Neutral Sites Research Articles

Faster-haplodiploid evolution under divergence-with-gene-flow: Simulations and empirical data from pine-feeding hymenopterans.

Although haplodiploidy is widespread in nature, the evolutionary consequences of this mode of reproduction are not well characterized. Here, we examine how genome-wide hemizygosity and a lack of recombination in haploid males affects genomic differentiation in populations that diverge via natural selection while experiencing gene flow. First, we simulated diploid and haplodiploid "genomes" (500-kb loci) evolving under an isolation-with-migration model with mutation, drift, selection, migration and recombination; and examined differentiation at neutral sites both tightly and loosely linked to a divergently selected site. As long as there is divergent selection and migration, sex-limited hemizygosity and recombination cause elevated differentiation (i.e., produce a "faster-haplodiploid effect") in haplodiploid populations relative to otherwise equivalent diploid populations, for both recessive and codominant mutations. Second, we used genome-wide single nucleotide polymorphism data to model divergence history and describe patterns of genomic differentiation between sympatric populations of Neodiprion lecontei and N. pinetum, a pair of pine sawfly species (order: Hymenoptera; family: Diprionidae) that are specialized on different pine hosts. These analyses support a history of continuous gene exchange throughout divergence and reveal a pattern of heterogeneous genomic differentiation that is consistent with divergent selection on many unlinked loci. Third, using simulations of haplodiploid and diploid populations evolving according to the estimated divergence history of N. lecontei and N. pinetum, we found that divergent selection would lead to higher differentiation in haplodiploids. Based on these results, we hypothesize that haplodiploids undergo divergence-with-gene-flow and sympatric speciation more readily than diploids.

Putative Phenotypically Neutral Genomic Insertion Points in Prokaryotes.

The barriers to effective genome editing in diverse prokaryotic organisms have been falling at an accelerated rate. As editing becomes easier in more organisms, quickly identifying genomic locations to insert new genetic functions without disrupting organism fitness becomes increasingly useful. When the insertion is noncoding DNA for applications such as information storage or barcoding, a neutral insertion point can be especially important. Here we describe an approach to identify putatively neutral insertion sites in prokaryotes. An algorithm (targetFinder) finds convergently transcribed genes with gap sizes within a specified range, and looks for annotations within the gaps. We report putative editing targets for 10 common synthetic biology chassis organisms, including coverage of available RNA-seq data, and provide software to apply to others. We further experimentally evaluate the neutrality of six identified targets in Escherichia coli through insertion of a DNA barcode. We anticipate this information and the accompanying tool will prove useful for synthetic biologists seeking neutral insertion points for genome editing.

The effects of weak selection on neutral diversity at linked sites.

The effects of selection on variability at linked sites have an important influence on levels and patterns of within-population variation across the genome. Most theoretical models of these effects have assumed that selection is sufficiently strong that allele frequency changes at the loci concerned are largely deterministic. These models have led to the conclusion that directional selection for selectively favorable mutations, or against recurrent deleterious mutations, reduces nucleotide site diversity at linked neutral sites. Recent work has shown, however, that fixations of weakly selected mutations, accompanied by significant stochastic changes in allele frequencies, can sometimes cause higher diversity at linked sites when compared with the effects of fixations of neutral mutations. This study extends this work by deriving approximate expressions for the mean conditional times to fixation and loss of mutations subject to selection, and analyzing the conditions under which selection increases rather than reduces these times. Simulations are used to examine the relations between diversity at a neutral site and the fixation and loss times of mutations at a linked site that is subject to selection. It is shown that the long-term level of neutral diversity can be increased over the purely neutral value by recurrent fixations and losses of linked, weakly selected dominant or partially dominant favorable mutations, or linked recessive or partially recessive deleterious mutations. The results are used to examine the conditions under which associative overdominance, as opposed to background selection, is likely to operate.

