Inactivation of Bacteriophages by ε-Poly-l-lysine Produced by Streptomyces

Degradation of a β-O-4lignin substructure model dimer by a white rot fungus, Phanerochaete chrysosporium, was investigated using a culture containing H₂¹⁸O, and the following conclusions were made. a) The direct hydrolysis at C_β of the β-O-4 dimer was not involved in formation of arylglycerol. b) About half of the oxygen at the benzyl (C_α) position of the glycerol was derived from H₂O (H₂¹⁸O) and the other half was from the oxygen at the benzyl (C_α) position of the substrate β-O-4 dimer. c) But, the oxygen at the C_α position of the substrate β-O-4 dimer did not migrate to the C_α position of the aryglycerol.     

Polarity induced by chloramphenicol and relief by suA

The suA allele, known to relieve polarity in Escherichia coli, also relieves a unique polar effect on E. coli tryptophan operon messenger RNA produced by chloramphenicol.     

Oviposition by Lobesia botrana is stimulated by sugars detected by contact chemoreceptors

Abstract.  The influence of glucose, fructose and sucrose on oviposition site selection by Lobesia botrana is studied by combining behavioural and electrophysiological experiments. Oviposition choice assays, using surrogate grapes treated with grape berry surface extracts of Vitis vinifera cv. Merlot at different development stages, show that L. botrana females are most stimulated by extracts of mature berries containing the highest concentrations of glucose and fructose. Choice assays reveal that the oviposition response to these sugars is dose-dependant (with a threshold of the applied solution = 10 m m and a maximum stimulation at 1  m ) and that females are more sensitive to fructose than to glucose. Tarsal contact-chemoreceptor sensilla are unresponsive to stimulation with sugars but the ovipositor sensilla contain at least one neurone most sensitive to fructose and sucrose with a threshold of approximately 0.5 m m . Corresponding to the behavioural data, glucose is significantly less stimulatory to sensilla than fructose or sucrose. It is argued that fructose may be of special importance for herbivorous insects exploiting fruit as an oviposition site.     

Body composition analysis by DEXA by using dynamically changing samarium filtration

Gotfredsen, Anders, Lene Bæksgaard, and Jannik Hilsted.Body composition analysis by DEXA by using dynamically changing samarium filtration. J. Appl. Physiol.82(4): 1200-1209, 1997.Dual-energy X-ray absorptiometry (DEXA)has a high accuracy for body composition analysis but is influenced bybeam hardening and other error sources in the extremes of measurement.To compensate for beam hardening, the Norland XR-36 introduces adynamically changing samarium filtration system, which depends on thecurrent-absorber thickness. With this system we found a good agreement(r = 0.99) between reference andmeasured amounts of tissue or fat percentages in a plastic phantom andin smaller (~0.5-4 kg) and larger (~5-20 kg) piles oftissue (ox muscle and lard). Scans of six healthy volunteers coveredwith combinations of beef and lard (~5-15 kg) showed a goodagreement (r = 0.99) between referenceand DEXA values of added soft tissue mass and fat percentage. Weconclude that the DEXA method (and, in particular, the Norland XR-36using dynamic filtration) has a high accuracy for body compositionanalysis. It has a potential for gaining status as a reference methodin the future and may presently be used as a supplement to thetraditional methods for body composition analysis.

     

Cost-effective copper removal by electrosorption powered by microbial fuel cells

This work studied a cost-effective electrosorption that driven by microbial fuel cells (MFC-sorption) to remove Cu²⁺ from wastewater without an external energy supply. The impact factors, adsorption isotherms and kinetics of the novel process were investigated. It indicated that a low electrolyte concentration and a high solution pH could enhance the Cu²⁺ removal efficiency, while the adsorption capacity increased with the increase of numbers of MFCs in series and the initial Cu²⁺ concentration. The adsorption isotherms study indicated that the monolayer adsorption in MFC-sorption was dominant. The kinetics study suggested the increase of initial Cu²⁺ concentration could enhance the initial adsorption rate. The electrode characterizations verified the existence of Cu₂O and Cu on the electrode surface of active carbon fibers (ACFs), suggesting that MFC-sorption was not only an adsorption process, but also a redox reaction process.     

