Gum arabic glycoprotein is a twisted hairy rope : a new model based on o-galactosylhydroxyproline as the polysaccharide attachment site

Separation of the wound exudate from Acacia senegal (L.) Willd., “gum arabic,” on a preparative Superose-6 column gave two major fractions: a high molecular weight gum arabic glycoprotein (GAGP) containing about 90% carbohydrate and a lower molecular weight heterogenous gum arabic polysaccharide fraction. Hydrogen fluoride-deglycosylation of GAGP gave a large (~400 residue) hydroxyproline-rich polypeptide backbone (dGAGP). Alkaline hydrolysis of GAGP showed that most of the carbohydrate was attached to the polypeptide backbone as small (~30 residue) hydroxyproline (Hyp)-polysaccharide substituents. After partial acid hydrolysis of the Hyp-polysaccharide fraction we identified O-galactosylhydroxyproline as the glycopeptide linkage, identical with that of hydroxyproline-rich arabinogalactan-proteins (AGPs). However, unlike the acidic alanine-rich AGPs, GAGP is basic and notably deficient in alanine. Thus, while the GAGP polypeptide backbone more closely resembles that of the Hyp-rich cell wall protein extensin, the GAGP polysaccharide sidechains resemble AGPs. Possibly all three proteins comprise a phylogenetically related extensin superfamily of extended rod-like macromolecules. The “wattle-blossom” model for AGP and gum arabic predicts a few large polysaccharide substituents along the polypeptide backbone of a spheroidal macromolecule. On the contrary, our data imply a rodlike molecule with numerous small polysaccharide substituents (attached to 24% of the Hyp residues), regularly arranged along a highly periodic polypeptide backbone based, hypothetically, on a 10 to 12 residue repetitive peptide motif. Thus, a simple statistical model of the gum arabic glycoprotein predicts a repeating polysaccharide-peptide subunit of about 7 kilodaltons. The small polysaccharide substituents will maximize intramolecular hydrogen bonding if aligned along the long axis of the molecule, forming in effect a twisted hairy rope. Electron micrographs of rotary shadowed GAGP molecules support that prediction and may also explain how such apparently large molecules can exit the cell by endwise reptation through the small pores of the primary cell wall.     

Polypeptides of the Maize Amyloplast Stroma : Stromal Localization of Starch-Biosynthetic Enzymes and Identification of an 81-Kilodalton Amyloplast Stromal Heat-Shock Cognate

In the developing endosperm of monocotyledonous plants, starch granules are synthesized and deposited within the amyloplast. A soluble stromal fraction was isolated from amyloplasts of immature maize (Zea mays L.) endosperm and analyzed for enzyme activities and polypeptide content. Specific activities of starch synthase and starch-branching enzyme (SBE), but not the cytosolic marker alcohol dehydrogenase, were strongly enhanced in soluble amyloplast stromal fractions relative to soluble extracts obtained from homogenized kernels or endosperms. Immunoblot analysis demonstrated that starch synthase I, SBEIIb, and sugary1, the putative starch-debranching enzyme, were each highly enriched in the amyloplast stroma, providing direct evidence for the localization of starch-biosynthetic enzymes within this compartment. Analysis of maize mutants shows the deficiency of the 85-kD SBEIIb polypeptide in the stroma of amylose extender cultivars and that the dull mutant lacks a >220-kD stromal polypeptide. The stromal fraction is distinguished by differential enrichment of a characteristic group of previously undocumented polypeptides. N-terminal sequence analysis revealed that an abundant 81-kD stromal polypeptide is a member of the Hsp70 family of stress-related proteins. Moreover, the 81-kD stromal polypeptide is strongly recognized by antibodies specific for an Hsp70 of the chloroplast stroma. These findings are discussed in light of implications for the correct folding and assembly of soluble, partially soluble, and granule-bound starch-biosynthetic enzymes during import into the amyloplast.     

Studies on Special Proteins and Polypeptides of Sperm Cell-Rich Fraction in Orychophragmus violaceus

d sperm cell-rich) were isolated from disrupted pollen of Orychophragmus violaceus (L.) O.F. Schulz with 10 lan nylon filter and sucrose gradient centrifugation. Proteins were extracted using a phenol procedure and polypeptide patterns were analysed with two-dimensional polyacrylamide gel electrophoresis. The sperm cell-ri& fraction had 249 spots and the sample fraction contained 204 spots. The interleaf of sample and 30% sucrose fraction revealed 190 spots, the 30% sucrose fraction 244 spots and the interleaf of 30% and 40% sucrose fraction 167 spots. Compared the spots of the sperm cell-ri& fraction with those of the other four fractions, more than 18 spots were unique to the sperm cell-rich fraction and most of the unique spots were above 60 kD.     

