Effects of Usag-1 and Bmp7 deficiencies on murine tooth morphogenesis

[ackground]Wnt5a and Mrfzb1 genes are involved in the regulation of tooth size, and their expression levels are similar to that of Bmp7 during morphogenesis, including during the cap and early bell stages of tooth formation. We previously reported that Usag-1-deficient mice form supernumerary maxillary incisors. Thus, we hypothesized that BMP7 and USAG-1 signaling molecules may play important roles in tooth morphogenesis. In this study, we established double genetically modified mice to examine the in vivo inter-relationships between Bmp7 and Usag-1. [Results]We measured the volume and cross-sectional areas of the mandibular incisors using micro-computed tomography (micro-CT) in adult Bmp7- and Usag-1-LacZ knock-in mice and their F2 generation upon interbreeding. The mandibular incisors of adult Bmp7+/− mice were significantly larger than those of wild-type (WT) mice. The mandibular incisors of adult Usag-1−/− mice were the largest of all genotypes examined. In the F2 generation, the effects of these genes were additive; Bmp7+/− was most strongly associated with the increase in tooth size using generalized linear models, and the total area of mandibular supernumerary incisors of Usag-1−/−Bmp7+/− mice was significantly larger than that ofUsag-1−/−Bmp7 +/+ mice. At embryonic day 15 (E15), BrdU assays demonstrated that the labeling index of Bmp7+/− embryos was significantly higher than that of WT embryos in the cervical loop. Additionally, the labeling index of Usag-1−/− embryos was significantly the highest of all genotypes examined in dental papilla. [Conclusions]Bmp7 heterozygous mice exhibited significantly increased tooth sizes, suggesting that tooth size was controlled by specific gene expression. Our findings may be useful in applications of regenerative medicine and dentistry

Shape variation in the Skull Within and Between Wild Populations of the Raccoon Dog ( Nyctereutes procyonoides ) in Japan

Patterns of evolution can be biased by patterns of variability (propensity to vary). However, the effects of variability on evolution at the geographic and inter-subspecies levels have not been investigated extensively. Variation between different populations is the result of evolution. Individual variation within a single population can be indicative of species variability. Therefore, comparing patterns of variation within and between populations can reveal the effects of variability on evolution. In this study, I used two-dimensional geometric morphometric methods to evaluate variation in the shape of raccoon dog skulls within and between wild populations in Japan. In three of the populations observed, the dominant individual variation was cranial tilting. Cranial tilting is also a major variation between Japanese populations that has no correlation with climatic factors. However, differences in another morphological trait involving the frontal bone, parietal bone, and zygomatic arch dominated the variation between the Hokkaido population and other populations in Japan that are often considered to be a different subspecies. This morphological trait was correlated to snowfall. In conclusion, at the intra-subspecies level, morphological evolution in the skull is neutrally driven by variability. However, at the inter-subspecies level, adaptation may have a relatively larger effect on morphological evolution

哺乳類の歯における変異性と進化可能性

京都大学0048新制・課程博士博士(理学)甲第17384号理博第3881号新制||理||1559(附属図書館)30150京都大学大学院理学研究科生物科学専攻(主査)准教授 本川 雅治, 教授 疋田 努, 教授 中務 真人学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

Tooth size variation in pinniped dentitions

It is contentious whether size variation among mammalian teeth is heterogeneous or homogeneous, whether the coefficient of variation is reliable, and whether the standard deviation of log-transformed data and the residual of standard deviation on mean variable size are useful replacements for the coefficient of variation. Most studies of tooth size variation have been on mammals with complex-crowned teeth, with relatively little attention paid to taxa with simple-crowned teeth, such as Pinnipedia. To fill this gap in knowledge and to resolve the existing controversies, we explored the variation of linear size variables (length and width) for all teeth from complete permanent dentitions of four pinniped species, two phocids (Histriophoca fasciata, Phoca largha) and two otariids (Callorhinus ursinus, Eumetopias jubatus). Size variation among these teeth was mostly heterogeneous both along the toothrow and among species. The incisors, canines, and mesial and distal postcanines were often relatively highly variable. The levels of overall dental size variation ranged from relatively low as in land carnivorans (Phoca largha and both otariids) to high (Histriophoca fasciata). Sexual size dimorphism varied among teeth and among species, with teeth being, on average, larger in males than in females. This dimorphism was more pronounced, and the canines were larger and more dimorphic relative to other teeth in the otariids than in the phocids. The coefficient of variation quantified variation reliably in most cases. The standard deviation of log-transformed data was redundant with the coefficient of variation. The residual of standard deviation on mean variable size was inaccurate when size variation was considerably heterogeneous among the compared variables, and was incomparable between species and between sexes. The existing hypotheses invoking developmental fields, occlusal complexity, and the relative timing of tooth formation and sexually dimorphic hormonal activity do not adequately explain the differential size variation along the pinniped toothrow

Revisiting the evolutionary trend toward the mammalian lower jaw in non-mammalian synapsids in a phylogenetic context

The mammalian lower jaw comprises a single bone, the dentary, which is a unique feature among vertebrates. The lower jaws of extinct non-mammalian synapsids were composed of the dentary and several postdentary bones. Synapsid fossils exhibit variation in the dentary size relative to the overall lower jaw. An evolutionary trend toward dentary enlargement and postdentary reduction in non-mammalian synapsids has long been documented but has not been established using modern phylogenetic comparative methods. In this study, we examine the evolutionary pattern of dentary size relative to the lower jaw through phylogenetic analyses of measurements in a broad range of non-mammalian synapsid taxa. Our analyses revealed an evolutionary trend toward dentary area enlargement relative to the overall lower jaw in the lateral view across all non-mammalian synapsids. This trend is likely due to vertical expansion of the dentary given that the same trend is not evident when looking at anterior to posterior measurements of the dentary relative to the lower jaw as a whole in lateral view. Ancestral character reconstructions revealed that the evolution of the measurements was not unidirectional in non-mammalian synapsids. Our results provide no evidence of an evolutionary trend toward the dentary enlargement at the expense of postdentary bones across non-mammalian synapsids. This implies that the evolutionary origin of the mammalian lower jaw is not adequately explained by the evolutionary trend of dentary enlargement throughout non-mammalian synapsids. Instead, selection that occurred during the transition from non-mammalian cynodonts to early mammals may have produced the mammalian lower jaw

A pipeline approach for syntactic and semantic dependency parsing

This paper describes our system for syntactic and semantic dependency parsing to participate the shared task of CoNLL-2008. We use a pipeline approach, in which syntactic dependency parsing, word sense disambiguation, and semantic role labeling are performed separately: Syntactic dependency parsing is performed by a tournament model with a support vector machine; word sense disambiguation is performed by a nearest neighbour method in a compressed feature space by probabilistic latent semantic indexing; and semantic role labeling is performed by a an online passive-aggressive algorithm. The submitted result was 79.10 macroaverage F1 for the joint task, 87.18 % syntactic dependencies LAS, and 70.84 semantic dependencies F1. After the deadline, we constructed the other configuration, which achieved 80.89 F1 for the joint task, and 74.53 semantic dependencies F1. The result shows that the configuration of pipeline is a crucial issue in the task.