Polysaccharide Produced by the Genus Pullularia: I. Production of Polysaccharide by Growing Cells

A dextranlike polysaccharide was found to be produced on substrates of sucrose, maltose, glucose, and fructose by growing cells of various strains of the genus Pullularia. The polysaccharide, obtainable in amounts as large as 2 to 3 g per 100 ml of culture medium using various carbohydrates as the carbon source, was soluble in cold water but not in 50% alcohol. The polysaccharide obtained had a α_d = +197.5° (c = 0.2 in water), and its molecular weight, determined by the light-scattering method, was found to be approximately 250,000.     

Conformational States of the Water-Soluble Fragment of Cytochrome b5. I. pH-Induced Denaturation

Cytochrome b ₅ is a membrane protein that comprises two fragments: one is water-soluble and heme-containing, and the other is hydrophobic and membrane-embedded. The function of electron transfer is performed by the former whose crystal structure is known; however, its conformational states when in the membrane field and interacting with other proteins are still to be studied. Previously, we proposed water–alcohol mixtures for modeling the effect of membrane surface on proteins, and used this approach to study the conformational behavior of positively charged cytochrome c as well as relatively neutral retinol-binding protein also functioning in the field of a negatively charged membrane. The current study describes the conformational behavior of the negatively charged water-soluble fragment of cytochrome b ₅ as dependent on pH. Decreasing pH was shown to transform the fragment state from native to intermediate, similar to the molten globule reported earlier for other proteins in aqueous solutions: at pH 3.0, the fragment preserved a pronounced secondary structure and compactness but lost its rigid tertiary structure. A possible role of this intermediate state in cytochrome b ₅ functioning is discussed.     

Robustness of the Rotary Catalysis Mechanism of F1-ATPase

F₁-ATPase (F₁) is the rotary motor protein fueled by ATP hydrolysis. Previous studies have suggested that three charged residues are indispensable for catalysis of F₁ as follows: the P-loop lysine in the phosphate-binding loop, GXXXXGK(T/S); a glutamic acid that activates water molecules for nucleophilic attack on the γ-phosphate of ATP (general base); and an arginine directly contacting the γ-phosphate (arginine finger). These residues are well conserved among P-loop NTPases. In this study, we investigated the role of these charged residues in catalysis and torque generation by analyzing alanine-substituted mutants in the single-molecule rotation assay. Surprisingly, all mutants continuously drove rotary motion, even though the rotational velocity was at least 100,000 times slower than that of wild type. Thus, although these charged residues contribute to highly efficient catalysis, they are not indispensable to chemo-mechanical energy coupling, and the rotary catalysis mechanism of F₁ is far more robust than previously thought.     

A physico-chemical study on the polysaccharide ulvan from hot water extraction of the macroalga Ulva.

Results of a study on the solution behaviour of the cell-wall polysaccharide named ulvan obtained from hot water extraction of a flour of Ulva ‘rigida’ are reported. In particular the spectroscopic properties and ion binding capacity of this charged polysaccharide were studied by circular dichroism and isothermal microcalorimetric titrations in order to gain information on the potential exploitation of this low cost biomass. A marked tendency of this polysaccharide to uptake water was evidenced by studying the proton spin-lattice relaxation times of the solvent, T₁, embedded in this highly charged polysaccharide.     

On the meaning of enzymatic superactivity in reverse micelles

Summary Two types of superactivity can be defined. One, is with respect to the activity for a fixed average substrate concentration in the water pool; the pushing of the charged substrate by the likewise charged micellar surface is responsible for the superactivity and its bell-shaped dependence on the hydration ratio. The other, is with respect to the activity in a bulk aqueous solution having a substrate concentration equal to a fixed overall concentration [S^–]_ov in the entire reverse micellar solution. In this case, the pushing effect, the constraint of a fixed [S^–]_ov and the partitioning of the substrate in the surfactant layer are responsible for the bell-shaped dependence. Superactivity exists for low substrate partitioning in the surfactant layer, subactivity for high partitioning.     

