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3,457 results for “chromosomes”
FIGURE 1 in A study of chromosome and gametophyte development in Pellaea connectens C. Chr.
FIGURE 1. Mitotic metaphase and spores of Pellaea connectens. A–B: mitotic metaphase of root tip cells; C: mitotic metaphase of tender bud cells; D: the spores in a sporangium.
FIGURE 4. Metaphase chromosomes. A. Festuca galiciensis, 2n in Festuca galiciensis, a new species of the F. valesiaca group (Poaceae) from Ukraine
FIGURE 4. Metaphase chromosomes. A. Festuca galiciensis, 2n=4x=28. B. Hybrid Festuca galiciensis × Festuca rupicola, 2n=5x=35. C. Festuca rupicola, 2n=6x=42. All scale bars 10 μm.
FIGURE 3. FISH showing the chromosomes with 35S in Does Solidago litoralis (Asteraceae) merit specific rank? Insights from cytogenetic, molecular and ecological data
FIGURE 3. FISH showing the chromosomes with 35S (red) and 5S (green) signals. A. Partial metaphase of S. litoralis; B. Partial metaphase of S. virgaurea (Livorno); C. S. virgaurea (Monte Pisano); D. S. virgaurea (Tre Potenze). Scale bar: 10 μm.
Simulation data for "Loop-extruder mediated rigidity can globally order bacterial chromosomes"
<p>Simulated data for the manuscript "Loop-extruder mediated rigidity can globally order bacterial chromosomes". Analysis code can be found on github, at <a href="https://github.com/PLSysGitHub/e_coli_loop_extrusion" target="_blank" rel="noopener">github.com/PLSysGitHub/e_coli_loop_extrusion </a>.</p>
Data from: Scale-specific sex-biased dispersal in the Valais shrew unveiled by genetic variation on the Y chromosome, autosomes, and mitochondrial DNA
We investigated sex-specificities in the evolutionary processes shaping Y chromosome, autosomes and mitochondrial DNA patterns of genetic structure in the Valais shrew (Sorex antinorii), a mountain dwelling species with a hierarchical distribution. Both hierarchical analyses of variance and isolation-by-distance analyses revealed patterns of population structure that were not consistent across maternal, paternal and bi-parentally inherited markers. Differentiation on a Y microsatellite was lower than expected from the comparison with autosomal microsatellites and mtDNA, and it was mostly due to genetic variance among populations within valleys, while the opposite was observed on other markers. In addition, there was no pattern of isolation-by-distance for the Y, while there was strong isolation-by-distance on mtDNA and autosomes. We use a hierarchical island model of coancestry dynamics to discuss the relative roles of the micro-evolutionary forces that may induce such patterns. We conclude that sex-biased dispersal is the most important driver of the observed genetic structure, but with an intriguing twist: it seems that dispersal is strongly male-biased at large spatial scale, while it is mildly biased in favour of females at local scale. These results add to recent reports of scale-specific sex-biased dispersal patterns, and emphasize the usefulness of the Y chromosome in conjunction with mtDNA and autosomes to infer sex-specificities.
Data from: Transition in sexual system and sex chromosome evolution in the tadpole shrimp Triops cancriformis
Transitions in sexual system and reproductive mode may affect the course of sex chromosome evolution, for instance by altering the strength of sexually antagonistic selection. However, there have been few studies of sex chromosomes in systems where such transitions have been documented. The European tadpole shrimp, Triops cancriformis, has undergone a transition from dioecy to androdioecy (a sexual system where hermaphrodites and males coexist), offering an excellent opportunity to test the impact of this transition on the evolution of sex chromosomes. To identify sex-linked markers, to understand mechanisms of sex determination and to investigate differences between sexual systems, we carried out a genome-wide association study using restriction site-associated DNA sequencing (RAD-seq) of 47 males, females and hermaphrodites from one dioecious and one androdioecious population. We analysed 22.9 Gb of paired-end sequences and identified and scored >3000 high coverage novel genomic RAD markers. Presence–absence of markers, single-nucleotide polymorphism association and read depth identified 52 candidate sex-linked markers. We show that sex is genetically determined in T. cancriformis, with a ZW system conserved across dioecious and androdioecious populations and that hermaphrodites have likely evolved from females. We also show that the structure of the sex chromosomes differs strikingly, with a larger sex-linked region in the dioecious population compared with the androdioecious population.