Mapping cross-variant neutralizing sites on the SARS-CoV-2 spike protein

ABSTRACT The emergence of multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern threatens the efficacy of currently approved vaccines and authorized therapeutic monoclonal antibodies (MAbs). It is hence important to continue searching for SARS-CoV-2 broadly neutralizing MAbs and defining their epitopes. Here, we isolate 9 neutralizing mouse MAbs raised against the spike protein of a SARS-CoV-2 prototype strain and evaluate their neutralizing potency towards a panel of variants, including B.1.1.7, B.1.351, B.1.617.1, and B.1.617.2. By using a combination of biochemical, virological, and cryo-EM structural analyses, we identify three types of cross-variant neutralizing MAbs, represented by S5D2, S5G2, and S3H3, respectively, and further define their epitopes. S5D2 binds the top lateral edge of the receptor-binding motif within the receptor-binding domain (RBD) with a binding footprint centred around the loop477–489, and efficiently neutralizes all variant pseudoviruses, but the potency against B.1.617.2 was observed to decrease significantly. S5G2 targets the highly conserved RBD core region and exhibits comparable neutralization towards the variant panel. S3H3 binds a previously unreported epitope located within the evolutionarily stable SD1 region and is able to near equally neutralize all of the variants tested. Our work thus defines three distinct cross-variant neutralizing sites on the SARS-CoV-2 spike protein, providing guidance for design and development of broadly effective vaccines and MAb-based therapies.

The Difference in the Proportions of Deleterious Variations within and between Populations Influences the Estimation of FST.

Estimating the extent of genetic differentiation between populations is an important measure in population genetics, ecology and evolutionary biology. The fixation index, or FST, is an important measure, which is routinely used to quantify this. Previous studies have shown that the FST estimated for selectively constrained regions was significantly lower than that estimated for neutral regions. By deriving the theoretical relationship between FST at neutral and constrained sites, we show that excess in the fraction of deleterious variations segregating within populations compared to those segregating between populations is the cause for the reduction in FST estimated at constrained sites. Using whole-genome data, our results revealed that the magnitude of reduction in FST estimates obtained for selectively constrained regions was much higher for distantly related populations compared to those estimated for closely related pairs. For example, the reduction was 47% for comparison between Europeans and Africans, 30% for the European and Asian comparison, 16% for the Northern and Southern European pair, and only 4% for the comparison involving two Southern European (Italian and Spanish) populations. Since deleterious variants are purged over time due to purifying selection, their contribution to the among-population diversity at constrained sites decreases with the increase in the divergence between populations. However, within-population diversities remain the same for all pairs compared; therefore, the FST estimated at constrained sites for distantly related populations are much smaller than those estimated for closely related populations. We obtained similar results when only the SNPs with similar allele frequencies at neutral and constrained sites were used. Our results suggest that the level of population divergence should be considered when comparing constrained site FST estimates from different pairs of populations.

Heterogeneity in effective size across the genome: effects on the inverse instantaneous coalescence rate (IICR) and implications for demographic inference under linked selection.

The relative contribution of selection and neutrality in shaping species genetic diversity is one of the most central and controversial questions in evolutionary theory. Genomic data provide growing evidence that linked selection, i.e. the modification of genetic diversity at neutral sites through linkage with selected sites, might be pervasive over the genome. Several studies proposed that linked selection could be modeled as first approximation by a local reduction (e.g. purifying selection, selective sweeps) or increase (e.g. balancing selection) of effective population size (Ne). At the genome-wide scale, this leads to variations of Ne from one region to another, reflecting the heterogeneity of selective constraints and recombination rates between regions. We investigate here the consequences of such genomic variations of Ne on the genome-wide distribution of coalescence times. The underlying motivation concerns the impact of linked selection on demographic inference, because the distribution of coalescence times is at the heart of several important demographic inference approaches. Using the concept of inverse instantaneous coalescence rate, we demonstrate that in a panmictic population, linked selection always results in a spurious apparent decrease of Ne along time. Balancing selection has a particularly large effect, even when it concerns a very small part of the genome. We also study more general models including genuine population size changes, population structure or transient selection and find that the effect of linked selection can be significantly reduced by that of population structure. The models and conclusions presented here are also relevant to the study of other biological processes generating apparent variations of Ne along the genome.