Effect of periodate oxidation on the polysaccharide content and microaggregate stability of rhizosphere and non-rhizosphere soils

Summary The relationship between the stability of soil microaggregates in water and the polysaccharide content was examined in rhizosphere and non-rhizosphere samples from a pot experiment using three soils that had grown peas, barley or grasses. The polysaccharide was oxidised and removed using 168h treatment with 0.02M periodate followed by 6h with 0.1M tetraborate. The decrease in polysaccharide content, measured as change in residual reducing sugars, was compared with the stability of soil microaggregates (ca 45m) in water, determined by a turbidimetric method.Total C, N and polysaccharide contents of rhizosphere soils were greater than those for the bulk soil, but the water stability of aggregates was not increased compared to unplanted controls. Periodate oxidation removed a large proportion (59–95%) of the polysaccharide and increased aggregated disruption, but there was no clear relationship between the two measurements. In rhizosphere soil, polysaccharides appreared to make less contribution to aggregate stability than polysaccharide in the bulk soil. The relatively small effect of rhizosphere polysaccharides is probably related to their presence as comparatively massive plant remains and debris; this contrasts with the decomposed and transformed material in the bulk soil.     

147Characterizing the conformational space of two disordered peptides in different solutions

Amyloid fibrils formed by peptides found in semen have been shown to enhance HIV infectivity in vitro. The first of these peptides to be identified was the 248–286 fragment of prostatic acid phosphatase (PAP_248–286) (Munich et al., 2007). PAP_248–286 is highly cationic, and its fibrils might facilitate infection by decreasing the electrostatic repulsion between the negatively charged surfaces of the virus and the target cell. Whereas PAP_248–286 can easily form fibrils in seminal fluid, it needs rapid agitation in other environments, and certain ions have been shown to be critical for its assembly into fibrils (Olsen et al., 2012). However, mutation of the positively charged residues to alanine results in a peptide (PAP_248–286Ala) that can more easily form fibrilar aggregates. We studied PAP_248–286 and PAP_248–286Ala fibril formation in water and water?+?NaCl environments. While PAP_248-286Ala can efficiently form fibrils in both water and water?+?NaCl, PAP_248-286 can only do so in a water?+?NaCl solution. The inability of PAP_248–286 to form fibrils in water could be due solely to repulsion between the positively charged peptides, an effect that might be diminished by the presence of salt. However, it is also possible that the explanation lies in PAP_248–286’s failure to populate conformations that can easily lead to ordered aggregates. To answer this question, using molecular dynamics simulations, we characterized the ensemble of conformations populated by the two peptides in water and water?+?NaCl environments. The results indicate that PAP_248-286Ala favors contacts that stabilize a strand-turn-strand, or β-arch, motif around P31, the only proline residue in the sequence. Because β-arches are a common feature in amyloid fibrils, and because it is very unlikely that a proline residue would be in any position other than the β-arch, we expect the formation of this motif to be the rate-limiting step in PAP_248–286Ala / PAP_248–286 fibril formation. Moreover, the contacts stabilizing the β-arch would bring positively charged residues into contact in PAP_248–286, which, consistent with the experimental results, would be facilitated by the presence of negative ions. To summarize, we have tried to understand if the inability of PAP_248–286 to efficiently form fibrils in water is only due to a slower aggregation caused by electrostatic repulsion between the positively charged peptides. Our data suggest that this effect is also due to electrostatic repulsion between the residues within each monomeric peptide, which prevents PAP_248–286 from populating conformations that would lead to ordered aggregates.     

Polysaccharide synthesis by Phanerochaete chrysosporium during degradation of kraft lignin

Summary Phanerochaete chrysosporium (Sporotrichum pulverulentum) produced an extracellular glucan type polysaccharide when grown in a chemostat under nitrogen limitation. When cells were transferred to a standing mode of cultivation in the presence of excess glucose (6 gl^–1), the amount of non-glucose total carbohydrates in the culture increased from 0.58 gl^–1 to 1.76 gl^–1 during 15 day experiments. The change in total carbohydrates was due to an increase in extracellular and cell-bound glucan type polysaccharide. This increase occured simultaneously with formation of mycelial mats and appearance of ligninolytic activity. When the cultures were agitated under atmospheric oxygen rather than 100% O₂, their non-glucose total carbohydrate content increased to 2.15 gl^–1 in 4 days. The excess polysaccharide formation had an inhibitory effect on lignin degradation as more lignin was degraded by cells with lower polysaccharide content. The lignin that was associated with cells after the degradation had stopped could be further degraded by new active cells.     

