Population studies of the wild tomato species Solanum chilense reveal geographically structured major gene-mediated pathogen resistance

Natural plant populations encounter strong pathogen pressure and defence-associated genes are known to be under selection dependent on the pressure by the pathogens. Here, we use populations of the wild tomato Solanum chilense to investigate natural resistance against Cladosporium fulvum, a well-known ascomycete pathogen of domesticated tomatoes. Host populations used are from distinct geographical origins and share a defined evolutionary history. We show that distinct populations of S. chilense differ in resistance against the pathogen. Screening for major resistance gene-mediated pathogen recognition throughout the whole species showed clear geographical differences between populations and complete loss of pathogen recognition in the south of the species range. In addition, we observed high complexity in a homologues of Cladosporium resistance (Hcr) locus, underlying the recognition of C. fulvum, in central and northern populations. Our findings show that major gene-mediated recognition specificity is diverse in a natural plant-pathosystem. We place major gene resistance in a geographical context that also defined the evolutionary history of that species. Data suggest that the underlying loci are more complex than previously anticipated, with small-scale gene recombination being possibly responsible for maintaining balanced polymorphisms in the populations that experience pathogen pressure.     

Inhibition of AIDS virus replication by acemannan in vitro.

Acemannan (ACE-M), a beta-(1,4)-linked acetylated mannan, was evaluated for in vitro activity against human immunodeficiency virus type 1 (HIV-1). Castanospermine (CAS), deoxymannojirimycin (DMN), swainsonine (SWS), azidothymidine (AZT), and dideoxythymidine (DDC) were tested in parallel as control compounds. In vitro antiviral efficacy of ACE-M was evaluated in a variety of cell lines including human peripheral mononuclear, CEM-SS1 and MT-2(2) cells. The virus strain, number of infectious units per cell, and target cell line were important factors in determining the degree of inhibition of viral cytopathic effect in the presence of ACE-M and other control compounds tested. Maximum inhibitory effect was observed in CEM-SS cells infected with the RFII strain of HIV-1. This inhibitory effect was determined to be concentration-dependent. Assay design included primary screening to measure cell viabilities of infected target cells in the presence and absence of test compounds. When tested on HIV-1/RFII-infected CEM-SS cells, the 50% inhibitory effect of CAS (IC50 = 28), an inhibitor of alpha-glucosidase I, was determined to be similar to that observed for ACE-M (IC50 = 45). However, DMN and SWS, inhibitors of mannosidase I and II, tested in parallel to CAS and ACE-M, exhibited no IC50 values. Antiviral potential of ACE-M as an inhibitor of syncytia formation was also explored using CEM-SS cells. Suppression of syncytia formation was observed at an ACE-M concentration of 31.25 micrograms/ml, and complete inhibition was observed at 62.5 micrograms/ml. In addition, HIV-1 RNA levels were studied to establish the antiviral potential of ACE-M in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dehalogenation of 4 — Chlorobenzoic Acid by <Emphasis Type="Italic">Pseudomonas</Emphasis> isolates

Twenty three bacterial isolates either pure or consortium were initially screened on the basis of their ability to degrade as well as dechlorinate 4 — chlorobenzoic acid (4-CBA). Based on comparative growth response, three pure isolates Pseudomonas putida GVS-4, Pseudomonas aeruginosa GVS-18 and Pseudomonas aeruginosa GWS-19 and a consortium SW-2 was finally selected for further studies. The enzyme studies performed with cell free extracts revealed that dehalogenase activity was substrate specific with maximum activity at 300 μgml⁻¹ substrate concentration. Catechol 1,2 dioxygenase activity was found to be present in cell free extracts suggesting that 4 — chlorobenzoic acid (4-CBA) is catabolized by ortho-ring cleavage pathway. The dehalogenase enzyme profile showed single enzyme band in case of GVS-4 (Rm 0.76), GVS-18 (Rm 0.84), GWS −19 (Rm 0.85) and two bands in SW-2 (Rm 0.71 & 0.10).     

Molecular basis of bluetongue virus neutralization.

Molecular and serological analyses of bluetongue virus serotypes 10 and 11 and their intertype reassortants indicate that the viral RNA segment L2 codes for the serotype-specific antigen. Individual RNA segments of parental and reassortant viruses were characterized by oligonucleotide fingerprint analyses. Analyses of their virion polypeptides by Cleveland peptide mapping (Cleveland et al., J. Biol. Chem. 252:1102-1106, 1977) demonstrated that the L2 gene segregated colinearly with the viral P2 protein, implicating it as the antigen that is responsible for the viral serotype specificity.     

Reprint of BMCL_19101

The pathogenesis of rheumatoid arthritis is mainly driven by NF-κB-mediated production of cytokines, such as TNF-α. We report herein that the orally available imidazoline-based NF-κB inhibitor, TCH-013, was found to significantly reduce TNF-α signaling and attenuate collagen antibody induced arthritis in BALB/c mice.     

Interspecific variation of body shape and sexual dimorphism in three coexisting species of the genus <Emphasis Type="Italic">Petrotilapia</Emphasis> (Teleostei: Cichlidae) from Lake Malawi

Differences in color patterns have been the most used feature in describing cichlid species belonging to genus Petrotilapia from Lake Malawi. In this study, we quantified morphological variation in body shape within and among three coexisting Petrotilapia species using landmark-based geometric morphometric methods. Statistic analyses revealed significant body shape differences among species but not between sexes. Post hoc multiple comparisons based on Mahalanobis distances revealed that P. nigra was significantly different from P. genalutea and Petrotilapia sp., whereas the latter two were not significantly different. The splines generated showed that the most pronounced variation was in the head region, in which P. nigra had a relatively longer and deeper head than the other two. The most clear-cut distinction was in gape length; P. genalutea had the longest gape, followed by Petrotilapia sp., whereas P. nigra had the shortest gape. Body depth was shallower in P. nigra than the others. When comparing sexes by their centroid size, ANOVA revealed that males were bigger than females. Therefore, we conclude that color is not the only feature that can distinguish these congeners. We discuss the observed sexual dimorphism in terms of sexual selection and relate morphological variation among species to feeding behavior, which may help explain their coexistence in nature.     

Remodeling the isoprenoid pathway in tobacco by expressing the cytoplasmic mevalonate pathway in chloroplasts

Metabolic engineering to enhance production of isoprenoid metabolites for industrial and medical purposes is an important goal. The substrate for isoprenoid synthesis in plants is produced by the mevalonate pathway (MEV) in the cytosol and by the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway in plastids. A multi-gene approach was employed to insert the entire cytosolic MEV pathway into the tobacco chloroplast genome. Molecular analysis confirmed the site-specific insertion of seven transgenes and homoplasmy. Functionality was demonstrated by unimpeded growth on fosmidomycin, which specifically inhibits the MEP pathway. Transplastomic plants containing the MEV pathway genes accumulated higher levels of mevalonate, carotenoids, squalene, sterols, and triacyglycerols than control plants. This is the first time an entire eukaryotic pathway with six enzymes has been transplastomically expressed in plants. Thus, we have developed an important tool to redirect metabolic fluxes in the isoprenoid biosynthesis pathway and a viable multigene strategy for engineering metabolism in plants.