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Kayotypes of four neotropical teiid lizard species (Tupinambinae) were herein studied after conventional as well as silver staining and CBG-banding: Crocodilurus amazonicus (2n = 34), Tupinambis teguixin (2n = 36), Tupinambis merianae and Tupinambis quadrilineatus (2n = 38). The karyological data for T. quadrilineatus as well as those obtained using differential staining for all species were unknown until now. The karyotypes of all species presented 12 macrochromosomes identical in morphology, but differed in the number of microchromosomes: 22 in C. amazonicus, 24 in T. teguixin and 26 in T. quadrilineatus and T. merianae. The Ag-NOR located at the secondary constriction at the distal end of pair 2 is shared by all species, contrasting with the variability observed for this character in species of the related Teiinae. CBG-banding revealed a species-specific pattern in T. quadrilineatus with conspicuous interstitial C-blocks at the proximal region of the long arm of pair 4 and the whole heterochromatic short arm of pair 6. The karyological data reported here corroborates the relationship hypothesis obtained for Tupinambis based on molecular characters. T. teguixin presents the putative ancestral karyotype for the genus with 2n = 36 whereas T. merianae and T. quadrilineatus exhibit 2n = 38, due to an additional pair of microchromosomes.

Chromosomes of Triportheus nematurus, a fish species from family Characidae, were analyzed in order to establish the conventional karyotype, location of C-band positive heterochromatin, Ag-NORs, GC- and AT-rich sites, and mapping of 18S and 5S rDNA with fluorescence in situ hybridization (FISH). The diploid number found was 2n = 52 chromosomes in both males and females. However, the females presented a pair of differentiated heteromorphic chromosomes, characterizing a ZZ/ZW sex chromosome system. The Z chromosome was metacentric and the largest one in the karyotype, bearing C-positive heterochromatin at pericentromeric and telomeric regions. The W chromosome was middle-sized submetacentric, appearing mostly heterochromatic after C-banding and presenting heterogeneous heterochromatin composed of GC- and AT-rich regions revealed by fluorochrome staining. Ag-NORs were also GC-rich and surrounded by heterochromatic regions, being located at the secondary constriction on the short arms of the second chromosome pair, in agreement with 18S rDNA sites detected with FISH. The 18S and 5S rDNA were aligned in tandem, representing an uncommon situation in fishes. The results obtained reinforce the basal condition of the ZZ/ZW sex system in the genus Triportheus, probably arisen prior to speciation in the group.

The speciose Brazilian Elateridae fauna is characterized by high karyotypic diversity, including one species (Chalcolepidius zonatus Eschscholtz, 1829) with the lowest diploid number within any Coleoptera order. Cytogenetic analysis of Conoderus dimidiatus Germar, 1839, C. scalaris (Germar, 1824,) C. ternarius Germar, 1839, and C. stigmosus Germar, 1839 by standard and differential staining was performed with the aim of establishing mechanisms of karyotypic differentiation in these species. Conoderus dimidiatus, C. scalaris, and C. ternarius have diploid numbers of 2n(male) = 17 and 2n(female) = 18, and a X0/XX sex determination system, similar to that encountered in the majority of Conoderini species. The karyotype of C. stigmosus was characterized by a diploid number of 2n = 16 and a neoXY/neoXX sex determination system that was highly differentiated from other species of the genus. Some features of the mitotic and meiotic chromosomes suggest an autosome/ancestral X chromosome fusion as the cause of the neoXY system origin in C. stigmosus. C-banding and silver impregnation techniques showed that the four Conoderus species possess similar chromosomal characteristics to those registered in most Polyphaga species, including pericentromeric C band and autosomal NORs. Triple staining techniques including CMA3/DA/DAPI also provided useful information for differentiating these Conoderus species. These techniques revealed unique GC-rich heterochromatin associated with NORs in C. scalaris and C. stigmosus and CMA3-heteromorphism in C. scalaris and C. ternarius.

