Induction of Simian Virus 40 Antigen in BSC1 Transformed Cells

Heating to 45 C induced in virus-free clones of simian virus 40 (SV40) transformed BSC₁ cells the synthesis of SV40 viral antigen, as evidenced by immunofluorescence. Up to 3.8% of the cells exhibited viral antigen 72 hr after heating to 45 C for 30 min. Depletion of arginine from the medium of the heated cells enhanced and increased the percentage of cells synthesizing viral antigen to 11%. Cytosine arabinoside completely inhibited the induction of the viral antigen. No infectious virus was recovered from the cells in which synthesis of viral antigen was induced. However, small amounts of infectious SV40 virus were rescued from the BSC₁ transformed cells by fusion with rabbit kidney cells or by treatment with mitomycin C.     

Niche Partition of Bacteriovorax Operational Taxonomic Units Along Salinity and Temporal Gradients in the Chesapeake Bay Reveals Distinct Estuarine Strains

The predatory Bacteriovorax are Gram-negative bacteria ubiquitous in saltwater systems that prey upon other Gram-negative bacteria in a similar manner to the related genus Bdellovibrio. Among the phylogenetically defined clusters of Bacteriovorax, cluster V has only been isolated from estuaries suggesting that it may be a distinct estuarine phylotype. To assess this hypothesis, the spatial and temporal distribution of cluster V and other Bacteriovorax phylogenetic assemblages along the salinity gradient of Chesapeake Bay were determined. Cluster V was expected to be found in significantly greater numbers in low to moderate salinity waters compared to high salinity areas. The analyses of water and sediment samples from sites in the bay revealed cluster V to be present at the lower salinity and not high salinity sites, consistent with it being an estuarine phylotype. Cluster IV had a similar distribution pattern and may also be specifically adapted to estuaries. While the distribution of clusters V and IV were similar for salinity, they were distinct on temperature gradients, being found in cooler and in warmer temperatures, respectively. The differentiation of phylotype populations along the salinity and temporal gradients in Chesapeake Bay revealed distinct niches inhabited by different phylotypes of Bacteriovorax and unique estuarine phylotypes.     

Utilization of oriented peptide libraries to identify substrate motifs selected by ATM

The ataxia telangiectasia mutated (ATM) gene encodes a serine/threonine protein kinase that plays a critical role in genomic surveillance and development. Here, we use a peptide library approach to define the in vitro substrate specificity of ATM kinase activity. The peptide library analysis identified an optimal sequence with a central core motif of LSQE that is preferentially phosphorylated by ATM. The contributions of the amino acids surrounding serine in the LSQE motif were assessed by utilizing specific peptide libraries or individual peptide substrates. All amino acids comprising the LSQE sequence were critical for maximum peptide substrate suitability for ATM. The DNA-dependent protein kinase (DNA-PK), a Ser/Thr kinase related to ATM and important in DNA repair, was compared with ATM in terms of peptide substrate selectivity. DNA-PK was found to be unique in its preference of neighboring amino acids to the phosphorylated serine. Peptide library analyses defined a preferred amino acid motif for ATM that permits clear distinctions between ATM and DNA-PK kinase activity. Data base searches using the library-derived ATM sequence identified previously characterized substrates of ATM, as well as novel candidate substrate targets that may function downstream in ATM-directed signaling pathways.     

The effect of the lunar cycle on fecal cortisol metabolite levels and foraging ecology of nocturnally and diurnally active spiny mice

We studied stress hormones and foraging of nocturnal Acomys cahirinus and diurnal A. russatus in field populations as well as in two field enclosures populated by both species and two field enclosures with individuals of A. russatus alone. When alone, A. russatus individuals become also nocturnally active. We asked whether nocturnally active A. russatus will respond to moon phase and whether this response will be obtained also in diurnally active individuals. We studied giving-up densities (GUDs) in artificial foraging patches and fecal cortisol metabolite levels. Both species exhibited elevated fecal cortisol metabolite levels and foraged to higher GUDs in full moon nights; thus A. russatus retains physiological response and behavioral patterns that correlate with full moon conditions, as can be expected in nocturnal rodents, in spite of its diurnal activity. The endocrinological and behavioral response of this diurnal species to moon phase reflects its evolutionary heritage.     

Body size of insular carnivores: little support for the island rule

Large mammals are thought to evolve to be smaller on islands, whereas small mammals grow larger. A negative correlation between relative size of island individuals and body mass is termed the "island rule." Several mechanisms--mainly competitive release, resource limitation, dispersal ability, and lighter predation pressure on islands, as well as a general physiological advantage of modal size--have been advanced to explain this pattern. We measured skulls and teeth of terrestrial members of the order Carnivora in order to analyze patterns of body size evolution between insular populations and their near mainland conspecifics. No correlations were found between the size ratios of insular/mainland carnivore species and body mass. Only little support for the island rule is found when individual populations rather than species are considered. Our data are at odds with those advanced in support of theories of optimal body size. Carnivore size is subjected to a host of selective pressures that do not vary uniformly from place to place. Mass alone cannot account for the patterns in body size of insular carnivores.     

