Conserved fMRI and LFP signals during new associative learning in the human and macaque monkey medial temporal lobe

We measured local field potential (LFP) and blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in the medial temporal lobes of monkeys and humans, respectively, as they performed the same conditional motor associative learning task. Parallel analyses were used to examine both data sets. Despite significantly faster learning in humans relative to monkeys, we found equivalent neural signals differentiating new versus highly familiar stimuli, first stimulus presentation, trial outcome, and learning strength in the entorhinal cortex and hippocampus of both species. Thus, the use of parallel behavioral tasks and analyses in monkeys and humans revealed conserved patterns of neural activity across the medial temporal lobe during an associative learning task.     

Biofilm roughness determines Cryptosporidium parvum retention in environmental biofilms

The genus Cryptosporidium is a group of waterborne protozoan parasites that have been implicated in significant outbreaks of gastrointestinal infections throughout the world. Biofilms trap these pathogens and can contaminate water supplies through subsequent release. Biofilm microbial assemblages were collected seasonally from three streams in eastern Pennsylvania and used to grow biofilms in laboratory microcosms. Daily oocyst counts in the influx and efflux flow allowed the calculation of daily oocyst retention in the biofilm. Following the removal of oocysts from the influx water, oocyst attachment to the biofilm declined to an equilibrium state within 5 days that was sustained for at least 25 days. Varying the oocyst loading rate for the system showed that biofilm retention could be saturated, suggesting that discrete binding sites determined the maximum number of oocysts retained. Oocyst retention varied seasonally but was consistent across all three sites; however, seasonal oocyst retention was not consistent across years at the same site. No correlation between oocyst attachment and any measured water quality parameter was found. However, oocyst retention was strongly correlated with biofilm surface roughness and roughness varied among seasons and across years. We hypothesize that biofilm roughness and oocyst retention are dependent on environmentally driven changes in the biofilm community rather than directly on water quality conditions. It is important to understand oocyst transport dynamics to reduce risks of human infection. Better understanding of factors controlling biofilm retention of oocysts should improve our understanding of oocyst transport at different scales.     

Metal accumulation in Lolium perenne and Brassica napus as affected by application of chitosans

The effects of chitosan, a fishery waste-based material, and its derivative glutaraldehyde cross-linked chitosan (chitosan-GLA) on metal uptake by Lolium perenne (perennial ryegrass) and Brassica napus (rapeseed) were studied in a greenhouse pot experiment. Metal uptake by perennial ryegrass was highly dependent on the rate of addition of the chitosans. Low application rate (1% w/w) enhanced metal uptake, whereas 10% (w/w) addition decreased metal uptake. It was estimated that chitosan 1% (w/w) treatment could assist perennial ryegrass to remove approximately 3.2 kg Zn/ha and 0.29 kg Pb/ha. For rapeseed, metal uptake was decreased at all rates of application of chitosans. The ammonium acetate extractable metals in soil decreased following application of chitosans and plant growth.     

The red blood cell Esterase D polymorphism in Europe and Asia

Summary Several regional series from Britain and 3 Asian series were typed for the Esterase D polymorphism. It was found that haemolysates up to 5 years old could be reliably typed when prepared from washed anticoagulated red blood cells. Lysates prepared from blood clots do not retain Esterase D activity quite as well. The Manx population has higher Esterase D 2 gene frequencies than neighbouring populations. A Nepalese population exhibits the highest Esterase D 2 gene frequency so far recorded. The other series presented supplement or confirm results already published.     

Progress towards initiation of somatic embryogenesis from differentiated tissues of radiata pine (Pinus radiata D. Don) using cotyledonary embryos

Green cones of radiata pine were collected from two open-pollinated, elite families in two successive years at weekly intervals, and initiation of embryogenic cultures was investigated as a function of sampling date, initiation medium, explant type, and developmental stage. A combination of dissected embryos and a modified Litvay medium, Glitz, was best. This combination gave the highest rate of initiation, and it was possible to initiate somatic embryogenesis (SE) from differentiated cells in the epicotyledonary region of post-cotyledonary zygotic embryos from the two tested families with an average initiation rate of approximately 24% and 7% from stage five and six embryos, respectively. This is different from established initiation protocols of embryogenic cultures in radiata pine, which has traditionally been based on embryo rescue and continued proliferation of immature zygotic embryos. A further implication of initiation of SE from excised post-cotyledonary embryos was that the period of initiation of embryogenic cultures was extended from 4 to 12 wk.     

Muscle blood flow and muscle metabolism during exercise and heat stress

The effect of heat stress on blood flow and metabolism in an exercising leg was studied in seven subjects walking uphill (12-17%) at 5 km/h on a treadmill for 90 min or until exhaustion. The first 30 min of exercise were performed in a cool environment (18-21 degrees C); then subjects moved to an adjacent room at 40 degrees C and continued to exercise at the same speed and inclination for a further 60 min or to exhaustion, whichever occurred first. The rate of O2 consumption, 2.6 l/min (1.8-3.3) (average from cool and hot conditions), corresponded to 55-77% of their individual maximums. In the cool environment a steady state was reached at 30 min. When the subjects were shifted to the hot room, the core temperature and heart rate started to rise and reached values greater than 39 degrees C and near-maximal values, respectively, at the termination of the exercise. The leg blood flow (thermodilution method), femoral arteriovenous O2 difference, and consequently leg O2 consumption were unchanged in the hot compared with the cool condition. There was no increase in release of lactate and no reduction in glucose and free net fatty acid uptake in the exercising leg in the heat. Furthermore, the rate of glycogen utilization in the gastrocnemius muscle was not elevated in the hot environment. There was a tendency for cardiac output to increase in the heat (mean 15.2 to 18.4 l/min), which may have contributed to the increase in skin circulation, together with a possible further reduction in flow to other vascular beds, because muscle blood flow was not reduced.(ABSTRACT TRUNCATED AT 250 WORDS)     

The salt dependence of the interferon regulatory factor 1 DNA binding domain binding to DNA reveals ions are localized around protein and DNA

The equilibrium dissociation constant of the DNA binding domain of interferon regulatory factor 1 (IRF1 DBD) for its DNA binding site depends strongly on salt concentration and salt type. These dependencies are consistent with IRF1 DBD binding to DNA, resulting in the release of cations from the DNA and both release of anions from the protein and uptake of a cation by the protein. We demonstrated this by utilizing the fact that the release of fluoride from protein upon complex formation does not contribute to the salt concentration dependence of binding and by studying mutants in which charged residues in IRF1 DBD that form salt bridges with DNA phosphates are changed to alanine. The salt concentration dependencies of the dissociation constants of wild-type IRF1 DBD and the mutants R64A, D73A, K75A, and D73A/K75A were measured in buffer containing NaF, NaCl, or NaBr. The salt concentration and type dependencies of the mutants relative to wild-type IRF1 DBD provide evidence of charge neutralization by solution ions for R64 and by a salt bridge between D73 and K75 in buffer containing chloride or bromide salts. These data also allowed us to determine the number, type, and localization of condensed ions around both IRF1 DBD and its DNA binding site.