Antiviral activity of <Emphasis Type="Italic">Cleome rosea</Emphasis> extracts from field-grown plants and tissue culture-derived materials against acyclovir-resistant <Emphasis Type="Italic">Herpes simplex</Emphasis> viruses type 1 (ACVr-HSV-1) and type 2 (ACVr-HSV-2)

Extracts from Cleome rosea were investigated for their activity against acyclovir-resistant strains of Herpes simplex type 1 (ACVr-HSV-1) and type 2 (ACVr-HSV-2). Methanolic and acidified (1% (v/v) HCl) methanolic extracts were prepared from field-grown plants and in vitro propagated plants, as well as from calli and cell suspension cultures. The extracts presented low cytotoxicity and caused virus titer reduction above 70%, with different mechanisms of action. Extracts from leaves of field-grown plants inhibited viral infection mainly by affecting the virus particle itself (virucidal effect), while extracts from calli acted mainly on cell receptors. On the other hand, all extracts evaluated affected the virus entry across the cell membrane and the intracellular viral replication at similar percentages, causing reduction on titers in the range of 68–90%. This study validated the potential use of in vitro materials as sources of antiherpetic agents from C. rosea.     

Osmotic stress at membrane level and photosystem II activity in two C4 plants after growth in elevated CO2 and temperature

In the last two decades, several studies have evaluated plant physiology, growth and survival under forecasted climate changes and the effects of these environmental factors in plants are started to be understood. However, there are few studies evaluating such effects at the tissue or cellular level, especially for plants with photosynthetic C4 metabolism that are believed to respond less to elevated CO₂ concentration. For this reason, we tested maize and pearl millet plants to consider cellular physiological responses to induce osmotic stress and acute heat shock. Plants were grown under elevated CO₂ concentration and temperature, simulating global climate changes and then were subjected to osmotic stress and acute heat shock in vitro. The results indicated that the growth under elevated CO₂ and temperature improved cellular tolerance to osmotic stress and acute heat shock for both species, but maize seemed to benefit more from increased CO₂ concentration whereas pearl millet seemed to benefit more from increased temperature. Taken together, the results indicated that the current and expected global climate changes, besides operating differentially in these two species, can similarly affect other C4 plant species in different ecosystems whether undisturbed or managed.     

Mycelium of Arbuscular Mycorrhizal fungi (AMF) from different genera: form, function and detection

It is often assumed that all species of arbuscular mycorrhizal fungi (AMF) have the same function because of the ubiquity of the arbuscular mycorrhizal symbiosis and the fact that all AMF occupy the same plant/soil niche. Despite apparent differences in the timing of evolutionary divergence and the morphological characteristics of AMF from the different genera, the majority of studies on these fungi use only species of Glomus. There is increasing evidence, however, that the mechanisms involved in the establishment of a mycorrhiza may differ for species and genera of AMF and influence their subsequent function. The aim of this paper is to highlight the diversity in the form and function of AMF from different genera, knowledge of which is vital in understanding their ecological roles. Potential use of biochemical and molecular approaches to detect AMF in planta and ex planta is also discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

The role of BAP in somatic embryogenesis induction from seed explants of <Emphasis Type="Italic">Arachis</Emphasis> species from Sections <Emphasis Type="Italic">Erectoides</Emphasis> and <Emphasis Type="Italic">Procumbentes</Emphasis>

Somatic embryogenesis was induced from seed explants of Arachis archeri, A. porphyrocalix (Section Erectoides) and A. appressipila (Section Procumbentes) in response to 6-benzylaminopurine (BAP). Embryo axes first developed into single shoots in response to 4.4 μM BAP. Friable embryogenic calluses were produced from the hypocotyl region of these explants in response to different BAP concentrations. Embryonic leaflets also gave rise to friable calluses, but somatic embryos were only observed in explants of A. archeri and A. appressipila. Histological analyses revealed the presence of heart-shaped, torpedo and cotyledonary stages embryos, both as isolated and fused structures. A low frequency of embryo-to-plant conversion was achieved by inducing shoot development on medium solidified with 0.5% phytagel and supplemented with 1.5% or 3% sucrose. Rooting was induced on MS supplemented with indole-3-acetic acid (IAA).     

