Microbiological Synthesis of Fat: THE FORMATION OF FAT FROM SUCROSE

1. Forty-three strains of moulds, selected from ten species,were examined to ascertain their capabilities as producers offat, when grown in four different solutions of nutrient inorganicsalts together with sucrose. The three highest yields of feltwere given by Penicillium javanicum van Beyma, P. Soppi Zaleski,and Aspergillus nidulans Eidam, in that order. The fat contenton felt weight was maximal at 34·8 per cent, with P.Soppi, at 28·4 per cent. with Fusarium lini(1), and at25·8 per cent. with A. nidulans; on sugar utilized itwas maximal at 11·4 per cent. with P. Soppi, at 7·9per cent, with A. nidulans, and at 5·6 per cent. withF. lini(1). 2. Other moulds considered worthy of further trial were P. spinulosum,P. aurantiobrunneum, F. graminearum, A. flavus, F. oxysporum,A. clavatus, and P. oxalicum.     

Microbiological Synthesis of Fat: PRELIMINARY SURVEY OF THE FAT-PRODUCING MOULDS

1. A survey of potential fat-producing moulds has shown that atleast 40 strains from 10 species are of interest.
2. These havebeen grown on five different media and A. nidulans,P. spinu-losum,P. javanicum, P. piscarium, P. flavo-cinereum,P. oxalicum,A. flavus, A. flavipes have shown the most promise.
3. The fatcontent on felt weight was maximal at 39?7 per cent,with A.flavipes and 34?6 per cent, with F. lini, and on usedsugarwas maximal at 9?3 per cent, with A. flavipes and 6?7per cent,with A. nidulans.
4. The potential value of micro-organisms asfat producers is discussedwith reference to the moulds.

     

Minerals, Carbohydrates and Amino Acids of Pollens from some Woody and Herbaceous Plants

The mineral, carbohydrate, protein, amino acid, lipid and energycontents of the seven main pollens gathered by honey-bees insouth-east Scotland were determined. Neither dry matter (mean73 per cent) nor ash (mean 3 per cent) were very variable. Thecalcium content of all pollens was relatively similar as werethe magnesium, potassium and sodium contents but manganese whichwas relatively high in ericaceae and phosphorus which was lowin Trifolium were more variable. Acer pollen contained mostprotein and Fagus least, and of the amino acids only serine,cystine and histidine were significantly different in the differentpollens. Over 30 per cent of all pollens was a mixture of fructoseand glucose, ericaceae containing most and Acer least. Hemicellulose(mean 7 per cent) was high in Ranunculus and low in Acer, cruciferaeand Fagus. ‘Cellulose’ (mean 0•5 per cent)was high in cruciferae and low in ericacea. Ether extract (mean5 per cent) was high in cruciferae and Fagus. The mean grossenergy of pollen was 23 kJ g^–1. Fresh pollen is comparable with lean meat as a source of energyand protein, and is more like dormant plant seeds than herbagein its water, ash and protein content but stores energy as sugarrather than starch or lipid.     

Links between Glucose Uptake and Metabolism in Nitella translucens

The uptake of ¹⁴C-glucose into cells of Nitella translucenshas been investigated under experimental conditions previouslyused in studies of the ionic relations of these cells. Glucoseentry was considerably stimulated by light, and under aerobicconditions the fluxes remained constant for many hours. Theinflux of glucose was inhibited by over 80 per cent at low temperature(4° C) and by over 90 per cent by the uncoupler carbonylcycanide-m-chlorophenylhydrazone. 2-Deoxy-D-glucose was a non-competitiveinhibitor of glucose uptake both in light and darkness. Cyclicphotophosphorylation promoted the influx (with decreasing efficiency)for several hours. It is suggested that an ATP-dependent transportprocess controls glucose entry to the cells, and that passivediffusion is of little significance.     

