Showing papers by "University of Göttingen published in 1982"
TL;DR: It is shown that the result known as Wahlund's principle can be expressed as a simple function of genic distances among the subpopulations, and if used with caution it can be employed to recognize mixtures of seed lots.
Abstract: An excess proportion of homozygous carriers of a gene arises on bulking of reproductively isolated subpopulations. This surplus of homozygotes in the mixture, measured relative to the panmictic proportion, is caused by variation of its frequencies in the respective subpopulations. It is shown that the result known as Wahlund's principle can be expressed as a simple function of genic distances among the subpopulations. If used with caution it can be employed to recognize mixtures of seed lots. The effect of bulking can be readily discriminated from that of inbreeding. It may also be distinguished from the effect of assortative mating by analysing such distances at several gene loci. Various effects of selection may disturb inference on whether a given lot is a mixture. Hence application should be confined to the dormant seed. Isozyme loci are most suitable for such checks since complete dominance occurs only rarely. Some advantages peculiar to conifer seed are discussed.
1,373 citations
TL;DR: Cardiac myocytes isolated from adult rats can be kept in culture with physiological calcium concentrations up to four days, and over this time cardiocytes preserve their normal ultrastructure.
291 citations
TL;DR: Differences in the course of alkaline denaturation indicate that only a fraction of strain-specific proteinases is capable to convey long-range effects in the host, suggesting a role of the secretory proteinases in the persistence of yeasts on mucous membranes.
Abstract: Randomly selected strains of Candida albicans were grown with bovine serum albumin (BSA) as a single nitrogen source. From all strains tested, culture supernatant contained carboxyl proteinase (E.C.3.4.23) as has been shown that with hemoglobin as a substrate and by specific inhibition with pepstatin-A. According to the separation pattern of BSA fragments, secretory proteinases from C. albicans belong to at least three groups. We have purified the partially proteolytic enzyme of strain 113 and have compared its properties with those of the totally proteolytic enzyme of strain CBS 2730. Both enzymes have virtually identical molecular weight (ca. 44,000) and cross-react immunologically; they differ in pH optimum, isoelectric point, substrate specificity, and resistance against alkali. IgG1, which is the prevalent immunoglobulin of human serum, was not cleaved by enzyme 113. Immunoglobulins A1, A2 and secretory component were cleaved by both enzymes, which points to a role of the secretory proteinases in the persistence of yeasts on mucous membranes. Differences in the course of alkaline denaturation indicate that only a fraction of strain-specific proteinases is capable to convey long-range effects in the host.
240 citations
TL;DR: Changes in the level of methylation of this sequence in different tissues of human males can be detected with the lowest levels found in sperm and placental DNA.
Abstract: The human Y chromosome carries 2000 copies of a tandemly repeated sequence, 2.47 kb long, which constitutes about 20% of the DNA of this chromosome. These sequences are localised on the tip of the long arm of the Y chromosome. Related sequences are present in DNA of females with a related but distinguishable restriction pattern. These autosomal sequences are distributed in tandem arrays on a number of autosomes. Related sequences are also present in gorilla and chimpanzee. In gorilla they resemble the human sequences in their restriction map but are not found on the Y chromosome whereas in chimpanzee the related sequences behave as a ‘dispersed’ repeat. Changes in the level of methylation of this sequence in different tissues of human males can be detected with the lowest levels found in sperm and placental DNA.
240 citations
01 Mar 1982
TL;DR: When Clostridium acetobutylicum was grown in continuous culture under glucose limitation at neutral pH and varying dilution rates the only fermentation products formed were acetate, butyrate, carbon dioxide and molecular hydrogen.
