Cytotoxic Effects of the Selective Ligands of Membrane Progesterone Receptors in Human Pancreatic Adenocarcinoma Cells BxPC3

Biochemistry (Moscow) - Progesterone and its synthetic analogues act on cells through different types of receptors, affecting proliferation and apoptosis. These compounds exert their effect through...     

Plant quality and local adaptation undermine relocation in a bog specialist butterfly

The butterfly Boloria aquilonaris is a specialist of oligotrophic ecosystems. Population viability analysis predicted the species to be stable in Belgium and to collapse in the Netherlands with reduced host plant quality expected to drive species decline in the latter. We tested this hypothesis by rearing B. aquilonaris caterpillars from Belgian and Dutch sites on host plants (the cranberry, Vaccinium oxycoccos). Dutch plant quality was lower than Belgian one conferring lower caterpillar growth rate and survival. Reintroduction and/or supplementation may be necessary to ensure the viability of the species in the Netherlands, but some traits may have been selected solely in Dutch caterpillars to cope with gradual changes in host plant quality. To test this hypothesis, the performance of Belgian and Dutch caterpillars fed with plants from both countries were compared. Dutch caterpillars performed well on both plant qualities, whereas Belgian caterpillars could not switch to lower quality plants. This can be considered as an environmentally induced plastic response of caterpillars and/or a local adaptation to plant quality, which precludes the use of Belgian individuals as a unique solution for strengthening Dutch populations. More generally, these results stress that the relevance of local adaptation in selecting source populations for relocation may be as important as restoring habitat quality.     

Bringing Conducting Polymers to High Order: Toward Conductivities beyond 105 S cm−1 and Thermoelectric Power Factors of 2 mW m−1 K−2

Here, an effective design strategy of polymer thermoelectric materials based on structural control in doped polymer semiconductors is presented. The strategy is illustrated for two archetypical polythiophenes, e.g., poly(2,5‐bis(3‐dodecyl‐2‐thienyl)thieno[3,2‐b]thiophene) (C₁₂‐PBTTT) and regioregular poly(3‐hexylthiophene) (P3HT). FeCl₃ doping of aligned films results in charge conductivities up to 2 × 10⁵ S cm^?1 and metallic‐like thermopowers similar to iodine‐doped polyacetylene. The films are almost optically transparent and show strongly polarized near‐infrared polaronic bands (dichroic ratio >10). The comparative study of structure–property correlations in P3HT and C₁₂‐PBTTT identifies three conditions to obtain conductivities beyond 10⁵ S cm^?1: i) achieve high in‐plane orientation of conjugated polymers with high persistence length; ii) ensure uniform chain oxidation of the polymer backbones by regular intercalation of dopant molecules in the polymer structure without disrupting alignment of π‐stacked layers; and iii) maintain a percolating nanomorphology along the chain direction. The highly anisotropic conducting polymer films are ideal model systems to investigate the correlations between thermopower S and charge conductivity σ. A scaling law S ∝ σ^?1/4 prevails along the chain direction, but a different S ∝ ?ln(σ) relation is observed perpendicular to the chains, suggesting different charge transport mechanisms. The simultaneous increase of charge conductivity and thermopower along the chain direction results in a substantial improvement of thermoelectric power factors up to 2 mW m^?1 K^?2 in C₁₂‐PBTTT.     

Distinct tubulin genes are differentially expressed during barley grain development

Tubulins, as major components involved in the organization of microtubules, play an important role in plant development. We describe here the expression profiles of all known α-tubulin (TUA), β-tubulin (TUB) and γ-tubulin (TUG) genes of barley ( Hordeum vulgare ), involving eight newly identified TUB sequences, five established TUA genes and one TUG gene. Macroarray and Northern blot-based expression patterns in the pericarp, endosperm and embryo were obtained over the course of the development of the grain between anthesis and maturation. These revealed that the various tubulin genes differed in their levels of expression, and to some extent were tissue specific. Two expression peaks were detected in the developing endosperm. The first and more prominent peak, at 2 days after flowering, included expression of almost all the tubulin genes. These tubulins are thought to be involved in mitoses during the formation of the syncytial endosperm. The second, less pronounced but more extended, peak included only some of the tubulin genes ( HvTUA3 , HvTUB1 and HvTUG ) and might be associated with the cell wall organization in aleurone and starchy endosperm. The HvTUA5 gene is expressed only in embryo of the developing grain and may be associated with shoot establishment. The expression profiles of the tubulin folding cofactors HvTFC A and HvTFC B as well as small G-protein HvArl2 genes were almost perfectly correlated with the global levels of tubulin mRNA, implying that they have a role in the control of the polymerization of α/β-tubulin heterodimers.     

