Volatiles from the epicuticular wax of watercress (Rorippa nasturtium-aquaticum)

Volatiles from the epicuticular wax of watercress were collected by ether washing and examined using gas chromatographic and mass spectrometric analysi     

Crown alterations induced by decline: a study of relationships between growth rate and crown morphology in beech (Fagus sylvatica L.)

One of the first symptoms expressed by declining trees is reduced growth in stem diameter and length increment. The possibility of a relationship between length increment and crown thinning in beech (Fagus sylvatica L.) was investigated by developing a computer model to simulate first order branching patterns of the apical 2 m of monopodially branching beech trees, 70–100 years old, for a range of length increment rates. The model was based on values for branching angle, main axis and branch length increment, number of branches produced per year and branch mortality rates for six healthy and declining trees. Shoot growth rates in the apical 2 m of the sample trees ranged from about 5 cm/year (decline class 3) to 43 cm/ year (healthy). Simulations of branching patterns in the apical 2 m of trees growing at different rates indicated that, when growth rate exceeded about 20 cm/year, total first order branch length and area explored were independent of growth rate. When growth rates fell below this value there was a reduction in total area explored and first order branch length due primarily to the formation of fewer branches. More acute branching angles contributed to a reduction in the area explored. Growth rate-related crown thinning could increase the risk of bark necrosis and secondary pathogen infection during dry and/or hot spells.     

Evidence of Coat Color Variation Sheds New Light on Ancient Canids

We have used a paleogenetics approach to investigate the genetic landscape of coat color variation in ancient Eurasian dog and wolf populations. We amplified DNA fragments of two genes controlling coat color, Mc1r (Melanocortin 1 Receptor) and CBD103 (canine-β-defensin), in respectively 15 and 19 ancient canids (dogs and wolf morphotypes) from 14 different archeological sites, throughout Asia and Europe spanning from ca. 12 000 B.P. (end of Upper Palaeolithic) to ca. 4000 B.P. (Bronze Age). We provide evidence of a new variant (R301C) of the Melanocortin 1 receptor (Mc1r) and highlight the presence of the beta-defensin melanistic mutation (CDB103-K locus) on ancient DNA from dog-and wolf-morphotype specimens. We show that the dominant K^B allele (CBD103), which causes melanism, and R301C (Mc1r), the variant that may cause light hair color, are present as early as the beginning of the Holocene, over 10 000 years ago. These results underline the genetic diversity of prehistoric dogs. This diversity may have partly stemmed not only from the wolf gene pool captured by domestication but also from mutations very likely linked to the relaxation of natural selection pressure occurring in-line with this process.     

Expression and purification of monospecific and bispecific recombinant antibody fragments derived from antibodies that block the CD80/CD86-CD28 costimulatory pathway

The development of recombinant techniques for rapid cloning, expression, and characterization of cDNAs encoding antibody (Ab) subunits has revolutionized the field of antibody engineering. By fusion to heterologous protein domains, chain shuffling, or inclusion of self-assembly motifs, novel molecules such as bispecific Abs can be generated that possess the subset of functional properties designed to fit the intended application. We describe the engineering of Ab fragments produced in bacteria for blocking the CD28-CD80/CD86 costimulatory interaction in order to induce tolerance against transplanted organs. We designed single-chain Fv antibodies, monospecific and bispecific diabodies, and a bispecific tetravalent antibody (BiTAb) molecule directed against the CD80 and/or CD86 costimulatory molecules. These recombinant Ab molecules were expressed in Escherichia coli, followed by purification and evaluation for specific interaction with their respective antigen in an enzyme-linked immunosorbent assay (ELISA). A specific sandwich ELISA confirmed the bispecificity of the bispecific diabodies and the BiTAb.     

Cytochemical and X-ray microanalytical studies of calcium in the extending zone, particularly in the rhizodermis of Zea mays roots

Calcium was detected in CaCl (10 m M )-pretreated roots of Zea mays L. (cv. LG 11) by means of electron probe X-ray microanalysis with energy-dispersive spectrometry (EDS) using embedded samples, fixed by the antimonate staining procedure. A high level of calcium was found where large amounts of antimonate precipitates were observed by light or transmission electron microscopy. In the elongation zone, after 20 h in humid air following a 2 h CaCl₂ pretreatment, the level of calcium was higher in trichoblasts than in atrichoblasts. In these cells it was detected mainly in the walls and nucleus, and antimonate staining was observed in the walls. Abundant precipitates containing calcium were associated with the nucleus, vacuoles, mitochondria and endoplasmic reticulum of non-differentiated cells, whereas they were confined to the walls of these cells just after the CaCl₂ pretreatment. The involvement of calcium in the formation of root hairs is discussed.     

