Interstitial Bands Research Articles

Heterochromatin patterns in four diploid Zephyranthes species with different basic chromosome number (Amaryllidaceae)

Diverse species-specific karyotypes have been reported within Zephyranthes Herb., as well as different basic chromosome numbers (x = 5, 6, 7, and 9), with x = 6 being the most common. The aim of this work was to analyze the constitutive heterochromatin (C-Het) pattern of karyotypes in four diploid Zephyranthes species. For this purpose, a cytomolecular analysis of the karyotypes of Z. andalgalensis (2n = 2x = 12 = 4 m + 2 sm), Z. chacoensis (2n = 2x = 12 = 3 m + 2 sm + 1 st), Z. robusta (2n = 2x = 12 = 3 m + 2 sm + 1 st), and Z. pedunculosa (2n = 2x = 14 = 1 m + 3 sm + 3 st) was performed for the first time. All the species analyzed showed CMA+ terminal bands that could be distinguished by their heterochromatin pattern. Interestingly, DAPI+ interstitial bands were also found in the karyotype of Z. robusta. The four Zephyranthes C-Het patterns analyzed show that diploid species have little GC-rich heterochromatin, which is generally associated with terminal satellites, and that AT-rich heterochromatin is rare. The dysploidy evolutionary change between two basic chromosome numbers (x = 6 and 7) is discussed in the present study.

Experimental and theoretical divulging of electronic structure and optical properties of Zn-doped SnSe thermoelectric materials

Electron momentum densities (EMDs) of undoped and Zn-doped SnSe are measured using a 100 mCi 241Am Compton spectrometer. Various density functional theories and hybrid exchange and correlation potentials (LDA, PBE, PBEsol, PBE0, and B3LYP) within the linear combinations of atomic orbitals (LCAO) calculations have been attempted to compute Compton profiles (CPs) and electronic structure of the doped and undoped SnSe. Among all the Compton line shapes predicted using first principles, B3LYP approximation-based EMDs are found to be in a better reconciliation with the CP measurements. Experimental data is also analyzed in terms of localization of Zn-d states. Going beyond the LCAO method, the density of state (DOS), energy bands, reflectance, dielectric constant, and absorption coefficient for Zn-doped (Sn0.97Zn0.03Se and Sn0.95Zn0.05Se) and undoped SnSe are computed using the FP-LAPW-mBJ method. It is seen that Sn-5s and Se-4p orbitals are responsible for the formation of the indirect band gap. Interestingly, Zn doping in SnSe (Sn0.97Zn0.03Se and Sn0.95Zn0.05Se) leads to interstitial bands in the low energy side of the conduction region leading to electron trapping centres and reduction of band gap (from 0.816 to 0.508eV in case of FP-LAPW-mBJ scheme and 1.152 to 0.510 eV in case of LCAO-B3LYP scheme). Our works evidently support the positive effect of Zn doping in enhancing the electronic and thermoelectric properties of the SnSe by forming interstitial bands. Apart from this, undoped and Zn-doped SnSe can also be used for solar cells as an absorber material and detection of ultraviolet (B and C) rays. Due to the formation of interstitial bands induced trapping centres, Zn-doped SnSe can also be uniquely employed in thermoluminescence devices (TLDs).

Classic and molecular cytogenetic analysis unveils different chromosome rearrangements shaping the karyotype ofMonobia angulosaSaussure, 1852 (Hymenoptera: Vespidae: Eumeninae)

AbstractCytogenetic molecular studies involving hymenopterans have improved our knowledge about the composition, organization and evolution of the genomes of these insects. However, few cytogenetic studies have been performed in solitary wasps Eumeninae, which represents the most diverse subfamily of Vespidae. In this study, we describe the karyotype of the wasp Monobia angulosa using conventional and molecular cytogenetic techniques, in order to contribute to the understanding of chromosomal variation in this solitary wasp. The results indicated an odd chromosome number of 2n = 27 in females and n = 14 in males. The heterochromatin was located in centromeric/pericentromeric regions, and also in short arms in females and males. Chromomycin A3 staining revealed four and two bright interstitial bands in females and males, respectively. One of these marks corresponded to 18S rDNA clusters in both females and males. The microsatellite (GA)15 was located exclusively in the euchromatic regions in females and males. These results allowed us to suggest the occurrence of different chromosomal rearrangements, such as duplication/deletion of heterochromatic and euchromatic segments due to unequal crossing-over and Robertsonian rearrangements, to explain the origin of the chromosomal variations detected in the karyotype of this species. The few molecular cytogenetic studies already performed with Eumeninae wasps have revealed extraordinary karyotypic plasticity in this insect group.

