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Cultivated sweetpotato [Ipomoeabatatas (L.) Lam.] from the family Convolvulaceae is a hexaploid species with 2n = 6x = 90 and has been controversial regarding its nature as an autopolyploid arising within a species or an allopolyploid forming between species. Here, we developed oligonucleotide-based painting probes for two chromosomes of I. nil, a model diploid Ipomoea species. Using these probes, we revealed the pairing behavior of homoeologous chromosomes in I. batatas and its two possible polyploid ancestral species, tetraploid I. tabascana (2n = 4x = 60) and hexaploid I. trifida (2n = 6x = 90). Chromosome painting analysis revealed a high percentage of quadrivalent formation in zygotene-pachytene cells of I. tabascana, which supported that I. tabascana was an autotetraploid likely derived by doubling of structurally similar and homologous genomes rather than a hybrid between I. batatas and I. trifida (2x). A high frequency of hexavalent/bivalent and tetravalent pairing was observed in I. trifida (6x)and I. batatas. However, the percentage of hexavalent pairing in I. trifida (6x) was far higher than that in I. batatas. Thus, the present results tend to support that I. trifida (6x) is an autohexaploid, while I. batatas is more likely to be a segmental allohexaploid. Key words: sweetpotato, polyploids, karyotype, chromosome pairing, chromosome painting La patate douce cultivée [Ipomea batatas (L.) Lam.] appartient à la famille des Convolvulaceae, est une espèce hexaploïde à 2n = 6x = 90 chromosomes. Sa nature exacte demeure controversée à savoir s'il s'agit d'une autopolyploïde dérivée d'une seule espèce ou encore d'une allopolyploïde formée à partir d'espèces distinctes. Dans ce travail, les auteurs ont mis au point des sondes oligonucléotidiques pour colorer deux chromosomes de l'I. nil, une espèce modèle diploïde pour les espèces du genre Ipomea. Au moyen de ces sondes, les auteurs ont révélé l'appariement des chromosomes homéologues chez l'I. batatas et les deux espèces polyploïdes ancestrales possibles, la tétraploïde I. tabascana (2n = 4x = 60) et l'hexaploïde I. trifida (2n = 6x = 90). La coloration des chromosomes a révélé un fort pourcentage de formation de quadrivalents au stade zygotène-pachytène chez les cellules de l'I. tabascana, une observation qui porte à penser que cette espèce est une autotétraploïde vraisemblablement dérivée du doublement de génomes structurellement similaires et homologues plutôt qu'un hybride entre l'I. batatas et l'I. trifida (2x). La fréquence d'hexavalents/bivalents et de tétravalents qui a été observée chez l'I. trifida (6x) était beaucoup plus élevée que chez l'I. batatas. Ainsi, les résultats obtenus tendent à montrer que l'I. trifida (6x) serait un autohexaploïde, tandis que l'I. batatas serait plus vraisemblablement un allohexaploïde segmentaire. Mots-clés: patate douce, polyploïdes, caryotype, appariement chromosomique, coloration des chromosomes, Introduction Cultivated sweetpotato [Ipomoea batatas (L.) Lam.] is the most important food and vegetable crop in the genus Ipomoea (Convolvulaceae). Because of its great economic importance, efforts are underway in [...]

