The expression of neurotrophin and neurotrophin receptor mRNAs was examined using RNase protection assays and Northern‐blot analysis in rat thymus, spleen tissue and immunocompetent mononuclear cells purified from these two organs. Nerve growth factor, brain‐derived neurotrophic factor, neurotrophin‐3 and neurotrophin‐4 mRNAs were all expressed in thymus and spleen tissue although at different levels, while immunocompetent cells expressed neurotrophin‐3 and neurotrophin‐4 mRNAs. Thymus and spleen tissue expressed mRNAs encoding the low‐affinity nervegrowth‐factor receptor, the non‐neuronal TrkA I receptor, the truncated (kinase deficient) and full‐length TrkB, and the TrkC receptor. Low‐affinity nerve‐growth‐factor receptor and non‐neuronal TrkA I mRNAs were detected in both thymus and spleen immunocompetent cells. In addition, thymus cells expressed neuronal TrkA II mRNA and spleen cells expressed truncated TrkB mRNA. The expression of TrkA I and TrkA II mRNAs was enhanced in both thymus and spleen cells after cell culture. Enhanced levels of neurotrophin‐4 mRNA were observed in spleen immunocompetent cells after adrenalectomy. Moreover, the expression of neurotrophin‐4 mRNA was up‐regulated after stimulation of immune cells with the mitogens concanavalin A or lipopolysaccharide or with the inflammatory mediator leukotriene B4. This suggests that neurotrophin‐4 could be secreted by immunocompetent cells and may be involved in inflammatory processes.

A chickpea cDNA encoding a cell wall copper amine oxidase (CuAO) was cloned and characterised. The 2010 bp open reading frame encodes a protein of 76.5 kDa which shares significant primary structure homology with other known CuAOs. Southern blot analysis indicates that in chickpea CuAO is encoded by a single gene or a small gene family. This cDNA was essential for studying the role of CuAO during seedling development and wound healing in chickpea seedlings. CuAO transcript level and activity were modulated during seedling development in parallel with cell maturation. Moreover, mechanical wounding induced a rapid increase of CuAO mRNA accumulation and enzyme activity which remained high during the wound-healing process. Aminoguanidine, a specific CuAO inhibitor, decreased the deposition of lignin-suberin barrier along the lesion. CuAO may be a limiting factor in H P O P production in the cell wall of chickpea seedlings and its expression seems to integrate with the remodelling of plant cell wall occurring during ontogenesis and wound healing.z 1998 Federation of European Biochemical Societies.

Substance P (SP) has recently been reported to induce interleukin 1 (IL-1) production by human monocytes. This was confirmed in our experiments with human monocytes cultivated in the presence of SP or SP together with lipopolysaccharide (LPS). In addition, a wide variability of cell response to the neuropeptide was noticed. Three out of twelve cell cultures were directly stimulated by SP to release IL-1, while four additional cultures needed prestimulation with suboptimal doses of LPS, and no effect was seen in the five remaining experiments. The data may suggest that preferentially activated monocytes respond to SP. The production of IL-1 by SP-stimulated monocytes is of great interest considering the broad spectrum of activity of IL-1 and the increasing evidence of sensory neuron involvement in acute and chronic inflammatory responses.

The photomodulation of polyamine oxidase (PAO) expression during de-etiolation of the maize (Zea mays L.) mesocotyl was used as the experimental model to investigate a possible correlation with the photomodulation of growth and with wall dierentiation and stiening. The accumulation of PAO transcript and enzyme activity were enhanced by light treatment in cortical and epidermal (outer) tissues of the mesocotyl. Histochemical analysis revealed that this phenomenon is mostly due to the increased level of PAO activity in epidermal and sub-epidermal tissues. The photomodulation of PAO activity upon de-etiolation in outer tissues is mediated by phytochrome. A close correlation was found between the time course of red-light-elicited increase of PAO activity and that of growth inhibition in the outer tissues of the apical, growing zone of the mesocotyl. Light exposure of etiolated, sub-apical mesocotyl segments resulted in a higher production of hydrogen peroxide (H 2 O 2 ) in the incubation medium compared with segments incubated in the dark. The latter phenomenon was inhibited by the speci®c PAO inhibitor guazatine. A short pre-treatment of mesocotyl and coleoptile segments with 1 mM spermidine inhibited IAA-induced elongation growth, this phenomenon being reversed by catalase. Pre-treatment with catalase alone resulted in a higher extent of IAA-induced elongation. Moreover, pre-incubation with 1,3-diaminopropane, a product of spermidine oxidation catalysed by PAO, had no eect on IAA-induced elongation growth of either coleoptile or mesocotyl segments, while H 2 O 2 pre-treatment was eective. These results indicate that PAO activity is important in producing H 2 O 2 in vivo for peroxidase-catalysed wall-stiening reactions and may be involved in the modulation of growth and cell wall dierentiation in the maize mesocotyl.Key words: Cell wall stiening ± Hydrogen peroxide ± Mesocotyl growth and phytochrome ± Peroxidase ± Polyamine oxidase ± Programmed cell death ± Zea (cell wall stiening)Abbreviations: AAP = 4-aminoantipyrine; DCHBS = 3,5-dichloro-2-hydroxybenzene sulfonic acid; PAO = polyamine oxidase; PCD = programmed cell death