Investigating a flower-insect forager network in a mountain grassland community using pollen DNA barcoding

Faced with the decline of pollinators, it is relevant to strengthen our understanding of the whole plant-pollinator web in semi-natural grasslands that serve as refuges for pollinator populations. The aim of this study was to explore the diversity of flower-foraging insects involved in pollen transfer in mountain semi-natural grasslands. Insects actively collecting pollen and/or nectar were caught in spring in six mountain semi-natural grasslands displaying a floristic richness gradient. Individual determinations of insects were made at the finest possible taxonomic scale and pollen loads were removed from the insect body. Using next-generation DNA sequencing, pollens were identified through the ribosomal DNA cistron using the ITS2 database and the ITS plant rDNA cistron sequences from Genbank. A total of 236 flower-foraging insects were collected. Diptera represented 82% of the total catches distantly followed by Hymenoptera (15%) and Apoidea (bees) (11%). Visual observations revealed that Diptera foraged on 16 of the 21 flower species visited by insects. DNA metabarcoding showed that 82% (191) of all of the collected insects were carrying pollen and 44% (104) were carrying two genera of plants or more. Our results demonstrate that Diptera are potential key-pollinators in mountain semi-natural grasslands that cannot be overlooked by the scientific community. However difficulties of taxonomic determination due to severe shortage of experts for Diptera have to be urgently overcome. Further studies on the link between pollen transfer and actual pollination in a global change context are also required. Moreover, our results support the idea that DNA metabarcoding provides accurate information about the plants-insects networks but it also pointed out sensitive issues, especially the necessity to build reliable national barcode databases.     

A new chromosomal race (2n=44) of Nannospalax xanthodon from Turkey (Mammalia: Rodentia)

A new karyotype for blind mole rats was recorded in Tunceli province in Eastern Turkey. The karyotype contained 44 chromosomes, including 13 biarmed pairs, 7 acrocentric pairs, and one heteromorphic pair with a submetacentric and an acrocentric homologue in the autosomal complement (FNa=69). The X chromosome was submetacentric and the Y chromosome medium-sized subtelocentric (FN=73). Distinct dark centromeric C-bands were observed on most of the biarmed and three pairs of the acrocentric autosomes. The NORs were detected on short arms of three subtelocentric pairs and one acrocentric pair of autosomes. The diploid number of chromosomes and the karyotype characteristics observed are obviously unique among hitherto studied populations of blind mole rats and the complement can be evaluated as a new chromosome race of Nannospalax xanthodon. The distribution ranges of individual chromosome races of the species recorded in Eastern Anatolia are revised and possible interracial hybridization is discussed in respect of the finding of a new race.     

Actigraphic estimates of sleep and the sleep-wake rhythm,and 6-sulfatoxymelatonin levels in healthy Dutch children

ABSTRACT

Sleep and the sleep-wake rhythm are essential for children’s health and well-being, yet reference values are lacking. This study therefore aimed to assess actigraphic estimates of sleep and the 24-h sleep-wake rhythm, as well as 6-sulfatoxymelatonin (aMT6s) levels in healthy children of different age groups. Additionally, relationships between the outcomes and sex, highest parental educational level (as an indication of socioeconomic status (SES)), and body-mass-index (BMI) were explored. In this cross-sectional study, healthy Dutch children (2–18 years) wore an actigraph (GT3x) for 7 consecutive days, collected first-morning void urine and completed a sleep log and sociodemographic questionnaire. Actigraphically estimated sleep variables were sleep onset latency (SOL), sleep efficiency (SE), total sleep time (TST), and wake after sleep onset (WASO). Non-parametric sleep-wake rhythm variables were intradaily variability (IV); interdaily stability (IS); the activity counts and timing of the least active 5-h period (L5counts and midpoint) and of the most active 10-h period (M10 counts and midpoint); and the relative amplitude (RA), i.e. the ratio of the difference and the sum of M10 and L5 counts. Finally, creatinine-corrected aMT6s levels were obtained by isotope dilution mass spectrometry. Effects of age group (preschool 2–5 years/school-aged 6–12 years/teenager 13–18 years), sex, highest parental educational level and BMI (Z-scores) were explored. Ninety-four children participated, equally divided across age groups (53% boys). Teenagers slept less, but more efficiently, than younger children, while their 24 h sleep-wake rhythm was the least stable and most fragmented (likely due to fragmentation of daytime activity). Additionally, aMT6s levels significantly declined over the age groups. Children from highly educated parents had lower sleep efficiency, but a more stable sleep-wake rhythm. Finally, sex or increase in BMI was not associated with any of the outcomes in this study. In conclusion, this study provides reference values of healthy children across different age groups and different sociodemographic factors. In the future, this information may help to better interpret outcomes in clinical populations.     

