Evolutionary Potential of Parthenogenesis-Bisexual Lineages within Triploid Apomictic Thelytoky in (Flor, 1861) (Hemiptera, Psylloidea) in Fennoscandia.

A widely accepted hypothesis is that parthenogenesis is an evolutionary dead end since it is selectively advantageous in the short term only but results in lowered diversification rates. Triploid apomictic parthenogenesis might represent an exception, as in favorable environments, triploid females are able to produce rare males and diploid females. The aim of the present study was to analyze the modes of reproduction and their evolutionary implications in the parthenogenetic psyllid (Flor, 1861) from Fennoscandia.

The Incidence of Bacterial Endosymbiont in Bisexual and Parthenogenetic Populations of the Psyllid Genus (Hemiptera, Psylloidea).

is one of the most common intracellular bacteria; it infects a wide variety of insects, other arthropods, and some nematodes. is ordinarily transmitted vertically from mother to offspring and can manipulate physiology and reproduction of their hosts in different ways, e.g.

Description of two new species of the genus Ossiannilsson, 1970 (Hemiptera, Psylloidea) from northern Fennoscandia recognized by morphology, cytogenetic characters and barcode sequence.

Based on chromosomal, molecular and morphological analyses, two new Ossiannilsson, 1970 species are described, S. Nokkala & Ch. Nokkala, and S.

Characteristics of parthenogenesis in (Flor, 1861) (Hemiptera, Sternorryncha, Psylloidea): cytological and molecular approaches.

Characteristics of parthenogenesis in (Flor, 1861) were analyzed using cytological and molecular approaches. In all three populations studied from Finland, i.e.

Meiosis in rare males in parthenogenetic Cacopsylla myrtilli (Wagner, 1947) (Hemiptera, Psyllidae) populations from northern Europe.

For studying meiosis in males, large samples of Cacopsylla myrtilli (Wagner, 1947) (Hemiptera, Psyllidae) were collected in Norway, Sweden, Finland and northwest Russia. In addition to all-female populations, males were present in 10 out of 47 populations; still, all populations were highly female-biased, the proportion of males varying from 0.1% to 9.

Cytogenetics of the true bug infraorder Cimicomorpha (Hemiptera, Heteroptera): a review.

The Cimicomorpha is one of the largest and highly diversified infraorders of the Heteroptera. This group is also highly diversified cytogenetically and demonstrates a number of unusual cytogenetic characters such as holokinetic chromosomes; m-chromosomes; multiple sex chromosome systems; post-reduction of sex chromosomes in meiosis; variation in the presence/absence of chiasmata in spermatogenesis; different types of achiasmate meiosis. We present here a review of essential cytogenetic characters of the Cimicomorpha and outline the chief objectives and goals of future investigations in the field.

Dm nxf1/sbr gene affects the formation of meiotic spindle in female Drosophila melanogaster.

The small bristles (sbr) gene of Drosophila melanogaster belongs to the family of nuclear export factor (NXF) genes that participate in mRNA nuclear export. During meiosis, females of Drosophila melanogaster that carry various combinations of mutant alleles of the Dm nxf1/sbr gene exhibit disruption of the division spindle and misalignment of chromosomes at the metaphase plate. Meiosis of sbr ( 5 ) /+ females is characterized by the formation of tripolar spindles during the first cell division.

The distribution and population sex ratio of Cacopsylla myrtilli (W. Wagner, 1947) (Hemiptera: Psylloidea).

In Cacopsylla myrtilli (W. Wagner, 1947) bisexual populations, all-female populations and populations heavily biased towards females have been described. In the present paper all the available data on the distribution and population sex ratio of C.

Holocentric chromosomes of psocids (Insecta, Psocoptera) analysed by C-banding, silver impregnation and sequence specific fluorochromes CMA3 and DAPI.

The pattern of nucleolus attachment and C-heterochromatin distribution and molecular composition in the karyotypes of psocid species Psococerastis gibbosa (2n = 16+X), Blaste conspurcata (2n = 16+X) and Amphipsocus japonicus (2n = 14+neo-XY) were studied by C-banding, silver impregnation and sequence specific fluorochromes CMA3 and DAPI. Every species was found to have a single nucleolus in male meiosis. In P.

First evidence of polyploidy in Psylloidea (Homoptera, Sternorrhyncha): a parthenogenetic population of Cacopsylla myrtilli (W. Wagner, 1947) from northeast Finland is apomictic and triploid.