DAPI Banding Pattern of Chromosomes in Several Brassicaceae Species

BRASSICACEAE family includes a number of the most important Brassica cultivars such as canola, mustard and cabbage, and Arabidopsis thaliana as plant biology model species. Chromosome banding is the most probable protocol for karyotyping and to distinguish numerical chromosome abnormalities, duplications, inversions or deletions of chromosome parts, or exchanging a part from one to another chromosome as well. The aim of this study is to illustrate the DAPI banding patterns in 16 Brassicaceae species with small chromosome size, and they have different origin, ploidy level (chromosome number varies from 2n= 14 to 2n= 32). These species belong to five tribes (Brassiceae, Sisymbrieae, Lepidieae, Arabideae and Alyssea. The aim of this study is to illustrate the DAPI banding patterns in 16 Brassicaceae species with small chromosome size, and they have different origin and ploidy level (chromosome number varies from 2n= 14 to 2n= 32). In the current study we investigated different genera belong to five tribes of the family in regard to the position of regions as by using DAPI staining. It was excluded that most of plants with small chromosomes have mostly a centromeric bands and the more the chromosome size the more tendency to have interstitial bands.

Chromosomal Mapping of Rex Retrotransposons in Tambaqui (Colossoma macropomum Cuvier, 1818) Exposed to Three Climate Change Scenarios

Greenhouse gas emissions are known to influence the planet's temperature, mainly due to human activities. To allow hypothesis testing, as well as to seek viable alternatives for mitigation, the Intergovernmental Panel on Climate Change (IPCC) suggested 3 main scenarios for changes projected for the year 2100. In this paper, we subjected Colossoma macropomum Cuvier, 1818 (tambaqui) individuals in a microcosm to IPCC scenarios B1 (mild), A1B (intermediate), and A2 (extreme) to test possible impacts on their genome. We found chromosome heterochromatinization in specimens exposed to the A2 scenario, where terminal blocks and interstitial bands were detected on several chromosome pairs. The behavior of Rex1 and Rex3 sequences differed between the test scenarios. Hybridization of Rex1 resulted in diffuse signals which showed a gradual increase in the tested scenarios. For Rex3, an increase was observed in the A2 scenario with blocks on several chromosomes, some of which coincided with heterochromatin. Heterochromatinization is an epigenetic process, which may have occurred as a mechanism for regulating Rex3 activity. The signal pattern of Rex6 did not change, suggesting that other mechanisms are acting to regulate its activity.

Betavoltaic Enhancement Using Defect-Engineered TiO2 Nanotube Arrays through Electrochemical Reduction in Organic Electrolytes.

Utilizing high-energy beta particles emitted from radioisotopes for long-lifetime betavoltaic cells is a great challenge due to low energy conversion efficiency. Here, we report a betavoltaic cell fabricated using TiO2 nanotube arrays (TNTAs) electrochemically reduced in ethylene glycol electrolyte (EGECR-TNTAs) for the enhancement of the betavoltaic effect. The electrochemical reduction of TNTAs using high cathodic bias in organic electrolytes is indeed a facile and effective strategy to induce in situ self-doping of oxygen vacancy (OV) and Ti3+ defects. The black EGECR-TNTAs are highly stable with a significantly narrower band gap and higher electrical conductivity as well as UV-vis-NIR light absorption. A 20 mCi of 63Ni betavoltaic cell based on the reduced TNTAs exhibits a maximum ECE of 3.79% with open-circuit voltage of 1.04 V, short-circuit current density of 117.5 nA cm-2, and a maximum power density of 39.2 nW cm-2. The betavoltaic enhancement can be attributed to the enhanced charge carrier transport and separation as well as multiple exciton generation of electron-hole pairs due the generation of OV and Ti3+ interstitial bands below the conductive band of TiO2.

