Toxic effects of HgCl2 on the growth and oogonium formation in Oedogonium hatei

The effect of mercuric chloride on the germination and growth of swarmers and subsequent induction of oogonia was studied in Oedogonium hatei Kam. (Oedogoniales, Chorophyceae). HgCl2 within the concentration range of 0.01 to 1.0 mg/l produced a progressive increase in the initiation of germination and reduction in the growth of the alga. The percentage of oogonia formed, and mature oogonia developed, decreased linearly with a rise in the concentrations of HgCl2 employed. The results showed that 1 mg/l HgCl2 was highly toxic to the growth and/or multiplication of zoospores and further development of sexual structures in O. hatei. The germination of zoospores and growth of germlings were so severely affected that induction of oogonia remained completely inhibited at 1 mg/l HgCl2. Moreover, 2 mg/l of HgCl2 was lethal to the asexual zoospores.     

Über die Entwicklung des marinen parasitischen PhycomycetenLagenisma coscinodisci (Lagenidiales)

This paper concentrates on the study of vegetative development and sexual reproduction inLagenisma coscinodisci Drebes. Before infecting a diatom cell (Coscinodiscus granii), the freshly released zoospores pass through two different cyst stages. The primary zoospores are kidney-shaped and laterally biflagellated. They form a primary cyst with a spiny cyst wall which is left by isomorphic secondary zoospores. The latter form a secondary cyst (sometimes perhaps repeatedly), which is smooth-walled. The secondary cyst germinates and infects a new diatom cell by means of an infecting tube which enters the cell through the gap between epi- and hypotheca and develops a new thallus. Sexual reproduction is induced by ageing of cultures. Two kinds of isomorphic, kidney-shaped, laterally biflagellated swarmers are produced as in zoosporogenesis. Female-determined swarmers settle down near the host cell and encyst with a more or less smooth wall (oogonia). Male-determined swarmers are obviously attracted by the oogonia and encyst close to them to form a more or less smooth-walled antheridium which drives a thin fertilization tube to the oogonium. During plasmogamy the oogonium develops a thick, short hypha. The cytoplasm with the two nuclei moves completely into this hypha, concentrates near the hyphal tip, and surrounds itself with a thick wall to become a resting spore (oospore) in which karyogamy takes place. The walls of cysts, tubes, hyphae and spores react positively with zinc-chlor-iodide. In the spines and walls of the primary cysts the network of 2 to 3 nm thick fibrils is more distinct than in the other walls.     

Production of 3-indoleacetic acid by aRhizobium sp. fromMimosa pudica

ARhizobium species isolated from the root nodules of the sensitive plant,Mimosa pudica, produced 60 mg/L of 3-indoleacetic acid (IAA) froml-tryptophan in culture. The production of IAA started simultaneously with the growth and had no different growth or production phase. The stationary phase of growth was reached after 55 h, but the production of IAA increased gradually up to 80 h, and then remained constant. The IAA production could be promoted in the culture medium up to 365% by supplementing the medium with maltose, CuSO₄ and Triton X-100.     

Additive effects of three auxins and copper on sorghum in vitro root induction

A healthy root system is vital for tissue culture plantlet survival and rapid adaptation from the in vitro microenvironment to glasshouse conditions. Optimization of the root induction medium is an effective way to promote root induction and elongation. Levels of three auxins (α-naphthaleneacetic acid [NAA], 3-indoleacetic acid [IAA], and 3-indolebutyric acid [IBA]) and copper sulfate (CuSO₄) have been investigated in a series of experiments with a sorghum inbred line, Tx430. Significant improvement in root proliferation and shoot growth were observed on Murashige and Skoog (MS) medium supplemented with 1 μmol/L CuSO₄, 1 mg/L NAA, 1 mg/L IAA, and 1 mg/L IBA. On average, one explant (the original in vitro-derived shoot) of Tx430 regenerated 56.7 roots, which was 20-fold higher on the optimal medium than on MS control medium. Another tested genotype SA281 showed similar response patterns as Tx430 across media. In addition, 100% of Tx430 and SA281 plantlets originating from the optimized root induction medium all survived after being transferred to potting soil in the glasshouse. The results demonstrate that a combination of auxins (NAA, IAA, and IBA) and CuSO₄ together at optimal concentrations provide additive effects on promoting root proliferation and explant growth of in vitro sorghum in root induction medium, and subsequently resulted in 100% survival rate of plantlets ex tissue culture. Compared with two published and frequently used root induction media, the optimized medium significantly enhanced root induction and plantlet growth.     

