Interferon synthesis in the early post-implantation mouse embryo

Abstract. A qualitative bioassay was adapted and used to determine the ability of the early post-implantation mouse embryo to synthesise interferon. Interferon production was not seen in any embryo tissue in the absence of an inducer and could only be detected in virus-induced tissue from the early 7th day of development. This induced interferon synthesis was initially confined to the trophoblast of the early 7th day embryo. It was then found in tissues of both trophoblast and inner cell mass origin in the early 8th day, and subsequently, in derivatives of the embryonic ectoderm in the 13th-day embryo.     

Cytological identification of the genomes in pentaploidAllium neapolitanum using Giemsa C-banding

Two homoeologous sets of chromosomes in pentaploidAllium neapolitanum Cyr. (Liliaceae) are recognizable by their C-bands. The banding pattern is the same for one Californian and five Yugoslavian populations, suggesting a common chromosomal origin. Predominant meiotic association of identically banded homologues indicates a genomic formula of AA A_I BB, confirms an allopolyploid origin, and argues against genetically controlled pairing.     

Electronmicroscopical detection of iota-Carrageenan as its ruthenium red complex

Summary Specific detection of iota-Carrageenan (i-CAR) at the ultrastructural level has been obtained by coupling with ruthenium red (RR) — an electron microscopic stain. The i-CAR-RR complex showed electron density on carbon layers. Peritoneal macrophages were treated with the complex and after 3 h it caused the same morphological changes in macrophages as iota-Carrageenan alone. On the surfaces of macrophages, fine filamentous electron dense material — the i-CAR-RR complex — was detected.     

Changes in chromatin structure during the mitotic cycle

Summary Optical density profiles of Feulgen-stained nuclei ofBryonia dioica at different stages of the mitotic cycle were determined. Nuclei in the G₂ phase have a greater fraction of dense chromatin than nuclei in G₁ phase. However, nuclei at the end of the S phase have dispersed chromatin of minimal density. Thus, chromatin density oscillates during the mitotic cycle of this species, consequently the progressive increase in density previously recorded throughout the intermitotic period of two other species (onion and mouse) cannot be a general rule.     

In vitro fertilization, development, and implantation after exposure of mature mouse oocytes to visible light.

Mature mouse oocytes were exposed prior to in vitro fertilization to visible light during 1, 2, or 4 hr at an intensity of 4,000 lux. Compared to controls cultured under identical conditions but protected from light, exposed eggs did not show any significant modification of cleavage speed and rate. After transfer of blastocysts obtained in vitro in uteri of pseudopregnant females, the implantation rate and the proportion of normal fetuses were not found to be different in relation to preliminary light exposure of oocytes fertilized and cultured in vitro.     

Molecular modelling of the structures of endothelin antagonists. Identification of a possible structural determinant for ET-A receptor binding.

Computer-aided molecular modelling of the endothelin (ET-A) receptor antagonists, BQ-123 and BE-18257B, shows that they have very similar 3D structures. Parts of their 3D structures are also shown to match closely with that reported for residues 6-8 in endothelin-1. On the basis of these similarities (and with supporting evidence from literature data on endothelin structure-activity relationships) a structural determinant is proposed for ET-A receptor binding, and novel designs of peptide are suggested for providing more potent and selective ET-A receptor antagonists.     

Lectin Binding to Radopholus citrophilus and R. similis Proteins

Lectin-binding glycoproteins in seven populations of two burrowing nematode sibling species were probed with five different biotinylated lectins on Western blots, and differences were correlated with nematode ability to parasitize citrus and to overcome citrus rootstock resistance. Banding patterns of molecular weight standards were fit best by an exponential decay function, and a predictive equation was used to estimate molecular weights (r² = 0.999). A band (131 kDa) that labeled with the lectin Concanavalin A (Con A) occurred in extracts from cuticles and egg shells of populations of Radopholus citrophilus that parasitize citrus. Wheat germ agglutin labeled a band (58 kDa) in aqueous homogenates of populations that reproduce in roots of citrus rootstock normally resistant to burrowing nematodes. The two sibling species R. citrophilus and R. similis were distinguished by a high molecular weight Con A-labeled band (608 kDa) from cuticle and egg shells. Probing blots with the lectin Limulus polyphemus agglutinin indicated that each population contained a band (12-16 kDa) specifically inhibited by the addition of 25 mM neuraminic acid, suggesting that glycoproteins with sialic acid moieties are present in burrowing nematodes.