Antitumour activities of levans produced by Zymomonas mobilis strains

Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.     

The effect of substance P on the regional lymph node antibody response to antigenic stimulation in capsaicin-pretreated rats

The undecapeptide substance P (SP) contained in primary afferent nerves is thought to mediate that part of the neurogenic inflammatory response consisting of vasodilation and plasma extravasation. This response is diminished in rats pretreated as neonates with the neurotoxin capsaicin. It is not known whether primary afferent nerves influence cellular responses of the immune response to antigenic stimulation. Using 6- to 12-wk-old Sprague-Dawley rats pretreated as neonates with capsaicin, we examined the regional lymph node response to a s.c. antigenic stimulus of sheep red blood cells. The number of cells secreting antigen-specific antibody in these animals was reduced by more than 80% using direct and indirect plaque assay methods. The reduced antibody response in capsaicin-pretreated animals was reversed by a s.c. infusion of SP given over a 4-hr period at the injection site immediately after antigen stimulation. This response had a threshold at approximately 1.0 X 10(-5) M SP. SP1-7 (1.0 X 10(-5) M) was without effect but an infusion of SP5-11 (1.0 X 10(-5) M) reversed the effects of capsaicin treatment indicating a carboxyl-terminal effect of SP. The results suggest that the reduced response of capsaicin-treated animals to an antigenic stimulus is due to an effect of capsaicin on the SP-containing primary afferent nerves rather than a toxic effect of capsaicin on the immune system.     

Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex

The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S nuclear ribosomal DNA sequence and the intervening 5.8S region were sequenced from three individuals in each of eight taxa of the Mimulus guttatus species complex. Three discrete variants, or "types," of ITS sequences were found, among which 30%-40% of sites differed, compared with 1%-2% within types. Dot plots indicate that these types were not related by conspicuous rearrangements or inversions. More than one ITS type was often found in the same taxon, and two of three ITS types span species boundaries, indicating their presence prior to speciation. These ITS sequences showed essentially no positional homology with the nearest sequenced relative, tomato. In contrast, the 5.8S region was relatively unvaried, with 8 of 162 sites varied in the sample among all eight taxa. The phylogeny inferred by the most common ITS sequence type, rooted by the two other ITS types, agreed with isozymes in showing the distinctness of M. nudatus, M. laciniatus, and M. tilingii from the other five taxa.      

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

Physiological characterization of Mycobacterium sp. strain 1B isolated from a bacterial culture able to degrade high-molecular-weight polycyclic aromatic hydrocarbons

AIM: The aim of this study was to further characterize a bacterial culture (VUN 10,010) capable of benzo[a]pyrene cometabolism. METHODS AND RESULTS: The bacterial culture, previously characterized as a pure culture of Stenotrophomonas maltophilia (VUN 10,010), was found to also contain another bacterial species (Mycobacterium sp. strain 1B), capable of degrading a similar range of PAH substrates. Analysis of its 16S rRNA gene sequence and growth characteristics revealed the strain to be a fast-growing Mycobacterium sp., closely related to other previously isolated PAH and xenobiotic-degrading mycobacterial strains. Comparison of the PAH-degrading characteristics of Mycobacterium sp. strain 1B with those of S. maltophilia indicated some similarities (ability to degrade phenanthrene and pyrene), but some differences were also noted (S. maltophilia able to degrade fluorene, but not fluoranthene, whereas Mycobacterium sp. strain 1B can degrade fluoranthene, but not fluorene). Unlike the S. maltophilia culture, there was no evidence of benzo[a]pyrene degradation by Mycobacterium sp. strain 1B, even in the presence of other PAHs (ie pyrene) as co-metabolic substrates. Growth of Mycobacterium sp. strain 1B on other organic carbon sources was also limited compared with the S. maltophilia culture. CONCLUSIONS: This study isolated a Mycobacterium strain from a bacterial culture capable of benzo[a]pyrene cometabolism. The Mycobacterium strain displays different PAH-degrading characteristics to those described previously for the PAH-degrading bacterial culture. It is unclear what role the two bacterial strains play in benzo[a]pyrene cometabolism, as the Mycobacterium strain does not appear to have endogenous benzo[a]pyrene degrading ability. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes the isolation and characterization of a novel PAH-degrading Mycobacterium strain from a PAH-degrading culture. Further studies utilizing this strain alone, and in combination with other members of the consortium, will provide insight into the diverse roles different bacteria may play in PAH degradation in mixed cultures and in the environment.     

