Ectoparasites of northern fulmars Fulmarus glacialis (Procellariiformes: Procellariidae) from the Canadian Arctic

We studied the prevalence and intensity of infestation of ectoparasites on northern fulmars (Fulmarus glacialis L.) from a breeding colony in Arctic Canada in June–August 2003. No fleas or ticks were found on any fulmars, but three species of chewing lice (Phthiraptera) were recorded: Ischnocera: Perineus nigrolimbatus (Giebel 1874), Ischnocera: Saemundssonia occidentalis (Kellogg 1896), and Amblycera: Ancistrona vagelli (Fabricius 1787). Non-breeding birds had a higher prevalence of lice than breeding birds, and prevalence varied markedly among louse species. Our study is an important baseline for the occurrence of ectoparasites on northern fulmars in the high Arctic, a region undergoing extensive environmental change due to global warming, and an area where parasites are expected to extend ranges or increase in prevalence under changing annual temperature regimes.     

Vegetation control effects on untreated wood,crude cellulose and holocellulose δ<Superscript>13</Superscript>C of early and latewood in 3- to 5-year-old rings of Douglas-fir

The stable carbon (C) composition of tree rings expressed as δ¹³C, is a measure of intrinsic water-use efficiency and can indicate the occurrence of past water shortages for tree growth. We examined δ¹³C in 3- to 5-year-old rings of Douglas-fir (Pseudotsuga menziesii (Mirb) Franco) trees to elucidate if decreased water supply or uptake was a critical factor in the observed growth reduction of trees competing with understory herb and shrub vegetation compared to those growing without competition. We hypothesized that there would be no differences in δ¹³C of earlywood in trees growing in plots with competing vegetation and those in plots receiving complete vegetation control during 5 years because earlywood formed early in the growing season when soil water was ample. We also hypothesized that δ¹³C in latewood which was formed during the later half of the growing season when precipitation was low, would be greater (less negative) in trees in plots without vegetation control. We then separated early and latewood from rings for three consecutive years and analyzed their δ¹³C composition. No significant differences in earlywood δ¹³C in years 3–5 were observed for trees in the two vegetation control treatments. δ¹³C of untreated latewood separated from wood cores was greater in 4- and 5-year-old rings of trees growing with competing vegetation compared to trees growing without vegetation competition (i.e., −25.5 vs. −26.3‰ for year 4, and −26.1 vs. −26.8‰ for year 5). Results suggest that water shortages occurred in Douglas-fir trees on this coastal Washington site in the latewood-forming portion of the growing season of years 4 and 5 in the no-vegetation control treatment. We also compared δ¹³C from untreated wood, crude cellulose extracted with the Diglyme–HCl method, and holocellulose extracted with toluene–ethanol to see if the extraction method would increase the sensitivity of the analysis. δ¹³C values from the two extraction methods were highly correlated with those from untreated samples (r ² = 0.97, 0.98, respectively). Therefore, using untreated wood would be as effective as using crude cellulose or holocellulose to investigate δ¹³C patterns in young Douglas-fir.     

Differential expression of 2′∶3′-cyclic nucleotide 3′-phosphodiesterase in cultured central,peripheral, and extraneural cells

The relative levels of the central nervous system myelin marker enzyme 2:3-cyclic nucleotide 3-phosphodiesterase (EC 3.1.4.37, CNPase) were determined in neuroblastoma, astrocyte, oligodendrocyte and Schwann cell cultures and in freshly isolated human lymphocytes and platelets. The highest specific activities were associated with the cells that elaborate myelin membrane in the central and peripheral nervous system, oligodendrocytes and Schwann cells, respectively. Antiserum to bovine CNPase recognized both CNP1 and CNP2 in CNS myelin and human oligodendroglioma. In addition, a 53,000 dalton protein was evident on autoradiographs of immunoblotted PNS myelin and human oligodendroglioma proteins. Cultured rat oligodendrocyte, C₆ and mouse NA neuroblastoma CNPase appear to share common determinants with the corresponding normal rat CNS enzyme.     