Present–absent: a chronicle of the dinoflagellate Peridinium gatunense from Lake Kinneret

A long-term record dating back to the 1960s indicates that Peridinium gatunense, an armored dinoflagellate, dominated the phytoplankton of Lake Kinneret (Sea of Galilee, Israel) until the mid-1990s, with a relatively stable spring bloom. However, since 1996, these blooms became irregular, failing to develop in 10 out of the past 16 years. During the later period, a significant correlation (R ² = 0.605, P = 0.013) was found between annual peak P. gatunense biomass and riverine inflow volume. In-lake surveys showed that patches of high P. gatunense densities were associated with water enriched with fresher inflowing Jordan River water. Supplementing laboratory cultures of P. gatunense with Hula Valley water stimulated its growth relative to un-enriched controls. A likely explanation to the recent irregular blooms of this dinoflagellate is a hydrological modification that was made in the catchment in the mid-1990s, preventing Hula Valley water from reaching Lake Kinneret in most years—except for exceptionally wet years. We propose that until the mid-1990s, the Jordan River water enriched Lake Kinneret with a growth factor (a microelement and/or organic compound) originating in the Hula Valley, which in recent years has arrived in sufficient quantities to support a bloom only in high-rainfall years.     

Enhanced Erythrocyte Adhesiveness/Aggregation in Obesity Corresponds to Low‐Grade Inflammation

Objective: Previous studies have suggested that obesity enhances the inflammatory response, producing macromolecules involved in the induction and/or maintenance of increased erythrocyte aggregation. The objectives of this study were to evaluate the correlation between inflammation markers, erythrocyte adhesiveness/aggregation, and the degree of obesity and to assess phosphatidylserine expression on erythrocyte surface membrane of obese vs. nonobese individuals. Research Methods and Procedures: Erythrocyte adhesiveness/aggregation in the peripheral venous blood was evaluated by using a new biomarker, phosphatidylserine expression was assessed by means of flow cytometry, and markers of inflammation were measured in 65 subjects: 30 obese [body mass index (BMI) = 41 ± 7.7 kg/m²] and 35 nonobese (BMI = 24 ± 2.7 kg/m²) individuals. Pearson correlations and Student's t test were performed. Results: A highly significant difference was noted in the degree of erythrocyte adhesiveness/aggregation and markers of inflammation between the study groups. BMI correlated with erythrocyte adhesiveness/aggregation (r = 0.42, p = 0.001), erythrocyte sedimentation rate (r = 0.42, p = 0.001), high‐sensitive C‐reactive protein (r = 0.55, p < 10^?4), fibrinogen (r = 0.37, p = 0.004), and white blood cell count (r = 0.45, p < 10^?4). The degree of erythrocyte adhesiveness/aggregation correlated with erythrocyte sedimentation rate (r = 0.5, p < 10^?4), high‐sensitive C‐reactive protein (r = 0.56, p < 10^?4), fibrinogen (r = 0.54, p < 10^?4), and white blood cell count (r = 0.32, p = 0.01). Discussion: Our results suggest that obesity‐related erythrocyte adhesiveness/aggregation is probably mediated through increased concentrations of adhesive macromolecules in the circulation and not necessarily through hyperlipidemia or phosphatidylserine exposure on erythrocyte's membrane.     

The COP9 signalosome is vital for timely repair of DNA double-strand breaks

The DNA damage response is vigorously activated by DNA double-strand breaks (DSBs). The chief mobilizer of the DSB response is the ATM protein kinase. We discovered that the COP9 signalosome (CSN) is a crucial player in the DSB response and an ATM target. CSN is a protein complex that regulates the activity of cullin ring ubiquitin ligase (CRL) complexes by removing the ubiquitin-like protein, NEDD8, from their cullin scaffold. We find that the CSN is physically recruited to DSB sites in a neddylation-dependent manner, and is required for timely repair of DSBs, affecting the balance between the two major DSB repair pathways—nonhomologous end-joining and homologous recombination repair (HRR). The CSN is essential for the processivity of deep end-resection—the initial step in HRR. Cullin 4a (CUL4A) is recruited to DSB sites in a CSN- and neddylation-dependent manner, suggesting that CSN partners with CRL4 in this pathway. Furthermore, we found that ATM-mediated phosphorylation of CSN subunit 3 on S410 is critical for proper DSB repair, and that loss of this phosphorylation site alone is sufficient to cause a DDR deficiency phenotype in the mouse. This novel branch of the DSB response thus significantly affects genome stability.