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.     

Nanoplanktonic coccolithophorids (Prymnesiophyceae, Haptophyceae) from the Weddell Sea, Antarctica

The examination of whole mounts prepared for transmission electron microscopy has resulted in the finding of thirteen taxa of nanoplanktonic coccolithophorids from the Weddell Sea, Antarctica. The material was collected as part of the AMERIEZ programme, March 1986. Cold-water adapted nanoplanktonic coccolithophorids have previously been shown to constitute a recurrent plankton element at subarctic and arctic localities. Three of the Weddell Sea species, Wigwamma annulifera, W. arctica , and Papposphaera sagittifera , are conspecific with northern hemisphere material, while two species, Calciarcus alaskensis and Turrisphaera arctica , are possibly identical with previously described arctidsubarctic material. Six taxa new to science have been described from the Weddell Sea, Wigwamma antarctica, W. triradiata, Trigonaspis melvillea, Pappomonas weddellensis, Papposphaera obpyramidalis , and P. simplicissima . The cooccurrence of identical forms at the two poles, and the fact that the species described are allocated to "arctic" genera, indicate a geologically relatively recent exchange of biological material between the poles.     

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.     

MTOCs in higher plant cells: an immunofluorescent study of microtubule assembly sites following depolymerization by APM

Summary A one hour exposure to 3 M amiprophos-methyl (APM) depolymerizes all MT arrays in cells from higher plant suspension cultures. On removal of APM, MT repolymerization sites are detected using immunofluorescent staining. During interphase, Mt arrays return uniformly dispersed across the cell cortex with transverse arrays in elongated cells and random arrays in isodiametric cells. During cell division, MT arrays return as follows: Prophase-MT arrays return in association with the nuclear envelope. Metaphase-MTs return associated with chromosomes. Teleophase-MTs return in apparent association with the reforming nuclear envelope and as aberrant phragmoplasts. MTOCs in higher plant cells may be membrane associated at many stages in the cell cycle. Isolated, condensed chromosomes are capable of nucleating MTs, which can attain small, spindle-like configurations.Abbreviations APM Amiprophos-methyl - MT Microtubule - MTOC Microtubule organizing center - NS Nucleating site     

Uses of 3D planning in addition to creating a good treatment: Ongoing studies at MGH/HCL

Summary Ongoing studies and 3D treatment planning and its clinical impact will be described.Invited paper given on the fourth workshop on Heavy Charged Particles in Biology and Medicine GSI, Darmstadt, FRG, September 23–25, 1991