Size and growth characteristics of dispersing voles,Microtus townsendii

Summary In a peak population of Microtus townsendii, adults and subadults dispersed during the spring decline, and subadults and juveniles dispersed during the summer and fall. Voles born in the spring dispersed before the start of the next year's breeding season, whereas fall-born voles dispersed during the next year's breeding season. Voles under 50 g, when they dispersed, had faster growth rates than similar-sized residents, but voles over 59 g, when they dispersed, had slower growth rates than similar-sized residents. Dispersing and resident voles 50–59 g had no consistent trend in growth rates.     

Three heat shock proteins are essential for rotifer thermotolerance

Heat shock proteins (HSPs) are important molecules in the stress response of organisms from prokaryotes to mammals, and thus may be useful biomarkers for environmental stress. Here we characterize the functional roles of genes belonging to four distinct families of HSPs (hsp40, hsp60, hsp70, and hsp90) in the monogonont rotifer Brachionus manjavacas. Because B. manjavacas inhabits ponds of varying thermal regimes, including ephemeral ponds that may experience temperature fluctuations, HSP-mediated thermotolerance likely is important to its survival and adaptation. Using interference RNA (RNAi), we provide the first conclusive evidence that HSPs are required for rotifer survival following heat stress. Effective RNAi-mediated suppression of all hsp genes except hsp90 was verified via quantitative PCR. Hsp40, hsp60, and hsp70 are required for rotifer thermotolerance (P < 0.05); however, our data do not indicate hsp90 is essential. Quantitative PCR further revealed immediate up-regulation of hsp40 mRNA following heat stress. Additionally, we demonstrated expression of hsp40 mRNA in multiple tissues using fluorescent in situ hybridization. Our characterization of mRNA expression and functional roles for four distinct hsp genes provides a baseline for molecular-level comparisons of the stress response of rotifers with other taxonomic groups, and the technique for in-depth studies of the role of specific genes in rotifer stress responses. Considering the potential for ambient temperatures to impact species survival, competitive interactions, and body size of individuals, thermotolerance may be an important influence on zooplankton community structure.     

A hypothalamic activator of calmodulin-dependent enzymes is thymosin β4 (1–39)

A new class of stimulators of basal activity of a number of calmodulin-dependent enzymes have been previously isolated from bovine hypothalamus. One of these stimulators, denoted as C₃, has been purified to homogeneity by reverse phase HPLC and tentatively identified as thymosin ₄ (1–39) by mass spectrometry and Edman microsequence analysis. The stimulating effect of C₃ on rabbit skeletal muscle MLCK basal activity was compared with that of thymosin ₁ and thymosin ₄ (16–38). Evidence is presented that all the indicated compounds are Ca²⁺-independent high-affinity MLCK stimulators. The potency of the stimulators in activating the enzyme was: C₃>₄>(CaM+Ca²⁺>₁.This revised version was published online in June 2005 with corrections to the author name Gurvits.     

Time-Dependent Increase in Protein Phosphorylation Following One-Trial Enhancement in Hermissenda

Abstract: One-trial conditioning of the nudibranch mollusk Hermissenda produces short- and long-term changes in excitability (enhancement) of identified sensory neurons. To investigate the biochemical mechanisms underlying this example of plasticity, we have examined changes in protein phosphorylation at different times following the in vitro conditioning trial. Changes in the incorporation of ³²PO₄ into proteins were determined using two-dimensional polyacrylamide gel electrophoresis, autoradiography, and densitometry. Conditioning resulted in increases in levels of several phosphoproteins, five of which, ranging in apparent molecular mass from 22 to 55 kDa, were chosen for analysis. The increased phosphorylation of the 46- and 55-kDa phosphoproteins detected 2 h postconditioning was significantly greater than the level of phosphorylation detected in an unpaired control group, indicating that long-term enhancement is pairing specific. Statistically significant increases in phosphorylation as compared with the control group that received only light were detected immediately after conditioning (5 min) for the 55-, 46-, and 22-kDa phosphoproteins, at 1 h for the 55- and 46-kDa phosphoproteins, and at 2 h for the 55-, 46-, and 22-kDa phosphoproteins. The 46- and 55-kDa phosphoproteins are putative structural proteins, and the 22-kDa phosphoprotein is proposed to be a protein kinase C substrate previously identified in Hermissenda following multitrial classical conditioning. Time-dependent increases in protein phosphorylation may contribute to the induction and maintenance of different memory stages expressed in sensory neurons after one-trial conditioning.     

