Immobilization induces a very rapid increase in osteoclast activity

We studied in a randomized, strictly controlled cross-over design, the effects of 6 days 6 degrees head-down tilt bed rest (HDT) in eight male healthy subjects in our metabolic ward. The study consisted of two periods (phases) of 11 days each in order to allow for the test subjects being their own controls. Both study phases were identical with respect to environmental conditions, study protocol and diet. Two days before arriving in the metabolic ward the subjects started with a diet. The diet was continued in the metabolic ward. The metabolic ward period (1l days) was divided into three parts: 4 ambulatory days, 6 days either HDT or control and 1 recovery day. Continuous urine collection started on the first day in the metabolic ward to analyze calcium excretion and bone resorption markers. On the 2nd ambulatory day in the metabolic ward and on the 5th day in HDT or control blood was drawn to analyze serum calcium, parathyroid hormone, and bone formation markers. Urinary calcium excretion was, as early as the first day in immobilization, increased (p<0.01). CTX- and NTX-excretion stayed unchanged in the first 24 h in HDT compared to the control. But already on the 2nd day of immobilization, both bone resorption markers significantly increased. We conclude from these results--pronounced rise of bone resorption markers--that already 24 h of immobilization induce a significant rise in osteoclast activity in healthy subjects. Thus, it appears possible to use short-term bed rest studies as a first step for the development of countermeasures to immobilization.     

Experimental support for an immunological approach to the search for life on other planets

We propose a three-phase approach to test for evidence of life in extraterrestrial samples. The approach capitalizes on the flexibility, sensitivity, and specificity of antibody-antigen interactions. Data are presented to support the first phase, in which various extraction protocols are compared for efficiency, and in which a preliminary suite of antibodies are tested against various antigens. The antigens and antibodies were chosen on the basis of criteria designed to optimize the detection of extraterrestrial biomarkers unique to living or once-living organisms.     

Recurrent isolation of hydrogen peroxide-resistant spores of Bacillus pumilus from a spacecraft assembly facility

While the microbial diversity of a spacecraft assembly facility at the Jet Propulsion Laboratory (Pasadena, CA) was being monitored, H2O2-resistant bacterial strains were repeatedly isolated from various surface locations. H2O2 is a possible sterilant for spacecraft hardware because it is a low-temperature process and compatible with various modern-day spacecraft materials, electronics, and components. Both conventional biochemical testing and molecular analyses identified these strains as Bacillus pumilus. This Bacillus species was found in both unclassified (entrance floors, anteroom, and air-lock) and classified (floors, cabinet tops, and air) locations. Both vegetative cells and spores of several B. pumilus isolates were exposed to 5% liquid H2O2 for 60 min. Spores of each strain exhibited higher resistance than their respective vegetative cells to liquid H2O2. Results indicate that the H2O2 resistance observed in both vegetative cells and spores is strain-specific, as certain B. pumilus strains were two to three times more resistant than a standard Bacillus subtilis dosimetry strain. An example of this trend was observed when the type strain of B. pumilus, ATCC 7061, proved sensitive, whereas several environmental strains exhibited varying degrees of resistance, to H2O2. Repeated isolation of H2O2-resistant strains of B. pumilus in a clean-room is a concern because their persistence might potentially compromise life-detection missions, which have very strict cleanliness and sterility requirements for spacecraft hardware.     

COSAC onboard Rosetta: a bioastronomy experiment for the short-period comet 67P/Churyumov-Gerasimenko

The COSAC (Cometary Sampling and Composition Experiment) onboard the Rosetta mission is a combined gas chromatograph (GC)-mass spectrometer (MS). It is situated on Philae, the lander of the mission, which is intended to land on the nucleus of comet 67P/Churyumov- Gerasimenko. The purpose of the experiment is to analyze the volatile fraction of soil samples retrieved by a drill. For investigation, the samples will be pyrolysed, and the emanating gases fed into a GC, into an MS, or the combination of both. In the first part of this paper, the bioastronomical relevance of such measurements is outlined. In the second part the details of the hardware and its performance are described.     

考古,寻找进化的雕塑——对话罗伯特·巴克（下）

斯：你不仅是知名的古生物学家，而且是一位有造诣的艺术家。你是怎样学习绘画的？ 巴：任何人都能作画。绘画的能力不在你的指尖，而在你的眼睛里。如果你能看见结构，如果你能看见形式，你就能把它记录下来。我上解剖学课，就把学生带到动物园，对他们说：“画那头美洲豹。”“我不会画。”他们说。“你们能看见那头美洲豹吗？”“能看见。”“肘部是直的还是弯的？“‘噢，弯的”“踝关节是弯的吗？”“是的。”“它比狗的踝关节还要弯吧？”“不错。”“把它画下来。”要是你懂得怎样看结构，能在你的头脑中大概画下一系列东西，你就能把它画到纸上。     

