Spatial population structure: patterns of adaptation in populations of the water hyacinth grasshopper Cornops aquaticum (Bruner 1906)

The water hyacinth grasshopper Cornops aquaticum (Bruner 1906) constitutes an appropriate model to assess phenotypic and karyotypic variability in the context of differentiation and adaptation of insect populations because it occurs over a wide latitudinal range. This study represents a general analysis of phenotype, karyotype and molecular variation in native populations of C. aquaticum in South America. This is also relevant because this insect is considered a promising biological control agent of water hyacinth, a native South American aquatic plant but a pest in South Africa. Along Paraná and Uruguay River Basins, body size correlated negatively with latitude, and positively so with temperature and rainfall in both sexes. To test whether the chromosomal and phenotypic patterns were adaptive, we compared them with neutral microsatellite loci variation in populations from the medium and lower course of the Paraná River. Firstly, the lack of pairwise association between karyotype and phenotype distance matrixes with that of neutral loci suggested non-neutrality. Secondly, phenotypic differentiation for all morphometric traits (PST) was significantly larger than molecular differentiation (FST), indicating a prevailing divergence selection effect on the observed phenotypic patterns. Finally, the phenotypic and genotypic spatial structures – inferred from Bayesian approaches – were discordant: neutral genetic structure clustered together most populations except for the two southernmost, downstream ones, whereas phenotypic spatial structure groups together all the deltaic populations and singles out the two northernmost ones. The results suggest directional selection leading to higher centric fusion frequencies in the downstream populations and favouring morphometric optimal differences in relation to the environment.

KARYOTYPAL VARIABILITY OF CARPATHIAN BROWN COWS

Brown Carpathian breed of cattle bred in Transcarpathia at the end of the XIX century. and belongs to the breeds of dairy and meat productivity. Animals of the modern breed are direct descendants of the ancient Brown Carpathian cattle, common at one time throughout Central Europe. The main advantage of the Brown Carpathian breed is that it can be effectively grown on natural pastures – both in the lowlands and in the mountains. The genetics of these animals are resistant to acute infectious diseases, they are well adapted to local conditions, sensitive to improved housing and feeding conditions, and cows produce special milk, which is used in the manufacture of high quality hard cheeses and baby food. Animals of the Brown Carpathian breed belong to the local small domestic breeds and are in a state of significant risk. The uterine population is bred only in households. The aim of our work was to study the karyotype variability of Brown Carpathian cows, which is quite relevant today. Cytogenetic analysis, which was aimed at establishing the karyotypic variability of Brown Carpathian cows, was performed in the village. Nyzhni Vorota, Volovets district, Zakarpattia region, in households. Purebred cows of Brown Carpathian breed – (16 heads) and local animals – (11 heads) were studied. According to the results of cytogenetic analysis, genomic disorders, aneuploidy, were found in purebred cows of Brown Carpathian breed, which was 1.6% and was expressed mainly by hypoploid cells 2n = 56–58. For domestic animals, the frequency of metaphase plates with aneuploidy was 3.3%, which corresponds to a spontaneous level of cytogenetic variability. Structural chromosome abnormalities, chromosomal breaks, in purebred cows were equal to 0.76%, which does not exceed the spontaneous level of chromosomal variability. In local animals, this variability did not manifest itsel. The indicators of the micronucleus test (the proportion of lymphocytes with a micronucleus of 1.7–2.0‰, dinuclear lymphocytes 1.5–2.7‰, and the mitotic index of 4.8–5.5‰, respectively) in domestic animals are higher compared to purebred animals, however, do not exceed those of the species Bos taurus. According to the results of the cytogenetic analysis, it was established that purebred cows of Brown Carpathian breed and their crossbreeds were characterized by quantitative and structural chromosome disorders. Genomic disorders, aneuploidy, in local animals are 2 times higher (3.3%) compared to purebred cows of Brown Carpathian breed with a statistically significant difference in mean values (P > 0.99). Low level or absence of structural disorders of chromosomes in purebred animals and their crossbreeds indicates a low degree of somatic mutagenesis. The indicators of the micronucleus test, as an indicator of the effect of the total mutagenic load on the body of the studied cows, in domestic animals are higher compared to purebred animals, however, do not exceed those characteristic of the species Bos taurus. It was established that the level of somatic mutagenesis is lower and the karyotype is more stable in purebred animals of the Brown Carpathian breed in comparison with the local ones.

