Effects of anaerobiosis on carbohydrate oxidation by roots of Pisum sativum

The aim of this work was to discover the effects of anaerobiosis on the breakdown of sugars by the apical 6 mm of the roots of 5-day-old seedlings of Pisum sativum. Estimates of the maximum catalytic activities of alcohol dehydrogenase, lactate dehydrogenase, phosphoenolpyruvate carboxylase and NADP-specific malic enzyme showed them to be comparable to that of phosphofructokinase. Metabolism of sucrose-[U-¹⁴C] by excised apices was restricted by anoxia mainly to conversion to ethanol, CO₂ alanine and glycolytic intermediates. Measurements of metabolites over a period of 240 min after transfer of excised apices to nitrogen showed a marked and continual accumulation of ethanol, a smaller continual accumulation of alanine, a small initial rise in lactate and no detectable accumulation of malate or pyruvate. The rates of CO₂ production, of accumulation of ethanol and alanine, and of the labelling of these compounds by sucrose-[¹⁴C] declined markedly during the first 240 min of anaerobiosis. The conclusion is that under anaerobic conditions carbohydrate metabolism in the pea root apex is largely restricted to alcoholic fermentation, and, to a lesser degree, to alanine production.     

Polar bear (Ursus maritimus) cub mortality at a den site in northern Alaska

In March 2009, we documented the death of one member of a triplet polar bear (Ursus maritimus) litter at its den site in the southern Beaufort Sea (SBS) of Alaska. We used a self-contained video camera unit to document activity between den emergence and departure. All three cubs showed low activity levels relative to other cubs observed, and one died within one week of den emergence. Necropsy confirmed that the dead cub had a low body weight and was malnourished. Capture later confirmed that the two surviving cubs were also undersized. Polar bear cub survival is influenced by many factors including litter size and sea ice conditions. Triplet litters are often smaller and suffer higher mortality rates than singletons and twins. This cub was not only a triplet but also born following 2 years of record minimum sea ice extent, both of which may have played a role in this cub’s demise.     

Using dot blot with immunochemical detection to evaluate global changes in SUMO-2/3 conjugation

Here we describe a non-invasive method for rapid and highly reproducible genotyping of transgenic mammals with ubiquitous expression of fluorophore reporters. Hair samples from transgenic mice and pigs with systemic expression of the fluorophore reporter Venus were analyzed with a fluorescence microscope in few minutes. The hair samples can be preserved for long-term storage at ambient temperature conditions. This non-invasive method is useful for genotyping of transgenic large animals and contributes to animal welfare by reducing stress and discomfort of the animals during sample collection.     

Does history repeat itself? Wavelets and the phylodynamics of influenza A

Unprecedented global surveillance of viruses will result in massive sequence data sets that require new statistical methods. These data sets press the limits of Bayesian phylogenetics as the high-dimensional parameters that comprise a phylogenetic tree increase the already sizable computational burden of these techniques. This burden often results in partitioning the data set, for example, by gene, and inferring the evolutionary dynamics of each partition independently, a compromise that results in stratified analyses that depend only on data within a given partition. However, parameter estimates inferred from these stratified models are likely strongly correlated, considering they rely on data from a single data set. To overcome this shortfall, we exploit the existing Monte Carlo realizations from stratified Bayesian analyses to efficiently estimate a nonparametric hierarchical wavelet-based model and learn about the time-varying parameters of effective population size that reflect levels of genetic diversity across all partitions simultaneously. Our methods are applied to complete genome influenza A sequences that span 13 years. We find that broad peaks and trends, as opposed to seasonal spikes, in the effective population size history distinguish individual segments from the complete genome. We also address hypotheses regarding intersegment dynamics within a formal statistical framework that accounts for correlation between segment-specific parameters.     

Pathogenicity and proteomic signatures of autoantibodies to Ro and La

Ro/SSA and La/SSB comprise a linked set of autoantigens that are clinically important members of the extractable nuclear antigen family and key translational biomarkers for lupus and primary Sj?gren's syndrome. Autoantibodies directed against the Ro60 and La polypeptide components of the Ro/La ribonucleoprotein complex, and the structurally unrelated Ro52 protein, mediate tissue damage in the neonatal lupus syndrome, a model of passively acquired autoimmunity in humans in which the most serious manifestation is congenital heart block (CHB). Recent studies have concentrated on two distinct pathogenic mechanisms by which maternal anti-Ro/La autoantibodies can cause CHB: by forming immune complexes with apoptotic cells in developing fetal heart; and/or by acting as functional autoantibodies that cross-react with and inhibit calcium channels. Although the precise role of the individual autoantibodies is yet to be settled, maternal anti-Ro60 and anti-Ro52 remain the most likely culprits. This article will discuss the molecular pathways that culminate in the development of CHB, including the recent discovery of β2 glycoprotein I as a protective factor, and present a proteomic approach based on direct mass spectrometric sequencing, which may give a more representative snapshot of the idiotype repertoire of these autoantibodies than genomic-based technologies.     

