Eight species belonging to five true bug families were analyzed using DAPI/CMA3-staining and fluorescence in situ hybridization (FISH) with telomeric (TTAGG)n and 18S rDNA probes. Standard chromosomal complements are reported for the first time for Deraeocoris rutilus (Herrich-Schäffer, 1838) (2n=30+2m+XY) and Deraeocoris ruber(Linnaeus, 1758) (2n=30+2m+XY) from the family Miridae. Using FISH, the location of a 18S rDNA cluster was detected in these species and in five more species: Megaloceroea recticornis (Geoffroy, 1785) (2n=30+XY) from the Miridae; Oxycarenus lavaterae (Fabricius, 1787) (2n=14+2m+XY) from the Lygaeidae s.l.; Pyrrhocoris apterus (Linnaeus, 1758) (2n=22+X) from the Pyrrhocoridae; Eurydema oleracea (Linnaeus, 1758) (2n=12+XY) and Graphosoma lineatum (Linnaeus, 1758) (2n=12+XY) from the Pentatomidae. The species were found to differ with respect to location of a 18S rRNA gene cluster which resides on autosomes in Oxycarenus lavaterae and Pyrrhocoris apterus, whereas it locates on sex chromosomes in other five species. The 18S rDNA location provides the first physical landmark of the genomes of the species studied. The insect consensus telomeric pentanucleotide (TTAGG)n was demonstrated to be absent in all the species studied in this respect, Deraeocoris rutilus, Megaloceroea recticornis, Cimex lectularius Linnaeus, 1758 (Cimicidae), Eurydema oleracea, and Graphosoma lineatum, supporting the hypothesis that this motif was lost in early evolution of the Heteroptera and secondarily replaced with another motif (yet unknown) or the alternative telomerase-independent mechanisms of telomere maintenance. Dot-blot hybridization analysis of the genomic DNA from Cimex lectularius, Nabis sp. and Oxycarenus lavaterae with (TTAGG)n and six other telomeric probes likewise provided a negative result.

Five species belonging to the two families of Dipsocoromorpha were studied: three species from the family Dipsocoridae ~ Cryptostemma pusillimum J . Sb. (2n = 16 + 2m + XY, Yz), C. hickmani Hill (2n = 18 + 2m + XU), and C. ca.ytuneouitreus Linnavuori (2n = 18 + m? + XU) and two species from the family Schizopteridae Pateenu elimata Hill (2n = 30 + 2m + X O ) and Rectilamintl australis Hill (2x1 = 30 + 2m + X0). In all species, autosomes formed chiasmate bivalents in spermatogenesis, and the sex chromosome univalent(s) divided at the first meiotic division and segregated at the second. The evolution of autosomal number, m-chromosomes, and sex chromosome systems within the Dipsocoromorpha and in the whole Heteroptera was discussed. Seppo FinlandThe Dipsocoromorpha is one of the most primitive infraorders within Heteroptera ( STYS and KERZH-NER 1975), and its study is important for understanding the phylogeny of the entire order. Karyological and anatomical (especially, the male reproductive system) characters of the Dipsocoromorpha are poorly studied. So far, only one species, Cryptostemma (as Pachycoleus) rujescens, has been briefly reported as 2n = 20 + X0 by COBBEN (1968). No detailed information on chromosome behavior, nor any information on follicle numbers in this infraorder is available, though the latter has been used for long time as an additional character in taxonomic and phylogenetic studies ( PENDER-GRAST 1957;GROZEVA and KUZNETSOVA 1992).There are several chromosomal characteristics in the Heteroptera like holokinetic chromosomes, diversity of sex chromosome systems (X0, XY, multiple sex chromosomes), alternative sequences of the meiotic reduction for autosomes and sex chromosomes, existence of a pair of m-chromosomes, and occurrence of chiasmatic and achiasmatic meioses. It is very important from the phylogenetical point of view to know to what extent these characteristics exist within the infraorder Dipsocoromorpha.In the present study information on the karyotypes and meiotic behavior of the chromosomes of five species, belonging to two families of Dipsocoromorpha, Dipsocoridae and Schizopteridae, is reported for the first time. Also information on the follicle number of some species is given. Material and methodsThe material for this study has been collected from Finland (Cryptostemma ( s . str.) pusillimum J. Sb.), Tasmania (C. (s. str.) hickmani Hill, Pateena elimata Hill, Rectilumina australis Hill), and Bulgaria (C. (Harpago) castaneouitreus Linnavuori).Specimens were fixed in an ethano1:glacial acetic acid mixture (3:l). The gonads of Bulgarian and Tasmanian material were stained in acetoorcein and squashed in a drop of 45 YO acetic acid.The gonads of the Finnish species were dissected out in 1% sodiumcitrate solution, fixed briefly, about 30 s, in a methano1:glacial acetic acid mixture (3:1), and squashed in a drop of 45% acetic acid. After removing cover slips, slides were dehydrated by immersing in glacial acetic acid for 25 s (or alternatively in fresh 3:l -fixative for 15 min) and air...

