Hierarchy of organization in eukaryotic chromosomes (a review)

Summary Several models of macromolecular arrangements in eukaryotic chromosomes have been proposed during the past fifteen years. Many of the models are consistent with physical and chemical data on the molecular components of chromosomes, and a few have the appearance of meeting the requirements for cytological organization in chromosomes. However, one of the most frustrating problems in developing a working model is to provide a scheme that fits genetic function while satisfying the structural parameters. This has not yet been achieved.Although emphasis in this review has been placed on uninemic and polynemic models, alternatives, such as a bineme, for example, remain. It is clear, moreover, that the issue can be resolved only through continued efforts to make direct observations of chromosomes with light and electron microscopy coupled with the additional tools ofX-ray analysis and analytical biochemistry. A recent analysis byWray andStubblefield (1969) has led to a rather innovative model of the chromosome, and exemplifies the kind of approach needed to clarify the phenomenon. Furthermore, analyses of meiotic chromosomes may provide valuable insight for relating organization to genetic function (cf Maguire, 1966 andBraselton, pers. comm). Of particular interest are mutation events as related to subchromatid organization, and the reorganization of chromosomal fibrils during early meiotic stages. At present, and as a generalization, the evidence points more strongly toward at least a binemic arrangement of chromosomal subunits than toward a uninemic one.     

Mitosis with undivided chromosomes

Summary Cases of cell division with single chromatids are discussed in connection with a study on mitosis with undivided chromosomes made on living material of the endosperm of Haemanthus katharinae. Such divisions are known from certain abnormal mitoses in the microspores of a few plant species, and also from the second meiotic division, in which it is possible in numerous materials to study the behaviour of daughter univalents, and, in a few cases, also daughter chromosomes derived from chromosomes that were paired during the first division.The various cases of mitosis with single chromatids show a great variation with respect to the degree of scattering of the chromosomes over the spindle at metaphase. In a few cases there is practically no tendency to form a metaphase plate. In other cases the tendency to form such a plate is more or less pronounced, but also in these cases it is difficult for the chromosomes to form this arrangement. Some of them remain scattered over the spindle. After the metaphase a kind of anaphase usually follows in which the single chromatids, without division, move to the poles, often with other chromosomes lagging in intermediate positions.An approach of chromosomes to the poles may be caused by two different mechanisms in mitoses of this kind and only in a few cases is the information sufficient to show that active centromere movements occur during these anaphases.In many aspects of their behaviour on the spindle, single chromatids are similar to ordinary univalents of the first meiotic division. For this reason the movement mechanics of the chromosomes of the first meiotic division is briefly reviewed.The interpretation is expressed that the structure of the centromere region of a single chromatid shows some similarity to that of a univalent of the first meiotic division and that this may be the reason for their similar behaviour. The chromatid centromere would have a structural multiplicity with respect to its kinetic elements, corresponding to its subdivision in half-chromatids and also to the presence of two or three consecutive chromomeres in its longitudinal direction. As these kinetic elements are arranged close to one another on one side of the narrow cylinder of the centromere constriction, it is difficult for them to orient, towards both poles simultaneously. A single chromatid having a centromere of this kind will show orientation instability and change its orientation between the two unipolar orientations and various more or less bipolar orientations. The movements following these different orientations would cause the scattering of these single chromatids over the spindle. The orientation of ordinary mitotic metaphase chromosomes, consisting of two such chromatids, could often be the consequence of a process of co-orientation similar to that in meiotic bivalents.The anaphase movement of undivided chromosomes, which by active centromere movements are shifted in the polar directions without a separation of daughter components, is discussed with reference to a similar behaviour observed by Dietz in multivalents in Ostracods. These multivalents are stabilized in the equator during metaphase, in spite of the fact that they have two or three centromeres directed towards one pole and a single one towards the other. During anaphase their chromosomes do not separate but the whole configurations are shifted towards that pole towards which the majority of the centromeres are directed (this is followed by another type of movement which does not concern us in this connection). Undivided chromosomes that are oriented with more of their kinetic material towards one of the poles and less towards the other should by the same mechanisms as moved the multivalents be shifted in the equatorial direction during metaphase and in the polar direction during anaphase. The mechanism of these events is obscure. A change in the interpretation given by Dietz is suggested.This paper is dedicated to Professor Franz Schrader on the occasion of his seventieth birthday.     

