Physiological role of germicidins in spore germination and hyphal elongation in Streptomyces coelicolor A3(2)

Four germicidin homologs were isolated from a liquid culture of Streptomyces coelicolor A3(2). These were identified as germicidins A, B and C, and surugapyrone A (germicidin D). Absolute stereochemistry of the chiral center in germicidins A and C is determined to be S. All germicidins inhibited germination of S. coelicolor A3(2) spores above 1?μg?ml(-1). S. coelicolor A3(2) spores collected from a single petri dish (9?cm i.d.) contained 5.4?μg of germicidin A (-2.7 × 10(-14) g per spore), which accounts for 2.3% of the spore extract, and contents of germicidins B, C and D were 0.2-0.8?μg. The activity of the spore extract corresponded well with the sum of the activity of each germicidin, which was estimated from the content and dose-response curve, which indicates that germicidins functions as self-germination inhibitors in S. coelicolor A3(2). Inhibitory action of germicidin A on spore germination was reversible and germicidin A inhibited not only spore germination but also hyphal elongation.     

Reversal of the inhibition of bacterial spore germination and outgrowth by antibacterial agents

The effects of some antibiotics and other antibacterial agents on the germination and outgrowth of Bacillus subtilis are described. The antibiotics tested (benzylpenicillin, cephalothin, chloramphenicol, minocycline, actinomycin D and mitomycin C) had no effect on germination but inhibited outgrowth to varying degrees. Of the preservative-type compounds, phenol and cresol acted predominantly at the germination stage, whereas the quaternary ammonium compound, benzalkonium chloride (BZK), and the organomercurial, phenylmercuric nitrate, inhibited out-growth but not germination. The inhibitory effect of phenol was reversed by membrane filtration, but not by 2% polysorbate 80, whereas BZK appeared to be tightly bound to the cells and could not be removed by filtration.     

Sensitivity of EEG in young rats to toluene exposure

Effects of toluene on the electroencephalogram (EEG) and its power spectra were measured during a 2-hr exposure in a dynamic inhalational chamber in young rats (30-53 days old) and compared to those in adult rats (63-77 days old). Rats were exposed to one of the three concentrations [low (108-111 ppm), medium (160-163 ppm), and high (407-432 ppm)] of toluene on different days. In tests on sleep-wake cycle, in the young animals the duration of the wake stage (W) was increased with decreases of rapid eye movement (REM) and non-REM (NREM) sleep during hr 1 and hr 2 of exposure to the low concentration. These effects were marked at the medium and the high concentrations. In adult rats, at the low concentration the increase of W and the decrease of REM were observed only at hr 1; however, at medium and high concentrations these changes of W and REM sleep were marked along with a decrease of NREM. Comparison of the changes of duration of different states in rats of two age groups showed that there was a significant difference in the increase of W and the decrease of NREM sleep in young rats at hr 2 of exposure to low concentrations only compared to those in adult rats. Tested on power spectrum in young rats during REM sleep recorded from the visual cortex, the power of delta waves increased at the medium and high concentrations and that of theta wave decreased at the high concentration during hr 2 of exposure compared to the controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sensitivity of brown trout reproduction to long-term estrogenic exposure

A decline in brown trout (Salmo trutta fario) catches has been reported in Switzerland, but at present the causative factors have not been clearly identified. Estrogen-active endocrine disrupters (EEDs) have been suggested as one possible explanation, since they are widespread in the aquatic environment and often found at elevated concentrations. In the present study the effects of long-term estrogenic exposure on the reproductive capability of brown trout were investigated. Adult fish were continuously exposed to an environmentally relevant mixture of the natural estrogens estrone (E1), 17beta-estradiol (E2) and the xenoestrogen 4-nonylphenol (NP); the average measured concentrations over the entire exposure time (n=9) were 14.0 ng/l (Min 8.1 and Max 20.6) for E1, 2.1 ng/l (Min 1.3 and Max 4.1) for E2 and 111.0 ng/l (Min 106.7 and Max 115.9) for NP. A solvent control served as negative control, and up to 10-fold higher mixture concentration than the environmentally relevant concentration served as positive control. The fish were exposed for 150 days from the onset of gonadal recrudescence until sexual maturation. Plasma vitellogenin (Vtg) was significantly induced by both concentrations of the estrogenic mixture, whereas effects on growth and fertility were only observed in fish exposed to the high mixture treatment. Fertilization success and offspring hatchability in brown trout exposed to the high mixture treatment were significantly reduced to 9% and 6%, respectively. Developmental time from fertilization until hatching, the percentage of larvae with malformations and survival of larvae, however, were not affected. The results suggest that a combination of estrogen-active compounds at environmentally relevant concentrations would not adversely affect those parameters of brown trout reproductive capability measured in this study. Plasma Vtg in male brown trout appeared to be more sensitive to (xeno)estrogen exposure than the measured reproductive effects.     