Identification of Proteins Correlated with Increased Freezing Tolerance in Bromegrass (Bromus inermis Leyss. cv Manchar) Cell Cultures

Cellular and extracellular protein profiles from Bromus inermis Leyss. cv Manchar cell suspension cultures cold hardened by low temperature and abscisic acid (ABA) treatment were analyzed by one- and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. Cellular proteins (25, 165, 190, and 200 kilodaltons) increased by low temperature growth and cellular proteins (20, 25, 28, 30, 32, 37, 40, 45, 200 kilodaltons) increased by exogenous ABA treatment were identified. Low temperature treatment inhibited the synthesis of a 22 kilodalton protein and ABA treatment resulted in the synthesis of two extracellular proteins (17 and 21 kilodaltons). Low temperature and ABA-induced hardening conditions increased or induced a 25 and a 200 kilodalton protein. The 25 and a 30 kilodalton protein previously shown to be enriched by ABA-induced hardening conditions at both 3 and 23°C temperatures co-fractionated with the crude membrane fraction (30,000g sediment). The 200 kilodalton protein was detected in the 30,000g supernatant. Two-dimensional analysis of the crude membrane fraction resolved the 30 kilodalton protein band into a major polypeptide with an apparent isoelectric point of 6.85.     

Nitrate-induced changes in protein synthesis and translation of RNA in maize roots

Nitrate regulation of protein synthesis and RNA translation in maize (Zea mays L. var B73) roots was examined, using in vivo labeling with [³⁵S]methionine and in vitro translation. Nitrate enhanced the synthesis of a 31 kilodalton membrane polypeptide which was localized in a fraction enriched in tonoplast and/or endoplasmic reticulum membrane vesicles. The nitrate-enhanced synthesis was correlated with an acceleration of net nitrate uptake by seedlings during initial exposure to nitrate. Nitrate did not consistently enhance protein synthesis in other membrane fractions. Synthesis of up to four soluble polypeptides (21, 40, 90, and 168 kilodaltons) was also enhanced by nitrate. The most consistent enhancement was that of the 40 kilodalton polypeptide. No consistent nitrate-induced changes were noted in the organellar fraction (14,000g pellet of root homogenates). When roots were treated with nitrate, the amount of [³⁵S]methionine increased in six in vitro translation products (21, 24, 41, 56, 66, and 90 kilodaltons). Nitrate treatment did not enhance accumulation of label in translation products with a molecular weight of 31,000 (corresponding to the identified nitrate-inducible membrane polypeptide). Incubation of in vitro translation products with root membranes caused changes in the SDS-PAGE profiles in the vicinity of 31 kilodaltons. The results suggest that the nitrate-inducible, 31 kilodalton polypeptide from a fraction enriched in tonoplast and/or endoplasmic reticulum may be involved in regulating nitrate accumulation by maize roots.     

Invertases of Lilium Pollen : Characterization and Activity during In Vitro Germination

Two different forms of invertase are found in pollen of lily (Lilium auratum). One form is cytoplasmic (Invertase 1) and the other is bound to the pollen wall (Invertase 2). Invertase 1 has been partially purified and is a glycoprotein (apparent molecular weight, 450 kilodaltons) with a K_m of 0.65 millimolar for sucrose. The two invertases differ in pH optimum and thermal stability. Invertases of lily pollen are β-fructofuranosidases which can hydrolyze sucrose but not melizitose. The mature pollen grains have enzyme activity in both cytoplasmic and wall fractions, and no increase in the activity of either occurs during germination. The wall-bound enzyme could not be released by treatments with detergents or high salt concentrations.     

Characterization of Radish (Raphanus sativus) Storage Proteins

Radish (Raphanus sativus cv Rond rose à bout blanc Vilmorin) seeds, as other cruciferae oil seeds, contain two major types of storage protein aggregates which can be separated by gel filtration into 12 and 1.7 Svedberg fractions. These two fractions have been characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, amino acid composition, and two bidimensional gel electrophoresis systems. These results were compared with those obtained with rapeseed storage proteins. Radish 12 Svedberg particles are made of a series of nine major polypeptides ranging from 33 to 30 kilodaltons. These polypeptides present charge heterogeneity. The 12 Svedberg particle is made of six subunits 55 kilodaltons. Each subunit is a couple of two polypeptides linked by a disulfide bridge. The 1.7 Svedberg particle has a simpler composition. It is made of two polypeptides of 10 and 12 kilodaltons and smaller peptides of 7 kilodaltons. Twelve and 1.7 Svedberg particles also differ in their amino acid composition, the 1.7 Svedberg being particularly rich in glutamic acid and proline. Its components are basic. The organization of the rapeseed storage protein is similar but more complex.     

