Maria Rozek

Induction of micronuclei in tadpoles of Rana temporaria and Xenopus laevis by the pyrethroid Fastac 10 EC

The mutagenic properties of the pyrethroid Fastac 10 EC were estimated using the micronucleus test in tadpoles of Rana temporaria and Xenopus laevis. The frequency of erythrocytes with micronuclei was examined in blood smears obtained from animals kept for 14 days in water containing 3 different concentrations of Fastac 10 EC. The study was accompanied by a positive control using the known mutagens cyclophosphamide and N-methyl-N-nitrosourea. The results obtained showed that at high concentrations Fastac 10 EC has a clastogenic activity and/or damages the mitotic spindle, as manifested by a significant increase in the frequency of the micronucleated red blood cells. It was also demonstrated that tadpoles of Rana temporaria are more sensitive to the mutagenic effect of the pyrethroid than are those of Xenopus laevis.

New data on the cytology of parthenogenetic weevils (Coleoptera, Curculionidae)

Parthenogenesis and, in particular, polyploidy are rare in animals. A number of cases, known among weevils, represent apomictic parthenogenesis—a reproductive mode in which eggs undergo one maturation division, the chromosomes divide equationally, and no reduction takes place. Among parthenogenetic weevils there are two diploids, 48 triploids, 18 tetraploids, six pentaploids, three hexaploids and one decaploid. Eight examined parthenogenetic species are triploids with 33 chromosomes of different morphology, confirming that triploidy is the most common level of ploidy in weevils. The karyotypes are heterogeneous with the presence of meta-, submeta-, subtelo- and acrocentric chromosomes. The C-banding method showed that only two species possess a large amount of heterochromatin visible as a band around the centromere during mitotic metaphase. This agrees with observations that weevils are characterized by a small amount of heterochromatin, undetectable in metaphase plates after C-banding. In three species an atypical course of apomictic oogenesis occurs with stages similar to meiosis, in which chromosomes form bivalents and multivalent clusters. This association of chromosomes probably represents the remnants of meiosis, although these events have nothing to do with recombination. The results support the hypothesis that the evolution of apomictic parthenogenesis in weevils has proceeded through a stage of automixis.

Karyology of parthenogenetic weevils (Coleoptera, Curculionidae): Do meiotic prophase stages occur?

We investigated the cytological mechanism of parthenogenesis by analyzing the chromosomes in five weevil species. All examined species are polyploids, four of which: Otiorhynchus ovatus, Simo variegates, Cathormiocerus aristatus, and Tropiphorus elevatus possess three haploid sets of chromosomes (3n=33), whereas the fifth, Trachyphloeus parallelus, is tetraploid with 44 chromosomes (4n=44). The plates contained 27-31 chromosomes in triploid species and 38, 39, 41 and even 44 in tetraploid T. parallelus. In all species single clusters of metaphase plates with a haploid number of n=11 were visible. Some oogonial cells showed nuclei configurations resembling the stages of diplotene and diakinesis. The spiralized chromosomes in these nuclei may have been connected by chiasmata resulting in rods figures and ring-shaped bivalents. Occurrence of the remnants of meiosis could suggest some degree of recombination in parthenogenetic lineages of weevils.

C-banding karyotype and NORs analyse in eight species of Barypeithes Duval from Central Europe (Coleoptera, Curculionidae, Entiminae)

Abstract — Karyotypes of eight species belonging to the genus Barypeithes were studied using standard Giemsa staining, AgNOR- and C-banding techniques.The species studied share almost the same chromosome number 2n = 22 (10 + Xyp) with exception of endemic Barypeithes liptoviensis which possesses 26 chromosomes (12 + Xyp). The karyotype of Barypeithes pellucidus is characterized by the presence of one to six B chromosomes clearly distinguishable from the regular members of the complement. In all examined species heterochromatin visualized by Cbanding, is found to be limited almost to the pericentromeric region of all chromosomes with differences in their amount. The wide C-bands visible during mitotic metaphase are observed in five species whereas a small blocks of heterochromatin visible during mitotic prophase are found in three species. Also the one Ag-stained NOR situated in the sex chromosomes is visible during mitotic and meiotic prophases.

