Lectins: a primer for histochemists and cell biologists.

An experimental observation on selecting binding partners underlies the introduction of the term 'lectin'. Agglutination of erythrocytes depending on their blood-group status revealed the presence of activities in plant extracts that act in an epitope-specific manner like antibodies. As it turned out, their binding partners on the cell surface are carbohydrates of glycoconjugates. By definition, lectins are glycan-specific (mono- or oligosaccharides presented by glycoconjugates or polysaccharides) receptors, distinguished from antibodies, from enzymes using carbohydrates as substrates and from transporters of free saccharides. They are ubiquitous in Nature and structurally widely diversified. More than a dozen types of folding pattern have evolved for proteins that bind glycans. Used as tool, this capacity facilitates versatile mapping of glycan presence so that plant/fungal and also animal/human lectins have found a broad spectrum of biomedical applications. The functional pairing with physiological counterreceptors is involved in a wide range of cellular activities from cell adhesion, glycoconjugate trafficking to growth regulation and lets lectins act as sensors/effectors in host defense.

Type of uromodulin mutation and allelic status influence onset and severity of uromodulin-associated kidney disease in mice.

Uromodulin-associated kidney disease (UAKD) is a dominant heritable renal disease in humans which is caused by mutations in the uromodulin (UMOD) gene and characterized by heterogeneous clinical appearance. To get insights into possible causes of this heterogeneity of UAKD, we describe the new mutant mouse line Umod(C93F), leading to disruption of a putative disulfide bond which is also absent in a known human UMOD mutation, and compare the phenotype of this new mouse line with the recently published mouse line Umod(A227T). In both mutant mouse lines, which were both bred on the C3H background, the Umod mutations cause a gain-of-toxic function due to a maturation defect of the mutant uromodulin leading to a dysfunction of thick ascending limb of Henle's loop (TALH) cells of the kidney. Umod mutant mice exhibit increased plasma urea and Cystatin levels, impaired urinary concentration ability, reduced fractional excretion of uric acid and nephropathological alterations including uromodulin retention in TALH cells, interstitial fibrosis and inflammatory cell infiltrations, tubular atrophy and occasional glomerulo- und tubulocystic changes, a phenotype highly similar to UAKD in humans. The maturation defect of mutant uromodulin leads to the accumulation of immature uromodulin in the endoplasmic reticulum (ER) and to ER hyperplasia. Further, this study was able to demonstrate for the first time in vivo that the severity of the uromodulin maturation defect as well as onset and speed of progression of renal dysfunction and morphological alterations are strongly dependent on the particular Umod mutation itself and the zygosity status.

Stage-specific proteome signatures in early bovine embryo development.

Development of early embryonic stages before activation of the embryonic genome depends on sufficiently stored products of the maternal genome, adequate recruitment and degradation of mRNAs, as well as activation, deactivation, and relocation of proteins. By application of an isobaric tagging for relative and absolute quantification (iTRAQ)-based approach, the proteomes of bovine embryos at the zygote and 2-cell and 4-cell stage with MII oocytes as a reference were quantitatively analyzed. Of 1072 quantified proteins, 87 differed significantly in abundance between the four stages. The proteomes of 2-cell and 4-cell embryos differed most from the reference MII oocyte, and a considerable fraction of proteins continuously increased in abundance during the stages analyzed, despite a strongly attenuated rate of translation reported for this period. Bioinformatic analysis revealed particularly interesting proteins involved in the p53 pathway, lipid metabolism, and mitosis. Verification of iTRAQ results by targeted SRM (selected reaction monitoring) analysis revealed excellent agreement for all five proteins analyzed. By principal component analysis, SRM quantifications comprising a panel of only five proteins were shown to discriminate between all four developmental stages analyzed here. For future experiments, an expanded SRM protein panel will provide the potential to detect developmental disturbances with high sensitivity and enable first insights into the underlying molecular pathways.

The actin family member Arp6 and the histone variant H2A.Z are required for spatial positioning of chromatin in chicken cell nuclei.

