Different Concentrations Of Mannitol Research Articles

Understanding the impact of mannitol on physical stability and aerosolization of spray-dried protein powders for inhalation

Pulmonary delivery of protein-based therapeutics, including antibodies, is a promising option for treating respiratory diseases. Spray drying is a widely used method for producing dry powder formulations with mannitol being a commonly used excipient for these inhalation formulations. There is limited research available concerning the utilization of mannitol as an excipient in the spray drying of proteins and its impact on aerosol performance. This study highlights the importance to understand mannitol’s potential role and impact in this context. To investigate the impact of mannitol on physical stability and aerosolization of spray-dried protein formulations, bovine serum albumin (BSA) was employed as a model protein and formulated with different concentrations of mannitol via spray drying. The spray-dried solids were characterized for their particle size using Malvern mastersizer and aerodynamic particle size using next generation impactor (NGI). Additionally, the solids were characterized with solid-state Fourier-transform infrared spectroscopy (ssFTIR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and solid-state nuclear magnetic resonance spectroscopy (ssNMR) to analyze the change in their secondary structure, crystallinity, particle morphology, and protein-excipient interaction, respectively. Size exclusion chromatography (SEC) was used to investigate changes in monomer content resulting from storage under stressed condition of 40 °C. Protein formulations containing more than 33 % mannitol by weight showed crystallization tendencies, causing an increase in monomer loss over time. ssNMR data also showed mixing heterogeneity of BSA and mannitol in the formulations with high mannitol contents. Futhermore, fine particle fraction (FPF) was found to decrease over time for the formulations containing BSA: Mannitol in the ratios of 2:1, 1:2, and 1:5, due to particle agglomeration induced by crystallization of mannitol. This study underscores the significant influence of excipients such as mannitol on the aerosol performance and storage stability of spray-dried protein formulations.

In vitro multiplication of lulo (Solanum quitoense Lamarck) for preservation purposes

The objective of the present study was to evaluate the effect of treatment, temperature and time using the minimum growth technique under in vitro conditions on stems with a length of 2 mm of Solanum quitoense. There were 8 treatments with different concentrations of mannitol, sucrose and Murashige and Skoog(1962) (0 ,5g L-1, 10 g L-1, 15 g L-1, 20 g L-1, 25 g L-1, 30 g L-1,30 g L-1), the experiments were placed in a room at 25 ºC and another at 21 ºC, the growth of the stem was recorded every fifteen days. The Generalized Linear Model showed that the treatments with the best results were those using 20 g L -1 and 30 g L-1 of mannitol in S. quitoense, which reduced in vitro growth in a remarkable way, preserving the characteristics of subsistence and vigor at a temperature of 21 ºC, while the applied concentrations of sucrose promoted rapid growth of the stem and shoots

Quartz Crystal Microbalance with Dissipation Monitoring of Dynamic Viscoelastic Changes of Tobacco BY-2 Cells under Different Osmotic Conditions.

The plant cell mechanics, including turgor pressure and wall mechanical properties, not only determine the growth of plant cells, but also reflect the functional and structural changes of plant cells under biotic and abiotic stresses. However, there are currently no appropriate techniques allowing to monitor the complex mechanical properties of living plant cells non-invasively and continuously. In this work, quartz crystal microbalance with dissipation (QCM-D) monitoring technique with overtones (3–9) was used for the dynamic monitoring of adhesions of living tobacco BY-2 cells onto positively charged N,N-dimethyl-N-propenyl-2-propen-1-aminiumchloride homopolymer (PDADMAC)/SiO2 QCM crystals under different concentrations of mannitol (CM) and the subsequent effects of osmotic stresses. The cell viscoelastic index (CVIn) (CVIn = ΔD⋅n/ΔF) was used to characterize the viscoelastic properties of BY-2 cells under different osmotic conditions. Our results indicated that lower overtones of QCM could detect both the cell wall and cytoskeleton structures allowing the detection of plasmolysis phenomena; whereas higher overtones could only detect the cell wall’s mechanical properties. The QCM results were further discussed with the morphological changes of the BY-2 cells by an optical microscopy. The dynamic changes of cell’s generated forces or cellular structures of plant cells caused by external stimuli (or stresses) can be traced by non-destructive and dynamic monitoring of cells’ viscoelasticity, which provides a new way for the characterization and study of plant cells. QCM-D could map viscoelastic properties of different cellular structures in living cells and could be used as a new tool to test the mechanical properties of plant cells.

