OUARTERLYMAGAIINE OFTHE SOCIETY FORGENERAL [/ICROBIOLOGY VOLUME 27NOVEMBER 2OOO Thenature of TSEs Viroids- thesmallest living fossils? Virusesrule the waves Astrobiology Transposableelements I Nan o bacte ria L Unculturables and bacterial diversity q ', i i l ffiI;ffiffi'ffi:ffiffi,% l SGM Headquarters MarlboroughHouse, Articles Basingstoke Road, Spencers Wood,Reading RG7 1AG Thetwilight zones of microbiologyJoh n Postgate 162 Tel 01189881800 Thenature of TSEsChris Bostock 164 FaxOl 189885656 emailmtoday@sgm,ac,u k Viroidsand othersub-viral pathogens of plants: SGMWebsite thesmallest living fossils? http:,/,/www.sg m.ac.u k NicolaSpence & DezBarbara 168 Editor Virusesrule - DrlVerielJones thewaves thesmallest and mosr abundantmembers of marineecosystems Editorial Board ProfessorDave Kelly GunnarBratbak&MikalHeldal 171 DrLynne lVacaskie Insearch of asecond evolutionaryexperiment ManagingEditor DonCowan & MonbaGrady 174 JanetHurst MobilegenesNrcholasWest&ChristophTang Production Editor 178 lanAtherton Nanobacteria:goldmine or minefield of intellectual Assistant Editor and enguiryAllan Hamrlton 182 Book Review Manager 'unculturable JaniceMeekings Bacterialdiversity and s'John Fry 1Bo Contributions Theseare always welcome and shouldbe addressed tothe Editor (c/oSG M Headquarters). Regular Features CopyDates SocietyNews I acl.letoc fnr'- roe--- oinl r"- n{ cr-rPY JulyCouncil Meeting 190 at l\,4arlboroughHouse are: NewMembers of Counciland Group Committees 190 General Copy NewHonoraryMembers February2O01issue 20 November 191 NewGroup Conveners 191 May2001issue2April Above: Microbiology- Allegedlythesmallest Advertisements (CRC) Grants 192 tho tr,vilinht znnoc replicatingmolecules February200 1 issue2 January Newsof Members 1 Couftesy Carltn lverson/ known,viroids cause 93 N/ay2001issue3OApril NewMembers of Council (biographies) t gS SciencePhoto Library devastationincrops, as Advertisements SGM membershipsubscriptions 2001 194 Allenquiries should be sentto: describedby Nicola Spence JulieLauder, NWH SalesLtd, andDez Barbara(pp. 168- GoingPublic '1 194 TheArcade Chambers, Yol.27rPast4, 7O).Bacteria have viruses TA^ n "^^..1^ At..t^"-t-^+ Gradline 196 | | tg nt uaug! ntugtJl tuLr November2OOO too.Gunnar Bratbak and Hampshire,GUl1 l EE MikalHeldal considerthe Meetings 198 re|01252 357000 Inth is issue tryto answer Fax01 252 3570C1 We roleof bacteriophagesin PublicAffairs - newsectron ! 200 [email protected] questionszuch as how small aquaticm icrobial ecology lSthesmallest unit of life?ls Subscriptions 2OO1 onpp. 1 71-173. Hotoffthe Press 202 NON_N/EMBERS itreally alive? ls it reallya Movingupthescale, MicroShorts 206 M icrobiology TodayS5O O0 micro-organism? t (us$85,00) AllanHamilton looks at Inhis overview of Reviews 208 N/EN/BERS nanobacteria(pp. 1 82-184) All members receiveMicrobiology thetwilightzones of andJohn Fry questions SGMStaff 211 (p, Today.lnaddition they maytake microbiology 162) just olo howunculturable the AddressBook zlz anyof the Soc ety'sjou rnals, John Postgatewonders if microbeson ly identified Ordinary Member whatnow may seem to be bymolecular biology Diary 219 MembershipSubscription (inc. biologicalcuriosities will techniquesreally are CommentDaveRoberts Mi c r o b i o I o g y To d ay) 9 40.OO leadto dramaticnew 220 (us$70oo) (pp.186-1BB), Microbiology9.70.00(US$ 1 35.00) scientificadvances, (us$ Andfinally,Don Cowan and JGvS70.00 135.00) Whatcauses TSEs? rJsEM 97O.OO (US$ 1 35 00) MonicaG rady consider the Other ltems Scientistsdisag ree but possibilities of extra- Studentor RetiredMember LettertoEdiior MembershipSubscription (inc. mostfavourtheprion terrestriallife (pp. 174-177), 180 Mi cr o b i o I o g y To d ay) 920.00 proteintheory discussed UKFCClogocompetition 184 (us$33oo) byChris Bostock on Othertopicscovered - Microbiol ogy t,35.00 (US$65.00) pp,1 64-1 66. includethe SG M's new Photo2000 Photographiccompeiition 185 JGyS35.00(US$65.00) initiativeto raisethe prof ile International Development Fund usEMsTo.o0(us$ 135.00) Mobilegenetic elements are of microbiology(p,200), report Culturecollection managemeni in UndergraduateMember foundwidely in nature. On culturecollections inCuba Cuba MembershipSubscription (inc. pp.1 78- 1BO Nicholas West (p. FranklinSotolongo 189 MicrobiologyToday) I 1O.O0 189) anda Lancashire andChristoph Tang look at attemptto interest chrld ren Velvetevolulion Aidan Parte Theviews expressed by 205 therole of prokaryoiic inmicrobiology (p,1 9S). contributorsare not necessarily transposonsin adaptive JointASM/SGMmeeting 206 thoseof the Sor.ie-v:nor can the Thesearticles appear in claimsof adverlisersbe evolutionand their potential SymposiumVolume reviews 207 +^" ^,,^t^i+^+i^^ h,, guaranteed. rur u yrurLaLrurruy additionto allthe regular mirrnhinlnnictc featr rrps and