Data from: Multiple origins of sex chromosome fusions correlated with chiasma localization in Habronattus jumping spiders (Araneae: Salticidae)
Entelegyne spiders rarely show fusions yielding neo-Y chromosomes, which M. J. D. White attributed to a constraint in spiders, namely their proximal chiasma localization acting to upset meiotic segregation in males with fusions. Of the 75 taxa of Habronattus and outgroups studied, 47 have X1X20 sex chromosomes in males, 10 have X1X2Y, 15 have X1X2X3Y, 2 have X0, and one has both X1X20 and X1X2X3Y. Chromosome numbers and behavior suggest neo-Ys formed by an autosome-X fusion to make X1X2Y, with a second fusion to an autosome to make X1X2X3Y. Phylogeny shows at least 8-15 gains (or possibly some losses) of neo-Y (i.e. X-autosome fusions), a remarkable number for such a small clade. In contrast to the many X-autosome fusions, at most one autosome-autosome fusion is indicated. Origins of neo-Y are correlated significantly with distal localization of chiasmata, supporting White's hypothesis that evolution of neo-Y systems is facilitated by looser pairing (distal chiasmata) at meiosis. However, an alternative (or contributing) explanation for the correlation is that X-autosome fusions were selected to permit isolation of male-favored alleles to the neo-Y chromosome, aided by distal chiasmata limiting recombination. This intralocus sexual conflict hypothesis could explain both the many X-autosome fusions, and the stunning complexity of male Habronattus courtship displays.
Data from: Sex-chromosome differentiation and 'sex races' in the common frog (Rana temporaria)
Sex-chromosome differentiation was recently shown to vary among common frog populations in Fennoscandia, suggesting a trend of increased differentiation with latitude. By rearing families from two contrasted populations (respectively, from northern and southern Sweden), we show this disparity to stem from differences in sex-determination mechanisms rather than in XY-recombination patterns. Offspring from the northern population display equal sex ratios at metamorphosis, with phenotypic sexes that correlate strongly with paternal LG2 haplotypes (the sex chromosome); accordingly, Y haplotypes are markedly differentiated, with male-specific alleles and depressed diversity testifying to their smaller effective population size. In the southern population, by contrast, a majority of juveniles present ovaries at metamorphosis; only later in development do sex ratios return to equilibrium. Even at these later stages, phenotypic sexes correlate only mildly with paternal LG2 haplotypes; accordingly, there are no recognizable Y haplotypes. These distinct patterns of gonadal development fit the concept of 'sex races' proposed in the 1930s, with our two populations assigned to the 'differentiated' and 'semi-differentiated' races, respectively. Our results support the suggestion that 'sex races' differ in the genetic versus epigenetic components of sex determination. Analysing populations from the 'undifferentiated race' with high-density genetic maps should help to further test this hypothesis.
FIGURE 3. A. Chromosome I in Karyotype of Propsilocerus akamusi (Tokunaga) from China (Diptera: Chironomidae)
FIGURE 3. A. Chromosome I of P. akamusi. Numbers designate chromosomal regions; other designations as in Figs. 1and 2. B. Centromere region of chromosome I; designations as in Figs. 1 and 2.
FIGURE 5 in The Peruvian species of Cristaria (Malveae, Malvaceae): taxonomic revision, chromosome counts, and breeding system
FIGURE 5. Chromosome preparations of Cristaria multifida subsp. multifida. A. Schneider & Huertas 2979. B. Schneider & Huertas 2801. Scale = 5 µm.
FIGURE 4 in The Peruvian species of Cristaria (Malveae, Malvaceae): taxonomic revision, chromosome counts, and breeding system
FIGURE 4. Habit and flower variants of Cristaria multifida subsp. multifida and details of flower and fruit. A. Cristaria multifida with small white flowers and broad leaf lobes from the Lomas de Lachay, Central Peru. B. Cristaria multifida from the southern border of its distribution range at Morro Sama, Tacna Department. C. Cristaria multifida with almost undivided leaves and minute white flowers from the interior lomas of Sama Grande at about 700 m. D. Large-flowered Cristaria multifida (petal length about 1 cm; C. aspera var. formosula) from the lomas of Mollendo. E. Detail of flower (here the Chilean C. integerrima) with its articulated pedicel (articulation see arrow). F. The characteristic carpocrater with the exposed winged mericarps; the lateral mericarp walls are evanescent and therefore the dark seeds are visible (here from C. multifida). All photos by the author.
