Absorption of manganese by rice under flooded and unflooded conditions

Summary Manganese absorption by rice plants under flooded and unflooded conditions, in an upland and a lowland soil was studied. Both under flooded and unflooded conditions the rate of manganese absorption was high during 3rd to 4th week and again during 9th to 10th week.Rice grown under flooded conditions, in lowland soil absorbed more manganese and showed higher dry matter accumulation than under unflooded conditions. However manganese absorption and dry matter accumulation in rice grown under flooded conditions in upland soil were lower than under unflooded conditions.Rice grown under flooded conditions may give lower yields than rice grown under unflooded conditions due to some factor or combination of factors one of which may possibly be a high soluble iron content which interferes with the absorption of manganese.     

Short-day and low-temperature conditions promote reproductive maturation in the terrestrial slug, Lehmannia valentiana

Terrestrial slugs (Lehmannia valentiana) collected from a field in Osaka, southwestern Japan, were reared under long-day (16-h light and 8-h darkness, LD 16:8) or short-day conditions (LD 12:12) at 15, 20, or 25 degrees C for 60 days. Slugs reared under short-day conditions were heavier than those reared under long-day conditions; however, slugs reared at 15 degrees C gained more weight regardless of the photoperiodic condition. Gonads were significantly heavier under short-day conditions than under long-day conditions, and oogenesis and spermatogenesis were also induced under short-day conditions. Under short-day conditions, reproductive maturation was suppressed at 25 degrees C as compared with 15 and 20 degrees C, whereas under long-day conditions, lower temperatures induced reproductive maturation. In contrast, slugs reared under short-day conditions at 20 degrees C from the time of hatching gained more weight than those reared under long-day conditions at the same temperature. Moreover, short-day conditions induced reproductive maturation, similar to that observed in the field-collected slugs. In conclusion, short-day and low-temperature conditions promoted growth and reproductive maturation, whereas long-day and high-temperature conditions suppressed them in L. valentiana. Thus, L. valentiana reproduces from late autumn to spring in Osaka.     

Influence of redox potential on the anaerobic biotransformation of nitrogen-heterocyclic compounds in anoxic freshwater sediments

The potential for degradation of four nitrogen-heterocyclic compounds was investigated in fresh-water sediment slurries maintained under denitrifying, sulfate-reducing, and methanogenic conditions. Pyridine (10 mg/l) was rapidly transformed within 4 weeks under denitrifying conditions but persisted for up to 3 months under sulfate-reducing and methanogenic conditions. No intermediate biotransformation products of pyridine metabolism were detected under denitrifying conditions. Quinoline (10 mg/l) was completely transformed without a lag phase under methanogenic and sulfate-reducing conditions after incubation for 23 and 45 days, respectively. 2-Hydroxyquinoline was produced concomitantly with quinoline transformation under methanogenic and sulfate-reducing conditions. Under denitrifying conditions, less than 23% of the initial concentration of quinoline was transformed after anaerobic incubation for 83 days. Indole, however, was completely removed from sediment slurries under denitrifying, sulfate-reducing, and methanogenic conditions after anaerobic incubation for 18, 27, and 17 days, respectively. Only low amounts of oxindole (2–4 mg/l) accumulated during indole metabolism under methanogenic and denitrifying conditions, but under sulfate-reducing conditions, oxindole accumulation was stoichiometric with indole transformation. No evidence for biotransformation of carbazole was noted for all anaerobic conditions tested.     

Effects of electron acceptors, reducing agents, and toxic metabolites on anaerobic degradation of heterocyclic compounds

Degradation of four heterocyclic compounds was examined under nitrate-reducing, sulphate-reducing and methanogenic conditions. Soil samples from a creosote-polluted site in Denmark were used as inoculum. Indole and quinoline were degraded under all redox conditions with the highest degradation rates obtained under sulphate-reducing conditions. Benzothiophene and benzofuran were not degraded during the observation period of 100 days under any of the redox conditions. Indole and quinoline degrading cultures could be repeatedly transferred under all redox conditions, except for degradation of quinoline under sulphate-reducing conditions which was inhibited by sulphide at concentrations above 0.8 mM. Degradation of quinoline under methanogenic conditions was also inhibited by 3.2 mM sulphide used as a reducing agent, but sulphide had no inhibitory effect on the degradation of indole in methanogenic and sulphate-reducing soil slurries.     