rcnnrfs nf O 2000 TheSociety for General Qnnioilr antiriiiioc Microbiology;ISSN: 1 464-0570 Design : Graph i cs Inte rnatio nal ,rrlT j Speciallssue of Microbiology Entitled Pseudomonas:Biology and Diversity andpublished in October 2000,this special issue provides a focusforthe vigorousactivity of the Pseudomonasresearch community associated with the completionof two genome-sequencingprojects. lt bringstogether some of the latest,original researchby leading international groups in the field, in oneunique source. Areasof researchin this extensive collection include: I Biotechnology I Evolutionand Systematics I MolecularBiology I Pathogenicity(plants and animals) t Physiology f Genomics A linkto a completelist of papersand abstracts, and orderforms can be found on our websiteat http://www.sgm.ac.uk/pseudo.htm lf youwould liketo keepup-to-date with the widelydiverse field of Pseudomonasbiology, simply order your copy using the orderform below. Pseudomonas:Biology and Diversitywillbecome an invaluableaddition to yourcollection Speciallssue Order Form Pleasesend me copiesof Pseudomonas:Biology and Diversity SGMmember price f25 Non-memberprice f 50 Paymentwill be acceptedonly in f sterling I I enclosea cheque(made payable to SocietyforGeneral Microbiology) for f E lwishto payby credit card. I authorizeyou to debitmy CreditCard Accountto the valueof f Pleasenotethatallcreditcardtransactionswillbe in f sterlingand no cardsotherthan thoseindicated can be accepted tr Access n Eurocard n Mastercard I visa CardNo. Expirydate ttl ttt ttl ttl | ,]-, I Name Address SGMMembership no. (if applicable) Signature Date Sendyour completedform to: Microbiology EditorialOffice, Societyfor GeneralMicrobiology, Marlborough House, BasingstokeRoad, Spencers Wood, ReadingRG7 1AG, UK Tel.+44 (0X 18988 1820 Fax+44(0X18 988 1834 [email protected] Thenatuleof TSEs ChrisBostock .i.lir Scientistsare Creutzfeld-Jacobdisease (CJD) and bovine The nature of the infectious agent unsureof the spongiform encephalopathy(BSE or mad cow There are currently three theories. One says that the disease)both belong to a group of diseasesinfectious agent is somewhat like a small conventional identityof the genetic material coding for its own proteins. infectiouscalled transmissible spongiform encephalopathies virus, with causative (TSEs) or prion diseases.BSE and the new variant of At present there is little evidence to support this theory. agentof TSEs, but CJD (vCJD) have been in the news recently and are new The second, and now most widely held theory states theproperties are additions to the group, but, as a whole, TSEs have been that it is the altered physical state of normal host prion unlikethose of around for centuries. Scrapie in sheep was first recorded protein, which is able to propagate itself by inducing conventional over two hundred years ago and sporadic CJD was first other normal prion protein molecules to adopt the pathogens. described in humans in the 7920s. Nevertheless, the abnormal conformation. This is commonly referred to TSEs remained a rather obscure group of diseasesuntil as the prion hypothesis. The third idea, called the virino 1986 when BSE first appeared.In the years since the hypothesis, is most easily thought of as a hybrid of these emergence of BSE, new TSEs have also been found in hypotheses.It suggeststhat there is a very small piece of exotic species of ruminants in UK zoos, exotic and genetic material, which encodesonly information for its domestic cats and, in 1996, vCJD was described in own survival and replication through interaction with a humans. host protein, perhaps the prion protein, using it also as The TSEs are fatalonce clinical signs appear,but there a protective coat. The essential, but very important is a long, usually many years,incubation period between difference between the prion and virino hypotheses the time of first exposure to the infectious agent and the is that in the prion hypothesis, all the information to time of appearance of disease. A normal microbial determine the properties of the infectious agent is infection usually elicits an immune responsein its target carried in the abnormal conformational state of the host, but in TSEs there is no conventional immune prion protein, whereas in the virino hypothesis, the 'genetic' fesponse, although the immune system plays an information is carried in an independent BELOW: the disease,before molecule. As yet no-one has defined the precise iri,;1.;i. Abnormalprion Protein important part in the development of canbe detected asbrown dePosits the infectious agent gets into the central nervous system molecular state(s) of the normal and infectious forms of 'prions' followingstaining withanlibodies (CNS). A common feature of all TSEs is degeneration the prion