The lowest diploid number in Testudines: Banding patterns,telomeric and 45S rDNA FISH in Peltocephalus dumerilianus, 2n = 26 and FN = 52 (Pleurodira,Podocnemididae)

The karyotype of the big-headed Amazon River turtle, Peltocephalus dumerilianus, is characterized based on a sample of seven juveniles from Reserva Biológica do Rio Trombetas, Pará State, Brazil (1°30′ S, 56°34′ W). Here we present the first results on GTG and CBG-banding patterns, Ag-NOR staining and FISH, with telomeric and 45S rDNA sequences as probes. A cytogenetic comparison with related Podocnemidae is also provided.     

Diet of a Group of Callicebus torquatus lugens (Humboldt, 1812) During the Annual Resource Bottleneck in Amazonian Colombia

A group of Callicebus torquatus lugens using a territory of 22.25 ha in eastern Colombia showed a varied diet throughout the annual period of lowest fruit availability. This is a time when the females are usually pregnant. During a 6-month period the study group's diet consisted of 59.4% fruits, 26.9% immature seeds, 6.4% leaves, 3.9% flowers, and 3.4% insects and spiders. At the fruit bottleneck, consumption of seeds and flowers increased, while consumption of leaves and insects showed no particular trend. They ate 62 species of plants: 45 for flesh, 6 for seeds, 2 for flowers, and 13 for foliage. The most important families in terms of species chosen are Moraceae (8 species, or 11 species if Cecropiaceae is included), Myristicaceae (7), Arecaceae (4), Chrysobalanaceae (4), and Euphorbiaceae. The most important families in terms of feeding time are Myristicaceae (25%), Euphorbiaceae (15%), Moraceae (14%), and Arecaceae (9%). Of 440 marked feeding trees in the territory of the group, 41.1% are represented by Sandwithia heterocalyx (Euphorbiaceae). This species is the most important food in the diet and has the highest density of all food trees in the home range. It followed by Heterostemon conjugates (Caesalpiniaceae) (10%), Iryanthera ulei (Myristicaceae) (6.1%), Anaxagorea brachycarpa (Annonaceae) (5.9%), and Iryanthera crassifolia (Myristicaceae) (3.4%). The remaining 33.5% of the marked trees are represented by the other 57 species. In terms of time spent feeding, the important trees in the diet include Sandwithia heterocalyx (13.9%), Virola melinonii (10%), Iryanthera ulei (8.35%), Oenocarpus bataua (7.06%), and Heterostemon conjugates (6.53%). We suggest that Callicebus torquatus should be described as a frugivore–granivore; they share with the Pitheciin an immature seed-eating adaptation.     

Evidence for insectivory in two primate species (Callicebus torquatus lugens and Lagothrix lagothricha lagothricha) from northwestern Amazonia

Insects were recovered and identified from stomach contents of two Callicebus torquatus lugens and one Lagothrix lagothricha lagothricha collected in a remote area of northwestern Amazonia. Both C. torquatus lugens showed little insect matter in stomach contents. Conversely, a minimum of 133 individual insects were recovered from stomach contents of the L. lagothricha lagothricha. These included various larger, rapid forms (Cicadellidae) unlikely to have been inadvertently consumed while the animal was eating fruit.     

Cytogenetical changes of offsprings from the induced tetraploid hybrid betweenRanunculus silerifolius (2n = 16) andR. chinensis (2n = 16) (Ranunculaceae)

Cytogenetical studies were carried out on the successive generations of offsprings from the induced tetraploid hybrid (2n = 32) betweenRanunculus silerifolius (2n = 16) andR. chinensis (2n = 16). Aneuploids, 2n = 30 to 35, frequently occurred. In latter subsequent generations the deviation of aneuploids increased, but the proportion of euploids decreased, accompanied by the reduction of fertility of pollen grains and seed sets. F₂ and F₄ PMCs constantly exhibited meiotic abnormality, i.e. formation of quadrivalents and univalents. The speciation process ofR. cantoniensis (2n = 32), which was presumed to arise from tetraploid hybrids between the above two species, is discussed on the basis of the above evidences.Former contributions of this series areOkada & Tamura (1977) andOkada (1984).     