Antisense inhibition of the plastidial glucose-6-phosphate/phosphate translocator in Vicia seeds shifts cellular differentiation and promotes protein storage

The glucose-6-phosphate/phosphate translocator (GPT) acts as an importer of carbon into the plastid. Despite the potential importance of GPT for storage in crop seeds, its regulatory role in biosynthetic pathways that are active during seed development is poorly understood. We have isolated GPT1 from Vicia narbonensis and studied its role in seed development using a transgenic approach based on the seed-specific legumin promoter LeB4. GPT1 is highly expressed in vegetative sink tissues, flowers and young seeds. In the embryo, localized upregulation of GPT1 at the onset of storage coincides with the onset of starch accumulation. Embryos of transgenic plants expressing antisense GPT1 showed a significant reduction (up to 55%) in the specific transport rate of glucose-6-phosphate as determined using proteoliposomes prepared from embryos. Furthermore, amyloplasts developed later and were smaller in size, while the expression of genes encoding plastid-specific translocators and proteins involved in starch biosynthesis was decreased. Metabolite analysis and stable isotope labelling demonstrated that starch biosynthesis was also reduced, although storage protein biosynthesis increased. This metabolic shift was characterized by upregulation of genes related to nitrogen uptake and protein storage, morphological variation of the protein-storing vacuoles, and a crude protein content of mature seeds of transgenics that was up to 30% higher than in wild-type. These findings provide evidence that (1) the prevailing level of GPT1 abundance/activity is rate-limiting for the synthesis of starch in developing seeds, (2) GPT1 exerts a controlling function on assimilate partitioning into storage protein, and (3) GPT1 is essential for the differentiation of embryonic plastids and seed maturation.     

Jekyll encodes a novel protein involved in the sexual reproduction of barley

Cereal seed development depends on the intimate interaction of filial and maternal tissues, ensuring nourishment of the new generation. The gene jekyll, which was identified in barley (Hordeum vulgare), is preferentially expressed in the nurse tissues. JEKYLL shares partial similarity with the scorpion Cn4 toxin and is toxic when ectopically expressed in Escherichia coli and tobacco (Nicotiana tabacum). In barley, jekyll is upregulated in cells destined for autolysis. The gene generates a gradient of expression in the nucellar projection, which mediates the maternal-filial interaction during seed filling. Downregulation of jekyll by the RNA interference technique in barley decelerates autolysis and cell differentiation within the nurse tissues. Flower development and seed filling are thereby extended, and the nucellar projection no longer functions as the main transport route for assimilates. A slowing down in the proliferation of endosperm nuclei and a severely impaired ability to accumulate starch in the endosperm leads to the formation of irregular and small-sized seeds at maturity. Overall, JEKYLL plays a decisive role in the differentiation of the nucellar projection and drives the programmed cell death necessary for its proper function. We further suggest that cell autolysis during the differentiation of the nucellar projection allows the optimal provision of basic nutrients for biosynthesis in endosperm and embryo.     

Low-frequency component of photoplethysmogram reflects the autonomic control of blood pressure

The question of how much information the photoplethysmogram (PPG) signal contains on the autonomic regulation of blood pressure (BP) remains unsolved. This study aims to compare the low-frequency (LF) and high-frequency components of PPG and BP and assess their correlation with oscillations in interbeat (RR) intervals at similar frequencies. The PPG signal from the distal phalanx of the right index finger recorded using a reflective PPG sensor at green light, the BP signal from the left hand recorded using a Finometer, and RR intervals were analyzed. These signals were simultaneously recorded within 15 min in a supine resting condition in 17 healthy subjects (12 males and 5 females) aged 33 ± 9 years (mean ± SD). The study revealed the high coherence of LF components of PPG and BP with the LF component of RR intervals. The high-frequency components of these signals had low coherence. The analysis of the signal instantaneous phases revealed the presence of high-phase coherence between the LF components of PPG and BP. It is shown that the LF component of PPG is determined not only by local myogenic activity but also reflects the processes of autonomic control of BP.     

Cloning and expression of the tubulin genes in barley

Tubulins are encoded by small gene families in plants. Based on the barley EST collection, cDNAs for alpha-, beta-, and gamma-tubulins were selected. Five genes for alpha-tubulin, eight newly identified beta-tubulin sequences and one gamma-tubulin gene were found to be expressed in barley. In silico analysis of relative abundance of the distinct tubulin sequences among ESTs derived from different libraries revealed that the various tubulin genes differed in their level of expression, and to some extent were tissue specific.