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Scientists Discover New Molecular Motor 'Clutch'

by Brian Thomas, M.S. *

How would a vehicle slow or stop on time or on target without some mechanism to disengage the engine from the drive train?

The vehicles that transport items within living cells face the same challenges as vehicles that transport people and goods. One molecular vehicle inside cells uses a protein motor called dynein. And researchers just discovered that a detachable clutch-like protein regulates its speed.¹

The dynein motor walks along microtubules, which are like train tracks inside cells. One end of the two-motor complex, which is a complex of 12 separately manufactured protein parts, has a long stem that acts like a trailer hitch attachable to a cargo bundle. At the other end, a short stalk connects to a pair of molecular leg-like appendages that alternately attach and detach as they literally walk down the length of a microtubule. This way, a cell transports products from one area to another. But what if there was no way to control how fast the dynein walked?

Without a clutch-like mechanism to regulate its speed, a cellular motor would carry its cargo too fast and too far, requiring constant cargo re-routing. Too much of such confusion would disrupt the cell's finely tuned and highly efficient inner workings. In short, failure to regulate the speed of protein motors could cause fatal intracellular traffic jams.

Fortunately, dynein motors are modulated by what researchers called a "clutch." A separate protein named "Lis1" attaches right where the appendages connect to the dynein's central motor. When the researchers added Lis1 to fully fueled dynein motors, they watched the dynein walking action slow down dramatically.² The study authors reasoned that Lis1disrupts the connection between dynein motors and their walking appendages, much like a clutch disengages an automobile engine from the transmission.

The specified complexity of Lis1, which is exactly the right size, shape, strength, and charge to fit perfectly into its notch on the dynein complex and fulfill its purpose, is one of thousands of essential details that the Creator provided for living cells.

References

1. Huang, J. et al. Lis1 Acts as a "Clutch" between the ATPase and Microtubule-Binding Domains of the Dynein Motor. Cell. 150 (5): 975-986.
   
2. To do this, the researchers chemically bonded molecular markers onto the dynein complexes, so that specialized equipment could visualize the motors in a laboratory setting.
   

* Mr. Thomas is Science Writer at the Institute for Creation Research.

Article posted on October 10, 2012.

[Avocado]

Grišo, kad Institut za Kreacionistička Istraživanja zaista izvrši neko istraživanje, otkrije nešto ili na bilo koji način proširi naše saznanje o univerzumu, obavezno nam javi!

A ovo... kako mali Tomica tumači naučna istraživanja koja su sproveli pravi naučnici... ne znam kome i zašto bi bilo interesantno...

[grigorije22]

Miles Babbage

Evolucione promene u spoljnom izgledu ili strukturi tela određene vrste su mnogo brži od promena u osnovnim nervnim sistemima (vid, sluh, itd.). Zbog ove činjenice, uporedna neuroanatomija (analiza promena u nervnom sistemu kroz evoluciju) se pokazala kao odličan pristup za razlučivanje evolucionih grananja u ranoj istoriji životinja, pogotovo insekata i drugih artropoda.

Nedavno je otkriven jako dobro očuvan fosil Kambrijskog artropoda Fuxianhuia protensa - toliko dobro očuvan da se struktura mozga mogla jasno razlučiti u ostacima. Analiza ove strukture pokazuje da je dotični artropod veoma blizak ranim insektima, i daje dodatne dokaze da su rani insekti bili sestrinska grupa današnjim rakovima i krabama (Malacostraca).

Ovaj nalaz takođe gura razvoj prvih relativno kompleksnih nervnih

sistema dublje u Ediakara period. Još jedan na sve većoj i većoj gomili dokaza koji pokazuju da se najkritičniji deo razvoja životinjskog carstva dogodio stotinama miliona godina pre Kambrijumske eksplozije.

Vest:

http://www.nature.com/news/picking-an-ancient-brain-1.11559

Ceo tekst studije, objavljen u Nature:

http://www.nature.com/nature/journal/v490/n7419/full/nature11495.html

Link na prethodnu odličnu neuroanatomsku studiju koja je jako čvrsto ustanovila vezu između Malacostraca i Hexapoda:

http://www.ncbi.nlm.nih.gov/pubmed?term=A+new+view+of+insect-crustacean+relationships+I.+Inferences+from+neural+cladistics+and+comparative+neuroanatomy

[grigorije22]

Miles Babbage Predvodnik ove studije je kolega sa mog odeljenja, Nik Strausfeld, koji je verovatno najveći svetski autoritet po pitanju neurologije i neuroevolucije artropoda. Nedavno je objavio fenomenalnu knjigu, sa fantastičnim fotografijama mozgova i nervne organizacije u stotinama različitih organizama:

http://www.amazon.com/Arthropod-Brains-Functional-Historical-Significance/dp/0674046331/ref=sr_1_1?ie=UTF8&qid=1350032554&sr=8-1&keywords=arthropod+brain

[montezuma]

[Млађони]

Veliki naucnik, josh veci hriscanin. A bogami i filozof da se nosi sa kompletnom sortom novog ateizma. Ima celo njegovo predavanje ovde i to bas to koje si "citirao".

