Gawantka V et al. (1998), Gene expression screening in Xenopus identifies...

XB-ART-13902

Mech Dev 1998 Oct 01;772:95-141.

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Gene expression screening in Xenopus identifies molecular pathways, predicts gene function and provides a global view of embryonic patterning.

Gawantka V , Pollet N , Delius H , Vingron M , Pfister R , Nitsch R , Blumenstock C , Niehrs C .

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In a large-scale gene expression screen 1765 randomly picked cDNAs were analyzed by whole-mount in situ hybridization in Xenopus embryos. Two hundred and seventy three unique, differentially expressed genes were identified, 204 of which are novel in Xenopus. Partial DNA sequences and expression patterns were documented and assembled into a database, 'AXelDB'. Approximately 30% of cDNAs analyzed represent differentially expressed genes and about 5% show highly regionalized expression. Novel marker genes and potential developmental regulators were found. Differential expression of mitochondrial genes was observed. Marker genes were used to study regionalization of the entire gastrula as well as the tail forming region and the epidermis of the tailbud embryo. Four 'synexpression' groups representing genes with shared, complex expression pattern that predict molecular pathways involved in patterning and differentiation were identified. According to their probable functional significance these groups are designated as Delta1, Bmp4, ER-import and Chromatin group. Within synexpression groups, a likely function of genes without sequence similarity can be predicted. The results indicate that synexpression groups have strong prognostic value. A cluster analysis was made by comparing gene expression patterns to derive a novel parameter, 'tissue relatedness'. In conclusion, this study describes a semi-functional approach to investigate genes expressed during early development and provides global insight into embryonic patterning.

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Species referenced: Xenopus
Genes referenced: 10a1.1 actl6a adam13 ag1 aifm2 akirin1 aldoa anxa5 apobec2 arl6ip1 arpc1b asl atp5mc3 atp6ap2 atp6v0c bambi blvra bmp4 bsg btg1 canx cbx3 ccdc50 ccnb1.2 ccnb3 cd63 cd81 cd9 cdk1 cdk4 cdknx churc1 cirbp cited4 ckap4 ckb cldn6.1 clic4 cluap1 copz1 cox5a cox7c crx ctnnbl1 cybrd1 cycs cyld cyp26a1 cystm1 ddit4 derl2 dhcr7 dhx32 dkc1 dkk1 dll1 eef1a1 eef1a1o eef2.1 efnb2 eif1 eif3b eif4g2 epha4 f11r fbxw4 fech fgfr4 ficd fn1 foxa4 frzb fth1.1 g0s2 gale gby gfpt1 gfpt2 glud1 gnb1 gpr4l.2 gs17 h1-6 h2az1 h3-5 hal.1 hao1 has1 hes5.5 hes5.6 hes5.7 hes6.1 hes7.2 hesx1 higd1a hmgb2 hmgb3 hmgn1 hmgn2 hmgn3 hnrnpa1 hnrnpa2b1 hnrnpab hnrnpdl hnrnpk hnrnpu hoxd1 hsp90b1 id2 id3 ilf2 ipo7 isyna1 itln1 jpt1 kcnk6 klf6 klhdc4 krt12.4 krt12.5 krt18.1 krt7 krt70 krt8.1 lbh ldhb lmo7 lsp1 magoh marcks marcksl1 MGC75753 mst1 msx2 mthfd2 myf5 myl1 naca nap1l1 nop56 nop58 not nradd nrarp nucks1 nudt9 odad2 odc1 ogt otx2 p4hb pax3 pcdh8.2 pcna perp pfkfb1 pitx2 plekhg4 plekho1 plod2 pnhd pnrc2 post pou5f3 ppdpf prdm1 preb prelid1 prmt1 psma2 ptma ptmap12 rbm28 rbm5 rcc1 rcl1 rcn3 rcor2 rhebl1 rhou rilpl1 rpa1 rpl29 rpl30 rpl37a rps2 rps20 rps3a scamp2 sec61a1 sec61b sec61g sema3a sesn2 sfpq slc22a4 slc25a20 slc25a20l slc25a24 slc30a2 sltm snu13 sox15 sox17a sox2 sox3 sp5l spint2 srsf2 srsf3 ss18 ssr2 ssr3 stard10 stmn1 tagln2 tardbp tbpl1 tbxt tmem126a tmpo tmsb4x tpt1 tuba1cl.3 tuba4b tuba5 tubb4a uap1 upk2 upk3a vdac2 ventx1.2 ventx2 XB22041735 XB5863530 XB5967085 xmc ywhaq znf326 znf451 znf608

