Isolation and identification of plant growth inhibitors as candidate(s) for allelopathic substance(s), from aqueous leachate from mesquite (Prosopis juliflora (Sw.) DC.) leaves

As candidate(s) for allelopathic substance(s), two plant growthinhibitors were isolated from aqueous leachate of leaves of mesquite, whichshowa strong allelopathy, and which were identified as syringin and(–)-lariciresinol by their spectral analyses. Syringin inhibited root andshoot growth of lettuce seedlings at concentrations greater than 0.8M, and root and shoot growth of barnyard grass seedlings atconcentrations greater than 2.7 and 26.9 M, respectively. Onthe other hand, (–)-lariciresinol inhibited root and shoot growth oflettuce seedlings at concentrations greater than 2.8 and 0.8M,and root and shoot growth of barnyard grass seedling at concentrations greaterthan 0.8 and 2.8 M, respectively. The contents of syringin and(–)-lariciresinol in the rhizosphere soil of mesquite were 0.34 and 0.38g/g soil, respectively. These results indicate that syringinand (–)-lariciresinol are allelopathic substance(s), and may play rolesinthe allelopathy of mesquite.     

Copper but not iron limitation increases astaxanthin production by Phaffia rhodozyma in a chemically defined medium

The influence of copper (0–32 M) and iron (0–108 M) on growth and astaxanthin production by Phaffia rhodozyma was studied. Copper below 3.2 M increased the astaxanthin content of the cells (from 220 to 287 g g^–1) but at the expense of a slightly decreased growth (from 11.3 to 10.2 mg ml^–1). In contrast, iron below 1 M decreased both the growth and astaxanthin content of the cells. Using copper limitation instead of toxic respiratory inhibitors to improve astaxanthin production has obvious advantages from the product quality, environmental and process operation points of view.     

Organogenesis versus embryogenesis from long-term suspension cultures of cucumber (Cucumis sativus L.)

Suspension cultures were initiated from leaf explant-derived callus of cucumber,Cucumis sativus cv. Hokus, and maintained under two different conditions; (I) continuously in medium with 5 M 2,4-D + 5 M BA, and (II) alternately three cultures in medium containing 5 M NAA + 5 M BA and one culture in 5 M 2,4-D + 5 M BA. After plating on solid medium with 0.5 M KIN + 0.1 M IAA, suspension aggregates from long-term culture in medium with 2,4-D developed into callus, and subsequently formed somatic embryos. These embryos, however, hardly developed into plants. They showed growth arrest and several structural abnormalities. In contrast, organogenesis took place when suspension aggregates from NAA containing medium were plated on solid medium with 0.5 M KIN + 0.1 M IAA. Numerous adventitious buds were regenerated, which quite normally developed into plants. Sucrose at low concentration of 1% improved plant formation. On the average thirty complete plants were obtained from each ml of suspension. It is discussed why adventitious buds develop into plants so well, whereas somatic embryos are prone to growth arrest and abnormal development.Abbreviations BA 6-benzylaminopurine - KIN kinetin - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid     

The effect of monoterpenes on astaxanthin production by a mutant ofPhaffia rhodozyma

Summary The total pigment and astaxanthin content ofPhaffia rhodozyma increased with increasing concentrations -pinene up to 500 l -pinene/l. Above this concentration the total pigment and astaxanthin content as well as the biomass production decreased. The addition of 500 l -pinene/l increased the total pigment content from 1652 g/g to 2201 g/g and the astaxanthin content from 1554 g/g to 1883 g/g. A sharp decrease in maximum specific growth rate occurred above 150 l -pinene/l.     

Coral growth in high-nutrient,low-pH seawater: a case study of corals cultured at the Waikiki Aquarium,Honolulu, Hawaii

Fifty-seven species of hermatypic corals have been maintained and grown in high-nutrient seawater at the Waikiki Aquarium, Honolulu, Hawaii. In this study we document the chemical conditions of aquarium water in terms of dissolved nutrients and carbon. Aquarium water is characterized by concentrations of inorganic nutrients that are high relative to most natural reef ecosystems: SiO₃ 200 M; PO₄ 0.6 M; NO₃ 5 M; NH₄ 2 M. In contrast, concentrations of organic nutrients are lower than most tropical surface ocean waters: DOP 0.1 M and DON 4 M. The incoming well-water servicing the facility has low pH, crating over-saturation of carbon dioxide. The coral communities in aquaria took up inorganic nutrients and released organic nutrients. Rates of nutrient uptake into aquaria coral communities were similar to nutrient uptake by natural reef communities. Coral growth rates were near the upper rates reported from the field, demonstrating corals can and do flourish in relatively high-nutrient water. The growth of corals does not appear to be inhibited at concentrations of nitrogen up to 5 M. Statements implying that corals can only grow in low nutrient oligotrophic seawater are therefore oversimplifications of processes that govern growth of these organisms. Some basic guidelines are given for maintenance of coral communities in aquaria.     