Terminal Restriction Fragment Length Polymorphism Data Analysis for Quantitative Comparison of Microbial Communities

Terminal restriction fragment length polymorphism (T-RFLP) is a culture-independent method of obtaining a genetic fingerprint of the composition of a microbial community. Comparisons of the utility of different methods of (i) including peaks, (ii) computing the difference (or distance) between profiles, and (iii) performing statistical analysis were made by using replicated profiles of eubacterial communities. These samples included soil collected from three regions of the United States, soil fractions derived from three agronomic field treatments, soil samples taken from within one meter of each other in an alfalfa field, and replicate laboratory bioreactors. Cluster analysis by Ward's method and by the unweighted-pair group method using arithmetic averages (UPGMA) were compared. Ward's method was more effective at differentiating major groups within sets of profiles; UPGMA had a slightly reduced error rate in clustering of replicate profiles and was more sensitive to outliers. Most replicate profiles were clustered together when relative peak height or Hellinger-transformed peak height was used, in contrast to raw peak height. Redundancy analysis was more effective than cluster analysis at detecting differences between similar samples. Redundancy analysis using Hellinger distance was more sensitive than that using Euclidean distance between relative peak height profiles. Analysis of Jaccard distance between profiles, which considers only the presence or absence of a terminal restriction fragment, was the most sensitive in redundancy analysis, and was equally sensitive in cluster analysis, if all profiles had cumulative peak heights greater than 10,000 fluorescence units. It is concluded that T-RFLP is a sensitive method of differentiating between microbial communities when the optimal statistical method is used for the situation at hand. It is recommended that hypothesis testing be performed by redundancy analysis of Hellinger-transformed data and that exploratory data analysis be performed by cluster analysis using Ward's method to find natural groups or by UPGMA to identify potential outliers. Analyses can also be based on Jaccard distance if all profiles have cumulative peak heights greater than 10,000 fluorescence units.     

The chromatin-remodeling enzyme BRG1 plays an essential role in primitive erythropoiesis and vascular development

ATP-dependent chromatin-remodeling complexes contribute to the proper temporal and spatial patterns of gene expression in mammalian embryos and therefore play important roles in a number of developmental processes. SWI/SNF-like chromatin-remodeling complexes use one of two different ATPases as their catalytic subunit: brahma (BRM, also known as SMARCA2) and brahma-related gene 1 (BRG1, also known as SMARCA4). We have conditionally deleted a floxed Brg1 allele with a Tie2-Cre transgene, which is expressed in developing hematopoietic and endothelial cells. Brg1(fl/fl):Tie2-Cre(+) embryos die at midgestation from anemia, as mutant primitive erythrocytes fail to transcribe embryonic alpha- and beta-globins, and subsequently undergo apoptosis. Additionally, vascular remodeling of the extraembryonic yolk sac is abnormal in Brg1(fl/fl):Tie2-Cre(+) embryos. Importantly, Brm deficiency does not exacerbate the erythropoietic or vascular abnormalities found in Brg1(fl/fl):Tie2-Cre(+) embryos, implying that Brg1-containing SWI/SNF-like complexes, rather than Brm-containing complexes, play a crucial role in primitive erythropoiesis and in early vascular development.     

The effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold

The purpose of this investigation was to determine the effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold (PWCFT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption (VO2max). Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of VO2max (range, 72-80%) for the purpose of glycogen depletion. For the next 3 days, the subjects were fed a 10.5 MJ.day-1 low carbohydrate diet which consisted of 7.5% carbohydrates, 22.0% protein and 70.5% fat. The subjects then performed an incremental cycle ergometer test to the onset of fatigue or PWCFT, which was estimated from integrated electromyographic voltages of the vastus lateralis muscle. For the next 3 days the subjects were fed a 10.5 MJ high carbohydrate diet which consisted of 72.2% carbohydrates, 12.4% protein and 15.4% fats for the purpose of glycogen supercompensation. The subjects then performed a second PWCFT test. A paired t-test indicated that there was no significant (p greater than 0.05) difference between the means of the PWCFT values (depletion 246 W, SD 30; supercompensation 265 W, SD 28) and they were highly correlated at r = 0.884. The results of this investigation suggested that the methods commonly used to affect glycogen depletion or supercompensation had no effect on PWCFT.