Photosynthesis and Formation of Fats in a Diatom

A study has been made, using C¹⁴ as a tracer, of the variationswhich occur according to the physiological condition of thecells in the distribution of carbon fixed, both in the lightand in the dark, by the diatom Navicula pelliculosa (Bréb.)Hilse during periods of 30 to 300 seconds. Fixation into thefollowing cell fractions was determined: (A) material solublein 80 per cent. ethanol but insoluble in benzene, (B) materialsoluble both in 80 per cent. ethanol and in benzene, and (C)material insoluble in 80 per cent. ethanol. Carbon fixed inphotosynthesis was incorporated, rapidly and in amounts representingup to 70 per cent. of the total fixation, into fractions B andC, as well as into fraction A. Considerable variation was foundin the proportions of carbon entering the three fractions inthe light; in actively growing cells the proportion enteringfraction C preponderated over that in B, corresponding to thesynthesis of protein, whereas in nitrogen-deficient cells fixationin B was the greater, corresponding to the synthesis of fat.These patterns changed only slowly, over periods of days, followingthe transfer of cells to altered conditions of nitrate supply.However, when ammonium nitrogen was supplied to nitrogen-deficientcells a marked change in distribution of carbon fixed occurredwithin 5 minutes, fixation in fraction B falling to a low valueand that in A rising correspondingly. In cells subjected toprolonged nitrogen-deficiency, fixation in fraction B fell toa relatively low value but the proportion which this fractionformed of the total dry matter in the cells rose as a resultof an increased rate of loss from the cells of constituentsother than lipides. The distribution of carbon fixed was alsodependent on light intensity. Fixation in fractions B and Crose relatively to that in A as light intensity was increasedup to 100 foot-candles but fell again at the highest intensityused, 2,000 foot-candles. These results are discussed with particularreference to the relationship between fat accumulation and photosynthesisin algae.     

Overcoming Incompatibility in Brassica campestris L. by Carbon Dioxide, and Dark Fixation of the Gas by Self- and Cross-pollinated Pistils

Supplementing pollen suspension cultures with CO₂ (3–5per cent) caused a marked increase in germination and tube growthin vitro in Brassica campestris L. cv. toria. A weakening ofself-incompatibility by increased CO₂ levels from 3–5per cent was observed. The percentage of pollen tubes whichpenetrated the cuticle layer of stigmatic papilla cells in self-pollinatedpistils was high when CO₂ level was 5 per cent. Phosphoenolpyruvate (PEP) carboxylase activity was greater in the pollengerminated in 4 per cent CO₂ as compared to air (0.03 per cent).A possible role of CO₂ for self-recognition and control of pollentube growth is proposed, proposed. Brassica campestris L., carbon dioxide, self-incompatibility, phosphoenol pyruvate carboxylase     

Hugo de Vries and the Development of Seed Aging Theory

Although work published in 1901 by de Vries has helped shapeour current understanding of the relationship between seed agingand genetic mutation, it has been fundamentally misinterpreted.Upon sowing 5 year-old Oenothera erythrosepala seed, de Vriesobtained an emergence of about 1 per cent. A relatively highproportion of the seedlings (about 40 per cent) displayed mutantphenotypes, mostly albida or lata. De Vries concluded that thesephenotypes, which were already present to a minor extent (about1 per cent) in unaged seed lots, were more resistant to agingthan the erythrosepala norm. Later opinion has dismissed DeVries' hypothesis, contending instead that the mutant phenotypesarose as a consequence of seed aging. A reconsideration of thesedata suggests that the De Vries' explanation remains more convincing;paradoxically, his work on seed aging has been influential becauseit has been consistently misunderstood. Mutation, Oenothera, seed aging     

Types of Rot, Rate of Rotting, and Analysis of Pectic Substances in Apples Rotted by Fungi

