[Incidence and case fatality rates of cardiovascular diseases in urban and rural community-dwelling populations in eastern, central and western regions of China].

Objective: To evaluate the incidence and case fatality rate of cardiovascular disease (CVD) among populations in urban and rural communities in eastern, central and western regions of China. Methods: The present study was based on the data of the Prospective Urban and Rural Epidemiology (PURE)-China cohort, which enrolled participants who had at least one follow-up visit and complete information on age and sex. Information on baseline demographics, cardiovascular risk factors, and prevention and treatment for CVD were collected. CVD and mortality events were documented using the standardized case report form of the PURE Global Study to assess the incidence and case fatality rate of CVD among populations in urban and rural communities in eastern, central and western China. Results: This study included a total of 47 262 community-dwelling participants (age: (51.1±9.6) years; female, n=27 529, 58.2%) from 115 urban and rural communities in 12 provinces across the eastern, central, and western regions of China. Over a follow-up period of 11.9 (9.5, 12.6) years, 2 686 deaths and 5 873 cardiovascular events were documented. The incidence of CVD was 11.90 (95%CI: 11.60-12.21)/1 000 person-years. A significant difference in CVD incidence was observed across regions (Ptrend<0.001), which was highest in the western provinces (13.99 (95%CI: 13.33-14.65)/1 000 person-years), intermediate in the eastern provinces (11.92 (95%CI: 11.52-12.33)/1 000 person-years), and lowest in the central provinces (8.87 (95%CI: 8.25-9.50)/1 000 person-years). The 1-year case fatality rate of CVD demonstrated an increasing trend from eastern to western regions (eastern: 10.20% (95%CI: 6.95-14.73); central: 13.50% (95%CI: 9.90-18.14); western: 18.62% (95%CI: 14.95-22.94); Ptrend<0.001). Moreover, the incidence of major CVD was consistently higher in rural areas compared with urban areas across eastern (P<0.001), central (P=0.01) and western (P<0.001)_regions, respectively. The 1-year case fatality rate in rural areas was also significantly higher compared with that in urban areas in both eastern (P<0.001) and western regions (P=0.02). Conclusions: The incidence and case fatality rate of CVD were high among middle-aged population in China, especially those in western regions with low socioeconomic levels and in rural areas.

Phylogenetic relationships and evolution in Chrysosplenium (Saxifragaceae) based on matK sequence data.

Chrysosplenium (Saxifragaceae) consists of 57 species widely distributed in temperate and arctic regions of the Northern Hemisphere, with two species restricted to the southern part of South America. Species relationships within the genus are highly problematic. The genus has traditionally been divided into two groups, sometimes recognized as sections (Oppositifolia and Alternifolia), based on leaf arrangement, or, alternatively, into 17 series. Based on morphological features, Hara suggested that the genus originated in South America and then subsequently migrated to the Northern Hemisphere. We conducted phylogenetic analyses of DNA sequences of the chloroplast gene matK for species of Chrysosplenium to elucidate relationships, test Hara's biogeographic hypothesis for the genus, and examine chromosomal and gynoecial diversification. These analyses revealed that both sections Oppositifolia and Alternifolia are monophyletic and form two large sister clades. Hence, leaf arrangement is a good indicator of relationships within this genus. Hara's series Pilosa and Macrostemon are each also monophyletic; however, series Oppositifolia, Alternifolia, and Nepalensia are clearly not monophyletic. MacClade reconstructions suggest that the genus arose in Eastern Asia, rather than in South America, with several independent migration events from Asia to the New World. In one well-defined subclade, species from eastern and western North America form a discrete clade, with Old World species as their sister group, suggesting that the eastern and western North American taxa diverged following migration to that continent. The South American species forms a clade with species from eastern Asia; this disjunction may be the result of ancient long-distance dispersal. Character mapping demonstrated that gynoecial diversification is dynamic, with reversals from inferior to half-inferior ovaries, as well as to ovaries that appear superior. Chromosomal evolution also appears to be labile with several independent origins of n = 12 (from an original number of n = 11) and multiple episodes of aneuploidy.

Timing the eastern Asian-eastern North American floristic disjunction: molecular clock corroborates paleontological estimates.

Sequence data of the chloroplast gene rbcL were used to estimate the time of the well-known eastern Asian-eastern North American floristic disjunction. Sequence divergence of rbcL was examined for 22 species of 11 genera (Campsis, Caulophyllum, Cornus, Decumaria, Liriodendron, Menispermum, Mitchella, Pachysandra, Penthorum, Podophyllum, and Phryma) representing a diverse array of flowering plants occurring disjunctly in eastern Asia and eastern North America. Divergence times of putative disjunct species pairs were estimated from synonymous substitutions, using rbcL molecular clocks calibrated for Cornus. Relative rate tests were performed to assess rate constancy of rbcL evolution among lineages. Corrections of estimates of divergence times for each species pair were made based on rate differences of rbcL between Cornus and other species pairs. Results of these analyses indicate that the time of divergence of species pairs examined ranges from 12.56 +/- 4.30 million years to recent (<0.31 million years), with most within the last 10 million years (in the late Miocene and Pliocene). These results suggest that the isolation of most morphologically similar disjunct species in eastern Asia and eastern North America occurred during the global climatic cooling period that took place throughout the late Tertiary and Quaternary. This estimate is closely correlated with paleontological evidence and in agreement with the hypothesis that considers the eastern Asian-eastern North American floristic disjunction to be the result of the range restriction of a once more or less continuously distributed mixed mesophytic forest of the Northern Hemisphere that occurred during the late Tertiary and Quaternary. This implies that in most taxa the disjunction may have resulted from vicariance events. However, long-distance dispersal may explain the disjunct distribution of taxa with low divergence, such as Menispermum.