Abstract. Bugs (Insecta: Heteroptera) are frequently used as examples of unusual cytogenetic characters, and the family Cimicidae is one of most interest in this respect. We have performed a cytogenetic study of the common bed bug Cimex lectularius Linnaeus, 1758 using both classical (Schiff-Giemsa and AgNO 3 -staining) and molecular cytogenetic techniques (base-specifi c DAPI/CMA 3 fl uorochromes and FISH with an 18S rDNA probe). Males originated from a wild population of C. lectularius were found to have 2n = 26 + X 1 X 2 Y, holokinetic chromosomes, 18S rRNA genes located on the X 1 and Y chromosomes; achiasmate male meiosis of a collochore type; MI and MII plates nonradial and radial respectively.

Male Nabis (Aspilaspis ) indicus (Stål), N. (A .) viridulus Spinola, Himacerus (Himacerus ) mirmicoides (O. Costa) (2n 0/32'/ XY) and Prostemma guttula (Fabricius) (2n0/26'/XY) were studied using C-banding, silver nitrate staining and basespecific fluorochrome (DAPI and CMA 3 ) staining. N. indicus differed from N. viridulus in distribution pattern of C-bands, which were telomeric in the former while interstitial in the latter. H. mirmicoides showed interstitial C-bands in the majority of autosomes. P. guttula had no conspicuous C-bands in other chromosomes, but only in the Y, which was totally heterochromatic. C-heterochromatin was labelled with DAPI, indicating that it was AT-rich. In every species, both X and Y chromosomes were NOR-bearing, and the NOR regions were GC-rich. In H. mirmicoides and P. guttula, NORs showed sub-median location in the X and distal in the Y, such a pattern being probably common in Nabidae. The present paper provides new information on the genome organization and new cytological markers useful for a better insight into karyotype evolution of nabid species.

Telomeres are terminal regions of chromosomes, which protect them from fusion with other chromosomes and stabilize their structure. Telomeres usually contain specific DNA repeats (motifs), which are maintained by telomerase, a kind of reverse transcriptase. In this review, we survey the current state of knowledge of telomere motifs in insects. Among Hexapoda, data on telomere composition are available for more than 350 species from 108 families and 25 orders. The telomere motif (TTAGG) n is considered ancestral for the class Insecta. However, certain insects have different and often unknown telomeric sequences. This apparently happens because telomerase-dependent mechanisms usually coexist with various means of alternative lengthening of telomeres as backup mechanisms of telomere maintenance. This coexistence can explain losses and reappearances of the TTAGG repeat and telomerase-dependent telomere replication in insect evolution. For example, a few higher taxa, such as Heteroptera (Hemiptera) and Hymenoptera, show presence of the (TTAGG) n motif in their basal clades as well as a subsequent loss and, at least in the Hymenoptera, independent reappearance of this repeat in some advanced groups. Analogously, most members of Coleoptera also retain the TTAGG repeat, although it is changed to TCAGG in certain families. Furthermore, the (TTAGG) n motif seems to have been irreversibly lost in the order Diptera. In this group, telomeric sequences are represented either by long terminal repeats or by retrotransposons. Retrotransposons are also interspersed with other telomeric sequences in many groups of insects. The accumulating data demonstrate that the class Insecta is substantially diverse in terms of its telomere structure. K E Y W O R D Schromosomes, FISH, insects, TTAGG, retrotransposons 128 |