Chloroplast Localized FIBRILLIN11 Is Involved in the Osmotic Stress Response during Arabidopsis Seed Germination.

Simple SummaryThe FIBRILLIN11 (FBN11) of Arabidopsis has a lipid-binding FBN domain and a kinase domain. FBN11 is present in chloroplasts and is involved in salt and osmotic stress responses during seed germination. In mannitol, the seed germination rate of the fbn11 mutants significantly reduced compared to that of the wild type. The ABA-dependent and -independent stress response regulating genes were differentially expressed in fbn11 mutants and wild-type when grown in mannitol supplemented medium. These results suggest that chloroplast localized FBN11 is involved in mediating osmotic stress tolerance through the signaling pathway that regulates the stress response in the nucleus.Plants live in ever-changing environments, facing adverse environmental conditions including pathogen infection, herbivore attack, drought, high temperature, low temperature, nutrient deficiency, toxic metal soil contamination, high salt, and osmotic imbalance that inhibit overall plant growth and development. Plants have evolved mechanisms to cope with these stresses. In this study, we found that the FIBRILLIN11 (FBN11) gene in Arabidopsis, which has a lipid-binding FBN domain and a kinase domain, is involved in the plant’s response to abiotic stressors, including salt and osmotic stresses. FBN11 protein localizes to the chloroplast. FBN11 gene expression significantly changed when plants were exposed to the abiotic stress response mediators such as abscisic acid (ABA), sodium chloride (NaCl), and mannitol. The seed germination rates of fbn11 homozygous mutants in different concentrations of mannitol and NaCl were significantly reduced compared to wild type. ABA-dependent and -independent stress response regulatory genes were differentially expressed in the fbn11 mutant compared with wild type when grown in mannitol medium. These results suggest a clear role for chloroplast-localized FBN11 in mediating osmotic stress tolerance via the stress response regulatory signaling pathway in the nucleus.

Functional Characteristics Analysis of Dehydrins in Larix kaempferi under Osmotic Stress.

Dehydrins (DHN) belong to the late embryogenesis abundant II family and have been found to enhance plant tolerance to abiotic stress. In the present study, we reported four DHNs in Larix kaempferi (LkDHN) which were identified from the published transcriptome. Alignment analysis showed that these four LkDHNs shared close relationships and belonged to SK3-type DHNs. The electrophoretic mobility shift assay indicated that these four LkDHNs all possess sequence-independent binding capacity for double-strands DNAs. The subcellular localizations of the four LkDHNs were in both the nucleus and cytoplasm, indicating that these LkDHNs enter the nucleus to exert the ability to bind DNA. The preparation of tobacco protoplasts with different concentrations of mannitol showed that LkDHNs enhanced the tolerance of plant cells under osmotic stress. The overexpression of LkDHNs in yeasts enhanced their tolerance to osmotic stress and helped the yeasts to survive severe stress. In addition, LkDHNs in the nucleus of salt treated tobacco increased. All of these results indicated that the four LkDHNs help plants survive from heavy stress by participating in DNA protection. These four LKDHNs played similar roles in the response to osmotic stress and assisted in the adaptation of L. kaempferi to the arid and cold winter of northern China.

Effect of Drought-induced Stress on Seed Germination and Seedling Growth of Zea mays L.

