Transcriptome sequencing in an ecologically important tree species: assembly, annotation, and marker discovery

<p>Abstract</p> <p>Background</p> <p>Massively parallel sequencing of cDNA is now an efficient route for generating enormous sequence collections that represent expressed genes. This approach provides a valuable starting point for characterizing functional genetic variation in non-model organisms, especially where whole genome sequencing efforts are currently cost and time prohibitive. The large and complex genomes of pines (<it>Pinus </it>spp.) have hindered the development of genomic resources, despite the ecological and economical importance of the group. While most genomic studies have focused on a single species (<it>P. taeda</it>), genomic level resources for other pines are insufficiently developed to facilitate ecological genomic research. Lodgepole pine (<it>P. contorta</it>) is an ecologically important foundation species of montane forest ecosystems and exhibits substantial adaptive variation across its range in western North America. Here we describe a sequencing study of expressed genes from <it>P. contorta</it>, including their assembly and annotation, and their potential for molecular marker development to support population and association genetic studies.</p> <p>Results</p> <p>We obtained 586,732 sequencing reads from a 454 GS XLR70 Titanium pyrosequencer (mean length: 306 base pairs). A combination of reference-based and <it>de novo </it>assemblies yielded 63,657 contigs, with 239,793 reads remaining as singletons. Based on sequence similarity with known proteins, these sequences represent approximately 17,000 unique genes, many of which are well covered by contig sequences. This sequence collection also included a surprisingly large number of retrotransposon sequences, suggesting that they are highly transcriptionally active in the tissues we sampled. We located and characterized thousands of simple sequence repeats and single nucleotide polymorphisms as potential molecular markers in our assembled and annotated sequences. High quality PCR primers were designed for a substantial number of the SSR loci, and a large number of these were amplified successfully in initial screening.</p> <p>Conclusions</p> <p>This sequence collection represents a major genomic resource for <it>P. contorta</it>, and the large number of genetic markers characterized should contribute to future research in this and other pines. Our results illustrate the utility of next generation sequencing as a basis for marker development and population genomics in non-model species.</p

A common root for coevolution and substitution rate variability in protein sequence evolution

We introduce a simple model that describes the average occurrence of point variations in a generic protein sequence. This model is based on the idea that mutations are more likely to be fixed at sites in contact with others that have mutated in the recent past. Therefore, we extend the usual assumptions made in protein coevolution by introducing a time dumping on the effect of a substitution on its surrounding and makes correlated substitutions happen in avalanches localized in space and time. The model correctly predicts the average correlation of substitutions as a function of their distance along the sequence. At the same time, it predicts an among-site distribution of the number of substitutions per site highly compatible with a negative binomial, consistently with experimental data. The promising outcomes achieved with this model encourage the application of the same ideas in the field of pairwise and multiple sequence alignment

Inhaled corticosteroids for asthma: are they all the same?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72783/1/j.1365-2710.2008.00970.x.pd

Bringing Molecules Back into Molecular Evolution

Much molecular-evolution research is concerned with sequence analysis. Yet these sequences represent real, three-dimensional molecules with complex structure and function. Here I highlight a growing trend in the field to incorporate molecular structure and function into computational molecular-evolution work. I consider three focus areas: reconstruction and analysis of past evolutionary events, such as phylogenetic inference or methods to infer selection pressures; development of toy models and simulations to identify fundamental principles of molecular evolution; and atom-level, highly realistic computational modeling of molecular structure and function aimed at making predictions about possible future evolutionary events

Toward a General Model for the Evolutionary Dynamics of Gene Duplicates

Gene duplication is an important process in the functional divergence of genes and genomes. Several processes have been described that lead to duplicate gene retention over different timescales after both smaller-scale events and whole-genome duplication, including neofunctionalization, subfunctionalization, and dosage balance. Two common modes of duplicate gene loss include nonfunctionalization and loss due to population dynamics (failed fixation). Previous work has characterized expectations of duplicate gene retention under the neofunctionalization and subfunctionalization models. Here, that work is extended to dosage balance using simulations. A general model for duplicate gene loss/retention is then presented that is capable of fitting expectations under the different models, is defined at t = 0, and decays to an orthologous asymptotic rate rather than zero, based upon a modified Weibull hazard function. The model in a maximum likelihood framework shows the property of identifiability, recovering the evolutionary mechanism and parameters of simulation. This model is also capable of recovering the evolutionary mechanism of simulation from data generated using an unrelated network population genetic model. Lastly, the general model is applied as part of a mixture model to recent gene duplicates from the Oikopleura dioica genome, suggesting that neofunctionalization may be an important process leading to duplicate gene retention in that organism