Abstract: When Clostridium acetobutylicum was grown in continuous culture under glucose limitation at neutral pH and varying dilution rates the only fermentation products formed were acetate, butyrate, carbon dioxide and molecular hydrogen. The Y
glucose
max
and (Y
ATP
max
)
gluc
exp
values were 48.3 and 23.8 dry weight/mol, respectively. Acetone and butanol were produced when the pH was decreased below 5.0 (optimum at pH 4.3). The addition of butyric acid (20 to 80 mM) to the medium with a pH of 4.3 resulted in a shift of the fermentation from acid, to solvent formation.
240 citations
01 Dec 1982
TL;DR: When Clostridium acetobutylicum was grown in continuous culture under phosphate limitation, glucose was fermented to butanol, acetone and ethanol as the major products, and on the basis of these results a two-stage continuous process was developed in which 87.5% of the glucose was converted into butanol and acetone.
Abstract: When Clostridium acetobutylicum was grown in continuous culture under phosphate limitation (0.74 mM) at a pH of 4.3, glucose was fermented to butanol, acetone and ethanol as the major products. At a dilution rate of D=0.025 h−1 and a glucose concentration of 300 mM, the maximal butanol and acetone concentrations were 130 mM and 74 mM, respectively. 20% of the glucose remained in the medium. On the basis of these results a two-stage continuous process was developed in which 87.5% of the glucose was converted into butanol, acetone and ethanol. The cells and minor amounts of acetate and butyrate accounted for the remaining 12.5% of the substrate. The first stage was run at D=0.125 h−1 and 37° C and the second stage at D=0.04 h−1 and 33° C. High yields of butanol and acetone were also obtained in batch culture under phosphate limitation.
188 citations
TL;DR: Out of the 101 common species studied, 28 have decreased, chiefly because oyster beds, Sabellaria reefs and a subtidal seagrass bed disappeared, and almost all losses occurred in the subtidal region.
172 citations
01 Dec 1982
TL;DR: The Ramfjordmoen heating facility at Tromso, Norway is briefly described in this article, and a survey is given of the experiments performed with this facility until now.
Abstract: The heating facility at Ramfjordmoen near Tromso, Norway, is briefly described, and a survey is given of the experiments performed with this facility until now. These experiments comprise D -region modification, polar electrojet modulation at VLF, ELF and ULF, HF absorption and backscatter due to short-scale field-aligned irregularities, stimulated radio wave emission of the modified ionospheric plasma, short-time scale HF absorption due to the parametric decay instability, airglow modification, excitation of large-scale irregularities, and F -region cross modulation.
167 citations
TL;DR: In contrast to 3-methylcholanthrene-type inducers, ethoxyquin and trans-stilbene oxide markedly induced GT1 reactions without affecting benzo[a]pyrene monooxygenase.
166 citations
TL;DR: In this paper, a calcite-depositing stream in the Pyrenees, south France, enabled the authors to study the equilibration of major components and carbon and oxygen isotopes during the formation of calcite and the degassing of CO2, and to examine the possible influence of aquatic flora on these processes.
TL;DR: The results show that the asynchronous activity of motor units and the distribution of their filtering and firing properties at various levels of muscle contraction are esponsible, at least partially, for the main features of the muscle force waveform, including tremor.
Abstract: A population stochastic model based on the differing properties and the independent activation of motor units is used to describe the production of force in the contracting skeletal muscle. Detailed force predictions of the model concerning a hand muscle are obtained by computer simulation. General features of the force signal are established analyticaly on the basis of the general properties of the neuromuscular system which the population model takes into account. The results show that the asynchronous activity of motor units and the distribution of their filtering and firing properties at various levels of muscle contraction are esponsible, at least partially, for the main features of the muscle force waveform, including tremor.
TL;DR: Using deep level transient spectroscopy (DLTS) the defects introduced into silicon by plastic deformation are investigated with respect to their capture and emission characteristics as discussed by the authors, in agreement with what has been found by electron spin resonance (EPR).
