Chemistry of the uropygial gland secretion of Hume’s ground jay Pseudopodoces humilis and its taxonomic implications

Humes ground jay (Pseudopodoces humilis), a species living in the high altitude steppes of the Qinghai-Tibet-Plateau (China), was traditionally thought to be a ground jay related to the genus Podoces (Corvidae). Recently, however, based on three independent datasets (comparative osteology, nuclear and mitochondrial DNA sequences), this species was discovered to be a member of the Paridae. Here, we reinvestigate the systematic position of Pseudopodoces humilis using the chemical composition of uropygial gland secretions, which have previously been shown to be phylogenetically informative in birds, including Corvidae and Paridae. We found strong similarities in the fatty acid composition of uropygial gland secretions between Pseudopodoces humilis and parids, but clear differences from corvids. This result supports the parid affinites of Pseudopodoces, but stands in contrast to behavioural and vocal characteristics which are clearly more similar to corvids than to parids.Communicated by A.J. Helbig     

Post-pandemic seroprevalence of pandemic influenza A (H1N1) 2009 infection (swine flu) among children <18 years in Germany

Background

We determined antibodies to the pandemic influenza A (H1N1) 2009 virus in children to assess: the incidence of (H1N1) 2009 infections in the 2009/2010 season in Germany, the proportion of subclinical infections and to compare titers in vaccinated and infected children.

Methodology/Principal Findings

Eight pediatric hospitals distributed over Germany prospectively provided sera from in- or outpatients aged 1 to 17 years from April 1^st to July 31^st 2010. Vaccination history, recall of infections and sociodemographic factors were ascertained. Antibody titers were measured with a sensitive and specific in-house hemagglutination inhibition test (HIT) and compared to age-matched sera collected during 6 months before the onset of the pandemic in Germany. We analyzed 1420 post-pandemic and 300 pre-pandemic sera. Among unvaccinated children aged 1–4 and 5–17 years the prevalence of HI titers (≥1∶10) was 27.1% (95% CI: 23.5–31.3) and 53.5% (95% CI: 50.9–56.2) compared to 1.7% and 5.5%, respectively, for pre-pandemic sera, accounting for a serologically determined incidence of influenza A (H1N1) 2009 during the season 2009/2010 of 25,4% (95% CI : 19.3–30.5) in children aged 1–4 years and 48.0% (95% CI: 42.6–52.0) in 5–17 year old children. Of children with HI titers ≥1∶10, 25.5% (95% CI: 22.5–28.8) reported no history of any infectious disease since June 2009. Among vaccinated children, 92% (95%-CI: 87.0–96.6) of the 5–17 year old but only 47.8% (95%-CI: 33.5–66.5) of the 1–4 year old children exhibited HI titers against influenza A virus (H1N1) 2009.

Conclusion

Serologically determined incidence of influenza A (H1N1) 2009 infections in children indicates high infection rates with older children (5–17 years) infected twice as often as younger children. In about a quarter of the children with HI titers after the season 2009/2010 subclinical infections must be assumed. Low HI titers in young children after vaccination with the AS03_B-adjuvanted split virion vaccine need further scrutiny.     

The chloroplastic protein import machinery contains a Rieske-type iron-sulfur cluster and a mononuclear iron-binding protein.

Transport of precursor proteins across the chloroplastic envelope membranes requires the interaction of protein translocons localized in both the outer and inner envelope membranes. Analysis by blue native gel electrophoresis revealed that the translocon of the inner envelope membranes consisted of at least six proteins with molecular weights of 36, 45, 52, 60, 100 and 110 kDa, respectively. Tic110 and ClpC, identified as components of the protein import apparatus of the inner envelope membrane, were prominent constituents of this complex. The amino acid sequence of the 52 kDa protein, deduced from the cDNA, contains a predicted Rieske-type iron-sulfur cluster and a mononuclear iron-binding site. Diethylpyrocarbonate, a Rieske-type protein-modifying reagent, inhibits the translocation of precursor protein across the inner envelope membrane, whereas binding of the precursor to the outer envelope membrane is still possible. In another independent experimental approach, the 52 kDa protein could be co-purified with a trapped precursor protein in association with the chloroplast protein translocon subunits Toc86, Toc75, Toc34 and Tic110. Together, these results strongly suggest that the 52 kDa protein, named Tic55 due to its calculated molecular weight, is a member of the chloroplastic inner envelope protein translocon.     

