Opposite effects of low and high doses of the gastrin-releasing peptide receptor antagonist RC-3095 on memory consolidation in the hippocampus: possible involvement of the GABAergic system

Although the gastrin-releasing peptide receptor (GRPR) has recently emerged as a system importantly involved in regulating memory formation, the role of hippocampal GRPRs in memory remains controversial. The present study examined the effects of GRPR antagonism on memory consolidation in area CA1 of the hippocampus. Male Wistar rats received bilateral infusions of the GRPR antagonist [D-Tpi6, Leu13 psi(CH2NH)-Leu14] bombesin (6-14) (RC-3095; 1, 3, or 10 microg/side) into the dorsal hippocampus immediately after inhibitory avoidance (IA) training. RC-3095 at 1 microg impaired, whereas the dose of 10 microg enhanced, 24-h IA retention. A second experiment showed that the RC-3095-induced enhancement of memory consolidation was prevented by pretraining infusion of an otherwise ineffective dose of the gamma-aminobutyric acid type A (GABA(A)) receptor agonist muscimol. The results indicate that high doses of GRPR antagonists can induce enhancement of memory consolidation in the hippocampus. In addition, the memory-enhancing effect of GRPR antagonists might be mediated by inhibition of GABAergic transmission.     

Dexamethasone reverses the memory impairment induced by antagonism of hippocampal gastrin-releasing peptide receptors

Storage of emotionally influenced memory is regulated by activation of glucocorticoid receptors (GRs) as well as of gastrin-releasing peptide receptors (GRPRs) in the dorsal hippocampus. In the present study, male Wistar rats were given a bilateral infusion of saline or the GRPR antagonist (D-Tpi6, Leu13 psi[CH2NH]-Leu14) bombesin (6-14) (RC-3095) (1.0 microg/side) into the dorsal hippocampus 10 min before training on an inhibitory avoidance task, followed by an immediate post-training i.p. injection of vehicle or the GR agonist dexamethasone (0.3 mg/kg). A retention test trial, carried out 24 h after training, indicated that intrahippocampal infusion of RC-3095 impaired inhibitory avoidance retention. Post-training administration of dexamethasone induced an enhancement of retention regardless of whether the animals had received saline or RC-3095 into the hippocampus before training. The findings indicate that hippocampal GRPR blockade does not prevent memory enhancement induced by dexamethasone. Together with previous results, these findings suggest that endogenous activation of GRPRs in the hippocampus modulates the consolidation of emotional memory, but is not a critical receptor system mediating memory formation.     

Non-associative learning and anxiety in rats treated with a single systemic administration of the gastrin-releasing peptide receptor antagonist RC-3095

The gastrin-releasing peptide receptor (GRPR) has been implicated in the modulation of emotionally-motivated memory. In the present study, we investigated the role of the GRPR on non-emotional, non-associative memory, and anxiety. Adult male Wistar rats were given a systemic injection of the GRPR antagonist [D-Tpi⁶, Leu¹³ psi(CH₂NH)-Leu¹⁴] bombesin (6–14) (RC-3095) (0.2, 1.0 or 5.0 mg/kg) 30 min before exposure to an open field or an elevated plus maze. Habituation to the open field was tested in a retention trial carried out 24 h after the first exposure to the open field. Rats given RC-3095 at the doses of 1.0 or 5.0 mg/kg showed impaired habituation. Animals treated with 5.0 mg/kg of RC-3095 spent significantly more time in the closed arms of the elevated plus maze. No effects of RC-3095 on locomotion or exploratory behavior were observed. The results implicate the GRPR in the regulation of non-emotional, non-associative memory as well as in anxiety.     