The rate at which the fungi grew through apples was determinedin various ways and used to estimate their rate of linear advance.Five fungi were studied;they were Sclerotinia fructigena (firm-browncoloured rot, rapid growth through apples), Botrytis cinerea(soft, light-brown coloured rot, rapid growth through apples),Psyrenochaeta furfuracea (firm to soft rot, variable in colourbut generaly dark, slow growth through apples), Penicilliumexpansion A (soft, white rot, slow growth through apples) andPenicillium expansum B (soft, white rot, medium rate of growththrough apples). S. fructigena which had the highest rate oflinear advance which was about three times that of P. furfuraceawhich had the lowest. Methods for extracting different types of pectic substancesfrom sound and rotted tissues are described, and details aregiven of a rapid and reasonably accurate colorimetric methodof determining the anhydrogalacturonic acid content of theseextracts. The firm-rot fungi reduced the water-insoluble pecticsubstances by 10–20 per cent., but the soft-rot fungicaused much larger changes, up to 70 per cent. being degraded,The firm-rot and soft-rot fungi had different effects on thepectic substances insoluble in dilute acid but soluble in dilutealkali. The soft-rot fungi had little effect on these substances,or reduced their concentration, whereas the firm-rot fungi causedsubstantial increases compared with sound tissue. These resultsare considered in terms of pectic enzyme activity. Analysisof extracts by paper chromatography showed that galacturonicacid, absent from sound tissue, was present in each type ofrotted tissue. Di- and tri-galacturonic acids were present inrots caused by P. expansum, and these rots probably also containedproducts from the break-down of other polysaccharides.     

Experimental and Analytical Studies of Pteridophytes XXIV. Investigations on Marsilea: 4. ANATOMICAL EFFECTS OF CHANGES IN SUGAR CONCENTRATION

Sporelings of Marsilea, grown aseptically in various concentrationsof sugars, particularly glucose, have been investigated anatomically. It is shown that, corresponding to the features of the externalmorphology, the anatomy of the sporelings from the lower sugarconcentrations (1 and 2 per cent. glucose) has many characteristicsof the water forms of amphibious plants, while that of the sporelingsfrom the higher sugar concentrations (4 and 5 per cent, glucose)has the characteristics of typical land forms. A number of the differences between the two types of sporelingmay be referred to a change in the duration and direction ofcell-division in the rhizome-apex. Views as to the factors influencingthe origin of land or water forms are briefly discussed.     

Accumulation, Partitioning and Redistribution of Dry Matter and Mineral Nutrients in Ixia flexuosa L., with Special Reference to its Cormaceous Habit

The seasonal dynamics of uptake, partitioning and redistributionof dry matter, N, P, K, S, Ca, Mg, Na, Cl, Fe, Zn, Mn and Cuby the cormaceous plant Ixia flexuosa were studied in pot cultureat Perth, Western Australia. Dry matter and P, N, K, Zn andCu were redistributed from the mother corm with about 90 percent net efficiency: there was no net redistribution of Ca,Na, Fe or Mn. The efficiency of redistribution from the leafyshoot to fruits and the new season's corm was 80 per cent forN and P, 24–49 per cent for K, Cu and Zn, and 0–15per cent for Na, Fe, Ca, Mn, Cl, Mg, S and dry matter. Redistributionfrom the mother corm and vegetative organs could have suppliedthe replacement corm, cormlets and fruits with 32–53 percent of their S, K, P, N, Cu and Zn, and 11–25 per centof their Ca, Cl, Mn, Mg and dry matter. The mature replacementcorm had over 60 per cent of the plant's N and P, 25–50per cent of its dry matter, Zn, Cu, Mg, K and Cl, but less than20 per cent of its Ca, Na, Fe and Mn. Each plant produced anaverage of 12 cormlets; these had 35 per cent of the dry matterand 23–47 per cent of the amount of a particular nutrientin the new season's corms. Fruits had less than 16 per centof the dry matter and each mineral in the mature plant. Ratesof mineral intake by Ixia were much lower than reported forcrop plants, and may be related to the long growing season ofthe species. Ixia polystachya L., corm, nutrition, mineral nutrients, nutrient redistribution     

Sporulation in Rhizopus sexualis and Some Other Fungi Following a Period of Intense Respiration

Rhizopus sexualis grown at 20° C. on liquid I per cent.malt or glucose-asparagine medium showed a peak of respiratoryactivity between 40 and 55 hours-after inoculation. Rate ofrespiration then fell until it reached a steady low level whichcoincided with maximum mycelial growth. Zygospore initiationoccurred at or just after the peak of respiration. At a low temperature (9° C.) or with high concentrationsof glucose the respiration peak was less marked and no zygosporesdeveloped. Single ‘plus’ or ‘minus’strains of the heterothallic species Mucor hiemalis and Phycomycesblakesleeanus showed a pattern of respiration and mycelial growthsimilar to that of R. sexualis but no zygospores were formed.Zygospores did not develop without a preliminary period of intenserespiration, but such a peak period could occur without beingfollowed by zygospore formation. A strain of Sordaria fimicola was grown at 25° C. on a syntheticmedium with 5.0 per cent. sucrose or glucose as source of carbon.Respiration reached a peak at approximately 4 and 5 days respectively,the actual peak value being twice as large on sucrose as onglucose. Dry weight of mycelium was greater on glucose thanon sucrose. Perithecia were formed only on the sucrose medium.Visible peri-thecial initials were first seen shortly afterthe occurrence of the respiratory peak. Mature perithecia werepresent 3 days later. The possible significance of these results is discussed.     

