Improved Luciferase Tagging System for Listeria monocytogenes Allows Real-Time Monitoring In Vivo and In Vitro

An improved system for luciferase tagging Listeria monocytogenes was developed by constructing a highly active, constitutive promoter. This construct gave 100-fold-higher activity in broth than any native promoter tested and allowed for imaging of lux-tagged L. monocytogenes in food products, during murine infections, and in tumor targeting studies.     

New taxa ofCosmarium Corda (Desmidiaceae) from Karnataka State,India

Six new taxa including two new species (Cosmarium bourrellyi Bongale sp. nov. andC. desikacharyi Bongale sp. nov.) and four new varieties (C. auriculatum var.protrusum Bongale var. nov.,C. pachydermum var.inflatum Bongale var. nov.,C. pseudoconnatum var.tuberculans Bongale var. nov. andC. quadrum var.rotundatum Bongale var. nov.) are reported. Algae were collected from a paddy field at Belgaum.     

Rate of erythropoietin formation in humans in response to acute hypobaric hypoxia

This study was carried out to investigate the early changes in erythropoietin (EPO) formation in humans in response to hypoxia. Six volunteers were exposed to simulated altitudes of 3,000 and 4,000 m in a decompression chamber for 5.5 h. EPO was measured by radioimmunoassay in serum samples withdrawn every 30 min during altitude exposure and also in two subjects after termination of hypoxia (4,000 m). EPO levels during hypoxia were significantly elevated after 114 and 84 min (3,000 and 4,000 m), rising thereafter continuously for the period investigated. Mean values increased from 16.0 to 22.5 mU/ml (3,000 m) and from 16.7 to 28.0 mU/ml (4,000 m). This rise in EPO levels corresponds to 1.8-fold (3,000 m) and 3.0-fold (4,000 m) increases in the calculated production rate of the hormone. After termination of hypoxia, EPO levels continued to rise for approximately 1.5 h and after 3 h declined exponentially with an average half-life time of 5.2 h.     

The removability of pesticides during the production of dialysis water (2)

In many cases it can be demonstrated that the amount of plant protectives and plant treatments (pesticides) in drinking-water exceeds the permitted levels of the drinking-water decree which will be effective on October 1st, 1989. These components are in parts toxicologically important. Therefore, an examination was made on how far pesticides are removed during the conventional purification of dialysis water, but especially during the reverse osmosis. Retention rates of a reverse osmosis plant for 14 different pesticides were discovered which were used in different concentrations and compositions. In part 2 of this contribution the results of the investigation are presented. The figures demonstrate that almost all of the examined components were retained with an effectiveness of 92-98%. The elimination efficiency did not depend on the basic concentration of the pesticides. After an initial phase of 50 h duration, the permeat concentration reached a constant value which did not alter even after more than 700 h.     

Patterns of bushmeat hunting and perceptions of disease risk among central African communities

There is a great need to determine the factors that influence the hunting, butchering and eating of bushmeat to better manage the important social, public health and conservation consequences of these activities. In particular, the hunting and butchering of wild animals can lead to the transmission of diseases that have potentially serious consequences for exposed people and their communities. Comprehension of these risks may lead to decreased levels of these activities. To investigate these issues, 3971 questionnaires were completed to examine the determinants of the hunting, butchering and eating of wild animals and perceptions of disease risk in 17 rural central African villages. A high proportion of individuals reported perceiving a risk of disease infection with bushmeat contact. Individuals who perceived risk were significantly less likely to butcher wild animals than those who perceived no risk. However, perception of risk was not associated with hunting and eating bushmeat (activities that, compared with butchering, involve less contact with raw blood and body fluids). This suggests that some individuals may act on perceived risk to avoid higher risk activity. These findings reinforce the notion that conservation programs in rural villages in central Africa should include health-risk education. This has the potential to reduce the levels of use of wild animals, particularly of certain endangered species (e.g. many non-human primates) that pose a particular risk to human health. However, as the use of wild game is likely to continue, people should be encouraged to undertake hunting and butchering more safely for their own and their community's health.     

Kinetics of ultrasonic degradation and polymerisation degree distribution of sonochemically degraded chitosans

The process of physical degradation by means of the ultrasonic action towards chitosans with mole fraction of 2-acetamido-2-deoxy-β- -glucopyranose units (the degree of N-acetylation, F_A) in the range of 0.10≤F_A≤0.28, and the weight average polymerisation degree in the range of has been investigated. The decrease of as well as changes in the distribution of the degree of polymerisation (P) has been determined as a function of time, F_A, temperature, concentration of chitosan solution and concentration of acetic acid in the solution. The use of low-power ultrasound emitter allowed to establish that in the case of chitosan (binary heteropolysaccharide) the general rate parameter (k) increased with F_A. This can be explained by the relatively stronger aggregation of macromolecules with higher F_A, which results in size increase of macromolecular individuals and hence in their higher susceptibility to ultrasonic action. It was also observed that k decreased with chitosan concentration and temperature. The value of limiting degree of polimerisation (x_e) was found to be influenced by structural parameters of chitosan chains (F_A, aggregation). The increase of acetic acid concentration caused the increase in the k value, what indicated accelerating effect of ultrasound towards acidic hydrolysis of chitosan. The shape of the P curve of sonochemically degraded chitosans are in good correlation with the mid-point breakage concept of degradation accepted in sonochemical degradation of polymers.     

