SELECTION FOR PRIME-NUMBER INTERVALS IN A NUMERICAL MODEL OF PERIODICAL CICADA EVOLUTION

Periodical cicadas are known for unusually long and prime-numbered life cycles (13 and 17 years) for insects. To explain the evolution of prime-numbered reproductive intervals (life cycles), the hybridization hypothesis claims that prime numbers greatly reduce the chance of hybridization with other life cycles. We investigate the hybridization hypothesis using a simulation model. This model is a deterministic, discrete population model with three parameters: larval survival per year, clutch size, and emergence success. Reproductive intervals from 10 years to 20 years compete for survival in the simulations. The model makes three key assumptions: a Mendelian genetic system, random mating among broods of different life-cycle lengths, and integer population sizes. Longer life cycles have larger clutch sizes but suffer higher total mortality than shorter life cycles. Our results show that (1) nonprime-numbered reproductive intervals disappear rapidly in comparison to the selection among the various prime-numbered life cycles, (2) the selection of prime-numbered intervals happens only when populations are at the verge of extinction, and (3) the 13- and 17-year prime phenotypes evolve under certain conditions of the model and may coexist. The hybridization hypothesis is discussed in light of other hypotheses for the evolution of periodical cicada life cycles.     

Design, synthesis, and biological activity of novel factor Xa inhibitors: improving metabolic stability by S1 and S4 ligand modification

Serine protease factor xa (fXa) inhibitor 1 showed good ex vivo anti-fXa activity upon oral administration in rats. However, it has been revealed that 1 had low metabolic stability against human liver microsomes. To improve the metabolic stability, we attempted to modify the S1 and S4 ligands of 1. These modifications resulted in compound 34b, which exhibited selective anti-fXa activity and excellent anti-coagulation activity.     

Role of PKR and Type I IFNs in Viral Control during Primary and Secondary Infection

Type I interferons (IFNs) are known to mediate viral control, and also promote survival and expansion of virus-specific CD8⁺ T cells. However, it is unclear whether signaling cascades involved in eliciting these diverse cellular effects are also distinct. One of the best-characterized anti-viral signaling mechanisms of Type I IFNs is mediated by the IFN-inducible dsRNA activated protein kinase, PKR. Here, we have investigated the role of PKR and Type I IFNs in regulating viral clearance and CD8⁺ T cell response during primary and secondary viral infections. Our studies demonstrate differential requirement for PKR, in viral control versus elicitation of CD8⁺ T cell responses during primary infection of mice with lymphocytic choriomeningitis virus (LCMV). PKR-deficient mice mounted potent CD8⁺ T cell responses, but failed to effectively control LCMV. The compromised LCMV control in the absence of PKR was multifactorial, and linked to less effective CD8⁺ T cell-mediated viral suppression, enhanced viral replication in cells, and lower steady state expression levels of IFN-responsive genes. Moreover, we show that despite normal expansion of memory CD8⁺ T cells and differentiation into effectors during a secondary response, effective clearance of LCMV but not vaccinia virus required PKR activity in infected cells. In the absence of Type I IFN signaling, secondary effector CD8⁺ T cells were ineffective in controlling both LCMV and vaccinia virus replication in vivo. These findings provide insight into cellular pathways of Type I IFN actions, and highlight the under-appreciated importance of innate immune mechanisms of viral control during secondary infections, despite the accelerated responses of memory CD8⁺ T cells. Additionally, the results presented here have furthered our understanding of the immune correlates of anti-viral protective immunity, which have implications in the rational design of vaccines.     

Relations Between Waist Circumference at Four Sites and Metabolic Risk Factors

The location of waist circumference (WC) measurement differs among diagnostic guidelines for the metabolic syndrome. The present study examined which of four WC measurements was associated most strongly with the clustering of metabolic risk factors in cross‐sectional study. The subjects comprised 1,140 Japanese employees, aged 20–70 years, who underwent health examinations in 2007 and 2008. WC was measured at (i) the narrowest part of the waist, (ii) midway between the lowest rib and the iliac crest, (iii) the umbilical level, and (iv) immediately above the iliac crest. A receiver operator characteristic (ROC) curve was used to assess the ability of each WC measurement to predict the presence of two or more other components of the metabolic syndrome, as defined by the National Cholesterol Education Program's Adult Treatment Panel III (NCEP‐ATP III) in 2005. Multiple risk factors were seen in 43.0% of the men and 12.9% of the women. The minimum and maximum WC measurements differed by 3.9 cm among the men and 12.6 cm among the women. The areas under the curve examining the ability of the four WC measurements to predict the clustering of multiple risk factors were similar. If the same WC cutoff value was applied, the prevalence of the metabolic syndrome changed considerably according to the site of WC measurement. The four WC measurements had similar screening abilities. Given the differences in the WC values according to the site of measurement, WC must be measured at the site specified by each diagnostic guideline.     