Effects of alginate oligomer on the expression of cell cycle- and stress-related genes in Chlamydomonas reinhardtii

Enzymatically prepared alginate oligomer (AO) promoted the growth of Chlamydomonas reinhardtii in a concentration-dependent manner. AO at 2.5 mg/mL induced increase in expression levels of cyclin A, cyclin B, and cyclin D in C. reinhardtii. CuSO₄ at 100 μM suppressed the growth of C. reinhardtiin, and AO at 2.5 mg/mL significantly alleviated the toxicity of CuSO₄. Increased intracellular reactive oxygen species level in C. reinhardtii induced by CuSO₄ was reduced by AO. After cultivation with CuSO₄ at 100 μM, expression levels of ascorbate peroxidase and superoxide dismutase in C. reinhardtii were increased, and AO reduced the increased levels of these enzymes. These results suggest that AO exhibits beneficial effects on C. reinhardtii through influencing the expression of various genes not only at normal growth condition but also under CuSO₄ stress.     

Inhibitory Effects of Methyl Jasmonate on the Germination and Ethylene Production in Cocklebur Seeds

Methyl jasmonate (JA-Me) inhibited the germination of cocklebur (Xanthium pennsylvanicum Wallr.) seeds. The inhibition of the germination of cocklebur seeds treated with JA-Me at concentrations less than 300 μm was nullified by ethylene applied exogenously, although the inhibitory effect of 1,000 μm JA-Me was not recovered completely even by high concentrations of ethylene (10,000 μL/liter). JA-Me inhibited ethylene production before seed germination. The level of 1-aminocyclopropane-1-carboxylic acid (ACC) in the cotyledonary tissues treated with JA-Me decreased but not the level of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC). JA-Me inhibited the conversion of ACC to ethylene in the tissues. These results suggested that JA-Me inhibits ethylene production by prevention of ACC oxidation in addition to ACC synthesis. We believe that the inhibition of ethylene production by JA-Me results in the retardation of the germination of cocklebur seeds. Received June 4, 1997; accepted October 23, 1997     

Studies on the mercury volatilizing enzymes in nitrogen-fixing Beijerinckia mobilis

Beijerinckia mobilis KDr₂, a broad-spectrum, mercury-resistant nitrogen-fixing organism, possesses multiple metal-resistance properties. Mercuric reductase and organomercurial lyase activities of this bacterial strain were determined using different mercury compounds and heavy metal salts of copper, nickel, cobalt, cadmium, silver, zinc, lead and arsenate as inducers and substrates. Mercuric reductase was partially purified and the effect of some enzyme inhibitors and heavy metal ions on the enzyme activity was studied. The enzyme activity was completely inhibited by CdCl₂, Bi(NO₃)₃ and KCN at 10^-5 M and by AgNO₃, CoCl₂ and CuSO₄ at 10^-4 M.     

Superoxide dismutase is involved in high tolerance to copper in the deep-sea yeast, Cryptococcus sp. N6

The activity and expression of superoxide dismutase (SOD) was analyzed in a copper-tolerant yeast, Cryptococcus sp. N6. Using cell extracts, two distinct bands exhibiting SOD activity appeared on native PAGE: one band, with higher mobility, appeared when the cells were grown without CuSO₄, and the other band appeared when the cells were grown with 10 mM CuSO₄. Cells grown with 3 mM CuSO₄ produced both SOD isoforms. Western blot analysis, using a monoclonal antibody against human SOD-1, showed that SOD protein was expressed in the absence of CuSO₄ and that the expression level increased when the cells were grown with 3 or 10 mM CuSO₄. The molecular weight of SOD from strain N6 was approx. 18 kDa. Treatment of the cells with the protein synthesis inhibitor, cycloheximide at 0.5 g ml^–1, did not affect cell growth in the absence of CuSO₄ but significantly inhibited growth in the presence of 10 mM CuSO₄ and inhibited expression of SOD protein. This suggests that SOD may play a role in cell growth in the presence of high concentrations of CuSO₄.     

