Gypsy moth caterpillar takes bite out of forest carbon storage (Environmental Research Letters)

Forests are impor­tant car­bon diox­ide stor­age mech­a­nisms, but a vora­cious leaf-eating cater­pil­lar is cut­ting into the trees’ capac­ity to remove the green­house gas from the atmos­phere, accord­ing to new research by sci­en­tists at Prince­ton Uni­ver­sity, Rut­gers Uni­ver­sity and the United States For­est Service.

The gypsy moth cater­pil­lar, wide­spread in the north­east­ern United States, can wreak dev­as­ta­tion on forests as it devours the leaves of oak, pine, and other tree species. The new research found that this defo­li­a­tion has a sig­nif­i­cant detri­men­tal effect on the ecosystem’s capac­ity to act as a car­bon sink.

The study found that an oak-pine for­est in the New Jer­sey pinelands hit by the gypsy moth every five years would store about one-third less of the above-ground car­bon as an unharmed sim­i­lar for­est, accord­ing to David Med­vigy, assis­tant pro­fes­sor of geo­sciences at Prince­ton University.

The research was con­ducted by Med­vigy and Karina Schäfer, assis­tant pro­fes­sor of ecosys­tem ecol­ogy at Rut­gers Uni­ver­sity as well as researchers from the US For­est Ser­vice: Ken­neth Clark of the Silas Lit­tle Exper­i­men­tal For­est in New Jer­sey and Nicholas Skowron­ski of the North­ern Research Sta­tion in West Virginia.

The research was pub­lished in the jour­nal Envi­ron­men­tal Research Let­ters. (Read the open access arti­cle.) A news arti­cle about the study can be found here.

Cita­tion: Med­vigy, D., K. L. Clark, N. S. Skowron­skiand and K. V. R. Schäfer. 2012. Sim­u­lated impacts of insect defo­li­a­tion on for­est car­bon dynam­ics. Env­i­ron. Res. Lett. 7 045703

 

Study explores the boundaries of embryonic development (eLife)

If all of the DNA in a human cell was stretched out, it would be about two meters long. The nucleus of a human cell, on the other hand, has a diam­e­ter of just 6 microm­e­ters, more than 300,000 times smaller, so the DNA mol­e­cules that carry all the genetic infor­ma­tion in the cell need to be care­fully folded to fit inside the nucleus. Cells meet this chal­lenge by com­bin­ing their DNA mol­e­cules with pro­teins to form a com­pact and highly orga­nized struc­ture called chro­matin. Pack­ag­ing DNA into chro­matin also reduces dam­age to it.

But what hap­pens when the cell needs to express the genes car­ried by the DNA as pro­teins or other gene prod­ucts? The answer is that the com­pact struc­ture of chro­matin relaxes and opens up, which allows the DNA to be tran­scribed into mes­sen­ger RNA. Indeed, pack­ing DNA into chro­matin makes this process more reli­able, thus ensur­ing that the cell only pro­duces pro­teins and other gene prod­ucts when it needs them. How­ever, because cross-talk between neigh­bor­ing genes could poten­tially dis­rupt or change gene expres­sion pat­terns, cells evolved spe­cial ele­ments called bound­aries or insu­la­tors to stop this from hap­pen­ing. These bound­ary fac­tors divide the chro­mo­somes into sub­do­mains that can func­tion inde­pen­dently of each other.

Since the pro­tein fac­tors impli­cated in bound­ary func­tion seemed to be active in all tis­sues and cell types, it was assumed for many years that these bound­aries and the result­ing chro­matin domains were fixed. How­ever, a num­ber of recent stud­ies have shown that bound­ary activ­ity can be sub­ject to reg­u­la­tion, and thus chro­matin domains are dynamic struc­tures that can be defined and rede­fined dur­ing devel­op­ment to alter pat­terns of gene expression.

New research from the lab­o­ra­tory of Paul Schedl at Prince­ton Uni­ver­sity has uncov­ered a new fruit fly bound­ary fac­tor that, unlike pre­vi­ously char­ac­ter­ized fac­tors, is active only dur­ing a spe­cific stage of devel­op­ment. The Elba fac­tor is also unusual in that it is made of three dif­fer­ent pro­teins, known as Elba1, Elba2, and Elba3, and all three must be present for it to bind to DNA. The lead author of the study was Tsu­tomo Aoki of the Prince­ton Uni­ver­sity Depart­ment of Mol­e­c­u­lar Biol­ogy. Aoki worked with co-authors Ali Sarkeshik and John Yates from the Scripps Research Insti­tute in La Jolla, CA.