Sampling for aphids by traps and by crop inspection

The catches of thirty aphid genera and species during 3 years in a suction trap at 40 ft and on a yellow cylindrical sticky trap at 5 ft at Rothamsted and Broom's Barn are tabulated. Suction-trap catches were the more consistent but both were more effective at recording the first seasonal immigration of Myzuspersicae (Sulz.) and Aphis fabae Scop, than the British Sugar Corporation crop-inspection scheme. The catches show the differential attraction to yellow by different species, the effects of local vegetation, and the seasonal distribution of aphids that are crop pests or potential vectors of viruses.     

Pathways of hydrocarbon dissimilation by aPseudomonas as revealed by chloramphenicol

Pseudomonas aeruginosa cells pre-grown on a particular hydrocarbon will oxidize other hydrocarbons as well. Degradation of these hydrocarbons proceeds to a point — depending on their structure — where new enzymes are needed for further degradation. Lack of these enzymes causes accumulation of products. However, secondary adaptation processes tend to decrease yields of intermediates, in particular when adaptation rates are high.By inhibiting these secondary adaptation processes with chloramphenicol (CAM), the amounts of various intermediates could be increased.Propionic acid was accumulated from heptane by hexane-grown cells in yields up to 60% (molar) calculated on heptane converted. The effect of CAM suggests that propionic acid is not subject to -oxidation (acrylate pathway) but is degraded via methylmalonate by adaptive enzymes.2-Methylhexane was converted for 30–40% (molar) intoiso-valeric acid by heptane-grown cells. A known pathway ofiso-valeric acid oxidation incorporates a carbon dioxide fixation step, and lack of this enzyme in heptane-grown cells probably causesiso-valeric acid accumulation.Heptene-1 incubation with heptane-grown cells resulted in a 30–40% conversion into 4-pentenoic plus 2, 4-pentadienoic acids. 6-Heptenoic acid was detected occasionally. A predominant attack at C₇ of the heptene-1 molecule is indicated at least for heptane-grown cells. Attack on the saturated end of the molecule seems well in line with the assumption that alkane oxidation by these bacteria is effected by oxygen transferring enzymes operating on a methyl group, as opposed to the action of a dehydrogenase and formation of an -olefin as the intermediate.     

Nitrate absorption by corn roots : inhibition by phenylglyoxal

Nitrate transport in excised corn (Zea mays L.) roots was inhibited by phenylglyoxal, but not by 4,4′-diisothiocyano-2,2′-stilbene disulfonic acid (DIDS) or fluorescein isothiocyanate (FITC). Inhibition of nitrate uptake by a 1-hour treatment with 1 millimolar phenylglyoxal was reversed after 3 hours, which was similar to the time needed for induction of nitrate uptake. If induction of nitrate uptake occurs by de novo synthesis of a nitrate carrier, then the resumption of nitrate uptake in the inhibitor-treated roots may occur because of turnover of phenylglyoxal-inactivated nitrate carrier proteins. All three chemicals inhibited chloride uptake to varying degrees, with FITC being the strongest inhibitor. While inhibition due to DIDS was reversible within 30 minutes, both FITC and phenylglyoxal showed continued inhibition of chloride uptake for up to 3 hours after removal from the uptake solution. Assuming that the anion transporter polypeptide(s) carries a positive charge density at or near the transport site, the results indicate that the nitrate carrier does not carry any lysyl residues that are accessible to DIDS or FITC, whereas the chloride carrier does. Both chloride and nitrate carriers, however, seem to possess arginyl residues that are accessible to phenylglyoxal.     

Superoxide Anion Production by Human Neutrophils Activated by Trichomonas vaginalis

Neutrophils are the predominant inflammatory cells found in vaginal discharges of patients infected with Trichomonas vaginalis. In this study, we examined superoxide anion (O₂^.-) production by neutrophils activated by T. vaginalis. Human neutrophils produced superoxide anions when stimulated with either a lysate of T. vaginalis, its membrane component (MC), or excretory-secretory product (ESP). To assess the role of trichomonad protease in production of superoxide anions by neutrophils, T. vaginalis lysate, ESP, and MC were each pretreated with a protease inhibitor cocktail before incubation with neutrophils. Superoxide anion production was significantly decreased by this treatment. Trichomonad growth was inhibited by preincubation with supernatants of neutrophils incubated for 3 hr with T. vaginalis lysate. Furthermore, myeloperoxidase (MPO) production by neutrophils was stimulated by live trichomonads. These results indicate that the production of superoxide anions and MPO by neutrophils stimulated with T. vaginalis may be a part of defense mechanisms of neutrophils in trichomoniasis.     

