Mosquito oostatic factor: a novel decapeptide modulating trypsin-like enzyme biosynthesis in the midgut

A peptide that inhibits egg development in mosquitoes (oostatic factor) has been purified from the ovaries of female Aedes aegypti. The factor is a decapeptide with a molecular mass of 1047.6. The primary sequence has been determined as NH2-Tyr-Asp-Pro-Ala-Pro-Pro-Pro-Pro-Pro-Pro-COOH from mass spectra recorded on a quadrupole Fourier transform instrument. The amino acid sequence exhibits sequence correlation to mammalian, plant, and several viral proteins. Injection of synthetic analogs into mosquitoes, biting midges, flies, and fleas inhibited proteolytic enzyme biosynthesis in the midgut. Binding studies with [3H]oostatic factor indicated that the midgut epithelial cells have a factor-specific receptor.     

Hensen's node,but not other biological signallers,can induce supernumerary digits in the developing chick limb bud

Summary The purpose of this study was to determine whether the organizer regions of early avian and amphibian embryos could induce supernumerary (SN) wing structures to develop when they were grafted to a slit in the anterior side of stage 19–23 chick wing buds. Supernumerary digits developed in 43% of the wings that received anterior grafts of Hensen's node from stage 4–6 quail or chick embryos; in addition, 16% of the wings had rods of SN cartilage, but not recognizable SN digits. The grafted quail tissue did not contribute to the SN structures. When tissue anterior or lateral to Hensen's node or lateral pieces of the area pellucida caudal to Hensen's node were grafted to anterior slits, the wings usually developed normally. No SN structures developed when Hensen's nodes were grafted to posterior slits in chick wing buds. Wings developed normally when pieces of the dorsal lip of the blastopore from stage 10–11.5 frog (Xenopus laevis and Rana pipiens) embryos were grafted to anterior slits. No SN digits developed when other tissues that have limb-inducing activity in adult urodele amphibians [chick otic vesicle, frog (Rana pipiens) lung and kidney] or that can act as heteroinductors in neural induction (rat kidney, lung, submaxillary gland and urinary bladder; mouse liver and submaxillary gland) were grafted to anterior slits in chick wing buds. SN digits also failed to develop following preaxial grafts of chick optic vesicles. These results suggest that although the anteroposterior polarity of the chick wing bud can be influenced by factors other than the ZPA (e.g., Hensen's node, retinoids), the wing is not so labile that it can respond to a wide variety of inductively-active tissues.     

Structural models of the evolutionarily conservative central domain of silk-moth chorion proteins

Silk-moth chorion proteins belong to a small number of families: A, B, C, Hc-A and Hc-B. The central domain is an evolutionarily conservative region in each family, of variable length and composition between families. This domain shows clear 6-fold periodicities for various amino acid residues, e.g. glycine. The periodicities, together with the well-documented prevalence of beta-sheet and beta-turn secondary structure of chorion proteins, strongly support a structural model in which four-residue beta-strands alternate with beta-turns, forming a compact antiparallel, probably twisted beta-sheet. Conformational analysis, aided by interactive graphics refinement and recent experimental findings, further suggest that this structure consists of beta-strands, alternating with I' and II' beta-turns, and apparently forms the basis for the molecular and supramolecular assembly of chorion.     

Lipoprotein metabolism in hepatic lipase deficiency: studies on the turnover of apolipoprotein B and on the effect of hepatic lipase on high density lipoprotein

