苯并[α]芘对不同修复潜力羊茅属植物的根系分泌物中几种低分子量有机物的影响

根系分泌物是植物与土壤间进行物质交换和信息传递的重要载体, 是植物响应外界胁迫的重要途径, 也是构成根际微生态特征的关键因素。根系分泌物与有机污染物的植物修复密切相关, 研究胁迫条件下不同修复潜力植物间根系分泌物的释放特征有助于揭示植物修复的内在机制。该文借助根际袋土培试验研究了苯并[α]芘(BaP)胁迫下5种羊茅属(Festuca)植物根系不同生长期(30-70天)几种低分子量有机物的分泌特征。结果表明: 1) BaP浓度在10.25-161.74 mg·kg^-1范围内时, 待试植物能有效地促进土壤中BaP的去除, 其修复潜力依次为苇状羊茅(F. arundinacea) > 草原羊茅(F. chelungkiangnica) ≥ 毛稃羊茅(F. rubra subsp. arctica) ≥ 贫芒羊茅(F. sinomutica) > 细芒羊茅(F. stapfii)。2) BaP胁迫增强了植物根系对可溶性糖的分泌: 随着胁迫强度的增大、胁迫期的延长, 其分泌量变化呈“先升后降”趋势。3) BaP胁迫促进了植物根系低分子量有机酸的释放, 植物的修复潜力越大, 有机酸高峰值出现时的胁迫浓度越高; 组成成分较稳定, 草酸、乙酸、乳酸和苹果酸为主要组分(>97.34%), 在修复潜力较强植物的根系分泌物中检测出微量的反丁烯二酸。4) BaP胁迫对氨基酸种类影响不大, 但对分泌量影响较大。其中, 苏氨酸、丝氨酸、甘氨酸、丙氨酸的分泌量随BaP胁迫强度的增强而剧增; 脯氨酸、羟脯氨酸和天冬氨酸近乎以加和效应甚至协同效应的形式参与植物对BaP胁迫的应激反应: 参与应激组分的分泌量随胁迫强度的增强而剧增, 植物的修复潜力越强, 参与的组分越多。可见BaP胁迫下, 5种羊茅属植物根系分泌物中几种低分子量有机物的释放特征与植物自身的修复潜力有关: 修复潜力越强, 释放量越多且成分也越复杂, 并呈现出较强的环境适应性及生理可塑性。     

Alternative temperate forages containing secondary compounds for improving sustainable productivity in grazing ruminants

The use of alternative temperate forages to improve the sustainable productivity of grazing ruminants, relative to grass-based pastures, is reviewed. Particular emphasis is placed upon forages containing secondary compounds for sustainable control of internal parasites, for increasing reproductive rate in sheep, reducing bloat risk in cattle and for reducing methane production as a means of lowering greenhouse gas emissions.

Of the forages reviewed, the herb chicory (Chicorium intybus) and the condensed tannin-containing legumes Lotus corniculatus L. and sulla (Hedysarum coronarium) offered the most advantages. Chicory and sulla promoted faster growth rates in young sheep and deer in the presence of internal parasites, and showed reduced methane production in other studies. L. corniculatus was not as effective as chicory and sulla in promoting growth of lambs in the presence of internal parasites. Grazing on L. corniculatus was associated with increases in reproductive rate in sheep, increases in milk production in both ewes and dairy cows and reduced methane production, effects that were mainly due to its content of condensed tannins (CT). Grazing ewes on L. corniculatus during mating and very early pregnancy may also reduce lamb mortality. However, there are no data on the effect of mating ewes, which are grazing chicory on their reproductive performance, an important omission. Risk of rumen frothy bloat in cattle grazing legumes is reduced when the forage contains 5 g CT/kg dry matter (DM) or greater. Gene transfer techniques aimed at achieving this for lucerne (Medicago sativa) have made progress, but CT concentration needs to be further increased from calculated values of 0.75–1.25 g CT/kg DM in the transformed plants. Bloat control may be achievable in genetically transformed legumes before increased amino acid absorption, as the concentration of CT required for bloat control is lower (5 versus 30–40 g/kg DM) than that required to cause increased amino acid absorption and is not affected by differences in CT structure.