Reversal by pressure of seed germination promoted by anesthetics

Germination of Panicum capillare L. caryopses induced by solutions of ethanol and ethyl ether was prevented by application of pressure >1 MPa during the period of exposure to the anesthetic. This effect of pressure indicates that germination is correlated with expansion at a site of anesthetic action in a cell membrane. The effects of several other anesthetics were measured on germination of P. capillare seeds. Ethanol, chloroform, and ethyl ether had the highest activity. Methanol and isopropanol were inactive. The effective compounds are thought to distribute preferentially to lipid-solution interfaces in cell membranes of the seeds.     

Log colonization by Ips sexdentatus prevented by increasing host unsuitability signaled by verbenone

Sudden increments of breeding material after windstorms, forest fires, or inappropriate management practices help bark beetles such as Ips sexdentatus Boerner (Coleoptera: Curculionidae: Scolytinae) increase in numbers and colonize standing healthy pine trees. Preventing bark beetles from arriving to susceptible trees or logs may have great relevance for bark beetle management. Recent studies have reported inhibition of the aggregation response of I. sexdentatus using verbenone. Two field experiments were conducted to examine the effect of verbenone on the colonization pattern of this beetle. The first experiment tested the combined effect of trans‐conophthorin, a non‐host bark volatile with known repellent effect, and verbenone on Pinus sylvestris L. (Pinaceae) log piles of two sizes, but failed to protect them against I. sexdentatus attack when these two infochemicals were released at low rates. The results of this experiment suggested an interaction with the associated secondary bark beetle Orthotomicus erosus (Wollaston). A second experiment examined the response of I. sexdentatus and O. erosus to log piles that released verbenone at 0, 2, 10, or 40 mg day^?1. Although I. sexdentatus colonization of Pinus nigra Arnold logs was completely prevented at 40 mg day^?1, O. erosus could be found at all tested verbenone release rates. Besides verbenone, O. erosus colonization density and the height from which logs originated were the variables that best explained I. sexdentatus log colonization pattern. In addition, I. sexdentatus and O. erosus were rarely recorded colonizing the same log, and niche breadth analyses suggested that they excluded each other. The role of verbenone in the colonization process and its potential use in the prevention of population buildups of damaging bark beetles such as I. sexdentatus are discussed.     

Inheritance by recruitment

Doolittle (Biol Philos 28(2):351–378, 2013) and Ereshefsky and Pedroso (Proc Natl Acad Sci 112:10126–10132, 2013) argue that selection can act at the level of biofilms and other microbial communities. Clarke (Biol Philos 191–212, 2016) is skeptical and argues that selection acts on microbial cells rather than microbial communities. Her main criticism is that biofilms lack one of the ingredients required for selection to operate: heritability. This paper replies to her concern by elaborating how biofilm-level traits can be inheritable     

Lipid production by Cryptococcus albidus using biowastes hydrolysed by indigenous microbes

The efficiency of Cryptococcusalbidus was evaluated for its abilities to assimilate onion and apple hydrolysates as a medium for lipid production. Onion waste (OW) and apple waste (AW) were hydrolysed at an organic load of 2% total solids by indigenous microbes under mesophilic conditions. The indigenous microbes effectively hydrolysed both wastes giving the highest reducing sugar content of 4.8 g/L and 10.8 g/L with OW and AW hydrolysates, respectively. The microbiome analysis revealed that most of the indigenous microbes belonged to genus Bacillus and a significant population of α-proteobacteria and γ-proteobacteria were also present. Cell retention culture of C. albidus at a dilution rate of 0.01 h⁻¹ resulted in a total dry cell weight (DCW) of 13.5 g/L with an intracellular lipid content of 20.0% at 168 h, corresponding to an enhancement of 3.48-folds and 2.37-folds in DCW and lipid concentration, respectively, as compared to batch fermentation.

     

Evolution by Squinches

Evolution: The Story of Life on Earth provides a lively, accurate, and delightful explanation of evolution in the form of a graphic novel.     

