scholarly journals Active microbial ecosystem in glacier basal ice fuelled by iron and silicate comminution-derived hydrogen

2021 ◽  
Author(s):  
Mario Toubes-Rodrigo ◽  
Sanja Potgieter-Vermaak ◽  
Robin Sen ◽  
Edda Oddsdottir ◽  
David Elliott ◽  
...  
Keyword(s):  
Soil Formation ◽  
Strong Interactions ◽  
Future Studies ◽  
Basal Ice ◽  
Carbon Release ◽  
Chemolithotrophic Bacteria ◽  
Similarities And Differences ◽  
Methane Metabolism ◽  
16S Rrna Diversity ◽  
Carbon Concentrations

The basal zone of glaciers is characterised by physicochemical properties that are distinct from firnified ice because of strong interactions with underlying substrate. Basal ice ecology and the roles that the microbiota play in biogeochemical cycling, weathering, and proglacial soil formation, remains poorly known. We report bacterial diversity and potential ecological roles at three temperate Icelandic glaciers. We sampled three physically distinct basal ice facies (stratified, dispersed, debris bands) and found biological similarities and differences between them; basal ice character is therefore an important sampling consideration in future studies. High abundance of silicates and Fe-containing minerals could sustain the basal ice ecosystem, in which chemolithotrophic bacteria (~23%), especially Fe-oxidisers and hydrogenotrophs, can fix C, which can be utilised by heterotrophs. Methanogenic-affiliated detected sequences showed that silicate comminution-derived hydrogen can also be utilised for methanogenesis. Metabolism predicted by 16S rRNA diversity revealed that methane metabolism and C-fixation are the most common pathways, indicating the importance of these metabolic routes. Carbon concentrations were low compared to other ecosystems, but we report the highest carbon concentration in basal ice to date. Carbon release from melting basal ice may play an important role in promoting pioneering communities establishment and soil development in deglaciating forelands.

scholarly journals Mycobacterium avium in the Postgenomic Era

2007 ◽  
Vol 20 (2) ◽  
pp. 205-229 ◽  
Author(s):  
Christine Y. Turenne ◽  
Richard Wallace ◽  
Marcel A. Behr
Keyword(s):  
Mycobacterium Avium ◽  
Status Quo ◽  
Future Studies ◽  
The Past ◽  
The Status ◽  
Functional Understanding ◽  
Similarities And Differences ◽  
Survival Mechanisms ◽  
Insight Into

SUMMARY The past several years have witnessed an upsurge of genomic data pertaining to the Mycobacterium avium complex (MAC). Despite clear advances, problems with the detection of MAC persist, spanning the tests that can be used, samples required for their validation, and the use of appropriate nomenclature. Additionally, the amount of genomic variability documented to date greatly outstrips the functional understanding of epidemiologically different subsets of the organism. In this review, we discuss how postgenomic insights into the MAC have helped to clarify the relationships between MAC organisms, highlighting the distinction between environmental and pathogenic subsets of M. avium. We discuss the availability of various genetic targets for accurate classification of organisms and how these results provide a framework for future studies of MAC variability. The results of postgenomic M. avium study provide optimism that a functional understanding of these organisms will soon emerge, with genomically defined subsets that are epidemiologically distinct and possess different survival mechanisms for their various niches. Although the status quo has largely been to study different M. avium subsets in isolation, it is expected that attention to the similarities and differences between M. avium organisms will provide greater insight into their fundamental differences, including their propensity to cause disease.

scholarly journals Kudos to you! Comparing co-authorships and acknowledgements in political science journals from Germany

2019 ◽  
Author(s):  
Stefan Wallaschek ◽  
Raphael Heiberger
Keyword(s):  
Social Network ◽  
Network Analysis ◽  
Political Science ◽  
Exploratory Study ◽  
Institutional Affiliation ◽  
Academic Collaboration ◽  
Future Studies ◽  
Collaborative Behavior ◽  
Similarities And Differences ◽  
Political Science Journals