Thinopyrum elongatum is an important gene pool for wheat genetic improvement. However, the origins of the Thinopyrum genomes and the nature of the genus' intraspecific relationships are still controversial. In this study, we used single-copy nuclear genes and non-denaturing fluorescence in situ hybridization (NDFISH) to characterize genome constitution and chromosome differentiation in Th. elongatum. According to phylogenetic analyses based on PepC and Pgk1 genes, there was an E genome with three versions ([E.sup.e],[E.sup.b],[E.sup.x])and St genomes in the polyploid Th. elongatum. The ND-FISH results of pSc119.2 and pAs1 revealed that the karyotypes of diploid Th. elongatum and Th. bessarabicum were different, and the chromosome differentiation occurred among accessions of the diploid Th. elongatum. In addition, the tetraploid Th. elongatum has two groups of ND-FISH karyotype, indicating that the tetraploid Th. elongatum might be a segmental allotetraploid. In summary, our results suggested that the diploid Th. elongatum, Th. Bessarabicum,andPseudoroegneria were the donors of the [E.sup.e],[E.sup.b], and St genomes to the polyploid Th. elongatum, respectively. Key words: Thinopyrum elongatum,phylogeny,PepC, Pgk1,ND-FISH. Le Thinopyrum elongatum constitue une importante ressource genetique pour l'amelioration du ble. Cependant, les origines et la nature des relations intraspecifiques des genomes presents au sein du genre Thinopyrum demeurent controversees. Dans ce travail, les auteurs ont employe l'hybridation in situ en fluorescence en conditions non-denaturantes (ND-FISH), en utilisant des genes nucleaires a simple copie comme sondes, pour etudier la composition genomique et la differenciation chromosomique chez le Th. elongatum. Sur la base d'analyses phylogenetiques realisees a l'aide des genes PepC et PgK1, trois versions d'un genome E ([E.sup.e],[E.sup.b] et [E.sup.x]) et des genomes St ont ete documentes chez le Th. elongatum polyploide. Les resultats des analyses ND-FISH a l'aide des sondes pSc119.2 et pAs1 ont revele que les caryotypes des Th. elongatum et Th. bessarabicum diploides etaient differents et qu'une differentiation chromosomique existait au sein des accessions diploides du Th. elongatum. De plus, le Th. elongatum tetraploidepresentedeux sortesde caryotypesND-FISH,cequi indique que le Th. elongatum tetraploide pourrait etre un allotetraploide segmentaire. En resume, les resultats obtenus suggerent que les especes diploides Th. elongatum, Th. bessarabicum et Pseudoroegneria seraient respectivement a l'origine des genomes [E.sup.e],[E.sup.b] et St presents chez les especes polyploides du Th. elongatum.[Traduit par la Redaction] Mots-cles : Thinopyrum elongatum, phylogenie, PepC, Pgk1, ND-FISH., Introduction The genus Thinopyrum is a perennial herb in the Triticeae, but the taxonomic status of this genus has been changed many times. The species in Thinopyrum were first classified [...]

Triploid salmonids have been shown to underperform in suboptimal environments. It is thought this might be due to having larger cells to accommodate the increased number of chromosomes and therefore effects on aerobic metabolism from having smaller cellular surface area to volume ratios. The goal of this study was to examine the aerobic metabolism of diploid and triploid white sturgeon (Acipenser transmontanus) in ambient (18 [degrees]C) and elevated water temperatures (24 [degrees]C). Resting and maximum metabolic rates, recovery time from exhaustive exercise, and surface area to volume ratios of erythrocytes and their nuclei in diploid and triploid sturgeon were evaluated. Triploid sturgeon had a reduced aerobic scope and hematological response (hematocrit and hemoglobin) to exhaustive exercise. A reduced surface area to volume ratio of erythrocytes in triploid sturgeon provides evidence that cellular surface area could be one mechanism limiting aerobic metabolism in triploid fishes. A lower aerobic scope found in triploid sturgeon may impact reproductive and somatic growth, yet more research is needed to determine implications for management decisions on farms and hatcheries. II a ete demontre que la performance de salmonides triploides dans des milieux suboptimaux est moins bonne que celle de salmonides diploides. Cela pourrait etre du au fait qu'ils ont des cellules plus grosses pour contenir leur plus grand nombre de chromosomes, ce qui aurait des effets sur le metabolisme aerobie associes aux rapports plus faibles de la surface et du volume des cellules. Le but de l'etude etait d'examiner le metabolisme aerobie d'esturgeons blancs (Acipenser transmontanus) diploides et triploides dans des temperatures ambiante (18 [degrees]C) et elevee (24 [degrees]C) de l'eau. Les metabolismes de base et maximum, le temps de recuperation d'un exercice epuisant et les rapports de la surface et du volume d'erythrocytes et de leurs noyaux chez des esturgeons diploides et triploides ont ete evalues. L'exercice intensif s'est traduit par une amplitude aerobie et une reaction hematologique (hematocrite et hemoglobine) reduites chez les esturgeons triploides. Un rapport plus faible de la surface et du volume des erythrocytes chez les esturgeons triploides indique que la surface des cellules pourrait etre un facteur qui limite le metabolisme aerobie chez les poissons triploides. L'amplitude aerobie plus faible observee chez les esturgeons triploides pourrait avoir une incidence sur la croissance reproductive et somatique, mais plus de travaux sont necessaires afin d'en etablir l'importance en ce qui concerne les decisions de gestion pour les piscicultures et les ecloseries. [Traduit par la Redaction], Introduction Study of the relationship between ploidy and physiological performance in fishes, at any biological level, has thus far been mostly limited to salmonid species (see Benfey 1999 and Maxime [...]

