Patterns of meiotic chromosome segregation were analyzed in cleavage stage and blastocyst stage human embryos from couples with autosomal reciprocal translocations (ART). The influence of quadrivalent asymmetry degree, the presence of terminal breakpoints, and the involvement of acrocentric chromosomes in the rearrangement were analyzed to evaluate their contribution to the formation of non-viable embryos with significant chromosomal imbalance due to pathological segregation patterns and to assess the selection of human embryos by the blastocyst stage. A selection of viable embryos resulting from alternate and adjacent-1 segregation and a significant reduction in the detection frequency of the 3 : 1 segregation pattern were observed in human embryos at the blastocyst stage. The presence of terminal breakpoints increased the frequency of 3 : 1 segregation and was also associated with better survival of human embryos resulting from adjacent-1 mode, reflecting the process of natural selection of viable embryos to the blastocyst stage. The demonstrated patterns of chromosome segregation and inheritance of a balanced karyotype in humans will contribute to optimizing the prediction of the outcomes of in vitro fertilization programs and assessing the risks of the formation of unbalanced embryos for ART carriers.

Results of the chromosome study of 12 sawfly species of the genus Schrank, 1802 are reviewed, including new data on the karyotypes of (Linnaeus, 1767) and (Linnaeus, 1767) with n = 10. Moreover, the same chromosome number, n = 10, is found in (Linnaeus, 1758), for which n = 8 was previously reported. In addition, n = 8 is confirmed in (Klug, 1814). The results of the morphometric analysis of chromosome sets of these four species are given. In the genus , haploid chromosome numbers of n = 8, 10, 11 and 13 were found. Among these sawflies, n = 8 appeared to be the most frequent chromosome number, followed by n = 10. The known data of the chromosome study of these insects are summarized and discussed in the light of phylogeny and taxonomy of the genus .

This work reveals the opportunities to obtain additional information about some biological problems through studying species that possess chromatin diminution. A brief review of the hypothesized biological significance of chromatin diminution is discussed. This article analyzes the biological role of chromatin diminution as it relates to the -value enigma. It is proposed to consider chromatin diminution as a universal mechanism of genome reduction, reducing the frequency of recombination events in the genome, which leads to specialization and adaptation of the species to more narrow environmental conditions. A hypothesis suggesting the role of non-coding DNA in homologous recombination in eukaryotes is proposed. Lilljeborg, 1901 (Copepoda, Crustacea) is proposed as a model species for studying the mechanisms of transformation of the chromosomes and interphase nuclei structure of somatic line cells due to chromatin diminution. Chromatin diminution in copepods is considered as a stage of irreversible differentiation of embryonic cells during ontogenesis. The process of speciation in cyclopoids with chromatin diminution is considered.

This study provides data on chromosome number (2n♂♀=26), sex determination mechanism (XY♂/XX♀), C-banding pattern, distribution of clusters of telomeric TTAGG repeats and 18S ribosomal DNA in the karyotype of the stonefly (McLachlan, 1872). For the first time in the history of stoneflies cytogenetics, we provide photos of the chromosomes of the Plecoptera insects. The karyotype of males and females of consists of 12 pairs of autosomes. Three pairs of large autosomes and four pairs of medium-sized autosomes are subacrocentric. The remaining pairs of autosomes are small, with unclear morphology. Pericentromeric C-bands were revealed in all autosomes. The sex chromosomes are also subacrocentric. The short arms of X and Y chromosomes are entirely heterochromatic and are rich in ribosomal DNA sequences. In the X chromosome this arm is larger than in the Y chromosome. It is likely that this arm associated with the nucleolar organizer (NOR). Telomeric DNA (TTAGG) repeats were detected in the terminal regions of all chromosomes.