Assessing hybridization in natural populations of Penstemon (Scrophulariaceae) using hypervariable intersimple sequence repeat (ISSR) bands.

Inferences regarding hybridization rely on genetic markers to differentiate parental taxa from one another. Intersimple sequence repeat (ISSR) markers are based on single-primer PCR reactions where the primer sequence is derived from di- and trinucleotide repeats. These markers have successfully been used to assay genetic variability among cultivated plants, but have not yet been tested in natural populations. We used genetic markers generated from eight ISSR primers to examine patterns of hybridization and purported examples of hybrid speciation in Penstemon (Scrophulariaceae) in a hybrid complex involving P. centranthifolius, P. grinnellii, P. spectabilis and P. clevelandii. This hybrid complex has previously been studied using three molecular data sets (allozymes, and restriction-site variation of nuclear rDNA and chloroplast DNA). These studies revealed patterns of introgression involving P. centranthifolius, but were unsuccessful in determining whether gene flow occurs among the other species, and support for hypotheses of diploid hybrid speciation was also lacking. In this study, we were able to fingerprint each DNA accession sampled with one to three ISSR primers and most accessions could be identified with a single primer. We found population- and species-specific markers for each taxon surveyed. Our results: (i) do not support the hybrid origin of P. spectabilis; (ii) do support the hypothesis that P. clevelandii is a diploid hybrid species derived from P. centranthifolius and P. spectabilis; and (iii) demonstrate that pollen-mediated gene flow via hummingbird vectors is prevalent in the hybrid complex.

Diploid hybrid speciation in Penstemon (Scrophulariaceae).

Hybrid speciation has played a significant role in the evolution of angiosperms at the polyploid level. However, relatively little is known about the importance of hybrid speciation at the diploid level. Two species of Penstemon have been proposed as diploid hybrid derivatives based on morphological data, artificial crossing studies, and pollinator behavior observations: Penstemon spectabilis (derived from hybridization between Penstemon centranthifolius and Penstemon grinnellii) and Penstemon clevelandii (derived from hybridization between P. centranthifolius and P. spectabilis). Previous studies were inconclusive regarding the purported hybrid nature of these species because of a lack of molecular markers sufficient to differentiate the parental taxa in the hybrid complex. We developed hypervariable nuclear markers using inter-simple sequence repeat banding patterns to test these classic hypotheses of diploid hybrid speciation in Penstemon. Each species in the hybrid complex was genetically distinct, separated by 10-42 species-specific inter-simple sequence repeat markers. Our data do not support the hybrid origin of P. spectabilis but clearly support the diploid hybrid origin of P. clevelandii. Our results further suggest that the primary reason diploid hybrid speciation is so difficult to detect is the lack of molecular markers able to differentiate parental taxa from one another, particularly with recently diverged species.

The eastern Asian and eastern and western North American floristic disjunction: congruent phylogenetic patterns in seven diverse genera.

One of the most remarkable examples of intercontinental disjunction of the North Temperate Flora involves eastern Asia and eastern and western North America. Although there has been considerable interest in this phytogeographic pattern for over 150 years (e.g., Gray, 1859; Li, 1952; Graham, 1972; Boufford and Spongberg, 1983; Wu, 1983; Tiffney, 1985a, 1985b), relationships among taxa displaying the disjunction remain obscure. Understanding phylogenetic relationships is, however, a prerequisite for historical biogeographic analyses of this distributional pattern. To understand better the relationships of taxa displaying this intercontinental disjunction, phylogenetic analyses were conducted using a variety of DNA data sets for species of four genera (Cornus, Boykinia, Tiarella, and Trautvetteria) that occur in eastern Asia, eastern North America, and western North America. An area cladogram was constructed for each of the four genera, all of which show a similar pattern of relationship: the eastern Asian species are sister to all North American species. An identical phylogenetic pattern is also found in three other taxa exhibiting this disjunction (Aralia sect. Aralia, Calycanthus, and Adiantum pedatum). The congruent phylogenetic pattern found in these seven diverse genera raises the possibility of a common origin of the eastern Asia, eastern and western North America disjunction. The data are in agreement with the long-standing hypothesis that this well-known floristic disjunction represents the fragmentation of a once continuous Mixed Mesophytic forest community and suggest that the disjunction may have involved only two major vicariance events: an initial split between Eurasia and North America, followed by the isolation of floras between eastern and western North America. However, congruence between phylogenies and geographic distributions does not necessarily indicate an identical phytogeographic history. Taxa exhibiting the same phylogenetic pattern may have originated at different geological times. Analysis of divergence times using the molecular clock indicates that species of Cornus, Boykinia, and Calycanthus may have diverged at different geological times, suggesting that the floristic disjunction involving eastern Asia and North America may not be simple; it may have involved multiple historical events at very different geological times in different genera.