Cranial bone morphometric study among mouse strains

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Little is known about the molecular mechanism which regulates how the whole cranium is shaped. Mouse models currently available for genetic research include several hundreds of unique inbred strains and genetically engineered mutants. By cross comparing their genomic structures, we can elucidate the cause of any differences in the phenotype between two strains. The craniometry of subspecies, or closely related species, of mice provide a good systemic model to study the relationship between genetic variance and cranial shape evolution. The lack of a quantified framework for comparing and analyzing mouse cranial shape has been a problem. For this reason, we performed quantitative analysis of cranial shape morphology between several mouse strains. Results: This article reports on a craniometric assay of seven mouse strains: four inbred strains (C57BL/6J, BALB/cA, C3H/HeJ, and CBA/JNCr) from Mus musculus domesticus (M. m. domesticus); one closed colony strain (ICR) from M. m. domesticus; one inbred strain (MSM/Ms) from Mus musculus molossinus; and, Mus spretus as a strain from a species other than M. m. domesticus. W

Comparative analysis of right element mutant lox sites on recombination efficiency in embryonic stem cells

<p>Abstract</p> <p>Background</p> <p>Cre-mediated site-specific integrative recombination in mouse embryonic stem (ES) cells is a useful tool for genome engineering, allowing precise and repeated site-specific integration. To promote the integrative reaction, a left element/right element (LE/RE) mutant strategy using a pair of <it>lox </it>sites with mutations in the LE or RE of the <it>lox </it>sequence has previously been developed. Recombination between LE and RE mutant <it>lox </it>produces a wild-type <it>lox</it>P site as well as an LE+RE double mutant <it>lox </it>site, which has mutations in both sides and less affinity to Cre, resulting in stable integration. We previously demonstrated successful integrative recombination using <it>lox</it>71 (an LE mutant) and <it>lox</it>66 (an RE mutant) in ES cells. Recently, other LE/RE mutant <it>lox </it>sites showing higher recombination efficiency in <it>Escherichia coli </it>have been reported. However, their recombination efficiency in mammalian cells remains to be analyzed.</p> <p>Results</p> <p>Using ES cells, we compared six RE mutant <it>lox </it>sites, focusing on their recombination efficiency with <it>lox</it>71. All of the RE mutant <it>lox </it>sites showed similar recombination efficiency. We then analyzed the stability of the recombined product, i.e., the LE+RE double mutant <it>lox </it>site, under continuous and strong Cre activity in ES cells. Two RE mutants, <it>lox</it>JTZ17 and <it>lox</it>KR3, produced more stable LE+RE double mutant <it>lox </it>than did the <it>lox</it>66/71 double mutant.</p> <p>Conclusion</p> <p>The two mutant RE <it>lox </it>sites, <it>lox</it>JTZ17 and <it>lox</it>KR3, are more suitable than <it>lox</it>66 for Cre-mediated integration or inversion in ES cells.</p

Role of Intrapancreatic SPINK1/Spink3 Expression in the Development of Pancreatitis

Studies on hereditary pancreatitis have provided evidence in favor of central role for trypsin activity in the disease. Identification of genetic variants of trypsinogen linked the protease to the onset of pancreatitis, and biochemical characterization proposed an enzymatic gain of function as the initiating mechanism. Mutations of serine protease inhibitor Kazal type 1 gene (SPINK1) are shown to be associated with hereditary pancreatitis. We previously reported that Spink3 (a mouse homolog gene of human SPINK1) deficient mice showed excessive autophagy, followed by inappropriate trypsinogen activation in the exocrine pancreas. These data indicate that the role of SPINK1/Spink3 is not only trypsin inhibitor, but also negative regulator of autophagy. On the other hand, recent studies showed that high levels of SPINK1 protein detected in a serum or urine were associated with adverse outcome in various cancer types. It has been suggested that expression of SPINK1 and trypsin is balanced in normal tissue, but this balance could be disrupted during tumor progression. Based on the structural similarity between SPINK1 and epidermal growth factor (EGF), we showed that SPINK1 protein binds and activates EGF receptor, thus acting as a growth factor on tumor cell lines. In this review, we summarize the old and new roles of SPINK1/Spink3 in trypsin inhibition, autophagy, and cancer cell growth. These new functions of SPINK1/Spink3 may be related to the development of chronic pancreatitis