Background: Drought is one of the major abiotic factors leading to diminishing growth, development and productivity of plants worldwide. Considering that germination is the first phase of growth which in large measure determines plant quality and yield, knowing the effects of different factors on this process is of major importance. This paper studies the effect of drought-induced stress on seed germination and seedling growth of Zea mays L. (the Sweet corn and the hybrid Pioneer B23). Methods: The effect of water stress was caused by different concentrations of mannitol: 5%, 10% and 20%. In the control, we used distilled water. The germination test was performed in three trials of 45 seeds each. The germination percentage, germination potential, drought resistance index were calculated at 3, 5 and 7 days. Growth of seedlings and biomass content were calculate at 14 days.Result: The results show significant differences between the variety and hybrid examined. The pioneer B23 seed germinated in larger number and more quickly. The Sweet corn variety seedling growth was completely absent after treatment with mannitol. The observed difference is certainly not just a consequence of higher mannitol concentrations, but also a difference in the water-retention capability of the variety and hybrid studied.

Effects of different concentrations of mannitol on gene expression in Stevia rebaudiana Bertoni.

Stevia rebaudiana Bertoni is one of the most important herbal sweetener plants from Asteracea family that have a lot of Steviol glycosides. Among different methods, tissue culture is the best way with high efficiency that is useful for studying stress tolerance mechanisms to obtain drought tolerance of stevia. For this purpose, different concentrations of mannitol (0, 10, 20, 30, 40, 50 mg/l) were used as various treatments in the culture medium of stevia. According to the results, the highest level of UGT85C2 gene expression (1.181 Total lab unit) was seen in plants grown under 30 mg/l mannitol treatment and the lowest level of this gene expression (0.603 Total lab unit) was observed under 40 mg/l mannitol treatment. However, the highest level of KO gene expression (1.323 Total lab unit) was observed under 20 mg/l mannitol. It shows stevia growth is affected by osmotic stress. Water deficiency has a negative impact on Stevia. However, the expression of genes had increased by particular mannitol concentrations. Actually, stevia can survive under various abiotic stresses.

FORMULATION AND EVALUATION OF ORODISPERSIBLE TABLETS OF DONEPEZIL HYDROCHLORIDE USING MODIFIED POLYSACCHARIDES

ABSTRACT The objective of the study was to prepare and evaluate orodispersible tablets of Donepezil Hydrochloride (DPH) using natural modified polysaccharides such as modified karaya gum and modified agar with glycine and mannitol. The prepared formulations were compared with Kyron T-314, super disintegrant, spray dried lactose, diluent for improvement in DT and other ODT parameters. FTIR studies revealed no interaction between DPH and excipients. Precompression parameters for all formulations were found to be satisfactory. The oral dispersible tablets formulated using modified agar with glycine showed better disintegration time compared to modified karaya gum formulations. Different concentrations of mannitol and glycine were used in the formulation to study the improvement in the DT. The glycine formulations with modified agar gave better ODT parameters than modified karaya gum with mannitol and glycine formulations. The optimized formulations of modified agar with glycine in different concentrations were prepared with spray dried lactose as diluent and compared with formulations of Kyron T-314 as superdisintegrant with spray dried lactose as diluent. The results of lactose and spray dried lactose as diluents in these formulations did not show any significant difference in ODT evaluation parameters. The formulations were optimized using ODT parameters such as disintegration time, wetting time, water absorption ratio and other physicochemical evaluation parameters. The accelerated stability studies of optimized formulation did not show significant changes compare to initial physicochemical evaluation parameters to conclude, modified polysaccharides with glycine can be used as superdisintegrant, which may be a cost effective alternative in comparison to synthetic superdisintegrant like Kyron T-314.