The Asp299Gly polymorphism alters TLR4 signaling by interfering with recruitment of MyD88 and TRIF

Asp(299)Gly (D299G) and, to a lesser extent, Thr(399)Ile (T399I) TLR4 polymorphisms have been associated with gram-negative sepsis and other infectious diseases, but the mechanisms by which they affect TLR4 signaling are unclear. In this study, we determined the impact of the D299G and T399I polymorphisms on TLR4 expression, interactions with myeloid differentiation factor 2 (MD2), LPS binding, and LPS-mediated activation of the MyD88- and Toll/IL-1R resistance domain-containing adapter inducing IFN-β (TRIF) signaling pathways. Complementation of human embryonic kidney 293/CD14/MD2 transfectants with wild-type (WT) or mutant yellow fluorescent protein-tagged TLR4 variants revealed comparable total TLR4 expression, TLR4-MD2 interactions, and LPS binding. FACS analyses with anti-TLR4 Ab showed only minimal changes in the cell-surface levels of the D299G TLR4. Cells transfected with D299G TLR4 exhibited impaired LPS-induced phosphorylation of p38 and TANK-binding kinase 1, activation of NF-κB and IFN regulatory factor 3, and induction of IL-8 and IFN-β mRNA, whereas T399I TLR4 did not cause statistically significant inhibition. In contrast to WT TLR4, expression of the D299G mutants in TLR4(-/-) mouse macrophages failed to elicit LPS-mediated induction of TNF-α and IFN-β mRNA. Coimmunoprecipitation revealed diminished LPS-driven interaction of MyD88 and TRIF with the D299G TLR4 species, in contrast to robust adapter recruitment exhibited by WT TLR4. Thus, the D299G polymorphism compromises recruitment of MyD88 and TRIF to TLR4 without affecting TLR4 expression, TLR4-MD2 interaction, or LPS binding, suggesting that it interferes with TLR4 dimerization and assembly of intracellular docking platforms for adapter recruitment.     

Purification and characterization of jararassin-I, A thrombin-like enzyme from Bothrops jararaca snake venom

Snake venoms of the Viperidae family contain a numberof proteins that cause hemostatic disturbances. Enveno-mation of this family is characterized by hemorrhage,edema, local tissue damage, myonecrosis, fibrinolytic andkinin releasing activities [1]. In southeastern Brazil, theviper Bothrops jararaca (Viperidae) is responsible for 90%of snakebite accidents [2]. The enzymes that have proteolytic, coagulate andhemorraghic activities can activate or interfere withthe process of coagulation, and…     

Taraxerol 4‐Methoxybenzoate,an in vitro Inhibitor of Photosynthesis Isolated from Pavonia multiflora A. St‐Hil. (Malvaceae)

A phytochemical study of Pavonia multiflora A. St ‐Hil . (Malvaceae) led to the isolation through chromatographic techniques of 10 secondary metabolites: vanillic acid ( 1 ), ferulic acid ( 2 ), p‐hydroxybenzoic acid ( 3 ), p‐coumaric acid ( 4 ), loliolide ( 5 ), vomifoliol ( 6 ), 4,5‐dihydroblumenol A ( 7 ), 3‐oxo‐α‐ionol ( 9 ), blumenol C ( 10 ), and taraxerol 4‐methoxybenzoate ( 8 ), the latter being a novel metabolite. Their structures were identified by ¹H‐ and ¹³C‐NMR, using one‐ and two‐dimensional techniques, and X‐ray crystallography. In this work, we report the effect of compounds 5 and 8 on several photosynthetic activities in an attempt to search for new compounds as potential herbicide agents that affect photosynthesis. Both compounds inhibited the electron flow from H₂O to methyl viologen; therefore, they act as Hill reaction inhibitors. Using polarographic techniques and studies of the fluorescence of chlorophyll a, the interaction sites of these compounds were located at photosystem II.     

Purification and characterization of hemolysin from periodontopathogenic bacterium Eikenella corrodens strain 1073

Eikenella corrodens 1073 was found to show hemolytic activity when grown on sheep blood agar. A high and dose-dependent hemolytic activity was detected in the cell envelope fraction, which was further purified by ion-exchange and gel-filtration chromatography. Consequently, a 65-kDa protein with hemolytic activity was obtained, suggesting that this protein might be a hemolysin. Its N-terminal amino acid sequence was nearly identical to that of X-prolyl aminopeptidase from E. corrodens ATCC 23834. To confirm that X-prolyl aminopeptidase functions as a hemolytic factor, we expressed the hlyA gene, encoding X-prolyl aminopeptidase, in Escherichia coli. After induction with isopropyl β-D-1-thiogalactopyranoside, a protein of about 65 kDa was purified on a Ni column, and its hemolytic activity was confirmed. Meanwhile, a strain with a disrupted hlyA gene, which was constructed by homologous recombination, did not show any hemolytic activity. These results suggested that X-prolyl aminopeptidase might function as a hemolysin in E. corrodens.