Hydrogen peroxide production by roots and its stimulation by exogenous NADH

H₂O₂ production by roots of young seedlings was monitored using a non-destructive in vivo assay at pH 5.0. A particularly high rate of H₂O₂ production was measured in the roots of soybean (Glycine max L. cv. Labrador) seedlings which were used for further investigation of the physiological and enzymological properties of apoplastic H₂O₂ production. In the soybean root H₂O₂ production can be stimulated 10-fold by exogenous NADH or NADPH. This response displays typical features of a peroxidase-catalyzed oxidase reaction using NAD(P)H as electron donor for the reduction of O₂ to H₂O₂. Comparative measurements showed that the NADH-induced H₂O₂ production of the roots resembles the H₂O₂-forming activity of horseradish peroxidase with respect to NADH and O₂ concentration requirements and sensitivity to inhibition by KCN, NaN₃, superoxide dismutase and catalase. NADH-induced H₂O₂ production can be observed with similar intensity in all regions of the root, in agreement with the distribution of apoplastic peroxidase activity. In contrast, the activity responsible for the basal H₂O₂ production in the absence of exogenous NADH was mainly confined to a short subapical zone of the root and differs from the NADH-induced reaction by insensitivity to inhibition by superoxide dismutase and a strikingly lower requirement for O₂. It is concluded that the basal H₂O₂ production of the root is mediated by an enzyme different from peroxidase, possibly a plasma membrane O₂^?-producing oxidase.     

Biotransformation of cholesterol by Micrococcus species mediated by plasmid DNA

A steroid-biotransforming strain RJ6 was identified as Micrococcus roseus. This bacterium has a 10kb plasmid pMQV10. Curing mediated through cultivation of the culture with a low concentration (200ng/ml) of mitomycin C is described. Loss of cholesterol degradation (chol⁺) and streptomycin resistance (Sm^r) phenotypes as a consequence of the loss of plasmid indicate the extrachromosomal location of these two genes in this strain. An electroporation procedure was developed for transformation of cured strain of Micrococcus (RJC6) by plasmids. Frequency of greater than 10⁵ transformants/g DNA was achieved, which is 100-fold higher than the standard transformation procedure that yielded 5.3×10³ transformants/g DNA in the same strain.     

Suppression of Mitochondrial Function by Oxidatively Truncated Phospholipids Is Reversible, Aided by Bid, and Suppressed by Bcl-XL

Oxidatively truncated phospholipids are present in atherosclerotic lesions, apoptotic cells, and oxidized low density lipoproteins. Some of these lipids rapidly enter cells to induce apoptosis by the intrinsic pathway, but how such lipids initiate this process is unknown. We show the truncated phospholipid hexadecyl azelaoyl glycerophosphocholine (Az-LPAF), derived from the fragmentation of abundant sn-2 linoleoyl residues, depolarized mitochondria of intact cells. Az-LPAF also depolarized isolated mitochondria and allowed NADH loss, but did not directly interfere with complex I function. Cyclosporin A blockade of the mitochondrial permeability transition pore partially prevented the loss of electrochemical potential. Depolarization of isolated mitochondria by the truncated phospholipid was readily reversed by the addition of albumin that sequestered this lipid. Ectopic expression of the anti-apoptotic protein Bcl-X_L in HL-60 cells reduced apoptosis by the truncated phospholipid by protecting their mitochondria. Mitochondria isolated from these cells were also protected from Az-LPAF-induced depolarization. Conversely mitochondria isolated from Bid^−/− animals that lack this pro-apoptotic Bcl-2 family member were resistant to Az-LPAF depolarization. Addition of recombinant full-length Bid, which has phospholipid transfer activity, restored this sensitivity. Thus, phospholipid oxidation products physically interact with mitochondria to continually depolarize this organelle without permanent harm, and Bcl-2 family members modulate this interaction with full-length Bid acting as a co-factor for pro-apoptotic, oxidatively truncated phospholipids.Vascular cells are exposed to oxidizing radicals during normal metabolism, but especially so during physiologic and pathologic inflammatory processes. The double bonds of polyunsaturated fatty acyl residues are particularly prone to attack by radicals because the C-H bond situated between two double bonds is relatively weak, allowing a more facile abstraction of hydrogen to produce a radical (1). Because polyunsaturated fatty acyl residues are abundant and are generally esterified in the sn-2 position of the glycerol backbone, common products of oxidative attack on cells and circulating lipoproteins are phospholipids that have been peroxidized at their sn-2 position. These peroxy radicals abstract hydrogen to form hydroperoxy phospholipids, may be reduced to the corresponding alcohol, rearrange (2, 3), or fragment to generate a host of oxidatively truncated phospholipids (4–7).The shortened sn-2 residue of truncated phospholipids, which may also contain a newly introduced polar oxygen function, does not intercalate into the membrane well and is energetically favored to protrude into the aqueous phase, a conformation that disorders phospholipid packing into a bilayer (8–10). Oxidatively truncated phospholipids are more water soluble than their phospholipid precursors and readily associate with plasma albumin (11), plasma membranes (12), and even traffic into cells to lysosomes (12) or mitochondria (13) depending on the structure of the truncated phospholipid.Phospholipid oxidation products can be cytotoxic (14, 15), and at least some of these are toxic because they initiate the apoptotic process of regulated cell death (13). The manner by which oxidatively truncated phospholipids alter cell viability has been ascribed to solubilization of the plasma membrane (14), adduction of mitochondrial proteins (17), temporary physical distortion of the plasma membrane (18), or activation of acid sphingomyelinase activity that alters plasma membrane microdomains by generating ceramide (15, 19). We found that a common oxidatively truncated phospholipid, containing a 9-carbon azelaoyl fragment derived from fragmentation of sn-2 linoleoyl residues, induces apoptosis by the intrinsic caspase cascade with loss of mitochondrial function and not, apparently, from damage of the plasma membrane (13).Members of the Bcl-2 family modulate mitochondria-dependent apoptosis either by promoting apoptosis (Bid, Bad, and Bax) or obstructing this event (Bcl-2 and Bcl-X_L). Aggregation of Bax on the mitochondrial outer membrane forms ion conducting pores and Bcl-X_L associates with mitochondrial outer membranes to suppress this Bax activity (20). In contrast, Bid promotes apoptosis after cleavage to truncated Bid, a regulatory event catalyzed by activated caspase 8 (21). Bid, alone among Bcl-2 family members, displays homology to plant lipid transfer proteins and both truncated and full-length Bid will incorporate fluorescent phospholipids, and not the cognate fluorescent fatty acid, into mitochondrial membranes (22).We determined whether mitochondrial integrity or function were directly affected by oxidatively truncated phospholipids, and then whether Bcl-2 family members alter these effects as they do in other, established apoptotic signaling pathways. We find that truncated phospholipids accumulated from the extracellular environment depolarize intracellular mitochondria, that these bilayer challenged phospholipids reversibly interact with mitochondria to continually reduce their transmembrane potential, and that Bcl-2 family members modulate this interaction.     

