Improvement of a Wine Saccharomyces cerevisiae Strain by a Breeding Program

Hybridization by spore conjugation was used to develop new and improved wine yeasts of Saccharomyces cerevisiae. The procedure was achieved with diploid, homothallic strains with high sporulation frequency and high spore viability. The method was verified by crossing flocculent and non-H₂S-forming strains. Single-spore descendants of the hybrids were studied by tetrad analysis with regard to the aforementioned characters and the other two winemaking traits, i.e., ethanol production and fermentation rate. A highly flocculent, non-H₂S-forming wine yeast strain with a high fermentation rate and high ethanol production was obtained.     

Electrical activity of the amygdala and the septum of rats on a high fat or a high protein diet

The authors studied biopotentials in the region of the amygdala and the septum of rats fed on a standard, high protein or high fat diet. During the first 3-6 days after changing from the standard to the high protein or high fat diet, a decrease in the amplitude of electrical activity was found in both the regions in question. After 3 days on the high fat or the high protein diet, an increase was found in the frequency of electrical activity in the amygdala or the septum, according to the type of diet. A study of the amplitude of electrical activity showed that the electrical potential in the septum was always lower than in the amygdala. The frequency spectrum analysis showed a marked change in the superimposed frequency curve only in animals fed on the high fat diet.     

Effect of summer weather on internal loading and chlorophyll a in a shallow lake: a modeling approach

The effect of weather on the eutrophication of a shallow lake was estimated by a hydrodynamic lake model coupled with a simple water quality module. The model was applied to Lake Villikkalanjärvi in southern Finland. This shallow, agriculturally loaded lake may stratify during warm and calm periods in summer and as a result oxygen is often consumed from the hypolimnion, causing high internal loading of phosphorus. Vertical mixing and temperature distribution in the lake were simulated by a one-dimensional, horizontally integrated hydrodynamic model. State variables included in the water quality model were dissolved reactive phosphorus, chlorophyll a and dissolved oxygen. The model was first calibrated against observations from 1989 and 1990. Thereafter, simulations were carried out using weather data from the years 1961 to 1988. The results indicated that warm summer periods may cause high chlorophyll a concentrations due to high internal loading. In four years with exceptionally warm summers the model predicted maximum chlorophyll a concentrations almost twice as high as in years without remarkable internal loading. The model simulates accurately temperature and mixing but the reliability of water quality predictions could be improved by adding more factors regulating algal biomass and sediment phosphorus release.     

Structural adaptation of a thermostable biotin-binding protein in a psychrophilic environment

Shwanavidin is an avidin-like protein from the marine proteobactrium Shewanella denitrificans, which exhibits an innate dimeric structure while maintaining high affinity toward biotin. A unique residue (Phe-43) from the L3,4 loop and a distinctive disulfide bridge were shown to account for the high affinity toward biotin. Phe-43 emulates the function and position of the critical intermonomeric Trp that characterizes the tetrameric avidins but is lacking in shwanavidin. The 18 copies of the apo-monomer revealed distinctive snapshots of L3,4 and Phe-43, providing rare insight into loop flexibility, binding site accessibility, and psychrophilic adaptation. Nevertheless, as in all avidins, shwanavidin also displays high thermostability properties. The unique features of shwanavidin may provide a platform for the design of a long sought after monovalent form of avidin, which would be ideal for novel types of biotechnological application.     

High lysozyme activity in a Norwegian bovine family co-segregates with a restriction fragment length polymorphism

Analysis of restriction fragment length polymorphism (RFLP) of the lysozyme gene cluster was performed in a Norwegian bovine family segregating a single dominant Mendelian factor for high lysozyme activity in serum. An RFLP site with allelic bands of 16kb and 5–9 kb turned out to be linked to the locus for the high lysozyme activity factor with a lod score of 6–8 at a recombination fraction of 3.4%. This implies that we have revealed a genetic marker for the high lysozyme activity trait.     

Modelling a pike (Esox lucius) population in a lowland river using a cellular automaton

Cellular automata (CAs) allow for transparent modelling of complex systems based on simple transition rules and are flexible in incorporating individual differences and local interactions. They may therefore be particularly suited to answer river management questions that could not be addressed by existing habitat suitability models, such as the optimal distance between spawning grounds. This study explores the usability of CAs for spatio-temporal modelling of a pike population to support river management. Specifically, we evaluated the usability of the CA model by analyzing its sensitivity to three model parameters: the number of pike in the grid, the initial pike distribution and the grid resolution. The model includes habitat characteristics and basic expert knowledge on the ecology of pike and was tested on a 10 km stretch of the river Yser in Flanders (Belgium). Simulation results showed that the model converged to a realistic pike distribution over the study area only at high pike density and low grid resolution, irrespective of the initial pike distribution. Pike density and grid resolution affected the sensitivity to the initial pike distribution in the grid. Specifically, the sensitivity was high at low pike density and high grid resolution, and absent when pike density was high. This analysis indicated that initial conditions and cell size may have a severe impact on the model output, illustrating the importance of firstly analyzing this impact before conducting further analyses. Depending on the outcome of such analyses, CAs can be a promising modelling technique to evaluate and predict the effect of river restoration on pike populations.     