Paternal and maternal epigenomes undergo marked changes after fertilization.sup.1. Recent epigenomic studies have revealed the unusual chromatin landscapes that are present in oocytes, sperm and early preimplantation embryos, including atypical patterns of histone modifications.sup.2-4 and differences in chromosome organization and accessibility, both in gametes.sup.5-8 and after fertilization.sup.5,8-10. However, these studies have led to very different conclusions: the global absence of local topological-associated domains (TADs) in gametes and their appearance in the embryo.sup.8,9 versus the pre-existence of TADs and loops in the zygote.sup.5,11. The questions of whether parental structures can be inherited in the newly formed embryo and how these structures might relate to allele-specific gene regulation remain open. Here we map genomic interactions for each parental genome (including the X chromosome), using an optimized single-cell high-throughput chromosome conformation capture (HiC) protocol.sup.12,13, during preimplantation in the mouse. We integrate chromosome organization with allelic expression states and chromatin marks, and reveal that higher-order chromatin structure after fertilization coincides with an allele-specific enrichment of methylation of histone H3 at lysine 27. These early parental-specific domains correlate with gene repression and participate in parentally biased gene expression--including in recently described, transiently imprinted loci.sup.14. We also find TADs that arise in a non-parental-specific manner during a second wave of genome assembly. These de novo domains are associated with active chromatin. Finally, we obtain insights into the relationship between TADs and gene expression by investigating structural changes to the paternal X chromosome before and during X chromosome inactivation in preimplantation female embryos.sup.15. We find that TADs are lost as genes become silenced on the paternal X chromosome but linger in regions that escape X chromosome inactivation. These findings demonstrate the complex dynamics of three-dimensional genome organization and gene expression during early development. Single-cell allelic HiC analysis, combined with allelic gene expression and chromatin states, reveals parent-of-origin-specific dynamics of chromosome organization and gene expression during mouse preimplantation development., Author(s): Samuel Collombet [sup.1] [sup.2] , Noémie Ranisavljevic [sup.1] [sup.3] , Takashi Nagano [sup.4] [sup.9] , Csilla Varnai [sup.4] [sup.5] , Tarak Shisode [sup.6] , Wing Leung [sup.4] [sup.9] , [...]