Influence of temperature upon growth and sporulation in two species of Phytophthora

The paper deals with the influence of temperature on the growth and sporulation of two species ofPhytophthora, viz.,P. palmivora Butl. andP. parasitica Dast. var.macrospora Ashby, the causal agents of fruit rots ofAchras sapota L. andAnona squamosa L. respectively. Germination of sporangia at different temperatures were also undertaken. There was marked variation in growth and sporulation of these two organisms. Isolate C (Phytophthora palmivora) showed no growth at 5° and 35°C, scanty growth at 10° and 32.5° with an optimum temperature between 26–28°C. On the other hand, Isolate S (Phytophthora parasitica var.macroscora) showed no growth at 10°C, but slight growth even at 37°C. Eight days exposure at 37°C completely stopped the growth of this Isolate. It showed best growth at 30°C and hence this was its optimum temperature. In general, Isolate C sporulated abundantly at all temperatures tested but reached its maximum at 25°C. On the other hand Isolate S showed best growth but failed to sporulate at any of the temperatures in 98 hours growth, although it sporulated freely when the incubation period extended up to two weeks. On the basis of temperature toleration the twoPhytophthora isolates are distinguished from each other as two different species. This confirms the earlier observations and nomenclature criterion as emphasized and formulated byTucker (1931). In the germination studies, it was observed that the indirect germination with the formation of abundant zoospores started from 5° and continued even up to 35°C, reaching maximum at 20°C. High temperature was not favourable for indirect germination. As the temperature proceeded increasing, the percentage of direct germination by formation of germ tubes also increased. Direct germination was observed from 10° which continued up to 37°C, with a maximum reach at 30°C. This confirms the epidemic of fruit rots in nature during monsoon season which is prevalent with the persistence of high humidity and rainfall.Taken from a thesis submitted by the author for the degree of Master of Science in the Faculty of Agriculture, Poona University, India.     

Effect of copper on shoot and root regeneration in wheat,triticale, rape and tobacco tissue cultures

CuSO₄ (0.1–100 M) significantly enhanced shoot regeneration from calli of wheat and triticale and of tobacco leaf disc cultures. In cultures of wheat and triticale, CuSO₄ also stimulated root formation. When equal concentrations of CuSO₄ were applied in different media, it was found that the components of the basal media had only modifying effects. CuSO₄ pretreatment promoted plant survival when regenerated wheat plants were transferred directly to potting soil. In contrast with CuSO₄, AgNO₃, which also stimulated shoot regeneration, inhibited rooting in wheat and triticale. In Brassica napus callus cultures, AgNO₃ strongly increased morphogenesis, whereas CuSO₄ had no significant effect.Abbreviations BA benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - KN kinetin - NAA naphthaleneacetic acid     

Abiotic metal stress enhances diosgenin yield in Dioscorea bulbifera L. cultures

Lower concentrations of CuSO₄ (25–75 M) in the MS medium supplemented with 0.1 mg l^–1 IAA+5.0 mg l^–1 Kn+500 mg l^–1 CH+10 mg l^–1 Cyst hyd enhanced the growth of regenerants of Dioscorea bulbifera L. CuSO₄ (75 M) induced an appreciable diosgenin yield in the regenerants compared to those obtained on media without Cu. The presence of Cu thus seems to stimulate diosgenin production. The regenerants also differentiated bulbils on lower concentrations of Cu. At CuSO₄ (100 M), however, cultures showed poor growth as well as a low diosgenin yield. Increased proline and protein contents were recorded in cultures grown on Cu-enriched media.     

