RNA polymerase holoenzyme of Escherichia coli consists of the core enzyme with the subunit composition of ␣ 2 ␤␤Ј and a subunit, which directs the core enzyme to initiate transcription at specific promoter sites on DNA (4). The major factor, 70 (the rpoD gene product), is responsible for transcription of most genes expressed during the exponential cell growth (12, 17). Besides 70 , six different molecular species of alternative subunits in E. coli have been identified. 54 (the rpoN gene product) is concerned with expression of a wide variety of genes including those involved in nitrogen metabolism (27,28). Temperature upshift increases transcription of the genes under the control of two heat shock subunits, 32 (the rpoH gene product) (8, 41) and 24 (the rpoE gene product) (7). Holoenzyme containing 32 transcribes the heat shock genes including those encoding chaperons and proteases (42), while the regulons under the control of 24 are known to be involved in extracytoplasmic functions (6,35). 38 (the rpoS gene product) is a key factor in the stress response during the transition from the exponential growth phase to the stationary growth phase (13,25). 28 (the rpoF gene product) governs transcription of the genes for flagellar formation and chemotaxis (3, 31). FecI involved in the ferric citrate transport system is now identified as a member of a new subfamily of subunits for extracytoplasmic functions (2).The switch of gene expression pattern upon sudden exposure to various stresses is thought to take place by replacement of the subunit on RNA polymerase. The level of each form of holoenzyme is thought to be determined by the concentration of each subunit and its affinity to core RNA polymerase. Until recently, however, little was known of the intracellular concentrations of individual subunits except for the major subunit, 70 (17). We then initiated a systematic determination of the intracellular concentrations of the subunits, and in a previous study (19), we reported the levels of 38 in E. coli MC4100 growing under various conditions. As an extension of this line of research, we determined in this study the intracellular levels of four subunits in E. coli growing under steadystate conditions or various stress conditions by the same quantitative Western blot (immunoblot) method employed in the previous study (19). Since the MC4100 strain lacks 28 for flagellar formation (39), we analyzed another strain, W3110, in order to understand the possible influence of the lack of one subunit on the levels of other subunits. MATERIALS AND METHODSBacterial strains and growth conditions. The bacterial strains used in this study were E. coli W3110 and MC4100. Cells were grown at 30 or 37ЊC under aeration in Luria broth (LB). Growth was monitored by measuring the turbidity with a Klett-Summerson photometer. The culture conditions were fixed as follows. A few colonies from a culture grown overnight on a LB agar plate were inoculated onto 5 ml of fresh LB medium. At the cell density of 30 Klett units, the culture was diluted 2...

Large animals can undergo enormous growth during development, suggesting that axons in nerves and white matter tracts rapidly expand as well. Because integrated axons have no growth cones to extend from, it has been postulated that mechanical forces may stimulate axon elongation matching the growth of the animal. However, this distinct form of rapid and sustained growth of integrated axons has never been demonstrated. Here, we used a microstepper motor system to evaluate the effects of escalating rates of stretch on integrated axon tracts over days to weeks in culture. We found that axon tracts could be stretch grown at rates of 8 mm/d and reach lengths of 10 cm without disconnection. Despite dynamic and long-term elongation, stretched axons increased in caliber by 35%, while the morphology and density of cytoskeletal constituents and organelles were maintained. These data provide the first evidence that mechanical stimuli can induce extreme "stretch growth" of integrated axon tracts, far exceeding any previously observed limits of axon growth.

