CYTOTAXONOMY AND SEX DETERMINATION OF RUMEX PAUCIFOLIUS

1956 ◽  
Vol 34 (2) ◽  
pp. 261-268 ◽  
Author(s):  
Áskell Löve ◽  
Nina Sarkar
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
The Other ◽  
Large Chromosome ◽  
Dioecious Species ◽  
The Third ◽  
Male Sex ◽  
Morphological Differences

The western North American dioecious species Rumex paucifolius is shown to be a tetraploid with 2n = 28 chromosomes. It is the third tetraploid known within the subgenus Acetosa, and the first polyploid dioecious taxon of that group, the others having either 2n = 14 ♂, 15 ♀ (R. Acetosa and relatives), or 2n = 8 ♂, 9 ♀ (R. hastatulus). The sex chromosomes of R. paucifolius are of the XX:XY type, the male sex being heterogametic. The X is a large chromosome, while the Y is the smallest chromosome of the complement. The mechanism of sex determination of R. paucifolius follows the Melandrium–Acetosella scheme with strongly epistatic male determinants in the Y–chromosome. Other dioecious Acetosae follow the Drosophila–Acetosa scheme of sex determination with a balance between the number of X and autosome complements, the Y being sexually inert. It is concluded from the observed cytogenetical and morphological differences that R. paucifolius should constitute a section of its own, Paucifoliae, which should be placed as far as possible from the section Acetosa, though within the same subgenus. The other American dioecious endemic, R. hastatulus, is placed in a subsection of the section Acetosa.

scholarly journals On the origin of sex chromosomes from meiotic drive

2015 ◽  
Vol 282 (1798) ◽  
pp. 20141932 ◽  
Author(s):  
Francisco Úbeda ◽  
Manus M. Patten ◽  
Geoff Wild
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Meiotic Drive ◽  
The Other ◽  
Evolution Of Sex ◽  
Dioecious Species

Most animals and many plants make use of specialized chromosomes (sex chromosomes) to determine an individual's sex. Best known are the XY and ZW sex-determination systems. Despite having evolved numerous times, sex chromosomes present something of an evolutionary puzzle. At their origin, alleles that dictate development as one sex or the other (primitive sex chromosomes) face a selective penalty, as they will be found more often in the more abundant sex. How is it possible that primitive sex chromosomes overcome this disadvantage? Any theory for the origin of sex chromosomes must identify the benefit that outweighs this cost and enables a sex-determining mutation to establish in the population. Here we show that a new sex-determining allele succeeds when linked to a sex-specific meiotic driver. The new sex-determining allele benefits from confining the driving allele to the sex in which it gains the benefit of drive. Our model requires few special assumptions and is sufficiently general to apply to the evolution of sex chromosomes in outbreeding cosexual or dioecious species. We highlight predictions of the model that can discriminate between this and previous theories of sex-chromosome origins.

SEX AND SUPERNUMERARY CHROMOSOMES IN THE DIOECIOUS GRASS SOHNSIA FILIFOLIA

1972 ◽  
Vol 14 (1) ◽  
pp. 175-180 ◽  
Author(s):  
D. N. Singh
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Supernumerary Chromosome ◽  
The Other ◽  
Male Plant ◽  
Diploid Male ◽  
Male And Female ◽  
Supernumerary Chromosomes ◽  
Determination System ◽  
Sex Determination System

A dioecious grass Sohnsia filifolia (Fourn.) Airy Shaw (Syn. Calamochloa filifolia Fourn.) from Mexico has been found to have 2n = 20 chromosomes in both male and female plants. The staminate plants have one chromosome much longer than the other chromosomes of the complement. One pistillate plant was found to have 30 chromosomes, among which the largest chromosome is quite similar to the largest component of the diploid male plant. The longest chromosome has been designated as the Y chromosome. An XY-mechanism of the Drosophilia type has been suggested for the sex determination system in this species. One small supernumerary chromosome was observed in the microsporocytes of some male plants, but was absent in roots.

