GENETIC VARIATION IN SYMPATRIC AND ALLOPATRIC POPULATIONS OF HYBRIDIZING FRESHWATER SNAIL SPECIES(VIVIPARUS ATER AND V. CONTECTUS)

To estimate the geographical extent of introgression, we studied the genetic structure of sympatric and allopatric populations of hybridizing freshwater snail species Viviparus ater and V. contectus in central Europe. Six allozyme loci which were variable in Lake Garda, Italy in a previous study (five nearly diagnostic loci between the two species and one highly polymorphic locus in V. contectus) were analyzed from ten sympatric locations and four allopatric populations each for the two species. Presumably introgressed genes (low allele frequencies) were found from at least one locus in seven out of the ten sympatric sites. These seven sites covered most of northern Italy. The data indicate that introgression has occurred from Viviparus contectus to V. ater and vice versa. Therefore, there is a possibility of widespread introgression or mosaic zones in nature. However, we cannot rule out that the observed patterns are due to the shared ancestry. V. ater possessed low genetic variation (the jackknifed mean of Wright's FST±S.E. over four loci was 0.041±0.004). On the other hand, V. contectus showed high genetic differentiation (the jackknifed mean of FST± S.E. over six loci was 0.546±0.166). Although introgression may have caused evolutionary changes in V. ater and V. contectus, it was not strong enough to level out the genetic differences between the two species, which may have originated from isolation among populations in V. contectus and a past bottleneck event in V. ate

Genetic and Systematic Study of Viviparus Georgianus (Lea), a Freshwater Snail Species Complex.

Genetic and morphological variation were studied in a brooding (ovoviviparous) and morphologically variable freshwater snail (Viviparus georgianus (Lea)) in the southeastern United States. Eleven populations were clustered into three genetically isolated, allopatric species characterized by 7 to 15 diagnostic loci out of the 38 loci examined. These allopatric species were an eastern species (in eastern and southern Florida), a western species (in the Florida panhandle), and a central species in the Ochlockonee River. Nei\u27s standard genetic distances between species were large (0.23-0.52) compared to within-species distances (0.00-0.06). Moreover, genetic distances between the Ochlockonee River species and other species were larger than the distance between the eastern and western species. Hierarchical F-statistics for differentiation among sites within drainage systems (F\sb{\rm SD}) of the western and eastern species were large (0.519 and 0.387, respectively). The F\sb{\rm DT} values (differentiation among drainage systems within the total area sampled) were negative, so most of the intraspecific genetic differentiation was due to differences among populations within drainage systems, rather than to differences among systems. Canonical discriminant analysis of nine shell measurements separated all three species with little overlap. The type specimens of the Viviparus georgianus complex and type locality specimens were compared to the discriminant function and canonical discriminant analyses of shell characters of the studied samples to assign correct species names. The western species and Ochlockonee River species appear to be Viviparus goodrichi Archer and Viviparus limi Pilsbry, respectively, which were originally described as subspecies of Viviparus contectoides (= Viviparus georgianus). The eastern species is Viviparus georgianus (Lea). The three species can be distinguished by the following morphological characteristics: V. goodrichi has a more globose shell with a larger aperture than V. limi; V. georgianus has shorter aperture height than the other species. Also, these three species can be identified reliably using allozyme characters

Direct Pulp Capping Effect with Experimentally Developed Adhesive Resin Systems Containing Reparative Dentin Promoting Agents on Rat Pulp -Mixed Amounts of Additives and Their Effect on Wound Healing-

This study examined the wound healing process of exposed rat pulp when treated with experimental adhesive resin systems. The experimental direct pulp capping adhesive resin systems were composed of primer-I, primer-II and an experimental bonding agent. Primer-I was Clearfil SE Bond (CSE) primer containing 1.0 or 5.0wt% CaCl2, and primer-II was CSE primer containing 0.1, 1.0 or 5.0wt% compound of equal mole of pA and pB with synthetic peptides derived from dentin-matrix-protein 1 (DMP1). Primer-I containing 1.0wt% and 5.0wt% CaCl2 were assigned to the experimental groups 1 to 3, and 4 to 6, respectively. Primer-II containing 0.1, 1.0 or 5.0wt% compound of pA and pB were assigned to the experimental groups 1 and 4, 2 and 5, and 3 and 6, respectively. In all experimental groups, CSE bond containing 10wt% hydroxyapatite powder was used as the experimental bonding agent. The positive control teeth were capped with calcium hydroxide preparation (Dycal), and the negative control teeth were capped with CSE. The specimens were alternately stained with Mayer's H&E and the enhanced polymer one-step staining method. Experimental groups 1, 4, 5 and 6 showed a higher level of reparative dentin formation compared to the negative control 14 days postoperatively. At 28 days postoperatively, all experimental groups showed the formation of extensive reparative dentin, and experimental groups 4, 5 and 6 demonstrated similar dentin bridge formation as that of the positive control. How quickly reparative dentin formation occurs might depend on the concentration of CaCl2 and pA and pB in the experimental primer

アタラシイ フチャク ヨクセイ ヒョウメン ショリ オ ホドコシタ コウ ヒョウメン エノ フンタイ ノ フチャク キョドウ ノ カイセキ

In this paper, we examined the relationship between surface roughness and particle adhesion behavior by a proposed experiment. Five kinds of SiO2 spherical powders (0.2μm-2.0μm) and stainless steel plates with seven kinds of surface roughness were used for the investigation. The adhesion ratios of SiO2 powders to polished stainless steel plates were measured. The adhesion ratios depend on the surface roughness and the particle diameters. The adhered particles on the steel plate were observed by SEM in order to examine the adhesion mechanism of SiO2 particle on the polished stainless plate substrate. As the result, 0.4-1.0 μm particles were easy to adhere independent of surface roughness and nominal powder diameter. The result indicates that adhesion behavior of powder depends on the adhesion force of 0.4-1.0 μm particles that are changed by the surface roughness of the steel plate

A new perspective on phylogeny and evolution of tetraodontiform fishes (Pisces: Acanthopterygii) based on whole mitochondrial genome sequences: Basal ecological diversification?