Effect of γ Irradiation on the Fatty Acid Composition of Soybean and Soybean Oil

Food irradiation is a form of food processing to extend the shelf life and reduce spoilage of food. We examined the effects of γ radiation on the fatty acid composition, lipid peroxidation level, and antioxidative activity of soybean and soybean oil which both contain a large amount of unsaturated fatty acids. Irradiation at 10 to 80 kGy under aerobic conditions did not markedly change the fatty acid composition of soybean. While 10-kGy irradiation did not markedly affect the fatty acid composition of soybean oil under either aerobic or anaerobic conditions, 40-kGy irradiation considerably altered the fatty acid composition of soybean oil under aerobic conditions, but not under anaerobic conditions. Moreover, 40-kGy irradiation produced a significant amount of trans fatty acids under aerobic conditions, but not under anaerobic conditions. Irradiating soybean oil induced lipid peroxidation and reduced the radical scavenging activity under aerobic conditions, but had no effect under anaerobic conditions. These results indicate that the fatty acid composition of soybean was not markedly affected by radiation at 10 kGy, and that anaerobic conditions reduced the degradation of soybean oil that occurred with high doses of γ radiation.     

Induction of adult diapause and of low and high reproductive states in a parasitoid wasp,Ooencyrtus nezarae, by photoperiod and temperature

Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) was reared on eggs ofRiptortus clavatus (Thunberg) (Heteroptera: Alydidae) at various temperatures under long-day (L16:D8) or short-day (L10:D14) conditions. There was no diapause during egg, larval or pupal stages under any set of conditions examined. However, at 15°C under short-day conditions, vitellogenesis was arrested in all adult females and they entered diapause. At 15°C under long-day conditions, or at 20°C under short-day conditions, some adult females entered diapause. Under the latter set of conditions, the adult females laid eggs but they laid fewer eggs than under long-day conditions, Even at 25°C, under short-day conditions, adult females laid fewer eggs than under long-day conditions, and this low rate of oviposition was attributed to the retarded development of ovaries. Diapause adults reared at 15°C were more resistant to low temperature than nondiapause adults reared at 25°C.     

Enhanced biodegradation of cyclotetramethylenetetranitramine (HMX) under mixed electron-acceptor condition

The biodegradation of cyclotetramethylenetetranitramine, commonly known as 'high melting explosive' (HMX), under various electron-acceptor conditions was investigated using enrichment cultures developed from the anaerobic digester sludge of Thibodaux sewage treatment plant. The results indicated that the HMX was biodegraded under sulfate reducing, nitrate reducing, fermenting, methanogenic, and mixed electron accepting conditions. However, the rates of degradation varied among the various conditions studied. The fastest removal of HMX (from 22 ppm on day 0 to < 0.05 ppm on day 11) was observed under mixed electron-acceptor conditions, followed in order by sulfate reducing, fermenting, methanogenic, and nitrate reducing conditions. Under aerobic conditions, HMX was not biodegraded, which indicated that HMX degradation takes place under anaerobic conditions via reduction. HMX was converted to methanol and chloroform under mixed electron-acceptor conditions. This study showed evidence for HMX degradation under anaerobic conditions in a mixed microbial population system similar to any contaminated field sites, where a heterogeneous population exists.     

