Natural occurrence of microbial sulphur oxidation by long-range electron transport in the seafloor

Recently, a novel mode of sulphur oxidation was described in marine sediments, in which sulphide oxidation in deeper anoxic layers was electrically coupled to oxygen reduction at the sediment surface. Subsequent experimental evidence identified that long filamentous bacteria belonging to the family Desulfobulbaceae likely mediated the electron transport across the centimetre-scale distances. Such long-range electron transfer challenges some long-held views in microbial ecology and could have profound implications for sulphur cycling in marine sediments. But, so far, this process of electrogenic sulphur oxidation has been documented only in laboratory experiments and so its imprint on the seafloor remains unknown. Here we show that the geochemical signature of electrogenic sulphur oxidation occurs in a variety of coastal sediment environments, including a salt marsh, a seasonally hypoxic basin, and a subtidal coastal mud plain. In all cases, electrogenic sulphur oxidation was detected together with an abundance of Desulfobulbaceae filaments. Complementary laboratory experiments in intertidal sands demonstrated that mechanical disturbance by bioturbating fauna destroys the electrogenic sulphur oxidation signal. A survey of published geochemical data and 16S rRNA gene sequences identified that electrogenic sulphide oxidation is likely present in a variety of marine sediments with high sulphide generation and restricted bioturbation, such as mangrove swamps, aquaculture areas, seasonally hypoxic basins, cold sulphide seeps and possibly hydrothermal vent environments. This study shows for the first time that electrogenic sulphur oxidation occurs in a wide range of marine sediments and that bioturbation may exert a dominant control on its natural distribution.     

Gα<Subscript>16</Subscript> interacts with tetratricopeptide repeat 1 (TPR1) through its β3 region to activate Ras independently of phospholipase Cβ signaling

Background  

G protein-coupled receptors constitute the largest family of cell surface receptors in the mammalian genome. As the core of the G protein signal transduction machinery, the Gα subunits are required to interact with multiple partners. The GTP-bound active state of many Gα subunits can bind a multitude of effectors and regulatory proteins. Yet it remains unclear if the different proteins utilize distinct or common structural motifs on the Gα subunit for binding. Using Gα₁₆ as a model, we asked if its recently discovered adaptor protein tetratricopeptide repeat 1 (TPR1) binds to the same region as its canonical effector, phospholipase Cβ (PLCβ).     

Genetic variants of TSLP and asthma in an admixed urban population

Background

Thymic stromal lymphopoietin (TSLP), an IL7-like cytokine produced by bronchial epithelial cells is upregulated in asthma and induces dendritic cell maturation supporting a Th2 response. Environmental pollutants, including tobacco smoke and diesel exhaust particles upregulate TSLP suggesting that TSLP may be an interface between environmental pollution and immune responses in asthma. Since asthma is prevalent in urban communities, variants in the TSLP gene may be important in asthma susceptibility in these populations.

Objectives

To determine whether genetic variants in TSLP are associated with asthma in an urban admixed population.

Methodology and Main Results

Ten tag-SNPs in the TSLP gene were analyzed for association with asthma using 387 clinically diagnosed asthmatic cases and 212 healthy controls from an urban admixed population. One SNP (rs1898671) showed nominally significant association with asthma (odds ratio (OR) = 1.50; 95% confidence interval (95% CI): 1.09–2.05, p = 0.01) after adjusting for age, BMI, income, education and population stratification. Association results were consistent using two different approaches to adjust for population stratification. When stratified by smoking status, the same SNP showed a significantly increased risk associated with asthma in ex-smokers (OR = 2.00, 95% CI: 1.04–3.83, p = 0.04) but not significant in never-smokers (OR = 1.34; 95% CI: 0.93–1.94, p = 0.11). Haplotype-specific score test indicated that an elevated risk for asthma was associated with a specific haplotype of TSLP involving SNP rs1898671 (OR = 1.58, 95% CI: 1.10–2.27, p = 0.01). Association of this SNP with asthma was confirmed in an independent large population-based cohort consortium study (OR = 1.15, 95% CI: 1.07–1.23, p = 0.0003) and the results stratified by smoking status were also validated (ex-smokers: OR = 1.21, 95% CI: 1.08–1.34, p = 0.003; never-smokers: OR = 1.06, 95% CI: 0.94–1.17, p = 0.33).