Karyotypic characterization of three weevil species (Coleoptera: Curculionidae, Brachyderini).

Karyotypes of three species, Brachyderes incanus, Brachysomus setiger and Paophilus afflatus, belonging to the tribe Brachyderini, were studied using C-banding technique. The species share the same chromosome number 2n = 22 and meioformula n = 10+Xy(p) at all metaphase 1 plates of spermatid division. Some differences between karyotypes were observed in terms of centromere positions and C-band sizes. Most chromosomes are meta- or submetacentric and form a graded series in respect to length. The chromosomes resemble one another in having a rather small amount of heterochromatin restricted to the pericentromeric region and visible as dark stained blocks mainly during early stages of nuclear division. Only in Brachyderes incanus do larger bands occur at mitotic metaphase and diakinesis. These cytogenetic data are in agreement with karyological findings obtained in other species of Brachyderini so far examined.

C-bands and NORs on chromosomes in four species of the genus Trechus Clairv. (Coleoptera, Carabidae)

SUMMARYC-banding pattern and Ag-NORs on chromosomes of Trechus latus, T. pilisensis, T. pulchellus, and T. quadristriatus are presented. T. pulchellus has a paracentromeric C-band similar in size on all chromosomes. T. latus has euchromatic the X chromosome but all autosomes have a paracentromeric C-positive band. In the karyotype of T. quadristriatus the 1st pair of autosomes is euchromatic while the autosomes have a paracentromeric C-band. T. pilisensis has a constitutive heterochromatic segment in a paracentromeric position on all chromosomes and in addition the terminal C-band on the 1st pair of autosomes. Males of the examined species have the same pattern of silver precipitation during spermatogenesis. In the mitotic stages, from the prophase to the prometaphase stage one silver dot on the end of two autosomes is visible. In prophase I (to diakinesis) one active NOR is observed.

Evidence of B-chromosomes in the karyotype of Barypeithes pellucidus Boheman 1834 [Coleoptera, Curculionidae, Entiminae] from Central Europe

B-chromosomes were observed in spermatogonial mitotic metaphases, meiotic metaphases I and II of Barpeithes pellucidus from one population in Slovakia. The number of B-chromosomes ranged from one to six per cell and they paired with the sex heterochromosomes in the first meiotic metaphase and rarely with the autosomes. In metaphase I one B-chromosome was always associated with X chromosome forming a tripartite complex. The XyBp was easily recognizable as a complex of three chromosomes in a parachute association The size of the B-chromosomes was approximately the same or a little smaller than that of the y heterochromosome which was the smallest element of the regular chromosome set. Their staining intensity seems to be similar to that of the autosomes and sex chromosomes, respectively. The behaviour of B-chromosomes during mitosis and meiosis in weevils is briefly discussed.

Karyotypes in Four Species of Amara (Coleoptera, Carabidae)

SUMMARYKaryotypes of four species belonging to the genus Amara were described and compared. It was found that A. aenea and A. fulva share the 17 + X formula, whereas the A. montivaga and A. plebeja showed 18+ X and 16 + Xy, respectively. In all the studied species karyotypes with a predominance of metacentric chromosomes were found, the X chromosome being the largest element in the set. The y chromosome, occurring exclusively in A. plebeja, was the smallest component of the karyotype. Diffuse diplotene was observed during meiosis in males of examined species.

Karyological Studies on Trechinae (Coleoptera, Carabidae). III. Karyotype of Trechos Latus Putz. and Trechus Quadristriatus (Schr.)

SUMMARYIn the present paper the chromosomes of two species of the genus Trechus are described and illustrated. The investigated species have a similar karyotype with a high proportion of metacentric chromosomes which can be expressed as the formula: male 22A + XO; female 22A + XX. In males of both species achiasmatic meiosis was recorded.