Cardiovascular diseases remain a major public health burden worldwide. It was reported that vitamin D protects the cardiovascular system through several mechanisms mainly by hindering atherosclerosis development. Genetic variations in vitamin D metabolic pathway were found to affect vitamin D levels. This study aimed at investigating the association between single nucleotide polymorphisms in genes involved in vitamin D metabolism, CYP27B and CYP24A1; 25-hydroxyvitamin D (25(OH)D) levels; and susceptibility to acute coronary syndrome (ACS). One hundred and eighty-five patients and 138 healthy controls were recruited. CYP24A1 rs2762939 was genotyped using fast real-time PCR, while CYP24A1 rs4809960 and CYP27B1 rs703842 were genotyped using polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP). 25(OH)[D.sub.3] and 25(OH)[D.sub.2] levels were measured using ultra-performance liquid chromatography tandem mass spectrum. Vitamin D level was significantly lower in patients than controls (p Key words: myocardial infarction, 25(OH)D, single nucleotide polymorphism, CYP24A1, CYP27B1. Les maladies cardiovasculaires demeurent un fardeau de sante publique majeur a l'echelle mondiale. On a rapporte que la vitamine D permet de proteger le systeme cardiovasculaire par l'intermediaire de plusieurs modes d'action, principalement en retardant l'evolution de l'atherosclerose. On a observe que des variations genetiques des voies metaboliques de la vitamine D affectent les taux de vitamine D. Cette etude portait sur l'association entre des polymorphismes a nucleotide unique (ou SNP pour<>) dans des genes jouant un role dans le metabolisme de la vitamine D, CYP27B et CYP24A1, les taux de 25-hydroxyvitamine D (25(OH)D) et la susceptibilite au syndrome coronarien aigu. Nous avons inscrit 185 patients et 138 temoins en bonne sante. Nous avons genotype le rs2762939 du CYP24A1 a l'aide de la technique de PCR rapide en temps reel, tandis que le rs4809960 du CYP24A1 et le rs703842 du CYP27B1 ont ete genotypes a l'aide de la technique de PCR suivie du polymorphisme de longueur des fragments de restriction (ou RFLP pour<>). Nous avons mesure les taux de 25(OH)[D.sub.3] et de 25(OH)[D.sub.2] a l'aide de la chromatographie liquide d'ultra performance en tandem avec spectrometrie de masse. Nous avons observe que les taux de vitamine D etaient nettement moins eleves chez les patients que chez les temoins (p < 0,05). Le genotype GG du rs2762939 etait manifestement associe au risque d'apparition de syndrome coronarien aigu, mais sans proportionnalite avec les taux de vitamine D. Pour leur part, les variantes genetiques rs4809960 et rs703842 n'etaient pas associees avec le syndrome coronarien aigu ni avec les taux de 25(OH)D. La variante genetique rs2762939 du CYP24A1 est remarquablement associee avec le syndrome coronarien aigu. En contrepartie, les variantes rs4809960 et rs703842 ne sont pas associees avec la survenue d'un syndrome coronarien aigu. [Traduit par la Redaction] Mots-cles: infarctus du myocarde, 25(OH)D, polymorphisme a nucleotide unique, CYP24A1, CYP27B1., Introduction Cardiovascular disease (CVD) represents an immense burden worldwide. It is responsible for the death of 17.3 million per year, which accounts for 30% of the reported worldwide mortality, and [...]

Tricholoma matsutake is an ectomycorrhizal agaricomycete that produces matsutake mushrooms in association with conifers. Here, we isolated a pleiotropic mutant, designated as G1, following 7-ray irradiation of T. matsutake NBRC 33136. In addition to exhibiting increased cellulose- and amylose-degrading activities and altered mycelial morphology, G1 degenerated lateral roots and caused stunting or fatal wilting of seedlings of its symbiotic partner, Pinus densiflora, in vitro. A mutant, designated Ar 59, previously isolated after argon-ion beam irradiation, exhibited the same phenotypes as G1, but without its detrimental effects. Ar 59, like NBRC 33136, developed a Hartig net around healthy cortical cells that was composed of uniseriate hyphae. In G1-inoculated seedlings, the Hartig net was composed of heavily bundled hyphae penetrating the intercellular space, and it was accompanied by somewhat unusual forms of plant cortical cells. Sequences of rRNA gene-related markers, including four single nucleotide polymorphisms present within each strain, were 100% identical among NBRC 33136, G1, and Ar 59, indicating that they are mutants of the wild-type. Thus, 7-ray irradiation can convert the fungus from a beneficial to a harmful agent. These findings suggest the presence of an unknown mechanism in the fungal genome that can transform mutualism into parasitism. Key words: degrading enzymes, 7-ray irradiation mutagenesis, heavy-ion beam, phenotypic transformation, plant-microbe interactions. Tricholoma matsutake est un agaromycète ectomycorhize qui produit les champignons matsutake en association avec les conifères. Les auteurs ont isolé ici un mutant pléiotropique qu'ils ont désigné G1, à la suite d'une irradiation [gamma] de T. matsutake NBRC 33136. En plus de présenter une activité accrue de dégradation de la cellulose et de l'amylose et une morphologie mycéliale modifiée, G1 provoquait la dégénérescence des racines latérales et un retard de croissance ou une flétrissure fatale des jeunes plants de son partenaire symbiotique, Pinus densiflora, in vitro. Un mutant désigné Ar 59, isolé précédemment après une irradiation à un faisceau d'argon ionisé, présentait le même phénotype que G1, mais sans les effets néfastes. Ar 59, comme NBRC 33136, développait un réseau de Hartig autour des cellules corticales saines, composé d'hyphes unisériées. Chez les plantules inoculées avec G1, le réseau de Hartig était composé d'hyphes en faisceau pénétrant l'espace intercellulaire et était accompagné par des cellules corticales végétales de formes quelque peu inhabituelles. Les séquences de marqueurs reliés aux gènes de l'ARNr, y compris quatre polymorphismes de nucléotides uniques présents dans chaque souche, étaient 100% identiques entre NBRC 33136, G1 et Ar 59, indiquant qu'ils constituent des mutants de la souche sauvage. Ainsi, l'irradiation gamme peut convertir le champignon d'une forme bénéfique en un agent pathogène. Ces données suggèrent la présence d'un mécanisme inconnu dans le génome fongique qui peut transformer le mutualisme en parasitisme. [Traduit par la Rédaction] Mots-clés : enzymes de dégradation, mutagenèse par irradiation gamma, faisceau d'ions lourds, transformation phénotypique, interactions plante-microbe., Introduction Ectomycorrhizal symbiosis occurs belowground between woody plants, belonging mostly to Caesalpinioideae, Dipterocarpaceae, Fagaceae, and Pinaceae, and filamentous fungi, belonging mostly to Ascomycota and Basidiomycota, greatly contributing to healthy forest [...]