Water-deficit tolerance induction during germination of Jalo Precoce bean (Phaseolus vulgaris L.) cultivar

Bean (Phaseolus vulgaris L.) cultivars are susceptible to water stress, especially during germination. Salicylic acid and thermal shock improve tolerance level in this plant to different kinds of stresses. However, in the present work, effects of cold shock and salicylic acid alone or combined on germinating beans under imposed water deficit were evaluated. Bean seeds from the Jalo Precoce cultivar were imbibed either in water or in salicylic acid for 24 h. After treatment, lots were divided and exposed to cold shock (7 °C) for another 24 h. The seeds were then placed on paper rolls imbibed with different concentrations of mannitol to impose a water deficit on them. They were evaluated for germination; seedling vigour; dry and total weights and length of shoot root; superoxide dismutase activity and proline content. Proline accumulates as a response to water-deficit stress, and SA alone or combined with cold shock improves this response. The use of SA increases many of the physiological variables than cold shock and decreases the antioxidant activity of SOD.

Establishment of Efficient System for Isolation and Manipulation of Single Protoplasts Containing Aposporous Embryo Sac Initial Cell in Guinea Grass (Panicum maximum)

Aims: In order to do the molecular analysis of mechanism of aposporous embryo sac initial cell (AIC) appearance, as the first step, we attempted to establish the system of isolating and manipulating single cells containing AIC using different methods in guinea grass (Panicum maximum). Original Research Article British Biotechnology Journal, 4(9): 980-989, 2014 981 Study Design: At first, single protoplasts were isolated from the ovaries staged in different developmental stages using different pre-treatments and different concentrations of enzyme solutions on ovaries; Based on it, the single protoplasts containing AIC were manipulated with ultra particle electronic syringe picopipet (UPESP) machine set onto microscope. Place and Duration of Study: Faculty of Environmental and Horticultural Science, Minami Kyushu University, between June 2012 and December 2013. Methodology: The ovary of facultatively apomictic guinea grass (Panicum maximum) was used as materials in this study for single protoplast isolation. The ovaries were classified and collected from young buds and flowers staged in different developmental stages, according to the colors of stigma and the ovary length. And then, the ovaries were pre-treated with needle into different shapes, and treated with different kinds of enzyme solution with different concentrations of mannitol to increase efficiency of protoplast isolation. In final, the single protoplasts containing AIC isolated from different stages of ovaries were manipulated by handle control. Results: 1) The ovaries in different stages of before AIC appearance, AIC appearance, and AIC-derived embryo sac formation were collected successfully and respectively, indicating that the stigma colors and length of ovaries are proportionate to stages of ovary mature. And single protoplasts containing AIC were isolated from the ovaries staged in white to yellow color. 2) The ovaries be flooded in enzyme solution, were pre-treated with needle in 4 types, that is, (1) Cut in micropylar end; (2) Cut in chalazal end; (3) Cut in middle part; (4) after 1hr of (3) treatment, cut in micropylar end. As a result, the efficiency of protoplast isolation of (3) and (4) was 1-2 hrs shorter than that of (1) and (2). 12%, 11%, 10% and 9% were proper enzyme concentrations for obtaining perfect shingle protoplasts from the ovaries with white, yellow, peach and purple colors, respectively. 3) The single protoplasts containing AIC were collected and manipulated with UPESP in the performance of controlled aspiration and spit. Conclusion: In this study, in order to do molecular analysis of the mechanism of AIC appearance, we focus on that, the key points were to isolate AIC single protoplasts from apomictic guinea grass using different methods, and then to establish the method of controlling a single protoplast using UPESP machine. These results obtained in this study will be a useful tool for molecular analysis of AIC, and provide important information for clarification of apomixis reproductive mode.

