Correlation between active rosette formation and delayed cutaneous hypersensitivity in experimental allergic encephalomyelitis

The effect of encephalitogenic myelin basic protein, BP, on active rosette-forming T cells (ARFC) was compared to that of nonencephalitogenic peptide S42, a synthetic analogue of the tryptophan region of BP. Depression of ARFC by these antigens was reversible within 24 h after a second dose of the antigen into the skin, or after in vitro incubation of lymphocytes with the sensitizing antigen (Ag-ARFC). The ratio of Ag-ARFC to ARFC rose with time following the sensitization but fell shortly before the clinical onset of experimental allergic encephalomyelitis in animals sensitized with BP. In contrast, the Ag-ARFC/ARFC ratios for animals sensitized with peptide S42 reached plateau levels from which they did not drop. The kinetics of the Ag-ARFC/ARFC responses paralleled those for delayed-type skin hypersensitivity (DTH) in the respective animals. The DTH responses rose following sensitization and fell shortly after the appearance of clinical signs of EAE. The results of this study provide in vitro and in vivo evidence for sensitization to myelin basic protein, and focus attention on the ARFC as a measure for an immunologically active cell population which may be quantitated by antigenic stimulation.Abbreviations used in this report EAE experimental allergic encephalomyelitis - DTH delayed-type skin hypersensitivity - ARFC active rosette-forming T cells - Ag-ARFC antigen-stimulated active rosette-forming T cells - TRFC total rosette-forming T cells     

Fossil Robinia wood from the western United States

A collection of petrified wood from the Lower Pliocene Ogallala Formation in western Oklahoma was examined. All specimens appear to be of the same taxon and exhibit features of extant Robinia species. To date, four fossil wood species of Robinia have been described. The relationship of Robinioxylon zuriensis Falqui to Robinia is doubtful because of the lack of diagnostic critical features. The remaining three, Robinia alexanderi Webber, Robinia breweri Prakash, Barghoorn and Scott, and Robinioxylon zirkelii (Platen) Müller-Stoll and Mädel do show affinity to Robinia and all have been noted as structurally similar to R. pseudoacacia. The Oklahoma woods and these three fossil species show considerable overlap in quantitative features and are identical in qualitative features. Examination of different sections (and specimens) of extant Robinia pseudoacacia wood reveals quantitative and qualitative variation similar to that found amongst the petrified woods. Robinia alexanderi, Webber, R. breweri Prakash, Barghoorn and Scott, R. zirkelii (Platen) Müller-Stoll and Mädel, and the Oklahoma specimens are considered to be conspecific as the differences between these fossil wood species are no different from those accounted for by variation within a single living species, R. pseudoacacia.     

Transfer of purified herpes virus thymidine kinase gene to cultured mouse cells.

Treatment of Ltk^?, mouse L cells deficient in thymidine kinase (tk), with Bam I restriction endonuclease cleaved DNA from herpes simplex virus-1 (HSV-1) produced tk⁺ clones with a frequency of 10^?6/2 μg of HSV-1 DNA. Untreated cells or cells treated with Eco RI restriction endonuclease fragments produced no tk+ clones under the same conditions. The thymidine kinase activities of four independently derived clones were characterized by biochemical and serological techniques. By these criteria, the tk activities were found to be identical to HSV-1 tk and different from host wildtype tk. The tk⁺ phenotype was stable over several hundred cell generations, although the rate of reversion to the tk^? phenotype, as judged by cloning efficiency in the presence of bromodeoxyuridine, was high (1–5 × 10^?3). HSV-1 DNA Bam restriction fragments were separated by gel electrophoresis, and virtually all activity, as assayed by transfection, was found to reside in a 3.4 kb fragment. Transformation efficiency with the isolated fragment is 20 fold higher per gene equivalent than with the unfractionated total Bam digest. These results prove the usefulness of transfection assays as a means for the bioassay and isolation of restriction fragments carrying specific genetic information. Cells expressing HSV-1 tk may also provide a useful model system for the detailed analysis of eucaryotic and viral gene regulation.     