Scientific research on academic collaboration focuses on co-authorships, citations and acknowledgements as ‘reward triangle’. However, acknowledgements have received comparatively little attention. In this paper, we compare co-authorship and acknowledgement networks and investigate conditions that influence their formation (gender, institutional affiliation and status of authors and acknowledged individuals). We select three sub-disciplinary political science journals from Germany between 2010 and 2017. We employ techniques from social network analysis to compare these conditions by using homophily measures. The results demonstrate that co-authorships have a rather sparse network while including acknowledgements reveals hidden collaboration structures. Moreover, scholars from the same institution are more likely to co-author and acknowledge each other while we show heterophily effects for acknowledging and co-authoring behavior of professors. We also identify an underrepresentation of female academics as authors and credit-givers alike. Thus, our exploratory study reveals similarities and differences patterns for co-authorships and acknowledgements providing new ground for future studies on all aspects of collaborative behavior in science.

scholarly journals ATTITUDE TOWARDS ADVERTISING AMONG YOUNG ADULTS: A COMPARATIVE STUDY BY ETHNICITY

2017 ◽  
Vol 16 (3) ◽  
Author(s):  
Hiram Ting ◽  
Ernest Cyril De Run ◽  
Teck-Weng Jee
Keyword(s):  
Young Adults ◽  
Cultural Differences ◽  
Ethnic Groups ◽  
Theoretical Basis ◽  
Reasoned Action ◽  
Future Studies ◽  
The Subject ◽  
Similarities And Differences ◽  
Belief Model ◽  
Attitude Towards Advertising

The purpose of this study is to determine the attitude of young adults towards advertising from the perspective of ethnicity. Specifically, it seeks to find out how young adults from the Iban, Chinese and Malay communities perceive advertising so as to understand the implication of ethnicity and culture on the subject matter. A seven-factor belief model is adopted to decompose the theory of reasoned action. As such, it provides theoretical basis to explain similarities and differences of beliefs and attitude towards advertising across the three ethnic groups. Given its quantitative stance, a questionnaire-based survey was administered at universities. 316 out of 400 copies were then collected for analyses. The findings show that despite cultural differences embedded in ethnicity, beliefs and attitude of the three ethnic groups towards advertising are found largely to be similar. They can only be set apart by the effect of beliefs on the formation of attitude towards advertising. Implications and future studies are provided.Keywords: Advertising; Attitude; Belief; Culture; Ethnic; Young Adults.

scholarly journals Quantification of basal ice microbial cell delivery to the glacier margin

2016 ◽  
Author(s):  
Mario Toubes-Rodrigo ◽  
Simon J. Cook ◽  
David Elliott ◽  
Robin Sen
Keyword(s):  
Crucial Role ◽  
Primary Succession ◽  
Soil Formation ◽  
Microbial Cell ◽  
Cell Delivery ◽  
Cell Transfer ◽  
Cell Discharge ◽  
Basal Ice ◽  
Viable Cells ◽  
Valley Glacier

Abstract. We present the first assessment of microbial cell discharge from sediment-laden glacier basal ice. At Svínafellsjökull, a temperate valley glacier in Iceland, approximately 1017 cells a−1 are transferred through basal ice to the proglacial environment, and between 101 and 106 cells g−1 basal ice were cultured from our samples under laboratory conditions. We suggest that the delivery of viable cells and dead microbial matter to proglacial ecosystems could be playing a crucial role in soil formation and primary succession during deglaciation, but further quantification of cell transfer from a range of glacier contexts is required.

scholarly journals CARBON IN SOIL IN DIFFERENT PHISIONOMIES OF CAATINGA IN PARAÍBA, BRAZIL

FLORESTA ◽  
2019 ◽  
Vol 49 (2) ◽  
pp. 287
Author(s):  
Bruna Vieira de Souza ◽  
Patrícia Carneiro Souto ◽  
Jacob Silva Souto ◽  
Francisco Das Chagas Vieira Sales ◽  
Carlos Magno Pereira de Souza Junior
Keyword(s):  
Organic Carbon ◽  
Rainy Season ◽  
Carbon Stock ◽  
Dry Season ◽  
Tukey Test ◽  
Caatinga Vegetation ◽  
Carbon Release ◽  
Successional Stages ◽  
The City ◽  
Carbon Concentrations

