In vitro transformation of petunia cells by an improved method of co-cultivation with A. tumefaciens strains

Summary A method (termed co-cultivation) for transforming plant cells in vitro with A. tumefaciens strains, which was originally developed by Marton et al. (1978) Nature 277: 129–131, has been modified by the incorporation of a novel feeder plate culture system and been extended to use with petunia protoplasts. Using efficient cell plating and selection conditions for phytohormone-independent growth, large numbers of independent transformed calli can be obtained efficiently (10^-1) and in less than 3 weeks following protoplast isolation. Southern hybridization analysis has confirmed that the majority of the resulting in vitro transformants contain a single copy of full length T-DNA.The high efficiency of this procedure allows simple screening to identify plant cells transformed by Ti plasmids attenuated by deletion of internal T-DNA regions. Results are presented that demonstrate the co-cultivation method can be used in conjunction with short term assays for monitoring plant gene expression.     

Effects of exercise on collateral development in myocardial ischemia in pigs

To study the effects of exercise on collateral development in myocardial ischemia, we induced coronary arterial stenosis of the left circumflex coronary artery (LCCA) in 18 of 30 pigs. During that surgery, we identified the coronary bed at risk. Nine of these pigs were then subjected to 5 mo of exercise training on a treadmill. After exercise training, we determined regional collateral and myocardial blood flow using radiolabeled microspheres. At autopsy, all animals had complete occlusion of the LCCA. Infarct size in the exercise-trained pigs was significantly less than in the sedentary pigs (5.9 +/- 1.0 vs. 11.7 +/- 1.0% of the left ventricle). The exercise-trained animals had a greater increase in collateral flow, 35.1 +/- 3.0 vs. 28.7 +/- 4.1 ml X min-1 X 100 g-1, in the noninfarcted jeopardized zone of the LCCA bed. The major findings of the study were the following: 1) chronic coronary artery stenosis progressing to occlusion stimulated development of the collateral circulation and salvaged tissue in the jeopardized myocardium of an animal model with sparse collaterals; 2) development of the collateral circulation and tissue salvage is increased by exercise training; 3) collaterals develop primarily in or near the ischemic zone; and 4) all collateral beds develop a circumferential flow gradient following occlusion.     

Food habits of the giant humphead wrasse,Cheilinus undulatus (Labridae)

Synopsis The giant humphead wrasse (Cheilinus undulatus), an inhabitant of coral reefs, is widely distributed in the tropical Indo-Pacific region. Stomach and intestinal contents of 72 specimens from the Pacific and the Red Sea revealed that this fish feeds primarily on mollusks, fishes, echinoids, and crustaceans.This article is one of several presented at the Second European Ichthyological Congress, Paris, 8-15 September 1976, to be published by Environmental Biology of Fishes.     

Regulation of growth in larvae of the crab : The effect of cyclic temperatures

Experiments were designed to demonstrate that growth is precisely regulated in crustacean larvae and that cyclic temperatures act as a perturbation on growth regulation. Newly hatched larvae were exposed to either the specific a cyclic temperature, cumulative growth was significantly inhibited. Also, the specific growth rate ( ) of larvae in the cyclic temperature regime was found to oscillate with decreasing amplitude around the of the larvae exposed to constant temperature. This oscillatory pattern has been observed in a wide variety of self-regulating systems. Evidence is presented to demonstrate that this regulatory mechanism also adapts to long-term exposure to cyclic temperatures. These findings increase our understanding of how larvae cope with and adapt to changing environmental temperatures. More significantly, the mechanism could provide a sensitive tool for estimating the effects of specific environmental disturbances on fitness.     