Histone mRNAs contain blocked and methylated 5′ terminal sequences but lack methylated nucleosides at internal positions

Histone mRNA, labeled with ³²P or ³H-methionine during the S phase of partially synchronized HeLa cells, was isolated from the polyribosomes and purified as a “9S” component by sucrose gradient sedimentation. We identified two types of 5′ terminals, m⁷G(5′)pppN^mpN and m⁷G(5′)pppN^m-pN^mpN, in which the first methylated nucleoside is 7-methylguanosine, the second is either N⁶,2′-O-dimethyladenosine, 2′-O-methyladenosine, or 2′-O-methylguanosine, and the third is 2′-O-methyluridine, 2′-O-methylcytidine, or 2′-O-methyladenosine. Approximately 1.7% of the ³²P label was present in the 5′ terminal structures. Assuming a similar specific radioactivity for all phosphates, this percentage corresponds to an average of one terminal per 335 nucleotides. Histone mRNA differed from bulk polyadenylylated mRNA of HeLa cells in lacking significant amounts of 2′-O-methyluridine or 2′-O-methylcytidine in the second position of the 5′ terminal oligonucleotide and in lacking N⁶-methyladenosine residues at internal positions.     

Active transport of alpha-aminoisobutyric acid in freshly prepared rat hepatocytes

The transport of alpha-aminoisobutyric acid in freshly prepared rat liver cells was saturable and exhibited a K_t of 13.9 × 10^?3M and a_max of 28.6 umoles/ml intracellular fluid/30 min. The system required the presence of sodium and was sensitive to ouabain. Anaerobiosis, 2,4-dinitrophenol and low temperature suppressed the uptake of the amino acid. Efflux studies also indicated that the majority of the intracellular amino acid was rapidly exchangeable and therefore probably present in the cell water in a free state. It is suggested that alpha-aminoisobutyric acid is transported into isolated rat hepatocytes by an active carrier system.     

Biosynthesis of eugenol and cinnamic aldehyde in Cinnamomum zeylanicum

Incorporation of [¹⁴C]-phenylalanine and [¹⁴C]-methionine into cinnamon cuttings suggests that synthesis of eugenol from phenylalanine involves exchange of the terminal carbon in the side chain with that from a donor molecule such as methionine whereas synthesis of cinnamic aldehyde incorporates phenylalanine in toto.     

Nitrogen fixation throughout growth,and varietal differences in nitrogen fixation by the rhizosphere of rice planted in pots

Summary The nitrogen-fixing activity in the rhizospheres of various rices was measured by the acetylene-reduction method throughout plant growth in green-house pots. The activity began to increase 4 weeks after transplanting, increased until heading stage, then decreased. The concentrations of exchangeable ammonium and sugars in the soil were not related to the variation of nitrogen-fixing activity during rice growth.The nitrogen-fixing activities in the rhizospheres of 41 rice varieties in pots were measured to discover varietal differences. Levels of nitrogen fixation were highly correlated with the rices' dry root weight at heading stage.     

An assay technique of measurement of nitrogenase activity in root zone of rice for varietal screening by the acetylene reduction method

Summary The feasibility of using a plastic bag was examined in a test to screen rice varieties for differences in the nitrogen-fixing activity in their root zones. The change in the volume of the plastic bag during 24 hours of incubation was not significant. Although the plastic bag was permeable to acetylene and ethylene, the amounts lost through permeation during 24 hours of incubation did not seem to affect the acetylene reduction assay. The plastic bag was convenient to use in creating different conditions of the gas phase, and was useful for screening six rice varieties for differences in nitrogen-fixing activity in their root zones.     

In-ovulo embryo culture and seedling development of cotton (Gossypium hirsutum L.)

A convenient and reliable method for culturing cotton embryos is needed to obtain interspecific hybrids of this genus. C.A. Beasley and I.P. Ting (Amer. J. Bot. 60, 130, 1973) developed a phytohormone-supplemented medium (BTP) upon which the growth of ovules was similar that of in situ ovules. This medium was examined for in-ovulo embryo culture. Although good ovule growth occurred on BTP no embryos developed to maturity. However, when the medium was supplemented with NH ₄ ⁺ , more than 50% of the ovules produced mature embryos, and many of these germinated precociously after 8–10 weeks of culture. After germination seedlings were established on a separate medium designed to give balanced root and shoot growth. Subsequently young plants could be transferred to pots for greenhouse culture.