Pollen-Derived Haploids of Nicotiana Knightiana, N. raimondii, and N. attenuata

Haploid plantlets were obtained in large numbers in three diploid,24-chromosome species of Nicotiana by culture of anthers ator just past the first pollen mitosis. The three species wereN. Knightiana, N. raimondii, and N. attentiata. Efficiency ofhaploid production varied from about 10 per cent in N. attenuatacultures to 30 and 38 per cent respectively in cultures of N.raimondii and N. Knightiana. H-medium without hormones and standardcultural conditions were used. N. Knightiana appeared to beespecially suitable for haploid studies on account of its highplantlet productivity, low chromosome number, and distinctivekaryotype.     

Phloem and Xylem Transport in the Supply of Minerals to a Developing Legume (Lupinus albus L.) Fruit

The economy of carbon, nitrogen, water and mineral elementsin fruits of Lupinus albus L. was studied by measuring accumulationof these quantities in the developing fruit and estimating itstranspirational losses and CO₂ exchanges. Combining this informationwith data on levels of mineral elements in the xylem sap andphloem sap supplying the fruit, it was possible to test whethertransport based on mass inflow through xylem and phloem wouldaccount for the observed intake of elements. A model of transportbased on water and carbon intake suggested that vascular intakeduring the fruit's life matched the recorded increment for mineralsto within ± 15 per cent for N, Na, Zn, Fe and Cu, andto within ± 23 per cent for P, K and S. However, estimatedvascular intake of Ca, Mg and Mn accounted for less than one–thirdof the recorded intake by the fruit, inadequacy of vascularintake being especially great early in growth. Transport inphloem accounted for more than 80 per cent of the fruit's vascularintake of C, N and S, and 70–80 per cent of its P, K,Mg and Zn. Xylem contributed 68 per cent of the vascular inputof Ca, 59 per cent of the Na, and 34–38 per cent of theFe, Mn and Cu. Enclosure and darkening of fruits reduced levelsof Ca and Fe but increased levels of N, P, K and Zn in fruitdry matter relative to unenclosed, illuminated fruits. Resultswere related to previous observations on fruit functioning. Lupinus albus, legume fruit, mineral supply, phloem, xylem     

Accumulation and Distribution of Nutrients in Fruits of Castor Bean (Ricinus communis L.)

The nutrition of developing fruits of Ricinus communis was studiednear Perth, Western Australia, where the species grows as aweed on poor sandy soil. Fruits required 60 days to mature anddehydration of the capsule began 20 days before the seeds ripened.Mature seeds accumulated 49 per cent of the fruit dry matterand over 80 per cent of its P, Zn and Cu, 50–80 per centof its Mg, N, Fe and Mn, 41–46 per cent of its S and Caand 11–21 per cent of its K and Na. Losses of nutrientsfrom capsules during fruit ripening were: Zn, 73 per cent, P,42 per cent, Cu, 23 per cent and Mn, 8 per cent. Dry matter,N, K, S, Ca, Mg, Na and Fe were not withdrawn from capsules.Apparent retranslocation from capsules could have provided from6–28 per cent of the Zn, Mn, P and Cu in mature seeds.Seeds from plants on poor sandy soil were small but had adequatelevels of nutrients when compared with those from plants growingon a fertile loam. Concentrations of all nutrients except P were higher in youngcapsules than in young seeds, but levels of N, P, Mg, Fe, Znand Cu were higher in mature seeds than in mature capsules.The intake of most nutrients by fruits was out of phase withdry matter accumulation, especially in capsules, and the elementsappeared to accumulate in fruit parts independently of eachother. Glutamine accounted for over 85 per cent of the amino-Nin phloem sap destined for fruits. Potassium made up over 90per cent of the inorganic cations in phloem exudate. Of theminor elements in the exudate, Fe was present at highest concentrationand Cu at the lowest. The results showed that retranslocation from the capsule madea very small contribution to the nutrition of seeds. It is suggestedthat R. communis would require a sustained supply of soil nutrientsto ensure maximum seed yield, partly due to the restricted retranslocationof most nutrients from capsules. Ricinus communis L., castor bean, mineral nutrition, translocation, retranslocation     

