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Polyploidy after hybridization between species can lead to immediate post-zygotic isolation, causing saltatory origin of new species. Although the incidence of polyploidization in plants is high, it is thought that a new polyploid lineage can succeed only if it establishes a new ecological niche divergent from its progenitor lineages. We tested the hypothesis that Rhodiola integrifolia from North America is an allopolyploid produced by R. rhodantha and R. rosea and determined whether its survival can be explained by the niche divergence hypothesis. To this end, we sequenced two low-copy nuclear genes (ncpGS and rpb2) in a phylogenetic analysis of 42 Rhodiola species and tested for niche equivalency and similarity using Schoener's D as the index of niche overlap. Our phylogeny-based approach showed that R. integrifolia possesses alleles from both R. rhodantha and R. rosea. Dating analysis showed that the hybridization event that led to R. integrifolia occurred ca. 1.67 Mya and niche modeling analysis showed that at this time, both R. rosea and R. rhodantha may have been present in Beringia, providing the opportunity for the hybridization event. We also found that the niche of R. integrifolia differs from that of its progenitors in both niche breadth and optimum. Taken together, these results confirm the hybrid origin of R. integrifolia and support the niche divergence hypothesis for this tetraploid species. Our results underscore the fact that lineages with no current overlapping distribution could produce hybrid descendants in the past, when climate oscillations made their distributions overlap.

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OBJECTIVE@#To explore the association between the abnormal root morphology and bone metabolism or root development related gene polymorphism in patients with generalized aggressive periodontitis.@*METHODS@#In the study, 179 patients with generalized aggressive periodontitis were enrolled, with an average age of (27.23±5.19) years, male / female = 67/112. The average number of teeth remaining in the mouth was (26.80±1.84). Thirteen single nucleotide polymorphisms (SNPs) of nine genes which related to bone metabolism and root development were detected by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). Root abnormalities were identified using periapical radiographs. The abnormal root morphology included cone-rooted teeth, slender-root teeth, short-rooted teeth, curved-rooted teeth, syncretic-rooted molars, and molar root abnormalities. The number of teeth and incidence of abnormal root morphology in different genotypes of 13 SNPs were analyzed.@*RESULTS@#The constituent ratio of root with root abnormality in GAgP patients was 14.49%(695/4 798). The average number of teeth with abnormal root morphology in GAgP was (3.88±3.84). The average number of teeth with abnormal root morphology in CC, CT and TT genotypes in vitamin D receptor (VDR) rs2228570 was (4.66±4.10), (3.71±3.93) and (2.68±2.68). There was significant difference between TT genotype and CC genotype (t = 2.62, P =0.01). The average number of root morphological abnormalities in CC, CT and TT genotypes of Calcitotin Receptor (CTR) gene rs2283002 was (5.02±3.70), (3.43±3.95), and (3.05±3.12). The incidence of root morphological abnormalities in CC genotype was higher than that in the patients with CT and TT, and the difference was statistically significant(87.86% vs. 65.26% & 63.64%, P=0.006, adjusted OR =3.71, 95%CI: 1.45-9.50). There was no significant difference in the incidence of abnormal root morphology between CT and TT genotypes.@*CONCLUSION@#VDR rs2228570 and CTR rs2283002 may be associated with the occurrence of abnormal root morphology in patients with generalized aggressive periodontitis, which is worthy of further research.

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BACKGROUND: Quaternary climatic oscillations had tremendous effects on the current distribution of species. Here, we aim to elucidate the glacial history of Rhodiola crenulata, a perennial herb almost exclusively restricted to rock crevices on mountain peaks, and to test whether the nunatak or massif de refuge hypotheses could explain its distribution pattern. RESULTS: Six haplotypes and six ribotypes were detected in the cpDNA data set and the ITS data set, respectively. The divergence of R. crenulata and its closest relatives was dated have occurred ca. 0.65 Mya, during the Naynayxungla glaciation on the QTP. Mismatch distribution analysis suggested that the species experienced a range expansion around 0.31 Mya. Populations with high genetic and haplotype diversity were found on the QTP platform as well in the Hengduan Mountains. The ecological niche modeling results showed that there were suitable habitats on both the QTP platform and in the Hengduan Mountains during the LGM. CONCLUSION: Our results support a scenario that both nunataks and the massif de refuge hypotheses could explain the distribution of R. crenulata. We also confirmed that Quaternary climatic oscillations could promote plant speciation in some circumstances. This study adds to a growing body of evidence suggesting that the QTP plant lineages exhibited diverse reactions to the Quaternary climatic oscillations.

