Vasopressin-immunoreactive cells in the dorsomedial hypothalamic region,medial amygdaloid nucleus and locus coeruleus of the rat

Summary Recently, the existence of a vasopressin-immunoreactive cell group was described in the bed nucleus of the stria terminalis (van Leeuwen and Caffé 1983). In the present investigation additional nuclei containing vasopressin-immunoreactive cells were found, after colchicine pretreatment, in the dorsomedial hypothalamus, medial amygdaloid nucleus and the locus coeruleus.Vasopressin-immunoreactive cells in the dorsomedial hypothalamus and medial amygdaloid nucleus are small (8–14 m and 10–14 m, respectively), while those in the locus coeruleus are medium-sized (20–25 m). Incubation with anti-bovine neurophysin II and anti-rat neurophysin revealed staining of the same cell group in the above-mentioned areas. None of these cell groups show stained cells after incubation with anti-oxytocin and anti-bovine neurophysin I. When sections of the homozygous Brattleboro rat, which shows a deficiency in vasopressin synthesis, are incubated with anti-vasopressin, anti-bovine neurophysin II, or anti-rat neurophysin, no immunoreactivity can be observed in these brain regions.The above-mentioned cell groups may contribute to the vasopressinergic innervation of brain sites that have been reported to persist after lesioning of the suprachiasmatic, paraventricular and bed nuclei of the stria terminalis.     

Ontogeny of the photoreceptors in the embryonic retina of the viviparous guppy,Poecilia reticulata P. (Teleostei)

Summary Ultrastructural analyses of retinal development in the guppy embryo show that at midgestation all types of photoreceptors are differntiated in the fundus, and at birth differentiation extends over the whole retina. Formation of discs of outer segments is more rapid in rods than in cones. Double cones differentiate simultaneously with long single cones and are formed by the adhesion of two primordial inner segments; short single cones develop last. Wherever cones are differentiated, they are arranged in an adult-type square mosaic. The rods in the embryo, as opposed to the adult, are likewise regularly arranged within the mosaic unit.These results are at variance with the generally held opinion that adult teleosts which possess duplex retinae have larvae with pure cone retinae, and that rods, double cones and mosaics appear in late larval life or only at metamorphosis.In the double cones of the guppy embryo subsurface cisternae develop along the adjoining primordial inner segments. Additionally, regularly distributed subsurface cisternae are formed in the regions of intimate contact of long single cones with double cones and rods.We suggest that the early development of rods and double cones, and a square-mosaic with regular distribution of rods and subsurface cisternae, provide the newly born with a fully functional optical apparatus, especially suited to perception of movements. This is necessary for its survival against predatory, especially maternal, attacks.This work was in part subsidized by a grant from the Medical Research Council of Ireland to Y.W.K.     

Activities of the nuclear envelope in the salivary glands of Drosophila

Morphological data are presented concerning the single-membrane-bound vesicles ("oval bodies") associated with the nuclear envelopes of larval salivary gland cells of Drosophila. Data are also presented concerning the existence of cytoplasmic annulate lamellae in these same cells. The mode of formation of these structures, as well as the relationships between them and with other cytoplasmic organelles are described. The possible functional significance of these phenomena is discussed.     

Iron loading in the livers of metamorphosing lampreys,Petromyzon marinus L.

Iron loading of hepatocytes was followed through the stages (1-7) of metamorphosis in lamprey (Petromyzon marinus L.) using light- and electron-microscopic histochemistry. Iron is present in ferric and ferrous forms in the hepatocytes of larval lampreys in levels that can only be detected in the electron microscope. During the initial stages (1-3) of metamorphosis iron begins to increase in the cytoplasmic matrix and in dense bodies but it is not apparent in the light microscope until stage 4. The increased accumulation of iron through the subsequent stages (5-7) of metamorphosis coincides with the advanced degeneration and ultimate disappearance of bile canaliculi and bile ducts. The absence of a bile canaliculus is concurrent with the beginning of staining of lateral cell borders for ferrous iron and with intense concentrations of ferric iron throughout the cytoplasmic matrix and within cytoplasmic dense bodies. By the end of metamorphosis the hepatocytes resemble iron-loaded hepatocytes in pathological and experimentally induced situations in other vertebrates. The iron loading of hepatocytes during metamorphosis is discussed with respect to both the concomitant atresia of the biliary tree and alteration of several aspects of blood morphology and chemistry. Since iron loading occurs synchronously in the hepatocytes of a given population of metamorphosing lampreys, this organism should prove to be a useful experimental system for investigation on cellular mechanisms of iron loading in vertebrates.     

