Learning of apple fruit biotypes by apple maggot flies

Previously, we showed that after a female apple maggot fly, Rhagoletis pomonella,arrives on a host hawthorn or apple fruit, its propensity to accept (bore into) or reject that fruit prior to egg deposition can be modified by previous ovipositional experience with one or the other species and, hence, involves learning. Here, we present both field and laboratory evidence indicating that females also are able to learn characteristics of three different apple biotypes or cultivars: Early Macintosh, Red Delicious, and Golden Delicious. We suspect that females learn to discriminate among these three cultivars on the basis of differences in chemical stimuli among cultivars. The effect of fruit cultivar learning was not as strong as the effect of fruit species learning.     

Optimal growth of Streptococcus cremoris HP in milk is related to β- and ϰ-casein degradation

Summary Initiation of growth and the growth rate of Streptococcus cremoris HP in a complete synthetic medium supplemented with an enzymatic digest of casein appeared to be inhibited by (di)hydrogen phosphate. The inhibitory effect of the inorganic phosphate fraction was counteracted by -glycerophosphate.Growth experiments involving different caseins or combinations of caseins as the only source of nitrogen (and essential amino acids) were performed in an adapted medium in which optimal growth was expected to depend only on the type of nitrogen source. Maximal growth occurred on a combination of -casein and a relatively low concentration of . It approximated the growth on milk added to the medium. These results and those showing the capacity of the organism to grow on milk-derived fractions suggest that in milk it is mainly the soluble (-) casein fraction together with the easily accessible hydrophilic part of micellar , which maintain optimal growth.     

Media from Rhabdomyosarcoma and Neuroblastoma Cell Cultures Stimulate in Vitro Aggregation and Fibrillization of Amyloid Beta-Protein

In vitro aggregation and fibrillization of synthetic amyloid beta-protein A 1–40 was assessed in the conditioned media from rhabdomyosarcoma (CRL 1598, HTB 82, HTB 153, CCL 136), adenocarcinoma (CCL 218), neuroblastoma (SY5Y), and COS cells cultured in the absence and presence of 10% heat-inactivated fetal bovine serum (FBS). The aggregation and formation of cross -pleated sheet structures in A was quantitated by Thioflavin T (ThT) fluorescence spectroscopy, while the morphology of A fibrils was examined in negative staining in the electronmicroscope (EM). In cultures supplemented with 10% FBS, the conditioned media from CRL 1598, HTB 82, CCL 218, and SY5Y cell cultures stimulated A aggregation in a time-dependent manner as compared to that of control (serum-containing medium that had not been exposed to cells). The order of stimulation was SY5Y > CRL 1598 HTB 82 > CCL 218, and the stimulation was higher in 2 week cultures than in 1 week cultures. Similar studies using media from HTB 153, CCL 136 and COS cell cultures showed no effect on A 1–40 aggregation. In serum-free cell cultures, only media from SY5Y and CRL 1598 could promote significant aggregation of A 1–40. Negative staining in EM revealed A fibril formation only with conditioned media from SY5Y and CRL 1598 cultured under serum free conditions; no A fibrils were noticed in media from cell cultures supplemented with 10% FBS. We propose that both the SY5Y neuroblastoma cell line and the CRL 1598 rhabdomyosarcoma cell line may serve as experimental models for in vitro studies of extracellular aggregation and fibrillization of A-protein in cell cultures, while rhabdomyosarcoma HTB 82 and adenocarcinoma CCL 218 may be models for study of A aggregation only.     

1H, 13C and 15N NMR assignments and solution secondary structure of rat Apo-S100β

Summary The ¹H, ¹³C and ¹⁵N NMR assignments of the backbone and side-chain resonances of rat S100 were made at pH 6.5 and 37°C using heteronuclear multidimensional NMR spectroscopy. Analysis of the NOE correlations, together with amide exchange rate and ¹H, ¹³C and ¹³C chemical shift data, provided extensive secondary structural information. Thus, the secondary structure of S100 was determined to comprise four helices (Leu³-Ser¹⁸, helix I; Lys²⁹-Leu⁴⁰, helix II; Gln⁵⁰-Glu⁶², helix III; and Phe⁷⁰-Ala⁸³, helix IV), four loops (Gly¹⁹-His²⁵, loop I; Ser⁴¹-Glu⁴⁹, loop II; Asp⁶³-Gly⁶⁶, loop III; and Cys⁸⁴-Glu⁹¹, loop IV) and two -strands (Lys²⁶-Lys²⁸, -strand I and Glu⁶⁷-Asp⁶⁹, -strand II). The -strands were found to align in an antiparallel manner to form a very small -sheet. This secondary structure is consistent with predictions that S100 contains two helix-loop-helix Ca²⁺-binding motifs known as EF-hands. The alignment of the -sheet, which brings the two EF-hand domains of S100 into close proximity, is similar to that of several other Ca²⁺ ion-binding proteins.     

