Photoautotrophic potato cells: Transition from heterotrophic to autotrophic growth

Cells of potato (Solanum tuberosum L.) were obtained which were capable of photoautotrophic growth in liquid suspension culture under a photon flux density of 90–110 μmol m^?2 s^?1 PAR and in an atmosphere enriched with 2% CO₂. These photoautotrophic cells contained between 100 to 200 μg Chl (g fresh weight)^?1 and fixed CO₂ at a maximum rate of 16 μmol CO₂ (g fresh weight)^?1h^?1. In order to obtain cells capable of photoautotrophic growth it was necessary to adapt highly chlorophyllous heterotrophic cells (>50 μg Chl (g fresh weight)^?1) for growth in medium with 2.5 g sucrose 1^?1 (photomixotrophic cells). The photomixotropic cells had a Chl content of ca 100 μg Chl (g fresh weight)^?1 and were capable of photosynthetic activity which allowed them to survive after sugars had been depleted from the medium. It was from the photomixotrophic cells that cells capable of photoautotrophic growth were obtained. Heterotrophic cells initially established in liquid medium with 25 g sucrose I^?1 from chlorophyllous callus contained about 50 to 150 μg Chl (g fresh weight)^?1. However, after 5 to 10 passages the Chl content decreased to a maximum of 15 μg Chl (g fresh weight)^?1. These cells could not be adapted to photomixotrophic or photoautotrophic growth. These cells also were not able to regain Chl or initiate high rates of CO₂ fixation during the stationary phase of growth as did photomixotrophic cells or chlorophyllous heterotrophic cells. The loss of Chl exhibited by the cells during adaption to heterotrophic growth could be attributed at least in part to unbalanced growth (when cell division and growth exceeds Chl accumulation). Sucrose appeared to have an inhibitory effect directly on photosynthesis independent of Chl accumulation.     

Molar growth yields of Zymomonas mobilis on glucose after the transition from anaerobic to aerobic continuous growth

An increase in the molar growth yield (Y_X/S = 14.3–20.3 g/mol) on glucose (25 mM) was achieved after the transition of Zymomonas mobilis ATCC 29191 from anaerobic to aerobic steady state growth at dilution rates of D = 0.31–0.40 1/h and under oxygen-unlimited conditions. The transfer of anaerobically or aerobically grown steady state cells into a fresh medium resulted in the higher values of Y_X/S. A positive correlation was established between biomass and acetaldehyde yield within the range of 5–9 mM acetaldehyde in the medium. An inhibitory effect of the exogenously added acetaldehyde (K_i = 16.7 ± 2.8 mM) on the ATPase activity was observed in vitro, using cell-free extracts of anaerobically grown Z. mobilis. The results obtained provide evidence that the increased values of biomass yield could be explained by the redirection of ATP usage during aerobic growth of Z. mobilis.     

The effectiveness of various nitrogen sources in white spruce [Picea glauca (Moench) Voss] somatic embryogenesis

The effects of glutamine-based dipeptides, glutamine and casein hydrolysate, as well as the deletion of organic nitrogen, were investigated during white spruce [Picea glauca (Moench) Voss] somatic embryogenesis. There were no differences in the fresh weight increase of the tissue masses grown on initiation medium with different combinations of organic nitrogen. This was also the case for subsequent growth on kinetin medium, except that glutamine alone produced a significantly lower fresh weight increase than the other organic nitrogen combinations. Without organic (i.e. with only inorganic) nitrogen in the medium, the fresh weight increase was significantly less than with organic nitrogen on both initiation and kinetin medium. No differences were found between the dry/fresh weight ratios obtained with the various nitrogen treatments. The number of mature embryos produced per gram fresh weight when cultured in the absence of organic nitrogen was significantly higher than that obtained in its presence. There were no differences in the total number of mature embryos produced in cultures grown with various organic nitrogen combinations or without organic nitrogen. There were large clone differences with respect to the number of mature somatic embryos per gram tissue and the total number of somatic embryos produced. Hence, nitrogen type influences culture growth rate but not the number of mature somatic embryos produced. The latter was clone dependent.Abbreviations BA 6-benzylaminopurine - CH casein hydrolysate     

