Properties and Characterization of the Host Bacterium of Bacteriophage PM2

A marine bacterium, which acts as host for bacteriophage PM2 isolated from the same environment, has been characterized as a Pseudomonas species. This Pseudomonas cannot be assigned to any of the subgeneric categories or "groups" described by Stanier, Palleroni, and Doudoroff. The psychrophilic and halophilic nature of the organism and its requirement for NaCl suggest an indigenous marine origin.     

Ultrastructure of Bacterial Cells Infected with Bacteriophage PM2, a Lipid-containing Bacterial Virus

The cytological pattern of infection of a host pseudomonad with PM2, a lipid-containing bacterial virus, was investigated by electron microscopy. Normal and infected cells frequently contain a myelin figure, which is found in the nucleoid region or at the periphery of the cell. The most striking finding in this investigation was that completed virions are found in the cell adjacent to or in association with the cytoplasmic membrane. This localization is precise; virions are not found elsewhere in infected cells. The completed virions occasionally appear to be attached to the cytoplasmic membrane. The virus contains a darkly staining core surrounded by a tripartite envelope of a thickness of approximately 70 A, which is identical to the thickness of the cytoplasmic membrane. Lysing cells appear to undergo extensive damage of the cytoplasmic membrane prior to rupture of the L layer of the cell wall.     

What controls variation in carbon use efficiency among Amazonian tropical forests?

Why do some forests produce biomass more efficiently than others? Variations in Carbon Use Efficiency (CUE: total Net Primary Production (NPP)/ Gross Primary Production (GPP)) may be due to changes in wood residence time (Biomass/NPP_wood), temperature, or soil nutrient status. We tested these hypotheses in 14, one ha plots across Amazonian and Andean forests where we measured most key components of net primary production (NPP: wood, fine roots, and leaves) and autotrophic respiration (R_a; wood, rhizosphere, and leaf respiration). We found that lower fertility sites were less efficient at producing biomass and had higher rhizosphere respiration, indicating increased carbon allocation to belowground components. We then compared wood respiration to wood growth and rhizosphere respiration to fine root growth and found that forests with residence times <40 yrs had significantly lower maintenance respiration for both wood and fine roots than forests with residence times >40 yrs. A comparison of rhizosphere respiration to fine root growth showed that rhizosphere growth respiration was significantly greater at low fertility sites. Overall, we found that Amazonian forests produce biomass less efficiently in stands with residence times >40 yrs and in stands with lower fertility, but changes to long‐term mean annual temperatures do not impact CUE.     

Oxidation of Ferrous Iron and Elemental Sulfur by Thiobacillus ferrooxidans

The oxidation of ferrous iron and elemental sulfur by Thiobacillus ferrooxidans that was absorbed and unabsorbed onto the surface of sulfur prills was studied. Unadsorbed sulfur-grown cells oxidized ferrous iron at a rate that was 3 to 7 times slower than that of ferrous iron-grown cells, but sulfur-grown cells were able to reach the oxidation rate of the ferrous iron-adapted cells after only 1.5 generations in a medium containing ferrous iron. Bacteria that were adsorbed to sulfur prills oxidized ferrous iron at a rate similar to that of unadsorbed sulfur-grown bacteria. They also showed the enhancement of ferrous iron oxidation activity in the presence of ferrous iron, even though sulfur continued to be available to the bacteria in this case. An increase in the level of rusticyanin together with the enhancement of the ferrous iron oxidation rate were observed in both sulfur-adsorbed and unadsorbed cells. On the other hand, sulfur oxidation by the adsorbed bacteria was not affected by the presence of ferrous iron in the medium. When bacteria that were adsorbed to sulfur prills were grown at a higher pH (ca. 2.5) in the presence of ferrous iron, they rapidly lost both ferrous iron and sulfur oxidation capacities and became inactive, apparently because of the deposition of a jarosite-like precipitate onto the surface to which they were attached.     

Epigenome Microarray Platform for Proteome-Wide Dissection of Chromatin-Signaling Networks

Knowledge of protein domains that function as the biological effectors for diverse post-translational modifications of histones is critical for understanding how nuclear and epigenetic programs are established. Indeed, mutations of chromatin effector domains found within several proteins are associated with multiple human pathologies, including cancer and immunodeficiency syndromes. To date, relatively few effector domains have been identified in comparison to the number of modifications present on histone and non-histone proteins. Here we describe the generation and application of human modified peptide microarrays as a platform for high-throughput discovery of chromatin effectors and for epitope-specificity analysis of antibodies commonly utilized in chromatin research. Screening with a library containing a majority of the Royal Family domains present in the human proteome led to the discovery of TDRD7, JMJ2C, and MPP8 as three new modified histone-binding proteins. Thus, we propose that peptide microarray methodologies are a powerful new tool for elucidating molecular interactions at chromatin.     

ACE16k: a 128x128 focal plane analog processor with digital I/O

This paper presents a new generation 128x128 Focal-Plane Analog Programmable Array Processor -FPAPAP, from a system level perspective. It has been manufactured in a 0.35 microm standard digital 1P-5M CMOS technology. It has been designed to achieve the high-speed and moderate-accuracy -8b- requirements of most real time -early-vision applications. External data interchange and control are completely digital. The chip contains close to four million transistors, 90% of them working in analog mode. It achieves peak computing values of 0.33TeraOPS while keeping power consumption at reasonable limits -82.5GOPS/W. Preliminary experimental results are also provided in the paper.     

Concentration of trace metals in excrements of two species of penguins from different locations of the Antarctic Peninsula

The presence of metals in Antarctica is becoming an issue that needs to be more investigated as human presence is increasing in the region, especially in the Antarctic Peninsula, where most of the polar animals, scientific bases and tourists are concentrated. Penguins are endemic species of Antarctica situated at the top of food web and are useful sentinels of pollution. To improve data of trace metal contamination in the Antarctic Peninsula region, concentrations of Cd, Pb, As, Cu and Zn in fresh excrement of penguins were determined by atomic absorption. Samples were collected in several locations during the 2011/2012 austral summer: eight sites (O’Higgins Station, Yankee Harbour, Mikkelsen Harbor, Danco Island, Gonzalez Videla Base, Yelcho Station and Brown Station) from gentoo penguin (Pygoscelis papua) colonies and four locations (Hydrurga Rocks, Cape Shirreff, Narebski Point and Kopaitic Island) from chinstrap penguin (Pygoscelis antarctica) colonies. Data showed that gentoo penguin colonies had higher levels of metals (μg g^?1 dw) like Pb, Cu and Zn at locations such as O’Higgins (2.89 for Pb, 199.95 for Cu and 379.99 for Zn) and Gonzalez Videla (2.74 for Pb and 222.51 for Cu). Levels of Cd in excreta of chinstrap penguins were higher at Narebski Point (3.13 μg g^?1). The levels of Pb, As, Cd, Cu and Zn were similar or even higher to those reported in excreta of the same species by previous studies at Antarctica. Data suggest that metals ingested by these two penguin species feeding in the sea end up in terrestrial ecosystems.