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 Memoirs: The Male Meiotic Phase in Two Genera of Marsupials (Macropus and Petauroides)

1923 ◽  
Vol s2-67 (266) ◽  
pp. 183-202
Author(s):  
W. E. AGAR
Keyword(s):  
Chromosome Number ◽  
Sex Chromosomes ◽  
Meiotic Division ◽  
Ovarian Follicle ◽  
The Other ◽  
Pachytene Stage ◽  
Follicle Cells ◽  
Crossing Over ◽  
Early Pachytene ◽  
Spermatogonial Metaphase

Macropus ualabatus has twelve chromosomes, namely 10 + XY in the male and 10 + XX in the female. In Petauroides the number is almost certainly twenty-two, the male being of the formula 20 + XY. No female counts were obtained for this animal. In the male Macropus Xis generally attached to one of the autosomes in spermatogonial mitoses. Y, which is exceedingly minute, is free. During the pachytene stage, while the autosomes are still elongated, X and Y condense into a bivalent. In the first meiotic division this bivalent is attached to an autosome. As a result of the first meiotic division the usual two classes of secondary spermatocytes are formed one with X and the other with Y. In the second meiotic division, those with X show only five separate chromosomes, showing that X, as usual, is fused with an autosome. The other class of second divisions shows five autosomes and the minute Y. In the female Macropus the sex chromosomes were never found free from the autosomes in the ovarian follicle cells, which therefore show only ten separate chromosomes. In Petauroides the sex chromosomes cannot be distinguished with certainty from the autosomes. An unequal pair of small chromosomes usually situated in the centre of the spermatogonial metaphase plates probably, however, are X and Y. Early pachytene nuclei show two compact bodies which unite into one, presumably the sex bivalent. The second reduction of the chromosome number to onequarter of the diploid total in the second meiotic division, which has been described for several species of birds and mammals, does not take place either in Macropus or Petauroides. Chromomeres are very prominent in Petauroides in the zygotene and diplotene stages. Probably in Macropus, and more convincingly in Petauroides, the cytological conditions to permit of ‘crossing over’ are present in the male. The plasmosome which appears in the pachytene stage is probably formed from the plastin or linin basis of the contracting sex chromosomes.

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.

INTROGRESSION BETWEEN THE CULTIVATED HEXAPLOID OAT A. SATIVA AND THE TETRAPLOID WILD A. MAGNA AND A. MURPHYI

1977 ◽  
Vol 19 (1) ◽  
pp. 59-66 ◽  
Author(s):  
G. Ladizinsky ◽  
R. Fainstein
Keyword(s):  
Gene Transfer ◽  
Chromosome Number ◽  
Small Proportion ◽  
Parental Species ◽  
Hexaploid Species ◽  
Pentaploid Hybrid ◽  
Restoration Of Fertility

Introgression between the hexaploid (2n = 42) oat A. sativa and the newly discovered tetraploid (2n = 28) species A. magna and A. murphyi was studied by the rate of stabilization of chromosome number, restoration of fertility of pentaploid hybrid derivatives and the ultimate gene transfer between the tetraploid and the hexaploid levels. The complete self-sterility of the pentaploid F1 hybrids was overcome by massive back-pollination to the parental species. Great variation in chromosome number (12-48) was found among the viable F1 female gametes. Meiotically stable and reasonably fertile derivatives were selected only at the F2 of the BC and in a relatively small proportion. Gene transfer between the tetraploid and the hexaploid species was demonstrated by introducing the allele for nonshattering seed from the cultivated oat A. sativa to both A. magna and A. murphyi, and lemma hairiness from the tetraploids to the hexaploid level. The possible exploitation of introgression between the polyploid oats for breeding purposes has been pointed out and the potential of A. magna and A. murphyi as cultivated oats has been briefly discussed.

scholarly journals Sexual and parasexual analysis of Ustilago violacea

1969 ◽  
Vol 14 (3) ◽  
pp. 195-221 ◽  
Author(s):  
A. W. Day ◽  
J. K. Jones
Keyword(s):  
Chromosome Number ◽  
Host Plant ◽  
High Frequency ◽  
Linkage Data ◽  
Crossing Over ◽  
Meiotic Segregation ◽  
Linkage Groups ◽  
Haploid Chromosome Number ◽  
Ustilago Violacea ◽  
Anther Smut

Forty-two mutants of the anther smut fungus Ustilago violacea were mapped by means of complementation tests, mitotic haploidization, and meiotic segregation. Spontaneous mitotic haploidization was very rare, but haploids were induced at a high frequency using p–fluorophenylalanine (PFP). Haploid segregants appeared as fast-growing, spherical colonies (papillae) which grew away from the diploid growth on PFP medium. Thirty-three markers, classified by complementation tests into 21 genes, were mapped by mitotic haploidization in 10–12 linkage groups. There were no discrepancies in the linkage data, and all the markers could be assigned unequivocally to linkage groups. Although about 250 diploids were analysed, there were no segregants in which mitotic crossing-over and mitotic haploidization appeared to have occurred simultaneously.Thirteen of the 33 markers, in six or seven genes, were expressed infrequently (0–5%) in the papillae produced on PFP medium. These markers, which behaved unusually and were designated missing-markers, were found to be on two chromosomes which tended to remain disomic on PFP medium. Thus 8–10 chromosomes haploidize readily on PFP medium, whereas two other chromosomes are resistant to the effects of PFP and remain disomic. Meiotic segregation was investigated in crosses of genetically marked haploid stocks and also hi diploids, using the host plant. Some of the results enabled preliminary maps to be made of three linkage groups. The results from meiotic segregation were fully compatible with those from mitotic haploidization and the complementation tests.The genetical evidence for a haploid chromosome number of at least 10–12 is in conflict with the observations of several cytologists that n = 2 in this species.