Ferrihydrite reduction by Geobacter species is stimulated by secondary bacteria

Geobacter species such as G. bremensis, G. pelophilus, and G. sulfurreducens are obligately anaerobic and grow in anoxic, non-reduced medium by fast reduction of soluble ferric citrate. In contrast, insoluble ferrihydrite was either only slowly or not reduced when supplied as electron acceptor in similar growth experiments. Ferrihydrite reduction was stimulated by addition of a reducing agent or by concomitant growth of secondary bacteria that were physiologically and phylogenetically as diverse as Escherichia coli, Lactococcus lactis, or Pseudomonas stutzeri. In control experiments with heat-inactivated Geobacter cells and viable secondary bacteria, no (E. coli, P. stutzeri) or only little (L. lactis) ferrihydrite was reduced. Redox indicator dyes showed that growing E. coli, P. stutzeri, or L. lactis cells lowered the redox potential of the medium in a similar way as a reducing agent did. The lowered redox potential was presumably the key factor that stimulated ferrihydrite reduction by all three Geobacter species. The observed differences in anoxic non-reduced medium with ferric citrate versus ferrihydrite as electron acceptor indicated that reduction of these electron acceptors involved different cellular components or different biochemical strategies. Furthermore, it appears that redox-sensitive components are involved, and/or that gene expression of components needed for ferrihydrite reduction is controlled by the redox state.Dedicated to Prof. Dr. Dr. h.c. mult. Hans Günter Schlegel on the occasion of his 80th birthday.     

Tryptophan uptake by Mycobacterium tuberculosis H37Rv--inhibition by isoniazid.

The effect of various sub-inhibitory concentrations of isoniazid on tryptophan uptake by $\text{Mycobacterium tuberculosis}$ H₃₇Rv grown $\text{in vitro}$ and $\text{in vivo}$ was studied. Uptake, measured after 3 minutes of drug exposure was inhibited mildly by 0.1 μg/ml and 0.2 μg/ml concentration and completely by 0.3 μg/ml. However, with the minimal inhibitory concentration (MIC)⁷ of 0.5 μg/ml, not only inhibition but also a strong efflux of the preformed tryptophan pool were observed. The results are discussed in the light of the theory that isoniazid interferes with the cell wall mycolate synthesis.