Hypoosmotic volume regulation in the sea anemone metridium senile

1. The anemone Metridium senile survives salinities from seawater (950 mOsm) to 55% SW (520 mOsm) for at least two weeks. Animals exposed to 40% SW (380 mOsm) die within three days.2. The tissue amino acid content of M. senile acclimated to 950 mOsm, 807 mOsm, 665 mOsm and 520 mOsm for two weeks is respectively, 444, 382, 331 and 251 μmol/g dry wt. A decrease in the concentration of taurine accounts for nearly all of the decrease in the free amino acid pool.3. Tissue hydration increases in M. senile acclimated to dilute seawater, but the increase was not proportional to the change in ambient salinity, indicating that the anemones partially regulate volume in dilute media.4. Mathematical analyses of changes in tissue hydration as a function of ambient salinity in M. senile, Haliplanella lineata, and Diadumene leucolena suggest that the effectiveness of volume regulation increases in individuals of these species acclimated to progressively more dilute media. The volume regulatory capability of Bunodosoma cavernata does not change in dilute media.     

Improved Sugar Conversion and Ethanol Yield for Forage Sorghum (Sorghum bicolor L. Moench) Lines with Reduced Lignin Contents

Lignin is known to impede conversion of lignocellulose into ethanol. In this study, forage sorghum plants carrying brown midrib (bmr) mutations, which reduce lignin contents, were evaluated as bioenergy feedstocks. The near-isogenic lines evaluated were: wild type, bmr-6, bmr-12, and bmr-6 bmr-12 double mutant. The bmr-6 and bmr-12 mutations were equally efficient at reducing lignin contents (by 13% and 15%, respectively), and the effects were additive (27%) for the double mutant. Reducing lignin content was highly beneficial for improving biomass conversion yields. Sorghum biomass samples were pretreated with dilute acid and recovered solids washed and hydrolyzed with cellulase to liberate glucose. Glucose yields for the sorghum biomass were improved by 27%, 23%, and 34% for bmr-6, bmr-12, and the double mutant, respectively, compared to wild type. Sorghum biomass was also pretreated with dilute acid followed by co-treatment with cellulases and Saccharomyces cerevisiae for simultaneous saccharification and fermentation (SSF) into ethanol. Conversion of cellulose to ethanol for dilute-acid pretreated sorghum biomass was improved by 22%, 21%, and 43% for bmr-6, bmr-12, and the double mutant compared to wild type, respectively. Electron microscopy of dilute-acid treated samples showed an increased number of lignin globules in double-mutant tissues as compared to the wild-type, suggesting the lignin had become more pliable. The mutations were also effective for improving ethanol yields when the (degrained) sorghum was pretreated with dilute alkali instead of dilute acid. Following pretreatment with dilute ammonium hydroxide and SSF, ethanol conversion yields were 116 and 130 mg ethanol/g dry biomass for the double-mutant samples and 98 and 113 mg/g for the wild-type samples.     

Osmotic regulation in late embryos and prelarvae of the American lobster Homarus americanus H. Milne-Edwards, 1837 (Crustacea,Decapoda)

Osmotic regulation of embryos, hatching prelarvae, and free prelarvae was studied in Homarus americanus H. Milne-Edwards, 1837. Adaptation time in dilute media was much longer in embryos than in hatchlings and prelarvae. Regulation in dilute media was hyperosmotic in embryos and hyperosmoconforming in hatchlings and prelarvae. The change in type of osmoregulation that occurred during the hatch is due to the rupture of the relatively impermeable outer egg membrane.     

Chemical and morphological characterization of sugarcane bagasse submitted to a delignification process for enhanced enzymatic digestibility

Background

While advantages of biofuel have been widely reported, studies also highlight the challenges in large scale production of biofuel. Cost of ethanol and process energy use in cellulosic ethanol plants are dependent on technologies used for conversion of feedstock. Process modeling can aid in identifying techno-economic bottlenecks in a production process. A comprehensive techno-economic analysis was performed for conversion of cellulosic feedstock to ethanol using some of the common pretreatment technologies: dilute acid, dilute alkali, hot water and steam explosion. Detailed process models incorporating feedstock handling, pretreatment, simultaneous saccharification and co-fermentation, ethanol recovery and downstream processing were developed using SuperPro Designer. Tall Fescue (Festuca arundinacea Schreb) was used as a model feedstock.

