<Emphasis Type="Italic">In vitro</Emphasis> propagation of the genus <Emphasis Type="Italic">Clivia</Emphasis>

We have developed a protocol for the in vitro propagation of the genus Clivia. Shoots were regenerated when fragments of the peduncle-pedicel junction (PP junction) from young inflorescences were used as explants. The optimal media for PP junction were Murashige and Skoog (MS)-based medium containing 10 M of 6-benzyladenine (BA) and 10 M of 2,4-dichlorophenoxyacetic acid (2,4-D) or MS supplemented with 5 M BA, 10 M -naphthaleneacetic acid (NAA), 250 mg l^-1 glutamine and 500 mg l^–1 casein hydrolysate and their usage depended on the breeding lines. Multiplication from initiations and in vitro seedlings was the best when the explants were cut longitudinally through the meristem and placed on MS plus 44 M BA. Plantlets were transferred on to hormone -free MS medium with charcoal for rooting.     

Influence of inorganic microelements on the production of camptothecin with suspension cultures of <Emphasis Type="Italic">Camptotheca acuminata</Emphasis>

The effects of eight microelements (I^–, BO₃ ^3–, MoO₄ ^2–, Co²⁺, Cu²⁺, Mn²⁺, Fe²⁺, Zn²⁺) on the biosynthesis of camptothecin and the growth of suspension cultures of Camptotheca acuminata were studied. The increase of I^– to 25 M l^–1, Cu²⁺ to 1 M l^–1, Co²⁺ to 2 M l^–1 and MoO₄ ^2– to 10 M l^–1 in Murashige and Skoog (MS) medium resulted in 1.66, 2.84, 2.53 and 2.04 times higher of camptothecin yield than that in standard MS medium respectively. Combined treatment of I^– (25 M l^–1), Cu²⁺ (1 M l^–1), Co²⁺ (2 M l^–1) and MoO₄ ^2– (10 M l^–1) lead to improve cell dry weight, camptothecin content, and camptothecin yield to 30.56 g l^–1, 0.0299%, and 9.15 mg l^–1, respectively, which were 20.2, 208.9 and 273.8% increment respectively when compared with those of control.     

Seasonal and spatial variation of woody tissue respiration in a <Emphasis Type="Italic">Pinus cembra</Emphasis> tree at the alpine timberline in the central Austrian Alps

Total stem, branch, twig, and coarse root respiration (R_t) of an adult Pinus cembra tree at the alpine timberline was measured continuously at ten positions from 7 October 2001 to 21 January 2003 with an automated multiplexing gas exchange system. There was a significant spatial variability in woody tissue respiration when expressed per unit surface area or per unit sapwood volume. Surface area related maintenance (R_m) respiration at 0°C ranged between 0.109 and 0.643 mol m^–2 s^–1 and there was no clear trend with respect to tissue type and diameter. Sapwood volume based R_m at 0°C by contrast, varied between 2.5 mol m^–3 s^–1 in the stem and 193.2 mol m^–3 s^–1 in thin twigs in the upper crown. Estimated Q₁₀ values ranged from 1.7 to 3.1. These Q₁₀ values were used along with R_m at 0°C and annual woody tissue temperature records to predict annual total R_m. Annual total R_m accounted for 73±6% of annual R_t in 2002.     

Evidence for the existence of PAH-quinone reductase and catechol-<Emphasis Type="Italic">O</Emphasis>-methyltransferase in <Emphasis Type="Italic">Mycobacterium vanbaalenii</Emphasis> PYR-1

Polycyclic aromatic hydrocarbon (PAH) quinone reductase (PQR) and catechol-O-methyltransferase (COMT), from the PAH-degrading Mycobacterium vanbaalenii PYR-1, were demonstrated to be constitutive enzymes located in the soluble fraction of cell extracts. PQR activities for the reduction of 9,10-phenanthrenequinone and 4,5-pyrene- quinone were 1.40±0.13 and 0.12±0.01 mol min^–1 mg-protein^–1, respectively. The exogenous catechols alizarin, anthrarobin, 2,3-dihydroxynaphthalene and esculetin inhibited PQR activity. Anthrarobin (100 M) and esculetin (100 M) inhibited 4,5-pyrenequinone reduction by 64–92%. COMT was involved in the O-methylation of 1,2-dihydroxyphenanthrene to form 1-methoxy-2-hydroxyphenanthrene and 1,2-dimethoxyphenanthrene. Both pyrene and 1-hydroxypyrene were metabolized by M. vanbaalenii PYR-1 to form 1-methoxypyrene, 1-methoxy-2-hydroxypyrene, 1-hydroxy-2-methoxypyrene and 1,2-dimethoxypyrene. Among the catechols tested, anthrarobin showed the highest COMT activity (1.06±0.04 nmol/30 min^–1 mg-protein^–1). These results suggest that the PQR and COMT activities of M. vanbaalenii PYR-1 may play an important role in the detoxification of PAH catechols.     

