Release in vitro of neurohypophysial proteins from neural lobe tissue slices and from isolated neurosecretory granules of the rat

Summary The release of neurophysin from neural lobe tissue slices and isolated neurosecretory granules of the rat was studied at various time intervals after injection of (³⁵S) cysteine into the supraoptic nucleus. For hours after isotope injection the release of radioactive neurophysin from neural lobe tissue was increased by depolarizing concentration of potassium in the presence of calcium ions. Fourteen and 30 days after isotope injection the release of radioactive neurophysin was relatively decreased in a medium of high potassium concentration which might be explained by the heterogeneity of the pool of neurophysin within the neural lobe. Four h after isotope injection the spontaneous release of neurophysin from neural lobe tissue was higher in dehydrated rats than in controls, and the neural lobes of these animals did not respond with an increased release of radioactive neurophysin when exposed to high potassium concentration.Eighteen h after isotope injection the predominating proportion of neurophysin-bound radioactivity was found in the neurosecretory granule fraction, whereas 14 days after injection a fairly equal amount of radioactivity was found in this fraction and in the soluble protein fraction. This indicates that with time an increasing amount of radioactive neurophysin passes from an intragranular to an extragranular pool.The spontaneous release of radioactive neurophysin from isolated neurosecretory granules was higher, and the increase of release upon exposure to an ATP-regenerating system was higher 14 days after isotope injection than 18 h after injection. This may imply that the neurosecretory material undergoes an intragranular maturation process to become more easily releasable. The release of radioactive neurophysin was inhibited in the presence of AMP and EDTA, which demonstrates the dependence of the release process of an ATPase and, probably, of calcium ions.Neurosecretory granules from dehydrated rats possessed a higher spontaneous release than those of control rats 18 h after injection, which may indicate an enhanced intragranular maturation process of the neurosecretory material due to osmotic stimulation.Abbreviations NSG neurosecretory granule - NSM neurosecretory material The present work was supported by grants from Carl-Bertel Nathhorsts vetenskapliga stiftelse, from Svenska Livförsäkrings bolags nämnd för medicinsk forskning, from Överläkare Albert Wallins fond and from the Medical Faculty of the University of Göteborg. I am most indebted to Miss Gull Grönstedt for careful secreterial work.     

Effects of colchicine on release of neurosecretory material from the posterior pituitary gland of the rat

Summary The effect of colchicine on the release of neurosecretory material from the posterior pituitary gland was investigated in the rat in vivo and in vitro. Colchicine was administered subarachnoidally when neurophysin, radiolabelled by injection of (³⁵S) cysteine into the supraoptic nucleus, had accumulated in the neural lobe. Dehydration for 3 days of non-colchicine-treated rats was followed by a 100% reduction of neurophysin-bound radioactivity. When colchicine was given prior to dehydration, the reduction of radioactive neurophysin was less marked. Colchicine treatment alone was likewise followed by a lowering of protein-bound radioactivity in the neural lobe, which may indicate that colchicine, in addition to blocking the rapid axonal transport of neurosecretory material, also impedes the slow transport.The release of radioactive neurophysin in response to depolarizing concentration of potassium in vitro was diminished in the presence of colchicine, the reduction being most pronounced after colchicine treatment in vivo. The biochemical data prove the view that colchicine inhibits the release of neurosecretory material from the neural lobe. The ultrastructural findings support the biochemical data. Thus, colchicine treatment alone or followed by dehydration induced a marked increase in the number of organelles, especially of mitochondria and dense bodies. There was a marked increase in the number of enlarged axons filled with dammed organelles in the infundibulum and neurohypophysis. There was an accumulation of dense core vesicles and microvesicles in the axonal terminals in the neurohypophysis after treatment with either colchicine or colchicine followed by dehydration, which indicates an impediment of the release process. Dehydration alone induced a depletion of the dense core vesicles in the terminals. Out from the combined biochemical and ultrastructural findings possible mechanisms for the action of colchicine are discussed.The present study was supported by grants from Svenska livförsäkringsbolags fond för medicinsk forskning, The Swedish Medical Research Council (No. B73-12X-2543-05B), Magnus Bergvalls stiftelse and from the Medical Faculty, University of Göteborg.Miss Gull Grönstedt is thanked for careful secretarial work and the technical assistance by Mrs. Wally Holmberg, Mrs. Elisabeth Norström and Mrs. Ulla Svedin is gratefully acknowledged. Abbreviations used: NSG = neurosecretory granules; NSN = neurosecretory material; SON = supraoptic nucleus.     