Results

Projected ethanol yields were 252.62, 255.80, 255.27 and 230.23 L/dry metric ton biomass for conversion process using dilute acid, dilute alkali, hot water and steam explosion pretreatment technologies respectively. Price of feedstock and cellulose enzymes were assumed as $50/metric ton and 0.517/kg broth (10% protein in broth, 600 FPU/g protein) respectively. Capital cost of ethanol plants processing 250,000 metric tons of feedstock/year was $1.92, $1.73, $1.72 and $1.70/L ethanol for process using dilute acid, dilute alkali, hot water and steam explosion pretreatment respectively. Ethanol production cost of $0.83, $0.88, $0.81 and $0.85/L ethanol was estimated for production process using dilute acid, dilute alkali, hot water and steam explosion pretreatment respectively. Water use in the production process using dilute acid, dilute alkali, hot water and steam explosion pretreatment was estimated 5.96, 6.07, 5.84 and 4.36 kg/L ethanol respectively.

Conclusions

Ethanol price and energy use were highly dependent on process conditions used in the ethanol production plant. Potential for significant ethanol cost reductions exist in increasing pentose fermentation efficiency and reducing biomass and enzyme costs. The results demonstrated the importance of addressing the tradeoffs in capital costs, pretreatment and downstream processing technologies.     

Photoselection and aggregation in purple membrane of Halobacterium halobium

Preparations of the purple membrane of Halobacterium halobium suspended in dilute buffer and basal salt have been examined by circular dichroism spectroscopy and correlation analysis of scattered laser light. Dark adapted samples suspended in basal salt show photoselection when examined by circular dichroism. This was confirmed by irradiation with plane polarized light. Light-adapted samples or dark-adapted samples suspended in dilute buffer did not show this phenomenon. The reaction responsible for photoselection was shown to be the light induced cis-trans isomerization of bacteriorhodopsin. The stability of the induced anisotropy was due to aggregation in the basal salt suspensions which occurred despite little or no visual indication. This aggregation was confirmed by correlation analysis of scattered laser light.     

Bees get a head start on honey production

Nectar concentration is assumed to remain constant during transport by honeybees between flowers and hive. We sampled crop contents of nectar foragers on Aloe greatheadii var. davyana, a major winter bee plant in South Africa. The nectar is dilute (approx. 20% w/w), but the crop contents of bees captured on flowers are significantly more concentrated. In returning foragers, the concentration increases further to 38–40%, accompanied by a volume decrease. The doubling of sugar concentration suggests that nectar is regurgitated onto the tongue and evaporated during foraging and on the return flight. Processing of the dilute nectar into honey thus begins early, aided by low ambient humidities. This has implications for honeybee thermoregulation, water balance and energetics during foraging, and for the communication of nectar quality to recruits.     

Two-Exon Skipping within MLPH Is Associated with Coat Color Dilution in Rabbits

Coat color dilution turns black coat color to blue and red color to cream and is a characteristic in many mammalian species. Matings among Netherland Dwarf, Loh, and Lionhead Dwarf rabbits over two generations gave evidence for a monogenic autosomal recessive inheritance of coat colour dilution. Histological analyses showed non-uniformly distributed, large, agglomerating melanin granules in the hair bulbs of coat color diluted rabbits. We sequenced the cDNA of MLPH in two dilute and one black rabbit for polymorphism detection. In both color diluted rabbits, skipping of exons 3 and 4 was present resulting in altered amino acids at p.QGL[37-39]QWA and a premature stop codon at p.K40*. Sequencing of genomic DNA revealed a c.111-5C>A splice acceptor mutation within the polypyrimidine tract of intron 2 within MLPH. This mutation presumably causes skipping of exons 3 and 4. In 14/15 dilute rabbits, the c.111-5C>A mutation was homozygous and in a further dilute rabbit, heterozygous and in combination with a homozygous frame shift mutation within exon 6 (c.585delG). In conclusion, our results demonstrated a colour dilution associated MLPH splice variant causing a strongly truncated protein (p.Q37QfsX4). An involvement of further MLPH-associated mutations needs further investigations.     

Isolation and characterisation of the cell-wall fibres of carrot

Cell-wall fractions have been prepared from an alcohol-insoluble-residue of carrot root by treatment with (a) Pronase to remove the cytoplasmic proteins, (b) hot dilute acid and cold dilute alkali to give pectin-free residues, and (c) concentrated alkali to leave the α-cellulose and lignin. The purified cell-wall material still contained ∼ 1% protein and was composed mainly of cellulose, lignin, methyl-esterified galacturonic acid, and smaller amounts of galactose and arabinose. Methylation analysis of the insoluble residues indicated the presence, in order of decreasing concentration, of rhamnogalacturonan with the rhamnosyl residues carrying side chains at position 4, cellulose, (1→4)-linked galactan, (1→5)-linked arabinan, (1→4)-linked xylan, (1→4)-linked mannan, and xyloglucan.     