Cell volume distribution dynamics of <Emphasis Type="Italic">Chlorella</Emphasis><Emphasis Type="Italic">vulgaris</Emphasis> Beij. in batch cultures under continuous light

Cell volume distribution in Chlorella vulgaris cultures coming out of senescence was measured by flow cytometry every 6 h for 114 h in a full-factorial experiment with initial nitrate (420–4200 g NO₃-N l^–1), phosphate (9–186 g PO₄-P l^–1), and continuous light (50–330 E m^–2 s^–1) as treatments. The maxima in median and median absolute deviation (MAD) of cell volume were achieved within 6 h of each other and their timing was not affected by any treatment. Population specific growth rate during the first 66 h calculated from volume distribution changes was significantly affected by light treatment only (p=0.002).Revisions requested 4 November 2004; Revisions received 17 January 2005     

<Emphasis Type="Italic">In vitro</Emphasis> regeneration of the medicinal woody plant <Emphasis Type="Italic">Phellodendron amurense</Emphasis> Rupr. through excised leaves

Shoot organogenesis and plant establishment has been achieved for Phellodendron amurense Rupr. from excised leaf explants. Young leaf explants were collected from in vitro established shoot cultures and used for the induction of direct shoot regeneration, callus and subsequent differentiation into shoots on MS medium. Direct shoot regeneration was achieved by culturing 1 cm² sections of about 10-day-old leaves on MS medium enriched with 4.4 M BAP and 1.0 M NAA after 4 weeks of culture. The leaf explants produced callus from their cut margins within 3 weeks of incubation on medium supplemented with 2.0 M TDZ and 4.0 M 2,4-D or 4.0 M NAA. The maximum number of adventitious shoots was regenerated from the leaf-derived callus within 4 weeks of culture on MS medium containing 1.5 M BAP and 1.0 M NAA. The highest rate of shoot multiplication was achieved at the third subculture, and more than 65 shoots were produced per callus clump. For rooting, the in vitro proliferated and elongated shoots were excised into 2–4 cm long microcuttings, which were planted individually on a root-induction MS medium containing 2.0 M IBA. Within 3 weeks of transfer to the rooting medium, all the cultured microcuttings produced 2–6 roots. The in vitro regenerated plantlets were transferred to Kanuma soil, and the survival rate ex vitro was 90%.     

Effects of <Emphasis Type="Italic">in vitro</Emphasis>rooting environments and irradiance on growth and photosynthesis of strawberry plantlets during acclimatization

Strawberry (Fragaria ananassaDuch. cv. Fengxiang) plantlets were cultured under two in vitroenvironments for rooting, and then acclimatized under two ex vitroirradiance conditions. At the end of rooting stage plant height, fresh weight and specific leaf area of T1-plants grown under high sucrose concentration (3 sucrose), low photosynthetic photon flux density (30 mol m^–2 s^–1) and normal CO₂ concentration (350–400 l l^–1) were significantly higher than those of T2-plantlets grown under low sucrose concentration (0.5), high photosynthetic photon flux density (90 mol m^–2 s^–1) and elevated CO₂ concentration (700–800 l l^–1). But T2-plantlets had higher net photosynthetic rate (Pn), effective photochemical quantum yield of PSII (_PSII), effective photosynthetic electron transport rate (ETR), photochemical quenching (q_P) and ratio of chlorophyll fluorescence yield decrease (Rfd). After transfer, higher irradiance obviously promoted the growth of plantlets and was beneficial for the development of photosynthetic functions during acclimatization. T2-plantlets had higher fresh weight, leaf area, _PSII and ETR under higher ex vitroirradiance condition.     

