to@ ANrn\ :,Ar( I\LVVJAI\U^,r,^/. ViLtiJ fossil evolutionar.v s1'nthesis by studying DNA, stiil look like nothing more tnan.a Palaeomolecular !t"lggJ too early tr'1 nlorious dream. Hou ever, it is far io nitl"up. and it nright just be possible.that buneo fossilized Raising the dead and ;SA ;;t ,ur" i' ed in some ^"materlal. point: DNA can easily be from Alec J. JeffreYs One final iare outiii.a ito* animals that have died' and Not press) and my oun (unpublished) survive for the quagga as dead as a dodo? of DNA [".. J.i.a it is stable and should Is ;;;;; ih;, suLstanrialquantities It is there- i"tit.'rtl""iior indeed might be the dodo' .i"*i.t rvithout degradation' Russell can be recor ered fronr Prcserveo or museums should ii";;';;;;rkable findinss of almost fore viral thar zoos co-workers rn"*rnotft tissue' Unfortunately' to store DNA from as iii-".rti, Allan wilson and microbial con- siart sysrematically of this issue are it comes from recent as possible' and certainly ;;;-ili on Page 282 "ii"i probably introduced after .uny'rp..i.t go Because even though the iu-i"urion, any that face exrinction' Friedrich ;'";;t;;,o uv;. Elephant-like DNA sequences froni chimaera of horse and excavation. *ho discovered nucleic acid in ouunnu. u curious at vanishingli' low levels (less tnli.r.t't.i, ,.bii b..urn. extinct just over a century "."1*i.", ;;;.-;"t. of its DNA has survived in a ;;;.;; ip.cimen in a state suitable for TE "';;;moiecular cloning' start, Higuchi et al' managed to & irofut. putiiuily degraded DNA from dried ro show that at least ;;il.'tissue-and a i-oml"of it is of quagga origin' rather.than .oniu*inun,, by virtue of its hybridization *"iirr-oNe fiom the closely related zebra' ftio.. i*pott^ntly' it was possible to-obtain lion., oi specific mitochondrial DNA se- these sequences euences. Comparison of ;;th-1h;t. of zebra mitochondrial DNA rri"ia.a-ift. final proof that they are of Iuttt. origin. Not only are the. trvo ti1 tr** t.qJ.n..t as closelv matched as is ;tdil most expectea for congeneric animals but oi'uff oi the differences that do exist at fr; it"ittfv synonymous base transitions not due itriiJ *0"" positions) are clearly . 3.t"*. ,.:t" i"'""tt*"t,.rn changes in DNA that have 4ry e; E& l.in-tuUr.quently misrepaired during ;b"i[, and so they must reflect the evolu- the quagga' Clearly' the Zoo troln I iion-uti'ttitroty of A quagga mare erhibited at London phylogenetic quagga in Am i,il,i:,i ?li'll:,t::i:!i:l'',:3:,?:i*'"i:il; nr.ui- oo".t of molecular ft"iot.-*. death of the last captir e to living animals' Die histochem- inJntit, so far restricted a and are 1868 (see Vogel' F.C.W than I part in 10 of the total DNA) von .an no*Ue Utought to bear on at leasl some this DNA ischei und physiologischen Arbeiten ;;;;;iy degraded. Cloning could h^ave extinct sPecies. task, and any i. *rirtrnrr, LeiPzig, i897), was would indeed be a mammoth if he The ciioice of mitochondrial DNA would su".J rfigu.iti et'al. a lot of trouble there are ,.ouanaa information recovered -the and store wise in view of its abundance: bl post- tlua f'tua foresight to make However' orob.bly be seriousll distorted i l many mitochondria in each cell' nothing fresh quagga'nuclein'' might ilortem-modification. \\'e knori ,o .*'ropof ut. from Higuchi et a/' it ' to about the chemistry of DNA degradation even be'possible to extend such studies gm over geological time Periods' copy genes of the nucleus' Thus 3 'l' !;, 3,'f: ii I f:,'' {' iinele"pt.*it=J Ariv lopes that moiccular.biolog-v and : ;,, {;,,'; { i?i:,, ; i i,,' tissue should yield sufficienr 7RH. LI.K. " oi puiu.ontoiogv can be fused into a grand DNA to produce a library ol up to J x ru perhaps 100 base clones, each containing accelerators ouit.'of quagga DNA and together Particle iovering most of the genome' The obvious next question is whether energies their for high ottrei museum specimens witl yield up New concepts that rnot..utu, s.creis. One can only hope J.D. Lawson rnur.o. curators will be reasonably sym- from paihetic to hordes of molecular biologists ago they met again, this time in development of particle ac- u,eeks dismantle their. cherished exhibits' Specraculen to examine in more depth some i"g.t,o has sustained the progress. ot Frascati--, could benefit too DNA celerators discussed at Oxford' an'tirropotogists - particle physics during the last of the ideas o-i Uog people and Egyptian .i.*.nruty beam' concept' llrst t.qu.n..t Although current proJects' The 'colliding would no doubt be fascinating' half century. t\^enty )ears ago, becomes *Jt*i.t to be fu nded will ensure the demonstrated the latter might prove.too unJ ori'.tt :1., ' when the ratio. of though cloning ph5'sics unril the end of ;;;;iJ;tly effecrive v, a task for the superstitious i."