Influence of growth conditions on production of capsular and extracellular polysaccharides byRhizobium leguminosarum

The influence of growth rate and medium composition on exopolymer production byRhizobium leguminosarum was studied. When grown in medium containing 10g/l mannitol and 1g/l glutamic acid,Rhizobium leguminosarum biovartrifolii TA-1 synthesized up to 2.0g/l of extracellular polysaccharide (EPS), and up to 1.6g/l of capsular polysaccharide (CPS). Under non-growing cell conditions in medium without glutamic acid, CPS synthesis by strain TA-1 could proceed to 2.1g/l, while EPS-production remained relatively low (0.8g/l). Maximal CPS-yield was 2.9g CPS/l medium in a medium containing 20g/l mannitol and 2g/l glutamic acid. TheEPS-deficient strain R. leguminosarum RBL5515,exo4::Tn5 was able to produce CPS to similar levels as strain TA-1, but CPS-recovery was easier because of the low viscosity of the medium and growth of the cells in pellets. With strain TA-1 in nitrogen-limited continuous cultures with a constant biomass of 500mg cell protein/l, EPS was the most abundant polysaccharide present at every dilution rate D (between 0.12 and 0.02 h^–1). The production rates were 50–100mg/g protein/h for EPS and 15–20mg/g protein/h for CPS. Only low amounts of cyclic -(1,2)-glucans were excreted (10–30 mg/l) over the entire range of growth rates.Abbreviations bv biovar - CPS capsular polysaccharide - EPS extracellular polysaccharide - HM_r high molecular mass - LM_r low molecular mass - YEMCR Yeast Extract-Mannitol-Congo Red agar     

Determination of the distribution of constituent disaccharide units within the chain near the linkage region of shark-cartilage chondroitin sulfate C

A method for analyzing the distribution of constituent disaccharide units within the chain near the linkage region of chondroitin sulfate has been developed. The method consists of (a) chemical modification of the reducing terminal residue in the polysaccharide by a 2-(2,4-dinitrophenylamino)ethylamino (DNP-AEA) group, (b) controlled fragmentation of the DNP-AEA-labeled polysaccharide with chondroitinase AC-I, followed by separation of the digestion products into the DNP-AEA-labeled fragments and unlabeled fragments on octyl-Sepharose CL-4B gel, (c) fractionation of the DNP-AEA-labeled fragments into fractions having different chain-lengths of Sephadex G-100 (superfine), and (d) determination of the disaccharide unit composition of the de-dinitrophenylated products (AEA-labeled fragments) by the method combining chondroitinase AC-II treatment with HPLC analysis. A preparation of shark cartilage chondroitin sulfate C, which has been characterized well with regard to molecular species (M_r 48 000; average number of repeating disaccharide units (dp_av) 93–94; consisting of chondroitin 6-sulfated 22.5%, disulfate (D type) 10.3%, and nonsulfated units 0.4%), was analyzed by the above method. On the basis of the data obtained, distribution features of the dissacharide units within the chain near the linkage region of the polysaccharide (dp_av 27) were estimated. It was, however, difficult to propose a final primary sequence of the polysaccharide chain, although there was a definite trend towards an enrichment of 4-sulfated and nonsulfated dissacharide residues in the area close to the linkage region (dp_av 3–9 or 11). This was apparent together with an enrichment of 6-sulfated and disulfated disaccharide residues in the area distant from the linkage region (dp_av 11 of 13–27).     

Liver Freezing Response of the Freeze-Tolerant Wood Frog, Rana sylvatica, in the Presence and Absence of Glucose. II. Mathematical Modeling

The “two-step” low-temperature microscopy (equilibrium and dynamic) freezing methods and a differential scanning calorimetry (DSC) technique were used to assess the equilibrium and dynamic cell volumes in Rana sylvatica liver tissue during freezing, in Part I of this study. In this study, the experimentally determined dynamic water transport data are curve fit to a model of water transport using a standard Krogh cylinder geometry (Model 1) to predict the biophysical parameters of water transport: L_pg = 1.76 μm/min-atm and E_Lp = 75.5 kcal/mol for control liver cells and L_pg[cpa] = 1.18 μm/min-atm and E_Lp[cpa] = 69.0 kcal/mol for liver cells equilibrated with 0.4 M glucose. The DSC technique confirmed that R. sylvatica cells in control liver tissue do not dehydrate completely when cooled at 5°C/min but do so when cooled at 2°C/min. Cells also retained twice as much intracellular fluid in the presence of 0.4 M glucose than in control tissue when cooled at 5°C/min. The ability of R. sylvatica liver cells to retain water during fast cooling (≥5°C/min) appears to be primarily due to its liver tissue architecture and not to a dramatically lower permeability to water, in comparison to mammalian (rat) liver cells which do dehydrate completely when cooled at 5°C/min. A modified Krogh model (Model 2) was constructed to account for the cell–cell contact in frog liver architecture. Using the same biophysical permeability parameters obtained with Model 1, the modified Krogh model (Model 2) is used in this study to qualitatively explain the experimentally measured water retention in some cells during freezing on the basis of different volumetric responses by cells directly adjacent to vascular space versus cells at least one cell removed from the vascular space. However, at much slower cooling rates (1–2°C/h) experienced by the frog in nature, the deciding factor in water retention is the presence of glucose and the maintenance of a sufficiently high subzero temperature (≥−8°C).     