Genomic Organization of Repetitive DNA in Woodpeckers (Aves, Piciformes): Implications for Karyotype and ZW Sex Chromosome Differentiation

Birds are characterized by a low proportion of repetitive DNA in their genome when compared to other vertebrates. Among birds, species belonging to Piciformes order, such as woodpeckers, show a relatively higher amount of these sequences. The aim of this study was to analyze the distribution of different classes of repetitive DNA—including microsatellites, telomere sequences and 18S rDNA—in the karyotype of three Picidae species (Aves, Piciformes)—Colaptes melanochloros (2n = 84), Colaptes campestris (2n = 84) and Melanerpes candidus (2n = 64)–by means of fluorescence in situ hybridization. Clusters of 18S rDNA were found in one microchromosome pair in each of the three species, coinciding to a region of (CGG)10 sequence accumulation. Interstitial telomeric sequences were found in some macrochromosomes pairs, indicating possible regions of fusions, which can be related to variation of diploid number in the family. Only one, from the 11 different microsatellite sequences used, did not produce any signals. Both species of genus Colaptes showed a similar distribution of microsatellite sequences, with some difference when compared to M. candidus. Microsatellites were found preferentially in the centromeric and telomeric regions of micro and macrochromosomes. However, some sequences produced patterns of interstitial bands in the Z chromosome, which corresponds to the largest element of the karyotype in all three species. This was not observed in the W chromosome of Colaptes melanochloros, which is heterochromatic in most of its length, but was not hybridized by any of the sequences used. These results highlight the importance of microsatellite sequences in differentiation of sex chromosomes, and the accumulation of these sequences is probably responsible for the enlargement of the Z chromosome.

Utilization of Karyotypic Analysis of C- Banded of Egyptian Clover Chromosomes and Karyotype Characterization of Fixed Isolation Distances

The present study was carried out to study the karyotype characterization of berseem Serw 1 cultivar as male parent and Gemmiza 1 cultivar as female parent, using the satellite chromosomes in Serw 1 as a marker to find out the accurate isolation distances in Gemmiza 1 as female parent, and their first generations polycrosses along 50,100,150 and 200 meter distances from the male parent cultivars (Serw1). The satellites chromsoms were previously found in Serw 1, where Gemmizal has not satellite chromosoms. Satellite chromosoms were not found in the first generations of (Gemmiza 1 x Serw 1) which planted in 100,150,200 m away from the male parent Serw 1, but the satellite chromosomes were found as a markers in the segregated generations of the polycrossed via 50 meter distance (Chromosome number 4 SAT). Also, C – banding technique was used to indentify the parental chromosomes of Serw 1 , Gemmizal and the resulted generations to confirm for how long the pollen grains of Serw 1 could be transfered under the open pollinated conditions for first generation polycrosses along 50,100, 150 and 200 meter distances. In the present study, changes in the chromosomal characterization were detected that indicating pollen grains were transferred from the male parent plants (Serw 1) to the female parent plants, Gemmiza 1 (50 meter distance, at 50 meter distance were recorded the highest percentage of cells containing chromosomal aberrations 24%), significant difference was found in chromosome area. Chromosome length and mitotic index between the isolation distances in all cases, data indicated that differences ranged from the highest score of chromosome area in the variety Serw 1 (male parent plants) to the lowest estimate in the 200 meter, studied isolation distances exhibited variations ranged from the highest score of chromosome length in Serw 1 (male parent plants) to the lowest estimate in the 200 meter distance. The present isolation distance of 50 meter identification of each of the eight pairs of chromosomes of a idiogram. All chromosomes had centromeric bands and a terminal band in the short arm except the satellite chromosome (chromosome Number 4). Interstitial bands were observed in the short arms. Chromosomes 1, 2, 3 and 4 each had one prominent interstitial band in their long arm. The satellite chromosome is easy to identify because of the presence of the secondary constriction. A minstrel degree of minimum recommended isolation distances for Egyptian clover, it includes three minimum distance recommendations : Isolation distance of 200m for foundation seed. Isolation distance of 150m for registered seed. Isolation distance of 100m for certified seed.

Chromosomal analysis of Physalaemus kroyeri and Physalaemus cicada (Anura, Leptodactylidae).

