Antimicrobial activity of lipoprotein particles containing apolipoprotein Al

Human plasmain vitro inhibits the growth of coagulase negative staphylococci,S. epidermidis, which may be pathogenic in the immunocompromised host. To determine the antimicrobial components, serum was fractionated by column chromatography, which revealed that elution areas where lipoproteins can be yielded had high antimicrobial activity againstS. epidermidis. Therefore, lipoprotein fractions, including very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL), were separated by ultracentrifugation and incubated withS. epidermidis. All 3 lipoprotein fractions suppressed bacterial growth within the first 3 h but VLDL enhanced bacterial growth after 9 h of incubation compared with the control. HDL, however, inhibited bacterial growth throughout 21 h of incubation.To confirm these results, serum from healthy volunteers was separated by ion exchange column chromatography and again by HPLC to purify the antimicrobial fraction. In the protein analysis with gradient polyacrylamide-SDS gel, apolipoprotein Al (apo Al), which is a major apolipoprotein of HDL, was detected in the antimicrobial fraction. Therefore, this fraction was loaded onto an immunoaffinity column coupled with the anti-apo Al monoclonal antibody (Mab). Unbound fraction had no antimicrobial activity, but anti-S. epidermidis activity was recovered from the bound fraction which consisted mainly of apo Al, All and apo C in protein composition.These results indicated that the antimicrobial activity was associated with the apo Al-containing lipoprotein particles (HDL). This property of HDL may directly affect bacterial growth and promote the self-defense mechanisms of normal and immunocompromised individuals.     

Novel relationship between the antifungal activity and cytotoxicity of marine-derived metabolite xestoquinone and its family

Xestoquinone and related metabolites (the xestoquinone family) occur in marine sponges and are known to show a variety of biological activities. In this study, the first comprehensive evaluation of antifungal activity was performed for xestoquinone and nine natural and unnatural analogues in comparison with their cytotoxicity. The cytotoxicity against two human squamous cell carcinoma cell lines, A431 and Nakata, indicated that the terminal quinone structure of the polycyclic molecules was important (xestoquinone, etc.) and that the presence of a ketone group at C-3 of the opposite terminus dramatically diminished the activity (halenaquinone, etc.). In contrast, a ketone group at C-3 enhanced the antifungal activity against the plant pathogen, Phytophthora capsici, regardless of the presence of a quinone moiety. The cytotoxicity and antifungal activity of the xestoquinone family were negatively correlated with each other.     

Biosynthesis of Firefly Luciferin in Adult Lantern: Decarboxylation of ?-Cysteine is a Key Step for Benzothiazole Ring Formation in Firefly Luciferin Synthesis

Background

Bioluminescence in fireflies and click beetles is produced by a luciferase-luciferin reaction. The luminescence property and protein structure of firefly luciferase have been investigated, and its cDNA has been used for various assay systems. The chemical structure of firefly luciferin was identified as the ᴅ-form in 1963 and studies on the biosynthesis of firefly luciferin began early in the 1970’s. Incorporation experiments using ¹⁴C-labeled compounds were performed, and cysteine and benzoquinone/hydroquinone were proposed to be biosynthetic component for firefly luciferin. However, there have been no clear conclusions regarding the biosynthetic components of firefly luciferin over 30 years.

Methodology/Principal Findings

Incorporation studies were performed by injecting stable isotope-labeled compounds, including ʟ-[U-¹³C₃]-cysteine, ʟ-[1-¹³C]-cysteine, ʟ-[3-¹³C]-cysteine, 1,4-[D₆]-hydroquinone, and p-[2,3,5,6-D]-benzoquinone, into the adult lantern of the living Japanese firefly Luciola lateralis. After extracting firefly luciferin from the lantern, the incorporation of stable isotope-labeled compounds into firefly luciferin was identified by LC/ESI-TOF-MS. The positions of the stable isotope atoms in firefly luciferin were determined by the mass fragmentation of firefly luciferin.

Conclusions

We demonstrated for the first time that ᴅ- and ʟ-firefly luciferins are biosynthesized in the lantern of the adult firefly from two ʟ-cysteine molecules with p-benzoquinone/1,4-hydroquinone, accompanied by the decarboxylation of ʟ-cysteine.     

Soil-eating byAlouatta andAteles

Among 12 species of New World monkeys studied in La Macarena Region and the River Caquetá basin of Colombia, onlyAlouatta seniculus andAteles belzebuth were frequently observed to eat soil. They do this at particular sites on the ground called salados by local people. They also eat termite nests found on tree trunks. OnlyAteles drink the water of salado sites. The chemical properties of 17 soil samples and 5 water samples were analyzed. The results are discussed in relation to the question of whyAlouatta andAteles eat soil.     

Novel cerebroside, termitomycesphin I, from the mushroom, Termitomyces titanicus

The novel cerebroside, termitomycesphin I (1), and two known cerebrosides (2 and 3) were isolated from the edible mushroom, Termitomyces titanicus. The structures of 1-3 were determined and identified by interpreting the spectroscopic data.     

Effects of interleukin-12 on in vitro culture with interleukin-2 of regional lymph node lymphocytes from lung cancer patients

 In the present study, we carried out a functional analysis of regional lymph node lymphocytes (RLNL) from patients with lung cancer after in vitro activation by interleukin-2 (IL-2) and interleukin-12 (IL-12). IL-12 (100 U/ml) enhanced both the proliferation and cytotoxic activity of RLNL in a culture with low doses of IL-2 (5 – 10 JRU/ml). After comparing an RLNL culture with a low dose of IL-2 alone, a higher proportion of CD8⁺ cells and CD56⁺ cells and a lower proportion of CD4⁺ cells were found in the culture with both IL-12 and a low dose of IL-2. Such a combination of the cytokines effectively activated RLNL in terms of the expression of IL-2 receptors. In the culture condition of IL-12 and a low dose of IL-2, a synergistic effect was observed in the production of such cytokines as interferon γ, tumor necrosis factor α (TNFα), and TNFβ, as well as in tumor cytotoxicity. However, the addition of IL-12 inhibited the cytotoxicity of RLNL in the culture with a high dose of IL-2 (100 JRU/ml). This inhibition is considered to be partially due to the endogenous production of TNFα by lymphocytes, because the neutralization of TNFα bioactivity partially restored the cytotoxic activities of RLNL. Furthermore, in the presence of hydrocortisone, IL-12 synergistically enhanced the cytotoxic activity of RLNL cultured with a high dose of IL-2. These results provide useful information about the improvement of adoptive immunotherapy against cancer using RLNL. Received: 2 February 1996 / Accepted: 30 July 1996