Predicting dust extinction properties of star-forming galaxies from H-alpha/UV ratio

Using star-forming galaxies sample in the nearby Universe (0.02<z<0.10) selected from the SDSS (DR7) and GALEX all-sky survey (GR5), we present a new empirical calibration for predicting dust extinction of galaxies from H-alpha-to-FUV flux ratio. We find that the H-alpha dust extinction (A(Ha)) derived with H-alpha/H-beta ratio (Balmer decrement) increases with increasing H-alpha/UV ratio as expected, but there remains a considerable scatter around the relation, which is largely dependent on stellar mass and/or H-alpha equivalent width (EW(Ha)). At fixed H-alpha/UV ratio, galaxies with higher stellar mass (or galaxies with lower EW(Ha)) tend to be more highly obscured by dust. We quantify this trend and establish an empirical calibration for predicting A(Ha) with a combination of H-alpha/UV ratio, stellar mass and EW(Ha), with which we can successfully reduce the systematic uncertainties accompanying the simple H-alpha/UV approach by ~15-30%. The new recipes proposed in this study will provide a convenient tool for predicting dust extinction level of galaxies particularly when Balmer decrement is not available. By comparing A(Ha) (derived with Balmer decrement) and A(UV) (derived with IR/UV luminosity ratio) for a subsample of galaxies for which AKARI FIR photometry is available, we demonstrate that more massive galaxies tend to have higher extra extinction towards the nebular regions compared to the stellar continuum light. Considering recent studies reporting smaller extra extinction towards nebular regions for high-redshift galaxies, we argue that the dust geometry within high-redshift galaxies resemble more like low-mass galaxies in the nearby Universe.Comment: 14 pages, 14 figures, Accepted for publication in MNRA

Novel migrating mouse neural crest cell assay system utilizing P0-Cre/EGFP fluorescent time-lapse imaging

<p>Abstract</p> <p>Background</p> <p>Neural crest cells (NCCs) are embryonic, multipotent stem cells. Their long-range and precision-guided migration is one of their most striking characteristics. We previously reported that <it>P0-Cre/CAG-CAT-lacZ </it>double-transgenic mice showed significant lacZ expression in tissues derived from NCCs.</p> <p>Results</p> <p>In this study, by embedding a <it>P0-Cre/CAG-CAT-EGFP </it>embryo at E9.5 in collagen gel inside a culture glass slide, we were able to keep the embryo developing <it>ex vivo </it>for more than 24 hours; this development was with enough NCC fluorescent signal intensity to enable single-cell resolution analysis, with the accompanying NCC migration potential intact and with the appropriate NCC response to the extracellular signal maintained. By implantation of beads with absorbed platelet-derived growth factor-AA (PDGF-AA), we demonstrated that PDGF-AA acts as an NCC-attractant in embryos.</p> <p>We also performed assays with NCCs isolated from <it>P0-Cre/CAG-CAT-EGFP </it>embryos on culture plates. The neuromediator 5-hydroxytryptamine (5-HT) has been known to regulate NCC migration. We newly demonstrated that dopamine, in addition to 5-HT, stimulated NCC migration <it>in vitro</it>. Two NCC populations, with different axial levels of origins, showed unique distribution patterns regarding migration velocity and different dose-response patterns to both 5-HT and dopamine.</p> <p>Conclusions</p> <p>Although avian species predominated over the other species in the NCC study, our novel system should enable us to use mice to assay many different aspects of NCCs in embryos or on culture plates, such as migration, division, differentiation, and apoptosis.</p