The family Formicidae is composed of ants that organize themselves into castes in which every individual has a joint organizational function. Westwood, 1840 is an ant genus with opportunistic and aggressive characteristics, known for being invasive species and stings that cause burning in humans. This genus is particularly difficult to classify and identify since its morphology provides few indications for species differentiation. For this, a tool that has been useful for evolutionary and taxonomic studies is cytogenetics. Here, we cytogenetically studied Smith, 1855 from Ouro Preto, Minas Gerais, Brazil. We evaluated the occurrence of polyploid cells in individuals and colonies by conventional cytogenetics. A total of 450 metaphases were analyzed and counted. Chromosome counts of individuals and colonies showed varied numbers of ploidies, from n = 16 to 8n = 128. The karyomorphometrical approach allowed determination of the following karyotypes: n = 10 m + 4 sm + 2 st, 2n = 20 m + 8 sm + 4 st, and 4n = 40 m + 16 sm + 8 st. Polyploidy can be found naturally in individuals and colonies and may represent an adaptative trait related to widespread distribution and invasion ability of new habitats.

Ribosomal RNA (18S, 5.8S, 28S) gene clusters in genomes form regions that consist of multiple tandem repeats. They are located on a single or several pairs of chromosomes and play an important role in the formation of the nucleolus responsible for the assembly of ribosome subunits. The rRNA gene cluster sequences are widely used for taxonomic studies, however at present, complete information on the avian rDNA repeat unit structure including intergenic spacer sequence is available only for the chicken ( Linnaeus, 1758). The GC enrichment and high-order repeats peculiarities within the intergenic spacer described for the chicken rDNA cluster may be responsible for these failures. The karyotype of the Japanese quail ( Temminck et Schlegel, 1849) deserves close attention because, unlike most birds, it has three pairs of nucleolar organizer bearing chromosomes, two of which are microchromosomes enriched in repeating elements and heterochromatin that carry translocated terminal nucleolar organizers. Here we assembled and annotated the complete Japanese quail ribosomal gene cluster sequence of 21166 base pairs (GenBank under the registration tag BankIt2509210 CoturnixOK523374). This is the second deciphered avian rDNA cluster after the chicken. Despite the revealed high similarity with the chicken corresponding sequence, it has a number of specific features, which include a slightly lower degree of GC content and the presence of bendable elements in the content of both the transcribed spacer I and the non-transcribed intergenic spacer.

The current study analyzed the chromosomal karyotype of David, 1875 from Hunan Province, China. The karyotype, C-banding, BrdU-banding pattern were characterized using direct preparation of bone-marrow cells and hemocyte cultures. The findings indicated that was a diploid species (2n = 26) that lacked heteromorphic chromosomes and secondary constrictions. C-banding analysis revealed an abundance of positive signals in the centromere regions, while the BrdU-banding pattern showed three phases in both male and female, occurring consistently and in chronological sequence during S-phase. Notably, there was no asynchronous replication in the late phase. This study enhanced our understanding of the karyotypic structure of by conventional cytogenetic techniques, thus providing essential scientific insights into the cytogenetics of .

We studied the karyotype and chromosomal distribution of 18S rDNA clustered in nucleolar organizer regions (NORs) in (Kolenati, 1845), belonging to the subfamily Orsillinae (Lygaeidae). It is shown that this species has a karyotype with 2n = 22(18+mm+XY), previously known in only one of 24 studied species of the genus Dallas, 1852, characterized by a similar karyotype, 2n = 14(12+mm+XY). In , 18S loci are located on sex chromosomes, which is a previously unknown trait for this genus. Our results in a compilation with previous data revealed dynamic evolution of rDNA distribution in . It is concluded that molecular chromosomal markers detected by FISH contribute to a better understanding of the structure and evolution of the taxonomically complex genus .

Keyl, 1961 is recorded from Sevan Lake for the first time. This species is widespread in Europe, the Caucasus, and Siberia. For species identification, we used a comprehensive approach that included morphological, cytogenetic and molecular genetic analyses. Morphological analysis showed a high similarity with the description. Nine chromosome banding sequences ndtA1, ndtA2, ndtB2, ndtC1, ndtD1, ndtE1, ndtF1, ndtG1, and ndtG2 were found. The banding sequences ndtA1, ndtA2, ndtG1, and ndtG2 are species-specific for and allow us to accurately distinguish it from the sibling species Belyanina, Sigareva et Loginova, 1990. Molecular-genetic analysis of the gene sequences has shown low genetic distances of 0.38-0.95% in the sibling species and complex and the insufficiency of using a single as a molecular marker for their separation.

