in 10240, even under unnaturally favorable circumstances.  That number is already way, way, way beyond the universal probability bound (i.e., it would never happen anywhere in the universe), and we don’t even have one protein of this multi-protein complex.  If by some wildly, radically, absurd stretch of imagination chance arrived at the right sequence for SecY (the shorter of the two proteins), it would be incredibly more unlikely to get the larger one, SecA, which is not only twice as long, but has to fit like lock and key with the first one.  Each of these protein parts is like that.  They all have to work together.  Calling this irreducibly complex is an understatement.  The machine parts don’t just happen to show up at the cell membrane by a random walk and work together for the first time.  They were designed to do what they do, and they do it exquisitely.    Evolutionists would have us believe that natural selection tinkers with whatever parts are available, and complexity just happens.  Sooner or later, though, if you carry that logic too far, you wind up tinkering with nothing.  You could tinker with an existing radio, for instance, to make it pick up new wavelengths, but how far back can you push the tinkering metaphor back until you have nothing but a few random pieces of plastic and wire lying around?  The metaphor also suffers from implicit personification, as if the parts would even want to do such things.  Humans impose their sense of design on molecules that have no ability to plan ahead and work together, and no reason to do so.  Left to themselves, they would randomize.    Economou has given us occasion to discuss economics.  The bankruptcy of evolutionary theory becomes more evident with each new investigation.  Trying to bail it out with public credulity is not going to make it recover.  The Darwin Party oligarchy needs to stop tinkering and tampering, remove its protectionist barricades, and let free inquiry have its way.  Intelligent design has the intellectual capital to inject into the logic markets.  Liquidity will result, knowledge banks will open up, and public confidence will stabilize the scientific institutions.  Freedom to invest in the best explanations, wherever the evidence leads, will once again usher in a prosperous era of bullish science.(Visited 14 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

African free trade area ‘boost for BRICS’

first_img15 June 2011The historic $1-trillion African free trade area, the first vital steps towards which were taken over the weekend, will serve as a major boost for the BRICS grouping, says International Marketing Council of South Africa CEO Miller Matola.Leaders of 26 countries African countries, meeting in Johannesburg over the weekend, agreed to formally launch negotiations to establish a grand free trade area pulling together three regional economic communities, namely the Common Market for East and Southern Africa, the East African Community and the Southern African Development Community.The agreement centres on creating the continent’s biggest free trade bloc to create a single continent-wide market estimated to be worth $1-trillion by 2013. The countries involved have an aggregate GDP of US$860-billion and a combined population of 590-million.One massive market“The BRICS countries [Brazil, Russia, India, China and South Africa] will welcome the prospect of interacting with a combined unit rather than having to deal will the countries in question on an individual basis,” Matola said in a statement on Monday.“In similar vein, the envisaged grand free trade area would contain considerably more muscle than its constituent parts.”The BRICS members would then deal with one massive market, instead of 26 separate ones, Matola said. South Africa, being both a member of BRICS and of the soon-to-be free trade area, would be particularly advantaged.Matola predicted that the free trade area would promote greater interaction between BRICS and Africa, especially in light of the International Monetary Fund’s optimism about Africa’s growth potential, and the likelihood that the free trade area would draw other African countries into joining.While Africa is a growing opportunity and experiencing the third-fastest growth behind China and India, a mere 10% of Africa’s trade is between fellow countries on the continent.South Africa ‘will not dominate’Briefing journalists in Parliament in Cape Town on Monday, Trade and Industry Minister Rob Davies said that although South Africa was by far the largest economy of the 26 across the three regions, it would not dominate trade when the free trade area was set up, as all members would play a role in negotiations.Added to this, the 25 other member countries did not hold any expectation that South Africa would finance all the continent’s necessary infrastructure development projects, he said.But Davies was quick to point out that South African companies should get involved in key infrastructure projects, such as the North-South Corridor which cuts through Zambia and Zimbabwe.He said formal trade blocs would never reach full fruition unless the continent’s infrastructure backlog was addressed. To this end, about 80 projects were already on the go in the North-South Corridor.Countries outside the FTADavies also stressed that the planned free trade area would not necessary affect any trade relationships South Africa had with African countries outside the free trade area.Davies said the idea was to set up a single regional economic community covering all three existing blocs.Next up for discussion would be to include West African countries in the free trade negotiations, he said, explained that practical considerations meant the three grouping that met in Johannesburg were already predisposed to working together.Many of the members of the three blocs were already members of more than one of these regional economic communities, which meant they had to work together, particularly in achieving a unified customs union. Under World Trade Organisation rules, member countries cannot be a member of more than one customs union.First phase ‘in three years’The first phase of setting up the 26-country free trade area is expected to come into effect in three years, Davies said, noting that member countries had agreed to carry out negotiations in two phases, with the first to be concluded within 36 months.Phase one, the current phase, was a trading goods agreement dealing with tariff liberalisation, rules of origin, dispute resolution, customs procedures and simplification, transit procedures and non-tariff barriers.The first phase would also include the movement of business people across the three regions, Davies said.Phase two would tackle trading services, competition policy and intellectual property rights across the three regional blocs. A work programme to address industrial development still needed to be set up. Davies said that although no time-frame had been set as yet for the conclusion of this phase.He said the time-period for phase one had been set at a rather short three years as each of the regional economic communities already ran free trade agreements confined to their respective communities.Members from the three regional economic communities had also committed to ongoing monitoring and negotiations.Two committees had been set up, namely a tripartite trade relations committee, which would file quarterly reports, and a sectoral ministerial committee on trade, which is expected to meet every six months and report to the council of ministers on negotiations.Davies said negotiations would allow for special differential treatment so that smaller states would be treated more leniently in the implementation of tariffs and other objectives.Added to this, nothing would be agreed upon until everything was agreed in full, he said.At home, the South African government would engage at every stage with business and labour through the National Economic Development and Labour Council (Nedlac).SAinfo reporter and BuaNewslast_img read more

