Mitotic analysis of the North American white sturgeon, Acipenser transmontanus Richardson (Pisces, Acipenseridae), a fish with a very high chromosome number

Genome ◽  
1998 ◽  
Vol 41 (2) ◽  
pp. 266-271 ◽  
Author(s):  
A L Eenennaam ◽  
J D Murray ◽  
J F Medrano
Keyword(s):  
Chromosome Number ◽  
North American ◽  
Sex Chromosome ◽  
Chromosomal Polymorphism ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Banding Technique ◽  
Supernumerary Chromosomes ◽  
C Banding ◽  
The North

The average chromosome number of the North American white sturgeon, Acipenser transmontanus Richardson, was found to be 271 ± 2.5 (ranging from 265 to 276). This number is significantly higher than previous estimates for this species. A representative karyotype was found to consist of 132 meta- and submeta-centric chromosomes, 44 acrocentric chromosomes, and 98 microchromosomes. An improved C-banding technique revealed variation (2-7) between animals in the number of entirely heterochromatic metacentric chromosomes. These heterochromatic chromosomes may represent supernumerary chromosomes. There was no cytogenetic evidence of a heteromorphic sex chromosome pair or any sex-related chromosomal polymorphism in either sex of this species.Key words: C-banding, fish, karyotype, supernumerary chromosomes, white sturgeon.

Chromosomes of the Parasitic Isopod Anilocra Physodes

Crustaceana ◽  
1996 ◽  
Vol 69 (1) ◽  
pp. 56-62
Author(s):  
Maria Stella Colomba ◽  
Roberto Vitturi ◽  
Lorenzo Pellerito ◽  
Eliodoro Catalano
Keyword(s):  
Chromosome Number ◽  
Diploid Number ◽  
Centromeric Region ◽  
Banding Technique ◽  
Robertsonian Fusion ◽  
Mitotic Chromosomes ◽  
C Banding ◽  
Parasitic Isopod

AbstractCounts of mitotic chromosomes have allowed to determine 2n = 12 as the modal diploid number of Anilocra physodes. Application of the C-banding technique reveals that two hetero-chromatic blocks bordering the centromeric region occur in each chromosome. This supports the notion that the actual low chromosome number of A. physodes may have been derived through a process of Robertsonian fusion.

Multiple supernumerary chromosomes in the pseudogamous parthenogenetic flatworm Polycelis nigra: lineage markers or remnants of genetic leakage?

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 850-856 ◽  
Author(s):  
Timothy F. Sharbel ◽  
Leo W. Beukeboom ◽  
Laas P. Pijnacker
Keyword(s):  
Chromosome Doubling ◽  
B Chromosome ◽  
B Chromosomes ◽  
Banding Technique ◽  
Free Living ◽  
Transmission Rates ◽  
Supernumerary Chromosomes ◽  
C Banding ◽  
Male Line ◽  
Lineage Markers

Polycelis nigra is a free-living simultaneous hermaphroditic flatworm that has amphimictic and pseudogamous parthenogenetic biotypes. Sexual individuals are always diploid (2n = 16) and pseudogamous parthenogens are polyploid (usually triploid). Two types of supernumerary chromosomes are found in parthenogens, those resembling autosomes ("A-like") and typical B chromosomes, both of which reach frequencies in populations of close to 100%. Experiments measuring the transmission rates of the B chromosomes indicated that they are potentially inherited via the male line, escaping expulsion by pseudogamous parthenogenesis. This study used the C-banding technique to demonstrate (i) that there is a single morphologically distinct B chromosome (B1) and (ii) that there are two "A-like" chromosomes that can be considered B chromosomes (B2 and B3) and which are not simple polysomics of one of the eight autosomes. As there is no genetic exchange between pseudogamous parthenogenetic lineages, two different individuals carrying a similar B morph must either have received it through common ancestry (a lineage marker) or have acquired it horizontally from another parthenogenetic lineage (leakage). C-banding further revealed intra-individual heteromorphy for band regions on chromosomes 5 and 8. This supports the karyotypic observation that oogenesis is preceded by premeiotic chromosome doubling followed by pairing of replicate homologues.Key words: B chromosome, C-banding, heterochromatin, heteromorphy, pseudogamous parthenogenesis.

Taxonomy of the Carex flava complex (Cyperaceae) in North America and northern Eurasia. II. Taxonomic treatment

1989 ◽  
Vol 67 (4) ◽  
pp. 1048-1065 ◽  
Author(s):  
William J. Crins ◽  
Peter W. Ball
Keyword(s):  
North America ◽  
Chromosome Number ◽  
North American ◽  
Northern Eurasia ◽  
Distribution Maps ◽  
Taxonomic Treatment ◽  
The North ◽  
Infraspecific Taxa ◽  
History Of ◽  
Inflorescence Structure

The taxonomy of the Carex flava complex (section Ceratocystis) in North America and northern Eurasia is revised. Three species are recognized in this complex (C. flava L., C. cryptolepis Mack., and C. viridula Michx.). Carex viridula contains six infraspecific taxa, which are differentiated on the basis of differences in inflorescence structure, degree of perigynium curvature, leaf and bract morphology, chromosome number, and ecological preference. Three nomenclatural changes are required: C. viridula ssp. brachyrrhyncha (Čelak.) B. Schmid var. elatior (Schlecht.) Crins, comb.nov.; C. viridula ssp. brachyrrhyncha var. nevadensis (Boiss. & Reuter) Crins, comb.nov.; C. viridula ssp. brachyrrhyncha var. saxilittoralis (Robertson) Crins, comb, et stat.nov. This classification reflects the results of morphological, ecological, and cytological studies, and is also consistent with the hypothesized phylogenetic history of the section as a whole. A key is provided for all of the North American and northern Eurasian members of section Ceratocystis. Descriptions and distribution maps for members of the C. flava complex are also provided.

