G3: Genes|Genomes|Genetics最新文献

Chemical signaling can play a crucial role in predator-prey dynamics. Here, we present evidence that ink from the common cuttlefish (Sepia officinalis) targets olfactory receptor proteins in shark, potentially acting as a predator deterrence. We apply in silico 3D docking analysis to investigate the binding affinity of various odorant molecules to shark olfactory receptors of two shark species: cloudy catshark (Scyliorhinus torazame) and white shark (Carcharodon carcharias). Pavoninin-4 (a known shark-repellent compound), displayed selectivity in binding to receptors in the white shark. In contrast, the primary component of cuttlefish ink, melanin, displayed the highest binding affinities to all shark olfactory receptor proteins in both species. Taurine, another important ink component, exhibited standard to strong bindings for both species. Trans-4,5-epoxy-(E)-2-decenal ("blood-decenal"), an odorant associated with the smell of blood displayed strong binding affinities to all shark olfactory receptors, similar to that of melanin. These findings provide new insights into the molecular interplay between cephalopod inking behavior and their shark predators, with cuttlefish ink likely exploiting the narrow band of the shark olfactory repertoire.

Polo-like kinases (Plks) are essential for spindle attachment to the kinetochore during prophase and the subsequent dissociation after anaphase in both mitosis and meiosis. There are structural differences in the spindle apparatus among mitosis, male meiosis, and female meiosis. It is therefore possible that alleles of Plk genes could improve kinetochore attachment or dissociation in spermatogenesis or oogenesis, but not both. These opposing effects could result in sexually antagonistic selection at Plk loci. In addition, Plk genes have been independently duplicated in many different evolutionary lineages within animals. This raises the possibility that Plk gene duplication may resolve sexual conflicts over mitotic and meiotic functions. We investigated this hypothesis by comparing the evolution, gene expression, and functional effects of the single Plk gene in Drosophila melanogaster (polo) and the duplicated Plks in D. pseudoobscura (Dpse-polo and Dpse-polo-dup1). Dpse-polo-dup1 is expressed primarily in testis, while other Drosophila Plk genes have broader expression profiles. We found that the protein-coding sequence of Dpse-polo-dup1 is evolving significantly faster than a canonical polo gene across all functional domains, yet the essential structure of the encoded protein has been retained. We present additional evidence that the faster evolution of Dpse-polo-dup1 is driven by the adaptive fixation of amino acid substitutions. We also found that over or ectopic expression of polo or Dpse-polo in the D. melanogaster male germline resulted in greater male infertility than expression of Dpse-polo-dup1. Last, expression of Dpse-polo or an ovary-derived transcript of polo in the male germline caused males to sire female-biased broods, suggesting that some Plk transcripts can affect the meiotic transmission of the sex chromosomes in the male germline. However, there was no sex bias in the progeny when Dpse-polo-dup1 was ectopically expressed, or a testis-derived transcript of polo was overexpressed in the D. melanogaster male germline. Our results therefore suggest that Dpse-polo-dup1 may have experienced positive selection to improve its regulation of the male meiotic spindle, resolving sexual conflict over meiotic Plk functions. Alternatively, Dpse-polo-dup1 may encode a hypomorphic Plk that has reduced deleterious effects when overexpressed in the male germline. Similarly, testis transcripts of D. melanogaster polo may be optimized for regulating the male meiotic spindle, and we provide evidence that the untranslated regions of the polo transcript may be involved in sex-specific germline functions.

Quantitative live imaging is a valuable tool that offers insights into cellular dynamics. However, many fundamental biological processes are incompatible with current live-imaging modalities. Drosophila oogenesis is a well-studied system that has provided molecular insights into a range of cellular and developmental processes. The length of the oogenesis, coupled with the requirement for inputs from multiple tissues, has made long-term culture challenging. Here, we have developed Bellymount-pulsed tracking (Bellymount-PT), which allows continuous, noninvasive live imaging of Drosophila oogenesis inside the female abdomen for up to 16 h. Bellymount-PT improves upon the existing Bellymount technique by adding pulsed anesthesia with periods of feeding that support the long-term survival of flies during imaging. Using Bellymount-PT, we measure key events of oogenesis, including egg chamber growth, yolk uptake, and transfer of specific proteins to the oocyte during nurse cell dumping with high spatiotemporal precision within the abdomen of a live female.

