Issues of authorship pracce and policy in experimental science research labs Cassandra Extavour Associate Professor Organismic and Evoluonary Biology Harvard University Members of the research team Principal Invesgator Graduate Postdocs Students Research Undergraduate Assistants Students Members of the research team have different goals Principal Invesgator Graduate Postdocs Students Research Undergraduate Assistants Students Authorship has different values for different members of the team Principal Invesgator Graduate Postdocs Students Research Undergraduate Assistants Students Authorship order has specific meaning, which is different in different fields of scholarship RESEARCH ARTICLE 5015 • DevelopmentAuthorship is merited if you have contributed substanally 138, 5015-5026 (2011) doi:10.1242/dev.073395 © 2011.to Published by The Company of Biologists Ltd Notch/Delta– Experimental design signalling is not required for segment generation– Carrying out experiments in the basally branching insect Gryllus bimaculatus– Analyzing data – Wring the manuscript Franz Kainz1,2, Ben Ewen-Campen1, Michael Akam2 and Cassandra G. Extavour1,* – Obtaining funding for the research • SUMMARYWho decides who has contributed substanally? First authorArthropods: carried out and vertebrates display a segmental body organisation along all Last authoror part of the : senior author anterior-posterior axis. Whether this reflects– aDifferent team members may differ in their definion of shared, ancestral developmental genetic mechanism for segmentation is uncertain. In vertebrates, segments are formed bulk of experimental and/sequentially by a segmentation ‘clock’ of oscillating gene expression involving Notch= PI. Usually major pathway components. Recent studies in or analycal work. Usually spiders and“substanal” basal insects have suggested that segmentation in these arthropodscontributor of intellectual also involves Notch-based signalling. These grad student or postdoc. observations have been interpreted as evidence for a shared, ancestral gene networkcontent and funding. for insect, arthropod and bilaterian segmentation.– Ulmately the PI makes this decision However, because this pathway can play multiple roles in development, elucidating the specific requirements for Notch– signallingPI should is important for understanding the ancestry of segmentation. Here we show that Delta, a ligand of the Notch Second authorpathway, is not: likely carried out some required for segment formationOther middle author in the cricket Gryllus bimaculatus: could have contributed in any , which retains ancestral characteristics of of experimental and/or analycal work. arthropod •embryogenesis. Clarify expectaons/lab publicaon policy Segment patterningway but how is unclear; less experimental/analycal genes are expressed before Delta in abdominal segments, and Delta expression doesUsually student or technician. not oscillate• guide other team members in effecve communicaon/negoaon of in the pre-segmental regioncontribuon than preceding authors AND less senior or in formed segments. Instead, Delta is required for neuroectoderm and mesectodermauthorship goals formation; embryos missing these tissues are developmentally delayed and show defects in segment morphology but normal segment number. Thus, what initially appear to berole played than last author. ‘segmentation phenotypes’ can in fact be due to developmental delays and cell specification errors. Our data do not support an essential or ancestral role of Notch signalling in segment generation across the arthropods, and show that the pleiotropy of the Notch pathway can confound speculation on possible segmentation mechanisms in the last common bilaterian ancestor. KEY WORDS: Arthropod, Segmentation clock, Evolution, Neurogenic phenotype, Gryllus bimaculatus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epartment of Organismic and Evolutionary Biology, Harvard University, 16 Divinity /"#$"%&( ,.&&"0%1%#( 1%( /3*0&J#"0$( .0&30*,*'/6( 1%2-5'1%# Avenue, Cambridge, MA 02138, USA. 2Laboratory for Development and Evolution, University Museum of Zoology, Department of Zoology, University of Cambridge, %"50*#"%"/1/6(.>1/("-*%#.&1*%(.%'(.,*,&*/1/8(Z>,0"//1*%(*4(G*&23 Downing Street, Cambridge CB2 3EJ, UK. ,.&3:.+( #"%"/( 1%( &3"( /3*0&J#"0$( 1%/"2&/( 6"'5#(',1* 2)$0).-,1 ?)""&-"F(.%'(72&'$0#2-"2)*8"-8)"') ?-*25/&F('*(%*&(/5##"/&(0*-"/(1% *Author for correspondence ([email protected]) ".0-+(/"#$"%&(#"%"0.&1*%(?@".0'"%(.%'(;P.$6(CDDDI(;0.%'.("&(.-86 Accepted 13 September 2011 CDDEF8(R*0"*7"06(1%(39*5'1)2,()0,$6(G*&23(/1#%.--1%#(1/($.&"0%.--+ Germ cell selection in genetic mosaics in Drosophila melanogaster Cassandra Extavour* and Antonio Garcı´a-Bellido†‡ *Museum Molecular Laboratory, University Museum of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom; and †Laboratorio Gene´ tica del Desarrollo, Centro de Biologı´a Molecular, Universidad Auto´ noma de Madrid, 28049 Madrid, Spain Contributed by Antonio Garcı´a-Bellido, August 3, 2001 Heritable mutations in the germ line lead to genetically heteroge- ref. 8). Given the large number of genes likely to be required by neous, or mosaic, gonads. Many of the genes used in germ-line the germ line, and the complexity of germ-line development, Author's personal copy development also play roles in somatic development [Saffman, particularly the loss of 50% of germ-line cell precursors early in E. E. & Lasko, P. (1999) Cell. Mol. Life Sci. 55, 1141–1163]. Mutations development (1) (see below), we undertook clonal and mosaic in these genes may have cellular phenotypes throughout germ-line analyses to ask whether or not germ-line cells undergo cellular development leading to their differential elimination or survival, as competition in genetic mosaics. Cell competition and selection has been observed in somatic cells [Morata, G. & Ripoll, P. (1975) in the germ line have important population and evolutionary 288 D.P. Sarikaya et al. / Developmental Biology 363 (2012) 279–289 Dev. Biol. 42, 211–221]. We investigate whether mutations in implications (9, 10). heterozygosis are subject to pregametic selection in the germ line. To date, only two mosaic and clonal analyses in the germ line, We initiated clones of wild-type homozygous cells at different concerned with proliferative parameters of germ cellsdevelopmental over process subject to evolutionary change in Drosophi- Acknowledgments stages of development in gonads heterozygous for eight different developmental time, have been published (11, 12). Wieschauslid ovariole number. Because developmental studies on this group recessive chromosome deficiencies. Here we show that cell selec- and Szabad (11) performed a quantitative germ-line clonal tion takes place in mosaic germ-line populations. This phenomenon analysis, initiating clones from blastoderm through pupalhave stages. thus far been limited, future work could