Higher Amount Of Proline Research Articles

Studying the effect of two biological fertilizers on salt tolerance of tall fescue (Festuca arundinaceae schreb.)

Biological bacteria alleviate the adverse effects of osmotic stress under salinity conditions by different processes. In the present research, factorial test was performed based on complete randomized block design and the effect of two types of bacteria azotobacter and azospirillum and five salinity levels of 0, 4, 6, 8, 12 dS/m in nutrients, fresh and dry weights of the plants, amount of auxin, proline, tillering, and quality of tall fescue were studied. Results showed that the highest dry weight of shoots, dry, and fresh weights of the roots, tillering and nitrogen have been observed in 8 dS/m salinity + azotobacter treatment. The highest fresh weight of shoot was seen in 4 dS/m salinity treatment without bacteria. The highest quality of tall fescue was seen in 4 and 6 dS/m salinity treatments without bacteria, the highest amount of sodium was seen in 12 dS/m salinity + azospirillum treatment, and the highest amount of auxin contents of roots, stems and the highest amount of phosphorus were obtained in the control + azospirillum treatment. Also, the highest amount of potassium (K) and the lowest amount of nitrogen (N) and sodium (Na) were seen in the control treatment without bacteria. The lowest amount of potassium and the lowest fresh and dry weights of the roots were seen in 12 dS/m salinity + azotobacter treatment. The lowest fresh and dry weights of the shoots were seen in 4 dS/m salinity + azospirillum treatment and 6 dS/m salinity treatment without bacteria. The lowest amount of proline was obtained in control + azotobacter treatment. The lowest amount of phosphorus and stem’s auxin and also the highest amount of proline were obtained in 12 dS/m salinity treatment without bacteria. Generally, growth-inducing bacteria reduces the adverse effects of salinity stress and improves quality of tall fescue.

The effects of carbon dioxide concentrations on some morphological and physiological characteristics of ligustrum vulgare

Carbon dioxide is one of the most important necessary factors for plant growth. In order to study morphological and physiological response of ligustrum vulgare to Co2 enrichment, one-year-old seedlings of this species exposed to different carbon dioxide concentrations for two months. Treatments included 450 (control), 750, and 1100 ppm Co2. The experiment was based on a completely randomized design with three replications. Then some morphological and physiological characteristics were measured. Results showed Co2 concentrations of 750 and 1100 ppm increased all morphological traits (except collar diameter and root dry weight) and physiological characteristics such as proline, chlorophyll a and nitrogen. The highest amounts of proline, chlorophyll a and nitrogen were observed at concentration of 750 ppm. The amount of increase in proline was about 4-fold compared to the control. The study concludes that the increased carbon dioxide concentration in the future maybe improve the growth of this plant.

Enhanced oxidative stress in the jasmonic acid-deficient tomato mutant def-1 exposed to NaCl stress

Jasmonic acid (JA) has been mostly studied in responses to biotic stresses, such as herbivore attack and pathogenic infection. More recently, the involvement of JA in abiotic stresses including salinity was highlighted; yet, its role in salt stress remained unclear. In the current study, we compared the physiological and biochemical responses of wild-type (WT) tomato (Solanum lycopersicum) cv Castlemart and its JA-deficient mutant defenseless-1 (def-1) under salt stress to investigate the role of JA. Plant growth, photosynthetic pigment content, ion accumulation, oxidative stress-related parameters, proline accumulation and total phenolic compounds, in addition to both enzymatic and non-enzymatic antioxidant activities, were measured in both genotypes after 14 days of 100 mM NaCl treatment. Although we observed in both genotypes similar growth pattern and sodium, calcium and potassium levels in leaves under salt stress, def-1 plants exhibited a more pronounced decrease of nitrogen content in both leaves and roots and a slightly higher level of sodium in roots compared to WT plants. In addition, def-1 plants exposed to salt stress showed reactive oxygen species (ROS)-associated injury phenotypes. These oxidative stress symptoms in def-1 were associated with lower activity of both enzymatic antioxidants and non-enzymatic antioxidants. Furthermore, the levels of the non-enzymatic ROS scavengers proline and total phenolic compounds increased in both genotypes exposed to salt stress, with a higher amount of proline in the WT plants. Overall the results of this study suggest that endogenous JA mainly enhanced tomato salt tolerance by maintaining ROS homeostasis.