Landscape genetics of a recent population extirpation in a burnet moth species

The intensification of agricultural land use over wide parts of Europe has led to the decline of semi-natural habitats, such as extensively used meadows, with those that remain often being small and isolated. These rapid changes in land use during recent decades have strongly affected populations inhabiting these ecosystems. Increasing habitat deterioration and declining permeability of the surrounding landscape matrix disrupt the gene flow within metapopulations. The burnet moth species Zygaena loti has suffered strongly from recent habitat fragmentation, as reflected by its declining abundance. We have studied its population genetic structure and found a high level of genetic diversity in some of the populations analysed, while others display low genetic diversity and a lack of heterozygosity. Zygaena loti was formerly highly abundant in meadows and along the skirts of forests. However, the species is currently restricted to isolated habitat remnants, which is reflected by the high genetic divergence among populations (F _ST: 0.136). Species distribution modelling as well as the spatial examination of panmictic clusters within the study area strongly support a scattered population structure for this species. We suggest that populations with a high level of genetic diversity still represent the former genetic structure of interconnected populations, while populations with low numbers of alleles, high F _IS values, and a lack of heterozygosity display the negative effects of reduced interconnectivity. A continuous exchange of individuals is necessary to maintain high genetic variability. Based on these results, we draw the general conclusion that more common taxa with originally large population networks and high genetic diversity suffer stronger from sudden habitat fragmentation than highly specialised species with lower genetic diversity which have persisted in isolated patches for long periods of time.     

Pulsed-light system as a novel food decontamination technology: a review

In response to consumer preferences for high quality foods that are as close as possible to fresh products, athermal technologies are being developed to obtain products with high levels of organoleptic and nutritional quality but free of any health risks. Pulsed light is a novel technology that rapidly inactivates pathogenic and food spoilage microorganisms. It appears to constitute a good alternative or a complement to conventional thermal or chemical decontamination processes. This food preservation method involves the use of intense, short-duration pulses of broad-spectrum light. The germicidal effect appears to be due to both photochemical and photothermal effects. Several high intensity flashes of broad spectrum light pulsed per second can inactivate microbes rapidly and effectively. However, the efficacy of pulsed light may be limited by its low degree of penetration, as microorganisms are only inactivated on the surface of foods or in transparent media such as water. Examples of applications to foods are presented, including microbial inactivation and effects on food matrices.     

Secondary polycythemia: a boon or a burden?

The development of a secondary erythrocytosis is usually considered a compensatory effort to counteract tissue hypoxia. However, the associated increase in viscosity tends to decrease blood flow and in theory should augment rather than relieve tissue hypoxia. Clinical observations have supported this concern and phlebotomies have been used to treat cardiopulmonary patients with high hematocrits and to prepare acclimatized mountain climbers for strenuous exercises. Direct measurements of tissue tension in rats and mice have shown that a moderate increase in hematocrit does increase the tissue tension of oxygen, probably due to a concomital increase in blood volume, and only severe increases in hematocrit are detrimental. In contrast, it was found that erythropoietin production in mice and man is decreased at even the most extreme hematocrits, suggesting that the tissue tension in the kidneys is not affected by high hematocrits and sluggish blood flow. This lack of renal hypoxia at high blood viscosities appears to serve an important purpose by preventing a vicious circle in which hypoxia will cause erythrocytosis leading to more hypoxia and more erythrocytosis and so on. However, well maintained secondary erythrocytosis cannot always be considered optimal for overall oxygen transport and has to be evaluated clinically for its potential benefit or harm.     

