Jiří Král

The evolutionary origin of insect telomeric repeats, (TTAGG) n

RNA polymerase II is responsible for transcription of most eukaryotic genes, but, despite exhaustive analysis, little is known about how it transcribes natural templates in vivo. We studied polymerase dynamics in living Chinese hamster ovary cells using an established line that expresses the largest (catalytic) subunit of the polymerase (RPB1) tagged with the green fluorescent protein (GFP). Genetic complementation has shown this tagged polymerase to be fully functional. Fluorescence loss in photobleaching (FLIP) reveals the existence of at least three kinetic populations of tagged polymerase: a large rapidly-exchanging population, a small fraction resistant to 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) but sensitive to a different inhibitor of transcription (i.e. heat shock), and a third fraction sensitive to both inhibitors. Quantitative immunoblotting shows the largest fraction to be the inactive hypophosphorylated form of the polymerase (i.e. IIA). Results are consistent with the second (DRB-insensitive but heat-shock-sensitive) fraction being bound but not engaged, while the third (sensitive to both DRB and heat shock) is the elongating hyperphosphorylated form (i.e. IIO).

Phylogeny of entelegyne spiders: Affinities of the family Penestomidae (NEW RANK), generic phylogeny of Eresidae, and asymmetric rates of change in spinning organ evolution (Araneae, Araneoidea, Entelegynae)

Penestomine spiders were first described from females only and placed in the family Eresidae. Discovery of the male decades later brought surprises, especially in the morphology of the male pedipalp, which features (among other things) a retrolateral tibial apophysis (RTA). The presence of an RTA is synapomorphic for a large clade of spiders exclusive of Eresidae. A molecular data matrix based on four loci was constructed to test two alternative hypotheses: (1) penestomines are eresids and the RTA is convergent, or (2) penestomines belong within the RTA clade. Taxon sampling concentrated on the Eresidae and the RTA clade, especially outside of the Dionycha and Lycosoidea. Evolution of the cribellum, conventionally characterized as a primitive araneomorph spinning organ lost multiple times, is explored. Parsimony optimization indicates repeated appearances of the cribellum. Exploration of asymmetric rates of loss and gain in both a likelihood framework and using a Sankoff matrix under parsimony reveals that cribellum homology is supported when losses are two times more likely than gains. We suggest that when complicated characters appear (under parsimony optimization) to evolve multiple times, investigators should consider alternative reconstructions featuring a relatively high rate of loss. Evolution of other morphological characters is also investigated. The results imply revised circumscription of some RTA-clade families, including Agelenidae, Amaurobiidae, Cybaeidae, Dictynidae and Hahniidae. Some nomenclatural changes are formally proposed here; others await further investigation. The family Penestomidae (NEW RANK) is established. Tamgrinia, not Neoramia, is the cribellate sister clade of the ecribellate Agelenidae. Tamgrinia and the subfamily Coelotinae are transferred from the family Amaurobiidae to the family Agelenidae. Zanomys and its relatives are not coelotines but belong to a clade tentatively identified as Macrobuninae.

Evolution of the karyotype and sex chromosome systems in basal clades of araneomorph spiders (Araneae: Araneomorphae).

Concepts of spider karyotype evolution are based mostly on advanced and most diversified clade, the entelegyne lineage of araneomorph spiders. Hence the typical spider karyotype is supposed to consist exclusively of acrocentric chromosomes including the multiple X chromosomes. However, our data show considerable diversity of chromosome morphology and sex chromosome systems in basal clades of araneomorphs. Karyotypes of basal araneomorphs consist of holocentric (superfamily Dysderoidea) or normal chromosomes with localized centromere. In males of basal araneomorphs the prophase of first meiotic division includes a long diffuse stage. Multiple X chromosomes are less common in basal clades. The sex chromosome system of many families includes a Y chromosome or nucleolus organizer region that occurs rarely in the entelegyne spiders. A derived X1X2Y system with an achiasmatic sex-chromosome pairing during meiosis was found in the families Drymusidae, Hypochilidae, Filistatidae, Sicariidae, and Pholcidae. This suggests a monophyletic origin of the families. In some lineages the X1X2Y system converted into an X0 system, as found in some pholcids, or into an XY system, which is typical for the family Diguetidae. The remarkable karyotype and sex chromosome system diversity allows us to distinguish four evolutionary lineages of basal araneomorphs and hypothesize about the ancestral karyotype of araneomorphs.