Hepatic lipase deficiency produces significant distortion in the plasma lipoprotein profile. Particles with reduced electrophoretic mobility appear in very low density lipoprotein (VLDL). Intermediate density lipoprotein (IDL) increases markedly in the circulation and plasma low density lipoprotein (LDL) levels fall. At the same time there is a mass redistribution within the high density lipoprotein (HDL) spectrum leading to dominance in the less dense HDL2 subfraction. The present study examines apolipoprotein B turnover in a patient with hepatic lipase deficiency. The metabolism of large and small very low density lipoproteins was determined in four control subjects and compared to the pattern seen in the patient. Absence of the enzyme did not affect the rate at which large very low density lipoproteins were converted to smaller particles within this density interval (i.e., of VLDL). However, subsequent transfer of small very low density lipoproteins to intermediate density particles was retarded by 50%, explaining the abnormal accumulation of VLDL in the patient's plasma. Despite this, intermediate density particles accumulated to a level 2.4-times normal because their subsequent conversion to low density lipoprotein has been almost totally inhibited. Consequently, the plasma concentration of low density lipoprotein was only 10% of normal. On the basis of these observations, hepatic lipase appears to be essential for the conversion of small very low density and intermediate density particles to low density lipoproteins. The pathways of direct plasma catabolism of these species were not affected by the enzyme defect. In vitro studies were performed by adding purified hepatic lipase to the patient's plasma.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo administration with IL-1 accelerates the development of collagen-induced arthritis in mice

In an attempt to examine the in vivo proinflammatory properties of IL-1, the effects of rIL-1 beta on the development of collagen-induced arthritis in mice were investigated. The results presented in this paper demonstrated that the administration of rIL-1 beta via mini-osmotic pumps into DBA/1 mice which were suboptimally immunized with native chick type II collagen (NcII) markedly accelerated the onset as well as the progression of the arthritic disease. When IL-1-containing osmotic pumps were s.c. implanted onto mice 18 days post-collagen immunization, clinical signs of arthritis appeared within 3 to 4 days after the implant with the pumps. Maximal incidence of arthritis which was usually 80 to 100% occurred between the 6th and 7th day after the administration of rIL-1 beta. Histologic analyses revealed that the knee and ankle joints from mice which were treated with rIL-1 beta for 7 days were most severely and consistently affected. Furthermore, these IL-1-treated mice exhibited granulocytic hyperplasia within the marrow as well as marked peripheral blood neutrophilia. By contrast, arthritis was not observed during the 7-day course of the IL-1 study in the following control groups: 1) mice that were only immunized with NcII, and 2) collagen-immunized mice which received osmotic pumps containing PBS. A substantial number of these collagen-immunized mice which were not treated with IL-1 eventually developed arthritis but at later times after the incidence of arthritis had peaked in the IL-1-treated group. In addition, unimmunized mice failed to develop arthritis upon treatments with IL-1 beta. Moreover, the humoral responses to NcII were not altered in the IL-1-treated mice. Thus, these in vivo studies suggest that IL-1 is potentially capable of triggering the various inflammatory events of collagen-induced arthritis, and thereby, contribute to the pathogenesis of murine arthritis.     

Preservation of the ability of dissociated quail wing bud mesoderm to elicit a position-related differentiative response

Previous studies showed that grafting wedges of fresh or cultured anterior quail wing mesoderm into posterior slits in chick wing buds resulted in the formation of supernumerary cartilage in a high percentage of cases. When anterior quail mesoderm, which had been dissociated into single cells and pelleted by centrifugation, was grafted into posterior slits of host chick wing buds, supernumerary rods or nodules of cartilage formed in 74.3% of the cases. Few supernumerary skeletal structures formed following control operations in which pelleted dissociated anterior or posterior mesoderm was grafted into homologous locations in host chick wing buds. When pelleted, dissociated anterior mesoderm was cultured in vitro for 1 or 2 days prior to being implanted in posterior locations, the incidence of supernumerary cartilage formation increased to 95.5% and 93.8%, respectively. The incidence of supernumerary cartilage formation following control orthotopic grafts of cultured mesoderm was 11.8% for 1-day and 31% for 2-day cultured anterior mesoderm; for 1- and 2-day cultured posterior mesoderm, the incidence of supernumerary cartilage formation was 20% and 41.7%, respectively. Longer-term culture resulted in a substantial decrease in the percentage of supernumerary cartilage after anterior to posterior grafts and an increase in the incidence of supernumerary cartilage from control grafts. The results demonstrate that quail anterior wing bud mesodermal cells do not need to maintain constant contact with one another in order to retain the ability to form or stimulate the formation of supernumerary cartilage after being grafted into a posterior location in a host wing bud. This ability is retained when the pelleted dissociated mesoderm is cultured in vitro outside the limb field for at least 1 to 2 days.