Meiotic studies in Lygaeus ulboornatus Blanchard 1852 ( Heteroptera , L ~ gaeidae , L ~ gaeinae ) 5 2 (original) (raw)
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Heredity, 1993
Cytogenetic analysis of an Argentine population of Largus rufipennis has revealed the presence of autosomal univalents and a supernumerary chromosome. All individuals present univalents at a variable frequency (0.31-21.83 per cent), and half of them carry a B chromosome at low frequency. Both the B chromosome and univalents divide equationally at anaphase I and reductionally at the second division. The present population is very heterogeneous with respect to chiasma frequency and distribution: desynapsis is responsible for the appearance of univalents, while the presence of the B chromosome is associated with an increase in chiasma frequency. However, two individuals that lack the supernumerary chromosome show a strikingly high chiasma frequency. This variation in chiasma frequency should be the result of the interaction between genes controlling chiasmata and the environmental conditions (both internal and external) together with the genetic background of each individual.
Chromosome research : an international journal on the molecular, supramolecular and evolutionary aspects of chromosome biology, 1999
The genus Dysdercus Guérin Méneville 1831 represents the only taxon within the family Pyrrhocoridae in the New World. Based on morphological features, it has been suggested that American species derived from immigrants from the Old World, most probably from the Ethiopian Region. So far, 10 species from Dysdercus, including six species from the Old World and four species from the Neotropical Region have been cytogenetically analyzed. As is characteristic of Heteroptera, they possess holokinetic chromosomes and a prereductional type of meiosis. While the X1X20 sex chromosome system has been reported in all cytologically analyzed species of Dysdercus from the Old World, the system X0 has been found in all but one species from the New World, regardless of the number of autosomes in the complement. In the present study the male meiosis of D. albofasciatus Berg 1878 was studied in specimens from four different populations from Argentina. The diploid chromosome number was found to be 2n = ...
Autosomal polyploidy and male meiotic pattern in the bug family Nabidae (Heteroptera)
Journal of Zoological Systematics and Evolutionary Research, 2000
Karyotypes of 18 species of Nabidae (Heteroptera), belonging to the genera Nabis (ll), Hitnacerus (3), Hopli.r/oscelis (I), and Pagasu (1) were studied. The data on Nabis tneridionulis Kerzhner 1963, N. lesquorutn (Kerzhner 1968), N. ussuriensis (Kerzhner 1962), N. paNidus Fieber 1861, N. sareptanus Dohrn 1862, Hop1istosceli.s .sordidus (Reuter 1872). and Pagasafu.scu (Stein 1857) were obtained for the first time in this study. Karyotypes of Nahis punctatus A. Costa 1847, N.Jerus (Linnaeus 1758), N. pseudoferus Remane 1949, N. rugosus (Linnaeus 1758), N. stenoferus Hsiao 1964. N. limbatus Dahlbom 1851, N. reuteri Jakovlev 1876, N. flrn~omurginatus Scholtz 1847. Himacrrus apterus (Fabricius 1798), H. mirmicoides ( 0 . . and H . tnarucandicus (Reuter 1890) were re-examined. A karyotype of 2n = 18 (16 + XY), which seems to be the most characteristic of Nabidae as a whole, was found in 12 species. Nabis pallidus and N. sareptanus showed a precise numerical doubling of the autosomal complement compared with the modal karyotype, 2n = 34 (32 + XY). Autosomal polyploidy is discussed as a possible evolutionary mechanism for these species. Meiosis in males of the above species was studied in detail. Male meiosis in Nabidae was shown to follow a highly peculiar scenario differing in many aspects from that known in the majority of the Heteroptera taxa.
