A marker chromosome number 14 with double satellite observed in two generations: An unbalanced chromosome constitution associated with normal phenotype

1972 ◽  
Vol 15 (2) ◽  
pp. 191-195 ◽  
Author(s):  
F. Gigliani ◽  
A. Capoa ◽  
A. Rocchi
Keyword(s):  
Chromosome Number ◽  
Marker Chromosome ◽  
Chromosome Constitution ◽  
Normal Phenotype ◽  
Two Generations

scholarly journals Digynic triploidy in rabbit blastocysts after delayed insemination

1978 ◽  
Vol 32 (1) ◽  
pp. 9-18 ◽  
Author(s):  
R. A. Beatty ◽  
V. J. Coulter
Keyword(s):  
Chromosome Number ◽  
Sex Chromosomes ◽  
Somatic Cells ◽  
Marker Chromosome ◽  
Normal Incidence ◽  
Chromosome Constitution ◽  
Embryonic Cells ◽  
The One

SUMMARYThe origin of triploid (3N) 5½-day blastocysts in rabbits is inferred from the segregation of sex chromosomes and of an autosomal M-marker whose properties are described. 39 triploids and no tetraploids were scored among 1454 chromosomally scored blastocysts. A delay of 8 h between an ovulatory injection and subsequent insemination raised the estimated normal incidence of 0·59% triploid blastocysts to 3·13%. The increase is ascribed primarily to digyny (17 blastocysts), and to diandry probably mediated by dispermy (1 blastocyst). The triploid components of the two 2N/3N mosaics and the one 3N/6N were digynic. Neither superovulation nor insemination of excessive numbers of spermatozoa could be shown to give rise to triploid embryos. The diandric triploid was X Y Y, the first of this constitution apparently reported in the rabbit. There was some evidence that X X Y triploid blastocysts up to 5½-day gestation are more viable than X X X. In the 2N/3N mosaics each component had been entered by one spermatozoon, and the dliploid component could not have been merely a contamination by dliploid maternal somatic cells. In 2N/4N, 2N/4N/8N and 3N/6N mosaics, each polyploid component showed an exact doubling of the marker chromosome constitution of a component of lower ploidy; their origin is ascribed to doubling or redoubling of chromosome number in isolated embryonic cells. With earlier data included, 49·08 (± s.e. 1·96)% of 652 diploid blastocysts were X Y. 460 non-experimental weaned rabbits were all cliploid.

MEIOTIC STABILITY IN CONTROL AND NEWLY COLCHICINE-INDUCED DIHAPLOID BARLEY

1979 ◽  
Vol 21 (1) ◽  
pp. 33-35 ◽  
Author(s):  
R. A. Finch ◽  
M. D. Bennett
Keyword(s):  
Chromosome Number ◽  
Breeding Material ◽  
Two Generations ◽  
Meiotic Stability

Comparison of meiosis in barley plants treated with colchicine when seedling or juvenile haploids and in control dihaploids similarly treated two generations earlier shows that colchicine used to double the chromosome number of barley haploids has no effect on meiosis which could lead to difficulties in screening breeding material.

Prenatal detection and characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 22 with apparently normal phenotype

2006 ◽  
Vol 26 (10) ◽  
pp. 898-902 ◽  
Author(s):  
Chyi-Chyang Lin ◽  
Yao-Yuan Hsieh ◽  
Chung-Hsing Wang ◽  
Yueh-Chun Li ◽  
Lie-Jiau Hsieh ◽  
...  
Keyword(s):  
Marker Chromosome ◽  
Chromosome 22 ◽  
Normal Phenotype ◽  
Small Supernumerary Marker Chromosome ◽  
Prenatal Detection

scholarly journals Stability in chromosome number and DNA content in synthetic tetraploids of Lolium multiflorum after two generations of selection