A gastrin-releasing peptide receptor antagonist blocks D-amphetamine-induced hyperlocomotion and increases hippocampal NGF and BDNF levels in rats

The gastrin-releasing peptide receptor (GRPR) has emerged as a novel molecular target in neurological and psychiatric disorders, and previous animal studies suggest that GRPR antagonists might display cognitive-enhancing and antipsychotic properties. Hyperlocomotion produced by administration of D-amphetamine (D-AMPH) to rats has been put forward as a model of the manic phase of bipolar disorder (BD). In the present study, we examined the effects of a single systemic administration of the GRPR antagonist [D-Tpi(6), Leu(13) psi(CH(2)NH)-Leu(14)] bombesin (6-14) (RC-3095) on hyperlocomotion induced by a single systemic injection of D-AMPH in male rats. We also evaluated the levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the hippocampus of rats treated with D-AMPH and RC-3095. Administration of RC-3095 at any of the doses used blocked D-AMPH-induced hyperlocomotion. Specific doses of RC-3095 increased the levels of NGF and BDNF in the dorsal hippocampus. Administration of D-AMPH did not affect NGF or BDNF levels by itself, but blocked the RC-3095 effects. The results suggest that GRPR antagonists might display anti-manic activity.     

Gastrin-Releasing Peptide Receptor Antagonism Induces Protection from Lethal Sepsis: Involvement of Toll-like Receptor 4 Signaling

In sepsis, toll-like receptor (TLR)-4 modulates the migration of neutrophils to infectious foci, favoring bacteremia and mortality. In experimental sepsis, organ dysfunction and cytokines released by activated macrophages can be reduced by gastrin-releasing peptide (GRP) receptor (GRPR) antagonist RC-3095. Here we report a link between GRPR and TLR-4 in experimental models and in sepsis patients. RAW 264.7 culture cells were exposed to lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-α and RC-3095 (10 ng/mL). Male Wistar rats were subjected to cecal ligation and puncture (CLP), and RC-3095 was administered (3 mg/kg, subcutaneously); after 6 h, we removed the blood, bronchoalveolar lavage, peritoneal lavage and lung. Human patients with a clinical diagnosis of sepsis received a continuous infusion with RC-3095 (3 mg/kg, intravenous) over a period of 12 h, and plasma was collected before and after RC-3095 administration and, in a different set of patients with systemic inflammatory response syndrome (SIRS) or sepsis, GRP plasma levels were determined. RC-3095 inhibited TLR-4, extracellular-signal–related kinase (ERK)-1/2, Jun NH₂-terminal kinase (JNK) and Akt and decreased activation of activator protein 1 (AP-1), nuclear factor (NF)-κB and interleukin (IL)-6 in macrophages stimulated by LPS. It also decreased IL-6 release from macrophages stimulated by TNF-α. RC-3095 treatment in CLP rats decreased lung TLR-4, reduced the migration of cells to the lung and reduced systemic cytokines and bacterial dissemination. Patients with sepsis and systemic inflammatory response syndrome have elevated plasma levels of GRP, which associates with clinical outcome in the sepsis patients. These findings highlight the role of GRPR signaling in sepsis outcome and the beneficial action of GRPR antagonists in controlling the inflammatory response in sepsis through a mechanism involving at least inhibition of TLR-4 signaling.     

A gastrin-releasing peptide receptor antagonist stimulates Neuro2a neuroblastoma cell growth: Prevention by a histone deacetylase inhibitor

Gastrin-releasing peptide (GRP) acts as an autocrine growth factor for neuroblastoma and other types of cancer, and its cell-surface receptor, GRPR, is overexpressed in advanced-stage human neuroblastoma. GRPR knockdown and GRPR antagonism inhibit the growth of experimental neuroblastoma. Here we show that a GRPR antagonist promotes rather than inhibits the growth of neuroblastoma cells. The GRPR antagonist, RC-3095, at 0.1 nM inhibited, whereas at 100 nM stimulated proliferation of Neuro2a murine neuroblastoma cells in vitro. The stimulatory effects were prevented by the histone deacetylase inhibitor (HDACi), sodium butyrate (NaB). Expression of GRPR mRNA in Neuro2a cells was analyzed by RT-PCR. These findings provide evidence that a GRPR antagonist can stimulate the growth of cancer cells, and suggest that GRPR might interact with epigenetic mechanisms in regulating neuroblastoma cell growth.     