Acquisition and assimilation of gaseous ammonia as revealed by intracellular pH changes in leaves of higher plants

Atmospheric ammonia (NH₃) from various anthropogenic sources has become a serious problem for natural vegetation. Ammonia not only causes changes in plant nitrogen metabolism, but also affects the acid-base balance of plants. Using the pH-sensitive fluorescent dyes pyranine and esculin, cytosolic and vacuolar pH changes were measured in leaves of C₃ and C₄ plants exposed for brief periods to concentrations of NH₃ in air ranging from 1.33 to 8.29 mol NH₃ · mol^-1 gas (0.94–5.86 mg · m^-3). After a lag phase, uptake of NH₃ from air at a rate of 200 nmol NH₃ · m ^{- 2} leaf area · s^{- 1} into leaves of Zea mays L. increased pyranine fluorescence indicating cytosolic alkalinisation. The increase was much larger in the dark than in the light. In illuminated leaves of the C₃ plant Pelargonium zonale L. and the C₄ plants Z. mays and Amaranthus caudatus L., NH₃-dependent cytosolic alkalinisation was particularly pronounced when CO₂ was supplied at very low levels (16 or 20 mol CO₂ · mol^{- 1} gas, containing 210 mmol O₂ · mol^{- 1} gas). An increase in esculin fluorescence, which was smaller than that of pyranine, was indicative of trapping of some of the NH₃ in the vacuoles of leaves of Spinacia oleracea L. and Z. mays. Photosynthesis and transpiration remained unchanged during exposure of illuminated leaves to NH₃, yielding an influx of 200 nmol NH₃ · m^-2 leaf area · s^-1 for up to 30 min, the longest exposure time used. Both CO₂ and O₂ influenced the extent of cytosolic alkalinisation. At 500 mol CO₂ · mol^-1 gas the cytosolic alkalinisation was suppressed more than at 16 or 20 mol CO₂ · mol^-1 gas. The suppressing effect of CO₂ on the NH₃induced alkalinisation was larger in illuminated leaves of the C₄ plants Z. mays and A. caudatus than in leaves of the C₃ plant P. zonale. A reduction of the O₂ concentration from 210 to 10 mmol O₂ · mol ^-1 gas, which inhibits photorespiration, increased the NH₃induced cytosolic alkalinisation in C₃ plants. Suppression by CO₂ or O₂ of the alkaline pH shift caused by the dissolution and protonation of NH₃ in queous leaf compartments, and possibly by the production of organic compounds synthesised from atmospheric NH₃, indicates that NH₃ which enters leaves is rapidly assimilated if photosynthesis or photorespiration provide nitrogen acceptor molecules.This work was supported by the Biotechnology and Biological Sciences Research Council and the Deutsche Forschungsgemein-schaft within the framework of the research of Sonderforschun-gsbreich 251 of the University of Würzburg. We are grateful to Dr. B. Wollenweber (The Royal Veterinary and Agricultural University, Denmark) for discussions.     

Evidence for the concentration of F-actin and myosin in synapses and in the plasmalemmal zone of axons

Fluorescent staining with phalloidin, a specific probe for F-actin, and antibodies to non-muscle myosin from thymus was used to localize actin and myosin in brain neurons of the rat. Phalloidin and anti-myosin displayed a preferential affinity for synaptic formations in the cerebellum, the brain stem, the spinal cord and the retina. The conclusion that F-actin and myosin are concentrated in synaptic terminals was further established by simultaneous staining of isolated rat brain synaptosomes with phalloidin and anti-thymus myosin as well as by the demonstration of a selective affinity of anti-thymus myosin for a 200 000-Mr protein band in gel electrophoretograms of synaptic fractions. Apart from synaptic areas, phalloidin and anti-thymus myosin reacted also, albeit rather weakly, with a narrow circumferential layer located in the area of the plasma membrane of virtually all axons in the white matter and the spinal roots. The spatial coexistence of myosin and actin in brain synapses and axons is of particular interest in view of various dynamic functions that have been proposed for axonal and synaptic actin.     