Hinokitiol Production in a Suspension Culture of Calocedrus formosana Florin

A suspension culture of Calocedrus formosana Florin was studied as a material for efficient production of hinokitiol. Murashige-Skoog’s medium containing 3% sucrose and 1 mg/l 1-naphthylacetic acid was most desirable for cell growth. Cell growth, expressed as fresh cell weight, showed a 20-fold increase after 4 weeks of culture in this medium. Adding potassium acetate or chitosan to the medium increased hinokitiol production. The highest hinokitiol yield, 1700 μg/g fresh cells, was obtained when cells were cultured in the growth medium with chitosan.     

Characteristic symptoms of photosynthesis inhibition by herbicides are expressed in photomixotrophic tissue cultures of Nicotiana

A photomixotrophic tissue culture system for Nicotiana plumbaginifolia and N. tabacum has been developed in which a primary symptom (bleching) of the inhibition of photosynthetic electron transport by herbicides can be observed. Photomixotrophic cultures were initiated and maintained in the light on medium containing 0.2–0.3% sucrose or glucose (low-sugar medium) as sole source of respirable carbohydrate. The usual medium for growing heterotrophic cultures contains 2–3% sucrose or glucose (high-sugar medium). Callus grown on low-sugar medium achieved a fresh weight three to four times greater in the light than in the dark and reached about half that of callus grown on high-sugar medium. Carbon-dioxide fixation rates were an order of magnitude higher in cultures grown on low-sugar medium in the light than in those grown on high-sugar medium or in any of the dark-grown cultures. The lightdependent growth and CO₂-fixation rates of cultures grown on low-sugar medium indicated that a major proportion of the weight increase resulted from photosynthesis. Under these photomixotrophic conditions it was found that a number of photosystem-II herbicides, at concentrations which inhibit photosynthetic electron transport, also inhibited the light-dependent component of callus growth, and caused bleaching. These effects could not be demonstrated on high-sugar medium.Abbreviations PSII photosystem II For common names of the herbicides the reader is referred to Weed Res. 19, 401–406 (1979)     

Production of the macrolide antibiotic tylosin in batch and chemostat cultures

The production of tylosin and related compounds by Streptomyces fradiae NRRL 2702 was studied in batch and chemostat cultures using a soluble synthetic medium. In batch culture, a trophophase–idiophase kinetic pattern was observed with tylosin, macrocin, and relomycin accumulating in the idiophase. When the organism was grown in chemostat culture, the specific rate of production of tylosin and related compounds (q_tylosin) was found to be a function of the growth rate. The maximum value of (q_tylosin) was observed when D = 0.017 hr^?1. At this growth rate only tylosin and relomycin accumulated in the medium. By varying the concentration of glucose in the ingoing medium it was possible to study the effects of glucose on tylosin synthesis in chemostat cultures. At a growth rate of 0.017 hr^?1, the maximum value of q_tylosin was 0.71 mg tylosin/g dry weight (DW)/hr when the glucose uptake rate was 7 mg glucose/g DW-hr. This value of q_tylosin was 40% greater than the maximum q_tylosin observed in batch culture. When glycerol was substituted for glucose in the medium, it was possible in chemostat culutures to get values of q_tylosin approximately 20% greater than those obtained with glucose at the same uptake rate. By varying the concentration of sodium glutamate in the ingoing medium it was possible to show that increasing the specific uptake rate of sodium glutamate increased the values of q_tylosin obtained. Similar chemostat experiments where the inorganic phosphate concentration in the ingoing medium was varied showed that increased the uptake of phosphate decreased the values of q_tylosin obtained. Also increasing the uptake rate of phosphate increased the relomycin-to-tylosin ratio. By taking into consideration the suppressing effects of glucose and the stimulating effects of sodium glutamate on tylosin synthesis, it was possible to formulate a medium that resulted in a value of q_tylosin of 1.1 mg/g/hr being obtained at a growth rate of 0.03 hr^?1. Batch fermentations with this medium did not follow a trophophase–idiophase kinetic pattern, but instead tylosin was actively synthesized during a period of rapid mycelial growth.     