Purification and characterization of an<Emphasis Type="Italic"> N</Emphasis>-acetylglucosaminidase produced by a<Emphasis Type="Italic"> Trichoderma harzianum</Emphasis> strain which controls<Emphasis Type="Italic"> Crinipellis perniciosa</Emphasis>

Isolate 1051 of Trichoderma harzianum, a mycoparasitic fungus, was found to impair development of the phytopathogen, Crinipellis perniciosa, in the field. This Trichoderma strain growing in liquid medium containing chitin produced substantial amounts of chitinases. The N-acetylglucosaminidase present in the culture-supernatant was purified to homogeneity by gel filtration and hydrophobic interaction chromatography, as demonstrated by SDS-PAGE analysis. The enzyme had a molecular mass of 36 kDa and hydrolyzed the synthetic substrate -nitrophenyl-N-acetylglucosaminide (NGlcNAc) with Michaelis–Menten kinetics. Maximal activities were determined at pH 4.0 and a temperature range of 50–60°C. K _m and V _max values for NGlcNAc hydrolysis were 8.06 moles ml^–1 and 3.36 moles ml^–1 min^–1, respectively, at pH 6.0 and 37°C. The enzyme was very sensitive to Fe³⁺, Mn²⁺ and Co²⁺ ions, but less sensitive to Zn²⁺, Al³⁺, Cu²⁺ and Ca²⁺. Glucose at a final concentration of 1 mM inhibited 65% of the original activity of the purified enzyme. Determination of the product (reducing sugar) of hydrolysis of C. perniciosa mycelium and scanning electron microscopic analysis revealed that the N-acetylglucosaminidase hydrolyses the C. perniciosa cell wall.     

Callus induction and <Emphasis Type="Italic">de novo</Emphasis> regeneration from callus in Guar (<Emphasis Type="Italic">Cyamopsis tetragonoloba</Emphasis>)

Guar (Cyamopsis tetragonoloba L. Taub) is a drought tolerant and multipurpose grain legume cash crop grown primarily under rainfed conditions in several countries. The effect of various growth regulators and their combinations on a variety of explants, namely the embryo, cotyledons, cotyledonary nodes, shoot tip and hypocotyle, has been studied and an efficient system for callus induction and regeneration from callus has been developed. It was established that Murashige and Skoogs culture medium containing 2,4-dichlorophenoxyacetic acid (10.0M) in combination with 6-benzylaminopurine (5.0M) with embryo or cotyledon explants is most suitable for induction of green and friable morphogenic callus, with a range of 82.5–95% of cultured explants responding to callus induction. Efficient de novo shoot regeneration was achieved by culturing the callus obtained on this medium on Murashige and Skoogs medium containing 1-naphthlenacetic acid (13.0M) in combination with 6-benzylaminopurine (5.0M) with a range of 82.1–88.4% of callus clumps producing 20–25 shoots. In vitro rooting of cultured shoots was obtained on half-salt concentration of Murashige and Skoogs culture medium supplied with indole-3-butyric acid (5.0M) on which 82–90% of cultured shoots produced healthy roots. The in vitro regenerated plants were grown to pod setting and subsequent maturity under greenhouse conditions.     

Thidiazuron Promotes <Emphasis Type="Italic">In Vitro</Emphasis> Plant Regeneration of <Emphasis Type="Italic">Arachis correntina</Emphasis> (<Emphasis Type="Italic">Leguminosae</Emphasis>) via Organogenesis

Arachis correntina (Burkart) Krapov. & W.C. Gregory is a herbaceous perennial leguminous plant growing in the Northeast of the Province Corrientes, Argentina. It is important as forage. The development of new A. correntina cultivars with improved traits could be facilitated through the application of biotechnological strategies. The purpose of this study was to investigate the plant regeneration potential of mature leaves of A. correntina in tissue culture. Buds were induced from both petiole and laminae on 0.7% agar-solidified medium containing 3% sucrose, salts and vitamins from Murashige and Skoog (MS) supplemented with 0.5–25 M thidiazuron (TDZ). Shoot induction was achieved by transference of calli with buds to MS supplemented with 5 M TDZ. Fifty-four percent of the regenerated shoot rooted on MS + 5 M naphthaleneacetic acid. Histological studies revealed that shoots regenerated via organogenesis.     

