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Journal Cover Journal of Developmental Biology
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  This is an Open Access Journal Open Access journal
   ISSN (Online) 2221-3759
   Published by MDPI Homepage  [146 journals]
  • JDB, Vol. 4, Pages 22: Hedgehog Signalling in the Embryonic Mouse Thymus

    • First page: 22
      Abstract: T cells develop in the thymus, which provides an essential environment for T cell fate specification, and for the differentiation of multipotent progenitor cells into major histocompatibility complex (MHC)-restricted, non-autoreactive T cells. Here we review the role of the Hedgehog signalling pathway in T cell development, thymic epithelial cell (TEC) development, and thymocyte–TEC cross-talk in the embryonic mouse thymus during the last week of gestation.
      PubDate: 2016-07-16
      DOI: 10.3390/jdb4030022
      Issue No: Vol. 4, No. 3 (2016)
       
  • JDB, Vol. 4, Pages 23: Regulation of Hedgehog Signalling Inside and
           Outside the Cell

    • Authors: Simon Ramsbottom, Mary Pownall
      First page: 23
      Abstract: The hedgehog (Hh) signalling pathway is conserved throughout metazoans and plays an important regulatory role in both embryonic development and adult homeostasis. Many levels of regulation exist that control the release, reception, and interpretation of the hedgehog signal. The fatty nature of the Shh ligand means that it tends to associate tightly with the cell membrane, and yet it is known to act as a morphogen that diffuses to elicit pattern formation. Heparan sulfate proteoglycans (HSPGs) play a major role in the regulation of Hh distribution outside the cell. Inside the cell, the primary cilium provides an important hub for processing the Hh signal in vertebrates. This review will summarise the current understanding of how the Hh pathway is regulated from ligand production, release, and diffusion, through to signal reception and intracellular transduction.
      PubDate: 2016-07-20
      DOI: 10.3390/jdb4030023
      Issue No: Vol. 4, No. 3 (2016)
       
  • JDB, Vol. 4, Pages 24: The Role of Sonic Hedgehog in Craniofacial
           Patterning, Morphogenesis and Cranial Neural Crest Survival

    • Authors: Sebastian Dworkin, Yeliz Boglev, Harley Owens, Stephen Goldie
      First page: 24
      Abstract: Craniofacial defects (CFD) are a significant healthcare problem worldwide. Understanding both the morphogenetic movements which underpin normal facial development, as well as the molecular factors which regulate these processes, forms the cornerstone of future diagnostic, and ultimately, preventative therapies. The soluble morphogen Sonic hedgehog (Shh), a vertebrate orthologue of Drosophila hedgehog, is a key signalling factor in the regulation of craniofacial skeleton development in vertebrates, operating within numerous tissue types in the craniofacial primordia to spatiotemporally regulate the formation of the face and jaws. This review will provide an overview of normal craniofacial skeleton development, and focus specifically on the known roles of Shh in regulating the development and progression of the first pharyngeal arch, which in turn gives rise to both the upper jaw (maxilla) and lower jaw (mandible).
      PubDate: 2016-08-03
      DOI: 10.3390/jdb4030024
      Issue No: Vol. 4, No. 3 (2016)
       
  • JDB, Vol. 4, Pages 13: Hoxa5: A Key Player in Development and Disease

    • Authors: Lucie Jeannotte, Florian Gotti, Kim Landry-Truchon
      First page: 13
      Abstract: A critical position in the developmental hierarchy is occupied by the Hox genes, which encode transcription factors. Hox genes are crucial in specifying regional identity along the embryonic axes and in regulating morphogenesis. In mouse, targeted mutations of Hox genes cause skeletal transformations and organ defects that can impair viability. Here, we present the current knowledge about the Hoxa5 gene, a paradigm for the function and the regulation of Hox genes. The phenotypic survey of Hoxa5−/− mice has unveiled its critical role in the regional specification of the skeleton and in organogenesis. Most Hoxa5−/− mice die at birth from respiratory distress due to tracheal and lung dysmorphogenesis and impaired diaphragm innervation. The severity of the phenotype establishes that Hoxa5 plays a predominant role in lung organogenesis versus other Hox genes. Hoxa5 also governs digestive tract morphogenesis, thyroid and mammary glands development, and ovary homeostasis. Deregulated Hoxa5 expression is reported in cancers, indicating Hoxa5 involvement in tumor predisposition and progression. The dynamic Hoxa5 expression profile is under the transcriptional control of multiple cis-acting sequences and trans-acting regulators. It is also modulated by epigenetic mechanisms, implicating chromatin modifications and microRNAs. Finally, lncRNAs originating from alternative splicing and distal promoters encompass the Hoxa5 locus.
      PubDate: 2016-03-25
      DOI: 10.3390/jdb4020013
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 14: Hox Genes in Cardiovascular Development and
           Diseases

