Editorial

Welcome to issue two of Organogenesis! On the following pages, you will find another selection of papers describing ground-breaking work at the interface of developmental biology and organ transplantation and regeneration.

Two of the papers concern the stability of differentiation in the gut and its appendages, and carry important implications for regeneration and tissue engineering. The review by Shen et al. [1] considers the propensity of cells of the gastrointestinal system to transdifferentiate; that is, to taken on the differentiated state characteristic of another organ or part of an organ. As well as being very interesting from the point of view of basic developmental biology, this transdifferentiation offers a great hope to regenerative medicine because it may be possible to use an undamaged organ as a source of cells to replace those in a damaged organ. Pancreas, for example, may contain cells that can be persuaded to build new liver. The original report by Lear et al. challenges the traditional view that islet cells of the pancreas develop only from endodermal precursors and suggests that, at least in culture models, islet cells can differentiate from the mesenchyme as well. Again, the message is that lineage in the gastrointestinal system is not as inflexible as was once thought: future work may uncover the signals that promote ‘unconventional’ differentiation and, therefore, open new paths to regeneration.

Stability of differentiation is also connected, tangentially, with the paper that demonstrates a negative correlation between the evolutionary age of an organ and that organ’s propensity to become cancerous in humans. This correlation may be entirely spurious, or it may indicate some deep-seated instability in the differentiated states of ‘modern’ organs, an instability we may one day be able either to use or to control.

The remaining papers address aspects of transplantation, and both point to techniques that may one day improve clinical outcomes. Rogers and Hammerman report a novel way of stimulating the development and function of transplanted foetal kidneys by treating them, just before transplantation, with vitamin D3. The mechanism by which vitamin D3 works in this system is not yet clear. Indeed, the fact vitamin D3 is more effective than its derivative, 1,25(OH)2D3, which is the active molecule in most systems, suggests that the explanation will not be simple. Nevertheless, from a technical point of view, Rogers and Hammerman’s technique can begin to be useful even before it is understood deeply. The report by Sawada et al. focuses on the largest and most accessible organ of the human body, the skin. The authors describe a transplantation technique that can be used to expand the area of epithelium by culturing it in vivo in a way that encourages it to form a cyst.

I hope you enjoy this issue, and that you will consider Organogenesis for publication of your own research in the general areas of organ development, regeneration, and tissue engineering.     

A breath of fresh air in lung regeneration

Enhancing the ability of the lungs to regenerate following injury could revolutionize the treatment of a wide range of different diseases. In this issue, Kumar et al. (2011) and Ding et al. (2011) dissect the cellular and molecular mechanisms of murine lung regeneration following injury and provide insights into the basic biology of the organ with implications for development of future therapeutic approaches.     

Moving right along: how PP1 helps clear the checkpoint

Spindle checkpoint silencing is crucial for cell-cycle progression, but mechanisms underlying this process remain mysterious. Two papers, one in this issue of Developmental Cell (Meadows et?al., 2011) and one in Current Biology (Rosenberg et?al., 2011), begin to show how phosphatase PP1-gamma connects chromosome-microtubule attachment with anaphase entry.     

Decision making: singin' in the brain

Which neurons in the brain "decide" to initiate particular behaviors in response to sensory information? In this issue of Neuron, two papers (Kohatsu et?al. and von Philipsborn et?al.) identify candidates in the courtship circuitry of Drosophila. The activity of these neurons is both regulated by sex pheromones and necessary and sufficient to trigger male love song.     

DLK: the "preconditioning" signal for axon regeneration?

In this issue of Neuron, Shin et?al. (2012) show that the dual leucine zipper kinase (DLK) is responsible for the retrograde injury signal in spinal sensory and motor neurons. DLK is required for the accelerated regeneration seen after axotomy and for the improved regeneration seen after a conditioning injury. DLK KO axons have severely reduced axon regeneration in?vivo.     

Forcing the third dimension

One goal of biomedical research is to reliably construct surrogate tissues for replacement therapy and to promote tissue regeneration. In this issue of Cell, Chun et al. (2006) provide insight into the molecular basis of tissue-specific differentiation. The authors show that remodeling of the extracellular matrix by the matrix metalloproteinase MT1-MMP contributes to the three-dimensional development of white adipose tissue in mice.     

A kinase gets caspases into shape

Two new papers (Kuranaga et al., 2006; Oshima et al., 2006) describe a previously uncharacterized Drosophila kinase (DmIKK epsilon) that regulates the abundance of DIAP1, a protein best known for its ability to inhibit apoptosis. However, DmIKK epsilon-mediated degradation of DIAP1 does not regulate apoptosis as might be predicted but instead regulates actin dynamics, cell morphology, and the differentiation of sensory organ precursor cells.     

Chemokinetics

How do migrating neural progenitor cells and growing axons know where to go? In this issue of Neuron, two papers (Knaut et al. and Lieberam et al.) demonstrate that activation of Cxcr4 chemokine receptors by the chemokine SDF1/Cxcl12 can direct both of these tasks.     