<p>Abstract</p> <p>Background</p> <p>The order Tetraodontiformes consists of approximately 429 species of fishes in nine families. Members of the order exhibit striking morphological diversity and radiated into various habitats such as freshwater, brackish and coastal waters, open seas, and deep waters along continental shelves and slopes. Despite extensive studies based on both morphology and molecules, there has been no clear resolution except for monophyly of each family and sister-group relationships of Diodontidae + Tetraodontidae and Balistidae + Monacanthidae. To address phylogenetic questions of tetraodontiform fishes, we used whole mitochondrial genome (mitogenome) sequences from 27 selected species (data for 11 species were newly determined during this study) that fully represent all families and subfamilies of Tetraodontiformes (except for Hollardinae of the Triacanthodidae). Partitioned maximum likelihood (ML) and Bayesian analyses were performed on two data sets comprising concatenated nucleotide sequences from 13 protein-coding genes (all positions included; third codon positions converted into purine [R] and pyrimidine [Y]), 22 transfer RNA and two ribosomal RNA genes (total positions = 15,084).</p> <p>Results</p> <p>The resultant tree topologies from the two data sets were congruent, with many internal branches showing high support values. The mitogenomic data strongly supported monophyly of all families and subfamilies (except the Tetraodontinae) and sister-group relationships of Balistidae + Monacanthidae and Tetraodontidae + Diodontidae, confirming the results of previous studies. However, we also found two unexpected basal splits into Tetraodontoidei (Triacanthidae + Balistidae + Monacanthidae + Tetraodontidae + Diodontidae + Molidae) and Triacanthodoidei (Ostraciidae + Triodontidae + Triacanthodidae).</p> <p>Conclusion</p> <p>This basal split into the two clades has never been reported and challenges previously proposed hypotheses based on both morphology and nuclear gene sequences. It is likely that the basal split had involved ecological diversification, because most members of Tetraodontoidei exclusively occur in shallow waters (freshwater, brackish and coastal waters, and open seas), while those of Triacanthodoidei occur mainly in relatively deep waters along continental shelves and slopes except for more derived ostraciids. This suggests that the basal split between the two clades led to subsequent radiation into the two different habitats.</p

Genetic stock compositions and natal origin of green turtle (Chelonia mydas) foraging at Brunei Bay

AbstractKnowledge of genetics composition and growth stages of endangered green turtles, as well as the connectivity between nesting and foraging grounds is important for effective conservation. A total of 42 green turtles were captured at Brunei Bay with curved carapace length ranging from 43.8 to 102.0 cm, and most sampled individuals were adults and large juveniles. Twelve haplotypes were revealed in mitochondrial DNA control region sequences. Most haplotypes contained identical sequences to haplotypes previously found in rookeries in the Western Pacific, Southeast Asia, and the Indian Ocean. Haplotype and nucleotide diversity indices of the Brunei Bay were 0.8444±0.0390 and 0.009350±0.004964, respectively. Mixed-stock analysis (for both uninformative and informative prior weighting by population size) estimated the main contribution from the Southeast Asian rookeries of the Sulu Sea (mean ≥45.31%), Peninsular Malaysia (mean ≥17.42%), and Sarawak (mean ≥12.46%). Particularly, contribution from the Sulu Sea rookery was estimated to be the highest and lower confidence intervals were more than zero (≥24.36%). When estimating contributions by region rather than individual rookeries, results showed that Brunei Bay was sourced mainly from the Southeast Asian rookeries. The results suggest an ontogenetic shift in foraging grounds and provide conservation implications for Southeast Asian green turtles

The dual origin of the peripheral olfactory system: placode and neural crest

<p>Abstract</p> <p>Background</p> <p>The olfactory epithelium (OE) has a unique capacity for continuous neurogenesis, extending axons to the olfactory bulb with the assistance of olfactory ensheathing cells (OECs). The OE and OECs have been believed to develop solely from the olfactory placode, while the neural crest (NC) cells have been believed to contribute only the underlying structural elements of the olfactory system. In order to further elucidate the role of NC cells in olfactory development, we examined the olfactory system in the transgenic mice Wnt1-Cre/Floxed-EGFP and P0-Cre/Floxed-EGFP, in which migrating NC cells and its descendents permanently express GFP, and conducted transposon-mediated cell lineage tracing studies in chick embryos.</p> <p>Results</p> <p>Examination of these transgenic mice revealed GFP-positive cells in the OE, demonstrating that NC-derived cells give rise to OE cells with morphologic and antigenic properties identical to placode-derived cells. OECs were also positive for GFP, confirming their NC origin. Cell lineage tracing studies performed in chick embryos confirmed the migration of NC cells into the OE. Furthermore, spheres cultured from the dissociated cells of the olfactory mucosa demonstrated self-renewal and trilineage differentiation capacities (neurons, glial cells, and myofibroblasts), demonstrating the presence of NC progenitors in the olfactory mucosa.</p> <p>Conclusion</p> <p>Our data demonstrates that the NC plays a larger role in the development of the olfactory system than previously believed, and suggests that NC-derived cells may in part be responsible for the remarkable capacity of the OE for neurogenesis and regeneration.</p