Physiological and molecular studies on the effect of gamma radiation in fenugreek (Trigonella foenum-graecum L.) plants.

This experiment assessed the biochemical changes in fenugreek plants exposed to gamma radiation. Two pot experiments were carried out during two growing seasons of 2015 and 2016. Seeds were subjected to five doses of gamma irradiation (25, 50, 100, 200 and 400 Gy) and were immediately planted into soil pots in a greenhouse. The experimental analysis was performed in M1 and M2 generations. Significant differences between irradiated and control plants were detected for most studied characters in M1 and M2 generations. It was demonstrated that low doses of gamma irradiation led to gradually increases in growth, yield characters, leaf soluble protein concomitantly with increases in the contents of phenolic and flavonoids compounds particularly at 100 Gy. These changes were accompanied by a substantial increase in ascorbic acid, α-tocopherol and retinol contents. Proline content was increased under all doses of gamma rays in M1 generation and the highest amount of proline was obtained at 200 Gy with visible decrease in M2 generation under the same dose. Meanwhile, the highest dose of gamma radiation (400 Gy) decreased all the studied parameters in both mutagenic generations as compared with control plants. In addition, gamma irradiation doses induced changes in DNA profile on using five primers and caused the appearance and disappearance of DNA polymorphic bands with variation in their intensity. These findings confirm the effectiveness of relatively low doses of gamma rays on improving the physiological and biochemical criteria of fenugreek plants.

Evaluation of bermuda and paspalum grass types for urban landscapes under saline water irrigation

ABSTRACTIn the arid regions, turfgrass cover is an integral part of landscape to protect the soil from erosion, enhance the aesthetic value, and improve the microclimate. The salinity and the scarcity of fresh water of the arid region are the major challenging factors in turfgrass production. Therefore, the need for salt tolerant turfgrass with functional quality is necessary to improve the turf performance. The detrimental effects of salinity include growth suppression, and lowered osmotic potential ultimately leading to firing of the leaf blades. In this context, the study was undertaken to determine the relative salt tolerance and growth response of turfgrass genotypes in order to recommend turfgrass cultivars that can tolerate high salinity irrigation and maintain excellent visual and functional qualities under United Arab Emirates (UAE) condition. The paspalum cultivars maintained the highest succulence percentage compared to the bermudagrass cultivars under enhanced salinity levels. The shoots count, fresh weight (FW), and dry weight (DW) were found highest in paspalum types. The chlorophyll a, chlorophyll b and the total chlorophyll content was found higher in bermuda grass types under high salinity levels. The bermudagrass cultivars showed significantly higher carotenoids, anthocyanins and proline compared to the paspalum types under salt stress condition. In the case of princess 77 and Yukon, an inherently high amount of proline was recorded which confirmed an increase up to 10,000 ppm and drastically declined beyond this concentration. Sea Dwarf paspalum and Sea Isle 2000 maintained uniformity in the proline level at all levels of salinity without significant variation. These findings point to the fact that both paspalum and bermuda types exhibited varied responses to different physiological and biochemical parameters under the saline conditions. Paspalum types have an edge over the bermudagrass in terms of shoot density, which is a potential factor in determining the high-quality turfs. Bermudagrass types can be applied in lower salinity conditions based on the responses as evidenced from the present results.

Bioactive properties: enhancement of hepatoprotective, antioxidant and DNA damage protective effects of golden grey mullet protein hydrolysates against paracetamol toxicity.