Genes
The Lygaeoidea comprise about 4660 species in 790 genera and 16 families. Using standard chromosome staining and FISH with 18S rDNA and telomeric (TTAGG)n probes, we studied male karyotypes and meiosis in 10 species of Lygaeoidea belonging to eight genera of the families Blissidae, Cymidae, Heterogastridae, Lygaeidae, and Rhyparochromidae. Chromosome numbers were shown to range from 12 to 28, with 2n = 14 being predominant. All species have an XY system and all but one have a pair of m-chromosomes. The exception is Spilostethus saxatilis (Lygaeidae: Lygaeinae); in another species of Lygaeinae, Thunbergia floridulus, m-chromosomes were present, which represents the first finding for this subfamily. All species have an inverted sequence of sex chromosome divisions (“post-reduction”). The 18S rDNA loci were observed on one or both sex chromosomes in Kleidocerys resedae and Th. floridulus, respectively (Lygaeidae), while on an autosomal bivalent in all other species. The rDNA loci tende...
Cytogenetic studies of three Lycosidae species from Argentina (Arachnida, Araneae)
Genetics and Molecular Biology, 2008
Cytogenetic studies of the family Lycosidae (Arachnida: Araneae) are scarce. Less than 4% of the described species have been analyzed and the male haploid chromosome numbers ranged from 8+X 1 X 2 to 13+X 1 X 2. Species formerly classified as Lycosa were the most studied ones. Our aim in this work was to perform a comparative analysis of the meiosis in "Lycosa" erythrognatha Lucas, "Lycosa" pampeana Holmberg and Schizocosa malitiosa (Tullgren). We also compared male and female karyotypes and characterized the heterochromatin of "L." erythrognatha. The males of the three species had 2n = 22, n = 10+X 1 X 2 , all the chromosomes were telocentric and there was generally a single chiasma per bivalent. In "Lycosa" pampeana, which is described cytogenetically for the first time herein, the bivalents and sex chromosomes showed a clustered arrangement at prometaphase I. The comparison of the male/female karyotypes (2n = 22/24) of "Lycosa" erythrognatha revealed that the sex chromosomes were the largest of the complement and that the autosomes decreased gradually in size. The analysis of the amount, composition and distribution of heterochromatin with C-banding and staining with DAPI-and CMA 3-showed that "Lycosa" erythrognatha had little GC-rich heterochromatin in the pericentromeric region of all chromosomes. In addition, the actual occurrence of the genus Lycosa in the Southern Hemisphere is discussed.
Caryologia, 2001
The Pentatomidae are one of the largest families of Heteroptera with approximately 250 species cytogenetically analyzed. They possess holokinetic chromosomes, a modal diploid number of 14 (range 6-27) and a sex chromosome determining system XY/XX. Male karyotype and meiosis of Proxys albopunctulatus, Dichelops furcatus, Piezodorus guildinii, Loxa deducta (Pentatominae); Dinocoris prolineatus and Macropygium reticulare (Discocephalinae) from Argentina are analyzed. All these species are 2n= 14 (12 + XY), except D. furcatus with 2n= 12 (10 + XY) as consequence of an autosomal fusion. Meiosis follows the typical pattern of the order Heteroptera (pre-reduction of autosomes, postreduccion of sex chromosomes, and ring arrangement of autosomes at both metaphase plates with sex chromosomes inside it). These species show a great constancy in the diploid number, but some differences in the karyotype and meiotic behaviour are encountered (relative size of sex chromosomes, characteristics of the diffuse stage). In all the species except in M. reticulare, bivalents with two chiasmata are observed. We suggest that ring bivalents are not so uncommon as it has been previously supported.
Folia biologica (Kraków), 2003
So far, only seven and five species of Dysdercus from the Old and New Worlds, respectively, have been cytogenetically analysed. They all have holokinetic chromosomes and a pre-reductional type of meiosis. In the present study the chromosome complement, male meiosis and nucleolar meiotic cycle of Dysdercus imitator were analysed. During male meiosis several cytogenetic features are remarkable, namely the presence of a long diffuse stage after pachytene, the finding of one or two ring bivalents per cell in almost all specimens, and the presence of several prenucleolar bodies lasting up to telophase II. The origin and function of these prenucleolar bodies could be related to a particular physiological cycle of the meiocytes.