Genomic diversity in aneudiploid (2n = 38) and diploid (2n = 40) Glycine tomentella revealed by cytogenetic and biochemical methods.

Of the 15 perennial species of the subgenus Glycine Willd., G. tomentella Hayata is unique in that it has four cytotypes (2n = 38, 40, 78, and 80) and a wide range of geographical distributions. The objective of this study was to uncover the genomic diversity among accessions of aneudiploid (2n = 38) and diploid (2n = 40) G. tomentella based on crossability rate, hybrid seed and seedling viability, meiotic chromosome pairing of F1 hybrids, and seed protein and protease inhibitor profiles. Aneudiploid and diploid G. tomentella accessions were divided into two (D1 and D2) and three [D3(A,B,C), D4, and D5] groups, respectively, based on previous isozyme studies. Crossability rate, intergenomic hybrid viability, degree of chromosome pairing, total seed protein profiles, and trypsin and chymotrypsin inhibitor banding patterns confirmed the isozyme grouping with minor disagreements. A consistent variation was not observed among the aneudiploid accessions in any method of analysis used in this study. Similarly, cytogenetic analysis and the total seed protein profiles did not show dissimilarity among the accessions from Papua New Guinea (PNG; the D3 group) and north of Mitchell River in Northern Queensland [N.Qld(n)]. However, trypsin and chymotrypsin inhibitor analysis revealed that the PNG accessions were distinctly different from N.Qld(n) accessions. The D4 and D5 group accessions were clearly distinguishable by both cytogenetic and biochemical methods. Thus, this study indicates the presence of four genomic groups among G. tomentella (2n = 38, 40) accessions, including the aneudiploids D1 and D2 in one group and diploids in three groups (D3, D4, and D5). These findings will be useful in further genome analysis and add to our present understanding of the biosystematics of the genus Glycine.     

Chromosome painting in<Emphasis Type="Italic"> Callicebus lugens</Emphasis>, the species with the lowest diploid number (2<Emphasis Type="Italic">n</Emphasis>=16) known in primates

Cytogenetic studies have shown that New World primates are karyologically diverse and highly derived. The genus Callicebus is the best example of this karyological diversity, with diploid numbers ranging from 2n=50 to 2n=16. We report on Callicebus lugens, which has the lowest diploid number (2n=16) yet found in the primate order and represents a striking example of extreme karyotypic shuffling. To better understand the genomic rearrangements that have resulted in this extremely low diploid number, we mapped chromosome homologies between C. lugens and humans by in situ hybridization. The total number of hybridization signals was 42, excluding the Y chromosome, with a total of 34 syntenic associations not found in humans. This species has one of the most derived karyotypes among the Platyrrhini. Fusion has been the predominant mode of karyological evolution, although fissions and inversions have also transformed the C. lugens karyotype. Remarkably in such a highly rearranged karyotype, the synteny of 11 human chromosomes (4, 5, 9, 12, 13, 14, 17, 18, 20, 21, and X) was maintained intact, even if most of these human-homologous gene clusters were translocated. Other human syntenies, such as homologues to human chromosomes 10 and 16, were highly fragmented. Comparisons of the C. lugens-human homology map with those of other New World primates have not yet helped establish a phylogenic arrangement between congeneric species or link Callicebus with any other genus.Communicated by S. Henikoff     

Synthesis, morphology and cytogenetics of Raphanofortii (TTRR, 2n = 38): a new amphidiploid of hybrid Brassica tournefortii (TT, 2n = 20) ×Raphanus caudatus (RR, 2n=18)