Conclusions

Genetic variants in TSLP may contribute to asthma susceptibility in admixed urban populations with a gene and environment interaction.     

CK2α is essential for embryonic morphogenesis

CK2 is a highly conserved serine-threonine kinase involved in biological processes such as embryonic development, circadian rhythms, inflammation, and cancer. Biochemical experiments have implicated CK2 in the control of several cellular processes and in the regulation of signal transduction pathways. Our laboratory is interested in characterizing the cellular, signaling, and molecular mechanisms regulated by CK2 during early embryonic development. For this purpose, animal models, including mice deficient in CK2 genes, are indispensable tools. Using CK2α gene-deficient mice, we have recently shown that CK2α is a critical regulator of mid-gestational morphogenetic processes, as CK2α deficiency results in defects in heart, brain, pharyngeal arch, tail bud, limb bud, and somite formation. Morphogenetic processes depend upon the precise coordination of essential cellular processes in which CK2 has been implicated, such as proliferation and survival. Here, we summarize the overall phenotype found in CK2α (-/- ) mice and describe our initial analysis aimed to identify the cellular processes affected in CK2α mutants.     

Argentine population genetic structure: large variance in Amerindian contribution

Argentine population genetic structure was examined using a set of 78 ancestry informative markers (AIMs) to assess the contributions of European, Amerindian, and African ancestry in 94 individuals members of this population. Using the Bayesian clustering algorithm STRUCTURE, the mean European contribution was 78%, the Amerindian contribution was 19.4%, and the African contribution was 2.5%. Similar results were found using weighted least mean square method: European, 80.2%; Amerindian, 18.1%; and African, 1.7%. Consistent with previous studies the current results showed very few individuals (four of 94) with greater than 10% African admixture. Notably, when individual admixture was examined, the Amerindian and European admixture showed a very large variance and individual Amerindian contribution ranged from 1.5 to 84.5% in the 94 individual Argentine subjects. These results indicate that admixture must be considered when clinical epidemiology or case control genetic analyses are studied in this population. Moreover, the current study provides a set of informative SNPs that can be used to ascertain or control for this potentially hidden stratification. In addition, the large variance in admixture proportions in individual Argentine subjects shown by this study suggests that this population is appropriate for future admixture mapping studies.     

C1q/TNF-related Protein 4 (CTRP4) Is a Unique Secreted Protein with Two Tandem C1q Domains That Functions in the Hypothalamus to Modulate Food Intake and Body Weight

CTRP4 is a unique member of the C1q family, possessing two tandem globular C1q domains. Its physiological function is poorly defined. Here, we show that CTRP4 is an evolutionarily conserved, ∼34-kDa secretory protein expressed in the brain. In human, mouse, and zebrafish brain, CTRP4 expression begins early in development and is widespread in the central nervous system. Neurons, but not astrocytes, express and secrete CTRP4, and secreted proteins form higher-order oligomeric complexes. CTRP4 is also produced by peripheral tissues and circulates in blood. Its serum levels are increased in leptin-deficient obese (ob/ob) mice. Functional studies suggest that CTRP4 acts centrally to modulate energy metabolism. Refeeding following an overnight fast induced the expression of CTRP4 in the hypothalamus. Central administration of recombinant protein suppressed food intake and altered the whole-body energy balance in both chow-fed and high-fat diet-fed mice. Suppression of food intake by CTRP4 is correlated with a decreased expression of orexigenic neuropeptide (Npy and Agrp) genes in the hypothalamus. These results establish CTRP4 as a novel nutrient-responsive central regulator of food intake and energy balance.     