Air Force goes hi-tech in flight training

first_imgRay Maota The simulator is designed to train pilots and flight engineers operating Eurocopter’s AS332 Super Puma and certain compatible machines, including the SAAF’s Oryx medium utility helicopter, manufactured by Denel.(Image: Military Factory) The company which operates and maintains the simulator is Sim Aerotraining, a French aviation training company whose Gauteng headquarters will house the machine.(Image: Eurocopter Southern Africa)MEDIA CONTACTS• Eurocopter Southern Africa+ 27 11 266 2600The first full-motion helicopter flight simulator to arrive in Africa will be used by pilots of the South African Air Force (SAAF) as part of their training programme.Located at aerospace manufacturer Denel’s facility in in Bonaero Park in the east of Johannesburg, the second-hand simulator was acquired by Eurocopter Southern Africa, and was previously used by the Swiss Air Force, originally commissioned there in 1993.Of the approximately 2 500 hours available for use by air forces on the simulator, the SAAF will use 1 000 per year.Eurocopter Southern Africa CEO Fabrice Cagnat said his company is able to provide a diverse range of training programmes by bringing the simulators closer to the pilots who need them for training.“We are confident that the simulator will add significant value, not just in terms of monetary savings for the SAAF, but in real terms, where the object is to save people’s lives.”The simulator is designed to train pilots and flight engineers operating Eurocopter’s AS332 Super Puma and certain compatible machines, including the SAAF’s Oryx medium utility helicopter, manufactured by Denel.With the full-motion version, chopper crews have the chance to hone their skills in all conceivable types of potential emergencies, including some which would be too risky to try with a real helicopter.They can also train as if in mountain and search-and-rescue operations and can use night-vision goggles to make the scenarios as authentic as possible.“Positioning the simulator in Johannesburg, which is easy to get to, is an attractive proposition for all other Super Puma operators,” said Cagnat, adding that the company has noted strong interest from other African countries and further abroad.The company which operates and maintains the simulator is Sim Aerotraining, an international aviation training company whose Gauteng headquarters will house the machine, while Eurocopter focuses on the marketing and sale of the simulator hours.“We could not have done it ourselves in a cost-competitive manner,” said Cagnat, referring to their decision to use Sim for training.Certification for civil use is not yet ready, but Eurocopter is working to achieve this.Improved training programmeThe SAAF currently does not operate the Super Puma, but utilises the locally built and very similar Denel Oryx – which is also developed by Eurocopter. The advantage for the SAAF is that the simulated training will cost 25% less than the actual training using actual aircraft.Up to now South Africa has had to send pilots to Europe to train on simulators there. This meant added budget spent on travel, accommodation and visa costs as well as a stipend for each person and no-show cancellation fees.Acting director for helicopter systems at the SAAF, Colonel Hardus Engelbrecht, said pilots who ordinarily use the Rooivalk and AgustaWestland A109 light utility aircraft will now get the opportunity to train on the simulator.“The current plan is that about 140 pilots and flight engineers will train on the system every year,” he said.SAAF crews need up to 12 hours of emergency training per year, currently all done on real aircraft. The force hopes to reduce these to three hours on the aircraft and nine on the simulator.The acquisition of the technology also coincides with the appointment of the SAAf’s new chief, Major-General Fabian Zimpande Msimang, who starts occupying his position in October.last_img read more

