Baring it all: undressing Cambrian ‘Orsten’ phosphatocopine crustaceans using synchrotron radiation X‐ray tomographic microscopy

Synchrotron radiation X‐ray tomographic microscopy (SRXTM) was used to virtually dissect and peel the shields off of the microscopic, bivalved phosphatocopine crustaceans in the Cambrian ‘Orsten’ type of preservation of Sweden. Doing so opened up for an array of concealed internal structures to be observed in a fully enclosed specimen of Hesslandona ventrospinata and a semi‐enclosed specimen of Hesslandona angustata. For comparison, also a head‐larva stage specimen of H. angustata, with shields in ‘butterfly position’, was analysed. The X‐ray tomographic data sets revealed excellently preserved structures, such as labrum, sternum, antennae, mandibular and post‐mandibular limbs with their minute setae, all of which were more or less disguised by the enclosing shields. This, moreover, allowed assignment to growth stages of the specimens, which is impossible based solely on external morphology and size. Micro‐spherules observed inside the shields of the semi‐enclosed H. angustata specimen may represent remains of food particles, and the feeding biology of phosphatocopines is discussed in detail. Our analyses suggest that phosphatocopines were particle feeders. The SRXTM technique offers the ability to three‐dimensionally reconstruct the morphology in high resolution, construct virtual serial sections and study concealed structures. The resulting data allow for new structures to be revealed for previously known taxa and for new taxa to be identified, with the added benefit of not destroying the specimens in the process. Hence, we do not longer have to rely on serendipitous finds of broken and/or open phosphatocopine specimens to elucidate their diagnostic ventral morphology.     

Effects of gamma radiation and hyperthermia on DNA repair synthesis and the level of NAD+ in cultured human mononuclear leukocytes

DNA repair has been investigated, estimated by unscheduled DNA synthesis (UDS) and the cellular NAD+ pool, after exposing human mononuclear leukocytes to hyperthermia and gamma radiation separately and in combination. It was found that gamma radiation induced a decline in UDS with increasing temperature through the temperature region studied (37-45 degrees C). At 42.5 degrees C the gamma-ray-induced UDS was reduced to about 70% of that at 37 degrees C. Following gamma-ray damage the NAD+ pool dropped to about 20% of control values. Without hyperthermic treatment the cells completely recovered to the original level within 5 hr. Moderate hyperthermia (42.5 degrees C for 45 min) followed by gamma-ray damage altered the kinetics so that even after 8 hr the NAD+ pool had recovered to only 70% of the original level. After heat treatment at 44 degrees C for 45 min prior to gamma radiation the cells did not recover at all, presumably because of the cytotoxic effects from the combined treatment.     

Embryonic response to long‐term exposure of the marine crustacean Nephrops norvegicus to ocean acidification and elevated temperature

Due to anthropogenic CO₂ emissions, our oceans have gradually become warmer and more acidic. To better understand the consequences of this, there is a need for long‐term (months) and multistressor experiments. Earlier research demonstrates that the effects of global climate change are specific to species and life stages. We exposed berried Norway lobsters (Nephrops norvegicus), during 4 months to the combination of six ecologically relevant temperatures (5–18°C) and reduced pH (by 0.4 units). Embryonic responses were investigated by quantifying proxies for development rate and fitness including: % yolk consumption, mean heart rate, rate of oxygen consumption, and oxidative stress. We found no interactions between temperature and pH, and reduced pH only affected the level of oxidative stress significantly, with a higher level of oxidative stress in the controls. Increased temperature and % yolk consumed had positive effects on all parameters except on oxidative stress, which did not change in response to temperature. There was a difference in development rate between the ranges of 5–10°C (Q₁₀: 5.4) and 10–18°C (Q₁₀: 2.9), implicating a thermal break point at 10°C or below. No thermal limit to a further increased development rate was found. The insensitivity of N. norvegicus embryos to low pH might be explained by adaptation to a pH‐reduced external habitat and/or internal hypercapnia during incubation. Our results thus indicate that this species would benefit from global warming and be able to withstand the predicted decrease in ocean pH in the next century during their earliest life stages. However, future studies need to combine low pH and elevated temperature treatments with hypoxia as hypoxic events are frequently and increasingly occurring in the habitat of benthic species.     

