Cellular Internalization Mechanism and Intracellular Trafficking of Filamentous M13 Phages Displaying a Cell-Penetrating Transbody and TAT Peptide

Cellular internalization of bacteriophage by surface-displayed cell penetrating peptides has been reported, though the underlying mechanism remains elusive. Here we describe in detail the internalization mechanism and intracellular trafficking and stability of filamentous M13 phages, the cellular entry of which is mediated by surface-displayed cell-penetrating light chain variable domain 3D8 VL transbody (3D8 VL-M13) or TAT peptide (TAT-M13). Recombinant 3D8 VL-M13 and TAT-M13 phages were efficiently internalized into living mammalian cells via physiologically relevant, energy-dependent endocytosis and were recovered from the cells in their infective form with the yield of 3D8 VL-M13 being higher (0.005∼0.01%) than that of TAT-M13 (0.001∼0.005%). Biochemical and genetic studies revealed that 3D8 VL-M13 was internalized principally by caveolae-mediated endocytosis via interaction with heparan sulfate proteoglycans as cell surface receptors, whereas TAT-M13 was internalized by clathrin- and caveolae-mediated endocytosis utilizing chondroitin sulfate proteoglycans as cell surface receptors, suggesting that phage internalization occurs by physiological endocytotic mechanism through specific cell surface receptors rather than non-specific transcytotic pathways. Internalized 3D8 VL-M13 phages routed to the cytosol and remained stable for more than 18 h without further trafficking to other subcellular compartments, whereas TAT-M13 phages routed to several subcellular compartments before being degraded in lysosomes even after 2 h of internalization. Our results suggest that the internalizing mechanism and intracellular trafficking of filamentous M13 bacteriophages largely follow the attributes of the displayed cell-penetrating moiety. Efficient internalization and cytosolic localization of 3D8 VL transbody-displayed phages will provide a useful tool for intracellular delivery of polar macromolecules such as proteins, peptides, and siRNAs.     

Incorporation and replication of 8-oxo-deoxyguanosine by the human mitochondrial DNA polymerase

To assess the role of oxidative stress on the replication of mitochondrial DNA, we examined the kinetics of incorporation of 8-oxo-7,8-dihydroguanosine (8-oxodG) triphosphate catalyzed by the human mitochondrial DNA polymerase. Using transient state kinetic methods, we quantified the kinetics of incorporation, excision, and extension beyond a base pair containing 8-oxodG. The 8-oxodGTP was incorporated opposite dC in the template with a specificity constant of 0.005 microM(-1) s(-1), a value approximately 10,000-fold lower than that for dGTP. Once incorporated, 96% of the time 8-oxodGMP was extended by continued polymerization rather than being excised by the proofreading exonuclease. The specificity constant for incorporation of 8-oxodGTP opposite a template dA was 0.2 microM(-1) s(-1), a value 13-fold higher than incorporation opposite a template dC. The 8-oxodG:dA mispair was extended rather than excised at least 70% of the time. Examination of the kinetics of polymerization with 8-oxodG in the template strand also revealed relatively low fidelity in that dCTP would be incorporated only 90% of the time. In nearly 10% of events, dATP would be incorporated, and once incorporated dA (opposite 8-oxodG) was extended rather than excised. The greatest fidelity was against a dTTP:8-oxodG mismatch affording a discrimination value of only 1800. These data reveal that 8-oxodGTP is a potent mutagen. Once it is incorporated into DNA, 8-oxodGMP codes for error prone DNA synthesis. These reactions are likely to play important roles in oxidative stress in mitochondria related to aging and as compounded by nucleoside analogs used to treat human immunodeficiency virus infections.     

Characterization of the cytoplasmic fibrils of Treponema refringens (Nichols).

The cytoplasmic fibrils of Treponema refringens were studied in situ by electron microscopy of thin sectioned and negatively stained cells. From 5 to 21 parallel fibrils ran through the cell in a band adjacent to the inner side of the cytoplasmic membrane, on the inner sides of the curves of the spirochete. The nuclear areas of cells were adjacent to the fibrils. Cross sections of fibrils isolated from cells which had been lysed were polygonal and not uniformly electron dense. Polyacrylamide gel electrophoresis of partially purified fibril preparations indicated their main component to be a protein with a molecular weight of 97,000. Fibrils were solubilized by 1% trypsin, 1% pronase, 6 M urea, 1 N HCl, 0.005 N NaOH or 1.3% sodium dodecyl sulfate. By electron microscopy of negatively stained isolated fibrils, each fibril was found to be a complex arrangement of strands rather than a single tubule.     

