Karyological pattern of two Chilean lizards species of the genusLiolaemus (sauria; iguanidae)

Summary The karyotypes of Chilean lizardsLiolaemus pictusandLiolaemus cyanogaster is described for the first time. Both species possess 34 chromosomes; 6 pairs of macrochromosomes and 11 pairs of microchromosomes. Karyologically it is possible to differenciate this species because the pair No. 2 is metacentric (m) inL. pictusand submetacentric (sm) inL. cyanogaster. It is shortly discussed the signification of formule 2n=34 for the species ofLiolaemus analized karyologically and its possible mechanism of acquisition.     

Cytogenetic observations inCeratitis capitata

Summary The 2n=10+XX/XY complement ofC. capitata includes3 pairs of metacentric and 2 pairs of submetacentric autosomes; theX andY chromosomes are acrocentrics. The sex chromosomes do not pair somatically during mitotic prophase, and, using the C-banding technique, band more extensively than the autosomes. Male meiosis may be achiasmate; there is no leptotene, zygotene or diplotene.Material kindly supplied by Dr.D. A. Lindquist, I.A.E.A./FAO Vienna, Austria.     

The chromosomes ofPasseromyia heterochaeta Villeneuve (Muscidae: Diptera)

Summary The 2 n=10 complement ofPasseromyia heterochaeta Villeneuve consists of 4 pairs of metacentric chromosomes and 1 pair of dots. The evolutionary implications of 2 n=10 in the tribe Phaoniini (Fam. Muscidae) are discussed.Acknowledgments. Thank are due to Dr Adrian C. Pont of British Museum (Natural Histoty), London for identifying our speciens through the courtesy of Dr Rokuro Kano, Dean Faculty of Medicine, Tokyo Medical and Dental University Tokyo, Japan. We also thank Dr U.S. Srivastava, Professor and Head, Dept. of Zoology, Univ. of Allahabad for providing the necessary laboratory faclities.     

Un cas nouveau de polymorphisme chromosomique intraspécifique chez un Mammifère (Leggada minutoides Smith. Rodentia-Muridae)

Summary The African mouse,Leggada minutoides Smith, shows a chromosomal polymorphism: a first male (Coast of Ivory) had 32 chromosomes; theX is a big metacentric, theY a big submetacentric and the autosomes are acrocentric, with the single exception of the biggest pair which associates two submetacentric elements. By a second male (Congo), 33 chromosomes are found, amongst them only one big submetacentric autosome. This statement and the odd diploid number shows clearly that we have to deal with an heterozygot, two acrocentric elements representing respectively one arm of the submetacentric autosome. Now, we may be sure that this male belongs to a population built of individuals having 32, 33 and 34 chromosomes. The origin of such a population must have arisen in a primitive population where 34 was the diploid number, through a centric fusion.Such cases pose the question of the balanced chromosomial polymorphism and of the adaptative value of each formula⁶.     

Caryotypes de quelques hybrides interspécifiques dePitymys (Mammalia,Rodentia)

Summary The Robertsonian polymorphism ofPitymys subterraneus involves only 1 pair of metacentric autosomes. The crosses of forms with 52, 53 and 54 chromosomes do not show any differences in their reproductive rate. So a single autosome trivalent does not affect the fecondity. Many hybrids have been obtained betweenP. subterraneus (2N=52 or 54) andP. multiplex (2N=48) with 50 or 51 chromosomes, respectively. Even with a heterogenous karyotype they are not entirely sterile. 2 progeny were produced from back-crosses. The 2 parental species seem to result from recent speciation. Only fecondation or embryogenesis occurs in crossingP. duodecimcostatus withP. subterraneus orP. multiplex. The chromosome complement of 1 hybrid embryo ofP. duodecimcostatus (2N=62)×P. multiplex (2N=48) has been studied showing 55 chromosomes.P. duodecimcostatus appears to belong to a more distant evolutionary group.     

Karyotype of the Japanese salamander,Hynobius abei

Summary A primitive representative of the Caudata endemic to Japan,Hynobius abei Sato (Caudata: Hynobiidae) has 2n=56 chromosomes, with 9 large, 4 medium and 15 small-sized homologous pairs. The morphology of the large-sized chromosomes is similar to that of the knownHynobius species, but the presence of a pair of acrocentrics in the medium-sized group and 5 pairs of biarmed chromosomes in the small-sized group characterized the karyotype ofH. abei.We thank A. Itoi, S. Segawa, K. Ban, T. Hikida and O. Murakami for their assistance in collecting specimens.     