A study of the possible association between adenosine A2A receptor gene polymorphisms and attention‐deficit hyperactivity disorder traits

The adenosine A_2A receptor (ADORA2A) is linked to the dopamine neurotransmitter system and is also implicated in the regulation of alertness, suggesting a potential association with attention‐deficit hyperactivity disorder (ADHD) traits. Furthermore, animal studies suggest that the ADORA2A may influence ADHD‐like behavior. For that reason, the ADORA2A gene emerges as a promising candidate for studying the etiology of ADHD traits. The aim of this study was to examine the relationship between ADORA2A gene polymorphisms and ADHD traits in a large population‐based sample. This study was based on the Child and Adolescent Twin Study in Sweden (CATSS), and included 1747 twins. Attention‐deficit hyperactivity disorder traits were assessed through parental reports, and samples of DNA were collected. Associations between six single nucleotide polymorphisms (SNPs) and ADHD traits were examined, and results suggested a nominal association between ADHD traits and three of these SNPs: rs3761422, rs5751876 and rs35320474. For one of the SNPs, rs35320474, results remained significant after correction for multiple comparisons. These results indicate the possibility that the ADORA2A gene may be involved in ADHD traits. However, more studies replicating the present results are warranted before this association can be confirmed .     

Interactions of galactose-binding lectins with plant protoplasts

Summary Protoplasts isolated from cell suspension cultures of carrot (Daucus carota L.) and leaves of tobacco (Nicotiana tabacum L.) were treated with three lectins specific for galactosyl residues. After incubation with RCA I (Ricinus communis agglutinin, molecular weight 120,000) conjugated to ferritin or fluorescein, freshly isolated protoplasts displayed heavy labeling of their surfaces. Moreover, they agglutinated rapidly when exposed to low concentrations of RCA I. In parallel studies, PNA (peanut agglutinin) also bound extensively to the protoplast plasma membranes whileBandeiraea simplicifolia lectin I attached relatively weakly. When protoplasts were cultured for two days and then incubated with conjugates of RCA I and PNA, additional binding sites were revealed on the regenerating walls.The results indicate that galactosyl residues are distributed densely over the surface of plant protoplasts. They also allow inferences to be made regarding the positions and linkages of the galactose groups being recognized by the lectins. Moreover, they open up the question whether the galactosyl moieties detected in the wall derive from those labeled on the plasma membrane. To conclude, we make comparisons with binding by concanavalin A, and predict that galactose-recognizing lectins will join and in certain respects prove superior to concanavalin A as probes of the plant cell surface.     

Deamination features of 5-hydroxymethylcytosine,a radical and enzymatic DNA oxidation product

Geometric consequences of electron delocalization were studied for all possible adenine tautomers in aqueous solution by means of ab initio methods {PCM(water)//DFT(B3LYP)/6-311+G(d,p)} and compared to those in the gas phase {DFT(B3LYP)/6-311+G(d,p)}. To measure the consequences of any type of resonance conjugation (π-π, n-π, and σ-π), the geometry-based harmonic oscillator model of electron delocalization (HOMED) index, recently extended to the isolated (DFT) and hydrated (PCM//DFT) molecules, was applied to the molecular fragments (imidazole, pyrimidine, 4-aminopyrimidine, and purine) and also to the whole tautomeric system. For individual tautomers, the resonance conjugations and consequently the bond lengths strongly depend on the position of the labile protons. The HOMED indices are larger for tautomers (or their fragments) possessing the labile proton(s) at the N rather than C atom. Solvent interactions with adenine tautomers slightly increase the resonance conjugations. Consequently, they slightly shorten the single bonds and lengthen the double bonds. When going from the gas phase to water solution, the HOMED indices increase (by less than 0.15 units). There is a good relation between the HOMED indices estimated in water solution and those in the gas phase for the neutral and ionized forms of adenine. Subtle effects, being a consequence of intramolecular interactions between the neighboring groups, are so strongly reduced by solvent that the relation between the HOMED indices and the relative energies for the neutral adenine tautomers seems to be better in water solution than in the gas phase.

