Chemosystematics and taxonomy of Ambrosia chamissonis

Specimens of the variable strand ragweeds of the Pacific Coasts of North and South America have commonly been divided among two or more specific or subspecific taxa. The results of this study indicate that they comprise a single heteromorphic and chemically variable species, Ambrosia chamissonis (Less.) Greene. Morphological and chemical variants within the complex show no overall correlation, and variation within and between populations is such as to suggest specific continuity. Less variable populations south of California's Monterey Peninsula appear to be derived from limited introductions from the north, and to owe their relative uniformity to genetic drift and development from limited progenitor stock. Genetic drift linked to self-pollination is evident within populations and within progeny groups developed from naturally produced seed, and is here termed ‘ethological drift’. Two varieties are recognized within the species: var. cuneifolia is found near and north of the mouth of the Columbia River. and is characterized by relatively large fruiting involucres with flattened spines and a tendency for unlobed leaves and pilose pubescence; var. chamissonis, with smaller involucres and basally inflated or terete spines, is found throughout the remainder of the range, and includes two intergrading forms—forma chamissonis with unlobed leaves and forma bipinnatisecta with pinnately decompound leaves.     

Synergistic inhibition of cell-to-cell HIV-1 infection by combinations of single chain variable fragments and fusion inhibitors

Cell-to-cell spread of HIV permits ongoing viral replication in the presence of antiretroviral therapy and is suggested to be a major contributor to sexual transmission by mucosal routes. Fusion inhibitors that prevent viral entry have been developed, but their clinical applications have been limited by weak antiviral activity, short half-life, and the low genetic barrier to development of resistance. We examined the inhibitory activities of a series of single-chain variable fragments (scFvs) targeting the V3 and CD4i epitopes against both cell-free and cell-to-cell HIV infection. We found that all anti-V3 scFvs, including two newly constructed scFvs, showed broad neutralization activity against a panel of subtype B viruses compared with the corresponding IgGs. All scFvs neutralized cell-free infection by HIV-1_{JR-FL WT} and fusion inhibitor-resistant mutants. In addition, all anti-V3 scFvs and some CD4i scFvs significantly inhibited cell fusion, while their IgG counterparts did not. Furthermore, scFvs-fusion inhibitors combinations, such as C34 and SC34, showed synergistic inhibition of cell fusion by both HIV-1_{JR-FL WT} and fusion inhibitor-resistant mutants. The most prominent combinational effect was observed for 916B2 CD4i scFv with SC34. The delayed fusion kinetics of fusion inhibitor-resistant mutants partly explain their synergistic inhibition by such combinations. Our data demonstrate the advantages of using scFvs over their parent IgGs for inhibiting both cell-free and cell-to-cell infection. High synergistic inhibition of cell fusion by using scFvs-fusion inhibitors combinations suggests the possibility of intensification therapy adding this combination to current anti-HIV treatment regimens.     

Simultaneous use of 1-hydroxybenzotriazole and copper(II) chloride as additives for racemization-free and efficient peptide synthesis by the carbodiimide method.

In the carbodiimide mediated coupling of Z-Gly-L-Val-OH with H-L-Val-OMe in DMF, the simultaneous use of HOBt and copper(II) chloride as additives was found to give the desired peptide in a high yield without racemization. In the presence of HOBt, reducing the amount of copper(II) chloride produced a higher yield. Besides improving the coupling efficiency as compared with the case using copper(II) chloride alone as an additive, the present procedure offered another advantage for racemization suppression. Thus, even for the couplings where a low level of racemization was observed in the presence of copper(II) chloride, the simultaneous addition of HOBt and copper(II) chloride resulted in the elimination of racemization. The effectiveness of this new procedure using the two carbodiimide additives in the synthesis of biologically active peptides was assessed by the preparation of a protected Leu-enkephalin. In the 4 + 1 segment condensation using HOBt and copper(II) chloride simultaneously as additives, no racemization was detected and the yield was high enough. The elimination of racemization and improvement of coupling efficiency produced by the present procedure can be attributable to a reduced tendency for the activated forms of the carboxyl component to form a 5(4H)-oxazolone by the action of HOBt, and to the prevention of racemization by copper(II) chloride of the small amount of the oxazolone formed which is not eliminated by the action of HOBt alone.     