Fluorescence in situ hybridization (FISH) using oligonucleotides is a simple and convenient method for chromosome research. In this study, 34 of 46 previously developed oligonucleotides produced signals in barley. Together with two plasmid clones and one PCR-amplified cereal centromere repeat (CCS1) probe, 37 repetitive sequences were chromosomally located produced three types of signals covering different positions on the chromosomes. The centromeric and pericentric regions had a more complex genomic organization and sequence composition probably indicative of higher contents of heterochromatin. An efficient multi-plex probe containing eight oligonucleotides and a plasmid clone of 45S rDNA was developed. Thirty-three barley karyotypes were developed and compared. Among them, 11 irradiation-induced mutants of cultivar 08-49 showed no chromosomal variation, whereas 22 cultivar and landrace accessions contained 28 chromosomal polymorphisms. Chromosome 4H was the most variable and 6H was the least variable based on chromosome polymorphic information content (CPIC). Five polymorphic chromosomes (1H-2, 2H-1, 3H-3, 5H-2, and 6H-2) were dominant types, each occurring in more than 50% of accessions. The multi-plex probe should facilitate identification of further chromosomal polymorphisms in barley. Key words: chromosome diversity, multi-plex probe, oligonucleotide FISH. L'hybridation in situ en fluorescence (FISH) au moyen de sondes oligonucleotidiques est une methode simple et facile pour l'etude des chromosomes. Dans ce travail, 34 des 46 des oligonucleotides employes precedemment ont produit des signaux chez l'orge. Des sondes derivees de deux clones plasmidiques, d'une repetition centromerique de cereales (CCS1) amplifiee par PCR, ainsi que de 37 sequences repetees ont produit des signaux occupant diverses positions sur les chromosomes. Les regions centormeriques et pericentriques presentaient une organisation genomique plus complexe et une composition indiquant vraisemblablement une plus grande teneur en heterochromatine. Une sonde multiplexe efficiente composee de huit oligonucleotides et d'un clone plasmidique de l'ADNr 45S a ete mise au point. Trente-trois caryotypes d'orge ont ete produits et compares. Parmi ceux-ci, 11 mutants induits par irradiation du cultivar 08-49 ne montraient aucune variation chromosomique, tandis que 22 cultivars et varietes de pays presentaient 28 polymorphismes chromosomiques. Le chromosome 4H etait le plus variable, tandis que le chromosome 6H etait le moins variable sur la base de l'indice de polymorphisme chromosomique (CPIC, << chromosomal polymorphism information content >>). Cinq chromosomes polymorphes (1H-2, 2H-1, 3H-3, 5H-2 et 6H-2) etaient predominants, chacun etant present chez plus de 50 % des accessions. Cette sonde multiplexe devrait faciliter l'identification d'autres polymorphismes chromosomiques chez l'orge. [Traduit par la Redaction] Mots-cles : diversite chromosomique, sonde multiplexe, FISH a sondes oligonucleotidiques., Introduction According to the United Nations Food and Agriculture Organization (FAO) (http://www.fao.org/faostat/en/#home) barley (Hordeum vulgare L., 2n = 14) is the 4th major cereal crop in the world with a [...]

