G3: Genes|Genomes|Genetics最新文献

Local adaptation is widely seen when species adapt to spatially heterogeneous environments. Although many theoretical studies have investigated the dynamics of local adaptation using two-population models, there remains a need to extend the theoretical framework to continuous space settings, reflecting the real habitats of species. In this study, we use a multidimensional continuous space model and mathematically analyze the establishment process of local adaptation, with a specific emphasis on the relative roles of mutation and migration. First, the role of new mutations is evaluated by deriving the establishment probability of a locally adapted mutation using a branching process and a diffusion approximation. Next, the contribution of immigrants from a neighboring region with similar environmental conditions is considered. Theoretical predictions of the local adaptation rate agreed with the results of Wright-Fisher simulations in both mutation-driven and migration-driven cases. Evolutionary dynamics depend on several factors, including the strength of migration and selection, population density, habitat size, and spatial dimensions. These results offer a theoretical framework for assessing whether mutation or migration predominantly drives convergent local adaptation in spatially continuous environments in the presence of patchy regions with similar environmental conditions.

Correlophus ciliatus, or the crested gecko, is widely kept as a pet in many countries around the world due to its ease to care and bred and its high survival rate. However, there is limited number of genomic studies on the crested gecko. In this study, we generated a high-quality chromosome-level genome assembly of the crested gecko by combining Nanopore, Illumina, and Hi-C data. The genome assemble has a size of 1.66 Gb, with scaffold N50 of 109.97 Mb, and 99.52% of the scaffold anchored on 19 chromosomes. The BUSCO analysis indicated a gene completeness of 90.3% (n=7,480), including 6,673 (89.2%) single-copy genes and 84 (1.1%) duplicated genes. Additionally, we identified 21,065 protein-coding genes using the MAKER3 annotation toolkit, with 41.98% (697.51 Mb) consisting of repetitive elements. Among these, 21,037 genes were validated through InterProScan5. Our study is the first to report a chromosome-level genome for the crested gecko. It provides valuable genomic resources for understanding molecular mechanisms under many interesting traits of the species.

Geisha coffee is recognized for its unique aromas and flavors and accordingly, has achieved the highest prices in the specialty coffee markets. We report the development of a chromosome-level, well-annotated, genome assembly of Coffea arabica var. Geisha. Geisha is considered an Ethiopian landrace that represents germplasm from the Ethiopian center of origin of coffee. We used a hybrid de novo assembly approach combining two long-reads single molecule sequencing technologies, Oxford Nanopore and Pacific Biosciences, together with scaffolding with Hi-C libraries. The final assembly is 1.03GB in size with BUSCO assessment of the assembly completeness of 97.7% of single-copy orthologs clusters. RNAseq and IsoSeq data were used as transcriptional experimental evidence for annotation and gene prediction revealing the presence of 47,062 gene loci encompassing 53,273 protein-coding transcripts. Comparison of the assembly to the progenitor subgenomes separated the set of chromosome sequences inherited from C. canephora from those of C. eugenioides. Corresponding orthologs between the two Arabica varieties, Geisha and Red Bourbon, had a 99.67% median identity, higher than what we observe with the progenitor assemblies (median 97.28%). Both Geisha and Red Bourbon contain a recombination event on Chromosome 10 relative to the two progenitors that must have happened before the geographical separation of the two varieties, consistent with a single allopolyploidization event giving rise to C. arabica. Broadening the availability of high-quality genome assemblies of Coffea arabica varieties, paves the way for understanding the evolution and domestication of coffee, as well as the genetic basis and environmental interactions of why a variety like Geisha is capable of producing beans with such exceptional and unique high-quality.

As human complex diseases are influenced by the interaction between genetics and the environment, identifying gene-environment interactions (G × E) is crucial for understanding disease mechanisms and predicting risk. Developing robust quantitative tools for G × E analysis can enhance the study of complex diseases. However, many existing methods that explore G × E focus on the interplay between an environmental factor and genetic variants, exclusively for common or rare variants. In this study, we developed MAGEIT_RAN and MAGEIT_FIX to identify interactions between an environmental factor and a set of genetic markers, including both rare and common variants, based on the MinQue for Summary statistics. The genetic main effects in MAGEIT_RAN and MAGEIT_FIX are modeled as random and fixed effects, respectively. Simulation studies showed that both tests had type I error under control, with MAGEIT_RAN being the most powerful test. Applying MAGEIT to a genome-wide analysis of gene-alcohol interactions on hypertension and seated systolic blood pressure in the Multi-Ethnic Study of Atherosclerosis revealed genes like EIF2AK2, CCNDBP1 and EPB42 influencing blood pressure through alcohol interaction. Pathway analysis identified one apoptosis and survival pathway involving PKR and two signal transduction pathways associated with hypertension and alcohol intake, demonstrating MAGEIT_RAN's ability to detect biologically relevant gene-environment interactions.