In vitro activity of 11 antibiotics against 74 anaerobes isolated from pediatric intra-abdominal infections

The in vitro activity of 11 antimicrobials was tested against 74 recent anaerobic isolates obtained from pretreatment cultures in pediatric patients with complicated intra-abdominal infections using the CLSI M11-A-6 agar dilution method. Carbapenems, beta-lactamase inhibitor combinations and metronidazole retained good activity, while all Bacteroides fragilis group species produced beta-lactamase and were penicillin resistant and 43% were either intermediately susceptible or resistant to clindamycin. Cefoxitin had moderate activity against B. fragilis but poor activity against Bacteroides thetaiotaomicron and other B. fragilis group isolates.     

Antifreeze glycoprotein levels in Antarctic notothenioid fishes inhabiting different thermal environments and the effect of warm acclimation

A quantification method was developed to determine the concentrations of the major antifreeze glycoprotein (AFGP) isoforms in the blood of Antarctic notothenioid fishes. Serum samples were precipitated with 2.5% TCA and the supernatant containing AFGPs were chromatographed on an HPLC size exclusion column and the concentrations of the major AFGP size classes were determined from the areas of the corresponding peaks in the elution profile. Eight species of Antarctic notothenioid fishes were examined and their blood AFGP concentrations varied from 5 to 35 mg/mL. All of these fishes synthesized both the large and small AFGPs, but maintained higher levels of small AFGPs than the large ones in their blood. The species inhabiting more severe water environments (lower temperature and presence of ice) had higher serum AFGP levels than those in milder environments. The cryopelagic Pagothenia borchgrevinki decreased their blood AFGP concentrations in response to warm acclimation, but to a much lower extent in comparison to the antifreeze-bearing fishes in the Northern Hemisphere. After being warm acclimated at +4 degrees C for 16 weeks, the serum concentrations of the small and large AFGPs were decreased by about 60% and 20%, respectively.     

Epidemiologic Typing of Methicillin-Resistant Staphylococcus aureus in Neonate Intensive Care Units Using Pulsed-Field Gel Electrophoresis

To elucidate the mode of dissemination of methicillin-resistant Staphylococcus aureus (MRSA) in neonate intensive care units (NICUs), a total of 223 isolates from 3 separate hospitals were investigated between 1994 and 1996 by a DNA fingerprinting technique with pulsed-field gel electrophoresis (PFGE). Exoprotein profiles of some strains were also examined using SDS-polyacrylamide gel-electrophoresis (SDS-PAGE) and the assessment of enzyme/toxin production such as coagulase, enterotoxin and TSST-1. Judging from the strain typing data from PFGE results and the epidemiological data, 2 different types of PFGE patterns (A and B) and their subtypes (A′, A″ and B′) were identified. The A type including A′ and A″ (comprising approximately 95% of the isolates) was markedly dominant. Only 5% of the isolates belonged to type B and subtype B′. On the other hand, MRSA isolated from adult patients admitted to the same hospital showed many different PFGE patterns. The results strongly suggested that some strain(s) with specific PFGE pattern(s) is prevalent in NICUs. Furthermore, isolates which expressed the same PFGE pattern did not always express the same SDS-PAGE pattern. There were some isolates with different abilities to produce coagulase, enterotoxin C and toxic-shock syndrome toxin (TSST)-1, and the abilities had no relation with a particular type of PFGE pattern. Therefore, a combination of PFGE analysis and biochemical analyses of coagulase, enterotoxin C and TSST-1 may provide us with more detailed information for the epidemiological study of MRSA in NICUs.     

The effect of fire on seed germination of campo rupestre species in the South American Cerrado

Plant Ecology - Fire is an important disturbance in terrestrial ecosystems and plays a key role in the germination process and seedling establishment of many species. In grassland ecosystems, seeds...