Developmental aspects of long-term callus culture ofVicia faba L.

Summary Vicia faba callus line (VFS 1), isolated from expiants of immature embryo, grew satisfactorily onMurashige andSkoog complete medium with 1.38 M 2,4-D, or with 0.92 M 2,4-D to which 1.0 M kinetin was added. It also grew well on the B 5 modified medium containing 2.3 M 2,4-D and 25.0 M kinetin. On the last of these media the cultures grew more uniformly and without necrosis. They also showed diminishing variation in polyploidy in favour of diploids and corresponding aneuploids (hypodiploids).After being cultured for nearly three years on MS containing 1.38 M 2,4-D, 8–33% of cultures of VFS 1 were able to regenerate roots when transferred to either MS half strength with 5.37 M NAA, or to a medium without 2,4-D, or else to media with the addition of kinetin only (in various concentrations).     

The contribution of size-fractionated plankton to biomass and primary production of phytoplankton in saline–alkaline ponds

Primary productivity, biomass and chlorophyll-a of size fractionated phytoplankton (<0.22 m, <3 m, <8 m, <10 m, <40 m, <64 m, <112 m and <200 m) were estimated in 6 ponds and 5 experimental enclosures. The results showed that the planktonic algae less than 10 m are important in the biomass and production of phytoplankton in saline–alkaline ponds. The production of size fractionated phytoplankton corresponding to <112 m, <10 m and <3 m in saline–alkaline ponds were 10.5 ± 6.6 , 8.6 ± 5.4 and 0.33 ± 0.1 mgC l^–1 d^–1, respectively. Mean community respiration rate was 1.80 ± 0.73, 1.69 ± 0.90 and 1.38 ± 1.12 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) were 1.61, 8.30 and 0.33 mgC l^–1 d^–1, respectively. The ratio of those to the total phytoplankton production was 15%, 79% and 3%, respectively. The mean respiration rate of the different size groups was 0.11, 0.31 and 1.38 mgC l^–1 d^–1; the ratio of those to total respiration of phytoplankton was 6%, 17% and 77%, respectively. The production of size-fractionated phytoplankton corresponding to <200 m, <10 m and <3 m in enclosures was 2.19 ± 1.63, 2.08 ± 1.75 and 0.22 ± 0.08 mgC l^–1 d^-1, respectively. Mean community respiration rates were 1.25 ± 1.55, 1.17 ± 1.42 and 0.47 ± 0.32 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton was 0.11, 1.86 and 0.22 mgC l^–1 d^–1, respectively. The ratio of those to the total production of phytoplankton was 5%, 85% and 10%, respectively. The mean respiration rate of different size groups were 0.08, 0.72 and 0.46 mgC l^–1 d^–1, the ratio of those to total respiration of phytoplankton was 6%, 57% and 37%, respectively. The concentrations of chlorophyll-a of the phytoplankton in the corresponding size of micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) plankton in the experimental ponds were 19.3, 98.2 and 11. 9 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 15%, 76% and 9%, respectively. The concentrations of chlorophyll-a of phytoplankton micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton in enclosures were 1.7, 34.3 and 3.0 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 4%, 88% and 8%, respectively.     

Callus growth and plant regeneration in diverse cultivars of cucumber (Cucumis sativus L.)

The growth and differentiation of callus tissues derived from cotyledons of ten cultivars ofCucumis sativus L. were investigated. Cotyledonary explants from all ten cultivars formed callus tissue on Murashige and Skoog (MS) medium supplemented with 0.5 M 2,4-dichlorophenoxyacetic acid and 5 M 6-benzylaminopurine. Fresh weight of the callus tissues averaged 1 to 8 g per flask after five weeks of culture. Shoot development was achieved in three cultivars, Hukchinju, Manchoonchoungjang and Seoul, on MS medium supplemented with 0.5 M -naphthaleneacetic acid and 5 M 6-benzylaminopurine. Reducing the 6-benzylaminopurine concentration to 0.01 M resulted in root formation on callus tissues and on shoots transferred to this medium. All cultivars gave the same response in tests of root formation, but shoot regeneration from callus culture of cucumber cotyledons was dependent on genotype with cultivar Manchoonchoungjang exhibiting the best shoot differentiation capability among the genotypes examined. Examination of mitotic metaphase from the regenerants revealed that all were tetraploid.     