The karyotype, nucleolar organizer region (NOR) location and C-banding pattern of two species of Hylodes (H. phyllodes and H. asper) and two of Crossodactylus (Crossodactylus sp. n. and Crossodactylus cf. caramaschi) were studied. All species had a diploid number of 2n = 26, with differences in the chromosomal morphology of the Hylodes species while the two Crossodactylus species were cytogenetically indistinguishable. The NOR was located on pair 1 in both species of Hylodes, and on pair 8 in the Crossodactylus species. In the latter, the NOR was heteromorphic between the homologues. The NOR was coincident with a secondary constriction in the four species. Except to H. phyllodes, such secondary constrictions were clearly seen strongly stained after C-banding treatment. The C-banding pattern varied between the two species of Hylodes, but was identical in the Crossodactylus species. The results from conventionally stained karyotypes confirmed the uniformity within the genus Crossodactylus, and the relatively conserved karyotypes within Hylodes, in agreement with other literature reports. We conclude that the cytogenetic data do not provide further evidence which could be useful to corroborate the supposed relationships between the hylodines and dendrobatids since there are no unambiguous homeologies between the karyotypes of these groups.

We analysed samples of Aedes aegypti from Sao Jose do Rio Preto and Franca (Brazil) by C‐banding and Ag‐banding staining techniques. C‐banding pattern of Ae.aegypti from Sao Jose do Rio Preto examined in metaphase cells differed from Franca. The chromosomes 2, 3 and X showed centromeric C‐bands in both populations, but a slightly stained centromeric band in the Y chromosome was observed only in Sao Jose do Rio Preto. In addition, the X chromosome in both populations and the Y chromosome of all individuals from Sao Jose do Rio Preto showed an intercalary band on one of the arms that was absent in Franca. An intercalary, new band, lying on the secondary constriction of chromosome 3 was also present in mosquitoes of both populations. The comparison of the present data with data in the literature for Ae.aegypti from other regions of the world showed that they differ as to the banding pattern of sex chromosomes and the now described intercalary band in chromosome 3. The observations suggested that the heterochromatic regions of all chromosomes are associated to constitute a single C‐banded body in interphase cells. Ag‐banding technique stained the centromeric regions of all chromosomes (including the Y) and the intercalary C‐band region of the X chromosome in both populations. As Ae.aegypti populations are widespread in a great part of the world, the banding pattern variations indicate environmental interactions and may reveal both the chromosome evolutionary patterns in this species and the variations that may interfere with its vector activity.

The chromosomes of Japanese flounder, Paralichthys olivaceus, were examined by conventional differential staining methods including G-, Q-, C-, silver (Ag)-, fluorochrome, and replication R-bandings and by fluorescence in situ hybridization (FISH) with 5S and 18S rDNAs and telomeric DNA as probes. Replication R-banding substantially made it possible to identify 24 homologous pairs by their RBG-banding pattern and relative length. Both rDNA loci were mapped to chromosome 1, where 5S and 18S rDNA loci were located at the centromeric region and secondary constriction, respectively. C-banding revealed that both rDNA loci were heterochromatic, and 18S rDNA loci were positive for chromomycin A(3) but negative for 4',6-diamidino-2-phenylindole (DAPI) staining. Telomeric FISH signals were observed at all chromosome ends and at the interstitial region of some chromosomes. The observed results were discussed in relation to the karyotype evolution in the order Pleuronectiformes.

This paper describes the karyotype analysis of Haemulon aurolineatum, Haemulon bonariensis and Haemulon plumierii, by Giemsa staining, C-banding, Ag-staining and fluorescent in situ hybridization (FISH), to locate the 18S and 5S rRNA genes. Diploid modal count in the three species was 2n = 48 acrocentric elements. Except for pair 24, which exhibited an unmistakable secondary constriction in all three species, it was not possible to classify them as homologous to each other because differences in chromosome size were too slight between adjacent pairs within a size-graded series. Ag-NOR clusters were located in pair 24 in the three species with signal located on the secondary constriction of these chromosomes. C-banding demonstrated that the three species share the same distribution pattern of the constitutive heterochromatin with centromeric heterochromatic blocks in the 23 chromosome pairs and a pericentromeric block in pair 24 which is coincident with the NORs. FISH experiments showed that 18S rDNA sequences were located coincident with the Ag-NOR site in the three species; however, differences in both the number and chromosome distribution of 5S-rDNA cluster were detected among them. Our data suggest that chromosome evolution of Haemulon has been preserved from major changes in the karyotypic macrostructure, whereas microstructural changes have occurred.