Root hair formation and elongation of primary maize roots

In maize ( Zea mays L. cv. LG 11) roots cultured in humid air, the presence of hairs was not related to root growth. However, maximum hair length and length of the hair zone could be correlated to the elongation rate of the primary root. Under the growth conditions used, the emergence of root hairs always took place in the extending zone. In more basal regions, rhizodermal cells could not give rise to root hairs. Results were similar for roots preincubated in a buffer solution.     

Early-life stress is associated with gender-based vulnerability to epileptogenesis in rat pups

During development, the risk of developing mesial temporal lobe epilepsy (MTLE) increases when the developing brain is exposed to more than one insult in early life. Early life insults include abnormalities of cortical development, hypoxic-ischemic injury and prolonged febrile seizures. To study epileptogenesis, we have developed a two-hit model of MTLE characterized by two early-life insults: a freeze lesion-induced cortical malformation at post-natal day 1 (P1), and a prolonged hyperthermic seizure (HS) at P10. As early life stressors lead to sexual dimorphism in both acute response and long-term outcome, we hypothesized that our model could lead to gender-based differences in acute stress response and long-term risk of developing MTLE. Male and female pups underwent a freeze-lesion induced cortical microgyrus at P1 and were exposed to HS at P10. Animals were monitored by video-EEG from P90 to P120. Pre and post-procedure plasma corticosterone levels were used to measure stress response at P1 and P10. To confirm the role of sex steroids, androgenized female pups received daily testosterone injections to the mother pre-natally and post-natally for nine days while undergoing both insults. We demonstrated that after both insults females did not develop MTLE while all males did. This correlated with a rise in corticosterone levels at P1 following the lesion in males only. Interestingly, all androgenized females showed a similar rise in corticosterone at P1, and also developed MTLE. Moreover, we found that the cortical lesion significantly decreased the latency to generalized convulsion during hyperthermia at P10 in both genders. The cortical dysplasia volumes at adulthood were also similar between male and female individuals. Our data demonstrate sexual dimorphism in long-term vulnerability to develop epilepsy in the lesion + hyperthermia animal model of MTLE and suggest that the response to early-life stress at P1 contributes significantly to epileptogenesis in a gender-specific manner.     

Pilot study naar het persoonsgericht gebruik van foto’s in de communicatie met mensen met dementie

Social contact is important for the wellbeing of people. Dementia can complicate social interaction. In two randomized controlled pilot studies, it was investigated whether viewing different types of images together affects the mood and social interaction of people with moderately severe to severe Alzheimer’s dementia residing in nursing homes. At the first intervention participants in the experimental group (n?=?10) were shown portraits with positive facial expressions, and the participants in the control group (n?=?10) were shown portraits with a neutral facial expression. During the second intervention, the experimental group (n?=?10) were shown personalized photos and the control group (n?=?10) non-personalized photos. There were no statistically significant differences in mood and the degree of social interaction between the groups. However, calculation of the effect sizes showed that there was a tendency for more positive behavior in viewing neutral portraits and that personalized images had a more positive impact on social interaction, negative behavior, speech and mood.     

Predicting Fire Frequency with Chemistry and Climate

A predictive equation for estimating fire frequency was developed from theories and data in physical chemistry, ecosystem ecology, and climatology. We refer to this equation as the Physical Chemistry Fire Frequency Model (PC2FM). The equation was calibrated and validated with North American fire data (170 sites) prior to widespread industrial influences (before ~1850 CE) related to land use, fire suppression, and recent climate change to minimize non-climatic effects. We derived and validated the empirically based PC2FM for the purpose of estimating mean fire intervals (MFIs) from proxies of mean maximum temperature, precipitation, their interaction, and estimated reactant concentrations. Parameterization of the model uses reaction rate equations based on the concentration and physical chemistry of fuels and climate. The model was then calibrated and validated using centuries of empirical fire history data. An application of the PC2FM regression equation is presented and used to estimate historic MFI as controlled by climate. We discuss the effects of temperature, precipitation, and their interactions on fire frequency using the PC2FM concept and results. The exclusion of topographic, vegetation, and ignition variables from the PC2FM increased error at fine spatial scales, but allowed for the prediction of complex climate effects at broader temporal and spatial scales. The PC2FM equation is used to map coarse-scale historic fire frequency and assess climate impacts on landscape-scale fire regimes.