SYNERESIS AND SWELLING OF GELATIN

1. When solid blocks of isoelectric gelatin are placed in cold distilled water or dilute buffer of pH 4.7, only those of a gelatin content of more than 10 per cent swell, while those of a lower gelatin content not only do not swell but actually lose water. 2. The final quantity of water lost by blocks of dilute gelatin is the same whether the block is immersed in a large volume of water or whether syneresis has been initiated in the gel through mechanical forces such as shaking, pressure, etc., even in the absence of any outside liquid, thus showing that syneresis is identical with the process of negative swelling of dilute gels when placed in cold water, and may be used as a convenient term for it. 3. Acid- or alkali-containing gels give rise to greater syneresis than isoelectric gels, after the acid or alkali has been removed by dialysis. 4. Salt-containing gels show greater syneresis than salt-free gels of the same pH, after the salt has been washed away. 5. The acid and alkali and also the salt effect on syneresis of gels disappears at a gelatin concentration above 8 per cent. 6. The striking similarity in the behavior of gels with respect to syneresis and of gelatin solutions with respect to viscosity suggests the probability that both are due to the same mechanism, namely the mechanism of hydration of the micellæ in gelatin by means of osmosis as brought about either by diffusible ions, as in the presence of acid or alkali, or by the soluble gelatin present in the micellæ. The greater the pressures that caused swelling of the micellæ while the gelatin was in the sol state, the greater is the loss of water from the gels when the pressures are removed. 7. A quantitative study of the loss of water by dilute gels of various gelatin content shows that the same laws which have been found by Northrop to hold for the swelling of gels of high concentrations apply also to the process of losing water by dilute gels, i.e. to the process of syneresis. The general behavior is well represented by the equations: See PDF for Equation and See PDF for Equation where P ₁ = osmotic pressure of the soluble gelatin in the gel, P ₂ = stress on the micellæ in the gelatin solution before setting, K_e = bulk modulus of elasticity, V_o = volume of water per gram of dry gelatin at setting and V_e = volume of water per gram of gelatin at equilibrium.     

Effect of Bovine Manure on Cryptosporidium parvum Oocyst Attachment to Soil

The objective of this work was to assess the effect of dilute bovine manure (1.0% and 0.1%) versus that of no manure on attachment and subsequent detachment of Cryptosporidium parvum oocysts to soil. Manure enhanced the attachment of oocysts to soil particles; the maximum attachment was observed with 0.1% manure. Oocyst attachment was partially reversible; maximum detachment was observed with dilute manure. These results indicate that oocyst attachment to soil is substantially affected by bovine manure in a complex manner and should have implications for how oocysts may be transported through or over soils.     

Polyacrylamide gels with modified cross-linkages

The retention of low molecular weight proteins during electrophoresis through gradient polyacrylamide gels was improved when a gradient of N,N′,N″-triallyl citric triamide (TACT) was superimposed on the gradient of acrylamide and N,N′-methylenebisacrylamide (MBA). Gels cross-linked only with N,N′-(1,2-dihydroxyethylene)bisacrylamide (DHEBA) are soluble in dilute periodic acid or dilute aqueous solutions of bases. DHEBA cross-linked gradient gels have a smaller pore structure at high acrylamide concentrations and a more open structure at low acrylamide concentrations than gels cross-linked with MBA. Proteins labeled with tritium and carbon-14 were fractionated through DHEBA cross-linked gradient gels and the isotopes measured after solution of the gel with periodic acid. The mild solubilizing conditions enhanced isotope resolution. The characteristics of several cross-linking molecules are discussed and reasons advanced for the superiority of those with acrylamido end groups.     

Molecular weight and pH aspects of the efficacy of oligochitosan against methicillin-resistant Staphylococcus aureus (MRSA)

Oligochitosan samples varying in molecular weight (M_w) and having narrow polydispersities were prepared by means of depolymerization of chitosan in hydrochloric acid, and their antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) was measured at pH values 5.5-8.0. The antibacterial testing of oligochitosans obtained showed that oligochitosans having M_w in the range of 0.73-20.0 kDa could be used both at slightly acidic and neutral pH values, and that the activity against MRSA remained moderate for oligochitosan samples having M_w about 3-5 kDa even at slightly basic pH values. The self-assembling behavior of oligochitosan macromolecules in the dilute solution at various pH values as a function of chain length was investigated. At first it was shown that oligochitosans formed supramolecular aggregates in dilute solutions below the critical pH value 6.5. Despite the aggregation phenomenon, the formation of nano-sized aggregates did not prevent oligochitosan from demonstrating the bactiostatic activity.     