SARS-CoV-2 mRNA vaccine induces robust specific and cross-reactive IgG and unequal neutralizing antibodies in naive and previously infected people

Understanding vaccine-mediated protection against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is critical to overcoming the global coronavirus disease 2019 (COVID-19) pandemic. We investigate mRNA-vaccine-induced antibody responses against the reference strain, seven variants, and seasonal coronaviruses in 168 healthy individuals at three time points: before vaccination, after the first dose, and after the second dose. Following complete vaccination, both naive and previously infected individuals developed comparably robust SARS-CoV-2 spike antibodies and variable levels of cross-reactive antibodies to seasonal coronaviruses. However, the strength and frequency of SARS-CoV-2 neutralizing antibodies in naive individuals were lower than in previously infected individuals. After the first vaccine dose, one-third of previously infected individuals lacked neutralizing antibodies; this was improved to one-fifth after the second dose. In all individuals, neutralizing antibody responses against the Alpha and Delta variants were weaker than against the reference strain. Our findings support future tailored vaccination strategies against emerging SARS-CoV-2 variants as mRNA-vaccine-induced neutralizing antibodies are highly variable among individuals.

Nucleic acid delivery of immune-focused SARS-CoV-2 nanoparticles drives rapid and potent immunogenicity capable of single-dose protection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines may target epitopes that reduce durability or increase the potential for escape from vaccine-induced immunity. Using synthetic vaccinology, we have developed rationally immune-focused SARS-CoV-2 Spike-based vaccines. Glycans can be employed to alter antibody responses to infection and vaccines. Utilizing computational modeling and in vitro screening, we have incorporated glycans into the receptor-binding domain (RBD) and assessed antigenic profiles. We demonstrate that glycan-coated RBD immunogens elicit stronger neutralizing antibodies and have engineered seven multivalent configurations. Advanced DNA delivery of engineered nanoparticle vaccines rapidly elicits potent neutralizing antibodies in guinea pigs, hamsters, and multiple mouse models, including human ACE2 and human antibody repertoire transgenics. RBD nanoparticles induce high levels of cross-neutralizing antibodies against variants of concern with durable titers beyond 6 months. Single, low-dose immunization protects against a lethal SARS-CoV-2 challenge. Single-dose coronavirus vaccines via DNA-launched nanoparticles provide a platform for rapid clinical translation of potent and durable coronavirus vaccines.

African experiences and alternativity in International Relations theorizing about security

Abstract Deconstructing International Relations (IR) episteme acknowledges its generation of power imbalances in security knowledge that relegate African experiences to the margins of global politics. Central to this process of relegation is a pervasive ‘methodological whiteness’, which, while eliding coloniality and racism, projects white experience as a universal perspective. Accompanying this Eurocentric bias has been the intrusive projection of the Weberian state as the most effective site for security governance and conflict prevention on a continent with states that are characterized by a hybridity of political orders, which deviate substantially from the ideal-type state that they seek to mimic. Not only has this resulted in disastrous policies in many parts of Africa, but critical questions arise as to the relevance of conventional IR and security studies as neutral sites for dispassionate knowledge production and policy-making on African security, thereby necessitating alternative perspectives. This article reflects on the ways in which IR and security studies have been responsible, in part, for the production of a racialized mode of security knowledge generation that obfuscates the security policies and experiences of people in African locales. It draws on insights from post-colonial discourses and the episteme of alternativity to explore how the study of events and processes in Africa in a theoretically conscious manner could advance IR scholarship as a whole. It contends that incorporating African experiences as they manifest through hybrid security orders can broaden the empirical base for IR theorizing about security since they offer another perspective outside the conventional western assumptions and experiences.

