The linkage relationship and chromosomal locations of the major histocompatl- bility (B) complex and nucleolar organizers (18S + 28S ribosomal RNA genes) were studied in normal and aneuploid chickens. The Balloantigens were defined by hemagglutin- ation, using monospecif c alloantisera. A chicken having three B haplotypes was detected and used in test matings to normal disomic chickens. Additional cases of birds having three different haplotypes were generated in the progeny of such matings. Analysis of the segregation patterns of B haplotypes suggested that the chickens with an additional haplotype were trisomics. Chickens having three B haplotypes also displayed a maximum of three nucleoli in somatic cells instead of the normal two nucleoln of diploids. This indicated the presence of an additional nucleolus organizing region (NOR). Cytogenetic and cytochemical studies were performed on cells of normal and putative trisomic chickens. All chickens displayed a normal array of chromosomes for pairs 1 through 9. Silver staining differentiated Ag-NORs on the long arms of two and three microchromosomes in disomic and trisomic types, respectively. Viable tetrasomic chickens, produced from nter se matings of trisomics, displayed four nucleoll and four Ag-NORs In somatic cell prepara- tions. These results indicate that the DNA sequences encoding the B histocompatibility antigens and the 18S + 28S ribosomal RNAs are linked on an acrocentric microchromo- some in the domestic chicken.

Linkage of the major histocompatibility (B) complex and the nucleolar organizer in the chicken Assignment to a microchromosome

Patton, 1. C., and R. 1. Baker (Department of Biological Sciences and The Museum, Texas Tech University, Lubbock, Texas 79409) 1978. Chromosomal homology and evolution of phyllostomatoid bats. Syst. Zool. 27:449-462.-Gand C-banding analyses were used to determine chromosome homology from representatives of bat families Mormoopidae, Noctilionidae and Phyllostomatidae, subfamily Phyllostomatinae. The karyotype of Macrotus waterhousii 2n = 46, F N = 60 is proposed as primitive for the Phyllostomatoidea. The major strategy involved in karyotypic evolution of taxa analyzed appears to have been reduction of the number of autosomal linkage groups by Robertsonian fusion from the 22 of Macrotus waterhousii to near 15 for the majority of taxa. Chromosome arms were found to be highly conserved. The X chromosomes of all taxa did not vary and were similar to the pattern thought to be characteristic of the primitive X of mammals. Two systematic groups appear recognizable within the Phyllostomatoidea above the family level (Phyllostomatidae in one group and the Noctilionidae and Mormoopidae in the other), whereas three systematic groups are discernible within the Phyllostomatinae. The three groups within the Phyllostomatinae include Macrotus waterhousii in the Macrotus-group, Tonatia minuta, Mimon crenulatum, Phyllostomus discolor and P. hastatus in the Tonatia-Mimon-Phyllostomus-group, and Micronycteris nicefori, M. brachyotis, and M, minuta in the Micronycteris-group. Tonatia bidens and Micronycteris megalotis were karyotypically so divergent that based solely on chromosomal data they could not be placed with any grouping. Examples are shown where extensive chromosomal evolution has been accompanied by little morphological evolution and where extensive morphological evolution has been accompanied by little chromosomal evolution. Such examples are the basis for questioning the hypothesis that chromosomal changes altering the position of regulator genes are a primary mechanism in the evolution of the large magnitude of morphological differentiation in the class Mammalia. [Phyllostomatoidea; Phyllostomatidae; Phyllostomatinae; Mormoopidae; Noctilionidae; G-bands; chromosome; phylogenetic relationships.] Evolutionary events and strategies inof the G-banding and C-banding patterns volving the karyotypes of vertebrates of bats of the genera Macrotus, Microhave been difficult to determine because nycteris, Tonatia, Mimon, Phyllostomus chromosome homology could only be in(subfamily Phyllostomatinae, family ferred. Data based on longitudinal differPhyllostomatidae), Pteronotus (family ential staining patterns for each chromoMormoopidae), and Noctilio (family Nocsome can be used as a test to reject or tilionidae). This particular combination accept proposed homologies, and thereof taxa offers the opportunity to examine by add to our understanding of mamma1)considerable chromosomal variation as lian evolutionary processes and phylogdiploid number varies from 16 to 46 and enies. G-banding and C-banding patterns fundamental number ranges from 20 to provide some of the same advantages to 68, which allows a determination of the cytogeneticists working with mammalian extent to which such chromosomal varichromosomes that the differentially ation has altered the G-banding patterns, banded chromosomes of Drosophila 2) representatives of phyllostomatids that have ~ r o v i d e d to evolutionists studying are believed most like the ancestral stock fruit flies. based on classical studies (see, Smith, This report is based on an examination 1976), and 3) representatives of all three families that are presently considered to Present address: Department of Zoology, Unihave been involved in early phyllostoversity of Georgia, Athens, Georgia 30602. matoid evolution (Smith, 1972, 1976). If

