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The sensitive detection of n-propanol, a typical marker molecule in respiratory gases for lung cancer, has attracted much attention from the consideration of health in modern society. However, the identification of n-propanol at the sub-ppm level with rapid responsive ability is a significant challenge but very critical for the early diagnosis of lung cancer. Herein, we demonstrate a unique chromosome-like HoFeO3 nanostructure material, prepared by annealing the self-sacrificial template of easily accessible HoFe-(CN)6, for high-performance n-propanol sensing. In detecting n-propanol, the HoFeO3 material-based sensor exhibits a response of 120.5 to 100 ppm of n-propanol at an operating temperature of 120 °C. Most importantly, it shows a low detection limit of 50 ppb and a good linear relationship between response and concentration. This sensor also possesses a rapid responsive ability with a response time of 4 s. The remarkable sensing performance, greatly outperforming other conventional semiconductor-based chemiresistive gas sensors, can be mainly attributed to the mesoporous structure, various surface element states, and narrow-band traits. The homemade experiment system further validates the practical potential of HoFeO3 microchromosome-based gas sensors for early-stage lung cancer diagnosis. [ABSTRACT FROM AUTHOR]

The perennial Secale cereanum cultivar 'Kriszta' is an artificial hybrid of S. cereale and S. strictum ssp. anatolicum. From the cross between the wheat line Mv9kr1 and 'Kriszta', which aimed the transfer of beneficial traits from rye to wheat, numerous translocation lines have been produced. For the identification of the translocated chromosomes, the unambiguous differentiation between chromosome arms of 'Kriszta' is essential. The identification of its short chromosome arms using conventional FISH probes is easy, but because of their similar hybridization patterns, its long arms cannot be distinguished. The present study aimed to create the detailed karyotype of 'Kriszta', especially that of long arms, by both chromosome measurements and FISH using highly repetitive, as well as subtelomeric tandem repeat, and synthetic microsatellite DNA sequences. Our results indicate that the chromosome complement of 'Kriszta' is not a simple combination of the chromosomes of the parental rye species but is composed of rearranged chromosomes. It is also showed that an adequate pair-wise combination of the DNA sequences pSc119.2, pSc200, pSc250, and (AAC)5 makes it possible to identify any of the long arms of S. cereanum cv. Kriszta chromosomes. The future usability of the identified wheat- 'Kriszta' translocated chromosomes is also discussed. [ABSTRACT FROM AUTHOR]

Lantana species are an important component of the U.S. environmental horticulture industry. The most commonly produced and used species are L. camara and, on a smaller scale, L. montevidensis. Both were introduced to the United States from Central and/or South America. Lantana species native to the continental United States include L. canescens, L. depressa, L. involucrata, etc. and most of them have not been well exploited. This study was conducted to obtain information about somatic chromosome numbers, karyotypes, and genome size of these five species. Nuclear DNA content in these species ranged from 2.74 pg/2C (L. involucrata) to 6.29 pg/2C (L. depressa var. depressa). Four chromosome numbers were observed: 2n = 2x = 22 in L. camara ‘Lola’ and ‘Denholm White’, 2n = 4x = 44 in L. depressa var. depressa, 2n = 2x = 24 in L. canescens and L. involucrata, and 2n = 3x = 36 in L. montevidensis. Two basic chromosome numbers were observed: x = 11 in L. camara and L. depressa var. depressa, and x = 12 in L. canescens, L. involucrata, and L. montevidensis. Analysis of somatic metaphases resulted in formulas of 20m + 2sm for L. camara ‘Lola’ and ‘Denholm White’, 12m + 12sm for L. canescens, 44m for L. depressa var. depressa, 10m + 14sm for L. involucrata, and 32m + 4sm for L. montevidensis. Satellites were identified in all five species, but were associated with a different chromosome group in different species. L. depressa var. depressa had the longest total chromatin length (146.78 µm) with a range of 1.88 to 4.41 µm for individual chromosomes. The maximum arm ratio was observed in L. canescens, with a ratio of 2.5 in chromosome group 3. L. depressa var. depressa was the only species that had all of its centromeres located in the median region of the chromosome. The results show significant differences in nuclear DNA content, chromosome number, and karyotype among three native and two introduced lantana species and will help to identify, preserve, protect, and use native lantana species. The information will be helpful in assessing the ploidy levels in the genus by flow cytometry.