Comparison of Methods for Isolation of Mycobacteria from Water

Twelve methods for the isolation of mycobacteria were compared by applying them in parallel to 26 samples of surface water and 109 samples of treated water. Each method was defined by a particular combination of decontamination method, growth medium, and incubation temperature. For the decontamination of surface water, we used cetylpyridinium chloride (CPC) (30 min, 0.05%), as well as sample preincubation in tryptic soy broth (TSB) followed by decontamination with a cocktail of NaOH, cycloheximide, and malachite green. Treated water was decontaminated with 0.005 and 0.05% CPC (30 min). After enrichment by filtration, all samples were incubated on Lowenstein-Jensen medium (LJ), Ogawa egg yolk medium (OEY), and Ogawa whole-egg medium containing ofloxacin and ethambutol (OEOE) at temperatures of 30 and 37(deg)C. The efficacy of each method was determined by calculating the positivity rate, negativity rate, contamination rate, mean number of mycobacterial colonies grown, and mean number of different mycobacterial strains isolated. The last value was determined by subjecting the isolates to PCR restriction analysis and mycolic acid thin-layer chromatography. Statistical analysis demonstrated that both the TSB method and 0.05% CPC were appropriate for the decontamination of surface water. Decontamination with 0.005% CPC was best for treated water. The results for incubation on LJ were at least equal to those for incubation on OEY and always superior to the results with OEOE. At an incubation temperature of 30(deg)C, all methods achieved higher yields than at 37(deg)C.     

Creep of the canine pericardium in vivo

In eight open chest dogs we assessed the creep of the pericardium by measuring the increase in surface area of the pericardium, occurring after pericardial surface pressure (Ppe) was rapidly increased by inflating an air-containing balloon positioned between the pericardium and the left ventricular (LV) epicardium. We observed an increase in LV end diastolic pressure (EDP) of 3.6 +/- 3.4 mmHg (1 mmHg = 133.3 Pa) (p less than 0.05) (mean +/- SD) and a reduction in LV anteroposterior (AP) diameter of 8.8 +/- 6.1 mm (p less than 0.01), both of which were stable after 10 s. Mean Ppe increased 11.6 +/- 3.3 mmHg (p less than 0.001). Pericardial surface lengths at 45 and 135 degrees to the long axis of the LV were measured with two pairs of ultrasonic crystals attached to the outer surface of the pericardium. The beam of ultrasound travelling between each pair was directed parallel to the pericardial surface through a film of conducting medium. Initial increase in surface area (calculated as the product of two pericardial lengths) occurring during the first 15 s after balloon inflation was 5.8 +/- 2.5% (p less than 0.001). During the next 30 min, while mean pericardial pressure did not change, pericardial surface area increased another 2.8% (p less than 0.005). This time-dependent 2.8% increase in pericardial surface area (equivalent to an increase in volume of approximately 5%) is due to creep.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduction in human urinary MHPG excretion by guanethidine: urinary MHPG as index of sympathetic nervous activity.

The norepinephrine metabolites methoxyhydroxyphenyl glycol (MHPG) and vanillylmandelic acid (VMA) were measured in the urine of hypertensive subjects before and during adminstration of guanethidine, a peripheral sympatholytic agent which does not cross the blood-brain barrier or deplete adrenal catecholamines. Dosages of guanethidine (1.2 mg/kg/day) sufficient to cause at least a 20 torr reduction in standing systolic blood pressure caused a mean 63% (maximum of 68%) reduction in urinary MHPG excretion (p=0.01) while only causing a mean 37% (maximum of 44%) reduction (p<0.005) in excretion of VMA. These results indicate that MHPG in human urine, as in lower animals, is predominantly the product of peripheral sympathetic nervous system, rather than central nervous system nonrepinephrine metabolism. Urinary MHPG is more sensitive to specific sympatholytic therapy than is urinary VMA, and may be a useful index of sympathetic nervous activity.     

