摘要:

The correct genome size inHedera helixL. has long been problematic, because several authors have reported nuclear DNA content plasticity in connection with phase change from juvenile to adult. Although this has been disproved, nevertheless uncertainty existed on the correct genomic DNA amount, due to one significantly higher flow-cytometric estimate in the more recent literature. The present analysis is concerned with this problem of a possibly variable genome size within the species or other reasons for this discrepancy. Plants of typicalH. helix (2n = 48),H. helixf.arborescens (2n = 48),H. canariensisWilld.(2n = 48) andH.colchica (2n = 192) were measured with flow cytometry (propidium iodide staining) and video based Feulgen densitometry for genome size. Internal standards used wereGlycine max(flow cytometry, 2C taken as 2.226 pg) and Pisum sativum (Feulgen densitometry, 2C taken as 8.84 pg). With flow cytometry, theH. helixvarieties andH. canar-iensiswere statistically invariant,1.263-fold of G.maxwith a 2C value of 2.81 pg. Hedera colchica was 4.895—fold of G. max with a 2C value of 10.90 pg in agreement with its higher poly-ploidy level. Feulgen estimates were slightly higher but basically in agreement with these data. Neither value is close to the deviating value for H.helixin the literature mentioned above, that must remain unsupported.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589175

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Mitosis and male meiosis were studied inMyrmedobia coleoptrata(Fn.), (Heteroptera,Microphysidae). Spermatogonial metaphase revealed 14 chromosomes(2n=12 + XY).The nucleolar organizing region was found on the X chromosome. No m-chromosomes were present in the complement. Male meiotic prophase was characterized by a prominent condensation stage. At this stage, the sex chromosomes were positively heteropycnotic and appeared as separate univalents, while in autosomal bivalents homologous chromosomes werealigned side by side along their entire length, i.e. meiosis is achiasmatic. Meiosis was prereductional for the autosomes and post-reductional for the X and Y chromosomes. Meiosis was further characterized by non-radial arrangement of chromosomes in metaphase I plate and radial arrangement in metaphase II. Cytological characteristics of achiasmatic meioses and their distribution within Heteroptera are discussed

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589176

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The behaviour and the morphology of the infection structures of the monokaryotic phase ofCronartium flaccidumestudied on needles ofPinus pineaseedlings inoculated with the rust basidiospore. It was found that the penetration and early colonization structures ofC. flaccidumin the monokaryotic phase maintained the morphological and functional significance of the typical monokaryotic ones, even if some aspects of their behaviour seemed to recall those of the dikaryon. A possible hypothesis as to the reason for the dynamics of penetration carried out on the markedly cutinized needles of pine byC. flaccidumin the monokaryotic phase is discussed. It can be concluded that inC. flaccidumin the monokaryotic phase it is the nuclear set which determines the morphology and function of the structures involved in the infection process; this is true even if the histological characteristics of the host organ which this rust species has evolved to infect in nature, condition its way of penetration.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589177

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The mitotic chromosomes, nucleolus organizer regions (NORs), C-banding patternand nuclear DNA content ofDiplomystes mesembrinuswere studied. The karyotype, with2n=56chromosomes (22m+24sm+6st+4a), has a high chromosome arm number (NF = 102),one chromosome pair with NORs, and a very small amount of heterochromatln. The NORbearing arm is entirely heterochromatic and exhibits a marked size polymorphism. The diploid DNA content detected in erythrocyte nuclei of D.mesembrinuswas 2.57 ± 0.15 pg/nucleus. The chromosome evolution in Siluriformes is discussed on the basis of available cytogenetic data and it is proposed that 2n=56 is synapomorphic for the order.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589178

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Cytogenetic studies involving conventional air drying techniques, Giemsa staining,constitutive heterochromatin analysis and silver staining were carried out onT. spegazzinifrom three hydrographic basins of the northwest of Argentina. In spite of colour and subtle morphological differencies the three populations showed the same karyologycal formulae, 54 biarmed chromosomes, 42 M and 12 SM pairs, NF = 108, with a very conspicuous first metacentric pair. The NORs were located at the terminal region on the short arm on a single submetacentric medium sized pair. The C banding analysis showed the presence of small blocks in pericentromeric position in an single metacentric large chromosome pair (3° o 4°). The species showed a conservative karyotype, with plesiomorphic condition for chromosome number and NOR bands.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589179