Phosphorylation of pollen proteins in relation to self-incompatibility in rye (Secale cereale L.)

The gametophytic two-locus self-incompatibility (SI) system in rye was investigated in view of a possible involvement of protein phosphorylation and Ca²⁺ as constituents of a signal transduction mechanism. Phosphorylation kinetics in pollen grains was found to be significantly different after in vitro treatment of pollen with either cross or self stigma proteins, with a pronounced phosphorylation activity in self-treated pollen grains. Loss of SI in self-compatible (SC) mutants was associated with a significantly decreased basic phosphorylation activity in untreated pollen grains as compared to SI genotypes. Separation of phosphorylated pollen proteins by SDS-PAGE reveals four major proteins in the MW range of 43–82 kDa which were differently phosphorylated in SI vs SC genotypes as well as in cross vs self-treated pollen grains. Application of different protein kinase inhibitors and the Ca²⁺ antagonists verapamil and La³⁺ to isolated stigmas resulted in an inhibition of the SI response in in vitro self-pollination. The role of protein kinases and Ca²⁺ as constituents of a putative SI-specific signal transduction mechanism is discussed.     

The effect of intracapillary media feed protocols on hollow fiber cell culture

Summary Two intracapillary (IC) media feed protocols termed media rich and media lean were examined in an effort to understand the effect of this variable on hollow fiber cell cultures. The media rich protocol emphasized a high volume IC media per day (5 liters) containing no serum and a normal amount of extracapillary (EC) media serum (10% v/v). Alternatively, the media lean protocol used up to 1.0 liter of IC media per day containing 5% v/v serum and increased EC media serum (20% v/v). Both protocols produced substantial amounts of antibody in 25 days using HFN7.1 hybridoma cells (ATCC CRL 1606), however the media rich protocol produced twice as much antibody as the media lean protocol. The metabolism of the cells was dramatically different as measured by glucose uptake rate (GUR) with media lean cells having a six-fold lower GUR. Our results indicate that the media rich protocol is useful for producing larger amounts of antibody in a short time frame. The media lean protocol may be considered when the production costs of antibody, particularly media and serum, is the overriding concern.     

Binding of Amyloid Beta-Protein to Intracellular Brain Proteins in Rat and Human

Amyloid beta-protein (A), in its soluble form, is known to bind several circulatory proteins such as apolipoprotein (apo) E, apo J and transthyretin. However, the binding of A to intracellular proteins has not been studied. We have developed an overlay assay to study A binding to intracellular brain proteins. The supernatants from both rat and human brains were found to contain several proteins that bind to A 1–40 and A 1–42. No major difference was observed in the A binding-proteins from brain supernatants of patients with Alzheimer's disease and normal age-matched controls. Binding studies using shorter amyloid beta-peptides and competitive overlay assays showed that the binding site of A to brain proteins resides between 12–28 amino acid sequence of A. The presence of several intracellular A-binding (AB) proteins suggests that these proteins may either protect A from its fibrillization or alternatively promote A polymerization. Identification of these proteins and their binding affinities for A are needed to assess their potential role in the pathogenesis of Alzheimer's disease.     

Capnocytophaga: New genus of Gram-negative gliding bacteria. II. Morphology and ultrastructure

Gram-negative, anaerobic gliding bacteria were isolated from normal supragingival plaque and from periodontal lesions. Isolates could be divided into two size classes: small 2.4–4.2 m×0.38–0.5 m and large 4.8–5.8 m×0.42–0.6 m cells. The outer membrane was either loose-fitting and wavy, or taut, and of variable thickness. An electron-dense fuzz was discernible on several of the isolates. The periplasmic region was of variable electron-density. The genus Capnocytophaga has been proposed for these organisms based on morphological and cultural characteristics.     