Quantitative structure-inhibitory activity relationships of phenols and fatty acids for Bacillus subtilis spore germination

Phenols and fatty acids were found to inhibit L-alanine-initiated germination of Bacillus subtilis spores without altering their heat resistance. Inhibitory effect was defined as the concentration necessary to cause 50% inhibition of the germination rate. The quantitative structure-inhibitory activity relationships for 39 phenols and 7 fatty acids were analyzed. The pH dependency of inhibition showed that the nonionized form of the molecule was responsible for inhibition. Hydrophobicity, which was expressed by the partition coefficient or the distribution coefficient of the compounds, was important for inhibition. In addition to hydrophobicity, the electronic effect, which was expressed by the dissociation constant, played a partial role in phenols. The correlation equation of the fatty acids was similar to those of the alcohols and other hydrophobic compounds, which had been reported earlier. That of the phenols, however, appeared to be different, indicating a different and more complex mechanism of inhibition. The type of inhibition by both compounds was mixed rather than competitive or noncompetitive.     

Regulation of gene expression in mouse germ cells upon exposure to tetrabutyltin

Tetrabutyltin is the starting material of the tributyltin and dibutyltin compounds. These tin compounds are starting materials for a wide range of organotin compounds used as stabilizers for PVC, biocides, fungicides, and anti-biofouling agents. It is commonly known that some of the environmental chemicals affect the human endocrine system. Since the 1970s, the harmful effects of endocrine disrupting chemical (EDC), Tetrabutyltin (TTBT) have been extensively studied. In the present study, we analyzed the effect of TTBT on gene regulation and expression of genes in mouse germ cells. Mouse germ cells were treated with TTBT for 3 and 24 hrs, and global gene expression was analyzed by using customized Agilent mouse arrays. We identified genes that were >2-fold differentially expressed in TTBT-treated cells than control cells (P<0.05) and analyzed their functions through Gene Ontology analysis. In a total number of 687 genes, there was differential expression between TTBT-treated and control cells. About 471 and 350 genes exhibited 2-fold (P<0.05) increased or decreased expression at 3 and 24 hrs, respectively. Additionally, in 134 genes, common and significant changes were observed in two-time series. Functional analysis of these genes showed that there were significant enrichments in some of the processes related to the reproduction such as, female gamete generation, homeostatic process, cell differentiation, response to chemical stress and reproductive process. In conclusion, the present study provides an insight on the effects of TTBT on mouse germ cells. Furthermore, it also increases our knowledge on the underlying molecular mechanisms on the adverse effects of organotin on the reproductive system.     

Sensitivity of the young infant to drug exposure through human milk

In spite of significant exposure to drugs and chemicals through breast milk, there are very few reports of documented adverse effects on the infant. It is perhaps appropriate to consider that the presence of drugs and chemicals in milk may have a positive effect on developmental processes of the young infant. New experimental techniques coupled with increasing sensitive assays for chemical moieties present opportunities for measuring the effect of such chemicals on development processes in the neonate and young infant.     