While Elba2 is present dur­ing most stages of devel­op­ment, the other two Elba pro­teins are only present dur­ing early embry­onic devel­op­ment, so the bound­ary fac­tor is only active in early embryos. In addi­tion to reveal­ing a new mech­a­nism for con­trol­ling bound­ary activ­ity as an organ­ism devel­ops, the stud­ies of Aoki et al. pro­vide fur­ther evi­dence that chro­matin domains can be dynamic.

Aoki, Tsu­tomu, Ali Sarkeshik, John Yang, and Paul Schedl. Elba, a novel devel­op­men­tally reg­u­lated chro­matin bound­ary fac­tor is a hetero-tripartite DNA bind­ing com­plex. eLife 2012;1:e00171

Read the article.

Arti­cle sum­mary pro­vided by eLife.

Truths we must tell ourselves to manage climate change (Vanderbilt Law Review)

Cli­mate change is unwel­come news, and the best and worst out­comes con­sis­tent with cur­rent sci­ence are very dif­fer­ent, says Prince­ton University’s Robert Socolow, pro­fes­sor of mechan­i­cal and aero­space engi­neer­ing, in a new review arti­cle pub­lished in the Van­der­bilt Law Review.  There are novel ways the envi­ron­men­tal com­mu­nity, in its role as mes­sen­ger, could tell the story about cli­mate change using greater empa­thy and can­dor.  This essay, which was deliv­ered as a keynote address at a sym­po­sium held Feb. 24, 2012 at the Van­der­bilt Law School, addresses new ways to freshen the conversation.

The era of con­scious­ness of cli­mate change began in 1958 when Charles David Keel­ing began the first accu­rate mea­sure­ments of car­bon diox­ide in the atmos­phere. The sea­sonal oscil­la­tions were unex­pected and the annual aver­age has become a new index (the Keel­ing Curve) of global human impact.

Fifty-four years later, cli­mate change nego­ti­a­tions in the United States and inter­na­tion­ally are in paral­y­sis. The cur­rent impasse has lit­tle social value and a “restart” but­ton is needed. Such a but­ton will be found when those already con­cerned about cli­mate change become bet­ter at telling truths first to them­selves and then to the gen­eral pub­lic. One can begin with acknowl­edge­ments that 1) cli­mate change is unwel­come news, a chal­lenge we would rather not have; and 2) the best and worst out­comes con­sis­tent with today’s cli­mate change sci­ence are very dif­fer­ent. More­over, every nom­i­nal energy “solu­tion” to cli­mate change has a dark side and the solution’s pro­po­nents are not the ones to be counted upon to iden­tify what can go wrong.

Accord­ingly, cli­mate change is a prob­lem of risk man­age­ment requir­ing bal­anc­ing the risks of dis­rup­tion from cli­mate change and the risks of dis­rup­tion from mit­i­ga­tion and adap­ta­tion. Both pub­lic and pri­vate insti­tu­tions need to find ways to over­come their reluc­tance to ver­ify whether intended car­bon reduc­tion goals have actu­ally occurred, so that progress can be accu­rately mon­i­tored and learn­ing can occur. Indi­vid­u­als can be helped to become more aware of how their every-day activ­i­ties cre­ate their car­bon foot­print. Pop­u­la­tion must reen­ter the conversation.

There are grounds for opti­mism. Sci­ence has dis­cov­ered threats fairly early. Many help­ful tech­nolo­gies are being devel­oped and deployed. And, our moral com­pass is in work­ing order, insist­ing that we care both for those alive today and for the col­lec­tive future of our species.

Cita­tion: Robert H. Socolow, “Truths We Must Tell Our­selves to Man­age Cli­mate Change.” Van­der­bilt Law Review, Vol. 65, Num­ber 6, pp. 1455–1478.

