Granulocyte-macrophage colony-stimulating factor augments the primary antibody response by enhancing the function of antigen-presenting cells

Purified, recombinant-derived murine granulocyte-monocyte colony-stimulating factor was found to enhance the primary in vitro immune response to SRBC by murine spleen cells. In determining the mechanism of this augmentation, it was found that only splenic adherent cells and neither resting nor activated T cells nor B cells expressed specific receptors for GM-CSF. When splenic adherent cells were pulsed briefly with GM-CSF before addition to macrophage-depleted cultures, they reconstituted the PFC response to a significantly greater degree than did control macrophages. Splenic adherent cells incubated overnight with SRBC plus GM-CSF were also more efficient antigen-presenting cells than splenic adherent cells incubated with antigen alone. The mechanism of this enhanced antigen presentation was found to be due to a GM-CSF-dependent increase in the level of IL 1 secretion and Ia antigen expression. Consistent with these data was the finding that GM-CSF augmented IL 2 production by splenic T cells in response to suboptimal concentrations of Con A. Finally, the day 5 in vivo antibody response (as measured by serum titers) of mice immunized with a low dose of SRBC was enhanced by two daily inoculations of GM-CSF. Thus, the role that GM-CSF plays in augmenting immune responses may not be solely accounted for by its ability to cause the proliferation or differentiation of macrophages, but more than likely includes its ability to enhance the function of antigen-presenting macrophages.     

Fluctuation domains in myoglobin. Fluorescence quenching studies

The dynamics of two domains in the myoglobin molecule, close to the heme and inside the protein medium including the surface, are investigated through the study of the fluorescence oxygen quenching of two probes imbedded in the heme pocket: zinc protoporphyrin IX (with a fluorescence lifetime of 2.1 ns) and metal-free protoporphyrin IX (with a fluorescence lifetime of 17.8 ns).     

Synthesis and degradation of collagens in skin of healthy and protein-malnourished rats in vivo, studied by 18O2 labelling.

To explore the effects of growth retardation, caused by restricted protein intake, on collagen turnover in the whole skin, Sprague-Dawley rats (n = 20) were labelled with 18O2 and fed on either an adequate (18%) or a low (3%) lactalbumin diet. Skin biopsies were obtained at intervals during the following 6 months. Independent groups of animals (n = 186) were used to determine the size of the 0.5 M-acetic acid-soluble and -insoluble collagen pools in the entire skin of healthy and malnourished rats. Collagen was estimated by measurement of hydroxyproline. Soluble-collagen synthesis rates were equivalent to 99 +/- 8 mumol of hydroxyproline/day in healthy animals and 11 +/- 2 mumol/day in malnourished rats. Insoluble-collagen synthesis rates were 32 and 5 mumol of hydroxyproline/day in the healthy and protein-depleted rats respectively. The degradation of soluble collagen amounted to 37 +/- 8 and 6 +/- 2 mumol of hydroxyproline/day in the healthy and malnourished groups respectively. Efflux of collagen from the soluble collagen, defined as the sum of the rate of soluble collagen that is degraded plus that which matures into insoluble collagen, was 70 +/- 8 and 11 +/- 2 mumol of hydroxyproline/day in the healthy and malnourished groups respectively. Insoluble collagen was not degraded in either group. The fraction of soluble collagen leaving the pool that was converted into insoluble collagen was 0.46 in both diet groups. It is concluded that the turnover of soluble collagen is markedly decreased with malnutrition, but degradation and conversion into insoluble collagen account for the same proportions of efflux from the soluble-collagen pool as in rapidly growing rats.     

Ac transposition in transgenic tomato plants

Summary As an initial step towards developing a transposon mutagenesis system in tomato, the maize transposable element Ac was transformed into tomato plants via Agrobacterium tumefaciens. Southern analysis of leaf tissue indicated that in nine out of eleven transgenic plants, Ac excised from the T-DNA and reintegrated into new chromosomal locations. The comparison of Ac banding pattern in different leaves of the same primary transformant provided evidnece for transposition during later stages of transgenic plant development. There was no evidence of Ds mobilization in tomato transformants.     

Response of resident murine peritoneal macrophages to in vivo administration of granulocyte-macrophage colony-stimulating factor

The effect of s.c. inoculation of purified recombinant derived granulocyte-macrophage (GM)-CSF on resident murine peritoneal macrophages was assessed in this study. From 18 to 24 h after s.c. administration of GM-CSF to normal mice, the resident peritoneal macrophages were harvested and the levels of membrane-bound IL-1, FcR, Mac-1 cell-surface Ag, and class II MHC expression were assessed. Peritoneal cells from GM-CSF-inoculated mice had significantly greater levels of membrane-bound IL-1 than did control mice. In addition when resident peritoneal macrophages from normal mice were purified by adherence and grown in the presence of GM-CSF, they produced greater levels of both membrane-bound and secreted IL-1. The peritoneal cells from GM-CSF-inoculated mice did not differ from controls in the expression of class II MHC-encoded Ag. This observation was confirmed by the finding that GM-CSF was unable to induce class II MHC expression on P388D1 cells, whereas a secondary mixed leukocyte culture supernatant was. Peritoneal cells from GM-CSF-inoculated mice also exhibited greater levels of expression of FcR and the Mac-1 cell-surface Ag. This resulted in an increase in their ability to phagocytose opsonized SRBC in vitro.     