Amphidiploid Raphanofortii was synthesized by colchicinization of the F₁ hybrid Brassica tournefortii (TT, 2n = 20)×Raphanus caudatus (RR, 2n = 18). The crossability between these two species, and the cytomorphology of the F₁ plants and the amphidiploids were investigated. Intergeneric hybrids between the species were obtained only when B. tournefortii was involved as female parent. The hybrid plants were intermediate for most of the morphological attributes and showed very low pollen fertility compared to the parents. Although a majority of the pollen mother cells of the dihaploid hybrid (TR, 2n = 19) harboured univalents, a maximum of six bivalents were also observed. Of the 37 colchicine-treated F₁ plants analyzed cytologically, 21 were found to be true amphidiploids (2n = 38), whereas seven were mixoploids. Meiosis in the amphidiploids was characterized by the occurrence of 19 bivalents, though multivalents and univalents were also observed in a few cells. Most of the amphidiploid plants exhibited a fairly high pollen and seed fertility, which was further enhanced with the advancement of generations. Out of 69 plants investigated in the A₂ generation, 64 were euploids while the remaining five were aneuploids (2n = 36, 37, 39, 40 and 42). The newly synthesized Raphanofortii has great potential as a new commercial crop, as well as a bridge species for the transfer of economically important attributes of both the species to other Brassicas. Received: 2 November 1999 / Accepted: 26 March 2000     

The synthesis and characterisation of some MnLnX2 complexes (n = 1, L = pyridine, 4-pyrrolidinopyridine,X = Cl,Br, I,NCS; n = 1, L = EtOH,X = Cl,Br; n = 2, L = EtOH,X = I,NCS)

Mono-ligand complexes MnLX₂ (L = pyridine, 4-pyrrolidinopyridine, X = Cl, Br, I, NCS) have been prepared. The pyridine complexes contain only bridging halide and pseudohalide groups, whereas the 4-py complexes contain both bridging and terminal bound anions. Ethanol is coordinated in Mn(EtOH)X₂ (X=C1, Br) and Mn(EtOH)₂X₂ (X=I, NCS). Although the MnLX₂ complexes have the same stoichiometry as the Mn(PR₃)X₂complexes none show any activity towaxds binding dioxygen either in the solid state or in solution.     

Comparative mapping of twenty-eight bovine loci in sheep (Ovis aries, 2n = 54) and river buffalo (Bubalus bubalis, 2n = 50) by FISH

Peripheral blood cell cultures were treated for late incorporation of both BrdU and Hoechst-33258 to obtain R-banding pattern preparations. Twenty-eight bovine cosmids from 19 bovine syntenic groups (U), three of which contain type I loci and 25 which contain microsatellite loci and have previously been assigned to cattle chromosomes, were comparatively FISH-mapped to sheep and river buffalo chromosomes according to the standard karyotypes (13 loci for the first time in the latter species). The results enrich the physical maps of both species with information relative to the following loci and to the corresponding syntenic groups: IDVGA35 and IDVGA53 (U6), IDVGA61 and IDVGA84 (U13), JAB10 (U5), IDVGA41 and IDVGA57 (U27), IDVGA87 (U11), IDVGA32 and IDVGA10 (U19), IDVGA49, IDVGA66 and IDVGA68 (U1), ZNF164 (U23), IDVGA74 and IDVGA70 (U9), IDVGA47, IDVGA46 and IDVGA58 (U21), MAP1B (U14), IDVGA79 (U4), CATHL (U12), IDVGA71 (U8), IDVGA59 (U26), IDVGA29 (U29), IDVGA7 (U7), IDVGA82 (X), IDVGA50 (Y). All mapped loci were localized on homoeologous chromosomes and chromosome regions of the two species, confirming the high degree of chromosome homoeologies between the subfamilies Bovinae and Caprinae.     

Thaptomys Thomas 1915 (Rodentia, Sigmodontinae, Akodontini) with karyotypes 2n = 50, FN = 48, and 2n = 52, FN = 52: Two monophyletic lineages recovered by molecular phylogeny