Lantana species are an important component of the U.S. environmental horticulture industry. The most commonly produced and used species are L. camara and, on a smaller scale, L. montevidensis. Both were introduced to the United States from Central and/or South America. Lantana species native to the continental United States include L. canescens, L. depressa, L. involucrata, etc. and most of them have not been well exploited. This study was conducted to obtain information about somatic chromosome numbers, karyotypes, and genome size of these five species. Nuclear DNA content in these species ranged from 2.74 pg/2C (L. involucrata) to 6.29 pg/2C (L. depressa var. depressa). Four chromosome numbers were observed: 2n = 2x = 22 in L. camara 'Lola' and 'Denholm White', 2n = 4x = 44 in L. depressa var. depressa, 2n = 2x = 24 in L. canescens and L. involucrata, and 2n = 3x = 36 in L. montevidensis. Two basic chromosome numbers were observed: x = 11 in L. camara and L. depressa var. depressa, and x = 12 in L. canescens, L. involucrata, and L. montevidensis. Analysis of somatic metaphases resulted in formulas of 20m + 2sm for L. camara 'Lola' and 'Denholm White', 12m + 12sm for L. canescens, 44m for L. depressa var. depressa, 10m + 14sm for L. involucrata, and 32m + 4sm for L. montevidensis. Satellites were identified in all five species, but were associated with a different chromosome group in different species. L. depressa var. depressa had the longest total chromatin length (146.78 mm) with a range of 1.88 to 4.41 mm for individual chromosomes. The maximum arm ratio was observed in L. canescens, with a ratio of 2.5 in chromosome group 3. L. depressa var. depressa was the only species that had all of its centromeres located in the median region of the chromosome. The results show significant differences in nuclear DNA content, chromosome number, and karyotype among three native and two introduced lantana species and will help to identify, preserve, protect, and use native lantana species. The information will be helpful in assessing the ploidy levels in the genus by flow cytometry. [ABSTRACT FROM AUTHOR]

In this study, karyotype analysis of the species of Onobrychis sp. was undertaken using the squash method. The results showed that the chromosome number of Onobrychis tournefortii (Willd.) Desv., O. gracilis Besser, O. hypargyrea Boiss. is 2n = 14 and O. argyrea Boiss. subsp. argyrea Boiss., 2n = 16. The karyotype formula of O. tournefortii (Willd.) Desv. is 4m+3sm, of O. hypargyrea Boiss. and O. gracilis Besser 3m+4sm, and of O. argyrea Boiss. subsp. argyrea Boiss. 2m+ 5sm+1 st.

Twenty four Anatolian Black cows with primary ketosis (PK) and 10 clinically healthy cows (considered as control) were used in the study. The clinical, haematological, serum biochemical and cytogenetical parameters of all the animals were measured. Primary clinical signs included diminished appetite, decreased milk production, loss of weight, firm faeces and depression. Although no significant differences were seen with regard to haematological findings between PK and the control groups, significance increases (P

Theridiidae is a derived family within the Araneoidea clade. In contrast to closely related groups, the 2n(male) = 20+X1X2 with acro/telocentric chromosomes is the most widespread karyotype among the theridiid spiders. In this work, the cytogenetic analysis of Argyrodes elevatus revealed original chromosome features different from those previously registered for Theridiidae, including the presence of 2n(male) = 20+X with meta/submetacentric chromosomes. Most individuals of Nesticodes rufipes showed family conserved karyotype characteristics. However, one individual had a 2n(male) = 24 due to the presence of an extra chromosome pair, which exhibited regular behavior and reductional segregation during meiosis. After silver staining, mitotic cells exhibited NORs localized on the terminal regions of the short arms of pairs 2, 3, and 4 of A. elevatus and on the terminal regions of long arms of pair 4 of N. rufipes. The comparative analysis with data from phylogenetically related species allowed the clarification of the origin of the interspecific and intraspecific chromosome variability observed in Argyrodes and in N. rufipes, respectively.