Abstract: Using deep level transient spectroscopy (DLTS) the defects introduced into silicon by plastic deformation are investigated with respect to their capture and emission characteristics. In agreement with what has been found by electron spin resonance (EPR), kind and density of the detected localized states strongly change with deformation temperature and during anneal around 0.6 Tm (Tm melting temperature). While part of this effect can be certainly explained by anneal out of point defects, there must be a structural change in the core region of the dislocation, since the dislocation density remains unchanged during anneal.
Die Defekte, die in Silizium durch plastische Verformung entstehen, wurden mit Hilfe einer Kapazitatsspektroskopie (DLTS) bezuglich ihrer Einfangs- und Emissionscharakteristik untersucht. In Ubereinstimmung mit den Ergebnissen der Elektronenspinresonanz (EPR) andern sich Art und Dichte der nachgewiesenen lokalisierten Zustande mit der Verformungstemperatur und wahrend des Ausheilens bei etwa 0,6 Tm (Tm Schmelztemperatur). Wahrend ein Teil dieses Effekts sicherlich auf das Ausheilen von Punktdefekten zuruckzufuhren ist, mus es auch eine strukturelle Anderung im Gebiet des Versetzungskernes geben, da die Versetzungsdichte durch die Gluhung nicht geandert wird.
TL;DR: An atom probe field ion microscope was applied to analyse the chemical inhomogeniety on an atomic scale as it exists after quenching and as it develops on annealing in the metallic glass Fe40Ni40B20.
01 Dec 1982
TL;DR: The subtidal fauna of the Wadden Sea proved to be vulnerable to human disturbance; thus, the present community can no longer be viewed as the outcome of entirely natural processes.
Abstract: During the years 1923–1926 Hagmeier & Kandler (1927) sampled the macrofauna of subtidal shallows and channels of the Wadden Sea close to the Island of Sylt (German Bight, North Sea) Reinvestigating this study area in 1980, a substantially altered faunal composition was recorded An approach is made to quantify the comparison in terms of abundance, species richness and diversity of invertebrate taxa Human interference is assumed to be responsible for the major changes Natural oyster beds have been overexploited and the local population ofOstrea edulis has been driven to extinction Subsequently, mussels(Mytilus edulis) spread in the entire region, promoted by shell fishery Particularly barnacles and many polychaetes took advantage of the expansion of mussel banks which is substantiated by correlation analysis Reefs of the colonial polychaeteSabellaria spinulosa stood in the way of shrimp trawling and became destroyed together with the associated fauna A subtidalZostera marina bed was wiped out in 1934 by a natural epidemic disease but never succeeded in reestablishing itself The associated fauna disappeared Large epibenthic predators and scavengers (crabs, snails and starfish) survived all these changes The total number of species remained approximately at the same level but molluscs experienced losses and polychaetes diversified Overall abundance increased with a disproportionately large share of a few species(Mytilus edulis, Balanus crenatus, Cerastoderma edule, Scoloplos armiger) The subtidal fauna of the Wadden Sea proved to be vulnerable to human disturbance; thus, the present community can no longer be viewed as the outcome of entirely natural processes
TL;DR: Archean calcites and dolomites, if compared to their Phanerozoic counterparts, are enriched in Sr2+, Ba2+, Mn2+, Fe2+, depleted in 18O, (Na+), and contain mantle-like 87Sr/86Sr as mentioned in this paper.
Abstract: Archean calcites and dolomites, if compared to their Phanerozoic counterparts, are enriched in Sr2+, Ba2+, Mn2+, Fe2+, depleted in 18O, (Na+), and contain mantle-like 87Sr/86Sr and, in associated S phases, mantle-like 34S/32S. This may be a consequence of massive seawater pumping through, and equilibration with, the coeval basaltic oceanic crust. The exponential decline of oceanic geothermal gradient in the course of terrestrial evolution led to a waning of this “mantle” flux and to the enhancement of the continental river discharge as the controlling factor of seawater composition; the major transition occurring probably during the late Archean — early Proterozoic time interval. Such evolution is consistent with the observed tectonic, sedimentological, geochemical and metallogenic secular patterns and may also provide an alternative, or complementary, inorganic explanation for the development of the post-Archean oxygenic atmosphere.