考古，寻找进化的雕塑——对话罗伯特·巴克（上）

达林·R．斯蒂尔（以下简称“斯”）：你刚上四年级的时候就决定研究恐龙。是受到什么影响吗？     

具有无源控制空腔时正激波/湍流附面层干扰的数值模拟

采用雷诺平均N-S方程和B/L代数湍流模型计算了具有无源控制空腔时正激波/湍流附面层干扰流场。计算与实验结果的比较表明,本文方法可较准确地预测激波结构、激波与附面层干扰区流动基本特征及波后流动分离状态、激波位置、波前马赫数等参数。      

Microbially induced iron precipitation associated with a neutrophilic spring at Borra Caves, Vishakhapatnam, India

The present investigation uncovers various pieces of evidence for the possible biologically induced mineralization in iron mats associated with a pH-neutral spring in the Borra caves, Vishakhapatnam, India. Electron microscopy [scanning electron microscopy (SEM) and transmission electron microscopy (TEM)] demonstrated large numbers of (i) hollow tubes (diameter ～1?μm) resembling sheaths of the iron-oxidizing bacteria Leptothrix, (ii) thin (diameter <1?μm) solid fibers of uncertain origin, (iii) nanoscale subspherical to irregularly shaped particles encrusting tubes and fibers, and (iv) aggregates of broken and partially disintegrated sheaths, fibers, and particles embedded in extracellular polymeric substances (EPS) occasionally including microbial cells. X-ray microanalyses by energy dispersive spectroscopy (EDS) revealed that the mat accumulated largely Fe but also smaller amounts of Si and traces of P and Ca. Particles rich in Si and Al (possibly kaolinite) and Ca (carbonate) were also observed. High-resolution TEM/EDS of unstained ultrathin sections suggests that microbial sheaths were highly mineralized by amorphous to cryptocrystalline Fe-rich phases and less frequently by other fine-grained and fibrous authigenic claylike minerals. Total number of microorganisms in the iron mats was 5.8×10(5) cells, g sed(-1) (wet weight). Analysis of the 16S rRNA gene diversity revealed microorganisms assigned to eight different phyla [Proteobacteria (62%), Chloroflexi (8%), Bacteroidetes (7%), Planctomycetes (1%), Actinobacteria (5%), Acidobacteria (6%), Nitrospira (1%), Firmicutes (5%)]. Within the Proteobacteria, Betaproteobacteria was the predominant class, which accounted for 28% of the sequences. Within this class some obvious similarities between the obtained sequences and sequences from other cave systems could be seen, especially sequences affiliated with Leptothrix, Siderooxidans, Crenothrix, Comamonadaceae, Dechloromonas, and many uncultured Betaproteobacteria. Four (4%) of the sequences could not be assigned to phylum level but were affiliating with the candidate division TM7 (2%), candidate division OP11 (1%), and candidate division WWE3 (1%). The results allow us to infer a possible relationship of microbial sheaths, EPS, and the iron precipitates to microbial community diversity in the Borra cave springs. Understanding biogenic iron oxides in caves has important astrobiological applications as it provides a potential tool for the detection of extraterrestrial life.     

Abundance and diversity of microbial inhabitants in European spacecraft-associated clean rooms

The determination of the microbial load of a spacecraft en route to interesting extraterrestrial environments is mandatory and currently based on the culturable, heat-shock-surviving portion of microbial contaminants. Our study compared these classical bioburden measurements as required by NASA's and ESA's guidelines for the microbial examination of flight hardware, with molecular analysis methods (16S rRNA gene cloning and quantitative PCR) to further develop our understanding of the diversity and abundance of the microbial communities of spacecraft-associated clean rooms. Three samplings of the Herschel Space Observatory and its surrounding clean rooms were performed in two different European facilities. Molecular analyses detected a broad diversity of microbes typically found in the human microbiome with three bacterial genera (Staphylococcus, Propionibacterium, and Brevundimonas) common to all three locations. Bioburden measurements revealed a low, but heterogeneous, abundance of spore-forming and other heat-resistant microorganisms. Total cell numbers estimated by quantitative real-time PCR were typically 3 orders of magnitude greater than those determined by viable counts, which indicates a tendency for traditional methods to underestimate the extent of clean room bioburden. Furthermore, the molecular methods allowed the detection of a much broader diversity than traditional culture-based methods.     

The PROCESS experiment: an astrochemistry laboratory for solid and gaseous organic samples in low-earth orbit

The PROCESS (PRebiotic Organic ChEmistry on the Space Station) experiment was part of the EXPOSE-E payload outside the European Columbus module of the International Space Station from February 2008 to August 2009. During this interval, organic samples were exposed to space conditions to simulate their evolution in various astrophysical environments. The samples used represent organic species related to the evolution of organic matter on the small bodies of the Solar System (carbonaceous asteroids and comets), the photolysis of methane in the atmosphere of Titan, and the search for organic matter at the surface of Mars. This paper describes the hardware developed for this experiment as well as the results for the glycine solid-phase samples and the gas-phase samples that were used with regard to the atmosphere of Titan. Lessons learned from this experiment are also presented for future low-Earth orbit astrochemistry investigations.