Plant communities, synusiae and the arithmetic of a sustainable classification

We propose an equation to evaluate the efficiency of a classification as a function of the effort required and the population size of data collectors. The formula postulates a “classification efficiency coefficient”, which relates not only to the complexity of the object to be classified, but also to the data availability and representativeness. When applied to the classification of phytocoenoses, the equation suggests that a classification system based on vascular plants offers the best compromise between sampling effort, resolution power and data availability. We discuss the possibility of basing a vegetation classification on plot records for all macroscopic photoautotrophic organisms co-occurring in the vertical projection of a given ground area, as recently suggested by some authors. We argue that the inclusion of cryptogams in the description of phytocoenoses dominated by vascular plants should rely on a synusial approach, conceived as complementary to the traditional Braun-Blanquet approach

Components of the E. coli envelope are affected by and can react to protein over-production in the cytoplasm.

BACKGROUND: Protein over-expression in bacteria is still the easiest, cheapest and therefore preferred way to obtain large amounts of proteins for industrial and laboratory scale preparations. Several studies emphasized the importance of understanding cellular and molecular mechanisms triggered by protein over-production in order to obtain higher yield and better quality of the recombinant product. Almost every step leading to a fully functional polypeptide has been investigated, from mRNA stability to the role of molecular chaperones, from aggregation to bottlenecks in the secretory pathway. In this context, we focused on the still poorly addressed relationship between protein production in the cytoplasm and the bacterial envelope, an active and reactive cell compartment that controls interactions with the environment and several major cellular processes. Results available to date show that the accumulation of foreign proteins in the cytoplasm induces changes in the membrane lipids and in the levels of mRNAs for some membrane proteins. However, a direct connection between membrane protein expression levels and soluble/aggregated protein accumulation in the cytoplasm has never been reported. RESULTS: By the use of a combined physiological and proteomic approach, we investigated the effects on the cell membrane of E. coli of the overexpression of two recombinant proteins, the B. cepacia lipase (BCL) and the green fluorescent protein (GFP). Both polypeptides are expressed in the cytoplasm at similar levels but GFP is fully soluble whereas inactive BCL accumulates in inclusion bodies.Growth and viability of the transformed cells were tested in the presence of different drugs. We found that chloramphenycol preferentially inhibited the strain over-producing GFP while SDS was more effective when BCL inclusion bodies accumulated in the cytoplasm. In contrast, both proteins induced a similar response in the membrane proteome, i.e. increased levels of LamB, OmpF, OmpA and TolC. Under all tested conditions, the lipopolysaccharide was not affected, suggesting that a specific rather than a generalized rearrangement of the envelope was induced. CONCLUSION: Taking together physiological and biochemical evidence, our work indicates that the E. coli envelope can sense protein over-expression in the cytoplasm and react by modulating the abundance of some membrane proteins, with possible consequences on the membrane traffic of small solutes, i.e. nutrients, drugs and metabolites. Such a response seems to be independent on the nature of the protein being over-expressed. On the other hand both our data reported herein and previous results indicate that membrane lipids may act as a second stress sensor responsive to the aggregation state of the recombinant protein and further contribute to changes in cellular exchanges with the environment.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Components of the E. coli envelope are affected by and can react to protein over-production in the cytoplasm

<p>Abstract</p> <p>Background</p> <p>Protein over-expression in bacteria is still the easiest, cheapest and therefore preferred way to obtain large amounts of proteins for industrial and laboratory scale preparations. Several studies emphasized the importance of understanding cellular and molecular mechanisms triggered by protein over-production in order to obtain higher yield and better quality of the recombinant product. Almost every step leading to a fully functional polypeptide has been investigated, from mRNA stability to the role of molecular chaperones, from aggregation to bottlenecks in the secretory pathway. In this context, we focused on the still poorly addressed relationship between protein production in the cytoplasm and the bacterial envelope, an active and reactive cell compartment that controls interactions with the environment and several major cellular processes. Results available to date show that the accumulation of foreign proteins in the cytoplasm induces changes in the membrane lipids and in the levels of mRNAs for some membrane proteins. However, a direct connection between membrane protein expression levels and soluble/aggregated protein accumulation in the cytoplasm has never been reported.</p> <p>Results</p> <p>By the use of a combined physiological and proteomic approach, we investigated the effects on the cell membrane of <it>E. coli </it>of the overexpression of two recombinant proteins, the <it>B. cepacia </it>lipase (BCL) and the green fluorescent protein (GFP). Both polypeptides are expressed in the cytoplasm at similar levels but GFP is fully soluble whereas inactive BCL accumulates in inclusion bodies.</p> <p>Growth and viability of the transformed cells were tested in the presence of different drugs. We found that chloramphenycol preferentially inhibited the strain over-producing GFP while SDS was more effective when BCL inclusion bodies accumulated in the cytoplasm. In contrast, both proteins induced a similar response in the membrane proteome, i.e. increased levels of LamB, OmpF, OmpA and TolC. Under all tested conditions, the lipopolysaccharide was not affected, suggesting that a specific rather than a generalized rearrangement of the envelope was induced.</p> <p>Conclusion</p> <p>Taking together physiological and biochemical evidence, our work indicates that the <it>E. coli </it>envelope can sense protein over-expression in the cytoplasm and react by modulating the abundance of some membrane proteins, with possible consequences on the membrane traffic of small solutes, i.e. nutrients, drugs and metabolites. Such a response seems to be independent on the nature of the protein being over-expressed. On the other hand both our data reported herein and previous results indicate that membrane lipids may act as a second stress sensor responsive to the aggregation state of the recombinant protein and further contribute to changes in cellular exchanges with the environment.</p

Interspecific somatic hybrids between Solanum bulbocastanum and S. tuberosum and their haploidization for potato breeding.

Protoplast fusion between incongruent Solanum bulbocastanum and S. tuberosum haploids was accomplished to produce hybrids combining elite traits from both parents. We identified 11 somatic hybrids out of 42 regenerants analyzed through ISSR markers. Some hybrids had loss or gain of fragments compared to the parents, likely due to rearrangements and deletions of chromosome segments after fusion, and/or to somaclonal variation during hybrid regeneration. Increased heterotic vigor for some traits as well as high diversity was observed as the effect of both ploidy and fusion combination. Microsporogenesis analysis indicated the occurrence of multivalent configurations and several meiotic abnormalities, such as chromosomes bridges and various spindle orientations. Since all hybrids were sterile, in vitro anther culture was employed for haploidization as a possible strategy to overcome barriers to hybridizations. Haploids were obtained from all the tetraploid S. bulbocastanum (+) S. tuberosum somatic hybrids tested, although with differences in both the number of embryos per 100 anthers cultured and the number of differentiated green plantlets. This is the first report on the successful production of haploid plants from S. bulbocastanum (+) S. tuberosum hybrids

A real-time 3D reconstruction of staircases for rehabilitative exoskeletons

In medical contexts, the use of assistive exoskeletons for the rehabilitation of people with impaired mobility represents a common practice. Recent advances suggest that, soon, such mechatronic systems will also be used to assist people in their everyday life. In order to reach such target, exoskeletons must become able to perceive the environment. To this purpose, a system for the parametric identification of a staircase is proposed in this paper. More precisely, given a staircase of unknown geometry, the system identifies its 3D shape. Furthermore, it also estimates the reciprocal orientation and distance between the exoskeleton and the staircase. Differently from other approaches, this result is achieved by means of low cost devices: an inertial measurement unit, two ranging sensors, and an Arm-Cortex processor. Starting from the ranging sensors acquisitions, the staircase model is identified in real time, during the execution of a step. The proposed procedure is based on an extended recursive total least squares strategy, in order to fully exploit the computational capabilities of the Arm processor, and it is characterized by execution times smaller than 10 −3 s. The estimation algorithm has been tested on an actual exoskeleton and the resulting experimental outcomes are compared with the results obtained through alternative methods

Eutrophication-like response to climate warming: an analysis of Lago Maggiore (N. Italy) zooplankton in contrasting years

Global mean surface temperatures are increasing. All ecosystems are likely to be affected and there is much interest at present in predicting the effects. In freshwater environments, we expect to observe, among other things, effects similar to those observed under eutrophication, such as increases in zooplankton population density and biomass as a result of enhanced population growth rates. Lago Maggiore underwent rapid eutrophication during the 60s and 70s, with a return to oligotrophy during the 80s and the 90s. Thus, it provides a case study to test the hypothesized eutrophication-like effects of recent climate warming. More specifically, we compare zooplankton biomass and density during the exceptionally warm years of the recent oligotrophic phase with values during the non-warm years of oligotrophy, and during years of the mesotrophic phase. This permits an analysis of zooplankton biomass and density with respect to temperature increase compared with the effects of eutrophication. Zooplankton population density and biomass sharply increased in 2003, the warmest year of the last century, as a result of Cladocera, particularly Daphnia, attaining values typical of the mesotrophic phase. These values were exceptional compared to typical values and were strongly different from those attained during cooler years since re-oligotrophication. Mean annual values of zooplankton density and biomass recorded in 2003 were fully comparable to typical values during the mesotrophic period. This observation confirms the hypothesis of an overall eutrophication-like effect of climate warming. Seasonal trends, characterized by an earlier start of population growth, are consistent with the effects of an increase in water temperature, as observed in laboratory experiments on the reproductive and growth strategies of Daphni

Entrepreneurial education and internationalisation of firms in transition economies: a conceptual framework from the case of Croatia

The aim of this paper is to offer an integrated perspective on internationalisation process in transition economies and the role that an entrepreneurial education can play in it. The context of a transition economy, such those countries belonging to the former Yugoslavian republic, deeply affect the entrepreneurial activities established. Internationalisation offers a viable advantage to entrepreneurs and their firms to overcome a limited internal market and hostile conditions faced in the local environment. Thanks to the results obtained by a stream of studies focused on the entrepreneurial context in Croatia, we build a framework to explore the problems faced by entrepreneurs when internationalisation is considered and possible solutions. Our main contribution is the proposition of an entrepreneurial education as facilitator of the process. Indeed, entrepreneurial education, considered as formal education and an entrepreneurial university context, can directly ameliorate the process of internationalisation. Simultaneously it can also affect the networking strategy that in literature is another prominent element tackled regarding the problem of internationalisation in transition economies. Thus, entrepreneurial education may represent a strong boost in which to invest with public policies and targeted interventions

DNA-based technologies for grapevine biodiversity exploitation: state of the art and future perspectives

The cultivated grapevine, Vitis vinifera subsp. vinifera L., is represented by an enormous population of varieties and clones. They arise from the accumulation of gametic and somatic mutations during centuries of sexual and asexual propagation. These varieties represent a vast reservoir of traits/alleles that could be useful in improving the berry quality as well as against environmental stresses. However, most of them are still unexploited. For this reason, an efficient characterization system is essential to define the varietal identity, avoid cases of synonymy (identical genotypes but different names) and homonymy (same names but different genotypes) and deepen our understanding of the existing diversity within the grape germplasm. The plethora of DNA-based high-throughput technologies currently available provides promising tools for the analysis of diversity, overcoming many of the limitations of phenotypic-based diversity analyses. However, the analysis of intra-varietal diversity remains challenging. In this scenario, after summarizing the causes and consequences of grapevine genetic inter- and intra-varietal diversity, we review the DNA-based technologies used for varietal genotyping, emphasizing those able to distinguish clones within a variety. This review provides an update on the technologies used to explore grapevine diversity, the knowledge of which is necessary for an efficient exploitation and conservation of the grapevine germplasm

Offline Calibration Procedure of the Drift Tube Detectors

A detailed description of the calibration of the DT local reconstruction algorithm is reported. After inter-channel synchronization has been verified through the appropriate hardware procedure, the time pedestal can be extracted directly from the distribution of the digi-times. Further corrections for time-of-flight and time of signal propagation are applied as soon as the three-dimensional hit position within the chamber is known. The different effects of the time pedestal miscalibration on the two main hit reconstruction algorithms are shown. The drift velocity calibration algorithm is based on the meantimer technique and different meantimer relations for different track angles and patterns of hit cells are used. This algorithm can also be used to determine the uncertainty of the reconstructed hit position