Identification of Low Molecular Mass GTP-Binding Proteins in Membranes of the Halotolerant Alga Dunaliella salina

A family of specific guanine nucleotide-binding proteins in Dunaliella salina was studied. Polypeptides of different subcellular fractions were separated by electrophoresis and transferred to nitrocellulose or Immobilon membranes. Incubation of the transfer blots with [³⁵S]GTPγS or [α-³²P]GTP showed no evidence for GTP-binding proteins in the chloroplast and cytosol fractions. However, two GTP-binding proteins with molecular masses of 28 and 30 kilodaltons were present in the plasma membrane and microsomal fractions. An additional 29 kilodalton GTP-binding protein was detected in the plasma membrane. The mitochondrial fraction contained significant amounts of only the 28 kilodalton GTP-binding protein. Binding of [³²P]GTP to the protein blots was completely prevented by 10 micromolar GTP or guanosine 5′-O-(2-thiodiphosphate) (added in 3 × 10⁴-fold excess), whereas ATP or CTP had no effect on the binding. The 28 kilodalton GTP-binding protein was recognized by polyclonal antibodies to the ras-related YPT1 protein of yeast but not by the anti-ras Y13-259 monoclonal antibody. GTP-binding proteins present in the microsomal fraction could not be solubilized by incubation of microsomes with 1 molar NaCl or 0.2 molar Na₂CO₃, but some GTP-binding activity was solubilized when microsomes were treated with 6 molar urea. These results indicate that D. salina GTP-binding proteins are tightly associated with the membranes. The covalent attachment of fatty acids to these proteins was also investigated. Electrophoresis followed by fluorography of delipidated microsomal proteins extracted from [³H]myristic acid-labeled cells showed an intense labeling of a 28 kilodalton protein. We conclude that D. salina contains proteins resembling the ras-related proteins found in animal cells and higher plants.     

Virus Attachment to Transparent Exopolymeric Particles along Trophic Gradients in the Southwestern Lagoon of New Caledonia

Viruses on organic aggregates such as transparent exopolymeric particles (TEP) are not well investigated. The number of TEP-attached viruses was assessed along trophic gradients in the southwestern lagoon of New Caledonia by determining the fraction of viruses removed after magnetic isolation of TEP. In order to isolate TEP magnetically, TEP were formed in the presence of magnetic beads from submicrometer precursors collected along the trophic gradients. The mixed aggregates of TEP-beads-viruses were removed from solution with a magnetic field. The percentage of viruses associated with newly formed TEP averaged 8% (range, 3 to 13%) for most of the stations but was higher (ca. 30%) in one bay characterized by the low renewal rate of its water mass. The number of viruses (N) attached to TEP varied as a function of TEP size (d [in micrometers]) according to the formulas N = 100d^1.60 and N = 230d^1.75, respectively, for TEP occurring in water masses with short (i.e., <40 days) and long (i.e., >40 days) residence times. These two relationships imply that viral abundance decreases with TEP size, and they indicate that water residence time influences viral density and virus-bacterium interactions within aggregates. Our data suggest that the fraction of viruses attached to TEP is highest in areas characterized by a low renewal rate of the water mass and can constitute at times a significant fraction of total virus abundance. Due to the small distance between viruses and hosts on TEP, these particles may be hot spots for viral infection.     

In vitro and in vivo phosphorylation of polypeptides in plasma membrane and tonoplast-enriched fractions from barley roots

Phosphorylation of polypeptides in membrane fractions from barley (Hordeum vulgare L. cv CM 72) roots was compared in in vitro and in vivo assays to assess the potential role of protein kinases in modification of membrane transport. Membrane fractions enriched in endoplasmic reticulum, tonoplast, and plasma membrane were isolated using sucrose gradients and the membrane polypeptides separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis. When the membrane fractions were incubated with γ-[³²P]ATP, phosphorylation occurred almost exclusively in the plasma membrane fraction. Phosphorylation of a band at 38 kilodaltons increased as the concentration of Mg²⁺ was decreased from millimolar to micromolar levels. Phosphorylation of bands at 125, 86, 58, 46, and 28 kilodaltons required millimolar Mg²⁺ concentrations and was greatly enhanced by Ca²⁺. When roots of intact plants were labeled with [³²P]orthophosphate, polypeptides at approximately 135, 116, 90, 46 to 53, 32, 28, and 19 kilodaltons were labeled in the plasma membrane fraction and polypeptides at approximately 73, 66, and 48 kilodaltons were labeled in the tonoplast fraction. Treatment of the roots of intact plants with 150 millimolar NaCl resulted in increased phosphorylation of some polypeptides while treatment with 100 mm NaCl had no effect.     