Photosynthetic light-use by three bromeliads originating from shaded sites (<Emphasis Type="Italic">Ananas ananassoides,Ananas comosus</Emphasis> cv. Panare) and exposed sites (<Emphasis Type="Italic">Pitcairnia pruinosa</Emphasis>) in the medium Orinoco basin,Venezuela

Three Bromeliaceae species of the medium Orinoco basin, Venezuela, were compared in their light-use characteristics. The bromeliads studied were two species of pineapple, i.e. the wild species Ananas ananassoides originating from the floor of covered moist forest, and the primitive cultivar Panare of Ananas comosus mostly cultivated in semi-shaded palm swamps, and Pitcairnia pruinosa, a species abundant in highly sun exposed sites on rock outcrops. Ananas species are Crassulacean acid metabolism (CAM) plants, P. pruinosa is C₃ plant. Plants were grown at low daily irradiance (LL = 1.3 mol m^–2 d^–1 corresponding to an incident irradiance of 30 mol m^–2 s^–1) and at high irradiance (HL = 14.7 mol m^–2 d^–1 or 340 mol m^–2 s^–1), and CO₂ and H₂O-vapour gas exchange and photochemical (q_P) and non-photochemical quenching (q_NP) of chlorophyll a fluorescence of photosystem 2 (PS2) were measured after transfer to LL, medium irradiance (ML = 4.1 mol m^–2 d^–1 or 95 mol m^–2 s^–1) and HL. All plants showed flexible light-use, and q_P was kept high under all conditions. LL-grown plants of Ananas showed particularly high rates of CAM-photosynthesis when transferred to HL and were not photoinhibited.     

A lyophilized aqueous extract of<Emphasis Type="Italic"> Maytenus ilicifolia</Emphasis> leaves inhibits histamine-mediated acid secretion in isolated frog gastric mucosa

Lyophilized aqueous extract of Maytenus ilicifolia leaves (LAEMIL) is commonly used in Brazilian folk medicine in the treatment of dyspepsia as well as gastric ulcers. We have investigated the effect and the possible mechanism of action of the LAEMIL on acid secretion in isolated frog gastric mucosa incubated in an Ussing chamber. It was observed that LAEMIL (7–28 mg%) as well as cimetidine (125–4,000 M), a well-known histamine H₂ receptor antagonist, decreased basal acid secretion in a concentration-dependent manner. Similarly to cimetidine (190 M), LAEMIL (21 mg%) also inhibited gastric acid secretion induced by increasing concentrations of histamine (50–800 M). The EC₅₀ values for histamine alone and histamine in the presence of LAEMIL or cimetidine were 94.6 M (71.1–125.9 M), 244.9 M (209.4–286.4 M) and 142.2 M (23.6–855.0 M), respectively. LAEMIL, histamine and cimetidine were effective on acid secretion only when added to the serosal surface of the mucosa. Furthermore, simultaneous addition of LAEMIL and cimetidine at concentrations, per se, ineffective, caused a 16% reduction in the basal acid secretion [from 8.3±0.3 to 6.9±0.2 Eq g^–1 (15 min)^–1, n=4]. Although effects such as inhibition of histamine biosynthesis and/or histamine release can not be ruled out, our data suggest that LAEMIL, like cimetidine, reduces acid secretion in the isolated frog gastric mucosa by antagonising histamine H₂ receptors.Abbreviations LAEMIL Lyophilized aqueous extract of Maytenus ilicifolia leaves - Hist Histamine - Cim Cimetidine     

Nitrate and phosphate removal by<Emphasis Type="Italic"> Spirulina platensis</Emphasis>

The cyanobacterium Spirulina platensis was used to verify the possibility of employing microalgal biomass to reduce the contents of nitrate and phosphate in wastewaters. Batch tests were carried out in 0.5 dm³ Erlenmeyer flasks under conditions of light limitation (40 mol quanta m^–2 s^–1) at a starting biomass level of 0.50 g/dm³ and varying temperature in the range 23–40°C. In this way, the best temperature for the growth of this microalga (30°C) was determined and the related thermodynamic parameters were estimated. All removed nitrate was used for biomass growth (biotic removal), whereas phosphate appeared to be removed mainly by chemical precipitation (abiotic removal). The best results in terms of specific and volumetric growth rates ( =0.044 day^–1, Q _x =33.2 mg dm^–3 day^–1) as well as volumetric rate and final yield of nitrogen removal ( =3.26 mg dm^–3 day^–1, =0.739) were obtained at 30°C, whereas phosphorus was more effectively removed at a lower temperature. In order to simulate full-scale studies, batch tests of nitrate and phosphate removal were also performed in 5.0 dm³ vessels (mini-ponds) at the optimum temperature (30°C) but increasing the photon fluence rate to 80 mol quanta m^–2 s^–1 and varying the initial biomass concentration from 0.25 to 0.86 g/dm³. These additional tests demonstrated that an increase in the inoculum level up to 0.75 g/dm³ enhanced both NO₃ ^– and PO₄ ^3– removal, confirming a strict dependence of these processes on biomass activity. In addition, the larger surface area of the ponds and the higher light intensity improved removal yields and kinetics compared to the flasks, particularly concerning phosphorus removal ( =0.032–0.050 day^–1, Q _x =34.7–42.4 mg dm^–3 day^–1, =3.24–4.06 mg dm^–3 day^–1, =0.750–0.879, =0.312–0.623 mg dm^–3 day^–1, and =0.224–0.440).     