The effect of constraint on the mechanical behaviour of trabecular bone specimens

The effect of the boundary conditions between trabecular bone specimens and the test columns of the testing machine was studied together with the effect of side-constraint on the mechanical behaviour of trabecular bone during axial compression. Cylindrical specimens taken from the upper tibial epiphysis of autopsy knees were tested non-destructively by cyclic compression to 0.8% strain under different conditions. Fixation of the specimens to the test columns by a thin layer of bone cement increased the stiffness by 40% and reduced the energy dissipation to 67% of those measured under unconstrained conditions (p less than 0.001). The thin cement layer alone increased the stiffness 19% and reduced energy dissipation to 86% (n.s.). When the machine was equipped with polished steel columns coated by a film of low-viscous oil, both the stiffness and the energy dissipation were reduced to 93% of those measured under standard conditions (p less than 0.005). Trabecular bone specimens tested side-constrained by the surrounding trabecular bone (in situ) showed a 19% larger stiffness than that measured during later testing of the corresponding machined specimens (p less than 0.005) whereas the energy dissipation was not altered significantly. The same specimens showed a 22% increase of stiffness and a 68% increase of energy dissipation when they were side-constrained by a closely fitting steel cylinder (p less than 0.005).     

枸杞多糖对鲤生长性能和肝胰脏抗氧化能力的影响

为探索枸杞多糖(Lycium barbarum polysaccharide,LBP)对鲤生长性能及肝胰脏抗氧化能力的影响,在试验饲料中分别添加比例为0、0. 005%、0. 01%、0. 015%、0. 02%的枸杞多糖,配制成5种等氮等能试验饲料。以450尾平均初始体质量为(10. 57±0. 89)g的健康鲤为试验对象,随机分为5组,每组3个重复,每个重复30尾试验鱼,分别投喂5种试验饲料,养殖时间为56 d。结果发现,鲤增重率(weight gain ratio,WGR)、特定生长率(specific growth ratio,SGR)均在枸杞多糖添加量为0. 005%时最大,分别为(118. 45±23. 80)%、(1. 39±0. 20)%/d,且差异显著(P0. 05)。枸杞多糖添加量大于0. 005%后,WGR,SGR则呈微弱下降的趋势,但差异不显著(P0. 05);饲料系数(feed conversion ratio,FCR)随着枸杞多糖添加量的提高而呈先降低后升的变化趋势,在0. 005%时最小,为1. 54±0. 24(P0. 05);添加量大于0. 005%后,FCR则呈上升趋势,且差异显著(P0. 05)。随着枸杞多糖添加量的提高,鲤肝胰脏超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)活性均呈现先升高后降低的变化趋势,均在枸杞多糖添加量为0. 005%时最高,分别为(110. 85±7. 51)U/mg、(104. 58±4. 53)mg/(g·min)(P0. 05);添加量大于0. 005%后,SOD活性呈微弱的下降趋势。CAT则在其添加量大于0. 01%后呈微弱的下降趋势(P0. 05);丙二醛(malondialdehyde,MDA)含量则呈先降低后升高的趋势,在添加量为0. 01%时最低,为(0. 73±0. 81)nmol/mg,但差异不显著(P0. 05)。研究说明添加一定比例的枸杞多糖可提高鲤对饲料的利用率,促进其生长,提高鲤机体的抗氧化能力,且综合考虑,鲤饲料中枸杞多糖的适宜添加水平为0. 005%。     

Beneficial effects of angiotensin converting enzyme inhibition on renal function in patients with diabetic nephropathy.

The effects of angiotensin converting enzyme inhibition with captopril were investigated in patients with diabetic nephropathy and hypertension. After nine days'' treatment with captopril glomerular filtration rate was unchanged in 13 patients, whereas renal plasma flow had increased from 265 to 302 ml/min/1.73 m2 body surface area (p less than 0.05) and the filtration fraction had decreased from 14.3 to 12.8% (p less than 0.025). During two years'' treatment with captopril in 14 patients the mean arterial blood pressure had fallen by 5 mm Hg (p less than 0.005) and the deterioration in glomerular filtration rate had decreased from 10.3 to 2.4 ml/min/year (p less than 0.005). There was no correlation between the fall in blood pressure and the reduction in the deterioration of glomerular filtration rate. These findings suggest that the effects of angiotensin converting enzyme inhibition on renal haemodynamics protect renal function. Inhibitors of angiotensin converting enzyme should be considered for lowering blood pressure in patients with diabetic nephropathy.     

Absence of exercise-induced MRI enhancement of skeletal muscle in McArdle's disease.