The Water Oxidation Complex of Chlamydomonas: Accumulation and Maturation of the Largest Subunit in Photosystem II Mutants

Photosystem II particles of Chlamydomonas reinhardtii contain three extrinsic polypeptides of 29, 20, and 16 kilodaltons, whose functions are incompletely defined. We prepared a monospecific polyclonal antibody against the 29 kilodalton protein and determined that it also specifically recognizes a protein of approximately 33 kilodaltons in thylakoid membrane fractions of several vascular plants, eukaryotic algae, and a cyanobacterium. The cross-reacting 33 kilodalton protein of pea was removed from inverted thylakoid vesicles by CaCl₂ washes demonstrating the structural relationship between the Chlamydomonas polypeptide and the largest subunit of the water oxidation complex of vascular plants. Functional identity of the Chlamydomonas polypeptide was confirmed by antibody inhibition of O₂ evolution in inverted pea vesicles. In contrast to wild-type cells, only low levels of the 29 kilodalton polypeptide are recovered with purified thylakoid membranes of the mutants examined. However, we show that the mature form of the 29 kilodalton polypeptide accumulates to wild-type levels in whole cell extracts of photosystem II deficient mutants and a water oxidation mutant of Chlamydomonas. Impaired membrane assembly has no effect on the maturation or stability of this component of the multi-subunit water oxidation complex.     

Development-Specific Differences in the Proteomics of Angiostrongylus cantonensis

Angiostrongyliasis is an emerging communicable disease. Several different hosts are required to complete the life cycle of Angiostrongylus cantonensis. However, we lack a complete understanding of variability of proteins across different developmental stages and their contribution to parasite survival and progression. In this study, we extracted soluble proteins from various stages of the A. cantonensis life cycle [female adults, male adults, the fifth-stage female larvae (FL5), the fifth-stage male larvae (ML5) and third-stage larvae (L3)], separated those proteins using two-dimensional difference gel electrophoresis (2D-DIGE) at pH 4–7, and analyzed the gel images using DeCyder 7.0 software. This proteomic analysis produced a total of 183 different dominant protein spots. Thirty-seven protein spots were found to have high confidence scores (>95%) by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Comparative proteomic analyses revealed that 29 spots represented cytoskeleton-associated proteins and functional proteins. Eight spots were unnamed proteins. Twelve protein spots that were matched to the EST of different-stage larvae of A. cantonensis were identified. Two genes and the internal control 18s were chosen for quantitative real-time PCR (qPCR) and the qPCR results were consistent with those of the DIGE studies. These findings will provide a new basis for understanding the characteristics of growth and development of A. cantonensis and the host–parasite relationship. They may also assist searches for candidate proteins suitable for use in diagnostic assays and as drug targets for the control of eosinophilic meningitis caused by A. cantonensis.     

Mate-Searching Behaviour of Common and Rare Wasps and the Implications for Pollen Movement of the Sexually Deceptive Orchids They Pollinate

Pollinator behaviour directly affects patterns of pollen movement and outcrossing rates in plants. In orchids pollinated by sexual deception of insects, patterns of pollen movement are primarily determined by the mate-searching behaviour of the deceived males. Here, using a capture-mark-recapture study (CMR) and dietary analysis, we compare mate-searching behaviour in relation to local abundance of two pollinator species and explore the implications for pollen movement in sexually deceptive Drakaea (Orchidaceae). Drakaea are pollinated solely by the sexual deception of male thynnine wasps. The rare Drakaea elastica and widespread D. livida occur sympatrically and are pollinated by the rare but locally common Zaspilothynnus gilesi, and the widespread and abundant Z. nigripes, respectively. Local abundance was significantly different with Z. nigripes twice as abundant as Z. gilesi. For the 653 marked wasps, there was no significant difference in median movement distance between Z. gilesi and Z. nigripes. However, the maximum movement distance was twice as high for Z. gilesi (556 m) compared with Z. nigripes (267 m). This is up to three times greater than previously reported for thynnines in CMR studies. Recapture rates were six times higher in Z. gilesi (57%) compared to Z. nigripes (9%). Pollen loads and wasp longevity were similar, suggesting that this difference in recapture rate arises due to differences in the number of males moving at a scale >500 m rather than through diet or mortality. Differences in the frequency of longer movements may arise due to variation in the spatial distribution of the wingless females. We predict that pollen movement will largely be restricted to within populations of Drakaea (<500 m), with few movements between populations (>500 m).     

