The occurrence and distribution of certain polypeptides within the human carotid body

Summary Both carotid bodies from 26 patients coming to necropsy were fixed in 10% neutral buffered formalin and sections 4 m thick were stained for various peptides by use of the immunogold technique. The results show that the human carotid body contains met- and leu-enkephalin, substance P, vasoactive intestinal peptide (VIP), neurotensin and bombesin. The distribution of these six peptides within the carotid body differs. Thus met- and leu-enkephalin are both present predominantly within glomic chief cells but with a marked tendency to favour the dark variant of these cells. Substance P and VIP both show a weak immunoreactivity in comparison to the enkephalins and are present in all three variants of chief cell. Neurotensin shows the weakest immunoreactivity of all and is restricted to a few glomic chief cells in a minority of cases. Bombesin also shows a weak immunoreactivity in glomic chief cells but a strong reaction in glomic arteries and arterioles. In these vessels bombesin appears to be confined to smooth muscle cells in the media but we cannot say whether it is secreted by them or merely bound to receptor sites on their membranes. These findings are related to quantitative data on the concentration of peptides in the human carotid body from a previous paper with which we were associated.     

Effects of substrata on the polarization of bovine endometrial epithelial cells in vitro

Summary Epithelial-cell function requires cellular polarity in which apical membrane surfaces have unique characteristics and cellular organelles are stratified. Physiological investigations of endometrial, epithelial cells would be enhanced greatly by the ability of a method to polarize cells in culture. This study investigates the effects of different substrata on polarization of cultured bovine endometrial epithelial cells. Fetal bovine endometrial epithelial-cell lines were developed from explant outgrowth. Epithelial monolayers were subcultured onto amniotic membranes, Millicell-HA membranes, or Millicell-CM membranes coated with rat-tail collagen, Matrigel, laminin, Vitrogen,or fibronectin. Cultures on these substrata were maintained at the air/liquid interface. Cells grown on either collagen-coated or uncoated Milli-cell membranes also were maintained submerged in medium. Excellent polarized morphology was attained in cultures grown at the air/liquid interface on amniotic membranes and rat-tail collagen-coated membranes. Lectin-binding patterns, to apical membranes of polarized epithelial cell cultures paralleled patterns of binding to bovine endometrial surfaces in vivo. Cultures on rat-tail collagen were maintained for several weeks. These methods provide a valuable system for studying the endometrium in vitro.     

Structural and compositional analyses of the phycobilisomes of Synechococcus sp. PCC 7002. Analyses of the wild-type strain and a phycocyanin-less mutant constructed by interposon mutagenesis

The phycobilisomes and phycobiliproteins of Synechococcus sp. PCC 7002 wild-type strain PR6000 have been isolated and characterized. The hemidiscoidal phycobilisomes of strain PR6000 are composed of eleven different polypeptides: phycocyanin and subunits; allophycocyanin and subunits; subunit of allophycocyanin B; the allophycocyanin -subunit-like polypeptide of M_r 18 000; the linker phycobiliprotein of M_r 99 000; and non-chromophore-carrying linker polypeptides of M_r 33 000, 29 000, 9000, and 8000. Several of these polypeptides were purified to homogeneity and their amino acid compositions and amino-terminal amino acid sequences were determined. Analyses of the phycobiliproteins of Synechococcus sp. PCC 7002 were greatly facilitated by comparative studies performed with a mutant strain, PR6008, constructed to be devoid of the phycocyanin and subunits by recombinant DNA techniques and transformation of strain PR6000. The absence of phycocyanin did not greatly affect the allophycocyanin content of the mutant strain but caused the doubling time to increase 2–7-fold depending upon the light intensity at which the cells were grown. Although intact phycobilisome cores could not be isolated from this mutant, it is probable that functionally intact cores do exist in vivo.Abbreviations used SDS-PAGE polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate - 2D-PAGE two-dimensional gel electrophoresis in which the first dimension consisted of isoelectric focusing in the presence of 8.0 M urea in the pH range 4–6 and the second dimension consisted of electrophoresis in the presence of sodium dodecylsulfate. The nomenclature employed for the phycobiliprotein subunits and linker polypeptides is that defined by Glazer (1985)     

The effect of salinity on the composition of fatty acid double-bond isomers andsn-1/sn-2 positional distribution in membrane phospholipids of a moderately halophilic eubacterium

We report the first study of the effect of NaCl on the double-bond isomeric composition of fatty acids and theirsn-1/sn-2 positional distribution in the membrane phospholipids of a moderately halophilic eubacterium. The major phospholipids, phosphatidylethanolamine and phosphatidylglycerol, ofVibrio costicola grown in 1M or 3M NaCl both have ansn-1 saturated,sn-2 unsaturated distribution of fatty acids. There is a greater effect of salinity on the fatty acid composition of phosphatidylglycerol compared with phosphatidylethanolamine. The fatty acids in phosphatidylethanolamine of cultures grown in 1M compared with 3M NaCl have the same unsaturation index and average chain length, but different double-bond isomeric compositions. In comparison, the fatty acid composition of phosphatidylglycerol is more unsaturated, with a different double-bond isomeric distribution, and has a shorter average chain length in cultures grown in 3M compared with 1M NaCl. The pattern of fatty acid isomers of 16:1 and 18:1 shows thatV. costicola uses the anaerobic pathway of fatty acid biosynthesis. The presence of the isomers 16:1c11 and 18:1c13 in the phospholipids of cultures grown in 3M but not in 1M NaCl indicates that external salinity affects the specificity of fatty acid synthetase in this moderately halophilic bacterium.     