All the species of Physalaemus Fitzinger, 1826 karyotyped up until now have been classified as 2n = 22. The species of the Physalaemus cuvieri group analyzed by C-banding present a block of heterochromatin in the interstitial region of the short arm of pair 5. Physalaemus cicada Bokermann, 1966 has been considered to be a member of the Physalaemus cuvieri species group, although its interspecific phylogenetic relationships remain unknown. The PcP190 satellite DNA has been mapped on the chromosomes of most of the species of the Physalaemus cuvieri group. For two species, Physalaemus cicada and Physalaemus kroyeri (Reinhardt & Lütken, 1862), however, only the chromosome number and morphology are known. Given this, the objective of the present study was to analyze the chromosomes of Physalaemus cicada and Physalaemus kroyeri, primarily by C-banding and PcP190 mapping. The results indicate that Physalaemus kroyeri and Physalaemus cicada have similar karyotypes, which were typical of Physalaemus. In both species, the NORs are located on the long arm of pair 8, and the C-banding indicated that, among other features, Physalaemus kroyeri has the interstitial band on chromosome 5, which is however absent in Physalaemus cicada. Even so, a number of telomeric bands were observed in Physalaemus cicada. The mapping of the PcP190 satellite DNA highlighted areas of the centromeric region of the chromosomes of pair 1 in both species, although in Physalaemus kroyeri, heteromorphism was also observed in pair 3. The cytogenetic evidence does not support the inclusion of Physalaemus cicada in the Physalaemus cuvieri group. In the case of Physalaemus kroyeri, the interstitial band on pair 5 is consistent with the existence of a cytogenetic synapomorphy in the Physalaemus cuvieri species group.

Distribution of constitutive heterochromatin and nucleolar organizer regions in two species of family Gomphidae (Odonata: Anisoptera)

Spermatogonial and primary spermatocyte chromosomes of Paragomphus lineatus (Selys) and Nepogomphus modestus (Selys) of family Gomphidae have been described on the basis of C-banding and NOR staining. Both the species possess 2n (♂) =23, n (♂) =12 without m chromosomes with XO(♂)/XX(♀) type sex determining mechanism. The sex chromosome is the largest element in the whole complement in Paragomphus lineatus but it is medium sized in Nepogomphus modestus. In Paragomphus lineatus, all the autosomal bivalents possess terminal C-bands while X chromosome is C-positive throughout the length but lightly stained in the centre. Similarly, terminal NOR bands are present on all the autosomal bivalents and X chromosome shows terminal NOR bands with large interstitial band. In Nepogomphus modestus, all the autosomal bivalents except one bivalent possess terminal C-bands while X chromosome represents large C-positive region on one end and small C-negative region on the other end. NOR staining shows terminal / non terminal NOR bands on some autosomal bivalents while X chromosome possesses dark NOR band only on one end.

Rye B Chromosomes Influence the Dynamics of Histone H3 Methylation during Microgametogenesis

We have studied the trimethylation dynamics of lysines 4 and 27 of histone H3 in rye with and without B chromosomes (Bs) in root tip mitosis, meiosis, and pollen grain mitosis by immunostaining. In root meristems, H3K4me3 immunolabeling was homogeneous along the chromosome arms of the normal complement (As), with the exception of the pericentromeric and subtelomeric regions which were unlabeled. On the contrary, a signal was observed on the long arm of the B chromosome, in the region where most of the B-specific repeats are located. H3K27me3 immunosignals were observed on the subtelomeric heterochromatic region of the As and the Bs and some interstitial bands of the As. Thus, the terminal region of the Bs showed both signals, whereas the subtelomeric region of the As showed H3K27me3 immunosignals only. During meiosis and first pollen grain mitosis, the immunosignals were observed distributed as in the root tip mitosis in plants with or without Bs. However, we observed remarkable changes in the immunolabeling patterns during the second pollen grain mitosis between 0B and +B plants. In 0B plants, H3K4me3 immunosignals were similarly distributed in the vegetative and generative nuclei. In B-carrying plants, the vegetative nucleus showed a lighter signal than the generative one. In 0B plants, all nuclei of the microgametophyte showed H3K27me3 immunosignals. In B-carrying plants, the generative nucleus and, correspondingly, the second metaphase, anaphase, and sperm nuclei did not show any signal. When the Bs were lost as micronuclei, they did not show any H3K4me3 or H3K27me3 signal. Most remarkably, Bs are able to change the pattern of H3 methylation on K4 and K27 during the second pollen mitosis, resulting in differently labeled sperm nuclei in 0 and +B plants.

Karyotypic diversity and chromosome evolution in the armored catfishes Callichthyinae (Siluriformes, Callichthyidae)

The Callichthyinae subfamily is composed of five genera with a small number of described species. Molecular cytogenetics studies show the scarcity of records for this subfamily. The aim of the present study was to employ cytogenetic parameters in the analysis of three species belonging to the subfamily Callichthyinae sampled from the Parana River (Brazil). Callichthys callichthys had 2n = 56 chromosomes (26 m-sm + 30 st-a); Lepthoplosternum pectorale had 2n = 64 chromosomes (8 m-sm + 56 st-a); and Hoplosternum littorale had 2n = 60 chromosomes (8 m-sm + 52 st-a). Regarding the location of the nucleolar organizer regions (NORs) (Ag-staining and 18S rDNA-FISH), different situations were found: single NORs in H. littorale and C. callichthys; multiple NORs in L. pectorale, with intra-individual and inter-individual variation. Heterochromatin was observed in the centromeric region in the chromosomes of the three species. Equilocal, interstitial bands were also found in H. littorale. Physical mapping of 5S ribo...

