The mycorrhizal status of the woody Mediterranean shrub Myrtus communis L.

  Myrtus communis L. (myrtle), a typical Mediterranean plant species belonging to the family Myrtaceae, was shown to form arbuscular mycorrhizal symbioses in nature. Many different spore types were isolated from its rhizosphere and grown in pot cultures; six of them were identified as Glomus species. In the laboratory, the myrtle root system was colonized by indigenous endophytes as well as by an Italian isolate of Glomus intraradices. In greenhouse experiments, mycorrhizal inoculation reduced transplant stress in 60-day-old myrtle seedlings; their growth was renewed immediately after transplanting, whereas non-mycorrhizal plants stopped development. Significantly larger growth responses were obtained using indigenous fungi than the Italian isolate of Glomus intraradices. Accepted: 16 January 1997     

MIB-1 and S-phase cell fraction predict survival in non-Hodgkin's lymphomas

The monoclonal antibody anti-Ki67 is used to detect proliferating cells, but its main limitation is the requirement of fresh-frozen material. On a series of patients with non-Hodgkin's lymphoma, we used a Ki67 equivalent monoclonal antibody, the recently proposed MIB-1, on formalin-fixed histopathological material using microwave antigen retrieval. MIB-1 expression was analysed in relation to other proliferation indices, such as autoradiographic ³H-thymidine labelling index (³HTL1) and flow cytometric S-phase cell fraction (FCM-S) and to pathological status. Moreover, the prognostic relevance of the cell kinetic indices was defined in uni- and multivariate analyses including histology and tumour stage. The relationship between MIB-1 index and the other proliferation indices was statistically significant even though the correlation coefficient was around 0.6. The MIB-1 index was also related to the REAL (Revised European American Lymphoma) classification, but not to the Ann Arbor stage classification. Univariate analysis showed that the MIB-1 index was a significant predictor of 6-year survival in the overall series and in distinctly analysed low-grade and high-grade lymphoma subgroups. With regard to S-phase indices, ³HTLI was a powerful prognosticator in patients with high-grade histologies and FCM-S in patients with low-grade histologies. Multivariate analyses revealed that MIB-1 indiex, ³HTLI and FCM-S retained their prognostic significance independent of histology. In conclusion, the MIB-1 antibody provides prognostic information in non-Hodgkin's lymphomas and has the main advantage that it can be used in formalin-fixed, paraffin-embedded specimens.     

The neutrophil migration induced by tumour necrosis factor alpha in mice is unaffected by glucocorticoids

Macrophages harvested from the peritoneal cavities of rats release a neutrophil chemotactic factor (MNCF) in response to stimulation with Gram-negative bacterial lipopolysaccharide (LPS). MNCF has been shown to be active in rats treated with dexamethasone, a glucocorticoid that usually inhibits the neutrophil migration induced in this species by interleukin (IL)-1, tumour necrosis factor alpha (TNFalpha), IL-8, C5a and leukotriene B(4) (LTB(4)). Here we report that macrophages harvested from peritoneal cavities of mice, and stimulated in vitro with LPS, also release a factor that induces neutrophil migration in dexamethasone-treated animals. This chemotactic activity was neutralized by the incubation of the LPS-stimulated macrophage supernatants with a purified polyclonal IgG anti-mouse TNFalpha. In addition, significant amounts of TNF were detected in the supernatants. The neutrophil migration induced by intraperitoneal administration of recombinant murine TNFalpha was also unaffected by pretreatment of the mice with dexamethasone. Moreover, neutrophil migration induced by intraperitoneal injection of LPS was completely blocked by pretreatment of the mice with a monoclonal antibody against murine TNFalpha. In conclusion, our results support the hypothesis that, in contrast to the role of TNF in rats (where it indirectly induces neutrophil migration), in mice, it may be an important mediator in the recruitment of neutrophils to inflammatory sites.     

Linkage disequilibrium, mutational analysis and natural selection in the repetitive region of the clock gene, period, in Drosophila melanogaster

We have used the method of disequilibrium pattern analysis to examine associations between the threonine-glycine (Thr-Gly) encoding repeat region of the clock gene period (per) of Drosophila melanogaster, and polymorphic sites both upstream and downstream of the repeat, in a number of European fly populations. The results are consistent with the view that selection may be operating on various haplotypes which share the Thr-Gly length alleles encoding 17, 20 and 23 dipeptide pairs, and that the repeat itself may be the focus for selection. These conclusions lend support to a number of other population and behavioural investigations which have provided evidence that selection is acting on the Thr-Gly region. The linkage analysis was also used to infer an approximate mutation rate (mu) for the repeat, of 10(-5) < mu < 4 x 10(-5) per gamete per generation. Direct measurements of the mutation rate using the polymerase chain reaction in a pedigree analysis of tens of thousands of individuals do not contradict this value. Consequently, the Thr-Gly repeat does not have a mutation rate that is as high as some of the non-coding minisatellites, but it is several orders of magnitude higher than the nucleotide substitution rate. The implications of this elevated mutation rate for linkage disequilibria and selection are discussed.     

