Persistent effects of early odor exposure on human neonates

Human neonates were exposed to an artificial odorant for 22h within the first two days after birth. When tested on days16–18 postpartum, these infants displayed preferentialorientation to the exposure odor when paired with a novel odorant.The effects of early mere exposure on the stimulus propertiesof odors can therefore endure over a two-week interval, indicatingthat infants retain a memory trace of the exposure odor throughoutthat time period.     

A calmodulin and alpha-subunit binding domain in human erythrocyte spectrin

Human erythrocyte spectrin binds calmodulin weakly under native conditions. This binding is enhanced in the presence of urea. The site responsible for this enhanced binding in urea has now been shown to reside in a specific region of the spectrin beta-subunit. Cleavage of spectrin with trypsin, cyanogen bromide or 2-nitro-5-thiocyanobenzoic acid generates fragments of the molecule which retain the ability to bind calmodulin under denaturing conditions. The origin of these fragments, identified by two-dimensional peptide mapping, is the terminal region of the spectrin beta-IV domain. The smallest peptide active in calmodulin binding is a 10 000 Mr fragment generated by cyanogen bromide cleavage. Only the intact 74 000 Mr fragment generated by trypsin (the complete beta-IV domain) retains the capacity to reassociate with the isolated alpha-subunit of spectrin. The position of a putative calmodulin binding site near a site for subunit-subunit association and protein 4.1 and actin binding suggests a possible role in vivo for calmodulin regulation of the spectrin-actin membrane skeleton or for regulation of subunit-subunit associations. This beta-subunit binding site in erythrocyte spectrin is found in a region near the NH2-terminus at a position analogous to the alpha-subunit calmodulin binding site previously identified in a non-erythroid spectrin by ultrastructural studies.     

Limited proteolysis of the erythrocyte membrane skeleton by calcium-dependent proteinases

The action of purified calcium-dependent proteinases on human erythrocyte membrane skeleton proteins has been examined. Preferential cleavage of proteins 4.1 a and b and band 3 and limited cleavage of alpha- and beta-spectrin occur when either calcium-dependent proteinase I or calcium-dependent proteinase II has access to the cytoplasmic side of the ghost membrane skeleton in the presence of calcium. Thus, when these proteinases are incubated with sealed ghosts they do not cleave these proteins. Leupeptin, mersalyl, the specific cellular protein inhibitor of these enzymes, and calcium chelators can inhibit proteolysis of the red cell ghost proteins by Ca2+-dependent proteinases. Each proteinase has also been loaded into erythrocyte ghosts in the absence of calcium at low ionic strength and subsequently trapped inside by resealing the ghosts. The proteinases were activated by incubating these ghosts in the presence of the calcium ionophore A23187 and calcium. Examination of the ghost proteins by electrophoresis demonstrated calcium-dependent proteolysis of Bands 4.1 and 3 and limited cleavage of alpha- and beta-spectrin similar to that observed on proteolysis of the open, leaky ghosts. In the presence of calcium each calcium-dependent proteinase appears to associate with the erythrocyte ghost membrane.     

Interstrain Variation in Amylase Gene Copy Number and mRNA Abundance in Three Mouse Tissues

Amylase expression in strain YBR differs in several respects from the standard mouse phenotype. The synthesis of salivary amylase is elevated twofold in YBR mice and the synthesis of pancreatic amylase is reduced to one-half the normal rate. We have compared the concentrations of amylase mRNA in the parotid, liver and pancreas of YBR mice with those in strains A/J and C3H. We observed differences in amylase mRNA abundance which can account for the levels of amylase protein synthesis in the parotid and pancreas of these strains. Unexpectedly, the concentration of amylase mRNA in the liver of YBR mice was also higher than in the other strains. Since liver amylase is transcribed from the same gene as parotid amylase, duplication of the Amy-1 locus could account for the elevated mRNA concentration in both tissues. Quantitative analysis of genomic DNA by Southern blotting provided direct evidence for duplication of Amy-1 in strain YBR.     

Pathogenesis of the delayed phase of Rauscher virus-induced thrombocytopenia

BALB/c (H-2d) mice infected with Rauscher murine leukemia virus (RMuLV) developed two phases of thrombocytopenia: an acute phase, probably due to direct virus-platelet interactions, and a delayed phase, starting 2 to 3 wk after virus injection, which was associated with the infection of megakaryocytes by RMuLV and with the expression of RMuLV gp70 and p30 antigens on platelet membranes. This study was concerned with the pathogenesis of this second phase of thrombocytopenia. During this period, the number of marrow megakaryocytes was increased. A peripheral platelet destruction was further indicated by reduced platelet life span. It was shown that radiolabeled platelets, either normal or infected, were submitted to a more rapid clearance in infected recipients than in normal recipients. This might be due to the splenomegaly observed in infected recipients. However, the immediate clearance of gp70+ platelets was more accelerated in infected recipients with high titers of serum anti-gp70 antibodies than in infected recipients without detectable serum anti-gp70 antibodies. In addition, the passive transfer of anti-RMuLV serum to normal BALB/c mice induced a rapid and specific clearance of previously injected radiolabeled platelets expressing RMuLV antigens. In H-2d mice, viral gp70 antigen expression on platelets correlated with the development of delayed thrombocytopenia; but H-2k strains of mice, although susceptible to RMuLV and expressing RMuLV-related antigens on their platelets, did not develop any anti-RMuLV antibodies nor any delayed thrombocytopenia. These results suggest that specific clearance of gp70+ platelets in the presence of significant amounts of serum antiviral antibodies and nonspecific hypersplenism play a role in the development of delayed thrombocytopenia in RMuLV-infected mice.     