Gastrin-releasing peptide and its receptor increase arthritis fibroblast-like synoviocytes invasiveness through activating the PI3K/AKT pathway

Rheumatoid arthritis (RA) is an autoimmune disease that leads to joint destruction. The fibroblast-like synoviocytes (FLS) has a central role on the disease pathophysiology. The present study aimed to examine the role of gastrin-releasing peptide (GRP) and its receptor (GRPR) on invasive behavior of mice fibroblast-like synoviocytes (FLS), as well as to evaluate GRP-induced signaling on PI3K/AKT pathway. The expression of GRPR in FLS was investigated by immunocytochemistry, western blot (WB) and qRT-PCR. The proliferation and invasion were assessed by SRB and matrigel-transwell assay after treatment with GRP and/or RC-3095 (GRPR antagonist), and/or Ly294002 (inhibitor of PI3K/AKT pathway). Finally, AKT phosphorylation was assessed by WB. GRPR protein was detected in FLS and the exposure to GRP increased FLS invasion by nearly two-fold, compared with untreated cells (p < 0.05), while RC-3095 reversed that effect (p < 0.001). GRP also increased phosphorylated AKT expression in FLS. When Ly294002 was added with GRP, it prevented the GRP-induced increased cell invasiveness (p < 0.001). These data suggest that GRPR expression in FLS and that exogenous GRP are able to activate FLS invasion. This effect occurs at least in part through the AKT activation. Therefore, understanding of the GRP/GRPR pathway could be relevant in the development of FLS-targeted therapy for RA.     

Intrahippocampal infusion of the bombesin/gastrin-releasing peptide antagonist RC-3095 impairs inhibitory avoidance retention

Bombesin (BN)-like peptides regulate cell proliferation and cancer growth as well as neuroendocrine and neural functions. We evaluated the effects of the BN/gastrin-releasing peptide (GRP) antagonist RC-3095 on memory formation. Male Wistar rats were given a bilateral infusion of saline or RC-3095 (0.2, 1.0 or 5.0 microg) into the dorsal hippocampus either immediately or 2 h after training in an inhibitory avoidance (IA) task. Retention test trials were carried out 1.5 h (short-term memory) and 24 h (long-term memory) after training. RC-3095 impaired both short- and long-term retention only when given immediately after training. The results suggest that the hippocampal BN/GRP receptor system modulates IA memory formation.     

High potency of a new bombesin antagonist (RC-3095) in inhibiting serum gastrin levels; comparison of different routes of administration.

This study was performed to evaluate the efficacy and duration of action of a new bombesin antagonist D-Tpi6,Leu13 psi (CH2NH)Leu14-bombesin (6-14) (RC-3095), given by different routes of administration, in suppressing gastrin releasing-peptide (GRP(14-27))-stimulated gastrin release in rats. First, we showed that GRP(14-27) itself was highly active when administered by different routes. GRP(14-27), given to rats at a dose of 25 micrograms/100 g b.w. significantly increased serum gastrin levels 3 and 6 min after intravenous and for more than 30 min after subcutaneous administration or pulmonary inhalation. RC-3095 was then injected subcutaneously, intravenously and also delivered by pulmonary inhalation at a dose of 10 micrograms/100 g b.w. in each case to seven male rats 2, 30, 60 or 120 min prior to i.v. administration of 5 micrograms GRP(14-27). RC-3095 administered 2 min prior to GRP(14-27) decreased the gastrin response to GRP(14-27), measured as area under the curve, by 81% in the intravenously injected group and 64% in the pulmonary inhalation group in the first 6 min. When GRP(14-27), was given 30 min after administration of RC-3095, the gastrin response was decreased by 52% in the subcutaneous group, 49% in the pulmonary inhalation group and 11% in the intravenous group during the first 6 min. RC-3095 delivered subcutaneously or by pulmonary inhalation 1 h before GRP(14-27) was also able to significantly inhibit gastrin release. Analysis of the data revealed that the bioavailability of RC-3095 given by the pulmonary inhalation route was about 69% of the s.c. route.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced autophagy blocks angiogenesis via degradation of gastrin-releasing peptide in neuroblastoma cells