The effect of phosphate concentration on growth and agar content of Gelidium robustum (Gelidiaceae,Rhodophyta) in culture

Phosphate concentration of the growth medium was found to affect the growth rate and agar yield of a clone of Gelidium robustum grown in the laboratory. To study differences in growth we used phosphate concentrations from 0 to 200 µM. To determine the effect of phosphate on agar yield and its properties we used concentrations from 0 to 20 µM. Growth rates generally increased with increasing phosphate concentration, with the highest growth rate (21% d^–1) obtained at 150 µM. Agar yield as percentage of fresh weight was highest (10%) in the algae grown with low phosphate concentrations, but agar yield as percentage of dry weight was highest(43%) at 20 µM of phosphate. Gel strength increased with phosphate concentration with a maximum of 160 g m^–2 for 0.75% gels for the cultures at 20 µM. Melting and gelling temperatures of the gels were also affected by phosphate concentration of the growth medium. Starch yield was highest in algae grown in low phosphate concentrations.     

Isolation of Phosphate Solubilizing Bacteria from Maize Rhizosphere and Their Potential for Rock Phosphate Solubilization–Mineralization and Plant Growth Promotion

Phosphate solubilizing bacteria (PSB) play a significant role in plant P nutrition by their effect on soil P dynamics and their subsequent ability to make P available to plants via solubilization and mineralization processes. This study aimed to evaluate the effect of separate and combined use of indigenous PSB, poultry manure (PM) and compost on solubilization and mineralization of rock phosphate (RP) and their subsequent effect on growth and P accumulation of maize (Zea mays L.). A group of fifty seven bacteria were isolated from the rhizosphere/rhizoplane of maize that had been grown in soils collected from varying altitudes (655–2,576 m) of the mountain region of Rawalakot, Azad Jammu and Kashmir, Pakistan. After screening, the capacity of eleven isolates to solubilize mineral phosphate was quantitatively evaluated using insoluble Ca₃(PO₄)₂ in culture medium as a time course study through spectrometer. The growth hormone producing (IAA) capacity of the isolates was also determined. Furthermore, five potential isolates were tested for their ability to increase P release capacity (mineralization) of insoluble RP in an incubation study. The effect of PSB inoculation on maize was determined in a completely randomized greenhouse experiment where root and shoot biomass and P accumulation in plants were assessed. The P solubilization index of selected isolates varied from 1.94 to 3.69, while the P solubilization efficiency ranged between 94.1% and 269.0%. The isolates MRS18 and MRS27 displayed the highest values. The P solubilization in the liquid medium was maximum at 6 and 9 days of incubation ranging between 9.91 and 44.04 µgmL^?1 and the isolates MRS27 and MRS34 exhibited the highest solubilization. Six isolates showed additional capability of producing IAA ranging between 2.66 and 28.41 µgmL^?1. Results of the incubation study indicated that P release capacity (P mineralization) of RP-amended soil varied between 6.0 and 11.8 µgPg^?1 that had been significantly increased to 30.6–36.3 µgPg^?1 (maximum value) when PSB were combined with RP. The combined application of PSB and organic amendments (PM, compost) with RP further increased P mineralization by releasing a maximum of 37.7 µgPg^?1 compared with separate application of RP (11.8 µgPg^?1) and organic amendments (21.5 and 16.5 µgPg^?1). The overall effect of PSB (as a group) with RP over RP alone on maize growth showing a relative increase in shoot length 21%, shoot fresh weight 42%, shoot dry weight 24%, root length 11%, root fresh weight 59%, root dry weight 35% and chlorophyll content 32%. This study clearly indicates that use of PSB, and organic amendments with insoluble RP could be a promising management strategy to enhance P availability in soil pool and improve plant growth in intensive cropping systems.     