This study was undertaken to examine the hepatoprotective, antioxidant, and DNA damage protective effects of protein hydrolysates from Liza aurata, against paracetamol overdose induced liver injury in Wistar rats. L. aurata protein hydrolysates (LAPHs) were mainly constituted by glutamic acid (Glu) and glutamine (Gln) and lysine (Lys). In addition, they contained high amounts of proline (Pro), leucine (Leu) and glycine (Gly). The molecular weight distribution of the hydrolysates was determined by size exclusion chromatography, which analyzed a representative hydrolysate type with a weight range of 3–20 kDa. The hepatoprotective effect of LAPHs against paracetamol liver toxicity was investigated by in vivo assay. Rats received LAPHs daily by gavage, for 45 days. Paracetamol was administrated to rats during the last five days of treatment by intraperitoneal injection. Paracetamol overdose induced marked liver damage in rats was noted by a significant increase in the activities of serum aspartate amino transferase (AST) and alanine amino transferase (ALT), and oxidative stress which was evident from decreased activity of the enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)), and level of glutathione (GSH), and increased concentration of lipid peroxidation products (MDA). Furthermore, paracetamol increased the DNA damage with liver histopathological changes. LAPH pretreatment significantly attenuated paracetamol-induced hepatotoxic effects, including oxidative damage, histopathological lesions, and apoptotic changes in the liver tissue. Interestingly, LAPHs restored the activities of antioxidant enzymes and the level of GSH, ameliorated histological and molecular aspects of liver cells. The present data suggest that paracetamol high-dose plays a crucial role in the oxidative damage and genotoxicity of the liver and therefore, some antioxidants such us LAPHs might be safe as hepatoprotectors. Altogether, our studies provide consistent evidence of the beneficial effect of LAPHs on animals treated with a toxic dose of paracetamol and might encourage clinical trials.

Water Deficit Affects Primary Metabolism Differently in Two Lolium multiflorum/Festuca arundinacea Introgression Forms with a Distinct Capacity for Photosynthesis and Membrane Regeneration.

Understanding how plants respond to drought at different levels of cell metabolism is an important aspect of research on the mechanisms involved in stress tolerance. Furthermore, a dissection of drought tolerance into its crucial components by the use of plant introgression forms facilitates to analyze this trait more deeply. The important components of plant drought tolerance are the capacity for photosynthesis under drought conditions, and the ability of cellular membrane regeneration after stress cessation. Two closely related introgression forms of Lolium multiflorum/Festuca arundinacea, differing in the level of photosynthetic capacity during stress, and in the ability to regenerate their cellular membranes after stress cessation, were used as forage grass models in a primary metabolome profiling and in an evaluation of chloroplast 1,6-bisphosphate aldolase accumulation level and activity, during 11 days of water deficit, followed by 10 days of rehydration. It was revealed here that the introgression form, characterized by the ability to regenerate membranes after rehydration, contained higher amounts of proline, melibiose, galactaric acid, myo-inositol and myo-inositol-1-phosphate involved in osmoprotection and stress signaling under drought. Moreover, during the rehydration period, this form also maintained elevated accumulation levels of most the primary metabolites, analyzed here. The other introgression form, characterized by the higher capacity for photosynthesis, revealed a higher accumulation level and activity of chloroplast aldolase under drought conditions, and higher accumulation levels of most photosynthetic products during control and drought periods. The potential impact of the observed metabolic alterations on cellular membrane recovery after stress cessation, and on a photosynthetic capacity under drought conditions in grasses, are discussed.

Fatty acid, amino acid and mineral composition of rainbow trout (Oncorhynchus mykiss) of Indian Himalaya

The present study was conducted to determine fatty acid profile, amino acid and mineral content of rainbow trout from Indian Himalayan region. The crude protein, crude fat and ash content were 19.44, 5.18 and 1.37% respectively. Protein had a well-balanced amino acid composition, with higher amounts of proline. The highest amino acid score was observed for tryptophan followed by isoleucine. Total monounsaturated fatty acids were high followed by saturated fatty acids and polyunsaturated fatty acids. Oleic acid was dominant, followed by palmitic acid and linoleic acid. Among the n-3 PUFAs, DHA was the most dominant followed by linolenic acid. The ratio of n-3/n-6 PUFA was 0.77. Among the minerals, K was high followed by Ca, Na, Fe, Zn, Se and Mn. From the present study, it can be concluded that rainbow trout has a rich amount of quality protein with well-balanced essential amino acids, PUFAs and minerals.