Subcellular distribution of neurophysin in rats subjected to haemorrhage,salt-loading and lactation and in rats with hereditary diabetes insipidus (brattleboro strain)

Summary The subcellular distribution of radioactive neurophysin and the release of neurophysin from isolated neurosecretory granules (NSG) from the posterior pituitary gland were studied at various time intervals after injection of (³⁵S) cysteine into the supraoptic nucleus under various functional conditions. In consistency with previous findings (Norström, 1972), increased amounts of radioactive neurophysin were recovered extra-granularly at longer time intervals after isotope injection. Increased quantities of free labelled neurophysin were found in lactating rats and homozygous diabetes insipidus (DI) rats 7 and 1 day after injection, respectively. Salt-loading for 4 days did not affect the subcellular distribution of radioactive neurophysin 1 day after injection of (³⁵S) cysteine. 8.5 days after isotope injection acute haemorrhage was followed by augmented amounts of radioactive neurophysin among the soluble proteins, but at 1 day no difference was observed between bled animals and controls. The spontaneous release of neurophysin form NSG was higher in stimulated animals and increased with time after isotope injection in controls as well as in experimental animals. The absolute increase in release of neurophysin in response to ATP was higher in stimulated rats whereas NSG from DI rats did respond poorly to ATP.The present work was supported by grants from Svenska Livförsäkringsbolags nämnd för medicinsk forskning, Wilhelm och Martina Lundgrens fond, Albert Wallins fond and the University of Göteborg. I am indebted to Miss Gull Grönstedt for careful secretarial work.     

The effect of chlorpromazine and tetracaine on the rapid axonal transport of neurosecretory material in the hypothalamo-neurohypophysial system of the rat

Summary The effects of chlorpromazine (cpz) and tetracaine (tc) on the rapid axonal transport of neurosecretory material (NSM) in the hypothalamo-neurohypophysial system was investigated. Following subarachnoidal injection of these drugs, the incorporation of (³⁵S) cysteine into proteins of the supraoptic nucleus was slightly depressed. The protein-bound radioactivity in the posterior pituitary was markedly lowered in experimental rats which indicates a partial blockage of the rapid axonal transport of NSM along the hypothalamoneurohypophysial tract. Both cpz and tc induced an increase in the number of mitochondria and profiles of granular endoplasmic reticulum. The axons in the infundibulum and neurohypophysis were enlarged by dammed organelles, indicating a blockage of axonal transport. There was an increased number of microvesicles, often arranged in a crystalloid pattern, in the terminals. The number and distribution of neurotubuli and neurofilaments were not changed. A possible stimulatory effect of cpz on the release of NSM from the neural lobe is assumed Possible mechanisms for the action of mitotic inhibitors, transquilizers and local anesthetics are discussed.The present work was supported by grants from Svenska Livforsäkringsbolags Fond, H. Hiertas stiftelse, Magnus Bergwalls stiftelse, The Swedish Medical Research Council No. B73-12X-2543-05B, Statens naturvetenskapliga forskningsråd No. 2535-8 and from the Medical Faculty, University of Göteborg. We are indebted to Mrs. Margareta Andersson, Mrs. Wally Holmberg, Mrs. Elisabeth Norström and Mrs. Ulla Svedin for excellent technical assistance, and to Miss Gull Grönstedt for careful secretarial work.     

Intra- and extraganglionic nerve endings formed by neurosecretory cells of the cerebral ganglion of the earthworm (Lumbricus terrestris L.)