Photoluminescence Properties of ZnO Thin Film Prepared by Sol-Gel Route

Temperature dependent photoluminescence (PL) properties of ZnO thin film prepared by sol-gel route were investigated. The excitonic-related emission peak at 3.336 eV dominates the spectra, and is attributed to the recombination of excitons bound to structural defects (DBX). Moreover, its thermal activation energy is 5.7 meV obtained by using least-squares fitting method. Compared to its larger localization energy, we propose that there exists a nonradiative relaxation path with energy released during the formation of DBX. The observed peak position of blue emission is in line with theoretical energy interval between the interstitial zinc level and valence band.

C-banded karyotype and nucleolar organizer regions of Tinca tinca (Cyprinidae) from Turkey

In this study, conventional Giemsa staining, Silver-Nucleolar Organizer Region (Ag-NOR) and C-banding were applied to eight specimens of Tench, Tinca tinca, of Lake Beysehir, and their detailed cytogenetic properties were investigated. It was determined that all of the chromosomes in karyotypes of the samples investigated were bi-armed (metacentric, submetacentric, subtelocentric). Also a secondary constriction was observed on the short arm of the third pair of chromosomes. No morphological difference was identified between sex chromosomes of male and female specimens. All chromosomes of the specimens had centromeric and pericentromeric C-bands. There was an interstitial band on the short arm of a chromosome pair, while all the short arms of three chromosome pairs were C-positive. Heteromorph C-bands were detected in two chromosome pairs. By Ag-nitrate staining, active NOR was identified on the short arm of the number three metacentric chromosome pair of all specimens. However, this active NOR was not rel...

Cloning and characterisation of a novel chromosome end repeat enriched with homopolymeric (dA)/(dT) DNA in Rhynchosciara americana (Diptera: Sciaridae)

Short tandem DNA repeats and telomerase compose the telomere structure in the vast majority of eukaryotic organisms. However, such a conserved organisation has not been found in dipterans. While telomeric DNA in Drosophila is composed of specific retrotransposons, complex terminal tandem repeats are present in chromosomes of Anopheles and chironomid species. In the sciarid Rhynchosciara americana, short repeats (16 and 22 bp long) tandemly arrayed seem to reach chromosome ends. Moreover, in situ hybridisation data using homopolymeric RNA probes suggested in this species the existence of a third putative chromosome end repeat enriched with (dA).(dT) homopolymers. In this work, chromosome micro-dissection and PCR primed by homopolymeric primers were employed to clone these repeats. Named T-14 and 93 % AT-rich, the repetitive unit is 14 bp long and appears organised in tandem arrays. It is localised in five non-centromeric ends and in four interstitial bands of R. americana chromosomes. To date, T-14 is the shortest repeat that has been characterised in chromosome ends of dipterans. As observed for short tandem repeats identified previously in chromosome ends of R. americana, the T-14 probe hybridised to bridges connecting non-homologous polytene chromosome ends, indicative of close association of T-14 repeats with the very end of the chromosomes. The results of this work suggest that R. americana represents an additional example of organism provided with more than one DNA sequence that is able to reach chromosome termini.

Cytogenetic studies of Atlantic mojarras (Perciformes - Gerreidae): chromosomal mapping of 5S and 18S ribosomal genes using double FISH

Fish of the family Gerreidae, mainly species of the genera Diapterus and Eugerres, have high potential for cultivation, because of their saline tolerance. A detailed cytogenetic analysis of Diapterus auratus, Diapterus rhombeus and Eugerres brasilianus was conducted using conventional staining, C-banding, Ag-NOR, AT/GC-specific fluorochrome staining and mapping of ribosomal sequences with 5S and 18S rDNA probes. All the species exhibited symmetrical karyotype, 2n = 48 acrocentric chromosomes. Ag-NORs and 18S rDNA are present in the interstitial position on pair 1 (genus Diapterus) and pair 6 in Eugerres brasilianus. The 5S rDNA sites, located in the interstitial position (pair 11), are conserved in the three species. Heterochromatic regions are similar in the Diapterus species, showing a pattern of reduced and centromeric bands, differing from E. brasilianus, where, in addition to these, more prominent interstitial bands were observed. GC-rich regions are located at ribosomal sites. Karyotypic comparison between Diapterus and Eugerres reveals similarity in chromosomal macrostructure, differing in C-positive heterochromatin distribution and position of 18S sites, indicating the occurrence of structural microrearrangements. Although complementary analyses are needed, the similarities observed for these and other species suggest the possibility of breaking postzygotic barriers and their potential use, through induced interspecific or intergeneric hybridizations.

