Morphological correlates of serotonin-neuropeptide Y interactions in the rat suprachiasmatic nucleus: Combined radioautographic and immunocytochemical data

Summary The morphological substrate of putative serotonin (5-HT)/neuropeptide Y (NPY) interactions in thé suprachiasmatic nucleus (SCN) was investigated by combined radioautography and immunocytochemistry after intraventricular administration of (³H)5-HT in the rat. In the ventral portion of the SCN, the distribution of (³H)5-HT uptake sites overlapped closely the NPY-immunoreactive terminals. Previous investigations have shown that the dense 5-HT and NPY innervations of the SCN originate in different structures, i.e., the midbrain raphe nuclei and the ventral lateral geniculate nucleus, respectively. Accordingly, in the present study, destruction of 5-HT afferents by 5,7-dihydroxytryptamine was not found to induce any modification in NPY staining and, in ultrastructural immuno-radioautographic preparations, two distinct pools of axonal varicosities could be identified. Both 5-HT and NPY terminals established morphologically defined synaptic junctions, sometimes on the same neuronal target. Some cases of direct axo-axonic appositions between the two types of terminals were also encountered. These data constitute additional criteria for characterizing the cytological basis of the multiple transmitter interactions presumably involved in the function of the SCN as a central regulator of circadian biological rhythms.     

冷冻或切除小脑蚓部山顶(Culmen)对豚鼠“踏步自动作用”(Stepping automatism)的影响

本研究探讨部分冷冻或切除小脑蚓部(vermis)对整体豚鼠“踏步自动作用”(steppingautomatism)的影响。“踏步自动作用”由我们近年来发现的诱发踏步物质(SIS)(4-R-2,2,5,5-四(三氟甲基)-咪唑啉)所引起。结果表明部分冷冻或切除小脑蚓部的山顶(culmen,Ⅴ和Ⅳ叶)和中央叶(Centralis,Ⅲa,b)明显增强豚鼠的“踏步自动作用”。冷冻小脑不能触发,但仅能调控“踏步自动作用”。这种调控作用对自动化程度差的弱“踏步自动作用”特别显著。蚓部山顶(Ⅴ叶为主)同时调控左右前肢踏步,而一侧蚓部山顶及其半球则主要调控同侧前肢踏步。此外,本研究的结果表明当介面温度(冷冻头和小脑幕间)致冷至5℃—0℃左右,冷冻小脑便可基本模拟部分切除小脑效应。     

Isolation and characterisation of transposon-induced mutants of Erwinia carotovora subsp. atroseptica exhibiting reduced virulence

Summary The blackleg pathogen Erwinia carotovora subsp. atroseptica (Eca) causes an economically important disease of potatoes. We selected a genetically amenable Eca strain for the genetic analysis of virulence. Tn5 mutagenesis was used to generate nine mutants which exhibited reduced virulence (Rvi^-) of strain SCRI1043. Following physiological characterisation, mutants were divided into three classes: (1) auxotrophs; (2) extracellular enzyme mutants; and (3) a growth rate mutant. The isolation of these Rvi^- mutants has allowed us to consider some factors that affect Eca virulence.     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity.     

Adrenergic nerves and 5-hydroxytryptamine-containing cells in the pulmonary vasculature of the aquatic file snake Acrochordus granulatus

Summary The adrenergic innervation of the pulmonary vasculature of the file snake Acrochordus granulatus was examined by use of glyoxylic acid-induced fluorescence. Perivascular plexuses of blue-green fluorescent nerves are observed around the common pulmonary artery, the anterior and posterior pulmonary arteries, the arterioles leading to the gas exchange capillaries of the lung, the venules draining the lung, and the anterior and posterior pulmonary veins. Adrenergic nerves are also associated with the visceral smooth muscle of the lung septa and other tissues. Thus, adrenergic control of pulmonary blood flow may occur either at the common pulmonary artery or more regionally within the lung. Regional control of blood flow in the elongate lung of this snake may be important in matching pulmonary perfusion with the distribution of respiratory gas. Glyoxylic acid-histochemistry and immunohistochemistry revealed that populations of cells located in the common pulmonary artery contain the indoleamine 5-hydroxy-tryptamine. Many of the cells are intimately associated with varicose blue-green fluorescent nerves. It is proposed that the 5-hydroxytryptamine-containing cells may be involved in intravascular chemoreception.     