Non-Indigenous Species and Ecological Explanation

Within the last 20 years, the US has mounted amassive campaign against invasions bynon-indigenous species (NIS) such as zebramussels, kudzu, water hyacinths, and brown treesnakes. NIS have disrupted native ecosystemsand caused hundreds of billions of dollars ofannual damage. Many in the scientificcommunity say the problem of NIS is primarilypolitical and economic: getting governments toregulate powerful vested interests thatintroduce species through such vehicles asships' ballast water. This paper argues that,although politics and economics play a role,the problem is primarily one of scientificmethod. Even if commercial interests werewilling to spend the necessary funds to controlNIS, and even if government were willing toregulate them, ecological theory is notadequate to provide clear direction for eithereffort. The paper argues there is nocomprehensive, predictive theory ofinvasibility, as part of a larger theory ofcommunity structure, that might guideecological decision making regarding NIS, andfor at least three reasons. (1) There is nofirm definition of NIS, native, exotic,and so on, and ecologists do not use the termsconsistently; as a result, biologists debatingvarious accounts of community structure andecological explanation often do not even makelogical contact with each other. (2) Thedominant theory used to understandinvasibility, island biogeography, has noprecise predictive power and is unable toclarify when NIS might promote biodiversity andwhen they might hinder it. (3) There are nofirm, empirical generalizations that revealwhen a colonizer or a NIS might be likely totake over a new environment, and when it mightnot succeed in doing so. As a result,scientists have only rough rules of thumb toshore up their arguments against NIS. Given theincompleteness of current ecological theory,the paper closes with several suggestions forways that study of NIS might enhanceunderstanding of basic commmunity structuresand vice versa.     

Orthopaedic implant related metal toxicity in terms of human lymphocyte reactivity to metal‐protein complexes produced from cobalt‐base and titanium‐base implant alloy degradation

Metal toxicity from sources such as orthopaedic implants was investigated in terms of immune system hyper-reactivity to metal implant alloy degradation products. Lymphocyte response to serum protein complexed with metal from implant alloy degradation was investigated in this in vitro study using primary human lymphocytes from healthy volunteers (n = 10). Cobalt chromium molybdenum alloy (CoCrMo, ASTM F75) and titanium alloy (Ti6Al4V, ASTM F136) beads (70 m) were incubated in agitated human serum at 37 degrees Celsius to simulate naturally occurring metal implant alloy degradation processes. Particulate free serum samples, which were incubated with metal, were then separated into molecular weight based fractions. The amounts of soluble Cr and Ti within each serum fraction were measured and correlated with lymphocyte proliferation response to the individual serum fractions. Lymphocytes from each subject were cultured with 11 autologous molecular weight based serum fractions either with or without added metal. Two molecular weight ranges of human serum proteins were associated with the binding of Cr and Ti from CoCrMo and Ti implant alloy degradation (at < 30 and 180–330 kDa). High molecular weight serum proteins ( 180 kDa) demonstrated greater lymphocyte reactivity when complexed with metal released from CoCrMo alloy and Ti alloy than with low (5–30 kDa) and midrange (30–77 kDa) serum proteins. When the amount of lymphocyte stimulation was normalized to both the moles of metal and the moles of protein within each fraction (MetalProtein Complex Reactivity Index, MPCRI), Cr from CoCrMo alloy degradation demonstrated approximately 10 fold greater reactivity than Ti in the higher molecular weight serum proteins ( 180–250 kDa). This in vitro study demonstrated a lymphocyte proliferative response to both CoCrMo and Ti alloy metalloprotein degradation products. This response was greatest when the metals were complexed with high molecular weight proteins, and with metalprotein complexes formed from CoCrMo alloy degradation.     

The γ-Glutamyl Transpeptidase Inhibitor Acivicin Preserves Glutathione Released by Astroglial Cells in Culture

The release of glutathione from astroglial cells was investigated using astroglia-rich primary cultures prepared from the brains of newborn rats. These cells release glutathione after onset of an incubation in a glucose-containing minimal medium. The amount of extracellular glutathione increased with the time of incubation, although the accumulation slowed down gradually. An elevated rate of increase of the glutathione concentration in the incubation medium was found if the astroglial ectoenzyme -glutamyl transpeptidase was inhibited by acivicin. The activity of -glutamyl transpeptidase in astroglia-rich primary cultures, which was found to be 1.9 ± 0.3 nmol/(min × mg protein), was markedly reduced if the cells had been incubated in the presence of acivicin. After 2 h of incubation with acivicin half-maximal and maximal inhibition of -glutamyl transpeptidase activity was found at concentrations of about 5 M and 50 M, respectively. In the presence of acivicin at a concentration above 10 M the glutathione content found released from astroglial cells apparently increased almost proportional to time for up to 10 h. Under these conditions the average rate of release was 2.1 ± 0.3 nmol/(h × mg protein) yielding after a 10 h incubation an extracellular glutathione content three times that of the medium of cells incubated without inhibitor. Half-maximal and maximal effects on the level of extracellular glutathione were found at 4 M and 50 M acivicin, respectively. After a 10 h incubation with acivicin the intracellular content of glutathione was reduced to 75% of the level of untreated astroglial cultures. These results suggest that glutathione released from astroglial cells can serve as substrate for the ectoenzyme -glutamyl transpeptidase of these cells.     