A Study on the Bias-Correction Effect of the AIC for Selecting Variables in Normal Multivariate Linear Regression Models under Model Misspecification

Abstract By numerically comparing a variable-selection method using the crude AIC with those using the bias-corrected AICs, we find out knowledge about what kind of bias correction gives a positive effect to variable selection under model misspecification. Actually, since it can be proved theoretically that all the variable-selection methods considered in this paper asymptotically choose the same model as the best model, we conduct numerical examinations using small and moderate sample sizes. Our results show that bias correction under assumption that the mean structure is misspecified has a better effect on variable selection than that under the assumption that the distribution of the model is misspecified

Augmentation of smad‐dependent BMP signaling in neural crest cells causes craniosynostosis in mice

Craniosynostosis describes conditions in which one or more sutures of the infant skull are prematurely fused, resulting in facial deformity and delayed brain development. Approximately 20% of human craniosynostoses are thought to result from gene mutations altering growth factor signaling; however, the molecular mechanisms by which these mutations cause craniosynostosis are incompletely characterized, and the causative genes for diverse types of syndromic craniosynostosis have yet to be identified. Here, we show that enhanced bone morphogenetic protein (BMP) signaling through the BMP type IA receptor (BMPR1A) in cranial neural crest cells, but not in osteoblasts, causes premature suture fusion in mice. In support of a requirement for precisely regulated BMP signaling, this defect was rescued on a Bmpr1a haploinsufficient background, with corresponding normalization of Smad phosphorylation. Moreover, in vivo treatment with LDN‐193189, a selective chemical inhibitor of BMP type I receptor kinases, resulted in partial rescue of craniosynostosis. Enhanced signaling of the fibroblast growth factor (FGF) pathway, which has been implicated in craniosynostosis, was observed in both mutant and rescued mice, suggesting that augmentation of FGF signaling is not the sole cause of premature fusion found in this model. The finding that relatively modest augmentation of Smad‐dependent BMP signaling leads to premature cranial suture fusion suggests an important contribution of dysregulated BMP signaling to syndromic craniosynostoses and potential strategies for early intervention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/1/jbmr1857.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/2/jbmr1857-0008-sm-SupplFigS8.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/3/jbmr1857-0004-sm-SupplFigS4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/4/jbmr1857-0009-sm-SupplFigS9.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/5/jbmr1857-0005-sm-SupplFigS5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/6/jbmr1857-0001-sm-SupplFigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/7/jbmr1857-0006-sm-SupplFigS6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/8/jbmr1857-0002-sm-SupplFigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/9/jbmr1857-0007-sm-SupplFigS7.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/98343/10/jbmr1857-0003-sm-SupplFigS3.pd

Novel method to rescue a lethal phenotype through integration of target gene onto the X-chromosome.

The loss-of-function mutations of serine protease inhibitor, Kazal type 1 (SPINK1) gene are associated with human chronic pancreatitis, but the underlying mechanisms remain unknown. We previously reported that mice lacking Spink3, the murine homologue of human SPINK1, die perinatally due to massive pancreatic acinar cell death, precluding investigation of the effects of SPINK1 deficiency. To circumvent perinatal lethality, we have developed a novel method to integrate human SPINK1 gene on the X chromosome using Cre-loxP technology and thus generated transgenic mice termed "X-SPINK1". Consistent with the fact that one of the two X chromosomes is randomly inactivated, X-SPINK1 mice exhibit mosaic pattern of SPINK1 expression. Crossing of X-SPINK1 mice with Spink3+/- mice rescued perinatal lethality, but the resulting Spink3-/-;XXSPINK1 mice developed spontaneous pancreatitis characterized by chronic inflammation and fibrosis. The results show that mice lacking a gene essential for cell survival can be rescued by expressing this gene on the X chromosome. The Spink3-/-;XXSPINK1 mice, in which this method has been applied to partially restore SPINK1 function, present a novel genetic model of chronic pancreatitis