Centrosomes and spindle pole bodies (SPBs) are important for mitotic spindle formation and also serve as signaling platforms. In the fission yeast Schizosaccharomyces pombe, genetic ablation and high-resolution imaging indicate that the α-helical Ppc89 is central to SPB structure and function. Here, we developed and characterized conditional and truncation mutants of ppc89. Alleles with mutations in 2 predicted α-helices near the C-terminus were specifically defective in anchoring Sid4, the scaffold for the septation initiation network (SIN), and proteins dependent on Sid4 (Cdc11, Dma1, Mto1, and Mto2). Artificial tethering of Sid4 to the SPB fully rescued these ppc89 mutants. Another ppc89 allele had mutations located throughout the coding region. While this mutant was also defective in Sid4 anchoring, it displayed additional defects including fragmented SPBs and forming and constricting a second cytokinetic ring in 1 daughter cell. These defects were shared with a ppc89 allele truncated of the most C-terminal predicted α-helices that is still able to recruit Sid4 and the SIN. We conclude that Ppc89 not only tethers the SIN to the SPB but is also necessary for the integrity of the SPB and faithful coordination of cytokinesis with mitosis.

Copper has been widely used as a main component in fungicides due to its versatility and effectivity. However, copper contamination from the environment creates selective pressure for the emergence of copper-tolerant pathogenic fungal strains that may proliferate and further cause damage to important agricultural crops. Although some studies focused on specific cellular mechanisms of copper tolerance, comprehensive genomic data are lacking. Here, we examined the genes potentially involved in copper tolerance by conducting a comparative analysis of newly sequenced genomes of 2 Fusarium oxysporum strains, IB-SN1W (copper-tolerant) and Foc-3429 (copper-sensitive), with other Fusarium species. Whole-genome assembly and annotation identified 10 core chromosomes shared between the 2 strains. Protein prediction revealed 16,894 and 15,420 protein-coding genes for IB-SN1W and Foc-3429, respectively. There are 388 unique genes in IB-SN1W not found in Foc-3429, potentially contributing to copper tolerance. Furthermore, the identification of synteny between the 2 strains, including the analysis of orthologous genes within the Fusarium genus, confirmed the presence of accessory chromosomes that are specific to IB-SN1W, accounting for 13% of the genome. These accessory chromosomes consist of genes associated with cation transporter activity, vacuole, copper oxidases, and copper transporters which shed light on the potential mechanism of copper tolerance in this strain. Additionally, a region within an accessory chromosome contains a high density of copper-related genes, raising the possibility that horizontal transfer of these chromosomes may contribute to copper tolerance.

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 2 long-read single molecule sequencing technologies, Oxford Nanopore and Pacific Biosciences, together with scaffolding with Hi-C libraries. The final assembly is 1.03 Gb in size with BUSCO assessment of the assembly completeness of 97.7% of single-copy orthologs clusters. RNA-Seq and Iso-Seq 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 Coffea canephora from those of Coffea eugenioides. Corresponding orthologs between the 2 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 2 progenitors that must have happened before the geographical separation of the 2 varieties, consistent with a single allopolyploidization event giving rise to C. arabica. Broadening the availability of high-quality genome assemblies of C. 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.

The effective planning and allocation of resources in modern breeding programs is a complex task. Breeding program design and operational management have a major impact on the success of a breeding program and changing parameters such as the number of selected/phenotyped/genotyped individuals in the breeding program will impact genetic gain, genetic diversity, and costs. As a result, careful assessment and balancing of design parameters is crucial, taking into account the trade-offs between different breeding goals and associated costs. In a previous study, we optimized the resource allocation strategy in a dairy cattle breeding scheme via the combination of stochastic simulations and kernel regression, aiming to maximize a target function containing genetic gain and the inbreeding rate under a given budget. However, the high number of simulations required when using the proposed kernel regression method to optimize a breeding program with many parameters weakens the effectiveness of such a method. In this work, we are proposing an optimization framework that builds on the concepts of kernel regression but additionally makes use of an evolutionary algorithm to allow for a more effective and general optimization. The key idea is to consider a set of potential parameter settings of the breeding program, evaluate their performance based on stochastic simulations, and use these outputs to derive new parameter settings to test in an iterative procedure. The evolutionary algorithm was implemented in a Snakemake workflow management system to allow for efficient scaling on large distributed computing platforms. The algorithm achieved stabilization around the same optimum with a massively reduced number of simulations. Thereby, the incorporation of class variables and accounting for a higher number of parameters in the optimization framework leads to substantially reduced computing time and better scaling for the desired optimization of a breeding program.