Neuroblastoma is characterized by florid vascularization leading to rapid tumor dissemination to distant organs; angiogenesis contributes to tumor progression and poor clinical outcomes. We have previously demonstrated an increased expression of gastrin-releasing peptide (GRP) and its receptor, GRPR, in neuroblastoma and that GRP activates the PI3K-AKT pathway as a proangiogenic factor during tumor progression. Interestingly, AKT activation phosphorylates MTOR, a critical negative regulator of autophagy, a cellular process involved in the degradation of key proteins. We hypothesize that inhibition of GRPR enhances autophagy-mediated degradation of GRP and subsequent inhibition of angiogenesis in neuroblastoma. Here, we demonstrated a novel phenomenon where targeting GRPR using shRNA or a specific antagonist, RC-3095, decreased GRP secretion by neuroblastoma cells and tubule formation by endothelial cells in vitro. Furthermore, shGRPR or RC-3095 treatment enhanced expression of proautophagic proteins in human neuroblastoma cell lines, BE(2)-C, and BE(2)-M17. Interestingly, rapamycin, an inhibitor of MTOR, enhanced the expression of the autophagosomal marker LC3-II and GRP was localized within LC3-II-marked autophagosomes in vitro as well as in vivo, indicating autophagy-mediated degradation of GRP. Moreover, overexpression of ATG5 or BECN1 attenuated GRP secretion and tubule formation, whereas opposite effects were observed with siRNA silencing of ATG5 and BECN1. Our data supported the role of autophagy in the degradation of GRP and subsequent inhibition of angiogenesis. Therefore, activation of autophagy may lead to novel antivascular therapeutic strategies in the treatment of highly vascular neuroblastomas.     

The bombesin/gastrin releasing peptide receptor antagonist RC-3095 blocks apomorphine but not MK-801-induced stereotypy in mice

Bombesin (BN)-like peptides might be involved in the pathogenesis of neuropsychiatric disorders such as schizophrenia. Stereotyped behaviors induced by the dopamine receptor agonist apomorphine or the N-methyl-D-aspartate glutamate receptor antagonist dizocilpine (MK-801) in rodents have been proposed as animal models of schizophrenic psychosis. In the present study we evaluated the effects of the BN/gastrin-releasing peptide receptor (GRP) antagonist (D-Tpi6, Leu13 psi[CH2NH]-Leu14) bombesin (6-14) (RC-3095) on apomorphine and MK-801-induced stereotyped behavior in mice. An intraperitoneal (i.p.) injection of RC-3095 (1.0, 10.0 or 100.0 mg/kg) blocked apomorphine-induced stereotypy. The inhibitory effect of RC-3095 on apomorhine-induced stereotypy was similar to that induced by haloperidol (0.5 mg/kg). RC-3095 did not affect stereotyped behavior induced by MK-801 (0.5 mg/kg). The results provide the first evidence that BN/GRP receptor antagonism blocks stereotyped behavior induced by a dopamine agonist. Together with previous evidence, the present study indicates that the BN/GRP receptor can be considered a drug target in the investigation of potential new agents for treating neuropsychiatric disorders.     

Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) Serves as a Carbon and Energy Source for a Mixed Culture Under Anaerobic Conditions

We studied the anaerobic biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a mineral medium by a mixed culture. RDX degradation activity was maintained for more than a year with only the addition of RDX. We observed a steady increase in the protein concentration of the culture from 4.8 μg mL⁻¹ to more than 24.4 μg mL⁻¹, a >400% increase. There was only a slight increase in protein in the RDX unamended control bottles containing live culture, increasing from 4.8 μg mL⁻¹ to 7.8 μg mL⁻¹. Radiolabeled ¹⁴C-RDX confirmed mineralization of the cyclic nitramine to ¹⁴CO₂. After 164 days, 35% of the radiolabel was recovered as ¹⁴CO₂. This is the first report demonstrating the mineralization of RDX when it serves as a growth substrate for a mixed culture.     