Summary In the cerebral (= supraesophageal, suprapharyngeal) ganglion of the earthworm, a number of neurosecretory Gomori-positive perikarya are bipolar; others are unipolar, or multipolar. Some of the neurosecretory cell processes project centrally into a fibrous zone; peripheral processes enter small nerves which leave the dorsocaudal aspect of the ganglion.In the central fibrous zone, the neurosecretory fibers form varicose Gomoripositive terminals. Here, also zinc-iodine-osmium (ZIO)-positive fibers and monoamine fluorescent fibers are found. With the electron microscope, nerve terminals containing synaptic vesicles and either large neurosecretory peptidergic granular vesicles (diameter more than 1500 Å), or smaller granular vesicles (diameter about 1300 Å, or 900 Å) are observed. These axon endings mainly form axo-dendritic synapses. Peptidergic profiles are both pre- and postsynaptic. Some of the extraganglionic peptidergic fibers appear to terminate around vessels, but most of them form terminals on the visceral muscle cells which surround the ganglion.We think that the central neurosecretory processes communicate with the fibers of the synaptic zone of the ganglion. The peripheral neurosecretory peptidergic fibers are supposed to form a primitive neurohemal area and/or to function as vasomotor nerves. The fibers innervating the visceral muscle cells may represent vegetative nerves.     

Physico-chemical and immunological properties of allophycocyanins

Allophycocyanins were purified from diverse cyanobacteria and one rhodophytan alga (Cyanidium caldarium). The native proteins are trimeric molecules with the structure ()₃. Representative native allophycocyanins and their and subunits were characterized with respect to molecular weight, amino acid composition, isoelectric point, absorption and fluorescence spectra and immunological properties. All of the allophycocyanins studied were strikingly similar with respect to each of these properties.Renatured and subunits of allophycocyanin were distinct immunologically from each other, and both cross-reacted with the antiserum to the native protein.Trimeric allophycocyanin was readily reconstituted from the purified and subunits. Formation of hybrid allophycocyanins was demonstrated by direct isolation and characterization of the hybrid proteins and by immunological techniques.The results support the view that allophycocyanins are a highly conserved group of proteins.Abbreviation Used SDS sodium dodecyl sulfate     

Seepage patterns, pore water, and aquatic plants: hydrological and biogeochemical relationships in lakes

This study documented linkages between lakeshore seepage fluxes, pore water chemistry, and aquatic plants in several lakes of the Adirondack Mountains region of New York, USA. Three replicate stations were set up along each of four different lake shorelines. From June through September 1998 and from snowmelt in April through August 1999, seepage flux was measured with seepage meters. Throughout this time period, lake surface water and pore water chemistry were monitored weekly to biweekly. At each station, leaf tissue chemistry of the water lily Nuphar variegatum was measured once in each year. Sediment chemistry and plant abundance were also measured once in 1998. We found that pore water concentrations of base cations, iron, and zinc were related to the direction, magnitude, and variability of seepage fluxes. Concentrations of base cations, iron, and zinc were both highest and most variable where seepage was low (0 to 50mLm^–2h^–1) in contrast to being more stable where seepage was highest and variable (–608 to 612mLm^–2h^–1). Leaf tissue chemistry and plant abundance were also related to seepage patterns. N. variegatum leaves had elevated zinc content at stations with low average discharge. Knowledge of seepage patterns helped to explain spatial patterns of elevated trace metal content in both pore water and plant tissues. Our work suggests that the hydrological process of lakeshore seepage exerts important controls on lakeshore biogeochemistry.     

Defining patch contribution in source-sink metapopulations: the importance of including dispersal and its relevance to marine systems

In metapopulations, individual patch contribution (source or sink) is typically calculated as a patch growth rate (the intrinsic lambda, _I) dependent only upon local demographics. We demonstrate that when dispersal is explicitly included in the model, the growth rates for all patches calculated in an analogous manner (the observed lambda, _O) equilibrate to the overall metapopulation growth rate and thus no longer serve as a useful reflection of the demographic and dispersive characteristics of a given patch. In these situations we suggest an alternative method of estimating patch contribution (the contribution lambda, _C) in which a patch is decremented for losses that occur within it and credited for gains that occur anywhere in the metapopulation because of it. We compare values of _I, _O, and _C for individual patches in discrete-time density-independent metapopulation models of two organisms with very different life histories, mayflies with adult dispersal, and reef fish with larval dispersal. Results confirm that when dispersal is included only _C clearly indicates the contribution of a particular patch. _I–_C comparisons indicate that inclusion of dispersal in the mayfly model was only important if connectivity patterns were random or directional. In the reef fish model, however, results were very different when dispersal was included and there were many cases of patches being misidentified (e.g., as a source when it was really a sink) depending upon the metric used (_I or _C). Our results demonstrate the importance of including dispersal in metapopulation models when considering the contribution of individual patches.     

