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.     

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.     

Fine structural and enzyme histochemical observations on the dorsal tail tubercle of Mertensiella caucasica (Urodela,Amphibia)

Summary Dorsal tubercle and skin of Mertensiella caucasica have been investigated with the electron microscope and enzyme histochemical methods. The epidermis of the tubercle consists of 8–9 cell layers, that of normal dorsal skin of 5–6. The tubercle is filled with large mucous glands which are surrounded by an almost complete layer of smooth muscle cells (myoepithelial cells). Their glandular cells undergo cyclical changes and are characterized by specific secretory granules, which differ from those of the relatively small mucous glands of the normal dorsal skin.In the connective tissue of the tubercle a relatively rich supply of nerve fibres has been found, which in part contain synaptic and dense core vesicles or accumulations of mitochondria. In the normal dorsal skin nerve fibres occur less frequently.The following enzymes have been demonstrated in the mucous glands of the tubercle: SDH, acid phosphatase, unspecific esterases, E 600 resistant esterase.The tubercle seems to stimulate the female cloaca chemically and mechanically.     

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.     

Beiträge zur funktionellen Morphologie der Neurohypophyse

Zusammenfassung Beidseitige Adrenalektomie und Hypophysektomie führen bei der Ratte zu gleichartigen histologischen Veränderungen in der Zona externa infundibuli. In beiden Fällen treten in der normalerweise weitgehend goniorinegativen Zona externa infundibuli große Mengen gomoripositiver Granula auf. Sie scheinen Fasern anzugehören, die senkrecht zur Längsachse des Infundibulum verlaufen.Die Befunde werden als weiterer Hinweis dafür betrachtet, daß die gomoripositiven Substanzen der Zona externa infundibuli eine Bedeutung für die Steuerung der Nebennierenrindenfunktion haben.

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Studies on the functional morphology of the neurohypophysisII. Comparison of histological changes in the median eminence of the rat after bilateral adrenalectomy and hypophysectomy

Summary Bilateral adrenalectomy and hypophysectomy in the rat produce similar histological changes in the outer layer of the median eminence. In both cases, abundant gomoripositive granules are observed in the outer layer, which normally reacts gomorinegative. The gomoripositive granules seem to belong to fibres running vertically through the infundibulum.These findings are regarded as a further indication, that the gomoripositive substances of the outer layer of the median eminence play a significant role in controlling adrenocortical function.

     

Energetics of the budding cycle of Saccharomyces cerevisiae during glucose limited aerobic growth

Summary A method for the estimation of the yield on energy (Y _ATP) and of the efficiency of oxidative phosphorylation, in vivo (P/O ratio) is described, which is based on the measurement of effective gas exchange values ( and ) and of the yield coefficient Y of continuously growing populations of baker's yeast which vary in the degree of fermentation and respiration. For Y _ATP a value of 12.0±0.5 and for P/O ratio one of 1.1±0.05 was found and seems to be independent of the type of glucose catabolism (under glucose limitation).The gas exchange of populations of Saccharomyces cerevisiae synchronized at different growth rates was determined. The specific oxygen uptake and carbon dioxide formation rate, Q _{O 2}, and Q _{CO 2}, are shown to depend on the state of the cells in the budding cycle. Increase in gas metabolism and therefore increased energy generation coincides with the initiation of budding. The longer the generation time g the more expressed are these oscillations of energy formation over the budding cycle. The relationship between the course of energy generation and energy storage and the sequence of budding and single cell phase over the division cycle is discussed.