Evidence for permanent water channels in the basolateral membrane of an ADH-sensitive epithelium

Summary The transepithelial water permeability in frog urinary bladder is believed to be essentially dependent on the ADH-regulated apical water permeability. To get a better understanding of the transmural water movement, the diffusional water permeability (P _d) of the basolateral membrane of urinary bladder was studied. Access to this post-luminal barrier was made possible by perforating the apical membrane with amphotericin B. The addition of this antibiotic increasedP _d from 1.12±0.10×10^–4 cm/sec (n=7) to 4.08±0.33×10^–4 cm/sec (n=7). The effect of mercuric sulfhydryl reagents, which are commonly used to characterize water channels, was tested on amphotericin B-treated bladders. HgCl₂ (10^–3 m) decreasedP _d by 52% andpara-chloromercuribenzoic acid (pCMB) (1.4×10^–4 m) by 34%. The activation energy for the diffusional water transport was found to increase from 4.52±0.23 kcal/mol (n=3), in the control situation, to 9.99±0.91 kcal/mol (n=4) in the presence of 1.4×10^–4 m pCMB. Our second approach was to measure the kinetics of water efflux, by stop-flow light scattering, on isolated epithelial cells from urinary bladders.pCMB (0.5 or 1.4×10^–4 m) was found to inhibit water exit by 91±2%. These data strongly support the existence of proteins responsible for water transport across the basolateral membrane, which are permanently present.     

Molecular Characteristics of Water-soluble Polysaccharide Extracted from Jelly Fig (Ficus awkeotsang Makino) Seeds

The molecular characteristics of polysaccharide obtained by extracting with water from jelly fig (Ficus awkeotsang Makino) seeds were elucidated by measuring the weight-average molecular weight (M_w) and radius of gyration (R_G), indicating the molecular expanse, by the light-scattering method.

The M_w and R_G values of the water-soluble jelly fig polysaccharide were 84–130 × 10⁴ and 240–450 mm, respectively, these values being larger than those of commercial LM pectin and HM pectin. In addition, the M_w and R_G values of the water-soluble jelly fig polysaccharide initially increased after being extracted, indicating the highest values 5 hours after the extraction, and thereafter decreased. These changes in the time-course of the molecule reflected well the changes with time in the mechanical characteristics and network structure of the water-soluble jelly fig polysaccharide gel. Exponent α in the expression was found to be 0.37. From these results, the conformation of the water-soluble jelly fig polysaccharide molecule after association by the contained inorganic elements proved to be of globular form rather than a random coil shape as a result of contraction of the molecule.     

Seasonal changes in apparent hydraulic conductance and their implications for water use of European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) and sessile oak [<Emphasis Type="Italic">Quercus petraea</Emphasis> (Matt.) Liebl] in South Europe