Effect of γ irradiation on the fatty acid composition of soybean and soybean oil

Food irradiation is a form of food processing to extend the shelf life and reduce spoilage of food. We examined the effects of γ radiation on the fatty acid composition, lipid peroxidation level, and antioxidative activity of soybean and soybean oil which both contain a large amount of unsaturated fatty acids. Irradiation at 10 to 80 kGy under aerobic conditions did not markedly change the fatty acid composition of soybean. While 10-kGy irradiation did not markedly affect the fatty acid composition of soybean oil under either aerobic or anaerobic conditions, 40-kGy irradiation considerably altered the fatty acid composition of soybean oil under aerobic conditions, but not under anaerobic conditions. Moreover, 40-kGy irradiation produced a significant amount of trans fatty acids under aerobic conditions, but not under anaerobic conditions. Irradiating soybean oil induced lipid peroxidation and reduced the radical scavenging activity under aerobic conditions, but had no effect under anaerobic conditions. These results indicate that the fatty acid composition of soybean was not markedly affected by radiation at 10 kGy, and that anaerobic conditions reduced the degradation of soybean oil that occurred with high doses of γ radiation.     

水分胁迫下AM真菌对枳实生苗叶片矿质营养吸收的影响

在温室盆栽条件下研究丛枝菌根真菌(AM真菌)Glomus versiforme对水分胁迫下(正常水分为对照)的枳[Poncirus trifoliata (L.) Raf.]实生苗叶片矿质营养吸收的影响.研究表明,水分胁迫显著抑制AM真菌对枳实生苗根系的侵染.无论在正常水分还是在水分胁迫下,AM真菌的感染显著提高枳实生苗叶片P、K和Ca的含量,水分胁迫下的菌根贡献率均高于对照;AM真菌的接种对叶片N、Mg和Cu含量没有显著影响.与未接种处理相比,AM真菌处理仅对水分胁迫下的枳实生苗叶片Fe和Zn含量有显著促进作用.研究还表明,接种处理降低叶片Mn含量,正常水分下达到显著水平.     

YS型小麦温敏雄性不育系A3017育性相关基因的SSH分析

以人工气候箱控温条件下YS型小麦温敏不育系A3017的不育幼穗和可育幼穗为材料,分别构建了不育和可育条件下基因特异表达的抑制消减杂交cDNA文库.在两个库中分别随机挑选100个阳性克隆进行测序,经BLAST序列比对分析,共获功能已知的EST 78条.比较发现,不育条件下与细胞质相关的基因表达数量(63.4%)远高于可育条件下的基因数量(35.1%),参与蛋白质合成、蛋白质修饰/加工/储藏、转运和信号传递过程基因的比例也均高于可育条件下的,而参与能量代谢过程基因的比例则明显偏低.分析认为,在不育和可育条件下的基因表达差异可能是导致温敏雄性不育系育性变化的关键,这为进一步从分子基础上揭示YS型小麦温敏雄性不育系育性转换机制奠定了基础.     

Microbial mineralization of VC and DCE under different terminal electron accepting conditions

Production of 14CO2 from [1,2-14C] dichloroethene (DCE) or [1,2-14C] vinyl chloride (VC) was quantified in aquifer and stream-bed sediment microcosms to evaluate the potential for microbial mineralization as a pathway for DCE and VC biodegradation under aerobic, Fe(III)-reducing, SO4-reducing, and methanogenic conditions. Mineralization of [1,2-14C] DCE and [1,2-14C] VC to 14CO2 decreased under increasingly reducing conditions, but significant mineralization was observed for both sediments even under anaerobic conditions. VC mineralization decreased in the order of aerobic > Fe(III)-reducing > SO4-reducing > methanogenic conditions. For both sediments, VC mineralization was greater than DCE mineralization under all electron-accepting conditions examined. For both sediments, DCE mineralization was at least two times greater under aerobic conditions than under anaerobic conditions. Although significant microbial mineralization of DCE was observed under anaerobic conditions, recovery of 14CO2 did not differ substantially between anaerobic treatments.     

Effect of larval density on development and diapause of Sesamia nonagrioides (Lef.) (Lep., Noctuidae) under laboratory conditions

The effect of larval density on development and diapause of Sesamia nonagrioides (Lef.) was examined. Larvae were grown on an artificial diet at densities of five, 10, 20, 30 and 40 larvae per box, under two environmental (diapause-including and diapause-averting) conditions. High larval densities resulted in increased mortality under both experimental conditions tested. Although crowded larvae showed a higher pupation rate than those reared under low densities, small differences occurred between mean larval developmental time at different densities under developmental condition. In spite of this, crowding proved effective on the intensity of diapause of this species and the duration of diapause was shorter for crowded larvae. Pupal weights of both sexes were significantly reduced at high densities while there were significant differences between pupal weights formed by larvae reared under diapause conditions and those formed by larvae reared under nondiapause conditions at all density treatments. The pupal period was significantly longer under diapause conditions than that under development conditions but density was not found to play a role on the time of the emergence of the adults produced by larvae reared under developmental or diapause conditions.     