Chemical and immunological characterization of developmentally expressed chicken erythroid surface membrane antigens

The expression of two hematopoietic-lymphoid membrane antigens, referred to as chicken fetal antigen (CFA) and chicken adult antigen (CAA) were investigated on primitive and definitive peripheral red blood cells (RBC) from different-aged chickens using chemical and immunological techniques. Differential adsorptions of antisera specific for adult RBC membrane antigens permitted the serological dissection of CAA into eight antigenic determinants. CFA and CAA were assayed by hemagglutination, hemolysis, and immune precipitation of radioiodinated surface antigens of RBC from different-aged chickens. Primitive RBC express CFA, while definitive RBC express three distinct phenotypes: CFA, both CFA and CAA, or CAA, depending on the developmental age of the chicken from which the RBC were obtained. When solubilized membrane extracts of radioiodinated peripheral RBC from chickens at 5 and 18 days embryonic development (E5 and E18, respectively), 13 days posthatch development (H13), and adult chickens were immunoprecipitated and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the major antigen detected by anti-CFA sera was associated with proteins having apparent molecular weights (M_r) of 50,000 daltons (50 kd). The antigens detected by anti-CAA sera were associated with proteins having apparent M_r of 102, 81, 48, and 43 kd.     

Glutamine is a powerful effector of heat shock protein expression in Drosophila Kc cells.

We have investigated the effects of extracellular anions on the regulation of expression of the heat shock response in Drosophila Kc cells incubated in defined balanced salt solutions. Widely varying chloride concentrations had no effect on normal or heat shock protein (hsp) expression. Increasing glutamate concentrations from zero to 15 mM increased hsp expression more than 100-fold while affecting expression of non-heat-shock proteins minimally. Glutamine was 20-100-fold more potent than glutamate in supporting hsp expression, while other amino acids were less effective or supported no detectable hsp synthesis in heat shock. Inhibition of glutamine synthetase with methionine-sulfoximine resulted in very low hsp expression with glutamate and normal high level expression with glutamine, confirming the importance of glutamine. The absence of glucose and treatment with 2-deoxyglucose did not change the requirement for adequate glutamine for hsp expression. Cells heat shocked under conditions which gave very low hsp expression resumed growth when returned to normal medium as well as cells which expressed normal levels of hsps. Measurements of free amino acid levels in cells heat shocked in the presence and absence of glutamine showed a correlation between glutamine levels and amount of hsp expression. We conclude that a physiological process regulated by glutamine or a glutamine metabolite is important for normal hsp expression in heat shock conditions in Drosophila.     

B cell-associated LFA-1 and T cell-associated ICAM-1 transiently cluster in the area of contact between interacting cells.

TNP-specific B cells interact with carrier-specific T hybridoma cells in an antigen-specific, MHC-restricted manner. The formation of T cell/B cell conjugates is time and temperature dependent and results in the formation of a broad area of close contact between the interacting cells. In order to determine which surface molecules on the two cells cluster at the interaction site. T cell/B cell conjugates were formalin-fixed at different times following conjugation and were stained with antibodies directed against cell surface molecules. Results of these studies indicate that the alpha- and beta-subunits of LFA-1 on B cells transiently cluster in the area of cell contact. Maximum clustering of LFA-1 occurs at 45 min, after which time LFA-1 redistributes on the surface of the B cells. Several other B cell-associated molecules (MHC Class II, ICAM-1, Ig, B220, J11D, or CD23) do not cluster at the interaction site at any time point. T cell-associated LFA-1 does not cluster with any specific pattern, but ICAM-1 does. Maximum clustering of ICAM-1 occurs 60 to 90 min after intercellular contact. After this time, ICAM-1 redistributes on the surface of the T cells. Although both the alpha- and beta-subunits of LFA-1 cluster at the interaction site on B cells, antibodies recognizing these subunits differ in their ability to affect conjugation. One antibody recognizing the alpha chain of LFA-1 (M17/4.2) inhibits T-cell/B cell conjugation, whereas another antibody that also recognizes the alpha chain-(G-48) enhances conjugation. In contrast, an antibody that recognizes LFA-1 beta (M18/2.a.8) has no effect. An antibody that recognizes ICAM-1 (YN/1.7), the ligand for LFA-1, inhibits conjugation. These data show that, during T cell/B cell interaction. LFA-1 on B cells and ICAM-1 on T cells transiently cluster with similar, albeit not identical, kinetics to the site of cell-cell contact.