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How geological events and climate oscillations in the Pleistocene glaciation shaped the geographic distribution of genetic variation of species on the Qinghai-Tibetan Plateau (QTP) and its adjacent areas has been extensively studied. However, little studies have investigated whether closely related species in the same genus with similar physiological and life history traits responded similarly to the glacial climatic oscillations. If this is not the case, we would expect that the population histories of studied species were not driven by extrinsic environmental changes alone. Here we conducted a phylogeographic study of a succulent alpine plant Rhodiola fastigiata, using sequences from chloroplast genome and nrITS region, as well as ecological niche modeling. The results of R. fastigiata were compared to other congeneric species that have been studied, especially to R. alsia and R. crenulata. We found that for both markers, two geographic groups could be revealed, corresponding to the QTP plateau and the Hengduan Mountains, respectively, indicating isolated refugia in those two areas. The two groups diverged 1.23 Mya during the Pleistocene. We detected no significant population expansion by mismatch distribution analysis and Bayesian Skyline Plot. We found that even these similar species with similar physiological and life history traits have had different demographic histories in the Quaternary glacial periods. Our comparative phylogeographic study sheds new lights into phylogeographic research that extrinsic environmental changes are not the only factor that can drive population demography, and other factors, such as coevolved interactions between plants and their specialized pathogens, that probably played a role need to be examined with more case studies.

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A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

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Quaternary climatic oscillations have had tremendous effects on current distribution of species. Previous studies unraveled multiple microrefugia on the Qinghai-Tibetan Plateau (QTP) in two woody plants. Still we know little whether herbs growing in forests responded to climatic oscillations similarly. We herein conducted a phylogeographic study on Rhodiola sect. Trifida, an herbaceous group endemic to the QTP, which mainly growing on the forest floors, using plastid and ITS sequences as well as ecological niche modeling. The origin and divergence of major clades of sect. Trifida were in accordance with the last phase of the QTP uplifts. Mismatch distribution analysis indicated a range expansion dated to ca. 135 thousand years ago. A high frequency and an even distribution of private haplotypes in both plastid and ITS data sets throughout the distribution of sect. Trifida were detected. The ecological niche modeling results showed that there were suitable habitats on the QTP platform during the LGM. Our results found that multiple microrefugia existed on the QTP platform, supporting the hypothesis that species with similar geographic distribution and inhabiting the same community had similar responses to the Quaternary climatic oscillations. Furthermore, species delimitations in sect. Trifida need to be tested based on integrative evidence from morphological, ecological and genetic data.

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The roots and rhizomes of Rhodiola crenulata and R. rosea have been used worldwide as adaptogens for hundreds of years. However, rapid growth in demand has resulted in merchants using other species of Rhodiola as adulterants. Here, we surveyed 518 individuals representing 47 of the 55 species in the genus, including 253 R. crenulata individuals from 16 populations and 98 R. rosea individuals from 11 populations, to evaluate the utility of the internal transcribed spacer 2 (ITS2) barcode for identification of Rhodiola species. We detected six haplotypes in R. crenulata and only one haplotype in R. rosea. An obvious overlap between intra- and inter-specific distance was detected, and the authentication efficacy of ITS2, which was assessed by BLAST1, a nearest distance method, and a tree test, was much lower than in other groups. However, R. crenulata and R. rosea could be exactly identified. Analysis showed that the secondary structure of ITS2 differs in R. crenulata and its closest relatives. Our results demonstrated that both a mini barcode from ITS2 and the structure of ITS2 are effective markers for the identification of R. crenulata and R. rosea. This study represents the most comprehensive database of ITS2 barcodes in Rhodiola to date and will be useful in Rhodiola species identification.

