Alterations in Resting-State MR Functional Connectivity of the Central Autonomic Network in Multiple System Atrophy and Relationship with Disease Severity.

BACKGROUND: The central autonomic network (CAN) plays a critical role in the body's sympathetic and parasympathetic control. However, functional connectivity (FC) changes of the CAN in patients with multiple system atrophy (MSA) remain unknown. PURPOSE: To investigate FC alterations of CAN in MSA patients. STUDY TYPE: Prospective. POPULATION: Eighty-two subjects (47 patients with MSA [44.7% female, 60.5 ± 6.9 years], 35 age- and sex-matched healthy controls [HC] [57.1% female, 62.5 ± 6.6 years]). FIELD STRENGTH/SEQUENCE: 3-T, resting-state functional magnetic resonance imaging (rs-fMRI) using gradient echo-planar imaging (EPI), T1-weighted three-dimensional magnetization-prepared rapid gradient echo (3D MPRAGE) structural MRI. ASSESSMENT: FC alterations were explored by using core modulatory regions of CAN as seeds, including midcingulate cortex, insula, amygdala, and ventromedial prefrontal cortex. Bartlett factor score (BFS) derived from a factor analysis of clinical assessments on disease severity was used as a grouping factor for moderate MSA (mMSA: BFS < 0) and severe MSA (sMSA: BFS > 0). STATISTICAL TESTS: For FC analysis, the one-way ANCOVA with cluster-level family-wise error correction (statistical significance level of P < 0.025), and post hoc t-testing with Bonferroni correction or Tamhane's T2 correction (statistical significance level of adjusted-P < 0.05) were adopted. Correlation was assessed using Pearson correlation or Spearman correlation (statistical significance level of P < 0.05). RESULTS: Compared with HC, patients with MSA exhibited significant FC aberrances between the CAN and brain areas of sensorimotor control, limbic network, putamen, and cerebellum. For MSA patients, most FC alterations of CAN, especially concerning FC between the right anterior insula and right primary sensorimotor cortices, were found to be significantly correlated with disease severity. FC changes were found to be more significant in sMSA group than in mMSA group when compared with HCs. DATA CONCLUSION: MSA shows widespread FC changes of CAN, suggesting that abnormal functional integration of CAN may be involved in disease pathogenesis of MSA. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 3.

When tropical and subtropical congeners met: Multiple ancient hybridization events within Eriobotrya in the Yunnan-Guizhou Plateau, a tropical-subtropical transition area in China.

Global climate changes during the Miocene may have created ample opportunities for hybridization between members of tropical and subtropical biomes at the boundary between these zones. Yet, very few studies have explored this possibility. The Yunnan-Guizhou Plateau (YGP) in Southwest China is a biodiversity hotspot for vascular plants, located in a transitional area between the floristic regions of tropical Southeast Asia and subtropical East Asia. The genus Eriobotrya (Rosaceae) comprises both tropical and subtropical taxa, with 12 species recorded in the YGP, making it a suitable basis for testing the hypothesis of between-biome hybridization. Therefore, we surveyed the evolutionary history of Eriobotrya by examining three chloroplast regions and five nuclear genes for 817 individuals (47 populations) of 23 Eriobotrya species (including 19 populations of 12 species in the YGP), plus genome re-sequencing of 33 representative samples. We concluded that: (1) phylogenetic positions for 16 species exhibited strong cytonuclear conflicts, most probably due to ancient hybridization; (2) the YGP is a hotspot for hybridization, with 11 species showing clear evidence of chloroplast capture; and (3) Eriobotrya probably originated in tropical Asia during the Eocene. From the Miocene onwards, the intensification of the Eastern Asia monsoon and global cooling may have shifted the tropical-subtropical boundary and caused secondary contact between species, thus providing ample opportunity for hybridization and diversification of Eriobotrya, especially in the YGP. Our study highlights the significant role that paleoclimate changes probably played in driving hybridization and generating rich species diversity in climate transition zones.

Development and characterization of genomic microsatellite markers in the tree species, Rhodoleia championii, R. parvipetala, and R. forrestii (Hamamelidaceae).

Rhodoleia Champion ex Hooker is one of the most primitive relict genera of Hamamelidaceae, a key family exploited to understand the origin and early evolution of flowering plants. Genomic simple sequence repeats (SSRs) were developed for R. championii to perform genetic diversity, phylogeographical structure or even systematic evolution studies of the genus. Among the 278,743 contigs (105,758,242 bps) de novo assembled from the low-coverage whole genome sequencing of R. championii, a total of 9106 SSRs were detected in 8370 contigs, and SSR primer pairs were successfully designed for 6677 SSRs. Among the 110 selected primer pairs, 41 were amplified successfully in the preliminary test of SSR screening. Further amplification of these 41 primer pairs across the 122 individuals collected from six populations of the three Rhodoleia species showed that 32 and 40 SSR markers can be amplified in Vietnam and Jinping populations of R. parvipetala, 41, 33, and 41 SSR markers in Boluo, Hongkong and Xinyi populations of R. championii, 25 SSR markers in Fugong population of R. forrestii, and 20 SSR markers demonstrated to be polymorphic across the three species. Genetic analysis for these 20 polymorphic SSRs showed that Allele number (A) ranged from four to 13 and polymorphic information content (PIC) ranged from 0.479 to 0.876 across the three species. At the population level, observed heterozygosity (HO) ranged from 0.000 to 1.000, and expected heterozygosity (HE) ranged from 0.091 to 0.851. In the present study, we provided the first whole-genome sequencing database for the species R. championii, identified ample SSR loci with designed primers, and revealed that 20 of the 110 selected SSRs were polymorphic across three Rhodoleia species. These provide valuable resources for future studies on genetic study, species delimitation, phylogeography, and conservation of this genus.