Microbial transformation of ethylpyridines

Pyridine and its derivatives have been found as pollutants in the environment. Although alkylpyridines constitute the largest class of pyridines contaminating the environment, little information is available concerning the fate and transformation of these compounds. In this investigation ethylpyridines have been used as model compounds for investigating the biodegradability of alkylpyridines. A mixed culture of ethylpyridine-degrading microorganisms was obtained from a soil that had been exposed to a variety of pyridine derivatives for several decades. The enrichment culture was able to degrade 2-, 3-, and 4-ethylpyridine (100 mg/L) at 28° C and pH 7 within two weeks under aerobic conditions. The degradation rate was greatest for 2-ethylpyridine and least for 3-ethylpyridine. Transformation of ethylpyridines was dependent on substrate concentration, pH, and incubation temperature. Studies on the metabolic pathway of 4-ethylpyridine revealed two products; these chemicals were identified by MS and NMR analyses as 4-ethyl-2(1H)-pyridone and 4-ethyl-2-piperidone. 6-Ethyl-2(1H)-pyridone was determined to be a product of 2-ethylpyridine degradation. These results indicate that the transformation mechanism of ethylpyridines involves hydroxylation and reduction of the aromatic ring before ring cleavage.     

Acclimation of photosynthesis to lightflecks in tomato leaves: interaction with progressive shading in a growing canopy

Plants in natural environments are often exposed to fluctuations in light intensity, and leaf‐level acclimation to light may be affected by those fluctuations. Concurrently, leaves acclimated to a given light climate can become progressively shaded as new leaves emerge and grow above them. Acclimation to shade alters characteristics such as photosynthetic capacity. To investigate the interaction of fluctuating light and progressive shading, we exposed three‐week old tomato (Solanum lycopersicum ) plants to either lightflecks or constant light intensities. Lightflecks of 20 s length and 1000 μmol m^?2 s^?1 peak intensity were applied every 5 min for 16 h per day, for 3 weeks. Lightfleck and constant light treatments received identical daily light sums (15.2 mol m^?2 day^?1). Photosynthesis was monitored in leaves 2 and 4 (counting from the bottom) during canopy development throughout the experiment. Several dynamic and steady‐state characteristics of photosynthesis became enhanced by fluctuating light when leaves were partially shaded by the upper canopy, but much less so when they were fully exposed to lightflecks. This was the case for CO₂‐saturated photosynthesis rates in leaves 2 and 4 growing under lightflecks 14 days into the treatment period. Also, leaf 2 of plants in the lightfleck treatment showed significantly faster rates of photosynthetic induction when exposed to a stepwise change in light intensity on day 15. As the plants grew larger and these leaves became increasingly shaded, acclimation of leaf‐level photosynthesis to lightflecks disappeared. These results highlight continuous acclimation of leaf photosynthesis to changing light conditions inside developing canopies.     

Microbial transformation of heterocyclic molecules in deep subsurface sediments

Recently attempts have been made to establish the presence and to determine the metabolic versatility of microorganisms in the terrestrial deep subsurface at the Savannah River Plant, Aiken, SC, USA. Sediment samples obtained at 20 different depths of up to 526 m were examined to determine carbon mineralization under aerobic, sulfate-reducing, and methanogenic conditions. The evolution of¹⁴CO₂ from radiolabelled glucose was observed under aerobic conditions in all sediments, whereas pyridine was transformed in 50% of the 20 sediments and indole was metabolized in 85% of the sediments. Glucose mineralization in certain sediments was comparable to that in the surface environment. Sulfate was reduced in only five sediments, and two were carbon limited. Methane production was detected in ten sediments amended with formate only after long-term incubations. The transformation of indole and pyridine was only rarely observed under sulfate-reducing conditions and was never detected in methanogenic incubations. This study provides information concerning the metabolic capability of both aerobic and anaerobic microorganisms in the deep subsurface and may prove useful in determining the feasibility of microbial decontamination of such environments.     

Stejneger's beaked whale strandings in Alaska, 1995–2020

Presented here is the first comprehensive and updated compilation of history, distribution, and findings of Stejneger's beaked whales (Mesoplodon stejnegeri) in Alaska. Stejneger's beaked whales are a poorly understood, elusive, deep-diving cetacean species found in the North Pacific Ocean. Since Stejneger's beaked whale strandings data in Alaska through 1994 were last published, 35 additional strandings have been documented. Twenty-seven animals stranded in the Aleutian Islands, seven stranded in Southcentral Alaska, and one animal stranded on St. Lawrence Island. Twenty-two carcasses were necropsied, but only four were fresh. Seventeen of the 22 died during mass stranding events and cause of death could not be definitively determined. Barotrauma was suspected in three cases and infectious disease possibly complicated by barotrauma occurred in two cases. We documented an expansion of strandings into the northern Bering Sea, characterized a sex bias, examined stomach contents that included macroplastic, and identified parasites not previously associated with Stejneger's beaked whales. Also included are data on the largest known mass stranding of Stejneger's beaked whales, which occurred on Adak Island in 2018. The history, distribution, and findings presented here are central to further our understanding of this species.