Chronic exposure to acrylamide induces DNA damage in male germ cells of mice

Acrylamide is a reproductive toxicant that has been detected in foods such as potato chips and breads. The consequences of chronic exposure to acrylamide in the human diet are unknown; however, rodent experiments have shown that acute acrylamide exposure in males can lead to decreased fertility and dominant lethality. One of the possible mechanisms by which acrylamide elicits these effects is thought to be related to its metabolic conversion to glycidamide, which can form DNA adducts. To determine whether chronic acrylamide exposure produces genetic damage in male germ cells in vivo, male mice were subjected to acrylamide through their drinking water. Acrylamide was administered at 0.001, 0.01, 0.1, 1, and 10 μg/ml for up to 1 year, which was equivalent to 0.0001-2mg/kg bodyweight/day. At 1, 3, 6, 9, and 12 months, early male germ cells were assessed for DNA damage using a Comet assay modified to detect adducts and γH2A.X expression, a marker of double-strand breaks. Acrylamide treatment did not significantly affect mouse or testis weight, and no gross morphological effects were observed in the testis. However, a significant dose-dependent increase in DNA damage was observed in germ cells following 6 months of exposure in the two highest dosage groups (1 and 10 μg/ml). After 12 months of exposure, increases in damage were detected at doses as low as 0.01 μg/ml (0.001mg/kg bodyweight/day). The results of this study are the first to demonstrate that chronic exposure to acrylamide, at doses equivalent to human exposures, generates DNA damage in male germ cells of mice.     

Perinatal exposure to Bisphenol A disturbs the early differentiation of male germ cells

Understanding the effects of Bisphenol A (BPA) on early germ cell differentiation and their consequences in adult life is an area of growing interest in the field of endocrine disruption. Herein, we investigate whether perinatal exposure to BPA affects the differentiation of male germ cells in early life using a transgenic mouse expressing the GFP reporter protein under the Oct4 promoter. In this model, the expression of GFP reflects the expression of the Oct4 gene. This pluripotency gene is required to maintain the spermatogonial stem cells in an undifferentiated stage. Thus, GFP expression was used as a parameter to evaluate the effect of BPA on early germ cell development. Female pregnant transgenic mice were exposed to BPA by oral gavage, from embryonic day 5.5 to postnatal day 7 (PND7). The effects of BPA on male germ cell differentiation were evaluated at PND7, while sperm quality, testicular morphology, and protein expression of androgen receptor and proliferating cell nuclear antigen were studied at PND130.We found that perinatal/lactational exposure to BPA up-regulates the expression of Oct4-driven GFP in testicular cells at PND7. This finding suggests a higher proportion of undifferentiated spermatogonia in BPA-treated animals compared with non-exposed mice. Moreover, in adulthood, the number of spermatozoa per epididymis was reduced in those animals perinatally exposed to BPA.This work shows that developmental exposure to BPA disturbed the normal differentiation of male germ cells early in life, mainly by altering the expression of Oct4 and exerted long-lasting sequelae at the adult stage, affecting sperm count and testis.     

孕期暴露重金属对妊娠结局的影响

近年来,环境污染日益严峻,严重影响的人类的健康和生存,其中重金属元素对环境的污染和破坏尤为严重,特别是铅(Pb)、镉(Cd)、汞(Hg)、铜(Cu)、锰(Mn)及其复合的污染最为突出.重金属是一类毒性很大的无机污染物.大量资料显示,孕妇长期暴露某一种或几种重金属可能会引起婴儿严重的出生缺陷、低出生体重、生长发育迟缓、死胎、智力发育障碍等.     

Anti-inflammatory activity of edible brown alga Saccharina japonica and its constituents pheophorbide a and pheophytin a in LPS-stimulated RAW 264.7 macrophage cells

Anti-inflammatory activity of Saccharina japonica and its active components was evaluated via in vitro inhibitory activities against lipopolysaccharide (LPS)-induced nitric oxide (NO) production, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) expression in RAW 264.7 murine macrophage cells. Since the methanolic extract of S. japonica showed strong anti-inflammatory activity, it was fractionated with several solvents. Among the fractions, the ethyl acetate fraction demonstrated the highest inhibition of LPS-induced NO production (IC₅₀ = 25.32 μg/mL), followed by the CH₂Cl₂ fraction (IC₅₀ = 75.86 μg/mL). Considering the yield and anti-inflammatory potential together, the CH₂Cl₂ fraction was selected for chromatographic separation to yield two active porphyrin derivatives, pheophorbide a and pheophytin a, together with an inactive fucoxanthin. In contrast to fucoxanthin, pheophorbide a and pheophytin a showed dose-dependent inhibition against LPS-induced NO production at nontoxic concentrations in RAW 264.7 cells. Both compounds also suppressed the expression of iNOS proteins, while they did not inhibit the COX-2 expression in LPS-stimulated macrophages. These results indicate that pheophorbide a and pheophytin a are two important candidates of S. japonica as anti-inflammatory agents which can inhibit the production of NO via inhibition of iNOS protein expression. Thus, these compounds hold great promise for use in the treatment of various inflammatory diseases.     