Peculiarities of karyotype of the Ukrainian aboriginal Hutsul breed of horse

Saving biodiversity and assessment of the genetic diversity of local breeds of domestic animals as priority subjects of protection in agrobiocenoses is one of the global challenges facing humanity in the 21st century. Hutsul horse is one of the oldest horse breeds in Ukraine, which according to the gene pool subject of horses in Ukraine belongs to the group “Local (mountain and ponies)” of the I category, which is already on the verge of extinction, and according to the FAO classification it is considered to be a subject of the gene pool threatened with extinction. Since the breeding chromosomal polymorphism of horses is insufficiently studied, it is timely to carry out a cytogenetic analysis of the characteristics of spontaneous mutagenesis in Hutsul horses. Karyotypic variability of Hutsul breed horses was determined using the methods of cytogenetic analysis and micronucleus test. The paper presents the results of cytogenetic analysis and micronucleus test of karyotypic variability of Hutsul breed horses. Asynchronous divergence of centromere regions of chromosomes occurs as a result of premature replication of centromere regions of heterochromatin associated with centromere activity. In the studied Hutsul horses, the magnitude of this variability corresponds to the spontaneous level for horses as a whole (2.2-9.1 %). No structural chromosomal abnormalities (chromosomal breaks) were revealed in Hutsul breed horses at Krai Neba LLC, and in the animals of the Hutsulshchina National Nature Park, the percentage of metaphase plates with chromosomal breaks was low (1.1 %), which indicates the stability of the karyotype of the studied animals. The results of the micronucleus test showed that the proportion of lymphocytes with micronuclei in the animals at the both farms was practically the same - 4.0-4.2. It can be concluded based on the data obtained that the animals under study were in ecologically clean conditions relative to the level of radionuclide contamination and were characterized by karyotype stability and reduced sensitivity to mutagenic factors of various nature.

Chromosomal Signatures Corroborate the Phylogenetic Relationships within Akodontini (Rodentia, Sigmodontinae)

Comparative chromosome-painting analysis among highly rearranged karyotypes of Sigmodontinae rodents (Rodentia, Cricetidae) detects conserved syntenic blocks, which are proposed as chromosomal signatures and can be used as phylogenetic markers. In the Akodontini tribe, the molecular topology (Cytb and/or IRBP) shows five low-supported clades (divisions: “Akodon”, “Bibimys”, “Blarinomys”, “Oxymycterus”, and “Scapteromys”) within two high-supported major clades (clade A: “Akodon”, “Bibimys”, and “Oxymycterus”; clade B: “Blarinomys” and “Scapteromys”). Here, we examine the chromosomal signatures of the Akodontini tribe by using Hylaeamys megacephalus (HME) probes to study the karyotypes of Oxymycterus amazonicus (2n = 54, FN = 64) and Blarinomys breviceps (2n = 28, FN = 50), and compare these data with those from other taxa investigated using the same set of probes. We strategically employ the chromosomal signatures to elucidate phylogenetic relationships among the Akodontini. When we follow the evolution of chromosomal signature states, we find that the cytogenetic data corroborate the current molecular relationships in clade A nodes. We discuss the distinct events that caused karyotypic variability in the Oxymycterus and Blarinomys genera. In addition, we propose that Blarinomys may constitute a species complex, and that the taxonomy should be revised to better delimit the geographical boundaries and their taxonomic status.

Rapid chromosomal evolution in enigmatic mammal with XX in both sexes, the Alay mole vole Ellobius alaicus Vorontsov et al., 1969 (Mammalia, Rodentia)

Evolutionary history and taxonomic position for cryptic species may be clarified by using molecular and cytogenetic methods. The subterranean rodent, the Alay mole vole Ellobiusalaicus Vorontsov et al., 1969 is one of three sibling species constituting the subgenus Ellobius Fischer, 1814, all of which lost the Y chromosome and obtained isomorphic XX sex chromosomes in both males and females. E.alaicus is evaluated by IUCN as a data deficient species because their distribution, biology, and genetics are almost unknown. We revealed specific karyotypic variability (2n = 52–48) in E.alaicus due to different Robertsonian translocations (Rbs). Two variants of hybrids (2n = 53, different Rbs) with E.tancrei Blasius, 1884 were found at the Northern slopes of the Alay Ridge and in the Naryn district, Kyrgyzstan. We described the sudden change in chromosome numbers from 2n = 50 to 48 and specific karyotype structure for mole voles, which inhabit the entrance to the Alay Valley (Tajikistan), and revealed their affiliation as E.alaicus by cytochrome b and fragments of nuclear XIST and Rspo1 genes sequencing. To date, it is possible to expand the range of E.alaicus from the Alay Valley (South Kyrgyzstan) up to the Ferghana Ridge and the Naryn Basin, Tien Shan at the north-east and to the Pamir-Alay Mountains (Tajikistan) at the west. The closeness of E.tancrei and E.alaicus is supported, whereas specific chromosome and molecular changes, as well as geographic distribution, verified the species status for E.alaicus. The case of Ellobius species accented an unevenness in rates of chromosome and nucleotide changes along with morphological similarity, which is emblematic for cryptic species.