Corticosteroid-binding globulin synthesis and distribution in rat white adipose tissue

The lactone isolated from Fusarium termed L659,699 is a potent specific inhibitor of the enzyme 3hydroxi3methylglutaril coenzyme A (HMG-CoA) synthase. In cultures of smooth muscle cells (SMC) isolated from aortic-arch of control (CSMC) and 5% of cholesterol diet (Ch-SMC) treated chicks, the incorporation of (¹⁴C)acetate to lipids (cholesterol, triacylglycerides and cholesterol ester) were greater in ChSMC cultures than in CSMC and the presence of 0.05 M L659,699 for 2 h in the incubation medium decrease the synthesis of cholesterol however the triacylglycerides synthesis increase. The effect of inhibitor is stronger in young cultures (3–4 steps) than in the older ones (11–12 steps). In young CSMC and ChSMC cultures the inhibition of cholesterol and triacylglycerides synthesis by L659,699 was reversal.     

Sucrose in storage media and cultivar affects post-storage regrowth of <Emphasis Type="Italic">in vitro</Emphasis> Hosta propagules

The goal of this research was to investigate if culturing in high sucrose (5%) liquid media during multiplication phase (stage II) would enhance endogenous sugar levels and dry matter sufficiently to allow storage of in vitro plants in sugar free media without adversely affecting post-storage recovery. Hosta tokudama Newberry Gold (NBG) and Hosta Striptease were cultured in Murashige and Skoog (MS) media containing 5% sucrose during stage II and transferred to rooting phase (stage III) in MS medium without (0%) sucrose or with 3% sucrose for 4weeks. At the end of stage III, cultures were stored, with the remaining media, at 10°C with 5molm^–2s^–1 photosynthetic photon flux (PPF) from cool white fluorescent lamps for 7 or 14weeks with or without a 2-week dark period prior to removal from storage. In both cultivars, stage III plants cultured in 3% sucrose media had higher soluble sugar levels and greater shoot and root biomass than those cultured in 0% sucrose media. Shoot and root soluble sugars decreased during storage. Shoot growth ceased during storage in both media. Root dry matter continued to increase in plants stored in 3% sucrose media but did not change in 0% sucrose media. Plants cultured in 3% sucrose media had less leaf chlorosis and less mortality after 7 or 14weeks of low temperature storage than the plantlets from sugar free media. Extending the storage period from 7 to 14weeks or introduction of 2-week dark period at the end of storage did not affect leaf chlorosis or plant mortality during acclimatization. Post-storage growth varied with the cultivar. Benefit of having sucrose in storage media was to develop a strong root system that aided the acclimatization and post-storage growth following 7 or 14week storage. Sucrose loading by culturing plants in liquid media containing 5% sucrose did not allow storage in sugar free media without adversely affecting post-storage growth in both cultivars.     

Seasonal changes in the breeding origin of migrating Dunlins(Calidris alpina) as revealed by mitochondrial DNA sequencing

Summary In the North Sea Wadden Sea, Dunlins of the two subspeciesCalidris alpina alpina andC. a schinzii occur on migration. In this study, I investigate the putative breeding origin of Dunlins caught at the Sylt/Rømø Wadden Sea during peak migration in spring and autumn. Genetic variation and haplotype composition was assessed by sequence analysis of the mitochondrial Control Region. A comparison with population genetic measures of breeding populations suggests that Dunlins caught in spring (May) predominantly belong to alpina while a high percentage of specimens sampled in autumn (September) belong to schinzii This study demonstrates that the putative origin of migrating birds can be assessed by quantitative genetic measures, even in the absence of exclusive genetic markers.