Interesting small mammal diversity is currently being uncovered in Nigeria, much of it through molecular analyses. The cytogenetic aspects of this diversity, however, remain largely unknown. In this study, diploid number and chromosome morphology viewed on Giemsa-stained slides for seven small mammal species trapped in Southwestern Nigeria are reported. The specimens were also sequenced for cytochrome b to assist in making accurate taxonomic designations. To our knowledge, chromosomal information is presented for four of these small mammal species for the first time from populations within Southwestern Nigeria. The respective diploid numbers detected in this study for Lophuromys sikapusi and Dasymys sp. differ from diploid numbers published for these species in previous studies. Cytochrome b sequencing helped us to correctly identify Mastomys erythroleucus (2n = 38), where specimens with this same chromosome number in our study area were erroneously assigned to other Mastomys species. Cytogenetic data combined with other lines of scientific evidence will help us appreciate and understand more the bountiful diversity of small mammals across Nigeria. [ABSTRACT FROM AUTHOR]

Thirteen wild species of Passiflora were analyzed using conventional and CMA/DA/DAPI staining to evaluate the karyotype diversity between and within the subgenus Decaloba and Passiflora. The karyotypic features indicate that both subgenera have a conserved chromosome number, as reported before for several species. Submetacentric ( sm ) chromosomes were found in species from both subgenera, suggesting that sm chromosomes are not restricted to a particular subgenus. The analysis of the karyotypic heterogeneity enabled to distribute the species in three groups, but with no support to phylogenetic and taxonomic levels. The application of fluorochromes allowed for the visualization of CMA + /DAPI − blocks, which in our studies always correlated with the occurrence of satellites, showing that occurrence of two chromosome pairs with satellites per cell is a characteristic shared by some species from both subgenera. This feature does not always have relationship with the basic chromosome number. The data found in this study will help to understand the phylogeny, cytotaxonomy, and evolution of the genus Passiflora showing that karyotypic variation can be seen between and within the subgenus Decaloba and Passiflora . [ABSTRACT FROM AUTHOR]

Aneuploids provide valuable tools for locating genes on specific chromosomes and for studying dosage effect of additional/missing chromosomes. Presently, a double hypoploid with 2n = 4x = 30 chromosomes was found for the first time among the seed progeny of a tetraploid plant growing in Jammu University Botanical Garden. These chromosomes on the basis of form/size formed six quadruples and two triplets, with six groups having single deviant chromosomes. Occurrence of single deviant members in most of the groups pointed towards the segmental allotetraploid nature of present strain. Like the normal tetraploids, most of the pollen mother cells (PMCs) of this variant had somatic number of chromosomes (2n = 30) present as univalents or multivalents and bivalents, a few cells had double the somatic number of chromosomes (2n = 60) which were always present as bivalents. Meiotic details in the PMCs with 30 chromosomes revealed that 15.21 % cells had 30 univalents, 10.86 % cells had 6IV + 2III and in 54.32 % cells had configurations as 6IV + 2II + 2I, 4IV + 3III + 2II + 1I, 3IV + 2III + 5II + 2I, 2IV + 2III + 8II. Presence of a few cells with 6IV + 2III and most of cells with lesser number of quadrivalents but more bi- and univalents as well as the fact that 30 chromosomes matched into six quadruples and two triplets with most of the groups having single deviant members indicates that the present variant represents segmental allotetraploid. At the same time, occurrence of few cells with penta-/hexavalents indicates the involvement of structural chromosomal alterations in the evolution of present cytotype. In order to identify the missing chromosomes, present karyotype has been compared with that of its tetraploid parent. This comparison indicated that the missing chromosomes of the former belong to groups VII and VIII. For having some clues regarding the origin of present strain, reduction division in the two tracks of its progenitor was also studied. In the female track, majority of embryo-sac mother cells (EMCs) of the parent plant had 64 chromosomes which were present as 32 bivalents at metaphase I, with clean 32:32 segregations at anaphase I whereas a few EMCs available with 32 chromosomes had multivalents and unequal segregations in half of the cells with this number at anaphase I. In the male track, majority of the PMCs with 32 chromosomes had either multivalents or univalents at metaphase I and unequal dis junctional patterns in 32 % of the cells. As EMCs with 32:32 segregations are expected to develop into embryo-sacs with eggs having 32 chromosomes and PMCs and EMCs with 32 chromosomes and unequal separation of chromosomes are more likely to form genetically imbalanced gametes, it seems that the present variant has originated by the formation and the fusion of aneuploid reduced gametes. [ABSTRACT FROM AUTHOR]