Development of an L6 myoblast in vitro model of moniliformin toxicosis

L6 myoblasts were used as an in vitro model to investigate the role of moniliformin and its interaction with monensin in turkey knockdown syndrome and sudden death syndromes in poultry. Cell viability and microscopic and ultrastructural alterations noted in L6 myoblasts cultured in the presence of moniliformin (0.0–0.3 g/l) were compared to those observed in parallel cultures also containing one of the following compounds: selenium (0–0.004 ng/l), thiamine (0–0.3 g/l), or pyruvate (0–0.46 g/l). Marked dilation of the RER, membranous whorls, glycogen deposition, membrane-bound cytoplasmic inclusions and necrosis were observed in myoblasts exposed to 0.03/2-0.30 g moniliformin/l medium. Supplementation of medium with thiamine and pyruvate, or selenium, provided significant protection to cells exposed to 0.0–0.3 g/l or 0.0–0.15 g moniliformin/l, respectively. Dose-dependent differences in protein and ATP production were not detected. Myoblasts grown in medium containing 0–0.15 g moniliformin/l and 7.5–50.0 M A23187, beauvericin or monensin had degrees of cytotoxicity similar to parallel cultures receiving only an ionophore. L6 myoblasts were a useful model of moniliformin toxicosis. The findings of this study suggest cytotoxicity due to moniliformin in L6 myoblasts may be due in part to oxidative damage and altered pyruvate metabolism, and that moniliformin does not predispose myoblasts to ionophore toxicosis. This study supports the results of in vivo investigations in poultry that moniliformin and monensin do not act synergistically to induce knockdown or monensin toxicosis.     

In vitro meristem cloning of Eucalyptus tereticornis Sm.

Rapid multiplication of axillary meristems and direct shoot development occurred from nodal explants of mature Eucalyptus tereticornis Sm. with 5.3 M NAA, 1.1 M IAA and 4.4 M BA in Murashige-Skoog medium. Repeated subcultures of the second generation shoot cultures into low cytokinin-auxin containing media (0.44–0.88 M BA+0.1 M NAA) yielded axillary microshoots in large numbers. Half-strength MS liquid medium with 4.9 M IBA, 5.5 M IAA and 5.3 M NAA for four days, half-strength semi-solid hormonefree MS medium with charcoal, and MS liquid medium without charcoal and hormones, in sequence, induced rooting of shoots in the dark. This system is suitable for the mass propagation of this difficult-to-root eucalypt.Abbreviations BA 6-benzyladenine - IAA indole-3-acetic acid - IBA -indole-3-butyric acid - 2-iP isopentyl adenine - Kn kinetin - MS Murashige-Skoog - NAA -naphthalene acetic acid - PVP polyvinylpyrrolidone     

Pre-epithelial mucus layer in the colon of conventional and germ-free rats

Summary The pre-epithelial mucus layer (PML) and epithelial mucins were studied by mucin histochemistry in 10m-thick celloidinstabilized cryostat sections in the proximal and distal colon of conventional and germ-free rats aged 120 and 350 days. No continuous PML was found in the proximal colon. A continuous mucus blanket, of fairly homogenous thickness, was observed in the distal colon, where the PML-thickness was 40±24 m at 120 days of age and 44±22 at 350 days of age in conventional rats, and 25±17m (120 days) and 22±10 (350 days) in germ-free rats. The stainability of the PML by periodic acid-Schiff and Alcian Blue at pH 2.5 and 1.0 was stronger in conventional rats than in germ-free rats, indicating higher concentrations of mucosubstances and of acid and sulphated mucins, respectively. The PML of the conventional rat distal colon showed a stratified structure of up to eight sublayers. In the distal colon of germ-free rats, the whole gut wall thickness was reduced 47% compared to the conventional rat (germ-free: 185±73m, conventional: 350±115m). No stratification of the PML was observed. The presence of intestinal microflora obviously had a strong influence on the thickness, compactness, mucin content, mucin composition and structure of the pre-epithelial mucus layer.     

Determination of copper, manganese and zinc in human liver

Autopsied liver tissue samples collected from 42 males and 31 females were analyzed for copper, manganese and zinc using atomic absorption spectrometry (AAS). With the exception of two liver samples for which the copper levels were determined to be 74.8 and 104.0 g/g (dry weight), hepatic copper concentrations were found to range from 1.7 to 32.4 g/g with a mean concentration of 14.2 g/g and standard deviation of 7.0 g/g. Manganese concentrations (with the exception of one sample having 12.9 g/g) ranged from 0.22 to 4.6 g/g with a mean of 2.26 ± 1.00 g/g. Hepatic zinc levels averaged 118.3 ± 44.4 g/g and ranged from 38.5 to 231.3 g/g. There were no apparent trends for the levels of any metals versus age nor were there any differences in average hepatic metal concentrations for males and females. © Rapid Science 1998.     

