Food availability modulates the effects of maternal antibodies on growth and immunity in young feral pigeons

It is now widely acknowledged that mothers can transfer their own immune experience to their progeny through the allocation of specific maternal antibodies (hereafter referred as MatAb) that can shape offspring phenotype and affect their fitness. However, the importance of environmental variability in modulating the effects of MatAb on offspring traits is still elusive. Using an experimental approach, we investigated how food availability interacted with MatAb to solve the trade‐off between humoral immunity and growth in young feral pigeons Columba livia. Results show that the inhibitory effect of MatAb on the humoral response of chicks was detected regardless of the food treatment. In addition, body mass growth was higher in chicks receiving lower amounts of maternal antibodies but only in chicks of the ad libitum food treatment. This contradicts previous studies and suggests that the transfer of MatAb could entail some costs for chicks and reduce their growth. Taken together these results reinforce the idea that the maternal antibodies play a central role in shaping offspring life‐history traits but that their adaptive value is highly dependent on the environmental context in which they are transmitted by the mother.     

Exploration of the Arrest Peptide Sequence Space Reveals Arrest-enhanced Variants

Translational arrest peptides (APs) are short stretches of polypeptides that induce translational stalling when synthesized on a ribosome. Mechanical pulling forces acting on the nascent chain can weaken or even abolish stalling. APs can therefore be used as in vivo force sensors, making it possible to measure the forces that act on a nascent chain during translation with single-residue resolution. It is also possible to score the relative strengths of APs by subjecting them to a given pulling force and ranking them according to stalling efficiency. Using the latter approach, we now report an extensive mutagenesis scan of a strong mutant variant of the Mannheimia succiniciproducens SecM AP and identify mutations that further increase the stalling efficiency. Combining three such mutations, we designed an AP that withstands the strongest pulling force we are able to generate at present. We further show that diproline stretches in a nascent protein act as very strong APs when translation is carried out in the absence of elongation factor P. Our findings highlight critical residues in APs, show that certain amino acid sequences induce very strong translational arrest and provide a toolbox of APs of varying strengths that can be used for in vivo force measurements.     

Opportunities of marker‐assisted selection for rice fragrance through marker–trait association analysis of microsatellites and gene‐based markers

Developing fragrant rice through marker‐assisted/aided selection (MAS) is an economical and profitable approach worldwide for the enrichment of an elite genetic background with a pleasant aroma. The PCR‐based DNA markers that distinguish the alleles of major fragrance genes in rice have been synthesised to develop rice scent biofortification through MAS. Thus, the present study examined the aroma biofortification potential of these co‐dominant markers in a germplasm panel of 189 F₂ progeny developed from crosses between a non‐aromatic variety (MR84) and a highly aromatic but low‐yielding variety (MRQ74) to determine the most influential diagnostic markers for fragrance biofortification. The SSRs and functional DNA markers RM5633 (on chromosome 4), RM515, RM223, L06, NKSbad2, FMbadh2‐E7, BADEX7‐5, Aro7 and SCU015RM (on chromosome 8) were highly associated with the 2AP (2‐acetyl‐1‐pyrroline) content across the population. The alleles traced via these markers were also in high linkage disequilibrium (R² > 0.70) and explained approximately 12.1, 27.05, 27.05, 27.05, 25.42, 25.42, 20.53, 20.43 and 20.18% of the total phenotypic variation observed for these biomarkers, respectively. F₂ plants harbouring the favourable alleles of these effective markers produced higher levels of fragrance. Hence, these rice plants can be used as donor parents to increase the development of fragrance‐biofortified tropical rice varieties adapted to growing conditions and consumer preferences, thus contributing to the global rice market.     

An electrochemical impedance spectroscopy (EIS) assay measuring the calcification inhibition capacity in biological fluids

Pathological calcification of the cardiovascular system is one of the major causes of high mortality and morbidity in dialysis patients. The inhibition of ectopic calcification relies (I) on the formation of calciprotein particles (CPPs), nanospherical complexes of calcium phosphate mineral, fetuin-A and other acidic serum proteins, and (II) on the stabilization of calcium phosphate prenucleation clusters by fetuin-A monomers. In supersaturated serum, mineral ion aggregation leads to a change in the electrical impedance. In this work, we present a method based on electrochemical impedance spectroscopy (EIS) to establish an impedance trace of mineral ion clustering in vitro. In the presence of 20 μM of serum protein fetuin-A, a prototypic calcification inhibitor, we measured a change in impedance (Δ(R)) of 195.52 ± 27.78%Ω compared to 430.41 ± 11.36%Ω in inhibitor-free samples. We also identified a CPP-formation dependency on the actual content of ions and protein in the samples under investigation. Two-step ripening of CPP was also observed. The presented method may form the basis of a simple label-free bedside or online test to be used in routine clinical practice for estimating the calcification risk in serum.     

