Modification of pectin with UV-absorbing substitutents and its effect on the structural and hydrodynamic properties of the water-soluble derivatives

Citrus pectin with a low degree of methyl esterification (LMP) and its deesterified form, potassium pectate (KP), were modified with a low amount of UV-absorbing substituents. For this purpose, two different substitution reactions were used (a) alkylation of hydroxyl groups with p-carboxybenzyl bromide in aqueous alkali and (b) alkylation of the carboxylate group with benzyl bromide in the DMSO/TBAI/catalyst system. Chemical and spectroscopic methods reveal a low degree of substitution (DS<0.1) for the derivatives. The hydrodynamic properties were assessed by analytical ultracentrifugion, viscometry, and HPGPC. The results indicate that the introduction of small amounts of p-carboxybenzyl ether groups practically had no effect on the hydrodynamic properties in the case of KP, whereas, it was accompanied with a decrease of the molecular mass for LMP. The degradation was more pronounced during the benzyl esterification of LMP. The results confirmed that LMP is susceptible to chain cleavage due to β-elimination during both modification reactions. However, KP seems to be more tolerant of the reaction conditions.     

Predicted ionisation in mitochondria and observed acute changes in the mitochondrial transcriptome after gamma irradiation: A Monte Carlo simulation and quantitative PCR study

It is a widely accepted that the cell nucleus is the primary site of radiation damage while extra-nuclear radiation effects are not yet systematically included into models of radiation damage.We performed Monte Carlo simulations assuming a spherical cell (diameter 11.5 μm) modelled after JURKAT cells with the inclusion of realistic elemental composition data based on published literature. The cell model consists of cytoplasm (density 1 g/cm³), nucleus (diameter 8.5 μm; 40% of cell volume) as well as cylindrical mitochondria (diameter 1 μm; volume 0.5 μm³) of three different densities (1, 2 and 10 g/cm³) and total mitochondrial volume relative to the cell volume (10, 20, 30%). Our simulation predicts that if mitochondria take up more than 20% of a cell's volume, ionisation events will be the preferentially located in mitochondria rather than in the cell nucleus.Using quantitative polymerase chain reaction, we substantiate in JURKAT cells that human mitochondria respond to gamma radiation with early (within 30 min) differential changes in the expression levels of 18 mitochondrially encoded genes, whereby the number of regulated genes varies in a dose-dependent but non-linear pattern (10 Gy: 1 gene; 50 Gy: 5 genes; 100 Gy: 12 genes).The simulation data as well as the experimental observations suggest that current models of acute radiation effects, which largely focus on nuclear effects, might benefit from more systematic considerations of the early mitochondrial responses and how these may subsequently determine cell response to ionising radiation.     

Asymmetrical intraspecific competition in <Emphasis Type="Italic">Echinochloa crus</Emphasis>-<Emphasis Type="Italic">galli</Emphasis> is related to differences in the timing of seedling emergence and seedling vigour

Individual size is an important factor that determines fitness in annual plants. Variation in size originates at the seedling stage based on differences in seedling vigour and time of emergence, ensuing asymmetrical intraspecific competition between early- and late-established plants. The effects of the order of seedling emergence on characteristics of barnyard grass (Echinochloa crus-galli) were studied. In the first experiment, competition between pairs of plants, one of which was sown and emerged 0, 3, 6 or 12 days earlier than the other, was determined. In the second experiment, competition between two plants that were sown at the same time, but emerged at different times because of variation in seed quality, was determined. Competition decreased plant mass, tillering, height and the number of caryopses per panicle, but not time to earing or root/shoot ratio. Plants that were sown 3 days after the first plants in competing pairs grew to 32% of the size of solitary control plants, with the effect of competition accounting for 40% and asymmetrical competition 28% of the total reduction in size. When a 3-day lag in germination was determined intrinsically, plant size was reduced to 19% of the control, with the effect of competition accounting for 34%, asymmetrical competition 15% and poor intrinsic quality of the plant 32% of the total reduction in size. Small environmentally induced delays and more importantly, intrinsically induced delays in the time of emergence result in a considerable decrease in final plant size and fitness.     

Automated analysis of craniofacial morphology using magnetic resonance images

Quantitative analysis of craniofacial morphology is of interest to scholars working in a wide variety of disciplines, such as anthropology, developmental biology, and medicine. T1-weighted (anatomical) magnetic resonance images (MRI) provide excellent contrast between soft tissues. Given its three-dimensional nature, MRI represents an ideal imaging modality for the analysis of craniofacial structure in living individuals. Here we describe how T1-weighted MR images, acquired to examine brain anatomy, can also be used to analyze facial features. Using a sample of typically developing adolescents from the Saguenay Youth Study (N = 597; 292 male, 305 female, ages: 12 to 18 years), we quantified inter-individual variations in craniofacial structure in two ways. First, we adapted existing nonlinear registration-based morphological techniques to generate iteratively a group-wise population average of craniofacial features. The nonlinear transformations were used to map the craniofacial structure of each individual to the population average. Using voxel-wise measures of expansion and contraction, we then examined the effects of sex and age on inter-individual variations in facial features. Second, we employed a landmark-based approach to quantify variations in face surfaces. This approach involves: (a) placing 56 landmarks (forehead, nose, lips, jaw-line, cheekbones, and eyes) on a surface representation of the MRI-based group average; (b) warping the landmarks to the individual faces using the inverse nonlinear transformation estimated for each person; and (3) using a principal components analysis (PCA) of the warped landmarks to identify facial features (i.e. clusters of landmarks) that vary in our sample in a correlated fashion. As with the voxel-wise analysis of the deformation fields, we examined the effects of sex and age on the PCA-derived spatial relationships between facial features. Both methods demonstrated significant sexual dimorphism in craniofacial structure in areas such as the chin, mandible, lips, and nose.     