Photoautotrophic Growth and Photosynthesis in Cell Suspension Cultures of Chenopodium rubrum

A method is described for growing cell suspension cultures of Chenopodium rubrum photoautotrophically for prolonged periods of time. By using a two-tier culture vessel the growth medium with the cells was separated from the CO₂ reservoir. Definite CO₂ concentrations were established by a K₂CO₃/KHCO₃ buffer. Photoautotrophic growth in C. rubrum cell suspension cultures was correlated with the CO₂ level. At 0.5% CO₂ the cell cultures contained 68 μg chlorophyll/g fresh weight and showed an increase in fresh weight of about 80% in 18 days. At 1% CO₂ an increase in fresh weight of 165% in 18 days was observed. The chlorophyll content rose up to 84 μg/g fresh weight. The photoautotrophic growth was also greatly influenced by the 2,4-D content of the medium. Cell growth was enhanced by lowering the auxin concentration. Best growth was attained (210% increase in fresh weight) at 10^?8M 2,4-D. The photosynthetic activity of the cells was measured by the light dependent ¹⁴CO₂ incorporation. At 0.5% CO₂ the cell suspensions assimilated about 100 μmol CO₂/mg chlorophyll × h. In the presence of 1% CO₂ the light driven assimilation was raised up to 185 μmol CO₂/mg chlorophyll × h. In both cases, the dark incorporation of CO₂ was merely 1.8% of the values obtained in light.     

Phytofiltration of anaerobically digested sugarcane ethanol stillage using a macrophyte with high potential for biofuel production

Anaerobically digested stillage (ADS) requires treatment before being discharged into water bodies or soils to avoid adverse effects. Phytofiltration systems are eco-friendly technologies for wastewater treatment, and they simultaneously serve as a source of biomass for biofuel production. The aim of the present study was to investigate the phytofiltration of ADS using Azolla sp. The effects of the ADS strength (dilutions 1:?50 and 1?:?25 v/v) and initial biomass density (IBD) [15.44 (IBD1) and 23.16 (IBD2) g dry weight (dw) m^?2] on plant growth and pollutant removal were assessed. Productivities obtained at ADS 1:?50 (2.93 and 3.04 g m^?2 d^?1 for IBD1 and IBD2, respectively) were not significantly different from those of a synthetic medium (2.56 and 3.15 g m^?2 for IBD1 and IBD2, respectively). Higher organic matter removal was found using ADS at 1:?25 than that obtained using ADS 1:?50 (52.16–53.34 vs 32.29–38.16%), while no IBD effect was observed. The nutrient concentrations in ADS were reduced significantly, especially the concentrations of NH₄-N (75.11–82.54%), PO₄-P (88.72–92.90%) and SO₄-S (55.95–66.61%). The conversion of nutrients from ADS into Azolla biomass may result in an effective way to produce an attractive feedstock for biofuel production.     

Efficiency of neural network-based combinatorial model predicting optimal culture conditions for maximum biomass yields in hairy root cultures

Key message

ANN-based combinatorial model is proposed and its efficiency is assessed for the prediction of optimal culture conditions to achieve maximum productivity in a bioprocess in terms of high biomass.