The genome DNA of Escherichia coli is associated with about 10 DNA-binding structural proteins, altogether forming the nucleoid. The nucleoid proteins play some functional roles, besides their structural roles, in the global regulation of such essential DNA functions as replication, recombination, and transcription. Using a quantitative Western blot method, we have performed for the first time a systematic determination of the intracellular concentrations of 12 species of the nucleoid protein in E. coli W3110, including CbpA (curved DNA-binding protein A), CbpB (curved DNA-binding protein B, also known as Rob [right origin binding protein]), DnaA (DNA-binding protein A), Dps (DNA-binding protein from starved cells), Fis (factor for inversion stimulation), Hfq (host factor for phage Qβ), H-NS (histone-like nucleoid structuring protein), HU (heat-unstable nucleoid protein), IciA (inhibitor of chromosome initiation A), IHF (integration host factor), Lrp (leucine-responsive regulatory protein), and StpA (suppressor oftd mutant phenotype A). Intracellular protein levels reach a maximum at the growing phase for nine proteins, CbpB (Rob), DnaA, Fis, Hfq, H-NS, HU, IciA, Lrp, and StpA, which may play regulatory roles in DNA replication and/or transcription of the growth-related genes. In descending order, the level of accumulation, calculated in monomers, in growing E. coli cells is Fis, Hfq, HU, StpA, H-NS, IHF*, CbpB (Rob), Dps*, Lrp, DnaA, IciA, and CbpA* (stars represent the stationary-phase proteins). The order of abundance, in descending order, in the early stationary phase is Dps*, IHF*, HU, Hfq, H-NS, StpA, CbpB (Rob), DnaA, Lrp, IciA, CbpA, and Fis, while that in the late stationary phase is Dps*, IHF*, Hfq, HU, CbpA*, StpA, H-NS, CbpB (Rob), DnaA, Lrp, IciA, and Fis. Thus, the major protein components of the nucleoid change from Fis and HU in the growing phase to Dps in the stationary phase. The curved DNA-binding protein, CbpA, appears only in the late stationary phase. These changes in the composition of nucleoid-associated proteins in the stationary phase are accompanied by compaction of the genome DNA and silencing of the genome functions.

Plaques composed of amyloid beta (Abeta) have been found within days following brain trauma in humans, similar to the hallmark plaque pathology of Alzheimer's disease (AD). Here, we evaluated the potential source of this Abeta and long-term mechanisms that could lead to its production. Inertial brain injury was induced in pigs via head rotational acceleration of 110 degrees over 20 ms in the coronal plane. Animals were euthanized at 3 hours, 3 days, 7 days, and 6 months post-injury. Immunohistochemistry and Western blot analyses of the brains were performed using antibodies specific for amyloid precursor protein (APP), Abeta peptides, beta-site APP-cleaving enzyme (BACE), presenilin-1 (PS-1), caspase-3, and caspase-mediated cleavage of APP (CCA). Substantial co-accumulation for all of these factors was found in swollen axons at all time points up to 6 months following injury. Western blot analysis of injured brains confirmed a substantial increase in the protein levels of these factors, particularly in the white matter. These data suggest that impaired axonal transport due to trauma induces long-term pathological co-accumulation of APP with BACE, PS-1, and activated caspase. The abnormal concentration of these factors may lead to APP proteolysis and Abeta formation within the axonal membrane compartment.

In this paper, we consider a large population of mobile stations that are interconnected by a multihop wireless network. The applications of this wireless infrastructure range from ad hoc networking (e.g., collaborative, distributed computing) to disaster recovery (e.g., fire, flood, earthquake), law enforcement (e.g., crowd control, search-and-rescue), and military (automated battlefield). Key characteristics of this system are the large number of users, their mobility, and the need to operate without the support of a fixed (wired or wireless) infrastructure. The last feature sets this system apart from existing cellular systems and in fact makes its design much more challenging. In this environment, we investigate routing strategies that scale well to large populations and can handle mobility. In addition, we address the need to support multimedia communications, with low latency requirements for interactive traffic and qualityof-service (QoS) support for real-time streams (voice/video). In the wireless routing area, several schemes have already been proposed and implemented (e.g., hierarchical routing, on-demand routing, etc.). We introduce two new schemes-fisheye state routing (FSR) and hierarchical state routing (HSR)-which offer some competitive advantages over the existing schemes. We compare the performance of existing and proposed schemes via simulation.

We demonstrated previously that dynamic stretch injury of cultured axons induces structural changes and Ca 2ϩ influx modulated by tetrodotoxin (TTX)-sensitive voltage-gated sodium channels (NaChs). In the present study, we evaluated potential damage to the NaCh ␣-subunit, which can cause noninactivation of NaChs. In addition, we explored the effects of pre-injury and post-injury treatment with TTX and protease inhibition on proteolysis of the NaCh ␣-subunit and intra-axonal calcium levels (

The results of this study indicate that damaged axons can serve as a large reservoir of Abeta, which may contribute to Abeta plaque formation after TBI in humans.

Background: Increased frequency of pathogenic variants in GBA, the causative gene for Gaucher disease, has been suggested to be associated with Parkinson disease (PD).Objectives: To conduct comprehensive resequencing of GBA to identify all sequence variants and to investigate the association of these variants with PD.