Cytogenetic evidence for diversity of two nuclei within a single diplomonad cell of Giardia

Giardia intestinalis is an ancient protist that causes the most commonly reported human diarrheal disease of parasitic origin worldwide. An intriguing feature of the Giardia cell is the presence of two morphologically similar nuclei, generally considered equivalent, in spite of the fact that their karyotypes are unknown. We found that within a single cell, the two nuclei differ both in the number and the size of chromosomes and that representatives of two major genetic groups of G. intestinalis possess different karyotypes. Odd chromosome numbers indicate aneuploidy of Giardia nuclei, and their stable occurrence is suggestive of a long-term asexuality. A semi-open type of Giardia mitosis excludes a chromosome interfusion between the nuclei. Differences in karyotype and DNA content, and cell cycle-dependent asynchrony are indicative of diversity of the two Giardia nuclei.

NATURAL HISTORY AND KARYOTYPE OF SOME ANT-EATING ZODARIID SPIDERS (ARANEAE, ZODARIIDAE) FROM ISRAEL

Abstract Natural history, including phenology, circadian activity, mimicry, reproduction, prey specialization and karyotype was studied in the zodariid spiders Trygettus sexoculatus, Zodarion cyrenaicum, Z. lutipes and Z. nitidum (Zodariidae, Zodariinae) found in Israel. The spiders were active throughout the year, with maximum seasonal activity in the summer. Two distinct reproductive periods were found for Z. cyrenaicum and Z. nitidum, one in May and the other in November. Individuals of all species studied were observed hunting only in the morning. Three zodariid species were found to generally mimic ants: Trygettus sexoculatus mimicked tiny yellow-brown ants such as Monomorium niloticum, Z. cyrenaicum mimicked large black ants such as Messor arenarius, and Z. lutipes mimicked large yellow-brown ants such as Camponotus fellah. The zodariids observed were able to subdue various ant species, from the subfamilies Formicinae, Myrmicinae and Dolichoderinae. Trygettus sexoculatus appeared to specialize on Monomorium sp., Z. lutipes on Camponotus sp. and Z. cyrenaicum on Messor sp. ants, i.e., the same ant species they imitate. When bitten by zodariids, Formicinae and Dolichoderinae ants were paralyzed much more quickly than Myrmicinae. Female zodariid paralyzed ants faster than juveniles and males. Courtship and mating were observed only in Z. lutipes and were found to be similar to other Zodarion species. The mean fecundity for all three Zodarion species ranged from 38–45 eggs per egg sac, thus being higher than reported in central European species. Females of all three species guarded egg sacs inside of their retreats. Karyotypes of studied Zodarion spiders were similar to the karyotypes of other zodariid spiders in terms of the diploid number (26 in Z. cyrenaicum and 25 in both Z. lutipes and Z. nitidum), sex chromosome systems and morphology of chromosomes. Most of the data indicate that the Zodarion species of this study have a close affinity to a group of Western European Zodarion species.

A COMPARATIVE STUDY OF THE BIOLOGY AND KARYOTYPES OF TWO CENTRAL EUROPEAN ZODARIID SPIDERS (ARANEAE, ZODARIIDAE)

Abstract A comparison of the biology and karyotypes of Zodarion germanicum and Zodarion rubidum (Araneae, Zodariidae) which occur in central Europe was carried out. Surprisingly, these species were found to differ in a number of characters such as pattern of activity, reproduction and karyotypes. Zodarion germanicum was observed to be diurnal, whereas Z. rubidum is nocturnal. Courtship and mating were markedly longer and more complex in Z. germanicum than in Z. rubidum. Females of Z. germanicum produced only one or two successive egg sacs including 17 eggs on average which they would guard, while females of Z. rubidum produced up to 5 egg sacs each having 4 eggs that they abandoned. The two species differ from each other also in number of chromosomes and the sex chromosome system. Results suggest these species belong to distant evolutionary lineages within the genus Zodarion.

The Spider Genus Dysdera (Araneae, Dysderidae) In Central Europe: Revision And Natural History

Abstract Nine species of the genus Dysdera were found to occur in central Europe: D. adriatica Kulczyński 1897, D. crocata Koch 1838, D. dubrovninnii Deeleman-Reinhold 1988, D. erythrina (Walckenaer 1802), D. ninnii Canestrini 1868, D. hungarica Kulczyński 1897, D. lantosquensis Simon 1882, D. longirostris Doblika 1853, and D. taurica Charitonov 1956. Two species, D. dubrovninnii and D. lantosquensis, are newly recorded from central Europe. The original description of D. hombergi (Scopoli 1763), the name used for a common species of the genus Harpactea, probably refers to D. ninnii. We retain the name D. ninnii as a nomen protectum. Dysdera hamulata Kulczyński 1897 appears to be a junior synonym of D. maurusia Thorell 1873. This North African species probably does not occur in central Europe, and a previous record from Slovakia is probably based on mislabeled material. A review of all species of Dysdera named from outside the Palearctic region demonstrated that D. australiensis Rainbow 1900 and D. magna Keyserling 1877 are junior synonyms of D. crocata, and that D. bicolor Tatzanovski 1874 and D. solers Walckenaer 1837 are erroneously placed in the genus Dysdera; the former is likely to be an oonopid and the latter a caponiid. In central Europe, Dysdera spiders prefer xerothermic forests, particularly sites enriched by calcium. All species probably have biennal life-cycles. The karyotype of males of seven species were examined, and diploid chromosome numbers were found to be extraordinarily variable, ranging from 9 (D. crocata) to 40 (D. longirostris). Karyotypes consist of holocentric chromosomes.

