Performance ofin vitro propagatedAlnus glutinosa (L.) Gaertn. clones inoculated withFrankiae

Summary ThreeAlnus glutinosa (L.) Gaertn. clones, obtained byin vitro propagation techniques, were inoculated with four strains ofFrankia. The ability of these clones to nodulate and fix nitrogen was previously reported; this study deals with the performance of 12 different combinations of pairs of symbionts.Shoot fresh weight, shoot height and collar diameter were measured 60 and 82 days after inoculation. Shoot fresh weight seems to be more sensitive and reliable than the other parameters. Nitrogenase activity, measured by the acetylene reduction assay, was assayed 78 days after inoculation and was consistent with the biomass measurements.Better growth was observed when type N strains were used. Significant growth differences were observed between clones AG-2 and AG-8 on the one hand and clone AG-4 on the other. Thus, the use of genetically defined host plants and microsymbionts permitted the demonstration of significant performance variation even among cloned plants from the same provenance (AG-4 and AG-8).The duration of the experiment influenced the results with differences becoming less significant with time. This might be caused by an external limiting factor such as the pot size, competition for light,etc. But it could also be indicative of differences in nodulation speed among the treatments.     

Isoproterenol induces a ribosomal modification in the heart and the skeletal muscle of hamsters

The protein synthesis activity of heart, skeletal muscle and liver polysomes from isoprotenerol-treated and control hamsters has been compared in an in vitro non-inititating translation system. Heart and skeletal muscle polysomes from treated hamsters were less active than controls and required a higher magnesium concentration for optimal protein synthesis. These results suggest that there is a conformational modification in heart and skeletal muscle ribosomes from isoprotenerol-treated hamsters. No such change was observed with ribosomes from the liver of isoproterenol-treated hamsters.     

Evidence for the participation of disulfide and sulfhydril groups in the specific binding of [3H]prazosin in cerebral cortex

The tritiated ₁ antagonist prazosin [³H]PRZ binds specifically and with high affinity to postsynaptic adrenoceptors in membrane preparations from cerebral cortex. Since adrenoceptors are of protein nature, it was of interest of investigate the possible role of disulfide (—SS—) and sulfhydril (—SH) groups in the binding of [³H]PRZ. Pretreatment of the membranes with the disulfide and sulfhydryl reactivesdl0Dithiothreitol,l-Dithiothreitol, Dithioerythritol or 5,5-Dithiobis-(2-nitrobenzoic acid) (DTNB), alone or in combination with the alkylating agent N-Methylmaleimide (NMM), decreased specific [³HPRZ binding, with minor changes in the non-specific counts. Saturation experiments revealed that all these reagents reduced the affinity of the binding site for [³H]PRZ, as judged by theK _d 25°C, but only the alkylating agent NMM and the oxydizing reagent DTNB produced in addition to the increase inK _d, a decrease of the maximum binding capacity (B _max). The present results provide evidence for a participation of—SS—and/or—SH groups in the recognition site of the ₁-adrenoceptor of cerebral cortex.     

The majority of independently transformed BHK cell clones share a single functional lesion which determines anchorage independence and influences tumorigenicity

Summary Expression of the anchorage-independent transformed phenotype in BHK 21/13 cells generally behaves as a recessive trait. When chemically induced and spontaneously arising transformants are fused to the nontransformed parent line, transformation is initially suppressed, reappearing after extended growth of the hybrids. In this paper, complementation for the expression of anchorage independence was sought among a large group of such transformants, all independently derived from BHK 21/13 cells. Tumorigenicity studies on selected hybrids and parental lines indicated that the in vitro trait of anchorage independence is an accurate indicator of in vivo neoplasia for these cells. Seventeen of the 18 clones tested did not complement one or more of three tester strains. This result indicates that anchorage independence arose in these clones as a result of lesions in the same genetic function and suggests that the final step in the progressive changes of carcinogenesis may frequently be restricted to lesions at a single locus. This investigation was supported by National Institutes of Health grant CA27306.     

The effects of crude oil on the growth of Spartinaalterniflora Loisel. and Spartina cynosuroides (L.) Roth

Greenhouse studies were conducted to examine the effects of crude oil on the growth of Spartinaalterniflora Loisel. and S. cynosuroides (L.) Roth from North Carolina. The way in which crude oil came into contact with the plant tissue and/or substratum was an important factor in determining the responses of both species to oil pollution. Plants recovered from a single application of oil to aerial tissue with relatively little impact on productivity. The presence of an oil layer on the surface of an overlying layer of water had little impact on existing aerial portions of S. alterniflora plants; however, regrowth following harvest was completely inhibited. Incorporation of oil into the substratum significantly reduced aerial productivity and regrowth of S. alternflora and S. cynosuroides. Observations suggest that decreased productivity and regrowth may have been caused by decreased root and rhizome growth. Regrowth potential of S. alterniflora grown in oiled substratum was greater in fine-textured marsh substratum than in sand substratum.     

Electrophoretic behavior of the H+-ATPase proteolipid from bovine heart mitochondria

The proteolipid subunit of H⁺-ATPase was labeled by [¹⁴C]N,N-dicyclohexylcarbodiimide in bovine heart mitochondria. The radioactive labeling was followed using various systems of sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). When using discontinuous SDS-PAGE (Laemmli, U.K., 1970,Nature (London)227, 680–685) a monomeric (Mr 7600±1500) and a dimeric form (Mr 17,800±1200) of the proteolipid were detected, while only the monomeric form was found on urea (8 M) containing gels (SDS-PAGE according to Laemmli; or Swank, R. T., and Munkers, K. D., 1971,Anal. Biochem. 39, 462–477). When using SDS-PAGE with Na-P_i buffer (Weber, K., and Osborn, M., 1969,J. Biol. Chem. 244, 4406–4442), only a dimeric form of the proteolipid (Mr 15,000±1000) was detected. Experimental data indicate that the different patterns of proteolipid separation are related to the presence of the two distinct proteolipid conformations in the SDS solution.     

Column cellulose hydrolysis reactor: Cellulase adsorption profile

Summary A column cellulose hydrolysis reactor was set up using a single passage of cellulase enzyme which was followed with a continuous percolation of buffer. Hydrolysis rates were found to decline precipitously upon the removal of the non-adsorbed cellulase components. By comparing specific activities of the cellulase before and after adsorption on the cellulose column, it was concluded that the adsorption efficiencies for the cellulase components decreased from exoglucanase (1,4--d-glucan cellobiohydrolase EC 3.2.1.91) to endoglucanase [1,4-(1,3;1,4)--d-glucan 4-glucanohydrolase, EC 3.2.1.4] to -glucosidase (-d-glucoside glucohydrolase, EC 3.2.1.21). Of the adsorbed cellulase components, the rate of endoglucanase leaching from the cellulose column was 20 times that for the exoglucanase despite the greater adsorption efficiency of the latter. By analysing the cellulase components which were bound and not bound by the cellulose column and comparing them with a purified exoglucanase enzyme on sodium dodecyl sulfate polyacrylamide gels, it was confirmed that the major cellulase component adsorbed to the cellulose column was an exoglucanase component. The resultant loss of other cellulase components from the reactor was probably the cause for the much reduced rate of cellulose hydrolysis when these components were flushed out of the column.