The Heterotrophic Nutrition of Chlorella vulgaris (Brannon No. 1 Strain): With two Figures In the Text

A range of sugars, sugar alcohols, sugar phosphates, organicacids, and monohydric alcohols have been tested as carbon sourcesfor growth and as respiratory substrates using Chlorella vulgaris,Brannon I, grown in darkness. Much higher rates of growth and respiration were obtained withd-glucose than with any other substance tested. Ethanol (at0·005 M.) sustained both growth and respiration at c.50 per cent, of the level with glucose (0·028 M. or higher).Evidence was obtained that the organism can become ‘adapted’to utilize d-galactose and sucrose as effective carbon sources.Sustained growth was not obtained with any of the other substancestested. The glucose monophosphates, methanol and certain organic acids(oxalacetate, -ketoglutarate, cis-aconitate, and pyruvate) clearlystimulated oxygen uptake but to a less extent than ethanol.The other substances tested were either inhibitory to respirationor inactive or of very low activity as substrates. The growth in darkness and in liquid culture of Chlorella whensupplied with d-glucose was insensitive to pH over the range4·5 to 7·0 and was markedly enhanced by a highlevel of aeration. Gains in cellular dry weight ranging from45 to 90 per cent, of the weight of d-glucose disappearing fromthe culture medium were recorded in growth experiments; measurementsof CO₂ evolution in the Warburg indicated retention of up totwo-thirds of the glucose-C in cell material.     

Respiratory Loss of Recently Assimilated Carbon in Wheat

A series of experiments was undertaken to assess the amountof respiration associated with the growth of wheat at differentstages. Plants (or in some cases just the flag leaf) were labelledwith ¹⁴CO₂ and the amount of ¹⁴CO₂ respired during the subsequent48 or 72 h was measured. The evolution of ¹⁴C, expressed asa percentage of the amount initially assimilated (referred toas the R/A value) was used as a measure of the overall efficiencyof dry matter production. Respiratory ¹⁴CO₂ evolution from labelledplants was most rapid in the first 12 h after labelling, thereafterdeclining rapidly. Evolution was also more rapid following labellingsat the end of the light period (dusk) than at the beginningof it (dawn). The R/A values were greatest (42 and 50 per centrespectively for dawn- and dusk-labelled plants) for young plantsand least (13 and 28 per cent respectively) for plants duringmid grain filling. When flag leaves, as distinct from wholeplants, were labelled, R/A values were lower still (9 and 21per cent respectively), indicating that flag leaf assimilatewas used efficiently in grain production. The calculated minimum R/A for the formation of grain material(10 per cent protein, 90 per cent starch) was 6.2 per cent.That the experimentally determined values were greater thanthis is attributed to the turnover of carbon in enzymes, toother maintenance processes, and possibly to the operation ofthe pentose phosphate pathway of glucose oxidation. R/A valueswere lower in those plants labelled at the beginning than thoseat the end of the photoperiod. This was considered to be a consequenceof refixation of respiratory ¹⁴CO₂ during the light. The higherR/A values found for young plants were considered to be a consequenceof the greater percentage of ¹⁴C translocated to the roots (rootsbeing unable to refix respired CO₂) and of greater turnoverof enzymes associated with more active metabolism. Triticum, wheat, respiration, carbon assimilation, carbon loss, grain-filling     

In Vitro Induction of Haploid, Diploid, and Triploid Androgenic Embryoids and Plantlets in Datura metal L.