Adventitious shoot formation and plant regeneration from tissues of tomatillo (Physalis ixocarpa Brot.)

Cultured hypocotyl explants of tomatillo (Physalis ixocarpa Brot.), were evaluated with regard to their morphogenic responses to combinations of benzyladenine (BA, 0–5 M) with either naphthaleneacetic acid (NAA, 0–50 M) or 2,4-dichlorophenoxyacetic acid (2,4-D, 0–50 M). The induction of shoots or roots was dependent on the cytokinin/auxin combination.Hypocotyl explants failed to form shoots when they were grown on media containing either a cytokinin or an auxin alone. The highest frequency of shoot formation was observed on media containing 12.5–25 M BA and 5 M NAA. Likewise the highest frequency of root formation was observed on media supplemented with 1 M BA and 1 M NAA. Complete plants were regenerated and transferred to soil, where they reached maturity.     

Purine and pyrimidine base and nucleoside concentrations in human cerebrospinal fluid and plasma

Purine and pyrimidine base and nucleoside levels were determined in adult human lumbar (CSF) and plasma by reversed-phase high performance liquid chromatography (HPLC). Guanine, thymine, cytosine and uracil were not detectable (<0.1 M) in human CSF or plasma. Adenine was detectable in plasma (0.3 M) but was not found in CSF (<0.2 M). Hypoxanthine and xanthine levels in CSF were each approximately 2.5 M. Plasma levels of hypoxanthine and xanthine were considerably lower (0.4–0.6 M). Purine and pyrimidine ribouncleosides in human CSF were less than or equal to 0.2 M with the exception of uridine which was present at concentrations of 2–3 M. Although low concentrations of thymidine and deoxyuridine (0.2 M) were present in human plasma, purine and pyrimidine deoxyribonucleosides were less than 0.1 M in human lumbar CSF.     

<Emphasis Type="Italic">In vitro</Emphasis> induction of polyploidy in annatto (<Emphasis Type="Italic">Bixa orellana</Emphasis>)

The present work aims to establish a protocol for in vitro polyploidization using hypocotyl segments or cotyledonary nodes from in vitro grown annatto seedlings. The culture medium used to induce polyploidization was supplemented with MS salts, B5 vitamin complex, 100 mg l^– myo-inositol, 3% (w/v) sucrose, 2.28 M ZEA and 0.30 M IAA (hypocotyl segments) or 4.56 M ZEA (cotyledonary nodes), 0.8% (w/v) agar, and different concentrations of microtubule depolymerising agents, namely colchicine (0, 25, 250 and 1250 M) and oryzalin (0, 5, 15 and 30 M). To determine the optimum duration of either colchicine or oryzalin treatment for the induction of tetraploids, explants were treated for 15 or 30 days on regeneration medium. High frequencies of polyploidy in regenerated shoots from cotyledonary nodes were achieved in culture medium supplemented with 15 M oryzalin, for 15 days. Ploidy determination was based on chromosome counting in metaphasic cells from apical buds, and in the number of pairs of heterochromatic markers on the biggest chromosome, as visualized in interphasic nuclei, detection being easier in the latter. Among the characteristics evaluated, the measurements based on stomata length, width, area and frequency enabled greater discrimination between diploid and polyploid regenerated shoots.     

Micropropagation of Frazinus angustifolia from mature and juvenile plant material

Micropropagation of Fraxinus angustifolia Vahl has been successfully achieved both from mature and juvenile plant material using shoot tip and nodal explants. Several basal media supplemented with benzyladenine (BA) and indolebutyric acid (IBA) were tested for shoot proliferation. The most new explants per mature explant (5.3) was obtained on DKW medium plus 4.4 M BA+0.98 M IBA. The most new explants per juvenile explant (5.6) was produced on QL medium plus 8.9 M BA+0.49 M IBA. Rooting was achieved on WPM supplemented with 0.98–4.9 M IBA. Rooted plantlets were transferred to soil and acclimatized with 85% survival.Abbreviations BA benzyladenine - IBA indolebutyric acid - NAA 1-naphthaleneacetic acid     

Regional and subcellular distribution of taurine-synthesizing enzymes in the rat central nervous system