To assess the role of glycogenolysis in mediating exercise-induced increases in muscle water as monitored by changes in muscle proton relaxation times on magnetic resonance imaging (MRI) and cross-sectional area (CSA), five patients with myophosphorylase deficiency (MPD) were compared with seven controls. Absolute and relative work loads were matched during ischemic handgrip and graded cycling, respectively. Relaxation times of active muscle did not increase after handgrip in MPD (T1: 1 +/- 14%, P greater than 0.1; T2: 4 +/- 4%, P greater than 0.1) but did in controls (T1: 59 +/- 30%, P less than 0.005; T2: 26 +/- 9%, P less than 0.005). The volume of exercised muscles, estimated by CSA, increased in both groups after handgrip (controls: 13.8 +/- 3.5%, n = 7, P less than 0.0001; MPD: 7.5 +/- 1.5%, n = 4, P less than 0.005), but the change was greater in controls (P less than 0.02). Ischemic handgrip in controls resulted in a large increase in finger flexor signal intensity (SI) on short tau-inversion recovery images (25 +/- 7%, n = 3; P less than 0.005 compared with preexercise) and a further increase with subsequent reflow (43 +/- 11%, n = 3; P less than 0.001 compared with rest); in MPD, SI did not increase. The ratio of active to inactive muscle SI did not increase from rest to maximal cycle exercise in MPD (0 +/- 20%, n = 2, P greater than 0.1) but did in normals (73 +/- 36%, n = 3; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of perivascular electromagnetic flow probes on pulmonary hemodynamics

We determined the effect of perivascular electromagnetic flow probes (EMF) on pulmonary hemodynamics in acute experiments. In seven dogs placement of the EMF on the main pulmonary artery (MPA) increased pulmonary arterial pulse pressure by 25% (17.8-21.9 cmH2O, P less than 0.005) and mean right ventricular pressure by 12% (23.2-25.9 cmH2O, P less than 0.001) but did not alter heart rate, systemic blood pressure, mean pulmonary arterial pressure, or right ventricular end-diastolic pressure. This response was not abolished by local application of lidocaine to the MPA. In three cats input impedance was calculated from measurements of pressure and flow in the MPA. Impedance was calculated with flow measured using an EMF and ultrasonic volume flow probe (USF), which avoids the constraining effect of the EMF. When flow was measured with an EMF rather than a USF, there was a significant difference in the impedance spectra (P less than 0.001), but it was only apparent in the moduli greater than six harmonics. We conclude that the EMF does affect right ventricular afterload in acute experiments and alters the measured input impedance.     

Increase of IGF I binding to erythrocyte receptors during the TRH-test: correlation between IGF I binding and thyroid hormone values

The effects of TRH on insulin-like growth factor I receptors were investigated on erythrocytes from 7 GH-deficient children having plasma GH levels less than 10 ng/ml during two provocation tests. Intravenous injection of synthetic TRH (0.2 mg/m2) was followed by a marked increase of IGF I binding on erythrocytes, from 3.9% +/- 0.3% to 5.9% +/- 0.3% (P less than 0.005) after 1 hour and 7.3% +/- 0.4% (P less than 0.005) after 2 hours. The IGF I binding variations were due to an increase in both the receptor affinity and the number of sites. The levels of plasma GH, IGF I, T3, T4, free T4, TSH and prolactin having been determined during the TRH test at 0, 1 hour, and 2 hours after the injection, the increase in the IGF I binding to erythrocytes at the same time correlated with the rise of thyroid hormones: triiodothyronine T3 (P less than 0.001) and thyroxine T4 (P less than 0.005) and not with the level of the other hormones. These findings suggest that thyroid hormones play a role in the regulation of insulin-like growth factor I receptors.     

Relevance of osteoporosis in women with fracture of the femoral neck.

A prospective study of fractures of the femoral neck was conducted over 12 months in order to ascertain the relevance of generalised osteoporosis as determined by metacarpal morphometry. A series of some 200 women sustaining a fracture of the femoral neck after minor trauma had bone mass measurements similar to those of a control population of normal women, and 16% were not osteoporotic. A history of previous fractures was documented in one third of the women, but this was unrelated to the presence or severity of osteoporosis, although over half of the fractures had occurred within the previous four years. Trochanteric fractures were seen more commonly in severely osteoporotic women (p less than 0.005), whereas cervical fractures predominated in those who were not osteoporotic. These findings support the hypothesis that postural instability is the major determinant for femoral neck fracture and that generalised osteoporosis, rather than being a prerequisite for fracture, merely determines the type of fracture sustained.     

