The mitotic chromosomes of Marsupials and their bearing on taxonomy and phylogeny.

1961 ◽  
Vol 9 (1) ◽  
pp. 38 ◽  
Author(s):  
GB Sharman
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Parallel Evolution ◽  
Mitotic Chromosomes ◽  
Cytological Evidence ◽  
Separate Genus ◽  
Y Chromosomes ◽  
Related Group ◽  
Living Species ◽  
Potorous Tridactylus

Chromosome numbers of marsupials vary between 2n = 11 B 10 @ and 2n =24. Most species have 14 or 22 chromosomes. There is no evidence that polyploidy has occurred in marsupial evolution. The Dasyuridae have 12 metacentric autosomes, a small metacentric X-chromosome and a very small Y-chromosome (20% of living species have been studied) and the chromosomes of Myrmecobius fasciatus are typically like those of other Dasyuridae. The Peramelidae (30% of species have been studied) have chromosomes like the Dasyuridae except that X- and Y-chromosomes are much larger. The occurrence of similar chromosome numbers in Dasyuridae and Peramelidae is not necessarily evidence of affinity. The chromosomes of the Phascolomidae are similar in number and morphology to those of the Peramelidae and the resemblances are, almost certainly, due to parallel evolution. The chromosomes of Phascolarctos are unlike those of any of the Phalangeridae and this genus might be just as easily grouped with the Phascolomidae. The Phalangeridae have considerable chromosomal heterogeneity but less than 20% of species have been studied. Two species of Cercaertus have 12 metacentric autosomes and small sex chromosomes like all members of the Dasyuridae. This suggests that the primitive phalangers may have retained the chromosome number and morphology of possible dasyurid ancestors but the resemblances may be due to parallel evolution of similar chromosome number and morphology in separate groups. The chromosomes have been studied in more than 50% of Macropodinae. Cytological evidence suggests that Thylogale (3 species studied), Petrogale (2 species studied), and probably Lagorchestes (1 species studied), all with 22 chromosomes, are a related group. Onychogalea unguifer, with 20 chromosomes, may be derived from this group. There is no justification for the placing of Thylogale billardierii in the genus Protemnodon. Lagostrophus fasciatus has 2n = 24 and its placement in a monotypic genus is justified. Macropus major and all species of Protentnodon, except P. bicolor, are a related group with 16 chromosomes. M. robustus is possibly included in this group. M. rufus has 20 chromosomes and should perhaps be placed in the separate genus Megaleia. P. bicolor, with 11 chromosomes in the male and 10 in the female, differs from all other species of Protemnodon and this genus, as at present constituted, may be diphyletic. The relationships of P. bicolor are unknown. Setonix brachyurus has 22, mostly metacentric, chromosomes and its affinities are at present unknown. Three species of Bettongia (Potoroinae) have 22 chromosomes which are mostly metacentric. Hypsiprymnodon moschatus has 22 chromosomes which are mostly acrocentric. Both genera are very different cytologically from Potorous tridactylus.

Chromosome elimination in a complex hybrid of the genus Hordeum

1977 ◽  
Vol 55 (24) ◽  
pp. 3023-3033 ◽  
Author(s):  
Thomas J. Orton ◽  
William Tai
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Chromosome Elimination ◽  
Progressive Increase ◽  
Basic Chromosome Number ◽  
Chromosome Loss ◽  
Cytoplasmic Organelle ◽  
Cytological Evidence ◽  
Embryonic Tissues ◽  
Hordeum Jubatum

Hybrid embryos, derived from the cross combining a Hordeum jubatum (4x) – H. compressum (2x) amphiploid and H. vulgare (4x), were observed and found to exhibit instability of chromosome numbers that resulted in an overall loss during the first 8 days of development in embryonic tissues. This instability seemed to be manifest as a progressive increase in the variability of chromosome numbers over this developmental period. The change in the overall mean chromosome number followed no discernible pattern with the exception that counts appeared to be clustered at numbers which are exact multiples of the basic chromosome number (x = 7). For each day postpollination, however, the mean chromosome numbers were significantly lower than the expected zygotic number (with one exception), indicative of net chromosome loss. Based on the data presented and cytological evidence, possible mechanisms are proposed to account for chromosome elimination in hybrid tissues. Chromosome loss may result from an incompatible interaction of the chromosomes and spindle-timing determinants originating from each genome during development or as a consequence of the malfunctioning of a proposed cytoplasmic organelle.

