The Cytology of Brachyscome Cass. (Asteraceae: Astereae). II. Hybridisation Between B. goniocarpa (N = 4) and B. dichromosomatica (N = 2)

1991 ◽  
Vol 39 (5) ◽  
pp. 475 ◽  
Author(s):  
K Watanabe ◽  
PS Short ◽  
K Kosuge ◽  
S Smith-White
Keyword(s):  
Parental Species ◽  
The Other ◽  
Meiotic Pairing ◽  
Mitotic Metaphase ◽  
Metaphase Chromosomes ◽  
Total Length

Artificial hybrids between the inbreeding species B. goniocarpa Sond. & F. Muell.(n = 4) and outbreeding B. dichromosomatica C. R. Carter var. dichromosomatica (n = 2) have been produced. Morphologically, the hybrids were essentially intermediate between the parental species. Cytological investigations showed that the total length of mitotic metaphase chromosomes for the B. dichromosomatica haploid set was 1.33 times that of the B. goniocarpa set. Chromosomes derived from the parental species showed similar condensation behaviour. Meiotic pairing involved both the B. dichromosomatica chromosomes and two of the four B. goniocarpa chromosomes; the other two B. goniocarpa chromosomes formed univalents. The results suggest that the current placement of the two taxa in different superspecies is not warranted.

Metaphase karyotype identity in four homosequential Drosophila species from Hawaii

1985 ◽  
Vol 27 (3) ◽  
pp. 308-311 ◽  
Author(s):  
Linda S. Chang ◽  
Hampton L. Carson
Keyword(s):  
Polytene Chromosome ◽  
Chromosomal Rearrangements ◽  
The Other ◽  
Drosophila Species ◽  
Mitotic Metaphase ◽  
Metaphase Chromosomes ◽  
Hawaiian Drosophila ◽  
Gross Chromosomal Rearrangements ◽  
Rule Out

Four recently evolved species of Hawaiian Drosophila (silvestris, heteroneura, dijferens, and planitibia) have previously been shown to be homosequential in all five polytene chromosome arms. This suggests that the changes involved in speciation are at the genic level and hence are not evident in the polytene banding sequences. Because this does not rule out the occurrence of heterochromatic differences between these homosequential species, the present study was carried out to examine this possibility. These species are now shown to have identical heterochromatin distributions in mitotic metaphase chromosomes. This proves that neither gross chromosomal rearrangements nor novel heterochromatic blocks have been involved in the divergence of these four species. A fifth, and evolutionarily more distant, species (hemipeza) belonging to the same subgroup has a significantly different heterochromatin distribution from the other four species.Key words: heterochromatin, metaphase karyotypes, Hawaiian Drosophila.

Cytogenetics of two interspecific synthetic hybrids of the grasshopper genus Euchorthippus

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 909-912 ◽  
Author(s):  
J. L. Santos ◽  
P. Arana ◽  
N. Henriques-Gil
Keyword(s):  
Parental Species ◽  
The Other ◽  
Meiotic Pairing ◽  
Banding Patterns ◽  
Hybrid Individual ◽  
C Banding ◽  
Isolating Mechanisms ◽  
Synthetic Hybrids ◽  
The Cross ◽  
Homoeologous Chromosomes

The spermatogenesis of two synthetic hybrid individuals of the grasshopper genus Euchorthippus was studied by C-banding methods. One resulted from the cross Euchorthippus pulvinatus ♂ × Euchorthippus chopardi ♀ (p/c), whereas the other one was produced in the cross E. chopardi ♂ × E. pulvinatus ♀ (c/p). The two parental sets of chromosomes were always recognized according to their different C-banding patterns. Chiasma frequency was decreased in both hybrids when compared with the parental species, this decrease being more accentuated in the hybrid individual c/p, where univalents at metaphase I were frequent. Chiasmata were formed between homoeologous chromosomes, and only two multivalent associations were observed. Polyploid spermatids and some micronuclei were a common feature in both hybrids. It is suggested that C-heterochromatin differences do not play any important role in the speciation process: genie differences between parental genomes are probably more important.Key words: synthetic hybrid, Euchorthippus, C-heterochromatin, meiotic pairing, reproductive isolating mechanisms.