On the Reversal of the Inhibition of Photosynthesis Induced by Sodium Dimethyldithiocarbamate and Tetramethylthiuram disulphide

The reversal of 80–100 per cent inhibition of photosynthesis in the green alga Enteromorpha linza (L.) J. Ag., obtained with tetramethylthiuram disulphide (TMTD) and the corresponding sodium dithiocarhamate (Na-DMDT), was investigated. The inhibition obtained by the two compounds proves to be almost completely reversible by simply washing away the inhibitors. Copper(II) sulphate partially reversed the inhibition obtained with Na-DMDT while reduced glutathione (GSH) partially reversed inhibition obtained with both Na-DMDT and TMTD. The time to complete the reversal varied between 12 and 33 min. Almost no reversal of the TMTD induced inhibition was achieved with CuSO₄. Na-DMDT and CuSO₄ reacted instantaneously with each other. GSH most probably reduced TMTD stoichiometrically to DMDT. This reaction was complete- within 6 seconds. No reaction took place between GSH and Na-DMDT. The interpretation of The results eliminates the most conventional explanation of the mechanism of the inhibition of photosynthesis in E. linza with Na-DMDT, viz. complex formation with functional metals. The reaction between TMTD and functional thiol groups in the alga is the most plausible inhibition mechanism. It is inferred from the results that Na-DMDT is most probably oxidized by E. linza to TMTD and effects inhibition in this form. (PDF DAMAGE)     

叶面喷施氨基酸和微量元素对金银花生长发育和质量的影响

以2年生金银花为试验材料,采用叶面喷施法,研究不同浓度的苯丙氨酸(Phe)、酪氨酸(Lyr)以及锌(Zn2+)、铜(Cu2+)对金银花生长发育和质量的影响。结果显示:(1)喷施不同浓度的Phe、Lyr以及Zn2+、Cu2+对叶面积无明显影响;不同处理的叶绿素含量随喷施次数的增加而出现不同程度的下降,喷施浓度适宜则有助于叶绿素的合成;喷施一定浓度的Phe、Lyr以及Zn2+、Cu2+可增加花蕾重量,如经1 000mg/g Phe处理后的花蕾鲜重与干重较对照增加了20.1%和51.4%。(2)不同浓度的Phe、Lyr可显著影响碳代谢,但对氮代谢影响不明显;Zn2+、Cu2+对碳氮代谢产物影响较明显,如喷施10mg/L的CuSO4及ZnSO4可提高可溶性糖及淀粉含量。(3)除Zn2+处理后的花蕾类黄酮含量显著低于对照外,其他处理较CK无显著差异;花蕾总黄酮含量均显著低于对照,但绿原酸含量均高于对照。(4)叶片中离子含量受喷施次数及浓度影响较明显,除30mg/L CuSO4处理外,其它处理的花蕾中Zn2+、Cu2+、Fe2+含量均显著低于对照。研究表明,在金银花的第一茬花抽枝初期喷施适宜浓度的Phe、Lyr(如1 000mg/g Phe、2 000mg/g Lyr)以及Zn2+、Cu2+(如50mg/L ZnSO4、10mg/L CuSO4)可改善金银花的生长发育,并提高产量和质量。     

An account of some physiological studies in two species of phytophthora

Summary The paper deals with some physiological studies of two typical strains ofPhytophthora palmivora Butl. andP. parasitica Dast. var.macrospora Ashby causing severe fruit rots ofAchras sapota L. andAnona squamosa L. respectively. The effect of temperature on the germination of sporangia had a marked effect. Maximum percentage of indirect germination (by formation of zoospores) occurred at 20° C, whereas direct germination of sporangia (by formation of germ tube) was at 30° C, which further continued upto 37° C. Maximum indirect germination at 20° C shows the favourable cool temperature for the epidemic of the diseases (Fruit rots) in nature. The best substrate (medium) for germination of sporangia was found to be tap water. Next to this was the host decoction or extract. Glucose solution also accelerated sporangial germination. The effect of two dyes viz., Malachite green and crystal violet was also studied in relation to growth and sporulation ofPhytophthora isolates. Their addition to the medium in various fractional dilutions had a profound influence in the rate of growth and sporulation. An interesting observation noted was that growth of the isolates was inversely porportional to the various concentrations of the dyes, under study. An attempt was also made to study the influence of various vitamins. In all, six vitamins were included in the study. Out of these, thiamine and riboflavin were found to be the best sources promoting good growth and sporulation of both the species ofPhytophthora under study.Forms a part of Senior author's M. Sc. (Agric.) Thesis, University of Poona, Poona (India).Respectively, Ex-Junior Research Fellow, I.C.A.R., New Delhi; Professor of Plant Pathology and Principa, College of Agriculture, Junagad (Gujarat); Plant Pathologist, Wheat Rust Research Station, Mahabaleshwar, Poona, India.     

