Genome sequences and population genomics reveal climatic adaptation and genomic divergence between two closely related sweetgum species.

Understanding the genetic basis of population divergence and adaptation is an important goal in population genetics and evolutionary biology. However, the relative roles of demographic history, gene flow, and/or selective regime in driving genomic divergence, climatic adaptation, and speciation in non-model tree species are not yet fully understood. To address this issue, we generated whole-genome resequencing data of Liquidambar formosana and L. acalycina, which are broadly sympatric but altitudinally segregated in the Tertiary relict forests of subtropical China. We integrated genomic and environmental data to investigate the demographic history, genomic divergence, and climatic adaptation of these two sister species. We inferred a scenario of allopatric species divergence during the late Miocene, followed by secondary contact during the Holocene. We identified multiple genomic islands of elevated divergence that mainly evolved through divergence hitchhiking and recombination rate variation, likely fostered by long-term refugial isolation and recent differential introgression in low-recombination genomic regions. We also found some candidate genes with divergent selection signatures potentially involved in climatic adaptation and reproductive isolation. Our results contribute to a better understanding of how late Tertiary/Quaternary climatic change influenced speciation, genomic divergence, climatic adaptation, and introgressive hybridization in East Asia's Tertiary relict flora. In addition, they should facilitate future evolutionary, conservation genomics, and molecular breeding studies in Liquidambar, a genus of important medicinal and ornamental values.

EST-SSR marker development based on transcriptome sequencing and genetic analyses of Phoebe bournei (Lauraceae).

High-throughput sequencing of the Phoebe bournei transcriptome was performed, and novel SSR markers were identified. A total of 73,518 nonredundant unigenes were assembled and annotated by sequence similarity searching in diverse public databases. A total of 40,853 SSRs were identified from 73,518 unigenes. Twenty-three pairs of polymorphic EST-SSR markers were selected from 98 markers and used for genetic analyses in 75 individuals from three P. bournei populations. The 23 pairs of markers could detect abundant genetic information from the samples (PIC = 0.769), and cross-species amplification was successfully performed in other related species. Three populations had high level of genetic diversity (He = 0.658 in average), of which the population YS from Jiangxi province had the most abundant genetic diversity (He = 0.722). The results of genetic structure analyses showed that the population YS from Jiangxi province had obvious genetic differences from the other two populations, and the genetic information of the population SX from Fujian province was related to that of the population LC from Guangdong province and the population YS. The transcriptomic resources and EST-SSR markers are valuable tools not only for the ecological conservation of P. bournei but also for phylogenetic studies.

[Clinical effect of percutaneous poking and tension band splint fixation for treatment of the calcaneal fracture].

OBJECTIVE: To observe the clinical efficacy of percutaneous poking tension band splint fixation for the treatment of calcaneal fractures. METHODS: From September 2007 to February 2009,40 patients with calcaneal fractures (42 feet) were treated by percutaneous poking reduction, including 28 feet of male and 14 feet of female, with an average age of 34.2 years ranging from 18 to 55 years. The course was from 2 hours to 7 days. All fractures were fresh and closed intra-articular calcaneal fractures. Patients were divided into two groups according to fixation methods, plaster fixation in 20 feet, tension band splint in 22 feet. Three aspects including the heel of the foot and ankle width of recovery, functional recovery, complications were compared according to the United States Orthopedic Foot and Ankle Society clinical score. RESULTS: These 40 patients were followed-up for 6 months to 2 years with an average of 9 months. The calcaneal width of the recovery, the functional recovery and force line of tension band splint group were all better than that of plaster fixation group (P < 0.05); There were no significant differences in pain between two groups (P > 0.05). Occurrence of complications in tension band splint group were lower than that of plaster fixation group (P < 0.05). CONCLUSION: Percutaneous poking tension band splint have advantage of stable calcaneal width and fewer complications on treatment of calcaneal fractures.