Pachytene karyotypes of 17 species of birds

Background: To date less than 10% of bird species have been karyotyped. They are rather conservative with diploid chromosome numbers about 78-80 in most species examined. Immunostaining of meiotic chromosomes at pachytene stage enables more precise estimates of the number, morphology and variability of macro- and microchromosomes than conventional analysis of mitotic metaphase chromosomes does. Analysis of pachytene chromosomes led to discovery of germline-restricted chromosome (GRC) that was present in germline cells and absent in somatic cells in all 16 species of passerine birds examined. GRC has not been found in any non-passerine bird. Results: In this study, using immunolocalization of SYCP3, the main protein of the lateral elements of the synaptonemal complex (SC) and centromere proteins we examined male pachytene karyotypes of sixteen passerine species and one outgroup species the Common cuckoo Cuculus canorus and provided their idiograms and precise estimates of their diploid chromosome numbers and the numbers of chromosome arms. We provided the first description of the karyotypes of three species, corrected the published data on the karyotypes of ten species and confirmed them for four species. The pachytene cells of the Gouldian finch, Brambling and Common linnet contained heteromorphic bivalents indicating heterozygosity for inversions or centromere shifts. The European pied flycatcher, Gouldian finch and Domestic canary have extended centromeres in several macro- and microchromosomes. GRCs of various sizes and shapes were detected in all passerine species examined. Their chromatin was heavily labeled by anticentromere antibodies. The lateral elements of the GRC SC varied in their size from the largest to the smallest element of the pachytene karyotype. They also varied in shape from continuous to fragmented. Conclusions: All songbirds examined, except the Eurasian skylark, have highly conservative karyotypes, 2n=80-82+GRC with seven pairs of macrochromosomes and 33-34 pairs of microchromosomes. The interspecies differences concern the sizes of the macrochromosomes, morphology of the microchromosomes and sizes of the centromeres. GRC is present in all songbird species examined, varying in size, morphology and SC structure even between closely related species. This indicates its fast evolution.

Check-list of chromosome numbers of the family Hygromiidae (Gastropoda: Stylommatophora) with new data on Circassina frutis

Chromosome number data on the Hygromiidae (Gastropoda: Stylommatophora) are summarized and reviewed briefly in the context of the phylogeny of the family. In hygromiids, the haploid chromosome numbers range from 21 to 26. It is supposed that n = 21 is the ancestral chromosome number in the family. The modal haploid number for Hygromiidae is 23. Description of karyotype in terms of chromosome number and morphology of hygromiid land snail Circassina frutis is provided for the first time. The diploid chromosome number of this species is 2n = 46. The karyotype is symmetric and consists of 21 pairs of metacentric and 2 pairs of submetacentric chromosomes. The karyotype formula is as follows: 2n = 42m + 4sm (n = 21m + 2sm). The fundamental number (FN) is 92. Chromosomes range in length from 2.53 μm for the smallest pair to 6.00 μm for the largest pair. The total length of chromosomes in diploid complement (TCL) is 170.40 ± 3.22 μm.

Chromosome numbers of invasive and potentially invasive species in the flora of the Republic of Altai. Post V

Chromosome numbers (2n) of 15 invasive and potentially invasive plant species from the families Asteraceae, Brassicaceae, Caryophyllaceae, Malvaceae, Onagraceae, Papaveraceae, Plantaginaceae, Poaceae, Polygonaceae, Portulacaceae, and Rosaceae are reported on the samples collected in the Republic of Altai. To determine the chromosome number (ploidy level), the method of direct counting was used. Among studied species, chromosome complements for Persicaria orientalis (2n = 22), Potentilla norvegica (2n = 42), Veronica persica (2n = 28) were first examined from Russia; for Papaver rhoeas (2n = 14) and Rumex obtusifolius (2n = 20) – from Asian part of Russia; for Bromus squarrosus (2n = 14), Cosmos bipinnatus (2n = 24), and Eriochloa villosa (2n = 54) – from Siberia. Abutilon theophrasti (2n = 42) and Lepidium densiflorum (2n = 32) were first studied from Western Siberia; Epilobium ciliatum subsp. adenocaulon (2n = 36), Portulaca oleracea (2n = 36), Spergularia rubra (2n = 36), and Xanthium strumarium (2n = 36) – from the Republic of Altai. Common distribution and the history of floristic findings of these species in the Republic of Altai are given. Previously published data on chromosome numbers from Russia are cited.

Chromosome numbers for the Italian flora: 12

In this contribution, new chromosome data obtained on material collected in Italy are presented. It includes the first counts for Hieracium glanduliferum s.str. and H. tenuiflorum, counts for two Armeria species endemic to Italy, and for Onopordum illyricum subsp. illyricum. We also present here the first chromosome count of Allium permixtum for Italy, where this species is known for few localities.

Chromosome Number, Ploidy Level, and Nuclear DNA Content in 23 Species of Echeveria (Crassulaceae)