Autoradiographic Analysis of GABAA Receptors in μ-Opioid Receptor Knockout Mice

Anatomical evidence indicates that γ-aminobutyric acid (GABA)-ergic and opioidergic systems are closely linked and act on the same neurons. However, the regulatory mechanisms between GABAergic and opioidergic system have not been well characterized. In the present study, we investigated whether there are changes in GABA_A receptors in mice lacking μ-opioid receptor gene. The GABA_A receptor binding was carried out by autoradiography using [³H]-muscimol (GABA_A), [³H]-flunitrazepam (FNZ, native type 1 benzodiazepine) and [³⁵S]-t-butylbicyclophosphorothionate (TBPS, binding to GABA_A-gated chloride channels) in brain slices of wild type and μ-opioid receptor knockout mice. The binding of [³H]-FNZ in μ-opioid receptor knockout mice was significantly higher than that of the wild type controls in most of the cortex and hippocampal CA1 and CA2 formations. μ-Opioid receptor knockout mice show significantly lower binding of [³⁵S]-TBPS than that of the wild type mice in few of the cortical areas including ectorhinal cortex layers I, III, and V, but not in the hippocampus. There was no significant difference in binding of [³H]-muscimol between μ-opioid receptor knockout and wild type mice in the cortex and hippocampus. These data indicate that there are specific regional changes in GABA_A receptor binding sites in μ-opioid receptor knockout mice. These data also suggest that there are compensatory up-regulation of benzodiazepine binding site of GABA_A receptors in the cortex and hippocampus and down-regulation of GABA-gated chloride channel binding site of GABA_A receptors in the cortex of the μ-opioid receptor knockout mice.     

Effect of Abiotic Stress on Phosphate Solubilization by Biocontrol Fungus <Emphasis Type="Italic">Trichoderma</Emphasis> sp.

This study was undertaken to explore the role of Trichoderma sp. in phosphate (P) solubilization and antagonism against fungal phytopathogens. All fungal isolates (SE₆, KT₆, KT₂₈, and BRT₁₁) and a standard culture of T. harzianum (Th-std) were able to antagonize two fungal phytopathogens (Sclerotium rolfsii and Rhizoctonia solani) of chickpea (Cicer arietinum L.) wilt complex. Transmission electron microscopic studies (TEM) further confirmed ultra-cytological changes in the sclerotia of S. rolfsii parasitized by Trichoderma sp. All fungal cultures exhibited production of NH₃ and siderophore, but only BRT₁₁, SE₆, and Th-std could produce HCN. Among all the cultures tested, isolate KT₆ was found to be most effective for solubilization of ferric phosphate releasing 398.4 μg ml⁻¹ phosphate while isolates BRT₁₁ and SE₆ showed more potential for tricalcium phosphate (TCP) solubilization releasing 449.05 and 412.64 μg ml⁻¹ phosphate, respectively, in their culture filtrates. Part of this study focused on the influence of abiotic stress conditions such as pH, temperature, and heavy metal (cadmium) on phosphate (TCP) solubilizing efficiency. Two selected cultures KT₆ and T. harzianum retained their P solubilizing potential at varying concentrations of cadmium (0–1000 μg ml⁻¹). Isolate KT₆ and standard culture of T. harzianum released 278.4 and 287.6 μg ml⁻¹ phosphate, respectively, at 1000 μg ml⁻¹cadmium. Maximum solubilization of TCP was obtained at alkaline pH and at 28°C temperature. Isolate BRT₁₁ was found most alkalo-tolerant releasing 448.0 μg ml⁻¹ phosphate at pH 9.     

Content of the <Emphasis Type="Italic">Alternaria</Emphasis> mycotoxin tenuazonic acid in food commodities determined by a stable isotope dilution assay

The Alternaria mycotoxin tenuazonic acid (TA) was quantified in fruit juices (n = 50), cereals (n = 12) and spices (n = 38) using a recently developed stable isotope dilution assay (SIDA). [¹³ C₆,¹⁵ N]-TA was used as the internal standard. Method validation revealed low limits of detection (LODs) of 0.15 μg/kg (fruit juices), 1.0 μg/kg (cereals) and 17 μg/kg (spices). The respective limits of quantitation were about three times higher. Recovery was about 100% for all matrices. The precision (relative standard deviation of replicate analyses of naturally contaminated samples) was 4.2% (grape juice; 1.7 μg/kg), 3.5% (whole wheat flour; 36 μg/kg) and 0.9% (curry powder; 215 μg/kg). The median content of TA in the analyzed samples was 1.8 μg/kg (fruit juices), 16 μg/kg (cereals) and 500 μg/kg (spices). Positive samples amounted to 86% (fruit juices), 92% (cereals) and 87% (spices).     