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<p><b>OBJECTIVE</b>To evaluate the effect of thermal cycling on surface microstructure of different light-curing composite resins.</p><p><b>METHODS</b>A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from lateral to center to form cubic specimens. The lateral surfaces were abrased and polished before water storage and 40 000 thermal cycles (5/55 degrees celsius;). The mean surface roughness (Ra) were measured and compared before and after thermal cycling, and the changes of microstructure were observed under scanning electron microscope (SEM).</p><p><b>RESULTS</b>Significant decreases of Ra were observed in the composites, especially in Spectrum (from 0.164±0.024 µm to 0.140±0.017 µm, P<0.001) and Z250 (from 0.169±0.035 µm to 0.144±0.033 µm, P<0.001), whose Ra approximated that of P60 (0.121±0.028 µm) with smoothly polished surface. SEM revealed scratches and shallower pits on the surface of all the 5 resins, and fissures occurred on Z350 following the thermal cycling.</p><p><b>CONCLUSION</b>Water storage and thermal cycling may produce polishing effect on composite resins and cause fissures on nanofilled composite resins.</p>

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Objective To study radiation -induced lung damage after lung ionizing radiation and the temporal and spatial release of pro -inflammatory cytokines of interleukin -6(IL-6),interleukin-8(IL-8) and interleukin-10(IL-10)in the irradiated lung tissue.Methods BALB/C male mice weighted around 25 g were randomly divided into two groups:radiation group ( R) and control group ( C) ,with 30 mice in R group and10 mice in C group.The thorax of mice was irradiated by 6 MV X-ray with 25 Gy in 5 fractions.The mice were sac-rificed at 12 weeks post irradiation.Lung tissues were collected and embedded in paraffin .After HE staining,lung histopathological changes were detected by immunohistochemistry to detect IL -6,IL-8 and IL-10 expression in lung tissue.Results Immunohistochemistry results showed that the expressions of IL -6,IL-8 and IL-10 were mainly expressed in macrophages and inflammatory cells .The results showed that the expressions of IL -6 and IL-8 in R group were significantly higher than that in C group .IL-10 expression level was lower than C group.Conclusion After 12 weeks exposing to radiation ,cytokines of IL-6,IL-8 and IL-10 in lung tissue are associated with radiation -induced lung injury .

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<p><b>OBJECTIVE</b>To compare the surface roughness of nanofilled dental composite resin and microhybrid composite resins after curing and polishing.</p><p><b>METHODS</b>A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from the lateral to the medial layers to prepare 8 mm×8 mm×5 mm cubical specimens. The 4 lateral surfaces of each specimens were polished with abrasive disks (Super-Snap). Profilometer was used to test the mean surface roughness (Ra) after polishing.</p><p><b>RESULTS</b>P60 had the lowest Ra (0.125∓0.030 µm) followed by Z250 and Spectrum. The Ra of Z350 (0.205∓0.052 µm) was greater than that of the other 3 resins, and AP-X had the roughest surfaces. Under scanning electron microscope, the polished faces of P60 resin were characterized by minor, evenly distributed particles with fewer scratches; the polished faces of Z350 presented with scratches where defects of the filling material could be seen.</p><p><b>CONCLUSION</b>The nanofilled composite Z350 has smooth surface after polishing by abrasive disks, but its smoothness remains inferior to that of other micro-hybrid composite resins.</p>

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<p><b>OBJECTIVE</b>To reveal the relationship between the storage time of the bark of Magnolia officinalis and the content of phenols in it, and lay a theoretical foundation for the harvest, processing, management and storage.</p><p><b>METHOD</b>The contents of magnolol and honokoiol in 15 bark samples, collected from the main producing areas in China, were determined in the time of freshly harvest and 3 and 10 years after respectively by HPLC method.</p><p><b>RESULT</b>It showed that within a certain period of time, bark storage was favorable to conversion and accumulation of phenols, that the content of magnolol tended to increase from year 0 to year 3, then followed by slight decrease with years on account of volatilization of phenols, but was still higher when the bark was stored for 10 years than that that when the bark was freshly harvested, and the content of honokoiol still tended to increase when the bark had been stored for 10 years.</p><p><b>CONCLUSION</b>The phenols in bark of M. officinalis is quite stable and the bark can be stored for 10 years or longer.</p>

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