The devastation of the caatinga vegetation by disorderly exploration has led to the intensification of carbon release, modifying the capacity of soils to stock this element. The study aimed to determine the stock of organic carbon in Caatinga areas. Which it was conducted in the city of Várzea, state of Paraíba in Brazil, in four areas with vegetation in different successional stages. Soil samples were collected to determine the levels of carbon in 04 depths (0-5 cm, 5-10 cm, 10-15 cm and 15-20 cm) in two seasons of the year. The averages of the carbon were compared by Tukey test. The amounts of carbon in the soil showed significant differences in the factors of time, study area and depth. In the dry season, the quantities and the carbon stock were higher than those registered in the rainy season in all the studied areas, being Late Secondary Caatinga and Preserved Caatinga the areas with the highest values. The Late Secondary Caatinga had the highest carbon stock (33.01 Mg ha-1) in the rainy season. On the other hand, in the dry season, the highest carbon stock was in Preserved Caatinga (49.77 Mg ha-1). Larger amounts of organic carbon were found in the area of Preserved Caatinga, being the higher carbon concentrations recorded in the dry season.

200kv superconducting cryo electron microscope

1987 ◽  
Vol 45 ◽  
pp. 642-643
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada ◽  
J. Lehman
Keyword(s):  
Electron Microscope ◽  
Structure Analysis ◽  
Organic Materials ◽  
Strong Interactions ◽  
Specimen Preparation ◽  
Great Effort ◽  
Electron Microscopic ◽  
Crystal Fields ◽  
Special Skill ◽  
Long Time

In recent years, the electron microscope has been significantly improved in resolution and we can obtain routinely atomic-level high resolution images without any special skill. With this improvement, the structure analysis of organic materials has become one of the interesting targets in the biological and polymer crystal fields.Up to now, X-ray structure analysis has been mainly used for such materials. With this method, however, great effort and a long time are required for specimen preparation because of the need for larger crystals. This method can analyze average crystal structure but is insufficient for interpreting it on the atomic or molecular level. The electron microscopic method for organic materials has not only the advantage of specimen preparation but also the capability of providing various information from extremely small specimen regions, using strong interactions between electrons and the substance. On the other hand, however, this strong interaction has a big disadvantage in high radiation damage.

An Early Developmental Marker for Radial Glia in Rat Spinal Cord

1996 ◽  
Vol 54 ◽  
pp. 36-37
Author(s):  
V. Kriho ◽  
H.-Y. Yang ◽  
C.-M. Lue ◽  
N. Lieska ◽  
G. D. Pappas
Keyword(s):  
Spinal Cord ◽  
Intermediate Filament ◽  
Radial Glia ◽  
Rat Spinal Cord ◽  
Future Studies ◽  
Spinal Cord Development ◽  
Median Septum ◽  
Differentiation Marker ◽  
Early Developmental ◽  
Developing Rat

Radial glia have been classically defined as those early glial cells that radially span their thin processes from the ventricular to the pial surfaces in the developing central nervous system. These radial glia constitute a transient cell population, disappearing, for the most part, by the end of the period of neuronal migration. Traditionally, it has been difficult to definitively identify these cells because the principal criteria available were morphologic only.Using immunofluorescence microscopy, we have previously defined a phenotype for radial glia in rat spinal cord based upon the sequential expression of vimentin, glial fibrillary acidic protein and an intermediate filament-associated protein, IFAP-70/280kD. We report here the application of another intermediate filament-associated protein, IFAP-300kD, originally identified in BHK-21 cells, to the immunofluorescence study of radial glia in the developing rat spinal cord.Results showed that IFAP-300kD appeared very early in rat spinal cord development. In fact by embryonic day 13, IFAP-300kD immunoreactivity was already at its peak and was observed in most of the radial glia which span the spinal cord from the ventricular to the subpial surfaces (Fig. 1). Interestingly, from this time, IFAP-300kD immunoreactivity diminished rapidly in a dorsal to ventral manner, so that by embryonic day 16 it was detectable only in the maturing macroglial cells in the marginal zone of the spinal cord and the dorsal median septum (Fig. 2). By birth, the spinal cord was essentially immuno-negative for this IFAP. Thus, IFAP-300kD appears to be another differentiation marker available for future studies of gliogenesis, especially for the early stages of radial glia differentiation.