On the origin of the branched alkyl substituents on ring B of flexirubin-type pigments

Studies with radioactive leucine, isoleucine, valine and acetate showed that in Flavobacterium spec. strain C1/2 leucine can function as the precursor of the terminally branched alkyl substituents in flexirubin-type pigments.Part 25 in the series Investigations on Metabolites of Microorganisms. For Part 24 see H. Achenbach, A. Böttger-Vetter, D. Hunkler, E. Fautz and H. Reichenbach, Tetrahedron, in the press     

Conformational transitions and charge translocation by the Na,K pump: Comparison of optical and electrical transients elicited by ATP-concentration jumps

Summary The electrogenic properties of the Na,K-ATPase were studied by correlating transient electrical events in the pump molecule with conformational transitions elicited by an ATP-concentration jump. Flat membrane fragments containing a high density (8000 m^–2) of oriented Na,K-ATPase molecules were bound to a planar lipid bilayer acting as a capacitive electrode. ATP was released in the medium from a photolabile inactive ATP derivative (caged ATP) by a 40-sec light flash. Electrical signals resulting from transient charge movements in the protein under single-turnover conditions were recorded in the external measuring circuit. In parallel experiments carried out under virtually identical conditions, the fluorescence of membrane fragments containing Na,K-ATPase with covalently-bound 5-iodoacetamido-fluorescein (5-IAF) was monitored after the ATP-concentration jump. When the medium contained Na⁺, but no K⁺, the fluorescence of the 5-IAF-labeled protein decreases monotonously after release of ATP. In the experiments with membrane fragments bound to a planar bilayer, a transient pump current was observed which exhibited virtually the same time behavior as the fluorescence decay. This indicates that optical and electrical transients are governed by the same rate-limiting reaction step. Experiments with chymotrypsin-modified Na,K-ATPase suggest that both the fluorescence change as well as the charge movement are associated with the deocclusion of Na⁺ and release to the extracellular side. In experiments with Na⁺-free K⁺ media, a large inverse fluorescence change is observed after the ATP-concentration jump, but no charge translocation can be detected. This indicates that deocclusion of K⁺ is an electrically silent process.     

The extravascular channel system in the rostral pituitary of Mugil cephalus (Teleostei) as revealed by use of horseradish peroxidase

Summary Using the unlabeled antibody peroxidase-antiperoxidase (PAP) technique at the light microscopic level, it was demonstrated that, in the amphibian magnocellular hypothalamo-hypophysial neurosecretory system, vasotocin and mesotocin are synthesized in separate neurons. A tendency to preferential location of the two kinds of neuronal perikarya is described. The neurosecretory perikarya are the origin of separate vasotocinergic and mesotocinergic axons. In the neural lobe, the pattern of distribution of the two types of axons is different. The coarse ventricular dendrites of both kinds of neurons are hormone-containing processes. Staining with anti-bovine neurophysin I serum suggested that the vasotocinergic and the mesotocinergic neurons synthesize different neurophysins.This investigation was supported by a grant from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

Reciprocal Innervation between Serotonergic and GABAergic Neurons in Raphe Nuclei of the Rat