Be the First to Find DNF’s in the Geocaching® app

first_imgThe latest update includes more improvements to core functionality to the Geocaching® app and a few cool additions too…First up, we’ve added DNF’s to the map! As a new feature to the Geocaching® app, we’re excited to see the caches we missed, so we can get back out there turn those frowns upside down. Once you find a cache you previously DNF’d, the yellow smiley will replace the DNF icon. DNF’s (Did Not Finds) will now have a separate icon making them easy to see on both the map and in Lists. SharePrint RelatedWhy You Should Log Your DNF’s – Weekly MailerAugust 22, 2012In “Groundspeak’s Weekly Newsletter”Geocache Icon Run: find the most cache types in one dayApril 19, 2018In “Community”One map. Endless inspiration.January 22, 2019In “News” DNF’s are not always fun to log, but we like to use them as motivation to try again! Plus, they’re helpful to both the community and cache owner. Oftentimes it’s the journey to ground zero that’s the adventure, so log your DNF’s with pride. Add a comment below and share your best DNF story with other geocachers!Next, we want you to know that we’ve been listening. After all, geocaching exists because of you, our community! That’s why we’re pleased to announce that you can now view Attributes in the app. A feature that many of you have been requesting!The cache details page will display up to 5 Attributes with the ability to view more on a separate screen. Additionally, when saving cache info for offline use, Attributes will be included.If you’re just joining the geocaching adventure, Attributes communicate what to expect at a cache location. For example, if a geocache requires tree climbing, you’ll see the tree icon.  Attributes denote permissions, equipment required, hazards, terrain conditions, and more. Attributes are great for planning cache outings so that you can be prepared to earn that smiley!As with all of our releases, we also make other small improvements and fix bugs. The 5.4 update includes an improved process for saving offline lists, easy access to the Help Center from the app, and more. Head to the Geocaching Forums to read about these updates.We’d love to hear what you’re most excited about from the 5.4 release. Tell us in the comments below!Share with your Friends:Morelast_img read more

Clipper Consolidates Bulk Segment

first_imgzoom Copenhagen-based shipping company Clipper Group revealed plans to consolidate its bulk activities into three hubs.“Clipper will simplify its operational and administrative set-up in its strongest field of business, bulk… We will concentrate our bulk business in three locations: Copenhagen, Houston and Hong Kong,” the company said in a statement.Consequently, Clipper will close its offices in Stamford, Sao Paulo, Rio de Janeiro, Singapore and Beijing.As explained, the company’s offices in Barranquilla, Tokyo and Nassau will remain unchanged.“Fewer but larger hubs will allow us to service our customers and to operate our fleet more efficiently,” according to Clipper.“Within the last year, Clipper has grown its operated bulk fleet from 100 to 150 vessels. We want to make communication more effective and our response time to market changes shorter,” Peter Norborg, Clipper Group CEO, commented.Clipper Group operates a fleet of around 150 Handysize and Supramax vessels. In addition to bulk, the company has complementary businesses in the RoRo and ferry segments.last_img read more