Oligomerization of water soluble proteins of rabbit crystalline lens under the action of diamide

The study has examined the effects of the SH-oxidizing agent diamide (Diazane dicarboxylic acid bis-(N,N-dimethyl-amide)) on the water-soluble portion of proteins from rabbit lenses. The dialyzed protein extracts were incubated for 1-1.5 hrs with various concentrations of diamide. Treatments were monitored for alterations in sulphydryl contents, gel filtration and gel electrophoresis profiles of proteins. The response to 2 mM diamide treatment for 1 hr consists of rapid oxidation (up to 40%) of protein-bound sulphydryl groups accompanied by an appearance of polypeptides with apparent molecular weights. The protein with molecular weight of 29 kilodaltons was shown to be involved in cross-linking. The linkages in the dialyzed water-soluble lens polypeptide fraction induced by diamide may be reduced by GSH (10 mM) treatment of protein extract. The main target of oxidative insult induced by diamide in the water-soluble proteins of the lens is probably the superficially localized sulphydryl groups of crystallins. Our observations suggest that the described oxidative system of proteins may be a useful tool for cataract research.     

Investigation of the effect of nitrogen on severity of Fusarium Head Blight in barley

The effect of nitrogen on Fusarium Head Blight (FHB) in a susceptible barley cultivar was investigated using gel-based proteomics. Barley grown with either 15 or 100 kg ha^? 1 N fertilizer was inoculated with Fusarium graminearum (Fg). The storage protein fraction did not change significantly in response either to N level or Fg, whereas eighty protein spots in the water-soluble albumin fraction increased and 108 spots decreased more than two-fold in intensity in response to Fg. Spots with greater intensity in infected plants contained fungal proteins (9 spots) and proteolytic fragments of plant proteins (65 spots). Identified fungal proteins included two superoxide dismutases, l-xylulose reductase in two spots, peptidyl prolyl cis–trans isomerase and triosephosphate isomerase, and proteins of unknown function. Spots decreasing in intensity in response to Fg contained plant proteins possibly degraded by fungal proteases. Greater spot volume changes occurred in response to Fg in plants grown with low nitrogen, although proteomes of uninfected plants were similar for both treatments. Correlation of proteome changes with measurement of Fusarium-damaged kernels, fungal biomass and mycotoxin levels indicated that increased Fusarium infection occurred in barley with low N and suggests control of N fertilization as a possible way to minimise FHB in barley.     

From the Macro to the Micro: Gel Mapping to Differentiate between Sporozoites of Two Immunologically Distinct Strains of Eimeria maxima (Strains M6 and Guelph)

Two immunologically distinct strains of E. maxima were examined in this study: the M6 strain and the Guelph strain. The differential expression between the sporozoites of the two strains of E. maxima was determined by image analysis of 100 μg of protein from each strain separated by standard one- and conventional two-dimensional polyacrylamide gel electrophoresis. In addition to differences in both molecular weight and the electrophoretic mobility, differences in the intensity of polypeptide bands for example, GS 136.4 and M6 169 were explored. Pooled gels were prepared from each strain. A representative 2D-PAGE gel spanning a non-linear pH range of 3–10 of E. maxima strain M6 consisted of approximately 694 polypeptide spots with about 67 (9.6%) of the polypeptide spots being unique relative to the other strain. E. maxima strain GS had about 696 discernable polypeptide spots with 69 spots (9.9%) that differed from those of the M6 strain. In-depth characterization of the variable polypeptide spots; unique polypeptide spots (absence or presence) and shared polypeptide spots with modifications may lead to novel vaccine target in the form of multi-component, multi-stage, multi-immunovariant strains, multi-species subunit vaccine, and diagnostic probe for E. maxima.     