Subsurface Microbial Diversity in Deep-Granitic-Fracture Water in Colorado

A microbial community analysis using 16S rRNA gene sequencing was performed on borehole water and a granite rock core from Henderson Mine, a >1,000-meter-deep molybdenum mine near Empire, CO. Chemical analysis of borehole water at two separate depths (1,044 m and 1,004 m below the mine entrance) suggests that a sharp chemical gradient exists, likely from the mixing of two distinct subsurface fluids, one metal rich and one relatively dilute; this has created unique niches for microorganisms. The microbial community analyzed from filtered, oxic borehole water indicated an abundance of sequences from iron-oxidizing bacteria (Gallionella spp.) and was compared to the community from the same borehole after 2 weeks of being plugged with an expandable packer. Statistical analyses with UniFrac revealed a significant shift in community structure following the addition of the packer. Phospholipid fatty acid (PLFA) analysis suggested that Nitrosomonadales dominated the oxic borehole, while PLFAs indicative of anaerobic bacteria were most abundant in the samples from the plugged borehole. Microbial sequences were represented primarily by Firmicutes, Proteobacteria, and a lineage of sequences which did not group with any identified bacterial division; phylogenetic analyses confirmed the presence of a novel candidate division. This “Henderson candidate division” dominated the clone libraries from the dilute anoxic fluids. Sequences obtained from the granitic rock core (1,740 m below the surface) were represented by the divisions Proteobacteria (primarily the family Ralstoniaceae) and Firmicutes. Sequences grouping within Ralstoniaceae were also found in the clone libraries from metal-rich fluids yet were absent in more dilute fluids. Lineage-specific comparisons, combined with phylogenetic statistical analyses, show that geochemical variance has an important effect on microbial community structure in deep, subsurface systems.     

THE CONCENTRATION EFFECT IN NITELLA

A method distinguishing between the concentration effect due to the cell wall and that due to the protoplasm is described: the importance of this lies in the fact that if the protoplasm shows a concentration effect one or both ions of the salt must tend to enter its outer surface. Studies on the concentration effect of KCl with living protoplasm of Nitella show that when P.D. is plotted as ordinates and the logarithm of concentration as abscissæ the graph is not the straight line demanded in the ideal case by theory but has less slope and is somewhat concave to the axis of the abscissæ. With a variety of salts the dilute solution is positive, which indicates that the cation has a greater mobility in the protoplasm than the anion or that the partition coefficient of the cation (A_c) increases faster than that of the anion (A_a) as the concentration increases. If the result depended on the partition coefficients we should say that when A_c ÷ A_a increases with concentration the dilute solution is positive. When A_c ÷ A_a decreases as the concentration increases the dilute solution is negative. In either case the increase in concentration may be accompanied by an increase or by a decrease in the relative amount of salt taken up. Theoretically therefore there need be no relation between the sign of the dilute solution and the relative amount of salt taken up with increasing concentration. Hypothetical diagrams of the electrical conditions in the cell are given. If we define the chemical effect as the P.D. observed in leading off at two points with equivalent concentrations of different salts we may say that the chemical effect of the protoplasm is very much greater than that of the cell wall.     

Concentration in renal counterflow systems

In this paper earlier work on two-loop counterflow systems is extended to n-loop systems. It is shown that a large class of such systems in which exchange between the flow tubes is passive is unable to concentrate or dilute.     

Osmotic Transport across Cell Membranes in Nondilute Solutions: A New Nondilute Solute Transport Equation

The fundamental physical mechanisms of water and solute transport across cell membranes have long been studied in the field of cell membrane biophysics. Cryobiology is a discipline that requires an understanding of osmotic transport across cell membranes under nondilute solution conditions, yet many of the currently-used transport formalisms make limiting dilute solution assumptions. While dilute solution assumptions are often appropriate under physiological conditions, they are rarely appropriate in cryobiology. The first objective of this article is to review commonly-used transport equations, and the explicit and implicit assumptions made when using the two-parameter and the Kedem-Katchalsky formalisms. The second objective of this article is to describe a set of transport equations that do not make the previous dilute solution or near-equilibrium assumptions. Specifically, a new nondilute solute transport equation is presented. Such nondilute equations are applicable to many fields including cryobiology where dilute solution conditions are not often met. An illustrative example is provided. Utilizing suitable transport equations that fit for two permeability coefficients, fits were as good as with the previous three-parameter model (which includes the reflection coefficient, σ). There is less unexpected concentration dependence with the nondilute transport equations, suggesting that some of the unexpected concentration dependence of permeability is due to the use of inappropriate transport equations.     

