Search results for " microbiology."

Anhydrobiosis: Inside yeast cells

2018

International audience; Under natural conditions yeast cells as well as other microorganisms are regularly subjected to the influence of severe drought, which leads to their serious dehydration. The dry seasons are then changed by rains and there is a restoration of normal water potential inside the cells. To survive such seasonal changes a lot of vegetative microbial cells, which belong to various genera and species, may be able to enter into a state of anhydrobiosis, in which their metabolism is temporarily and reversibly suspended or delayed. This evolutionarily developed adaptation to extreme conditions of the environment is widely used for practical goals - for conservation of microorg…

How to escape from insect egg parasitoids : a review of potential factors explaining parasitoid absence across the Insecta

2020

The egg is the first life stage directly exposed to the environment in oviparous animals, including many vertebrates and most arthropods. Eggs are vulnerable and prone to mortality risks. In arthropods, one of the most common egg mortality factors is attack from parasitoids. Yet, parasitoids that attack the egg stage are absent in more than half of all insect (sub)orders. In this review, we explore possible causes explaining why eggs of some insect taxa are not parasitized. Many insect (sub)orders that are not attacked by egg parasitoids lack herbivorous species, with some notable exceptions. Factors we consider to have led to escape from egg parasitism are parental egg care, rapid egg deve…

The Strategic Reference Gene: an organismal theory of inclusive fitness

2019

How to define and use the concept of inclusive fitness is a contentious topic in evolutionary theory. Inclusive fitness can be used to calculate selection on a focal gene, but it is also applied to whole organisms. Individuals are then predicted to appear designed as if to maximise their inclusive fitness, provided that certain conditions are met (formally when interactions between individuals are 'additive'). Here we argue that applying the concept of inclusive fitness to organisms is justified under far broader conditions than previously shown, but only if it is appropriately defined. Specifically, we propose that organisms should maximise the sum of their offspring (including any accrued…

Occurrence of antibiotics and antiretroviral drugs in source-separated urine, groundwater, surface water and wastewater in the peri-urban area of Chu…

2020

Recently, there has been an increased interest in bridging the knowledge gap in the occurrence and fate of pharmaceuticals in African urban water  cycles. In this study, the occurrence of 7 antibiotics and 3 antiretrovirals in source-separated urine, groundwater, wastewater and surface water of the peri-urban area of Chunga in Lusaka, Zambia, was studied. In groundwater, the pharmaceuticals were only sporadically present with 4 antibiotics and 1 antiretroviral detected. The concentration of the antibiotics ranged from below limit of quantification (<LOQ) to 880 ng/L, with sulfamethoxazole having the highest detection frequency of 42.3%. In the surface water, a comparatively high concentrati…

Beyond cells – The virome in the human holobiont

2019

Viromics, or viral metagenomics, is a relatively new and burgeoning field of research that studies the complete collection of viruses forming part of the microbiota in any given niche. It has strong foundations rooted in over a century of discoveries in the field of virology and recent advances in molecular biology and sequencing technologies. Historically, most studies have deconstructed the concept of viruses into a simplified perception of viral agents as mere pathogens, which demerits the scope of large-scale viromic analyses. Viruses are, in fact, much more than regular parasites. They are by far the most dynamic and abundant entity and the greatest killers on the planet, as well as th…

2020

ABSTRACT The vertical structuring of methanotrophic communities and its genetic controllers remain understudied in the water columns of oxygen-stratified lakes. Therefore, we used 16S rRNA gene sequencing to study the vertical stratification patterns of methanotrophs in two boreal lakes, Lake Kuivajärvi and Lake Lovojärvi. Furthermore, metagenomic analyses were performed to assess the genomic characteristics of methanotrophs in Lovojärvi and the previously studied Lake Alinen Mustajärvi. The methanotroph communities were vertically structured along the oxygen gradient. Alphaproteobacterial methanotrophs preferred oxic water layers, while Methylococcales methanotrophs, consisting of putative…

'Palaeoshellomics' reveals the use of freshwater mother-of-pearl in prehistory

2019

The extensive use of mollusc shell as a versatile raw material is testament to its importance in prehistoric times. The consistent choice of certain species for different purposes, including the making of ornaments, is a direct representation of how humans viewed and exploited their environment. The necessary taxonomic information, however, is often impossible to obtain from objects that are small, heavily worked or degraded. Here we propose a novel biogeochemical approach to track the biological origin of prehistoric mollusc shell. We conducted an in-depth study of archaeological ornaments using microstructural, geochemical and biomolecular analyses, including ‘palaeoshellomics’, the first…

The Comparison of Cellulolytic Activity of the Modified Soil Treated with Roundup

2016

Abstract The activity of soil microorganisms affects soil fertility and structure, what leads to satisfactory crop yields, thanks to changes in the decay of organic matter. Their activity may be impaired as a result of application by farmers both fertilizers and pesticides. The degradation of cellulosic biomass represents an important part of the carbon cycle within the biosphere. Cellulolitic microorganisms are responsible for this decomposition, as they produced the enzymes of the cellulase complex. The aim of the study was to compare the cellulolytic activity of soil with Roundup and modified using urea phosphate and / or manure. The pot experiment was conducted under laboratory conditio…

Pathogenic Escherichia coli Among Asymptomatic Children and Associated Factors

2020

Abstract Although Escherichia coli is a part of the commensal flora of the gastrointestinal tract, pathogenic types of E. coli can cause diarrhea, especially in children. Pathogenic types are found also in healthy individuals, but prevalence of pathogenic E. coli among asymptomatic children varies and has not been studied in Latvia. The aim of the study was to determine prevalence of pathogenic E. coli among asymptomatic children and identify factors associated with presence of bacterium. Children (aged 0.5–8 years) without acute gastrointestinal symptoms were included in a cross-sectional study. Parents were asked to answer a questionnaire (demographic data, parental education, type of del…

La couverture vaccinale contre la grippe saisonnière du personnel soignant en gériatrie : mise au point

2016

Resume Position du probleme La vaccination antigrippale des professionnels de sante semble representer l’une des actions preventives des plus efficaces face a une pathologie a haut risque d’epidemie nosocomiale et potentiellement grave en milieu geriatrique. Ce travail avait pour objectif de faire une mise au point sur le statut vaccinal antigrippal chez le personnel soignant en geriatrie et les raisons expliquant leur reticence vis-a-vis de cette vaccination, afin d’emettre des propositions d’amelioration de la couverture vaccinale. Methode Une recherche bibliographique des articles publies depuis 2000 dans le domaine de la geriatrie, des maladies infectieuses ou de la pneumologie a ete re…