scholarly journals DOSAGE COMPENSATION OF GENES ON THE LEFT AND RIGHT ARMS OF THE X CHROMOSOME OF DROSOPHILA PSEUDOOBSCURA AND DROSOPHILA WILLISTONI

Genetics ◽  
1974 ◽  
Vol 78 (4) ◽  
pp. 1119-1126
Author(s):  
Irene Abraham ◽  
John C Lucchesi

ABSTRACT We have investigated the occurrence of dosage compensation in D. willistoni and D. pseudoobscura, two species whose X chromosome is metacentric with one arm homologous to the X and the other homologous to the left arm of chromosome 3 of D. melanogaster. Crude extracts were assayed for isocitrate dehydrogenase (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?), and α-glycerophosphate dehydrogenase (chromosome 2) in D. willistoni, and for esterase-5 (XR), glucose-6-phosphate dehydrogenase (XL?), 6-phosphogluconate dehydrogenase (XL?) and amylase (chromosome 3) in D. pseudoobscura. Our results indicate that a mechanism for dosage compensation is operative in both arms of the X chromosome of these two species.

Genetics ◽  
1981 ◽  
Vol 99 (1) ◽  
pp. 127-150
Author(s):  
C C Laurie-Ahlberg ◽  
J H Williamson ◽  
B J Cochrane ◽  
A N Wilton ◽  
F I Chasalow

ABSTRACT Isogenic lines, in which chromosomes sampled from natural populations of D. melanogaster are substituted into a common genetic background, were used to detect and partially characterize autosomal factors that affect the activities of the two pentose phosphate pathway enzymes, glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD). The chromosome 3 effects on G6PD and 6PGD are clearly correlated; the chromosome 2 effects, which are not so great, also appear to be correlated, but the evidence in this case is not so strong. Examination of activity variation of ten other enzymes revealed that G6PD and 6PGD are not the only pair of enzymes showing a high positive correlation, but it is among the highest in both sets of lines. In addition, there was some evidence that the factor(s) affecting G6PD and 6PGD may also affect two other metabolically related enzymes, transaldolase and phosphoglucose isomerase.—Rocket immunoelectrophoresis was used to estimate specific CRM levels for three of the enzymes studied: G6PD, 6PGD and ME. This experiment shows that a large part of the activity variation is accounted for by variation in CRM level (especially for chromosome 3 lines), but there remains a significant fraction of the genetic component of activity variation that is not explained by CRM level.—These results suggest that the autosomal factors are modifiers involved in regulation of the expression of the X-linked structural genes for G6PD and 6PGD, but a role in determining part of the enzymes′ primary structure cannot be excluded with the present evidence.


Genetics ◽  
1996 ◽  
Vol 143 (4) ◽  
pp. 1739-1752 ◽  
Author(s):  
Xavier Montagutelli ◽  
Rowena Turner ◽  
Joseph H Nadeau

Abstract Strong deviation of allele frequencies from Mendelian inheritance favoring Mus spretus-derived alleles has been described previously for X-linked loci in four mouse interspecific crosses. We reanalyzed data for three of these crosses focusing on the location of the gene(s) controlling deviation on the X chromosome and the genetic basis for incomplete deviation. At least two loci control deviation on the X chromosome, one near Xist (the candidate gene controlling X inactivation) and the other more centromerically located. In all three crosses, strong epistasis was found between loci near Xist and marker loci on the central portion of chromosome 2. The mechanism for this deviation from Mendelian expectations is not yet known but it is probably based on lethality of embryos carrying particular combinations of alleles rather than true segregation distortion during oogenesis in F1 hybrid females.


Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 138-146 ◽  
Author(s):  
P. E. Kaiser ◽  
J. A. Seawright ◽  
B. K. Birky

Ovarian polytene chromosomes from eight populations of Anopheles quadrimaculatus in the southeastern United States were observed for chromosomal polymorphisms. Two sibling species, species A and B, each with intraspecific inversions, were distinguished. Species A correlates with the previously published standard maps for salivary gland and ovarian nurse-cell polytene chromosomes. Species A was found at all eight collection sites, and five of these populations also contained species B. Three inversions on the right arm of chromosome 3 were observed in species A. Species B contained a fixed inversion on the X chromosome, one fixed and one floating inversion on the left arm of chromosome 2, and one fixed and one floating inversion on the right arm of chromosome 3. The fixed inversion on the X chromosome makes this the best diagnostic chromosome for distinguishing species A and B. An unusual dimorphism in the left arm of chromosome 3, found in both species A and B, contained two inversions. The heterokaryotypes, as well as two distinct homokaryotypes, were seen in all of the field populations. Intraspecific clinal variations in the frequencies of the species A inversions were noted. The Florida populations were practically devoid of inversions, the Georgia and Alabama populations contained some inversions, and the Arkansas population was mostly homozygous for two of the inversions. The phylogenetic relationships of species A and B to the Maculipennis complex (Nearctic) are discussed.Key words: Anopheles, inversion, populations, chromosome polymorphism, phylogenetics.


Development ◽  
1995 ◽  
Vol 121 (10) ◽  
pp. 3245-3258 ◽  
Author(s):  
G.J. Bashaw ◽  
B.S. Baker

In Drosophila dosage compensation increases the rate of transcription of the male's X chromosome and depends on four autosomal male-specific lethal genes. We have cloned the msl-2 gene and shown that MSL-2 protein is co-localized with the other three MSL proteins at hundreds of sites along the male polytene X chromosome and that this binding requires the other three MSL proteins. msl-2 encodes a protein with a putative DNA-binding domain: the RING finger. MSL-2 protein is not produced in females and sequences in both the 5′ and 3′ UTRs are important for this sex-specific regulation. Furthermore, msl-2 pre-mRNA is alternatively spliced in a Sex-lethal-dependent fashion in its 5′ UTR.


