Jia-Xing Yue | Rice University (original) (raw)

Papers by Jia-Xing Yue

Genome Biology and Evolution

Cephalochordates, the sister group of tunicates plus vertebrates, have been called “living fossil... more Cephalochordates, the sister group of tunicates plus vertebrates, have been called “living fossils” due to their resemblance to fossil chordates from Cambrian strata. The genome of the cephalochordate Branchiostoma floridae shares remarkable synteny with vertebrates and is free from whole-genome duplication. We performed RNA sequencing from larvae and adults of Asymmetron lucayanum, a cephalochordate distantly related to B. floridae. Comparisons of about 430 orthologous gene groups among both cephalochordates and 10 vertebrates using an echinoderm, a hemichordate, and a mollusk as outgroups showed that cephalochordates are evolving more slowly than the slowest evolving vertebrate known (the elephant shark), with A. lucayanum evolving even more slowly than B. floridae. Against this background of slow evolution, some genes, notably several involved in innate immunity, stand out as evolving relatively quickly. This may be due to the lack of an adaptive immune system and the relatively high levels of bacteria in the inshore waters cephalochordates inhabit. Molecular dating analysis including several time constraints revealed a divergence time of ∼120 Ma for A. lucayanum and B. floridae. The divisions between cephalochordates and vertebrates, and that between chordates and the hemichordate plus echinoderm clade likely occurred before the Cambrian.

Gigascience, May 14, 2014

BACKGROUND: Horseshoe crabs are marine arthropods with a fossil record extending back approxim... more BACKGROUND:

Horseshoe crabs are marine arthropods with a fossil record extending back approximately 450 million years. They exhibit remarkable morphological stability over their long evolutionary history, retaining a number of ancestral arthropod traits, and are often cited as examples of "living fossils." As arthropods, they belong to the Ecdysozoa, an ancient super-phylum whose sequenced genomes (including insects and nematodes) have thus far shown more divergence from the ancestral pattern of eumetazoan genome organization than cnidarians, deuterostomes and lophotrochozoans. However, much of ecdysozoan diversity remains unrepresented in comparative genomic analyses.
RESULTS:

Here we apply a new strategy of combined de novo assembly and genetic mapping to examine the chromosome-scale genome organization of the Atlantic horseshoe crab, Limulus polyphemus. We constructed a genetic linkage map of this 2.7 Gbp genome by sequencing the nuclear DNA of 34 wild-collected, full-sibling embryos and their parents at a mean redundancy of 1.1x per sample. The map includes 84,307 sequence markers grouped into 1,876 distinct genetic intervals and 5,775 candidate conserved protein coding genes.
CONCLUSIONS:

Comparison with other metazoan genomes shows that the L. polyphemus genome preserves ancestral bilaterian linkage groups, and that a common ancestor of modern horseshoe crabs underwent one or more ancient whole genome duplications 300 million years ago, followed by extensive chromosome fusion. These results provide a counter-example to the often noted correlation between whole genome duplication and evolutionary radiations. The new, low-cost genetic mapping method for obtaining a chromosome-scale view of non-model organism genomes that we demonstrate here does not require laboratory culture, and is potentially applicable to a broad range of other species.

New Phytologist

Plant disease resistance genes (R genes) encode proteins that function to monitor signals indicat... more Plant disease resistance genes (R genes) encode proteins that function to monitor signals indicating pathogenic infection, thus playing a critical role in the plant's defense system. Although many studies have been performed to explore the functional details of these important genes, their origin and evolutionary history remain unclear.

BMC Plant Biology

Background: Rates of molecular evolution vary widely among species. While significant deviations ... more Background: Rates of molecular evolution vary widely among species. While significant deviations from molecular clock have been found in many taxa, effects of life histories on molecular evolution are not fully understood. In plants, annual/perennial life history traits have long been suspected to influence the evolutionary rates at the molecular level. To date, however, the number of genes investigated on this subject is limited and the conclusions are mixed. To evaluate the possible heterogeneity in evolutionary rates between annual and perennial plants at the genomic level, we investigated 85 nuclear housekeeping genes, 10 non-housekeeping families, and 34 chloroplast genes using the genomic data from model plants including Arabidopsis thaliana and Medicago truncatula for annuals and grape (Vitis vinifera) and popular (Populus trichocarpa) for perennials.

Molecular Genetics and …, Jan 1, 2008

Most disease resistance genes in plants encode NBS-LRR proteins. However, in woody species, littl... more Most disease resistance genes in plants encode NBS-LRR proteins. However, in woody species, little is known about the evolutionary history of these genes. Here, we identiWed 459 and 330 respective NBS-LRRs in grapevine and poplar genomes. We subsequently investigated protein motif composition, phylogenetic relationships and physical locations. We found signiWcant excesses of recent duplications in perennial species, compared with those of annuals, represented by rice and Arabidopsis. Consequently, we observed higher nucleotide identity among paralogs and a higher percentage of NBS-encoding genes positioned in numerous clusters in the grapevine and poplar. These results suggested that recent tandem duplication played a major role in NBS-encoding gene expansion in perennial species. These duplication events, together with a higher probability of recombination revealed in this study, could compensate for the longer generation time in woody perennial species e.g. duplication and recombination could serve to generate novel resistance speciWcities. In addition, we observed extensive species-speciWc expansion in TIR-NBS-encoding genes. Non-TIR-NBS-encoding genes were poly-or paraphyletic, i.e. genes from three or more plant species were nested in diVerent clades, suggesting diVerent evolutionary patterns between these two gene types.