Identification and development of microsatellite (SSRs) makers of Exbucklandia (HAMAMELIDACEAE) by high-throughput sequencing.

Hamamelidaceae (Saxifragales, previously Rosales) comprises approximately six subfamily, 30 genera and 140 species, most of which are Tertiary relicts. Exbucklandia is the only genus of the subfamily Exbucklandioideae, Hamelidaceae, containing only 2-4 species. Of them, the species E. longipetala H. T. Chang is endemic to China and listed as endangered in The Biodiversity Red List of China: Higher Plant, yet some taxonomists put forward that E. longipetala should be merged into E. tonkinensis (Lecomte) H. T. Chang. Currently, there was nearly no phylogeographic studies on this genus possibly due to the deficiency of efficient molecular markers. In this study, we sequenced the genome of E. tonkinensis based on high throughput sequencing technology, and obtained approximately 6 G raw data, which was further de novo assembled into 303,481 contigs. Based on them, 15,326 SSRs were identified from 13,596 contigs, and primers were successfully designed for 10,660 SSRs. A total of 139 paired primers were synthesized, 106 of them were successfully amplified in six Exbucklandia individuals with expected PCR product size, and 24 demonstrated to be polymorphic among three Exbucklandia populations. Accordingly, the expected and observed heterozygosity were between 0.097-0.717 and 0.098-0.583. Based on these efforts, future researches on genetic diversity and population structure of Exbucklandia can be performed to understand its phylogenetic origins and phylogeographic pattern.

Pronounced genetic differentiation in Fokienia hodginsii revealed by simple sequence repeat markers.

Fokienia hodginsii is a Tertiary relict conifer of the monotypic genus Fokienia (Cupressaceae s.l.). Currently, the species is distributed in southern China, northern Vietnam, and northern Laos and listed as a "near threatened" species by the IUCN. In this study, a total of 427 individuals of F. hodginsii were sampled from China and Vietnam to characterize its genetic diversity and population differentiation. Based on the profiles of 12 simple sequence repeat (SSR) markers, we observed a high level of genetic diversity in F. hodginsii at the species level (H e =0.635), albeit slightly lower than that of its sister species Chamaecyparis obtusa. Signals of bottleneck events were detected in the populations GXDMS, GXHJ, V-PXB, and V-HB, probably due to Pleistocene glaciations or overexploitation in recent years. Pronounced genetic differentiation (F st   = 0.157) was found in this species. The inbreeding index (F is  = 0.176 ± 0.024) indicated that F. hodginsii has a mixed mating system. Significant correlation was found between the pairwise genetic differentiation and geographic distance (r = 0.882, p = 0.01), suggesting that genetic differentiation among the populations follows the model of isolation by distance (IBD). STRUCTURE analysis and principal coordinate analysis revealed that these populations were divided into four groups: the western China group located mainly in the Yunnan-Guizhou Plateau, the central China group located mostly in the Luoxiao Mountains and Nanling Mountains, the eastern China group located in the Wuyi Mountains and the Vietnam group containing two populations in Vietnam. The different terrains and elevations of populations may be the most likely factors leading to the differentiation between the western China group and the central China group, while the geographic isolation caused by the lack of appropriate habitats may greatly contribute to the differentiation between the central China group and the eastern China group. Based on the results, some conservation suggestions for this species are provided, such as establishing seed orchards and multiple nature reserves.

Identification and development of microsatellite markers in Hamamelis mollis (Hamamelidaceae).

PREMISE OF THE STUDY: Hamamelis mollis (Hamamelidaceae) is a Tertiary relict species endemic to southern China. Polymorphic microsatellite markers were developed to reveal the genetic diversity of this species. METHODS AND RESULTS: The genome of H. mollis was sequenced and de novo assembled into 642,351 contigs. A total of 72,097 paired primers were successfully designed from 80,282 simple sequence repeat (SSR) markers identified in 63,419 contigs. PCR amplification showed that 96 of the 136 synthesized primers could be successfully amplified, and 22 demonstrated polymorphism. The mean number of alleles, levels of observed heterozygosity, and levels of expected heterozygosity were 4.602 ± 0.140, 0.632 ± 0.020, and 0.696 ± 0.010, respectively. The majority of the 96 primer pairs could be amplified in at least one other Hamamelidaceae species, including Distylium myricoides (60), Loropetalum chinense (39), Exbucklandia populnea (24), and E. tonkinensis (24). CONCLUSIONS: These microsatellite loci provide abundant genomic SSR markers to evaluate genetic diversity of this woody ornamental plant.

A global plastid phylogeny uncovers extensive cryptic speciation in the fern genus Hymenasplenium (Aspleniaceae).

The fern genus Hymenasplenium (Aspleniaceae) is one of the two genera in the family. It is generally recognized among modern pteridologists. However, its infrageneric relationships and species diversity have been unclear and controversial. The molecular studies so far have had small taxon and character sampling. In the present study, DNA sequences of six plastid markers of 158 accessions representing ca. 40 out of ca. 50 known species of Hymenasplenium, and 16 species of Asplenium were used to infer a phylogeny with maximum likelihood, Bayesian inference, and maximum parsimony approaches. Our major results include: (1) Hymenasplenium as currently defined is strongly supported as monophyletic; (2) three major clades representing early splits in Hymenasplenium are identified, with the Old World species being strongly supported as monophyletic; it is ambiguous if the New World species are monophyletic; (3) extensive cryptic speciation in the Old World is discovered demonstrating the complexity of evolution of the genus; and (4) six strongly or moderately supported subclades in the Old World clade are revealed, differing from one another in molecular, morphological, and geographical features.