O-286 Bisphenol A in blood serum and follicular fluid of women undergoing to cycle of IVF living in areas with different environmental impact. (EcoFoodFertility Project)

Study question

Bisphenol A (BPA) is a constituent of polycarbonate and epoxy resin plastics and is also a by-product of combustion of plastics, resulting harmful for health.

Summary answer

To evaluate the presence of BPA in the blood and Follicular Fluids, in women, subjected to IVF cycles, living in areas with different environmental impact.

What is known already

BPA is used in the production of polycarbonate plastics and epoxy resins. 1,3,5-triphenylbenzene is a tracer for burning plastic and has been related to levels of bisphenol A in the air, so the actual release of bisphenol A to the atmosphere could result from burning the plastic. Bisphenol A belongs to the group of endocrine disruptors.

Little is known about the effects of BPA on human female reproduction. BPA levels appear to be inversely related to the number of oocytes retrieved in IVF cycles, and it also appears to negatively affect the ovulatory peak of estradiol.

Study design, size, duration

In the frame of EcoFoodFertility project a cross sectional study conducted in Campania Region (Southern Italy), between January 2019 and December 2020, 74 women, no smokers, no chronic diseases, not exposed to occupational risk factors. living for at least 5 years in areas with low environmental impact (LEI, 31 women), Alto-Medio Sele in province of Salerno and high environmental impact (HEI, 43 women), so-called “Land of Fires” in province of Naples, were selected.

Participants/materials, setting, methods

Participants have a normal ovarian reserve, average age 32.05 + 3.49, with infertility duration between 26 and 39 months and at the first experience of an IVF cycle. ELISA was used for measuring bisphenol A in blood and Follicular Fluids (FFs), expressed in ng/ mL. 5 mL glass tubes, without additives, not siliconized and kept in a horizontal position were used. FFs were bloodless with a negative albumin test.

Main results and the role of chance

Differents levels of BPA were found in all processed samples.

In the LEI (Low Environmental Impact) group, serum levels vary from a minimum of 3.1 ng/mL to a maximum of 7.7 ng/mL (4.1 ± 1.6) and the Follicular Fluids levels vary from a minimum of 7,1 ng/mL to a maximum of 55.3 ng/mL (13.8 ± 10.9).

In the HEI (High Environmental Impact) group, serum levels vary from a minimum of 69.2 ng/mL to a maximum of 167.8 ng/mL (95.5 ± 24.3) and Follicular Fluids levels vary from a minimum of 4.2 ng/mL to a maximum of 34.3 ng/mL (19.9 ± 9.2).

Statistical processing of the data shows a highly significant variation in serum levels (p < 0.0001) with higher values in the HEI group (95.5 ± 24.3) than in the LEI group (4.1 ± 1.6).

A moderately significant change (p < 0.01) for Follicular Fluids levels, higher in the HEI group (19.9 ± 9.2) than in the LEI group (13.8 ± 10.9).

Furthermore, the data did not show any correspondence between serum and Follicular Fluids for any of the participants tested.

Limitations, reasons for caution

The ELISA method for the determination of BPA seems suitable to us, however, the subject requires further biomonitoring studies, with a larger sample and greater selection of participants, to better understand the effects of BPA and its metabolites in FF and in other districts of the female reproductive system.

Wider implications of the findings

The results indicate that the greater bioaccumulation in women of the HEI group appears consistent with the environmental condition of the area and with the comparative studies already carried out within the EcoFoodFertility project. This is further evidence that pollution in this area can interfere with female fertility and beyond.

Trial registration number

G003

Wastewater toxicity of tannin- versus chromium-based leather tanneries in Marrakesh, Morocco

The toxicity of leather tanning wastewater from a traditional tannery (TT), which is based on vegetable tannin (VT), was compared with wastewater from a tannery combining the use of chromium-based tanning (CT) with VT-based tanning operations. Wastewater samples from a TT and a CT plant as well as from five sewer sampling points were collected in Marrakesh, Morocco, and the concentrations of VT and some selected inorganics were measured. A set of bioassays were used to test wastewater toxicity in sea urchin (Paracentrotus lividus) embryos and sperm, in Daphnia magna, and in marine microalgae (Dunaliella tertiolecta). Toxicity end points included: (1) developmental defects, embryonic mortality, sperm fertilization success, and offspring damage in sea urchins; (2) D. magna immobilization; and (3) algal growth rate inhibition. Toxicity tests on TT and CT effluents (TTE and CTE) were run at dilutions ranging from 0.1% to 2% (sea urchins and algae) or up to 12% in D. magna. Parallel bioassays were run on VT extract (VTE) at nominal tannin concentrations ranging from 0.1 to 10 mg l(-1). The results showed higher toxicity of CTE compared with TTE. CTE toxicity in sea urchins and algae showed concentration-related trends, whereas TTE exerted hormetic effects at levels of 0.1% to 0.2% and toxic effects at levels >or=1%. The same trends were observed for VTE, suggesting a prevailing role of tannin in TTE-associated effects. The moderate wastewater toxicity of VT-based tanneries might prompt interest in the VT tanning process.

Permeability of human oocytes to ethylene glycol and their survival and spindle configurations after slow cooling cryopreservation

BACKGROUND

To develop novel cryopreservation methods, we estimated the permeability coefficients Lp (hydraulic conductivity) and P(EG) (cryoprotectant permeability) of mature human oocytes after exposure to ethylene glycol (EG) and tested the efficiency of a multi-step slow cooling protocol based on this cryoprotectant.

METHODS

Oocytes were perfused with 1.5 mol/l EG for 10 min. Oocyte volume at each time point was calculated and normalized to the original volume. Slow cooling was conducted by exposing oocytes to increasing EG concentrations (0.5, 1.0 and 1.5 mol/l n = 155) or 1.5 mol/l of propane-1,2-diol (PrOH) n = 102. Oocytes which survived cryopreservation n = 80 and fresh oocytes n = 73 were prepared for confocal microscopy analysis of the meiotic spindle.