Triatoma sanguisuga is the most widespread triatomine bug species in the United States (US). The species vectors the human parasite Trypanosoma cruzi, which causes Chagas disease. Vector-borne Chagas disease is rarely diagnosed in the US, but T. sanguisuga has been implicated in a handful of cases. Despite its public health importance, little is known about the genomics or population genetics of T. sanguisuga. Here, we used long-read sequencing to assemble the first whole genome sequence for T. sanguisuga using DNA extracted from one adult specimen from Delaware. The final size of the genome was 1.162 Gbp with 77.7x coverage. The assembly consisted of 183 contigs with an N50 size of 94.97 Kb. The Benchmarking Universal Single-Copy Ortholog (BUSCO) complete score was 99.1%, suggesting a very complete assembly. Genome-wide GC level was 33.56%, and DNA methylation was 18.84%. The genome consists of 62.75% repetitive DNA and 17,799 predicted coding genes. The assembled T. sanguisuga genome was very close in size and BUSCO score to that of Triatominae species Triatoma dimidiata (1.16 Gbp with 99.1% BUSCO score for T. sanguisuga vs 1.22 Gbp with 98.7% BUSCO score for T. dimidiata) and slightly larger than that of T. infestans and Rhodnius prolixus (949 Mbp with 90.4% BUSCO score and 706 Mbp with 96.5% BUSCO score, respectively). The T. sanguisuga genome is the first North American triatomine species genome to be sequenced, allowing for deeper investigations into epidemiologically relevant aspects of triatomines in temperate climates, thus providing potential vector-borne disease management targets and strengthening public health preparedness.

Mate selection plays an important role in breeding programs. The Usefulness Criterion was proposed to improve mate selection, combining information on both the mean and standard deviation of the potential offspring of a cross, particularly in clonally propagated species where large family sizes are possible. Predicting the mean value of a cross is generally easier than predicting the standard deviation, especially in outbred species when the linkage of alleles is unknown and phasing is required. In this study, we developed a method for estimating phasing accuracy from unphased genotype data on possible parental lines and evaluated whether the accuracy was sufficient to predict family standard deviations of possible crosses. We used simulations spanning a wide range of genetic architectures and used genotypes from a real strawberry breeding population to evaluate the conditions when usefulness could be accurately predicted. We found that with highly accurate computational phasing, predicting family standard deviations and usefulness criteria for potential crosses yields benefit over simply selecting crosses based on predicted family means only at high selection intensity and high heritability and with small numbers of QTL. However, even then the gain from using the family usefulness is small.

The release of heavy metals from industrial, agricultural, and mining activities poses significant risks to aquatic ecosystems by degrading water quality and generating reactive oxygen species (ROS) that can damage DNA in aquatic organisms. Daphnia is a widespread keystone species in freshwater ecosystems that is routinely exposed to a range of anthropogenic and natural stressors. With a fully sequenced genome, a well-understood life history and ecology, and an extensive library of responses to toxicity, Daphnia serves as an ideal model organism for studying the impact of environmental stressors on genomic stability. Ribosomal DNA (rDNA) encodes ribosomal RNA, which is essential for protein synthesis, and the spacers that separate the rRNA genes contain regulatory elements. However, the effects of heavy metals on this region of the genome are not well documented. We used short-read whole-genome sequences to analyze copy number and sequence variation in Daphnia pulex mutation accumulation lines exposed to nickel and copper, both individually and in combination, at concentrations that mimic levels often found at contaminated sites. We found no significant direct effect of chronic exposure to either metal on rDNA copy number or sequence variation. However, the results suggest that nickel and copper exposure may indirectly influence rDNA by altering recombination rates. We also emphasize the importance of interval length between generational samples for accurately assessing the frequency and magnitude of rDNA copy number changes. In addition, we observed differential expansion of rDNA haplotypes, suggesting that they may be clustered within the rDNA array.