Phenotypic spectrum caused by transgenic overexpression of activated Akt in the heart

The serine-threonine kinase, Akt, inhibits cardiomyocyte apoptosis acutely both in vitro and in vivo. However, the effects of chronic Akt activation in the heart are unknown. To address this issue, we generated transgenic mice (TG+) with cardiac-specific expression of a constitutively active mutant of Akt (myr-Akt) driven by the myosin heavy chain-alpha promoter. Three TG+ founders (9-19 weeks) died suddenly with massive cardiac dilatation. Two viable TG+ lines (TG564 and TG20) derived from independent founders demonstrated cardiac-specific transgene expression as well as activation of Akt and p70S6 kinase. TG564 (n = 19) showed cardiac hypertrophy with a heart/body weight ratio 2.3-fold greater than littermates (n = 17, p < 0.005). TG20 (n = 18) had less marked cardiac hypertrophy with a heart/body weight ratio 1.6-fold greater than littermates (n = 17, p < 0.005). Isolated TG564 myocytes were also hypertrophic with surface areas 1.7-fold greater than littermates (p < 0.000001). Echocardiograms in both lines demonstrated concentric hypertrophy and preserved systolic function. After ischemia-reperfusion, TG+ had a 50% reduction in infarct size versus TG- (17 +/- 3% versus 34 +/- 4%, p < 0.001). Thus, chronic Akt activation is sufficient to cause a spectrum of phenotypes from moderate cardiac hypertrophy with preserved systolic function and cardioprotection to massive cardiac dilatation and sudden death.     

Effects of exercise and conditioning on clotting and fibrinolytic activity in men

Sixty healthy men in three physical fitness categories (sedentary, on no organized fitness program; joggers, running 5-15 miles/wk; and marathoners, running greater than 50 miles/wk) were evaluated for changes in blood clotting and fibrinolytic activity before and after maximum exercise on a treadmill according to the Bruce protocol. The rate of blood clotting, as measured by prothrombin times, partial thromboplastin times and thrombin times, was accelerated by exercise (all P less than 0.005). The ability of euglobulin clots and plasma clots to lyse incorporated 125I-fibrin, termed 125I-euglobulin clot lysis (IEL) and 125I-plasma clot lysis (IPCL), were used as indexes of fibrinolytic activity. Marathoners had greater increases in fibrinolytic activity with exercise (76% compared with 63% for joggers and 55% for sedentary subjects by IEL; 427% compared with 418% for joggers and 309% for sedentary subjects by IPCL; all P less than 0.05). Fibrin degradation products increased with exercise (P less than 0.005 for the total group of 60 subjects). The absolute concentrations of alpha 2-plasmin inhibitor, alpha 2-macroglobulin, and antithrombin III increased with exercise (all P less than 0.005), but when concentrations were corrected for acute shifts of plasma water during exercise, the quantity of these inhibitors actually decreased (all P less than 0.005). The changes in clotting assays with exercise were not significantly correlated with changes in whole blood lactate, blood pyruvate, or rectal temperatures. Fibrinolytic assays before and after exercise correlated poorly to moderately with blood lactates (IEL: r = 0.441 and r = 0.425, respectively; IPCL: r = 0.294 and r = 0.544, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Molecular distribution and charge of polylysine layers at the surface of lipid membranes and mica

Electrophoretic mobility of cardiolipin liposomes was measured in the presence of polylysines of different molecular weight at various concentrations of the background electrolyte (KCl). The electrophoretic mobility in a liposome suspension changes its sign and reaches a plateau at high polylysine content. The surface charge in the plateau region was determined according to the Gouy-Chapman model of the electrical double layer. The average charge density was found to equal 0.005 and 0.016 Coulomb/m² for the polymer length of 5 and 12 units (bases), respectively, and 0.032 Coulomb/m² for polylysines with the length of 130 and 1435 units. The molecular distribution of these polylysines was studied at the mica surface using atomic force microscopy in the 10-mM KCl solution. It was shown that pentalysine molecules covered uniformly about 90% of the surface with the layer thickness of about 0.8 nm. The high-molecular polylysines cover about 60% of the surface with the layer thickness of more than 1.5 nm. The data suggest that the polymer forms a compact layer on the membrane surface; the charge density at the outer surface is determined both by the polymer properties and by the total amount of anionic lipids, irrespective of their ionization state.     