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Saisonale Unterschiede in der Brutherkunft migrierender AlpenstrandläuferCalidris alpina, detektiert durch Sequenzanalyse mitochondrialer DNA

Zusammenfassung Im Wattenmeer zur Zugzeit auftretende Alpenstrandläufer gehören zu den beiden UnterartenCalidris alpina alpina undC. a. schnizii. In dieser Untersuchung wurde die wahrscheinliche Brutherkunft von Alpenstrandläufern ermittelt, die zur Hauptzugzeit im Frühjahr und Herbst im Sylt/Rømø-Wattenmeer gefangen wurden. Hierzu wurden genetische Variation und Haplotypenverteilung mittels DNA-Sequenzanalyse der mitochondrialen Kontrollregion untersucht. Ein Vergleich mit populationsgenetischen Maßzahlen der Brutpopulationen deutet an, daß es sich bei im Frühjahr (Mai) gefangenen Alpenstrandläufern vor allem um alpina, bei im Herbst (September) gefangenen zum großen Teil um schinzii handelt. Die Untersuchung zeigt, daß die wahrscheinliche Herkunft migrierender Vögel mit Hilfe quantitativer genetischer Maßzahlen ermittelt werden kann, auch wenn exklusive genetische Marker für die Ursprungspopulationen fehlen.

     

Protein compositional analysis of inclusion bodies produced in recombinant Escherichia coli

Summary Culture conditions favouring the simulataneous formation of soluble protein and inclusion bodies (IBs) were chosen for producing the cytoplasmic protein -galactosidase or the periplasmic protein TEM--lactomase. Soluble and insoluble cell fractions of Escherichia coli producing either -galactosidase or TEM--lactomase were analyzed by one- and two-dimensional gel electrophoresis and subsequent silver staining or immunodection of the recombinant protein. The results show that truncated fragments of the recombinant protein were not present in the soluble cell fraction but accumulate in the IB fraction. The presense of other cellular, non-plasmid-encoded proteins in IB preparations such as the outer membrane proteins OmpF, OmpC, and OmpA or the ribosomal subunit proteins L7/L12 was attributed to co-precipitation of cell-debris-associated components. Protein-folding enzymes were not detected in IB preprations. The specificity of in-vivo protein association in the formation of IBs and its implication on protein purification is discussed. Correspondence to: J. E. Bailey     

Sertoli cells of adult rats “in vitro”

Summary A cell line obtained from isolated seminiferous tubules of adult rat testis has been studied in vitro over a period of 35 days.Light and electron microscopic studies performed from hour 2 to the end of culture have shown the presence of a monomorphic cell population. After 5–6 days of culture the cells formed a monolayer. The cytoplasm of the cells contained numerous lipid bodies and produced numerous projections. The nucleus showed several indentations and one or more nucleoli. From the 9th to the 15th day of culture the cells developed a large amount of endoplasmic reticulum, Golgi apparatus and aggregates of electron dense granules. From the 20th to 40th day the cell cultures progressively degenerated.Immunochemical analysis of the culture medium revealed the presence of estradiol-17, which reached its maximum production rate from the 8th day to the 18th day of culture. Corresponding to cell involution estradiol concentration underwent a rapid decrease.On the basis of morphological and biochemical data the cells could be considered Sertoli cells.This work was supported by Grants n. 74.00155.04 and n. 75.01224.04 from the Consiglio Nazionale delle Ricerche (C.N.R.), Rome, Italy, and by Istituto di Ricerca F. Angelini, Rome, ItalyPart of this work was presented at the 10th Italian Congress of Electron Microscopy. Ostuni 1–4 October 1975The excellent technical assistance of Miss Laura Vassallo, Daniela Venturini and Mr. Massimo Rosati and Mario Termine is deeply appreciated     

Comparison of [35S]GTPγS binding to plasma membranes and endomembranes prepared from soybean and rat

Summary Plasma membranes were prepared from soybean hypocotyls and roots by aqueous two-phase partitioning and subsequent free-flow electrophoresis. The highly purified plasma membranes bound [³⁵S]GTPS with a relatively high affinity (K_d10nM). The binding was saturable and specific as it was indicated by the displacement of bound [³⁵S]GTPS by unlabeled GTPS and GTP, but not by ATPS, ATP, UTP or CTP. ITP was intermediate in its ability to displace [³⁵S]GTPS. When soybean plasma membrane proteins were separated by SDS-PAGE and displayed by autoradiography, two major [³⁵S]GTPS binding proteins were revealed with apparent molecular weights of 24 and 28 kDa. Results with plasma membranes from soybean hypocotyls and roots were similar but differed from those with plasma membranes prepared from rat liver and adipocytes where only a single major [³⁵S]GTPS binding activity with a molecular weight of 28 kDa was observed.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - G protein hetero-trimeric GTP binding protein with , , subunits - G_n protein GTP binding protein detected on nitrocellulose blots - GTPS guanosine 5-[-thio]triphosphate - IAA 3-indoleacetic acid - SDS-PAGE sodium dodecylsulfate-polyacrylamide gel electrophoresis     