Influence of fasting status on the effects of coconut oil on chick plasma and lipoprotein composition

For a better understanding of the hyperlipidemic function of saturated fat, we have studied the effects of diet supplementation with 10-20% coconut oil on the chick plasma and lipoprotein composition under postprandial and starvation conditions. A significant hypercholesterolemia was found in chicks fed the standard diet after 12 h of food deprivation. In these conditions, LDL-cholesterol also increased, whereas triglyceride levels were reduced in HDL, VLDL and chylomicron fractions. Coconut oil induced a significant hypercholesterolemia under both conditions, also increasing the plasma triglyceride content under postprandial conditions, but not after starvation. Coconut oil feeding increased all the chemical components of HDL, especially under postprandial conditions, but did not affect the HDL-triglycerides under food-deprivation conditions. Total cholesterol and triglyceride levels in LDL increased after coconut oil supplementation to the diet. Differences were more pronounced under postprandial conditions. Changes in VLDL and chylomicron composition were less evident.     

Effects of atmospheric environment,before and after treatment,on the toxicity to insects of contact poisons

Experiments were made on the effect of conditions before and after treatment on the toxicity to adult Tribolium castaneum Hbst. of the following contact poisons in the media stated: (i) pyrethrins, (2) lauryl thiocyanate, (3) nicotine-all in aqueous medium, (4) dinitro-o-cresol in ethylene glycol, (5) Wakefield half-white oil, (6) D.D.T. in Wakefield half-white oil.
The difference in environment before spraying did not have any marked effect but, with the exceptions of nicotine and petroleum oil, all the toxicants used were more insecticidal when the beetles were kept under cool conditions after spraying. Nicotine showed little difference due to after-treatment when an inverted filter funnel was used to confine the insects, but seemed markedly more toxic under cooler conditions of after-treatment when the insects were confined in the dishes by means of muslin.
Wakefield half-white oil, a non-volatile petroleum oil, proved more toxic when the insects were kept under warm conditions after treatment than under cool conditions. The increase in toxicity of chemically active contact poisons under cool conditions of after-treatment appeared to occur whatever the nature of the carrier, whether volatile or non-volatile, water or oil.
In the substances tested, with the exception of nicotine under special circumstances, the increase in toxicity under cool conditions of after-treatment occurred whatever the volatility of the poison.
The change in toxicity, when cool conditions were compared with hot, varied with the poison used. With nicotine in aqueous medium the change was relatively small, the toxicity under cold conditions throughout being 1-23 times the toxicity under hot conditions throughout. At the other extreme with pyrethrins and terpineol in aqueous medium there was a large alteration, the toxicity under cold conditions throughout being about 7 times the toxicity under the hot conditions throughout.     

Effects of Glycerol on the Fluorescence Spectra and Chloroplast Ultrastructure of Phaeodactylum tricornutum (Bacillariophyta)

Responses of the photosynthetic activity of Phaeodactylum tricornutum (Bacillariophyta) to organic carbon glycerol were investigated. The growth rate, photosynthetic pigments, 77 K fluorescence spectra, and chloroplast ultrastructure of P. tricornutum were examined under photoautotrophic, mixotrophic, and photoheterotrophic conditions. The results showed that the specific growth rate was the fastest under mixotrophic conditions. The cell photosynthetic pigment content and values of Chl a/Chl c were reduced under mixotrophic and photoheterotrophic conditions. The value of carotenoid/Chl a was enhanced under mixotrophic conditions, but was decreased under photoheterotrophic conditions. In comparison with photoautotrophic conditions, the fluorescence emission peaks and fluorescence excitation peaks were not shifted. The relative fluorescence of photosystem (PS) Ⅰ and PS Ⅱ and the values of F6851F710 and F685/F738 were decreased. Chloroplast thylakoid pairs were less packed under mixotrophic and photoheterotrophic conditions. There was a strong correlation between degree of chloroplast thylakoid packing and the excitation energy kept in PS Ⅱ. These results suggested that the PS Ⅱ activity was reduced by glycerol under mixotrophic conditions, thereby leading to repression of the photosynthetic activity.     