Antimycobacterial activity: synthesis of novel 3-(substituted phenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]isoxazole analogues

In this study, a series of novel 3-(substituted phenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]isoxazole analogues were synthesized and evaluated for antimycobacterial activity against Mycobacterium tuberculosis (MTB) H(37)Rv and isoniazid resistant M. tuberculosis (INHR-MTB). All the newly synthesized compounds were showing moderate to high inhibitory activities. The compound 6,7-dimethoxy-3-(4-chloro phenyl)-4H-indeno[1,2-c]isoxazole (4b) was found to be the most promising compound, active against MTB H(37)Rv and INHR-MTB with minimum inhibitory concentrations of 0.22 and 0.34 μM.     

Intraspecific variation in the venom of the vermivorous cone snail Conus vexillum

A combination of proteomic and biochemical assays was used to examine variations in the venom of Conus vexillum taken from two locations (Hurgada and Sharm El-Shaikh) in the Red Sea, Egypt. Using MALDI/TOF-MS, a remarkable degree of intra-species variation between venom samples from both locations was identified. To evaluate variability in the cytotoxic effects of Conus venom, mice were injected with the same dose from each location. The oxidative stress biomarkers [malondialdehyde (MDA), protein carbonyl content (PCC)], antioxidants [glutathione (GSH), superoxide dismutase (SOD), catalase (CAT)], total antioxidant capacity (TAC) and nitric oxide (NO), were measured 3, 6, 9 and 12 h post venom injection. The venoms induced a significant increase in the levels of PCC, MDA, NO, GSH and CAT. The venoms significantly inhibited the activity of SOD and reduced the TAC. Toxicological data showed that the venom obtained from Hurgada was more potent than that obtained from Sharm El-Shaikh. It can be concluded that: (1) the venom of the same Conus species from different regions is highly diversified (2) the venoms from different locations reflect clear differences in venom potency and (3) the cytotoxic effects of C. vexillum venom can be attributed to its ability to induce oxidative stress.     

Au-Catalyzed Silicon Nanoneedles Synthesized from Pure Silane Gas at Various RF Powers on Silicon Substrate by VHF-PECVD

Silicon nanonowires (SiNWs) were synthesized with approximately 100 nm/min by very-high-frequency plasma-enhanced chemical vapor deposition method via a vapor–liquid–solid mechanism. Pure silane gas was deposited on Au-coated silicon substrates at various radio frequency (RF) powers varied from 5 to 20 W, keeping other deposition parameters constant. Synthesized SiNWs were needle-like shape with an ultra-sharp tip diameter of about 10 nm and a length about 3 μm, which differs from the standard cylindrical nanowire produced by similar techniques. Furthermore, it was shown that the average length of nanoneedles augmented with the increase of RF power. High-resolution transition electron microscopy displayed that the nanowires were composed of a crystalline Si core with an amorphous oxide shell. Raman spectroscopy also revealed the presence of crystalline Si in the grown Si nanoneedles.     

Heterologous Expression of Human Cytochromes P450 2D6 and CYP3A4 in <Emphasis Type="Italic">Escherichia coli</Emphasis> and Their Functional Characterization

This study aimed to express two major drug-metabolizing human hepatic cytochromes P450 (CYPs), CYP2D6 and CYP3A4, together with NADPH-cytochrome P450 oxidoreductase (OxR) in Escherichia coli and to evaluate their catalytic activities. Full length cDNA clones of both isoforms in which the N-terminus was modified to incorporate bovine CYP17α sequence were inserted into a pCWori⁺ vector. The modified CYP cDNAs were subsequently expressed individually, each together with OxR by means of separate, compatible plasmids with different antibiotic selection markers. The expressed proteins were evaluated by immunoblotting and reduced CO difference spectral scanning. Enzyme activities were examined using high performance liquid chromatography (HPLC) assays with probe substrates dextromethorphan and testosterone for CYP2D6 and CYP3A4, respectively. Results from immunoblotting demonstrated the presence of both CYP proteins in bacterial membranes and reduced CO difference spectra of the cell preparations exhibited the characteristic absorbance peak at 450 nm. Co-expressed OxR also demonstrated an activity level comparable to literature values. Kinetic parameters, K_m and V_max values determined from the HPLC assays also agreed well with literature values. As a conclusion, the procedures described in this study provide a relatively convenient and reliable means of producing catalytically active CYP isoforms suitable for drug metabolism and interaction studies.