A single mutation in the glycophorin A binding site of hepatitis A virus enhances virus clearance from the blood and results in a lower fitness variant

Hepatitis A virus (HAV) has previously been reported to bind to human red blood cells through interaction with glycophorin A. Residue K221 of VP1 and the surrounding VP3 residues are involved in such an interaction. This capsid region is specifically recognized by the monoclonal antibody H7C27. A monoclonal antibody-resistant mutant with the mutation G1217D has been isolated. In the present study, the G1217D mutant was characterized physically and biologically in comparison with the parental HM175 43c strain. The G1217D mutant is more sensitive to acid pH and binds more efficiently to human and rat erythrocytes than the parental 43c strain. In a rat model, it is eliminated from serum more rapidly and consequently reaches the liver with a certain delay compared to the parental 43c strain. In competition experiments performed in vivo in the rat model, the G1217D mutant was efficiently outcompeted by the parental 43c strain. Only in the presence of antibodies reacting specifically with the parental 43c strain could the G1217D mutant outcompete the parental 43c strain in serum, although the latter still showed a remarkable ability to reach the liver. Altogether, these results indicate that the G1217D mutation induces a low fitness phenotype which could explain the lack of natural antigenic variants of the glycophorin A binding site.     

Fertilizing Methods and Nutrient Balance at the End of Traditional Organic Agriculture in the Mediterranean Bioregion: Catalonia (Spain) in the 1860s

By reconstructing the nutrient balance of a Catalan village circa 1861–65 we examine the sustainability of organic agricultural systems in the northwest Mediterranean bioregion prior to the green revolution and the question of whether the nutrients extracted from the soil were replenished. With a population density of 59 inhabitants per square km, similar to other northern European rural areas at that time, and a lower livestock density per cropland unit, this village experienced a manure shortage. The gap was filled by other labour-intensive ways of transferring nutrients from uncultivated areas into the cropland. Key elements in this agricultural system were vineyards because they have few nutrient requirements, and woodland and scrublands as sources of relevant amounts of nutrients collected in several ways.     

Biochemical behaviour of an incidentally diagnosed silent corticotroph adenoma

Silent corticotroph adenoma (SCA) is a non-functioning macroadenoma that has positive immunoreactivity for ACTH. Few studies have evaluated the biochemical behaviour of these tumours. We present the case of a 65-year-old male incidentally diagnosed with SCA, in which an exhaustive study of the corticotroph axis was conducted.     

Using successional theory to measure marine ecosystem health

Marine ecosystems are diverse and complex, providing significant challenges to the development of generalizable metrics of ecosystem health. Of particular concern is the varied form of change caused by multiple human activities, which limits the capacity to generate a single measure to encapsulate the overall condition of the ecosystem. Here we consider how successional theory can help to simplify our understanding of marine community structure, especially when viewed in context of human disturbance. During succession, the emergent properties of communities change in predictable ways. As communities mature, there is an increase in total production and biomass, the mean size of organisms, the level of internal recycling of food and nutrients, and the mean trophic level. Using a set of multi-species trophic models, we explore the changes in community structure that are likely to occur during succession. These changes include increases in biomass within trophic levels due to decreased rates of energy and food loss through trophic and production inefficiencies, and potential shifts from top-down control early in succession to bottom-up later. Because human activities disproportionately favor early-successional species, we can gain insights by considering community degradation in the context of succession being played in reverse. Indicators of health based on ecological succession thus provide a mechanistic view to measure the impact of human activities (both positive and negative) on marine ecosystems.     

Effects of Disinfection on Legionella spp., Eukarya, and Biofilms in a Hot Water System

Legionella species are frequently detected in hot water systems, attached to the surface as a biofilm. In this work, the dynamics of Legionella spp. and diverse bacteria and eukarya associated together in the biofilm, coming from a pilot scale 1 system simulating a real hot water system, were investigated throughout 6 months after two successive heat shock treatments followed by three successive chemical treatments. Community structure was assessed by a fingerprint technique, single-strand conformation polymorphism (SSCP). In addition, the diversity and dynamics of Legionella and eukarya were investigated by small-subunit (SSU) ribosomal cloning and sequencing. Our results showed that pathogenic Legionella species remained after the heat shock and chemical treatments (Legionella pneumophila and Legionella anisa, respectively). The biofilm was not removed, and the bacterial community structure was transitorily affected by the treatments. Moreover, several amoebae had been detected in the biofilm before treatments (Thecamoebae sp., Vannella sp., and Hartmanella vermiformis) and after the first heat shock treatment, but only H. vermiformis remained. However, another protozoan affiliated with Alveolata, which is known as a host cell for Legionella, dominated the eukaryal species after the second heat shock and chemical treatment tests. Therefore, effective Legionella disinfection may be dependent on the elimination of these important microbial components. We suggest that eradicating Legionella in hot water networks requires better study of bacterial and eukaryal species associated with Legionella in biofilms.     