Chromosome number and ploidy-level in a Dutch population ofCrenobia alpina Dana (Planaria)

A Dutch population ofCrenobia alpina was found to have a chromosome number of 2n=42. One pair of large chromosomes is acrocentric and probably shows a secondary constriction; one small pair is acrocentric as well. All other chromosomes are metacentric or sub-metacentric; it has not been possible to discriminate with certainty between them. According to the hypothesis ofDahm (1958) populations with, 2n=42 are autohexaploid, the basic genome consisting of seven chromosomes. On basis of the karyotype it was concluded that the Dutch population described here, is not autohexaploid but functionally diploid, perhaps allohexaploid.     

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.     

Chromosomal structure of populations of drosophila flavopilosa studied in larvae collected in their natural breeding sites

Summary D. flavopilosa Frey, is a neotropical species of Drosophila living in Chile that, together with 13 other species, has been included by Wheeler, Takada und Brncic (1962) in the flavopilosa species group. Despite the fact that it has not been possible to breed this species in the laboratory, the circumstance that its habitat is well known, has allowed the study of the chromosomal structure of some natural populations of this species, analyzing larvae directly taken to the laboratory from their natural breeding sites: the flowers of the solanacean Cestrum parqui L'Héritier.The present paper describes the mitetic and salivary gland chromosomes of D. flavopilosa, and gives a composite map of the Standard gene arrangement. In central Chile, natural populations of this species are polymorphic with respect to the gene orders in their chromosomes, due to the presence of four independent inversions, all located in one of the six chromosomes (the right arm of the V-chromosome). Quantitative data on the distribution of the inversions shows that there is an altitudinal gradient in the frequencies of two of the four inversions. Heterozygotes for Inversion A, are more frequent at high altitudes than at sea level. On the contrary, heterozygotes for inversion B, are abundant at sea level, but practically disappear at high altitudes. These altitudinal clines have been observed in two valleys near Santiago, Chile, which run from the Andes mountains to the Pacific coast.The work reported in this article has been carried out under Contract AT (30-1) 2465 US Atomic Energy Commission, and partially supported by Grants from the University of Chile, Faculty of Medicine and the Rockefeller Foundation under a joint program.     

Carnitine suppression of position-effect variegation in Drosophila melanogaster

Carnitine is a well-known naturally occurring compound, very similar to butyrate, with an essential role in intermediary metabolism mainly at the mitochondrial level. Since butyrate inhibits the enzyme histone deacetylase and is capable of suppressing position-effect variegation in Drosophila melanogaster, we tested a further possible function of carnitine in the nucleus, using an assay for the suppression of position-effect variegation. We tested three physiological forms of carnitine (l-carnitine, l-propionylcarnitine, l-acetylcarnitine) for the ability to suppress two different chromosomal rearrangements, inducing variegation of the white ⁺ and brown ⁺ genes. The results show that the carnitine derivatives are capable of suppressing the position-effect variegation, albeit with different efficiencies. The carnitine derivatives interact lethally with Su-var(2)1 ⁰¹, a mutation that induces hyperacetylation of histones, whilst hyperacetylated histories accumulated in both the nuclei of HeLa cells and Drosophila polytene chromosomes treated with the same compounds. These results strongly suggest that the carnitine derivatives suppress position-effect variegation by a mechanism similar to that of butyrate. It is suggested that carnitines may have a functional role in the nucleus, probably at the chromatin level.     