Stable sulfur isotopic biogeochemistry of the Hubbard Brook Experimental Forest, New Hampshire

In natural ecosystems, differences often exist in the relative abundanceof stable S isotopes (°³⁴S) that can provide clues as tothe source, nature, and cycling of S. Values of °³⁴S inprecipitation, throughfall, soils, soil solution, and stream waters weremeasured at the Hubbard Brook Experimental Forest (HBEF), New Hampshire.Values of °³⁴S in precipitation and throughfall weresimilar to each other but differed seasonally. Precipitation°³⁴S values were higher in the dormant season[°³⁴S = 5.9±0.6 (17)][Mean + SE(N)]than in the growing season [°³⁴S = 5.0±0.6(40)] but throughfall growing-season values were higher[°³⁴S = 5.6±0.6(68)] than for the dormantseason [°³⁴S = 4.9±0.7 (9)]. Different treespecies did not affect throughfall °³⁴S values. In soilsolution, °³⁴S values were higher in the growing season(°³⁴S = 8.9±2.8; 8.8±1.7;and 4.0±0.6 for Oa, Bh, and Bs horizons, respectively) thanin the dormant season (°³⁴S = 5.6±1.5;3.7±2.4; and 3.4±1.2 for Oa, Bh, and Bshorizons, respectively). These seasonal differences in°³⁴S were probably caused by biological isotopicfractionation. The °³⁴S values in streams were generally2 lower and more variable than those in precipitation andthroughfall, suggesting fractionation and/or different isotopic sources inthe soil.     

Laboratory culture studies of Trichodesmium isolated from the Great Barrier Reef Lagoon, Australia

Cultures of Trichodesmium from the Northern and Southern Great Barrier Reef Lagoon (GBRL) have been established in enriched seawater and artificial seawater media. Some cultures have been maintained with active growth for over 6years. Actively growing cultures in an artificial seawater medium containing organic phosphorus (glycerophosphate) as the principal source of phosphorus have also been established. Key factors that contributed to the successful establishment of cultures were firstly, the seed samples were collected from depth, secondly, samples were thoroughly washed and thirdly, incubations were conducted under relatively low light intensities (PAR 40–50molquantam^–2s^–1). N₂ fixation rates of the cultured Trichodesmium were found to be similar to those measured in the GBRL. Specific growth rates of the cultures during the exponential growth phase in all enriched media were in the range 0.2–0.3day^–1 and growth during this phase was characterised by individual trichomes (filaments) or small aggregations of two to three trichomes. Characteristic bundle formation tended to occur following the exponential growth phase, which suggests that the bundle formation was induced by a lack of a necessary nutrient e.g. Fe. Results from some exploratory studies showed that filament-dominated cultures of Trichodesmium grew over a range of relatively low irradiances (PAR 5–120molquantam^–2s^–1) with the maximum growth occurring at 40–50molquantam^–2s^–1. These results suggest that filaments of the tested strain are well adapted for growth at depth in marine waters. Other studies showed that growth yields were dependent on salinity, with maximum growth occurring between 30 and 37psu. Also the cell yields decreased by an order of magnitude with the reduction of Fe additions from 450 to 45nM. No active growth was observed with the 4.5nM Fe addition.     

Effects of glycine supplement on protein production and release in recombinant Escherichia coli

Summary The effect of glycine supplement to growth media on protein expression and release in a recombinant strain RR1 of E. coli was investigated. Addition of glycine to the growth media in moderate amount (up to 1%) was observed to enhance significantly the release of periplasmic proteins from the cell to the broth. The extracellular activities of the model enzymes -amylase and -lactamase were increased by a factor of 16.3 and 3.8 respectively in the presence of glycine. These activities corresponded to about 50% of the total production for each protein. Furthermore, with glycine supplement the total enzyme activity of both -amylase, -lactamase as well as -galactosidase were increased by a factor of about 2.5. Cell growth characteristics and low extracellular activity of the cytoplasmic protein -galactosidase are indicative that glycine does not cause significant cell-lysis for a concentration below 0.7%.