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first_imgThis story is not about Enron and Exxon, but about introns and exons.  The proportions of the scandals they are causing in evolutionary theory, however, may be comparable.    Introns are spacers between genes.  For several decades now, it has been a puzzle why they are there, and why a complex machine called a spliceosome takes them out and joins the active genetic parts – the exons – together. Only eukaryotes have spliceosomes, though; mitochondria have “group II introns” and some mRNAs may have them.  Their presence and numbers in various groups presents a bewildering array of combinations.  Figuring out a phylogenetic tree for introns has eluded evolutionary geneticists, as has understanding their origin and functions (02/18/2005).  Why do genes come in pieces that have to be reassembled?     William Martin and Eugene Koonin said in Nature1 that “The discovery of introns had a broad effect on thoughts about early evolution.”  Some theories have been falsified, and others remain in the running.  Consider the scope of the problems:A current consensus on introns would be that prokaryotes do indeed have group II introns but that they never had spliceosomes; hence, streamlining in the original sense (that is, loss of spliceosomal introns) never occurred in prokaryotes, although it did occur in some eukaryotes such as yeast or microsporidia.  An expansion of that consensus would be that spliceosomes and spliceosomal introns are universal among eukaryotes, that group II introns originating from the mitochondrion are indeed the most likely precursors of eukaryotic mRNA introns and spliceosomal snRNAs, and that many—conceivably most—eukaryotic introns are as old as eukaryotes themselves.  More recent are the insights that there is virtually no evolutionary grade detectable in the origin of the spliceosome, which apparently was present in its (almost) fully fledged state in the common ancestor of eukaryotic lineages studied so far, and that the suspected source of introns—mitochondria, including their anaerobic forms, hydrogenosomes and mitosomes—was also present in the common ancestor of contemporary eukaryotes (the only ones whose origin or attributes require explanation).    This suggests that intron origin and spread occurred within a narrow window of evolutionary time: subsequent to the origin of the mitochondrion, but before the diversification of the major eukaryotic lineages.  This, in turn, indicates the existence of a turbulent phase of genome evolution in the wake of mitochondrial origin, during which group II introns invaded the host’s chromosomes, spread as transposable elements into hundreds—perhaps thousands—of positions that have been conserved to the present, and fragmented into both mRNA introns and snRNA constituents of the spliceosome.This means that a complex molecular machine, the spliceosome (09/17/2004, 09/12/2002), appeared fully formed almost abruptly, and that the intron invasion took place over a short time and has not changed for hundreds of millions of years.  They submitted a new hypothesis:Here we revisit the possible evolutionary significance of introns in light of mitochondrial ubiquity.  We propose that the spread of group II introns and their mutational decay into spliceosomal introns created a strong selective pressure to exclude ribosomes from the vicinity of the chromosomes—thus breaking the prokaryotic paradigm of co-transcriptional translation and forcing nucleus-cytosol compartmentalization, which allowed translation to occur on properly matured mRNAs only.   (Emphasis added in all quotes.)But this means that the nucleus, nucleolus and other complex structures also had to appear in a very brief period of time.  It means that the engulfed organism that somehow became mitochondria had to transfer its introns rapidly into a genome lacking a nucleus.  It means the nucleus had to evolve quickly to segregate the new mitochondrial genes from the nuclear genes.  A lot had to happen quickly.  “This bipartite cell would not be an immediate success story: it would have nothing but problems instead,” they admitted, but they believed that natural selection would favor the few that worked out a symbiotic relationship with their new invaders.    This is not the end of the problems.  The group II introns would have had to embed themselves with reverse transcriptase and maturase without activating the host’s defenses, then evolve into spliceosome-dependent introns and remain unchanged forever after.  Then those embedded group II introns would undergo mutational decay, interfering with gene expression.  Will this work without some miracles?A problem of a much more severe nature arises, however, with the mutational decay of group II introns, resulting in inactivation of the maturase and/or RNA structural elements in at least some of the disseminated copies.  Modern examples from prokaryotes and organelles suggest that splicing with the help of maturase and RNA structural elements provided by intact group II introns in trans could have initially rescued gene expression at such loci, although maturase action in trans is much less effective than in cis.  Thus, the decay of the maturase gene in disseminated introns poses a requirement for invention of a new splicing machinery.  However, as discussed below, the transition to spliceosome-dependent splicing will also impose an unforgiving demand for inventions in addition to the spliceosome.A spliceosome is not an easy thing to invent; it has five snRNAs and over 200 proteins, making it one of the most complex molecular machines in the cell.  