Resource sharing among ramets in the clonal herb,Fragaria chiloensis

Summary The herbaceous perennial, Fragaria chiloensis, reproduces vegetatively on coastal sand dunes in California by growth of stolons that bear rosettes. Movement of water and photosynthates through stolons integrates water and carbon metabolism of rosettes both before and after they root. New, unrooted rosettes import sufficient water and nitrogen to maintain levels near those of established rosettes; yet support of an unrooted rosette did not decrease growth of a connected, rooted sibling given abundant light, water, and soil nutrients. Under such conditions strings of unrooted rosettes with the associated stolon appeared self-sufficient for carbon; shade and drought induced import of photosynthates. New rosettes produced and maintained a limited root mass upon contact with dry sand, which could increase probability of establishment. Rooting did not induce senescence of stolons. Connection between two established rosettes prevented death by drought and shade, even when neither rosette could have survived singly. Results suggest that physiological integration of connected rosettes may increase total growth of clones of F. chiloensis through sharing of resources among ramets, especially when resource availability is changeable or patchy.     

Microvascular transplantation of expanded free scalp flaps between identical twins

Long-term follow-up of a previous free scalp transplant between identical twins is provided. A recent third transplant between these twins is presented in which donor flap expansion is used prior to transplantation, and the postoperative use of medicinal leeches is discussed.     

Implication of the alpha 1 beta 1 interface in the hemoglobin affinity changes. A comparative study between normal and San Diego fully ligated hemoglobins

The alpha 1 beta 1 interface of normal and mutated San Diego hemoglobins in their fully liganded form was investigated, through the SH vibrational absorption of beta-112 cysteine, by Fourier-transform infrared spectroscopy. The center frequency of this thiol group was significantly shifted in San Diego hemoglobin compared with normal human hemoglobin. Different dimer organization between the two proteins was also revealed by circular dichroism of the heme. These findings agree well with assessment that the alpha 1 beta 1 interface, far from being inert, is involved in the affinity changes of the hemoglobin molecule.     

fw 2.2:a major QTL controlling fruit weight is common to both red- and green-fruited tomato species

We have shown that a major QTL for fruit weight (fw2.2) maps to the same position on chromosome 2 in the green-fruited wild tomato species, Lycopersicon pennellii and in the red-fruited wild tomato species, L. pimpinellifolium. An introgression line F₂ derived from L. esculentum (tomato) x L. pennellii and a backcross 1 (BC₁) population derived from L. esculentum x L. pimpinellifolium both place fw2.2 near TG91 and TG167 on chromosome 2 of the tomato highdensity linkage map. fw2.2 accounts for 30% and 47% of the total phenotypic variance in the L. pimpinellifolium and L. pennellii populations, respectively, indicating that this is a major QTL controlling fruit weight in both species. Partial dominance (d/a of 0.44) was observed for the L. pennellii allele of fw 2.2 as compared with the L. esculentum allele. A QTL with very similar phenotypic affects and gene action has also been identified and mapped to the same chromosomal region in other wild tomato accessions: L. cheesmanii and L. pimpinellifolium. Together, these data suggest that fw2.2 represents an orthologous QTL (i.e., derived by speciation as opposed to duplication) common to most, if not all, wild tomato species. High-resolution mapping may ultimately lead to the cloning of this key locus controlling fruit development in tomato.     

Kinetic analysis of dynamic 13C NMR spectra: metabolic flux, regulation, and compartmentation in hearts.

Control of oxidative metabolism was studied using 13C NMR spectroscopy to detect rate-limiting steps in 13C labeling of glutamate. 13C NMR spectra were acquired every 1 or 2 min from isolated rabbit hearts perfused with either 2.5 mM [2-13C]acetate or 2.5 mM [2-13C]butyrate with or without KCl arrest. Tricarboxylic acid cycle flux (VTCA) and the exchange rate between alpha-ketoglutarate and glutamate (F1) were determined by least-square fitting of a kinetic model to NMR data. Rates were compared to measured kinetics of the cardiac glutamate-oxaloacetate transaminase (GOT). Despite similar oxygen use, hearts oxidizing butyrate instead of acetate showed delayed incorporation of 13C label into glutamate and lower VTCA, because of the influence of beta-oxidation: butyrate = 7.1 +/- 0.2 mumol/min/g dry wt; acetate = 10.1 +/- 0.2; butyrate + KCl = 1.8 +/- 0.1; acetate + KCl = 3.1 +/- 0.1 (mean +/- SD). F1 ranged from a low of 4.4 +/- 1.0 mumol/min/g (butyrate + KCl) to 9.3 +/- 0.6 (acetate), at least 20-fold slower than GOT flux, and proved to be rate limiting for isotope turnover in the glutamate pool. Therefore, dynamic 13C NMR observations were sensitive not only to TCA cycle flux but also to the interconversion between TCA cycle intermediates and glutamate.