Key plant characteristics for improved sustainable productivity are a high ratio of readily fermentable: structural carbohydrate and the presence of CT and certain other secondary compounds.

Taking into account both nutritional and agronomic considerations, chicory is considered one of the best emerging plants for grazing livestock, with L. corniculatus being more suitable for areas with dry summers and warm winters. Some of the agronomic limitations of L. corniculatus and sulla could be reduced by mechanical harvesting and their inclusion as a component in total mixed rations (TMR), instead of grazing.     

Synthesis, spectroscopy, structure and photophysical properties of dinaphthylmethylarsine complexes of palladium(II) and platinum(II)

Dinaphthylmethylarsine complexes of palladium(II) and platinum(II) with the formulae [MX₂L₂] (M = Pd, Pt; L = di(1-naphthyl)methylarsine = Nap₂AsMe and X = Cl, Br, I), [M₂Cl₂(μ-Cl)₂L₂], [PdCl(S₂CNEt₂)L], [Pd₂Cl₂(μ-OAc)₂L₂] and [MCl₂(PR₃)L] (PR₃ = PEt₃, PPr₃, PBu₃, PMePh₂) have been prepared. These complexes have been characterized by elemental analyses, IR, Raman, NMR (¹H, ¹³C, ³¹P) and UV-vis spectroscopy. The stereochemistry of the complexes has been deduced from the spectroscopic data. The crystal structures of trans-[PdCl₂(PEt₃)(Nap₂AsMe)] and of [Pd(S₂CNEt₂)₂], a follow-up product, were determined. The UV-vis spectra of [MX₂L₂] complexes show a red shift on going from X = Cl to X = I. The complexes [PdX₂L₂] and [PtX₂L₂] are strongly luminescent in fluid solution and in the solid at ambient temperature.     

Oxidative stress in digestive gland and gill of the brown mussel (Perna perna) exposed to air and re-submersed

Mussels Perna perna were exposed to air for 24 h showing a clear increase in the levels of lipid peroxidation and oxidative DNA damage, measured as 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo). The levels of lipid peroxidation increased both in the digestive gland and gills, while oxidative DNA damage increased only in the gills. After the 24 h of air exposure, mussels were re-submersed for a period of 3 h, leading values to return to a pre-aerial exposure levels. Control animals were kept immersed during the whole period. Several antioxidant and complementary enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH), glutathione S-transferase (GST) and the levels of total glutathione (Total GSH) were assayed in a second set of experiments where one group of mussels were exposed to air for 18 h and other to 1 h re-submersion after 18 h aerial exposure. Only a 52% increase in the glutathione S-transferase activity was observed in the digestive gland, which remained elevated to about 40% after 1 h re-submersion, showing that defense systems can be modulated even during oxygen deprivation in P. perna. The DNA and lipid oxidative damage observed after aerial exposure indicates that mussels face an oxidative challenge, and are able to counteract such an “insult” as values of lipid peroxidation and DNA damage returned to control values after 3 h re-submersion.     

Indirect organogenesis and plant regeneration in Helicteres isora L., an important medicinal plant