The spatial organization of chromatin in the nucleus contributes to genome function and is altered during the differentiation of normal and tumorigenic cells. Although nuclear actin-related proteins (Arps) have roles in the local alteration of chromatin structure, it is unclear whether they are involved in the spatial positioning of chromatin. In the interphase nucleus of vertebrate cells, gene-dense and gene-poor chromosome territories (CTs) are located in the center and periphery, respectively. We analyzed chicken DT40 cells in which Arp6 had been knocked out conditionally, and showed that the radial distribution of CTs was impaired in these knockout cells. Arp6 is an essential component of the SRCAP chromatin remodeling complex, which deposits the histone variant H2A.Z into chromatin. The redistribution of CTs was also observed in H2A.Z-deficient cells for gene-rich microchromosomes, but to lesser extent for gene-poor macrochromosomes. These results indicate that Arp6 and H2A.Z contribute to the radial distribution of CTs through different mechanisms. Microarray analysis suggested that the localization of chromatin to the nuclear periphery per se is insufficient for the repression of most genes.

A transgenic mouse line expressing cre recombinase in pancreatic ß-cells.

Transgenic mouse lines expressing Cre recombinase in a cell-specific and tissue-specific manner are essential tools for studying gene function and for developing suitable models for human diseases. Here, we used an expression cassette containing the full 5' untranslated region of the porcine insulin gene to generate a mouse line expressing Cre recombinase specifically in pancreatic ß-cells by pronuclear DNA microinjection. We obtained a founder animal that transmitted the construct to its descendants in a Mendelian fashion and whose descendants showed a clear activation of ß-galactosidase expression in pancreatic ß-cells after crossing into the ROSA26 lacZ reporter mouse line. Cre expression in other organs was negative except for the kidney, intestine, and the cerebral pons where ß-galactosidase activity was detected in a small percentage of the cells. This new mouse line is a valuable tool for recombination of floxed alleles in pancreatic ß-cells in vivo.

Galectins as tools for glycan mapping in histology: comparison of their binding profiles to the bovine zona pellucida by confocal laser scanning microscopy.

Gene divergence has given rise to the galectin family of mammalian lectins. Since selective binding to distinct ß-galactosides underlies the known bioactivities of galectins, they could find application in cyto- and histochemistry. The pertinent question on the characteristics of their individual reactivity profiles therefore needs to be answered. Toward this end, comparative studies of a panel of galectins in defined systems are required. We here characterise the staining profiles of seven human lectins as well as five natural derivatives originating from proteolytic truncation and serine phosphorylation and one engineered variant. As test system, bovine germinal vesicle oocytes with their glycoprotein envelope (zona pellucida), which presents bi- to tetraantennary complex-type N-glycans with N-acetyllactosamine repeats and core fucosylation, were processed. Technically, confocal laser scanning microscopy was used, first with plant lectins to map the sialylation status. Hereby, α2,3/6-sialylation was detected in the superficial filamentous meshwork of the zona pellucida, while sialic acid-free glycan chains were found to characterise the main inner part of the compact layer of the zona pellucida. Galectin staining was specific and non-uniform. Significant differences in reactivity were detected for the superficial filamentous meshwork and the compact layer of the zona pellucida between galectins-1 to -4 versus galectins-8 and -9. The typical staining profiles intimate a spatially organised display of N-glycans in the different layers of the zona pellucida, underscoring the potential of galectins as cyto- and histochemical tools. Our results encourage further comparative analysis and research to trace the underlying structural and/or topological properties.

What Cyto- and Histochemistry Can Do to Crack the Sugar Code.

As letters form the vocabulary of a language, biochemical 'symbols' (the building blocks of oligo- and polymers) make writing molecular messages possible. Compared to nucleotides and amino acids, sugars have chemical properties that facilitate to reach an unsurpassed level of oligomer diversity. These glycans are a part of the ubiquitous cellular glycoconjugates. Cyto- and histochemically, the glycans' structural complexity is mapped by glycophenotyping of cells and tissues using receptors ('readers', thus called lectins), hereby revealing its dynamic spatiotemporal regulation: these data support the concept of a sugar code. When proceeding from work with plant (haem)agglutinins as such tools to the discovery of endogenous (tissue) lectins, it became clear that a broad panel of biological meanings can indeed be derived from the sugar-based vocabulary (the natural glycome incl. post-synthetic modifications) by glycan-lectin recognition in situ. As consequence, the immunocyto- and histochemical analysis of lectin expression is building a solid basis for the steps toward tracking down functional correlations, for example in processes leading to cell adhesion, apoptosis, autophagy or growth regulation as well as targeted delivery of glycoproteins. Introduction of labeled tissue lectins to glycan profiling assists this endeavor by detecting counterreceptor(s) in situ. Combining these tools and their applications strategically will help to take the trip toward the following long-range aim: to compile a dictionary for the glycan vocabulary that translates each message (oligosaccharide) into its bioresponse(s), that is to crack the sugar code.