The Bromeliaceae family has been traditionally distributed in the subfamilies Bromelioideae, Tillandsioideae and Pitcairnioideae. However, phylogenetic studies have provided other classifications, highlighting the need for analyses in order to characterize the genome of different species from this family. In this sense, the present work aimed to determine nuclear 2C-value and base composition, characterize the chromosomes and establish the karyogram of Pitcairnia flammea. Flow cytometry yielded 2C = 1.44 pg, AT = 64.28 % and GC = 35.72 % for this species, indicating its relatively small genome size. Despite reduced length and morphological similarity of the chromosomes, P. flammea metaphases presented well-spread chromosomes, with well-defined primary constriction, without chromatin damage and cytoplasmic background. These aspects allowed morphometric chromosomal characterization and assembly of the first karyogram of a Bromeliaceae species. The karyogram displayed 2 n = 50 chromosomes, of which all were submetacentric. Karyomorphological analysis revealed grouped pairs of cytogenetically identical chromosomes (2-3, 4-5, 6-9, 10-17, 18-19, 20-23 and 24-25), plus one isolated chromosome (1), not identical to any other. This result suggests an allopolyploid origin for the P. flammea genome. Thus, the present investigation contributed with karyotype data for taxonomic and evolutionary aspects of this group. [ABSTRACT FROM AUTHOR]

Naturally occurring/spontaneously produced polyploids with six/more genomes are rarely found in Alliums. A hexaploid form of Allium tuberosum with 2n = 48 chromosomes has been isolated for the first time amongst the open-pollinated seedlings of a hypotetraploid plant (2n = 4x = 31); latter being the seed-derived product of a normal tetraploid stock (2n = 4x = 32) growing in Jammu University Botanical Garden. Except for the guard cells and pollen grains that are of increased size, this form compared to its progenitor is dwarf, has smaller leaves and bears inflorescences with few flowers. This plant is also different from its progenitor in having nearly one-fourth (27.8 %) of its pollen mother cells (PMCs) with varying chromosome number viz. 27-64, with the remaining cells having somatic or double the somatic number of chromosomes. To assess the nature of hexaploid form, its chromosomes were studied for morphological details, putative grouping and pairing properties during reduction division. Morphological similarity in the chromosomes of the present cytotype and its progenitor, arrangement of 48 chromosomes in eight groups of six chromosomes each and presence of 21.88 % euploid cells with eight hexavalents pointed towards the autopolyploid nature of the present strain. Regarding the origin of this strain, observation made on the meiosis in the two sex mother cells of the progenitor provides some clues. In the later plant, presence of most of embryo-sac mother cells with 62 chromosomes that showed 31:31 segregations and existence of majority of the PMCs with 31 chromosomes exhibiting erratic segregations indicate that the hexaploid strain has probably originated as a result of the fusion of reduced male (n = 17) and unreduced female gamete (2n = 31). [ABSTRACT FROM AUTHOR]

Eight taxa of the genus Bellevalia (Hyacinthaceae) occurring in Greece, all with basic chromosome number x = 4, were cytologically studied using classical and molecular-cytogenetic techniques [fluorochrome banding with chromomycin A, fluorescence in situ hybridization (FISH) using probes of 18S-5.8S-26S and 5S ribosomal RNA genes]. Two of the examined taxa are endemic, i.e., B. brevipedicellata and B. sitiaca, both restricted to the Island of Kriti. B. hyacinthoides and B. edirnensis are Balkan endemics, and the four remaining taxa, i.e., B. dubia subsp. boissieri, B. trifoliata, B. romana, and B. ciliata, are more widely distributed Mediterranean elements. Genome size, estimated by flow cytometry, ranged from 18.59 to 53.38 pg. The results of fluorochrome banding and FISH are reported for the first time for the genus Bellevalia. Despite the morphological similarity of the chromosome complement, which is in accordance with the general 'basic' Bellevalia karyotype formula, the karyotypes of the studied species are clearly distinguished by the number and position of GC-rich bands and ribosomal DNA (rDNA) loci, revealing clear interspecific differentiation among the taxa. Additionally, examination of the polyploid species B. sitiaca and B. edirnensis and populations of B. hyacinthoides and B. ciliata with different ploidy levels permits discussion about the origin of polyploids and the taxonomic relationships among the taxa. [ABSTRACT FROM AUTHOR]