Abstract    Helicteres isora is a medicinal plant effective against asthma, diabetes, hypolipidemia, HIV, polio besides a good source of diosgenin. Seed dormancy and low natural fruit production rate make this plant a perfect candidate for developing an in vitro regeneration method. However, to date, no such work has been procured in this plant. An efficient method for plant regeneration via shoot organogenesis from callus cultures has been developed using nodal explants in H. isora. Murashige and Skoog (MS) media counting 2,4-Dichlorophenoxyacetic acid (2,4-D, 2.26 to 13.57 μM), Indole-3-acetic acid (IAA, 2.85 to 17.13 μM), Indole-3-butyric acid (IBA, 2.46 to 14.70 μM), 6-Benzylaminopurine (BA, 2.22 to 13.32 μM) and Kinetin (Kin, 2.32 to 13.92 μM) either singly or in the following combinations (IAA + BA; IAA + Kin, and BA + Kin) produced granular callus except BA + Kin which resulted in compact, hard, greenish-white (CHGW) callus. The optimum CHGW callus (2.62 g fresh weight/ explant) was produced on MS media with 13.32 μM BA + 2.32 μM Kin with over 93% callus induction frequency. Optimum shoot organogenesis (67% frequency) was achieved in CHGW callus with lower level of BA (2.22 μM) and Kin (2.32 μM) and produced 3.2 shoots/0.5 g callus within 35 d of culture. Microshoots were rooted successfully (62% frequency) after 35 d of culture on 1/2MS containing 4.90 μM IBA and hardened off. Antioxidant enzymes such as catalase, peroxidase, polyphenol oxidase, and biochemical parameters viz. hydrogen peroxide, reducing and nonreducing sugars, starch, proteins, phenols, and proline contents were studied in regenerating and nonregenerating CHGW calluses to establish a correlation between these parameters and shoot morphogenesis. All the enzyme activities and biochemical parameters were found more in regenerating callus than in nonregenerating except phenols.     

Piperine activates testicular apoptosis in adult rats

Piperine, an alkaloid present in the fruits of commonly used spice pepper, is known to impair reproductive functions. In the present study, piperine was administered to adult male rats at the dose levels of 1, 10, and 100 mg/kg body weight for 30 days to evaluate its effects on the testis. A significant decrease in the activities of antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase in the testis was observed at 10 and 100 mg of piperine administration when compared with the controls. A dose‐dependent increase in lipid peroxidation and hydrogen peroxide generation was also observed. Sialic acid levels in the testis were also found to be decreased when piperine was administered at 10 and 100 mg dose levels. Immunofluorescence studies demonstrated a dose‐dependent increase in caspase 3 and Fas protein in testicular germ cells after piperine treatment. These observations indicate that piperine induces oxidative stress and thereby triggers apoptosis in the testis, contributing to hampered reproductive functions. © 2008 Wiley Periodicals, Inc. J Biochem Mol Toxicol 22:382–388, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20251     

ICAM-1 expression in vaginal cells as a potential biomarker for inflammatory response

This study aimed to elucidate the mechanisms that may lead to an efficient strategy to induce a suitable host response of the vaginal mucosa upon exposure to intravaginally delivered exogenous compounds. It was hypothesized that the upregulation of intercellular adhesion molecule (ICAM)-1 gene expression may reflect the inflammatory response evoked by exogenous compounds. Major emphasis was placed on ethylenediamine tetraacetic acid (EDTA) which was added as a synergistic agent to conventional spermicidal agents or anti-HIV drugs. The levels of ICAM-1 mRNA were examined as a surrogate marker for inflammatory response in human vaginal epithelial cells upon exposure to EDTA or interleukin (IL)-1β (i.e. positive control, 25 mM). The effects of estrogen on EDTA-induced ICAM-1 expression were also evaluated for the estrogen involvement in the inflammatory process of the vaginal mucosa. ICAM-1 expression in human vaginal cells (VK2/E6E7 cells) increased as EDTA concentration added to human vaginal cell lines increased. The effects of estrogen on EDTA-induced ICAM-1 expression in human vaginal epithelial cells were estrogen-concentration dependent; estrogen at lower concentrations (∼1-10 nM) did not affect ICAM-1 expression, whereas estrogen at higher concentrations (∼100 nM-1 µM) attenuated ICAM-1 expression. The influence of estrogen in ICAM-1 expression suggests the beneficial effects of estrogen on the regulation of vaginal homeostasis. Identification and quantification of specific surrogate markers for the inflammatory response evoked by exogenous compounds and their regulation by estrogen will lead to an efficient strategy against sexually transmitted diseases including AIDS.     

