Cell Quality Control Runs a Tight Ship

first_imgWithout the surveillance and rapid response of quality control, cells would collapse and die.  Here are some recently-published examples of nanoheroes in action.Plant checkpoints:  Picture a child watching the wonder of a seedling breaking through the soil into the light for the first time.  Within hours, the ghostly-white stem turns green, and a day later, leaves begin to appear.  Does he or she have any idea what is going on at a scale too small to see?  Not until that kid grows into a modern lab scientist with sophisticated equipment.  The transformation requires the coordinated transportation of key elements through specialized checkpoints, an international team reported in PNAS.1    Without boring the reader with technical terms, what basically happens is this.  The underground seedling contains pre-chloroplast parts in readiness for the arrival into sunlight, but saves its energy by not allowing the light-gathering factories to assemble until it’s time.  “Chloroplasts need to import a large number of proteins from the cytosol because most are encoded in the nucleus,” they reported.  Once there, they have a double membrane to get through.  Specialized gates permit entry of the authenticated parts.  One particular light-sensitive part has its own unique gate.  The team decided to see what happened when they mutated one gene in the process.  The results were not pretty: the light-sensitive molecules accumulated outside the plastid because they couldn’t get into the factory.  “After a dark-to-light shift, this pigment operated as photosensitizer and caused rapid bleaching and cell death,” they found.  “Our results underscore the essential role of the substrate-dependent import pathway” that this protein depends on.  Maybe this error resembles a chemical spill outside a pharmaceutical plant, or pistons firing before they get into the engine.Now hear this:  In a surprise finding that might provide hope for the deaf, scientists publishing in PNAS reported that “Restoration of connexin26 protein level in the cochlea completely rescues hearing in a mouse model of human connexin30-linked deafness.”2  Two protein partners are needed for healthy hair-cell formation in the cochlea of the inner ear.  Mutations in one of them, connexin26, account for about half of all cases of inherited human deafness.  Usually, connexin26 and connexin30 join together to form gap junctions, but if one is mutated, deafness results.  The gap junctions are essential for cell-to-cell communication.  Surprisingly, connexin26 (Cx26) appears able to bridge the gap when connexin30 (Cx30) is missing; therefore, “up-regulation of Cx26 or slowing down its protein degradation might be a therapeutic strategy to prevent and treat deafness caused by Cx30 mutations.”    The scientists suspected that these two isoforms of connexins regulate each other.  They also noted that this partnering occurs in the lens of the eye.  Losing one by mutation, therefore, affects the regulation of the partner.  On a hunch that one of the isoforms could compensate for the loss of the other if allowed to assemble, and could build functional gap junctions on its own, they tried up-regulating the remaining connexin.  To their surprise, hearing was completely restored in mice. Bad translator triggers SOS:  We’ve talked about the DNA translation team a number of times (e.g., 12/28/2006, 07/26/2005, 06/09/2003, 04/29/2003).  The team of 20 aminoacyl-tRNA synthetases, as they are called, have rigid requirements.  “Mistranslation in bacterial and mammalian cells leads to production of statistical proteins that are, in turn, associated with specific cell or animal pathologies, including death of bacterial cells, apoptosis of mammalian cells in culture, and neurodegeneration in the mouse,” said Bacher and Schimmel in PNAS.3  “A major source of mistranslation comes from heritable defects in the editing activities of aminoacyl-tRNA synthetases.”  This is because the protein machines, which snap the right amino acid onto the appropriate transfer-RNA (tRNA), cannot perform their vital role in protein synthesis if broken.    These researchers suspected that broken synthetases could also cause mutations.  They decided to test what happens when they caused an “editing defect” in one of them.  (These enzymes are usually able to proofread their own errors with a high degree of accuracy.)  The result, again, was not pretty: “A striking, statistically significant, enhancement of the mutation rate in aging bacteria was found.”  The bug was like flipping a fire alarm: “This enhancement comes from an increase in error-prone DNA repair through induction of the bacterial SOS response,” they explained.  “Thus, mistranslation, as caused by an editing-defective tRNA synthetase, can lead to heritable genetic changes that could, in principle, be linked to disease.”    Another press release from Ohio State also discussed the neurological disease that can result from mistranslated proteins caused by mutated aminoacyl-tRNA synthetases. 1Pollman et al, “A plant porphyria related to defects in plastid import of protochlorophyllide oxidoreductase A,” Proceedings of the National Academy of Sciences USA, 10.1073/pnas.0610934104, published online before print January 29, 2007.2Ahmad et al, “Restoration of connexin26 protein level in the cochlea completely rescues hearing in a mouse model of human connexin30-linked deafness,” Proceedings of the National Academy of Sciences USA, 10.1073/pnas.0606855104, published online before print January 16, 2007.3Jamie M. Bacher and Paul Schimmel, “An editing-defective aminoacyl-tRNA synthetase is mutagenic in aging bacteria via the SOS response,” Proceedings of the National Academy of Sciences USA, 10.1073/pnas.0610835104, published online before print January 30, 2007.Dear Darwinist, does this increase your faith that random accidents in working systems are going to make things better?  Is this a better way to build a plant, an ear, or a translation system?  If you think terrorism is the best way to build a civilization, reread the 12/14/2006 entry. (Visited 8 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