Effects of Dietary Copper (II) Sulfate and Copper Proteinate on Performance and Blood Indexes of Copper Status in Growing Pigs

160 crossbred (Duroc × Landrace ×Yorkshire) gilts averaged 21.25 kg body weight were used to study the effects of dietary copper (II) sulfate (CuSO₄) and copper proteinate (Cu-Pr) on growth performance, plasma Cu concentration, ceruloplasmin activity, and erythrocyte Cu/Zn-superoxide dismutase (SOD) activity. All pigs were allotted to four treatments and fed with basal diets supplemented with 0 (control), 250 mg /kg Cu as CuSO₄, and 50 and 100 mg/kg Cu as Cu-Pr. Growth performance was determined based on two growth phase (phase 1: days 0 to 15, phase 2: days 15 to 30). After 30 days of the treatment, 16 pig blood samples (four per treatment) were collected for indexes of copper status determination. The experimental results showed that compared with control, pigs fed with 250 mg Cu/kg as CuSO₄ and 100 mg Cu/kg as Cu-Pr had higher average daily gain and average daily feed intake in the whole growth phase (d 0 to 30). In addition, 250 mg Cu/kg as CuSO₄ and 100 mg/kg Cu as Cu-Pr enhanced plasma ceruloplasmin activity (P < 0.05), and 100 mg/kg Cu as Cu-Pr increased erythrocyte Cu/Zn-SOD activity (P < 0.01) compared with the control. There was no obvious treatment response on plasma Cu concentration in the present study.     

Characterization of a P-type Copper-Stimulated ATPase from Mouse Liver

Mouse liver microsomes treated with octylthioglucoside (OTG-microsomes) were examined for copper-stimulated ATPase activity. The activity was about 1 μmol Pi/mg protein/hr under optimal conditions [300 mm KCl, 3 mm MgSO₄, 10 mm GSH, 0.5 μm CuSO₄, 3 mm ATP and 50 mm acetate buffer at pH5.0]. A reducing agent such as GSH or dithiothreitol was required for the activity, and removal of Cu⁺ from the reaction mixture by bathocuporinedisulfonate resulted in a complete loss of copper-stimulated ATPase activity. Vanadate inhibited the copper-stimulated ATPase activity. The OTG-microsomes were phosphorylated in a hydroxylamine-sensitive and copper-stimulated way. Iron used instead of copper also stimulated both ATPase and phosphorylation. These results suggest that microsomes from mouse liver contain copper/iron-stimulated P-type ATPase. Received: 2 September 1998/Revised: 16 March 1999     

Nutrition of eidamella deflexa V. effect of varying the concentrations of certain inorganic compounds on growth and pigment elaboration

Summary The effect of addition of varying concentrations of certain inorganic compounds in selected media upon growth and pigment elaboration ofEidamella deflexa (Berk.)Benjamin was studied in submerged culture. Preliminary experiments were performed to establish approximate optimum ranges of certain inorganic compounds. Further investigations in a glycine-sucrose basal medium indicated that the following range of concentrations stimulated growth to the greatest extent: 0.2% MgSO₄·7H₂O, 0.2% K₂HPO₄, 0.25 mg% CuSO₄·5H₂O, 0,0% ZnSO₄·7H₂O and 10.0 mg % FeSO₄·7H₂O. The degree of pigment production did not seem to be affected by different concentrations of these compounds.The effects of additional molybdenum and zinc upon growth and pigmentation were studied in the following media: lactose-peptone, lactose-glycine, maltose-peptone and maltose-glycine. Molybdenum increased pigmentation slightly in maltose-glycine and maltose-peptone media, but inhibited the amount of growth. Molybdenum decreased both growth and pigmentation in the two lactose media. Zinc had little affect on either growth or pigment elaboration in the two maltose media. However, in the lactose-glycine medium, zinc decreased both growth and pigmentation while in lactose-peptone media zinc slightly increased growth and pigmentation.     

