Random arrangement of chromosomes inUvularia (Liliaceae)

Chromosome arrangement in interphase has been inferred from an analysis of the relative positions of the chromosomes and the chromosome arms in untreated haploid pollen grain metaphases ofUvularia grandiflora. The distances between centromeres forming the smallest possible circle were measured in 43 metaphases. The relative positions of the chromosomes did not differ significantly from randomness. Neither did similar-sized chromosome arms show any tendency to be next to each other. The results thus disagree both with the hypothesis ofComings (1968) that each chromosome occupies a definite position in the interphase nucleus and with the claim ofBennett (1982) that similar-sized chromosome arms lie next to each other.     

Reversion of XO to XY sex chromosome mechanism in a phasmid

Summary The sex chromosomes of the male phasmid Isagoras schraderi Rehn comprise an X and a Y, — each with a submedian kinetochore, and one euchromatic and one heterochromatic arm. At meiosis X and Y form an unequal sex bivalent in which the euchromatic arms are terminally associated. Relatively recent reversion from the XO-XX mechanism characteristic of the Phasmidae is indicated by the presence of the euchromatic arm in both X and Y. The diploid number of the male is 34.Unequal autosomal bivalents are found at meiosis in two other species of Isagoras — Isagoras subaquiles Rehn and Isagoras sp. — and in Pseudophasma menius Westwood. The chromosome complements of these species are described.     

Coulonia parva n. sp., a new species of Astropectinidae (Asteroidea; Echinodermata) from the Santonian (Upper Cretaceous) of Sierra de Montsech (southern Pyrenees, Spain)

A new astropectinid sea star,Coulonia parva n. sp., is described from the Santonian of the Sierra de Montsech, northern Spain. The single specimen shows part of a rather weathered ventral side. It is characterized by comparatively long arms (R/r approx. 3/1), with one row of actinals reaching far into the arms; inferomarginals on the interbrachial arc have deep fasciolar grooves that are less developed on the arms; there are no larger spines on adambulacrals and probably also on inferomarginals. Based on presence of deep marginal fascioles,C. parva n. sp. is inferred to have shared the capability for self-burial with the relatedC. platyspina Hess &Blake.      

Chromosomes of three freshwater stingrays (Rajiformes Potamotrygonidae) from the Rio Negro basin, Amazon, Brazil

Potamotrygonidae is the representative family of South American freshwater elasmobranchs. It is a monophyletic group containing 20 species grouped into three genera. Three species belonging to two genera of this family were collected from the middle Negro River, Amazonas, Brazil, and studied cytogenetically: Paratrygon aiereba, Potamotrygon motoro and Potamotrygon orbignyi. Paratrygon aiereba presented 2n = 90 chromosomes and 4M+2SM+10ST+74A. Both species of Potamotrygon presented 2n = 66 chromosomes and differed in their chromosomal formulas: P. motoro had 18M+12SM+10ST+26A and P. orbignyi had 22M+10SM+8ST+26A. No sex heteromorphism was detected. The Fundamental Number (FN) was 106 for the three species. A system of multiple NORs was found in the three species, but with interspecific differences in terms of location and position of the active Ag-NORs sites. Paratrygon aiereba presented only four sites on the short arms of two chromosomal pairs, both in terminal regions. Potamotrygon motoro presented seven sites, on the long and short arms, all in terminal regions of non-homologous chromosomes; P. orbignyi presented eight sites on the long arms, all in terminal regions, of non-homologous chromosomes. The constitutive heterochromatin was in pericentromeric regions of all chromosomes, and no significant interspecific difference was found in relation to this marker.     

Further studies on polyploid amphibians (Ceratophrydidawe)

Odontophrynus cultripes Reinhardt and Lutken, 1862 has 22 chromosomes in its diploid complement. Spermatocyte I contained 11 ring bivalents and metaphase II exhibited 11 chromosomes. Odontophrynus americanus (Duméril and Bibron) 1882 has 44 chromosomes in somatic as well as germ cells, these can be sorted into 11 groups of homologues. Metaphase I showed varying numbers of quadrivalents and metaphase II exhibited 22 dyads. Ceratophrys dorsata Wied., 1824 has 104 chromosomes in somatic and germ cells; these 104 chromosomes comprise 8 each of 13 kinds of homologues. The spermatocyte I contained ring octovalents and other multivalents, and metaphase II 52 chromosomes. The above findings indicate that evolution by polyploidization occurred in South American frogs belonging to the family Ceratophrydidae.This work was supported by a grant (GM-14577-01) from the National Institute of General Medical Sciences U. S. Public Health Service.     