    • First page: 14
      Abstract: Congenital heart defects (CHD) are the leading cause of death in the first year of life. Over the past 20 years, much effort has been focused on unraveling the genetic bases of CHD. In particular, studies in human genetics coupled with those of model organisms have provided valuable insights into the gene regulatory networks underlying CHD pathogenesis. Hox genes encode transcription factors that are required for the patterning of the anterior–posterior axis in the embryo. In this review, we focus on the emerging role of anteriorly expressed Hox genes (Hoxa1, Hoxb1, and Hoxa3) in cardiac development, specifically their contribution to patterning of cardiac progenitor cells and formation of the great arteries. Recent evidence regarding the cooperative regulation of heart development by Hox proteins with members of the TALE-class of homeodomain proteins such as Pbx and Meis transcription factors is also discussed. These findings are highly relevant to human pathologies as they pinpoint new genes that increase susceptibility to cardiac anomalies and provide novel mechanistic insights into CHD.
      PubDate: 2016-03-24
      DOI: 10.3390/jdb4020014
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 15: Functional and Comparative Genomics of Hoxa2 Gene
           cis-Regulatory Elements: Evidence for Evolutionary Modification of
           Ancestral Core Element Activity

    • Authors: Adam Davis, Michael Reubens, Edmund Stellwag
      First page: 15
      Abstract: Hoxa2 is an evolutionarily conserved developmental regulatory gene that functions to specify rhombomere (r) and pharyngeal arch (PA) identities throughout the Osteichthyes. Japanese medaka (Oryzias latipes) hoxa2a, like orthologous Hoxa2 genes from other osteichthyans, is expressed during embryogenesis in r2–7 and PA2-7, whereas the paralogous medaka pseudogene, ψhoxa2b, is expressed in noncanonical Hoxa2 domains, including the pectoral fin buds. To understand the evolution of cis-regulatory element (CRE) control of gene expression, we conducted eGFP reporter gene expression studies with extensive functional mapping of several conserved CREs upstream of medaka hoxa2a and ψhoxa2b in transient and stable-line transgenic medaka embryos. The CREs tested were previously shown to contribute to directing mouse Hoxa2 gene expression in r3, r5, and PA2-4. Our results reveal the presence of sequence elements embedded in the medaka hoxa2a and ψhoxa2b upstream enhancer regions (UERs) that mediate expression in r4 and the PAs (hoxa2a r4/CNCC element) or in r3–7 and the PAs ψhoxa2b r3–7/CNCC element), respectively. Further, these elements were shown to be highly conserved among osteichthyans, which suggests that the r4 specifying element embedded in the UER of Hoxa2 is a deeply rooted rhombomere specifying element and the activity of this element has been modified by the evolution of flanking sequences that redirect its activity to alternative developmental compartments.
      PubDate: 2016-03-26
      DOI: 10.3390/jdb4020015
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 16: Mechanisms of Specificity for Hox Factor Activity