Assessment of gelatin–chitosan interactions in films by a chemometrics approach

Information looking at the interaction mechanism of chitosan–gelatin is scarce. The objective of this work was to analyze the interactions between chitosan and bovine (BG) and salmon gelatins using a chemometrics approach based on the multivariate statistical analysis, partial least square regression (PLSR), with data collected from amino acid profiling and differential scanning calorimetry.Gelatins showed differences in imino acid profile (higher amount of proline and hydroxyproline in BG). Chitosan modified the microstructure of films as indicated by variations in glass transition temperature (Tg), heat capacity (∆Cp), melting temperature (Tm), and enthalpy (∆H), in partially crystalline and amorphous films due to the effect of chitosan on gelatin chain renaturation and moisture content. PLSR showed that thermal properties of gelatin–chitosan films were affected by presence of amino acids Cysteine, Tyrosine, Valine, Arginine, Hydroxyproline, and Glycine, which would modify the orientation of side chains of polymer, while charged amino acids would encourage gelatin renaturation rather than gelatin–chitosan interaction.

Stress-induced Δ1-pyrroline-5-carboxylate synthetase (P5CS) gene confers tolerance to salt stress in transgenic sugarcane

High salinity interferes in sugarcane growth and development, affecting not only crop yield but also reducing sucrose concentration in culms. Sugarcane plants submitted to salt stress can accumulate compatible solutes, such as proline, which may counteract the effects of salt accumulation in the vacuole and scavenge reactive oxygen species. The objective of this study was to evaluate the response to salt stress of sugarcane plants transformed with the Vigna aconitifolia P5CS gene, which encodes ∆1-pyrroline-5-carboxylate synthetase, under the control of a stress-induced promoter AIPC (ABA-inducible promoter complex). For this, 4-month-old clonally multiplied sugarcane plants from two transformation events were irrigated every 2 days with 1/10 Hoagland’s solution supplemented with 100, 150 and 200 NaCl, progressively, during 28 days. Transgenic lines showed increased transgene expression in 3.75-fold when compared with the control plants after 9 days of irrigation with saline water, which can explain the higher proline concentration found in these plants. At the end of the experiment (day 28), the transgenic lines accumulated up to 25 % higher amounts of proline when compared with non-transformed control plants. Stress response in transgenic plants was also accompanied by a reduction of malondialdehyde (MDA) derived from cellular lipid peroxidation in leaves, lower Na+ accumulation in leaves and maintenance of photochemical efficiency of PSII. Thus, proline contributed to the protection of the photosynthetic apparatus and the prevention of oxidative damage in transgenic sugarcane under salt stress.

Tolerance of Miscanthus × giganteus to salinity depends on initial weight of rhizomes as well as high accumulation of potassium and proline in leaves

Miscanthus×giganteus, a species useful for sustainable agriculture, can be cultivated on soils with lower bonitation and also with higher salinity. The study aimed to estimate NaCl concentrations which limit growth of Miscanthus×giganteus plants and to determine physiological parameters best reflecting the response of Miscanthus to salt stress. The experiment was conducted on plants grown at 0–200mM of NaCl. All analyses were done after 12 weeks of salt treatment. In rhizomes and leaves, fresh (FW) and dry weight (DW), relative water content (RWC), electrolyte leakage (EL), and ion content were determined; in leaves only, chlorophyll fluorescence, net photosynthesis rate (PN), transpiration (E), stomatal conductance (gs) and proline content. Shoots developed at all NaCl concentrations, but at 200mM many rhizomes produced none; thus analyses on leaves were done only on plants grown at 0–150mM of NaCl. Salinity decreased FW and DW of roots and shoots significantly, and retarded increases in rhizome weight. In leaves, salinity of 100 and 150mM NaCl did not damage membrane structures, while in rhizomes only 200mM increased EL considerably. Most parameters of chlorophyll fluorescence and gas exchange declined under salinity. High amounts of proline, K and Na were accumulated in leaves at 100 and 150mM NaCl. RWC remained unchanged in roots and leaves and decreased in rhizomes under rising salinity. The initial FW of the rhizomes studied correlated with the salt tolerance of Miscanthus plants. Changes in chlorophyll fluorescence, PN, FW and DW of roots and leaves as well as potassium and proline concentrations in leaves are the most reliable indicators of the response of Miscanthus to salinity. A high accumulation of K+ and proline in leaves reduces the sodium effect and determines the tolerance of Miscanthus to salinity.

