Journal of Developmental Biology最新文献

The epidermal barrier of mammals is initially formed during embryonic development and continuously regenerated by the differentiation and cornification of keratinocytes in postnatal life. Cornification is associated with the breakdown of organelles and other cell components by mechanisms which are only incompletely understood. Here, we investigated whether heme oxygenase 1 (HO-1), which converts heme into biliverdin, ferrous iron and carbon monoxide, is required for normal cornification of epidermal keratinocytes. We show that HO-1 is transcriptionally upregulated during the terminal differentiation of human keratinocytes in vitro and in vivo. Immunohistochemistry demonstrated expression of HO-1 in the granular layer of the epidermis where keratinocytes undergo cornification. Next, we deleted the Hmox1 gene, which encodes HO-1, by crossing Hmox1-floxed and K14-Cre mice. The epidermis and isolated keratinocytes of the resulting Hmox1^f/f K14-Cre mice lacked HO-1 expression. The genetic inactivation of HO-1 did not impair the expression of keratinocyte differentiation markers, loricrin and filaggrin. Likewise, the transglutaminase activity and formation of the stratum corneum were not altered in Hmox1^f/f K14-Cre mice, suggesting that HO-1 is dispensable for epidermal cornification. The genetically modified mice generated in this study may be useful for future investigations of the potential roles of epidermal HO-1 in iron metabolism and responses to oxidative stress.

We have assembled ten interesting manuscripts submitted by developmental biologists in Japan [...].

The sexual fate of honeybees is determined by the complementary sex determination (CSD) model: heterozygosity at a single locus (the CSD locus) determines femaleness, while hemizygosity or homozygosity at the CSD locus determines maleness. The csd gene encodes a splicing factor that regulates sex-specific splicing of the downstream target gene feminizer (fem), which is required for femaleness. The female mode of fem splicing occurs only when csd is present in the heteroallelic condition. To gain insights into how Csd proteins are only activated under the heterozygous allelic composition, we developed an in vitro assay system to evaluate the activity of Csd proteins. Consistent with the CSD model, the co-expression of two csd alleles, both of which lack splicing activity under the single-allele condition, restored the splicing activity that governs the female mode of fem splicing. RNA immunoprecipitation quantitative PCR analyses demonstrated that the CSD protein was specifically enriched in several exonic regions in the fem pre-mRNA, and enrichment in exons 3a and 5 was significantly greater under the heterozygous allelic composition than the single-allelic condition. However, in most cases csd expression under the monoallelic condition was capable of inducing the female mode of fem splicing contrary to the conventional CSD model. In contrast, repression of the male mode of fem splicing was predominant under heteroallelic conditions. These results were reproduced by real-time PCR of endogenous fem expression in female and male pupae. These findings strongly suggest that the heteroallelic composition of csd may be more important for the repression of the male splicing mode than for the induction of the female splicing mode of the fem gene.

Podocytes are exquisitely fashioned kidney cells that serve an essential role in the process of blood filtration. Congenital malformation or damage to podocytes has dire consequences and initiates a cascade of pathological changes leading to renal disease states known as podocytopathies. In addition, animal models have been integral to discovering the molecular pathways that direct the development of podocytes. In this review, we explore how researchers have used the zebrafish to illuminate new insights about the processes of podocyte ontogeny, model podocytopathies, and create opportunities to discover future therapies.

The trigeminal ganglion contains the cell bodies of sensory neurons comprising cranial nerve V, which relays information related to pain, touch, and temperature from the face and head to the brain. Like other cranial ganglia, the trigeminal ganglion is composed of neuronal derivatives of two critical embryonic cell types, neural crest and placode cells. Neurogenesis within the cranial ganglia is promoted by Neurogenin 2 (Neurog2), which is expressed in trigeminal placode cells and their neuronal derivatives, and transcriptionally activates neuronal differentiation genes such as Neuronal Differentiation 1 (NeuroD1). Little is known, however, about the role of Neurog2 and NeuroD1 during chick trigeminal gangliogenesis. To address this, we depleted Neurog2 and NeuroD1 from trigeminal placode cells with morpholinos and demonstrated that Neurog2 and NeuroD1 influence trigeminal ganglion development. While knockdown of both Neurog2 and NeuroD1 affected innervation of the eye, Neurog2 and NeuroD1 had opposite effects on ophthalmic nerve branch organization. Taken together, our results highlight, for the first time, functional roles for Neurog2 and NeuroD1 during chick trigeminal gangliogenesis. These studies shed new light on the molecular mechanisms underlying trigeminal ganglion formation and may also provide insight into general cranial gangliogenesis and diseases of the peripheral nervous system.

The integument of vertebrates is a complex and large organ positioned at the interface with the aquatic or terrestrial environment, and is derived from the embryonic ectoderm (epidermis) and mesoderm (dermis and hypodermis) [...].

Amphibian skin is a particularly complex organ that is primarily responsible for respiration, osmoregulation, thermoregulation, defense, water absorption, and communication. The skin, as well as many other organs in the amphibian body, has undergone the most extensive rearrangement in the adaptation from water to land. Structural and physiological features of skin in amphibians are presented within this review. We aim to procure extensive and updated information on the evolutionary history of amphibians and their transition from water to land-that is, the changes seen in their skin from the larval stages to adulthood from the points of morphology, physiology, and immunology.

The reptile skin is a barrier against water loss and pathogens and an armor for mechanical damages. The integument of reptiles consists of two main layers: the epidermis and the dermis. The epidermis, the hard cover of the body which has an armor-like role, varies among extant reptiles in terms of structural aspects such as thickness, hardness or the kinds of appendages it constitutes. The reptile epithelial cells of the epidermis (keratinocytes) are composed of two main proteins: intermediate filament keratins (IFKs) and corneous beta proteins (CBPs). The outer horny layer of the epidermis, stratum corneum, is constituted of keratinocytes by means of terminal differentiation or cornification which is a result of the protein interactions where CBPs associate with and coat the initial scaffold of IFKs. Reptiles were able to colonize the terrestrial environment due to the changes in these epidermal structures, which led to various cornified epidermal appendages such as scales and scutes, a beak, claws or setae. Developmental and structural aspects of the epidermal CBPs as well as their shared chromosomal locus (EDC) indicate an ancestral origin that gave rise to the finest armor of reptilians.

High-quality academic publishing is built on rigorous peer review [...].

The adhesive digital pads in some gecko and anoline lizards are continuously utilized for movements on vertical surfaces that may determine wear and a decrease of adhesion efficiency. The pads are formed by lamellae bearing adhesive setae that are worn out following frequent usage and are replaced by new inner setae that maintain an efficient adhesion. Whether the extensive usage of adhesive setae determines a higher shedding frequency in the digital pads with respect to other body regions remains unknown. Setae replacement has been analyzed in embryos and adult lizards using autoradiography and 5BrdU-immunohistochemistry. The observation strongly suggests that during development and epidermal renewal in adult lamellae, there is a shifting of the outer setae toward the apex of the lamella. This movement is likely derived from the continuous addition of proteins in the beta- and alpha-layers sustaining the outer setae while the inner setae are forming. Ultrastructural and in situ hybridization studies indicate that the thin outer beta- and alpha-layers still contain mRNAs and ribosomes that may contribute to the continuous production of corneous beta proteins (CBPs) and keratins for the growth of the free margin at the apex of the lamella. This process determines the apical shifting and release of the old setae, while the new inner setae formed underneath becomes the new outer setae.