English

-1 ), mannitol (0.0, 5 and10 g l -1 ) and sucrose (20 and 30 g l -1 ) on the synthesis of these pigments and glands on the produced leaves. Leaf discs of in vitro plantlets, were prepared and cultured on MS medium with 0.5 mg l -1 BAP to induce the shoot. All the cultures were incubated in the dark at 25 ± 2°C for 1 month. In all of the treatments, callus and shoot induction were observed. Percentage of calli and leaves containing red pigments, number of glands and percentage of leaves containing gland were noted as indicating the presence of hypericin and pseudohypericin pigments. Percentage of calli and leaves containing red pigments were significantly influenced by different concentrations of the hydrolyzed casein, mannitol and sucrose. The highest percentage of calli containing red pigments was observed in the culture medium which had 500 or 0.0 mg l -1 hydrolyzed casein and 20 g l -1 sucrose, without mannitol. Glands were observed on all the produced leaves. Number of glands and percentage of leaves containing gland were significantly influenced by the different concentrations of mannitol and sucrose and their interaction. The highest number of gland and percentage of leaves containing gland was achieved when explants were cultured in medium that included 30 g l -1 sucrose with 5 or 10 g l -1

Effects of drought stress on biochemical and physiological parameters in callus cultures of Carthamus tinctorius varieties

The aim of the work was to evaluate the callus induction response and in vitro drought tolerance of eight genotypes of safflower. The experiment was laid out as a completely randomized design in a factorial arrangement with three replications. To evaluate the drought tolerance of the genotypes, growing calli were exposed to drought stress after two subcultures by adding different concentrations of mannitol to the culture medium for one month. Under stress conditions, the genotypes were compared in terms of proline content, cell viability, relative growth rate, ion content (Na+ and K+), relative water content and index of tolerance. Drought affected all the measured biochemical and physiological factors and there were significant differences between the tested genotypes. The proline content increased in drought-stressed calli, and mannitol, as a stress agent, stimulated the synthesis of proline in all the genotypes, especially at the highest concentration (505 mM), whereas the ion contents, cell viability, RWC, RGR and index of tolerance exhibited a significant decrease. This suggested that these biochemical and physiological traits could be used to predict the drought tolerance of safflower genotypes. The results indicated that the cultivars Isfahan and LRV-51-51 were more drought-tolerant under in vitro conditions than the other genotypes.

IN VITRO APPROACHES FOR CONSERVATION OF DAHLIA (DAHLIA VARIABILIS L.)

Dahlia (Dahlia variabilis L.) is one of the popular bulbous flower crops in most gardens of the world. Dahlias are extensively used in exhibition, garden display and decoration. The available diversity with respect to floral characters is worth conserving. In situ field conservation is costly, labour intensive, prone to attack of pests and diseases and require more area. However, in vitro conservation technique offers the best alternative methods for germplasm conservation. An experiment was, therefore, conducted to standardize the growth and storability protocol for in vitro conservation of dahlia micro shoots using different concentrations of mannitol, alar (B-9) and maleic hydrazide. Micro shoots cultured on MS medium supplemented with maleic hydrazide at 40 mg/L recorded a significantly higher number of days (27.5) for bud sprouting, least shoot length (4.25 cm), maximum storage period (134.00 days) and good percent recovery (83.00%) followed by MS medium supplemented with alar (B-9) at 40 mg/L (higher number of days for bud sprouting (22.70), least shoot length (3.40 cm), maximum storage period (129.00 days) and good percent recovery (91.00%). Next best treatment was mannitol at 20 gm/L which registered significantly higher number of days (29.20) for bud sprouting, least shoot length (4.80 cm), maximum storage period (125.00 days) and good percent recovery (89.00%).

Modified buffer layers for polymer photovoltaic devices

The influence of anode buffer layers on the performance of polymer photovoltaic devices based on blends of poly(3-hexylthiophene) and [6,6]-phenyl-C-61-buytyric acid methyl ester has been investigated. The buffer layers consist of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT-PSS) doped with different concentrations of mannitol. Improved power conversion efficiency, up to 5.2%, has been observed by reducing the resistance of PEDOT:PSS after doping. One extrapolation method has been developed to exclude the resistance from the connection of the electrodes from the total device resistance. The results confirm that the device improvement is due to the reduction of series resistance of the PEDOT:PSS after the mannitol doping.