Localization of γ-melanocyte stimulating hormone (γMSH) immunoreactivity in rat brain and pituitary

γ-Melanocyte stimulating hormone (γMSH) is a possibly biologically active material discovered in the cryptic N-terminus of the pro-opiocortin precursor by recombinant DNA analysis of bovine pituitary mRNA. Well-characterized antisera to synthetic bovine γ-3MSH (γ₃MSH) were used to localize immunoreactive sites in sections of formaldehyde-fixed rat brain and pituitary by the indirect immunoperoxidase technique. Specificity for staining was established by absorption with the synthetic antigen peptides or their fragments; staining was not blocked by absorption with synthetic replicates of other natural peptides that contain redundant amino acid sequences, with those of γMSH such as corticotropin or β-MSH. The general patterns of staining within adenohypophysis, intermediate lobe, and central nervous system closely followed the previously described patterns of β-endorphin immunoreactivity. Corticotrophs, all intermediate lobe cells and neuronal perikarya in the ventro-basal hypothalamus exhibited immunoreactivity for γ₃MSH as they do for β-endorphin. Furthermore, the general distribution of immunoreactive nerve fibers and terminals within the diencephalon and pons was quite similar to endorphin immunoreactivity patterns as well. In series of alternating sections, prepared for either γ₃MSH β-endorphin immunoreactivity, the same specific terminal fields were found to exhibit very similarly shaped varicose axons and probable terminal bouton configurations. However, the density of the innervation by fibers exhibiting immunoreactivity for the two peptides varied among the common target areas. Furthermore, the perikarya exhibiting γ₃MSH immunoreactivity were fewer in number, smaller in size, and more medially clustered than those exhibiting immunoreactivity for β-endorphin. These results demonstrate that γ₃MSH also occurs in rat brain and in pituitary cells which were already known to contain endorphin immunoreactivity. However, γ₃MSH-immunoreactive neurones may not be coexistent with all endorphin-immunoreactive neurons, and these cells project with varying intensity to common target fields. Such observations are in agreement with the proposal of different processing of a common precursor in different cells.     

Electron microscopy of the leucocytes of the typhlosole in ammocoetes,with special attention to the antibody- producing cells

In an attempt to determine the role in the immune responses of the typhlosole, a hematopoietic tissue along the ventral wall of the larval lamprey Lampetra reissneri, scanning and transmission electron microscopic observations were made on ammocoetes hyperimmunized with sheep red blood cells. Besides including the cells of the erythrocyte series, this tissue also contained the following leucocytes forming an amorphous parenchyma: the cells of the granulocyte series, the most predominant cell type, possessing a markedly lobed nucleus and membrane-bounded granules of various sizes; the macrophages possessing primary and secondary lysosomes and long lamellipodia on the cell surface; the lymphocytes of a large nucleocytoplasmic ratio with a number of long, spiky microvilli, constituting a major type of rosette-forming (antigen-binding) cells; and the plasma cells possessing highly extended cisternae of rough endoplasmic reticula that are characteristic of the higher vertebrates. The immunoperoxidase technique, which employs rabbit antibodies against lamprey immunoglobulin, proved that these plasma cells do contain immunoglobulin. These results strongly indicate that the typhlosole of the larval lamprey, besides functioning as a hematopoietic tissue, is actively involved in the antibody responses. It is also stressed that the plasma cell occurs in the most primitive vertebrates as an immunologically competent cell.     

Targeting of Chrolamphenicol Acetyltransferase to Human Immunodeficiency Virus Particles via Vpr and Vpx

Vpr and Vpx are the auxiliary proteins of human immunodeficiency viruses (HIVs) selectively incorporated into mature viral particles. We showed that the bacterial chloramphenicol acetyltransferase (CAT) fused to the N-terminus of HIV-1 Vpr, HIV-2 Vpr, or HIV-2 Vpx was incorporated into mature virions in a type-selective manner. By using chimeric proteins between HIV-1 Vpr and HIV-2 Vpx, we found that the N-terminal side of these proteins was mainly important for type-selective virion incorporation. The C-terminal arginine-rich region of HIV-1 Vpr was also found to transport CAT fusion proteins into virions but without any type selectivity. Furthermore, the corresponding regions of HIV-2 Vpr and HIV-2 Vpx had no such activity. This region of HIV-1 Vpr may interact nonspecifically with viral genomic RNA. Collectively, Vpr and Vpx may provide a means to introduce foreign proteins and other molecules into HIV virions for therapeutic purposes.