*i.rt particle energy 1o rest energy' be- n.iu."-tu.ting "ip.rricle serious concern about iotal in.i.ntrtv, there is rhe total energY of genetic engineer. beyond then' \\re need ;;;;Ji";c;. ntmoir two in a museum ts one wtrai *ilf hupp.n ihen available for particle creat- A centurY or or some radically new i"* is years in a Siberian perma- some new concepts 'in'!na", .^.i,ution, whereas if one of rh.e thing; 40,000 to contillue past trends.' Two fate of the Magadan i*.it"ofogv is initially stationary iil'"t*! t' frosi'Uog the energv and accelerator particles - another' Nevertheless' v.utt ugo high rnr**oift is consider 'The , ll'.h I l( d lor Patlrclc \c"clcrationlovcr) - nreiin oxford to t*,n. .,'.,n j"'.''' ()'rob!'r 1984' grou p (Fed. Proc' 43, I 557 ; I 984)' orrvti.iri, I :'\(r'r(Inhcr' I Wllron't Energies'' A few -lr i ,ii \'":'1, ' ; in the 6tt"lf.ng. of Ultra-High lA. CooOilun s (A c ta Zool' Fe nn ica' a.ry

::y.T- .nr':; NATURE VOL.3l2 15 NOVE\jBER 1984 NTWSANDVIIWS value nerv and detecting a beat rvave, and there are carries a\\'ay mosl of the energy as kinetic but not incredible ' Any. fields to hopes that a experiment rvill be approved in energy and only VTymoc: is accessible. approach must either enable such than at the United Kingdom. There is plenty of the large values of y now available, it seems be obtained more economically scope for further theory and simulations, that future high energy accelerators must present or promise higher fields. on how to use the concept lo in the colliding beam mode. The Progress was rePorted on two other and for ideas operate the'wake accelerator. The stringent large electron-positron (LEP) storage linear accelerator concepts, build an Voss and T' requirements for efficiency and good beam rings now under construction at CERN field' accelerator of G. (DESY) and the 'tu'o beam' quality make this task difficult, but there near Geneva represent the most advanced Weiland Sessler (Lawrence Berkeley *'as plenty of enthusiasm for further enterprise of this type. The tunnel to house concept of A. the former, converging exploratory work. the rings is 27 km in length, and the planned Laborator5'). In a ring of electrons moving An idea much discussed in earlier energy is ultimately expected to exceed 10O rvake fields from structure produce meetings is the acceleration of particles Gev per beam (i' = 2x105). An even larger through a suitable which can then be grating carrying an evanescent machine, for protons of energy 10-20 TeV intense fields on the axis over a Experiments to test surface rvave, excited by an incident laser per beam, is being considered in the United used for acceleration. way DESY in beam. At its simplest this rvould not be ef- States. These machines are near the limits the idea are under at with different ficient, but basic experimental studies on of acceptable cost and sheer physical size. Hamburg, FRG and, a Japan' In the two coupling of *'aves and grating In the case of electrons, the energy loss by geometry, at Osaka in the power provided not by structures are being planned in Ottawa. A synchrotron radiation in the magnet fields beam accelerator is but from a single low development due to R. Palmer also represents a technical iimit; further an array of klystrons, parallel to (Brookhaven) is to replace the grating by progress will require 'linear colliders', in energy electron beam that runs passes tiny spheres spaced about three which two linear accelerators fire very the accelerator structure. This two rows of magnetic undulators, to a u'avelength. The idea is to squirt these dense bunches of electrons at one another. alternately through required microwave from an ink jet printer and, rvhen they have An experiment to test the principle of this which generate the laser action, and arrived at the correct position, to subiect method, and to learn how to generate and power by free electron that restore the beam them sequentially to a travelling pulse of control the very dense bunches that will be induction sections at Livermore has laser light. This should render the spheres needed, is underway at the Stanford Linear energy. An experiment at 34 GHz conducting and, on the short time scale Accelerator Center (SLAC). produced i00 MW of radiation these ideas required, capable of sustaining the enor- Two questions were asked at Frascati: with 5 per cent efficiency. Both potential required for rapid acceleration first, what is the minimum performance