[montezuma]

odgledao ...a i imam isti

isecak je postavljen,iz razoga sto direktno odgovara na "neredukujucu kompleksnost"....ovu duzu varijantu,tesko da ce vecina i odgledati....bar vecina kreacionista..

....na zalost...

[Млађони]

odgledao ...a i imam isti

isecak je postavljen,iz razoga sto direktno odgovara na "neredukujucu kompleksnost"....ovu duzu varijantu,tesko da ce vecina i odgledati....bar vecina kreacionista..

....na zalost...

Хехе, то си у праву тотално. Он је мени објаснио еволуцију више него сви остали заједно. Човек је сјајан предавач. Давао сам ја њега креационистима, ништа нисам постигао. Покачио сам силне његове клипове овде. Док сам још био атеисти, критиковали су ме јер је он написао књигу Finding darwins God, па је канда због те књиге неваљатан научник и глуп на том пољу али је овако ван тога ок!

Доприонео је разумевању науке и еволуције више од свих Давкисонових сведока заједно. Јер увек искључу религизоне тврдње из својих прадавања док они не могу да се суздрже да не аргументују то кроз атеизам.

[Млађони]

ЕВО ПРИМЕРА ЗАШТО ЈЕ ЕВОЛУЦИЈА ЛАЖ!

[GeniusAtWork]

ЕВО ПРИМЕРА ЗАШТО ЈЕ ЕВОЛУЦИЈА ЛАЖ!

Paz' ovo:

[grigorije22]

New Genes, New Brain

A bevy of genes known to be active during human fetal and infant development first appeared at the same time that the prefrontal cortex—the area of the brain associated with human intelligence and personality—took shape in primates, a new study publi

By Cristina Luiggi | October 19, 2011

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Wellcome Images, Mark Lythgoe & Chloe Hutton

A bevy of genes known to be active during human fetal and infant development first appeared at the same time that the prefrontal cortex—the area of the brain associated with human intelligence and personality—took shape in primates, a new study published yesterday (October 18) in PLoS Biology found. The timing suggests that the new genes may have been intimately tied to the evolution of the human brain.

“This is one of the first studies to look at the role of completely novel genes” in primate brain development, said Eric Vallender, a neurogeneticist at Harvard Medical School who was not involved in the study. Previous research has focused on relatively old genes (i.e. genes that are conserved across the animal kingdom and beyond), he said, with a particular focus given to identifying changes in their protein products as well as overall changes to gene regulation. The new study’s emphasis on the addition of new genes to the genetic repertoire could yield new insights into the genetic changes that led to the modern human brain, he added.

By comparing the order and orientation of genes along chromosomes across multiple mammalian species—spanning humans to mice—the researchers, led by University of Chicago evolutionary geneticist Manyuang Long, noticed several striking patterns.

First, genes that arose around the time that mammals first appeared (a little over 200 million years ago) tended to be active in the fetal human neocortex, a brain region largely unique to mammals that houses the prefrontal cortex. Furthermore, out of the 1,000 or so genes found only in primates, 251 were upregulated in the developing prefrontal cortex, which evolved right after the primate lineage diverged from the rest of the mammals around 60 to 80 million years ago. Finally, 54 of the 280 genes found to be unique to humans were also highly expressed in the developing prefrontal cortex, which grew considerably in humans after the human chimpanzee lineages broke off around 5 to 7 million years ago. (The human prefrontal cortex is six times larger than the chimpanzee’s.)

“We were very shocked that there were that many new genes that were upregulated in this part of the brain,” said Long, who added that he was also taken aback by synchronicity of the origin of the genes and the development of novel brain structures. It seems that around the same time that the neocortex and the prefrontal cortex arose, and then expanded in humans, a large collection of genes also popped up.

“You always have the correlation versus causation question,” Vallender cautioned. “But it’s very consistent that these genes were all arising at the same time as these new anatomical structures that we know are very important in cognition and behavior.”

The researchers also determined that the majority of these new genes underwent strong positive selection in humans, further supporting the hypothesis that the genes contributed to the evolution of important functions in the brain.