Diverse patterns of the tandem repeats organization in rye chromosomes

Although the monomer size, nucleotide sequence, abundance and species distribution of tandemly organized DNA families are well characterized, little is known about the internal structure of tandem arrays, including total arrays size and the pattern of monomers distribution. Using our rye specific probes, pSc200 and pSc250, we addressed these issues for telomere associated rye heterochromatin where these families are very abundant. Fluorescence in situ hybridization (FISH) on meiotic chromosomes revealed a specific mosaic arrangement of domains for each chromosome arm where either pSc200 or pSc250 predominates without any obvious tendency in order and size of domains. DNA of rye-wheat monosomic additions studied by pulse field gel electrophoresis produced a unique overall blot hybridization display for each of the rye chromosomes. The FISH signals on DNA fibres showed multiple monomer arrangement patterns of both repetitive families as well as of the Arabidopsis-type telomere repeat. The majority of the arrays consisted of the monomers of both families in different patterns separated by spacers. The primary structure of some spacer sequences revealed scrambled regions of similarity to various known repetitive elements. This level of complexity in the long-range organization of tandem arrays has not been previously reported for any plant species. The various patterns of internal structure of the tandem arrays are likely to have resulted from evolutionary interplay, array homogenization and the generation of heterogeneity mediated by double-strand breaks and associated repair mechanisms.     

Fermentation of seaweed sugars by Lactobacillus species and the potential of seaweed as a biomass feedstock

It is known that seaweeds differ greatly from land plants in their sugar composition. The current research on the L-lactic acid fermentation process focuses on land plant sugars as a carbon source, with the potential of seaweed sugars being largely ignored. This study examined the feasibility of seaweed biomass as a possible carbon source for the production of l-lactic acid, by comparing the fermentation of seaweed sugars (d-galactose, d-mannitol, l-rhamnose, d-glucuronic acid, and l-fucose) and land plant sugars (d-glucose, d-xylose, d-mannose, and l-arabinose). The experiments were repeated with 2 sugar acids (d-gluconic acid, d-glucaric acid) in order to investigate the effect of the degree of reduction of carbon source on the fermentation yield. This research also examined the effect of bacterial strain on the characteristics of fermentation reactions, by conducting l-lactic acid fermentation with 7 different Lactobacillus species. Taking into account the sugar composition of seaweed and the levels of lactic acid production from each pure sugar, it was possible to predict the lactic acid production yield of various seaweeds and land plants. From comparative analysis of the predicted lactic acid production yield, it was found that seaweeds are already comparable to lignocellulosics at the current stage of technology. If new technologies for the utilization of non-fermentable seaweed sugars are developed, seaweeds show promise as an even more useful biomass feedstock than lignocellulosics.     

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.     

Ultrastructure of globule leucocyte inclusions in the rat and mouse

Summary The fine structure of the globules in globule leucocytes of rat and mouse infected with various parasites has been studied. Best preservation was obtained with glutaraldehyde and subsequent osmium fixation. It is concluded that the structure of the globules is host specific. In rat, the structure is not parasite specific, but in mouse slight differences in the structure of the globules of the globule leucocyte in different experimental conditions suggest a small change in the packing of the sub-units.The authors are grateful to Professor G. M. Wyburn and Mr. R. N. C. Aitken for research facilities and advice. The work was partially financed by Agricultural Research Council Grant No. AG 17/49.     

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.     

Einfluß von Pockenimpfviren auf menschliche Chromosomen in vivo und in vitro

Zusammenfassung Menschliche Lymphocyten, die am 6., 9. und 12. Tag nach Pockenschutzimpfung kultiviert wurden, zeigten keine sicher verwertbaren Chromosomenanomalien. Nach Infektion menschlicher Lymphocytenkulturen hemmt Vaccinevirus die Mitosen und zerst?rt die Zellen in toto parallel zur Dauer der Einwirkung. Numerische und strukturelle Ver?nderungen an den Chromosomen wurden nicht beobachtet.