SweepCluster: A SNP clustering tool for detecting gene-specific sweeps in prokaryotes

BackgroundThe gene-specific sweep is a selection process where an advantageous mutation along with the nearby neutral sites in a gene region increases the frequency in the population. It has been demonstrated to play important roles in ecological differentiation or phenotypic divergence in microbial populations. Therefore, identifying gene-specific sweeps in microorganisms will not only provide insights into the evolutionary mechanisms, but also unravel potential genetic markers associated with biological phenotypes. However, current methods were mainly developed for detecting selective sweeps in eukaryotic data of sparse genotypes and are not readily applicable to prokaryotic data. Furthermore, some challenges have not been sufficiently addressed by the methods, such as the low spatial resolution of sweep regions and lack of consideration of the spatial distribution of mutations.ResultsWe proposed a novel gene-centric and spatial-aware approach for identifying gene-specific sweeps in prokaryotes and implemented it in a python tool SweepCluster. Our method searches for gene regions with a high level of spatial clustering of pre-selected polymorphisms in genotype datasets assuming a null distribution model of neutral selection. The pre-selection of polymorphisms is based on their genetic signatures, such as elevated population subdivision, excessive linkage disequilibrium, or significant phenotype association. Performance evaluation using simulation data showed that the sensitivity and specificity of the clustering algorithm in SweepCluster is above 90%. The application of SweepCluster in two real datasets from the bacteria Streptococcus pyogenes and Streptococcus suis showed that the impact of pre-selection was dramatic and significantly reduced the uninformative signals. We validated our method using the genotype data from Vibrio cyclitrophicus, the only available dataset of gene-specific sweeps in bacteria, and obtained a concordance rate of 78%. We noted that the concordance rate could be underestimated due to distinct reference genomes and clustering strategies. The application to the human genotype datasets showed that SweepCluster is also applicable to eukaryotic data and is able to recover 80% of a catalog of known sweep regions.ConclusionSweepCluster is applicable to a broad category of datasets. It will be valuable for detecting gene-specific sweeps in diverse genotypic data and provide novel insights on adaptive evolution.

Spray-dryer feed preparation: Enzymatic degradation of glucomannan for iron nanoencapsulation

<abstract> <p>Viscosity of glucomannan (GM) needs to be modified to support its application for spray drying encapsulation. The purpose of this study was to investigate degradation of GM using cellulase that fulfills viscosity in a spray-dryer specification. This hydrolyzed glucomannan (HGM) was subsequently spray-dried for encapsulating iron. Lower initial GM concentrations (0.5–1%) reached approximately 0.30 Pa·s which allowed to be spray-dried after 100 min degradation using 10 mg/L cellulase. Meanwhile, viscosity of 1.5% and 1.7% GM did not reach the target viscosity even after 300 min. The n<sup>th</sup>-order model was the most suitable model which fitted viscosity reduction of ≤1.5% initial GM concentration (coefficient of determination, R<sup>2</sup> > 0.98), whereas the Mahammad model fitted the viscosity reduction of 1.75% initial GM concentration (R<sup>2</sup> = 0.99). Hydrolysis decreased the degree of polymerization and surface tension but increased the antioxidant activities of HGM. Smaller molecules of the polysaccharides were released after hydrolysis. Particles of encapsulated iron using HGM were more hydrophilic than those using GM. The iron tended to have a higher release rate at pH 6.8 than at pH 1.2 in the first 40 min. Hence, the HGM showed its ability to act as a control release matrix for the iron that needs a protection in the acid environment, and delivers them to the neutral site for absorption. Nanoencapsulation using 0.35 Pa·s viscosity of HGM was able to have 84% yield, 96.41% encapsulation efficiency, and 10% moisture content. Particle size of the iron encapsulation was dominated by 341.99 nm-diameter. This study shows a potency to use an appropriate viscosity of HGM which not only allows to be spray-dried but also support in protecting the iron as aimed by encapsulation the iron. Performances and properties of this matrix on encapsulating other bioactive compounds become future study.</p> </abstract>