Arthropod community of dandelion (Taraxacum officinale) capitula during seed dispersal

Dandelion (Taraxacum officinale) is an abundant Asteraceae species of grassland and vasteland stands. Through the vegetative season each plant produces a number of short-lived inflorescens. Final stage of inflorescence development is seed dispersal that lasts 2 days. Despite its ephemeral persistence, inflorescences at this period host abundant fauna. In 2005–2010 the inflorescences were collected in regular intervals in May–October, at Prague-Ruzyně and selected sites of western Czech Republic. Typical fauna consist of Heteroptera adults and larvae (34 species), phytophagans feeding on receptacle and seeds (mainly Miridae, Pentatomidae, Rhopalidae) and predators consuming thrips (Anthocoridae). The composition of Heteroptera fauna varies through the vegetative season, and its abundance decreases with increasing altitude of the locality. Other fauna are relics of species consuming seeds in the post-flowering phase of inflorescence maturation (mainly Thysanoptera) and occasional visitors with no trophic relationship to dandelion (Coleoptera, Diptera, Hymenoptera, Araneae). The reasons for association of phytophagous Heteroptera and dandelion may be preferences for seed consumption and chemicals present in plant tissues and possibly used for sequestration of aposematic substances.     

Routine Clinical Measures of Adiposity as Predictors of Visceral Fat in Adolescence: A Population-Based Magnetic Resonance Imaging Study

Objective

Visceral fat (VF) increases cardiometabolic risk more than fat stored subcutaneously. Here, we investigated how well routine clinical measures of adiposity, namely body mass index (BMI) and waist circumference (waist), predict VF and subcutaneous fat (SF) in a large population-based sample of adolescents. As body-fat distribution differs between males and females, we performed these analyses separately in each sex.

Design and Methods

VF and SF were measured by magnetic resonance imaging in 1,002 adolescents (482 males, age 12–18 years). Relationships of BMI and waist with VF and SF were tested in multivariable analyses, which adjusted for potentially confounding effects of age and height.

Results

In both males and females, BMI and waist were highly correlated with VF and SF, and explained 55–76% of their total variance. When VF was adjusted for SF, however, BMI and waist explained, respectively, only 0% and 4% of VF variance in males, and 4% and 11% of VF variance in females. In contrast, when SF was adjusted for VF, BMI and waist explained, respectively, 36% and 21% of SF variance in males, and 48% and 23% of SF variance in females. These relationships were similar during early and late puberty.

Conclusions and Relevance

During adolescence, routine clinical measures of adiposity predict well SF but not VF. This holds for both sexes and throughout puberty. Further longitudinal studies are required to assess how well these measures predict changes of VF and SF over time. Given the clinical importance of VF, development of cost-effective imaging techniques and/or robust biomarkers of VF accumulation that would be suitable in everyday clinical practice is warranted.     

Characteristics of an Environmentally Monitored Prolonged Type 2 Vaccine Derived Poliovirus Shedding Episode that Stopped without Intervention

Vaccine derived poliovirus (VDPV) type 2 strains strongly divergent from the corresponding vaccine strain, Sabin 2, were repeatedly isolated from sewage in Slovakia over a period of 22 months in 2003–2005. Cell cultures of stool specimens from known immune deficient patients and from an identified putative source population of 500 people failed to identify the potential excretor(s) of the virus. The occurrence of VDPV in sewage stopped without any intervention. No paralytic cases were reported in Slovakia during the episode. According to a GenBank search and similarity plotting-analysis, the closest known relative of the first isolate PV2/03/SVK/E783 through all main sections of the genome was the type 2 poliovirus Sabin strain, with nucleotide identities in 5′UTR, P1, P2, P3, and 3′UTR parts of the genome of 88.6, 85.9, 87.3, 88.5, and 94.0 percent, respectively. Phenotypic properties of selected Slovakian aVDPV strains resembled those of VDPV strains isolated from immune deficient individuals with prolonged PV infection (iVDPV), including antigenic changes and moderate neurovirulence in the transgenic mouse model. One hundred and two unique VP1 coding sequences were determined from VDPV strains isolated from 34 sewage specimens. Nucleotide differences from Sabin 2 in the VP1 coding region ranged from 12.5 to 15.6 percent, and reached a maximum of 9.6 percent between the VDPV strains under study. Most of the nucleotide substitutions were synonymous but as many as 93 amino acid positions out of 301 in VP1 showed substitutions. We conclude that (1) individuals with prolonged poliovirus infection are not as rare as suggested by the studies on immune deficient patients known to the health care systems and (2) genetic divergence of VDPV strains may remain extensive during years long replication in humans.