Cytotaxonomy of the Seychelles tree frog,Megalixalus seychellensis (Duméril and Bibron) (Amphibia: Hyperoliidae)

Summary The Seychelles tree frog,Megalixalus seychellensis has 2n=24 chromosomes of gradually decreasing length. Pairs 2, 3, and 4 are submetacentric, and the remaining pairs are metacentric. The karyotype affirms hyperoliid assignment of this species, and indicates a link between the Seychellean fauna and the African-Madagascan faunas.Research supported by the National Geographic Society.     

Les chromosomes deLeggadina hermannsburgensis hermannsburgensis Waite et le problème des Muridae australiens

Summary As contribution to the problem of the Australian endemic Muridae, the chromosome complement ofLeggadina h. hermannsburgensis is described: 2N=48 –N.F.=56 –X-chromosome big and metacentric.     

Somatic chromosomes of Indian burrowing toad,Uperodon globulosum (Gunther) (Anura; Amphibia)

Summary Somatic chromosome complements of the Indian burrowing toad,Uperodon globulosum, have been described for the first time. The 2n number is 26 (NF=52) in both the sexes. No heteromorphism in relation to sex chromosome pair has been recorded. Deviations from 2n number (2n=10–28) have been noticed in the cells of different specimens. The result has been compared withU. systoma.Acknowledgment. Sincere thanks are due to Prof. P. K. Ghosh, Hooghly Mohsin College and to Dr A. K. Roy of the same college for encouragement. Thanks are due to Mr Bipul Kumar Das for his help during collection of specimen.     

Cytogenetics of South American akodont rodents (Cricetidae). V. Segregation of chromosome No. 1 polymorphism inAkodon molinae

Summary Akodon molinae is polymorphic with 2n=42, 43, 44, where the metacentric autosome No. 1 is homologous to 2 acrocentrics 1a and 1b. Matings between 2n=43 heterozygotes 1/1a, 1b gave a surplus of 1/1 offspring, a moderate reduction of heterozygous and a strong reduction of homozygous 1a, 1b/1a, 1b offspring. The latter type also has a highly reduced fertility.This work was supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas, the Comisión de Investigaciones Científicas de la Provincia de Buenos Aires and the Organización de Estados Americanos.     

The largest known chromosome number for a mammal,in a South American desert rodent

Summary Tympanoctomys barrerae, a desert specialist member of the family Octodontidae, until now thought to be conservative, and ancestral to South American hystricognath rodents, presents the highest diploid chromosome number (2n=102) known in a mammal. Unexpectedly, its karyotype was found to be composed mainly of metacentric to sub-metacentric chromosomes. Mechanisms by which such a karyotype may have been derived are discussed.     

Normaler und aberranter Karyotyp vonCepaea hortensis (Müller) (Gastropoda)

Summary The karyotype of 9Cepaea hortensis were analyzed. The haploid chromosome number was 22. 2 types of longest chromosomes were encountered. In 8 out of 9 animals, the longest chromosome had an arm ratio of 1.2. One animal showed a ratio of 4.9. This aberration is thought to have arisen by a pericentric inversion. Because both the normal and the aberrant chromosome coexisted in the same population, a chromosomal polymorphism seems to be present.     

Un nouveau type de détermination chromosomique du sexe chez les mammifèresEllobius lutescens Th. etMicrotus (Chilotus) oregoni Bachm. (Muridés-Microtinés)

Summary (1)Ellobius lutescens andMicrotus oregoni show the same type of sex-chromosomes. The diploid number is odd in both sexes, seventeen.(2) The odd element ofEllobius is morphologically alike in the male and in the female. InM. oregoni, the odd element of the male is acrocentric, that of the female metacentric.(3) Following a hypothesis ofWhite, it seems very probable that the heterochromosome of the male is built of the primitiveY (short arm) and the primitiveX (long arm) linked together. In the female of the same species (M. oregoni), the sex-chromosome represents both theX fused together.(4) Only the half of the Zygotes may develope, the other half being lethal.(5) The close kinship betweenEllobius andM. oregoni is certain, a parallel evolution appearing as highly improbable.     