Midbrain slices containing the dorsal and medial raphe nuclei were prepared from rat brain in order to study serotonergic-GABAergic interaction. The slices were loaded with either [³H] serotonin or [³H]GABA, superfused and the electrically induced efflux of radioactivity was determined. The GABA_A receptor agonist muscimol (3 to 30 M) and the GABA_B receptor agonist baclofen (30 and 100 M) inhibited [³H]serotonin and [³H]GABA release. These effects of muscimol were reversed by the GABA_A antagonists bicuculline (100 M). The GABA_B antagonist phaclofen (100 M) also antagonized the baclofen-induced inhibition of [³H]serotonin and [³H]GABA release. Phaclofen by itself increased [³H]serotonin release but it did not alter [³H]GABA overflow. Muscimol (10 M) and baclofen (100 M) also inhibited [³H]serotonin release after depletion of GABAergic neurons by isoniazid pretreatment. These findings indicate the presence of postsynaptic GABA_A and GABA_B receptors located on serotonergic neurons. The 5-HT_1A receptor agonist 8-OH-DPAT (0.01 to 1 M) and the 5-HT_1B receptor agonist CGS-12066A (0.01 to 1 M) inhibited the electrically stimulated [³H]serotonin and [³H]GABA release. The 5-HT_1A antagonist WAY-100135 (1 M) was without effect on [³H]serotonin and [³H]GABA efflux by itself but it reversed the 8-OH-DPAT-induced transmitter release inhibition. During KCl (22 mM)-induced depolarization, tetrodotoxin (1 M) did not alter the inhibitory effect of CGS-12066A (1 M) on [³H]GABA release, it did blocked, however, the ability of 8-OH-DPAT (1 M) to reduce [³H]GABA efflux. After depletion of raphe serotonin neurons by p-chlorophenylalanine pretreatment, CGS-12066A (1 M) still inhibited [³H]GABA release whereas in serotonin-depleted slices, 8-OH-DPAT (1 M) was without effect on the release. We conclude that reciprocal influence exists between serotonergic projection neurons and the GABAergic interneurons or afferents in the raphe nuclei and these interactions may be mediated by 5-HT_1A/B and GABA_A/B receptors. Both synaptic and non-synaptic neurotransmission may be operative in the 5-HTergic-GABAergic reciprocal interaction which may serve as a local tuning in the neural connection between cerebral cortex and midbrain raphe nuclei.     

A histochemical study of the oxidation of 17β-estradiol in human term placenta at different incubation conditions

Summary The present study deals with the histochemical demonstration of 17-estradiol dehydrogenase in human term placenta using the polyvinyl alcohol method to reduce diffusion artefacts. Incubations took place with both NAD⁺ and NADP⁺ as coenzymes and at different pH values of the incubation medium. The NAD⁺ linked enzyme reaction showed a greater activity than the NADP⁺ linked, both in the trophoblast as well as in connective tissue. There were differences in staining intensity at the different pH values, and strongest reaction was observed using glycine-NaOH buffer pH 10 in the incubation medium. Owing to a non-enzymatically reduction of nitro blue tetrazolium by reduced NAD⁺, the demonstration of 17-estradiol dehydrogenase is independent of diaphorase at this high pH. The findings are discussed in relation to data about nothing dehydrogenase and biochemically determined pH optima for the enzymatic reactions dealt with in this work.The following Abbreviations are used in this Article NAD⁺ -nicotinamide adenine dinucleotide - NADP⁺ nicotinamide adenine dinucleotide phosphate - NBT nitro blue tetrazolium - PVA polyvinyl alcohol - tris tris (hydroxymethyl)-aminomethane - 17-OH-SDH 17-OH-steroid-dehydrogenase Supported by The Norwegian Research Council for Science and the Humanities. Skilful assistance of Mrs. E. Alvestad, Mrs. Aa. Flatnes and Mrs. F. Sørensen is greatfully acknowledged.     

Sheep α-globin gene sequences: Implications for their concerted evolution and for the down-regulation of the 3′ genes

In sheep as in man and most other mammals, there are two -globin genes (^I and ^II), which are expressed at different levels, the upstream gene being the most efficient. In -globin gene triplication and quadruplication, this trend is confirmed, i.e., the -chain output of the downstream genes progressively decreases. In this study, we have determined the complete sequence of the cDNAs and of both the introns in a triple- haplotype in which each gene could be recognized for the presence of distinct alleles. The sequence analysis reveals that the bodies of the three -globin genes are essentially identical (99.9% homology) and moreover indicates that the down-regulation of additional -globin genes in sheep is not the effect of sequence variation from the Cap to the Poly(A) addition sites. This striking similarity among -genes is higher than that seen in other mammals and is probably sustained by particularly efficient mechanisms of gene conversion and cross-over fixation. Correspondence to: Dr. M.S. Ristaldi     

Structure of the cDNA coding for conglutin γ, a sulphur-rich protein from Lupinus angustifolius