Phytoremediation potential of <Emphasis Type="Italic">Amaranthus</Emphasis> hybrids: Antagonism between nickel and iron and chelating role of polyamines

Three amaranth hybrids (Amaranthus paniculatus f. cruentus (Vishnevyi dzhem), A. paniculatus (Bronzovyi vek), and A. caudatus f. iridis (Izumrud) were grown in the climate-controlled chamber on Jonson nutrient medium supplemented with 2 μM Fe³⁺-EDTA. When plants developed 5–6 true leaves (six-week-old plants), NiCl₂ was added to medium to final concentrations of 0 (control), 50, 100, 150, 200, and 250 μM. In 6 days, the increment in biomass of young and mature leaves, stems, and roots, and also the contents of Ni and Fe in them were measured. The red leaf amaranth hybrid Vishnevyi dzhem manifested the highest phytoremediation potential. i.e., the highest capacity for Ni accumulation in the shoots and the most pronounced symptoms of Fe deficit. In the presence of 150 and 250 μM NiCl₂ in medium, the shoots of these plants contained about 2 and 4 mg Ni/g dry wt, respectively. In experiments with Fe deficit in plants grown for a week in the presence of NiCl₂ (0, 25, 50, 75, and 100 μM), it was established that all tested nickel concentrations suppressed iron reduction in intact roots, which is catalyzed by ferric-chelate reductase, and this may underlie the antagonism between the two metals. In the presence of 50 μM NiCl₂ in medium and 2 μM Fe³⁺ (Fe deficit) and especially 100 μM Fe³⁺ (Fe excess), the content of MDA and proline in leaves increased and superoxide dismutase was activated; this indicates a development of oxidative stress. Leaf treatment with polyamines (putrescine or spermidine) with aminoguanidine (the inhibitor of H₂O₂ generation at polyamine oxidation) and with 1,3-diaminopropane led to the increase in nickel accumulation in leaves but did not result in the appearance of any signs of injury. This confirms our previous suggestion that polyamines manifest their protectory action as Ni chelators and detoxicants.     

Mercury contamination and life history traits of Allis shad <Emphasis Type="Italic">Alosa alosa</Emphasis> (Linnaeus, 1758) and Twaite shad <Emphasis Type="Italic">Alosa fallax</Emphasis> (Lacépède, 1803) in the Gironde estuary (South West France)

Mercury concentration [Hg] was assessed in 20 adult Allis shad Alosa alosa (54–59 cm) and 20 adult Twaite shad Alosa fallax (36–44 cm) collected during their spawning migration in the Dordogne and the Garonne rivers (France). [Hg] was measured in the gills, dorsal muscle, liver and kidney. Twaite shad exhibited higher [Hg] than Allis shad. Median [Hg] values were [Hg]_Gills = 0.33 μg g⁻¹ (dw), [Hg]_Muscle = 1.22 μg g⁻¹, [Hg]_Liver = 1.99 μg g⁻¹, [Hg]_Kidney = 1.93 μg g⁻¹ for Twaite shad and [Hg]_Gills = 0.06 μg g⁻¹, [Hg]_Muscle = 0.20 μg g⁻¹, [Hg]_Liver = 1.18 μg g⁻¹, [Hg]_Kidney = 1.08 μg g⁻¹ for Allis shad. In order to understand such differences, we investigated some life history traits of the two species: migratory history, age (3–6 years), size at age (an expression of growth) and the number of spawning events (0–2 events). The difference in estuarine residence time between the juveniles of both species, which was assumed to influence [Hg], was investigated using otolith Sr:Ca ratio. The microchemical analysis revealed a significant difference in the residence time of juveniles in the estuary (medians are 21 d and 10 d for Twaite shad and Allis shad, respectively) but this residence time seems too short to influence [Hg] (Allis shad: r _spearman < 0.128; Twaite shad: r _spearman < −0.340). As both species show the same age structure, the influence of age on [Hg] was negligible. The literature shows that the differences in growth and in the number of spawning events reported in our study are in favour of a higher [Hg] for Twaite shad than for Allis shad. Although trophic status was not investigated here, the literature reveals that it is another factor that could produce higher [Hg] in Twaite shad, since its diet includes higher trophic levels than Allis shad. Guest editors: S. Dufour, E. Prévost, E. Rochard & P. Williot Fish and diadromy in Europe (ecology, management, conservation)     