RESULTS

During EG exposure, oocytes underwent an abrupt 50% volume reduction. Complete recovery of the initial volume was not observed. From the values of a best fit plot, the coefficients Lp = 0.82 +/- 0.29 microm min(-1) atm(-1) (mean +/- SD) and P(EG) 0.10 +/- 0.01 microm s(-1) were generated. Survival rates after freezing with EG were lower than with PrOH (51.6 versus 71.5%, respectively, P < 0.05). The frequencies of normal spindle configuration were lower in frozen EG and frozen PrOH oocytes compared with fresh oocytes (53.8, 50.9 and 66.7%, respectively, P < 0.05).

CONCLUSIONS

The oocyte plasmalemma possesses limited permeability to EG and EG exposure causes considerable osmotic stress. However, post-thaw rates of survival and normal meiotic spindle organization may be preserved by protocols which are designed in order to minimize osmotic stress.

Hormetic versus toxic effects of vegetable tannin in a multitest study

Tannin from mimosa trees (Acacia sp.) utilized in traditional leather tanning was tested for toxicity in sea urchin (Sphaerechinus granularis and Paracentrotus lividus) embryos and sperm, marine, and freshwater algae (Selenastrum capricornutum and Dunaliella tertiolecta), and Daphnia magna. Based on a two-step tanning procedure used in traditional tanneries, two mimosa tannin preparations, i.e., fresh tannin (FT) and used tannin (UT), were tested as suspensions. The early results in S. granularis embryos showed that UT exerted lower acute toxicity than FT, namely, 1 vs 100 mg/L, to obtain 100% mortality, respectively. Subsequent bioassays were conducted on fresh tannin water extracts (TWE) corresponding to nominal tannin concentrations ranging from 0.1 to 30 mg/L. Developmental toxicity, up to embryonic mortality was exerted by TWE at levels > 1 mg/L, S. granularis being more sensitive than P. lividus embryos/larvae. At the concentration of 0.1 mg/L, the frequencies of larval malformations were significantly lower than in controls. This positive stimulatory effect (currently termed as hormesis) was observed in extended numbers of culture replicates (up to 14) and was significant in the embryo cultures characterized by a relatively poor control quality (with < 70% viable larvae in controls), whereas this effect was not observed in good-quality cultures (with > or = 70% viable larvae in controls). Cytogenetic analysis of S. granularis embryos reared in FT or UT suspensions (1 mg/L to 1 g/L) showed mitotoxic effects (decrease in active mitoses per embryo) in FT-exposed, but not in UT-exposed embryos. Mitotic aberrations were significantly increased by 10 mg/L UT. Sperm fertilization success in both sea urchin species showed an increasing fertilization rate (FR) up to 0.3 mg/L TWE and a dose-related decrease in FR up to 30 mg/L. Again, the offspring of P. lividus sperm exposed to TWE (0.1 and 0.3 mg/L) showed a decrease in larval malformations compared to controls, whereas a dose-related increase in developmental defects was observed in the offspring of P. lividus sperm exposed to higher TWE levels (1 to 30 mg/L). Algal cell growth bioassays in two species (S. capricornutum and D. tertiolecta) also showed a maximum growth at TWE levels ranging from 0.3 to 3 mg/L and a subsequent decline up to 30 mg/L TWE. D. magna bioassays resulted in daphnid immobilization by TWE concentrations ranging from 100 to 300 mg/L. The results demonstrate that tannins utilized in traditional leather tanning industry may raise concern of environmental damage at relatively high concentrations, whereas low-level tannins may result in hormetic effects. The present study also points to the need for bioassay design that should rely on adequate criteria in control quality, allowing to detect both inhibitory and hormetic effects.

Emerging diseases: a global threat

A growing and globalizing threat of emerging and re-emerging diseases is best addressed through reliance on rapid detection, diagnosis, and containment. The efficiency and success of this approach depends on intricate networking and collaboration among all stakeholders including intergovernmental and nongovernmental organizations and specialized agencies in the developed and developing countries. Such cooperation, while focusing on eliminating a growing threat, also helps avoid duplication of effort and improves use of scarce financial resources. This review provides a summary of the problem of emerging/re-emerging diseases and the effort being directed at controlling the threat. Opportunities are identified for a more coordinated approach to addressing the problem.

Diepoxybutane and mitomycin C toxicity is associated with the induction of oxidative DNA damage in sea urchin embryos

Diepoxybutane (DEB)- and mitomycin C (MMC)-associated toxicity was investigated in embryos from the sea urchin (SU) species Sphaerechinus granularis. DEB- and MMC-induced toxicity resulted in S. granularis embryos and larvae at concentrations ranging 10(-5) to 10(-4) M DEB, and 3 x 10(-6) to 3 x 10(-5) M MMC, in terms of larval malformations, developmental arrest and mortality. The formation of DNA oxidative damage, 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured in DEB- and in MMC-exposed embryos (at gastrula stage). A dose-dependent increase in 8-OHdG levels was observed that was significantly correlated with DEB- and MMC-induced developmental defects. The results lend further support to the body of evidence associating both DEB and MMC toxicity with oxidative stress, including DNA oxidative damage.

