Cyclic Expression of Lhx2 Regulates Hair Formation

Hair is important for thermoregulation, physical protection, sensory activity, seasonal camouflage, and social interactions. Hair is generated in hair follicles (HFs) and, following morphogenesis, HFs undergo cyclic phases of active growth (anagen), regression (catagen), and inactivity (telogen) throughout life. The transcriptional regulation of this process is not well understood. We show that the transcription factor Lhx2 is expressed in cells of the outer root sheath and a subpopulation of matrix cells during both morphogenesis and anagen. As the HFs enter telogen, expression becomes undetectable and reappears prior to initiation of anagen in the secondary hair germ. In contrast to previously published results, we find that Lhx2 is primarily expressed by precursor cells outside of the bulge region where the HF stem cells are located. This developmental, stage- and cell-specific expression suggests that Lhx2 regulates the generation and regeneration of hair. In support of this hypothesis, we show that Lhx2 is required for anagen progression and HF morphogenesis. Moreover, transgenic expression of Lhx2 in postnatal HFs is sufficient to induce anagen. Thus, our results reveal an alternative interpretation of Lhx2 function in HFs compared to previously published results, since Lhx2 is periodically expressed, primarily in precursor cells distinct from those in the bulge region, and is an essential positive regulator of hair formation

Plxdc2 Is a Mitogen for Neural Progenitors

The development of different brain regions involves the coordinated control of proliferation and cell fate specification along and across the neuraxis. Here, we identify Plxdc2 as a novel regulator of these processes, using in ovo electroporation and in vitro cultures of mammalian cells. Plxdc2 is a type I transmembrane protein with some homology to nidogen and to plexins. It is expressed in a highly discrete and dynamic pattern in the developing nervous system, with prominent expression in various patterning centres. In the chick neural tube, where Plxdc2 expression parallels that seen in the mouse, misexpression of Plxdc2 increases proliferation and alters patterns of neurogenesis, resulting in neural tube thickening at early stages. Expression of the Plxdc2 extracellular domain alone, which can be cleaved and shed in vivo, is sufficient for this activity, demonstrating a cell non-autonomous function. Induction of proliferation is also observed in cultured embryonic neuroepithelial cells (ENCs) derived from E9.5 mouse neural tube, which express a Plxdc2-binding activity. These experiments uncover a direct molecular activity of Plxdc2 in the control of proliferation, of relevance in understanding the role of this protein in various cancers, where its expression has been shown to be altered. They also implicate Plxdc2 as a novel component of the network of signalling molecules known to coordinate proliferation and differentiation in the developing nervous system

Prox1 Is Required for Granule Cell Maturation and Intermediate Progenitor Maintenance During Brain Neurogenesis

The transcription factor Prox1 plays a crucial role in intermediate progenitor maintenance and hippocampal neuron differentiation during adult neurogenesis in the dentate gyrus region of the hippocampus

Evidence for genetic association of RORB with bipolar disorder

<p>Abstract</p> <p>Background</p> <p>Bipolar disorder, particularly in children, is characterized by rapid cycling and switching, making circadian clock genes plausible molecular underpinnings for bipolar disorder. We previously reported work establishing mice lacking the clock gene D-box binding protein (<it>DBP</it>) as a stress-reactive genetic animal model of bipolar disorder. Microarray studies revealed that expression of two closely related clock genes, <it>RAR</it>-related orphan receptors alpha (<it>RORA</it>) and beta (<it>RORB</it>), was altered in these mice. These retinoid-related receptors are involved in a number of pathways including neurogenesis, stress response, and modulation of circadian rhythms. Here we report association studies between bipolar disorder and single-nucleotide polymorphisms (SNPs) in <it>RORA </it>and <it>RORB</it>.</p> <p>Methods</p> <p>We genotyped 355 <it>RORA </it>and <it>RORB </it>SNPs in a pediatric cohort consisting of a family-based sample of 153 trios and an independent, non-overlapping case-control sample of 152 cases and 140 controls. Bipolar disorder in children and adolescents is characterized by increased stress reactivity and frequent episodes of shorter duration; thus our cohort provides a potentially enriched sample for identifying genes involved in cycling and switching.</p> <p>Results</p> <p>We report that four intronic <it>RORB </it>SNPs showed positive associations with the pediatric bipolar phenotype that survived Bonferroni correction for multiple comparisons in the case-control sample. Three <it>RORB </it>haplotype blocks implicating an additional 11 SNPs were also associated with the disease in the case-control sample. However, these significant associations were not replicated in the sample of trios. There was no evidence for association between pediatric bipolar disorder and any <it>RORA </it>SNPs or haplotype blocks after multiple-test correction. In addition, we found no strong evidence for association between the age-at-onset of bipolar disorder with any <it>RORA </it>or <it>RORB </it>SNPs.</p> <p>Conclusion</p> <p>Our findings suggest that clock genes in general and <it>RORB </it>in particular may be important candidates for further investigation in the search for the molecular basis of bipolar disorder.</p

An enriched model for the integrated berth allocation and quay crane assignment problem

Given the increasing pressure to improve the efficiency of container terminals, a lot of research efforts have been devoted to optimizing container terminal operations. Most papers deal with either the Berth Allocation Problem (BAP) or the (Quay) Crane Assignment Problem (CAP). In the literature, handling times are often simplified to be berth dependent or proportional to vessel size to ignore the CAP when scheduling vessels. This is unsatisfactory for real-life applications because the handling time primarily depends on the number of containers to be handled and the number of cranes deployed. Only a limited number of papers deal with the combination of berth allocation and crane assignment. In these papers however, authors often have resorted to algorithmic simplifications that limit the practical use of the models. This paper presents an integrated BAP-CAP model taking into account vessel priorities, preferred berthing locations and handling time considerations. The proposed MILP model is validated on real-life data illustrating the potential to support operational and tactical decision-making.container terminal; berth allocation; quay cranes; mathematical modelling

Tank allocation for liquid bulk vessels using a hybrid constraint programming approach

This papers considers the allocation of cargoes to tanks for the specific case of chemical liquid bulk vessels. No articles in the literature and no commercial software packages are available that can handle the multitude of side constraints that need to be considered. These constraints include segregation constraints for the chemicals on the one hand, to prevent chemicals from being loaded into certain types of tanks or next to other chemicals in adjacent tanks. On the other hand, the constraints include vessel stability considerations, which limit the volumes with which the tanks are loaded. A hybrid CP-LP model is presented in this paper, in which constraint programming (CP) is used to determine possible cargo-to-tank allocations, after which linear programming (LP) is used to generate actual loading plans that optimize the vessel stability. The validity and practical usefulness of this model are shown by solving real-life instances.Tank allocation problem, Constraint programming, Chemical tankers, Load planning.