    • Authors: Arya Zandvakili, Brian Gebelein
      First page: 16
      Abstract: Metazoans encode clusters of paralogous Hox genes that are critical for proper development of the body plan. However, there are a number of unresolved issues regarding how paralogous Hox factors achieve specificity to control distinct cell fates. First, how do Hox paralogs, which have very similar DNA binding preferences in vitro, drive different transcriptional programs in vivo' Second, the number of potential Hox binding sites within the genome is vast compared to the number of sites bound. Hence, what determines where in the genome Hox factors bind' Third, what determines whether a Hox factor will activate or repress a specific target gene' Here, we review the current evidence that is beginning to shed light onto these questions. In particular, we highlight how cooperative interactions with other transcription factors (especially PBC and HMP proteins) and the sequences of cis-regulatory modules provide a basis for the mechanisms of Hox specificity. We conclude by integrating a number of the concepts described throughout the review in a case study of a highly interrogated Drosophila cis-regulatory module named “The Distal-less Conserved Regulatory Element” (DCRE).
      PubDate: 2016-05-09
      DOI: 10.3390/jdb4020016
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 17: Nutrient-Deprived Retinal Progenitors Proliferate
           in Response to Hypoxia: Interaction of the HIF-1 and mTOR Pathway

    • Authors: Helena Khaliullina, Nicola Love, William Harris
      First page: 17
      Abstract: At a cellular level, nutrients are sensed by the mechanistic Target of Rapamycin (mTOR). The response of cells to hypoxia is regulated via action of the oxygen sensor Hypoxia-Inducible Factor 1 (HIF-1). During development, injury and disease, tissues might face conditions of both low nutrient supply and low oxygen, yet it is not clear how cells adapt to both nutrient restriction and hypoxia, or how mTOR and HIF-1 interact in such conditions. Here we explore this question in vivo with respect to cell proliferation using the ciliary marginal zone (CMZ) of Xenopus. We found that both nutrient-deprivation and hypoxia cause retinal progenitors to decrease their proliferation, yet when nutrient-deprived progenitors are exposed to hypoxia there is an unexpected rise in cell proliferation. This increase, mediated by HIF-1 signalling, is dependent on glutaminolysis and reactivation of the mTOR pathway. We discuss how these findings in non-transformed tissue may also shed light on the ability of cancer cells in poorly vascularised solid tumours to proliferate.
      PubDate: 2016-05-19
      DOI: 10.3390/jdb4020017
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 18: Developmental Mechanism of Limb Field Specification
           along the Anterior–Posterior Axis during Vertebrate Evolution

    • Authors: Mikiko Tanaka
      First page: 18
      Abstract: In gnathostomes, limb buds arise from the lateral plate mesoderm at discrete positions along the body axis. Specification of these limb-forming fields can be subdivided into several steps. The lateral plate mesoderm is regionalized into the anterior lateral plate mesoderm (ALPM; cardiac mesoderm) and the posterior lateral plate mesoderm (PLPM). Subsequently, Hox genes appear in a nested fashion in the PLPM and provide positional information along the body axis. The lateral plate mesoderm then splits into the somatic and splanchnic layers. In the somatic layer of the PLPM, the expression of limb initiation genes appears in the limb-forming region, leading to limb bud initiation. Furthermore, past and current work in limbless amphioxus and lampreys suggests that evolutionary changes in developmental programs occurred during the acquisition of paired fins during vertebrate evolution. This review presents these recent advances and discusses the mechanisms of limb field specification during development and evolution, with a focus on the role of Hox genes in this process.
      PubDate: 2016-05-19
      DOI: 10.3390/jdb4020018
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 19: Regulation of Silk Genes by Hox and Homeodomain
           Proteins in the Terminal Differentiated Silk Gland of the Silkworm Bombyx
           mori

    • Authors: Shigeharu Takiya, Takuya Tsubota, Mai Kimoto
      First page: 19
      Abstract: The silk gland of the silkworm Bombyx mori is a long tubular organ that is divided into several subparts along its anteroposterior (AP) axis. As a trait of terminal differentiation of the silk gland, several silk protein genes are expressed with unique regional specificities. Most of the Hox and some of the homeobox genes are also expressed in the differentiated silk gland with regional specificities. The expression patterns of Hox genes in the silk gland roughly correspond to those in embryogenesis showing “colinearity”. The central Hox class protein Antennapedia (Antp) directly regulates the expression of several middle silk gland–specific silk genes, whereas the Lin-1/Isl-1/Mec3 (LIM)-homeodomain transcriptional factor Arrowhead (Awh) regulates the expression of posterior silk gland–specific genes for silk fiber proteins. We summarize our results and discuss the usefulness of the silk gland of Bombyx mori for analyzing the function of Hox genes. Further analyses of the regulatory mechanisms underlying the region-specific expression of silk genes will provide novel insights into the molecular bases for target-gene selection and regulation by Hox and homeodomain proteins.
      PubDate: 2016-05-25
      DOI: 10.3390/jdb4020019
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 20: Hedgehog Signaling in Endochondral Ossification

