The reduction of genic activity in the tetraploid amphibianOdontophrynus americanus is not due to loss of ribosomal DNA

Summary Genic activity in tetraploid members of the amphibian speciesOdontophrymus americanus is reduced to that of diploid ones. Loss of ribosomal genes, a mechanism suggested by others as a means of decreasing genetic activity, could be ruled out. The diploids and the tetraploids have almost identical proportions of their genomes complementary to (28s+18s) ribosomal RNA.     

Nucleic acid content of a diploid and of a triploid strain ofDrosophila melanogaster

Zusammenfassung Beim triploidenDrosophila-StammFM4, y ^31d sc ⁸ dm B/y ² sc w ^a ec.=ist der DNS-Anteil an der fettfreien Trockenmasse wesentlich höher als beim diploiden Stamm «Berlin normal ». Der RNS-Anteil an der fettfreien Trockenmasse stimmt in beiden Stämmen überein. Es wird diskutiert, dass die 2 Genome der diploidenDrosophila offensichtlich etwa ebenso aktiv sind wie die 3 Genome der triploiden.Drosophila verfügt also offenbar über einen Regulationsmechanismus, der die RNS-Konzentration trotz unterschiedlichen DNS-Gehalts konstant hält.     

Plasma estrogens in Pleurodeles waltlii. Comparison between diploid and triploid females]

Estrogens have been examined in the plasma of diploid and triploid newts Pleurodeles waltlii. Estradiol-17 beta (E2) and estrone (E1) were determined by radioimmunoassay, before and after enzymatic hydrolysis of the conjugates. Total (t) and unconjugated (u) E2 levels were positively correlated (E2u = 0.478 35 E2t + 0.579 98; r = 0.883), but no correlation was detected between E1 levels. No statistical difference was found for the estrogen levels between the different experimental lots of diploid newts (E2t = 7.5 +/- 0.37 ng/ml, E2u = 4.3 +/- 0.20 ng/ml, E1t = 2.19 +/- 0.08 ng/ml, E1t = 0.41 +/- 0.02 ng/ml) but every estrogen level was lower in the triploid group (E2t = 1.8 +/- 0.60, E2u = 1.0 +/- 0.18, E1t = 1.4 +/- 0.13, E1u = 0.3 +/- 0.04 ng/ml). This difference is discussed in relation to lower fertility of the triploid females.     

Sterols of the lobster (Homarus americanus) and the shrimp (Pandalus borealis).

In this study we have analyzed the sterol compositions of two continental shelf species of crustacea, the lobster (Homarus americanus) and the shrimp (Pandalus borealis). Cholesterol was found to be the most abundant sterol in these two species with smaller amounts of desmosterol, 24-methylcholesterol, 24-ethylcholesterol, 24-methylenecholesterol and 22-dehydrocholesterol.     

Sterols of the lobster (Homarus americanus) and the shrimp (Pandalus borealis)

Summary In this study we have analyzed the sterol compositions of two continental shelf species of crustacea, the lobster (Homarus americanus) and the shrimp (Pandalus borealis). Cholesterol was found to be the most abundant sterol in these two species with smaller amounts of desmosterol, 24-methylcholesterol, 24-ethylcholesterol, 24-methylenecholesterol and 22-dehydrocholesterol. Woods Hole Oceanographic Institution Contribution Number 3494. This work was supported by the Office of Sea Grant of the National Oceanic and Atmospheric Administration, U.S. Department of Commerce. Special thanks are extended to Ms.R. Beebe-Center, who was responsible for a large part of the isolation work described here.     

Cell fusion as a mechanism for the origin of polyploid cells in vitro

Zusammenfassung In Kulturen vonPeromyscus maniculatus und inMuntiacus muntjak wurden Tetraploidzellen gefunden, die als Produkte von Zellfusionen aufgefasst werden. Es wird angenommen, dass die ursprünglichen diploiden Elemente sich im Zeitpunkt der Fusion in verschiedenen Phasen des Zellzyklus befunden haben.

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Supported in part by NIH fellowship No. 1-F02-CA-42, 531-02 from the National Cancer Institute, USPHS grant No. GM-15361, and Grant No. E 286 from the American Cancer Society.     

Statistical analysis of the relation between the length of the genoma and the diploid number of the chromosomes inCercopithecus

Riassunto Utilizzando metodiche statistiche è stato analizzato l'incremento della lunghezza totale del genoma rispetto al numero dei cromosomi in piastre a diversa ploidia nel genereCercopithecus. È stato riscontrato che la relazione numero dei cromosomi e lunghezza del genoma è significativamente lineare. È supposto un meccanismo adittivo per interpretare l'incremento del numero dei cromosomi.     

Effects of ethidium bromide in diploid and duplication strains of Aspergillus nidulans

Summary Unstable duplication and diploid strains of Aspergillus nidulans were treated with ethidium bromide, and it was shown that this drug reduces the number of sectors produced by such strains. The mechanisms which could be responsible for the partial stabilization of the strains are discussed and it is suggested that a similar mechanism is responsible for the production of sectors in both strains. It is also suggested that ethidium bromide could be useful for the reduction of instability of industrial strains.Acknowledgment. The authors are thankful to the National Council for the Development of Science and Technology (CNPq) for financial assistance.     

Mammalian arylsulfatases A and B: relative rates of hydrolysis of artificial substrates

Summary Rodent and bovine arylsulfatase B hydrolyze 4-methylumbelliferyl sulfate (4MUS) 10- to 30-fold more efficiently than arylsulfatase A. Therefore, 4MUS grossly underestimates arylsulfatase A activity in the presence of excess arylsulfatase B.     

Mammalian arylsulfatases A and B: relative rates of hydrolysis of artificial substrates

Rodent and bovine arylsulfatase B hydrolyze 4-methylumbelliferyl sulfate (4MUS) 10- to 30-fold more efficiently than arylsulfatase A. Therefore, 4MUS grossly underestimates arylsulfatase A activity in the presence of excess arylsulfatase B.