Trends of karyological evolution in Pelobatoid frogs

Summary The Pelobatids have a basal karyotype of 26 chromosomes, with 6 pairs of large and 7 of small chromosomes (6+7). From this karyotype, shown byLeptobrachium, Pelobates andScaphiopus, those ofMegophrys andSpea (5+8) may be derived, as well as that ofL. pelodytoides, with only 24 chromosomes.Pelodytes has 24 chromosomes and a karyotype 7+5 differing from that of typical Pelobatids under several respects.Research supported by a contribution from the Italian C. N. R.     

C-band differentiation between the chromosomes of two subspecies of the chironomid midgeChironomus thummi

Summary The metaphase chromosomes ofChironomus th. thummi contain approximately 17% more pericentric C-band heterochromatin than the chromosomes ofChironomus th. piger with 11% heterochromatin. InCh. th. thummi, the proportion of heterochromatin appeared to be much larger in metaphase chromosomes than in polytene chromosomes. This discrepancy is interpreted as being due to the specific chromosome organization and not as the result of an underreplication of heterochromatin during polytenization.     

The origin of the brown frogs with 2n=24 chromosomes

Late replication and C-banding analyses of somatic metaphase chromosomes were attempted on three species of brown frogs with 2n=26 chromosomes (Rana japonica, R. tsushimensis andR. temporaria), and three with 2n=24 chromosomes (R. ornativentris, R. dybowskii andR. chensinensis), which are distributed in the Palearctic region. The late replication banding patterns were highly conserved in these species. Four chromosome inversions were demonstrated inR. ornativentris, two inR. dybowskii and two inR. tsushimensis. From a detailed comparison of late replication and C-banding patterns between the 2n=26 and the 2n=24 species, it was found that an end-to-end fusion of two small chromosomes (nos 11 and 13) in an ancestral 2n=26 species may have produced the medium-sized no. 6 chromosome of the 2n=24 species.     

I cromosomi di alcuniPipidae (Amphibia Salientia)

Summary The karyotype of the African PipidHymenochirus boettgeri (2n=24, all meta- or submetacentric chromosomes) is different from the one of the African PipidXenopus laevis (2n=36). The karyotype of the American PipidPipa (Protopipa)parva (2n=30, all acrocentric chromosomes) is very primitive and different from the karyotypes of the African Pipids and from that ofPipa pipa; the male meiotic chromosomes ofP. parva, usually with 1 procentric chiasma, show a clear difference from the male bivalents of the other Pipids, all with 2 terminal chiasmata.     

Chromosome complement of tenrecs,Centetes ecaudatus (Order Insectivora,Class Mammalia)

Résumé Dans les leucoyctes en culture de 7 TenrecsCentetes ecaudatus (4 mâles et 3 femelles) provenant de la République Malgache, l'auteur a compté 38 chromosomes et constaté que les sexes ont un caryocyte distinct. C'est la première étude faite sur les chromosomes d'un représentant de la famille des Tenrecidae (Insectivores).

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Skin fibroplast cells were cultured fromCentetes ecaudatus (Animal No. 2). These cells gave a count of 38 chromosomes. Using the same techniques as above, whole blood cultures of the related tenrec,Hemicentetes semispinosus G. Cuvier, were counted. Preliminary studies indicate 38 chromosomes for this speices.     

The karyotype,C-bands and AgNO3-bands of a lungless salamander from Korea:Onychodactylus fischeri (Boulenger) (Amphibia,Urodela)

The karyotype of a lungless salamander,Onychodactylus fischeri, from Korea was analyzed and compared with that of the Japanese congeneric species,O. japonicus. In both species the diploid karyotype consists of78 chromosomes, including 6 pairs of large chromosomes, 6 pairs of medium-sized ones, and the remaining 27 pairs of microchromosomes. The chromosome number ofO. fischeri, 2n=78, is, like that ofO. japonicus, the largest so far reported in the order Urodela. C-banding showed that constitutive heterochromatin inO. fischeri was mainly in the centromeric regions and near the secondary constrictions of the large chromosomes. AgNO₃-bands were located in the secondary constrictions associated with C-band heterochromatin.     

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.     