TL;DR: Two distinct FBPases are in- volved: a stromal enzyme participating in the Cal- vin cycle and a cytosolic enzyme involved in sucrose synthesis, which permits a balanced withdrawal of carbon from the chloroplast stroma.
TL;DR: The retention of the desmin marker characteristic of normal muscle in cases of rhabdomyosarcoma not only allowed the undifferentiated desmin-positive sarcoma to be classified as rhabDomyosARcoma but also suggests that the use of antibodies to desmin could be very helpful in the future for the diagnosis of undifferentiate r HabdomyOSarcomas.
Abstract: Four embryonal rhabdomyosarcomas, one tumor diagnosed as an undifferentiated sarcoma, probably a rhabdomyosarcoma, and six different non-muscular sarcomas were investigated with antibodies specific for different intermediate filament types. The tumor cells in the rhabdomyosarcomas and the undifferentiated tumor were stained clearly by antibodies to desmin, the intermediate filament type characteristic of muscle. The staining of tumor cells by antibodies to vimentin, the intermediate filament type characteristic of certain cell types of mesenchymal origin including myoblasts, was different in these 5 cases. In one case of embryonal rhabdomyosarcoma nearly all tumor cells were stained, but in the remaining cases few or no tumor cells were positive with the vimentin antibody. In these rhabdomyosarcomas not only the large rhabdomyoblasts, but also the small undifferentiated cells were labeled by antibodies to desmin. In the latter cell type the desmin filaments were arranged typically in coils. In contrast, tumor cells in the non-muscular mesenchymal sarcomas were stained only by antibodies to vimentin but not by antibodies to desmin or prekeratin. The retention of the desmin marker characteristic of normal muscle in cases of rhabdomyosarcoma not only allowed the undifferentiated desmin-positive sarcoma to be classified as rhabdomyosarcoma but also suggests that the use of antibodies to desmin could be very helpful in the future for the diagnosis of undifferentiated rhabdomyosarcomas.
TL;DR: The results demonstrate that the gross electrical activity of the brain changes in a parallel with changed hormone levels, and changes in performance tests coincide with increasing or decreasing alpha activities in the EEG.
TL;DR: This chapter discusses the membrane flow via the Golgi apparatus (GA) of higher plant cells, as a large part of the intracellular transport of macromolecules takes place via dictyosomes.
Abstract: Publisher Summary This chapter discusses the membrane flow via the Golgi apparatus (GA) of higher plant cells. GA plays a significant role in membrane flow processes, as a large part of the intracellular transport of macromolecules takes place via dictyosomes. Therefore, the membranes of the GA are considered as packing material and transportation vehicles for the transfer of polysaccharides and proteins from their sites of synthesis to the plasma membrane (PM). The transfer processes constitute a membrane flow beginning at the GA or, when starting at the endoplasmic reticulum (ER), via the GA. Membrane transfer from the ER to the PM via the GA can be divided into three different phases. Those three phases are, (1) beginning at the ER and ending at the forming faces of the dictyosomes; (2) comprising the flow through the cisternal stack of the dictyosomes, and (3) extention from the maturing faces of the dictyosomes to the PM. The velocity of granulocrine secretion involves measurements based on the use of content markers; measurements based on membrane markers; and calculations derived from a morphometric analysis of thin sections. The recycling of membrane from the PM is a necessary consequence of granulocrine secretion.
TL;DR: Transfer in vitro of mitochondrial porin from the cytosolic fraction into the outer membrane of mitochondria could be demonstrated and binding of the precursor form to mitochondria occurs at 4 degrees C and appears to precede insertion into the membrane.