Acute respiratory fatality associated with exposure to sheet metal and cadmium fumes

The authors report on a case of an acute fatality characterized by abdominal pain and respiratory failure occurring soon after beginning to weld and solder galvanized sheet metal. Heating of galvanized sheet metal is a recognized cause of metal fume fever, data from this patient suggests an additional and unrecognized risk for cadmium poisoning.     

Head and neck cancer due to heavy metal exposure via tobacco smoking and professional exposure: A review

Chronic exposures to heavy metals via tobacco smoking and professional exposure may increase the risk of head and neck cancer, although the epidemiologic evidence is limited by problems of low study power and inadequate adjustment for tobacco and professional exposure use. Numerous scientific reviews have examined the association of various heavy metals exposure with respiratory cancer as well as other cancer types, but few have been published on head and neck cancer. The purpose of this paper, therefore, is to review the head and neck tract cancer-related data on exposure to heavy metals via smoking and working exposure and to study the major mechanisms underlying some toxic metals carcinogenesis.     

Sensitivity of the spiny dogfish (Squalus acanthias) to waterborne silver exposure

The physiological effects of waterborne silver exposure (added as AgNO(3)) on spiny dogfish, Squalus acanthias, were evaluated at 30, 200 and 685 microg silver per l in 30 per thousand seawater. These concentrations cover the toxic range observed for freshwater teleosts, where silver is extremely toxic, to seawater teleosts which tolerate higher silver concentrations. However, these levels are considerably higher than those that occur in the normal environment. At 685 microg l(-1), dogfish died within 24 h. Causes of death were respiratory as well as osmoregulatory failure. Arterial P(a)O(2) rapidly declined below 20 Torr, and blood acidosis (both respiratory and metabolic) occurred. Urea excretion increased dramatically and plasma urea dropped from 340 to 225 mM. There were pronounced increases in plasma Na(+), Cl(-), and Mg(2+), indicative of ionoregulatory failure due to increased diffusive permeability as well as inhibited NaCl excretion. At 200 microg l(-1), fish died between 24 and 72 h of silver exposure. The same physiological events occurred with a small time delay. At 30 microg l(-1), effects were much less severe, although slight mortality (12.5%) still occurred. Respiratory alkalosis occurred, together with moderate elevations in plasma Na(+) and Cl(-) levels. Silver accumulated to the highest concentrations on gills, with only low levels in the intestine, in accord with the virtual absence of drinking. Na(+)/K(+)-ATP-ase activities of gill and rectal gland tissue were impaired at the highest silver concentration. Normal gill function was impaired due to swelling and fusion of lamellae, lamellar aneurism and lifting of the lamellar epithelium. Our results clearly indicate that this elasmobranch is much more sensitive (about 10-fold) to silver than marine teleosts, with silver's toxic action exerted on the gill rather than on the intestine, in contrast to the latter.     

Antagonistic effects of gestational dietary exposure to low-dose vinclozolin and genistein on rat fetal germ cell development

Continuous, low-dose exposure to a phytoestrogen (1 mg/kg/day genistein) and/or to an antiandrogenic food contaminant (1 mg/kg/day vinclozolin) has been recently reported to affect male reproductive tract and fertility [1] in adults. We investigated whether alterations of the testis are already present at the end of in utero exposure using the same rat model and doses following exposure from conception to delivery. After vinclozolin exposure, we observed in the neonate a slight but significant alteration of steroidogenesis and gametogenesis with a reduction of testosterone secretion and of the number of gonocytes. In contrast, genistein exposure had no effect. While the vinclozolin-genistein mixture acts in a synergistic manner to induce the most significant alterations in the adult, interestingly, genistein antagonized the deleterious effect of vinclozolin on germ cells in the neonate. This difference emphasizes the importance of studying the effects of endocrine disruptors during various developmental stages to understand their effects.     

