A low mutation rate for chloroplast microsatellites.

We used chloroplast simple sequence repeats (cpSSRs) to examine whether there is any variation present in the chloroplast genome of Pinus torreyana (Parry ex Carrière) that may previously not have been detected using RFLPs. Analysis of 17 cpSSR loci showed no variation, which is consistent with previous cpRFLP work and confirms that the species is descended from an original, highly monomorphic population following a bottleneck. This lack of biological variation in the chloroplast genome of P. torreyana allowed us to estimate the mutation rates at cpSSR loci as between 3. 2 x 10(-5) and 7.9 x 10(-5). This estimate is lower than published mutation rates at nuclear SSR loci but higher than substitution rates elsewhere in the chloroplast genome.     

Lack of effect of glutathione depletion on cytotoxicity, mutagenicity and DNA damage produced by doxorubicin in cultured cells

Since endogenous glutathione (GSH), the main non-protein intracellular thiol compound, is known to provide protection against reactive radical species, its depletion by diethylmaleate (DEM) was used to assess the role of free radical formation mediated by doxorubicin in DNA damage, cytotoxicity and mutagenicity of the anthracycline. Subtoxic concentrations of DEM that produced up to 75% depletion of GSH did not increase doxorubicin cytotoxicity in a variety of cell lines, including Chinese hamster ovary (CHO) and lung (V-79) cells, LoVo human carcinoma cells and P388 murine leukemia cells. Similarly, the number of doxorubicin-induced DNA single strand breaks in CHO cells and the mutation frequency in V-79 cells were not affected by GSH depletion. The results obtained suggest that mechanisms other than free radical formation are responsible for DNA damage, cytotoxicity and mutagenicity of anthracyclines.     

Bombesin-like immunoreactivity in eosinophils. A light and electron microscopic study: effect of fixatives and cross-reactivity with various compounds.

Eosinophils immunopositive for bombesin tetradecapeptide were detected by means of light and electron microscopy in human and rat gastrointestinal tract and pulmonary tissue. This immunoreaction was only evidenced after the use of acetic acid-containing fixative such as Bouin's fluid. The dependence of this immunostaining on fixatives and time course were extensively studied. This immunoreaction promotes mainly one epitope probably associated with the C-terminal sequence. This epitope seems also to be present in other neuropeptides such as substance P (SP) and, to a lesser extent in chemotactic factors like formyl peptide (fMLP) or eosinophil chemotactic factor of anaphylaxis (ECF-A). At the electron microscopic level, the immunopositivity was associated with eosinophil membranes.     

Macrophage metabolism: activation of NADPH oxidation by phagocytosis

Rabbit and guinea pig peritoneal and alveolar macrophages and rabbit polymorphonuclear leucocytes (PMN) have been tested for their capacity to oxidize NADPH and NADH. In all these cells granule-bound NADPH oxidase is much more active than NADH oxidase, thus confirming our previous observations on human blood and guinea pig PMN. If the phagocytes are challenged with bacteria, the activity of NADPH oxidase is considerably stimulated. The enhancement of the oxidase activity is due to an increase of its V_max and, in the case of the PMN, also to a decrease of the K_m. We conclude that NADPH oxidase might play a relevant role in the metabolic stimulation of both PMN and macrophages by phagocytosis.     

Amplified fragment length polymorphism (AFLP) analysis of genetic variation in Moringa oleifera Lam

Moringa oleifera is an important multipurpose tree introduced to Africa from India at the turn of this century. Despite limited knowledge of the levels of genetic diversity and relatedness of introduced populations, their utilization as a source of seed for planting is widespread. In order to facilitate reasoned scientific decisions on its management and conservation and prepare for a selective breeding programme, genetic analysis of seven populations was performed using amplified fragment length polymorphism (AFLP) markers. The four pairs of AFLP primers ( Pst I/ Mse I) generated a total of 236 amplification products of which 157 (66.5%) were polymorphic between or within populations. Analysis of molecular variance ( AMOVA ) revealed significant differences between regions and populations, even though outcrossing perennial plants are expected to maintain most variation within populations. A phenetic tree illustrating relationships between populations suggested at least two sources of germplasm introductions to Kenya. The high levels of population differentiation detected suggest that provenance source is an important factor in the conservation and exploitation of M. oleifera genetic resources.