This paper reports results of the first cytogenetic study of parthenogenetic psyllids, carried out on an asexual population of the holarctic species Cacopsylla myrtilli W. Wagner from northeast Finland. Preparations of mature eggs extracted from females revealed 39 univalent chromosomes in prophase and metaphase cells.

Cytogenetic characterization of the Trinidad endemic, Arachnocoris trinitatus Bergroth: the first data for the tribe Arachnocorini (Heteroptera: Cimicomorpha: Nabidae).

As an extension of the ongoing cytogenetic studies of the bug family Nabidae (Heteroptera: Cimicomorpha), the first evidence for the tribe Arachnocorini (the subfamily Nabinae), with reference to the Trinidad endemic, Arachnocoris trinitatus Bergroth, is provided. This is an attempt to gain a better insight into the evolution, systematics and within-family relationships of the family Nabidae. The studies were conducted using a number of cytogenetic techniques.

Automictic and apomictic parthenogenesis in psocids (Insecta: Psocoptera).

Karyotypes and meiosis patterns in three obligatory thelytokous Psocoptera species have been studied for the first time. Females of Aaroniella badonneli (Danks) display 9 chiasmatic bivalents in oocyte metaphase I (2n = 18), hence meiosis is of the automictic type. Females of Ectopsocus meridionalis Ribaga and Valenzuela sp.

First evidence of sex chromosome pre-reduction in male meiosis in the Miridae bugs (Heteroptera).

The karyotype and male meiosis of Macrolophus costalis Fieber (Insecta, Heteroptera, Miridae) were studied using C-banding, AgNOR-banding and DNA sequence specific fluorochrome staining. The chromosome formula of the species is 2n = 28(24+X1X2X3Y). Male meiotic prophase is characterized by a prominent condensation stage.

Role of Jun N-terminal Kinase (JNK) signaling in the wound healing and regeneration of a Drosophila melanogaster wing imaginal disc.

When a fragment of a Drosophila imaginal disc is cultured in growth permissive conditions, it either regenerates the missing structures or duplicates the pattern present in the fragment. This kind of pattern regulation is known to be epimorphic, i.e.

Dynamics of decapentaplegic expression during regeneration of the Drosophila melanogaster wing imaginal disc.

Regeneration of an imaginal disc involves highly ordered proliferation and pattern regulation of the newly formed tissue. Although the general principles of imaginal disc regeneration have been extensively studied, knowledge of the underlying molecular mechanisms is far from complete. Results from other model organisms suggest that regeneration is the result of local recapitulation of the normal patterning genes.

A new approach to the auchenorrhyncha (Hemiptera, Insecta) cytogenetics: chromosomes of the meadow spittlebug Philaenus spumarius (L.) examined using various chromosome banding techniques.

The karyotype of the meadow spittlebug Philaenus spumarius (L.) was studied using conventional chromosome staining, C- and AgNOR- banding, and fluorescent CMA3- and DAPI- techniques. This is the first report on differential staining of the holocentric chromosomes of Auchenorrhyncha.

C-heterochromatin and extra (B) chromosome distribution in six species of the Nabis (Heteroptera, Nabidae) with the modal male karyotype 2n = 16 + XY.

The basic male karyotype of the six Nabis species (Heteroptera, Nabidae) is confirmed as being 2n=16+XY. The chromosomes are holokinetic while male meiosis is achiasmatic. The sex chromosomes undergo postreduction and in second metaphase show distance pairing, registered in all nabid species examined so far.

The origin of the achiasmatic XY sex chromosome system in Cacopsylla peregrina (Frst.) (Psylloidea, Homoptera).

The status of an extra univalent, if it is a B chromosome or an achiasmatic Y chromosome, associating with the X chromosome in male meiosis of Cacopsylla peregrina (Frst.) (Homoptera, Psylloidea) was analysed. One extra univalent was present in all males collected from three geographically well separated populations, it was mitotically stable, and showed precise segregation from the X chromosome.

Mitotic and meiotic chromosomes in Somatochlora metallica (Cordulidae, Odonata). The absence of localized centromeres and inverted meiosis.

Spermatogonial metaphase chromosomes were examined in two dragonfly species, Somatochlora metallica (Cordulidae) and Aeshna grandis (Aeshnidae), and the behaviour of male meiotic chromosomes was studied in S. metallica. Both in S.