“All of this is circumstantial evidence that supports this more broad idea that these new genes have something interesting to say about primate-specific or human-specific brain function,” Vallender said.

Y.E. Zhang et al., “Accelerated recruitment of new brain development genes into the human genome,” PLoS Biology, doi:10.1371/journal.pbio.1001179, 2011.

Categories

http://www.the-scientist.com/?articles.view/articleNo/31302/title/New-Genes--New-Brain/

[grigorije22]

http://www.sciencedaily.com/releases/2012/11/121106201124.htm

[grigorije22]

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Australopithecus Was a Well-Adapted Tree Climber

by Jeffrey Tomkins, Ph.D. *

New research has confirmed that an extinct type of ape called Australopithecus afarensis, which includes the famous "Lucy" fossil, was a well-adapted tree climber. The research team conducted a detailed anatomical analysis of two complete shoulder blades of a fossil Australopithecince called "Selam," reported in the journal Science to be about 3.3 million years old.¹

A number of studies in zoological anatomy indicate that the various species of Australopithecus represent nothing more than different varieties of an extinct ape kind.² The fact that fully human remains have been found in rock layers as old as the ones containing Australopithecus fossils, further complicates the evolutionary story—a phenomema discussed at length by paleontologist Marvin Lubenow.²

Amazingly, it took 11 years for researchers to extract the fossil shoulder blades of Selam from the sandstone rock in which they were encased. Science study co-author Zeresenay Alemseged told LiveScience, "Because shoulder blades are paper-thin, they rarely fossilize, and when they do, they are almost always fragmentary." Alemseged also said that "finding both shoulder blades completely intact and attached to a skeleton of a known and pivotal species was like hitting the jackpot."³

Lucy, a fossil that was once widely promoted as a hypothetical human ancestor, had shoulder sockets that faced upward, a common feature of modern apes. The Selam fossil has the same type of sockets. This unique feature enables apes to dexterously climb and swing from tree branches. In contrast, humans have downward facing shoulder sockets at birth that gradually develop to face forward as they become adults. This position is also integral to the uniquely human walking gait.

Also in contrast to humans, ape shoulder morphology does not change during development. The authors wrote in Science, "Many of these traits change significantly throughout modern human ontogeny [development from an embryo], but remain stable in apes. Thus, the similarity of juvenile and adult fossil morphologies implies that A. afarensis development was apelike."¹

The idea that humans evolved from apes by leaving the trees to walk across the ground in a largely bipedal lifestyle, is a central evolutionary paradigm. The authors of the recent Science paper wrote, "Scapular traits throughout African ape development are associated with shifts in locomotor behavior. This affirms the functional relevance of those characteristics, and their presence in australopith fossils supports the hypothesis that their locomotor repertoire included a substantial amount of climbing."¹ If australopithecines were bipedal while on the ground, they did not walk like humans. And this recent analysis clearly shows that they were also well-adapted tree climbers with unique bone structures not found in humans.

No doubt this report was a setback for the evolutionary model of human origins that had postulated the idea that Australopithecines had largely transitioned to the ground from the trees. Indeed, another recent study evaluating fossilized food particles between Australopithecus teeth showed a diet of primarily tree-based food (tree leaves, fruits, wood, bark), compared to a small amount of grass.⁴

Even the highly subjective field of anthropology vindicates the scientifically accurate claim of the Bible—that man is created uniquely in the image of God.

References

1. Green, D. J. and Z. Alemseged. 2012. Australopithecus afarensis Scapular Ontogeny, Function, and the Role of Climbing in Human Evolution. Science. 338 (6106): 514-517.
   
2. Lubenow, M. 2004. Bones of Contention: A Creationist Assessment of Human Fossils. Grand Rapids, MI: Baker Books.
   
3. Choi, C. Early Human 'Lucy' Swung from the Trees. LiveScience. Posted on livescience.com October 25, 2012, accessed October 31, 2012.
   
4. Henry, A. G. et al. 2012. The diet of Australopithecus sediba. Nature. Posted on nature.com June 27, 2012, accessed October 31, 2012.
   

* Dr. Tomkins is Research Associate at the Institute for Creation Research and received his Ph.D. in Genetics from Clemson University.

Article posted on November 12, 2012.

[Анастасија]

A,evo i naše žive copy mashine.Tema je"Postavite pitanja vezana za evolucionu biologiju",a ne " Copy paste sve što ima bilo kakve veze sa evolucionom biologijom".Grigorije imao si opomenu za ovo što radiš.

[grigorije22]

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