Germ-line transmission of lentiviral PGK-EGFP integrants in transgenic cattle: new perspectives for experimental embryology.

Lentiviral vectors are a powerful tool for the genetic modification of livestock species. We previously generated transgenic founder cattle with lentiviral integrants carrying enhanced green fluorescent protein (EGFP) under the control of the phosphoglycerate kinase (PGK) promoter. In this study, we investigated the transmission of LV-PGK-EGFP integrants through the female and male germ line in cattle. A transgenic founder heifer (#562, Kiki) was subjected to superovulation treatment and inseminated with semen from a non-transgenic bull. Embryos were recovered and transferred to synchronized recipient heifers, resulting in the birth of a healthy male transgenic calf expressing EGFP as detected by in vivo imaging. Semen from a transgenic founder bull (#561, Jojo) was used for in vitro fertilization (IVF) of in vitro matured (IVM) oocytes from non-transgenic cows. The rates of cleavage and development to blastocyst in vitro corresponded to 52.0 +/- 4.1 and 24.5 +/- 4.4%, respectively. Expression of EGFP was observed at blastocyst stage (day 7 after IVF) and was seen in 93.0% (281/302) of the embryos. 24 EGFP-expressing embryos were transferred to 9 synchronized recipients. Analysis of 2 embryos, flushed from the uterus on day 15, two fetuses recovered on day 45, and a healthy male transgenic calf revealed consistent high-level expression of EGFP in all tissues investigated. Our study shows for the first time transmission of lentiviral integrants through the germ line of female and male transgenic founder cattle. The pattern of inheritance was consistent with Mendelian rules. Importantly, high fidelity expression of EGFP in embryos, fetuses, and offspring of founder #561 provides interesting tools for developmental studies in cattle, including interactions of gametes, embryos and fetuses with their maternal environment.

Highly sensitive saturation labeling reveals changes in abundance of cell cycle-associated proteins and redox enzyme variants during oocyte maturation in vitro.

Oocyte maturation is a complex process and a critical issue in assisted reproduction techniques (ART) in humans and other mammals. We used a sensitive 2-D DIGE saturation labeling approach including an internal pooled standard for quantitative proteome profiling of immature versus in vitro matured bovine oocytes in six independent samples. The study comprised 48 2D gel images representing 24 DIGE experiments. From 250 ng sample analyzed per gel, quantitative analysis revealed an average of 2244 spots in pH 4-7 images and 1291 spots in pH 6-9 images. Thirty-eight spots with different intensities were detected in total. Spots of a preparative gel from 2200 oocytes were identified by nano-LC-MS/MS analysis. The ten spots which could be unambiguously identified include the Ca2+-binding protein translationally controlled tumor protein, enzymes of the Krebs and pentose phosphate cycles, clusterin, 14-3-3 epsilon, elongation factor-1 gamma, and redox enzymes such as polymorphic forms of GST Mu 5 and peroxiredoxin-3. The cellular distribution of two proteins was determined by confocal laser scanning microscopy. The interesting protein candidates identified by this study may help to improve the in vitro maturation process in order to increase the rate of successful in vitro fertilization and other ART in cattle and other mammals.

Bloom helicase and DNA topoisomerase IIIalpha are involved in the dissolution of sister chromatids.

Bloom's syndrome (BS) is an autosomal disorder characterized by predisposition to a wide variety of cancers. The gene product whose mutation leads to BS is the RecQ family helicase BLM, which forms a complex with DNA topoisomerase IIIalpha (Top3alpha). However, the physiological relevance of the interaction between BLM and Top3alpha within the cell remains unclear. We show here that Top3alpha depletion causes accumulation of cells in G2 phase, enlargement of nuclei, and chromosome gaps and breaks that occur at the same position in sister chromatids. The transition from metaphase to anaphase is also inhibited. All of these phenomena except cell lethality are suppressed by BLM gene disruption. Taken together with the biochemical properties of BLM and Top3alpha, these data indicate that BLM and Top3alpha execute the dissolution of sister chromatids.

Non-random radial arrangements of interphase chromosome territories: evolutionary considerations and functional implications.