Robertsonian translocations in Mus musculus from Sicily

Summary The karyotypes of 6 mice from different places in Sicily have been determined. 3 of them had abnormal chromosome numbers of 2n=26, 2n=27 and 2n=29, caused by Robertsonian translocations of one acrocentric chromosome to another resulting in metacentric chromosomes, The newly described metacentric chromosomes are Rb(4.3)1Sic, Rb(15.2)2Sic, Rb(12.6)3Sic, Rb(13.5)4Sic, Rb(14.10)5Sic, Rb(17.8)6Sic and Rb(16.9)7Sic.We thank Dr J. Olert, Pathologisches Institut der Universität Ulm, for karyotyping 1 mouse from Sicily.     

The fine structure of the conical-headed sperm of the crinoidAntedon bifida

Summary Scanning- and transmission electron microscopy show that the sperm head ofAntedon bifida is conical and thus different from the spherical sperm head that is typical of crinoids. The head consists of the acrosome and the nucleus. The posterior fibrogranular component of the acrosome is housed in a tubular, axial invagination running from the anterior pole almost to the posterior pole of the nucleus. The middle piece includes a mitochondrion and a pair of centrioles. One of the centrioles is a basal body, which gives rise to the tail flagellum.     

Robertsonian fusion leading to the formation of stable dicentric chromosome in an ascites cell line of the mouse

Summary The dicentric nature of a marker metacentric chromosome originated by robertsonian fusion has been established in the ascites cells of mouse sarcoma 180. C-banding analysis has revealed that the metacentric is actually a dicentric with 2 closely situated C-positive heterochromatic zones. The nature of the centromeres and the NF value of the cell indicate that this meta-dicentric marker has orginated by breakage and fusion within each of the short arms of 2 acrocentric chromosomes.Acknowledgment. Grateful acknowledgment is made to Dr N. Chatterji, former Director, CNCRC, Calcutta, for supplying the cell-line to the first author. Sincere thanks are due to Prof. Sujit K. Dasgupta, Head, Dept. of Zoology, H. M. Govt. College and to Dr A. K. Roy of the same department for encouragement.     

Cytologie comparée des Muridae. L'origine des Ellobii

Summary (1) The present paper deals with the chromosomial cytology of 11 species and underspecies ofMuridae. (2) The diploïd number being the same (2N=42), there are striking differences between two species ofBandicota, B. indica showing about 20 big metacentric chromosomes which are lackingB. bengalensis. (3)Meriones blackleri is characterized by 72 chromosomes, the species previously described possessing either 44 or 60 elements. (4) The study ofPhenacomys ungava confirms the view that 56 (54) is the primitive number in theMicroti. There is an interesting parallelism between the morphological and the cytological data. (5) A missing link betweenMicroti andEllobii has been found inMicrotus oregoni which possesses 17 chromosomes, its digamety belonging to the typeX-O, X-X. (6) Owing to the fact thatM. oregoni is more fossorial than the otherMicrotus, it is a morphological intermediate betweenMicroti andEllobii. (7) The genusChilotus (Baird) is also fully valid.     

Heterochromosomen beiVipera berus L. (Viperidae,Serpentes)

Summary A dimorphic pair of chromosomes was found among the macrochromosomes in mitosis of females ofVipera berus L. It corresponds to a pair of medium-sized chromosomes in the male. The conclusion is drawn that females are heterogametic (ZW-type), males being homogametic (ZZ-type). Similar observations were made inVipera aspis L.,Natrix natrix L., andNatrix maura L.     

Centromeric heterochromatin in the karyotype of the male Greater Kudu (Tragelaphus strepsiceros)

Summary The chromosomes of a male Kudu (Tragelaphus strepsiceros) have been studied by C-banding and H³ thymidine labelling. It is suggested that heterochromatin may have accumulated on the 14th pair of autosomes before its translocation to the Y-chromosome.     

Chromosome banding patterns and the nucleolar organizer region of the eastern mole (Scalopus aquaticus)

Summary The C and G chromosome banding patterns and the AgAS positive sites (NOR regions) of cultured lung cells of the Eastern mole (Scalopus aquaticus) are presented. A distinctive secondary constriction is found on a pair of autosomes instead of on the X-chromosome as previously believed. The presence of a heterochromatic heteromorphism is noted and a large amount of constitutive heterochromatin is present in the karyotype.