Abstract: Mitochondrial porin, the major protein of the outer mitochondrial membrane is synthesized by free cytoplasmic polysomes. The apparent molecular weight of the porin synthesized in homologous or heterologous cell-free systems is the same as that of the mature porin. Transfer in vitro of mitochondrial porin from the cytosolic fraction into the outer membrane of mitochondria could be demonstrated. Before membrane insertion, mitochondrial porin is highly sensitive to added proteinase; afterwards it is strongly protected. Binding of the precursor form to mitochondria occurs at 4°C and appears to precede insertion into the membrane. Unlike transfer of many precursor proteins into or across the inner mitochondrial membrane, assembly of the porin is not dependent on an electrical potential across the inner membrane.
TL;DR: The data indicate that GIP is not the exclusive incretin and that additional gut factors with insulinotropic activity exist.
Abstract: The action of gastric inhibitory polypeptide (GIP) antiserum on glucose tolerance and insulin secretion after an intraduodenal glucose load (600 mg/kg) was examined in anesthetized rats. In control experiments the insulin secretion was nearly doubled when glucose was administered intraduodenally, as compared to an iv glucose load to simulate the blood glucose curve after the intraduodenal glucose administration. After injection of GIP antiserum, the glucose curve resulting from the intraduodenal glucose load was slightly elevated and the insulin response was significantly reduced. No free GIP could be measured in the plasma of antibody-treated rats. However, the GIP antiserum did not offset the incretin effect of the intraduodenal glucose load completely. In control experiments the same amount of GIP antibody completely blocked the insulinotropic effect of exogenous porcine GIP (0.6 microgram/kg . h). In nonanesthetized rats serial oral glucose tolerance tests were performed for 14 days after injection of the GIP antiserum. Despite the blockage of endogenous GIP, the glucose tolerance did not change significantly in the antibody-treated group of rats as compared to a control group. These data indicate that GIP is not the exclusive incretin and that additional gut factors with insulinotropic activity exist.
TL;DR: In this article, the authors describe a bubble vortex ring after jet formation upon collapse of a spherical bubble in front of a plane solid boundary, where the vortex ring may expand and contract several times until it disintegrates into a ring of bubbles by some instability finally taking over.
Abstract: With the help of laser produced bubbles in water and high speed photography and holography sophisticated experiments on cavitation bubble dynamics can be conducted. The observation of a bubble vortex ring after jet formation upon collapse of a spherical bubble in front of a plane solid boundary is reported. The vortex ring may expand and contract several times until it disintegrates into a ring of bubbles by some instability finally taking over. A critical discussion of our qualitative understanding of jet formation is included. In a second part the problem of the acoustic cavitation noise spectrum is discussed. Numerically obtained ‘visible cavitation noise’ plots from a single bubble already resemble those obtained experimentally from acoustic cavitation. A discussion shows that the theory should be extended to self-consistency.
TL;DR: Soot measurements were made in laminar ethylene diffusion flames for various fuel and air flow rates in a Wolfhard-Parker burner as mentioned in this paper, and particle number densities, particle size, and soot volume fraction were obtained.
TL;DR: The 20-nm particles from viremic HBeAg-positive carriers always contained more GP33 and GP36 than those from nonviremic anti-HBe- positive carriers, and probably, the two glycoproteins are not essential components of the 20- nm particles, however, they may be important for the formation of complete virions.
TL;DR: Calculated cycling rates showed that during a normal feeding rhythm the periportal zone should catalyze net glucose output and the perivenous zone should mediate net glucose uptake, as proposed by the model of 'metabolic zonation'.
Abstract: Periportal and perivenous hepatocytes contain different activities (V) of antagonistic key enzymes such as glucokinase and glucose-6-phosphatase. In order to get an insight into the metabolism of the periportal and perivenous area the flux rates (v) of the glucose/glucose-6-phosphate cycle were calculated on the basis of the Michaelis-Menten equation using the measured zonal concentrations of glucose and glucose 6-phosphate, the zonal activities of glucokinase and glucose-6-phosphatase previously reported and the half-saturating substrate con- centrations (Km) of the two enzymes found in the literature. The concentrations of glucose were obtained as a first approximation by measuring the concentrations in portal (= periportal) and hepatovenous (= perivenous) blood; those of glucose 6-phosphate were calculated from the levels determined in microdissected periportal and perivenous liver tissue.