In the nucleus of animal and plant cells individual chromosomes maintain a compartmentalized structure. Chromosome territories (CTs), as these structures were named by Theodor Boveri, are essential components of the higher-order chromatin architecture. Recent studies in mammals and non-mammalian vertebrates indicate that the radial position of a given CT (or segments thereof) is correlated with its size, its gene-density and its replication timing. As a representative case, chicken cell nuclei show highly consistent radial chromatin arrangements: gene-rich, early replicating microchromosomes are clustered within the nuclear interior, while gene-poor, later replicating macrochromosomes are preferentially located at the nuclear periphery. In humans, chromosomes 18 and 19 (HSA18 and 19) territories that are of similar size show a distinctly different position in the cell nuclei of lymphocytes and lymphoblastoid cells: the gene-rich and early replicating HSA19 CTs are typically found close to the nuclear center, while the gene-poor and later replicating HSA18 CTs are preferentially located at the nuclear periphery. Recent comparative maps between human and chicken chromosomes revealed that the chicken macrochromosomes 2 and Z contain the genes homologous to HSA18, while the genes on HSA19 are located onto the chicken microchromosomes. These data lend tentative support to the hypothesis that differences in the radial nuclear positions of gene-rich, early replicating and gene-poor, later replicating chromatin have been evolutionarily conserved during a period of more than 300 million years irrespective of the evolution of highly divergent karyotypes between humans and chicken.

Cell arrest and cell death in mammalian preimplantation development: lessons from the bovine model.

BACKGROUND: The causes, modes, biological role and prospective significance of cell death in preimplantation development in humans and other mammals are still poorly understood. Early bovine embryos represent a very attractive experimental model for the investigation of this fundamental and important issue. METHODS AND FINDINGS: To obtain reference data on the temporal and spatial occurrence of cell death in early bovine embryogenesis, three-dimensionally preserved embryos of different ages and stages of development up to hatched blastocysts were examined in toto by confocal laser scanning microscopy. In parallel, transcript abundance profiles for selected apoptosis-related genes were analyzed by real-time reverse transcriptase-polymerase chain reaction. Our study documents that in vitro as well as in vivo, the first four cleavage cycles are prone to a high failure rate including different types of permanent cell cycle arrest and subsequent non-apoptotic blastomere death. In vitro produced and in vivo derived blastocysts showed a significant incidence of cell death in the inner cell mass (ICM), but only in part with morphological features of apoptosis. Importantly, transcripts for CASP3, CASP9, CASP8 and FAS/FASLG were not detectable or found at very low abundances. CONCLUSIONS: In vitro and in vivo, errors and failures of the first and the next three cleavage divisions frequently cause immediate embryo death or lead to aberrant subsequent development, and are the main source of developmental heterogeneity. A substantial occurrence of cell death in the ICM even in fast developing blastocysts strongly suggests a regular developmentally controlled elimination of cells, while the nature and mechanisms of ICM cell death are unclear. Morphological findings as well as transcript levels measured for important apoptosis-related genes are in conflict with the view that classical caspase-mediated apoptosis is the major cause of cell death in early bovine development.

Specific transgene expression in mouse pancreatic beta-cells under the control of the porcine insulin promoter.

The availability of regulatory sequences directing tissue-specific expression of transgenes in genetically modified mice and large animals is a prerequisite for the development of adequate models for human diseases. The rat insulin 2 gene (Ins2) promoter, widely used to achieve transgene expression in pancreatic beta-cells of mice, also directs expression to extrapancreatic tissues and performs poorly in isolated pancreatic islets of human, mouse, and pig. To evaluate whether the full 5' untranslated region (UTR) of the porcine insulin gene (INS) confers robust and specific expression in beta-cells we generated an expression cassette containing 1500bp of the porcine INS 5' UTR and the 3' UTR of the bovine growth hormone gene (GH). The cassette was designed to allow easy exchange of the sequences to be expressed and easy removal of the vector backbone from the expression cassette. To evaluate the properties of the cassette, we initially inserted a cDNA encoding human betacellulin, a growth factor known to affect structural and functional parameters of beta-cells. After confirming the functionality and specificity of the construct in vitro, transgenic mouse lines were generated by pronuclear DNA microinjection. Using RT-PCR, immunohistochemistry and immunofluorescence, we show that transgenic mice expressed human betacellulin exclusively in beta-cells. Confirming the proposed insulinotropic effect of betacellulin, transgenic mice showed improved glucose tolerance. We conclude that the newly designed expression cassette containing 1500bp of the porcine insulin promoter 5' UTR confers robust and specific transgene expression to beta-cells in vitro and in transgenic mice.