Context-Dependent Mutation Dynamics, Not Selection, Explains the Codon Usage Bias of Most Angiosperm Chloroplast Genes

Two competing proposals about the degree to which selection affects codon usage of angiosperm chloroplast genes are examined. The first, based on observations that codon usage does not match expectations under the naïve assumption that base composition will be identical at all neutral sites, is that selection plays a significant role. The second is that codon usage is determined almost solely by mutation bias and drift, with selection influencing only one or two highly expressed genes, in particular psbA. First it is shown that, as a result of an influence of neighboring base composition on mutation dynamics, compositional biases are expected to be widely divergent at different sites in the absence of selection. The observed mutation properties are then used to predict expected neutral codon usage biases and to show that observed deviations from the naïve expectations are in fact expected given the context-dependent mutational dynamics. It is also shown that there is a match between the observed and expected codon usage when context effects are taken into consideration, with psbA being a notable exception. Overall, the data support the model that selection is not a widespread factor affecting the codon usage of angiosperm chloroplast genes and highlight the need to have an accurate model of mutational dynamics.

Overexpression of Cu/Zn Superoxide Dismutase (Cu/Zn SOD) in Synechococcus elongatus PCC 7942 for Enhanced Azo Dye Removal through Hydrogen Peroxide Accumulation.

Simple SummarySynthetic azo dyes are used in various industries like apparel, food, paper, etc. The improper discharge of these recalcitrant dyes poses a serious threat to the environment. However, in nature, certain microorganisms including cyanobacteria can degrade these recalcitrant compounds by producing various reactive oxygen species (ROS), particularly by hydrogen peroxide (H2O2). This study aimed at developing a genetically modified cyanobacterium for better H2O2 accumulation that results due to superoxide radicals dismutation by enzyme superoxide dismutase (SOD). The modified strain (MS-sodC+) was created by integrating Cu/Zn SOD gene (sodC) from another cyanobacterium, and its expression was driven by a strong constitutive psbA gene promoter. The modified strain (MS-sodC+) resulted in over-accumulation of H2O2 during azo dye treatment with a higher rate of dye removal than the wild-type strain (WS-sodC). Therefore, to encourage cyanobacteria for biodegradation of toxic azo dyes faster than the natural rate enhanced H2O2 accumulation through SODs, overexpression may serve as a valuable bioremediation tool.Discharge of recalcitrant azo dyes to the environment poses a serious threat to environmental health. However certain microorganisms in nature have developed their survival strategies by degrading these toxic dyes. Cyanobacteria are one such prokaryotic, photosynthetic group of microorganisms that degrade various xenobiotic compounds, due to their capability to produce various reactive oxygen species (ROS), and particularly the hydrogen peroxide (H2O2) when released in their milieu. The accumulation of H2O2 is the result of the dismutation of superoxide radicals by the enzyme superoxide dismutase (SOD). In this study, we have genetically modified the cyanobacterium Synechococcus elongatus PCC 7942 by integrating Cu/Zn SOD gene (sodC) from Synechococcus sp. PCC 9311 to its neutral site through homologous recombination. The overexpression of sodC in the derivative strain was driven using a strong constitutive promoter of the psbA gene. The derivative strain resulted in constitutive production of sodC, which was induced further during dye-treated growth. The genetically engineered Synechococcus elongatus PCC 7942 (MS-sodC+) over-accumulated H2O2 during azo dye treatment with a higher dye removal rate than the wild-type strain (WS-sodC−). Therefore, enhanced H2O2 accumulation through SODs overexpression in cyanobacteria may serve as a valuable bioremediation tool.

Systematic Engineering of Synechococcus elongatus UTEX 2973 for Photosynthetic Production of l-Lysine, Cadaverine, and Glutarate.