Lipase-catalyzed synthesis of aromatic polyesters

The enzymatic synthesis of aromatic polyesters by direct polyesterification between a diacid and a diol is described. The effects of the type of substrate, type and quantities of lipase, temperature, vacuum, and reaction time on the synthesis of aromatic polyesters were studied in detail. Among three lipases investigated, only Novozym 435 worked well for aromatic polyester synthesis. Temperature and vacuum played an important role in obtaining a high molar mass of the aromatic polyesters. Furthermore, with isophthalic acid and 1,6-hexanediol as substrates, the mass average molar mass of the polyester obtained increased with an increase in the lipase quantity up to 0.375 g (11.7%, w/w of total reactor contents). The mass average molar mass of the polyester was as high as 50000 g mol⁻¹ in 168 h, with a polydispersity of PD ≈ 1.4. Received 27 January 1998/ Accepted in revised form 19 May 1998     

Using variation partitioning techniques to quantify the effects of invasive alien species on native urban bird assemblages

Quantifying the impacts that invasive alien species (IAS) cause on affected systems is not an easy task. Here, we explore the application of variation partitioning techniques to measure and control for the effects of possible confounding factors when studying the impact that feral pigeons, European starlings, and house sparrows cause on native urban bird communities in Mexico. We argue that these IAS are provoking a severe impact on whole assemblages of native passerines only if (a) their marginal effect is statistically significant, (b) it remains so after partialling out other explanatory variables, and (c) is larger than (or similar to) the conditional effect of these covariates. We censused passerine bird assemblages and measured habitat variables in a number of greenspaces in three replicate study areas. Then, by means of partial redundancy analyses, we decomposed the total variability in bird data as a function of IAS, physical variables and vegetation data. In one of the study areas the marginal effect of IAS on native assemblages was significant, but the conditional effect was not. We conclude that this IAS effect was confounded with other explanatory variables. In the other study areas, no (marginal or partial) significant effect was found. Without invoking interspecific competition, our results support the opportunistic hypothesis, according to which IAS can exploit ecological conditions in modern cities that native species cannot even tolerate. Finally, apart from the Precautionary Principle, we found no scientific justification to control the abundance of the three IAS in our study areas.     

A biomechanical mathematical model for the collagen bundle distribution-dependent contraction and subsequent retraction of healing dermal wounds

A continuum hypothesis-based, biomechanical model is presented for the simulation of the collagen bundle distribution-dependent contraction and subsequent retraction of healing dermal wounds that cover a large surface area. Since wound contraction mainly takes place in the dermal layer of the skin, solely a portion of this layer is included explicitly into the model. This portion of dermal layer is modeled as a heterogeneous, orthotropic continuous solid with bulk mechanical properties that are locally dependent on both the local concentration and the local geometrical arrangement of the collagen bundles. With respect to the dynamic regulation of the geometrical arrangement of the collagen bundles, it is assumed that a portion of the collagen molecules are deposited and reoriented in the direction of movement of (myo)fibroblasts. The remainder of the newly secreted collagen molecules are deposited by ratio in the direction of the present collagen bundles. Simulation results show that the distribution of the collagen bundles influences the evolution over time of both the shape of the wounded area and the degree of overall contraction of the wounded area. Interestingly, these effects are solely a consequence of alterations in the initial overall distribution of the collagen bundles, and not a consequence of alterations in the evolution over time of the different cell densities and concentrations of the modeled constituents. In accordance with experimental observations, simulation results show furthermore that ultimately the majority of the collagen molecules ends up permanently oriented toward the center of the wound and in the plane that runs parallel to the surface of the skin.

     

Synthesis,Molecular Modeling,and Biological Evaluation of Novel Chiral Thiosemicarbazone Derivatives as Potent Anticancer Agents

A series of new chiral thiosemicarbazones derived from homochiral amines in both enantiomeric forms were synthesized and evaluated for their in vitro antiproliferative activity against A549 (human alveolar adenocarcinoma), MCF‐7 (human breast adenocarcinoma), HeLa (human cervical adenocarcinoma), and HGC‐27 (human stomach carcinoma) cell lines. Some of compounds showed inhibitory activities on the growth of cancer cell lines. Especially, compound 17b exhibited the most potent activity (IC₅₀ 4.6 μM) against HGC‐27 as compared with the reference compound, sindaxel (IC₅₀ 10.3 μM), and could be used as a lead compound to search new chiral thiosemicarbazone derivatives as antiproliferative agents. Chirality 27:177–188, 2015. © 2014 Wiley Periodicals, Inc.