Determining the base number, ploidy level and type of ploidy are important aspects in the cytogenetic study of a species. To assess the nature of Allium hookeri Thwaites (2n=22), chromosomes of its two populations from North-eastern Himalayas were worked out for morphological details, putative grouping and pairing properties during reduction division. Karyotype was found to split into 7 pairs and 8 single chromosomes; 7 pairs revealed minor differences in overall chromosome morphology. Critical analysis of chromosome behaviour during reduction division at diakinesis and metaphase I revealed the presence of trivalents in 60.5 and 58.5% pollen mother cells respectively. High frequency of cells with trivalents pointed towards considerable homology in three genomes. Though remaining cells had multivalents higher than trivalents, similarity in three genomes was there. High frequency of cells with trivalents and the fact that 22 chromosomes can be arranged in seven twos and eight ones indicated that these represent numerical variants of segmental allotriploids. Besides, occurrence of 29.8 and 17.6% chromosomes as multivalents higher than trivalents at diakinesis and metaphase I supported that multiple interchanges accompanied the polyploidy in the evolution of present cytotypes. Pairing anomalies noticed during meiosis result in very low pollen stainability (0.05%) leading to sterility. Propagation by bulbs ensures the survival and maintenance of such a complex heterozygosity in the species. [ABSTRACT FROM AUTHOR]

The article explores the role of small ubiquitin-like modifier (SUMO) in synaptonemal complex (SC) formation in meiosis. In the process of meiosis, the ladder-like SC is an important player especially in several chromosome interactions. The authors' discovery of the role of SUMO in the formation of SC revealed the protein-protein interaction in creating SC. They conclude that with this discovery SC can be a differential regulatory of structure and function of chromosomes.

The detailed karyotypes of diploid (2n = 2x = 24) and triploid (2n = 3x = 36) of L. tigrinum were constructed based on fluorescence in situ hybridization (FISH) using 5S rDNA and 45S rDNA probes. The lengths of mitotic metaphase chromosomes ranged from 15.92 to 30.18 um, with a total length/genome of 250.46 um in diploid, and 15.24 to 28.16 um, with a total length/genome of 233.42 um in triploid. The chromosome composed of two pairs of metacentrics (Chromosomes 1 and 2), four pairs of subtelocentrics (Chromosomes 3, 4, 5, and 6) and six pairs of telocentrics (Chromosomes 7, 8, 9, 10, 11, and 12) in diploid L. tigrinum, two pairs of metacentrics (Chromosomes 1 and 2), six pairs of subtelocentrics (Chromosomes 3, 4, 5, 6, 7, and 11) and four pairs of telocentrics (Chromosomes 8, 9, 10, and 12) in triploid L. tigrinum. Ten (Chromosomes 1, 2, 6, 7, and 11) or twelve (Chromosomes 1, 2, 4, 6, 7, and 11) loci of 45S rDNA were detected in the diploid chromosomes whereas fifteen loci were detected in triploid chromosomes (Chromosomes 1, 2, 6, 7, and 11). Two loci of 5S rDNAs were located close to each other at the both diploid and triploid chromosome 3. New cytotypes of secondary constriction were observed in diploid (1-1-1-0) and triploid (3-2-1-1). [ABSTRACT FROM AUTHOR]

The development of perennial wheat cultivars in the Pacific Northwest (PNW) region of the U.S. addresses the need for alternative cropping systems that reduce soil erosion and degradation from mechanical tillage. Selection of parental lines will be especially important for breeding perennial wheat. Here we describe the karyotypes of three cultivars of bluebunch wheatgrass, Pseudoroegnaria spicata [Pursh] A. Love, and one cultivar of Snake River wheatgrass, Elymus wawawaiensis. These four cultivars are wild relatives of wheat that are adapted to the low rainfall regions of the PNW and can be crossed with bread wheat (Triticum aestivuin L.) using traditional breeding methods. Chromosome number, arm ratio, relative length and centromere index are given for Ps. spicata cultivars 'Whitmar' (ssp. inermis), 'Goldar' (ssp. spicata), and 'Anatone' (ssp. spicata), and the E. wawawaiensis cultivar 'Secar'. [ABSTRACT FROM AUTHOR]

