Introgression between highly divergent fungal sister species.

To understand how species evolve and adapt to changing environments, it is important to study gene flow and introgression due to their influence on speciation and radiation events. Here, we apply a novel experimental system for investigating these mechanisms using natural populations. The system is based on two fungal sister species with morphological and ecological similarities occurring in overlapping habitats. We examined introgression between these species by conducting whole genome sequencing of individuals from populations in North America and Europe. We assessed genome-wide nucleotide divergence and performed crossing experiments to study reproductive barriers. We further used ABBA-BABA statistics together with a network analysis to investigate introgression, and conducted demographic modelling to gain insight into divergence times and introgression events. The results revealed that the species are highly divergent and incompatible in vitro. Despite this, small regions of introgression were scattered throughout the genomes and one introgression event likely involves a ghost population (extant or extinct). This study demonstrates that introgression can be found among divergent species and that population histories can be studied without collections of all the populations involved. Moreover, the experimental system is shown to be a useful tool for research on reproductive isolation in natural populations.

Large-scale fungal strain sequencing unravels the molecular diversity in mating loci maintained by long-term balancing selection.

Balancing selection, an evolutionary force that retains genetic diversity, has been detected in multiple genes and organisms, such as the sexual mating loci in fungi. However, to quantify the strength of balancing selection and define the mating-related genes require a large number of strains. In tetrapolar basidiomycete fungi, sexual type is determined by two unlinked loci, MATA and MATB. Genes in both loci define mating type identity, control successful mating and completion of the life cycle. These loci are usually highly diverse. Previous studies have speculated, based on culture crosses, that species of the non-model genus Trichaptum (Hymenochaetales, Basidiomycota) possess a tetrapolar mating system, with multiple alleles. Here, we sequenced a hundred and eighty strains of three Trichaptum species. We characterized the chromosomal location of MATA and MATB, the molecular structure of MAT regions and their allelic richness. The sequencing effort was sufficient to molecularly characterize multiple MAT alleles segregating before the speciation event of Trichaptum species. Analyses suggested that long-term balancing selection has generated trans-species polymorphisms. Mating sequences were classified in different allelic classes based on an amino acid identity (AAI) threshold supported by phylogenetics. 17,550 mating types were predicted based on the allelic classes. In vitro crosses allowed us to support the degree of allelic divergence needed for successful mating. Even with the high amount of divergence, key amino acids in functional domains are conserved. We conclude that the genetic diversity of mating loci in Trichaptum is due to long-term balancing selection, with limited recombination and duplication activity. The large number of sequenced strains highlighted the importance of sequencing multiple individuals from different species to detect the mating-related genes, the mechanisms generating diversity and the evolutionary forces maintaining them.

Multicenter study on the treatment of cerebralcare granule for patients with mild and moderate vascular cognitive impairment / 中华行为医学与脑科学杂志

Objective To explore the improvement of cognitive impairment in patients with mild and moderate vascular cognitive impairment( VCI) treated with cerebralcare granule ( CG) and basic treat-ment.Methods From October in 2014 to December in 2016 year,143 cases of VCI patients were admitted from six hospitals in some areas of Hebei Province as the research objects,and divided into CG treatment group (experimental group,n=98) and conventional treatment group (control group,n=66).Three months and six months after treatment,the score of mental state examination ( MMSE) ,the Montreal cognitive assess-ment scale ( MoCA) and the daily living capacity scale( ADL) of the two groups were compared after 3 and 6 moths of treatment.Results ①The total score of MMSE in the experimental group was higher than that of the control group for six months after treatment, and the difference was statistically significant ( ( 23. 76 ± 4.02) vs (21.52±5.13),P<0.05).②Six months after treatment,the total score of MoCA ((21.06±4.66) vs (18.32±5.20)) and visual spatial/executive function((3.05±1.37) vs (2.42±1.66)),calculation force ((2.24±0.84) vs (1.83±1.05)) and orientation ability((5.20±1.12) vs (4.06±1.35)) scores in the ex-perimental group were significantly higher than those in the control group (P<0.05) .③Six months after treat-ment,the ADL score in the experimental group was lower than that before treatment,and the difference was statistically significant((24.96±8.74) vs (29.20±11.55),P<0.05);while there was no significant difference in the ADL score between the experimental group and the control group after 6 months (P>0.05).Conclusion CG can improve cognitive function in mild to moderate VCI patients,mainly in visual space/execution func-tion,calculation ability and orientation ability,and with the extension of treatment time,the curative effect is more obvious.