Cucumis anguria is a potential genetic resource for improving crops of the genus Cucumis, owing to its broad-spectrum resistance. However, few cytogenetic studies on C. anguria have been reported because of its small metaphase chromosomes and the scarcity of distinguished chromosomal landmarks. In this study, 14 single-copy genes from cucumber and rDNAs were used as probes for FISH to identify the individual chromosomes of C. anguria. The distinctive signal distribution patterns of the probes allowed us to distinguish each chromosome of C. anguria (A01-A12). Further, detailed chromosome characteristics were obtained through pachytene chromosome FISH. The lengths of pachytene chromosomes varied from 54.80 to 143.41 [micro]m. The proportion of heterochromatin regions varied from 13.56% to 63.86%. Finally, the chromosomal homeologous relationship between C. anguria and cucumber (C1-C7) was analyzed. The results showed that A06 + A09, A03 + A12, A02 + A04, and A01 + A11 were homeologs of C1, C2, C3, and C6, respectively. Furthemore, chromosomes A08, A10, and A05 were homeologs of C4, C5, and C7, respectively. Chromosome identification and homeologous relationship analysis between C. anguria and cucumber lay the foundation for further research of genome structure evolution in species of Cucumis. Key words: Cucumis anguria, cross-species FISH, single-copy genes, karyotype, homeologous relationship. Resume : Le Cucumis anguria constitue une ressource genetique pouvant potentiellement contribuer a l'amelioration des cultures appartenant au genre Cucumis en raison de sa resistance a large spectre. Peu d'etudes cytogenetiques ont ete rapportees en raison de la petite taille de ses chromosomes en metaphase et du peu de points de reperes chromosomiques. Dans ce travail, 14 genes a simple copie du concombre et les ADNr ont ete employes comme sondes FISH pour identifier les chromosomes individuels du C. anguria. La distribution distinctive des signaux produits par les sondes a permis de distinguer chacun des chromosomes du C. anguria (A01 a A12). De plus, des caracteristiques chromosomiques detaillees ont ete obtenues a l'aide d'analyses FISH sur des chromosomes en pachytene. La longueur des chromosomes en pachytene variait de 54,80 a 143,41 [micro]m. Les regions heterochromatiques representaient entre 13,56 et 63,86 % des chromosomes. Finalement, les relations d'homeologie chromosomique entre les chromosomes du C. anguria et ceux du concombre (C1-C7) ont ete analysees. Les resultats ont montre que les chromosomes A06 + A09, A03 + A12, A02 + A04, et A01 + A11 etaient des homeologues des chromosomes C1, C2, C3 et C6, respectivement. Les chromosomes A08, A10 et A05 etaient homeologues des chromosomes C4, C5 et C7, respectivement. L'identification des chromosomes et l'etablissement des relations d'homeologie entre le C. anguria et le concombre fournissent une assise pour de futurs travaux sur l'evolution de la structure des genomes au sein des especes du genre Cucumis. [Traduit par la Redaction] Mots-cles: Cucumis anguria, FISH interspecifique, genes a simple copie, caryotype, relations d'homeologie., Introduction Cucumis anguria (West Indian gherkin) (2n = 2x = 24) is of Africa origin, and is now cultivated in many places especially in Brazil and the United States because [...]