Ultraviolet light induced injury: immunological and inflammatory effects

This article reviews many of the complex events that occur after cutaneous ultraviolet (UV) exposure. The inflammatory changes of acute exposure of the skin include erythema (sunburn), the production of inflammatory mediators, alteration of vascular responses and an inflammatory cell infiltrate. Damage to proteins and DNA accumulates within skin cells and characteristic morphological changes occur in keratinocytes and other skin cells. When a cell becomes damaged irreparably by UV exposure, cell death follows via apoptotic mechanisms. Alterations in cutaneous and systemic immunity occur as a result of the UV-induced inflammation and damage, including changes in the production of cytokines by keratinocytes and other skin-associated cells, alteration of adhesion molecule expression and the loss of APC function within the skin. These changes lead to the generation of suppressor T cells, the induction of antigen-specific immunosuppression and a lowering of cell-mediated immunity. These events impair the immune system's capacity to reject highly antigenic skin cancers. This review gives an overview of the acute inflammatory and immunological events associated with cutaneous UV exposure, which are important to consider before dealing with the complex interactions that occur with chronic UV exposure, leading to photocarcinogenesis.     

Comparison of a range of green fluorescent protein-tagging vectors for monitoring a microbial inoculant in soil

Two new transposon-based tagging vectors have been constructed using the gfp marker gene under control of either constitutive or inducible promoters. The two vectors, along with the established pUTminiTn5gfp were used to tag a diesel-degrading Pseudomonas strain. Tagged strains were obtained that were not affected in terms of their growth or ability to use diesel as a carbon source. The transposon tags were stably maintained in the strains without selection and provided visible fluorescence as colonies or single cells in suspension. Tagging did not impede the survival of tagged Pseudomonas aeruginosa GP41B strains in diesel-contaminated soil microcosms. The tagged strains were easily recovered from the microcosms after a 3-month period. The tagging of bacteria with gfp using either native or introduced constitutive/inducible promoters is an effective and easy way to monitor their survival in soil.     

Expression of toll-like receptors on B lymphocytes

Toll-like receptors (TLRs) are a family of trans-membrane receptors that play an important role in the innate immune system. Most studies examining the cellular expression of TLRs on immune cells have focussed on neutrophils, monocytes and dendritic cells, but there is little evidence of TLRs being expressed on lymphocytes. Using 3-colour flow cytometry, expression of TLR-1, TLR-2, TLR-3, TLR-4, and TLR-9 on peripheral blood lymphocyte populations was determined. Further examination of TLRs on CD5- and CD5+ CD19+ B cell subsets was performed. The binding of TLR1 and TLR9 antibodies was detected on 15-90% of resting B cells, but not on resting T-cells. The higher expression of TLR1 and TLR9 on CD5+ B cells compared to CD5- B cells may reflect the role of B1 cells in more primitive, less specific antibody responses.     

Establishment of DsRed.T3_S4T as an improved autofluorescent marker for microbial ecology applications

Autofluorescent proteins (AFPs), such as green fluorescent protein (GFP) and DsRed, are valuable tools for studying plant-microbe interactions. Nevertheless, because of some limitations, efforts are ongoing to generate improved AFP variants. Several groups have generated variants of GFP with altered spectral characteristics, and faster maturing and brighter variants of DsRed. In this study we used plasmid and chromosomal constructs to test the efficacy of a new variant of DsRed, DsRed.T3_S4T, in Pseudomonas fluorescens F113rif. In addition, we compared the ecological fitness of strains carrying chromosomal copies of EGFP, DsRed or DsRed.T3_S4T. Strains expressing DsRed.T3_S4T fluoresced significantly brighter than strains expressing DsRed. Furthermore, it was found that although all strains grew equally well in vitro, only strains carrying DsRed.T3_S4T functioned as well as wild type in a competitive rhizosphere colonization assay. In particular, it was observed that DsRed.T3_S4T is an improved marker over DsRed for microbial ecology studies in this strain.