Not only that, they appeared in primitive eukaryotes and have been largely conserved since.  Perhaps the miracles can be made more believable by dividing them into smaller steps:It seems that the protospliceosome recruited the Sm-domain, possibly to replace the maturase, while retaining group II RNA domains (snRNAs) ancestrally germane to the splicing mechanism.  While the later evolution of the spliceosome entailed diversification with the recruitment of additional proteins—leading to greater efficiency—the simpler, ancestral protospliceosome could, in principle, rescue expression of genes containing degenerate group II introns in a maturase-independent manner, but at the dear cost of speed.Will a lateral pass from maturase to incipient spliceosome during a long field run lead to a touchdown?  If a stumbling protospliceosome could survive, in spite of vastly decreased translation rate, it might have been able to run the distance with natural selection’s encouragement, they think.  Players would be falling left and right in this “extremely unhealthy situation,” they say, and “the prospects of any descendants emerging from this situation are bleak.”  How could the game go on, then?  “The only recognizable mechanism operating in favour of this clumsy chimaera is weakened purifying selection operating on its exceptionally small initial population.”  Purifying selection means weeding out losers, not adding new champions.  “Finding a solution to the new problem of slow spliceosomes in the presence of fast and abundant ribosomes required an evolutionary novelty.”    They winnow down the possibilities.  Getting instant spliceosomes smacks too much of an improbable feat.  Getting rid of spliceosomal introns from DNA apparently did not occur.  Their solution?  The invention of the nucleus, where slow spliceosomes could operate without competition from fast ribosomes.    This adds new miracles, however.  The nucleus has highly complex pores that permit only authenticated molecules into the inner sanctum.  They think, however, that it must have happened, somehow: “Progeny that failed to physically separate mRNA processing from translation would not survive, nor would those that failed to invent pore complexes to allow chromosome-cytosol interaction.”  So pick your miracles: since necessity is the mother of invention, “The invention of the nucleus was mandatory to allow the expression of intron-containing genes in a cell whose ribosomes were faster than its spliceosomes.”    The near-miraculous arrival of the nucleus is underscored by other feats it performs: “In addition to splicing, eukaryotes possess elaborate mRNA surveillance mechanisms, in particular nonsense-mediated decay (NMD), to assure that only correctly processed mature mRNAs are translated, while aberrant mRNAs and those with premature termination codons are degraded.”  How could this originate?  Again, necessity must have driven the invention: “The initial intron invasion would have precipitated a requirement for mechanisms to identify exon junctions and to discriminate exons (with frame) from introns (without frame), as well as properly from improperly spliced transcripts.  Thus, NMD might be a direct evolutionary consequence of newly arisen genes-in-pieces.”  But then, if it is verified that some translation occurs in the nucleus, that would be “difficult to reconcile with our proposal.”    They ended with comparing their hypothesis with others.  “Our suggestion for the origin of the nucleus differs from previous views on the topic,” they boasted, “which either posit that the nuclear membrane was beneficial to (not mandatory for) its inventor by protecting chromosomes from shearing at division, or offer no plausible selective mechanism at all.”  At least theirs is simpler and includes some requirements to select for the cells with the best inventors – or the ones with the luckiest miracles.1Martin and Koonin, “Hypothesis: Introns and the origin of nucleus-cytosol compartmentalization,” Nature 440, 41-45 (2 March 2006) | doi:10.1038/nature04531.Was any of this storytelling useful?  The shenanigans they pulled, couched in biochemical jargon, can be summarized by two principles in their own imaginations: (1) since the cell needed these superbly-crafted machines, it had to invent them somehow, and (2) since evolution is a fact, it had to happen somehow.  Do you catch any hint of a mechanism for actually inventing a 200-protein supermachine that would actually work?  Did you find any hint that any cell any time had a “protospliceosome” that only worked half-way?  All this was pure fiction built on childlike faith in evolution.    Presenting a hypothesis in science is fine, but how would they ever test something like this?  They offered a few tests that could discriminate between their just-so story and other just-so stories, but nothing that could explain how a spliceosome, or a nuclear membrane with its elaborate pore complexes, or nonsense-mediated decay could have been invented from scratch just because a cell needed these things.    Would that evolutionists would get off this storytelling kick and do something useful with their lives.  Let’s find a cure for cancer.  Let’s find better sources of energy, and think of ways to reduce risks of disease and terrorism, and use science to improve our lives and our world.  Stringing together uncooperative data into a fictional account of prehistory will accomplish nothing and is wasting time and money in a world desperately in need of the productive possibilities of true science.(Visited 10 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