Evaluation of Antioxidant Status of Two Limoniastrum Species Growing Wild in Tunisian Salty Lands.

We aim to highlight the differential antioxidant status of Limoniastrum guyonianum and Limoniastrum monopetalum in relation to their respective chemical and location characteristics. Metabolite analysis revealed similar contents in phenolic, flavonoïds, sugars and chlorophyll in the two species’ leaves. Higher amounts of proline (Pro), carotenoïds (Carot), sodium (Na) and potassium (K) were measured in L. monopetalum leaves relative to L. guyonianum ones. While the two Limoniastrum species have similar free radical DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity, L. guyonianum showed more than two-fold higher ferrous ions chelating activity relative to L. monopetalum. However, highest reducing power activity was observed in L. monopetalum. Thiobarbituric acid-reactive substances (TBARS) determination indicated that L. monopetalum behave better lipid membrane integrity relative to L. guyonianum. These findings suggested that the lesser stressful state of L. monopetalum was related to higher metabolites accumulation and reducing capacity compared to L. guyonianum.

Nutritional study of new variety of groundnut(Arachis hypogaea L.) JL-24 seeds

Proximate composition, anti-nutritional and nutritional value of seeds of new variety of groundnut (Arachis hypogaea L) JL-24 was determined. The result showed that the groundnut seed contain moisture (5.529%), crude fibre (1.149%), lipid (46.224%), crude protein (25.20%), carbohydrate (21.26%), ash (2.577%), calcium (0.087%), phosphorus (0.29%) and energy (601.856%). The total fatty acid composition was 10.44 and 33.51% for saturated and unsaturated fatty acid, respectively. The protein solubility at different pH ranging from 0.5 to 13.5, the maximum seeds proteins were extracted at pH 12. The serine has not been reported in the seed protein and the seed was found to contain highest amount of proline (6.412%). The anti-nutritional analysis shows that cyanide content 4.818 HCN/100g, tannin 0.412 g/100g, oxalate 0.180 g/100g and haemagglutinin activity for goat blood group is 1:8 and no haemagglutinin activity for chicken and human blood group, and no trypsin inhibition was found. The nutritive values were determined in terms of feed utilization 6.552%, nitrogen utilization 0.2957%, protein efficiency ratio (PER) (+) 1.368% and feed efficiency ratio (FPR) (+) 0.345%. The knowledge of this study could be utilized for various food preparation and selection for breeding purpose. Key word: Arachis hypogaea JL-24, chemical composition, nutritional and anti-nutritional composition.

The relationship between citrulline accumulation and salt tolerance during the vegetative growth of melon (Cucumis melo L.)

