Growth Characteristics of an Estuarine Heterocystous Cyanobacterium

A new estuarine filamentous heterocystous cyanobacterium was isolated from intertidal sediment of the Lagoa dos Patos estuary (Brazil). The isolate may represent a new genus related to Cylindrospermopsis. While the latter is planktonic, contains gas vesicles, and is toxic, the newly isolated strain is benthic and does not contain gas vesicles. It is not known whether the new strain is toxic. It grows equally well in freshwater, brackish and full salinity growth media, in the absence of inorganic or organic combined nitrogen, with a growth rate 0.6 d-1. Nitrogenase, the enzyme complex responsible for fixing dinitrogen, was most active during the initial growth phase and its activity was not different between the different salinities tested (freshwater, brackish, and full salinity seawater). Salinity shock also did not affect nitrogenase activity. The frequency of heterocysts was high, coinciding with high nitrogenase activity during the initial growth phase, but decreased subsequently. However, the frequency of heterocysts decreased considerably more at higher salinity, while no change in nitrogenase activity occurred, indicating a higher efficiency of dinitrogen fixation. Akinete frequency was low in the initial growth phase and higher in the late growth phase. Akinete frequency was much lower at high salinity, which might indicate better growth conditions or that akinete differentiation was under the same control as heterocyst differentiation. These trends have hitherto not been reported for heterocystous cyanobacteria but they seem to be well fitted for an estuarine life style

Atuação das multinacionais brasileiras e portuguesas nos mercados da CPLP

info:eu-repo/semantics/publishedVersio

Too Much of Two Good Things: Explicating the Limited Complementarity Between Drivers of MNC Headquarters’ Absorptive Capacity

This study examines how multinational corporation (MNC) knowledge management mechanisms (systems, coordination and socialization) and international exposure affect MNC headquarters' absorptive capacity (AC). We build on Cohen and Levinthal's (Admin Sci Quart 35(1):128–152, 1990, https://doi.org/10.2307/2393553) under-researched trade-off between the inward- and outward-looking drivers of AC in the context of the MNC international knowledge transfer. First, we hypothesize that knowledge management mechanisms (the inward-looking driver) and international exposure (the outward-looking driver) directly influence headquarters' AC. Our findings from a sample of 106 Brazilian and Portuguese MNC headquarters support this view. Second, because "not-invented-here" syndrome and distance can affect knowledge flows from subsidiaries, we develop a hypothesis on the trade-off between AC's inward- and outward-looking drivers. We observe that their impact on the AC of MNC headquarters is diminished for high levels of coordination mechanisms and international exposure. Hence, coordination mechanisms become less effective to absorb subsidiary knowledge as the MNC increases its international footprint. We also conclude that the headquarters of highly internationalized MNCs can regard socialization mechanisms as facilitators of the absorption of knowledge generated by subsidiaries

Telocytes and putative stem cells in the lungs: electron microscopy, electron tomography and laser scanning microscopy

This study describes a novel type of interstitial (stromal) cell — telocytes (TCs) — in the human and mouse respiratory tree (terminal and respiratory bronchioles, as well as alveolar ducts). TCs have recently been described in pleura, epicardium, myocardium, endocardium, intestine, uterus, pancreas, mammary gland, etc. (see www.telocytes.com). TCs are cells with specific prolongations called telopodes (Tp), frequently two to three per cell. Tp are very long prolongations (tens up to hundreds of μm) built of alternating thin segments known as podomers (≤ 200 nm, below the resolving power of light microscope) and dilated segments called podoms, which accommodate mitochondria, rough endoplasmic reticulum and caveolae. Tp ramify dichotomously, making a 3-dimensional network with complex homo- and heterocellular junctions. Confocal microscopy reveals that TCs are c-kit- and CD34-positive. Tp release shed vesicles or exosomes, sending macromolecular signals to neighboring cells and eventually modifying their transcriptional activity. At bronchoalveolar junctions, TCs have been observed in close association with putative stem cells (SCs) in the subepithelial stroma. SCs are recognized by their ultrastructure and Sca-1 positivity. Tp surround SCs, forming complex TC-SC niches (TC-SCNs). Electron tomography allows the identification of bridging nanostructures, which connect Tp with SCs. In conclusion, this study shows the presence of TCs in lungs and identifies a TC-SC tandem in subepithelial niches of the bronchiolar tree. In TC-SCNs, the synergy of TCs and SCs may be based on nanocontacts and shed vesicles

The great screen anomaly—a new frontier in product discovery through functional metagenomics

Functional metagenomics, the study of the collective genome of a microbial community by expressing it in a foreign host, is an emerging field in biotechnology. Over the past years, the possibility of novel product discovery through metagenomics has developed rapidly. Thus, metagenomics has been heralded as a promising mining strategy of resources for the biotechnological and pharmaceutical industry. However, in spite of innovative work in the field of functional genomics in recent years, yields from function-based metagenomics studies still fall short of producing significant amounts of new products that are valuable for biotechnological processes. Thus, a new set of strategies is required with respect to fostering gene expression in comparison to the traditional work. These new strategies should address a major issue, that is, how to successfully express a set of unknown genes of unknown origin in a foreign host in high throughput. This article is an opinionating review of functional metagenomic screening of natural microbial communities, with a focus on the optimization of new product discovery. It first summarizes current major bottlenecks in functional metagenomics and then provides an overview of the general metagenomic assessment strategies, with a focus on the challenges that are met in the screening for, and selection of, target genes in metagenomic libraries. To identify possible screening limitations, strategies to achieve optimal gene expression are reviewed, examining the molecular events all the way from the transcription level through to the secretion of the target gene product

The role of the State in Transnational Exchange: an inter-group contracting. Perspective on Brazilian MNEs' expansion into Mozambique

This paper identifies institutional voids in cross-border exchanges and explores potential responses from the state and transnational firms. Using a longitudinal case study of several Brazilian transnational firms’ expansion into Mozambique from 1998 to 2012, it investigates how the states of Brazil and Mozambique, through the highest official channels, i.e. Presidential meetings, forge cordial inter-state relationship to serve as relational governance for transnational firms, which attenuates the problem of institutional voids at the inter-national level as well as the voids in the host and home country. The case also reveals that those transitional firms have facilitated the governance formation by conducting non-market strategies. The paper contributes to literatures of institutional voids, the role of the state and also international business