aim at high fields, but their still mous fields to high energies of a beam of injected specification for an 'interesting' acceler- needs to be established. previous meeting, the 'beat- parricles. The spheres act as a sort of ator beyond the range of established tech- As at the Tajima (University of receiving antenna that transfers energy niques; second, what approaches might wave' concept of T. Dawson (University of from the laser light to the particles. ultimately be capable of achieving the nec- Texas) and J. Angeles), excited con- Everyone u'i11 have their orvn views essary specification? Appropriately, Carlo California, Los promises the most about how credible these ne$ concepts Rubbia (CERN) opened the discussion by siderable interest. It accelerating fields, generated really are, but there u'as considerable attempting to define not only what energies spectacular two laser beams in a enthusiasm at the meeting and no doubt are required, but what minimum rate of by beating together laser future is going to bring increasing worthwhile events would need to be plasma, where the difference of the that the equal to the plasma frequ- activity in this fascinating and potentially achieved. frequencies is the field. The ratio of event rate to cross sectlon ls ency. Despite tantalizing figures for important physics of the known as the luminosity, which for pairs of field gradient, the detailed it is too early to bunches each containing N particles coi- process is still not clear and J. D. Lav'son is ot lhe Science dnd liding head-on is given by the expression see how one might design such an Engineering Research Council Rutherford - Didcot, L : N2f,zA, where f is the repetition rate accelerator. In the United States, Aipteton Laboratory. Chilton, planned setting up Ox.iordshire OXl l )QX' UK. and A the bunch area. For linear colliders experiments are to try the bunches are used once only, so that the beam power is P : NfYmoc2. L is deter- 100 years ago the minimum acceptable event mined by THE NEW VOLCANIC ISLAND OFF rare for experimentation, and P by the ICELAND the porver supplied to the accelerator times Ar the end of July this year the light-keeper at iffici.ncy of acceleration of the beam' Cape Reykjanes, the south-west point of Since cross sections for interesting events Iceiand, reported rhat a volcanic island had risen involving point-like particles decrease with in the sea a ferv miles off the cape. Reykjanes has volcanic activit)', energy. both L and P must increase, and long been noted as a centre of time to time islands have arisen and Rubbia made a plea for L = lgrn cm-2 sec'r frot "ndsubmarine eruptions have occurred in its 5 + 5 TeVelectronmachine. Inserting fora neighbourhood. In the year of the great values for P and technically- affordable Skapt6rfell eruption, which proved so fatal to credible values for f and N in the above Iceiand,1783, an island appeared off formuiae yields sub-micron diameter Reykjanes, only to disappear again after a very bunches with an optical beam quality that brief existence' Only a year or two ago an the is better than has so far been achieved. This eruption of considerable violence occured in challenge was quantified by L. Hand sea, not far from the spot where the new island of The island as it now appears' (Cornell University) and J. Rees (SLAC)' appeared. Columns of stream and clouds duit, mingled wirh occasional glowing masses of who indicated the need for high efficiency damaged the lamps' The fused roci, were seen to rise out of the sea, and the lighthouse and and optical precision in the beams. High altered: a large large quanrities of pumice were thrown up and island-'s shape was considerably also essential, and it was this the south side had slipped fields are drifted ashore on the neighbouring coast' part of the ilop. on at the meeting' rvhere now lies, forming aspect that was emphasized When first seen, on July 29, its shape was that iown into the sea, it the main Recent experiments at SLAC suggest that with a slight depression on t$,o little hillocks close to the foot of of a truncated cone face nearly extrapolation to above 100 MeV/metre the top, and a considerable hollow half way mass, and leaving a steep 5 perpendicular tos'ards the bottom. shouLd be possible by development of con- down ihe slope on the north side. On August ventional techniques; this implies not more and 6 a series of violent earthquake shocks split the masonry of From Nalure 31, 37, l3 November 1884' than 50 kM for a 5 TeV machine, a large occurred. u hich shook and

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