Relationship Between Gene-Phenotype and Clinical Manifestations of Chromosomal Copy Number Variations Indicated by Non-Invasive Prenatal Testing

Objective:To analyze the clinical value of non-invasive prenatal testing(NIPT)in detecting chromosomal copy number variations(CNVs)and to explore the relationship between gene expression and clinical manifestations of chromosomal copy number variations.Methods:3551 naturally conceived singleton pregnant women who underwent NIPT were included in this study.The NIPT revealed abnormalities other than sex chromosome abnormalities and trisomy 13,18,and 21.Pregnant women with chromosome copy number variations underwent genetic counseling and prenatal ultrasound examination.Interventional prenatal diagnosis and chromosome microarray analysis(CMA)were performed.The clinical phenotypes and pregnancy outcomes of different prenatal diagnoses were analyzed.Additionally,a follow-up was conducted by telephone to track fetal development after birth,at six months,and one year post-birth.Results:A total of 53 cases among 3551 cases showed chromosomal copy number variation.Interventional prenatal diagnosis was performed in 36 cases:27 cases were negative and 8 were consistent with the NIPT test results.This indicates that NIPT’s positive predictive value(PPV)in CNVs is 22.22%.Conclusion:NIPT has certain clinical significance in screening chromosome copy number variations and is expected to become a routine screening for chromosomal microdeletions and microduplications.However,further interventional prenatal diagnosis is still needed to identify fetal CNVs.

Genome size evolution of the extant lycophytes and ferns

Ferns and lycophytes have remarkably large genomes.However,little is known about how their genome size evolved in fern lineages.To explore the origins and evolution of chromosome numbers and genome size in ferns,we used flow cytometry to measure the genomes of 240 species(255 samples)of extant ferns and lycophytes comprising 27 families and 72 genera,of which 228 species(242 samples)represent new reports.We analyzed correlations among genome size,spore size,chromosomal features,phylogeny,and habitat type preference within a phylogenetic framework.We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size.Using the phylogeny,we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference.We found that 2 C values had weak phylogenetic signal,whereas the base number of chromosomes(x)had a strong phylogenetic signal.Furthermore,our analyses revealed a positive correlation between genome size and chromosome traits,indicating that the base number of chromosomes(x),chromosome size,and polyploidization may be primary contributors to genome expansion in ferns and lycophytes.Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types;specifically,multinomial logistic regression indicated that species with larger 2 C values were more likely to be epiphytes.Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes,whereas transitions to other habitat types occurred as the major clades emerged.Shifts in habitat types appear be followed by periods of genomic stability.Based on these results,we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.

Karyotypes of nineteen species of Asteraceae in the Hengduan Mountains and adjacent regions

The Hengduan Mountains region is a biodiversity hotspot. In this study, we report the karyotypes of 19 species(21 populations) of Asteraceae from this region, 14 of which are reported for the first time. We also examined polyploidy in Asteraceae plants and summarized karyotype data in the literature for 69 congeneric taxa. In these genera, there were five different ploidy levels in the region, though the most dominant was diploid(73.08%). There is no direct evidence that ploidy level and karyotype asymmetry are associated with the distribution of recorded Asteraceae species from the Hengduan Mountains. This suggests that polyploidy(26.92%) may not play an important role in the evolutionary history of these plants, even though, among these genera, the ratio of paleopolyploidy was high(46.15%).

The Cytological Studies on Neglected and Underutilized Cucurbit Species with Special Reference to Chayote,an Under-Exploited Species

Cucurbitaceae family contains important economic and medical crops, they can be divided into two categories according to the worldwide consumption, use, and production. The Cucurbit Popular Crops (CuPoC) are comprised of cucumber, the Cucurbita group (pumpkin and squash), melon and watermelon. On the other hand, Neglected and Underutilized Cucurbit Species (NUCuS) group has been used as food sources, medicinal properties and elements in the elaboration of different types of items. The NUCuS is represented in this review work by bitter gourd, bottle gourd, chayote, ridge gourd, and snake gourd, which are recognized mainly in Asia. The center of origin of the majority of NUCuS was proposed to be in the Old World. In contrast, the origin of chayote or Sechiumedule (Jacq.) Sw. was suggested in the New World, precisely in Mesoamerican region based on linguistic uses and distribution of wild relatives. The environmental factors along with artificial selection, production systems and traditional knowledge have been influenced the evolutionary history of NUCuS, Infraspecific variation of chayote has been reported in Mexico over-described varietal groups. These descriptors were determined based on biochemical and morpho-structural traits;however, cytogenetic analyses are scarce. Specifically, chromosome and nuclear content analyses are important to support botanical groups, analyze artificial selection history, developing breeding and conservation programs. The present review paper discusses agronomic and evolutionary importance based on cytological evidence in NUCuS, mainly in the prominent chayote;with the perspective to prompt breeding, conservation, cytology, structural and functional genomics research for its sustainable utilization.