Abstract

A neural network approach is utilized in combination with Hidden Markov concept to assess the optimal values of different environmental factors that result in maximum biomass productivity of cultured tissues after definite culture duration. Five hidden Markov models (HMMs) were derived for five test culture conditions, i.e. pH of liquid growth medium, volume of medium per culture vessel, sucrose concentration (%w/v) in growth medium, nitrate concentration (g/l) in the medium and finally the density of initial inoculum (g fresh weight) per culture vessel and their corresponding fresh weight biomass. The artificial neural network (ANN) model was represented as the function of these five Markov models, and the overall simulation of fresh weight biomass was done with this combinatorial ANN–HMM. The empirical results of Rauwolfia serpentina hairy roots were taken as model and compared with simulated results obtained from pure ANN and ANN–HMMs. The stochastic testing and Cronbach’s α-value of pure and combinatorial model revealed more internal consistency and skewed character (0.4635) in histogram of ANN–HMM compared to pure ANN (0.3804). The simulated results for optimal conditions of maximum fresh weight production obtained from ANN–HMM and ANN model closely resemble the experimentally optimized culture conditions based on which highest fresh weight was obtained. However, only 2.99 % deviation from the experimental values could be observed in the values obtained from combinatorial model when compared to the pure ANN model (5.44 %). This comparison showed 45 % better potential of combinatorial model for the prediction of optimal culture conditions for the best growth of hairy root cultures.     

Growing microalgae as aquaculture feeds on twin-layers: a novel solid-state photobioreactor

Four strains of marine microalgae commonly used as live feeds in hatcheries (Isochrysis sp. T.ISO, Tetraselmis suecica, Phaeodactylum tricornutum, Nannochloropsis sp.) were grown in a novel solid-state photobioreactor, the twin-layer system. Microalgae were immobilized by self adhesion to vertically oriented twin-layer modules which consisted of two different types of ultrathin layers, a macroporous source layer (glass fiber nonwoven) through which the culture medium was transported by gravity flow, and a microporous substrate layer (plain printing paper) which carried the algae on both surfaces of the source layer. This simple open cultivation system effectively separated the immobilized microalgae from the bulk of the growth medium and permitted prolonged cultivation of microalgae with average biomass yields of 10–15 g dry weight m^?2 growth area after 14–25 days of cultivation. Algal biomass was harvested as fresh weight (with 72–84 % water content) without the need to pre-concentrate algae. No aeration or external CO₂ supply was necessary, and due to the microporous substrate layer, no eukaryotic contaminations were observed during the experiment. All experiments were conducted in Germany under greenhouse conditions with natural sunlight. Small-scale growth experiments performed under the same conditions revealed that growth over most of the experimental period (24 days) was linear in all tested algae with growth rates (dry weight per square meter growth area) determined to be 0.6 g ?m^?2?day^?1 (Isochrysis), 0.8 g? m^?2?day^?1 (Nannochloropsis), 1.5 g ?m^?2?day^?1 (Tetraselmis), and 1.8 g? m^?2?day^?1 (Phaeodactylum). Due to its cost-effective construction and with further optimisation of design and productivity at technical scales, the twin-layer system may provide an attractive alternative to methods traditionally used to cultivate live microalgae.     

Development of a Polygonum minus cell suspension culture system and analysis of secondary metabolites enhanced by elicitation

Polygonum minus has been reported to contain valuable metabolites and to date, there is no report on using cell culture technique for metabolite production in P. minus. Naphthalene acetic acid (NAA) concentrations in the range of 2–6 mg L^?1 were used in a matrix of combinations with dichlorophenoxyacetic acid (2,4-D) concentrations in the range of 2–10 mg L^?1 as plant growth regulators (PGRs) to induce callus cultures. Media that were supplemented with 2 mg L^?1 2,4-D + 4 mg L^?1 NAA, 2 mg L^?1 2,4-D + 6 mg L^?1 NAA and 6 mg L^?1 2,4-D + 8 mg L^?1 NAA were effective for callus induction (93.3 % of the explants produced callus). To establish cell culture, the best growth was obtained from medium that was supplemented with 1 mg L^?1 2,4-D + 2 mg L^?1 NAA. From a 1-g inoculum size, the fresh weight increases exponentially after 5–10 days of culture, and a 26.71 g maximum fresh weight was obtained after 25 days of culture. The cell culture medium was then analyzed using gas chromatography–mass spectrometry (GC–MS). Jasmonic acid (100, 50, 25 and 5 μM), salicylic acid (100, 50, 25 and 5 μM), yeast extract (500, 250 and 100 mg L^?1) and glass beads were used in this research as elicitors. The cell cultures were then incubated with the different elicitors for 1, 2, 3 and 4 days. Several compounds with high peak area percentages were detected, including 2-furancarboxaldehyde, 5-hydroxymethyl, furfural, and 2-cyclopenten-1-one, 2-hydroxy. These results show the diversity of metabolites released by P. minus cell into the culture medium under control conditions.     