Echeveria is a polyploid genus with a wide diversity of species and morphologies. The number of species registered for Echeveria is approximately 170; many of them are native to Mexico. This genus is of special interest in cytogenetic research because it has a variety of chromosome numbers and ploidy levels. Additionally, there are no studies concerning nuclear DNA content and the extent of endopolyploidy. This work aims to investigate the cytogenetic characteristics of 23 species of Echeveria collected in 9 states of Mexico, analyzing 2n chromosome numbers, ploidy level, nuclear DNA content, and endopolyploidy levels. Chromosome numbers were obtained from root tips. DNA content was obtained from the leaf parenchyma, which was processed according to the two-step protocol with Otto solutions and propidium iodide as fluorochrome, and then analyzed by flow cytometry. From the 23 species of Echeveria analyzed, 16 species lacked previous reports of 2n chromosome numbers. The 2n chromosome numbers found and analyzed in this research for Echeveria species ranged from 24 to 270. The range of 2C nuclear DNA amounts ranged from 1.26 pg in E. catorce to 7.70 pg in E. roseiflora, while the 1C values were 616 Mbp and 753 Mbp, respectively, for the same species. However, differences in the level of endopolyploidy nuclei were found, corresponding to 4 endocycles (8C, 16C, 32C and 64C) in E. olivacea, E. catorce, E. juarezensis and E. perezcalixii. In contrast, E. longiflora presented 3 endocycles (8C, 16C and 32C) and E. roseiflora presented 2 endocycles (8C and 16C). It has been suggested that polyploidization and diploidization processes, together with the presence of endopolyploidy, allowed Echeveria species to adapt and colonize new adverse environments.

POLYPLOIDY OF NORTH EAST ASIA AQUATIC AND SEMIAQUATIC VASCULAR PLANTS

The chromosome numbers of aquatic and semiaquatic vascular plants growing in extreme North-East Asia, east of the Lena River, were analyzed. We have reviewed the information about the karyological peculiarity of the aquatic flora based on published data, including our own definitions. The karyological data are considered depending on the taxonomic position, distribution and ecological characteristics of the species. The chromosome numbers are known for 119 out of 123 species. There is no data on Zannichellia komarovii, Eleocharis termale, Stuckenia subretusa and Potamogeton sibiricus. In the aquatic flora of North-East Asia, the proportion of polyploids is higher (79%) than that reported for the entire Beringian flora (69%). We analyzed species for the presence of polyploidy depending on the type of area. Analysis by latitudinal groups revealed that all Arctic and hypoarctic species of aquatic plants are polyploids. The minimum proportion of polyploids is observed among arctoboreal species. Analysis by longitudinal groups revealed that the lowest proportion of polyploids was noted among species found only in Eurasia and absent in North America (61%), and it was the highest among pluriregional species (96%). The species of the families Cyperaceae, Lemnaceae, Ranunculaceae and Poaceae are characterized by a high level of variability in the number of chromosomes. The greatest variety of chromosome numbers is observed in the polymorphic species Caltha palustris s. l., Agrostis stolonifera, Dupontia fisheri s. l., Phragmites australis, in all species of the genus Eleocharis, and in Nymphaea tetragona, Acorus calamus, Calla palustris. The isolated cases of a high level of ploidy were found in the extreme northeast, at the northern borders of ranges, in 3 species - Hippuris vulgaris, Arctophila fulva and Beckmannia syzigachne. Only diploids are known in the families Equisetaceae, Typhaceae, Zosteraceae from the flora of North East Asia. We revealed the existence of several chromosomal races in Ranunculus gmelinii and Caltha palustris (Ranunculaceae) in the Magadan region; the distribution of chromosomal races is partly related to geographic location and partly to plant habitats. Rare karyotypes in these species are observed in aquatic forms with mainly vegetative reproduction, growing in non-freezing watercourses.

Chromosome and Genome Diversity in the Genus Trifolium (Fabaceae)

Trifolium L. is an economically important genus that is characterized by variable karyotypes relating to its ploidy level and basic chromosome numbers. The advent of genomic resources combined with molecular cytogenetics provides an opportunity to develop our understanding of plant genomes in general. Here, we summarize the current state of knowledge on Trifolium genomes and chromosomes and review methodologies using molecular markers that have contributed to Trifolium research. We discuss possible future applications of cytogenetic methods in research on the Trifolium genome and chromosomes.

Cytogeography of the Solidago rugosa Mill. Complex (Asteraceae: Astereae) in Eastern North America

Chromosome numbers are reported here for the first time from 117 individuals of Solidago rugosa and S. fistulosa. Including 178 previously published reports for the two species plus S. latissimifolia, chromosome numbers have been determined from 295 individuals from 269 locations. Only diploids (2n = 18) were found throughout the range of S. fistulosa on the coastal plain in the eastern U.S.A. (44 counts). Diploids (2n = 18) were found in the northern portion of the range of S. latissimifolia, and tetraploids (2n = 36) and hexaploids (2n = 54) were found in the central and southern portions of the range (nine counts in total). Diploids (2n = 18) were found throughout the range of S. rugosa in much of eastern North America in four of the five varieties (northern var. rugosa, var. sphagnophila; southern var. aspera and var. celtidifolia). Tetraploids (2n = 36) were found in all four of these varieties and exclusively in var. cronquistiana in the southern high Appalachian Mountains. Hexaploids (2n = 54) were found in var. sphagnophila at scattered locations. One possible hexaploid in var. rugosa was found in the Allegheny Mountains. The diversity in ploidy levels was independent of the size of the range and the diversity of growing conditions among the three species of S. subsect. Venosae.

Regime Shift of Genome Size Crossing the Chasm of Eukaryogenesis

The origin of the nucleus remains a great mystery in life science, although nearly two centuries have passed since the discovery of nuclei. To date, studies of eukaryogenesis have focused largely on micro-evolutionary explanations. Here, we examined macro-patterns of C-values (the total amount of DNA within the haploid chromosome set of an organism) for over 110,000 species and the chromosome numbers for over 11,000 species and their potential links with the state of atmospheric oxidation over geological time. Eukaryogenesis was in sync with an over 2.5 order-of-magnitude increase in genome size from prokaryote to eukaryote, and also with a rapid rise of atmospheric oxidation, suggesting that eukaryogenesis would have resulted from a regime shift of genomes driven by the oxidation-driven complexification and structuralization (e.g. chromatin packing).