Band-related leg injuries in an Australian passerine and their possible causes

ABSTRACT.   We examined the extent and causes of band-related leg injuries in an Australian passerine, the Bell Miner ( Manorina melanophrys ). Eight percent of banded birds exhibited leg injuries, and most were birds with two plastic color bands on a tarsus. Leg injuries typically followed the accumulation of shed tarsal scales under the color bands. Color bands used on Bell Miners were tighter on the tarsus than the metal band and also tighter than the color bands used on Superb Fairy-wrens ( Malurus cyaneus ), a commonly banded species with no reported leg injuries. The tendency for scales to accumulate under two plastic color bands appeared to be influenced by the diameter of a band relative to the size of a bird's tarsus (with looser bands less likely to cause accumulation) and the material used to make the band (with smoother surfaces less likely to cause accumulation). Celluloid color bands had rougher internal surfaces than either Darvic or metal bands. In addition, both celluloid and Darvic color bands generated static electricity capable of attracting tarsal scales. Scales that accumulated under bands provided an environment where potentially harmful fungi became established, potentially contributing to the severity of leg injuries. Our results suggest that, when selecting an appropriate band size for a bird, the diameter of the tarsus at its midpoint should occupy only between 60% and 65% of the internal diameter of the band and, when possible, a single, bicolored, anodized aluminum alloy band should be used instead of multiple plastic color bands.     

Differences between homologous alleles of olfactory receptor genes require the Polycomb Group protein Eed

A number of mammalian genes are expressed from only one of the two homologous chromosomes, selected at random in each cell. These include genes subject to X-inactivation, olfactory receptor (OR) genes, and several classes of immune system genes. The means by which monoallelic expression is established are only beginning to be understood. Using a cytological assay, we show that the two homologous alleles of autosomal random monoallelic loci differ from each other in embryonic stem (ES) cells, before establishment of monoallelic expression. The Polycomb Group gene Eed is required to establish this distinctive behavior. In addition, we found that when Eed mutant ES cells are differentiated, they fail to establish asynchronous replication timing at OR loci. These results suggest a common mechanism for random monoallelic expression on autosomes and the X chromosome, and implicate Eed in establishing differences between homologous OR loci before and after differentiation.     

Laboratory experiments on the effects of variable suspended sediment concentrations on the ecophysiology of the porcelain crab Petrolisthes elongatus (Milne Edwards, 1837)

The porcelain crab Petrolisthes elongatus is a particulate suspension feeding species common to coastal areas of New Zealand (NZ). Consistent with the responses of other suspension feeding species, it is likely to be negatively influenced by elevated suspended sediment concentrations. Laboratory experiments were conducted to quantify the effect of temperature (12 °C, 15 °C and 18 °C) and suspended sediment concentration (total particulate matter (TPM): low < 100 mg L^− 1; medium 100-1000 mg L^− 1; high > 1000 mg L^− 1) on the clearance rate (CR in L h^− 1), oxygen uptake rate (VO₂ in mL h⁻¹), net absorption efficiency (AE), and net energy budget (NEB in J h^− 1) of P. elongatus across a range of sizes. Variation in CR and AE was independent of temperature and of body size, but were significantly different (P < 0.05) at low and medium suspended sediment concentrations compared with high suspended sediment concentrations. CR responded in a non-linear manner to changes in TPM, increasing with TPM up to a maximum value at medium-low concentrations (approximately 250 mg L^− 1) and then decreasing thereafter. CR had almost completely shut down at TPM concentrations of > 1000 mg L^− 1 and at particulate organic matter (POM) concentrations of > 250 mg L^− 1. AE was zero at approximate TPM and POM values of 1200 mg L^− 1 and 300 mg L^− 1, respectively. VO₂ was positively correlated with body size and with temperature, but was independent of TPM. NEB values for P. elongatus were low (approx 110 J g^− 1 h^− 1) at low sediment concentrations, were high (approx 320 J g^− 1 h^− 1) at medium sediment concentrations, and were negative (approx − 114 J g^− 1 h^− 1) at high sediment concentrations. These findings indicate that P. elongatus is likely to be food-limited at sediment concentrations of < 100 mg L^− 1, and severely negatively affected at sediment concentrations of > 1000 mg L^− 1, at least for the duration of such events which may persist for 2-3 days in coastal environments where this crab occurs.     