Genetics ◽  
1997 ◽  
Vol 145 (3) ◽  
pp. 729-736
Author(s):  
Irina Arkhipova ◽  
Jingjing Li ◽  
Matthew Meselson

A procedure is described for determining the mode and magnitude of gene-dosage compensation of transformed genes. It involves measurement of the ratio of the activity of a gene inserted at X-linked sites to the activity of the same gene inserted at autosomal sites. Applying the procedure to the Drosophila pseudoobscura Hsp82 gene inserted at ectopic sites in D. melanogaster and taking gene activity as proportional to the amount of transcript per gene copy, we conclude that (1) in both adults and larvae the gene is not compensated at autosomal sites or at a site in β-heterochromatin at the base of the X chromosome and is fully compensated at euchromatic X-chromosomal sites; (2) inappropriate normalization is responsible for a claim that the gene is compensated at autosomal sites; and (3) the observed compensation operates mainly or entirely by heightened activity of X-linked genes in males, rather than by reduced activity in females.


2013 ◽  
Vol 31 (3) ◽  
pp. 614-624 ◽  
Author(s):  
Masafumi Nozawa ◽  
Nana Fukuda ◽  
Kazuho Ikeo ◽  
Takashi Gojobori

1969 ◽  
Vol 14 (2) ◽  
pp. 137-150 ◽  
Author(s):  
S. C. Lakhotia ◽  
A. S. Mukherjee

Morphology and the rate of RNA synthesis of the X-chromosome in XX/XO mosaic larval salivary glands of Drosophila melanogaster have been examined. For this purpose the unstable ring-X was utilized to produce XX and XO nuclei in the same pair of glands. The width of the X-chromosome and the left arm of the 3rd chromosome (3L) of larval salivary glands was measured and the rate of RNA synthesis by them was studied upon the use of [3H]uridine autoradiography in such XX (female) and XO (male) nuclei developing in a female background (i.e. otherwise genotypically XX). In such mosaic glands the width of the single X-chromosome of male nuclei is nearly as great as that of the paired two X's of female nuclei, as is also the case in normal male (X Y) and female (XX). The single X of male nuclei synthesizes RNA at a rate equal to that of the paired two X's of female nuclei and nearly twice that of an unpaired X of XX nuclei. Neither the developmental physiology of the sex nor the proportion of XO nuclei in a pair of mosaic salivary glands of an XX larva has any influence on these two characteristics of the male X-chromosome.It is suggested that dosage compensation in Drosophila is achieved chiefly, if not fully, by a hyperactivity of the male X, in contrast to the single X inactivation in female mammals, that this hyperactivity of the male X is expressed visibly in the morphology and metabolic activity of the X-chromosome in the larval salivary glands of the male, and that this hyperactivity and therefore dosage compensation in Drosophila in general is not dependent on sex-differentiation, but is a function of the doses of the X-chromosome itself.


Genetics ◽  
1980 ◽  
Vol 96 (3) ◽  
pp. 727-741
Author(s):  
R A Norman ◽  
Satya Prakash

ABSTRACT Efforts were made to discriminate new genetic variants among electrophoretic alleles that are associated with chromosome 3 inversions of Drosophila pseudoobscura and D. persimilis. Apparent genetic similarities for electrophoretic alleles between these two species and among the common inversions they carry were reexamined by altering gel concentration and buffer pH. At the amylase locus, the 1.09 electrophoretic allele could be further separated into two allelic classes that differentiated the WT and KL arrangements. Similarly, the 0.84 electrophoretic allele was divided into two allelic classes, one characteristic of the Santa Cruz phylad arrangements, TL and SC, and the other found in strains of the Standard phylad arrangements and CH. Uncommon amylase alleles proved to be different alleles in the two species. No new allelic variants, however, could be found among strains with the amylase 1.00 allele, the commonest allele in the Standard phylad of both species. No major new allelic variation was detected for acid phosphatase-3 and larval protein-10 that revealed any further differentiation among species or inversions. Variation at all three loci in strains of the Bogota population remained genetically similar to variation in strains of mainland D. pseudoobscura.


1960 ◽  
Vol 38 (1) ◽  
pp. 1449-1456 ◽  
Author(s):  
J. S. Willmer

Adrenalectomy caused a decrease in the hepatic levels of glucose-6-phosphatase and glucose-6-phosphate dehydrogenase. Restoration to normal levels in rats which had been fasted for 18 hours was obtained by treatment with cortisone or corticosterone. In fed animals hydrocortisone and progesterone were also capable of maintaining an elevated level of glucose-6-phosphatase. Cortisone and corticosterone raised the level of this enzyme in fed sham-operated animals, but none of the other steroids showed this effect. The activity of 6-phos-phogluconate dehydrogenase did not change significantly under the influence of adrenalectomy or individual steroid hormones.A comparison is made between the effects of adrenalectomy and starvation upon the level of these enzymes in the liver during a 7-day period.


1989 ◽  
Vol 67 (4) ◽  
pp. 869-871 ◽  
Author(s):  
R. H. Gooding

In hybrid females of Glossina morsitans morsitans Westwood and Glossina morsitans centralis Machado that carried four well-separated marker genes, suppression of intrachromosomal recombination occurred between the loci for glucose-6-phosphate dehydrogenase (G6pd) and arginine phosphokinase (Apk) on the X chromosome. Fertility of backcross females was not influenced by whether they mated with G. m. morsitans or G. m. centralis, but it was higher in females that received both of their X chromosomes from G. m. morsitans than it was in females that received one X chromosome from G. m. morsitans and the other from G. m. centralis.


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