The chromosomes of Dall's porpoise,Phocoenoides dallii (True), with remarks on the phylogenetic relation of the Cetacea

Summary The chromosome complex of Dall's porpoise Phocoenoides dallii (True), a species of the Delphinidae (Cetacea), was investigated in male germ cells during the course of spermatogenesis. The diploid number of chromosomes in this species was 44 in the spermatogonia and the haploid number was 22 in both primary and secondary spermatocytes. Sex chromosomes of the typical XY-type were found to occur in this species. The X element is represented by one of the medium-sized chromosomes of rod-type characterized by a globular body located at its inner extremity, while the Y is very minute, attaining a size approximately one third that of the smallest autosome.Morphological analysis of the chromosomes shows the chromosome complement of this species to be strikingly characterized by the prevalence of medium-sized elements having subterminal fibre attachments. Comparison of the chromosomes with those of related forms of mammals shows that the chromosome constitution of this species approximates closely that of the pig. The question of the phylogenetical affinity of the Cetacea was discussed on the basis of the karyological evidence here reported.Contribution No. 213 form the Zoological Institute, Faculty of Science, Hokkaido University, Sapporo, Japan.     

The genetical control of tissue-specific peroxidases,Per-1,Per-2,Per-3,Per-4, andPer-5 in wheat

Summary Isoelectric focusing (IEF) of extracts from different tissues of hexaploid wheat cv Chinese Spring provided a method of distinguishing and identifying the four known, and one newly discovered, sets of genes encoding peroxidase isozyme production.Per-1, carried on the short arms of homoeologous group 1 chromosomes, shows a high degree of conservation and is active in coleoptile tissue.Per-2, carried on the short arms of group 2 chromosomes, shows some polymorphism and is most active in root tissue.Per-3, on the long arms of group 3 chromosomes, is highly variable and most active in embryo tissue.Per-4, carried on chromosome arms7AS,4AL, and7DS, is quite variable and most active in endosperm tissue. (The chromosome nomenclature used in this paper is that agreed to by the 7th International Wheat Genetics Symposium, where the previous designations of4A and4B were reversed.) Restriction fragment length polymorphism (RFLP)-based maps of the group 7 chromosomes were used to locatePer-A4 to a distal region of7AS. In addition, a further set of genes was identified as being active in root tissue. In wheat a single locus,Per-D5, was found on chromosome arm2DS.     

Heterochromatin and cytogenetic polymorphisms in Cebus apella (Cebidae,Platyrrhini)

Cytogenetic studies have been carried out in 39 specimens of C. apella of different origins. Three different morphologies, one affecting the long arm of chromosome 4 and two affecting pair 17, have been detected. In each case, they can be related by paracentric inversions. Heterochromatin polymorphisms affecting terminal or interstitial C+ regions have also been observed. The length of the terminal heterochromatic region in the long arms of chromosome 11 is variable in C. apella sp., in C. a. paraguayanus and absent in the C. a. nigritus specimens studied. Interstitial C + bands can be observed in the long arms of the biarmed chromosomes 4 and 6, and in the long arms of the acrocentric pairs 12, 13, 17, 18, 19, 20, and 21. Interstitial C + bands in the long arms of chromosomes 4, 12, 17, and 19 are present in all animals studied, although their size is variable, especially in the case of chromosomes 17 and 19. © 1995 Wiley-Liss, Inc.     