N-Glycosylation regulates endothelial lipase-mediated phospholipid hydrolysis in apoE- and apoA-I-containing high density lipoproteins

Endothelial lipase (EL) is a member of the triglyceride lipase gene family with high phospholipase and low triacylglycerol lipase activities and a distinct preference for hydrolyzing phospholipids in HDL. EL has five potential N-glycosylation sites, four of which are glycosylated. The aim of this study was to determine how glycosylation affects the phospholipase activity of EL in physiologically relevant substrates. Site-directed mutants of EL were generated by replacing asparagine (N) 62, 118, 375, and 473 with alanine (A). These glycan-deficient mutants were used to investigate the kinetics of phospholipid hydrolysis in fully characterized preparations of spherical reconstituted high density lipoprotein (rHDL) containing apolipoprotein E2 (apoE2) [(E2)rHDL], apoE3 [(E3)rHDL], apoE4 [(E4)rHDL], or apoA-I [(A-I)rHDL] as the sole apolipoprotein. Wild-type EL hydrolyzed the phospholipids in (A-I)rHDL, (E2)rHDL, (E3)rHDL, and (E4)rHDL to similar extents. The phospholipase activities of EL N118A, EL N375A, and EL N473A were significantly diminished relative to that of wild-type EL, with the greatest reduction being apparent for (E3)rHDL. The phospholipase activity of EL N62A was increased up to 6-fold relative to that of wild-type EL, with the greatest enhancement of activity being observed for (E2)rHDL. These data show that individual N-linked glycans have unique and important effects on the phospholipase activity and substrate specificity of EL.     

Tryptophan Biosynthesis in Stramenopiles: Eukaryotic Winners in the Diatom Complex Chloroplast

Tryptophan is an essential amino acid that, in eukaryotes, is synthesized either in the plastids of photoautotrophs or in the cytosol of fungi and oomycetes. Here we present an in silico analysis of the tryptophan biosynthetic pathway in stramenopiles, based on analysis of the genomes of the oomycetes Phytophthora sojae and P. ramorum and the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum. Although the complete pathway is putatively located in the complex chloroplast of diatoms, only one of the involved enzymes, indole-3-glycerol phosphate synthase (InGPS), displays a possible cyanobacterial origin. On the other hand, in P. tricornutum this gene is fused with the cyanobacteria-derived hypothetical protein COG4398. Anthranilate synthase is also fused in diatoms. This fusion gene is almost certainly of bacterial origin, although the particular source of the gene cannot be resolved. All other diatom enzymes originate from the nucleus of the primary host (red alga) or secondary host (ancestor of chromalveolates). The entire pathway is of eukaryotic origin and cytosolic localization in oomycetes; however, one of the enzymes, anthranilate phosphoribosyl transferase, was likely transferred to the oomycete nucleus from the red algal nucleus during secondary endosymbiosis. This suggests possible retention of the complex plastid in the ancestor of stramenopiles and later loss of this organelle in oomycetes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Quantitative DNA hybridization in solution using magnetic/luminescent core-shell nanoparticles

Nanoscale magnetic/luminescent core-shell particles were used for DNA quantification in a hybridization-in-solution approach. We demonstrated a rapid, simple, and non-polymerase chain reaction-based DNA hybridization-in-solution assay for quantifying bacteria capable of biodegrading methyl tertiary-butyl ether. Fe3O4/Eu:Gd2O3 core-shell nanoparticles synthesized by spray pyrolysis were biofunctionalized with NeutrAvidin. Following immobilization of a biotinylated probe DNA on the particles' surfaces via passive adsorption, target DNA labeled with fluorescein isothiocyanate was hybridized with probe DNA. The hybridized DNA complex was separated from solution with a magnet, while nonhybridized DNA remained in solution. The normalized fluorescence (fluorescein isothiocyanate/nanoparticles) measured with a spectrofluorometer indicated a linear quantification (R(2)=0.98) of the target bacterial 16 S rDNA. The rate of hybridization increased concurrently with the target DNA concentration. In addition, this approach differentiated between the signal outputs from perfectly complementary target and two-base mismatched target DNA in a range of concentrations, showing the specificity of the assay and the possibility for environmental applications.     

