Behavioral responses to the alarm pheromone of the ant Camponotus obscuripes (Hymenoptera: Formicidae)

The alarm pheromone of the ant Camponotus obscuripes (Formicinae) was identified and quantified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Comparisons between alarm pheromone components and extracts from the major exocrine gland of this ant species revealed that the sources of its alarm pheromone are Dufour's gland and the poison gland. Most components of Dufour's gland were saturated hydrocarbons. n-Undecane comprised more than 90% of all components and in a single Dufour's gland amounted to 19 microg. n-Decane and n-pentadecane were also included in the Dufour's gland secretion. Only formic acid was detected in the poison gland, in amounts ranging from 0.049 to 0.91 microl. This ant species releases a mixture of these substances, each of which has a different volatility and function. When the ants sensed formic acid, they eluded the source of the odor; however, they aggressively approached odors of n-undecane and n-decane, which are highly volatile. In contrast, n-pentadecane, which has the lowest volatility among the identified compounds, was shown to calm the ants. The volatilities of the alarm pheromone components were closely related to their roles in alarm communication. Highly volatile components vaporized rapidly and spread widely, and induced drastic reactions among the ants. As these components became diluted, the less volatile components calmed the excited ants. How the worker ants utilize this alarm communication system for efficient deployment of their nestmates in colony defense is also discussed herein.     

Mechanism of plasma glutathione peroxidase production in bovine adipocytes

CD97, an epidermal growth factor (EGF)-TM7 receptor, is not restricted to hematopoetic and carcinoma cells but is also found on smooth muscle cells (SMC). We have examined its location and biochemical structure in various normal and tumorigenic SMC-containing tissues. SMC of the urinary bladder, lung bronchi and bronchioles, myometrium, and gastrointestinal tract were immunohistologically stained by using monoclonal antibodies (mabs) to the CD97 stalk region (CD97^stalk). Mabs directed against an N-glycosylation-dependent epitope within the EGF-domains (CD97^EGF) did not bind to normal SMC. Vascular SMC, which was also CD97^EGF-negative, showed further CD97 heterogeneity. Only a few, if any, SMC from the aorta or elastic arteries of the systemic circulation were positive for CD97 mRNA and therefore also for CD97^stalk. CD97^stalk-positive SMC were slightly more numerous in muscular and peripheral arteries. In contrast, most venous SMC expressed CD97^stalk. A comparison with other SMC molecules revealed a similar but not identical staining pattern for CD97^stalk and desmin. Further CD97 heterogeneity was observed during SMC transformation. All leiomyomas (n=5) and nine out of 21 leiomyosarcomas were positive for both CD97^stalk and CD97^EGF. As expected, CD97^EGF-positive SMC tumors expressed partly N-glycosylated CD97. Seven out of 21 leiomyosarcomas were completely devoid of CD97. Thus, CD97 showed variable expression in vascular and biochemical modification in tumorigenic SMC, suggesting that the function of the molecule is specific for the SMC subtype. This study was supported by a joint grant from the German Research Council (DFG; project AU 132/3-1) and by the Interdisziplinary Center of Clinical Research (IZKF) Leipzig at the Faculty of Medicine, University of Leipzig (project D6). E. Wandel is a fellow of the IZKF.     

Analysis of a rare melanoma patient with a spontaneous CTL response to a MAGE-A3 peptide presented by HLA-A1

We describe an HLA-A1 melanoma patient who has mounted a spontaneous cytolytic T cell (CTL) response against an antigenic peptide encoded by gene MAGE-A3 and presented by HLA-A1. The frequency of anti-MAGE-3.A1 CTLp was 5×10⁻⁷ of the blood CD8 cells, with a dominant clonotype which was present in six out of seven independent anti-MAGE-3.A1 CTL clones. After vaccination with a recombinant poxvirus coding for the MAGE-3.A1 antigen, the blood frequency of anti-MAGE-3.A1 CTLp increased tenfold. Twenty-two independent CTL clones were derived. Surprisingly, only one of them corresponded to the dominant clonotype present before vaccination. Two new clonotypes were repeated 12 and 7 times, respectively. Our interpretation of these results is that the spontaneous anti-MAGE-3.A1 CTL response pre-existing to vaccination was polyclonal, and that the vaccine restimulated only some of these clones. To estimate the incidence of spontaneous anti-MAGE-3.A1 CTL responses in melanoma patients with a tumor expressing gene MAGE-A3, we measured the blood frequency of anti-MAGE-3.A1 T cells in 45 patients, and found only two clear responses.     