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The influence od vaccinia viruses on human chromosomes in vitro and in vitro

Summary Contradictory views are expressed in the literature on the question as to whether viruses induce anomalies in chromosomes. Vaccinia viruses in particular are generally stated to cause chromatid and chromosome breakage in L-cells (human embryonal lung tissue). The subject of the present paper is an experimental investigation of the effect of vaccinia viruses on the chromosomes of human blood lymphocytes. In the in vivo portion of this investigation the chromosomes were examined during and after viremia subsequent to vaccination. Only two of the eight vaccinated children examined showed a larger number of chromosome breaks during viremia than unvaccinated controls. This might possibly be due to different degrees of viremia, although local and general reactions were the same. Other causes might also be sought in vivo or in vitro, such as preparation of the chromosomes, or an unnoted mycoplasma infection of the lymphocyte cultures. In the in vitro portion of this investigation, cultures of human lymphocytes were infected with vaccinia viruses at different stages of incubation. In culture the virus concentrations exhibited a rapid initial decrease, which gradually tapered off during the period of observation. No increases in virus concentration were noted. The longer the period of infection with caccinia virus, the less growth shown by the lymphocytes, and the more mitotic cells with in toto destruction of the chromosome. Anomalies in individual chromosomes were not observed any more frequently than in controls.

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(Direktor: Prof. Prof. Dr. ?. Kerpel-Fronius)

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(Direktor: OMR Prof. Dr. med. habil. W. Plenert)

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(Direktor: Prof. Dr. G. Veres)     

De chromosomengetallen der organismen

Résumé The present paper gives an enumeration of the lists of the numbers of chromosomes in different organisms which have been published. It treats more in detail of the lists, referring to the Animal Kingdom, published by Mrs.Harvey and more especially of her conclusions in regard to the heterochromosomes. It is pointed out, in connection with a paper byNonidez on the X-complex inBlaps, that the occurrence of multiple or single X and Y chromosomes, expressed in non-committing language means that in forms possessing such X and Y's or such X and Y complexes we have to deal with the simultaneous presence of paired and unpaired chromosomes.It is pointed out that such an occurrence in plants has been shown to be due to hybridisation between forms possessing different chromosome-numbers.It is therefore suggested, that the presence of X and Y complexes or of single X and Y chromosomes is an indication of previous hybridization of forms differing in chromosome-numbers.The author is well aware, that this is as yet but a suggestion, and the present communication is published with no other object than to beg zoologists, to whom apparently this idea has not yet occurred, to look at the problem from this point of view and to test its applicability.It need hardly be pointed out, that if this suggestion should prove to be correct, it would give considerable support to the view that hybridisation has played on important role in evolution.The author wishes to lay stress on the point that the suggested origin of the X chromosome and its function are of course two very different questions.     

Biotechnological production of <Emphasis Type="SmallCaps">d</Emphasis>-glyceric acid and its application

Glycerol is currently produced in large amounts as a by-product during fat splitting and biodiesel fuel production. Over the past decade, both chemical and biotechnological processes to convert glycerol to value-added chemicals have been increasingly explored. This mini-review provides recent information about the biotechnological production of a glycerol derivative, d-glyceric acid (d-GA), and its possible applications. Little is known about GA as a bioproduct, but it is naturally found in different kinds of plants as a phytochemical constituent and is reported to have some biological activity. A racemic mixture of dl-GA can be obtained from glycerol via chemical oxidation; however, d-GA is mainly biotechnologically produced with the aid of bacteria. Under aerobic conditions, some acetic acid bacteria transform glycerol into d-GA, and optimization of initial glycerol concentration and aeration rate provided a yield of more than 80 g/l d-GA, using a strain of Gluconobacter frateurii.     

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.     

Synthesis and application of dipeptides; current status and perspectives

The functions and applications of l-α-dipeptides (dipeptides) have been poorly studied compared with proteins or amino acids. Only a few dipeptides, such as aspartame (l-aspartyl-l-phenylalanine methyl ester) and l-alanyl-l-glutamine (Ala-Gln), are commercially used. This can be attributed to the lack of an efficient process for dipeptide production though various chemical or chemoenzymatic method have been reported. Recently, however, novel methods have arisen for dipeptide synthesis including a nonribosomal peptide-synthetase-based method and an l-amino acid α-ligase-based method, both of which enable dipeptides to be produced through fermentative processes. Since it has been revealed that some dipeptides have unique physiological functions, the progress in production methods will undoubtedly accelerate the applications of dipeptides in many fields. In this review, the functions and applications of dipeptides, mainly in commercial use, and methods for dipeptide production including already proven processes as well as newly developed ones are summarized. As aspartame and Ala-Gln are produced using different industrial processes, the manufacturing processes of these two dipeptides are compared to clarify the characteristics of each procedure.     