A new diploid chromosome number for tomato (Lycopersicon esculentum)?

1984 ◽  
Vol 26 (5) ◽  
pp. 636-639 ◽  
Author(s):  
P. Banks
Keyword(s):  
Chromosome Number ◽  
Lycopersicon Esculentum ◽  
Chromosome Numbers ◽  
Centric Fusion ◽  
Diploid Chromosome Number ◽  
Mitotic Chromosomes ◽  
Tomato Chromosome ◽  
Hybrid Variety ◽  
Numerical Variation ◽  
Morphological Differences

The recognized chromosome number of tomato has been 2n = 24. In this paper the chromosome number 2n = 26 is reported in 18 varieties of tomato. One commercial hybrid variety, revealed 25 mitotic chromosomes. This variety, as well as the varieties with 26 chromosomes, appeared to be fully fertile. Different chromosome numbers did not appear to be associated with any morphological differences between the varieties examined. Preliminary meiotic examination of the variety 'Flora-Dade' (2n = 26 mitotic chromosomes) sometimes revealed 12 associations of chromosomes and sometimes 13 associations. Meiotic examination of the variety 'Sunny' (2n = 25 mitotic chromosomes) revealed what appeared to be 12 bivalents. Centric fission may account for the numerical variation of the diploid chromosome number of tomatoes.Key words: Lycopersicon, tomato, chromosome number, centric fusion.

Y Chromosomes in Male Psychiatric Patients above 180 cm. Tall

1968 ◽  
Vol 114 (517) ◽  
pp. 1589-1590 ◽  
Author(s):  
Johannes Nielsen
Keyword(s):  
Chromosome Number ◽  
State Hospital ◽  
Psychiatric Patients ◽  
Chromosome Analysis ◽  
Y Chromosomes ◽  
Sex Chromatin ◽  
Male Patients

All male patients above 180 cm. tall who were resident in the Århus State Hospital on 13 April, 1966, were registered: they numbered 42 out of the total of 440 resident males (8 · 1 per cent.). One patient, a 78-year-old man, died before chromosome analysis was made. Sex-chromatin analysis was made on Feulgenstained buccal smears and chromosome analysis was made on leucocyte cultures according to the method described by Moorhead et al. (1960), slightly modified. Not less than 25 metaphases were counted, at least 15 metaphases with the modal figure and all metaphases with a chromosome number deviating from the modal figures were analysed.

scholarly journals New Contribution to the Knowledge on the Chromosome Numbers of Turkish Cerambycidae (Coleoptera)

2021 ◽  
Vol 69 (2) ◽  
pp. 93-99
Author(s):  
Yavuz Koçak ◽  
Elmas Yağmur
Keyword(s):  
Chromosome Number ◽  
Sex Determination ◽  
Chromosome Numbers ◽  
Chromosome Count ◽  
Chromosomal Number ◽  
The Poor ◽  
Karyological Data ◽  
First Time

Information on the karyotypes of Turkish species of Cerambycidae is scanty. Our study contributes to the knowledge of the karyological data (chromosomal number and mechanism of sex determination) of five Turkish longicorn beetles; karyotypes of four taxa, one endemic, are described for the first time and for the remaining one, Purpuricenus budensis (Götz, 1783), the previously published chromosome count is confirmed. The chromosome number of Purpuricenus desfontainii inhumeralis Pic, 1891 and Purpuricenus budensis (Götz, 1783) (Cerambycinae, Trachyderini) was found to be 2n = 28 (13 + Xyp); Clytus rhamni Germar, 1817 and Plagionotus floralis (Pallas, 1773) (Cerambycinae, Clytini) 2n = 20 (9 + Xyp); and the endemic Dorcadion triste phrygicum Peks, 1993 (Lamiinae, Dorcadionini) 2n = 24 (11 + Xyp). In view of the paucity of data available until now, our study is important for both to improve the poor karyological knowledge of Turkish Cerambycidae and to provide an incentive for other researchers.