Genes that promote sexual conflict, such as those with a sex-limited fitness benefit, are expected to accumulate differentially on sex chromosomes relative to autosomes. Few tests of this hypothesis exist for male homogametic (ZZ) taxa, however, and most use RNA expression data to identify such genes. Here, we employ a different identification method by using proteomic analysis of sperm cells to identify genes with a sex-limited benefit. We tested for a bias in genomic location of sperm protein genes in two species of Lepidoptera. An excess of sperm protein genes was identified on the Z chromosomes of both the Carolina sphinx moth (Manduca sexta) and the monarch butterfly (Danaus plexippus). Taking into consideration a Z-autosome fusion in monarchs, we discover that the ancestrally sex-linked portion of the genome is the source of this enrichment, while the newly sex-linked portion still appears similar to autosomes in relative abundance of sperm protein genes. Together, these results point to an enrichment of male-beneficial genes on the Z chromosome and demonstrate the usefulness of proteomic datasets in sexual conflict research. Key words: sex chromosomes, sexual antagonism, sexual conflict, sperm, female heterogamety, Lepidoptera. Il est attendu que les genes qui promeuvent le conflit sexuel, comme ceux qui presentent un benefice adaptatif limite a un sexe, s'accumulent de maniere preferentielle sur les chromosomes sexuels plutot que sur les autosomes. Cependant, peu de tests de cette hypothese ont ete faits chez des taxons ayant des males homogametiques (ZZ) et la plupart ont employe des donnees sur l'expression des ARN pour identifier de tels genes. Ici, les auteurs emploient une methode d'identification differente faisant appel a l'analyse proteomique des cellules spermatiques pour identifier des genes dont le benefice est limite a un sexe. Les auteurs ont teste pour des biais dans l'emplacement genomique de genes codant pour des proteines du sperme chez deux especes de lepidopteres. Un exces de genes codant pour des proteines du sperme a ete identifie sur les chromosomes Z tant chez le sphinx du tabac (Manduca sexta) que le monarque (Danaus plexippus). En tenant compte d'une fusion Z-autosome chez les monarques, les auteurs ont trouve que la portion du genome qui etait precedemment liee au sexe etait responsable de cet enrichissement, tandis que la portion nouvellement liee au sexe ressemblait aux autres autosomes en ce qui a trait a l'abondance relative en genes codant pour des proteines du sperme. Ensemble, ces resultats suggerent un enrichissement de genes benefiques pour le male sur le chromosome Z et demontrent l'utilite de donnees proteomiques dans les travaux de recherche sur les conflits sexuels. [Traduit par la Redaction] Mots-cles: chromosomes sexuels, antagonisme sexuel, conflit sexuel, sperme, heterogametie femelle, Lepidoptera., Introduction All living organisms exist as partnerships of genes that can only function in conjunction with each other, but there are many times when a gene's function does not benefit [...]

Drosophila has demonstrated to be an excellent model to study the adaptation of organisms to global warming, with inversion chromosomal polymorphism having a key role in this adaptation. Here, we introduce a new index (Chromosomal Thermal Index or CTI) to quantify the thermal adaptation of a population according to its composition of 'warm' and 'cold' adapted inversions. This index is intuitive, has good statistical properties, and can be used to hypothesis on the effect of global warming on natural populations. We show the usefulness of CTI using data from European populations of D. subobscura, sampled in different years. Out of 15 comparisons over time, nine showed significant increase of CTI, in accordance with global warming expectations. Although large regions of the genome outside inversions contain thermal adaptation genes, our results show that the total amount of warm or cold inversions in populations seems to be directly involved in thermal adaptation, whereas the interactions between the inversions content of homologous and non-homologous chromosomes are not relevant. Key words: Drosophila, thermal adaptation, chromosomes, inversions, global warming. La drosophile s'est averee un excellent modele pour etudier l'adaptation des organismes au rechauffement climatique, le polymorphisme pour les inversions chromosomiques jouant un role cle dans cette adaptation. Dans ce travail, les auteurs developpent un nouvel indice (le << Chromosomal Thermal Index >> ou CTI) pour quantifier l'adaptation thermique d'une population en fonction de sa composition en matiere d'inversions adaptees a des conditions chaudes ou froides. Cet indice est intuitif, presente de bonnes proprietes statistiques et on peut l'employer pour tester des hypotheses sur l'effet du rechauffement sur des populations naturelles. Les auteurs illustrent l'utilite du CTI en utilisant des donnees sur des populations europeennes du D. subobscura, lesquelles ont ete echantillonnees en differentes annees. Des 15 comparaisons realisees au cours du temps, neuf ont montre un accroissement significatif du CTI, conformement aux attentes liees au rechauffement. Bien que de grandes regions du genome situees hors de ces inversions contiennent des genes d'adaptation thermique, les resultats de ce travail montrent que le nombre total d'inversions conferant une adaptation aux conditions froides ou chaudes semble directement lie a l'adaptation thermique, tandis que les interactions entre la teneur en inversions des chromosomes homologues et non-homologues semblent denuees de relation. [Traduit par la Redaction] Mots-cles : Drosophila, adaptation thermique, chromosomes, inversions, rechauffement climatique., Introduction Almost a century ago, Sturtevant (1917, 1921) described chromosomal inversions for the first time in Drosophila melanogaster. He observed that their main genetic effect was recombination reduction. According to [...]