Effect of copper excess in environment on soybean root viability and morphology

The effects of increase copper concentrations in medium (10–150 μM CuSO₄) on growth and viability of the roots of two-week-old soybean seedlings (Glycine max L., cv. Dorintsa) were studied. Copper excess suppressed biomass accumulation and linear plant growth; copper affected root growth much stronger than shoot growth. The presence of 10 μM CuSO₄ in medium suppressed accumulation of plant biomass by 40% and the root length by 70%; in the presence of 25 μM CuSO₄, these indices were equal to 80 and 90%, respectively. In the presence of 50 μM CuSO₄, roots ceased to grow but biomass and shoot length still increased slightly. 150 μM CuSO₄ was lethal for plants. The earliest sign of excessive copper toxicity was the accumulation of MDA, indicating activation of membrane lipid peroxidation. A significant increase in MDA content was observed at plant incubation in medium with 10 μM CuSO₄ for 1 h; in this case, the content of copper in the roots increased from 36 ±1.8 (in control) to 48 ± 2.4 μg/g dry wt. The number of dead cells (permeable for the dye Evans Blue) was doubled in the presence of 200 μg/g dry wt within the root; this occurred in 72 h of growth in medium with 10 μM CuSO₄, in 6 h at 25 μM CuSO₄, in 3 h at 50 μM CuSO₄, and 1 h at 150 μM CuSO₄. Toxicity of copper excess was manifested stronger in dividing and elongation cells of the root apex (root meristem and the zone of elongation) than in more basal root regions. Copper excess resulted in the formation of breaks in the surface cell layers of the root tips and affect root morphology. When plant grew in medium with 10 μM CuSO₄, a distance of lateral root formation zone from the root tip decreased markedly, and spherical swellings were formed on the tips of lateral roots. The higher copper concentrations (50 and 150 μM) suppressed completely the development of lateral roots.     

Somatic embryogenesis of agriculturally important lupin species (Lupinus angustifolius,L. albus,L. mutabilis)

Somatic embryos were obtained from immature cotyledons of Lupinus angustifolius, L. albus and L. mutabilis but not from L. luteus. Different kinds of basal media and plant growth regulators in primary and secondary culture were tested. The best induction media were based on B5 and were supplemented with 5 mg I^-1 2,4-D alone or with 0.25 mg I^-1 kinetin. Mature stage somatic embryos were obtained on media containing ABA (0.1–0.5 mg I^-1) and a high NH₄/NO₃ ratio. Embryo germination and plantlet development occurred on MS media supplemented with glutamine or GA₃.     

Antibacterial Activity and Mechanisms of Ethanol Extracts from <i>Scutellaria baicalensis</i> Georgi and <i>Magnolia officinalis</i> against <i>Phytophthora nicotianae</i>

Phytophthora nicotianae causes substantial economic losses in most countries where tobacco is produced. At present, the control of P. nicotianae mainly depends on chemical methods, with considerable environmental and health issues. We investigated the effects of ethanol extracts from Scutellaria baicalensis Georgi (SBG) and Magnolia officinalis (MO). On mycelial growth, sporangium formation, and zoospore release of P. nicotianae. Both extracts inhibited the growth of P. nicotianae, with mycelial growth inhibition rates of 88.92% and 93.92%, respectively, at 40 mg/mL, and EC50 values of 5.39 and 5.74 mg/mL, respectively. The underlying mechanisms were the inhibition of sporangium formation, the reduction of zoospore number, and the destruction of the mycelium structure. At an SBG extract concentration of 16.17 mg/mL, the inhibition rates for sporangia and zoospores were 98.66% and 99.39%, respectively. At an MO extract concentration of 2.87 mg/mL, the production of sporangia and zoospores was completely inhibited. The hyphae treated with the two plant extracts showed different degrees of deformation and damage. Hyphae treated with SBG extract showed adhesion and local swelling, whereas treatment with MO extract resulted in broken hyphae. Mixture of the extracts resulted in a good synergistic effect.