Familial supernumerary marker chromosome evolution through three generations

1998 ◽  
Vol 18 (2) ◽  
pp. 178-181 ◽  
Author(s):  
Siddharth G. Adhvaryu ◽  
Trisha Peters-Brown ◽  
Elizabeth Livingston ◽  
Mazin B. Qumsiyeh
Keyword(s):  
Chromosome Evolution ◽  
Marker Chromosome ◽  
Three Generations

The origins of invented vocabulary in a utopian Philippine language

2016 ◽  
Vol 2 (1) ◽  
pp. 82-120
Author(s):  
Piers Kelly
Keyword(s):  
Small Proportion ◽  
Historical Context ◽  
Linguistic Variation ◽  
Small Community ◽  
Three Generations

Abstract The utopian Eskayan language and script has been spoken for at least three generations by a small community on the island of Bohol in the southern Philippines. Speakers, who use the language in special domains, attribute its creation to a legendary ancestor known as Pinay. In this paper I consider the origins of Eskayan vocabulary, showing how lexical models from Cebuano, Spanish and English account for a small proportion of Eskayan lexemes. The traces of these colonial languages lend important clues to the development of the lexicon as a whole, shedding light on the tumultuous historical context in which Eskayan came into being. Further, the patterning of Eskayan vocabulary reveals Pinay’s folklinguistic conceptions about the nature of ‘language’ and linguistic variation.

A chromosome marker for the early detection of mouse embryos carrying the neural tube defect mutation splotch

1986 ◽  
Vol 28 (5) ◽  
pp. 862-866 ◽  
Author(s):  
C. M. Kapron-Brás ◽  
M. J. J. Vekemans ◽  
D. G. Trasler
Keyword(s):  
Neural Tube ◽  
Neural Tube Defects ◽  
Early Stage ◽  
Marker Chromosome ◽  
Paternal Age ◽  
Crossing Over ◽  
Chromosome Marker ◽  
Stage Of Development ◽  
Gene Carriers ◽  
Map Distance

A major problem in the study of neural tube defects caused by the splotch (Sp) gene in the mouse has been the identification of gene carriers or potentially affected embryos at an early stage of development, since the gene's effects become visible only late in gestation or after birth. To aid in the identification of Sp carriers, we have developed a technique using a Robertsonian translocation as a marker for this gene. The accuracy of identification is reduced by crossing-over between the Sp locus and the centromere but, because of crossover suppression in the particular cross used, there was only 23.2% recombination compared with the known map distance of 36%. Paternal age had no effect on the frquency of recombination, but individual males differed significantly in the degree of crossover suppression.Key words: mouse, embryo, neural tube defects, marker, chromosome.

scholarly journals Genetics of the Bombay Phenotype

Blood ◽  
1969 ◽  
Vol 33 (1) ◽  
pp. 124-132 ◽  
Author(s):  
EDMOND J. YUNIS ◽  
JANET M. SVARDAL ◽  
ROBERT A. BRIDGES
Keyword(s):  
Active Site ◽  
Genetic Basis ◽  
Crossing Over ◽  
First Report ◽  
Indian Family ◽  
Three Generations ◽  
Effective Suppression ◽  
H Gene ◽  
Lewis Gene

Abstract Seven individuals with the Bombay phenotype have been found among the thirty-three members of an Indian family spanning three generations. This is the first report of children resulting from the union of an individual of the Bombay phenotype hh and an individual heterozygous Hh at the Bombay locus. This family again demonstrates the effective suppression of the A-B-O phenotype by the Bombay genotype. Three Bombay individuals of this family were shown to be heterozygous at the Lewis locus. This had not been determinable in previously reported cases. This is consistent with the concept that there are two kinds of Bombay genotypes. We propose that the Lewis gene has evolved from a duplication of the H gene. Such duplication predisposes to both higher orders of duplication and to deletion. Deletions in this system would then provide the genetic basis for the Lewis-negative and the Bombay phenotype. In order to explain the rarity of the Lewis-negative Bombay phenotype by the proposed mechanism, we postulate that it would only arise by crossing over at the position determining the active site of the transferase enzymes which determine the Lewis and the H specificities.

Cytoplasmic Tubules in Cells Infected with Laryngotracheitis Virus

1969 ◽  
Vol 27 ◽  
pp. 376-377
Author(s):  
A. M. Watrach
Keyword(s):  
Tissue Culture ◽  
Small Proportion ◽  
Chicken Embryo ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Morphologic Characteristics ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus ◽  
In Cells

During a study of the development of infectious laryngotracheitis (LT) virus in tissue culture cells, unusual tubular formations were found in the cytoplasm of a small proportion of the affected cells. It is the purpose of this report to describe the morphologic characteristics of the tubules and to discuss their possible association with the development of virus.The source and maintenance of the strain of LT virus have been described. Prior to this study, the virus was passed several times in chicken embryo kidney (CEK) tissue culture cells.

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