Involving undergraduates in the annotation and analysis of global gene expression studies: creation of a maize shoot apical meristem expression database

Through a multi-university and interdisciplinary project we have involved undergraduate biology and computer science research students in the functional annotation of maize genes and the analysis of their microarray expression patterns. We have created a database to house the results of our functional annotation of >4400 genes identified as being differentially regulated in the maize shoot apical meristem (SAM). This database is located at http://sam.truman.edu and is now available for public use. The undergraduate students involved in constructing this unique SAM database received hands-on training in an intellectually challenging environment, which has prepared them for graduate and professional careers in biological sciences. We describe our experiences with this project as a model for effective research-based teaching of undergraduate biology and computer science students, as well as for a rich professional development experience for faculty at predominantly undergraduate institutions.     

Survivorship,growth and reproduction of the non-native <Emphasis Type="Italic">Caprella mutica</Emphasis> Schurin, 1935 (Crustacea: Amphipoda)

Caprella mutica Schurin is an epifaunal amphipod crustacean which originates in north-east Asia and has spread throughout the world, yet very little is known about fundamental aspects of this species biology. This paper examined the survivorship of C. mutica reared under laboratory conditions at 13–14 °C, 14 h light: 10 h dark photoperiod and fed commercial salmon feed, the diatom Cylindrotheca fusiformis Reumann and Lewin, the macroalgae, Fucus vesiculosus L. and given no additional feed. In addition, growth, maturation and reproduction of C. mutica fed C. fusiformis were assessed. No significant difference in survivorship of C. mutica was observed for the diet types over the experimental period. C. mutica was able to survive for upto 20 days without additional food. Average survival time of males and females fed the diatom, C. fusiformis was 68.8 d (range = 62–73 d) and 82.0 d (range = 76–92 d). Juvenile C. mutica emerged from the brood pouch at a body length of 1.33 mm and moulted at 5.0–11.0 day intervals. Males exhibited faster growth rates than females after Instar VII. Females produced their first brood at Instar VII, 24–26 days post-hatching and with an average body length of 8.5 mm. Each female had an average of two broods sequentially and these were released at 20.2 day intervals. Brood size for a single female increased from 11.3 (±9.9) hatchlings at Instar VII to 25.5 (±11.5) at Instar IX and the maximum number of hatchlings produced by a single female was 82. The results suggest that C. mutica exhibits a number of life-history traits that would potentially enable it to withstand global transportation and to rapidly become established in an introduced region, if environmental conditions are suitable.     

Catalase (KatA) and alkyl hydroperoxide reductase (AhpC) have compensatory roles in peroxide stress resistance and are required for survival, persistence, and nasal colonization in Staphylococcus aureus

Oxidative-stress resistance in Staphylococcus aureus is linked to metal ion homeostasis via several interacting regulators. In particular, PerR controls the expression of a regulon of genes, many of which encode antioxidants. Two PerR regulon members, ahpC (alkylhydroperoxide reductase) and katA (catalase), show compensatory regulation, with independent and linked functions. An ahpC mutation leads to increased H2O2 resistance due to greater katA expression via relief of PerR repression. Moreover, AhpC provides residual catalase activity present in a katA mutant. Mutation of both katA and ahpC leads to a severe growth defect under aerobic conditions in defined media (attributable to lack of catalase activity). This results in the inability to scavenge exogenous or endogenously produced H2O2, resulting in accumulation of H2O2 in the medium. This leads to DNA damage, the likely cause of the growth defect. Surprisingly, the katA ahpC mutant is not attenuated in two independent models of infection, which implies reduced oxygen availability during infection. In contrast, both AhpC and KatA are required for environmental persistence (desiccation) and nasal colonization. Thus, oxidative-stress resistance is an important factor in the ability of S. aureus to persist in the hospital environment and so contribute to the spread of human disease.