Intergeneric hybrids between Thinopyrum and Psathyrostachys (Triticeae)

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 845-849 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Genome Analysis ◽  
Parental Species ◽  
Intergeneric Hybrids ◽  
Meiotic Pairing ◽  
Green Leaves ◽  
Psathyrostachys Juncea ◽  
Basic Genome ◽  
Chromosome Associations ◽  
Thinopyrum Elongatum ◽  
First Time

Intergeneric hybrids were synthesized for the first time from the diploid crosses Thinopyrum elongatum (JeJe) × Psathyrostachys juncea (NjNj), T. elongatum × P. fragilis (NfNf), T. bessarabicum (JbJb) × P. huashanica (NhNh), and T. bessarabicum × P. juncea, as well as from a cross between the amphidiploid of T. bessarabicum × T. elongatum (JbJbJeJe) and P. juncea. Spikes of these hybrids are morphologically intermediate between those of the parental species. Double spikelets occurred occasionally at central nodes of the spikes. Glaucous blue leaves appeared in the F1 only in the cross T. bessarabicum × P. huashanica, suggesting that the gene(s) for glaucous blue leaves in T. bessarabicum is (are) recessive to a gene(s) for green leaves in P. juncea but is (are) dominant to that for yellowish green leaves in P. huashanica. Meiotic pairing at metaphase I in these diploid (JN) and triploid (JJN) hybrids revealed a very low level of homology between the basic J and N genome. Therefore, the J and N genomes are nonhomologous and justifiably represented by different genome symbols. The triploid hybrids exhibited a pattern of chromosome associations that substantiated the earlier conclusion that the genomes in T. bessarabicum and T. elongatum are two versions of a basic genome (J). These hybrids will be useful in genome analysis, forming new Leymus species with the J and N genomes and broadening the diversity in the genus Pascopyrum with the SHJN genomes.Key words: hybrid, Thinopyrum, Psathyrostachys, genome.

scholarly journals The influence of removal of the large intestine and increasing quantities of fat in the diet on general metabolism in dogs

1899 ◽  
Vol 64 (402-411) ◽  
pp. 77-88 ◽  
Keyword(s):  
Large Intestine ◽  
The Other ◽  
Total Length ◽  
General Metabolism ◽  
Minced Meat

In this research it was intended, by comparing the results obtained in dogs on a given diet with the same animals after the removal of the large intestine, to study more carefully the functions and any influence the absence of the large intestine might have on general metabolism. In one dog a little more than the middle third of the large intestine was removed, while in the other two dogs the total length of the large intestine, together with the cæcum, was extirpated. The dogs were fed after recovering from the operation on meat and biscuit, to which varying quantities of fat were added. The meat employed was preserved by sterilising minced meat in separate weighed out portions sufficient for each day.

scholarly journals Ecological Observations on Hybrid Populations of European Plethodontid Salamanders, Genus Speleomantes

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 285
Author(s):  
Enrico Lunghi ◽  
Fabio Cianferoni ◽  
Stefano Merilli ◽  
Yahui Zhao ◽  
Raoul Manenti ◽  
...  
Keyword(s):  
Body Condition ◽  
Parental Species ◽  
Stomach Contents ◽  
Trophic Niche ◽  
Natural Hybrid ◽  
Ecological Information ◽  
Total Length ◽  
Plethodontid Salamanders ◽  
The Future ◽  
First Time