Five distinct classes of secondary constriction are found in the hylid frogs from the genera Litoria and Cyclorana, each of which is defined by its C-banding pattern and morphology (King, 1980, 1987). In-situ hybridization experiments utilizing 18S + 28S copy RNA probes derived from Xenopus and Drosophila rDNA templates, were made on nine species of frogs possessing the major constriction types. Types 1, 2, 4, and 5 are confirmed as being NORs. These results also indicate that type 1 and 2 constriction types are not differentially despiralized as previously suggested, but show absolute differences in the quantity of ribosomal DNA present. This variation took two forms, deletion polymorphism and amplification polymorphism. These differences were observed between homologues within cells and between cells within individuals. Animals possessing these 'despiralized' constrictions are therefore mosaics for both deletion and amplification polymorphisms. Polymorphism frequencies vary greatly between constriction types. Some specimens have a higher level of presence/absence heterozygosity, (L. moorei, type 2, L. nannotis type 5, L. raniformis (animal A, pair 8 type 2), than do others (L. peronii, L. rothii, L. caerulea). The above species also vary markedly in the degree and frequency of amplification of the NORs. The type 4 constrictions analysed (L. coplandi, L. lesueuri and C. novaehollandiae) have a particularly low frequency of presence/absence heterozygosity, and they have fewer size heteromorphisms between homologues. The type 3 ephemeral constrictions did not hybridize to cRNA probes at any stage. In all but one of the species studied, a single pair of chromosomes possessed an NOR. However, in L. raniformis these occurred on two pairs of chromosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

NORs were localized by Ag-AS-staining in karyotypes of Rana nigromaculata, R. macrocnemis, R. latastei (2n=26) and R. chensinensis, 2n=24. As in the majority of other Rana species, the NORs are located in the long arms of the 10th (or 11th in R. chensinensis) chromosome pair. The presence of a second secondary constriction in R. latastei, as reported earlier, was not confirmed.

Three cultivated varieties of Narcissus tazetta, ‘Grand Soleil d'Or’, ‘Chinese Sacred Lily’ and ‘Cypri’, are triploid (2n = 3x+30) with the basic number 10. ‘Grand Soleil d'Or’ has three homomorphic sets, each comprising 2 long submetacentrics, 4 long acrocentrics and 4 short acrocentrics. Karyotypes of the other two varieties are heteromorphic. Both possess one telocentric satellited chromosome. In addition, ‘Cypri’ shows translocation between two chromosomes belonging to the seventh and eighth triplets. The number of secondary constrictions varies between 3 (‘Chinese Sacred Lily’) and 4 (‘Grand Soleil d'Or’ and ‘Cypri’) which is also the number of nucleoli observed in the respective varieties.

Nucleolar number variation has been investigated in root tip cells by cytologically determining the number of nucleoli per cell in autoploids and alloploids of Hordeum species, their haploids and interspecific hybrids. The nucleolus organisers in autoploid types of H. vulgare or H. bulbosum did not show any alterations irrespective of the ploidy level. The nucleolar number variation in these species results from a definite pattern of fusion and the maximum number of nucleoli per nucleus corresponds to the number of secondary constrictions. Nucleolus formation in alloploids and interspecific hybrids is impaired on some of the NORs, suggesting differential amphiplasty or nucleolar dominance. A comparison of nucleolar formation in the alloploid species (brachyantherum, arizonicum, procerum and parodii), their haploids, and the interspecific hybrids revealed different degrees of variation from the expected mean and maximum numbers of nucleoli. While the deviations in hybrids between alloploids (H. arizonicum and H. brachyantherum or H. procerum and H. brachyantherum) are marginal, nucleolar dominance is more pronounced in hybrids involving H. vulgare or H. bulbosum as one of the parents and is invariably associated with the disappearance of the secondary constriction(s) from the NOR(s) contributed by one of the parents, and the number of nucleoli is appropriately reduced.