The calculations showed (a) that the overall cycling rates agreed remarkably well with those reported for intact animals and (b) that during a normal feeding rhythm the periportal zone should catalyze net glucose output and the perivenous zone should mediate net glucose uptake, as proposed by the model of ‘metabolic zonation’.
TL;DR: In this paper, the γ-ray spectrum emitted after thermal neutron capture in 35Cl has been studied by use of the crystal and pair spectrometers installed at the ILL high flux reactor.
TL;DR: Samwer et al. as discussed by the authors showed that the Nagel-Tauc condition for high (meta-) stability of the metallic glasses is not possible due to the apparent failure of both free-electron and rigid-band models.
Abstract: Amorphous Zr/sub x/Cu/sub 1-x/ alloys (0.50< or =x< or =0.74) prepared by melt-spinning are investigated by means of electrical and thermal measurements. The negative temperature coefficient of the electrical resistivity suggests that the criterion 2k/sub F/roughly-equalk/sub p/ is always fulfilled in this system (k/sub F/ = Fermi wave number, k/sub p/ = position of the first maximum of the structure factor S(k)). The high density of states N/sub ..gamma../(E/sub F/) as inferred from specific-heat measurements originates from the d electrons of Zr. The bare density of states (determined from N/sub ..gamma../(E/sub F/) with the aid of the electron-phonon coupling constant lambda) is three times higher than calculated from the free-electron model and almost independent of the Zr concentration. Phonon-electron scattering as determined by thermal-conductivity measurements shows a similar deviation from free-electron behavior. A decisive test of the Nagel-Tauc condition for high (meta-) stability of the metallic glasses is not possible due to the apparent failure of both free-electron and rigid-band models. All samples investigated are superconducting and belong to the extreme-type-II superconductors. Fluctuation-induced paraconductivity extends up to 1.5T/sub c/. An analysis of the electron-phonon coupling constant lambda as determined from T/sub c/ indicates that the electron-ion matrix element variesmore » strongly across the Zr/sub x/Cu/sub 1-x/ series. The size of lambda, the jump of the specific heat at T/sub c/, and its drop at low temperatures show that Zr-Cu alloys are weak- to intermediate-coupling superconductors. The relatively high T/sub c/ values of the Zr-rich metallic glasses allow the observation of a linear specific-heat term for T<« less Authors: Samwer, K. ; Loehneysen, H.v. Publication Date:1982-07-01 OSTI Identifier:5036836 Resource Type:Journal Article Resource Relation:Journal Name: Phys. Rev. B: Condens. Matter; (United States); Journal Volume: 26:1 Research Org:I. Physikalisches Institut der Universitaet Goettingen, D-3400 Goettingen, West Germany Country of Publication:United States Language:English Subject: 36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COPPER ALLOYS; ELECTRICAL PROPERTIES; SUPERCONDUCTIVITY; ZIRCONIUM ALLOYS; AMORPHOUS STATE; ELECTRIC CONDUCTIVITY; ELECTRON-PHONON COUPLING; ENERGY-LEVEL DENSITY; EXPERIMENTAL DATA; SPECIFIC HEAT; STABILITY; TYPE-II SUPERCONDUCTORS; ALLOYS; DATA; INFORMATION; NUMERICAL DATA; PHYSICAL PROPERTIES; SUPERCONDUCTORS; THERMODYNAMIC PROPERTIES 360104* -- Metals & Alloys-- Physical Properties; 656102 -- Solid State Physics-- Superconductivity-- Acoustic, Electronic, Magnetic, Optical, & Thermal Phenomena-- (-1987)
TL;DR: In the present study a cAMP-dependent pathway leading to exocytosis in the rat lacrimal gland was investigated in detail and an additive enhancement of secretion as well as of phosphorylation of the EC-protein was resulted in.