Callus induction and regeneration in<Emphasis Type="Italic"> Spirodela</Emphasis> and<Emphasis Type="Italic"> Lemna</Emphasis>

The development of tissue culture systems in duckweeds has, to date, been limited to species of the genus Lemna. We report here the establishment of an efficient tissue culture cycle (callus induction, callus growth and plant regeneration) for Spirodela oligorrhiza Hegelm SP, Spirodela punctata 8717 and Lemna gibba var. Hurfeish. Significant differences were found among the three duckweed species pertaining to carbohydrate and phytohormone requirements for callus induction, callus growth and frond regeneration. In vitro incubation with poorly assimilated carbohydrates such as galactose (S. oligorrhiza SP and L. gibba var. Hurfeish) and sorbitol (S. punctata 8717) as sole carbon source yielded high levels of callus induction on phytohormone-supplemented medium. Sorbitol is required for optimal callus growth of S. oligorrhiza SP and S. punctata 8717, while sucrose is required for callus growth of L. gibba var. Hurfeish. Sucrose either alone (S. oligorrhiza SP, L. gibba var. Hurfeish) or in addition to sorbitol (S. punctata 8717) is required for frond regeneration.Abbreviations ABA: (±)-Abscisic acid - BA: N⁶-Benzyladenine - 2,4-D 2,4-Dichlorophenoxyacetic acid - Dicamba: 3,6-Dichloro-2-methoxybenzoic acid - 2iP: N⁶-(2-Isopentenyl)adenine - NAA: -Naphthaleneacetic acid - PCA: p-Chlorophenoxy acetic acid - Picloram: 4-Amino-3,5,6-trichloropicolinic acid - TDZ: Thidiazuron Communicated by A. AltmanJ. Li and M. Jain contributed equally to the research reported in this article.     

Biotechnological advantages of laboratory-scale solid-state fermentation with fungi

Despite the increasing number of publications dealing with solid-state (substrate) fermentation (SSF) it is very difficult to draw general conclusion from the data presented. This is due to the lack of proper standardisation that would allow objective comparison with other processes. Research work has so far focused on the general applicability of SSF for the production of enzymes, metabolites and spores, in that many different solid substrates (agricultural waste) have been combined with many different fungi and the productivity of each fermentation reported. On a gram bench-scale SSF appears to be superior to submerged fermentation technology (SmF) in several aspects. However, SSF up-scaling, necessary for use on an industrial scale, raises severe engineering problems due to the build-up of temperature, pH, O₂, substrate and moisture gradients. Hence, most published reviews also focus on progress towards industrial engineering. The role of the physiological and genetic properties of the microorganisms used during growth on solid substrates compared with aqueous solutions has so far been all but neglected, despite the fact that it may be the microbiology that makes SSF advantageous against the SmF biotechnology. This review will focus on research work allowing comparison of the specific biological particulars of enzyme, metabolite and/or spore production in SSF and in SmF. In these respects, SSF appears to possess several biotechnological advantages, though at present on a laboratory scale only, such as higher fermentation productivity, higher end-concentration of products, higher product stability, lower catabolic repression, cultivation of microorganisms specialized for water-insoluble substrates or mixed cultivation of various fungi, and last but not least, lower demand on sterility due to the low water activity used in SSF.     

RIP: the evolutionary cost of genome defense

Repeat-induced point mutation (RIP) is a homology-based process that mutates repetitive DNA and frequently leads to epigenetic silencing of the mutated sequences through DNA methylation. Consistent with the hypothesis that RIP serves to control selfish DNA, an analysis of the Neurospora crassa genome sequence reveals a complete absence of intact mobile elements. As in most eukaryotes, the centromeric regions of N. crassa are rich in sequences that are related to transposable elements; however, in N crassa these sequences have been heavily mutated. The analysis of the N. crassa genome sequence also reveals that RIP has impacted genome evolution significantly through gene duplication, which is considered to be crucial for the evolution of new functions. Most if not all paralogs in N. crassa duplicated and diverged before the emergence of RIP. Thus, RIP illustrates the extraordinary extent to which genomes will go to defend themselves against mobile genetic elements.