Impact of Fatty-Acid Labeling of Bacillus subtilis Membranes on the Cellular Lipidome and Proteome

Developing cultivation methods that yield chemically and isotopically defined fatty acid (FA) compositions within bacterial cytoplasmic membranes establishes an in vivo experimental platform to study membrane biophysics and cell membrane regulation using novel approaches. Yet before fully realizing the potential of this method, it is prudent to understand the systemic changes in cells induced by the labeling procedure itself. In this work, analysis of cellular membrane compositions was paired with proteomics to assess how the proteome changes in response to the directed incorporation of exogenous FAs into the membrane of Bacillus subtilis. Key findings from this analysis include an alteration in lipid headgroup distribution, with an increase in phosphatidylglycerol lipids and decrease in phosphatidylethanolamine lipids, possibly providing a fluidizing effect on the cell membrane in response to the induced change in membrane composition. Changes in the abundance of enzymes involved in FA biosynthesis and degradation are observed; along with changes in abundance of cell wall enzymes and isoprenoid lipid production. The observed changes may influence membrane organization, and indeed the well-known lipid raft-associated protein flotillin was found to be substantially down-regulated in the labeled cells – as was the actin-like protein MreB. Taken as a whole, this study provides a greater depth of understanding for this important cell membrane experimental platform and presents a number of new connections to be explored in regard to modulating cell membrane FA composition and its effects on lipid headgroup and raft/cytoskeletal associated proteins

KLEIN: A New Family of Lightweight Block Ciphers

Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while in the same time its hardware implementation can also be compact

Mechanisms whereby insulin increases diacylglycerol in BC3H-1 myocytes

We previously suggested that insulin increases diacylglycerol (DAG) in BC3H-1 myocytes, both by increases in synthesis de novo of phosphatidic acid (PA) and by hydrolysis of non-inositol-containing phospholipids, such as phosphatidylcholine (PC) and phosphatidylethanolamine (PE). We have now evaluated these insulin effects more thoroughly, and several potential mechanisms for their induction. In studies of the effect on PA synthesis de novo, insulin stimulated [2-3H]glycerol incorporation into PA, DAG, PC/PE and total glycerolipids of BC3H-1 myocytes, regardless of whether insulin was added simultaneously with, or after 2 h or 3 or 10 days of prelabelling with, [2-3H]glycerol. In prelabelled cells, time-related changes in [2-3H]glycerol labelling of DAG correlated well with increases in DAG content: both were maximal in 30-60 s and persisted for 20-30 min. [2-3H]Glycerol labelling of glycerol 3-phosphate, on the other hand, was decreased by insulin, presumably reflecting increased utilization for PA synthesis. Glycerol 3-phosphate concentrations were 0.36 and 0.38 mM before and 1 min after insulin treatment, and insulin effects could not be explained by increases in glycerol 3-phosphate specific radioactivity. In addition to that of [2-3H]glycerol, insulin increased [U-14C]glucose and [1,2,3-3H]glycerol incorporation into DAG and other glycerolipids. Effects of insulin on [2-3H]glycerol incorporation into DAG and other glycerolipids were half-maximal and maximal at 2 nM- and 20 nM-insulin respectively, and were not dependent on glucose concentration in the medium, extracellular Ca2+ or protein synthesis. Despite good correlation between [3H]DAG and DAG content, calculated increases in DAG content from glycerol 3-phosphate specific radioactivity (i.e. via the pathway of PA synthesis de novo) could account for only 15-30% of the observed increases in DAG content. In addition to increases in [3H]glycerol labelling of PC/PE, insulin rapidly (within 30 s) increased PC/PE labelling by [3H]arachidonic acid, [3H]myristic acid, and [14C]choline. Phenylephrine, ionophore A23187 and phorbol esters did not increase [2-3H]glycerol incorporation into DAG or other glycerolipids in 2-h-prelabelling experiments; thus activation of the phospholipase C which hydrolyses phosphatidylinositol, its mono- and bis-phosphate, Ca2+ mobilization, and protein kinase C activation, appear to be ruled out as mechanisms to explain the insulin effect on synthesis de novo of PA, DAG and PC.(ABSTRACT TRUNCATED AT 400 WORDS

Lysosomal enzyme cathepsin D protects against alpha-synuclein aggregation and toxicity

α-synuclein (α-syn) is a main component of Lewy bodies (LB) that occur in many neurodegenerative diseases, including Parkinson's disease (PD), dementia with LB (DLB) and multi-system atrophy. α-syn mutations or amplifications are responsible for a subset of autosomal dominant familial PD cases, and overexpression causes neurodegeneration and motor disturbances in animals. To investigate mechanisms for α-syn accumulation and toxicity, we studied a mouse model of lysosomal enzyme cathepsin D (CD) deficiency, and found extensive accumulation of endogenous α-syn in neurons without overabundance of α-syn mRNA. In addition to impaired macroautophagy, CD deficiency reduced proteasome activity, suggesting an essential role for lysosomal CD function in regulating multiple proteolytic pathways that are important for α-syn metabolism. Conversely, CD overexpression reduces α-syn aggregation and is neuroprotective against α-syn overexpression-induced cell death in vitro. In a C. elegans model, CD deficiency exacerbates α-syn accumulation while its overexpression is protective against α-syn-induced dopaminergic neurodegeneration. Mutated CD with diminished enzymatic activity or overexpression of cathepsins B (CB) or L (CL) is not protective in the worm model, indicating a unique requirement for enzymatically active CD. Our data identify a conserved CD function in α-syn degradation and identify CD as a novel target for LB disease therapeutics

A MAC Mode for Lightweight Block Ciphers

status: accepte

Evaluation of reporting timeliness of public health surveillance systems for infectious diseases

BACKGROUND: Timeliness is a key performance measure of public health surveillance systems. Timeliness can vary by disease, intended use of the data, and public health system level. Studies were reviewed to describe methods used to evaluate timeliness and the reporting timeliness of National Notifiable Diseases Surveillance System (NNDSS) data was evaluated to determine if this system could support timely notification and state response to multistate outbreaks. METHODS: Published papers that quantitatively measured timeliness of infectious disease surveillance systems operating in the U.S. were reviewed. Median reporting timeliness lags were computed for selected nationally notifiable infectious diseases based on a state-assigned week number and various date types. The percentage of cases reported within the estimated incubation periods for each disease was also computed. RESULTS: Few studies have published quantitative measures of reporting timeliness; these studies do not evaluate timeliness in a standard manner. When timeliness of NNDSS data was evaluated, the median national reporting delay, based on date of disease onset, ranged from 12 days for meningococcal disease to 40 days for pertussis. Diseases with the longer incubation periods tended to have a higher percentage of cases reported within its incubation period. For acute hepatitis A virus infection, which had the longest incubation period of the diseases studied, more than 60% of cases were reported within one incubation period for each date type reported. For cryptosporidiosis, Escherichia coli O157:H7 infection, meningococcal disease, salmonellosis, and shigellosis, less than 40% of cases were reported within one incubation period for each reported date type. CONCLUSION: Published evaluations of infectious disease surveillance reporting timeliness are few in number and are not comparable. A more standardized approach for evaluating and describing surveillance system timeliness should be considered; a recommended methodology is presented. Our analysis of NNDSS reporting timeliness indicated that among the conditions evaluated (except for acute hepatitis A infection), the long reporting lag and the variability across states limits the usefulness of NNDSS data and aberration detection analysis of those data for identification of and timely response to multistate outbreaks. Further evaluation of the factors that contribute to NNDSS reporting timeliness is warranted