Pollen plantlets of Datura metel L. have been successfully rearedin vitro through anther culture on a nutrient medium supplementedwith coconut milk (15 per cent v/v) The early segmentation patternof the proembryos and their subsequent differentiation intoheart, torpedo, and cotyledonary stages were traced. More than100 plantlets were grown to maturity on soil. They grew normallyand produced flowers. Root-tip and leaf-squash preparationsshowed variable numbers of chromosomes in their cells, and thisindicated the occurrence of ploidy plants among the population.Frequency determinations showed the predominant types to bediploid (70 per cent), triploid (24 per cent), and haploid (6per cent). Differences in the morphology of mature plants inregard to floral size, meiotic irregularities in PMCs, formationof giant pollen grains, differential fruitset, somatic mosaicismin respect of chromosome number, and aneuploidy of cells, wererecorded. The origin of diploid and triploid plants is discussed.     

Variations with Age in Net Assimilation Rate and other Growth Attributes of Sugar-beet, Potato, and Barley in a Controlled Environment: With two Figures in the Text

Sugar-beet, potato, and barley plants were grown in a controlledenvironment, for periods of up to 10 weeks from sowing, witha light intensity of 1,8oo f.c. (4·9 cal./cm.²/hr.) anda temperature of 20° C. during the 18-hour photoperiod and15° C. during the dark period, to test whether net assimilationrate varied with age and differed between the three species. Net assimilation rate of all species based on leaf area (E_A)fell approximately linearly with time. During 5 weeks E_A ofsugar-beet decreased by only about 20 per cent. and E_A of potatodecreased by 50 per cent. E_A of barley remained approximatelyconstant for 4 weeks after sowing and was halved during thesubsequent 4 weeks. The average value of E_A for all times wasgreatest for sugarbeet and least for barley. Net assimilation rates based on leaf weight (E_W) and leaf N(E_N) decreased at about 15 per cent. of the initial value perweek for all species; this was similar to the mean rate of decreaseof E_A of potato and barley, but greater than that of E_A of sugar-beet.Mean values of E_W or E_N for potato and barley were similar andless than for sugar-beet. Relative growth rate (R_W), relative leaf growth-rate (R_A), andleaf-area ratio (F) fell with time at similar rates for allspecies. Average values of R_W decreased and of F increased inthe order sugar-beet, potato, barley. R_A was greatest for potatoand least for barley.     

Nutritional Factors Influencing the Production of Sclerotia by Certain Fungi

In various fungi (Botrytis cinerea, B. allii, Sclerotinia gladioli,Sclerotiun cepivorum, S. rolfsii, and Rhizoctonia solani) theinitiation of sclerotia, their further development to full sizeand their maturation were three distinct stages with differentnutritional requirements. These processes were followed on peptone-saltsmedia with a variety of carbon sources (carbohydrate or mannitol)ranging in concentration between 0·5 and 3 per cent.The nitrogen nutrition was varied in the presence of 2 per cent.glucose with peptone replaced by asparagine, potassium nitrate,or ammonium salts. All were suitable provided a high aciditydid not develop. Urea was unsatisfactory. Details given includethe rate of sugar utilization in some examples.     

An Analysis of Growth of Oil Palm Seedlings in Full Daylight and in Shade

Growth of seedling oil palms (Elaeis guineensis), in full daylightand under three levels of shade, was studied using growth analysistechniques. In full day-light, net assimilation rates (E_A) betweeno.15 and 0.32 g./dm.²/week were obtained associated with lowleaf-area ratios (F) giving relative growth-rates (R_W) rangingfromI I.8 to 3.2 per cent, per day. There were no indicationsof seasonal differences within the small range of values found. The plants take about 90 days to adapt to shade conditions becausethe mean plastochron is 24 days, and shading effects are beststudied on plants grown since germination under the shade treatments.Very different pictures of response to shade were obtained usingplants grown initially in full light followed by 90 days' shadebefore sampling compared with plants grown under shade sincegermination. In the latter, except at the lowest light levelused, I I.I per cent, of full day-light, there was very littleeffect of light on E_A or R_w, although the F values decreasedas light increased. Extrapolation of the F values to the extinctionpoint gave values similar to those obtained in another experimenton the effect of a number of shade levels on F. The physiological and ecological implications of these findings,particularly the low growth-rates and shade tolerance, are discussed.