The Practical Guide to Non-Standardized LED Specs

first_imgImage via ARRI.ConclusionWhile comparing the output of light fixtures can be technical and confusing, knowing how much light fixtures actually put out is a great way to narrow your search.Looking for more information on lighting? Check out these articles.How to Shoot Interior Locations with Limited LightingLighting Different Times of DayGrab These Low-Budget Lighting Accessories For Under $10A Practical Guide to Working with Light Stands on SetLight Storm C300d: Aputure’s Brightest LED Light Ever Is Now Available Shopping for LED lighting fixtures can be a headache. However, there a few things you can do to streamline the process and get the right gear.Cover image via Shutterstock.Buying any new piece of filmmaking equipment is usually a fun and enjoyable process. However, at times, it can also be confusing. This is especially applicable when comparing CRI, wattage draw, and lumens vs. LUX for your lighting setup. There seems to be no standardized system between manufacturers to compare fixtures, leaving you to wonder if you’re getting the most output for your money. Let’s take a look at some considerations that should help you across the board.Find a FoundationThe first step is to establish a baseline with which to compare all other fixtures. What I like to use is the ARRI Photometrics App. It’s a fantastic tool that gives you photometric data of all of their light fixtures. Since most of us have worked with their tungsten fresnel fixtures, they can serve as an excellent baseline to center all other lights’ performance. Plus, you will constantly see LED manufacturers tout their lights as a “1,000w hot light equivalent.” Understanding how to compare these fixtures will help you analyze the validity of these claims.Fortunately, most LED fixtures have a photometric data sheet detailing their output at different distances. Using the ARRI Photometrics app helps you compare these distances between prospective LED fixtures and the baseline of tungsten fixtures. This way, you can decide if an LED fixture is closer to a 500w light or a 650w light. Beam AngleWhen evaluating these lights, it’s important that have similar beam angles to compare against. For example, a light at a 110-degree beam angle is not a fair comparison to a light at a 40-degree beam angle. The output will be vastly different. It’s important that you try to compare these lights under similar light quality conditions.Fortunately, the ARRI Photometrics app allows you to adjust the beam angle of fixtures to make a fair comparison between the lighting fixtures. While you may not be able to perfectly match beam angles, you’ll be able to get close. Most LED light manufacturers will provide beam angle information on their photometric data sheet.Image via LITEGEAR.LUX, Lumens, and FootcandlesWith no uniform system, you will find fixtures measured in LUX, lumens, and/or footcandles. Without a standardized system, you will constantly find yourself trying to figure out a way to compare lights. Fortunately, there are conversion calculators to help you in this process. A great one is featured at Suprabeam. You can use this calculator to get the accurate LUX of your light then compare that to a tungsten source.If the light fixture you’re looking at in measured in footcandles, Google has its own calculator that can help you with this conversion by simply searching “footcandles to lux calculator.”last_img read more

Boy killed by car in UP minister’s fleet; Yogi Adityanath seeks report

first_imgA five-year-old boy died after being hit allegedly by a car in the motorcade of Uttar Pradesh Minister Om Prakash Rajbhar near Colonelganj in Gonda district, following which Chief Minister Yogi Adityanath has sought a report from the State police chief.Mr. Rajbhar maintained he was not travelling with the cavalcade at the time of the incident even as opposition parties attacked the State government over the incident which comes ahead of civic polls in the State.One of the cars in Mr. Rajbhar’s cavalcade, while passing through the Colonelganj area on Saturday, had allegedly knocked down Shiva Goswami, who died on way to hospital last night, the police said.Eyewitnesses and family members of the boy alleged that no one in the convoy stopped to help the child. His father Vishwanath alleged that the minister sped away in one of the cars that was decorated with garlands.Mr. Rajbhar, however, claimed that he was 25 km away, in another car, when the incident occurred.The boy was playing by the side of a road when he was hit reportedly by one of the cars in the cavalcade. His mother and grandmother were near the spot.Following the incident, angry villagers placed the boy’s body on the road demanding action. Visuals of the boy’s father carrying the body were flashed repeatedly by TV channels.Stepping in, Mr. Adityanath directed the State police chief to submit a report and announced ₹5 lakh compensation to the next of kin of the deceased. He also directed the state DGP to initiate strict action against those responsible for the incident.Meanwhile, opposition parties targeted the Adityanath government and Mr. Rajbhar over the incident.Samajwadi Party leader Juhi Singh raised questions as to why nobody had the decency to stop and take care of the injured boy. “We demand his (Rajbhar’s) resignation. Otherwise, the chief minister should take action,” she said.Senior BSP leader Sudhindra Bhadoria termed the incident as shameful. “It reminds us of the days of landlords and feudal leaders who cared two hoots for the poor,” he said.Mr. Rajbhar, who heads the Suheldev Bharatiya Samaj Party, an ally of the ruling BJP in Uttar Pradesh, is the State divyangjan (diffently-abled) empowerment minister.He was in the news three weeks back when a video went viral on social media purportedly showing him warning that parents who fail to send their children to school would be locked up in police stations without food and water.In July, Mr. Rajbhar had threatened to sit on a dharna if a senior official in his home district was not removed.Recently, another State minister, Jai Kumar Singh Jaiki, was in the news when a farmer in Jalaun district claimed that his crop was allegedly trampled by the convoy of the minister.The farmer had alleged that last week nearly a dozen vehicles of the minister destroyed his crops in Orai.Jaiki, an MLA of BJP ally Apna Dal (Sonelal) from Jahanabad assembly constituency in Fatehpur district, however, said there were no standing crop on the field, as the sown mustard seeds were yet to germinate, but still ₹4,000 was paid to the farmer as damages.last_img read more