Chromosome morphology was studied in diploid cultivars of Tulipa fosteriana and T. gesneriana (2n = 2x = 24) and triploid Darwin hybrids (2n = 3x = 36) developed from interspecific crosses of T. gesneriana and T. fosteriana. Chromosomes were arranged in the karyotype according to decreasing total length. Based on our karyotypic analysis, we propose that median chromosomes may serve as markers for diploid genotypes. Discriminant analysis with respect to total chromosome length and short arm length showed a significant difference between the size of the larger median chromosomes of T. gesneriana and T. fosteriana Comparison of median chromosome length in Darwin hybrid tulips showed that two larger chromosomes and one smaller chromosome were derived from T. gesneriana and T. fosteriana, respectively. This finding was clearly and unambiguously confirmed by simultaneous hybridization of differentially labeled genomic probes of T. fosteriana and T. gesneriana to metaphase chromosomes of the triploid cultivar ‘Yellow Dover’, thereby enabling us to distinguish between the 24 chromosomes derived from T. gesneriana and 12 chromosomes derived from T. fosteriana. Thus, genomic in situ hybridization and median chromosome analyses can be useful to identify the genome constitution of triploid Darwin hybrid tulips. In addition, their hybridity was readily verified by flow cytometry using vegetative tissue of Darwin hybrid tulips. Our results clarify the process of Tulipa cultivar formation and will be useful for interspecific hybridization breeding. [ABSTRACT FROM AUTHOR]

Chromosome numbers and karyotypes of Sonchus oleraceus (n=16, 2n=32), S. asper (n=9, 2n=18 for subsp. asper and subsp. glaucescens, and S. microcephalus (n=15, 2n=30) are studied; for the first time their idiograms are given. Karyotypes mainly comprise small chromosomes with a degree of asymmetry 2B in S. oleraceus and S. microcephalus and 2A or 2A--2B in S. asper. No karyological differences can be pointed out between S. asper subspecies. Data presented support the amphiploid character of S. oleraceus, and the origin of S. microcephalus through a dysploid process involving the former taxon. In Iberian representatives of the genus, diagrams of karyotype asymmetry indices show a cluster grouping for species, with the detached exceptions of S. maritimus and S. crassifolius, which spontaneously hybridize in central Spain. A review of available karyological data shows that in the evolution of the genus Sonchus s.l. and relatives, the basic chromosome number x=9 has generally been maintained. Dysploidy is restricted to the series S. bourgeaui (n=8) -- S. tenerrimus (n=7) and S. oleraceus (n=16) -- S. microcephalus (n=15), evolutionarily related and included in the present subgenus Sonchus. Polyploidy has been detected in a total of nine taxa of Sonchus and in the genera Embergeria, Kirkianella, and Dendroseris, being more common in peripheral regions of the distribution area of the group. Five diversification centers are proposed for the whole group, of which the Western Mediterranean area, including the Iberian Peninsula, is related to diversification of the present subgenus Sonchus. [ABSTRACT FROM AUTHOR]

The effect of the cytomegalovirus on the cell cycle was studied autoradiographically in an asynchronous culture of human diploid fibroblasts. The analysis of labeled mitosis showed that some cells infected in the S phase ceased to progress through the cell cycle at one of its phases (S, G2, or M); at the same time, at least part of the infected cells remained capable of entering mitosis. Beginning from day 2 after infection by cytomegalovirus, the accumulation of pathological mitotic cells blocked at metaphase was observed in the culture. Approximately 50% of these cells contained 3H-thymidine label above chromosomes. This suggested the possibility of pathological mitosis in cells that were infected both at the S and other phases of the cell cycle. The detailed morphological analysis of chromosomes at different stages of infection demonstrated that the degree of their morphological changes increases from slight (stronger condensation) to severe pathology (fragmentation). In the aggregate, the results of the study suggested that abnormal chromosome morphology resulted from irreversible cell division arrest under the effect of the cytomegalovirus. [ABSTRACT FROM AUTHOR]

A preparation technique has been developed for plants with small chromosomes, which produces large numbers of good-quality mitotic preparations. The technique employs a hydrochloric acid treatment to hydrolyse the cytoplasm, facilitating the subsequent removal of cytoplasmic debris. The evaporative force of a methanol-based fixative is exploited to disperse the cytoplasm and to deposit the chromosomes in a single optical plane. This technique permits detailed observations of chromosome morphology and karyotyping. The mitotic preparations are also suitable for the complex analysis associated with in-situ hybridization, as in studies of genome interaction in plant hybrids. [ABSTRACT FROM AUTHOR]

A cytological survey of Leucanthemum species in North Africa has shown that they are all diploid with a somatic chromosome number of 2n = 18. New counts are reported for 8 species and 1 subspecies. 11 taxa were used in a crossing programme and the results show a good agreement between phenetic distance based on morphological characters and genetic differentiation as expressed in the ability of the species to hybridize. A strong barrier to gene exchange exists between European and North African species. Bagging experiments showed that the North African species comprise a self-incompatible group of cytogenetically related species. [ABSTRACT FROM AUTHOR]