    • Authors: Shinsuke Ohba
      First page: 20
      Abstract: Hedgehog (Hh) signaling plays crucial roles in the patterning and morphogenesis of various organs within the bodies of vertebrates and insects. Endochondral ossification is one of the notable developmental events in which Hh signaling acts as a master regulator. Among three Hh proteins in mammals, Indian hedgehog (Ihh) is known to work as a major Hh input that induces biological impact of Hh signaling on the endochondral ossification. Ihh is expressed in prehypertrophic and hypertrophic chondrocytes of developing endochondral bones. Genetic studies so far have demonstrated that the Ihh-mediated activation of Hh signaling synchronizes chondrogenesis and osteogenesis during endochondral ossification by regulating the following processes: (1) chondrocyte differentiation; (2) chondrocyte proliferation; and (3) specification of bone-forming osteoblasts. Ihh not only forms a negative feedback loop with parathyroid hormone-related protein (PTHrP) to maintain the growth plate length, but also directly promotes chondrocyte propagation. Ihh input is required for the specification of progenitors into osteoblast precursors. The combinatorial approaches of genome-wide analyses and mouse genetics will facilitate understanding of the regulatory mechanisms underlying the roles of Hh signaling in endochondral ossification, providing genome-level evidence of the potential of Hh signaling for the treatment of skeletal disorders.
      PubDate: 2016-06-03
      DOI: 10.3390/jdb4020020
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 21: Signalling by Transforming Growth Factor Beta
           Isoforms in Wound Healing and Tissue Regeneration

    • Authors: Richard Gilbert, Matthew Vickaryous, Alicia Viloria-Petit
      First page: 21
      Abstract: Transforming growth factor beta (TGFβ) signalling is essential for wound healing, including both non-specific scar formation and tissue-specific regeneration. Specific TGFβ isoforms and downstream mediators of canonical and non-canonical signalling play different roles in each of these processes. Here we review the role of TGFβ signalling during tissue repair, with a particular focus on the prototypic isoforms TGFβ1, TGFβ2, and TGFβ3. We begin by introducing TGFβ signalling and then discuss the role of these growth factors and their key downstream signalling mediators in determining the balance between scar formation and tissue regeneration. Next we discuss examples of the pleiotropic roles of TGFβ ligands during cutaneous wound healing and blastema-mediated regeneration, and how inhibition of the canonical signalling pathway (using small molecule inhibitors) blocks regeneration. Finally, we review various TGFβ-targeting therapeutic strategies that hold promise for enhancing tissue repair.
      PubDate: 2016-06-22
      DOI: 10.3390/jdb4020021
      Issue No: Vol. 4, No. 2 (2016)
       
  • JDB, Vol. 4, Pages 2: Hermes (Rbpms) is a Critical Component of RNP
           Complexes that Sequester Germline RNAs during Oogenesis

    • Authors: Tristan Aguero, Yi Zhou, Malgorzata Kloc, Patrick Chang, Evelyn Houliston, Mary King
      First page: 2
      Abstract: The germ cell lineage in Xenopus is specified by the inheritance of germ plasm that assembles within the mitochondrial cloud or Balbiani body in stage I oocytes. Specific RNAs, such as nanos1, localize to the germ plasm. nanos1 has the essential germline function of blocking somatic gene expression and thus preventing Primordial Germ Cell (PGC) loss and sterility. Hermes/Rbpms protein and nanos RNA co-localize within germinal granules, diagnostic electron dense particles found within the germ plasm. Previous work indicates that nanos accumulates within the germ plasm through a diffusion/entrapment mechanism. Here we show that Hermes/Rbpms interacts with nanos through sequence specific RNA localization signals found in the nanos-3′UTR. Importantly, Hermes/Rbpms specifically binds nanos, but not Vg1 RNA in the nucleus of stage I oocytes. In vitro binding data show that Hermes/Rbpms requires additional factors that are present in stage I oocytes in order to bind nanos1. One such factor may be hnRNP I, identified in a yeast-2-hybrid screen as directly interacting with Hermes/Rbpms. We suggest that Hermes/Rbpms functions as part of a RNP complex in the nucleus that facilitates selection of germline RNAs for germ plasm localization. We propose that Hermes/Rbpms is required for nanos RNA to form within the germinal granules and in this way, participates in the germline specific translational repression and sequestration of nanos RNA.
      PubDate: 2016-01-19
      DOI: 10.3390/jdb4010002
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 3: Notochord Cells in Intervertebral Disc Development
           and Degeneration