Recently, hypotheses regarding the evolutionary patterns of ribosomal genes in ant chromosomes have been under discussion. One of these hypotheses proposes a relationship between chromosomal location and the number of rDNA sites, suggesting that terminal locations facilitate the dispersion of rDNA clusters through ectopic recombination during meiosis, while intrachromosomal locations restrict them to a single chromosome pair. Another hypothesis suggests that the multiplication of rDNA sites could be associated with an increase in the chromosome number in Hymenoptera due to chromosomal fissions. In this study, we physically mapped rDNA sites in 15 new ant species and also reviewed data on rDNA available since the revision by Teixeira et al. (2021a). Our objectives were to investigate whether the new data confirm the relationship between chromosomal location and the number of rDNA sites, and whether the increase in the chromosome number is significant in the dispersion of rDNA clusters in ant karyotypes. Combining our new data with all information on ant cytogenetics published after 2021, 40 new species and nine new genera were assembled. Most species exhibited intrachromosomal rDNA sites on a single chromosome pair, while three species showed these genes in terminal regions of multiple chromosome pairs. On one hand, the hypothesis that the chromosomal location of rDNA clusters may facilitate the dispersion of rDNA sites in the ant genome, as previously discussed, was strengthened, but, on the other hand, the hypothesis of chromosomal fission as the main mechanism for dispersion of ribosomal genes in ants is likely to be refuted. Furthermore, in certain genera, the location of rDNA sites remained similar among the species studied, whereas in others, the distribution of these genes showed significant variation between species, suggesting a more dynamic chromosomal evolution.

Linnaeus, 1753, the largest genus of woody plants in the Northern Hemisphere, includes some of the most significant species in horticulture. Hemsl, 1911, a member of subsection Triflora Sleumer 1947, exemplifies typical alpine species. The analysis of the complete chloroplast genome of offers new insights into the evolution of species and enhances the resolution of phylogenetic relationships. This genome is composed of 207,478 base pairs, including a pair of inverted repeats (IRs) of 47,249 bp each, separated by a large single-copy (LSC) region of 110,367 bp and a small single-copy (SSC) region of 2,613 bp. It contains 110 genes: 77 protein-coding genes, 29 tRNAs, four unique rRNAs (4.5S, 5S, 16S, and 23S), with 16 genes duplicated in the IRs. Comparative analyses reveal substantial diversity in the chloroplast genome structures, identifying a fourth variant pattern. Specifically, four highly divergent regions (, , , ) were noted in the intergenic spacers. Additionally, 76 simple sequence repeats were identified. Positive selection signals were detected in four genes (, , , and ), evidenced by high Ka/Ks ratios. Phylogenetic reconstruction based on two datasets (shared protein-coding genes and complete chloroplast genomes) suggests that is closely related to Hemsley, 1889. However, the phylogenetic positions of subsection Triflora Pojarkova, 1952 species remain unresolved, indicating that the use of complete chloroplast genomes for phylogenetic research in requires careful consideration. Overall, our findings provide valuable genetic information that will enhance understanding of the evolution, molecular biology, and genetic improvement of spieces.

The karyotype of Litoria (L.) paraewingi (Watson et al., 1971) (Big River State Forest, Victoria) is described here for the first time. It is prepared following tissue culture of toe clipping macerates, cryopreservation, reculture and conventional 4',6-diamidino-2-phenylindole (DAPI) staining. The karyotype is then compared to similarly processed IUCN (International Union for the Conservation of Nature) least concern members (Duméril et Bibron, 1841) (southern Victoria) and (Duméril et Bibron, 1841) (Myall Lakes National Park, New South Wales), all members of the same complex/group. The diploid number is 2n = 26, the same as for the other two species. chromosomes 1, 2, 6 and 7 are submetacentric, chromosomes 3 and 5 are subtelocentric and the remainder are metacentric. No secondary constriction or putative nucleolus organiser region (NOR) was readily identifiable following conventional DAPI staining in any scored metaphase spread. Conversely, a putative NOR was readily identifiable on the long arm of chromosome 1 in all examined metaphase spreads for the other two species. The karyotypes of and here further differ from with chromosome 1 being metacentric and chromosomes 8 and 10 being submetacentric for both former species. The karyotype differs from those of and by DAPI staining with: (i) apparent relative length inversion of subtelocentric chromosome 3 and metacentric chromosome 4 and (ii) chromosome 6 being metacentric rather than submetacentric. All three species have a highly conserved chromosome morphology with respect to chromosomes 2, 5, 7, 9, 11, 12 and 13. The greatest gross morphological difference karyotypically is observed between and . These karyotype data support the previous phylogenetic separation of these three species based upon genetic compatibility and behavioural, biochemical and molecular genetic analyses.