SFTG international collaborative study on in vitro micronucleus test III. Using CHO cells

In this report, results are presented from an international study of the in vitro micronucleus assay using Chinese hamster ovary cells. This study was coordinated by an organizing committee supported by the SFTG (the French branch of the European Environmental Mutagen Society). Test chemicals included mannitol, bleomycin, cytosine arabinoside, urethane and diethylstilboestrol. Mitomycin C was used as a positive control. Each chemical was evaluated in at least two laboratories following a variety of different protocols (short and long exposures, varying recovery times, with and without cytochalasin B) in order to help determine a standard protocol for routine testing in Chinese hamster ovary cells. Mannitol and urethane were negative, while bleomycin, cytosine arabinoside and diethylstilboestrol induced a dose dependent increase in micronucleated cells. In the presence of cytochalasin B, increases in micronuclei were observed in binucleated as well as mononucleated cells in cultures treated with bleomycin, cytosine arabinoside or diethylstilboestrol. Importantly, all three of these chemicals were detected in each of the different treatment/recovery regimens. No differences were seen in the sensitivity or accuracy of the responses in the presence of absence of cytochalasin B. Overall, these results demonstrate the suitability of Chinese hamster ovary cells for the in vitro micronucleus assay.     

Enhanced tolerance to ozone and drought stresses in transgenic tobacco overexpressing dehydroascorbate reductase in cytosol

Ascorbate (vitamin C) is a potent antioxidant protecting plants against oxidative damage imposed by environmental stresses such as ozone and drought. Dehydroascorbate reductase (DHAR; EC 1.8.5.1) is one of the two important enzymes functioning in the regeneration of ascorbate (AsA). To examine the protective role of DHAR against oxidative stress, we developed transgenic tobacco plants overexpressing cytosolic DHAR gene from Arabidopsis thaliana . Incorporation of the transgene in the genome of tobacco plants was confirmed by polymerase chain reaction and Southern blot analysis, and its expression was confirmed by Northern and Western blot analyses. These transgenic plants exhibited 2.3–3.1 folds higher DHAR activity and 1.9–2.1 folds higher level of reduced AsA compared with non-transformed control plants. The transgenic plants showed maintained redox status of AsA and exhibited an enhanced tolerance to ozone, drought, salt, and polyethylene glycol stresses in terms of higher net photosynthesis. In this study, we report for the first time that the elevation of AsA level by targeting DHAR overexpression in cytosol properly provides a significantly enhanced oxidative stress tolerance imposed by drought and salt.     

Degradation of Tributyltin in Microcosm Using Mekong River Sediment

The degradation of tributyltin (TBT) and changes of bacterial number and community structures were investigated in microcosms using the sediment collected from the Mekong River, Vietnam. Concentrations of TBT in sediments were less than 0.62 ng/g (dry wt), lower than those reported from other areas. TBT-resistant bacteria were found in the three sampling sites, and the occurrence rates were 11–16% out of the total viable count. In this microcosm experiment, initial concentration of TBT [1.0–1.4 μg/g (dry wt)] decreased to 0.6 μg/g (dry wt) during 150 days, whereas that in the control microcosm with autoclaved sediment did not change, indicating that Mekong River sediment contains high TBT-degrading activity by microorganisms. The occurrence of TBT-resistant bacteria and the bacterial community structures monitored by denaturing gradient gel electrophoresis were almost the same between test and control groups, indicating that the addition of TBT had little influence on microbial community structure. Mekong River sediment seems to have a stable microbial community against TBT pollution.     

Cloning and expression of two crystal protein genes, cry30Ba1 and cry44Aa1, obtained from a highly mosquitocidal strain, Bacillus thuringiensis subsp. entomocidus INA288

Two novel crystal protein genes, cry30Ba and cry44Aa, were cloned from Bacillus thuringiensis subsp. entomocidus INA288 and expressed in an acrystalliferous strain. Cry44Aa crystals were highly toxic to second-instar Culex pipiens pallens (50% mortality concentration [LC50] = 6 ng/ml) and Aedes aegypti (LC50 = 12 ng/ml); however, Cry30Ba crystals were not toxic.     

EshA accentuates ppGpp accumulation and is conditionally required for antibiotic production in Streptomyces coelicolor A3(2)

Disruption of eshA, which encodes a 52-kDa protein that is produced late during the growth of Streptomyces coelicolor A3(2), resulted in elimination of actinorhodin production. In contrast, disruption of eshB, a close homologue of eshA, had no effect on antibiotic production. The eshA disruptant accumulated lower levels of ppGpp than the wild-type strain accumulated. The loss of actinorhodin production in the eshA disruptant was restored by expression of a truncated relA gene, which increased the ppGpp level to the level in the wild-type strain, indicating that the reduced ppGpp accumulation in the eshA mutant was solely responsible for the loss of antibiotic production. Antibiotic production was also restored in the eshA mutant by introducing mutations into rpoB (encoding the RNA polymerase β subunit) that bypassed the requirement for ppGpp, which is consistent with a role for EshA in modulating ppGpp levels. EshA contains a cyclic nucleotide-binding domain that is essential for its role in triggering actinorhodin production. EshA may provide new insights and opportunities to unravel the molecular signaling events that occur during physiological differentiation in streptomycetes.