Catálogo de publicaciones - revistas

<jats:title>Telling Hexanes Apart</jats:title> <jats:p> The efficiency of modern internal combustion engines depends on the relative reactivity of the hydrocarbons that comprise the fuel. In particular, branched hydrocarbons are less likely than their linear counterparts to react prematurely—a property reflected in the fuel mixture's octane number. <jats:bold> Herm <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="960" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234071">960</jats:related-article> ) report a metal organic framework material with triangular pore channels that discriminate among the differently shaped isomers of hexane more finely than the commercial standard. </jats:p>

<jats:title>The Master Switch for Itch?</jats:title> <jats:p> Recently, gastrin-releasing peptide (GRP) has been implicated as the primary neurotransmitter between itch-sensitive nerve fibers and downstream neurons in the spinal cord. However, <jats:bold>Mishra and Hoon</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="968" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1233765">968</jats:related-article> ) challenge this view, provide evidence that natriuretic polypeptide b (Nppb) is the central itch neurotransmitter, and suggest that GRP is released by second-order neurons in the spinal dorsal horn that express the Nppb receptor and are excited by Nppb. </jats:p>

<jats:title>Sugar Aversion</jats:title> <jats:p> Several populations of the German cockroach have become averse to the glucose used as bait in toxic traps, which has severely reduced the traps' effectiveness. <jats:bold> Wada-Katsumata <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="972" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234854">972</jats:related-article> ) show that this aversion is a result of changes in the peripheral gustatory system, whereby glucose, as well as “sweet” receptors, stimulated an aversive bitter compound receptor. </jats:p>

<jats:title>Spleen Knockout Explained</jats:title> <jats:p> Isolated congenital asplenia (ICA) is a rare disorder where patients are born without a spleen and are at increased risk of bacterial infection but have no other developmental abnormalities. Through sequence analysis of familial and sporadic cases, <jats:bold> Bolze <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="976" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234864">976</jats:related-article> , published online 11 April) found that ICA patients carry mutations in the gene encoding ribosomal protein SA and as a result express about half the normal amount of this protein. The mechanism by which reduced expression of a housekeeping protein causes an organ-specific defect remains unclear. </jats:p>

<jats:title>Folding Too Slow, Off You Go</jats:title> <jats:p> One of the major questions of chaperone-assisted protein-folding pathways is how substrates that fail to fold avoid futile folding cycles. <jats:bold> Xu <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="978" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1234055">978</jats:related-article> ; see the Perspective by <jats:bold> <jats:related-article issue="6135" page="" related-article-type="in-this-issue" vol="340">Kleizen and Braakman</jats:related-article> </jats:bold> ) developed a model to examine a folding-competent protein that nevertheless fails to fold within the endoplasmic reticulum. Under these circumstances, the unfolded protein was subject to an unusual glycosylation, O-mannosylation, which appeared to terminate folding of the unfinished molecules. Eliminating O-mannosylation allowed the protein to fold completely. </jats:p>

<jats:title>Keeping Coordinated</jats:title> <jats:p> Before a cell divides, it must replicate its genome so that both daughter cells receive a copy of the parental DNA. Replication must be tightly regulated to ensure that the genome is replicated only once, because over- or underreplication could result in aberrations that cause genome instability. Thus, replication must be coordinated with other events in the cell, such as the cell cycle and DNA damage response systems. <jats:bold> Boos <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="981" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1237448">981</jats:related-article> ) analyzed the function of the Treslin/TICRR protein, an essential DNA replication factor regulated by cyclin-dependent kinases and the DNA damage checkpoint. Treslin interacts with the Mdm Two Binding Protein (MTBP), implicated in oncogenesis. MTBP and Treslin appear to integrate signals from the cell cycle and the DNA damage–response pathway, thereby controlling the initiation of DNA replication. </jats:p>

<jats:title>Malaria Cloak and Dagger</jats:title> <jats:p> Mosquitoes have a complex immune system capable of effective antiparasite responses; however, malaria transmission is still highly efficient. <jats:bold> Molina-Cruz <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="984" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1235264">984</jats:related-article> , published online 9 May; see the Perspective by <jats:related-article issue="6135" page="" related-article-type="in-this-issue" vol="340"> <jats:bold>Philip and Waters</jats:bold> </jats:related-article> ) show that <jats:italic>Plasmodium falciparum</jats:italic> has a gene product, <jats:italic>Pfs47</jats:italic> , that makes the parasite's ookinetes “invisible” to the mosquito immune system. Disruption of this mechanism could potentially be used to block malaria transmission. </jats:p>

<jats:title>Going Off-Target</jats:title> <jats:p> Sulfamethoxazole is a widely used sulfa-drug often used at high doses in the treatment of Pneumocytis pneumonia (PCP) in immunocompromised individuals. <jats:bold> Haruki <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="987" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1232972">987</jats:related-article> ) show that sulfamethoxazole and certain other sulfa drugs inhibit the enzyme septiapterin reductase that catalyzes the final step in the biosynthesis of tetrahydrobiopterin (BH4). BH4 is a cofactor in the biosynthesis of neurotransmitters such as serotonin and dopamine. In cell culture, sulfamethoxazole lowered neurotransmitter levels through depletion of BH4, which may explain central nervous system side effects associated with PCP treatment. </jats:p>

<jats:title>Sensing Tension</jats:title> <jats:p> Many cellular processes are regulated by mechanical signals. Single-molecule force spectroscopy has been used to probe molecular unfolding or unbinding; however, measuring the single-molecule forces required to activate signaling remains a challenge. <jats:bold>Wang and Ha</jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6135" page="991" related-article-type="in-this-issue" vol="340" xlink:href="10.1126/science.1231041">991</jats:related-article> ) describe a “Tension Gauge Tether” approach to measure the force applied on a single receptor ligand bond. By using tethers with a range of tension tolerances and monitoring activation, the force required to activate signaling could be measured. </jats:p>