Draft Genome Sequence Determination for Cystic Fibrosis and Chronic Granulomatous Disease Burkholderia multivorans Isolates

Burkholderia multivorans is a Gram-negative bacterium and a member of the Burkholderia cepacia complex, which is frequently associated with respiratory infections in people with cystic fibrosis (CF) and chronic granulomatous disease (CGD). We are reporting the genome sequences of 4 B. multivorans strains, 2 from CF patients and 2 from CGD patients.     

Molecular regulation of both dietary vitamin A and fatty acid absorption and metabolism associated with larval morphogenesis of Senegalese sole (Solea senegalensis)

The present study aimed to deepen the understanding of molecular mechanisms governing the absorption and metabolism of some nutrients, growth and development in larvae of Senegalese sole (Solea senegalensis) fed with Artemia enriched with Easy Selco© (ES, INVE) or Aquagrow Gold© (AGG, ABN), which mainly differed in their vitamin A (VA) content and fatty acid composition. The expression profile of genes involved in VA metabolism (crbp2, rbp, crabp1), lipid transport (i-fabp, l-fabp), nuclear receptors for VA and fatty acids (rarα1, rxrα, pparβ), growth (igf1, igf2 and their receptor igf1r) and development (bgp) was analyzed at 22, 30 and 38 days post hatching. The main results suggested that the amount of VA absorbed by larvae is controlled at the intestinal level by crbp2 in both groups, preventing excessive accumulation of this vitamin in the target tissues. The stable expression of i-fabp in the ES group with age could cause an excessive fat accumulation in the intestine inducing, in turn, the steatosis found in the liver and vascular system of these specimens. In liver, the regulation of rbp and fabp expression reflected the status of the physiological functions demanding VA and lipids. The findings revealed that dietary composition induced different strategies for VA and lipid absorption and metabolism affecting, in turn, larval development, growth and health.     

Structural Organization of Mammalian Prions as Probed by Limited Proteolysis

Elucidation of the structure of PrP^Sc continues to be one major challenge in prion research. The mechanism of propagation of these infectious agents will not be understood until their structure is solved. Given that high resolution techniques such as NMR or X-ray crystallography cannot be used, a number of lower resolution analytical approaches have been attempted. Thus, limited proteolysis has been successfully used to pinpoint flexible regions within prion multimers (PrP^Sc). However, the presence of covalently attached sugar antennae and glycosylphosphatidylinositol (GPI) moieties makes mass spectrometry-based analysis impractical. In order to surmount these difficulties we analyzed PrP^Sc from transgenic mice expressing prion protein (PrP) lacking the GPI membrane anchor. Such animals produce prions that are devoid of the GPI anchor and sugar antennae, and, thereby, permit the detection and location of flexible, proteinase K (PK) susceptible regions by Western blot and mass spectrometry-based analysis. GPI-less PrP^Sc samples were digested with PK. PK-resistant peptides were identified, and found to correspond to molecules cleaved at positions 81, 85, 89, 116, 118, 133, 134, 141, 152, 153, 162, 169 and 179. The first 10 peptides (to position 153), match very well with PK cleavage sites we previously identified in wild type PrP^Sc. These results reinforce the hypothesis that the structure of PrP^Sc consists of a series of highly PK-resistant β-sheet strands connected by short flexible PK-sensitive loops and turns. A sizeable C-terminal stretch of PrP^Sc is highly resistant to PK and therefore perhaps also contains β-sheet secondary structure.     

Circadian-related heteromerization of adrenergic and dopamine D₄ receptors modulates melatonin synthesis and release in the pineal gland

The role of the pineal gland is to translate the rhythmic cycles of night and day encoded by the retina into hormonal signals that are transmitted to the rest of the neuronal system in the form of serotonin and melatonin synthesis and release. Here we describe that the production of both melatonin and serotonin by the pineal gland is regulated by a circadian-related heteromerization of adrenergic and dopamine D₄ receptors. Through α_{1 B}-D₄ and β₁-D₄ receptor heteromers dopamine inhibits adrenergic receptor signaling and blocks the synthesis of melatonin induced by adrenergic receptor ligands. This inhibition was not observed at hours of the day when D₄ was not expressed. These data provide a new perspective on dopamine function and constitute the first example of a circadian-controlled receptor heteromer. The unanticipated heteromerization between adrenergic and dopamine D₄ receptors provides a feedback mechanism for the neuronal hormone system in the form of dopamine to control circadian inputs.     

Hepatitis A virus evolution and the potential emergence of new variants escaping the presently available vaccines

Hepatitis A is the most common infection of the liver worldwide and is fecal-orally transmitted. Its incidence tends to decrease with improvements in hygiene conditions but at the same time its severity increases. Hepatitis A virus is the causative agent of acute hepatitis in humans and belongs to the Hepatovirus genus in the Picornaviridae family, and it has very unique characteristics. This article reviews some molecular and biological properties that allow the virus to live in a very quiescent way and to build an extremely stable capsid that is able to persist in and out of the body. Additionally, the relationship between the genomic composition and the structural and antigenic properties of the capsid is discussed, and the potential emergence of antigenic variants is evaluated from an evolutionary perspective.