A novel karyotype with 2n = 50, FN = 48, was described for specimens of Thaptomys collected at Una, State of Bahia, Brazil, which are morphologically indistinguishable from Thaptomys nigrita, 2n = 52, FN = 52, found in other localities. It was hence proposed that the 2n = 50 karyotype could belong to a distinct species, cryptic of Thaptomys nigrita, once chromosomal rearrangements observed, along with the geographic distance, might represent a reproductive barrier between both forms. Phylogenetic analyses using maximum parsimony and maximum likelihood based on partial cytochrome b sequences with 1077 bp were performed, attempting to establish the relationships among the individuals with distinct karyotypes along the geographic distribution of the genus; the sample comprised 18 karyotyped specimens of Thaptomys, encompassing 15 haplotypes, from eight different localities of the Atlantic Rainforest. The intra-generic relationships corroborated the distinct diploid numbers, once both phylogenetic reconstructions recovered two monophyletic lineages, a northeastern clade grouping the 2n = 50 and a southeastern clade with three subclades, grouping the 2n = 52 karyotype. The sequence divergence observed between their individuals ranged from 1.9% to 3.5%.     

Induction of haploid and diploid plants though in vitro anther culture of haploid wheat (n=3x=21)

Summary Five haploid plants of wheat were used for anther culture. Embryos were formed and six plants were regenerated. Of these, two were haploid (n=3x=21) and two diploid (2n=6x=42). The two diploids derived from the anthers of the same haploid wheat plant gave seeds, but the fertility was reduced in one of them showing, abnormalities at meiosis.     

The ancestral carnivore karyotype (2n = 38) lives today in ringtails

Chromosome painting was used to investigate the conservation of high-resolution longitudinal 4',6-diamidino-2-phenylindole (DAPI)/G bands in Carnivore chromosomes. Cat (Felis catus) and raccoon dog (Nyctereutes procyonoides) painting probes were hybridized to the ringtail (Bassaricus astutus), dwarf mongoose (Helogale parvula), and Malagasy civet (Fossa fossa) to identify homologous chromosome elements. The patterns of chromosome segment homology among Carnivore species allowed us to reconstruct and propose the disposition of a high-resolution banded ancestral carnivore karyotype (ACK). Three bi-armed chromosomes consistently found among Caniformia species are represented as 6 homologous acrocentric chromosomes among Feliformia species of Carnivora. However, reexamination of the most basal of Feliformia species, the African palm civet Nandinia, revealed the presence of the 3 heretofore Caniformia bi-armed chromosomes. Because these 3 bi-armed chromosomes are found in both Caniformia and Feliformia lineages, they are presumed ancestral for all Carnivora, suggesting that the ACK chromosome number would be 38, rather than the previously supposed 42. Banded chromosomes of the ACK are used to evaluate the consistency between recently determined molecular phylogenetic relationships and postulated cytogenetic dynamics in the same Carnivore species.     

Evidence for the existence of 2n gametes in Lotus tenuis Wald. et Kit. (2n=2x=12): their relevance in evolution and breeding of Lotus corniculatus L. (2n=4x=24)

Summary Crosses between male sterile L. corniculatus (2n=4x=24) and L. tenuis (2n=2x=12) plants were performed in order to verify the presence of 2n gametes in L. tenuis. All but one of the plants from these crosses had 2n=4x=24 and the L. corniculatus phenotype; this plant had 2n=2x=12 and the L. tenuis phenotype. The plants also showed good quantity of pollen at tripping, good pollen fertility and good percentage of seed setting in the backcross to L. corniculatus. On the whole, both cytological and morphological observations, showing that all but one of the plants from L. corniculatus x L. tenuis were normal tetraploids, suggest the existence of diploandrous gametes in L. tenuis. On the other hand, haploid parthenogenesis probably gave origin to the dihaploid plant 2n=2x=12.     