Oxygen control of nitrogen oxide respiration, focusing on α-proteobacteria

Denitrification is generally considered to occur under micro-oxic or anoxic conditions. With this in mind, the physiological function and regulation of several steps in the denitrification of model α-proteobacteria are compared in the present review. Expression of the periplasmic nitrate reductase is quite variable, with this enzyme being maximally expressed under oxic conditions in some bacteria, but under micro-oxic conditions in others. Expression of nitrite and NO reductases in most denitrifiers is more tightly controlled, with expression only occurring under micro-oxic conditions. A possible exception to this may be Roseobacter denitrificans, but the physiological role of these enzymes under oxic conditions is uncertain.     

Biodegradation and metabolites of 2-methylquinoline by acclimated activated sludge under aerobic and denitrifying conditions

2-Methylquinoline is a common organic contaminant in environment. Its degradation in wastewater treatment system has not been fully explored. In this study, batch experiments were conducted to investigate the biodegradation of 2-methylquinoline by activated sludge under both aerobic and denitrifying conditions. The results showed that 2-methylquinoline was degraded under both conditions, but the degradation under aerobic condition was significantly faster than that under denitrifying condition. Total organic carbon (TOC) residues were detected in the final effluent under both conditions, indicating the formation of recalcitrant metabolites. Further analysis identified 1,2,3,4-tetrahydro-2-methylquinoline, N,N-diethyl-benzenamine, and 4-ethyl-benzenamine as common metabolites under both conditions. 4-Butyl-benzenamine and 2,6-diethyl-benzenamine were additional metabolites under the aerobic condition, whereas 2-methyl-4-quinolinol was exclusive to the denitrifying condition. Most of these metabolites were further degraded during the treatment process. 1,2,3,4-Tetrahydro-2-methylquinoline, however, remained in the final effluent under both conditions, implying its persistence in the environment. It can be concluded that 2-methylquinoline undergoes the similar degradation pathway under both treatment conditions.     

Murine gallbladder epithelial cells can differentiate into hepatocyte-like cells in vitro

We determined whether extrahepatic biliary epithelial cells can differentiate into cells with phenotypic features of hepatocytes. Gallbladders were removed from transgenic mice expressing hepatocyte-specific beta-galactosidase (beta-Gal) and cultured under standard conditions and under experimental conditions designed to induce differentiation into a hepatocyte-like phenotype. Gallbladder epithelial cells (GBEC) cultured under standard conditions exhibited no beta-Gal activity. beta-Gal expression was prominent in 50% of cells cultured under experimental conditions. Similar morphological changes were observed in GBEC from green fluorescent protein transgenic mice cultured under experimental conditions. These cells showed higher levels of mRNA for genes expressed in hepatocytes, but not in GBEC, including aldolase B, albumin, hepatocyte nuclear factor-4alpha, aldehyde dehydrogenase 1, and glutamine synthetase, and they synthesized bile acids. Additional functional evidence of a hepatocyte-like phenotype included LDL uptake and enhanced benzodiazepine metabolism. Connexin-32 expression was evident in murine hepatocytes and in cells cultured under experimental conditions, but not in cells cultured under standard conditions. Notch 1, 2, and 3 and Notch ligand Jagged 1 mRNAs were downregulated in these cells compared with cells cultured under standard conditions. CD34, alpha-fetoprotein, and Sca-1 mRNA were not expressed in cells cultured under standard conditions, suggesting that the hepatocyte-like cells did not arise from hematopoietic stem cells or oval cells. These results point to future avenues for investigation into the potential use of GBEC in the treatment of liver disease.