The popularity of genomic selection as an efficient and cost-effective approach to estimate breeding values continues to increase, due in part to the significant saving in phenotyping. Ridge regression is one of the most popular methods used for genomic prediction; however, its efficiency (in terms of prediction performance) depends on the appropriate tunning of the penalization parameter. In this paper we propose a novel, more efficient method to select the optimal penalization parameter for Ridge regression. We compared the proposed method with the conventional method to select the penalization parameter in 14 real data sets and we found that in 13 of these, the proposed method outperformed the conventional method and across data sets the gains in prediction accuracy in terms of Pearson's correlation was of 56.15%, with not-gains observed in terms of normalized mean square error. Finally, our results show evidence of the potential of the proposed method, and we encourage its adoption to improve the selection of candidate lines in the context of plant breeding.

Long unique genomic regions have been reported to be highly enriched for developmental genes in mice and humans. In this paper we identify unique genomic regions using an efficient method based on fast string matching. We quantify the resource consumption and accuracy of this method before applying it to the genomes of 18 mammals. We annotate their unique regions of at least 10 kb and find that they are strongly enriched for developmental genes across the board. We then investigated the subset of unique regions that lack annotations, which we call "anonymous". The longest anonymous unique region in the tasmanian devil spanned 83 kb and contained the gene encoding inositol polyphosphate-5-phosphatase A, which is an essential part of intracellular signaling. This discovery of an essential gene in a unique region implies that unique regions might be given priority when annotating mammalian genomes. Our documented pipeline for annotating unique regions in any mammalian genome is available from the repository github.com/evolbioinf/auger; additional data for this study is available from the dataverse at doi.org/10.17617/3.4IKQAG.

Double-strand breaks (DSBs) are genotoxic DNA lesions that pose significant threats to genomic stability, necessitating precise and efficient repair mechanisms to prevent cell death or mutations. DSBs are repaired through nonhomologous end-joining (NHEJ) or homology-directed repair (HDR), which includes homologous recombination (HR) and single-strand annealing (SSA). CtIP and Rif1 are conserved proteins implicated in DSB repair pathway choice, possibly through redundant roles in promoting DNA end-resection required for HDR. Although the roles of these proteins have been well-established in other organisms, the role of Rif1 and its potential redundancies with CtIP in Drosophila melanogaster remain elusive. To examine the roles of DmCtIP and DmRif1 in DSB repair, this study employed the direct repeat of white (DR-white) assay, tracking across indels by decomposition (TIDE) analysis, and P{wIw_2 kb 3'} assay to track repair outcomes in HR, NHEJ, and SSA, respectively. These experiments were performed in DmCtIPΔ/Δ single mutants, DmRif1Δ/Δ single mutants, and DmRif1Δ/Δ; DmCtIPΔ/Δ double mutants. This work demonstrates significant defects in both HR and SSA repair in DmCtIPΔ/Δ and DmRif1Δ/Δ single mutants. However, experiments in DmRif1Δ/Δ; DmCtIPΔ/Δ double mutants reveal that DmCtIP is epistatic to DmRif1 in promoting HDR. Overall, this study concludes that DmRif1 and DmCtIP do not perform their activities in a redundant pathway, but rather DmCtIP is the main driver in promoting HR and SSA, most likely through its role in end resection.

Lotmaria passim is a ubiquitous trypanosomatid parasite of honey bees nestled within the medically important subfamily Leishmaniinae. Although this parasite is associated with honey bee colony losses, the original draft genome-which was completed before its differentiation from the closely related Crithidia mellificae-has remained the reference for this species despite lacking improvements from newer methodologies. Here we report the updated sequencing, assembly, and annotation of the BRL type strain (ATCC PRA-422) of Lotmaria passim. The nuclear genome assembly has been resolved into 31 complete chromosomes and is paired with an assembled kinetoplast genome consisting of a maxicircle and 30 minicircle sequences. The assembly spans 33.7 Mb and contains very little repetitive content, from which our annotation of both the nuclear assembly and kinetoplast predicted 10,288 protein-coding genes. Analyses of the assembly revealed evidence of a recent chromosomal duplication event within chromosomes 5 and 6 and provides evidence for a high level of aneuploidy in this species, mirroring the genomic flexibility employed by other trypanosomatids as a means of adaptation to different environments. This high-quality reference can therefore provide insights into adaptations of trypanosomatids to the thermally regulated, acidic, and phytochemically rich honey bee hindgut niche, which offers parallels to the challenges faced by other Leishmaniinae during the challenges they undergo within insect vectors, during infection of mammals, and exposure to antiparasitic drugs throughout their multi-host life cycles. This reference will also facilitate investigations of strain-specific genomic polymorphisms, their role in pathogenicity, and the development of treatments for pollinator infection.