First report on C‐banding and fluorescent banding in species of Dieuches (Rhyparochrominae: Lygaeidae: Heteroptera)

AbstractAlthough the karyotypes of twelve species of Dieuches Dohrn, 1860 belonging to Rhyparochrominae have been described so far, there is no information about heterochromatin and its characterization in terms of base composition for any of the species. In the present paper, C‐banding and fluorescent banding have been applied for the first time to three species of Dieuches: D. uniguttatus, D. insignis (2n = 12 = 8A + 2m + XY) and D. coloratus (2n = 14 = 10A + 2m + XY). Dieuches uniguttatus and D. insignis show distinct terminal C‐bands along with a few interstitial bands in all the autosomal bivalents, whereas in D. coloratus, one autosomal pair is almost completely heterochromatic, three show C‐positive bands while one is totally euchromatic. The sex chromosomes too show heterogeneity in distribution of C‐heterochromatin among three Dieuches species. Characterization of heterochromatin in D. uniguttatus and D. insignis using DAPI/CMA3 staining reveals that in D. uniguttatus, C‐ heterochromatin blocks of all the autosomal bivalents, which are predominantly A–T rich, whereas in D. insignis, these are rich both in A–T and G–C. In D. uniguttatus, sex chromosomes X and Y have localized G–C rich regions whereas in D. insignis, these are scattered in X and absent in Y. As variations in the heterochromatin represent the main source of karyological differentiation among and within species, it seems that there occurred extensive redistribution of heterochromatin within the complement as the three species evolved. There is need for cytological details of more species to understand evolutionary aspects in the genus Dieuches.

Lymphoma‐Associated Polymyositis in Dogs

Lymphoma‐Associated Polymyositis in Dogs

Cytogenetic study of two species of the family Pimelodidae (Siluriformes) collected in lago Guaíba, Rio Grande do Sul, Brazil

A cytogenetic study was conducted on specimens of Parapimelodus nigribarbis and Pimelodus maculatus collected in the lago Guaíba drainage, Porto Alegre, Rio Grande do Sul, Brazil. The two species had a diploid number of 56 chromosomes, with P. nigribarbis showing a karyotype of 20m + 20sm + 4st + 12a with FN of 100, and P. maculatus showing a karyotype of 24m + 20sm + 6st + 6a with FN of 106. NORs were demonstrated in both species in only one pair of subtelocentric chromosomes, in the terminal region of the long arm, which was coincident with C- banding and CMA3 staining, while DAPI staining was negative in these regions. Parapimelodus nigribarbis had a greater number of heterochromatic bands than did P. maculatus, which were distributed mainly in the terminal regions, where the latter species showed an interstitial band on the short arm of the first metacentric pair. C-banding plus CMA3 demonstrated heterochromatin that was associated with GC-rich NORs in both P. nigribarbis and P. maculatus, although other fluorescent regions were also observed in the former species. With C-banding plus DAPI, various chromosomal regions were stained in the two species, along with interstitial staining in P. maculatus, indicating that heterochromatin contained a greater quantity of AT-rich regions.

Chromosomal evolution in parrots, lorikeets and cockatoos (Aves: Psittaciformes)

The karyotypes of 9 species of parrot (Psittacidae). lorikeet (Lorudae) and cockatoo (Cacatuidae) are presented together with C-band data on 5 of the species. All cockatoos possess a similar karyotype, which is very distinct from those observed in lorikeets and parrots. Even though there is considerable karyotypic diversity within the parrots (Psittacidae) an ancestral karyotype can still be deduced. This ancestral karyotype appears to be shared with the lorikeets (Loriidae), indicating that parrots and lorikeets are closely related. C-band variation is greatest within the cockatoos (Cacatuidae) and involves both centromeric and interstitial bands. The pattern of C-band distribution on the Z-chromosomes is also distinctive in both Cacatuildae and Psittacidae; its possiblle significance is discussed.