Die kinetische Organisation der Lepidopteren-Chromosomen

In monokinetic chromosomes half of the recombinations from reciprocal translocation are expected to be lethal owing to the formation of bikinetic and akinetic chromosomes. In holokinetic chromosomes all reciprocal recombinations should be viable, because all again are holokinetic. This difference can be used as a tool other than the study of fragment behaviour to decide which type of chromosome is present in an animal species. — Pieris brassicae males X-rayed with 6,000 r units and mated to normal females gave in F₁ only 19.9% lethal zygotes (14.7% of which dying late) as compared to a control mortality of about 7.7%. Among the hatched male caterpillars cytologically tested in the last larval instar 64.9% contained in their spermatocytes 1 to 4 heterozygous translocation rings or chains consisting of from 4 to 14 chromosomes. Translocations of similar frequency and even greater complexity have been observed in preliminary experiments on Philosamia cynthia. — The discrepancy between these results and those on species with monokinetic chromosomes (Drosophila, Phryne etc.) where very high zygotic lethality is observed at comparable Röntgen doses is proof of the holokinetic nature of Pieris and Philosamia chromosomes. Together with earlier results on Bombyx mori by Astaurow and Frolowa and the cytogenetic studies especially by Seiler sufficient proof exists to conclude that all Lepidoptera have holokinetic chromosomes. — A survey of the known groups of organisms with chromosomes of this type leads to the assumption that holokinetic chromosomes must be derived from monokinetic ones. The problems connected with this change in kinetic organisation of chromosomes are discussed.

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Herrn Professor Dr. J. Seiler ist diese Arbeit in herzlicher Dankbarkeit für in mehr als 40 Jahren gewachsene Freundschaft zu seinem achtzigsten Geburtstag gewidmet worden.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Endomitosis in the mealy bug,Planococcus citri (Homoptera: Coccoidea)

Endomitosis in the Malpighian tubules of the mealy bug Planococcus citri (Risso) is described. The stages are identified on the basis of the length of the chromosomes and the distance between the sister chromatids or chromosomes. The appearance of the chromosomes in the various stages of endomitosis is compared to that in other hemipteran insects. During anaphase and telophase of endomitosis the ends of the sister chromatids and chromosomes tend to stay together longer than the other parts. It is suggested that in holokinetic chromosomes special regions for holding the chromatids together are concentrated near the ends of the chromosomes.Supported by grant GB1585 from the National Science Foundation, Washington, D.C.     

Taxonomy of the genusBrimeura (Hyacinthaceae)

A taxonomic reevaluation of two little-knownBrimeura taxa,B. fontqueri (Pau)Speta andB. duvigneaudii (L. Llorens)Rosselló et al., has been made.Brimeura fontqueri, described from the Iberian peninsula, has been put into synonymy ofB. amethystina (L.)Salisb., since it could not be distinguished on morphological, anatomical or cytogenetic grounds.Brimeura duvigneaudii, from the Balearic Islands, is closely related toB. amethystina and has 2n=28 chromosomes. It differs from the latter by its naked bulbs lacking dark cataphylls, and its narrower leaves and whitish corollas. Accessory chromosomes are reported for the first time in the genus. Karyological instability (with chromosome numbers ranging from 2n=28 to 42) is reported for a population ofB. fastigiata (Viv.)Chouard. A key to the recognized taxa ofBrimeura is provided.     

Variation of the chromosome phenotype in zea,solanum and salvia

Summary InSolanum lycopersicum pachytene chromosomes the gradient in chromomere size, originating on both sides of the kinetochore, reveals the following characteristics: 1. a relatively abrupt decrease in size of the large chromomeres, 2. the gradient is related to arm length in 9 of the 12 chromosomes, 3. the gradient is particularly irregular in the short arm of the nucleolar chromosome and in the long arm is not conspicuous, 4. chromosome 6 shows an abrupt interruption in the gradient close to the kinetochore. Salvia viridis andZea mays chromosomes represent intermediate conditions between species with well defined and species without gradients. InSalvia the intermediate condition is manifested by the presence of a very large chromomere on each side of the kinetochore followed by very small chromomeres. In two chromosomes the intermediate condition is particularly apparent. In these chromosomes two chromomeres of intermediate size are present in the proximal region of the long arm. The nucleolar organizing arm has also an irregular pattern in this species.Maize has a less distinct gradient than tomato in all its chromosomes. Chromosomes 3, 4, 5 and 8 are those where the gradient is the least sharp. The nucleolar organizing arm of chromosome 6 has also an irregular pattern.In a translocation between chromosomes 5 and 6 of maize, a segment composed of very small chromomeres from the distal region of 5 which was moved to the right of the kinetochore of chromosome 6, did not change appreciably its phenotype after ten years of cultivation. During the period of cultivation a selection was made for plants where the original phenotype was preserved so that this result cannot be considered as demonstrating an absence of change in chromomere phenotype with changed position.InDrosophila andChironomus salivary gland chromosomes where chromomeres are large, and no selection has been carried out with such a purpose, the pattern and nucleic acid content of the bands is known to change when rearrangements occur within the chromosome.Supported by a grant from the Swedish Natural Science Research Council toA. Lima-De-Faria. This work was partly carried out at the Department of Botany, University of Illinois, U.S.A. during a visit to this department byA. Lima-De-Faria.P. Sarvella's collaboration in this work was done during her stay at the University of Lund.     