Amino acids and related targets are typically produced by well-characterized heterotrophs including Corynebacterium glutamicum and Escherichia coli. Cyanobacteria offer an opportunity to supplant these sugar-intensive processes by instead directly utilizing atmospheric CO2 and sunlight. Synechococcus elongatus UTEX 2973 (hereafter UTEX 2973) is a particularly promising photoautotrophic platform due to its fast growth rate. Here, we first engineered UTEX 2973 to overproduce l-lysine (hereafter lysine), after which both cadaverine and glutarate production were achieved through further pathway engineering. To facilitate metabolic engineering, the relative activities of a subset of previously uncharacterized promoters were investigated, in each case, while also comparing the effects of both chromosomal (from neutral site NS3) and episomal (from pAM4788) expressions. Using these parts, lysine overproduction in UTEX 2973 was engineered by introducing a feedback-resistant copy of aspartate kinase (encoded by lysCfbr) and a lysine exporter (encoded by ybjE), both from E. coli. While chromosomal expression resulted in lysine production up to just 325.3 ± 14.8 mg/L after 120 h, this was then increased to 556.3 ± 62.3 mg/L via plasmid-based expression, also surpassing prior reports of photoautotrophic lysine bioproduction. Lastly, additional products of interest were then targeted by modularly extending the lysine pathway to glutarate and cadaverine, two 5-carbon, bioplastic monomers. By this approach, glutarate has so far been produced at final titers reaching 67.5 ± 2.2 mg/L by 96 h, whereas cadaverine has been produced at up to 55.3 ± 6.7 mg/L. Overcoming pathway and/or transport bottlenecks, meanwhile, will be important to improving upon these initial outputs.

Quantitative spatial and temporal assessment of regulatory element activity in zebrafish

Mutations or genetic variation in noncoding regions of the genome harbouring cis-regulatory elements (CREs), or enhancers, have been widely implicated in human disease and disease risk. However, our ability to assay the impact of these DNA sequence changes on enhancer activity is currently very limited because of the need to assay these elements in an appropriate biological context. Here, we describe a method for simultaneous quantitative assessment of the spatial and temporal activity of wild-type and disease-associated mutant human CRE alleles using live imaging in zebrafish embryonic development. We generated transgenic lines harbouring a dual-CRE dual-reporter cassette in a pre-defined neutral docking site in the zebrafish genome. The activity of each CRE allele is reported via expression of a specific fluorescent reporter, allowing simultaneous visualisation of where and when in development the wild-type allele is active and how this activity is altered by mutation.

Facile synthesis of MIL-100 metal-organic framework via heatless technique for the adsorptive treatment of cationic and anionic pollutants

The facile synthesis of an iron-based metal-organic framework, MIL-100(Fe) has been successfully conducted via a heatless water-based technique. The unique features have been evaluated with respect to the X-ray diffraction, field emission scanning electron microscopy, nitrogen adsorption-desorption analysis, Fourier transform infrared spectroscopy, and zero point of charge measurement. The adsorptive potential was examined using the cationic (methylene blue, MB) and anionic (naproxen, NPX) water pollutants. The synthesized MIL-100(Fe) sample, MIL-100(FeSO 4 ), owned a crystalline microporous-mesoporous structure, with a large BET surface area of 1984 m 2 /g and total pore volume of 1.096 cm 3 /g. The equilibrium data best conformed to the Langmuir-Freundlich isotherm and pseudo-second order kinetic model, with the maximum adsorption capacity for MB and NPX of 568.1 mg/g and 148.8 mg/g, respectively. Thermodynamic analysis revealed the favorable energetics (Δ G < 0 and Δ S > 0), endothermic (Δ H > 0 for MB) and exothermic nature (Δ H < 0 for NPX) of the adsorption process. Negligible degradation of the adsorptive performance was recorded under high ionic strength solutions and simulated wastewaters. MIL-100(FeSO 4 ) demonstrated great regenerative potential by ethanol stripping for at least 5 regeneration cycles. The present findings provide an invaluable insight into the green synthesis technique of MIL-100(Fe), with high upscaling prospects. Imparted with different surface anionicity and electrically neutral functional sites, MIL-100(FeSO 4 ) has emerged to be a potent adsorbent for the successful treatment of both cationic and anionic water pollutants, even under high-strength water samples with complex water matrices.

