Decreased Toll-like receptor 8 expression and lower TNF-alpha synthesis in infants with acute RSV infection

Background

Toll-like receptors (TLRs) are part of the innate immune system, able to recognize pathogen-associated molecular patterns and activate immune system upon pathogen challenge. Respiratory syncytial virus (RSV) is a RNA virus particularly detrimental in infancy. It could cause severe lower respiratory tract disease and recurrent infections related to inadequate development of anti-viral immunity. The reason could be inadequate multiple TLRs engagement, including TLR8 in recognition of single-stranded viral RNA and diminished synthesis of inflammatory mediators due to a lower expression.

Methods

Intracellular TLR8 expression in peripheral blood monocytes from RSV-infected infants was profiled and compared to healthy adults and age matched controls. Whether the observed difference in TLR8 expression is a transitory effect, infants in convalescent phase (4-6 weeks later) were retested. Specific TLR8-mediated TNF-α production in monocytes during an acute and convalescent phase was analyzed.

Results

RSV-infected and healthy infants had lower percentage of TLR8-expressing monocytes than healthy adults whereas decreased of TLR8 protein levels were detected only for RSV-infected infant group. Lower protein levels of TLR8 in monocytes from RSV-infected infants, compared to healthy infants, negatively correlated with respiratory frequency and resulted in lower TNF-α synthesis upon a specific TLR8 stimulation. In the convalescent phase, levels of TLR8 increased, accompanied by increased TNF-α synthesis compared to acute infection.

Conclusions

Lower TLR8 expression observed in monocytes, during an acute RSV infection, might have a dampening impact on early anti-viral cytokine production necessary to control RSV replication, and subsequently initiate an adaptive Th1 type immune response leading to severe disease in infected infants.     

Sub-angstrom conformational changes of a single molecule captured by AFM variance analysis

A system's equilibrium variance can be analyzed to probe its underlying dynamics at higher resolution. Here, using single-molecule atomic-force microscope techniques, we show how the variance in the length of a single dextran molecule can be used to establish thermodynamic equilibrium and to detect conformational changes not directly observable with other methods. Dextran is comprised of a chain of pyranose rings that each undergoes an Angstrom-scale transition from a chair to boat conformation under a stretching force. Our analysis of the variance of the molecule's fluctuations verifies equilibrium throughout the force-extension curve, consistent with the expected thermodynamic ensemble. This validates further analysis of the variance in the transition region, which reveals an intermediate conformation between the chair and the boat on the sub-Angstrom scale. Our test of thermal equilibrium as well as our variance analysis can be readily extended to a wide variety of molecules, including proteins.     

Invasive ant (<Emphasis Type="Italic">Anoplolepis gracilipes</Emphasis>) disrupts pollination in pumpkin

Yellow crazy ant (Anoplolepis gracilipes (F. Smith); “YCA”) is known for its aggressive predatory ability and ability to exert exploitation competition on both native and other invasive ants via floral nectar. We argue that YCA invasion can exert both interference and exploitation competition on legitimate pollinators. In pumpkin fields (Cucurbita maxima L.) of south India, YCA infested the flowers, particularly the pistillate flowers, for nectar foraging. Pumpkin is a honey bee-mediated cross-pollinated monoecious plant that produces disproportionately very few pistillate flowers. We hypothesize that YCA presence in the flowers can affect the visitation rate and foraging time of honey bees in the flowers, the fruit set in pumpkins, and can exert predatory pressure on the honey bees if the bees linger in ant-colonized flowers. Both YCA and honey bees preferred to forage on the limited pistillate flowers in the plants. After colonizing the flowers, YCA did not retreat for hours, even upon disturbance by competitors, such as honey bees. Both the visitation frequency and the foraging time of honey bees were drastically reduced in ant-colonized flowers, and none of the ant-colonized flowers developed into fruits, suggesting that the YCA exert both an ecological and evolutionary pressure on pumpkin. The ants preyed upon about 17% of the honey bees that lingered in ant-colonized flowers, and the time the bees spent foraging predicted the fate of the bees. Exploitation competition exerted by the YCA on pumpkin may have far-reaching consequences for the pollination and productivity of this cash crop.     

A novel peptide tag for detection and purification of recombinant expressed proteins

Peptide tags have proven useful for the detection and purification of recombinant proteins. However cross reactions of antibodies raised to the tag are frequently observed due to the presence of host proteins containing all or parts of the tag. In this report we have identified a unique viral peptide sequence, R-tag, that by blast searches is absent from the commonly expression hosts Arabidopsis thaliana, Escherichia coli, Pichia pastoris and mouse myeloma cell NSO. We have prepared monoclonal antibodies to this peptide and confirmed the absence of this peptide sequence from the above genomes by Western blotting. We have also modified protein expression vectors to incorporate this sequence as a fusion tag in expressed proteins and shown its use to successfully purify recombinant proteins by immunoaffinity procedures.     