    • First page: 3
      Abstract: The intervertebral disc is a complex structure responsible for flexibility, multi-axial motion, and load transmission throughout the spine. Importantly, degeneration of the intervertebral disc is thought to be an initiating factor for back pain. Due to a lack of understanding of the pathways that govern disc degeneration, there are currently no disease-modifying treatments to delay or prevent degenerative disc disease. This review presents an overview of our current understanding of the developmental processes that regulate intervertebral disc formation, with particular emphasis on the role of the notochord and notochord-derived cells in disc homeostasis and how their loss can result in degeneration. We then describe the role of small animal models in understanding the development of the disc and their use to interrogate disc degeneration and associated pathologies. Finally, we highlight essential development pathways that are associated with disc degeneration and/or implicated in the reparative response of the tissue that might serve as targets for future therapeutic approaches.
      PubDate: 2016-01-21
      DOI: 10.3390/jdb4010003
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 4: Cell Fate Decisions During Breast Cancer Development

    • Authors: Kayla Gross, Ania Wronski, Adam Skibinski, Sarah Phillips, Charlotte Kuperwasser
      First page: 4
      Abstract: During the formation of breast cancer, many genes become altered as cells evolve progressively from normal to a pre-malignant to a malignant state of growth. How mutations in genes lead to specific subtypes of human breast cancer is only partially understood. Here we review how initial genetic or epigenetic alterations within mammary epithelial cells (MECs) can alter cell fate decisions and put pre-malignant cells on a path towards cancer development with specific phenotypes. Understanding the early stages of breast cancer initiation and progression and how normal developmental processes are hijacked during transformation has significant implications for improving early detection and prevention of breast cancer. In addition, insights gleaned from this understanding may also be important for developing subtype-specific treatment options.
      PubDate: 2016-01-22
      DOI: 10.3390/jdb4010004
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 5: Acknowledgement to Reviewers of Journal of
           Developmental Biology in 2015

    • Authors: Journal of Developmental Biology Editorial Office
      First page: 5
      Abstract: The editors of Journal of Developmental Biology would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]
      PubDate: 2016-01-25
      DOI: 10.3390/jdb4010005
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 6: Alterations in Synthesis and Repair of DNA during
           the Development of Loach Misgurnus fossilis

    • Authors: Leonid Gening, Andrei Lakhin, Irina Makarova, Valentina Nenasheva, Ludmila Andreeva, Vyacheslav Tarantul
      First page: 6
      Abstract: Using a modified radiolabeled primer extension method (we named this modification misGvA—“misincorporation of G versus A”) we have investigated the DNA synthesis and repair at early and late stages of development of loach Misgurnus fossilis. The misincorporation activity of DNA polymerase iota (Pol ι) in wild-type loach could not be detected by this method at any stage of loach development. In transgenic loach overexpressing human Pol ι we have shown that the bypassing of DNA synthesis arrest after incorporation of mismatched nucleotide by Pol ι (the T-stop) was not associated with this enzyme. Non-transgenic loach larvae are virtually lacking the capacity for error correction of DNA duplex containing a mismatched nucleotide. Such repair activity develops only in the adult fish. It appears that the initial stages of development are characterized by more intensive DNA synthesis, while in terminal stages the repair activities become more prominent. The misGvA approach clearly indicates substantial changes in the DNA synthesis intensity, although the role of particular replicative and repair DNA polymerases in this process requires further study.
      PubDate: 2016-01-27
      DOI: 10.3390/jdb4010006
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 7: Restricted Pax3 Deletion within the Neural Tube
           Results in Congenital Hydrocephalus