The water status of Fagus sylvatica L. and Quercus petraea (Matt) Liebl. was analysed during a cycle of progressive natural drought in southern Europe. Predawn (Ψ_pd) and midday water potential were measured in transpiring (Ψ_leaf) and non-transpiring leaves (Ψ_xyl). Furthermore, photosynthesis (A), stomatal conductance to water vapour (g_s) and sap flow (F_d) were recorded on the same dates. Apparent leaf specific hydraulic conductance in the soil–plant–air continuum (K_h) and whole tree hydraulic conductance (K_hsf) were calculated by using the simple analogy of the Ohm’s law. K_h was estimated at different points in the pathway as the ratio between transpiration (E) in the uppermost canopy leaves at midday and the gradient of water potential in the different compartments of the continuum soil–roots–stem–branches–leaves. There was a progressive decrease in water potential measured on non-transpiring leaves at the base of tree crown in both species (Ψ^l_xyl) from the beginning of the growing season to the end of summer. A similar decrease was shown in shoot water potential (Ψ^u_xyl) at the uppermost canopy. Predawn water potential (Ψ_pd) was high in both species until late July (28 July); afterwards, a significant decrease was registered in F. sylvatica and Q. petraea with minimum values of −0.81±0.03 and −0.75±0.06 MPa, respectively, by 15 September. In both species, leaf specific hydraulic conductance in the overall continuum soil–plant–air (K_h) decreased progressively as water stress increases. Minimum values of K_h and K_hsf were recorded when Ψ_pd was lower. However, Q. petraea showed higher K_h than F. sylvatica for the same Ψ_pd. The decrease in K_h with water stress was mainly linked to its fall from the soil to the lowermost canopy (K_srs). Nevertheless, a significant resistance in the petiole–leaf lamina (K_pl) was also recorded because significant differences in all dates were found on Ψ between transpiring and non-transpiring leaves from the same shoot. The decline in K_h was followed by an increase in stomatal control of daily water losses through the decrease of stomatal conductance to water vapour (g_s) during the day. It promoted a seasonal increase in the stomatal limitation to carbon dioxide uptake for photosynthesis (A). These facts were more relevant in F. sylvatica, which had concurrently a higher decline in water use at the tree level than Q. petraea. The results showed a strong coupling in F. sylvatica and Q. petraea between processes at leaf and tree level. It may be hypothesised a role of specific hydraulic conductance not only in the regulation of water losses by transpiration but also of carbon uptake.     

A (1-->3)-beta-d-Glucan Isolated From Zea Shoot Cell Wall Preparations

A small quantity of (1→3)-β-d-glucan was extracted with a (1→3),(1→4)-β-d-glucan by hot water after treatment of the insoluble fraction of a buffer homogenate of Zea shoots with 3 molar LiCl. An ammonium sulfate precipitation procedure effected a separation of the (1→3)-β-d-glucan from the more prevalent (1→3),(1→4)-β-d-glucan. The minor component polysaccharide precipitated at a concentration of 20% ammonium sulfate (w/v) and was, as a consequence of precipitation, rendered insoluble in water. The insoluble products were dissolved in 1 normal NaOH followed by neutralization with CH₃COOH. The purified polysaccharide accounted for approximately 0.3% of total hot water extract. It consisted mostly of glucose and its average mol wt was estimated to be about 7.0 × 10⁴, based on elution from a calibrated Sepharose CL-4B column. Methylation analysis and enzymic hydrolysis or partial acid-hydrolysis of the polysaccharide followed by analysis of the hydrolysate showed that the polysaccharide consisted of (1→3)-β-linked glucose residues.     

Isolation and characterization of a galactorhamnan polysaccharide from the seed coat of Canavalia ensiformis that is toxic to the cowpea weevil (Callosobruchus maculatus)

We have isolated a water-soluble polysaccharide from the Jack bean [Canavalia ensiformis (L) DC] seed coat that was shown to be highly detrimental to larval development of the cowpea weevil (Callosobruchus maculatus) (Coleoptera: Bruchidae). Determination of the composition and structure of this polysaccharide showed that it is a galactorhamnan with an M_w of 883.0, containing 92% rhamnose and 8% galactose. The polymer is formed by a main chain of rhamnose (1to2) substituted at O-4 by galactose nonreducing end-units. Immunolocalisation by light and electron microscopy showed that this polysaccharide is localised in the innermost cell layer of the seed coat and also in cotyledon tissues in the cytoplasm space. The presence of this toxic polysaccharide in the testa of a non-host seed may have been important for the evolutionary discrimination of legume seeds by bruchids.     