The location of heterochromatin in the chromosomes of Petunia hybrida (2n=14) is presented. C-banded mitotic metaphase chromosomes and carmine-stained pachytene bivalents have been studied. It is shown that the heterochromatin is predominantly located near the centromeres and at the secondary constrictions of the satellite chromosomes. The distribution of chromomeres in pachytene bivalents also reveals that heterochromatin is not restricted to distinct blocks, as is the case in tomato, but occurs in smaller chromomeres which gradually decrease in size towards the ends. Conspicuous telomeres have not been observed. Both C-banding technique and pachytene analysis demonstrate large variation of heterochromatin between different lines of Petunia. The study of pachytene morphology has been hampered by a high degree of non-specific stickiness of the bivalents. Both techniques prove to be unsuitable tools for large-scale chromosome identification of Petunia lines.

G-banding, C-banding and silver staining techniques were used to analyse the chromosomes of the roe deer (2n=70, NF=72). On the basis of several G-banded metaphases a standard description of the karyotype has been proposed. C-bands show constitutive heterochromatin in the centromeric regions of all the autosomes. The submetacentric X and Y are both C-band negative. The largest centromeric C-bands in prometaphase plates are differentiated into two distinct bands. The nucleolus organizer regions (NORs) are terminally located distally on the largest pair of autosomes, in close correspondence with a G negative secondary constriction. Associations were seen in 11% of all investigated metaphases.

Chromosome measurements were carried out in Hordeum vulgare, H. bulbosum, and their diploid, triploid, and tetraploid hybrids. The chromosomes were classified by using relative values, and thus karyotypes were established. For comparison of these karyotypes both relative and absolute values were used. It was concluded that differential amphiplasty occurred, whereas neutral amphiplasty could not be demonstrated. In the hybrids the relative length of the parts of the chromosomes (long arm, short arm, satellite) was not changed in comparison with these lengths in the pure species. The karyotypes of both species had considerable similarities. From comparing the mean absolute genome lengths, it was, however, concluded that in the pure species, as well as in all hybrid types, the chromosomes of H. vulgare were longer than those of H. bulbosum. In the diploid and tetraploid hybrids the mean genome lengths were shorter than those in the pure species and the triploid hybrids. The differential amphiplasty was such that the secondary constriction of chromosome 6 of H. bulbosum, did not show up in the hybrids. This could be related to the suppression of nucleolar formation in the genome of H. bulbosum, because the maximum number of nucleoli in root tip cells equalled the number of satellite chromosomes. Finally it was found that the pattern of nucleolar fusion in diploid and triploid hybrids deviated from the expectation. The results were discussed in relation to chromosomal disturbances that occurred in the hybrid tissues and that resulted in elimination of chromosomes and other effects.

The karyotype of the osprey consists of 74 chromosomes. There are no large macrochromosomes and no typical microchromosomes. Autosome No. 2 has a prominent secondary constriction in the long arm. The Z chromosome is similar in size and shape to the largest autosome, the W is a small metacentric. Among the Falconiformes, the osprey karyotype mainly resembles the karyotypes of some accipitrid species. However, certain characteristic features of the karyotype, a unique secondary constriction chromosome and absence of microchromosomes, speak in favour of maintaining the osprey in a family of its own, Pandionidae.

Differential staining techniques were used to study the structure and variation of the NORs of 27 species of cryptodiran turtles. No species or individuals had more than a single pair of NORs. Extensive variation in NOR structure and chromosomal location was found among higher taxa and individual variation in NOR size was common. Thirty eight percent of all individuals studied were heterozygous for the size of the NOR. However, interspecific variation in chromosomal location and structure of the NOR within major taxa was relatively rare. It is concluded that ( I ) the pattern of variation of NORs is consistent with patterns of chromosomal evolution in turtles; (2) Turtles have only a single pair of NORs whereas other animals, such as some mammals, possess numerous NORs; (3) The heterochromatin associated with the NOR is involved in the structure of the nucleolus.

A Dutch population ofCrenobia alpina was found to have a chromosome number of 2n=42. One pair of large chromosomes is acrocentric and probably shows a secondary constriction; one small pair is acrocentric as well. All other chromosomes are metacentric or sub-metacentric; it has not been possible to discriminate with certainty between them. According to the hypothesis ofDahm (1958) populations with, 2n=42 are autohexaploid, the basic genome consisting of seven chromosomes. On basis of the karyotype it was concluded that the Dutch population described here, is not autohexaploid but functionally diploid, perhaps allohexaploid.