Clues from other animals and theoretical considerations

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 3-4
Author(s):  
Anne McLaren
Keyword(s):  
Sex Determination ◽  
Genetic Control ◽  
Y Chromosome ◽  
X Chromosome ◽  
X Chromosomes ◽  
The Third ◽  
Mouse Species ◽  
Primary Male ◽  
Theoretical Considerations ◽  
State Of Activity

In the first two papers of this volume, the genetic control of sex determination in Caenorhabditis and Drosophila is reviewed by Hodgkin and by Nöthiger & Steinmarin-Zwicky, respectively. Sex determination in both cases depends on the ratio of X chromosomes to autosomes, which acts as a signal to a cascade of règulatory genes located either on autosomes or on the X chromosome. The state of activity of the last gene in the sequence determines phenotypic sex. In the third paper, Erickson & Tres describe the structure of the mouse Y chromosome and the polymorphisms that have been detected in different mouse species and strains. As in all mammals, the Y carries the primary male-determining locus; autosomal genes may also be involved in sex determination, but they must act down-stream from the Y-linked locus.

Y chromosome specific markers and the evolution of dioecy in the genus Silene

Genome ◽  
1998 ◽  
Vol 41 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Y Hi Zhang ◽  
Veronica S Stilio ◽  
Farah Rehman ◽  
Amy Avery ◽  
David Mulcahy ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Silene Latifolia ◽  
Dioecious Species ◽  
Sequence Characterized Amplified Region ◽  
Y Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Males And Females ◽  
Genus Silene ◽  
Evolution Of Dioecy

Sex determination in plants has been most thoroughly investigated in Silene latifolia, a dioecious species possessing heteromorphic sex chromosomes. We have identified several new Y chromosome linked RAPD markers and converted these to more reliable sequence characterized amplified region (SCAR) markers by cloning the RAPD fragments and developing longer primers. Of the primer pairs for seven SCARs, five amplify a single, unique fragment from the DNA of male S. latifolia. Two sets of primers also amplify additional fragments common to males and females. Homology between the X and Y chromosomes is sufficient to allow the amplification of fragments from females under less stringent PCR conditions. Five of the SCARs also distinguish between the sexes of closely related dioecious taxa of the section Elisanthe, but not between the sexes of distantly related dioecious species. These markers will be useful for continued investigations into the evolution of sex, phylogenetic relationships among taxa, and population dynamics of sex ratios in the genus Silene.Key words: Melandrium, RAPDs, sex chromosomes, SCARs.

scholarly journals The Determination of Stacking Fault Energy by the Tetrahedron Method

1968 ◽  
Vol 21 (6) ◽  
pp. 941 ◽  
Author(s):  
P Humble ◽  
CT Forwood
Keyword(s):  
Electron Microscope ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
The Other ◽  
Dislocation Loops ◽  
The Third ◽  
Wide Range ◽  
Length Measurements ◽  
Incomplete Theory

At present there are three methods for obtaining values of the stacking fault energy y of face-centred cubic (f.c.c.) materials by direct observation of dislocationstacking fault configurations in the electron microscope. These are based on measurements of extended three-fold dislocation nodes (e.g. Whelan 1958; Brown and ThOlen 1964), faulted dipole configurations (e.g. Haussermann and Wilkens 1966; Steeds 1967), and triangular Frank dislocation loops and stacking fault tetrahedral (e.g. Silcox and Hirsch 1959; Loretto, Clarebrough, and Segall 1965). The main advantages of the third method over the other two are that it is applicable to materials of a very wide range of stacking fault energy and involves only simple length measurements of defects that are easily recognized. However, it has suffered from the disadvantage that the values of y deduced from these measurements relied on an incomplete theory. The present authors have reconsidered this problem and, subject to the limitations of isotropic linear elasticity, have taken into account the major variables that may affect the values of y. It is the purpose of this note to present the results of this theory in a form in which values of y may easily be obtained from measurements of Frank dislocation loops and stacking fault tetrahedral without the resources of a large digital computer.

scholarly journals AL-QUR'AN DAN MATERIAL GENETIK DALAM SEL KELAMIN PRIA PENENTU JENIS KELAMIN BAYI

2018 ◽  
Vol 8 (2) ◽  
pp. 141-162
Author(s):  
Bayyinatul Muchtaromah
Keyword(s):  
Molecular Biology ◽  
Sex Determination ◽  
Y Chromosome ◽  
X Chromosome ◽  
Seventh Century ◽  
The Other ◽  
Male And Female

In many verses of al-Qur'an, men are called to pay their attention to understand how they were created. Human creation and incredible aspects followed were strongly mentioned in many verses in detail until it's impossible for anyone who lived in the seventh century to recognize it. One of them was the information saying that the determinant of baby gender is the spermatozoa coming from men sperm. Allah said in his verse: "and that He (Allah) creates in pairs, male and female. From Nutfah (drops of semen male and female discharge) when it is emitted" (translation of al-Qur'an 53 verse 45-46). Branches of knowledge which have developed, such as Genetics and Molecular Biology, have proved scientifically the information accuracy which has been given by al-Qur'an. Nowadays it has been well-known that sex determination is determined by sperm of man and in fact women play no roles in this determination. If the ovum fuses with sperm which carries Y chromosome than the baby will be born as a male. Conversely, if the sperm carries X chromosome than the baby will be a female. In the other word, the sex of the baby is determined by the kind of man's sperm chromosome which fuses with women's ovum.