Transformation of tobacco with an Arabidopsis thaliana gene involved in trehalose biosynthesis increases tolerance to several abiotic stresses

Trehalose (a non-reducing disaccharide) plays an important role in abiotic stress protection. It has been shown that using trehalose synthesis genes of bacterial origin, drought and salt tolerance could be achieved in several plants. A cassette harboring the AtTPS1 gene under the control of the CaMV35S promoter and the Bialaphos resistance gene was inserted in the binary plasmid vector pGreen0229 and used for Agrobacterium-mediated transformation of tobacco (Nicotiana tabacum). T0 plants obtained were analyzed by PCR for the presence of AtTPS1 gene. Thirty lines were positive and seeds were germinated on media with 6 mg/l PPT to obtain T1 plants that were grown in the greenhouse to obtain T2 seeds that were germinated on selective media. Lines which seeds showed a 100 % survival rate were considered homozygous transgenic T1 lines. Three lines were selected and gene expression confirmed by northern and western blots. Transgenic seeds were germinated on media with different concentrations of mannitol (0, 0.25, 0.5 and 0.75 M) and sodium chloride (0, 0.07, 0.14, 0.2, 0.27 and 0.34 M) to score their tolerance to osmotic stress. Assays were conducted to test the tolerance of transgenic plants to drought (measurement of water percentage as a consequence of water withdrawal), desiccation (measurement of water loss as a consequence leaf detaching) and temperature stresses (germination at 15 ∘C and 35∘C). Transgenic tobacco plant lines registered higher germination rates under osmotic and temperature stress situations than did wild-type plants. Responses to drought and desiccation stresses were similar for all plant lines. It can hence be suggested that the heterologous expression of TPS1 gene from Arabidopsis can be used successfully to increase abiotic stress tolerance in model plants and probably in other crops.

Effect of Light Wavelength and Osmolality on the Swimming of Cercariae of Proterometra macrostoma (Digenea: Azygiidae)

The objectives of this study were to describe the effect of light wavelength and osmolality on the vertical swimming distance of the cercaria of Proterometra macrostoma. Significant differences were found in the average swimming distances and electrical burst activity in the tail of cercariae exposed to red vs. blue, green or white light, but no difference was observed when the last three colors were compared to one another with one exception. Cercarial swimming decreased slightly after 12 hr PE (post-exposure) in artificial pond water (15 mOsm) and artificial snail water (102 mOsm). By contrast, a significant reduction in swimming distance was observed in distilled water (0 mOsm) and artificial snail water with two different concentrations of mannitol (180 and 267 mOsm).

Factors affecting minimal growth conservation of potato microplants in vitro

Combined effects of sucrose, mannitol and photoperiod on microplant conservation were studied in four potato genotypes belonging to two different groups viz., Tuberosum and Andigena. Minimal growth medium was based on Murashige and Skoog (MS) supplemented with 6 different concentrations of sucrose (30, 40, 50, 60, 70 and 80 gl-1) with 4 different concentrations of mannitol (0, 20, 40 and 60 gl-1). The cultures were conserved under two photoperiod conditions i.e. continuous illumination and 16-h photoperiod at 6 ± 1 °C. There were significant interactions between photoperiod and sucrose, and between photoperiod and mannitol. Maximum microplant survival and desirable microplant growth were observed under 16-h photoperiod. Sucrose alone did not improve culture viability over 30 months of storage. Inclusion of mannitol in the conservation medium increased microplant survival. Sucrose x mannitol interaction showed that sucrose was effective in enhancing microplant survival in combination with 20 or 40 gl-1 mannitol, but not with 60 gl-1 mannitol. Combined effect of sucrose, mannitol and photoperiod showed that optimum microplant growth and maximum culture viability were obtained when the cultures were grown in MS medium containing 40 gl-1 sucrose and 20 gl-1 mannitol under 16-h photoperiod. Potato microplants can be conserved in this medium and cultural conditions up to 30 months without subculturing.

