Testing assumptions of central place foraging theory: a study of Adélie penguins Pygoscelis adeliae in the Ross Sea

We investigated central place foraging (CPF) in the context of optimal foraging theory in Adélie penguins Pygoscelis adeliae of the southern Ross Sea by using satellite tracking and time‐depth recorders to explore foraging at two spatio‐temporal scales: within the day‐to‐day (sub‐mesoscale: single foraging trip, 10s of km²) and the entire breeding season (mesoscale: trips by multiple individuals across the collective foraging area, 100s of km²). Specifically, we examine whether three basic assumptions of the Orians–Pearson CPF model, shown to occur in other CPF species, are met: 1) within a patch, the rate of prey acquisition declines with time spent in that patch; 2) food is distributed in discrete patches and is not available between those patches; and 3) CPF species have knowledge of the potential (or average, at least) feeding rate within their universe of patches, and use this knowledge to determine their foraging strategy when planning or engaging in a foraging trip. We found that prey consumption rates did not decline with time spent in patches, and penguins foraged to some degree most of the time when at sea. Food availability, as measured by foraging dive rate, appeared to be predictable within the same day at the same location, but predictability broke down after 2 d at distances > 10 km away. We conclude that the assumptions of the Orians–Pearson CPF model are not a good fit to the circumstances of Ross Sea penguins, which clearly are central place foragers.     

Pyridyl amides as potent inhibitors of T-type calcium channels

A novel series of amide T-type calcium channel antagonists were prepared and evaluated using in vitro and in vivo assays. Optimization of the screening hit 3 led to identification of the potent and selective T-type antagonist 37 that displayed in vivo efficacy in rodent models of epilepsy and sleep.     

Design and synthesis of long acting inhaled corticosteroids for the treatment of asthma

In this Letter we present data for a novel series of ICS for the treatment of asthma. 'Inhalation by design' principles have been applied to a series of highly potent steroidal GR agonists, with a focus on optimising the potential therapeutic index in human. Pharmacokinetic properties were tuned with high intrinsic clearance and low oral bioavailability in mind, to minimise systemic exposure and reduce systemically driven adverse events. High CYP mediated clearance as well as glucuronidation were targeted to achieve high intrinsic clearance coupled with multiple routes of clearance to minimise drug-drug interactions. Furthermore, pharmaceutical properties such as stability, crystallinity and solubility were considered to ensure compatibility with a dry powder inhaler. This work culminated in the identification of the clinical candidate 15, which demonstrates preclinically the desired efficacy and safety profiles confirming its potential as an inhaled agent for the treatment of asthma.     

High-resolution melting genotyping of Enterococcus faecium based on multilocus sequence typing derived single nucleotide polymorphisms

We have developed a single nucleotide polymorphism (SNP) nucleated high-resolution melting (HRM) technique to genotype Enterococcus faecium. Eight SNPs were derived from the E. faecium multilocus sequence typing (MLST) database and amplified fragments containing these SNPs were interrogated by HRM. We tested the HRM genotyping scheme on 85 E. faecium bloodstream isolates and compared the results with MLST, pulsed-field gel electrophoresis (PFGE) and an allele specific real-time PCR (AS kinetic PCR) SNP typing method. In silico analysis based on predicted HRM curves according to the G+C content of each fragment for all 567 sequence types (STs) in the MLST database together with empiric data from the 85 isolates demonstrated that HRM analysis resolves E. faecium into 231 "melting types" (MelTs) and provides a Simpson's Index of Diversity (D) of 0.991 with respect to MLST. This is a significant improvement on the AS kinetic PCR SNP typing scheme that resolves 61 SNP types with D of 0.95. The MelTs were concordant with the known ST of the isolates. For the 85 isolates, there were 13 PFGE patterns, 17 STs, 14 MelTs and eight SNP types. There was excellent concordance between PFGE, MLST and MelTs with Adjusted Rand Indices of PFGE to MelT 0.936 and ST to MelT 0.973. In conclusion, this HRM based method appears rapid and reproducible. The results are concordant with MLST and the MLST based population structure.     