Extracellular Matrix in Early Stages of Direct Somatic Embryogenesis in Leaves of Drosera spathulata

The growth and water relations of Paulownia fortunei in photoautotrophic cultures (nutrient medium lacking sucrose and growth regulator) with CO₂ enrichment (PWAH) or without CO₂ enrichment (PWAL) were compared with those in photomixotrophic shoot (PWC; 30 g dm⁻³ sucrose and 0.3 mg dm⁻³ N⁶-benzyladenine) and root cultures (PWR; 0.3 mg dm⁻³ indole-3-butyric acid). The photoautotrophic and photomixotrophic cultures were incubated under photosynthetic photon flux 125 and 60 μmol m⁻² s⁻¹, respectively. 100 % sprouting and significantly higher number of shoots (1.6) were obtained with PWAH as compared to PWAL and PWC. PWAH and PWAL stimulated spontaneous rooting from the cut end of axillary shoots. In PWAH, 84 % of shoots rooted with an average of 5.9 roots per shoot and 4.0 cm of root length in 21 d. Rooting of photomixotrophic shoot cultures were stimulated by an auxin treatment. In this case, 98.3 % of shoots were rooted with an average of 4.6 roots per shoot and 1.9 cm length. A microscopic observation on leaf abaxial surface prints from photomixotrophic shoot and root cultures showed widely open (6 – 8 μm) spherical stomata (12 – 14 μm) and from photoautotrophic cultures elliptical stomata (10 – 12 μm) with narrow openings (3 – 4 μm). Leaves from photomixo-trophic cultures had higher stomatal index as compared to photoautotrophic cultures. The rate of moisture loss from detached leaves was not varying significantly in different cultures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Enhanced mineralization of pentachlorophenol by κ-carrageenan-encapsulated Pseudomonas sp. UG30

A pentachlorophenol(PCP)-degrading Pseudomonas sp. strain UG30 was encapsulated in κ-carrageenan for use in PCP degradation. Free and encapsulated cells were compared for their ability to dechlorinate and mineralize 100–800 μg/ml sodium pentachlorophenate in broth. Dechlorination was measured with a chloride ion electrode, and mineralization was measured by ¹⁴CO₂ evolution from radiolabelled [U-¹⁴C]PCP. Free and encapsulated Pseudomonas sp. UG30 cells mineralized up to 200 μg/ml and 600 μg/ml PCP, respectively, after 21 days. Encapsulation of UG30 cells provided a protective effect, allowing dechlorination and mineralization of high levels of PCP to occur. Received: 3 May 1996 / Received revision: 4 September 1996 / Accepted: 13 September 1996     

Monitoring of mycotoxin biomarkers in the Czech Republic

AFM₁ was determined in 72 (72%) samples of human urine, range 19-6064 pg/g creatinine, mean 367 pg/g creatinine, median 158 pg/g creatinine and 90% percentile 755 pg/g creatinine in 1997. AFM₁ was determined in 46 (43.8%) samples of human urine, range 21-19219 pg/g creatinine, mean 414 pg/g creatinine, median 96 pg/g creatinine and 90% percentile 415 pg/g creatinine in 1998. OTA was determined in 2077 (94.2%) samples of human serum, range 0.1–13.7 μg/L, mean 0.28 μg/L, median 0.2 μg/L and 90% percentile 0.5 μg/L in 1994–2002. OTA was determined in 12 (40%) samples of human kidneys, range 0.1–0.2 μg/kg, mean 0.07 μg/kg, and median 0.05 μg/kg in 2001. Presented at the 26^th Mykotoxin-Workshop in Herrsching, Germany, May 17–19, 2004.