Maternal effects and temperature-sensitive period of mutations affecting embryogenesis in Caenorhabditis elegans

We have used standard tests to investigate the nature of gene expression of a new set of temperature-sensitive mutants defining 30 emb genes (essential for embryogenesis) in the nematode Caenorhabditis elegans. The mode of gene expression as determined by progeny tests for parental effects divides the genes into four classes. For 18 genes maternal gene expression is necessary and sufficient for normal embryogenesis; for 2 genes zygotic expression is necessary and sufficient; for 7 genes either maternal or zygotic expression is sufficient; for 3 genes both maternal and zygotic expression are necessary. One mutant displayed partial paternal sufficiency. The results of temperature-shift experiments define two “execution stages,” corresponding to the limits of the temperature-sensitive period (TSP), and indicate the nature and the time of action or synthesis of the gene products. Most of the maternally expressed genes have very early execution stages indicating translation before fertilization, but some are temperature sensitive late in embryogenesis. Early execution stages for 2 zygotically necessary genes demonstrate that the zygotic genome can be active in the earliest stages of embryogenesis. All taken together, the mode of gene expression, TSP, and arrest stage (terminal phenotype) allow us to classify functionally and begin to order the genes essential for embryogenesis. The results indicate a preeminent role for maternal genes and gene products in embryogenesis, in agreement with the results of others.     

Molecular forms of beta-hexosaminidase and cathepsin D in serum and urine of healthy subjects and patients with elevated activity of lysosomal enzymes.

A procedure is described that allows the characterization of the molecular forms of beta-hexosaminidase and cathepsin D in controls and pathological specimens of human serum and human urine. The following observations were made. (1) In human serum, beta-hexosaminidase (alpha- and beta-chain) and cathepsin D are present predominantly in their high-molecular-weight precursor forms. In human urine, these enzymes exist as both precursor and mature forms. (2) Cathepsin D precursor from serum and urine differs in the number of oligosaccharides that are sensitive to endo-beta-N-acetylglucosaminidase H. Therefore the urine enzyme is not likely to originate from the serum. (3) The presence exclusively of precursors of beta-hexosaminidase and of cathepsin D in the sera of patients with hepatitis suggests that in hepatitis secretion of lysosomal enzymes is elevated, rather than the enzymes leaking from damaged cells. (4) In the urine of patients with nephrotic syndrome, beta-hexosaminidase and cathepsin D are present in grossly elevated amounts, but do not differ in the polypeptide patterns from controls. (5) In urine from a patient with mucolipidosis II, the elevated activity of beta-hexosaminidase is accounted for mainly by the precursor forms. Mature beta-chain of beta-hexosaminidase is lacking, and incompletely processed beta-hexosaminidase polypeptides are present. Both the precursor and the mature forms of cathepsin D are increased. They contain only complex oligosaccharides.     

Stoffwechsel-Regulation aerober Zellsuspensionen vonSaccharomyces carlsbergensis nach Glucosezugabe

Zusammenfassung Wird eine ausgehungerte aerobe Zellsuspension vonSaccharomyces carlsbergensis mit Glucose gefüttert, dann ist eine deutliche Stimulierung des O₂-Verbrauchs zu registrieren. Mit Hilfe verschiedener Meßmethoden wurde der Verlauf dieser nicht-linearen O₂-Abnahme analysiert und mit den gleichzeitig auftretenden Konzentrationsänderungen einiger glykolytischer Metabolite korreliert.Dabei zeigt sich, daß ca. 20–60 Sekunden nach Glucosezugabe die Rate des O₂-Verbrauchs abnimmt und gleichzeitig eine deutliche Äthanol-Synthese einsetzt, obgleich der O₂-Partialdruck zu diesem Zeitpunkt noch etwa halbmaximal ist.

