Estimation of the Number of Sex Alleles and Queen Matings from Diploid Male Frequencies in a Population of APIS MELLIFERA

The distribution of diploid males in a population of Apis mellifera was obtained by direct examination of the sexual phenotypes of the larvae. Using these data, estimates are derived for the number of sex alleles and the number of matings undergone by the queen. The number of sex alleles is estimated to be 18.9. The estimate is larger than previous ones, which have ranged between 10 and 12. However, the increase in the number of sex alleles can be explained by the large effective population number for our data. The best estimator of the number of matings by a queen is a maximum likelihood type that assumes a prior distribution on the number of matings. For the data presented here, this estimate is 17.3. This estimate is compared to others in the literature obtained by different approaches.     

ALTERATIONS IN THE BINDING OF [3H]LEUCINE-ENKEPHALIN TO STRIATAL MEMBRANES BY ENDOGENOUS FACTORS

—Saturation binding studies with [³H]leu-enk ([tyrosyl-3, 5-³H(N)]⁵leu-enkephalin) revealed the presence of high and low affinity binding sites in a paniculate fraction derived from rat striatum. The binding of [³H]leu-enk to the high affinity component (K_D= 2.0 ± 0.3 nM) was sensitive to morphine and levorphanol, while the binding to the low affinity component (K_D= 21 ± 2 nM) was not. Incubation of the membranes, prior to assay for 30 min at 37°C, followed by centrifugation at 27, 000 g for 20 min in order to pellet the membranes allowed the detection of a factor, present in the high speed supernatant, which caused a dose-dependent inhibition of the binding of [³H]leu-enk to the morphine-sensitive and insensitive binding components. Investigations into the nature of the morphine-insensitive binding component demonstrated that it was an artifact since it was not detectable when bound and free ligand were separated by centrifugation. Furthermore, [³H]leu-enk bound to Whatman glass fiber filters, used to collect bound ligand, in a morphine-insensitive manner, and under conditions where the binding of [³H]leu-enk to the morphine sensitive component diluted proportionally with serial dilutions of the membranes, the binding to the morphine-insensitive component did not. The factor present in the high speed supernatant did not dialyze and its effects were mimicked by either trypsin or soybean trypsin inhibitor, but not by bovine serum albumin. The apparent inhibition of the binding of [³H]leu-enk to these binding components is probably not of biological significance, but the fact that the artifactual morphine insensitive binding component of striatal membranes has been shown to decrease by 20–30% following lesions of the substantia nigra suggests that the influence of this endogenous factor must be controlled for.     

Human T cell activation by OKT3 is inhibited by a monoclonal antibody to CD44.

The CD44 molecule, also known as Hermes lymphocyte homing receptor, human Pgp-1, and extracellular matrix receptor III, has been shown to play a role in T cell adhesion and activation. Specifically, anti-CD44 mAb block binding of lymphocytes to high endothelial venules, inhibit T cell-E rosetting, and augment T cell proliferation induced by the CD2 or CD3-TCR pathways. We have characterized an anti-CD44 mAb (212.3) which immunoprecipitates a 90-kDa protein and is specific for CD44 as shown by peptide mapping and antibody competition studies. Interestingly, our studies with 212.3 demonstrate that this CD44-specific mAb completely inhibits T cell proliferation stimulated by the anti-CD3 mAb, OKT3. Inhibition is not a result of reduced cell viability, but is associated with 1) inhibition of IL-2 production, 2) inhibition of IL-2R expression, and 3) inhibition of OKT3-mediated increases in intracellular Ca2+ levels. In addition, 212.3 does not inhibit proliferation by the T cell mitogens PHA or PWM nor does it inhibit proliferation in a mixed lymphocyte reaction. Similar to other anti-CD44 mAb, 212.3 also augments T cell proliferation induced by mAb directed against the T11(2) and T11(3) epitopes of CD2. Thus, these studies describe a novel CD44-specific mAb (212.3) that inhibits T cell activation by OKT3 by blocking early signal transduction. Furthermore, these studies suggest that "receptor cross-talk" between the CD3-TCR complex and CD44 may regulate T cell activation.     

Gamma-COP, a coat subunit of non-clathrin-coated vesicles with homology to Sec21p.

Constitutive secretory transport in eukaryotes is likely to be mediated by non-clathrin-coated vesicles, which have been isolated and characterized [(1989) Cell 58, 329-336; (1991) Nature 349, 215-220]. They contain a set of coat proteins (COPs) which are also likely to exist in a preformed cytosolic complex named coatomer [(1991) Nature 349, 248-250]. From peptide sequence and cDNA structure comparisons evidence is presented that one of the subunits of coatomer, gamma-COP, is a true constituent of non-clathrin-coated vesicles, and that gamma-COP is related to sec 21, a secretory mutant of the yeast Saccharomyces cervisiae.     