Inhibition enzyme-linked immunosorbent assay for detection of Pseudomonas fluorescens on meat surfaces.

An inhibition enzyme-linked immunosorbent assay was developed for Pseudomonas fluorescens enumeration of meat surfaces. The assay detected contamination levels as low as 3 x 10(5) bacteria per ml and could be completed within 4 h. It could be used as a framework for a test system for quantifying P. fluorescens spoilage in meat products.     

Gene technology-based antimetabolite design: the use of an in vitro protein expression system to facilitate antimetabolite design for virally-induced human diseases and malignant conditions

A precondition for the chemotherapeutic treatment of a variety of virally-induced human diseases and malignant conditions is a highly selective interaction of the drug molecule to be used with it's biological target. To ensure the development of novel, effective drugs, it is essential that the biological target is well characterised with regard to it's structure and activity. Such characterisation relies upon adequate amounts of pure target being available. One of the most important enzymatic importers for antimetabolites is the enzyme thymidine kinase. In this article an in vitro protein expression system is described which facilitates the production of milligram amounts of pure and biologically active thymidine kinase, from a number of important biological sources. Results have shown that the in vitro produced enzyme has the exact biochemical propeties of the in vivo enzyme. Thus the in vitro protein expression system is an ideal vechicle to facilitate an in depth investigation of the enzyme's biological properties.     

Linkage disequilibrium patterns vary with chromosomal location: a case study from the von Willebrand factor region.

Linkage disequilibrium analysis has been used as a tool for analyzing marker order and locating disease genes. Under appropriate circumstances, disequilibrium patterns reflect recombination events that have occurred throughout a population's history. As a result, disequilibrium mapping may be useful in genomic regions of < 1 cM where the number of informative meioses needed to detect recombinant individuals within pedigrees is exceptionally high. Its utility for refining target areas for candidate disease genes before initiating chromosomal walks and cloning experiments will be enhanced as the relationship between linkage disequilibrium and physical distance is better understood. To address this issue, we have characterized linkage disequilibrium in a 144-kb region of the von Willebrand factor gene on chromosome 12. Sixty CEPH and 12 von Willebrand disease families were genotyped for five PCR-based markers, which include two microsatellite repeats and three single-base-pair substitutions. Linkage disequilibrium and physical distance between polymorphisms are highly correlated (rm = -.76; P < .05) within this region. None of the five markers showed significant disequilibrium with the von Willebrand disease phenotype. The linkage disequilibrium/physical distance relationship was also analyzed as a function of chromosomal location for this and eight previously characterized regions. This analysis revealed a general trend in which linkage disequilibrium dissipates more rapidly with physical distance in telomeric regions than in centromeric regions. This trend is consistent with higher recombination rates near telomeres.     

Decreased Proportion of Cytomegalovirus Specific CD8 T-Cells but No Signs of General Immunosenescence in Alzheimer’s Disease

Cytomegalovirus (CMV) has been suggested as a contributing force behind the impaired immune responsiveness in the elderly, with decreased numbers of naïve T-cells and an increased proportion of effector T-cells. Immunological impairment is also implicated as a part of the pathogenesis in Alzheimer’s disease (AD). The aim of this study was to investigate whether AD patients present with a different CMV-specific CD8 immune profile compared to non-demented controls. Blood samples from 50 AD patients and 50 age-matched controls were analysed for HLA-type, CMV serostatus and systemic inflammatory biomarkers. Using multi-colour flow cytometry, lymphocytes from peripheral blood mononuclear cells were analysed for CMV-specific CD8 immunity with MHC-I tetramers A01, A02, A24, B07, B08 and B35 and further classified using CD27, CD28, CD45RA and CCR7 antibodies. Among CMV seropositive subjects, patients with AD had significantly lower proportions of CMV-specific CD8 T-cells compared to controls, 1.16 % vs. 4.13 % (p=0.0057). Regardless of dementia status, CMV seropositive subjects presented with a lower proportion of naïve CD8 cells and a higher proportion of effector CD8 cells compared to seronegative subjects. Interestingly, patients with AD showed a decreased proportion of CMV-specific CD8 cells but no difference in general CD8 differentiation.