Factors affecting R6 fungicide toxicity on sea urchin fertilization and early development: roles of exposure routes and mixture components

A technical fungicide mixture, R6 and its components, cymoxanil (CYM) and cupric oxychloride (Cu-OCl), were tested by sea urchin bioassays (Paracentrotus lividus and Sphaerechinus granularis). A set of toxicity endpoints was evaluated including both lethal and sublethal effects with the following endpoints: (a) acute embryotoxicity, (b) developmental defects, (c) changes in sperm fertilization success, (d) transmissible damage from sperm to the offspring, and (e) cytogenetic abnormalities. Acute effects on developing embryos were observed as early (prehatch) mortality at R6 levels > or =25 microg/ml. The pesticide mixture R6 was tested at realistic concentrations, ranging from 25 ng/ ml to 2.5 microg/ml, and the two components, CYM and Cu-OCl, were tested, either alone or in mixture, at concentrations equal to their levels in the corresponding R6 solutions. R6 was either dissolved in filtered seawater (water only, W-O), or spiked in "pristine" silt-clay sediment or soil samples before bioassays. Developmental toxicity of R6, following W-O dissolution, displayed a significant dose-related increase of larval malformations and differentiation arrest at concentrations of 750 ng/ml to 2.5 microg/ml both in P. lividus and in S. granularis larvae. Developmental toxicity was removed in spiked sediment up to R6 nominal levels (25 microg/ml), 10-fold above the embryotoxic R6 levels in W-O exposure. No significant developmental toxicity was exerted by CYM or Cu-OCl (W-O exposure) up to their concentrations equivalent to 2.5 microg/ml R6. The laboratory-prepared mixture of CYM and Cu-OCl, in the same concentration range, only resulted in minor effects, as larval retardation, suggesting the presence of toxic impurities (or additional components) in the R6 formulation. When sperm from either P. lividus or S. granularis were exposed to R6 before fertilization, a W-O exposure resulted in a dose-related decrease in fertilization of P. lividus sperm (up to 250 microg/ml R6), whereas S. granularis sperm underwent a significant increase of fertilization rate at the highest R6 nominal levels (up to 25 microg/ml). Equivalent CYM or Cu-OCl levels were ineffective on sperm fertilization success in both species. The offspring of S. granularis sperm exposed to 25 microg/ml R6 showed a significant increase in larval malformations, which were not detected in the offspring of R6-exposed P. lividus sperm. Again, CYM or Cu-OCl was unable to exert any transmissible damage from sperm to the offspring in either species. The present study raises the case of possible discrepancies between toxicity of a technical mixture and of its analytical-grade components, also providing evidence for a loss of pesticide toxicity following dispersion in an environmental matrix such as sediment or soil.

The Rhizobium GstI protein reduces the NH4+ assimilation capacity of Rhizobium leguminosarum

We show that the protein encoded by the glutamine synthetase translational inhibitor (gstI) gene reduces the NH4+ assimilation capacity of Rhizobium leguminosarum. In this organism, gstI expression is regulated by the ntr system, including the PII protein, as a function of the nitrogen (N) status of the cells. The GstI protein, when expressed from an inducible promoter, inhibits glutamine synthetase II (glnII) expression under all N conditions tested. The induction of gstI affects the growth of a glutamine synthetase I (glnA-) strain and a single amino acid substitution (W48D) results in the complete loss of GstI function. During symbiosis, gstI is expressed in young differentiating symbiosomes (SBs) but not in differentiated N2-fixing SBs. In young SBs, the PII protein modulates the transcription of NtrC-regulated genes such as gstI and glnII. The evidence presented herein strengthens the idea that the endocytosis of bacteria inside the cytoplasm of the host cells is a key step in the regulation of NH4+ metabolism.

The role of oxidative stress in developmental and reproductive toxicity of tamoxifen

The antiestrogen tamoxifen (TAM) is widely used as a drug against breast cancer and is currently being tested as a chemopreventive agent. However, a number of studies showed genotoxic and carcinogenic effects of TAM. These effects are thought to be related to oxygen radical overproduction which occurs during TAM metabolic activation. There is no evidence, thus far, on TAM toxicity to embryos and gametes. The present study was designed to elucidate the mechanisms of TAM-induced developmental, reproductive and cytogenetic toxicity towards sea urchin (SU) embryos with regard to the possibility of TAM-initiated oxidative stress. Embryo cultures from SU were subjected to long-term (throughout embryogenesis) or short-term (two hours) incubation with TAM at concentrations from 10(-8) to 10(-5) M. The experiments on TAM-induced toxicity to gametes were carried out with SU sperm, or unfertilized eggs, suspended in TAM (10(-8) to 10(-6) M). To assess the effects of TAM to embryos or to gametes, developmental defects, embryonic mortality, fertilization success, and cytogenetic abnormalities were scored. Oxidative damage to DNA and lipids was detected by measurements of 8OHdG levels and lipid peroxidation, respectively. Reactive oxygen species (ROS) production by eggs and embryos was recorded by luminol-dependent chemiluminescence (LDCL) and cytochrome c reduction methods. The changes in activities of SU superoxide dismutase (SOD) and catalase were also evaluated. TAM exerted: a) early embryonic mortality to exposed embryos and to the offspring of exposed eggs; b) developmental defects to the offspring of exposed sperm; c) decrease in sperm fertilization success, and d) cytogenetic effects in the offspring of exposed sperm or eggs. These morphological effects corresponded to the state of oxidative stress in SU embryos (increased oxidative damage to DNA and lipids and induction of antioxidant enzymes). Since TAM did increase significantly ROS production by embryos, it is suggested that TAM may be metabolically activated by SU embryonic oxidases and peroxidases, which in turn could be induced by TAM. The present study provides further support to the utilization of the SU system as a useful model to help elucidate mechanisms of chemical teratogenesis and carcinogenesis.

Inhibition of glutamine synthetase II expression by the product of the gstI gene

We report the identification of a previously unrecognized gene that is involved in the regulation of the Rhizobium leguminosarum glnII (glutamine synthetase II) gene. This gene, which is situated immediately upstream of glnII, was identified by means of a deletion/complementation analysis performed in the heterologous background of Klebsiella pneumoniae. It has been designated gstI (glutamine synthetase translational Inhibitor) because, when a complete version of gstI is present, it is possible to detect glnII-specific mRNA, but neither GSII activity nor GSII protein. The gstI gene encodes a small (63 amino acids) protein, which acts in cis or in trans with respect to glnII and is transcribed divergently with respect to glnII from a promoter that was found to be strongly repressed by the nitrogen transcriptional regulator NtrC. A mutated version of GstI lacking the last 14 amino acids completely lost its capacity to repress glnII expression. Our results indicate that gstI mediates the translation inhibition of glnII mRNA and, based on in silico analyses, a mechanism for GstI action is proposed.