Structure and biosynthesis of the BT peptide antibiotic from Brevibacillus texasporus

We isolated a novel gram-positive bacterium, Brevibacillus texasporus, that produces an antibiotic, BT. BT is a group of related peptides that are produced by B. texasporus cells in response to nutrient limitation. We report here purification and determination of the structure of the most abundant BT isomer, BT1583. Amino acid composition and tandem mass spectrometry experiments yielded a partial BT1583 structure. The presence of ornithine and d-form residues in the partial BT1583 structure indicated that the peptide is synthesized by a nonribosomal peptide synthetase (NRPS). The BT NRPS operon was rapidly and accurately identified by using a novel in silico NRPS operon hunting strategy that involved direct shotgun genomic sequencing rather than the unreliable cosmid library hybridization scheme. Sequence analysis of the BT NRPS operon indicated that it encodes a colinear modular NRPS with a strict correlation between the NRPS modules and the amino acid residues in the peptide. The colinear nature of the BT NRPS enabled us to utilize the genomic information to refine the BT1583 peptide sequence to Me(2)-4-methyl-4-[(E)-2-butenyl]-4,N-methyl-threonine-L-dO-I-V-V-dK-V-dL-K-dY-L-V-CH2OH. In addition, we report the discovery of novel NRPS codons (sets of the substrate specificity-conferring residues in NRPS modules) for valine, lysine, ornithine, and tyrosine.     

Wnt/beta-catenin signaling acts upstream of N-myc, BMP4, and FGF signaling to regulate proximal-distal patterning in the lung

Branching morphogenesis in the lung serves as a model for the complex patterning that is reiterated in multiple organs throughout development. Beta-catenin and Wnt signaling mediate critical functions in cell fate specification and differentiation, but specific functions during branching morphogenesis have remained unclear. Here, we show that Wnt/beta-catenin signaling regulates proximal-distal differentiation of airway epithelium. Inhibition of Wnt/beta-catenin signaling, either by expression of Dkk1 or by tissue-specific deletion of beta-catenin, results in disruption of distal airway development and expansion of proximal airways. Wnt/beta-catenin functions upstream of BMP4, FGF signaling, and N-myc. Moreover, we show that beta-catenin and LEF/TCF activate the promoters of BMP4 and N-myc. Thus, Wnt/beta-catenin signaling is a critical upstream regulator of proximal-distal patterning in the lung, in part, through regulation of N-myc, BMP4, and FGF signaling.     

HTII-280, a Biomarker Specific to the Apical Plasma Membrane of Human Lung Alveolar Type II Cells

The pulmonary alveolar epithelium is composed of two morphologically distinct cell types, type I (TI) and type II (TII) cells. Alveolar TII cells synthesize, secrete, and recycle surfactant components; contain ion transporters; and secrete immune effector molecules. In response to alveolar injury, TII cells have the capacity to act as progenitor cells, proliferating and transdifferentiating into TI cells. Although various proteins are associated with TII cells, a plasma membrane marker specific to human TII cells that would be useful for identification in tissue and for isolating this cell type has not been described previously. We devised a strategy to produce a monoclonal antibody (MAb) specific to the apical surface of human TII cells and developed an MAb that appears to be specific for human TII cells. The antibody recognizes a 280- to 300-kDa protein, HTII-280, which has the biochemical characteristics of an integral membrane protein. HTII-280 is detected by week 11 of gestation and is developmentally regulated. HTII-280 is useful for isolating human TII cells with purities and viabilities >95%. HTII-280 is likely to be a useful morphological and biochemical marker of human TII cells that may help to advance our understanding of various lung pathological conditions, including the origin and development of various lung tumors. (J Histochem Cytochem 58:891–901, 2010)     

Further study on the role of HSP70 on Ca2+ homeostasis in rat ventricular myocytes subjected to simulated ischemia