Selection, recombination, and the ancestral initiation graph

Recently, the selection–recombination equation with a single selected site and an arbitrary number of neutral sites was solved by Alberti and Baake (2021) by means of the ancestral selection–recombination graph. Here, we introduce a more accessible approach, namely the ancestral initiation graph. The construction is based on a discretisation of the selection–recombination equation. We apply our method to systematically explain a long-standing observation concerning the dynamics of linkage disequilibrium between two neutral loci hitchhiking along with a selected one. In particular, this clarifies the nontrivial dependence on the position of the selected site.

Impact of glgA1, glgA2 or glgC overexpression on growth and glycogen production in Synechocystis sp. PCC 6803

Low production rates are still one limiting factor for the industrial climate-neutral production of biovaluable compounds in cyanobacteria. Next to optimized cultivation conditions, new production strategies are required. Hence, the use of established molecular tools could lead to increased product yields in the cyanobacterial model organism Synechocystis sp. PCC6803. Its main storage compound glycogen was chosen to be increased by the use of these tools. In this study, the three genes glgC, glgA1 and glgA2, which are part of the glycogen synthesis pathway, were combined with the Pcpc560 promoter and the neutral cloning site NSC1. The complete genome integration, protein formation, biomass production and glycogen accumulation were determined to select the most productive transformants. The overexpression of glgA2 did not increase the biomass or glycogen production in short-term trials compared to the other two genes but caused transformants death in long-term trials. The transformants glgA1_11 and glgC_2 showed significantly increased biomass (1.6-fold - 1.7-fold) and glycogen production (3.5-fold - 4-fold) compared to the wild type after 96 h making them a promising energy source for further applications. Those could include for example a two-stage production process, with first energy production (glycogen) and second increased product formation (e.g. ethanol).

Structural analysis of surprisingly formed CuII cubane through the specific cleavage of >C[dbnd]N[sbnd] and >C[sbnd]S[sbnd] of a Schiff base ligand and its biological activities

Extraordinary specific breaking of the carbon-sulfur linkage of the thiosemicarbazone moiety from a Schiff base has been watched the blue, bringing about the development of a four coordinated tetra CuII cubane containing triphenyl phosphine and µ3-S as ligands. At the same time, the ketimine group of the Schiff base ligands also got ruptured to regenerate the diketone used for the synthesis of thiosemicarbazone ligand. The synthesized complex was spectrally and structurally investigated. The crystallographic information reveals that the complex is having the shape of a cubane, where as the alternate four corners were occupied by tricoordinated copper and the other corners are by µ3-S respectively. µ3-S behaves as a ligand which is having the binegative site and neutral site to get bonded with the copper as bridging ligand. Antimicrobial and antioxidant efficacy were explored and shows a better results than the controls used.

Evidence for a force favoring GC over AT at short intronic sites in Drosophila simulans and Drosophila melanogaster.

Population genetics studies often make use of a class of nucleotide site free from selective pressures, in order to make inferences about population size changes or natural selection at other sites. If such neutral sites can be identified, they offer the opportunity to avoid any confounding effects of selection. Here, we investigate evolution at putatively neutrally evolving short intronic sites in natural populations of Drosophila melanogaster and Drosophila simulans, in order to understand the properties of spontaneous mutations and the extent of GC-biased gene conversion in these species. Use of data on the genetics of natural populations is advantageous because it integrates information from large numbers of individuals over long timescales. In agreement with direct evidence from observations of spontaneous mutations in Drosophila, we find a bias in the spectrum of mutations toward AT basepairs. In addition, we find that this bias is stronger in the D. melanogaster lineage than in the D. simulans lineage. The evidence for GC-biased gene conversion in Drosophila has been equivocal. Here, we provide evidence for a weak force favoring GC in both species, which is correlated with the GC content of introns and is stronger in D. simulans than in D. melanogaster.