New form of Transmission Cross Coefficient for High-Resolution Imaging

1990 ◽  
Vol 48 (1) ◽  
pp. 60-61
Author(s):  
Kazuo Ishizuka
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Transmission Function ◽  
Incident Beam ◽  
Optical Microscope ◽  
Strong Interactions ◽  
Small Range ◽  
Specimen Thickness ◽  
Beam Direction ◽  
Diffracted Waves

It is well known that taking into account spacial and temporal coherency of illumination as well as the wave aberration is important to interpret an image of a high-resolution electron microscope (HREM). This occues, because coherency of incident electrons restricts transmission of image information. Due to its large spherical and chromatic aberrations, the electron microscope requires higher coherency than the optical microscope. On an application of HREM for a strong scattering object, we have to estimate the contribution of the interference between the diffracted waves on an image formation. The contribution of each pair of diffracted waves may be properly represented by the transmission cross coefficients (TCC) between these waves. In this report, we will show an improved form of the TCC including second order derivatives, and compare it with the first order TCC.In the electron microscope the specimen is illuminated by quasi monochromatic electrons having a small range of illumination directions. Thus, the image intensity for each energy and each incident direction should be summed to give an intensity to be observed. However, this is a time consuming process, if the ranges of incident energy and/or illumination direction are large. To avoid this difficulty, we can use the TCC by assuming that a transmission function of the specimen does not depend on the incident beam direction. This is not always true, because dynamical scattering is important owing to strong interactions of electrons with the specimen. However, in the case of HREM, both the specimen thickness and the illumination angle should be small. Therefore we may neglect the dependency of the transmission function on the incident beam direction.

Autophagy and ageing: implications for age-related neurodegenerative diseases

2013 ◽  
Vol 55 ◽  
pp. 119-131 ◽  
Author(s):  
Bernadette Carroll ◽  
Graeme Hewitt ◽  
Viktor I. Korolchuk
Keyword(s):  
Neurodegenerative Diseases ◽  
Energy Availability ◽  
Future Studies ◽  
Intracellular Degradation ◽  
Age Related ◽  
Autophagy Induction ◽  
Social Importance ◽  
Cellular Dysfunction ◽  
Autophagy Activity ◽  
Intense Research

Autophagy is a process of lysosome-dependent intracellular degradation that participates in the liberation of resources including amino acids and energy to maintain homoeostasis. Autophagy is particularly important in stress conditions such as nutrient starvation and any perturbation in the ability of the cell to activate or regulate autophagy can lead to cellular dysfunction and disease. An area of intense research interest is the role and indeed the fate of autophagy during cellular and organismal ageing. Age-related disorders are associated with increased cellular stress and assault including DNA damage, reduced energy availability, protein aggregation and accumulation of damaged organelles. A reduction in autophagy activity has been observed in a number of ageing models and its up-regulation via pharmacological and genetic methods can alleviate age-related pathologies. In particular, autophagy induction can enhance clearance of toxic intracellular waste associated with neurodegenerative diseases and has been comprehensively demonstrated to improve lifespan in yeast, worms, flies, rodents and primates. The situation, however, has been complicated by the identification that autophagy up-regulation can also occur during ageing. Indeed, in certain situations, reduced autophagosome induction may actually provide benefits to ageing cells. Future studies will undoubtedly improve our understanding of exactly how the multiple signals that are integrated to control appropriate autophagy activity change during ageing, what affect this has on autophagy and to what extent autophagy contributes to age-associated pathologies. Identification of mechanisms that influence a healthy lifespan is of economic, medical and social importance in our ‘ageing’ world.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

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