Holocentric chromosome behaviour inCuscuta (Cuscutaceae)

The present study demonstrates thatCuscuta babylonica Choisy has holocentric chromosomes. Evidence for this phenomenon comes from three different observations. (1) Mitosis: During metaphase and anaphase the sister-chromatids are situated parallel to the equatorial plane with no sign of localized kinetochore activity. (2) Inverted meiosis in microsporocytes. (3) X-rayed microsporocytes, in which the numerous chromosome fragments do not show any lagging or formation of micronuclei. We assume that only one out of the three subgenera inCuscuta, namely subg.Cuscuta, has holocentric chromosomes, while the two other subgenera have monocentric chromosomes.     

Perspectives of biotechnological production of <Emphasis Type="SmallCaps">l</Emphasis>-ribose and its purification

l-Ribose is a non-natural and expensive sugar that can be used as an important intermediate for the synthesis of l-nucleoside analogues, which are used as antiviral drugs. In contrast to chemical production, biotechnological methods can produce l-ribose from biomass under environmentally friendly conditions. In this mini-review, various strategies for synthesizing l-ribose by applying microorganisms and their enzymes are discussed, including microbial biotransformation and biocatalysis by engineering bacteria. Furthermore, subsequent isolation-and-purification techniques, as an integral step in the whole process, are accordingly described, containing the especial introduction of a promising strategy of l-ribose separation. Particularly, further researches and outlook for the improvement of l-ribose preparation was solely stressed. Compared with each method, this mini-review provides a panorama of respective advantages and disadvantages existing in them.     

A comparative study of the chromosomes in the incipient species of the Drosophila paulistorum complex

Summary Drosophila paulistorum Dobzhansky et Pavan is a complex of six races or incipient species. The races are mostly allopatric, but they are reproductively isolated sufficiently to permit them to exist also sympatrically in some places. The gene arrangements in the chromosomes of the races have been compared by means of examination of the giant chromosomes in the larval salivary glands; 28 strains of all races, and about an equal number of interracial hybrids have been studied.Chromosomal inversion polymorphism has been discovered in all races, even in the Guianan race of which only a single strain is available. Inversion heterozygotes are found in every one of the five chromosomal strands which the species has. Interracial hybrids tend to be heterozygous for more inversions than are present in the strains of the parental races. The Transitional race has however much the same gene arrangements as the widespread Andean — South Brazilian race.With the exception of the Transitional race, and of three other possible exceptions, each race has a collection of its own race-specific inversion polymorphs, not found in the other races. This very striking finding is discussed in connection with the hypothesis which envisages the origin of new species from marginal colonies at the periphery of the geographic distribution area of the ancestral species.The work reported in this article has been carried under Contract No. AT-(30-1)-1151, U.S. Atomic Energy Commission, mostly at the Department of Zoology, Columbia University, New York.     

Chemical variation in two species of theLecanora subfusca group (Lecanoraceae,lichenizedAscomycotina)

The chemical variation inLecanora epibryon andL. subimmersa, two species of theL. subfusca group, has been examined. In both species the chemical differences are correlated with geographical distribution, but not with morphological differences. As a consequence the chemotypes are recognized at subspecific level. InL. epibryon three chemical races are segregated according to the various chemosyndromes present. Subspeciesepibryon, containing atranorin and triterpenoids, occurs in the northern hemisphere and South America, while the other two subspecies occur only in the southern hemisphere. The subsp.broccha (Nyl.)Lumbsch, comb. nova, contains atranorin, the stictic acid and the 2,5,7-trichloro-3-O-methylnorlichexanthone chemosyndromes, while subsp.xanthophora Lumbsch, subsp. nova, is similar but lacks the stictic acid chemosyndrome. Two chemical races occur in the pantropical speciesL. subimmersa. While subsp.subimmersa contains atranorin and zeorin, subsp.ramboldii Lumbsch & Elix, subsp. nova, contains an additional ten chlorinated xanthones.L. impressa is reduced to synonymy toL. subimmersa.