Redox-dependent toxicity of diepoxybutane and mitomycin C in sea urchin embryogenesis

The effects and mechanisms of action of diepoxybutane (DEB) and mitomycin C (MMC) were investigated on sea urchin embryogenesis, (Sphaerechinus granularis and Paracentrotus lividus). DEB- and MMC-induced toxicity was evaluated by means of selected end-points, including developmental defects, cytogenetic abnormalities and alterations in the redox status [oxygen-dependent toxicity, Mn-superoxide dismutase (MnSOD) and catalase activities and glutathione (GSH) levels]. Both DEB and MMC exhibited developmental toxicity (at concentrations ranging from 3 x 10(-5) to 3 x 10(-4) M and 3 x 10(-6) to 3 x 10(-5) M, respectively) expressed as larval abnormalities, developmental arrest and mortality. The developmental effects of both compounds were significantly affected by oxygen at levels ranging from 5 to 40%. These results confirmed previous evidence for oxygen-dependent MMC toxicity and are the first report of oxygen dependence for DEB toxicity. Both DEB and MMC exerted significant cytogenetic abnormalities, including mitotoxicity and mitotic aberrations, but with different trends between the two chemicals, at the same concentrations as exerted developmental toxicity. The formation of reactive oxygen species was evaluated using: (i) luminol-dependent chemiluminescence (LDCL); (ii) reactions of the main antioxidant systems, such as GSH content and MnSOD and catalase activities. The results point to clear-cut differences in the effects induced by DEB and MMC. Thus, DEB suppressed GSH content within the concentration range 10(-7)-3 x 10(-5) M. The activity of catalase was stimulated at lower DEB levels (10(-7)-10(-6) M) and then decreased at higher DEB concentrations (> or =10(-5) M). Increasing MMC concentrations induced LDCL and MnSOD activity (> or =10(-6) M) greatly and modulated catalase activity (10(-7) - 10(-6) M). GSH levels were unaffected by MMC. The results suggest that oxidative stress contributes to the developmental and genotoxic effects of both toxins studied, although through different mechanisms.

The Rhizobium etli metZ gene is essential for methionine biosynthesis and nodulation of Phaseolus vulgaris

A mutant strain (CTNUX23) of Rhizobium etli carrying Tn5 unable to grow with sulfate as the sole sulfur source was isolated and characterized. Sequence analysis showed that Tn5 is inserted into a metZ (O-succinylhomoserine sulfhydrylase)-homologous gene. The CTNUX23 mutant strain had a growth dependency for methionine, although cystathionine or homocysteine, but not homoserine or O-succinylhomoserine, allowed growth of the mutant. RNase protection assays showed that the metZ-like gene had a basal level of expression in methionine- or cysteine-grown cells, which was induced when sulfate or thiosulfate was used. The metZ gene was cloned from the parent wild-type strain, CE3, and the resulting plasmid pAR204 relieved, after transformation, the methionine auxotrophy of both strains CTNUX23 of R. etli and PAO503(metZ) of Pseudomonas aeruginosa. Unlike strain CE3 or CTNUX23 (pAR204), strain CTNUX23 showed undetectable levels of O-succinylhomoserine sulfhydrylase activity. Strain CTNUX23 was unable to produce flavonoid-inducible lipo-chitin oligosaccharides (Nod factors) or to induce nodules or nodulelike structures on the roots of Phaseolus vulgaris, unless methionine was added to the growth medium. These data and our previous results support the notion that cysteine or glutathione, but not methionine, is supplied by the root cells to bacteria growing inside the plant.

The soybean ENOD40(2) promoter is active in Arabidopsis thaliana and is temporally and spatially regulated

The ENOD40 gene is induced early during Rhizobium-legume symbiosis and has probably a primary role in the nodule organogenesis. In this paper we show that the 1.7 kb 5'-flanking region of the GmENOD40(2) is able to drive the expression of a gusA-int marker in transgenic Arabidopsis thaliana. The promoter activity is developmentally regulated and the major activity is detected in the root and in the stigma.

A cysG mutant strain of Rhizobium etli pleiotropically defective in sulfate and nitrate assimilation

By its inability to grow on sulfate as the sole sulfur source, a mutant strain (CTNUX8) of Rhizobium etli carrying Tn5 was isolated and characterized. Sequence analysis showed that Tn5 is inserted into a cysG (siroheme synthetase)-homologous gene. By RNase protection assays, it was established that the cysG-like gene had a basal level of expression in thiosulfate- or cysteine-grown cells, which was induced when sulfate or methionine was used. Unlike its wild-type parent (strain CE3), the mutant strain, CTNUX8, was also unable to grow on nitrate as the sole nitrogen source and was unable to induce a high level of nitrite reductase. Despite its pleiotropic phenotype, strain CTNUX8 was able to induce pink, effective (N2-fixing) nodules on the roots of Phaseolus vulgaris plants. However, mixed inoculation experiments showed that strain CTNUX8 is significantly different from the wild type in its ability to nodulate. Our data support the notion that sulfate (or sulfite) is the sulfur source of R. etli in the rhizosphere, while cysteine, methionine, or glutathione is supplied by the root cells to bacteria growing inside the plant.