The distribution of cysteine oxidase (CO) and cysteine sulfinate decarboxylase (CSD) was examined in 12 regions of the rat central nervous system (CNS). The distribution of CO activity, expressed as mol of cysteine sulfinate formed per h per g, was the following: hypothalamus, superior and inferior colliculi, 94–99 mol/h/g; olfactory bulbs, cerebral cortex, striatum, and hippocampus, 44–51 mol/h/g; cerebellum, 71 mol/h/g; pons-medula and spinal cord, 94 and 60 mol/h/g, respectively. The distribution of CSD activity expressed as mol of cysteine sulfinate decarboxylated per h per g was the following: hypothalamus and colliculi, 14–21 mol/h/g; olfactory bulbs, cerebral cortex, striatum, hippocampus, and cerebellum, 8–13 mol/h/g; pons-medulla, 7.3; and spinal cord, 3.6 mol/h/g. No CSD activity was detected in sciatic nerve. The subcellular distribution of CO and CSD activities was studied in hypothalamus, colliculi, and cerebral cortex. CO activity was localized in synaptosomes, mitochondria, and microsomes. CSD was primarily confined to the crude mitochondrial fraction and after subfraction, recovered mainly in the synaptosomal fraction.     

Susceptibility of clinical isolates of yeasts to anti-fungal agents

The antimicrobial activity of amphotericin B, 5-fluorocytosine, nystatin, clotrimazole and miconazole were compared in vitro against 244 strains of yeasts that had been isolated from clinical specimens. The yeasts used in this study included 20 species of Candida, Cryptococcus, Saccharomyces Geotrichum, Rhodotorula, Torulopsis and Trichosporon. The majority of the strains (78%) had an MIC of 0.5 g/ml for amphotericin B, 81% an MIC of 1 g/ml for 5-fluorocytosine, 99% 8 g/ml for nystatin, 91%, 8.0 g/ml for clotrimazole and 98% had an MIC of 4.0 for miconazole. Of the anti-fungal agents tested, 5-fluorocytosine and nystatin were found to have the greatest antifungal activity.     

Silver nitrate and aminoethoxyvinylglycine affect <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated apple transformation

In Fuji, the production of ethylene was increased with the addition of AgNO₃ and inhibited with the addition of 10 M aminoethoxyvinylglycine (AVG). The addition of 80 M AgNO₃ to transformed explants of Fuji cultured on selection medium resulted in increased ethylene production (20 l l^–1) at 3 weeks. Under examining the effect of AgNO₃ in Fuji, the 40 M AgNO₃ showed with higher 33.8% and 6.5% in the efficiency of regeneration and transformation. However, ethylene production in Gala explants treated with 10M AgNO₃ (3 l l^–1) decreased after 2 weeks compared with the control (5 l l^–1). Although the regeneration efficiency of Gala with 10 M AgNO₃ was higher (41.1%) than the control (20.1%), there was no significant difference in the transformation efficiency at the same concentration. Shoot regeneration of Fuji and Gala was completely inhibited with 10 M AVG. These results suggest that the addition of AgNO₃ affects the efficiency of Agrobacterium-mediated gene transfer in Fuji.Eun Soo Seong, Ill Min Chung- These two Authors Contributed equally to this work     

Effects of retinoids on porcine thyrocytes under different culture conditions

The purpose of the paper was to study the morphological effects of retinoids on non-transformed cells such as thyrocytes. The formation of follicles was studied in primary cultures of porcine thyrocytes by adding retinol and thyroid stimulating hormone (TSH) to cells grown in the absence of TSH to form monolayers. The proliferation and apoptosis of thyrocytes were studied in cells both grown adherent to plastic surfaces and in suspension. Standard medium with traces of retinol and the same medium without retinol were used. Retinol alone was added to thyrocytes grown in the absence of TSH (TSH culture) or both retinol and TSH were added to cultures after stimulation with TSH (TSH culture). The concentration was varied from 0 to 80M for retinol and from 0 to 13M for retinoic acid. At a concentration of 13M, the effect of retinol was similar to that of retinoic acid. At concentrations higher than 40M, retinol reduced the formation of thyroglobulin-immunoreactive follicles, whereas up to 13M retinoic acid had no obvious influence on follicle formation. The retinoids induced apoptosis under all experimental conditions. In contrast, a significant decrease in proliferation and in the formation of thyroglobulin-immunoreactive follicles was observed only in adherent cells cultured in customary medium. The decrease in functional follicles after treatment with retinol suggests a de-differentiating effect of retinoids on normal thyrocytes and is in contrast with the differentiating effect of retinoids observed in cancer cells.