Ontogenetic and Pathogenetic Views on Somatic Chromosomal Mosaicism

Intercellular karyotypic variability has been a focus of genetic research for more than 50 years. It has been repeatedly shown that chromosome heterogeneity manifesting as chromosomal mosaicism is associated with a variety of human diseases. Due to the ability of changing dynamically throughout the ontogeny, chromosomal mosaicism may mediate genome/chromosome instability and intercellular diversity in health and disease in a bottleneck fashion. However, the ubiquity of negligibly small populations of cells with abnormal karyotypes results in difficulties of the interpretation and detection, which may be nonetheless solved by post-genomic cytogenomic technologies. In the post-genomic era, it has become possible to uncover molecular and cellular pathways to genome/chromosome instability (chromosomal mosaicism or heterogeneity) using advanced whole-genome scanning technologies and bioinformatic tools. Furthermore, the opportunities to determine the effect of chromosomal abnormalities on the cellular phenotype seem to be useful for uncovering the intrinsic consequences of chromosomal mosaicism. Accordingly, a post-genomic review of chromosomal mosaicism in the ontogenetic and pathogenetic contexts appears to be required. Here, we review chromosomal mosaicism in its widest sense and discuss further directions of cyto(post)genomic research dedicated to chromosomal heterogeneity.

Karyotypic variability in some species of the genus Chondrilla (Asteraceae)

Karyotypic variability of plants was evaluated in 17 populations of six species of the genus Chondrilla (C. ambigua Fisch., C. brevirostris Fisch, et Mey., C. laticoronata Leonova, C. canescens Kar., Kir., C. juncea, C. pauciflora Ledeb.) in the Astrakhan, Voronezh and Saratov regions, the Republic of Kalmykia, and Western Kazakhstan. It is maintained that C. ambigua is a strict diploid (2n = 2x = 10) species, while its close relative - C. pauciflora - is a strict triploid (2n = 3x = 15) taxon. The research demonstrates that the plants of the apomictic taxa C. brevirostris, C. canescens, C. juncea and C. laticoronata are characterized by the genomic instability in the form of chromosome instability which results in these species’ mixed-ploidy populations.

Chromosomal Copy Number Variation in Saccharomyces pastorianus Is Evidence for Extensive Genome Dynamics in Industrial Lager Brewing Strains

ABSTRACTLager brewing strains ofSaccharomyces pastorianusare natural interspecific hybrids originating from the spontaneous hybridization ofSaccharomyces cerevisiaeandSaccharomyces eubayanus. Over the past 500 years,S. pastorianushas been domesticated to become one of the most important industrial microorganisms. Production of lager-type beers requires a set of essential phenotypes, including the ability to ferment maltose and maltotriose at low temperature, the production of flavors and aromas, and the ability to flocculate. Understanding of the molecular basis of complex brewing-related phenotypic traits is a prerequisite for rational strain improvement. While genome sequences have been reported, the variability and dynamics ofS. pastorianusgenomes have not been investigated in detail. Here, using deep sequencing and chromosome copy number analysis, we showed thatS. pastorianusstrain CBS1483 exhibited extensive aneuploidy. This was confirmed by quantitative PCR and by flow cytometry. As a direct consequence of this aneuploidy, a massive number of sequence variants was identified, leading to at least 1,800 additional protein variants inS. pastorianusCBS1483. Analysis of eight additionalS. pastorianusstrains revealed that the previously defined group I strains showed comparable karyotypes, while group II strains showed large interstrain karyotypic variability. Comparison of three strains with nearly identical genome sequences revealed substantial chromosome copy number variation, which may contribute to strain-specific phenotypic traits. The observed variability of lager yeast genomes demonstrates that systematic linking of genotype to phenotype requires a three-dimensional genome analysis encompassing physical chromosomal structures, the copy number of individual chromosomes or chromosomal regions, and the allelic variation of copies of individual genes.

Molecular and cytogenetic analyses of cryptic species within the Synbranchus marmoratus Bloch, 1795 (Synbranchiformes: Synbranchidae) grouping: species delimitations, karyotypic evolution and intraspecific diversification

The fish species Synbranchus marmoratushas been reported to exist as a species complex due to high intraspecific karyotypic variability in spite of the difficulty or impossibility to distinguish them using morphological traits alone. The goal of this work was to use cytogenetic and molecular methods to determine the species delimitations and understand the karyoevolution ofS. marmoratususing samples collected from distinct Brazilian localities. Among the analyzed specimens, a large degree of cytogenetic variation related to diploid numbers and karyotype structure was observed, with karyotypes showing 2n=42, 44 and 46 chromosomes. In addition, using sequences of three mitochondrial genes, the phylogenetic relationships between every sample with a known karyotype were determined, which revealed significant nucleotide divergence among the karyomorphs. Also, the analyses indicate that chromosomal rearrangements occurred independently within the distinct lineages of S. marmoratuscomplex, which resulted in the appearance of distinct karyotypic variants in a non-linear fashion related to diploid numbers and in the appearance of similar non-homologous chromosomes. Finally, the integration of both molecular cytogenetic and phylogenetic approaches allowed the determination of specific chromosomes possibly involved in rearrangements and a better understanding about the evolutionary processes involved in the differentiation ofSynbranchusgenus.