Characterization of chromosome structures of Falconinae (Falconidae, Falconiformes, Aves) by chromosome painting and delineation of chromosome rearrangements during their differentiation.

Karyotypes of most bird species are characterized by around 2n = 80 chromosomes, comprising 7-10 pairs of large- and medium-sized macrochromosomes including sex chromosomes and numerous morphologically indistinguishable microchromosomes. The Falconinae of the Falconiformes has a different karyotype from the typical avian karyotype in low chromosome numbers, little size difference between macrochromosomes and a smaller number of microchromosomes. To characterize chromosome structures of Falconinae and to delineate the chromosome rearrangements that occurred in this subfamily, we conducted comparative chromosome painting with chicken chromosomes 1-9 and Z probes and microchromosome-specific probes, and chromosome mapping of the 18S-28S rRNA genes and telomeric (TTAGGG)( n ) sequences for common kestrel (Falco tinnunculus) (2n = 52), peregrine falcon (Falco peregrinus) (2n = 50) and merlin (Falco columbarius) (2n = 40). F. tinnunculus had the highest number of chromosomes and was considered to retain the ancestral karyotype of Falconinae; one and six centric fusions might have occurred in macrochromosomes of F. peregrinus and F. columbarius, respectively. Tandem fusions of microchromosomes to macrochromosomes and between microchromosomes were also frequently observed, and chromosomal locations of the rRNA genes ranged from two to seven pairs of chromosomes. These karyotypic features of Falconinae were relatively different from those of Accipitridae, indicating that the drastic chromosome rearrangements occurred independently in the lineages of Accipitridae and Falconinae.

Leptin promotes meiotic progression and developmental capacity of bovine oocytes via cumulus cell-independent and -dependent mechanisms.

Leptin has been shown to exert positive effects during the maturation of bovine oocytes, influencing blastocyst development, apoptosis, and the transcript levels of developmentally important genes. The present study was conducted to characterize further the mechanisms of leptin action on oocytes and the role of cumulus cells (CCs) in this context. In the first series of experiments, cumulus-oocyte complexes (COCs) were matured in serum-free medium that contained 0, 1 or 10 ng/ml leptin or in medium that was supplemented with 10% (v/v) estrus cow serum (ECS). Leptin concentrations of 1 and 10 ng/ml stimulated the meiotic progression of oocytes. Moreover, TUNEL staining demonstrated that these leptin doses reduced the proportion of apoptotic CCs. In the second series of experiments, COCs or denuded oocytes (DOs) were matured in the presence of 0 or 10 ng/ml leptin. The percentages of COCs and DOs with extruded polar bodies were increased by leptin. In contrast, positive effects of leptin on fertilization rates and blastocyst development were only observed after treatment of COCs but not of DOs. Leptin treatment of COCs consistently enhanced blastocyst development even after parthenogenetic activation of oocytes or after the removal of CCs before fertilization. The proportion of polyspermic oocytes was not affected by leptin treatment or oocyte denudation. In the third series of experiments, COCs were matured in the presence of 0, 1 or 10 ng/ml leptin. The transcript levels of specific genes were determined by reverse transcriptase-quantitative PCR (RT-qPCR) analysis of cumulus cells and single oocytes. Leptin treatment increased the levels of FAS, FASLG, and STAT3 transcripts in oocytes, but did not affect the LEPR, BAX, and BIRC4 mRNA concentrations. In cumulus cells, leptin treatment increased the mRNA levels for LEPR, STAT3, BAX, BIRC4, and FAS, but did not alter FASLG mRNA abundance. In conclusion, leptin differentially regulates gene expression in oocytes and cumulus cells. Moreover, leptin enhances both oocyte maturation and developmental capacity via cumulus cell-independent and -dependent mechanisms.

Quantitative monitoring of pluripotency gene activation after somatic cloning in cattle.