Biological activities of peptides and peptide analogues derived from common sequences present in thrombospondin, properdin, and malarial proteins

Thrombospondin (TSP), a major platelet-secreted protein, has recently been shown to have activity in tumor cell metastasis, cell adhesion, and platelet aggregation. The type 1 repeats of TSP contain two copies of CSVTCG and one copy of CSTSCG, per each of the three polypeptide chains of TSP and show homology with peptide sequences found in a number of other proteins including properdin, malarial circumsporozoite, and a blood-stage antigen of Plasmodium falciparum. To investigate whether these common sequences functioned as a cell adhesive domain in TSP, we assessed the effect of peptides corresponding to these sequences and an antibody raised against one of these sequences, CSTSCG, in three biological assays which depend, in part, on the cell adhesive activity of TSP. These assays were TSP-dependent cell adhesion, platelet aggregation, and tumor cell metastasis. We found that a number of peptides homologous to CSVTCG promoted the adhesion of a variety of cells including mouse B16-F10 melanoma cells, inhibited platelet aggregation and tumor cell metastasis, whereas control peptides had no effect. Anti-CSTSCG, which specifically recognized TSP, inhibited TSP-dependent cell adhesion, platelet aggregation, and tumor cell metastasis, whereas control IgG had no effect. These results suggest that CSVTCG and CSTSCG present in the type I repeats function in the adhesive interactions of TSP that mediate cell adhesion, platelet aggregation, and tumor cell metastasis. Peptides, based on the structure of these repeats, may find wide application in the treatment of thrombosis and in the prevention of cancer spread.     

Structure-activity relationship of the neurotransmitter alpha-bag cell peptide on Aplysia LUQ neurons: implications regarding its inactivation in the extracellular space.

Alpha-bag cell peptide [alpha-BCP (Ala-Pro-Arg-Leu-Arg-Phe-Tyr-Ser-Leu)] is a neurotransmitter that mediates bag cell-induced inhibition of left-upper-quadrant (LUQ) neurons L2, L3, L4, and L6 in the abdominal ganglion of Aplysia. Our recent biochemical studies have shown that alpha-BCP[1-9] is cleaved into alpha-BCP[1-2], [3-9], [1-5], [6-9], and [7-9] by a combination of three distinct peptidase activities located within the extracellular spaces of the CNS: A diaminopeptidase-IV (DAP-IV)-like enzyme cleaves alpha-BCP[1-9] at the 2-3 peptide bond; a neutral metalloendopeptidase (NEP)-like enzyme cleaves either alpha-BCP[1-9] or alpha-BCP[3-9] at the 5-6 bond; an aminopeptidase M-II (APM-II)-like enzyme cleaves alpha-BCP[6-9] at the 6-7 bond, but cleaves neither alpha-BCP[1-9], nor the other ganglionic peptidase products. To further understand the manner in which alpha-BCP is inactivated after release, that is loses its electrophysiological activity, we studied its structure-activity relationship by recording intracellularly from LUQ neurons in isolated abdominal ganglia that were arterially perfused with peptides dissolved in artificial sea water. The effects of alpha-BCP[1-9] and 15 of its fragments ([1-8], [1-7], [1-6], [1-5], [2-9], [3-9], [3-8], [6-9], [7-9], [8-9], [6-7], [6-8], [1-2], Phe, Tyr) indicated that the sequence Phe6-Tyr7 was both necessary and sufficient to produce LUQ inhibitory activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

The yeast SEC17 gene product is functionally equivalent to mammalian alpha-SNAP protein.

The SEC17 gene of Saccharomyces cerevisiae is required for vesicular transport between the endoplasmic reticulum and the Golgi apparatus. Here we report that the product of the SEC17 gene has the exact biochemical properties expected for a yeast homologue of the mammalian transport factor, alpha-SNAP. The DNA sequence of SEC17 codes for a protein of predicted molecular mass of 33 kDa. Immunoblotting indicates that Sec17p fractionates as a peripheral membrane protein and is mostly soluble when overexpressed, suggesting the presence of a saturable membrane receptor for Sec17p. Sec17p was purified from yeast cytosol using a SNAP-dependent in vitro mammalian Golgi transport assay. Kinetic analysis using this assay shows Sec17p acts temporally close to the fusion of transport vesicles with the medial Golgi compartment. In yeast extracts, Sec17p binds to Sec18p with a 1:1 stoichiometry. The interaction between Sec17p and Sec18p requires an activity provided by yeast membranes, and this putative membrane receptor activity is not extracted by high salt treatment of membranes.     

Stretch increases inositol trisphosphate and inositol tetrakisphosphate in cultured pulmonary vascular smooth muscle cells.

There are no reports of the effect of stretch on inositol phosphates in smooth muscle. Phosphoinositide and inositol phosphate metabolism was studied in cultured rat vascular smooth muscle cells subjected to stretching. The masses of inositol trisphosphate and tetrakisphosphate increased (+34 +/- 7% and +58 +/- 12%, respectively; p less than 0.001) after 25 s of a single 20% stretch and had returned to control levels by 45 s; phosphatidylinositol, phosphatidylinositol phosphate and bisphosphate did not change. Repetitive stretch did not alter the masses of any of the compounds. A single stretch also increased 45Ca2+ efflux (+52 +/- 5%, p less than 0.01). These data suggest that stretch of cultured vascular smooth muscle can elicit a rapid, short-lived increase in inositol phosphates, which may subsequently affect Ca2+.     

Nonparallel transport and mechanisms of secretion.

After many years of controversy, it is now clear that at least some cells and tissues that secrete more than one product can vary the composition of the secreted mixture as the result of the differential transport of various substances out of the cells that secrete them. In this article we discuss this phenomenon, non-parallel transport or secretion, and how it has and continues to inform us about how cells release the products they manufacture. We focus on expression of the phenomenon in the secretion of digestive enzymes by the exocrine pancreas, where it has been studied most extensively.