Ultrastructure of pericytes in early stages of histamine-induced inflammation

Physiological and ultrastructural assessment of changes in the walls of venules in the rat cremaster muscle after administration of histamine indicates that pericytes have essential roles in the normal functioning of venules during inflammation. Fluorescein-labelled albumin was used to quantitate macromolecular leakage and to select suitable venules for ultrastructural analysis 4 and 7 minutes after addition of histamine. Pericytes were concentrated over endothelial cell junctions and gaps. At 4 minutes, when albumin leakage was becoming detectable, gaps between endothelial cells were observed in the venule wall. In 24 serially sectioned gaps, pericytes formed covers, with contact points to the endothelial cells along the sides of the gaps. At 7 minutes, when albumin leakage was maximal, gaps with pericyte covers were still evident, but more commonly observed were pericyte covers over closed endothelial cell junctions. Spaces between the innermost pericytes and endothelial cells were enlarged by an order of magnitude, from 95 nm in controls to 872 nm at 4 minutes and 958 nm at 7 minutes. Pericytes formed coverings or bridges over inclusions of extravasated cells, fluid, proteins, and the vascular label monastral blue. The data indicate that pericytes protect the endothelial lining of venules during histamine-induced inflammation by forming a cohesive covering across gaps.     

Light-evoked walking in crayfish: Behavioral and neuronal responses triggered by the caudal photoreceptor

The caudal photoreceptors (CPRs) of crayfish (Procambarus clarkii) can trigger walking and abdominal movements by their response to light.

Localization of Usher syndrome type II to chromosome 1q

Usher syndrome is characterized by congenital hearing loss, progressive visual impairment due to retinitis pigmentosa, and variable vestibular problems. The two subtypes of Usher syndrome, types I and II, can be distinguished by the degree of hearing loss and by the presence or absence of vestibular dysfunction. Type I is characterized by a profound hearing loss and totally absent vestibular responses, while type II has a milder hearing loss and normal vestibular function. Fifty-five members of eight type II Usher syndrome families were typed for three DNA markers in the distal region of chromosome 1q: D1S65 (pEKH7.4), REN (pHRnES1.9), and D1S81 (pTHH33). Statistically significant linkage was observed for Usher syndrome type II with a maximum multipoint lod score of 6.37 at the position of the marker THH33, thus localizing the Usher type II (USH2) gene to 1q. Nine families with type I Usher syndrome failed to show linkage to the same three markers. The statistical test for heterogeneity of linkage between Usher syndrome types I and II was highly significant, thus demonstrating that they are due to mutations at different genetic loci.     

Purification and properties of theDrosophila zen protein

Summary The zen protein is encoded by the zerknullt gene required for normal early development inDrosophila. Like many regulatory proteins of this type, zen contains a 60 amino acid homeobox sequence. We have purified the zen protein and studied its solution behavior and its interaction with DNA. The zen protein exists as a monomer in solution with a molecular weight of about 40000. It binds specifically to a site about 900 bases upstream from thezen gene. Within this binding site DNase protection experiments indicate that binding is confined to two regions approximately 11 and 14 bases in length that are separated by about 30 base pairs. The protein concentration dependence of the binding curve suggests that protein binding is non cooperative.     

Post-receptor modulation of the effects of cyclic AMP in isolated cardiac myocytes

Summary The actions of cyclic AMP are subject to several levels of post-receptor modulation in cardiac tissue. Isoproterenol and prostaglandin E₁ both stimulate cAMP accumulation, but only isoproterenol causes activation of particulate cAMP-dependent protein kinase, leading to activation of phosphorylase kinase and glycogen phosphorylase, and inhibition of glycogen synthase. Through the use of isolated, adult ventricular myocytes, we have determined that the hormone-specific activation of glycogen phosphorylase is due to subcellular compartmentation of cAMP. There is some evidence that cyclic nucleotide phosphodiesterases, whose activity is stimulated by alpha₁-adrenergic agonists in isolated myocytes, may have a role in compartmentation. Phosphoinositide hydrolysis is stimulated by alpha, and muscarinic agonists, presumably leading to activation of protein kinase C, which in turn has multiple effects on hormone-sensitive adenylate cyclase.Abbreviations cAMP Adenosine-3,5-Cyclic Monophosphate - cGMP Guanosine-3,5-Cyclic Monophosphate - G_i, G_S Guanine nucleotide-binding proteins linked to inhibition and stimulation, respectively, of adenylate cyclase - GTP Guanosine-5-triphosphate - PDE Cyclic Nucleotide Phosphodiesterase - PGE₁ Prostaglandin E₁     

Homozygous osteogenesis imperfecta unlinked to collagen I genes

Summary In a consanguineous pedigree in which a severe type of osteogenesis imperfecta was segregating as an autosomal recessive trait, analysis of genetic markers for both collagen I structural loci COL1A1 and COL1A2 showed that the phenotype was unlinked to either locus.