Read the full arti­cle: http://www.vanderbiltlawreview.org/content/articles/2012/11/Socolow_-65_Vand_L_Rev_1455.pdf

Transition from individual to group behavior in bacteria (Journal of Bacteriology)

Bac­te­ria use a chem­i­cal com­mu­ni­ca­tion process called quo­rum sens­ing to con­trol tran­si­tions between indi­vid­ual and group behav­iors. In the bac­te­ria known as Vib­rio har­veyi, two mas­ter “switches” of gene reg­u­la­tion, or tran­scrip­tion fac­tors, coor­di­nate the quorum-sensing response.The researchers found that one of the reg­u­la­tors, LuxR, acts as a sort of mas­ter switch that reg­u­lates quorum-sensing, while the other reg­u­la­tor, AphA, does the fine-tuning. Together the two reg­u­la­tors gen­er­ate a pre­cise pat­tern of activ­ity as bac­te­ria tran­si­tion from act­ing as indi­vid­u­als to act­ing as a group.

Julia C. van Kessel, Steven T. Ruther­ford, Yi Shao, Alan F. Utria, and Bon­nie L. Bassler. The mas­ter reg­u­la­tors AphA and LuxR con­trol the Vib­rio har­veyi quorum-sensing reg­u­lon: analy­sis of their indi­vid­ual and com­bined effects
J. Bac­te­riol. pub­lished 30 Novem­ber 2012, 10.1128/JB.01998–12

Read the abstract.

New approach can rapidly estimate damage from earthquakes (Bulletin of the Seismological Society of America)

A new approach that can rapidly esti­mate dam­age to tall build­ings fol­low­ing a large earth­quake has been devel­oped by researchers. The approach involves cre­at­ing a data­base of build­ing responses to typ­i­cal earthquake-related ground motions. After an earth­quake, an analy­sis of the ground motions can indi­cate what type of dam­age is likely to have occurred to nearby build­ings. The results could be use­ful for emer­gency response deci­sion making.

Swami­nathan Krish­nan, Emanuele Casarotti, Jim Goltz, Chen Ji, Dim­itri Komatitsch, Ram­ses Mourhatch, Matthew Muto, John H. Shaw, Carl Tape, and Jeroen Tromp. Rapid Esti­ma­tion of Dam­age to Tall Build­ings Using Near Real‐Time Earth­quake and Archived Struc­tural Sim­u­la­tions. Bul­letin of the Seis­mo­log­i­cal Soci­ety of Amer­ica. 2012; 102:2646–2666.

Read the abstract.

Effects of climate and land management on the type and location of vegetation in wetlands (PNAS)

Peri­odic floods are a nor­mal occur­rence in wet­lands. To find out how these floods impact niches of dif­fer­ent plant species in wet­lands, Prince­ton researchers stud­ied plant species in Ever­glades National Park (ENP) in Florida. They found that the sizes of the clus­ters of each species fol­low a power law prob­a­bil­ity dis­tri­b­u­tion and that such clus­ters have well-defined frac­tal char­ac­ter­is­tics. They mod­eled the effect that peri­odic flood­ing and neigh­bor­ing veg­e­ta­tion have on plant clus­ters. They found that cli­mate and land man­age­ment have a pre­dictable impact on the type of veg­e­ta­tion and its spa­tial orga­ni­za­tion in wetlands. The find­ings are highly rel­e­vant for the man­age­ment of wet­land ecosystems.

R Foti, M Del Jesus, A Rinaldo, and I Rodriguez-Iturbe. Hydrope­riod regime con­trols the orga­ni­za­tion of plant species in wet­lands.
PNAS, Novem­ber 13, 2012

Read the abstract

The role of breast structure in tumor development (PNAS)

Why do some breast tumors grow aggres­sively while oth­ers grow slowly? In this study, researchers found that the stiff­ness of the cells in the area around an emerg­ing tumor influ­ences its abil­ity to grow and invade the breast. Using a 3-D fab­ri­ca­tion process, the researchers cre­ated arti­fi­cial breast ducts con­tain­ing nor­mal breast cells and a sin­gle tumor cell. They found that regions char­ac­ter­ized by stiff­ness among the nor­mal cells were more likely to give rise to tumors that are aggres­sive and inva­sive, while regions that were less stiff gave rise to tumors that are less invasive.

Eline Boghaert, Jason P. Gleghorn, Kan­gAe Lee, Nikolce Gjorevski, Derek C. Radisky, and Celeste M. Nel­son. Host epithe­lial geom­e­try reg­u­lates breast can­cer
cell inva­sive­ness. Pub­lished online before print Novem­ber 12, 2012, doi: 10.1073/pnas.1118872109 PNAS Novem­ber 12, 2012

Read the abstract.