Brazilian Microbiome Project: Revealing the Unexplored Microbial Diversity—Challenges and Prospects

The Brazilian Microbiome Project (BMP) aims to assemble a Brazilian Metagenomic Consortium/Database. At present, many metagenomic projects underway in Brazil are widely known. Our goal in this initiative is to co-ordinate and standardize these together with new projects to come. It is estimated that Brazil hosts approximately 20 % of the entire world’s macroorganism biological diversity. It is 1 of the 17 countries that share nearly 70 % of the world’s catalogued animal and plant species, and is recognized as one of the most megadiverse countries. At the end of 2012, Brazil has joined GBIF (Global Biodiversity Information Facility), as associated member, to improve the access to the Brazilian biodiversity data in a free and open way. This was an important step toward increasing international collaboration and clearly shows the commitment of the Brazilian government in directing national policies toward sustainable development. Despite its importance, the Brazilian microbial diversity is still considered to be largely unknown, and it is clear that to maintain ecosystem dynamics and to sustainably manage land use, it is crucial to understand the biological and functional diversity of the system. This is the first attempt to collect and collate information about Brazilian microbial genetic and functional diversity in a systematic and holistic manner. The success of the BMP depends on a massive collaborative effort of both the Brazilian and international scientific communities, and therefore, we invite all colleagues to participate in this project.     

Aerobic endospore-forming bacteria isolated from Antarctic soils as producers of bioactive compounds of industrial interest

Spore-forming bacteria are known to produce various enzymes and bioproducts valuable to different industries and to bear the harsh conditions found in the Antarctic environment. However, aerobic or facultative spore-forming bacterial communities found in maritime Antarctic soils yet remain poorly studied. In this study, 80 spore-forming and cold-adapted bacterial strains were isolated from nine different soil samples of King George Island, in maritime Antarctica, and further clustered into amplified ribosomal DNA restriction analysis groups within each soil. Representative strains were then identified as belonging to Bacillus, Rummeliibacillus, Paenibacillus and Sporosarcina by 16S rRNA gene sequencing. The ability to produce extracellular enzymes, antimicrobial substances and biosurfactants was determined in all isolates. The enzymatic activities most frequently found among the isolates were as follows: esterase (45 %), caseinase (30 %), amylase (16.2 %) and gelatinase (15 %). Biosurfactant production was detected in 25 % of the isolates. The growth inhibition of methicillin-resistant Staphylococcus aureus was observed in 13.7 % of the strains tested, but only two strains inhibited the growth of Candida albicans. The isolated spore-forming bacterial species were also compared with the characteristics of the different Antarctic soils sampled based on their physicochemical properties, showing that pH, C and P were the main factors correlated with the distribution of this group of bacteria in the Antarctic soils studied. These Antarctic endospore-forming bacterial strains may have a potential for industrial processes occurring at low temperatures.     

Meningoencephalitis Due to Listeria monocytogenes in a Pregnant Rhesus Macaque (Macaca mulatta)