Comparison of metal toxicity bioassays based on inhibition of sporulation and spore release inUlva pertusa

The present investigation involves the use of green marine macroalgae,U. pertusa, as a tool for bioassay of heavy metals (silver, arsenic, cadmium, cobalt, chromium, copper, iron, mercury, manganese, nickel, lead and zinc) prevalent in most industrial wastewaters. This is the first report of its kind wherein both, sporulation as well as spore release, is investigated synchronously. The EC₁₀ and EC₅₀ values obtained were also compared with toxicity norms of waste water quality criteria in Korea and global permissible limits. Based on variability it could be stated that the sporulation test was more reliable than the spore release test. The cosmopolitan presence ofUlva spp. makes the applicability of both these tests prominent as effective diagnostic tools for detecting pollution in metal polluted waters.     

Pulmonary toxicity after exposure to military-relevant heavy metal tungsten alloy particles

Significant controversy over the environmental and public health impact of depleted uranium use in the Gulf War and the war in the Balkans has prompted the investigation and use of other materials including heavy metal tungsten alloys (HMTAs) as nontoxic alternatives. Interest in the health effects of HMTAs has peaked since the recent discovery that rats intramuscularly implanted with pellets containing 91.1% tungsten/6% nickel/2.9% cobalt rapidly developed aggressive metastatic tumors at the implantation site. Very little is known, however, regarding the cellular and molecular mechanisms associated with the effects of inhalation exposure to HMTAs despite the recognized risk of this route of exposure to military personnel. In the current study military-relevant metal powder mixtures consisting of 92% tungsten/5% nickel/3% cobalt (WNiCo) and 92% tungsten/5% nickel/3% iron (WNiFe), pure metals, or vehicle (saline) were instilled intratracheally in rats. Pulmonary toxicity was assessed by cytologic analysis, lactate dehydrogenase activity, albumin content, and inflammatory cytokine levels in bronchoalveolar lavage fluid 24 h after instillation. The expression of 84 stress and toxicity-related genes was profiled in lung tissue and bronchoalveolar lavage cells using real-time quantitative PCR arrays, and in vitro assays were performed to measure the oxidative burst response and phagocytosis by lung macrophages. Results from this study determined that exposure to WNiCo and WNiFe induces pulmonary inflammation and altered expression of genes associated with oxidative and metabolic stress and toxicity. Inhalation exposure to both HMTAs likely causes lung injury by inducing macrophage activation, neutrophilia, and the generation of toxic oxygen radicals.     

Sensitivity of fetal rat testicular steroidogenesis to maternal prochloraz exposure and the underlying mechanism of inhibition.

The fungicide prochloraz (PCZ) induces malformations in androgen-dependent tissues in male rats when administered during sex differentiation. The sensitivity of fetal testicular steroidogenesis to PCZ was investigated to test the hypothesis that the reported morphological effects from maternal exposure were associated with reduced testosterone synthesis. Pregnant Sprague-Dawley rats were dosed by gavage with 0, 7.8, 15.6, 31.3, 62.5, and 125 mg PCZ/kg/day (n = 8) from gestational day (GD) 14 to 18. On GD 18, the effects of PCZ on fetal steroidogenesis were assessed by measuring hormone production from ex vivo fetal testes after a 3-h incubation. Lastly, PCZ levels in amniotic fluid and maternal serum were measured using liquid chromatography/mass spectroscopy and correlated to the inhibition of steroidogenesis. Fetal progesterone and 17alpha-hydroxyprogesterone production levels were increased significantly at every PCZ dose, whereas testosterone levels were significantly decreased only at the two high doses. These results suggest that PCZ inhibits the conversion of progesterone to testosterone through the inhibition of CYP17. To test this hypothesis, PCZ effects on CYP17 gene expression and in vitro CYP17 hydroxylase activity were evaluated. PCZ had no effect on testicular CYP17 mRNA levels as measured by quantitative real-time polymersase chain reaction. However, microsomal CYP17 hydroxylase activity was significantly inhibited by the fungicide (K(i) = 865nM). Amniotic fluid PCZ concentrations ranged from 78 to 1512 ppb (207-4014nM) and testosterone production was reduced when PCZ reached approximately 500 ppb, which compares favorably with the determined CYP17 hydroxylase K(i) (326 ppb). These results demonstrate that PCZ lowers testicular testosterone synthesis by inhibiting CYP17 activity which likely contributes to the induced malformations in androgen-dependent tissues of male offspring.