Temperature effects on intra- and extracellular acid-base status in the American locust,Schistocerca nitens

Summary This study examined the effect of temperature on hemolymph and intracellular acid-base status in the locust,Schistocerca nitens. Hemolymph pH decreased with temperature by 0.017 pH units·°C^–1 above 25°C, but was stable at lower temperatures. Average intracellular pH (pH_i, calculated from CO₂ distribution) decreased by approximately 0.018 pH units·°C^–1, in accordance with predictions for preservation of relative alkalinity and protein charge state. DMO was found to be unsuitable for use as an in vivo pH_i marker in locusts due to rapid metabolism and excretion of this compound. Hemolymph pH regulation when temperature changed was accomplished by a combination of variation ofP _CO2 and [HCO ₃ ^– ], with changes in [HCO ₃ ^– ] predominating. Digestive tracts contained a large portion of total body water (over 30%), and total body CO₂ (over 40%). Variation in [HCO ₃ ^– ] may dominate pH regulation in locusts because of the relatively large size of the digestive tract and its powerful acid-base transporting capacities.Abbreviations C _car carcass total CO₂ - C _hem hemolymph total CO₂ - C _in intracellular total CO₂ - C _tot total CO₂ - DMO 5,5 dimethyl-2,4-oxazolidinedione - ECW extracellular water mass - ECWF fraction of total body water which is extracellular - ICW intracellular water mass - ICWF fraction of total body water which is intracellular - PCA perchloric acid - S dissolved CO₂ - TBW total body water - TV tracheal volume     

Permeability parameters of the toad isolatedstratum corneum

Summary A technique for isolating thestratum corneum from the subjacent layers of the epithelium was developed which permits studying thestratum corneum as an isolated membrane mounted between half-chambers. The method basically consists of an osmotic shock induced by immersing a piece of skin in distilled water at 50°C for 2 min. When the membrane is bathed on each surface by NaCl-Ringer's solution, its electrical resistance is 14.1±1.3 cm² (n=10). This value is about 1/100 of the whole skin resistance in the presence of the same solution. The hydraulic filtration coefficient (L _p ) measured by a hydrostatic pressure method, with identical solutions on each side of the membrane, is 8.8×10^–5±1.5×10^–5 cm sec^–1 atm^–1 (n=10) in distilled water and 9.2×10^–5±1.4×10^–5 cm sec^–1 atm^–1 (n=10) in NaCl-Ringer's solution. These values are not statistically different and are within the range of 1/80 to 1/120 of the whole skinL _p . Thestratum corneum shows an amphoteric character when studied by KCl diffusion potentials at different pH's. The membrane presents an isoelectric pH of 4.6±0.3 (n=10). Above the isoelectric pH the potassium transport number is higher than the chloride transport number; below it, the reverse situation is valid. Divalent cations (Ca⁺⁺ or Cu⁺⁺) reduce membrane ionic discrimination when the membrane is negatively charged and are ineffective when the membrane fixed charges are protonated at low pH.     

Enhanced shear protection and increased production of an anti-tumor polysaccharide by Agaricus blazei in xanthan-supplemented cultures

Xanthan supplementation provided shear protection and stimulated polysaccharide production by Agaricus blazei. In xanthan-free cultures, the optimal cell yield, 0.63 g biomass g^–1 glucose, and product yield, 0.19 g polysaccharide g^–1 glucose, were, respectively, when the critical impeller tip speed was 50.3 cm s^–1 and 100.5 cm s^–1. Furthermore, the critical impeller tip speed of cell yield shifted from 50.3 cm s^–1 to 100.5 cm s^–1 with the supplementation of 1 g xanthan l^–1. Maximum specific product yield, namely 0.74 g polysaccharide g^–1 biomass, was achieved with inlet air supply of 3% O₂ and impeller tip speed of 100.5 cm s^–1.     

Chemical characterization and radioprotective effect of polysaccharide from <Emphasis Type="Italic">Monostroma angicava</Emphasis> (Chlorophyta)

Polysaccharide from the green alga Monostroma angicava was extracted with boiling water and was purified by ion-exchange and size-exclusion column chromatography. The radioprotective effect of the polysaccharide was investigated in mice. The results show that polysaccharide from M. angicava has a different chemical composition to other Chlorophyta having a high rhamnose – containing sulfated polysaccharide. The sulfate ester content was estimated to be 21.8%. When the polysaccharide was applied to BALB/c mice following whole-body X-ray irradiation the counts of leukocytes, thrombocytes and erythrocytes recovered more rapidly in the polysaccharide treated mice after irradiation. In the irradiated mice, the polysaccharide significantly increased the spleen index, natural killer cytostatic activity and the transformation response of splenic lymphocytes. The present observations suggest that polysaccharide from M. angicava led to leukocytogensis and hematopoetic activation in mice after irradiation and that the biological response might be caused by immune activation.