Production of spent mushroom substrate hydrolysates useful for cultivation of Lactococcus lactis by dilute sulfuric acid, cellulase and xylanase treatment

Spent mushroom substrate (SMS) was treated with dilute sulfuric acid followed by cellulase and xylanase treatment to produce hydrolysates that could be used as the basis for media for the production of value added products. A L9 (3⁴) orthogonal experiment was performed to optimize the acid treatment process. Pretreatment with 6% (w/w) dilute sulfuric acid at 120 °C for 120 min provided the highest reducing sugar yield of 267.57 g/kg SMS. No furfural was detected in the hydrolysates. Exposure to 20 PFU of cellulase and 200 XU of xylanase per gram of pretreated SMS at 40 °C resulted in the release of 79.85 g/kg or reducing sugars per kg acid pretreated SMS. The dilute sulfuric acid could be recycled to process fresh SMS four times. SMS hydrolysates neutralized with ammonium hydroxide, sodium hydroxide, or calcium hydroxide could be used as the carbon source for cultivation of Lactococcus lactis subsp. lactis W28 and a cell density of 2.9 × 10¹¹ CFU/mL could be obtained. The results provide a foundation for the development of value-added products based on SMS.     

Ontogenesis and independent genetic control of the rat adenylate kinase isozymes (EC 2.7.4.3.)

The level of activity of cytoplasmic isozyme II of adenylate kinase (EC 2.7.4.3) appears to be genetically controlled in the rat (Rattus norvegicus). Adult animals of the Okamoto inbred strain exhibit a ninefold higher erythrocytic activity than the rats of the dilute agouti inbred strain. This difference seems to be due to two codominant autosomal alleles at a same locus. The study of the ontogeny of that enzyme in muscle in the two strains shows that the wellknown postnatal activity increase of that isozyme is reduced in the low activity (dilute agouti) strain. However, the mitochondrial isozyme III activity is not similarly regulated as no difference between the two strains has been observed.     

Superoxide dismutase and the oxygen enhancement of radiation lethality

Escherichia coli B were more susceptible to radiation lethality and showed a greater oxygen enhancement ratio when exposed in dilute suspension (1 × 10⁵ cells/ml) than when exposed in dense suspensions (1 × 10⁹ cells/ml). The oxygen enhancement, seen with dilute suspensions, was diminished by superoxide dismutase, catalase, mannitol, or histidine. Heat-denatured superoxide dismutase was without effect. The results are interpreted as indicating a role for O₂^? plus H₂O₂ in the oxygen enhancement of radiation lethality, and a scheme is proposed which is consistent with the observations.     

CHANGES OF APPARENT IONIC MOBILITIES IN PROTOPLASM : III. SOME EFFECTS OF GUAIACOL ON HALICYSTIS

Lowering the pH of sea water from 8.2 to 6.4 lowers the positive P.D. of Halicystis reversibly (this does not happen with Valonia). Exposure to sea water at pH 6.4 does not affect the apparent mobility of Na⁺ or of K⁺ (this agrees with Valonia). Guaiacol makes the P.D. of Halicystis less positive (in Valonia it has the opposite effect). Exposure to guaiacol does not reverse the effect of KCl in Halicystis which in this respect differs from Valonia. The P.D. can be changed from 66 mv. positive to 23 mv. negative by the combined action of KCl and guaiacol. Exposure to guaiacol affects Halicystis and Valonia similarly in respect to their behavior with dilute sea water. Normally the dilute sea water makes the P.D. more negative but after sufficient exposure to guaiacol dilute sea water either produces no change in P.D. or makes it more positive. In the latter case we may assume that the apparent mobility of Na⁺ has become greater than that of Cl^- as the result of the action of guaiacol. (Normally the apparent mobility of Cl^- is greater than that of Na⁺.) In Halicystis, as in Valonia and in Nitella, an organic substance can greatly change the apparent mobilities of certain inorganic ions (K⁺ or Na⁺).