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Metabolite-regulation of aerobic cell-suspension ofSaccharomyces carlsbergensis after feeding with glucose. I. Shift from respiration to aerobic fermentation

Summary After feeding with glucose, an aerobic starved cell-suspension ofSaccharomyces carlsbergensis shows an increasing of oxygen consumption. This stimulation is not linear during the transition from high to low oxygen-level.For this aerobic phase the regulated fluxes of some metabolites are analyzed. It could be shown that with highest oxygen consumption an ethanol synthesis is starting.

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Herrn Prof. Dr.A. Betz danke ich an dieser Stelle für viele wertvolle Hinweise zur Interpretation der hier beschriebenen Ergebnisse. Die gewissenhafte technische Assistenz erfolgte durch FrauR. Hinrichs. Die Durchführung dieser Arbeit wurde durch Sachbeihilfen der Stiftung Volkswagenwerk und der Deutschen Forschungsgemeinschaft ermöglicht.     

Behavioral responses to linear accelerations in blind goldfish

Blind goldfish were subjected to linear accelerations on a motor car and on a parallel swing. Moyements of the fish in a tank during the accelerations were recorded with a movie camera. During the horizontal acceleration, the fish aligns his longitudinal axis in a plane perpendicular to the direction of an apparent gravity with the fish's back pointing away from the direction of this apparent gravity vector. This is similar to the manner in which the fish usually aligns himself horizontally in response to the vertically downward terrestrial gravity and can therefore be termed gravity reference response. It is concluded that blind goldfish cannot distinguish between otolith displacements caused by passive tilts and equivalent otolith displacements caused by moderate inertial forces during rectilinear acceleration. With a horizontal jerk of higher magnitude, two additional responses can occur: horizontal 180° turns following tailward jerks and straight forward darting following noseward jerks.This work was supported by NASA Grant No. NGR 23-005-201.     

A fluorescence microscope attachment for flow-through cytofluorometry

A flow-through system for rapid automated analysis of intracellular fluorescence parameters is described. In combination with commercially available instrumentation for fluorescence microscopy, fluorometry and pulse height analysis, the hydrodynamic focusing flow-through principle can be successfully applied. The specific advantages and disadvantages of this principle compared with the mechanical focusing system are discussed.     

In vitro incorporation of 2′-deoxyadenosine and 3′-deoxyadenosine into yeast tRNAPhe using tRNA nucleotidyl transferase,and properties of tRNAPhe-C-C-2′dA and tRNAPhe-C-C-3′dA

2′-Deoxyadenosine and 3′-deoxyadenosine (cordycepin) can be incorporated into the 3′-terminal position of tRNA^Phe by tRNA nucleotidyl transferase. tRNA^Phe-C-C-2′dA and tRNA^Phe-C-C-3′dA, missing the cis-diol group at the 3′-terminal end are resistant to periodate oxidation and are not able to form borate complexes. In aminoacylation experiments only the tRNA^Phe-C-C-3′dA proved to be chargeable.     

ACTIVATION IN VITRO OF RAT LIVER POLYRIBOSOMES

The increase in the incorporation of amino acids into protein in vitro by preparations obtained from protein-fed rats as compared with preparations obtained from carbohydrate-fed rats has been described previously. After molecular sieving through Sephadex G-25 of cell-free preparations, the difference in incorporating activity between the two types of rats was diminished in systems containing ATP, phosphoenolpyruvate, pyruvate kinase, GTP, and a mixture of amino acids. When, after molecular sieving, a mitochondrial (15,000 g) supernatant was incubated for 4 min at 35°C the polysomal pattern of the preparations was unchanged. In the presence of ATP, phosphoenolpyruvate, and pyruvate kinase the polysomal incorporating activity was low and the polysomal pattern was only slightly changed. Addition of GTP increased the activity markedly, and a more pronounced activity was observed when a mixture of amino acids was added as well. As the amino acid incorporation ability increased, monosomes were formed from the polyribosomes. The activity of the polyribosomes was severalfold higher than that of non-Sephadex-treated preparations, indicating an activation of polysomal aggregates which under the usually applied conditions of incubation and prior to molecular sieving show little or insignificant activity. It was possible to activate polyribosomes from carbohydrate-fed and protein-fed rats to almost the same extent.