Characterization of novel long-chain 1,2-diols in Thermus species and demonstration that Thermus strains contain both glycerol-linked and diol-linked glycolipids.

In this study, we purified and characterized tetra- and triglycosyl glycolipids (GL-1 and GL-2, respectively) from two different colonial forms of Thermus scotoductus X-1, from T. filiformis Tok4 A2, and from T. oshimai SPS-11. Acid hydrolysis of the purified glycolipids liberated, in addition to the expected long-chain fatty acids, two components which were identified by gas chromatography-mass spectrometry as 16-methylheptadecane-1,2-diol and 15-methylheptadecane-1,2-diol. Fast atom bombardment mass spectrometry of the intact glycolipids indicated that a major proportion consisted of components with glycan head groups linked to long-chain 1,2-diols rather than to glycerol, although in all cases glycerol-linked compounds containing similar glycan head groups were also present. As in other Thermus strains, the polar head group of GL-1 from T. filiformis Tok4 A2 and from T. scotoductus X-1 colony type t2 was a glucosylgalactosyl-(N-acyl)glucosaminylglucosyl moiety. However, GL-2 from T. scotoductus X-1 colony type t1 and from T. oshimai SPS-11 was a truncated analog which lacked the nonreducing terminal glucose. Long-chain 1,2-diols have been previously reported in the polar lipids of Thermomicrobium roseum and (possibly) Chloroflexus aurantiacus, but to our knowledge, this is the first report of their detection in other bacteria and the first account of the structural determination of long-chain diol-linked glycolipids.     

Neurochemical effects ofl-pyroglutamic acid

The effect ofl-pyroglutamic acid, a metabolite that accumulates in pyroglutamic aciduria, on different neurochemical parameters was investigated in adult male Wistar rats. Glutamate binding, adenylate cyclase activity and G protein coupling to adenylate cyclase were assayed in the presence of the acid.l-pyroglutamic acid decreased Na⁺-dependent and Na⁺-independent glutamate binding Basal and GMP-PNP stimulated adenylate cyclase activity were not affected by the acid. Furthermore, rats received unilateral intrastriatal injections of 10–300 nmol of bufferedl-pyroglutamic acid. Vehicle (0.25 M Tris-Cl, pH 7.35–7.4) was injected into the contralateral striatum. Neurotoxic damage was assessed seven days after the injection by histological examination and by weighing both cerebral hemispheres. No difference in histology or weight could be identified between hemispheres. These results suggest that, although capable of interfering with glutamate binding, pyroglutamate did not cause a major lesion in the present model of neurotoxicity.     

Functional impairment of rat Kupffer cells induced by aflatoxin B1 and its metabolites

Abstract Contamination of food with mycotoxins is a major health problem. Impairment of several immune functions has been repeatedly reported in animals fed with contaminated fodder. Since the liver is a major target of toxicity by aflatoxins, the effects of aflatoxins B1, and its hepatic metabolites Q₁ and M₁ on Kupffer cell function was investigated in vitro. Aflatoxin B₁ induced significant ( P < 0.05) inhibition of phagocytosis, intracellular killing of Candida albicans , and intrinsic anti-Herpes virus activity at concentrations as low as 0.01 pg ml⁻¹. Aflatoxin Q₁ and M₁ had similar effects on phagocytosis and microbicidal activity, but were two- to ten-fold less potent than aflatoxin B₁.     

Hemispheric asymmetries in cortical electrical activity during sleep. I

The hypothesis of a predominance of the right hemisphere in stage REM as compared to NREM has been tested through a spectral analysis of the EEG recorded from left (T3) and right (T4) temporal sites in 5 young healthy right-handed male subjects. Variations in the asymmetry coefficient R - L/R + L in different sleep stages have been analyzed by one way ANOVAs and Sheffé's tests. The hypothesis of a progressive increase in left hemisphere activity throughout different REM cycles as one approaches final awakenings have been investigated by comparing variations in the asymmetry coefficient for epochs of REM and stage 2 NREM sampled in different phases of the REM cycle. EEG results do not support either the hypothesized stage dependent or cycle dependent variation in EEG activity during sleep. We question whether variations in EEG amplitude and synchronization can be used as indices of hemispheric asymmetries during sleep.     

Choline acetyltransferase- and peptide immunoreactivity of submucous neurons in the small intestine of the guinea-pig

Summary The peptides cholecystokinin (CCK), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and vasoactive intestinal peptide (VIP), and the synthesizing enzyme for acetylcholine, choline acetyltransferase (ChAT) were localized immunohistochemically in nerve cell bodies of the submucous ganglia in the small intestine of the guinea-pig. VIP-like immunoreactivity was found in 45% of submucous neurons. ChAT immunoreactivity was observed in a separate group of nerve cells, which made up 54% of the total population. There were three subsets of neurons immunoreactive for ChAT: (1) ChAT neurons that also contained immunoreactivity for each of the peptides CCK, SOM and NPY, representing 29% of all submucous neurons; (2) ChAT neurons that also contained SP-like immunoreactivity, representing 11% of all submucous neurons, and (3) ChAT cells that did not contain any detectable amount of the peptides that were localized in this study.