Fluorescence replication banding of frog chromosomes

To identify individual chromosomes of a frog karyotype by their fluorescence banding patterns, chromosomes were stained with actinomycin D and 4,6-diamidino-2-phenylindole (DAPI) after incorporation of BrdU during the late S-phase. The chromosomes of three Rana species which were selected for this study (R. ridibunda, R. lessonae and R. japonica) showed well-defined late replication bands. The fluorescence patterns obtained were the reverse of those produced by a 4Na-EDTA Giemsa-staining technique. Fluorescence patterns of the two water frog species (R. ridibunda and R. lessonae) were similar to each other, except for the different fluorescence of the centromeric heterochromatin, which gave extremely bright signals in R. ridibunda but no signal in R. lessonae. Experiments also showed differences between the fluorescence patterns of R. lessonae chromosome 13 in the Italian and Luxembourgian populations. These results sho w that the fluorescence replication banding using actinomycin D and DAPI is very effective in identifying individual frog chromosomes and detecting their structural changes. Received 7 June 1996; received after revision 23 July 1996; accepted 21 August 1996     

Démonstration du caractère géographique de la parthénogénèse deSaga pedo Pallas et de sa polyploïdie,par comparaison avec les espèces bisexuéesS. ephippigera Fisch. etS. gracilipes Uvar

Summary The males of two species of Palestine,Saga ephippigera Fisch. andS. gracilipes Uvar have respectively 33 and 31 chromosomes in the diploid state.S. pedo Pallas, a parthenogenetic thelytoc species largely distributed in Europe, has 68 chromosomes and probably represents a tetraploid. The cells of the three species have identical dimensions and the polyploidS. pedo is even the smallest in size.     

Die Genomsonderung in den Mitosen der Rattenleber

Summary Model squashes with gelatine cubes containing 8 files like the chromosomes ofBellevalia romana (2n=8) showed the chromosomes only in groupings that correspond to the original position of metaphase chromosomes. The metaphase chromosomes in root tip cells ofBellevalia romana are arranged at random; there is neither somatic pairing nor genome segregation (= grouping of metaphase chromosomes into two complete chromosome sets). In contradiction to these results, the chromosomes in the regenerating liver cells (2n=42) show a certain precentage of grouping into complete genomes. It is concluded that in rat liver cells a mechanism exists which, starting with the genome segregation, may produce a change in chromosome number. Thus these same euploid or aneuploid chromosome numbers can be explained which are really observed in normal and treated rat liver. 4 possibilities of such mechanism are discussed.

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Nach einem Vortrag, gehalten anlässlich des IV. Symposium histologicum internationale Lausanne (Suisse), 5.–8. September 1961.     

Chromatin ofh regions of human chromosomes at high resolution

Summary Segmentation of the secondary constriction region (h) of human chromosomes 1, 9 and 16 is demonstrated by a high resolution banding technique. Based on these staining properties, it is suggested that the composition of theh region in human chromosomes is heterochromatic as well as euchromatic.     

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.     

The chromosomes of the didelphiid marsupialMarmosa robinsoni bangs

Résumé L'étude des chromosomes somatiques du marsupial sudaméricainMarmosa robinsoni Bangs, démontre que l'équipement chromosomique diploïde de cette espèce de la subfamille Didelphiinae est composé de 14 chromosomes. Trois paires d'autosomes sont grands et submétacentriques; 1 paire est formée par de chromosomes moyens, métacentriques, et 2 paires sont acrocentriques et plus petites. Le complexe sexuel est du typeXY, formé par unX métacentrique et unY télocentrique, tous les 2 étant les chromosomes les plus petits du complément. La similitude de ce caryotype avec celui du genreCaluromys, appartenant à la subfamille Microbiotherinae, est remarquable.     

The mitotic chromosomes of the lamprey,Petromyzon marinus L.

Résumé L'étude des chromosomes somatiques de la lamproie,Petromyzon marinus L. a montré que l'équipment chromosomique diploïde de cette espèce est composé de 168 chromosomes très petits, dont queleues-uns des plus grands sont métacentriques. Le chiffre semble représenter le plus grand nombre de chromosomes trouvé dans une espèce de Vertébré. On a comparé les chromosomes de P.marinus avec ceux des autres espèces de lamproies.

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Holder of a Science Research Council Fellowship.     

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.     

Larvale und imaginale Mitteldarmchromosomen vonDrosophila repleta

Summary In certain tissues ofD. repleta-flies, it is possible to observe the interphase chromosomes that are either of larval origin or that occur in imaginal tissues. The imaginal interphase chromosomes from the midgut are similar to the small larval midgut chromosomes in the early phases of their development.     

Supernumerary chromosomes inDrosophila nasuta albomicana

Summary Supernumerary chromosomes have been detected in the karyotype ofD.n. albomicana. Their number varies from one to three. They are the smallest elements in the karyotype. Karyotypes ofD.n. albomicana with and without supernumerary chromosomes have been presented.     

Centromere separation: existence of sequences

Summary The centromeres of chromosomes from human lymphocytes as well as root tips ofVicia faba andCrepis capillaris release the sister-chromatids in nonrandom, genetically controlled sequences. In man chromosomes 18 and 17 are amongst the earliest and 13, 14, 15 the last. The sequences may be a universal phenomenon among eukaryotes.I wish to thank Drs Rieger and J. Van't Hoff for supply of seed.     

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.     

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.