Production of Candida utilis protein from peat extracts

Sphagnum peat extracts or hydrolysates have been obtained and used as a culture medium for the production of Candida utilis biomass as single cell proteins. Acid hydrolysis of ground peat (4–60 mesh) in an autoclave operated under a set of conditions for acid strength (0.3-1.5 (v/v) H₂SO₄), holding time (1–4 hr), temperature (100–165°C), and weight ratio of dry peat to solution (3.3–16.7 g dry peat/100 g solution) yielded carbohydrate-rich extracts of different concentrations (1–34g/liter). The best yield (mg total carbohydrate/g dry peat) was obtained for a holding time of I hr and a temperature of 152°C. Low peat concentratio (4.1 g dry peat/100 g solution)resulted in high yield(280mg total carbohydrate/gdry peat) with a corresponding low carbohydrate content in hydrolysate (13 g/liter), while a lower yield with a higher carbohydrate content (34 g/liter)in hydrolysate were found when increasing peat concentration (16.7 g dry peat/100 g solution). Shake-fladk experiments using peat hydrolysates as the culture medium together with NH₄OH (～4.8 g/liter) and K₂HPO₄(5 g/liter) as nitrogen and phosphate supplement, respectively, gave a maximum biomass concentration of 7.5 g/liter after 60 hr at 30°C and 200rpm. Batch cultivation in a fermentor under controlled conditions for aeration (4.2 liter/min), agitation (500rpm), temperature (30°C), and pH (5.0) produced a maximum biomass of 10 g/liter after 20 hr with a specific growth rate of 0.13 hr^?1. For the continuous cultivation, a maximal biomass productivity of 1.24 g/gliter-he was obtained at a dilution rate of 0.125 hr ^?1. Monod's equation's equation has been used for the estimation of the coefficients μ_Max, K_s, and Y. It was found that the yield coefficient Y is not constant during the progress of batch cultivation.     

Chemoautotrophic growth of Rhodopseudomonas species with hydrogen and chemotrophic utilization of methanol and formate

A chemolithoautotrophic type of metabolism, which was hitherto unknown for purple nonsulfur bacteria, was demonstrated by growth experiments using Rhodopseudomonas capsulata Kb1 and Rhodopseudomonas acidophila 10050. These strains were able to grow in a mineral medium in the dark at the expense of H₂, O₂, and CO₂. A minimum doubling time of 9 h was obtained for R. capsulata under an atmosphere containing less than 15% oxygen; higher oxygen concentrations suppressed autotrophic but not chemoorganotrophic growth. Oxygen sensitivity of chemoautotrophically growing cells of R. acidophila was even more pronounced, whereas cells growing chemotrophically on methanol almost tolerated the oxygen concentration of air. Highest oxygen sensitivity of growth of R. acidophila was observed with formate as substrate. The growth yield of cultures grown semiaerobically in the dark on methanol was 0.23 g dry cell material per g methanol consumed.     

Growth ofChlamydia psittaci strain menigopneumonitis in mouse L cells cultivated in a defined medium in spinner cultures