The sequence of cDNA coding for a sulphur-rich storage protein from Lupinus angustifolius L., conglutin , was determined. The coding region contained an N-terminal leader peptide of 28 amino acids which directly preceded subunits of M _r 28 239 and 16 517. Extensive sequence homology between the protein encoded by conglutin cDNA and basic 7S globulin from soybean was observed. Sequence homology to proteins from other classes of storage proteins, 11S, 7S and 2S, was limited to short and highly fragmented sequences. The amino acid sequence, Asn-Gly-Leu-Glu-Glu-Thr, characteristic of the primary site for post-translational cleavage of the precursors of 11S proteins, was absent from the sequence predicted for prepro-conglutin . It is concluded that conglutin is a representative of a fourth type of storage protein in legumes, distinct from the 11S, 7S and 2S storage protein families.     

Biochemical composition of maize (Zea mays L.) pollen

Summary Proline was the most abundant amino acid with a mean value of 186.28 moles/mg dry pollen. The other amino acids tested were below 33 moles/mg dry pollen. The mutant wx significantly increased aspartic acid, valine, histidine and an unknown but significantly decreased aminobutyric acid. The mutant sh ₂ significantly increased glutamic acid, proline, lysine, histidine and an unknown but significantly decreased aspartic acid and aminobutyric acid. The effect of su ₁ was altered by the genetic background involved. In one genetic background, su ₁ did not significantly increase any amino acid but significantly decreased alanine and aminobutyric acid. However, in a distinctly different background, su ₁ significantly increased aminobutyric acid but significantly decreased aspartic acid and glutamic acid. Apparently the genetic background is capable of producing major shifts in the amino acid pattern in addition to the action of these mutants.The fatty acids, palmitic and linolenic were the most common with percentages of 54.1 and 34.4 respectively. The mutants tested did not affect the fatty acid distribution.

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Zusammenfassung Prolin war die am reichlichsten vorkommende Aminosäure mit einem mittleren Gehalt von 186,28 Mikromol per mg trockenen Pollen. Die anderen Aminosäuren erreichten weniger als 33 Mikrogramm per mg trockenen Pollen.Die Mutante wx zeigte einen signifikant erhöhten Gehalt an Asparaginsäure, Valin, Histidin, sowie einer nicht identifizierten Komponente, während der Gehalt an -Aminobuttersäure signifikant erniedrigt war. Die Mutante sh ₂ ist gekennzeichnet durch einen signifikant erhöhten Gehalt an Glutaminsäure, Prolin, Lysin, Histidin, sowie einer unbekannten Fraktion; der Gehalt an Asparaginsäure und -Aminobuttersäure war dagegen signifikant erniedrigt. Die Wirkung des mutierten Gens su ₁ wurde durch das übrige Genom, in dem es sich befand, geändert. In dem einen genetischen Milieu verursachte su ₁ keine signifikante Erhöhung des Gehaltes irgend einer Aminosäure, während der Gehalt an Alanin und -Aminobuttersäure signifikant erniedrigt war. In einem anderen genetischen Milieu jedoch zeigte su ₁ eine signifikante Erhöhung der -Aminobuttersäure; Asparaginsäure und Glutaminsäure waren signifikant erniedrigt.Offensichtlich ist das übrige Genom zusätzlich zu der Wirkung der genannten Mutanten in der Lage, wesentliche Verschiebungen im Verteilungsmuster der Aminosäuren zu verursachen.Von den Fettsäuren wurden am häufigsten Palmitin- und Linolen-Säure mit einem Gehalt von 54,1 bzw. 34,4% gefunden. Die untersuchten Endosperm-Mutanten zeigten keinen Einfluß auf die Fettsäureverteilung im Pollen.

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Journal Series Paper No. 3468, Florida Agricultural Experiment Station.     

Novel prebiotic systems: Nucleotide oligomerization in surfactant entrapped water pools

Summary Oligomerization of 5-TMP in water pools entrapped by dodecyl-ammonium chloride surfactant aggregates in benzene: hexane in the presence of dicyanodiimide at temperatures ranging from 21°–72° resulted in the formation of linear and cyclic oligonucleotides containing up to pentamers. Effects of temperature, time and surfactants have been examined. Rate constants for the formation of oligomers have been determined at five different temperatures. These data afforded values of H = 11.8 ± 1.9 Kcal mole^–1, S=–53 6 e.u. and G = 27.4 4.0 Kcal mole^–1. Prebiotic significance of these results are discussed.     