BASIC CHROMOSOME NUMBER, CYANOGENETIC GLUCOSIDE VARIATION, AND GEOGRAPHIC DISTRIBUTION OF LOTUS SPECIES

1967 ◽  
Vol 45 (5) ◽  
pp. 639-647 ◽  
Author(s):  
William F. Grant ◽  
B. S. Sidhu
Keyword(s):  
Chromosome Number ◽  
Geographic Distribution ◽  
North American ◽  
New World ◽  
Basic Chromosome Number ◽  
North American Species ◽  
Hydrocyanic Acid ◽  
Basic Chromosome ◽  
Fresh Leaf ◽  
The North

Leaves of 51 species and three varieties of Lotus (Leguminosae) were assessed quantitatively for hydrocyanic acid (HCN) reaction intensity and the data correlated with basic chromosome number and geographic distribution. The presence of HCN was determined from 0.05 grams of fresh leaf samples by the picric acid – filter paper technique. A gradation of 10 different color reactions (−), (±), and (+1 to +8) was used to compare the HCN reaction for each species. On the basis of potassium cyanide equivalents, each gram of fresh leaf material was estimated to contain an amount of HCN which varied between the different plants and accessions from 0.5 mg to 750 mg. Most of the Old World species were positive for HCN, whereas the reverse was true for the North American species. This would favor the previous separation of the North American species into a separate genus Hosackia. All of the n = 7 species have a greater concentration of HCN than the n = 6 species in both the Old and New World. None of the n = 6 species in the New World reacted positively. Therefore, there was a reduction of HCN with evolutionary development. Two colchicine-induced tetraploids (4x = 24, 28) gave a lower HCN reaction than their diploid counterparts. Leaves of L. siliquosus (n = 7) reacted negatively to the HCN test; however, the cotyledons gave a highly positive reaction supporting the retention of the generic name Tetragonolobus (T. siliquosus (L.) Roth.) for this species. Chromosome number determinations are reported for the first time for L. holosericeus Webb and Berth. (2n = 14), L. mascaensis Buchard (2n = 28), L. nevadensis Greene (2n = 14), L. helleri Britton (2n = 14), and L. oblongifolius var. nevadensis (Gray) Munz (2n = 14).

A satellite DNA evolutionary analysis in the North American endemic dioecious plant Rumex hastatulus (Polygonaceae)

Genome ◽  
2011 ◽  
Vol 54 (4) ◽  
pp. 253-260 ◽  
Author(s):  
M.E. Quesada del Bosque ◽  
R. Navajas-Pérez ◽  
J.L. Panero ◽  
A. Fernández-González ◽  
M.A. Garrido-Ramos
Keyword(s):  
North Carolina ◽  
North American ◽  
Satellite Dna ◽  
Sex Chromosome ◽  
Sequence Variant ◽  
Evolutionary Analysis ◽  
Dioecious Plant ◽  
The North ◽  
Sex Chromosome System ◽  
Rumex Hastatulus

We studied the evolution of RAE180 satellite DNA family in the North American endemic dioecious plant Rumex hastatulus . In this species, the Texas race is characterized by a single XX/XY sex chromosome system, whereas the North Carolina race has evolved a derived complex XX/XY1Y2 sex chromosome system. RAE180 repeats were autosomic and poorly represented (2 × 10–4% of the genome) with no differences between individuals of different genders or different races of R. hastatulus. In fact, the sex chromosomes of the North Carolina race are still euchromatic, and they have not accumulated satellite DNA sequences, which contrasts with that occurring in the rest of dioecious XX/XY1Y2 Rumex species. In R. hastatulus, we detected the existence of three RAE180 subfamilies. Notwithstanding, while in the Texas race the TX1/NC1 subfamily is the most frequent, the TX2/NC2 subfamily is the most abundant in the North Carolina race. Additionally, the third, less represented subfamily (TX3/NC3) appears currently as relict sequences in both genomes. A common feature of RAE180 satellite is the sudden replacement of one sequence variant by another in different species (or populations as in R. hastatulus races). Thus, the phylogenetic analysis of RAE180 repeats from six dioecious Rumex species supports the “library” hypothesis. According to this hypothesis, we assume that a set of divergent RAE180 variants were present in the ancestral genome of dioecious Rumex species, from which novel tandem arrays originated by the amplification of different variants in different lineages. Differential levels of RAE180 satellite DNA amplification in each lineage, at different evolutionary times, and in different chromosomal positions gave rise to differential patterns of sequence evolution.

TAXONOMICAL VALUE OF ALISMA TRIVIALE PURSH AND ALISMA SUBCORDATUM RAFIN

1963 ◽  
Vol 41 (7) ◽  
pp. 1011-1013 ◽  
Author(s):  
Eugenia Pogan
Keyword(s):  
Chromosome Number ◽  
North American ◽  
Morphological Characters ◽  
The North

Detailed morphological and karyological studies have revealed that the North American taxa of the Alisma plantago-aquatica complex are most appropriately classified as the two species, A. subcordatum Rafin. (2n = 14), and A. triviale Pursh (2n = 28). The morphological characters separating these species and distinguishing them from the European diploid, A. plantago-aquatica L., s. str., are given, and also the chromosome number of American material of A. gram-ineum Gmel. (2n = 14).

Sign in / Sign up

Export Citation Format

Share Document