Introduction by the Chairman

Tropical forest ecosystems are the world's richest and most complex habitats and globally recognised for their importance in the human survival. Birds constitute an important component of tropical forests, not only in terms of their diversity, but also in terms of their role in the ecosystem. However, despite great advances made in our knowledge and protection of tropical forest birds, our efforts remain inadequate, particularly in Africa. African forests are being cut down by a very high rate (4 million hectare disappearing per year), putting at risk so many bird species, that the first challenge for research and conservation is to help managers in identifying priorities.

The relationship emphasised by the theme of the PAOC 9 “Birds, Habitats and People” is well examined during the symposium on the “Conservation of Forest Birds in Afiica”. The papers presented cover a wide range of topics. A broad scale analysis on the congruence between forest birds and mammals (Neil et al.) compares species richness and species endemism in the Afrotropical region. Larison et al. compare avian biodiversity of montane forest birds of northern Cameroon and Bioko island and evaluate their conservation potential based on species richness and human impacts and attitudes. A similar approach is done by Waiyaki and Bennun on birds of coastal forests in southern Kenya, while Math et al. examine the distribution the east Coast Akalat Sheppardia gunningi sokokensis in one single forest of Arabuko-Sokoke. The major threat to tropical forests today is the selective logging. The effect of this issue is presented by Dranzoa in a case study from Uganda's Kibale National Park.

Results of these papers show the necessity to take into account the particular requirements of all species in the management of the forest, the socio-cultural considerations in implementation of conservation measures, the necessity of policy changes in some cases and the necessity of further research.     

Amyloid-beta and tau pathologies act synergistically to induce novel disease stage-specific microglia subtypes

Drug-refractory forms of neurological diseases could find their next breakthrough therapy in non-pharmacological approaches to brain repair. Lentini et al. present the potential of in situ brain regeneration to address neurodegeneration in the epileptic brain.

     

The high road and the low road: trafficking choices in plants

Polar transport of the signaling molecule auxin is critical for plant development and depends on both the polar distribution of auxin efflux carriers, which pump auxin out of the cell and the alignment of these polarized cells. Two papers in this issue of Cell (Michniewicz et al., 2007; Jaillais et al., 2007) address how polar transport of these carriers occurs and describe the endosomal pathways involved.     

MicroRNA regulation of stem cell fate

MicroRNAs modulate target gene expression and are essential for normal development, but how does this pathway impact cell fate decisions? In this issue of Cell Stem Cell, Ivey et al. (2008) find that muscle-specific microRNAs repress nonmuscle genes to direct embryonic stem cell differentiation to mesoderm and muscle.     

Alternative cells for regeneration

Normally, in fish fin regeneration, bone regenerates from bone. But what happens when there is no bone? Singh et al. (2012) show in this issue of Developmental Cell that the bony rays still regenerate from an alternative cell source.     

Guest Editorial

Abstract

This special issue is a selection of papers from the sessions on Molecular Simulation that were presented at the annual American Institute of Chemical Engineering meeting in Miami Beach, Florida, in November 1992. It reflects the great diversity of research that is now underway using atomic-level computer simulation methods and the progression to simulations of more complex systems. In this issue, for instance, the materials studied range from electrolytes (Chialvo and Cummings) to polymers (Broadbelt, LaMarca, Klein, Andrews and Colter) to precursors to exotic natural gas hydrates (Long and Sloan). The study of solid/fluid interfaces is an emerging theme. Wang and Fichthorn have studied the adsorption of EAM modeled Pt on Pt substrates. Ravi and Murad have produced an interesting new method of studying the adsorption of fluids, here nitrogen in pores. Uttorrnark et al. have studied the kinetics of growth and dissolution processes in solidAiquid systems.     

Journal of Cellular Biochemistry: Volume 113, Number 6, June, 2012

Cover: Adipose‐derived stem cells following induction of differentiation. See article by Shu et al, this issue, pages 2020–2026.     

Molecular Reproduction & Development Volume 79, Issue 2, February 2012 cover image

Reflected image assembly of a median sagittal section of the epididymal channel during the mating period in the seasonal breeder Podarcis sicula (lizard). The main channel lumen is filled with spermatozoa and secretory granules during this period. Details about the regionalization and specialization of this organ are detailed in Verderame et al. (this issue).     

Journal of Cellular Biochemistry: Volume 113, Number 1, January, 2012

Cover: The cover shows rapamycin inhibition of Epo‐dependent osteoblast differentiation in hBMSC cells. See article in this issue by Kim et al, pages 220–228.     

Early retinal activity and visual circuit development

Does spontaneous retinal activity prior to vision play a role in the establishment of visual maps? In this issue of Neuron, two separate papers by Huberman et al. and Hooks and Chen demonstrate a role for early spontaneous retinal activity in the establishment of ocular dominance columns and synaptic refinement at retinogeniculate synapses.