Evolution of multiple sex chromosomes in the spider genus Malthonica (Araneae: Agelenidae) indicates unique structure of the spider sex chromosome systems

Most spiders exhibit a multiple sex chromosome system, X1X20, whose origin has not been satisfactorily explained. Examination of the sex chromosome systems in the spider genus Malthonica (Agelenidae) revealed considerable diversity in sex chromosome constitution within this group. Besides modes X1X20 (M. silvestris) and X1X2X30 (M. campestris), a neo-X1X2X3X4X5Y system in M. ferruginea was found. Ultrastructural analysis of spread pachytene spermatocytes revealed that the X1X20 and X1X2X30 systems include a pair of homomorphic sex chromosomes. Multiple X chromosomes and the pair exhibit an end-to-end pairing, being connected by attachment plaques. The X1X2X3X4X5Y system of M. ferruginea arose by rearrangement between the homomorphic sex chromosome pair and an autosome. Multiple X chromosomes and the sex chromosome pair do not differ from autosomes in a pattern of constitutive heterochromatin. Ultrastructural data on sex chromosome pairing in other spiders indicate that the homomorphic sex chromosome pair forms an integral part of the spider sex chromosome systems. It is suggested that this pair represents ancestral sex chromosomes of spiders, which generated multiple X chromosomes by non-disjunctions. Structural differentiation of newly formed X chromosomes has been facilitated by heterochromatinization of sex chromosome bivalents observed in prophase I of spider females.

Karyotype of Trichomonas vaginalis

Summary At present, information on ploidy, number and morphology of chromosomes in protozoa is scarce. Thus, we investigated the karyotype of the parasitic protozoon, Trichomonas vaginalis. The metaphase chromosomes from colchicin-treated cells were obtained by a spreading technique using Carnoy fixative and Giemsa staining. The karyotype of T. vaginalis is haploid and consists of six different monocentric chromosomes ranging from 2.40 to 1.00 μn. A typical karyotype consists of 1 metacentric, 1 metacentric/submetacentric, 1 submetacentric/subtelocentric, 1 subtelocentric/acrocentric and 2 acrocentric chromosomes. The nature of the chromosome constrictions, the probable occurrence of meiosis and the reciprocal relationship between diploid/haploid phases are discussed. Comparison of our results with previous data indicates only a small variation in chromosome numbers during the karyotype evolution of the subfamily Trichomonadinae. Morphology of the centromeric area in T. vaginalis seems to be different from those described earlier in the class Hypermastigotea and in a devescovinid trichomonad, Caduceia theobromae.

Insights into the Meiotic Behavior and Evolution of Multiple Sex Chromosome Systems in Spiders

A characteristic feature of spider karyotypes is the predominance of unusual multiple X chromosomes. To elucidate the evolution of spider sex chromosomes, their meiotic behavior was analyzed in 2 major clades of opisthothele spiders, namely, the entelegyne araneomorphs and the mygalomorphs. Our data support the predominance of X1X20 systems in entelegynes, while rare X1X2X3X40 systems were revealed in the tuberculote mygalomorphs. The spider species studied exhibited a considerable diversity of achiasmate sex chromosome pairing in male meiosis. The end-to-end pairing of sex chromosomes found in mygalomorphs was gradually replaced by the parallel attachment of sex chromosomes in entelegynes. The observed association of male X univalents with a centrosome at the first meiotic division may ensure the univalents’ segregation. Spider meiotic sex chromosomes also showed other unique traits, namely, association with a chromosome pair in males and inactivation in females. Analysis of these traits supports the hypothesis that the multiple X chromosomes of spiders originated by duplications. In contrast to the homogametic sex of other animals, the homologous sex chromosomes of spider females were already paired at premeiotic interphase and were inactivated until prophase I. Furthermore, the sex chromosome pairs exhibited an end-to-end association during these stages. We suggest that the specific behavior of the female sex chromosomes may have evolved to avoid the negative effects of duplicated X chromosomes on female meiosis. The chromosome ends that ensure the association of sex chromosome pairs during meiosis may contain information for discriminating between homologous and homeologous X chromosomes and thus act to promote homologous pairing. The meiotic behavior of 4 X chromosome pairs in mygalomorph females, namely, the formation of 2 associations, each composed of 2 pairs with similar structure, suggests that the mygalomorph X1X2X3X40 system originated by the duplication of the X1X20 system via nondisjunctions or polyploidization.