Topographical distribution of the gonadotrophs,mammotrophs, somatotrophs and thyrotrophs in the pituitary gland of the baboon (Papio cynocephalus)

The identification and regionalization of four pituitary parenchymal cell types, gonadotrophs, mammotrophs, somatotrophs and thyrotrophs, were studied in the baboon (Papio cynocephalus) hypophysis using immunocytochemistry. The gonadotrophs were homogeneously distributed throughout the entire pars distalis. Both mammotrophs and somatotrophs predominate at the superior and inferior poles of the organ. The medial and anteromedial regions are populated by mammotrophs and thyrotrophs, while the lateral and posterior portions of the pars distalis contain large numbers of somatotrophs.     

Structure of the tail fin in teleosts

The influence of adrenalectomy and administration of hypertonic saline on the amount of vasopressin, oxytocin, and neurophysin contained in the median eminence and the neural lobe of rats was studied by means of the following methods: (i) morphometric and microphotometric analyses of aldehyde fuchsin-stained histological sections of the neurohypophysis; (ii) immunohistochemical demonstration of vasopressin, oxytocin, and neurophysin in the neurohypophysis, and (iii) radioimmunological measurement of vasopressin and oxytocin in extracts of the median eminence and the neural lobe. Adrenalectomy increases the amount of vasopressin and neurophysin in the external layer of the median eminence but does not change the content of oxytocin. It has no influence on the amount of vasopressin, oxytocin, and neurophysin demonstrable in the inner layer of the median eminence and in the neural lobe two weeks after the operation. Hypertonic saline markedly diminishes the vasopressin, oxytocin, and neurophysin content of the inner layer of the median eminence and the neural lobe but reduces only slightly, if at all, the amount of vasopressin and neurophysin in the outer layer of the median eminence. The findings support the concept that osmotic stress reduces only the vasopressin and oxytocin content of the hypothalamus-neural lobe system and has no or only little influence on the vasopressin content of the outer layer of the median eminence.     

Organization of gene and non-gene sequences in micronuclear DNA of Oxytricha nova.

In order to study the derivation of the macronuclear genome from the micronuclear genome in Oxytricha nova micronuclear DNA was partially digested with EcoRI, size fractionated, and then cloned in the lambda phage Charon 8. Clones were selected a) at random b) by hybridization with macronuclear DNA or c) by hybridization with clones of macronuclear DNA. One group of these clones contains only unique sequence DNA, and all of these had sequences that were homologous to macronuclear sequences. The number of macronuclear genes with sequences homologous to these micronuclear clones indicates that macronuclear sequences are clustered in the micronuclear genome. Many micronuclear clones contain repetitive DNA sequences and hybridize to numerous EcoRI fragments of total micronuclear DNA, yielding similar but non-identical patterns. Some micronuclear clones containing these repetitive sequences also contained unique sequence DNA that hybridized to a macronuclear sequence. These clones define a major interspersed repetitive sequence family in the micronuclear genome that is eliminated during formation of the macronuclear genome.     

Cloning and sequencing of a full length cDNA coding for human retinol-binding protein.

We have isolated and sequenced a cDNA clone coding for human Retinol Binding Protein. The sequence indicates that Retinol Binding Protein is synthesized as a single polypeptide chain precursor which is then matured to the secreted protein by removal of a leader peptide. Southern and Northern blot analysis suggest that the gene is present in one or few copies per haploid genome and is transcribed in a single mRNA species.     

Synthesis of short RNA fragments by the benzotriazolyl phosphotriester approach

Analytical and experimental evidence will be presented to show that addition of a slight excess of 2-chlorophenyl-0,0-bis[1-benzotriazolyl]phosphate to a properly 2',5'-protected ribonucleoside gives an intermediate 3'-phosphotriester, which, after addition of a 2'-protected ribonucleoside, affords a dimer containing solely a 3'-5'-internucleotide linkage. The above phosphorylation procedure has been used in the synthesis of the pentamer UpApCpGpC.