Differences between genetic and physical centromere distances in the case of two genes for male sterility in barley

Summary Linkage studies with thirty translocations (one of the two chromosomes involved being number 4) in relation to msg24 (chromosome 4) and thirteen translocations (one of the two chromosomes involved being number 6) in relation to msg6 (chromosome 6) show without exception close linkage for all combinations tested. The results indicate that both genes are located genetically in or close to the centromere regions of their chromosomes.Cytological analysis of two BTT stocks (balanced tertiary trisomics) ascertained the respective chromosome arms (both msg24 and msg6 on the short arms) and revealed marked differences between genetic and physical centromere distances. The reason is obviously the high content of centromeric heterochromatin occupying both the chromosome arms involved.     

Constitutive heterochromatin,G-bands and nucleolus-organizer regions in four species of Didelphidae (Marsupialia)

Chromosomes of Didelphis albiventris, D. marsupialis, Philander opossum and Lutreolina crassicaudata, four species of marsupials with very similar karyotypes and 2n=22 were studied. All the chromosomes were acrocentrics except the X in L. crassicaudata, which is a metacentric.The G-band patterns of these species are similar but the distribution of constitutive heterochromatin differs among them as shown by C-banding. The hypothesis that the X in L. crassicaudata might be an isochromosome derived from the acrocentric X in the other species is discarded since G-and C-banding patterns differ in the two arms.In D. marsupialis the Ag-NORs are terminal and located in both arms of one pair and in the long arms of two pairs of medium-sized autosomes. In P. opossum the NOR-bearing chromosomes could be precisely identified through simultaneous silver staining and G-banding. The Ag-NORs are terminal and located at the short arm of pair 5 and the long arm of pair 7.     

New observations on lecanoid spermatogenesis in the mealy bug,Planococcus citri

Summary A reexamination of the second spermatogenic division of the mealy bug, Planococcus citri (Risso), a lecanoid coccid, has revealed hitherto unknown spindle activity of the euchromatic set of chromosomes during anaphase II. An initial large half spindle elaborated by the heterochromatic chromosomes in early metaphase, gives way to a less pronounced, but clearly visible bipolar spindle involving both sets of chromosomes at early anaphase. There is no lengthening of the spindle or cell, but the separation of the chromosomes occurs around the periphery of the cell with the aid of interzonal activity. The active participation of the euchromatic chromosome during the separation is furthermore inferred by the formation of bridges resulting from euchromatic-heterochromatic translocations.     

Overproduction of d-hydantoinase and carbamoylase in a soluble form in Escherichia coli

The production of d-hydantoinase and carbamoylase from Agrobacterium radiobacter NRRL B11291 using T7 and trc promoters, respectively, was found to cause protein aggregates in Escherichia coli. We initiated a systematic study aimed at overproducting these two proteins in a soluble form. As a result, the protein aggregate from carbamoylase overproduction could be alleviated with the aid of GroEL/GroES. In contrast, the production of a high level of d-hydantoinase in an active form can be achieved at low temperature (25 °C) or by the coproduction of DnaJ/DnaK. Overall, with such approaches both recombinant proteins gain more than a four-fold increase in enzyme activity. In addition, by fusion with thioredoxin, d-hydantoinase activity can be increased 25% more than the unfused counterpart in the presence of DnaJ/DnaK. These results indicate the success of our approaches to overproducing d-hydantoinase and carbamoylase in a soluble form in E. coli. Received: 26 November 1999 / Received revision: 28 February 2000 / Accepted: 10 March 2000     

Cytogenetic evidence for the specific distinction of an Alaskan marmot,Marmota broweri Hall and Gilmore (Mammalia: Sciuridae)

Summary Cytogenetic studies based upon somatic cells (bone marrow) have disclosed that the marmot hitherto designated Marmota caligata broweri Hall and Gilmore, occurring in the Brooks Range of arctic Alaska, differs from M. c. caligata (Eschscholtz) in number of chromosomes (2n=36 as compared with 2n=42 in M. caligata) and in proportions of chromosomal types. Typical karyograms for the two species are presented. It is concluded that the Brooks Range marmot is specifically distinct from M. caligata, the applicable name being Marmota broweri Hall and Gilmore. Also determined were diploid chromosome numbers for two other Nearctic species of marmots, M. flaviventris (Audubon and Bachman), with 42, and M. olympus (Merriam), with 40. It is suggested that M. broweri survived the last (Wisconsin) glaciations in the amphi-Beringian refugium, and that its closest affinities may be with one of the Eurasian species of Marmota.     