L-methionine induces stage-dependent changes of differentiation and oxidative activity in sea urchin embryogenesis

This study was to investigate developmental toxicity of some selected low molecular weight antioxidants, by utilising sea urchin embryos and gametes as model system. Sea urchin embryos or sperm were exposed at different developmental stages to L-methionine or some selected low molecular weight antioxidants: a) N-acetylcysteine; b) L-carnosine; c) L-homocarnosine, and d) L-anserine. L-methionine displayed developmental toxicity at levels > or = 10(-5) M, whereas the other agents tested were mostly active at levels > or = 10(-4) M. When embryos were exposed to 10(-4) M L-methionine or N-acetylcysteine at different developmental stages, the most severe effects were exerted by early exposures (0 to 2 hr after fertilisation), whereas later exposures turned to lesser or no effects. Cytogenetic analysis of L-methionine-exposed embryos showed a significant mitogenic effect and increase of mitotic aberrations. Fertilisation success was decreased by L-methionine (10(-6) M to 10(-3) M) added at the moment of fertilisation, with increasing developmental and cytogenetic abnormalities in the offspring. The formation of reactive oxygen species in embryos and gametes was determined by: a) analysing the DNA oxidative product, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and b) luminol-dependent chemiluminescence. The results showed that: 1) 8-OHdG levels were increased during embryogenesis; 2) fertilisation was associated with a double-wave luminol-dependent chemiluminescence emission; 3) luminol-dependent chemiluminescence was maximal in cleavage, declining down to zero in plutei, and 4) an embryotoxic L-methionine or N-acetylcysteine level (10(-4) M) turned to a decrease in reactive oxygen species formation. The data suggest that L-methionine- or N-acetylcysteine-induced developmental toxicity is confined to early stages. A role for oxidative activity is suggested in modulating cell differentiation and embryogenesis, consistent with antioxidant-induced damage to early life stages.

Cloning and transcriptional analysis of the lipA (lipoic acid synthetase) gene from Rhizobium etli

We report here the isolation of a Rhizobium etli gene involved in lipoic acid metabolism, the lipA gene, which complements a lipA mutant strain of Escherichia coli. A promoter region (lipAp) was mapped immediately upstream of lipA and two in vivo transcription initiation sites were identified, preceded by sequences showing some homology to the -10/-35 promoter consensus sequences. The activity of the lipAp was found not to be regulated either by the carbon source or by the addition of lipoic acid. Moreover, quantitative analysis of the lipA transcript by RNase protection assays indicated its down-regulation during entry into stationary phase.

Cloning of the rpoD analog from Rhizobium etli: sigA of R. etli is growth phase regulated

Rhizobium bacteria fix atmospheric nitrogen during symbiosis with legume plants only after bacterial division is arrested. The role of the major vegetative sigma factor, SigA, utilized by Rhizobium bacteria during symbiosis is unknown. By using PCR technology, a portion of the sigA gene corresponding to domain II was directly amplified from Rhizobium etli total DNA by using two primers designed in accordance with the published sequence of sigA from Agrobacterium tumefaciens. The amplified fragment was cloned and used as a hybridization probe for cloning of the R. etli sigA gene. Sequencing data revealed an open reading frame of 2,055 bp showing extensive similarity to various vegetative sigma factors. The 5' end of the sigA transcript was determined and revealed a long, seemingly untranslated region of 170 nucleotides. Quantitative analysis of the sigA transcript by RNase protection and by primer extension assays indicated its down-regulation during entry into the stationary phase. On the basis of the structures of various vegetative sigma factors and considering previous information on heterologous expression, we speculate on the function of domain I of vegetative sigma factors.

Cytogenetic, developmental, and biochemical effects of aluminum, iron, and their mixture in sea urchins and mussels

The present study was undertaken to evaluate the toxicity of aluminum sulfate, ferric chloride and their 1:1 mixture (Mix) on early development, fertilization and offspring quality in three sea urchins species (Sphaerechinus granularis, Paracentrotus lividus, Psammechinus microtuberculatus) and in mussels (Mytilus galloprovincialis). The endpoints were the following: a) larval malformations; b) developmental arrest; c) embryonic mortality; d) fertilization success; e) cytogenetic effects, and f) luminol-dependent chemiluminescence (LDCL). Overall data point to the induction of developmental defects in both sea urchin and mussel embryos following exposure of embryos to Al(III) or Fe(III) (10(-7) to 10(-6) M), whereas Mix caused varied effects vs. Al(III) or Fe(III) alone, from scarce or no additive effects (M. galloprovincialis and P. lividus) to a dramatic rise in embryolethality even at nominal levels of 10(-8) M (Ps. microtuberculatus).S. granularis sperm underwent a dose-dependent decrease in fertilization success following exposure to Al(III), or Fe(III), or Mix at levels ranging from 10(-8) to 10(-5) M. A significant increase of developmental defects was observed in the offspring of S. granularis sperm exposed to micromolar levels of the agents, suggesting an Al(III)- and Fe(III)-related transmissible damage to sperm. The cytogenetic analysis of Al(III)-, Fe(III)-, or Mix-exposed S. granularis embryos showed a significant increase in mitotic aberrations. A relevant feature of the observed cytogenetic damage included scattered chromosomes, suggesting cytoskeleton damage. The LDCL emission in S. granularis embryos showed a dose-related inhibition by agent levels ranging from 10(-7) to 10(-5) M; this held true for both spontaneous and, to a larger extent, for horseradish peroxidase (HRP)-activated LDCL. LDCL associated with fertilization was affected by Al(III), Fe(III) and Mix, with a time- and dose-related shift from stimulation to inhibition. The changes observed in LDCL emission suggested that the observed damage to embryogenesis, fertilization and mitotic activity may be related, at least partly, to alterations of the embryo prooxidant state. The present data point to developmental, cytogenetic and biochemical changes related to realistic levels of Al(III), Fe(III) and their mixtures, raising concern as to their environmental, occupational and iatrogenic exposures.

In vitro characterization of the ORF1-ntrBC promoter of Rhizobium etli

Rhizobium sigma vegetative-dependent promoters are different from those of enteric bacteria and have never been characterized before. We report here the biochemical characterization of the ORF1-ntrBC promoter of Rhizobium etli. The minimal promoter region was located by means of a transcriptional fusion and further characterized by in vitro transcription and gel retardation experiments. Oligonucleotides used as DNA competitors in runoff transcription experiments allowed the precise localisation of the promoter region. Protein extracts from an ntrC+, but not from an ntrC- strain, inhibited in vitro transcription. The NtrC protein was found to bind specifically to the promoter, where an NtrC binding site overlapping the transcription initiation site, is present.

Is the plasma membrane of the human oocyte reorganised following fertilisation and early cleavage?