Role of inducible nitric oxide synthase in mitochondrial depolarization and graft injury after transplantation of fatty livers

This study investigated the role of inducible nitric oxide synthase (iNOS) in failure of ethanol-induced fatty liver grafts. Rat livers were explanted 20 h after gavaging with ethanol (5 g/kg) and storing in UW solution for 24h before implantation. Hepatic oil red O staining-positive areas increased from ～2 to ～33% after ethanol treatment, indicating steatosis. iNOS expression increased ～8-fold after transplantation of lean grafts (LG) and 25-fold in fatty grafts (FG). Alanine aminotransferase release, total bilirubin, hepatic necrosis, TUNEL-positive cells, and cleaved caspase-3 were higher in FG than LG. A specific iNOS inhibitor 1400W (5 μM in the cold-storage solution) blunted these alterations by >42% and increased survival of fatty grafts from 25 to 88%. Serum nitrite/nitrate and hepatic nitrotyrosine adducts increased to a greater extent after transplantation of FG than LG, indicating reactive nitrogen species (RNS) overproduction. Phospho-c-Jun and phospho-c-Jun N-terminal kinase-1/2 (JNK1/2) were higher in FG than in LG, indicating more JNK activation in fatty grafts. RNS formation and JNK activation were blunted by 1400W. Mitochondrial polarization and cell death were visualized by intravital multiphoton microscopy of rhodamine 123 and propidium iodide, respectively. After implantation, viable cells with depolarized mitochondria were 3-fold higher in FG than in LG and 1400W decreased mitochondrial depolarization in FG to the levels of LG. Taken together, iNOS is upregulated after transplantation of FG, leading to excessive RNS formation, JNK activation, mitochondrial dysfunction, and severe graft injury. The iNOS inhibitor 1400W could be an effective therapy for primary nonfunction of fatty liver grafts.     

Towards characterization of DNA structure under physiological conditions in vivo at the single-molecule level using single-pair FRET

Fluorescence resonance energy transfer (FRET) under in vivo conditions is a well-established technique for the evaluation of populations of protein bound/unbound nucleic acid (NA) molecules or NA hybridization kinetics. However, in vivo FRET has not been applied to in vivo quantitative conformational analysis of NA thus far. Here we explored parameters critical for characterization of NA structure using single-pair (sp)FRET in the complex cellular environment of a living Escherichia coli cell. Our measurements showed that the fluorophore properties in the cellular environment differed from those acquired under in vitro conditions. The precision for the interprobe distance determination from FRET efficiency values acquired in vivo was found lower (～31%) compared to that acquired in diluted buffers (13%). Our numerical simulations suggest that despite its low precision, the in-cell FRET measurements can be successfully applied to discriminate among various structural models. The main advantage of the in-cell spFRET setup presented here over other established techniques allowing conformational analysis in vivo is that it allows investigation of NA structure in various cell types and in a native cellular environment, which is not disturbed by either introduced bulk NA or by the use of chemical transfectants.     

Exploiting antitumor immunity to overcome relapse and improve remission duration

Cancer survivors often relapse due to evolving drug-resistant clones and repopulating tumor stem cells. Our preclinical study demonstrated that terminal cancer patient's lymphocytes can be converted from tolerant bystanders in vivo into effective cytotoxic T-lymphocytes in vitro killing patient's own tumor cells containing drug-resistant clones and tumor stem cells. We designed a clinical trial combining peginterferon α-2b with imatinib for treatment of stage III/IV gastrointestinal stromal tumor (GIST) with the rational that peginterferon α-2b serves as danger signals to promote antitumor immunity while imatinib's effective tumor killing undermines tumor-induced tolerance and supply tumor-specific antigens in vivo without leukopenia, thus allowing for proper dendritic cell and cytotoxic T-lymphocyte differentiation toward Th1 response. Interim analysis of eight patients demonstrated significant induction of IFN-γ-producing-CD8(+), -CD4(+), -NK cell, and IFN-γ-producing-tumor-infiltrating-lymphocytes, signifying significant Th1 response and NK cell activation. After a median follow-up of 3.6 years, complete response (CR) + partial response (PR) = 100%, overall survival = 100%, one patient died of unrelated illness while in remission, six of seven evaluable patients are either in continuing PR/CR (5 patients) or have progression-free survival (PFS, 1 patient) exceeding the upper limit of the 95% confidence level of the genotype-specific-PFS of the phase III imatinib-monotherapy (CALGB150105/SWOGS0033), demonstrating highly promising clinical outcomes. The current trial is closed in preparation for a larger future trial. We conclude that combination of targeted therapy and immunotherapy is safe and induced significant Th1 response and NK cell activation and demonstrated highly promising clinical efficacy in GIST, thus warranting development in other tumor types.     

Vascular function in rats with adenine-induced chronic renal failure

The aim of the present study was to characterize the function of resistance arteries, and the aorta, in rats with adenine-induced chronic renal failure (A-CRF). Sprague-Dawley rats were randomized to chow with or without adenine supplementation. After 6-10 wk, mesenteric arteries and thoracic aortas were analyzed ex vivo by wire myography. Plasma creatinine concentrations were elevated twofold at 2 wk, and eight-fold at the time of death in A-CRF animals. Ambulatory systolic and diastolic blood pressures measured by radiotelemetry were significantly elevated in A-CRF animals from week 3 and onward. At death, A-CRF animals had anemia, hyperphosphatemia, hyperparathyroidism, and elevated plasma levels of asymmetric dimethylarginine and oxidative stress markers. There were no significant differences between groups in the sensitivity, or maximal response, to ACh, sodium nitroprusside (SNP), norepinephrine, or phenylephrine in either mesenteric arteries or aortas. However, in A-CRF animals, the rate of aortic relaxation was significantly reduced following washout of KCl (both in intact and endothelium-denuded aorta) and in response to ACh and SNP. Also the rate of contraction in response to KCl was significantly reduced in A-CRF animals both in mesenteric arteries and aortas. The media of A-CRF aortas was thickened and showed focal areas of fragmented elastic lamellae and disorganized smooth muscle cells. No vascular calcifications could be detected. These results indicate that severe renal failure for a duration of less than 10 wk in this model primarily affects the aorta and mainly slows the rate of relaxation.