Structure of the murine serum amyloid A gene family. Gene conversion

Serum amyloid A (SAA) is an apolipoprotein produced by the liver in response to inflammation; the levels of SAA mRNA and SAA protein increase at least 500-fold within 24 h. We have obtained clones of all three genes and pseudogene that make up the murine SAA gene family. Two of the genes have 96% sequence homology over their entire length, including introns and flanking sequences 288 base pairs (bp) 5' and 443 bp 3' to the genes: an overall length of 3215 bp. The sharp boundaries between homologous and nonhomologous sequences and the absence of interspersed repeated sequences there suggest that conversion has occurred between these two genes. The homologous regions are bounded by short inverted repeats containing alternating purine and pyrimidine residues, as described for other gene conversion units. The third SAA gene has evolved separately, although all are closely linked on chromosome 7. Comparison of the upstream regions of the SAA genes with those of the rat fibrinogen genes, whose expression is also induced by inflammation, reveals sequences common to all six genes which are very improbable on a random basis.     

k-Binding and Degradation of [3H]Dynorphin A (1–8) and [3H]Dynorphin A (1–9) in Suspensions of Guinea Pig Brain Membranes

Following incubation of [3H]dynorphin A (1-8) and [3H]dynorphin A (1-9) with suspensions of guinea pig brain membranes, analysis of the supernatants by HPLC has shown that both peptides are degraded at 25 degrees C and at 0 degrees C. Bestatin and captopril reduce degradation at 0 degrees C but for a similar degree of protection at 25 degrees C arginine-containing dipeptides are also required. The effects of these peptidase inhibitors on the degradation profiles indicate that [3H]dynorphin A (1-8) has three main sites of cleavage: the Tyr1-Gly2, Arg6-Arg7, and Leu5-Arg6 bonds. With [3H]dynorphin A (1-9) as substrate the Arg7-Ile8 and Ile8-Arg9 bonds are also liable to cleavage. In binding assays, in contrast to the effects of peptidase inhibitors on the degradation of unbound [3H]dynorphin A (1-8) and [3H]dynorphin A (1-9), bestatin and captopril have little effect on the binding characteristics of the tritiated dynorphin A fragments at the kappa-site at 0 degrees C. However, at 25 degrees C binding is low in the absence of peptidase inhibitors. When binding at mu- and delta-sites is prevented, the maximal binding capacities of [3H]dynorphin A (1-8), [3H]dynorphin A (1-9), and [3H](-)-bremazocine at the kappa-site are similar; [3H]dynorphin A (1-9) has 5-10 times higher affinity for the kappa-site than [3H]dynorphin A (1-8). Comparison of the effects of peptidase inhibitors on unbound dynorphin A fragments with their effects in binding assays suggests that the bound peptides are protected from the action of peptidases.     

The oral assimilation of radiomanganese by the mouse

The metabolism of orally administered radiomanganese was studied in mice. Assimilation of absorbed manganese (Mn) was determined using whole body counting techniques. When⁵⁴MnCl₂ was administered, 2.7% of the dose was retained after 10 d compared with 1.2% from the⁵⁴Mn-nitrilotriacetate (NTA) complex. However, this difference was accounted for by the rapid and persistent adsorption of the Mn onto the teeth of the lower jaw when fed as the ionic salt at pH 2.0 compared with the NTA-chelate fed at pH 9.0. Once corrected for the amount adsorbed onto the teeth, the biodistribution and relative specific activity of the assimilated radiomanganese into a variety of tissues were similar for both forms of the metal.     

Extraction and Partial Characterization of Enkephalin-Like Peptides from Splanchnic Nerve

A method is described for the extraction of enkephalin-like peptides from peripheral nerve using chloroform and acidic methanol to facilitate a differential extraction of peptides and lipid. Porcine splanchnic nerve contains enkephalin-like peptides in low amounts compared to porcine adrenal medulla and striatum. Gel filtration chromatography reveals the presence of enkephalin-like peptides in both processed and cryptic forms. This is the first reported isolation and partial characterization of these peptides in splanchnic nerve. The presence of these peptides in this nerve provides support for the contention that the splanchnic nerve can modulate catecholamine release from the adrenal medulla through an effect on opiate receptors located on chromaffin cells.