    • Authors: Hong-Ming Zhou, Simon Conway
      First page: 7
      Abstract: Congenital hydrocephalus is a common birth-defect whose developmental origins are poorly understood. Pax3-null mutants show defects in myogenesis, neural tube closure, neural crest morphogenesis, and heart development that, consequently, results in embryonic lethality. Here we demonstrate that conditional deletion of the mouse Pax3 transcription factor results in fully-penetrant congenital obstructive hydrocephalus. To identify the role of Pax3 during cranial development, we deleted Pax3 within the neuroepithelium (via Pax7−Cre), in the neural crest (via P0-Cre), and in both the neuroepithelium and the neural crest (via Wnt1-Cre). Only conditional mutants generated using Pax7−Cre or Wnt1-Cre developed early onset congenital hydrocephalus due to stenosis of the third ventricle, suggesting that loss of neuroepithelial Pax3 is sufficient to disturb third ventricle morphogenesis. Dilation of lateral ventricles occurs as early as E14.5, and lineage-mapping revealed that the neuroepithelial cells in the conditional mutants are present, but fail to undergo normal differentiation at the stenotic site. Concomitant with a narrowing of the mutant third ventricle, we detected ectopic apoptosis, reduced proliferation, and abnormal β-catenin localization. Furthermore, consistent with the overlapping expression pattern of Pax3 and Pax7 in early cranial neuroepithelium, we demonstrated a combinatorial role, as compound Pax3/Pax7 heterozygotes display partially-penetrant congenital hydrocephalus. These murine data provide an experimental paradigm underpinning clinical observations of the presence of PAX3 mutations in some hydrocephalic patients.
      PubDate: 2016-02-01
      DOI: 10.3390/jdb4010007
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 8: Solving Classification Problems for Large Sets of
           Protein Sequences with the Example of Hox and ParaHox Proteins

    • Authors: Stefanie Hueber, Tancred Frickey
      First page: 8
      Abstract: Phylogenetic methods are key to providing models for how a given protein family evolved. However, these methods run into difficulties when sequence divergence is either too low or too high. Here, we provide a case study of Hox and ParaHox proteins so that additional insights can be gained using a new computational approach to help solve old classification problems. For two (Gsx and Cdx) out of three ParaHox proteins the assignments differ between the currently most established view and four alternative scenarios. We use a non-phylogenetic, pairwise-sequence-similarity-based method to assess which of the previous predictions, if any, are best supported by the sequence-similarity relationships between Hox and ParaHox proteins. The overall sequence-similarities show Gsx to be most similar to Hox2–3, and Cdx to be most similar to Hox4–8. The results indicate that a purely pairwise-sequence-similarity-based approach can provide additional information not only when phylogenetic inference methods have insufficient information to provide reliable classifications (as was shown previously for central Hox proteins), but also when the sequence variation is so high that the resulting phylogenetic reconstructions are likely plagued by long-branch-attraction artifacts.
      PubDate: 2016-02-04
      DOI: 10.3390/jdb4010008
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 9: The Roles of Aquaporins in Plant Stress Responses

    • Authors: Zunaira Afzal, T. Howton, Yali Sun, M. Mukhtar
      First page: 9
      Abstract: Aquaporins are membrane channel proteins ubiquitously present in all kingdoms of life. Although aquaporins were originally discovered as water channels, their roles in the transport of small neutral solutes, gasses, and metal ions are now well established. Plants contain the largest number and greatest diversity of aquaporin homologs with diverse subcellular localization patterns, gating properties, and solute specificity. The roles of aquaporins in physiological functions throughout plant growth and development are well known. As an integral regulator of plant–water relations, they are presumed to play an important role in plant defense responses against biotic and abiotic stressors. This review highlights involvement of various aquaporin homologs in plant stress responses against a variety of environmental stresses that disturb plant cell osmotic balance and nutrient homeostasis.
      PubDate: 2016-02-04
      DOI: 10.3390/jdb4010009
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 10: HoxA Genes and the Fin-to-Limb Transition in
           Vertebrates

