Sema3D and Sema7A have distinct expression patterns in chick embryonic development

Abstract

By RT-PCR, we isolated a partial cDNA clone for the chick Semaphorin7A (Sema7A) gene. We further analyzed its expression patterns and compared them with those of the Sema3D gene, in chick embryonic development. Sema3D and Sema7A appeared to be expressed in distinct cell populations. In mesodermderived structures, Sema7A expression was detected in the newly formed somites, whereas Sema3D expression was found in the notochord. In ectoderm-derived tissues, Sema3D is expressed broadly in the surface ectoderm, lens and nasal placodes. Sema3D is also expressed in the developing nervous system including diencephalon, dorsal neural tube, optical and otic vesicles. In the limb bud, Sema3D expression was found throughout the ectoderm excluding the apical ectoderm ridge (AER), where Sema7A is concentrated. Although both genes appeared to be expressed in the migrating neural crest cells, Sema3D expression is limited to neural crest cells migrating out of the midbrain/hindbrain regions, while Sema7A expression is widespread in both cranial and trunk neural crest cells. Developmental Dynamics 235: 2282-2289, 2006.

Subdivisions of chick diencephalic roof plate: Implication in the formation of the posterior commissure

“…The different axonal behaviors in the midline suggest that in this place the cells of the MDRP may secrete other guidance signal, different to SCO-spondin, which the axons required to decide if they have to cross or not the midline. In this context it has been described the presence of EphrA7 (Araujo and Nieto, 1997;Marin et al, 2001;Baker and Antin, 2003;Garcia-Calero et al, 2006) and semaphorin 3D (Bao and Jin, 2006) in diencephalic roof plate, although the precise location (lateral or medial) and the function of these molecules in PC development are unknown.…”

Expression of class III Semaphorins and their receptors in the developing chicken (Gallus gallus) inner ear

“…Using a cryostat, the inner ear was cut from dorsal‐to‐ventral as 15 μm‐thick sections. Embedded hearts were cut into 15 μm‐thick sagittal sections as a positive control for Sema3D and Sema3F in situ probes (Bao & Jin, ; Jin, Chau, & Bao, ). Adjacent sections were collected onto three sets of alternating Superfrost® Plus Slides (Fisherbrand®) and stored at −20 °C until subjected to in situ hybridization or immunohistochemistry.…”

“…For Sema3D (NM_205373.1, 1031‐1792) and Sema3F (NM_204258.1, 721‐1440), probe templates were created from chicken cDNA using primer sequences as reported earlier (Bao & Jin, ; Jin et al, ). The amplicons were inserted into the Topo TA vector.…”

Neural Crest Cell Migration

“…The otic region expresses semaphorins [19,30], but evidence for an inhibitory effect is lacking. For instance, the otic placode is adjacent to the rhombencephalon in amniotes and forces chick and mouse NCC to migrate anteriorly and posteriorly after delamination to join cells coming out of nearby rhombomeres.…”