Do the lichens Xanthoparmelia conspersa (Ach.)Hale and Rhizocarpon Ram. em. Th. Fr. subgenus Rhizocarpon utilise exogenous carbohydrates for radial growth?

To field test the hypothesis that lichen thalli can use environmental sources of carbon, solutions of ribitol, arabitol and mannitol were added to intact thalli of Xanthoparmelia conspersa (Ach.)Hale and a yellow species of Rhizocarpon (Rhizocarpon Ram. em. Th. Fr. subgenus Rhizocarpon). In addition, ribitol and an arabitol/mannitol mixture were added to the marginal hypothalli of Rhizocarpon thalli after removal of the areolae. Carbohydrates were added at the beginning of 2- or 3-month growth periods for up to 15 months at concentrations approximately three times the levels estimated to be in the thalli. Addition of carbohydrates to intact thalli of both species had no effect on total radial growth but addition of mannitol significantly increased growth of X. conspersa thalli in the September/October growth period in one experiment. However, this effect was not repeated in a subsequent experiment in which different concentrations of mannitol were added to intact thalli. Addition of ribitol to hypothalli of Rhizocarpon enabled hypothalli to grow but at significantly lower levels than untreated intact thalli. Addition of an arabitol/mannitol mixture to hypothalli resulted in significantly increased hypothallus growth in the first few months of the experiment, growth then declining to levels below that of untreated thalli. The data suggest that, although hypothalli of Rhizocarpon may have the ability to utilise exogenous carbohydrates for growth, there was little evidence that intact thalli of either species utilise environmental sources of carbon in the field.

Volume control of erythrocytes during storage. The role of mannitol.

When red cells are stored as suspensions in artificial preservative solutions such as those consisting of saline, adenine, and glucose, increased hemolysis of the red cells occurs in vitro, a phenomenon that is readily prevented by the addition of mannitol. The mechanism by which mannitol prevents hemolysis is unknown. The authors have examined the possibility that mannitol prevents hemolysis by prevention of osmotic swelling of red cells that might otherwise increase their volume beyond their critical hemolytic volume. Storage in artificial media does, indeed, result in swelling of the red cells, which is prevented by mannitol and is increased by the addition of nystatin, an agent that greatly increases the sodium-potassium permeability of the cells. Swelling and hemolysis are correlated at different concentrations of mannitol, but the correlation breaks down when the case of nystatin-treated cells is considered; even with marked swelling, there is relatively little hemolysis. Moreover, increasing the volume of the stored red cells acutely by osmotic means results in relatively little additional hemolysis. These findings make it appear unlikely that simple osmotic lysis is the cause of hemolysis in stored cells. Some other stabilizing effect of mannitol that may or may not be related to its osmotic effect must play a role.

Effect of osmotic pressure on prolactin release in rainbow trout: In vitro studies

To investigate a possible effect of osmotic pressure on prolactin (PRL) release in rainbow trout, we developed a technique for in vitro perifusion of trout pituitaries. Changes in osmotic pressure similar to those observed in fish plasma during transfer experiments did not induce significant modifications of PRL release. In contrast, high-amplitude variation of osmotic pressure resulted in clear modifications of PRL secretion: hyperosmotic medium caused a reduction in PRL release, while infusion of hyposmotic medium induced a transitory increase in PRL release. By using different concentrations of mannitol, we found that the modifications of prolactin secretion could not be ascribed to alterations of the ionic composition of the medium but actually resulted from variations in the osmotic pressure of the incubation medium. In further experiments osmotic pressure was decreased from 300 to 220 mOsm/kg or from 400 to 300 mOsm/kg; a similar transitory increase in PRL release was observed. Measurement of gonadotropin (GtH) in the perifusion effluent medium showed that PRL and GtH secretion followed similar patterns. Thus, our results suggest a possible mechanical effect of wide changes in osmotic pressure on pituitary cell membranes. These data indicate that the rainbow trout differs notably from nonsalmonid teleost species thus far studied in the lack of sensitivity of its PRL cells to osmotic pressure.