first_imgSignificant amounts of sunshine and good, prevalent wind conditions have given South Africa the perfect opportunity to diversify its energy generation plan, moving away from a reliance on fossil fuels towards “green” renewable energy.Given its favourable climate conditions, South Africa is more than adequately suited to take advantage of wind and solar energy. With almost 100 projects across the country, either fully operational or in the planning stages, South Africa has an opportunity to use renewable energy as an economy grower. Pictured is the Darling Wind Farm on the Western Cape coast. (Image: Wikipedia)CD AndersonIn line with the South African government’s official outline towards a cleaner economy, taking advantage of renewable energy, in the form of solar and wind power, and building private-public partnerships are key discussions at the World Economic Forum: Africa 2017, being held in Durban, South Africa from 3 to 5 May 2017.Renewable energy plays an important role in powering the country and developing its economy.South Africa currently has almost 100 renewable energy projects either fully operational or at various build stages to be completed over the next five to 10 years. Projects, while focused predominately on wind and solar energy, include biomass (plant photosynthesis energy) and hydro-electric ventures. Of the 100 projects, 53 up and running enterprises focus on solar and wind, with a combined energy capacity of more than 4,000MW.The work being done is the product of co-operation between the government, the private technology sector, and research and science bodies.Here is an infographic featuring nine flagship wind and solar projects around South Africa:Source: Energy.org.za, WEF Africa 2017Would you like to use this article in your publication or on your website? See Using Brand South Africa material.last_img read more

first_imgShare Facebook Twitter Google + LinkedIn Pinterest African swine fever has been sweeping through various pockets of the world, threatening the pork market. While this disease has been around for many years, it’s only been in the last year that concern has ramped up about this highly contagious disease. Ohio Farm Bureau Director of Water Quality and Research Jordan Hoewischer discusses why this is the case during a recent Field Day podcast with insight from Dr. Paul Sundberg, executive director of the Swine Health Information Center, and Dr. Liz Wagstrom, chief veterinarian at the National Pork Producers Council.What is African swine fever? It’s a highly contagious viral disease with a high mortality rate and affects both domestic and wild pigs. Multiple strains exist with some more virulent than others.Is it in the United States? No. It’s been found in Africa, Eastern Europe, Southeast Asia and China where it infected the largest pig herd in the world. China has more than half the world’s pork production and markets 500-600 million pigs per year compared to 120 million in the United States.Is the disease a threat to human health? No. It can’t be transmitted from pigs to humans and is not a food safety issue.Is there a cure? No. Currently there is no treatment or vaccine available. The only way to stop the disease is to depopulate affected herds.What are the symptoms? The disease causes hemorrhaging throughout the organs, and symptoms include fever, discolored skin that is purplish in color, weakness, diarrhea and vomiting and coughing or difficulty breathing.What is being done to prevent it from infecting U.S. herds? The Swine Health Information Center has been collaborating with swine veterinary diagnostic labs across the United States to report endemic diseases and keep an eye out for possible cases. The center also has increased education efforts about African swine fever to pork producers and veterinarians. More intense border protection measures have been put in place with a proposal to add 600 more agricultural inspectors. Additionally, some states have joined forces on developing a response protocol if African swine fever is found there.Learn more about African swine fever and other emerging issues in agriculture by subscribing to the Field Day with Jordan Hoewischer podcasts.Full transcriptlast_img read more

first_imgShare with your Friends:More Cache In Trash Out WeekendWe hear it all the time, “Geocachers are the nicest people!” It’s a wonderful compliment that good-hearted geocachers have earned for over a decade. Cache In Trash Out (CITO) weekend is just another example of geocachers giving back. Since 2002, tens of thousands of geocachers have cleaned up parks, trails and other geocaching-friendly destinations. Geocachers plan CITO events year round, but one weekend each year the global geocaching community unites to cleanup tons of trash together.CITO Event in TexasThe 11th Annual CITO weekend is scheduled for April 20, 21, and 22 2013. There will be hundreds of events to attend in dozens of countries, but if there’s not one in your area, it’s time to gather your friends and create your own CITO Event. Be sure to check the CITO Event calendar for gatherings near you.Those attending CITO Events on April 20, 21 or 22 (or all three!) will earn a 2013 CITO Souvenir for their Geocaching profile. Thanks for keeping the geocaching a community one of the nicest groups of people out there![Editor’s note: This video is spoken in German and Czech. Click the CC button for English, German or Czech subtitles.][vsw id=”HOqobTmkbbU” source=”youtube” width=”425″ height=”344″ autoplay=”no”] SharePrint RelatedWill You CITO?March 24, 2013In “Cache In Trash Out”CITO 2013 – It Takes a VillageApril 22, 2013In “Cache In Trash Out”Join a Worldwide Geocaching MovementApril 8, 2013In “Cache In Trash Out”last_img read more

