Notch signalling in the regulation of peripheral T-cell function

The Notch signalling pathway plays a highly-conserved role in regulating the cellular differentiation and proliferation events that characterise pattern formation in the embryo. As cells in the embryo respond to environmental signals, similarly T-cells in the peripheral immune system must monitor their environment for antigens and respond accordingly by entering one of several potential differentiation pathways. Recent studies have identified a role for the Notch pathway in regulating the responses of T-cells in the periphery. In this review, we discuss these findings in the context of the Notch signalling pathway's role as an orchestrator of cellular differentiation, and propose a central role for Notch as a regulator of immune system function.     

Anaerobic Growth and Fermentation Characteristics of Paecilomyces lilacinus Isolated from Mullet Gut

The anaerobic growth and fermentation of a marine isolate of Paecilomyces lilacinus is described. The fungus was isolated from mullet gut and grew optimally at 30°C and at a salinity of ≥10%. The best growth was obtained with glucose or laminarin as substrate, and the growth yield was 5.0 g (dry weight of fungus) per mol of hexose fermented. Moles of products as a percentage of moles of hexose fermented were acetate, 29.0%; ethanol, 156.6%; CO₂, 108.0%; and lactate, 4.3%. Together these products accounted for >80% of hexose carbon. Hydrogen and formate were not detectable as fermentation end products (<0.5%). Other substrates utilized for growth, although less effectively than laminarin or glucose, included the monosaccharides galactose, fructose, arabinose, and xylose and the disaccharides maltose and cellobiose. No growth of the fungus occurred on cellulose, and of a variety of other polysaccharides tested only xylan supported growth.     

Fucosylation enhances colonization of ticks by Anaplasma phagocytophilum

Fucosylated structures participate in a wide range of pathological processes in eukaryotes and prokaryotes. The impact of fucose on microbial pathogenesis, however, has been less appreciated in arthropods of medical relevance. Thus, we used the tick‐borne bacterium Anaplasma phagocytophilum– the agent of human granulocytic anaplasmosis to understand these processes. Here we show that A. phagocytophilum uses α1,3‐fucose to colonize ticks. We demonstrate that A. phagocytophilum modulates the expression of α1,3‐fucosyltransferases and gene silencing significantly reduces colonization of tick cells. Acquisition but not transmission of A. phagocytophilum was affected when α1,3‐fucosyltransferases were silenced during tick feeding. Our results uncover a novel mechanism of pathogen colonization in arthropods. Decoding mechanisms of pathogen invasion in ticks might expedite the development of new strategies to interfere with the life cycle of A. phagocytophilum.     

Systematic segregation to mutant mitochondrial DNA and accompanying loss of mitochondrial DNA in human NT2 teratocarcinoma Cybrids

In this study a well-characterized pathological mutation at nucleotide position 3243 of human mitochondrial DNA was introduced into human rho(0) teratocarcinoma (NT2) cells. In cloned and mixed populations of NT2 cells heteroplasmic for the mutation, mitotic segregation toward increasing levels of mutant mitochondrial DNA always occurred. Rapid segregation was frequently followed by complete loss of mitochondrial DNA. These findings support the idea that pathological mitochondrial DNA mutations are particularly deleterious in specific cell types, which can explain some of the tissue-specific aspects of mitochondrial DNA diseases. Moreover, these findings suggest that mitochondrial DNA depletion may be an important and widespread feature of mitochondrial DNA disease.     

An apoA-I mimetic peptide increases LCAT activity in mice through increasing HDL concentration

Lecithin cholesterol acyltransferase (LCAT) plays a key role in the reverse cholesterol transport (RCT) process by converting cholesterol to cholesteryl ester to form mature HDL particles, which in turn deliver cholesterol back to the liver for excretion and catabolism. HDL levels in human plasma are negatively correlated with cardiovascular risk and HDL functions are believed to be more important in atheroprotection. This study investigates whether and how D-4F, an apolipoprotein A-I (apoA-I) mimetic peptide, influences LCAT activity in the completion of the RCT process. We demonstrated that the apparent rate constant value of the LCAT enzyme reaction gives a measure of LCAT activity and determined the effects of free metals and a reducing agent on LCAT activity, showing an inhibition hierarchy of Zn²⁺>Mg²⁺>Ca²⁺ and no inhibition with β-mercaptoethanol up to 10 mM. We reconstituted nano-disc particles using apoA-I or D-4F with phospholipids. These particles elicited good activity in vitro in the stimulation of cholesterol efflux from macrophages through the ATP-binding cassette transporter A1 (ABCA1). With these particles we studied the LCAT activity and demonstrated that D-4F did not activate LCAT in vitro. Furthermore, we have done in vivo experiments with apoE-null mice and demonstrated that D-4F (20 mg/kg body weight, once daily subcutaneously) increased LCAT activity and HDL level as well as apoA-I concentration at 72 hours post initial dosing. Finally, we have established a correlation between HDL concentration and LCAT activity in the D-4F treated mice.     