Within a practical course of cytotaxonomy organized in Pisa (Italy) on February 2024 by the Group for Floristics, Systematics and Evolution of the Italian Botanical Society, we tested whether using image analysis softwares possible biases are still introduced by different observers. We conclude that observer bias selectively applies in possibly overestimating the length of short arms in a karyotype. As a consequence, the parameters most sensitive to these possible errors are CV and CV, and to a less degree M and THL. To achieve more stable results among observers, a still lacking standardized measurement protocol could be helpful.

An account is given of my development of techniques to obtain well-spread Giemsa-stained banded chromosome preparations. Apparent G-banding could be obtained following very slight trypsin treatment of freshly prepared slides, but this banding was very fine (close-grained) and possibly not a reflection of chromosome structure. However, treatment of developing embryos with 5-fluorouridine produced a similar chromomere banding, which is therefore regarded as genuine. Steady accumulation of Fabricius, 1775 karyotypes has resulted in the production of an Atlas covering 62 of the 170 species known to occur in the Palaearctic. Chromosome polymorphisms involving pericentric inversions and addition of extra C-banding regions have been found, as well as small B-chromosomes in a few species. In general, karyotypes have proved very useful in establishing the limits of individual species. Parthenogenesis involving triploidy has been found in two species. Karyotypes of experimentally produced hybrids have revealed irregularities in chromosome condensation.

To characterize the chromosomes of the four species of Miller, 1754, used in traditional Chinese medicine, Hua, 1892, Collett et Hemsley, 1890, (Miller, 1768) Druce, 1906, and Redouté, 1811, and have an insight into the karyotype variation of the genus , fluorescence hybridization (FISH) with 5S and 45S rDNA oligonucleotide probes was applied to analyze the karyotypes of 9 populations of the four species. Detailed molecular cytogenetic karyotypes of the 9 populations were established for the first time using the dataset of chromosome measurements and FISH signals of 5S and 45S rDNA. Four karyotype asymmetry indices, CV, CV, M and Stebbins' category, were measured to elucidate the asymmetry of the karyotypes and karyological relationships among species. Comparison of their karyotypes revealed distinct variations in the karyotypic parameters and rDNA patterns among and within species. The basic chromosome numbers detected were = 9, 11 and 13 for , = 15 for , = 10 and 11 for , and = 12 for . The original basic chromosome numbers of the four species were inferred on the basis of the data of this study and previous reports. All the 9 karyotypes were of moderate asymmetry and composed of metacentric, submetacentric and subtelocentric chromosomes or consisted of two of these types of chromosomes. Seven populations have one locus of 5S rDNA and two loci of 45S rDNA, and two populations added one 5S or 45S locus. The karyological relationships among the four species revealed by comparison of rDNA patterns and PCoA based on , 2, TCL, CV, M and CV were basically accordant with the phylogenetic relationships revealed by molecular phylogenetic studies. The mechanisms of both intra- and inter-specific dysploidy in were discussed based on the data of this study and literature.

The mitotic metaphases of five Andean species of genus are described for the first time. The evolutionary and interspecific genetic relationships within three Neotropical species groups are analyzed. The diploid chromosome number for each species is as follows: Céspedes et Rafael, 2012 2n = 6 (2V, 1J) (X = J, Y = R), Vela et Rafael, 2004 2n = 10 (3R, 2V) (X = V, Y = R), Vela et Rafael, 2005 2n = 10 (3R, 1V, 1D) (X = V, Y = R), Vela et Rafael, 2005 2n = 12 (4R, 2V) (X = V, Y = R), Llangarí-Arizo et Rafael, 2018 2n = 8 (3R, 1J) (X = J, Y = R).