Author(s): Taru Tukiainen (corresponding author) [1, 2]; Alexandra-Chlo Villani [2, 3]; Angela Yen [2, 4]; Manuel A. Rivas [1, 2, 5]; Jamie L. Marshall [1, 2]; Rahul Satija [2, 6, [...]

Abstract: Korean field mouse (Apodemus peninsulae) shows a wide variation in the number of B chromosomes composed of constitutive heterochromatin. For this reason, it provides a good model to study [...]

Abstract: B chromosomes have so far been described in about 80 species of Coleoptera, mainly using conventional staining analysis. In this study, 152 individuals of the dung beetle Dichotomius sericeus [...]

X-chromosome inactivation (XCI) involves major reorganization of the X chromosome as it becomes silent and heterochromatic. During female mammalian development, XCI is triggered by upregulation of the non-coding Xist RNA from one of the two X chromosomes. Xist coats the chromosome in cis and induces silencing of almost all genes via its A-repeat region (1,2), although some genes (constitutive escapees) avoid silencing in most cell types, and others (facultative escapees) escape XCI only in specific contexts (3). A role for Xist in organizing the inactive X (Xi) chromosome has been proposed (4-6). Recent chromosome conformation capture approaches have revealed global loss of local structure on the Xi chromosome and formation of large mega-domains, separated by a region containing the DXZ4 macrosatellite (7-10). However, the molecular architecture of the Xi chromosome, in both the silent and expressed regions, remains unclear. Here we investigate the structure, chromatin accessibility and expression status of the mouse Xi chromosome in highly polymorphic clonal neural progenitors (NPCs) and embryonic stem cells. We demonstrate a crucial role for Xist and the DXZ4-containing boundary in shaping Xi chromosome structure using allele-specific genome-wide chromosome conformation capture (Hi-C) analysis, an assay for transposase-accessible chromatin with high throughput sequencing (ATAC-seq) and RNA sequencing. Deletion of the boundary disrupts mega-domain formation, and induction of Xist RNA initiates formation of the boundary and the loss of DNA accessibility. We also show that in NPCs, the Xi chromosome lacks active/inactive compartments and topologically associating domains (TADs), except around genes that escape XCI. Escapee gene clusters display TAD-like structures and retain DNA accessibility at promoter-proximal and CTCF-binding sites. Furthermore, altered patterns of facultative escape genes in different neural progenitor clones are associated with the presence of different TAD-like structures after XCI. These findings suggest a key role for transcription and CTCF in the formation of TADs in the context of the Xi chromosome in neural progenitors., To investigate the structure of the Xi chromosome, we performed allele-specific Hi-C in a clonal neural progenitor cell (NPC) line that was derived from highly polymorphic F1 mouse embryonic stem [...]

Chromosome engineering is an important approach for generating wheat germplasm. Efficient development of chromosome aberrations will facilitate the introgression and application of alien genes in wheat. In this study, zebularine, [...]

Accurate chromosome segregation requires timely dissolution of chromosome cohesion after chromosomes are properly attached to the mitotic spindle. Separase is absolutely essential for cohesion dissolution in organisms from yeast to [...]