We here report a spontaneous case of meningoencephalitis due to Listeria monocytogenes in an adult primiparous rhesus macaque (Macaca mulatta) during an outbreak of listeriosis in an outdoor enclosure. Clinical signs included tremors, abnormal posture, and altered mental status. Hematology and analyses of cerebrospinal fluid were consistent with bacterial infection. Pure cultures of L. monocytogenes were recovered from the placenta–abortus, cerebrospinal fluid, and brain tissue. The macaque did not respond to treatment and was euthanized. Histopathologic examination of the brain revealed acute meningoencephalitis. This case represents an unusual clinical and pathologic presentation of listeriosis in a nonhuman primate in which the dam and fetus both were affected.Listeria monocytogenes is a ubiquitous, facultative anaerobic, intracellular gram-positive coccobacillus. This bacterium is found in diverse environments including (but not limited to) soil, water, plant matter, food items, and the intestinal tract of mammalian hosts.^15,18 The organism is environmentally resistant, being able to survive in dried media for several months and in moist soil for up to a year.¹⁵ L. monocytogenes is the causative agent of listeriosis, a bacterial infection that has a worldwide distribution and affects a wide range of mammals and birds, including human beings.In people, L. monocytogenes is a relatively uncommon foodborne pathogen; its abilities to survive food processing and grow in cold conditions allow it to persist in appropriately stored or refrigerated foods.² In people, listeriosis occurs both sporadically and as large outbreaks,¹⁸ generally comprising 3 separate syndromes with clinical manifestations ranging from mild to life-threatening.³⁵ The most common form is seen in immunocompetent, nonpregnant adults as a febrile gastroenteritis.^2,18,21 The other 2 forms, which occur in fetuses and immunocompromised patients, are more severe.^19,21 In pregnant women, maternal listeriosis is asymptomatic or causes mild, flu-like symptoms, but the bacterium''s ability to cross the placenta and the blood–brain barrier of the fetus results in neonatal septicemia, meningitis, abortion, and stillbirth.¹⁶ In elderly and immunocompromised patients, septicemia and meningoencephalitis are life-threatening manifestations of literiosis.²⁶ The worldwide case fatality rate varies widely among countries, sometimes exceeding 50% despite what is considered to be appropriate antibiotic therapy.¹⁸ In 2009, the Centers for Disease Control reported 524 cases of listeriosis in the United States, which were associated with a 19% resulting in death.⁴In ruminants, listeriosis is also known as ‘circling disease’ and ‘silage disease.’^8,18,21 Foodborne infection with L. monocytogenes is well described, and many studies have shown that spoiled silage may be a source of listeria outbreaks.^8,18 Rhombencephalitis and diffuse meningoencephalitis are the most recognized forms of the infection in ruminants; sporadic abortion is reported also.²² Clinical signs of listeria encephalitis in cattle, sheep, and goats are characterized by unilateral or bilateral brainstem dysfunction and cranial nerve deficits. In sheep and goats, the course of the disease is acute, but the disease in cattle has a more chronic progression, with neurologic manifestations that can last 4 to 14 d.^1,22In rabbits, infection with L. monocytogenes is characterized by abortion in pregnant does or sudden death; neurologic signs are rare.¹ In poultry, an acute form with septicemia and sudden death occurs in adults, in contrast to a subacute–chronic form, with encephalitis, in the young.⁶The literature on L. monocytogenes in nonhuman primates is sparse^5,11,17,33 and more recently limited to experimental infection of pregnant animals. In pregnant rhesus macaques (Macaca mulatta), experimental infection during the last trimester of gestation can cause stillbirth with no other clinical signs.^23,24 In our colony, however, infection with L. monocytogenes is endemic. Every year, several spontaneous abortions or stillbirths in our outdoor colony are caused by infection of the dam with this organism. Culture of L. monocytogenes from both the abortus–fetus and placenta are well documented. As described in the literature,^23,24 the dams in our colony do not demonstrate any clinical signs prior to the abortion or stillbirth.During the winter to spring of 2011, one of our outdoor housing enclosures experienced an outbreak of listeriosis. This outside corral housed 100 rhesus macaques in a social group that included 42 reproductive females. Of these reproductive females, 37 (88%) were confirmed pregnant by abdominal palpation or ultrasonography or both. From January 2011 to May 2011, 19 (51%) stillbirths and neonatal deaths (in infants younger than 3 d) were reported in this enclosure; 13 (68%) of these tissues (placenta, 3; fetal lungs, 8; fetal peritoneum, 2) were culture-positive for L. monocytogenes. In all cases except the one presented here, the dam did not manifest any clinical signs prior to or after the delivery of a stillborn or premature birth with neonatal death.Here we describe an unusual case of listeriosis in a primiparous pregnant female rhesus macaque that manifested severe neurologic impairment and intrautero death of the fetus.