Orthodontic Treatment of a Congenitally Missing Maxillary Lateral Incisor

Clinicians agree that, regardless of gender or race, tooth agenesis has become more prominent in recent societies. The congenital absence of one or more maxillary lateral incisors poses a challenge to effective treatment planning for the restorative dentist. However, the one-sided orthodontic approach of just moving canines mesially to eliminate restorative procedures leads to compromise. Adult patients presenting with malocclusions, missing lateral incisors, or anterior crowding but who fail to get proper orthodontic treatment, requesting instead esthetic solutions that do not establish a stable occlusion, proper alignment, and proper axial inclination of the teeth will have compromised esthetic and periodontal results. An evaluation of anterior smile esthetics must include both static and dynamic evaluations of frontal and profile views to optimize both dental and facial appearance. This article presents how orthodontics is combined with other specialties in treating a congenitally missing lateral incisor. One case is used to illustrate how orthodontic treatment is progressed in collaboration with other specialists

Polymorphisms in eruption sequence of permanent teeth in American children

This study provides basic descriptive data on the frequency of pairwise eruption sequences ascertained in cross-sectional examination of 6,000 black and white American children in the Ten State Nutritional Survey of 1968–1970. All sex and race groups share a distinct pattern of sequence polymorphisms in terms of location, number, and level. Teeth in eruption phase I (M1, I1, I2) rarely reverse in sequence with those in phase II (C, P1, P2, and M2). Five sequences have variants that appear at ≥20% in all groups, with M 1 I 1 vs. I 1 M 1 approaching maximum polymorphic values of 50%/50%. The traditional notation for eruption sequences can be modified to reflect these important variants, giving the sequence M1 I1 I2 [P1 C P2] M2 for the maxilla and [M1 I1] I2 [C P1] [P2 M2] for the mandible. The location of major polymorphisms is explicable by close timing of teeth within phase I and, separately, teeth within phase II eruption. However, strong integration of development of physically adjacent teeth apparently acts to reduce substantially the number of sequence reversals. The Ten State Survey data provide a sound descriptive basis for two populations, yet precise comparative data are available for few other human groups or primate species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37642/1/1330740303_ftp.pd

Celiprolol double-peak occurrence and gastric motility: Nonlinear mixed effects modeling of bioavailability data obtained in dogs

Investigation of the underlying mechanism leading to inter- and intrasubject variations in the plasma concentration-time profiles of drugs (1) can considerably benefit rational drug therapy. The significant effect of gastric emptying on the rate and extent of celiprolol absorption and its role with respect to double-peak formation was demonstrated in the present study. In four dogs racemic celiprolol was dosed perorally in a crossover design during four different phases of the fasted-state gastric cycle and gastric motility was recorded simultaneously using a manometric measurement system. Intravenous doses were also given to obtain disposition and bioavailability parameters. The blood samples were assayed by a stereoselective HPLC method (2). The time to onset of the active phase of the gastric cycle showed an excellent correlation with the time to celiprolol peak concentration. Furthermore, bioavailability was increased when celiprolol was administered during the active phase. Double peaks were observed when the first active phase was relatively short, suggesting that a portion of the drug remained in the stomach until the next active phase. Population pharmacokinetic modeling of the data with a two-compartment open model with two lag times incorporating the motility data confirmed the effect of time to gastric empyting on the variability of the oral pharmacokinetics of celiprolol. The fasted-state motility phases determine the rate and extent of celiprolol absorption and influence the occurrence of double peaks. Peak plasma levels of celiprolol exhibit less variability if lag times, and therefore gastric emptying times, are taken into consideration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45049/1/10928_2006_Article_BF02354285.pd