We hypothesized that activation of heat shock protein 70 (HSP70) by preconditioning, which is known to confer delayed cardioprotection, attenuates the impaired handling of Ca²⁺ at multiple sites. To test the hypothesis, we determined how the ryanodine receptor (RyR), sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA), and Na⁺/Ca²⁺ exchanger (NCX) handled Ca²⁺ in rat ventricular myocytes preconditioned with a -opioid receptor agonist, U50488H (UP), followed by blockade of HSP70 with a selective antisense oligonucleotide and subsequently subjected to simulated ischemia. We determined the following: 1) the Ca²⁺ transients induced by electrical stimulation and caffeine, which provide the overall picture of Ca²⁺ homeostasis; 2) expression of RyR, SERCA, and NCX; and 3) Ca²⁺ fluxes via NCX by the use of ⁴⁵Ca²⁺ in the rat ventricular myocyte. We found that UP increased the activity of RyR, SERCA, and NCX and the expression of RyR and SERCA. These effects led to increases in the release of Ca²⁺ from the sarcoplasmic reticulum via RyR and in the removal of Ca²⁺ from the cytoplasm by reuptake of Ca²⁺ to the SR via SERCA and by extrusion of Ca²⁺ out of the cell via NCX. UP also reduced mitochondrial Ca²⁺ accumulation. All of the effects of UP were either abolished or significantly attenuated by blockade of HSP70 synthesis with a selective antisense oligonucleotide. The results are evidence that activation of HSP70 by preconditioning improves the ischemia-impaired Ca²⁺ homeostasis at multiple sites in the heart, which may be responsible, at least partly, for attenuated Ca²⁺ overload, improved recovery in contractile function, and cardioprotection. intracellular Ca²⁺, -opioid receptor; Na⁺/Ca²⁺ exchanger; ryanodine receptor; sarco(endo)plasmic reticulum Ca²⁺-ATPase     

Effects of glutamate on microbial efficiency and metabolism in continuous culture of ruminal contents and on performance of mid-lactation dairy cows

Three experiments were conducted to determine (1) the dose of glutamate needed to alter fermentation and nitrogen (N) partitioning in a continuous culture system, (2) the effect of supplemental glutamate in diets varying in rumen-undegradable protein on fermentation and N partitioning in a continuous culture system, and (3) the effect of dietary supplemental glutamate on the lactational performance of mid-lactation dairy cows, total tract nutrient digestibility, and ruminal microbial N synthesis. In experiment 1, the equivalent of 0, 40, or 80 g of supplemental glutamate per cow per day was added to a basal diet. The dietary treatments were evaluated in a continuous culture system. Glutamate decreased protein digestion and microbial growth while increasing non-ammonia, non-microbial N. Within the doses tested, the equivalent of 80 g glutamate per cow per day most effectively increased non-ammonia, non-microbial N. In experiment 2, dietary treatments consisted of diets formulated to have low rumen-undegradable protein (LRUP; 62 g/kg DM), low rumen-undegradable protein plus the equivalent of 80 g glutamate per cow per day (LRUP + G), and high rumen-undegradable protein [HRUP; 68 g/kg dry matter (DM)]. The dietary treatments were evaluated in a continuous culture system. When added to a diet low in rumen-undegradable protein, glutamate tended to decrease DM and organic matter (OM) digestibility, decreased total volatile fatty acid (VFA) production, increased fermenter pH, increased feed N converted to microbial N, and had no effect on microbial N production. The LRUP + G diet was similar to the HRUP diet and different from the LRUP diet in feed N converted to microbial N and ammonia N concentration. In experiment 3, 40 Holstein cows were utilized in a crossover study to test the effects of two dietary treatments: 0 or 80 g of supplemental glutamate per cow per day. The addition of glutamate to the diet of lactating dairy cows did not improve lactational performance or nutrient digestibility. Based on the results from these in vitro and in vivo experiments, the addition of glutamate to lactating cow diets is not recommended.