Production of branched-chain aroma compounds by Propionibacterium freudenreichii: links with the biosynthesis of membrane fatty acids

Aims: Short branched-chain fatty acids (BCFAs) are cheese flavour compounds, which result from the conversion of branched-chain amino acids (BCAAs). In Swiss cheese, the production of short BCFAs is mainly performed by Propionibacterium freudenreichii and is strain dependent. Our aim was to investigate the possible links between the biosynthesis of short BCFAs and membrane BCFAs in P. freudenreichii. Methods and Results: Short and membrane BCFAs were analysed by gas chromatography-mass spectrometry. Two strains differing in their capacities to release short BCFAs were selected. Tri-deuterated-labelled leucine was used in both strains as a precursor of short extracellular iso-BCFAs and of membrane iso-BCFAs. The proportions of anteiso : iso BCFAs synthesized varied as function of the BCAAs provided in the growth medium, from 72 : 28 to 100 : 0, with leucine and valine, and with isoleucine as sole BC precursors, respectively. The branching pattern of short BCFAs exactly matched that of membrane BCFAs, whatever the exogenous BCAAs provided. Conclusions: The biosynthesis of short BCFAs is closely related to that of membrane BCFAs in P. freudenreichii. Significance and Impact of the Study: The biosynthesis of short BCFAs in P. freudenreichii depends more on the strain than on the presence of exogenous BC precursors.     

UV mutagenesis of Cupriavidus necator for extracellular production of (R)-3-hydroxybutyric acid

Aim:  Ultraviolet (UV) mutagenesis was carried out to obtain mutant strains of Cupriavidus necator that could produce ( R )-3-hydroxybutyric acid [( R )-3-HB] in the culture supernatant.
Methods and Results:  C. necator (formerly known as Ralstonia eutropha ) was subjected to UV radiation to generate mutants that are capable of producing ( R )-3-HB in the culture supernatant. Results indicated that UV mutagen disrupted the phbB ( phbB knock-out) and thus, promoted production of ( R )-3-HB in mutant strains. Inclusion of acetoacetate esters (carbonyl compounds) in the culture broth led to increased production of ( R )-3-HB. Thus, acetoacetyl-CoA (an intermediate of the PHB synthetic pathway) might have been converted to acetoacetate, which in the presence of ( R )-3-HB dehydrogenase and NADPH/NADP⁺, resulted in extracellular production of ( R )-3-HB.
Conclusions:  UV mutagenesis proved to be a satisfactory method in generating interesting mutants for extracellular production of ( R )-3-HB. Extracellular production of ( R )-3-HB upon addition of acetoacetate esters would suggest a likely ( R )-3-HB biosynthetic pathway in C. necator .
Significance and Impact of the Study:  Mutants obtained in this study are very useful for production of ( R )-3-HB. For the first time, the production of ( R )-3-HB by C. necator via acetoacetate is reported.     

Characterization of kinetic parameters and the formation of volatile compounds during the tequila fermentation by wild yeasts isolated from agave juice

The production of aroma compounds during tequila fermentation using four native yeast strains isolated from agave juice was quantified at controlled (35 degrees C) and uncontrolled temperatures (room temperature) by gas chromatography (FID). Three of the four strains were identified as Saccharomyces cerevisiae (MTLI 1, MALI 1 and MGLI 1) and one as Kloeckera apiculata (MALI 2). Among the aroma compounds produced, acetaldehyde has the highest accumulation at the controlled temperature and before 50% of sugar was consumed. The S. cerevisiae strains produced ethyl acetate in almost the same quantity at a concentration of 5 mg/L and the K. apiculata produced six-times more (30 mg/L) than the S. cerevisiae strains, independent of the fermentation temperature. The rate and amount of 1-propanol, amyl alcohols and isobutanol production were affected by the type of yeast used. The K. apiculate strain produced 50% less of the higher alcohols than the Saccharomyces strains. The results obtained showed that indigenous isolated yeasts play an important role in the tequila flavor and suggest that mixtures of these yeasts may be used to produce tequila with a unique and desirable aroma.