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	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 6
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 7
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 8
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 9
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 10
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 11
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 12
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 13
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 14
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 15
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 16
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 17
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 18
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 19
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 20
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 21
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 22
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 23
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 24
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 25
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 26
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 27
	Fig. 3. Whole mount in situ hybridizations, sequence similarities and functional classifications. The left-most part represents the results of sequence similarity searches from 273 partially sequenced cDNAs representing unique, differentially expressed genes: clone name; accession number of best hit, P-value; name of best hit; functional classification. The order of the genes follows first digit sorting, e.g. 1, 10, 2, 20 etc. Abbreviations: o, orphan genes; m, metabolism gene; r, developmental regulator gene; r?, housekeeping regulator gene; s, structural gene; Xl, known Xenopus gene; +, GRAIL1 good coding potential; ++, GRAIL1 excellent coding potential. The P-value is the probability provided by the BLAST programme and calculated using Karlinltschul statistics, that the sequence similarity is due to randomness. For EST hits, the similarities derived from the comparison of the EST or cluster of EST sequences is given. The right-most part shows in situ hybridizations results for stages 10+, 13 and 30. Abbreviations are: a, animal view (stage 10); a, anterior view (stage 30); d, dorsal view; l, lateral view; p, posterior view; s, sagittal section; t, transverse section; v, vegetal view (stage 10); v, ventral view (stage 30). page 28
	Fig. 4. Gastrula regionalization. Whole-mount in situ hybridizations of gastrula embryos are shown. Expression in ectodermal and mes-endodermal domains is shown in upper and lower panel, respectively.(A,D,K) Dorsal view with animal pole facing up; (B,C,G,L), mid-sagittal sections, dorsal facing right, animal pole facing up; (E,F) animal view, dorsal facing up. (H,I,J) Vegetal view, dorsal facing up. bp, Dorsal blastopore lip; dac, dorsal animal cap; dNIMZ, dorsal non-involuting marginal zone; eac, epithelial layer of animal cap; sac, sensorial layer of animal cap; vac, ventral animal cap.
	Fig. 5. Tail regionalization. Whole-mount in situ hybridizations were carried out on tailbud embryos. The tail region in lateral view and vibratome sections thereof are shown. (A) Show selected marker gene expression, (N and O) show diagrams summarizing the identified domains in mid-sagittal and frontal view, respectively. Where indicated, frontal (f, posterior to the right), sagittal (s, posterior to the right), or transverse (t, dorsal to the top) vibratome sections are shown. Abbreviations: acnh, anterior chordoneural hinge; cnh, chordoneural hinge; end, endoderm; fs, forming somites; if, inner fin; mcnh, mid chordoneural hinge; of, outer fin; nec, neurenteric canal; pag, post-anal gut; pcnh, posterior chordoneural hinge; psm, presomitic mesoderm; pnc, posterior notochord; pw, posterior wall; scf, spinal cord floor; scr, spinal cord roof; so, somites; tpw, tip of posterior wall; vpw, ventral posterior wall.
	Fig. 6. Epidermal regionalization. Whole-mount in situ hybridizations of tailbud embryos are shown in lateral view. (A,B) Show pan-epidermal markers and (C) show genes with expression in various epidermal regions. cg, Cement gland; ci, ciliated cells; dae, dorsoanterior epidermis; f, fin; hg, hatching gland.
	Fig. 7. Synexpression groups. Whole-mount in situ hybridizations of tailbud embryos are shown in lateral view. Four groups of genes with shared, complex expression patterns (synexpression groups) are shown (see also Table 3). For the Delta1-group, expression patterns of XDelta1 and two group representatives are shown. For the Bmp4 group, expression patterns of Bmp4 and the two group representatives are shown. For the ER-import group, expression patterns of three group representatives are shown. For the chromatin group expression patterns of three group representatives are shown, with inserts displaying transverse sections of the trunk. Arrows indicate stained structures common to all members of the group. Bmp4 and XDelta1 were not isolated in this screen. Note, that the absence of staining in the endoderm of the chromatin group genes is probably due to technical difficulties to stain this tissue. Abbreviations: br, brain; ce, cement gland; de, dorsal eye; df, dorsal fin; en, endoderm; ey, eye; fs, forming somites; no, notochord; po, proctodeum; pr, pronephros; sc, spinal cord; so, somites; tb, tailbud; va, ventral visceral arches.
	Fig. 8. Analysis of tissue relatedness. Expression profiles of 206 cDNAs expressed in more than one tissue were selected. These profiles were arranged in a matrix and compared among each other using Fitch Margoliash algorithm to compute a tree using the implementation from the Phylip package. Length of lines corresponds relative distance between tissues (issue relatedness. Mesodermal and ectodermal derivatives are coloured in red and blue, respectively.
	blvra (biliverdin reductase A) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 13 or 30.
	Diagram summarizing the identified domains of the tail region, in mid-sagittal section. cnh, chordoneural hinge (orange to yellow); end, endoderm; if, inner fin; mcnh, of, outer fin; nec, neurenteric canal; pag, post-anal gut; pnc, posterior notochord (red); pw, posterior wall ( dark blue and light blue); scf, spinal cord, floor plate (light green); and scr, spinal cord, roof plate ( dark green).