Speleomantes are the only plethodontid salamanders present in Europe. Multiple studies have been performed to investigate the trophic niche of the eight Speleomantes species, but none of these studies included hybrid populations. For the first time, we studied the trophic niche of five Speleomantes hybrid populations. Each population was surveyed twice in 2020, and stomach flushing was performed on each captured salamander; stomach flushing is a harmless technique that allows stomach contents to be inspected. We also assessed the potential divergence in size and body condition between natural and introduced hybrids, and their parental species. Previously collected data on Speleomantes were included to increase the robustness of these analyses. In only 33 out of 134 sampled hybrid Speleomantes we recognized 81 items belonging to 11 prey categories. The frequency of empty stomachs was higher in females and individuals from natural hybrid populations, whereas the largest number of prey was consumed by males. We compared the total length and body condition of 685 adult salamanders belonging to three types of hybrids and three parental (sub)species. Three group of salamanders (one hybrid and two parental species) showed significantly larger size, whereas no difference in body condition was observed. This study provided novel ecological information on Speleomantes hybrid populations. We also provided insights into the potential divergence between hybrids and parental species in terms of size and body condition. We discuss our findings, and formulate several hypotheses that should be tested in the future.

Structural hybridity and supernumerary chromosomes in a diploid Tradescantia hirsuticaulis

1975 ◽  
Vol 53 (5) ◽  
pp. 456-465 ◽  
Author(s):  
C. C. Chinnappa
Keyword(s):  
Reciprocal Translocation ◽  
Cytological Study ◽  
B Chromosomes ◽  
The Other ◽  
Meiotic Pairing ◽  
Structural Hybridity ◽  
Supernumerary Chromosomes

Cytological study of a diploid (2n = 12) population of Tradescantia hirsuticaulis Small from Stone Mountain, Georgia, revealed striking variation in four plants growing in a cluster, indicating that they constitute different genotypes. The occurrence of B chromosomes, fragments, and aneusomaty in the plants is associated with structural hybridity in the chromosomes. Two plants were homozygotes with simple meiotic pairing, one was heterozygous for a reciprocal translocation, and the other was a heterozygote for two interchanges as well as for inversions. The behavior and the origin of B chromosomes, fragments, and structural hybridity are discussed.

scholarly journals Fine Structure and Staining Behaviour of Heterochromatic Segments in Two Plants

1974 ◽  
Vol 14 (3) ◽  
pp. 505-521
Author(s):  
L. F. LACOUR ◽  
B. WELLS
Keyword(s):  
Fine Structure ◽  
Light Microscope ◽  
Mitotic Cycle ◽  
The Other ◽  
Masking Effect ◽  
Root Tips ◽  
Metaphase Chromosomes ◽  
Differential Reactivity ◽  
Scilla Sibirica ◽  
Electron Microscopes

With the use of the light and electron microscopes, the chromosomes of Fritillaria lanceolata and Scilla sibirica are shown to differ in respect of the heterochromatin they contain. In root meristems of the former, the heterochromatic regions (H-segments) were recognizable at all phases of the mitotic cycle by their slighter opacity to electrons than that of euchromatic parts. This was due both to less tight packing of the chromatin fibrils and lower opacity of the fibrils themselves, even though both had the same diameter, about 3 nm. In root tips of the Scilla, the heterochromatin was invariably of similar opacity to euchromatin and thus only recognizable at telophase and interphase as large chromocentres. The opacity to electrons in the heterochromatin of the 2 species, was at all times closely paralleled by the staining behaviour seen with the light microscope in sections (0.07-0.5 µm in thickness) stained with toluidine blue. The disparity in the Fritillaria, as seen in sections with the light microscope, in respect of the stainability of the hetero- and euchromatin, was masked in Feulgen squash preparations of root tips from plants grown at 18-20 °C; at metaphase by the thickness of the chromosomes and at interphase by the density of the chromocentres. When, on the other hand, the plants were grown for 4 days at 2 °C, the masking effect of thickness was circumvented in metaphase chromosomes by differential super-contraction in euchromatin. The implications of these findings in respect to previous interpretations of the differential reactivity of H-segments to low temperature, as well as the phenomenon of enhanced and reduced fluorescence in these segments with fluorochromes are discussed.

scholarly journals GENOME SIZE IN THREE SPECIES OF Glandularia AND THEIR HYBRIDS

2019 ◽  
Vol 30 (2) ◽  
pp. 47-54
Author(s):  
M.R. Ferrari ◽  
E.J. Greizerstein ◽  
L. Poggio
Keyword(s):  
Genome Size ◽  
Dna Content ◽  
High Frequency ◽  
Parental Species ◽  
The Other ◽  
F1 Hybrids ◽  
Homoeologous Pairing ◽  
The Relationship ◽  
Species Being ◽  
Homoeologous Chromosomes