Die intraspezifische Variabilität des heterochromatischen Armes eines Chromosoms bei der GattungCarabus L. (Coleoptera)

The chromosome complement ofC. auronitens Fabr. is 2n _♂=26+XY. One autosomal pair—called A-chromosomes—is relatively long.A-chromosomes consist of a euchromatic and a heterochromatic arm. Labelling of mitotic chromosomes with³H-thymidine shows that replication of the heterochromatic arm continues when it has ended in the euchromatic arm. In males and females the length of the heterochromatic arm varies intraindividually. In 47 of 99 males the heterochromatic arms were heteromorphic. Calculations of the quotient length of the euchromatic/length of the heterochromatic arm have shown that at least 6 different types of the A-chromosome exist. These types differ from each other in the number of heterochromatic sections separated by constrictions. The longest heterochromatic arm observed consisted of 8 such sections. The genetic significance of the heterochromatin in the genus ofCarabus is at present unknown (Zusammenfassung see p.305).      

Hermaphroditism in icerya zeteki cockerell,and the mechanism of gonial reduction in iceryine coccids (coccoidea: Margarodidae morrison)

In the Panamanian iceryine coccid Icerya zeteki Cockerell (Family Margarodidae Morrison) all females become hermaphroditic early in the first instar; occasional males arise from unfertilized eggs, but self-fertilization is assured by the protandry of the hermaphrodite. In the development of the ovotestis, initiation of the male phase is brought about by haploidization of those germ cells destined for spermatogenesis. In both Icerya zeteki and Icerya purchasi this gonial reduction results from the degeneration and elimination of one genome during prophase. Except for minor variations in the coiling cycle of spermatocytes, the chromosomes (n=2) of I. zeteki correspond closely to those of all other haplo-diploid iceryines known. The present status of the species Icerya zeteki Cockerell is reviewed, and on both taxonomicand cytological grounds is judged to be uncertain.Supported in part by National Science Foundation Grant GB — 1922.     

Fine structure of meiotic chromosomes comparative study of nine species of insects

A comparative electron microscope study at magnifications ranging from about 80,000 up to 800,000 x was carried out in nine species of insects (Gryllus argentinus, Myogryllus verticalis, undetermined species of Gryllus; Blaptica dubia, Periplaneta americana, Blattella germanica; Laplatacris dispar, Aleua lineata and Omexechae servillei). Particular attention was paid: a) to the elementary components of the s. complexes and b) to the structure of their medial ribbon. - a) In all the species examined the basic element found is a curled filament some 15–20 Å thick. Filaments of this kind integrate: the 100 Å fibrils of the chromosome body, the compacts layers of the s. complexes (lateral arms) and the slender planes of the pairing space. The filaments are similar to those described in metaphase chromosomes and their kinetochores (Wettstein and Sotelo, 1965). A difference in density between the filaments of the lateral arms and those of the medial planes is sometimes noticed. - b) Three structural patterns were found in the pairing space. In crickets, the medial ribbon is composed of three parallel, longitudinal planes of filaments, interconnected and connected with the lateral arms by means of bridges. The latter are constituted by fibrils or by single filaments. In cockroaches only two longitudinal planes were found. The distribution of components in these planes follows a plan similar to the one found in crickets. In the electron-micrographs the medial component of both groups of Insecta appears as composed of three (crickets) or two (cockroaches) lines in the longitudinal frontal views, and ladder-like striated in lateral views. The latter striae correspond to filaments or groups of filaments running in antero-posterior direction. - The pattern of structure of grasshoppers differs completely from those mentioned above. Bridging between the homologues is made of regularly spaced transversal planes of filaments. No longitudinal array was observed.This investigation was supported by United States Public Health Service Research Grant GM 08337 from the Research Grants Branch, Division of Medical Sciences, and partly by Grant RF 61034 from The Rockefeller Foundation.