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Pollen tube microtubules (MTs) are as dynamic as animal MTs and they may interact with plasma membrane, endoplasmic reticulum, Golgi apparatus, mitocondria and a variety of cytoplasmic proteins. Bridges connecting MTs to each other and to membranes have been documented in pollen tubes by electron microscopy; however, the biochemical and molecular nature of these linkages is not known. In other cell types interaction between organelles and MTs require the participation of Microtubule-Associated Proteins (MAPs) that bridge the cytoskeleton to these organelles. Although biochemical documentation of such bridging MAPs in plant cells is lacking, it is reasonable to assume, by analogy with the animal systems, that specialized MAPs regulate MTs polymerization and dynamic in pollen tube. As a first step toward testing this hypothesis, the ability ofNicotiana tabacumpollen tube taxol-stabilized MTs to bind mammalian brain High Molecular Weight MAPs (HMWMAPs)(MAP2) was tested. This association analysis revealed the presence of mammalian MAP2-binding sites on pollen tube taxol-induced structures suggesting that the association presumably occurs at conserved domains on the tubulin molecules

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589180

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A chromosome analysis on nineVernoniaspecies (Vernonieae, Asteraceae) from South America was carried out. First chromosome counts are notified in four species:V. lilacinaMart. (2n=32= 24m + 6sm + 2st),V. oxyodontaMalme (2w=128),pulverulentaBaker (2n=96) andV. tarijensis(Griseb.) Hieron. (2n=32= 24m + 8sm). Furthermore, the somatic chromosome numbers ofV. chalybaeaMart, ex DC. (2n=32= 22m + l0sm),V.polyphyllaSch.Bip. (2n=64=: 40m + 20sm + 4st),V. squarrosaLess. (2n=64) andV. teyucuarensisCabrera (2n=160) are also confirmed. For V. aurea Mart, ex DC. is presented an unreported chromosome number (2n=32= 24m + 8sm). The karyotype analysis made on five species mainly showed metacentric and submetacentric chromosomes, differing in proportion between the species. InV. lilacinaandV. polyphyllawere also found one and two subtelocentric pairs respectively. The nine analyzed species presented x=16, a basic chromo some number very frequent in South America, specially in species from the subsect. Macrocephalae Baker. The chromosome number 2n=32 found inV. aurea, V. chalybaea, V. liladnaandV.tarijensissuggests that these species, included actually in other group, should be transferred to the subsection Macrocephalae

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589181

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A qualitative and quantitative analysis of flavonoids has been carried out for first time inVicia eristalioidesMaxt. and inVicia kalakhensisKhatt., Maxt. Bisby. Free aglycones were consistently absent from both species while kaempferol derivatives were pre dominant inV. kalakhensis;a more complex mixture of flavonoid glycosides,(kaempferoland quercetin glycosides) was present inV. eristalioides. Therer was no evidence of flavones glycosides.The flavonoid patterns ofV. kalakhensisandV. eristalioideswere compared with that ofV. narbonensiswhich is considered to be the ancestor of the Narbonensis complex. The results indicate that qualitative and quantitative flavonoid data may be used in the study of the organization and evolution of the Narbonensis complex.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589182

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Chironomid larvae were collected from different localities of industrial polluted area of Finland. By the cytogenetical and external larval morphological analysis the material studied could be referred to either asChironomus plumosusL. or asC. anthracinusZett. The effect of an industrial and a municipal contamination on the appearance of structural and functional alterations in the polytene chromosomes of both studied species was shown. Chromosome and genome polymorphism ofChironomus plumosusL. in different localities of industrial polluted areas of Lohjanjaveri, south Finland is described. A high chromosome polymorphism involving para-and pericentric inversions was established. A polymorphic system exists in all studied localities and it is characterised by the transition of one homozygous inversion into another through heterozygote formation. The studying areas were characterised by an increasing frequency of inverted homozygous inversions in arms A,C,D.The genome polymorphism is expressed by an additional " B" chromosome which varies in frequency and morphology. This polymorphism may provide the population with better chance to surviving under extreme polluted conditions. Structural-functional alterations inC. anthracinuswere observed. New para and pericentric inversions, were found in the studied polluted areas. Balbiani ring system (BR) ofC.plumosusand nucleolus (N) ofC. anthra cinuswere very sensitive to the pollution. Together with a normal activity of BR system ofC.plumosusand N ofC.anthracinuswe observed a clear reversed level: there were number of individuals and cells which BR and N were in heterozygous state or collapsed. Their potential for detecting genotoxic agents in ecosystems are discussed and some morphological deformities of both studied species were described. However, no correlation between the rate,> of chromosome rearrangements and rate of morphological deformities were established.

ISSN:0008-7114    

DOI:10.1080/00087114.2000.10589183

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor