The mobilization of plasmids from gram-negative Escherichia coli to gram-positive Brevibacterium lactofermentum, mediated by P-type transfer functions, was used to construct disrupted mutants blocked specifically in the homoserine branch of the aspartate pathway. The mutant strain B. lactofermentum R31 showed an efficiency of conjugal transfer two to three orders of magnitude higher than that of the wild-type strain B. lactofermentum ATCC 13869. The hom- and thrB-disrupted mutants of B. lactofermentum ATCC 13869 were lysine overproducers. B. lactofermentum R31 mutants do not overproduce lysine because R31 is an alanine-overproducing strain and channels the pyruvate needed for lysine biosynthesis to the production of alanine.

The minimal region for autonomous replication of pBL1, a 4.5-kb cryptic plasmid of Brevibacterium lactofermentum ATCC 13869 that has been used to construct a variety of corynebacterium vectors, was shown to be contained on a 1.8-kb HindII-SphI DNA fragment. This region contains two open reading frames (ORFs) (ORF1 and ORF5) which are essential for pBL1 replication in B. lactofermentum. Accumulation of single-strand intermediates in some of the constructions indicates that plasmid pBL1 replicates via the rolling circle replication model; its plus strand and minus strand were identified by hybridization with two synthetic oligonucleotide probes complementary to each pBL1 strand. ORF1 seems to encode the Rep protein and showed partial homology with sequences for Rep proteins from Streptomyces plasmids which replicate via rolling circle replication such as pUJ101, pSB24, and pJVl.pBL1 is a multicopy plasmid isolated from Brevibacterium lactofermentum ATCC 13869 (19) and later described as pAM330 (14) Streptomyces lividans. pUL61 was unstable in B. lactofermentum, and two stable deletion derivatives (pUL330 and pUL340) appeared after B. lactofermentum had been transformed with pUL61. A similar instability has also been observed in most other small plasmids from gram-positive bacteria. The main characteristic of plasmids showing instability is their mode of replication via the rolling circle replication (RCR) mechanism. RCR plasmids were classified into four families according to homologies of their replication proteins (Rep) and the position of the double-stranded origin (DSO) (7). RCR plasmids have the information to synthesize their own Rep protein. The Rep protein initiates replication by nicking the DNA at the DSO sequence, after which replication of the plus strand begins. The newly generated single-stranded DNA (ssDNA) intermediates (plus strand) serve as a template for minus strand synthesis. The conversion of the ssDNA intermediates to duplex forms requires the recognition of another sequence, different and separated from the DSO sequence, called single-stranded origin (SSO). The absence or nonfunctionality of SSO results in the accumulation of ssDNA. The SSO sequence is rather specific, and it is usually recognized inefficiently in hosts different from the parental one (7, 15).We describe in this paper the identification and characterization of the region involved in replication functions of pBL1. Our results indicate that pBL1 belongs to the group of plasmids which replicate via the RCR mechanism. MATERIALS AND METHODSPlasmids, bacterial strains, and transformation conditions. Plasmids used in this study are listed in Table 1. B. lactofermentum BL31 (20), a pBL1-cured strain, and C. glutamicum ATCC 13032 were grown in Trypticase soy broth (TSB) medium and transformed by electroporation as described by Dunican and Shivnan (5). E. coli DH5ao was grown in L broth and transformed by the method of Hanahan (8).

Corporate social responsibility (CSR) is a voluntary competitive strategy that is based upon social, economic, and environmental improvement in which the organisation is involved. Internationalisation, a type of corporate strategy, is a set of processes that help companies to expand globally to achieve the aim of improving their competitive position. Both of the strategies have become more important due to ever increasing globalisation, whose consequences modify economic and business environments, thus causing them to be more dynamic and competitive. This directly affects business management, thus companies increasingly consider the opinion of society, attempting to gain stakeholders’ trust through effective CSR management. In this context, this paper aims to analyse CSR and internationalisation strategies and their possible connection from a theoretical viewpoint. From a practical viewpoint, the relationship between both strategies is analysed while using a sample of Spanish listed companies.

Temperature and nutrient supply interactively control phytoplankton growth and productivity, yet the role of these drivers together still has not been determined experimentally over large spatial scales in the oligotrophic ocean. We conducted four microcosm experiments in the tropical and subtropical Atlantic (29°N-27°S) in which surface plankton assemblages were exposed to all combinations of three temperatures (in situ, 3 °C warming and 3 °C cooling) and two nutrient treatments (unamended and enrichment with nitrogen and phosphorus). We found that chlorophyll a concentration and the biomass of picophytoplankton consistently increase in response to nutrient addition, whereas changes in temperature have a smaller and more variable effect. Nutrient enrichment leads to increased picoeukaryote abundance, depressed Prochlorococcus abundance, and increased contribution of small nanophytoplankton to total biomass. Warming and nutrient addition synergistically stimulate light-harvesting capacity, and accordingly the largest biomass response is observed in the warmed, nutrient-enriched treatment at the warmest and least oligotrophic location (12.7°N). While moderate nutrient increases have a much larger impact than varying temperature upon the growth and community structure of tropical phytoplankton, ocean warming may increase their ability to exploit events of enhanced nutrient availability.

Temperature and nutrient supply are key factors that control phytoplankton ecophysiology, but their role is commonly investigated in isolation. Their combined effect on resource allocation, photosynthetic strategy, and metabolism remains poorly understood. To characterize the photosynthetic strategy and resource allocation under different conditions, we analyzed the responses of a marine cyanobacterium (Synechococcus PCC 7002) to multiple combinations of temperature and nutrient supply. We measured the abundance of proteins involved in the dark (RuBisCO, rbcL) and light (Photosystem II, psbA) photosynthetic reactions, the content of chlorophyll a, carbon and nitrogen, and the rates of photosynthesis, respiration, and growth. We found that rbcL and psbA abundance increased with nutrient supply, whereas a temperature‐induced increase in psbA occurred only in nutrient‐replete treatments. Low temperature and abundant nutrients caused increased RuBisCO abundance, a pattern we observed also in natural phytoplankton assemblages across a wide latitudinal range. Photosynthesis and respiration increased with temperature only under nutrient‐sufficient conditions. These results suggest that nutrient supply exerts a stronger effect than temperature upon both photosynthetic protein abundance and metabolic rates in Synechococcus sp. and that the temperature effect on photosynthetic physiology and metabolism is nutrient dependent. The preferential resource allocation into the light instead of the dark reactions of photosynthesis as temperature rises is likely related to the different temperature dependence of dark‐reaction enzymatic rates versus photochemistry. These findings contribute to our understanding of the strategies for photosynthetic energy allocation in phytoplankton inhabiting contrasting environments.

Contrary to predictions by the allometric theory, there is evidence that phytoplankton growth rates peak at intermediate cell sizes. However, it is still unknown if this pattern may result from the effect of experimental temperature. Here we test whether temperature affects the unimodal size scaling pattern of phytoplankton growth by (1) growing Synechococcus sp., Ostreococcus tauri, Micromonas commoda and Pavlova lutheri at 18 °C and 25 °C, and (2) using thermal response curves available in the literature to estimate the growth rate at 25 °C as well as the maximum growth rate at optimal temperature for 22 species assayed previously at 18 °C. We also assess the sensitivity of growth rate estimates to the metric employed for measuring standing stocks, by calculating growth rates based on in vivo fluorescence, chlorophyll a concentration, cell abundance and biomass (particulate organic carbon and nitrogen content). Our results show that the unimodal size scaling pattern of phytoplankton growth, with a peak at intermediate cell sizes, is observed at 18 °C, 25 °C and at the optimal temperature for growth, and that it prevails irrespective of the standing-stock metric used. The unimodal size scaling pattern of phytoplankton growth is supported by two independent field observations reported in the literature: (i) a positive relationship between cell size and metabolic rate in the picophytoplankton size range and (ii) the dominance of intermediate-size cells in nutrient-rich waters during blooms.

Sea surface warming has the potential to alter the diversity, trophic organization and productivity of marine communities. However, it is unknown if temperature fluctuations that ecosystems naturally experience can alter the predicted impacts of warming. We address this uncertainty by exposing a natural marine plankton community to warming conditions (+3°C) under a constant vs. fluctuating (±3°C) temperature regime using an experimental mesocosm approach. We evaluated changes in stoichiometry, biomass, nutrient uptake, taxonomic composition, species richness and diversity, photosynthetic performance, and community metabolic balance. Overall, warming had a stronger impact than fluctuating temperature on all biological organization levels considered. As the ecological succession progressed toward post-bloom, the effects of warming on phytoplankton biomass, species richness, and net community productivity intensified, likely due to a stimulated microzooplankton grazing, and the community metabolic balance shifted toward a CO2 source. However, fluctuating temperatures reduced the negative effects of warming on photosynthetic performance and net community productivity by 40%. Our results demonstrate that temperature fluctuations may temper the negative effect of warming on marine net productivity. These findings highlight the need to consider short-term thermal fluctuations in experimental and modeling approaches because the use of constant warming conditions could lead to an overestimation of the real magnitude of climate change impacts on marine ecosystems.

Purpose: The present study is aimed at presenting a critical appraisal of the empirical literature on the Balassa-Samuelson hypothesis for emerging and developing Asian countries. Design/methodology/approach: A critical appraisal of the relevant studies is carried out across various important dimensions of the empirical estimation of the Balassa-Samuelson hypothesis including the scheme of sectoral division followed, definitions and proxy variables used for constructing real exchange rate and price series, choice of output and employment series and their subsequent transformation, empirical methodology followed and (theoretically) different variants of the hypothesis chosen for empirical estimation. Findings: Only a handful of studies have investigated the Balassa-Samuelson hypothesis for Asia. Nevertheless, these studies are characterized by a variety of irregularities in dealing with different important features of the theory, which may be of critical importance for yielding consistent empirical estimates. In multi-country studies for Asia, serious inconsistencies are observed whilst handling these critical aspects of the hypothesis. Such irregularities may hold serious implications for model estimates since the empirical evidence from Asia is very mixed, and in many cases, not even robust. Practical implications: The inconsistencies highlighted in this review paper hold strong implications for future research in this area. The selection of price indicators for the construction of real exchange rate series, choice of econometric methodology and the theoretical framework followed are aspects of the empirical verification of the Balassa-Samuelson hypothesis that need to be handled with great caution since they turn out to be most sensitive in relation to yielding intuitively correct and robust model estimates. Originality: To our knowledge, so far, no study on Asia has presented such an extensive appraisal of literature on the productivity-real exchange rate nexus. The present study is therefore novel in the sense that it critically evaluates studies on Asia against all those features of the Balssa-Samuelson theory which may stand responsible for yielding mixed and even contrasting empirical estimates for Asia.