scholarly journals Karyotype Analysis of Alnus Mill. (Betulaceae) Species Originating From Northeastern Asia

2010 ◽  
Vol 59 (1-6) ◽  
pp. 219-223 ◽  
Author(s):  
Liu Jun ◽  
Ren Bao-Qing ◽  
Luo Peigao ◽  
Ren Zhenglong
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Karyotype Analysis ◽  
Full Potential ◽  
Northeastern Asia ◽  
Ploidy Levels ◽  
Genetic Makeup ◽  
Fossil Records

Abstract Alnus Mill. (alder) is an ecologically valuable tree genus. It is essential to study its genetic makeup in order to use alder trees to their full potential. Five specimens from four Alnus species (A. mandshurica, A. pendula, A. sibirica, and A. sieboldiana), found in northeastern Asia, were subjected to karyotype analysis. The analysis showed that these tree samples could be divided into three categories based on chromosome numbers or ploidy levels: viz., 2n = (4x) = 28, 2n = (8x) = 56 and 2n = (16x) = 112. The differences in chromosome number and karyotype parameters among Alnus species and even within the same species possibly resulted from natural polyploidization. Comparing the chromosome numbers of Alnus species in China with those in Japan showed that there appear to be only two categories in China, whereas there are up to five categories in Japan. The earliest fossil records of Alnus pollen were also discovered in Japan. We conclude that the center origin of Alnus spp. is Japan rather than China.

The Chromosome Numbers and Nuclear Cytology of Some Common British Serpulids

1960 ◽  
Vol s3-101 (56) ◽  
pp. 395-400
Author(s):  
S. DASGUPTA ◽  
A. P. AUSTIN
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Somatic Cells ◽  
Diploid Chromosome Number ◽  
Iron Alum ◽  
Artificial Fertilization ◽  
Nuclear Cytology

The chromosome numbers of Hydroides norvegica, Mercierella enigmatica, and Pomatoceros triqueter were determined from squashes of somatic cells in young embryos obtained by artificial fertilization, and stained with iron-alum/aceto-carmine. All had a diploid count of zn = 26 chromosomes. Mitotic and meiotic divisions in the 5 species of Spirorbis examined, and in Filograna implexa, all revealed a diploid chromosome number of 2n = 20. A diploid chromosome number of 14 is suggested for the ancestral serpulid.

Chromosome studies on African plants. 9. Chromosome numbers in Ehrharta (Poaceae: Ehrharteae)

Bothalia ◽  
1989 ◽  
Vol 19 (1) ◽  
pp. 125-132 ◽  
Author(s):  
J. J. Spies ◽  
E. J. L. Saayman ◽  
S. P. Voges ◽  
G. Davidse
Keyword(s):  
Chromosome Number ◽  
Ploidy Level ◽  
Chromosome Numbers ◽  
Basic Chromosome Number ◽  
B Chromosomes ◽  
Basic Chromosome ◽  
Cytogenetic Studies ◽  
African Plants ◽  
First Time

Cytogenetic studies of 53 specimens of 14 species of the genus  Ehrharta Thunb. confirmed a basic chromosome number of 12 for the genus. Chromosome numbers for 13 species are described for the first time. The highest ploidy level yet observed in the genus (2n = lOx = 120) is reported for E. villosa var.  villosa. B chromosomes were observed in several specimens of four different species.

Cytology of somatic and gametangial nuclei in Phytophthora capsici and Phytophthora megasperma var. sojae

1974 ◽  
Vol 52 (9) ◽  
pp. 2055-2060 ◽  
Author(s):  
L. W. Stephenson ◽  
D. C. Erwin ◽  
J. V. Leary
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Phytophthora Capsici ◽  
Relative Size ◽  
Pollen Tubes ◽  
Reduction Division ◽  
Phytophthora Megasperma ◽  
Linear Alignment ◽  
Size Of Nuclei

Nuclear divisions in the hyphae and gametangia of Phytophthora capsici and in hyphae of Phytophthora megasperma var. sojae resembled those of typical mitosis. The chromosomal configurations in prophase are similar to classical angiosperm prophase configurations. However, in metaphase the linear alignment of chromosomes resembled the pattern reported in pollen tubes of Lilium and Tradescantia. The relative size of nuclei and numbers of chromosomes per nucleus remained constant during gametangial development. Somatic and gametangial nuclei were about equal in size and chromosome number. Chromosome numbers in somatic and gametangial nuclei of P. capsici and P. megasperma var. sojae were about six and eight, respectively. There was no evidence of reduction division in gametangia.