The purpose of the present study was to determine whether the plasma membrane of the human oocyte is reorganised following fertilisation and during early cleavage. In order to characterise and localise the major sugar moieties on surface glycoproteins, oocytes and embryos were labelled with a range of fluorescent lectins. Regional organisation of plasma membrane microvilli in oocytes and embryos was also studied using scanning electron microscopy (SEM). The plasma membrane of human oocytes, zygotes and early blastomeres stained strongly and homogeneously with concanavalin A and Triticum vulgaris lectin (WGA), indicating the presence of plasma membrane glycoconjugates with alpha-D-mannosyl residues, sialic acid and beta-NAc-glucosaminyl groups. We did not observe regional domains in oocytes and zygotes, suggesting that the plasma membrane is not topographically reorganised following fertilisation. SEM shows the surface of the human zygote to be organised into short microvilli 0.2-3.0 microns in length and at a density of 5-20/microns2. In early cleavage stages the microvilli are shorter and less frequent (0.2-1.0 microns; 1-5/microns2); however, there is no evidence of polarisation at this level of organisation, at either stage of development. The surface of cell fragments, common in the human embryo in vitro, differs in having few microvilli and numerous cytoplasmic blebs. In conclusion, there are no obvious morphological signs of regionalisation in the plasma membrane of the human embryo before the 8-cell stage.

DNA binding activity of NtrC from Rhizobium grown on different nitrogen sources

The DNA-binding activity of the NtrC protein can be demonstrated in gel retardation assays with concentrated protein extracts of Rhizobium etli. Using extracts from either the wild type or a ntrC mutant strain and an antiserum raised against the NtrC protein, we demonstrate specific binding of NtrC to the upstream regulatory region of the glnII gene, where two putative NtrC-binding sites are present. KNO3-grown bacteria contain less NtrC protein and more NtrC-binding activity than NH4Cl-grown bacteria, thus showing that with this protocol it is possible to detect changes in NtrC-binding activity. The advantages of this assay system in comparison with that using pure proteins is discussed.

[Fractures of maxillo-facial bones in children. Our experience]

A clinic-statistical study of maxillo-facial fractures in a series of 52 children is reported. This group presents a higher involvement of mandibular body and a low rate M:F than in the literature. Factors responsible for increasing of maxillo-facial traumas in little girls and in school age are analyzed.

Fertilization current in the human oocyte

In this report we show that the first event of activation in the human oocyte, the Fertilization current (FC), is a slow transient outward current of 300 pA, which induces a gradual hyperpolarization of the plasma membrane from -20mV to -60mV, 60-120 min after insemination, followed by a repolarization to -20mV. Activation currents (AC) of 600-2,500 pA, induced by exposure to the calcium ionophore A23187 or by microinjection of InsP3 into the cytosol, are also outward. The AC are inhibited by preloading oocytes with EGTA suggesting they are calcium dependent. Since AC are 2-10-fold the amplitude of the FC the fertilizing spermatozoon in the human only activates a portion of the primary elements stored in the oocyte for triggering metabolic depression. Oocyte activation in the human resembles that in the hamster rather than other mammals or invertebrates studied to date.

Regulation of nitrogen metabolism is altered in a glnB mutant strain of Rhizobium leguminosarum

We isolated a Rhizobium leguminosarum mutant strain altered in the glnB gene. This event, which has never been described in the Rhizobiaceae, is rare in comparison to mutants isolated in the contiguous gene, glnA. The glnB mutation removes the glnBA promoter but in vivo does not prevent glnA expression from its own promoter, which is not nitrogen regulated. The glnB mutant strain does not grow on nitrate as a sole nitrogen source and it is Nod+, Fix+. Two -24/-12 promoters, for the glnII and glnBA genes, are constitutively expressed in the glnB mutant, while two -35/-10-like promoters for glnA and ntrBC are unaffected. We propose that the glnB gene product, the PII protein, plays a negative role in the ability of NtrC to activate transcription from its target promoters and a positive role in the mechanism of nitrate utilization.

A morphological and functional study of fusibility in round-headed spermatozoa in the human

OBJECTIVE

To study the molecular origin and functionality of the plasma membrane of round-head spermatozoa in the human.

DESIGN

Clinical and laboratory study.

SETTING

Patients in a clinical and academic environment.

PATIENTS

Men with round-head spermatozoa.

RESULTS

Pisum sativum lectin homogeneously stains the surface of round sperm; however, the staining pattern and transmission electron microscopy show that the plasma membrane does not alter after exposure to the calcium ionophore A23187. In a clinical program, round-head spermatozoa injected subzonally into metaphase II oocytes with or without pretreatment with the fusogen polyethylene glycol did not bind or fuse to the oocyte surface.

CONCLUSION

The data suggests that plasma membrane fusion in human gametes is regulated by specific surface molecules and that exposure of these molecules on the sperm surface cannot be triggered by elevating intracellular calcium alone.

Uridylylation of the PII protein in Rhizobium leguminosarum

Permeabilization with cetyl trimethyl ammonium bromide was used to study the post-translational modification of the PII protein in Rhizobium leguminosarum. Upon incubation with radioactive UTP a single band was obtained after SDS-PAGE and autoradiography. RNase resistance and snake venom phosphodiesterase sensitivity showed that radioactivity was bound through a phosphodiester bond to a protein which was absorbed by an antiserum specific for the PII protein. Uridylylation of the PII protein was shown to be dependent on the modifications of the glutamine/alpha-ketoglutarate ratio.

The ntrBC genes of Rhizobium leguminosarum are part of a complex operon subject to negative regulation

We report here that ntrB and ntrC genes of Rhizobium leguminosarum biovar phaseoli are cotranscribed with an open reading frame (called ORF1) of unknown function. The promoter region of the ORF1-ntrB-ntrC operon was mapped immediately upstream of ORF1 and two in vivo transcription initiation sites were identified, both preceded by -35/-10 promoter consensus sequences. Some major aspects differentiate R. leguminosarum from the enteric nitrogen regulatory system: the ntrBC genes are cotranscribed with ORF1 which is homologous to an ORF located upstream of ntrBC of R. capsulatus and to the ORF1 located upstream of the fis gene of Escherichia coli; ntrBC are not transcribed from a -24/-12 promoter and are only autogenously repressed. Moreover, the intracellular concentration of the NtrC protein increases when the bacterium is grown on ammonium salts, while under the same conditions the promoter of one of its target genes, glnII, is 12 times less active.