first_imgrichard macmanus The popularity of Twitter has produced a number of clones in China, just as there are Facebook clones. Some of China’s Twitter clones have been closed down by the Chinese government, but some have survived. We take a look at both cases in this post. We also assess Twitter’s chances of success in China, should it ever be freed from the ‘Great Firewall of China.’ Fanfou, Jiwai and Digu were some of the first Twitter clones to become successful in China. Howeverall three – plus Twitter itself – were blocked by the Chinese government in July 2009, because of their usage during the uprisings in Ürümqi. According to an AFP article, Chinese authorities blamed online agitators for helping to stoke violence in that region. Prior to being shut down, Fanfou had been dubbed “China’s Twitter” and had almost reached 1 million registered users by the end of June 2009. An October 2009 report by China Daily noted that Fanfou was founded in July 2007 by Wang Xing, a young entrepreneur who also founded China’s current most popular social network Renren (formally known as Xiaonei). Both Renren and Fanfou were almost carbon copies of their U.S. equivalent services – Facebook and Twitter respectively. Facebook is Becoming Less Personal and More Pro… Guide to Performing Bulk Email Verification The Dos and Don’ts of Brand Awareness Videos Weibo Rises to Take Fanfou’s PlaceSince the closure of Twitter, Fanfou, Jiwai and Digu, other services have risen to take their place. Taotao (owned by the company that produces popular IM service QQ) andZuosa.com are two examples. However it isWeibo that has emerged to become the biggest micro-blogging service in China. Weibo is owned by Sina.com, a huge portal company in China, and is connected to Sina’s blogging platform. Weibo is very much like Twitter, in that it allows users to post short messages 140 Chinese characters or less via the Web, SMS or MMS. Although according to Chinese Internet expert and Beijing resident Kaiser Kuo, in Chinese 140 characters can actually produce quite a long message.The major difference between Weibo and Twitter, according to Kuo, is that Weibo is censored. Or in the parlance of Chinese Internet users, it is “harmonized.”Sina’s Weibo probably has a much greater chance of surviving than its counterparts like Twitter and Fanfou, because it knows how to self-censor. Meng Bo, deputy editor-in-chief of Sina.com and project manager of Sina Weibo, told China Daily in October that “Sina is playing by the rules as they are laid down, with strict word filtering in operation.”According to Meng, there are two teams of staff “keeping close watch to ensure there is no vulgar content or anything that violates the rules.” Would Twitter Succeed in China Anyway?China’s surviving micro-blogging services are tightly controlled by the censorship climate in China. However even if Twitter became available again in China, would it take off with mainstream Chinese Internet users? Kaiser Kuo thinks that it wouldn’t, because of the popularity of currently operational services like Weibo and Taotao. He remarked that although there would be an uptake in the number of users on Twitter, if it was ever to be made available again, Weibo and others will have gained too much momentum by then. Related Posts Tags:#international#NYT#twitter#web A Comprehensive Guide to a Content Auditlast_img read more

first_imgOdisha’s ruling Biju Janata Dal on Wednesday won the Patkura Assembly constituency by defeating the BJP. The Congress finished third in the election held on July 20.BJD nominee Sabitri Agarwalla defeated BJP’s Bijoy Mohapatra by 17,920 votes. Ms. Agarwalla bagged 96,017 votes, while Mr. Mohapatra got 78,097 votes and lost yet another battle to enter the State Assembly for another term. Jayanta Mohanty of the Congress secured only 2,104 votes by the end of last round of counting of votes. Mr. Mohapatra, who won from Patkura four times – 1980, 1985, 1990 and 1995, was a member of Biju Patnaik’s Council of Ministers in his last term. Although he was a founder-member of the BJD, Mr. Mohapatra failed to contest the 2000 polls when the party cancelled his ticket at the last minute. He lost all elections in subsequent years. In 2001, he formed the Odisha Gana Parishad, which he later merged with the Nationalist Congress Party. He joined the BJP when the NCP turned an ally of the BJD before the 2009 polls. Often referred as Chief Minister and BJD president Naveen Patnaik’s bête noire, Mr. Mohapatra quit the BJP in November last, but returned to the party again before this year’s general election.Polling in Patkura, which was initially scheduled for April 29 as part of the simultaneous Lok Sabha and Assembly elections, was first adjourned due to the death of the Biju Janata Dal nominee – Ms. Agarwalla’s husband Bed Prakash Agarwalla.The Election Commission of India then fixed May 19 as the next date of polling, but it was postponed again due to Cyclone Fani that hit the State’s coast on May 3.The seat witnessed high-voltage campaigning, with senior leaders from the three major parties holding meetings to woo the voters. Mr. Patnaik also campaigned for Ms. Agarwalla for a day apart from a majority of his Ministers and party MLAs.last_img read more

first_imgViacom’s Comedy Central has launched a two-hour programming block on the TMF channel in Belgium. The Comedy Channel block will air on Viacom-owned TMF, which broadcasts to the Flemish region of Belgium, from 22:00-24:00.The channel kicked off its Belgian launch with a promotional spoof of YouTube video Push to add drama, which it said was picked up by all major Belgian news media.last_img