High larval density does not induce a prophylactic immune response in a butterfly

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Adding carbon at a standard and a higher rate reduces soil nitrate in a grassy woodland

C addition has been used successfully in grassland restoration in Australia, generally as sucrose at a standard rate of 840 g C/m²/year. Previous experiments that have varied the rate of soil carbon application to reduce nitrate to favour native over nitrophilous exotic species have found that the benefits can increase over the whole range used for some native species, but only appear above particular rates of C addition for others. A restoration trial of degraded grassy woodland on former agricultural land in western Sydney combined burning and slashing to remove biomass with C addition at the standard rate, and a high rate, to reduce soil nitrate on the burnt or slashed plots. Soil was sampled for extractable nitrate, ammonium and phosphorus, and plant root simulator probes were used to measure nitrate and ammonium supply. Both extractable nitrate and nitrate supply were periodically high in the controls, at which times C addition at the standard rate significantly reduced extractable nitrate with an even greater reduction at the high rate, and resulted in negative relationships between nitrate supply and added C. Effects of added C on extractable nitrate or nitrate supply were not detectable in non‐peak periods. Extractable ammonium and ammonium supply were either unaffected or increased with added C. Colwell phosphorus showed temporal variation but was unresponsive to added C. Of the three nutrients, only the decline in nitrate matched the decline in plant cover which was lowest in value at the high carbon rate (Morris & Gibson‐Roy 2018). In the absence of added C, extractable nitrate was less than control values in the fire and slash treatments 1 year after treatment application but was similar to control values at other times.     

Production of a secreted glycoprotein from an inducible promoter system in a perfusion bioreactor

The primary advantage of an inducible promoter expression system is that production of the recombinant protein can be biochemically controlled, allowing for the separation of unique growth and production phases of the culture. During the growth phase, the culture is rapidly grown to high cell density prior to induction without the extra metabolic burden of exogenous protein production, thus minimizing the nonproductive period of the culture. Induction of the culture at high cell density ensures that the volumetric production will be maximized. In this work, we have demonstrated the feasibility of overexpressing a reporter glycoprotein from the inducible MMTV promoter in recombinant Chinese hamster ovary (CHO) cells cultured in a high cell density perfusion bioreactor system. Retention of suspension-adapted CHO cells was achieved by inclined sedimentation. To maximize volumetric production of the culture, we have demonstrated that high cell density must be achieved prior to induction. This operating scheme resulted in a 10-fold increase in volumetric titer over the low density induction culture, corresponding directly to a 10-fold increase in viable cell density during the highly productive period of the culture. The amount of glycoprotein produced in this high cell density induction culture during 26 days was 84-fold greater than that produced in a week long batch bioreactor. Long-term perfusion cultures of the recombinant cell line showed a production instability, a phenomenon that is currently being investigated.     

Evidence of a High Density Population of Harvested Leopards in a Montane Environment

Populations of large carnivores can persist in mountainous environments following extensive land use change and the conversion of suitable habitat for agriculture and human habitation in lower lying areas of their range. The significance of these populations is poorly understood, however, and little attention has focussed on why certain mountainous areas can hold high densities of large carnivores and what the conservation implications of such populations might be. Here we use the leopard (Panthera pardus) population in the western Soutpansberg Mountains, South Africa, as a model system and show that montane habitats can support high numbers of leopards. Spatially explicit capture-recapture (SECR) analysis recorded the highest density of leopards reported outside of state-protected areas in sub-Saharan Africa. This density represents a temporally high local abundance of leopards and we explore the explanations for this alongside some of the potential conservation implications.     

Size-dependent territory defense by a damselfish

Summary Three adult size classes of the territorial Caribbean dusky damselfish,Stegastes dorsopunicans, are differently distributed with respect to habitat, and with respect to the biomass of filamentous algal turfs in the areas they defend. The density of large individuals is positively correlated with the decalcified dry biomass of these turfs, whereas the densities of medium and small individuals are inversely related to algal biomass. Density of the urchin,Diadema, is also inversely correlated with algal biomass. The high density of large dusky damselfish in sites with algal turfs of relatively high biomass probably results from preferences of dusky damselfish for sites in which algal turfs are thick, and superior abilities of large individuals to defend these sites.Because both rate of attacks and the effectiveness of attacks on territory invaders by dusky damselfish increases with increasing size, sites with relatively high biomass algal turfs are typically better defended than those with lower biomass turfs. Apparently as a result of this, small foraging groups of the blue tang surgeonfish,Acanthurus coeruleus, feed less on high biomass algal turfs than do larger foraging groups, the members of which experience attacks by defending damselfishes less frequently. The relatively low proportionate use of high biomass feeding sites by solitary blue tangs and members of small foraging groups is caused by dusky damselfish. When the density of this damselfish was reduced artificially, use of high biomass algal turfs by solitary blue tangs increased to a level indistinguishable from that of participants in large foraging groups.     