Summary L cells were grown in spinner cultures in a defined medium consisting of Waymouth medium MB752/1 (19) supplemented with 2 mg of fatty acid-free bovine serum albumin (BSA) per ml and 5 μg of oleate per ml (WO₅ medium). Growth in WO₅ medium was comparable to spinner L cell growth in two serum-containing media. The optimal concentration of oleate in the WO medium was 5 to 10 μg per ml. The use of 20 to 80 μg of oleate per ml of medium resulted in lower peak populations and earlier declines in viable cell counts. Cell death occurred rapidly in WO₁₆₀ medium. Cell growth in WO medium containing 5 to 80 μg of oleate per ml was well above the level of growth observed when no oleate was present in the medium. Since the total lipid and fatty acid compositions of the BSA used in this study have been characterized by the authors, the WO medium may be considered a defined medium. L cells have been continuously maintained in spinner cultures in WO₅ medium for over 50 passages with no major variation in the growth pattern. A 1000-fold increase inChlamydia psittaci strain meningopneumonitis, with a peak titer of 9.3×10⁷ plaque-forming units per ml, was observed when the chlamydial agents were grown in spinner L cells in WO₅ medium. This investigation was supported by Public Health Service Research Grant HE 08214 from the Program Projects Branch, Extramural Programs, National Heart and Lung Institute; The World Health Organization; and The Hormel Foundation.     

Improved Growth of Tissue Cultures of the Onion, Allium cepa

A forty-fold increase in tissue fresh weight has been achieved for Allium cepa stem tissue callus grown on a modified B5 medium with increased ammonium, phosphate and nitrogen levels; and decreased level of 2,4-dichlorophenoxyacetic acid. Growth was examined on several standard media, using fresh weight, dry weight and cell number as parameters over an 8-week growth period. Further, tissue grown upon this medium is more friable than on other media. The value of such friable callus for suspension culture initiation and for single cell cloning experiments is discussed.     

Evidence for multiple molecular weight froms of somatostatin-like material in Escherichia coli

Extracts of Escherichia coli grown in defined medium contain somatostatin-related material (1–10 pg/g wet weight of cells). Preconditioned medium had no immunoactive somatostatin whereas, conditioned medium had 110–150 pg/1. Following purification of the extracted material on Sep-pak C₁₈, Bio-Gel P-6 and HPLC, multiple molecular weight forms of somatostatin- (SRIF-) related material were identified. The material in one peak reacted in both the N-terminal and C-terminal SRIF immunoassay and coeluted on HPLC with SRIF-28, whereas that in a second peak eluted near SRIF-14 and was reactive only in the C-terminal SRIF assay. The two peaks are thus similar to SRIF-28 and SRIF-14 of vertebrates. These findings add support to the suggestion that vertebrate-type peptide hormones and neuropeptides have early evolutionary origins.     

Trehalose, Respiration und Photosynthese in dem Farn Ophioglossum, Ein neuer Schattenblattypus

Trehalose, Resipration and Photosynthesis in the Fern Ophioglossum. A new Type of Shade-Leaves.—Trehalose has been identified in the leaf-blades, sporehouses, stems and rhizomes of the fern Ophioglossum vulgatum by paper chromatography. The leaf-blades represent a hitherto undescribed type of shade-leaf. Just like normal shade-leaves, they have a low respiratory activity ～0.2–0.3 mg CO₂ per 50 cm² leaf-blade (one side only) and hour at 20°C and low maximal photosynthesis: 2–2.7 mg CO₂ per 50 cm² leaf-blade (one side only) and hour at 20°C and a CO₂-pressure of 0.25 mm Hg and a light intensity of 20,000 lux. But in contrast to the hitherto described type of shade-leaves, the area per 1 g fresh weight is that of typical sun-leaves which is 35–50 cm² (one side only) per 1 g fresh weight. The large area weight is connected with particularly low dry matter content ～10–11 per cent in the leaf-blades; this indicates that the material is a kind of semisucculent shade-leaf.     

Growth Response to Cyanide by Plants Grown in the Presence or Absence of Iron

Seedlings of Phaseolux vulgaris were grown in media with and without iron. Growth was measured in terms of leaf length and fresh weight increase. Cyanide at & concentration of 0.05 mM was found to inhibit severely plants growing in complete media but failed to inhibit growth to (he same extent in those plants grown in media lacking iron. It was established that this result was obtained whether the plants were grown in an unchanged medium or if the growth medium was replaced at intervals. A number of suggestions were made in an attempt to account for this anomalous behavior.