Karyotype evolution in South American subterranean rodents Ctenomys magellanicus (Rodentia: Octodontidae): chromosome rearrangements and (TTAGGG)n telomeric sequence localization in 2n=34 and 2n=36 chromosomal forms

Ctenomys is the most numerous genus of South American subterranean rodents and one of the most karyotypically diverse clades of mammals known. Ctenomys magellanicus is the southernmost species of the group and the only one living in Isla Grande de Tierra del Fuego (Argentina). This species presents two chromosomal forms, i.e. 2n=34, and 2n=36 (FN=68). Recent studies suggest that genetic divergence between both karyotypic forms resulted from a chromosomal speciation process. In order to identify the chromosomal rearrangement involved in the process of karyotype evolution in this species, we used chromosome banding techniques and fluorescence in situ hybridization with a telomeric probe to metaphase chromosomes of the two chromosomal forms of Ctenomys magellanicus. Chromosome analysis of Giemsa-stained and G-banding preparations showed that Cm34 and Cm36 karyotypes differ in one rearrangement involving chromosomes A9 from Cm34 and B12 and B17 from Cm36. In addition FISH analysis showed that all of the chromosomes from both chromosomal forms exhibit a telomeric-only distribution pattern of the (TTAGGG)n sequence, indicating that none of the chromosomal forms of Ctenomys magellanicus has true telocentric chromosomes. Our results suggest that a chromosome fission event would have occurred during the process of karyotype evolution in this species.     

C-heterochromatin and extra (B) chromosome distribution in six species of the Nabis (Heteroptera, Nabidae) with the modal male karyotype 2n = 16 + XY

The basic male karyotype of the six Nabis species (Heteroptera, Nabidae) is confirmed as being 2n=16+XY. The chromosomes are holokinetic while male meiosis is achiasmatic. The sex chromosomes undergo postreduction and in second metaphase show distance pairing, registered in all nabid species examined so far. Using C-banding technique for the first time in the family Nabidae, the heterochromatin was revealed on chromosomes of six species. The species showed different amount and distribution of C-heterochromatin. Only in Nabis (Dolichonabis) limbatus did the C-bands distribution make possible the identification of every chromosome pair in the karyotype. In other species, C-bands were found in some of the autosomes and the X, localized either interstitially or at telomeres. Only the Y usually showed relative stability ofthe C-banding pattern. In four of six species, extra (B) chromosomes were observed and their behaviour in meiosis described.     

Chromosomal assignment of R-spondin genes in the donkey (equus asinus, 2n=62)

R-spondins constitute a recently discovered small family of growth factors, and the evidence of their role in several developmental pathways is growing fast. In this work we describe the chromosomal location of the fourRSPO genes in the donkey. Using horse BACs, we localizedRSPO1 on EAS 5q23,RSPO2 on EAS 12q13,RSPO3 on EAS 24q26, andRSPO4 on EAS 15p13. Moreover,RSPO2, RSPO3, andRSPO4 are the first genes mapped on donkey chromosomes 12, 24, and 15, respectively.     

Barley chromosome identification using genomic in situ hybridization in the genome of backcrossed progeny of barley-wheat amphiploids [H. geniculatum All. (2n = 28) x T. aestivum L. (2n = 42)] (2n = 70)

Genomic in situ hybridization (GISH) has been used to study characteristics of the formation of alloplasmic lines detected among self-pollinated backcrossed progeny (BC1F5-BC1F8) of barley--wheat amphiploids [Hordeum geniculatum All. (2n = 28) x Triticum aestivum L. (2n = 42)] (2n = 70). The chromosome material of the wild barley H. geniculatum has been shown to contribute to these lines. For example, fifth-generation plants (BC1F5) had genotypes (2n = 42w + 2g), (2n = 42w + 1g + 1tg), and (2n = 41w + 1g), where w is common wheat chromosomes, g is barley (H. geniculatum) chromosomes, and tg is the telocentric chromosome of wild barley. Beginning from the BC1F6 generation, alloplasmic telocentric addition lines (2n = 42 + 2tg) and (2n = 42 + 1tg) appear. This lines has been found cytogenetically unstable. The progeny of each of these cytological types include not only the (2n = 42 + 2tg) and (2n = 42 + 2tg) addition plants, but also plants with the monosomic (2n = 41 + 1tg) and the disomic (2n = 40 + 2tg) substitutions, as well as the (2n = 41 + 2tg) plants, which lack one wheat chromosome and have two telocentric barley chromosomes. It has been demonstrated that the selection for well-filled grains favors the segregation of telocentric addition lines (2n = 42 = 2tg) and (2n = = 42 + 1tg).