Vasoactive intestinal polypeptide (VIP)- and neuropeptide Y (NPY)-containing nerve fibres in the penile cavernous tissue of green monkeys (Cercopithecus aethiops)

Summary The cavernous body of green monkeys contains many unmyelinated and few myelinated axons. The unmyelinated axons form terminals in the adventitia of the arteries, between trabecular muscle cells, in the interstitium, and close to endothelium cells of the sinuses. All terminals displayed predominantly small clear vesicles and very few large granular vesicles; small granular vesicles were not seen. However, in rabbit penises, terminals with many large granular vesicles are prominent. Immunohistochemistry (PAP technique) showed a dense network of VIP- and NPY-reactive fibres around the arteries and around trabecular muscles. The density of nerve fibres was particularly high around the subendothelial cushions of the helicine arteries. Double staining for NPY and VIP revealed that both peptides were colocalized. Immunocytochemistry (preembedding PAP technique) showed VIP- and NPY-reactivity in terminals with small clear vesicles; the reaction product was bound to the cytoplasmic face of different membrane types. Although the intracellular localization of the reaction product is probably due to artefactual displacement during preparation, the uniformity of the terminals questions the view that large and small granular vesicles in all species characterize peptidergic and noradrenergic terminals, respectively. The essential findings can be summarized as (1) a high degree of uniformity of nerve terminals, (2) colocalization of VIP and NPY, (3) heavy innervation of the subendothelial cushions of the helicine arteries, and (4) possible innervation of endothelial cells.     

Localization and characterization of neuropeptide Y-like peptides in the brain and islet organ of the anglerfish (Lophius americanus)

Summary Results from a previous report demonstrate that more than one molecular form of neuropeptide Y-like peptide may be present in the islet organ of the anglerfish (Lophius americanus). Most of the neuropeptide Y-like immunoreactive material was anglerfish peptide YG, which is expressed in a subset of islet cells, whereas an additional neuropeptide Y-like peptide(s) was localized in islet nerves. To learn more about the neuropeptide Y-like peptides in islet nerves, we have employed immunohistochemical and biochemical methods to compare peptides found in anglerfish islets and brain. Using antisera that selectively react with either mammalian forms of neuropeptide Y or with anglerfish peptide YG, subsets of neurons were found in the brain that labelled with only one or the other of the antisera. In separate sections, other neurons that were labelled with either antiserum exhibited similar morphologies. Peptides from brains and islets were subjected to gel filtration and reverse-phase high performance liquid chromatography. Radioimmunoassays employing either the neuropeptide Y or peptide YG antisera were used to examine chromatographic eluates. Immunoreactive peptides having retention times of human neuropeptide Y and porcine neuropeptide Y were identified in extracts of both brain and islets. This indicates that peptides structurally similar to both of these peptides from the neuropeptide Y-pancreatic polypeptide family are expressed in neurons of anglerfish brain and nerve fibers of anglerfish islets. The predominant form of neuropeptide Y-like peptide in islets was anglerfish peptide YG. Neuropeptide Y-immunoreactive peptides from islet extracts that had chromatographic retention times identical to human neuropeptide Y and porcine neuropeptide Y were present in much smaller quantities. These results are consistent with the hypothesis that peptides having significant sequence homology with human neuropeptide Y and porcine neuropeptide Y are present in the nerve fibers that permeate the islet.     

Cellular origin and distribution of transforming growth factor-β1 in the normal rat myocardium

Summary Transforming growth factor- (TGF-) is a biologically active polypeptide present in normal tissues as well as transformed cells. Two structurally related forms of this peptide are TGF- ₁ and TGF- ₂. Using freshly isolated cardiomyocytes and non-myocyte heart cells, and a [³²P]-labelled cDNA probe to human TGF- ₁, we demonstrated that mRNA for TGF- ₁ could be detected only in the nonmyocyte fraction of heart cells. In the present study, the distribution of TGF- ₁ in the heart was determined by immunofluorescence staining by use of a polyclonal antibody to porcine TGF- ₁ in cryostat sections of rat heart. Immunofluorescence staining was intense around the blood vessels and radially diffuse in the surrounding myocardium.