Genome Biology and Evolution

Cephalochordates, the sister group of tunicates plus vertebrates, have been called “living fossil... more Cephalochordates, the sister group of tunicates plus vertebrates, have been called “living fossils” due to their resemblance to fossil chordates from Cambrian strata. The genome of the cephalochordate Branchiostoma floridae shares remarkable synteny with vertebrates and is free from whole-genome duplication. We performed RNA sequencing from larvae and adults of Asymmetron lucayanum, a cephalochordate distantly related to B. floridae. Comparisons of about 430 orthologous gene groups among both cephalochordates and 10 vertebrates using an echinoderm, a hemichordate, and a mollusk as outgroups showed that cephalochordates are evolving more slowly than the slowest evolving vertebrate known (the elephant shark), with A. lucayanum evolving even more slowly than B. floridae. Against this background of slow evolution, some genes, notably several involved in innate immunity, stand out as evolving relatively quickly. This may be due to the lack of an adaptive immune system and the relatively high levels of bacteria in the inshore waters cephalochordates inhabit. Molecular dating analysis including several time constraints revealed a divergence time of ∼120 Ma for A. lucayanum and B. floridae. The divisions between cephalochordates and vertebrates, and that between chordates and the hemichordate plus echinoderm clade likely occurred before the Cambrian.

Gigascience, May 14, 2014

BACKGROUND: Horseshoe crabs are marine arthropods with a fossil record extending back approxim... more BACKGROUND:

Horseshoe crabs are marine arthropods with a fossil record extending back approximately 450 million years. They exhibit remarkable morphological stability over their long evolutionary history, retaining a number of ancestral arthropod traits, and are often cited as examples of "living fossils." As arthropods, they belong to the Ecdysozoa, an ancient super-phylum whose sequenced genomes (including insects and nematodes) have thus far shown more divergence from the ancestral pattern of eumetazoan genome organization than cnidarians, deuterostomes and lophotrochozoans. However, much of ecdysozoan diversity remains unrepresented in comparative genomic analyses.
RESULTS:

Here we apply a new strategy of combined de novo assembly and genetic mapping to examine the chromosome-scale genome organization of the Atlantic horseshoe crab, Limulus polyphemus. We constructed a genetic linkage map of this 2.7 Gbp genome by sequencing the nuclear DNA of 34 wild-collected, full-sibling embryos and their parents at a mean redundancy of 1.1x per sample. The map includes 84,307 sequence markers grouped into 1,876 distinct genetic intervals and 5,775 candidate conserved protein coding genes.
CONCLUSIONS:

Comparison with other metazoan genomes shows that the L. polyphemus genome preserves ancestral bilaterian linkage groups, and that a common ancestor of modern horseshoe crabs underwent one or more ancient whole genome duplications 300 million years ago, followed by extensive chromosome fusion. These results provide a counter-example to the often noted correlation between whole genome duplication and evolutionary radiations. The new, low-cost genetic mapping method for obtaining a chromosome-scale view of non-model organism genomes that we demonstrate here does not require laboratory culture, and is potentially applicable to a broad range of other species.

New Phytologist

Plant disease resistance genes (R genes) encode proteins that function to monitor signals indicat... more Plant disease resistance genes (R genes) encode proteins that function to monitor signals indicating pathogenic infection, thus playing a critical role in the plant's defense system. Although many studies have been performed to explore the functional details of these important genes, their origin and evolutionary history remain unclear.

BMC Plant Biology

Background: Rates of molecular evolution vary widely among species. While significant deviations ... more Background: Rates of molecular evolution vary widely among species. While significant deviations from molecular clock have been found in many taxa, effects of life histories on molecular evolution are not fully understood. In plants, annual/perennial life history traits have long been suspected to influence the evolutionary rates at the molecular level. To date, however, the number of genes investigated on this subject is limited and the conclusions are mixed. To evaluate the possible heterogeneity in evolutionary rates between annual and perennial plants at the genomic level, we investigated 85 nuclear housekeeping genes, 10 non-housekeeping families, and 34 chloroplast genes using the genomic data from model plants including Arabidopsis thaliana and Medicago truncatula for annuals and grape (Vitis vinifera) and popular (Populus trichocarpa) for perennials.

Molecular Genetics and …, Jan 1, 2008

Most disease resistance genes in plants encode NBS-LRR proteins. However, in woody species, littl... more Most disease resistance genes in plants encode NBS-LRR proteins. However, in woody species, little is known about the evolutionary history of these genes. Here, we identiWed 459 and 330 respective NBS-LRRs in grapevine and poplar genomes. We subsequently investigated protein motif composition, phylogenetic relationships and physical locations. We found signiWcant excesses of recent duplications in perennial species, compared with those of annuals, represented by rice and Arabidopsis. Consequently, we observed higher nucleotide identity among paralogs and a higher percentage of NBS-encoding genes positioned in numerous clusters in the grapevine and poplar. These results suggested that recent tandem duplication played a major role in NBS-encoding gene expansion in perennial species. These duplication events, together with a higher probability of recombination revealed in this study, could compensate for the longer generation time in woody perennial species e.g. duplication and recombination could serve to generate novel resistance speciWcities. In addition, we observed extensive species-speciWc expansion in TIR-NBS-encoding genes. Non-TIR-NBS-encoding genes were poly-or paraphyletic, i.e. genes from three or more plant species were nested in diVerent clades, suggesting diVerent evolutionary patterns between these two gene types.