CHROMOSOME NUMBER, VOLUME AND NUCLEAR VOLUME RELATIONSHIPS IN A POLYPLOID SERIES (2X-20X) OF THE GENUS RUMEX

1971 ◽  
Vol 13 (4) ◽  
pp. 842-863 ◽  
Author(s):  
S. Ichikawa ◽  
A. H. Sparrow ◽  
C. Frankton ◽  
Anne F. Nauman ◽  
E. B. Smith ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Abrupt Change ◽  
Diploid Species ◽  
Nuclear Volume ◽  
Polyploid Series ◽  
Unidentified Species

Ninety-one acquisitions of the genus Rumex obtained from various sources were examined taxonomically and cytologically. These acquisitions included 36 species plus 2 unidentified species. The chromosome numbers counted were 2n = 14 (or 15), 16, 18, 20, 40, 42, 60, 80, 100, 120, 140, 160, ca. 170, 180 and ca. 200. The count of 2n = 180 made on one of the R. orbiculatus acquisitions is a new count for this genus, but other acquisitions had 160 and ca. 170. First counts were obtained for four species, R. frutescens (2n = 160), R. crystallinus (2n = 60), R. cristatus (2n = 80) and R. tenax (2n = 80). The count of 2n = 160 for R. frutescens is the highest chromosome number ever reported in the section Axillares. The chromosome numbers determined in R. palustris (2n = 60), R. confertus (2n = 100), R. arcticus (2n = 120) and R. aquaticus (2n = 140) differ from previously published counts. Our counts for eight other species support one of the previous counts where two or more counts are reported. It is shown that the species of the subgenus Acetosa sections Acetosa and Vesicarii and of the subgenus Platypodium have relatively large chromosomes, those of the subgenus Acetosa section Scutati and of the subgenus Acetosella have medium-sized chromosomes, and the members of the subgenus Rumex sections Axillares and Rumex have smaller chromosomes. The chromosomes of the diploid species of the section Rumex were larger than those of the polyploids (4x to 20x) of the same section. Within the section Rumex the log of nuclear volume increased with increasing ploidy, with an abrupt change (decrease) in slope between the 12x and 14x levels.

KARYOLOGICAL RELATIONSHIPS IN TURTLES (REPTILIA: CHELONIA)

1972 ◽  
Vol 14 (4) ◽  
pp. 859-868 ◽  
Author(s):  
A. Dean Stock
Keyword(s):  
Chromosome Number ◽  
Sex Chromosomes ◽  
Mitotic Chromosomes ◽  
Meiotic Chromosomes ◽  
Telocentric Chromosomes ◽  
Chromosome Karyotype

The mitotic chromosomes of 33 species of chelonians representing 22 genera and six families were investigated. Chromosome number and morphology are the same for most members of a given family and range from 66 in Trionyx to 34 in Pelomedusa. Most emydid genera have 50 chromosomes. The karyotype of Chelydra (2n = 52) is similar to those of some testudinid and emydid genera and is unlike the 56 chromosome karyotype of kinosternid turtles. The three genera of tortoises examined, Gopherus, Testudo, and Geochelone, have 52 chromosomes, but Gopherus differs in karyotypic details. The karyotype of Geochelone is like that of Chelydra and the 52 chromosome genera of emydid turtles. The African pleurodiran Pelomedusa has three additional pairs of small acrocentric or telocentric chromosomes not present in the earlier described karyotype of Podocnemis. Examination of meiotic chromosomes revealed frequencies of chiasmata formation similar to those reported earlier. Sex chromosomes were not distinguishable.

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