The genus Martius, 1823 (Arecaceae) includes five species commonly used in Amazonia, especially for their fruits. Little is known about the cytogenetic characteristics and DNA amounts of these species, except for (Martius, 1823). This study characterized and compared the types of interphase nuclei, the chromosome sets, and estimated the nuclear DNA amounts of (Martius, 1823), , (Martius, 1823), (H. Karsten, 1857) and (Martius, 1823). Standard cytogenetic analyses and estimates of the nuclear DNA amount by flow cytometry were carried out. These are the first reports of chromosome numbers and DNA amounts, except for , as is the description of the chromatin distribution in interphase nuclei and karyotype for all species. All species presented 2n = 36, confirming the previous report for . Differences between karyotype formulas and the positioning of secondary constrictions were observed. There were no significant differences for the nuclear DNA amounts among species. The constancy in chromosome number and variations in karyotype formulas suggest the occurrence of chromosome rearrangement as an important mechanism in speciation.

The karyotype and reproductive features of Gavrilov-Zimin, 2017 (Pseudococcidae) were studied for the first time. Diploid chromosome number is 18 in females. Reproduction is probably bisexual, as indicated by the presence of characteristic Lecanoid heterochromatinization of the paternal set of chromosomes in embryonic cells of about 50% of the embryos studied. The female reproductive system has a pair of lateral oviducts merged into enlarged common oviduct; the spermatheca and accessory glands are connected to the common oviduct in its proximal part. Complete ovoviviparity occurs in ontogenesis.

Polyploidy is a condition in which a cell has multiple diploid sets of chromosomes. Two forms of polyploidy are known. One of them, generative polyploidy, is characteristic of all cells of the organism, while the other form develops only in some somatic tissues at certain stages of postnatal ontogenesis. Whole genome duplication has played a particularly important role in the evolution of plants and animals, while the role of cellular (somatic) polyploidy in organisms remains largely unclear. In this work we investigated the contribution of cellular polyploidy to the normal and the reparative liver growth of (Berkenhout, 1769) and Linnaeus, 1758. It is shown that polyploidy makes a significant contribution to the increase of the liver mass both in the course of normal postnatal development and during pathological process.

The karyotype of the IUCN least concern red-backed toadlet Pseudophryne (P.) coriacea (Keferstein, 1868) from the New South Wales Central Coast is described following tissue culture of toe clipping macerates and conventional DAPI staining. The diploid number is 2n = 24. The karyotype is represented by six large and five small chromosomal pairs and one very small chromosomal pair. The very small chromosome 12 is 12% the size of chromosome 1. One of the large chromosomes is subtelocentric, two of the large chromosomes are submetacentric and the remaining chromosomes are metacentric. The putative nucleolus organiser region (NOR) is observed on chromosome 4. The diploid number and location of the putative NOR correlates to that of the previously published IUCN critically endangered (Moore 1953) and unpublished descriptions of the karyotype. This is the first described cell culture of a species from the genus Fitzinger, 1843, first published analysis of the karyotype and the first published analysis of centromeric allocation of this genus. Globally there exists a large inventory of tissue samples in cryobanks that are not associated with known recovery mechanisms such as basic cell culture techniques. Detailed cytogenetic analyses of these cryobanked samples are therefore not possible. This work therefore enables: (i) a comparison of the karyotype with that of the critically endangered and (ii) a benchmark for repeat and future cytogenetic and genomic analyses of cryostored samples of this genus.

The karyotype of (Muesebeck, 1938), an important parasitoid of a serious tomato pest (= ) Meyrick, 1917 (Lepidoptera, Gelechiidae), in the Neotropics and adjacent regions, was studied for the first time using morphometric analysis and several techniques of differential chromosome staining, i.e., C-banding and staining with base-specific fluorochromes, together with fluorescence hybridization (FISH) with an 18S rDNA probe. We found n = 7 and 2n = 14 in , with seven metacentric chromosomes of similar size in the haploid set. C-banding revealed various C-positive bands, either centromeric or interstitial, on most chromosomes. Both AT-specific and GC-specific fluorochromes, 4'6-diamidino-2-phenylindole (DAPI) and chromomycin A (CMA) respectively, showed uniform staining of chromosomes. FISH visualized a single subterminal rDNA site on a medium-sized metacentric. A brief review of known chromosome sets of the subfamily Microgastrinae (Braconidae) is given; certain features of karyotype evolution of this group are discussed.