Phytochelatin synthesis and cadmium localization in wild type of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

AlthoughArabidopsis thaliana is known as a model plant, in molecular studies, as well as heavy metal tolerance of higher plants, there have been no detailed studies of its cadmium accumulation, tolerance and cellular distribution in a wild type of this species. In hydroponic experiments the wild type of A. thaliana (L.) Heynh cv. Columbia plants grew at cadmium concentrations varying from 5 to 100 M with phytotoxicity symptoms depending on the concentration and time of application. The concentration of cadmium in roots and shoots increased from 0.28 and 0.08 mg g^–1 d.wt at 5 M Cd treatment after 7 days to 0.82 and 0.85 mg g^–1 d.wt at 100 M Cd treatment after 14 days, respectively. Most of the cadmium (69–88% of its total pool) was found in shoot. Cd application induced the biosynthesis of phytochelatins (PCs) in root and shoot tissues. Studies with buthionine sulfoximine [BSO, specific inhibitor of glutathione (GSH) synthesis] supported the presence of Cd–phytochelatin complexes and their role in Cd detoxification and tolerance in wild type of A. thaliana. Cellular distribution of cadmium was examined using energy-dispersive X-ray micro-analysis. Particularly interesting was the observation of cadmium localized in the root pericycle.     

<Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>-mediated transformation of blueberry (<Emphasis Type="Italic">Vaccinium corymbosum</Emphasis> L.)

Transient expression studies using blueberry leaf explants and monitored by -glucuronidase (GUS) assays indicated Agrobacterium tumefaciens strain EHA105 was more effective than LBA4404 or GV3101; and the use of acetosyringone (AS) at 100 M for inoculation and 6 days co-cultivation was optimum compared to 2, 4, 8, 10 or 12 days. Subsequently, explants of the cultivars Aurora, Bluecrop, Brigitta, and Legacy were inoculated with strain EHA105 containing the binary vector pBISN1 with the neomycin phosphotransferase gene (nptII) and an intron-interrupted GUS gene directed by the chimeric super promoter (Aocs)₃AmasPmas. Co-cultivation was for 6 days on modified woody plant medium (WPM) plus 100 M AS. Explants were then placed on modified WPM supplemented with 1.0 mg l^–1 thidiazuron, 0.5 mg l^–1 -naphthaleneacetic, 10 mg l^–1 kanamycin (Km), and 250 mg l^–1 cefotaxime. Selection for Km-resistant shoots was carried out in the dark for 2 weeks followed by culture in the light at 30 E m^–2 s^–1 at 25°C. After 12 weeks, selected shoots that were both Km resistant and GUS positive were obtained from 15.3% of the inoculated leaf explants of cultivar Aurora. Sixty-eight independent clones derived from such shoots all tested positive by the polymerase chain reaction using a nptII primer. Eight of eight among these 68 clones tested positive by Southern hybridization using a gusA gene derived probe. The transformation protocol also yielded Km-resistant, GUS-positive shoots that were also PCR positive at frequencies of 5.0% for Bluecrop, 10.0% for Brigitta and 5.6% for Legacy.     

Development of a shoot regeneration protocol for genetic transformation in <Emphasis Type="Italic">Pelargonium zonale</Emphasis> and <Emphasis Type="Italic">Pelargonium peltatum</Emphasis> hybrids

The attempts of this investigation were to develop a system for plant regeneration from explants of adult plants and its use for genetic transformation of important commercial Pelargonium zonale hybrid and P. peltatum hybrid cultivars. To this aim, leaf blade and petiole explants of eight cultivars were cultured on modified MS (Murashige and Skoog, 1962) medium with two concentrations of TDZ, BA, and zeatin (5 and 20 M). Petiole explants showed a higher regeneration response than leaf blade explants and TDZ was the most effective cytokinin. Petioles of 16 cultivars were incubated on medium containing 5, 10, 15, and 20 M TDZ, respectively, in order to identify the most effective TDZ concentration. For the majority of genotypes 10 M TDZ resulted in the best regeneration response. Cefotaxim at 500 mg l ^–1 had no effect on shoot regeneration and did not show interaction with glufosinate. For selection of transgenic cells, a concentration of 2.5 M glufosinate was shown to be appropriate. LBA4404 and EHA101 Agrobacterium strains carrying pIBGUS vector with pat gene as selectable marker gene and GUS gene as reporter gene were compared in transformation studies. With regard to GUS expression in petiole explants 16 days after coculture, better results were obtained with EHA 101 than with LBA 4404.     