Single umbilical artery: a Doppler flow velocity study of four cases

We measured the pulsatility index of the umbilical artery in four fetuses identified as having a single umbilical artery. A pulsed color Doppler ultrasound machine was used and measurements were performed at 4-week intervals following the first diagnosis of single umbilical artery (week 22-34). The pulsatility index was derived from the mean of five consecutive measurements at the umbilical insertion of the cord, taking care to obtain the Doppler signal with an incidence angle between +45 degrees and -15 degrees. All measurements were taken during periods of fetal inactivity. The pulsatility index at 22, 26, 30, 34 and 38 weeks in these pregnancies did not differ significantly from the mean values registered in normal pregnancies. The four women gave birth to babies of normal weight: two were healthy, one suffered from bladder extrophy and hemispondyly, the other had bilateral dilatation of the renal pelves, megalocystis, megalourethra and an imperforate anus.

[Rheumatic manifestations and dental foci: a review of the cases in 12 years of activity in a pediatrics division]

By examining 8244 clinical records, in a period of 12 years of paediatric activity, the authors point out the connection between dental caries and rheumatic fever. They suggest fluoride supplementation since the early age, in countries where the fluoride is lack in drink able-water.

[Axial polydactyly: a clinical case]

After a short review of the normal embryonal development of lower limbs the authors describe a case of polydactyly associated with a 2nd-grade hypospadias observed in a 4-month-age patient. The authors, after the surgical treatment of both defects, have made the follow-up of the patient until six year age.

Phenotype of a Rhizobium leguminosarum ntrC mutant

A Tn5 insertion mutant, strain CFN2012, of Rhizobium leguminosarum biovar phaseoli devoid of glutamine synthetase II (GSII) activity was analysed. It was shown to contain Tn5 within an 11-kb BamHI DNA fragment, which was isolated (pSM261) from the wild-type strain and, when introduced into strain CFN2012, was shown to complement the absence of GSII activity. The DNA sequence of the corresponding region from the wild-type allele revealed the presence of an ntrC regulatory gene, and restriction analysis indicated that the mutant allele carried the Tn5 insertion within it. Further analysis of strain CFN2012 indicated that this mutant has reduced levels of the PII regulatory protein and that, in contrast to ntrC mutants of other Rhizobiaceae, it grows on nitrate as the sole nitrogen source.

The Rhizobium leguminosarum biovar phaseoli glnT gene, encoding glutamine synthetase III

Plasmid pGE203 contains the Rhizobium leguminosarum biovar phaseoli glnT locus. Glutamine synthetase III (GSIII) was purified from a glutamine auxotrophic strain of Klebsiella pneumoniae carrying this plasmid. Sequencing of a 2.4-kb fragment containing the glnT locus reveals an open reading frame of 435 amino acids (aa), whose first eight aa are identical to those determined from pure GSIII by direct aa sequencing, thus confirming that glnT indeed codes for GSIII activity. The comparison of the GSIII aa sequence with the reported sequence of GSs from other organisms shows a significant degree of homology. Since the three-dimensional structure of GS from Salmonella typhimurium is known, a three-dimensional model of GSIII was built by homology.

Dissociation by NH4Cl treatment of the enzymic activities of glutamine synthetase II from Rhizobium leguminosarum biovar viceae

Glutamine synthetase II (GSII) was purified to homogeneity from Rhizobium leguminosarum biovar viceae and characterized. The sequence of 26 amino acid residues from the amino-terminal end of the protein showed high similarity with the sequence of GSII from Bradyrhizobium japonicum or from Rhizobium meliloti. Non-denaturing PAGE showed that GSII, either in crude extracts or in the pure state, was a mixture of an octamer and a tetramer and that under specific conditions the octamer/tetramer ratio could be modified in either direction. The pure enzyme was used to raise an antiserum which was highly specific. Addition of NH4Cl to a bacterial culture derepressed for GSII caused a specific decrease in transferase activity, faster than the one observed when the amount of immunoreactive material was measured by different methods. On the other hand, biosynthetic activity, measured as the rate of ADP or glutamine formation, paralleled the rate of decrease in immunoreactive material. A partially purified enzyme preparation retained this dissociation of kinetic parameters, strongly suggesting a post-translational modification. These findings are discussed with respect to the possible role of GSII in the Rhizobium-legume symbiosis.

Activation of the Rhizobium leguminosarum glnII gene by NtrC is dependent on upstream DNA sequences

The cloning and sequence determination is reported of the DNA region of Rhizobium leguminosarum coding for glutamine synthetase II (GSII). An open reading frame (ORF) encoding 326 amino acids was defined as the glnII gene on the basis of its similarity to other glnII genes and the ability of a DNA fragment carrying this ORF to complement the glutamine auxotrophy of a Klebsiella pneumoniae glnA mutant. We find that the glnII gene in R. leguminosarum is transcribed as a monocistronic unit from a single promoter, which shows structural features characteristic of rpoN (ntrA)-dependent promoters. In K. pneumoniae, such promoters require the ntrC and rpoN (ntrA) gene products for transcription. The intracellular level of glnII mRNA changes when R. leguminosarum is grown on different nitrogen sources, as expected for regulation by the nitrogen regulatory system. Promoter deletion analysis has shown that an extensive upstream DNA sequence (316 bp) is essential for in vivo activation of the glnII promoter in different biovars of R. leguminosarum. This DNA region requires a wild-type ntrC gene for activity and includes two conserved putative NtrC-binding site sequences. The results conclusively show that transcription from the R. leguminosarum glnII promoter is fully dependent on positive control by NtrC protein and on an upstream activator sequence (UAS).

