Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Angelo S
,
Lohr J
,
Lee KH
,
Ticho BS
,
Breitbart RE
,
Hill S
,
Yost HJ
,
Srivastava D
.
???displayArticle.abstract??? dHAND and eHAND are related basic helix-loop-helix transcription factors that are expressed in the cardiac mesoderm and in numerous neural crest-derived cell types in chick and mouse. To better understand the evolutionary development of overlapping expression and function of the HAND genes during embryogenesis, we cloned the zebrafish and Xenopus orthologues. Comparison of dHAND sequences in zebrafish, Xenopus, chick, mouse and human demonstrated conservation throughout the protein. Expression of dHAND in zebrafish was seen in the earliest precursors of all lateralmesoderm at early gastrulation stages. At neurula and later stages, dHAND expression was observed in lateral precardiac mesoderm, branchial arch neural crest derivatives and posteriorlateralmesoderm. At looping heart stages, cardiac dHAND expression remained generalized with no apparent regionalization. Interestingly, no eHAND orthologue was found in zebrafish. In Xenopus, dHAND and eHAND were co-expressed in the cardiac mesoderm without the segmental restriction seen in mice. Xenopus dHAND and eHAND were also expressed bilaterally in the lateralmesoderm without any left-right asymmetry. Within the branchial arches, XdHAND was expressed in a broader domain than XeHAND, similar to their mouse counterparts. Together, these data demonstrate conservation of HAND structure and expression across species.
???displayArticle.pubmedLink???
10906469
???displayArticle.link???Mech Dev ???displayArticle.grants???[+]
Fig. 3. dHAND expression in staged Xenopus embryos. Whole-mount in situ hybridization in Xenopus embryos revealed dHAND expression in punctate subepidermal cells (arrowheads) as early as stage 20 (A). The punctate cells later appeared to be migrating to the branchial arches and heart (C). dHAND expression was observed in the branchial arches throughout their development (C–E). dHAND was expressed bilaterally in the lateral plate mesoderm (lpm) at stage 24 through stage 33 (B–D). High magnification of the anteriorembryo better demonstrated expression in the looped heart tube and branchial arches at stage 37 (E). Even higher magnification of the cardiac region (F) demonstrated expression in the heart tube (ht) and outflow tract (ot) at stage 47 without any chamber restriction.
Fig. 4. eHAND expression in staged Xenopus embryos. eHAND expression in stage 15 Xenopus embryos was evident in the antero-lateralmesoderm (m) in lateral (A) and frontal (B) views. Bilaterally symmetric expression in the lateral plate mesoderm (lpm) was observed at stage 22 (C) and stage 33 in a ventral view (D). Expression in the precardiac mesoderm (pcm) became apparent at stage 30–33 (D). In a lateral view at stage 33 (E), branchial arch (ba) expression was observed in addition to the heart (ht) and lateral plate mesoderm expression. Magnification of the anterior region (F) better illustrated branchial arch and heart expression. High levels of heart expression were seen at stage 47 (G).
Fig. 2.
dHAND expression in staged zebrafish embryos. Whole-mount in situ hybridization (A–F) revealed expression of dHAND in the lateral plate mesoderm (lpm), pre-cardiac mesoderm (pcm), branchial arches (ba) and in the heart (ht). As early as 8 h post fertilization (hpf), expression was evident circumferentially in the anteriorlateral plate mesoderm (alpm) and posteriorlpm (plpm) in an oblique head-on view (A); positions of head (hd), eye (e) and tailbud (tb) are shown. At 12 hpf expression was again seen in the alpm and plpm (B); embryo is oriented with the head to the left and the tailbud to the right. Notochord (n) and yolk (y) are also noted. Expression in the pcm became evident at 18 hpf (C) and persisted into the heart tube at 24 hpf (D) seen ventrally, when branchial arch expression also became apparent. The embryo at 24 hpf demonstrated bilaterally symmetric expression of dHAND in the lateral plate mesoderm (E) in a dorsal view of the caudal region. Branchial arch expression persisted at 36 hpf (F) in the rostral region as seen dorsally. Transverse sections of 18 (G) and 24 (H) hpf embryos in the rostral and caudal regions, respectively, confirmed expression in the pcm and lpm. (I) demonstrates branchial arch expression of zdHAND at the histological level. (J) Shows expression of zdHAND throughout the heart tube.
hand1 (heart and neural crest derivatives expressed 1 ) gene expression in bisected Xenopus laevis embryo, mid-sagittal section, assayed via in situ hybridization, NF stage15, anteriorleft.
hand1 (heart and neural crest derivatives expressed 1 ) gene expression in sectioned Xenopus laevis embryo, assayed via in situ hybridization, NF stage 15, frontal view, anterior up.
hand1 (heart and neural crest derivatives expressed 1 ) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 22, lateral view, anteriorleft, dorsal up.
hand1 (heart and neural crest derivatives expressed 1 ) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 33, lateral view, anteriorleft, dorsal up.
hand1 (heart and neural crest derivatives expressed 1 ) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage47, dorsal view, anterior up.
hand2 (heart and neural crest derivatives expressed 2 ) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 22, lateral view, anteriorleft, dorsal up.
hand2 (heart and neural crest derivatives expressed 2 ) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 24, dorsal view, anterior up.
hand2 (heart and neural crest derivatives expressed 2 ) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 47 high magnification view of cardiac region.