The development of somatic cell nuclear transfer (SCNT) embryos critically depends on appropriate reprogramming and expression of pluripotency genes, such as Pou5f1/POU5F1 (previously known as Oct4/OCT4). To study POU5F1 transcription activation in living bovine SCNT embryos without interference by maternal POU5F1 mRNA, we generated chromosomally normal fetal fibroblast donor cells stably carrying a mouse Pou5f1 promoter-driven enhanced green fluorescent protein (EGFP) reporter gene at a single integration site without detectable EGFP expression. Morphologic and quantitative analyses of whole-mount SCNT embryos by confocal microscopy revealed robust initial activation of the Pou5f1 reporter gene during the fourth cell cycle. In Day 6 SCNT embryos EGFP expression levels were markedly higher than in Day 4 embryos but varied substantially between individual embryos, even at comparable cell numbers. Embryos with low EGFP levels had far more morphologically abnormal cell nuclei than those with high EGFP levels. Our data strongly suggest that bovine SCNT embryos consistently start activation of the POU5F1 promoter during the fourth cell cycle, whereas later in development the expression level substantially differs between individual embryos, which may be associated with developmental potential. In fibroblasts from phenotypically normal SCNT fetuses recovered on Day 34, the Pou5f1 reporter promoter was silent but was activated by a second round of SCNT. The restoration of pluripotency can be directly observed in living cells or SCNT embryos from such Pou5f1-EGFP transgenic fetuses, providing an attractive model for systematic investigation of epigenetic reprogramming in large mammals.

The chicken leukocyte receptor complex: a highly diverse multigene family encoding at least six structurally distinct receptor types.

The chicken Ig-like receptors (CHIR) have been described as two Ig domain molecules with long cytoplasmic tails containing inhibitory motifs. In this study, we demonstrate that CHIR form a large family, with multiple members showing great sequence variability among members as well as a great diversity in domain organization and properties of the transmembrane and cytoplasmic segments. We characterize various novel receptor types with motifs indicative of inhibitory, activating, or both functions. In addition to the inhibitory receptors with two ITIM, receptors with a single immunoreceptor tyrosine-based switch motif or receptors lacking a cytoplasmic domain were isolated. Activating receptors with a short cytoplasmic domain and a transmembrane arginine assembled with the newly identified chicken FcepsilonRIgamma chain. Three bifunctional receptor types were characterized composed of one or two C2-type Ig-like domains, a transmembrane region with a positively charged residue and combinations of cytoplasmic motifs such as ITIM, immunoreceptor tyrosine-based switch motif, and YXXM. RT-PCR revealed distinct expression patterns of individual CHIR. All receptor types shared a conserved genomic architecture, and in single Ig domain receptors a pseudoexon replaced the second Ig exon. Southern blot analyses with probes specific for the Ig1 domain were indicative of a large multigene family. Of 103 sequences from the Ig1 domain of a single animal, 41 unique sequences were obtained that displayed extensive variability within restricted Ig regions. Fluorescence in situ hybridization localized the CHIR gene cluster to microchromosome 31 and identified this region as orthologous to the human leukocyte receptor complex.

Chromosome reshuffling in birds of prey: the karyotype of the world's largest eagle (Harpy eagle, Harpia harpyja) compared to that of the chicken (Gallus gallus).

Like various other diurnal birds of prey, the world's largest eagle, the Harpy (Harpia harpyja), presents an atypical bird karyotype with 2n=58 chromosomes. There is little knowledge about the dramatic changes in the genomic reorganization of these species compared to other birds. Since recently, the chicken provides a "default map" for various birds including the first genomic DNA sequence of a bird species. Obviously, the gross division of the chicken genome into relatively gene-poor macrochromosomes and predominantly gene-rich microchromosomes has been conserved for more than 150 million years in most bird species. Here, we present classical features of the Harpy eagle karyotype but also chromosomal homologies between H. harpyja and the chicken by chromosome painting and comparison to the chicken genome map. We used two different sets of painting probes: (1) chicken chromosomes were divided into three size categories: (a) macrochromosomes 1-5 and Z, (b) medium-sized chromosomes 6-10, and (c) 19 microchromosomes; (2) combinatorially labeled chicken chromosome paints 1-6 and Z. Both probe sets were visualized on H. harpyja chromosomes by multicolor fluorescence in situ hybridization (FISH). Our data show how the organization into micro- and macrochromosomes has been lost in the Harpy eagle, seemingly without any preference or constraints.

Precise identification of chicken chromosomes in the lampbrush form using chromosome painting probes.

Chromosome painting probes specific for macrochromosomes 1, 2, 3, 4, 5, and Z were applied to both mitotic and lampbrush chromosomes of the chicken (Gallus gallus domesticus). Five autosomal macrobivalents and sex chromosome Z in the lampbrush phase were identified and their correspondence to the target chromosomes in the metaphase of mitosis was shown. Nascent transcripts on lateral loops of the target lampbrush chromosome were intensively labelled when the hybridization was performed without RNase A treatment according to the DNA/(DNA + RNA) hybridization protocol.