2017 ◽  
Vol 47 (2) ◽  
Author(s):  
Roselaine Cristina Pereira ◽  
Natália de Souza Santos ◽  
Fernanda de Oliveira Bustamante ◽  
Andrea Mittelmann ◽  
Vânia Helena Techio
Keyword(s):  
Chromosome Number ◽  
Dna Content ◽  
Genetic Stability ◽  
Chromosome Doubling ◽  
Lolium Multiflorum ◽  
Colchicine Treatment ◽  
Italian Ryegrass ◽  
Chromosome Counting ◽  
Two Generations ◽  
Viable Seeds

ABSTRACT: Chromosome doubling of Italian ryegrass genotypes ( Lolium multiflorum Lam.) adapted to the brazilian edaphoclimatic conditions is an important strategy used by breeders and aims to obtain more vigorous genotypes with better forage quality and disease resistance. The effectiveness of chromosome doubling can be measured by genetic stability and fertility rates of plants over generations. However, a common problem in the polyploidization process is the regeneration of mixoploid plants that have impaired fertility and genetic stability. The objective of this study was to verify if progenies of recently tetraploidized plants remain stable regarding DNA content and chromosome number, over two generations. Progenies of L. multiflorum plants artificially tetraploidized with colchicine treatment were evaluated. Chromosome counting and estimates of the DNA content were used to evaluate the genetic stability. The percentage of tetraploid plants (4X) increased over generations (18%, 34% and 91% in cycle 0, 1 and 2, respectively). All progenies identified as tetraploid by flow citometry showed variation in chromosome number (mixoploidy), but produced viable seeds. Results showed that stabilization in chromosome number and DNA content in tetraploidized plant progenies requires time and that the success of this procedure depends on a continuous and accurate screening and selection.

scholarly journals Taxonomic Description and Reproductive Behavior of Giant Pangola (Digitaria valida Stent)

1969 ◽  
Vol 44 (2) ◽  
pp. 53-59
Author(s):  
A. Sotomayor-Ríos ◽  
K. F. Schertz ◽  
R. Woodbury ◽  
J. Vélez Fortuño
Keyword(s):  
Chromosome Number ◽  
Reproductive Behavior ◽  
Somatic Chromosome ◽  
Seed Set ◽  
Pollen Grains ◽  
Breeding Program ◽  
Chromosome Constitution ◽  
Low Fertility ◽  
Taxonomic Description ◽  
Multivalent Formation

The chromosome number and reproductive behavior of Giant Pangola, a type of Digitaria valida Stent, were determined to evaluate the possibility of using it in a breeding program. It was also described and verified taxonomically. The observations revealed anomalies which would appear to severely handicap its use in breeding. The somatic chromosome constitution of 42 is different from those previously reported for this species. Microsporogenesis was irregular in all cells studied, characterized by multivalent formation, lagging univalents, and micronuclei, and resulted in only 2.3 percent of the pollen grains staining completely in IKI solution. No degeneration was observed during megasporogenesis but was usually apparent after megaspore formation. It is concluded that the chromosomal irregularities noted may be sufficient to cause the very low seed set and that this low fertility will limit the utilization of Giant Pangola in a breeding program.

Yield improvement of oilseed rape (Brassica napus L.) in a low rainfall environment. I. Utilization of genes for early flowering in primary and secondary gene pools

1992 ◽  
Vol 43 (3) ◽  
pp. 609 ◽  
Author(s):  
N Thurling ◽  
R Kaveeta
Keyword(s):  
Brassica Napus ◽  
Chromosome Number ◽  
Flowering Time ◽  
Chromosome Complement ◽  
Early Flowering ◽  
Gene Pools ◽  
Yield Improvement ◽  
Two Generations ◽  
The Cross ◽  
Recurrent Backcrossing