Abstract: In the present study a cAMP-dependent pathway leading to exocytosis in the rat lacrimal gland was investigated in detail. Using a lobule system in vitro, adrenocorticotropic hormone (corticotropin) and α-melano-cyte-stimulating hormone (α-melanotropin) stimulated protein discharge almost equally effective as dibutyryl-adenosine 3′,5′-monophosphate (Bt2cAMP) and 3-isobutyl-1-methylxanthine but less potent than carbamoyl-choline. Maximal stimulation was obtained at a hormone concentration of 20 nM for both peptides indicating that the active sequence is part of the first 13 amino acids of the corticotropin molecule. 3-Isobutyl-1-methyl-xanthine (40 μM) potentiated the effect of corticotropin on secretion. In contrast to the action of carbamoyl-choline, corticotropin-induced protein discharge was not inhibited by omission of Ca2+ ions from the incubation medium.
The tissue content of cAMP was not significantly affected, by corticotropin or 40 μM 3-isobutyl-1-methyl-xanthine. However, a combination of both agonists led to a rapid 2.5–5-fold increase of the tissue cAMP level in vitro. Adenylate cyclase activity of a lacrimal membrane fraction was effectively stimulated by corticotropin as well as by α-melanotropin. The following hormones and neurotransmitters were ineffective with respect to induction of secretion or activation of adenylate cyclase: isoproterenol (20 μM), dopamine (10 μM), secretin (0.1 μM) glucagon (10 nM), vasoactive intestinal peptide (0.1 μM), substance P (0.1 μM), pancreozymin (0.1 μM) and methioninenkephalin (0.1 μM).
Corticotropin, α-melanotropin, Bt2cAMP and 3-isobutyl-1-methylxan thine induced the phosphorylation of three membrane-bound proteins (Mr 35000, 26000 and 20000) which corresponded almost exactly to the EC-protein and the proteins II and III respectively described previously for the parotid gland [Jahn, R., Unger, C. and Soling, H.D. (1980) Eur. J. Biochem. 112, 345–352]. In accordance with an earlier report [Jahn, R. and Soling, H.D. (1981) FEBS Lett. 131, 28–30] proteins II and III were not phosphorylated during cholinergic stimulation. The combination of submaximal concentrations of agonists acting via the same or via different mechanisms resulted in an additive enhancement of secretion as well as of phosphorylation of the EC-protein.
TL;DR: The qualitative analysis of the Ag-stainability of the NORs was in very good agreement with the results obtained for mammals: Ag-stained NORs are detectable during the entire meiotic prophase up to the pachytene stage, completely absent in the meiotic metaphases I and II, and again demonstrable in early spermatid nuclei.
Abstract: The patterns of activity of the nucleolus organizer regions (NORs) in the spermatogeneses of ten species of all non-mammalian classes of vertebrates and one species of the cephalochordates were investigated with the silver (Ag)-staining technique. The Ag-stainability of the NORs is a measure of the transcriptional activity of the ribosomal RNA genes. In all species, there is a very similar pattern of NOR-activity in the various stages of Spermatogenesis. The qualitative analysis of the Ag-stainability of the NORs was in very good agreement with the results obtained for mammals: Ag-stained NORs are detectable during the entire meiotic prophase up to the pachytene stage, completely absent in the meiotic metaphases I and II, and again demonstrable in early spermatid nuclei. The results confirm the occurrence of postmeiotic reactivation of the RNA genes. The preferential inhibition of rRNA synthesis by low doses of actinomycin D induced a rapid decline of the Ag-stainability of the postmeiotically reactivated NORs. The significance of the evolutionary conservation of the postmeiotic NOR-reactivation is discussed.