Citrulline has been recently shown to behave as a novel compatible solute in the <i>Citrullus lanatus</i> (<i>Cucurbitaceae</i>) growing under desert conditions. In the present study we have investigated some aspects of the relationship which might occur in leaves of melon seedlings, also known to produce citrulline, between the capacity to accumulate this ureido amino acid and salt tolerance. With this end in view, salt-induced changes at the citrulline level have been compared in two melon genotypes exhibiting contrasted abilities to withstand the damaging effects of high salinity. Progressive salinization of the growing solution occurred at 23 days after sowing. The final 250 mmol/l external NaCl concentration was reached within 5 days and further maintained for 16 days. In response to this treatment, it was found that the citrulline amount increased in fully expanded leaves of both genotypes according to different kinetics. The salt tolerant genotype Midyat was induced to accumulate citrulline 4 days before the salt sensitive Yuva and as a consequence the final amount of this amino acid was twice higher in the former than in the latter. Compared with citrulline, the free proline level was found to be relatively low and the changes induced in response to the salt treatment exhibited different trends according to the genotypes under study. Thus at the end of the treatment mature leaves of the salt sensitive Yuva contained higher amount of proline than those of Midyat. The changes in the calculated molar ratio between citrulline and free proline suggested that salt tolerance might be associated with high values for this ratio and vice et versa for sensitivity. The interest of citrulline as a biochemical marker for salt tolerance of melon genotypes is discussed.

Specific effect of high-pressure treatment of milk on cheese proteolysis

The extent of primary and secondary proteolysis of cheeses made from raw (RA), pasteurized (PA, 72 degrees C, 15 s) or pressure-treated (PR, 500 MPa, 15 min, 20 degrees C) goats' milk was assessed. Modifications in cheese-making technology were introduced to obtain cheeses with the same moisture content, and thus studied per se the effect of milk treatment on cheese proteolysis. The PR milk cheese samples were differentiated from RA and PA milk cheeses by their elevated beta-lg content, and by the faster degradation of alphas1-, alphas2- and beta-CN throughout ripening. Non-significant differences were found in either pH 4.6 soluble-nitrogen or trichloracetic acid soluble-nitrogen contents of cheeses. However, the pasteurization of milk decreased the free amino acid production in cheese. The RA milk cheeses had the highest amount of proline and the lowest concentrations of serine, tyrosine, arginine and alpha-aminobutyric acid, whereas PR milk cheese showed higher levels of arginine.

Seasonal changes in the levels of compatible osmolytes in three halophytic species of inland saline vegetation in Hungary

Seasonal changes in the leaf concentration of compatible osmolytes were investigated in three halophytic species (Lepidium crassifolium, Camphorosma annua and Limonium gmelini subsp. hungaricum) native to a salty-sodic grassland. The investigated species were shown to accumulate both carbohydrate- and amino acid-derived osmolytes. The leaf tissues of C. annua (Chenopodiaceae) preferentially stored glycine betaine and pinitol, while in L. gmelini (Plumbaginaceae) beta-alanine betaine, choline-O-sulphate, and pinitol were accumulated. In the leaves of L. crassifolium (Brassicaceae) a very high amount of proline, associated with a high level of soluble carbohydrates was found. Not only the biochemical nature of the osmolyte, but also the seasonal pattern of osmolyte accumulation showed significant species-specific fluctuations. In addition, the cellular levels of the observed osmolytes changed with the growth period and according to the environmental parameters. The highest concentrations of osmolytes were found in March, when low temperatures, hypoxic conditions and high salt concentrations were the main constraints to plant growth. The high structural diversity of osmolytes combined with their multifunctionality and the seasonal flexibility of the metabolism in plants facing multiple stresses is discussed.

Synaptopodin: an actin-associated protein in telencephalic dendrites and renal podocytes.

Synaptopodin is an actin-associated protein of differentiated podocytes that also occurs as part of the actin cytoskeleton of postsynaptic densities (PSD) and associated dendritic spines in a subpopulation of exclusively telencephalic synapses. Amino acid sequences determined in purified rat kidney and forebrain synaptopodin and derived from human and mouse brain cDNA clones show no significant homology to any known protein. In particular, synaptopodin does not contain functional domains found in receptor-clustering PSD proteins. The open reading frame of synaptopodin encodes a polypeptide with a calculated Mr of 73.7 kD (human)/74.0 kD (mouse) and an isoelectric point of 9.38 (human)/9. 27 (mouse). Synaptopodin contains a high amount of proline ( approximately 20%) equally distributed along the protein, thus virtually excluding the formation of any globular domain. Sequence comparison between human and mouse synaptopodin revealed 84% identity at the protein level. In both brain and kidney, in vivo and in vitro, synaptopodin gene expression is differentiation dependent. During postnatal maturation of rat brain, synaptopodin is first detected by Western blot analysis at day 15 and reaches maximum expression in the adult animal. The exclusive synaptopodin synthesis in the telencephalon has been confirmed by in situ hybridization, where synaptopodin mRNA is only found in perikarya of the olfactory bulb, cerebral cortex, striatum, and hippocampus, i.e., the expression is restricted to areas of high synaptic plasticity. From these results and experiments with cultured cells we conclude that synaptopodin represents a novel kind of proline-rich, actin-associated protein that may play a role in modulating actin-based shape and motility of dendritic spines and podocyte foot processes.