A rapid redistribution of the transferrin receptor to the cell surface of HL-60 cells and K562 cells upon treatment with dimethyl sulfoxide due to slowing of endocytosis

Treatment of two human leukemia cell lines with 1.25% dimethyl sulfoxide at 37 degrees C results in a rapid increase in the number of transferrin receptors on the cell surface detected by fluorescein-labeled anti-transferrin receptor antibodies. Both HL-60 cells, a human myeloid cell line, and K562 cells, a human erythroid-myeloid cell line, showed a 25-65% increase in cell surface transferrin binding in parallel experiments. Scatchard plot analysis of the data indicates that the number of receptors increases while the affinity of transferrin for the receptor remains the same. This rapid increase in the number of receptors at the cell surface appears to be due to a slowing of endocytosis rather than an increase in externalization of the receptor.     

The interrelationship of cesium, intracellular sodium activity, and pacemaker potential in cardiac Purkinje fibers

The actions of cesium (Cs) on intracellular sodium activity (aiNa), membrane potentials, and force were studied in sheep cardiac Purkinje and myocardial fibers superfused in vitro. In Purkinje fibers, Cs (2 mM) decreased diastolic depolarization, aiNa (-6.7%, p less than 0.005), and force (-28.0%, p less than 0.01). The effects of 4 and 8 mM Cs were more pronounced. In quiescent fibers, Cs (2-4 mM) also decreased aiNa (-17.3%, p less than 0.005) and induced an initial hyperpolarization (+5.6 +/- 1.3%, p less than 0.005) followed by a return toward control. Diastolic depolarization was almost abolished by driving the fibers at 180/min (diastole was very short) but still Cs decreased aiNa (-15.4%). Tetrodotoxin decreased aiNa (-16.2%, p less than 0.025) and reduced the Cs-induced fall in aiNa (-2.2%, p less than 0.05). In zero [K]o, Cs decreased aiNa and caused repolarization. In 0.1 mM strophanthidin, Cs did not decrease aiNa any longer and affected the membrane potential little. In quiescent myocardial fibers, Cs (4 mM) decreased aiNa (-12.6%, p less than 0.05) and transiently hyperpolarized (+2.1%). Rubidium (2 mM) decreased aiNa and resting potential in Purkinje fibers and in myocardial fibers and also decreased diastolic depolarization in Purkinje fibers. Thus, cesium and rubidium decrease aiNa and modify the membrane potential but not through a block of the inward pacemaker current If.     

Characterization of the cytoplasmic fibrils of Treponema refringens (Nichols)

The cytoplasmic fibrils of Treponema refringens were studied in situ by electron microscopy of thin sectioned and negatively stained cells. From 5 to 21 parallel fibrils ran through the cell in a band adjacent to the inner side of the cytoplasmic membrane, on the inner sides of the curves of the spirochete. The nuclear areas of cells were adjacent to the fibrils. Cross sections of fibrils isolated from cells which had been lysed were polygonal and not uniformly electron dense. Polyacrylamide gel electrophoresis of partially purified fibril preparations indicated their main component to be a protein with a molecular weight of 97,000. Fibrils were solubilized by 1% trypsin, 1% pronase, 6 M urea, 1 N HCl, 0.005 N NaOH or 1.3% sodium dodecyl sulfate. By electron microscopy of negatively stained isolated fibrils, each fibril was found to be a complex arrangement of strands rather than a single tubule.Abbreviations CM Cytoplasmic membrane - PTA Phosphotungstic acid - UOx Uranyl oxalate - SDS sodium dodecyl sulfate This communication is Journal Acticle No. 7644 from the Michigan Agricultural Experiment Station     

Disruption of the Primary Fouling Sequence on Fiber Glass-Reinforced Plastic Submerged in the Marine Environment

Fiber glass-reinforced plastic immersed in an experimental estuarine mesocosm fouled at estimated rates of 0.5, 5.5, and 18.8 ng (wet weight) mm⁻² day⁻¹ over days 0 to 2, 2 to 6, and 6 to 14, respectively. Protists, dominated by diatoms, which developed between days 3 and 6 and covered 90% of the undisturbed surface in 2 weeks, were effectively removed by twice-weekly brushing of the surface to maintain an immature 3-day bacterial film which covered 12% or less of the surface and had a biomass 3 orders of magnitude smaller than surfaces with 2 weeks' unrestricted fouling. Direct brushing of the fiber glass-reinforced plastic tank walls of experimental estuarine mesocosms minimized the “wall effect” by keeping a surface that maintained a low biomass of a slowly accumulating bacterial film rather than a surface which supported the more rapid accumulation of protists which in turn may induce the settlement of invertebrates and macrophytes.