    • First page: 10
      Abstract: HoxA genes encode for important DNA-binding transcription factors that act during limb development, regulating primarily gene expression and, consequently, morphogenesis and skeletal differentiation. Within these genes, HoxA11 and HoxA13 were proposed to have played an essential role in the enigmatic evolutionary transition from fish fins to tetrapod limbs. Indeed, comparative gene expression analyses led to the suggestion that changes in their regulation might have been essential for the diversification of vertebrates’ appendages. In this review, we highlight three potential modifications in the regulation and function of these genes that may have boosted appendage evolution: (1) the expansion of polyalanine repeats in the HoxA11 and HoxA13 proteins; (2) the origin of +a novel long-non-coding RNA with a possible inhibitory function on HoxA11; and (3) the acquisition of cis-regulatory elements modulating 5’ HoxA transcription. We discuss the relevance of these mechanisms for appendage diversification reviewing the current state of the art and performing additional comparative analyses to characterize, in a phylogenetic framework, HoxA11 and HoxA13 expression, alanine composition within the encoded proteins, long-non-coding RNAs and cis-regulatory elements.
      PubDate: 2016-02-17
      DOI: 10.3390/jdb4010010
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 11: Histologic Assessment of Drug-Eluting Grafts
           Related to Implantation Site

    • First page: 11
      Abstract: Drug-eluting vascular prostheses represent a new direction in vascular surgery to reduce early thrombosis and late intimal hyperplasia for small calibre grafts. Subcutaneous implantation in rats is a rapid and cost-effective screening model to assess the drug-elution effect and could, to some extent, be useful to forecast results for vascular prostheses. We compared biological and histological responses to scaffolds in different implantation sites. Polycaprolactone (PCL), paclitaxel-loaded PCL (PCL-PTX) and dexamethasone-loaded PCL (PCL-DXM) electrospun scaffolds were implanted subcutaneously and in an infrarenal abdominal aortic model in rats for up to 12 weeks. At the conclusion of the study, a histological analysis was performed. Cellular graft invasion revealed differences in the progression of cellular infiltration between PCL-PTX and PCL/PCL-DXM groups in both models. Cell infiltration increased over time in the aortic model compared to the subcutaneous model for all groups. Cell counting revealed major differences in fibroblast, macrophage and giant cell graft colonisation in all groups and models over time. Macrophages and giant cells increased in the PCL aortic model; whereas in the subcutaneous model these cell types increased only after three weeks or even decreased in the drug-eluting PCL groups. Other major findings were observed only in the aortic replacement such as extracellular matrix deposition and neo-angiogenesis. The subcutaneous implant model can be used for screening, especially when drug-eluting effects are studied. However, major histological differences were observed in cell type reaction and depth of cell penetration compared to the aortic model. Our results demonstrate that the implantation site is a critical determinant of the biological response.
      PubDate: 2016-02-20
      DOI: 10.3390/jdb4010011
      Issue No: Vol. 4, No. 1 (2016)
       
  • JDB, Vol. 4, Pages 12: An Overview of Hox Genes in Lophotrochozoa:
           Evolution and Functionality

    • Authors: Marco Barucca, Adriana Canapa, Maria Biscotti
      First page: 12
      Abstract: Hox genes are regulators of animal embryonic development. Changes in the number and sequence of Hox genes as well as in their expression patterns have been related to the evolution of the body plan. Lophotrochozoa is a clade of Protostomia characterized by several phyla which show a wide morphological diversity. Despite that the works summarized in this review emphasize the fragmentary nature of the data available regarding the presence and expression of Hox genes, they also offer interesting insight into the evolution of the Hox cluster and the role played by Hox genes in several phyla. However, the number of genes involved in the cluster of the lophotrochozoan ancestor is still a question of debate. The data presented here suggest that at least nine genes were present while two other genes, Lox4 and Post-2, may either have been present in the ancestor or may have arisen as a result of duplication in the Brachiopoda-Mollusca-Annelida lineage. Spatial and temporal collinearity is a feature of Hox gene expression which was probably present in the ancestor of deuterostomes and protostomes. However, in Lophotrochozoa, it has been detected in only a few species belonging to Annelida and Mollusca.
      PubDate: 2016-03-19
      DOI: 10.3390/jdb4010012
      Issue No: Vol. 4, No. 1 (2016)
       
 
 
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