Ovular development and morphology of the outer integument of Magnolia grandiflora (Magnoliaceae)

Ovular development of Magnolia grandiflora was examined to determine the morphology of the outer integument. At the time the ovular primordium begins incurving, the outer integument is initiated subdermally, and later the inner integument arises from the dermal layer. Whereas the inner integument is annular, the outer integument is formed as a semiannular rim interrupted on the concave side of the funiculus. Later the outer integument becomes a hood-shaped envelope. The obturator is formed as a transversely elongate outgrowth on the concave side of the funiculus and intervenes in the gap of the outer integument. During further development the inner integument produces several distal lobes, and the outer integument becomes bilobed. The exostome is a transverse slit with a middle notch, formed by the outer integument and the obturator. Presumed wide occurrence of the hood-shaped outer integument in primitive families suggests that it is a primitive state. The outer integument is compared with the ovuliferous sporophylls of the glossopterid and caytonialean seed ferns.     

Studies on delayed hypersensitivity to protein antigen. Antigen-specific suppression of delayed hypersensitivity by chemically modified antigen.

An extensively modified protein antigen (methylated bacterial α-amylase, M-BαA) which was neither reactive with anti-BαA antibody nor able to induce a humoral anti-BαA response, retained the ability to prime native BαA-specific T cells which were responsible for the enhanced anti-BαA response to subsequent immunization with BαA and delayed hypersensitivity (DH). The splenic T cell-rich fraction from mice primed with M-BαA collaborated with a native BαA-primed B cell-rich fraction to give a good adoptive IgG anti-BαA response in syngeneic irradiated mice, whereas M-BαA-primed B cell fractions failed to cooperate with native BαA-primed T cell fractions. Splenic T cells from mice given a subcutaneous (s.c.) injection of M-BαA in complete Freund's adjuvant (CFA) exhibited DH in syngeneic cyclophosphamide-treated mice. In the present study, native and methylated BαA were tested for their ability to generate suppressor T cells capable of inhibiting the development of DH. An intraperitoneal (i.p.) injection of either native or methylated BαA in incomplete Freund's adjuvant (IFA) interferred with the development of DH to M-BαA by an s.c. injection of the same antigen in CFA. Transfer of spleen cells from mice given an i.p. injection of either of these antigens 5 days previously, suppressed antigen-specifically induction and expression of DH in the syngeneic recipient mice. The suppressive activity was sensitive to treatment with anti-θ antiserum plus complement. These results indicate that the early phase of inhibition of DH after an i.p. injection is in part mediated by suppressor T cells and that M-BαA cross-reacts with native BαA at the suppressor T cell level as well as the level of effector T cells in DH.     

Induction by Staphylococcus aureus L-form of tumor necrosis factor-alpha from macrophages

Induction of tumor necrosis factor-alpha (TNF-alpha) by Staphylococcus aureus L-form was investigated. The supernatant of a macrophage culture mixed with S. aureus L-form showed a potent cytotoxic activity to L cells. Addition of anti TNF-alpha antibody inhibited completely the cytotoxic activity of the supernatant, indicating that the activity might be due mostly to TNF-alpha. To investigate localization of TNF-alpha production, the membranes of hypotonicity treated L-form were layered on a step-gradient composed of an upper and lower layers of 35% and 50% sucrose, respectively. The membranes were banded at the interface of 35% and 50% of sucrose. The activity of TNF-alpha production of the membrane fraction was 10-times higher than that of the soluble fraction.     

Inducation of chromosomal aberrations in cultured mammalian cells by nickel compounds

The effects of 4 Ni compounds, nickel chloride, nickel acetate, potassium cyanonickelate, and nickel sulfide were studied in a line of mammary carcinoma cells from the C3H mouse. All 4 were easily taken up by the cells and reacted with protein, RNA, and possibly DNA. Measurements of leucine, uridine, and thymidine uptake during exposure showed that the syntheses of protein and DNA were more sensitive than RNA. Chromosomal aberrations were observed during the recovery period following the end of the treament with Ni. The implications of these results were discussed with respect to the carcinogenicity of the compounds and to the recommended protocols for mutagenicity testing by chromosomal aberrations.     

Demonstration of capsule in a strain of Staphylococcus hyicus by an electron microscope

A compact type variant designated as strain ST67V was isolated by a high-temperature subculture method from strain ST67P of Staphylococcus hyicus , which was a diffuse type in serum-soft agar. The parent strain was relatively virulent in mice and resisted ingestion by mouse peritoneal cells. The variant strain, however, was avirulent in mice and no antiphagocytic activity was observed in the peritoneal cavity. In ultra-thin sections of the organisms treated with anti-ST67P rabbit anti-serum conjugated with ferritin, the outermost layer of the cell wall of the parent strain was covered with a well-defined capsule while no capsule was shown in the variant strain.     

Morphological Differences in Flagella in Campylobacter fetus Subsp. intestinalis and C. fetus Subsp. jejuni

Intact flagella were isolated from human pathogenic strains of Campylobacter, C. fetus subsp. intestinalis and C. fetus subsp. jejuni, by the method of DePamphilis and Adler and examined by electron microscopy. The isolated flagella were composed of a filament, a hook, a basal body, and a large disk associated with the end of the hook region covering the basal body. The width of the hook was approximately 28 nm, somewhat greater than that of the filament (20 nm in diameter). The hook region of C. fetus subsp. intestinalis was curved, but it was straight in C. fetus subsp. jejuni. The structure of the basal body of the two subspecies was similar to that reported for other gram-negative bacteria. The large disk detached from the flagella showed concentrically arranged circular structures. This structure was more clearly observed in the disk of C. fetus subsp. jejuni than in C. fetus subsp. intestinalis. Observations of thin-sectioned profiles at the attachment site of the flagellum revealed that the large disk is located on the inner side of the outer membrane. The role of the large disk in bacterial movement is not clear, but it is assumed that it acts as an organ to protect the flagellar insertion site from vigorous rotation of the polar end inflicted during bacterial movement.     

Accumulation of phosphate-containing granules in the nucleoid area of Pseudomonas aeruginosa

Many electron-dense granules were found in the nucleoid area of Pseudomonas aeruginosa strain K by electron microscopy with the technique of the freeze-substitution method. These granules contained phosphorus and calcium as determined by X-ray microanalysis. The size and the numbers of the granules decreased when the bacteria was cultured in the medium from which phosphate-containing compounds were depleted. From these observations we concluded that the granule was a phosphate-containing granule and possibly a polyphosphate granule. The excellent preservation of the fine structures by the freeze-substitution technique enables us to show very small polyphosphate granules in the nucleoid area of the bacterial cells which cannot be revealed by the conventional chemical fixation method. As we could not see the granules in other bacteria cultured in nutrient medium such as Serratia, Escherichia, Bacillus and Vibrios, the accumulation of the phosphate granules in Ps. aeruginosa might be a unique character of this bacteria and might be related to the growing capability of this bacteria in extremely low nutrient supply.