Optimization of cell density and dilution rate in <Emphasis Type="Italic">Pichia pastoris</Emphasis> continuous fermentations for production of recombinant proteins

This paper provides an approach for optimizing the cell density (X_c) and dilution rate (D) in a chemostat for a Pichia pastoris continuous fermentation for the extracellular production of a recombinant protein, interferon (INF-). The objective was to maximize the volumetric productivity (Q, mg INF- l^–1 h^–1), which was accomplished using response surface methodology (RSM) to model the response of Q as a function of X_c and D within the ranges 150 X_c 450 g cells (wet weight) l^–1 and 0.1 _mD0.9 _m (_m=0.0678 h^–1, the maximum specific growth rate obtained from a fed-batch phase controlled with a methanol sensor). The methanol and medium feed rates that resulted in the desired X_c and D were determined based on the mass balance. From the RSM model, the optimal X_c and D were 328.9 g l^–1 and 0.0333 h^–1 for a maximum Q of 2.73 mg l^–1 h^–1. The model of specific production rate (, mg INF- g^–1 cells h^–1) was also established and showed the optimal X_c=287.7 g l^–1 and D=0.0361 h^–1 for the maximum (predicted to be 8.92×10^–3 mg^–1 g^–1 h^–1). The methanol specific consumption rate (, g methanol g^–1 cells h^–1) was calculated and shown to be independent of the cell density. The relationship between and (specific growth rate) was the same as that discovered from fed-batch fermentations of the same strain. The approach developed in this study is expected to be applicable to the optimization of continuous fermentations by other microorganisms.     

<Emphasis Type="Italic">In vitro</Emphasis> regeneration of <Emphasis Type="Italic">Perilla frutescens</Emphasis> from hypocotyl and cotyledon explants

Organogenetic buds were induced from hypocotyl and cotyledon explants of oil crop Perilla frutescens in Murashige and Skoog (MS) medium supplemented with 5.7 M indole-3-acetic acid (IAA) and 8.9 – 13.3 M 6-benzylaminopurine (BA). Shoots were rooted on MS medium with 2.9 M IAA and 1.4 M gibberellic acid (GA3) and the regenerated plants flowered and set seeds normally.     

Tissue culture propagation of Mongolian cherry (<Emphasis Type="Italic">Prunus fruticosa</Emphasis>) and Nanking cherry (<Emphasis Type="Italic">Prunus tomentosa</Emphasis>)

In vitro culture establishment, shoot proliferation and ex vitro rooting responses of Mongolian cherry (Prunus fruticosa L.), and Nanking cherry (Prunus tomentosa L.), were examined using various combinations of growth regulators. Dormant buds, taken during winter months, were used as explants. In both species, Murashige and Skoog Minimal Organic (MSMO) solid medium supplemented with 0.49 M indole-3-butyric acid (IBA) and either 4.44 or 8.88 M 6-benzylaminopurine (BA), was the best for culture initiation, and with 8.88–15.16 M BA for shoot proliferation. Good rooting responses were also obtained with shoots produced on media containing 0.91 M thidiazuron (TDZ). Auxin treatments were required for ex vitro rooting of approximately 20 mm long shoots in peat/perlite (1:1 v/v) mixture, at 25 °C, under mist. The best rooting (79%) was obtained with IBA/NAA (naphthaleneacetic acid) (9.80/2.69 M) combination. A commercial rooting powder, Rootone F, containing IBA/NAA (0.057/0.067%), was also effective (73%). The ex vitro rooted plantlets did not require any additional acclimatization prior to transplanting to the regular greenhouse conditions.     

Enhancement of photorespiration in immobilized <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> cells

Immobilization of Chlamydomonas reinhardtii in alginate increases its photorespiration rate. In the immobilized cells, the photorespiratory enzyme, phosphoglycolate phosphatase, was 75% higher than in freely suspended cells. Thus, the immobilized cells produced glycolate at twice the rate than in freely suspended cells when treated with aminooxyacetate (a transaminase inhibitor). With immobilized cells in a batch reactor, 270mol glycolatemg^–1 Chl was produced after 12h.Revisions requested 27 October 2004; Revisions received 13 December 2004