High temperature-induced thermotolerance in pollen tubes of tradescantia and heat-shock proteins

Growing pollen tubes of Tradescantia paludosa are protected from inhibition of growth at 41°C by a prior exposure to gradually increasing temperatures. Heat shock proteins (hsps) are not synthesized by pollen tubes as determined by labeling with [³⁵S]methionine and two-dimensional gel electrophoresis, during either a heat shock at 41°C or a gradual temperature increase to 41°C. A comparison after two-dimensional electrophoresis of silver-stained spots and radioactive spots after autoradiography of an extract of ungerminated pollen mixed with a trace amount of [³⁵S]methionine-labeled vegetative tissue heat shocked at 41°C to act as a hsps marker, indicates that the majority, if not all, of the major hsps are not present in the pollen grain at anthesis. The type of thermotolerance seen with pollen tubes can thus be achieved without the presence or the new synthesis of the hsps.     

Antioxidant,antibacterial, antifungal activities and gas chromatographic fingerprint of fractions from the root bark of Afzelia africana

Background: Afzelia africana is a tropical plant with numerous ethno-medicinal benefits. The plant has been used for the treatment of pain, hernia, fever, malaria, inflammation and microbial infections. Objectives: To perform bioassay-guided fractionation, antioxidant and antimicrobial activities of the bark of Afzelia africana. Methods: Column chromatography fractionation, antioxidant activity (% (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 1,1-diphenyl picrylhydrazyl (DPPH) scavenging activity))), antimicrobial activity (microbroth dilution: Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), MBC/MIC ratio), and synergistic activities (Checkerboard assay: Fraction Inhibitory Concentration Index (FICI)). Results: Bioassay-guided fractionation of A. africana produced four fractions that displayed promising free radical scavenging activities in the ABTS (54-93)% and the DPPH (35-76)% assays in the ranking order of F1(93-54)>F4(81-58)>F2(74-58)>F3(72-55) and F3(77-42)>F1(64-46)>F4(55-44)>F2(47-35) respectively at a concentration range of 1.0-0.01 mg/mL. The fraction F1 (MBC: 2.5-5.0 mg/mL) and F4 (MBC: 1.25-10.0 mg/mL) exhibited broad spectrum of superior bactericidal effects than F2 (MBC≥100.0 mg/mL) and F3 (MBC: 12.5-100.0 mg/mL) against Staphylococcus mutans, Staphylococcus aureus, Escherichia coli, fluconazole-resistant Candida albicans, methicillin-resistant S. aureus, Bacillus subtilis, Klebsiella pneumonia, Pseudomonas aeruginosa, Salmonella typhi, and Candida albicans (standard strain). The two most active fractions (F1 and F4) reported synergistic effects (FICI≤0.5) against S. typhi whilst the F4 reported additional synergism against E. coli, K. pneumonia, and S. typhi when combined with ciprofloxacin. Furthermore, the two fractions reported synergistic effects against Escherichia coli, Klebsiella pneumonia, Salmonella typhi, and Pseudomonas aeruginosa when combined with tetracycline whilst F1 reported antifungal synergism against fluconazole resistant Candida albicans when combined with fluconazole and ketoconazole. Conclusion: The study has confirmed the antioxidant, antimicrobial and synergistic uses of A. africana for the treatment of both infectious and non-infectious disease.     

Zinc and zinc binding substances in the tissues of common carp

Extraordinarily high concentrations of zinc (300–500 μg/(g fresh tissue)) are often found in the digestive tract tissue of common carp Cyprinus carpio, and high zinc concentrations (typically >100 μg/(g fresh tissue)) are also found in the kidney, gill, skeletal tissues, and spleen. In the present study, we found that only about 40% of the zinc in the digestive tract tissue of common carp could be extracted by water. However, 0.01 M citrate buffer, pH 6.2 could extract over 90% of the zinc. Subcellular zinc distribution in the tissues of common carp, grass carp Ctenopharyngodon idellus, silver carp Aristichthys nobilis, and tilapia Oreochromis aureus were compared. It was found that zinc concentrations in the cytosol, microsomal and mitochondrial fractions were approximately the same for all four species, being only about 16, 5, and 4 μg/(g fresh tissue), respectively. However, zinc concentrations in the nuclei/cell debris fraction of common carp tissue were much higher (46–370 μg/(g fresh tissue)) than the <14 μg/(g fresh tissue) found in the other three species. From this we conclude that neither water-soluble zinc proteins nor metallothionein could account for the high levels of zinc found in common carp tissues. A preliminary biochemical investigation suggests that the main zinc binding substance(s) in the nuclei/cell debris fraction of digestive tract tissue of common carp was probably a membrane protein(s).