The glycine betaine inhibitory effect on the osmoinduced proline response of rape leaf discs

Rape leaf discs submitted in vitro to osmotic upshocks accumulated very high amounts of proline. PEG 6000 and sucrosewere found to be strong inducers of the proline response while mannitol and NaCl were low inducers. Whatever the osmoticum, proline accumulation was significantly lowered when the stress media were added with glycine betaine at concentrations ranging from 5 to 50 mM. The antagonistic effect of glycine betaine was investigated in response to different concentrations as well as in terms of timing of its supply before the onset of the treatment or during the time course of the osmoinduced proline response. When supplied with the osmoticum during the whole treament, the deduced apparent I 50's for glycine betaine ranged from 15–25 mM for mannitol, sucrose and NaCl to 250 mM for PEG 6000. The observed effect relied on glycine betaine uptake and accumulation via a possible osmotie effect because its endogenous level was close to that of proline accumulated in discs incubated in stress media devoid of glycine betaine. The efficacy of glycine betaine in reversing the effect of osmotic shock on the proline response has been confirmed in leaf discs loaded with glycine betaine prior to their incubation under wilting conditions. Possible targets for the glycine betaine effect were then investigated. It appears that Δ 1-pyrroline 5-carboxylate reductase activity and the capacity of leaf discs to mobilize proline after releasing of stress conditions are not modulated by glycine betaine. It is suggested that glycine betaine might exert some effect at the membrane level since it was found that triethylammonium chloride mimicked the GB inhibitory role on the osmoinduced proline response.

Factors Contributing to Urea Formation in Commercially Fermented Wines

Juices and corresponding wines from 22 different wineries were obtained and analyzed. The results of over 400 data pairs showed that yeast strain and α-amino nitrogen content of the juices were the major controlling factors for urea accumulation. Prise de Mousse yeast from two sources was superior to all other yeast strains surveyed for minimizing urea formation, as they showed excellent independence from α-amino nitrogen concentration in white wines. Other yeast strains showed an α-amino nitrogen concentration dependence for the formation of urea. Red wines, especially those cultivars with high amounts of proline, were generally uniformly low in urea formation regardless of yeast strain. Urea concentration in the unheated wines correlated with ethyl carbamate in the heated wines.

Amino Acids in Pollens and Nectars of Citrus Cultivars and in Stored Pollen and Honey from Honeybee Colonies in Citrus Groves

SummaryTotal amino acids and crude protein levels were analysed in pollens from flowers of nine citrus cultivare, and in stored pollen from three honeybee colonies in citrus groves. Free amino acids were determined in the nectars from six cultivars and in three citrus honeys. Although the protein levels of pollens from different cultivars ranged from 6middot;2% to 20·7%, the percentage of individual amino acids was relatively constant. Aspartic acid and glutamic acid were the predominant amino acids in the pollen from flowers. Stored pollen contained 17·1 % to 22·6% protein, and higher amounts of proline than flower pollen.Nectars contained 7·5 to 79·1 mg/100 g of amino acids. Wide variation was observed both in the numbers and in the levels of amino acids in the nectars. In nectars in which they were found, proline and serine were the predominant amino acids. In contrast, the kinds and amounts of amino acids were fairly constant in the honey samples, proline being the major one. Unlike most plants, Citru...