Saccharomyces cerevisiae 2-mum DNA. An analysis of the monomer and its multimers by electron microscopy.

Summary The non-tandem inverted duplication in the 2-m DNA of Saccharomyces cerevisiae has a length of 0.19 m and is located asymmetrically along the molecule. The majority of the dumb-bell structures that are formed upon denaturation and selfannealing of the 2-m monomer consists of the renatured inverted duplication sequences as double stranded stem and two single stranded loops of 0.67 m±0.06 m (S-loop) and 0.86 m±0.05 m (L-loop) length. Two additional size classes which comprised 5–10% of the measured molecules had contour lengths of around 1.7 m and 2.1 m. The smaller dumb-bells contained two S-loops and the larger dumb-bells contained two L-loops as was shown by heteroduplex mapping with an HindIII fragment from the L-loop. Two models which assume illegitimate or site specific recombination, are presented to explain the generation of double S-loop and double L-loop molecules. At least part of the 4-m and 6- circular molecules present in the yeast supercoiled DNA fraction are shown to be dimers and trimers of 2-m monomers, but often with inverted loop segments most probably due to intramolecular recombination between sequences of the inverted duplication.2-m DNA is used to indicate the supercoiled DNA fraction although in our measurements the average monomeric length is 1.9 mPart of this work has been presented at the Conference: The Genetics and Biogenesis of Chloroplasts and Mitochondria, Munich, August, 1976     

Ultrastructural characterisation of vasopressinergic terminals in the lateral septum of murine brains by use of monoclonal anti-neurophysins

Summary Synapses in the lateral septum of the murine brain have been investigated by ultrastructural immunocytochemistry, using monoclonal anti-neurophysins in both immunoperoxidase and immunogold techniques. In the region shown by light microscopy to be rich in vasopressinergic innervation, synaptic boutons containing 30 nm clear vesicles and occasional 100 nm dense-cored granules (granules) were stained by pre-embedding immunoperoxidase procedures with antisera to vasopressin-neurophysin, but not oxytocin-neurophysin; reaction product was diffusely distributed in the terminals. Terminals were symmetrical, and both axosomatic and axodendritic in type. Postembedding immunogold procedures by use of anti-vasopressin-neurophysin labeled only the 100 nm diameter granules in the terminals. Sodium meta-periodate treatment bleached immunoreactive granules, indicating the presence of a carbohydrate residue. The quantum of peptide packaged in the granules appears to be smaller than that in magnocellular neurones; nevertheless, the results indicate that, as in the magnocellular neurosecretory system, vasopressin and its neurophysin are packaged exclusively in granules, and that vasopressin in the septum is likely to be derived from a precursor comprising vasopressin, vasopressin-neurophysin and a glycosylated residue.     

The hypothalamo-hypophysial system in acipenseridae

Summary The neurohypophysis of sexually mature male and female Acipenser güldenstädti Brandt and Acipenser stellatus Pallas was studied light and electron microscopically. The recessus hypophysei lined with ependymal cells of two main types, narrow and wide, are in the center of the neurohypophysial roots. Processes from both cell types run radially to the basement membrane of the connective tissue layers abutting on the hypophysial intermediate lobe. Protrusions penetrating deep into the recessus hypophyseus are found in the apical parts of the wide cells. Pituicytes are rare in the neurohypophysis. The ultrastructure of both ependymal cell types and of the pituicytes is described. Nonmyelinated Gomori-positive (peptidergic) neurosecretory A₁ and A₂ type fibres and their terminals containing elementary neurosecretory granules (1400–1800 Å and 1000–1400 Å respectively) are the main structural elements of the neurohypophysis. Some dark and single myelinated neurosecretory fibres have been found. The adrenergic fibres (type B) were described earlier (Polenov et al., 1972a). The structural peculiarities of the neurohypophysis are discussed in functional and comparative-morphological terms.