Sex determination in mice: Y and chromosome 17 interactions

Development ◽  
1987 ◽  
Vol 101 (Supplement) ◽  
pp. 25-32
Author(s):  
Robert P. Erickson ◽  
Edward J. Durbin ◽  
Laura L. Tres
Keyword(s):  
Sex Determination ◽  
Y Chromosome ◽  
Dna Sequences ◽  
Sex Differentiation ◽  
Specific Antigen ◽  
Inbred Strains ◽  
Chromosome 17 ◽  
Male Sex ◽  
Male Specific ◽  
Type Chromosome

Mice provide material for studies of Y-chromosomal and autosomal sequences involved in sex determination. Eicher and coworkers have identified four subregions in the mouse Y chromosome, one of which corresponds to the Sxr fragment. This fragment demonstrates that only a small portion of the Y is necessary for male sex determination. The mouse Y chromosome also shows variants: the BALB/cWt Y chromosome, which causes nondisjunction of the Y in some germ cells leading to XO and XYY cells and resulting in many infertile true hermaphrodites; the YDom, a wild-type chromosome which can result in sex reversal on a C57BL/6J background; and Y-chromosomal variants detected with Y-derived genomic DNA clones among inbred strains. Two different autosomal loci affecting sex differentiation have been identified in the mouse by Eicher and coworkers. The first of these has not been mapped to a particular chromosome and has been designated Tda-1 (Testis-determining autosomal-1). This is the locus in C57BL/6J mice at which animals must be homozygous in order to develop as true hermaphrodites or sex-reversed animals in the presence of YDom. The other locus has been identified on proximal chromosome 17. This locus also caused hermaphrodites on the C57BL/6J background and it is most easily interpreted as a locus deleted in 7hp. It is located in a region on chromosome 17 containing other genes or DNA sequences that may be related to sex determination. These include both the Hye (histocompatibility Y expression) locus that affects the amount of male-specific antigen detected by serological and cell-mediated assays and a concentration of Bkm sequences. Despite the Y and chromosomal 17 localizations of Bkm sequences, there is no evidence that transcripts from these are involved in sex determination: RNA hybridizing to sense and anti-sense Bkm clones can be detected in day-14 fetal gonads of both sexes.

On the determination of the dorso-ventral polarity in the amphibian embryo: suppression by lactate of the formation of Ruffini's flask-cells

Development ◽  
1976 ◽  
Vol 36 (2) ◽  
pp. 343-354
Author(s):  
Ulf Landström ◽  
Huguette Løvtrup-Rein ◽  
Søren Løvtrup
Keyword(s):  
Cell Differentiation ◽  
Rna Synthesis ◽  
Ambystoma Mexicanum ◽  
The Other ◽  
Animal Cells ◽  
Amphibian Embryo ◽  
Aerobic Conditions ◽  
The Third

Cells isolated from the vegetal hemisphere of the blastula of Ambystoma mexicanum differentiate spontaneously into fibroblast-like cells. Similar cells may be formed from animal cells, provided they are induced either by vegetal cells or by Li+. We have found that lactate and various inhibitors of RNA synthesis suppress the spontaneous cell differentiation. The effect of lactate differs from that of the other agents in so far as lactate must be present before the second day of culture to suppress the outgrowth of flbroblasts on the third day; the other inhibitors are active also when added on the second day. An explanation of this difference may possibly be found in the fact that lactate suppresses incorporation of RNA but only by 40%. The effect on the differentiation of various substances supposed to interfere with the metabolism of lactate was established. The results obtained were suggestive, but not conclusive. It is concluded that the effect of anaerobiosis may be explained as a lactate inhibition. The amounts of lactate under aerobic conditions are so slight that it is unlikely, but not impossible, that lactate is directly involved in the control of differentiation.

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