https://www.jstor.org/stable/pdfplus/2412927.pdf

Chromosomal Homology and Evolution of Phyllostomatoid Bats

G and C-chromosome banding techniques have been used to compare the structure of the karyotype in a variety of colubrid and boid snakes. The comparison of G-band patterns indicates that while some band sequences have been conserved, either as whole chromosomes or entire arms, there is also evidence of considerable rearrangement especially in the smaller chromosomes. In the colubrid Elaphe subocularis there is also evidence that there has been a relocation of the centromere on chromosome 2 without any accompanying inversion in the sequence of G-bands. Finally, G-banding has facilitated the demonstration of a simple pericentric inversion distinguishing the Z and W chromosomes in Acrantophis dumereli. This represents the first report of differentiated sex chromosomes in a boid snake. The combined banding data thus indicates that snake chromosomes are certainly not lacking in variability. The use of C-banding to detect constitutive heterochromatin has confirmed that in some boids and colubrids macrochromosomes have been derived from microchromosomes by the additions of heterochromatin.

/pdf/chromosomal-evolution-in-serpentes-a-comparison-of-g-and-c-4h4j5u2ytc.pdf

Chromosomal Evolution in Serpentes; A Comparison of G and C Chromosome Banding Patterns of Some Colubrid and Boid Genera

G-, C-, Q-banding and standard karyotypic analyses were used to study the chromosomal relationships of emydid turtles. Ten species of emydids were used (5 batagurines and 5 emydines) which samples all of the karyotypic variation known for the Emydidae. Data from a testudinid and a chelydrid are compared to the emydids. The karyotype of Mauremys and Sacalia is considered representative of the primitive karyotype for this group because of its widespread occurrence in the morphologically primitive Batagurinae and its similarity to that of some testudinids. The emydine karyotype is believed to have evolved from the primitive batagurine karyotype by the deletion of a heterochromatic macrochromosome. Siebenrockiella and Rhinoclemys are karyotypically derived batagurines.

Chromosome homology and evolution of emydid turtles.

The G-banded karyotypes of 4 species of birds representing the orders Galliformes, Columbiformes and Musophagiformes were compared. Banding pattern homology between orders was limited to 5 major chromosome arms and the Z chromosome. Even in these major chromosome arms pericentric and paracentric inversions produced alteration of the banding pattern sequences. Addition of constitutive heterochromatin was responsible for changes in banding pattern in the Z chromosome. The chromosome banding patterns of an emydid turtle, Terrepene Carolina, 5 species of boid snakes of the genera Liasis, Acrantophis, and Sanzinia and the African clawed-frog, Xenopus muelleri, were also compared to the bird chromosome banding patterns. No homology was observed between any of these major groups: bird, snake, turtle, amphibian. However, intergrouphomology was apparent. — The data obtained do not support reports of broad interordinal direct homology of the macrochromosomes of birds and refutes the idea of a primitive bird karyotype with 3 pairs of “A group” chromosomes and 3 pairs of “B group” chromosomes. — The major mechanisms responsible for chromosome evolution in birds appear to be centric and tandem fusions, paracentric and pericentric inversions, and addition or deletion of heterochromatin.

Chromosome banding pattern conservatism in birds and nonhomology of chromosome banding patterns between birds, turtles, snakes and amphibians.

Improved techniques for culturing avian tissue in combination with a trypsinurea chromosome banding technique has allowed an analysis of chromosome homology in three bird species. Three macrochromosomes of the domestic chicken (Galliformes) showed homology with those of the ring-necked dove and the domestic pigeon (Columbiformes). The ring-necked dove and domestic pigeon displayed similar banding patterns, except that the pigeon possessed an additional four pairs of microchromosomes, which are fused to form two pairs of macrochromosomes in the dove. Both G- and C-banded metaphase chromosomes of the three species are presented, and chromosome evolution and phyletic relations are discussed.

Chromosome homology in birds: banding patterns of the chromosomes of the domestic chicken, ring-necked dove, and domestic pigeon.

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Chromosome homology in birds: banding patterns of the chromosomes of the domestic chicken, ring-necked dove, and domestic pigeon.