In this work the relationship between genome size of Glandularia species and the meiotic configurations found in their hybrids are discussed. Glandularia incisa (Hook.) Tronc., growing in two localities of Corrientes and Córdoba provinces, Argentina, with different ecological conditions, showed inter-population variability of the 2C-value. The DNA content found in the Corrientes locality (2.41 pg) was higher than that obtained in the Córdoba locality (2.09 pg) which has more stressful environmental conditions than the former. These values are statistically different from those that were found in Glandularia pulchella (Sweet) Tronc. from Corrientes (1.43 pg) and in Glandularia perakii Cov. et Schn from Córdoba (1.47 pg). The DNA content of the diploid F1 hybrids, G. pulchella × G. incisa and G. perakii × G. incisa, differed statistically from the DNA content of the parental species, being intermediate between them. Differences in the frequency of pairing of homoeologous chromosomes were observed in the hybrids; these differences cannot be explained by differences in genome size since hybrids with similar DNA content differ significantly in their meiotic behavior. On the other hand, the differences in the DNA content between the parental species justify the presence of a high frequency of heteromorphic open and closed bivalents and univalents with different size in the hybrids. Key words: Intra-specific DNA content variability, homoeologous pairing, heteromorphic bivalents

Hybrids between Schistosoma mansoni and S. rodhaini: characterization by cercarial emergence rhythms

Parasitology ◽  
1989 ◽  
Vol 99 (2) ◽  
pp. 225-228 ◽  
Author(s):  
A. Thèron
Keyword(s):  
Schistosoma Mansoni ◽  
Parental Species ◽  
Genetic Determinism ◽  
The Other ◽  
Relative Importance ◽  
Emergence Rhythm ◽  
Cercarial Emergence

SummaryHybridization between Schistosoma mansoni, with a diurnal cercarial emergence rhythm and S. rodhaini, with a nocturnal cercarial shedding pattern leads to F1 and F2 generations, hybrid schistosomes whose chronobiological phenotype of cercariae is characterized by two unequal emergence peaks, one diurnal and the other nocturnal. The relative importance of diurnal and nocturnal peaks depends upon which S. mansoni strain (early or late) is used for the hybridization with S. rodhaini. The results are compared and discussed with those resulting from crosses between intraspecific sympatric and allopatric chronobiological variants (early and late) of S. mansoni. The genetic determinism of the cercarial emergence of schistosomes and the significant differences observed between cercarial shedding patterns of parental species and their hybrids allow the use of this behavioural marker in biological and genetical studies in schistosome populations.

scholarly journals Statistical analysis of chromosome distribution to the poles in interspecific hybrids with variable chromosome pairing

1963 ◽  
Vol 4 (2) ◽  
pp. 266-275 ◽  
Author(s):  
A. G. Sficas
Keyword(s):  
Statistical Analysis ◽  
Interspecific Hybrids ◽  
Random Distribution ◽  
The Other ◽  
Meiotic Pairing ◽  
Variable Amount ◽  
Short Discussion ◽  
Equal Distribution ◽  
Chromosome Separation ◽  
Opposite Tendency

A probability distribution of chromosome separation to the poles was developed to test the randomness of movement of univalents in asynaptic material where a variable amount of meiotic pairing occurs. Two tables were calculated, one for 24 chromosomes which can be used for any even number equal or less than 24, and the other for 19 chromosomes which can be used for any odd number equal or less than 19.Three Nicotiana hybrids, namely N. glutinosa × N. otophora, N. glutinosa, N. sylvestris, and N. tabacum × N. glutinosa, and one polyhaploid were investigated. All hybrids had a tendency towards an equal distribution of unpaired chromosomes to the poles. The polyhaploid N. tabacum (with a substituted N. plumbaginifolia chromosome) had an opposite tendency, i.e. towards a flatter distribution than expected from random distribution of univalents. A short discussion of the problem is given.

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