The extent to which time to flowering of a Brassica napus commercial cultivar could be reduced through utilization of genes in its primary and secondary pools was examined with particular reference to yield improvement in lower rainfall environments. The B. napus breeding line RU2 and the B. campestris population Chinoli C42, which were used as sources of early flowering genes to be incorporated into the commercial B. napus cultivar Wesbrook, flowered significantly earlier than Wesbrook with or without vernalization and/or long days. In the cross of Wesbrook with RU2, the substantial variation in flowering time in the F2 was highly heritable (hn2 = 0.79), and some plants in the F2 and first backcross to Wesbrook flowered earlier than the early flowering parent RU2. Many lines flowering much earlier than Wesbrook were still obtained after two generations of recurrent backcrossing to Wesbrook and subsequent selfing without selection at any stage. Variation in flowering time among these lines primarily reflected differences in growth rate as measured by the rate of leaf node development. F2 plants derived from the cross between Wesbrook and the B. campestris population Chinoli C42 varied widely in chromosome number and flowering time, but there was no relationship between pre-anthesis development and chromosome number. Two generations of recurrent backcrossing to Wesbrook and subsequent selfing without selection at any stage produced a series of lines all having the normal B. napus chromosome complement. All these lines flowered significantly earlier than Wesbrook, and the earliest flowering line flowered at the same time as the early flowering B. campestris parent. The implications of these results are discussed with particular reference to developing agronomically superior B. napus cultivars closely adapted to lower rainfall environments in the Western Australian wheatbelt and elsewhere in southern Australia.

ASYMMETRY OF CHROMOSOME NUMBER 1 PAIR IN THREE GENERATIONS OF A PHENOTYPICALLY NORMAL FAMILY

1968 ◽  
Vol 10 (3) ◽  
pp. 575-589 ◽  
Author(s):  
Kuang-Lin Ying ◽  
Elizabeth J. Ives
Keyword(s):  
Chromosome Number ◽  
Small Proportion ◽  
Normal Family ◽  
Marker Chromosome ◽  
Culture Technique ◽  
Crossing Over ◽  
Replication Pattern ◽  
Genetic Inactivation ◽  
Three Generations ◽  
Extended Region

A family is reported in which 6 of the 15 members studied carry a greatly lengthened #1 chromosome. This has segregated in three generations without phenotypic effect.Blood grouping provides evidence in favour of linkage of the Duffy locus and #1 chromosome.Autoradiographic studies demonstrate that DNA replication in the extended region of the marker chromosome occurs late in the majority of cells but early in a small proportion of cells in each of the three individuals thus studied. Possible explanations discussed include environmental modifications in culture technique, an unstable replication pattern in the extended region, and the chance that somatic crossing over of homologues allows a shift of a hypothetical "genetic inactivation centre" from one chromosome to the corresponding region of its homologue.

scholarly journals The first case of a small supernumerary marker chromosome derived from chromosome 10 in an adult woman with an apparently normal phenotype

2015 ◽  
Vol 61 (6) ◽  
pp. 398-402
Author(s):  
Rosa Santacroce ◽  
Roberta Trunzo ◽  
Angelica Leccese ◽  
Angela Pansini ◽  
Mattia Gentile ◽  
...  
Keyword(s):  
Marker Chromosome ◽  
Adult Woman ◽  
Chromosome 10 ◽  
Normal Phenotype ◽  
Small Supernumerary Marker Chromosome ◽  
First Case

scholarly journals The chromosome constitution of the pomoideæ

1931 ◽  
Vol 108 (758) ◽  
pp. 423-446 ◽  
Keyword(s):  
Chromosome Number ◽  
Chromosome Pairing ◽  
Chromosome Numbers ◽  
Previous Investigation ◽  
Basic Number ◽  
Basic Chromosome Number ◽  
Chromosome Constitution ◽  
Basic Chromosome ◽  
Original Ancestor ◽  
Derived Series

Previous investigation on cultivated varieties of apples have shown that the apparent basic chromosome number is 17, but chromosome pairing, morphology and breeding results indicate that the 34 chromosome form a more complex constitution than that of an ordinary diploid. In a recent paper (Darlington and Moffett, 1930) it was concluded that in the cultivated apples the set of 34 chromosome in the diploid belong to seven types, three of which are represented six times and four them are represented four times. Thus the original ancestor of the apple would have had a basic number of 7, and the present number of 17 is a secondary basic number. The derived series of polyploids with chromosome numbers 34, 51 and 68 are, therefore, secondary polyploids.

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