FIGURE 3 in The Peruvian species of Cristaria (Malveae, Malvaceae): taxonomic revision, chromosome counts, and breeding system
FIGURE 3. Leaf variation, hair types, and inflorescence morphology of Cristaria multifida (A-D & H-J, subsp. multifida; E-G, subsp. moquipana). A. Tripartite leaf (Dombey s.n. [MA]). B. Undivided leaf (Müller 3621 ([LZ]). C. Trilobed leaf (Schneider et al. 2819 [USM]). D. Broadened apex of main leaf lobe. E. Deeply divided (to midvein) leaf (Müller et al. 1738 [LZ]). F & G. Narrowly obtuse to rounded apices of main leaf lobes (Weigend et al. 8400 & 8399 [LZ]). H. Erect bifid hair. I. Glandular hair (both Ferreyra 12485 [FR]). J. Apical part of flexuose inflorescence axis with remaining basal parts of pedicels and one fruiting flower (Müller et al. 12244 [LZ]). Illustrations by Julio V. Schneider.
FIGURE 3 in Polytene chromosomes of Simulium (Psaroniocompsa) daltanhani (Diptera: Simuliidae) from Central Amazonia, Brazil
FIGURE 3. Chromosome III of Simulium daltanhani. Bl = blister, bm = basal marker, C = centromere, Ca = capsule, Em = end marker, IIIL = long arm, IIIS = short arm. Section numbers indicate regions homologous with S. ulyssesi. Brackets on IIIL indicate the large, fixed inversion, relative to S. ulyssesi, that inverts the basal and end markers.
FIGURE 2. Chromosome II in Polytene chromosomes of Simulium (Psaroniocompsa) daltanhani (Diptera: Simuliidae) from Central Amazonia, Brazil
FIGURE 2. Chromosome II of Simulium daltanhani. C = centromere, IIL = long arm of male larva, IIS = short arm, RB = ring of Balbiani, T = trapezoid, '3' = three sharp, Pb = parabalbiani. Section numbers indicate regions homologous with S. ulyssesi. IIL-1 = breakpoints of heterozygous inversion linked to the X chromosome; brackets on IIS indicate fixed inversions relative to the sequence of S. ulyssesi.
FIGURE 1. Chromosome I in Polytene chromosomes of Simulium (Psaroniocompsa) daltanhani (Diptera: Simuliidae) from Central Amazonia, Brazil
FIGURE 1. Chromosome I of Simulium daltanhani. C = centromere, IL = long arm, IS = short arm, NO = nucleolar organizer, '3h' = three heavy. Section numbers indicate regions homologous with S. ulyssesi.
FIGURE 2 in Chromosomal analysis of three Brazilian "eleutherodactyline" frogs (Anura: Terrarana), with suggestion of a new species
FIGURE 2. Karyotype of Pristimantis aff. dundeei: (a) Giemsa and AgNOR staining; (b) Cbanding. The arrow indicates secondary constrictions, which are coincident with the NOR position (inset). The arrowheads indicate the interstitial heterochromatin. Bar = 10 µm.
FIGURE 1 in Chromosomal analysis of three Brazilian "eleutherodactyline" frogs (Anura: Terrarana), with suggestion of a new species
FIGURE 1. Karyotype of Pristimantis dundeei: (a) Giemsa and AgNOR staining; (b) Cbanding. The arrow indicates secondary constrictions, which are coincident with the NOR position (inset). The arrowheads indicate interstitial heterochromatin. Bar = 10 µm.
FIGURE 4 in Chromosomal analysis of three Brazilian "eleutherodactyline" frogs (Anura: Terrarana), with suggestion of a new species
FIGURE 4. Diplotene of I. paulodutrai: (a) Giemsa staining; (b) Cbanding showing bivalents and centromeric heterochromatin in all pairs. The arrow indicates interstitial heterochromatin in the pair 9. The arrowhead indicates the NORbearing chromosome pair. Bar = 10 µm.
FIGURE 5 in Chromosomal analysis of three Brazilian "eleutherodactyline" frogs (Anura: Terrarana), with suggestion of a new species
FIGURE 5. Giemsastained (a and c) and Cbanded (b and d) metaphases showing chromosomes associated by thin filaments (arrows) in P. dundeei and I. paulodutrai, respectively. Bar = 10 µm.
FIGURE 3 in Chromosomal analysis of three Brazilian "eleutherodactyline" frogs (Anura: Terrarana), with suggestion of a new species
FIGURE 3. Karyotype of Ischnocnema paulodutrai: (a) Giemsa and AgNOR staining; (b) Cbanding. The arrow indicates secondary constrictions. The arrowheads indicate interstitial heterochromatin. Inset: the AgNOR bearing chromosomes. Bar = 10 µm.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.