Heterochromatin characterization and distribution in the chromosomes of two populations ofIdotea baltica basteri Audouin, 1826 (Isopoda,Valvifera)

Two mediterranean populations ofIdotea baltica basteri from Messina and Naples showed a set of chromosomes composed by 58 all-biarmed chromosomes. The heterochromatin was located in the pericentromeric region of the chromosomes, and its composition appeared heterogeneous. In fact, not all the homologs showed heterochromatin resistant to digestion with three restriction enzymes (Alu I, Hae III and Sau 3A). Moreover, the two populations showed polymorphism in a band of G+C-rich telomeric heterochromatin, which was present only in the population from Messina. It is hypothesized that chromosomal polymorphism might reflect the geographical isolation of the two populations. It is also suggested that a process of diversification is taking place.     

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 and chromosome banding in the Turkish desert woodlouseDesertellio elongatus (Crustacea,Isopoda, Oniscidea)

The karyotype ofD. elongatus was investigated by means of C-banding, silver staining, and mithramycin-and quinacrine fluorescent staining. The diploid chromosome number is 2n=50. C-banding shows pericentromerically localized constitutive heterochromatin in every chromosome. Two of the chromosome pairs carry two telomeric nucleolus organizer regions each. No heteromorphic sex chromosomes were found.     

A new chromosome number forBombina (Anura,Discoglossidae)

Summary The karyotype of a primitive discoglossid anuran,Bombina maxima, native to southwestern China, has 2n=28 chromosomes with 6 large and 8 small bi-armed homologous pairs. This is a higher chromosome number than described for otherBombina species, all of which have 2n=24.     

Chromosome arrangement throughout mitosis and interphase inAllium sativum (Liliaceae)

Summary Allium sativum (garlic) root-tip chromosomes were subjected to a C-banding procedure. In addition to the nucleolar bands reported previously in this species, bands which are telomeric or close to the telomeres have been detected in some pairs. This has allowed us to analyze the arrangement of chromosomes during interphase.     

Nuclear lamellae in the germ-line cells of gall midges (Cecidomyiidae,Diptera)

Summary Lamellar structures in oogonial and spermatogonial cells of gall midges were found to form a complicated system of intranuclear compartments inside which all heteropycnotic chromosomes present in the germ-line cells of these insects are located. In this way, the heteropycnotic S-chromosomes are separated by the nuclear lamellae from the remaining, decondensed chromosomes (E-chromosomes) of the interphase germ-line nucleus.This investigation was supported in part under Contract DPKBN/52/76-II.1.3.10. with the Polish Academy of Sciences.     

Detection of nucleolus organizer regions (NOR) in the chromosomes of the domestic pig (Sus scrofa domestica L.)

In the domestic pig (Sus scrofa domestica L.) nucleolar organizer regions (NOR) were detected by a combined silver-Giemsa method (Ag-G). The main sites of NORs are the secondary constrictions of chromosomes 8 and 10. Sometimes an additional NOR was observed near the centromere of 1 homologue of chromosome 11. Association of NORs were seen only between chromosomes 10 and at a very low frequency.     

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.     

Detection of nucleolus organizer regions (NOR) in the chromosomes of the domestic pig (Sus scrofa domestica L.)

Summary In the domestic pig (Sus scrofa domestica L.) nucleolar organizer regions (NOR) were detected by a combined silver-Giemsa method (Ag-G). The main sites of NORs are the secondary constrictions of chromosomes 8 and 10. Sometimes an additional NOR was observed near the centromere of 1 homologue of chromosome 11. Associations of NORs were seen only between chromosomes 10 and at a very low frequency.     

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.     

Chromosome mechanism inPolididus armatissimus (Reduviidae-Heteroptera)

Résumé Le nombre diploïde des chromosomes duPolididus armatissimus est de 14. L'X et l'Y sont de taille presque égale. L'ensemble des chromosomes de cette espèce représente un karyotype primitif pour la famille des Reduviidae.     

Intergeneric interactions betweenEimeria separata (Apicomplexa) andNippostrongylus brasiliensis (Nematoda) in the rat

Summary Ova production inNippostrongylus brasiliensis infected rats was significantly greater than in rats singly infected with the helminth whenEimeria separata infections were introduced 4, 6 and 11 days postinoculation withN. brasiliensis. Patent periods were unaltered during concurrent infections. These results suggest that the presence ofE. separata affects helminth fecundity but does not increaseN. brasiliensis longevity as has been shown withE. nieschulzi.This study was supported by NIH MB RS Grant RRO8012-8.     

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.     

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.     

Genetic basis of some morphological differences between temperate and equatorial populations ofDrosophila melanogaster

The genetic basis of three morphological traits (ovariole number, sternopleural bristle number and wing length) ofDrosophila melanogaster has been investigated in natural populations that show great differences in these traits, i. e. Bordeaux (France) and Loua (Congo). F1 and F2 crosses, and chromosome substitutions between these two populations, were analysed. Maternal and/or X chromosome effects were found for sternopleural bristle number and wing length. For all traits, significant effects from each of the three chromosomes were found, but in general only one or two chromosomes had a major effect. Moreover, in all cases significant interactions between chromosomes were observed, suggesting the existence of epistatic effects. Our results are discussed and compared to those obtained from the analysis of selected laboratory strains.     

A new chromosome race ofSorex araneus L. from Northern Poland

Summary G-band patterns were studied in the chromosomes of two Polish populations of the common shrew. Two chromosome races were established in Poland, differing by various combinations of chromosome arms.     

H-Y antigen expression in heterogametic males (XY) and females (ZW): a factor in reproductive strategy?

The cells of heterogametic females with ZW sex chromosomes express H-Y or H-W antigen. A hypothesis is formulated to explain why these animals are capable of 'practicing' amphigonia retardata, i.e., delay in actual fertilization of eggs by retaining viable sperm within the oviduct for a considerable time (several months).     

Chromosomal translocations in 2 Italian populations ofReticulitermes lucifugus (Rossi) (Insecta,Isoptera: Rhinotermitidae)

Summary The chromosomes of 2 Italian populations ofReticulitermes lucifugus (Rossi) were studied in both spermatogonial and oogonial divisions. The diploid chromosome complement is 2=42. All the first meiotic metaphases in Sardinian males show a complex translocation arranged in chains of 4 bivalents. The Apulian males show either 21 bivalents or 19 bivalents and a chain of 2.The authors express their thanks to Prof. A. Springhetti for his kind help in supplying the materials and for criticism in preparation of this paper, and to Prof. G. Colombo for valuable advice and criticism.     

The mitotic chromosomes of the lampreyMordacia mordax (agnatha: Petromyzonidae)

Résumé L'étude des chromosomes somatiques de la lamproie de l'hémisphère sud,Mordacia mordax (Richardson), montre que l'équipement chromosomique diploïde de cette espèce est composé de 76 chromosomes très petits. La plupart des chromosomes sont métacentrique ou bien submétacentrique. Ces chromosomes sont différents en nombre de ceux décrits pour les lamproies de l'hémisphère nord.     

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.