Multiple strategies for a high light existence in a tropical marine macroalga

Acclimation to high light conditions on the top of coral reefs was examined in the coenocytic, filamentous green macroalga Chlorodesmis fastigiata (C. Ag.) Ducker. Despite having a pool of violaxanthin, high light does not induce formation of zeaxanthin in this macroalga. Exposure to 11 and 33% of surface irradiance resulted in parallel, reversible declines in F_v/F_mand in the number of functional PSII centers. The quantum requirement for PSII inactivation was calculated to be approx. 2×10⁷photons. Recovery of PSII activity after low photon exposures did not depend on protein synthesis, unlike at higher photon exposures, where recovery was inhibited by 50% in the presence of lincomycin. Accumulation of inactive, quenching PSII centers is proposed as a mechanism of energy dissipation; only some of these centers require protein synthesis for reactivation. In natural-sized populations, midday photoinhibition was greater in filament tips than in bases, but the number of inactive PSII centers within entire filaments did not significantly change over the course of the day. It is proposed that the higher chlorophyll concentration in the tips provides protective shading to chloroplasts in lower regions, and that cytoplasmic streaming of chloroplasts within this siphonous alga limits the cumulative exposure to high light, thereby providing another level of protection from high light stress.     

Dekkera bruxellensis and Lactobacillus vini form a stable ethanol-producing consortium in a commercial alcohol production process

The ethanol production process of a Swedish alcohol production plant was dominated by Dekkera bruxellensis and Lactobacillus vini, with a high number of lactic acid bacteria. The product quality, process productivity, and stability were high; thus, D. bruxellensis and L. vini can be regarded as commercial ethanol production organisms.     

Covalent stabilization of a small molecule-RNA complex

We demonstrate covalent bond formation between an RNA aptamer containing a cysteamine-tethered nucleobase and helix-threading peptides (HTPs) containing α-bromoacetamide N-termini. The reaction is high yielding and inhibited by a DNA strand Watson-Crick complementary to the aptamer sequence indicating covalent reaction is dependent on the high affinity HTP-binding site present in the folded aptamer. These results are important for future structural studies of HTP-RNA complexes and methods for the discovery of new high affinity analogs via covalent tethering strategies.     

Kinesin-8 Is a Low-Force Motor Protein with a Weakly Bound Slip State

During the cell cycle, kinesin-8s control the length of microtubules by interacting with their plus ends. To reach these ends, the motors have to be able to take many steps without dissociating. However, the underlying mechanism for this high processivity and how stepping is affected by force are unclear. Here, we tracked the motion of yeast (Kip3) and human (Kif18A) kinesin-8s with high precision under varying loads using optical tweezers. Surprisingly, both kinesin-8 motors were much weaker compared with other kinesins. Furthermore, we discovered a force-induced stick-slip motion: the motor frequently slipped, recovered from this state, and then resumed normal stepping motility without detaching from the microtubule. The low forces are consistent with kinesin-8s being regulators of microtubule dynamics rather than cargo transporters. The weakly bound slip state, reminiscent of a molecular safety leash, may be an adaptation for high processivity.     

Characterization of a protease of a feather-degrading Microbacterium species

AIMS: To characterize a new feather-degrading bacterium. METHODS AND RESULTS: The strain kr10 producing a high keratinolytic activity when cultured on native feather broth was identified as Microbacterium sp., based on phenotypical characteristics and 16S rDNA sequence. The bacterium presented optimum growth and feather-degrading activity at pH 7.0 and 30 degrees C. Complete feather degradation was achieved during cultivation. The keratinase was partially purified by gel filtration chromatography. It was optimally active at pH 7.0 and 55 degrees C. The enzyme was inhibited by 1,10-phenanthroline, EDTA, p-chloromercuribenzoic acid, 2-mercaptoethanol and metal ions like Hg(2+), Cu(2+) and Zn(2+). SIGNIFICANCE AND IMPACT OF THE STUDY: A new Microbacterium sp. strain was characterized presenting high feather-degrading activity, which appears to be associated to a metalloprotease-type keratinase. This micro-organism has enormous potential for use in biotechnological processes involving keratin hydrolysis.     

Modification of cellulose fiber surfaces by use of a lipase and a xyloglucan endotransglycosylase

A strategy for the modification of cellulose fiber surfaces was developed that used the ability of Candida antarctica lipase B (CALB) to acylate carbohydrates with high regioselectivity, combined with the transglycosylating activity of the Populus tremula x P. tremuloides xyloglucan endotransglycosylase 16A (PttXET16A). Xyloglucan oligosaccharides (XGOs) prepared from tamarind xyloglucan were acylated with CALB as a catalyst and vinyl stearate or gamma-thiobutyrolactone as acyl donors to produce carbohydrate molecules with hydrophobic alkyl chains or reactive sulfhydryl groups, respectively. The modified XGOs were shown to act as glycosyl acceptors in the transglycosylation reaction catalyzed by PttXET16A and could therefore be incorporated into high M(r) xyloglucan chains. The resulting xyloglucan molecules exhibited a high affinity for cellulose surfaces, which enabled the essentially irreversible introduction of fatty acid esters or thiol groups to cellulose fibers.