PCSK9 reduces the protein levels of the LDL receptor in mouse brain during development and after ischemic stroke

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a major role in cholesterol homeostasis through enhanced degradation of the LDL receptor (LDLR) in liver. As novel inhibitors/silencers of PCSK9 are now being tested in clinical trials to treat hypercholesterolemia, it is crucial to define the physiological consequences of the lack of PCSK9 in various organs. LDLR regulation by PCSK9 has not been extensively described during mouse brain development and injury. Herein, we show that PCSK9 and LDLR are co-expressed in mouse brain during development and at adulthood. Although the protein levels of LDLR and apolipoprotein E (apoE) in the adult brain of Pcsk9(-/-) mice are similar to those of wild-type (WT) mice, LDLR levels increased and were accompanied by a reduction of apoE levels during development. This suggests that the upregulation of LDLR protein levels in Pcsk9(-/-) mice enhances apoE degradation. Upon ischemic stroke, PCSK9 was expressed in the dentate gyrus between 24 h and 72 h following brain reperfusion. Although mouse behavior and lesion volume were similar, LDLR protein levels dropped ～2-fold less in the Pcsk9(-/-)-lesioned hippocampus, without affecting apoE levels and neurogenesis. Thus, PCSK9 downregulates LDLR levels during brain development and following transient ischemic stroke in adult mice.     

Blood pressure in relation to dietary calcium intake, alcohol consumption, blood lead, and blood cadmium in female nonsmokers

The interrelationship of dietary calcium (Ca) intake, alcohol consumption, blood lead (BPb), blood cadmium (BCd), age, and body mass index (BMI) to blood pressure was examined in 267 peasant women 40-85 years of age. They were residents of two rural areas in Croatia and differed with regard to dietary Ca intake: 100 women with low Ca intake (approximately 450 mg/day) and 167 women with relatively high Ca intake (approximately 940 mg/day). All of the women were nonsmokers and consumed very little or no alcohol. Median and range BPb values were 74 (29-251) microg/L in women with low Ca intake and 59 (21-263) microg/L in women with high Ca intake (p < 0.0002), whereas corresponding BCd values were 0.6 (0.2-3.6) microg/L and 0.6 (0.3-4.5) microg/L (p > 0.10). Results of multiple regression showed a significant (p < 0.05) increase in systolic blood pressure with age, BMI, and BCd, and marginally with alcohol consumption (multiple r = 0.48, p < 10(- 6)). An increase in diastolic blood pressure was significantly (p < 0.05) associated with BMI, age, and residence area (i.e., it was higher in women with low Ca intake), and marginally with BCd, and alcohol consumption (multiple r = 0.38, p < 10(-6)) When the two groups of women with different Ca intake were subdivided into consumers and nonconsumers of alcohol, BPb was related positively to alcohol consumption and inversely to Ca intake. The highest BPb was found in the subgroup of alcohol consumers with low Ca intake, and the lowest BPb in the subgroup of nonconsumers with high Ca intake: 78 (42-251) microg/L and 51 (22-192) microg/L, respectively (p < 10(-8)). Diastolic blood pressure was significantly higher in the former subgroup as compared to the latter: 95 (72-130) mm Hg and 90 (60-120) mm Hg, respectively (p < 0.05). This cannot be explained by age, BMI, or BCd, which were comparable in the two subgroups. The results indicate that alcohol consumption and low Ca intake can increase BPb, which may significantly contribute to an increase in diastolic blood pressure in female nonsmokers even at relatively low-level Pb exposure.     

Development and regulation of RORγt innate lymphoid cells

RORγt⁺ innate lymphoid cells (ILCs), or ILC3, play a fundamental role in the development of lymphoid tissues, as well as in homeostasis and defence of mucosal tissues. These cells produce IL-22, IL-17A and LTα1β2, key cytokines for the activation of epithelial defences and the recruitment of polymorphonuclear phagocytes. In the absence of ILC3, the early defence to infection and resistance to injury are compromised. Given the importance of ILC3 in mucosal immunity, significant efforts are made to discover their multiple functions and decipher their mode of action and regulation.     

Epistasis between mutations is host-dependent for an RNA virus

How, and to what extent, does the environment influence the way mutations interact? Do environmental changes affect both the sign and the magnitude of epistasis? Are there any correlations between environments in the variability, sign or magnitude of epistasis? Very few studies have tackled these questions. Here, we addressed them in the context of viral emergence. Most emerging viruses are RNA viruses with small genomes, overlapping reading frames and multifunctional proteins for which epistasis is abundant. Understanding the effect of host species in the sign and magnitude of epistasis will provide insights into the evolutionary ecology of infectious diseases and the predictability of viral emergence.     

Coding of Visual Object Features and Feature Conjunctions in the Human Brain

Object recognition is achieved through neural mechanisms reliant on the activity of distributed coordinated neural assemblies. In the initial steps of this process, an object''s features are thought to be coded very rapidly in distinct neural assemblies. These features play different functional roles in the recognition process - while colour facilitates recognition, additional contours and edges delay it. Here, we selectively varied the amount and role of object features in an entry-level categorization paradigm and related them to the electrical activity of the human brain. We found that early synchronizations (approx. 100 ms) increased quantitatively when more image features had to be coded, without reflecting their qualitative contribution to the recognition process. Later activity (approx. 200–400 ms) was modulated by the representational role of object features. These findings demonstrate that although early synchronizations may be sufficient for relatively crude discrimination of objects in visual scenes, they cannot support entry-level categorization. This was subserved by later processes of object model selection, which utilized the representational value of object features such as colour or edges to select the appropriate model and achieve identification.     

Effects of Potato Spindle Tuber Viroid Infection on Phytohormone and Antioxidant Responses in Symptomless Solanum laxum Plants

Journal of Plant Growth Regulation - To better understand the role of phytohormones and antioxidative responses in plant-viroid interaction, changes in endogenous phytohormone contents and...