Cryopreservation of economically valuable marine micro-algae in the classes Bacillariophyceae, Chlorophyceae, Cyanophyceae, Dinophyceae, Haptophyceae, Prasinophyceae, and Rhodophyceae

The ability to routinely cryopreserve micro-algal species reduces costs associated with maintaining large culture collections and reduces the risks of losing particular strains or species through contamination and genetic drift. Cryopreservation is also a useful adjunct in aquaculture hatcheries for strains of micro-algae where the nutritional status may change as a result of continuous sub-culture. In this study, cryopreservation of isolates from seven micro-algal classes was investigated. Successful candidates included the marine dinoflagellates Amphidinium carterae, Amphidinium trulla, and Gymnodinium simplex, and the haptophytes Chrysochromulina simplex, Prymnesium parvum, Prymnesium parvum f. patelliferum, Isochrysis galbana, and Pavlova lutheri. Also successfully cryopreserved were the planktonic diatoms Chaetoceros calcitrans, Chaetoceros muelleri, Chaetoceros sp., and the benthic Nitzschia ovalis, the chlorophyte Chlamydomonas coccoides, the rhodophyte Porphyridium purpureum, the prasinophytes Tetraselmis chuii, and Tetraselmis suecica, and the cyanophytes Raphidiopsis sp., and Aphanizomenon flos-aquae. All species were successfully cryopreserved using 15% Me2SO.     

Lack of Interleukin-6 (IL-6) Enhances Susceptibility to Infection but Does Not Alter Latency or Reactivation of Herpes Simplex Virus Type 1 in IL-6 Knockout Mice

The ability of the pleotropic, proinflammatory cytokine interleukin-6 (IL-6) to affect the replication, latency, and reactivation of herpes simplex virus type 1 (HSV-1) in cell culture and in IL-6 knockout (KO) mice was studied. In initial studies, we found no effect of exogenous IL-6, monoclonal antibodies to IL-6, or monoclonal antibody to the IL-6 coreceptor, gp130, on HSV-1 replication in vitro by plaque assay or reactivation ex vivo by explant cocultivation of latently infected murine trigeminal ganglia (TG). Compared with the wild-type (WT) mice, the IL-6 KO mice were less able to survive an ocular challenge with 10(5) PFU of HSV-1 (McKrae) (40% survival of WT and 7% survival KO mice; P = 0.01). There was a sixfold higher 50% lethal dose of HSV-1 in WT than IL-6 KO mice (1.7 x 10(4) and 2.7 x 10(3) PFU, respectively). No differences were observed in titers of virus recovered from the eyes, TG, or brains or in the rates of virus reactivation by explant cocultivation of TG from latently infected WT or KO mice. Exposure of latently infected mice to UV light resulted in comparable rates of reactivation and in the proportions of WT and KO animals experiencing reactivation. Moreover, quantitative PCR assays showed nearly identical numbers of HSV-1 genomes in latently infected WT and IL-6 KO mice. These studies indicate that while IL-6 plays a role in the protection of mice from lethal HSV infection, it does not substantively influence HSV replication, spread to the nervous system, establishment of latency, or reactivation.     

The extended relationship between child cardiovascular risks and academic performance measures

Objective: To examine the relationship between children's overweight status and other cardiovascular risk fitness factors and academic performance among fifth‐grade students. Research Methods and Procedures: Using a sample of 968 fifth‐grade students (50.7% boys; mean age = 10.6 years), children's cardiovascular risks (BMI, blood pressure, acanthosis nigricans) and fitness measures were compared with their mean group performance scores across four subscales (mathematics, reading/language arts, science, and social studies) of a statewide standardized academic performance test. Results: Of this sample, 39% were either at risk for being overweight or were already overweight; slightly over one half were of normal weight. Initial findings revealed a significant relationship between children's weight category and their reading/language arts, mathematics, and science test scores even after controlling for a proxy of socioeconomic status. When additional cardiovascular risk and fitness measures were included in the model, however, children's BMI status had no association. Instead, a composite fitness index, children's blood pressure, sex, and proxy of socioeconomic status were significantly associated with children's academic test scores. Discussion: This study expanded our understanding of the connection between children's overweight risks and academic performance by examining the impact of other cardiovascular risk factors such as high blood pressure and measures of fitness. These findings support the development and implementation of childhood cardiovascular risk surveillance programs that evaluate not only children's overweight risks but also their fitness, risk for type 2 diabetes, and/or high blood pressure by showing a relationship between some of these risks and children's academic test performance.