Transcriptional analysis of the glnB-glnA region of Rhizobium leguminosarum biovar viciae

We report that the glnB and glnA genes of Rhizobium leguminosarum biovar viciae are preceded by promoters located upstream of each gene. We find the presence of a glnB-glnA and a glnA mRNA whose intracellular concentration changes two- to three-fold when R. leguminosarum is grown on different nitrogen sources. Primer extension analysis shows unique transcriptional initiation sites upstream of glnB and glnA. The glnB promoter is rpoN(ntrA)-dependent, while the glnA promoter does not contain a typical consensus sequence for previously described promoters. In Klebsiella pneumoniae the glnB promoter requires active ntrC and ntrA genes and a DNA fragment containing 53 nucleotides upstream of the transcription initiation site shows full promoter activity, thus indicating that no NtrC binding sites are necessary for this activation in the glnB upstream region.

A previously unrecognized glutamine synthetase expressed in Klebsiella pneumoniae from the glnT locus of Rhizobium leguminosarum

Using glnT DNA of Rhizobium meliloti as a hybridization probe we identified a R. leguminosarum biovar phaseoli (R. l. phaseoli) locus (glnT) expressing a glutamine synthetase activity in Klebsiella pneumoniae. A 2.2 kb DNA fragment from R. l. phaseoli was cloned to give plasmid pMW5a, which shows interspecific complementation of a K. pneumoniae glnA mutant. The cloned sequence did not show cross-hybridization to glnA or glnII, the genes coding for two glutamine synthetase isozymes of Rhizobium spp. While in previous reports on glnT of R. meliloti and Agrobacterium tumefaciens no glutamine synthetase activity was detected, we do find activity with the glnT locus of R. l. phaseoli. The glutamine synthetase (GSIII) activity expressed in a K. pneumoniae glnA strain from pMW5a shows a ratio of biosynthetic to transferase activity 10(3)-fold higher than that observed for GSI or GSII. GSIII is similar in molecular weight and heat stability to GSI.

Comparative study of the symbiotic plasmid DNA in free living bacteria and bacteroids of Rhizobium leguminosarum

The symbiotic plasmid (pSym) DNA present in bacteroids of strain RCR1001 of Rhizobium leguminosarum biovar viceae has been compared qualitatively and quantitatively with that present in free living bacteria by hybridization experiments with appropriate probes. A decrease in the relative amount of pSym DNA was observed in bacteroids as compared to bacteria. No rearrangements of the symbiotically expressed pSym borne genes were detected in bacteroids.

Tight linkage of glnA and a putative regulatory gene in Rhizobium leguminosarum

Rhizobium leguminosarum, biovar viceae, strain RCC1001 contains two glutamine synthetase activities, GSI and GSII. We report here the identification of glnA, the structural gene for GSI. A 2 kb fragment of DNA was shown to complement the Gln- phenotype of Klebsiella pneumoniae glnA mutant strains. DNA sequence analysis revealed an open reading frame (ORF) of 469 codons specifying a polypeptide of 52,040 daltons. Its deduced amino acid sequence was found to be highly homologous to other glutamine synthetase sequences. This ORF was expressed in Escherichia coli minicells and the corresponding polypeptide reacted with an antiserum raised against GSI. Upstream of glnA we found an ORF of 111 codons (ORF111) preceded by the consensus sequence for an ntrA-dependent promoter. Minicells experiments showed a protein band, with a molecular weight in good agreement with that (10,469) deduced from the nucleotide sequence. On the basis of homology studies we discuss the possibility that the product of ORF111 is equivalent to the PII protein of E. coli and plays a similar role in regulation of nitrogen metabolism.

Characterization and cloning of two Rhizobium leguminosarum genes coding for glutamine synthetase activities

We have demonstrated that Rhizobium leguminosarum strain LPR1105 contains a heat stable and a heat labile glutamine synthetase (EC 6.3.1.2) activity similar to those described for other Rhizobiaceae. Most of the activity is heat stable when this strain is grown on glutamine as sole nitrogen source, but most is heat labile when grown on nitrate. Using a gene bank of R. leguminosarum DNA we have isolated two clones, which code for heat stable (p7D9) and heat labile (p4F7) glutamine synthetase activity, by complementing the glutamine auxotrophy of Klebsiella pneumoniae glnA mutants. Cross-hybridization of p7D9 with a fragment of the glnA gene of K. pneumoniae was observed, but no cross-hybridization between p7D9 and p4F7 was found. Since these two regions hybridize to genomic DNA of R. leguminosarum they are probably the structural genes for GSI and GSII, and the availability of these genes will make it possible to test this hypothesis. Clone p4F7 complements an ntrC+ but not an ntrC K. pneumoniae glnA mutant, suggesting that the ntrC gene is required for the complementation of the glutamine auxotrophy by this plasmid.

Characterization of bacteriophages infecting Streptomyces erythreus and properties of phage-resistant mutants

Three bacteriophages infecting Streptomyces erythreus, called G3, G4 and G5, were isolated and characterized. They contain double-stranded linear DNA molecules with cohesive ends. The restriction map of G3 DNA (48 kilobases long) for four restriction endonucleases and that of G4 DNA (43 kilobases long) for seven restriction endonucleases are reported. Restriction analysis and hybridization experiments showed that G3 and G4 share little DNA homology, while G4 and G5 are apparently identical except for an additional EcoRI site present in G5. The region containing this EcoRI site has been mapped on G4 DNA. Microbiological and serological data showed that G5 is very similar to G4. G3- and G4-resistant mutants of S. erythreus PS1 were isolated. The screening of phage-resistant mutants showed a high frequency of strains with increased erythromycin production. The mechanism of phage resistance of strain PS3 (G3 resistant) and of strain PS16 (G4 resistant) was examined. The DNA of the resistant strains contains no phage DNA, ruling out lysogeny as a cause of phage resistance. Transfection of strains PS1, PS3, and PS16 with DNA of the three phages showed the same efficiency, indicating that resistance is at the level of the bacterial wall.