Gene duplication in the genome of parasitic Giardia lamblia

<p>Abstract</p> <p>Background</p> <p><it>Giardia </it>are a group of widespread intestinal protozoan parasites in a number of vertebrates. Much evidence from <it>G. lamblia </it>indicated they might be the most primitive extant eukaryotes. When and how such a group of the earliest branching unicellular eukaryotes developed the ability to successfully parasitize the latest branching higher eukaryotes (vertebrates) is an intriguing question. Gene duplication has long been thought to be the most common mechanism in the production of primary resources for the origin of evolutionary novelties. In order to parse the evolutionary trajectory of <it>Giardia </it>parasitic lifestyle, here we carried out a genome-wide analysis about gene duplication patterns in <it>G. lamblia</it>.</p> <p>Results</p> <p>Although genomic comparison showed that in <it>G. lamblia </it>the contents of many fundamental biologic pathways are simplified and the whole genome is very compact, in our study 40% of its genes were identified as duplicated genes. Evolutionary distance analyses of these duplicated genes indicated two rounds of large scale duplication events had occurred in <it>G. lamblia </it>genome. Functional annotation of them further showed that the majority of recent duplicated genes are VSPs (Variant-specific Surface Proteins), which are essential for the successful parasitic life of <it>Giardia </it>in hosts. Based on evolutionary comparison with their hosts, it was found that the rapid expansion of VSPs in <it>G. lamblia </it>is consistent with the evolutionary radiation of placental mammals.</p> <p>Conclusions</p> <p>Based on the genome-wide analysis of duplicated genes in <it>G. lamblia</it>, we found that gene duplication was essential for the origin and evolution of <it>Giardia </it>parasitic lifestyle. The recent expansion of VSPs uniquely occurring in <it>G. lamblia </it>is consistent with the increment of its hosts. Therefore we proposed a hypothesis that the increment of <it>Giradia </it>hosts might be the driving force for the rapid expansion of VSPs.</p

Study on vibration characteristics of rolling mill based on vibration absorber

The vertical vibration often occurs during the rolling production, which has an influence on the accuracy of rolling mill. In order to effectively suppress the vertical vibration of the rolling equipment, the rolling mill model with vibration absorber device was established. Based on the main resonance singularity of the rolling mill system, the best combination of opening parameters was obtained. The best combination of opening parameters helps the rolling mill system work in a stable area. Finally, the effects of different vibration absorber parameters on the vibration characteristics of the rolling mill system were analyzed. Results show that the vibration absorber device can effectively improve the stability of the rolling mill system

Dynamics testing and simulation of inflatable deployable

The inflatable deployablemembrane antenna structures have many advantages such as small folding size, high reliability and low cost. The structure mainly consists of its center hub, thin-plate ribs, inflatable thermo-curing torus, reflected membrane and inflation control system. This paper establishes a deployable system to simulate zero-gravity based on the parabolic membrane antenna with inflatable torus and tests the deployable process. The shell-membranes finite element model of the antenna structuresis modeled to simulateof the dynamics charactersof the structure. After that the effectsof the different inflatable pressure inside its support torus, the temperature of thermos-curing on the dynamic characteristics are also discussed.Finally,the dynamic charactersof the inflatable antenna was tested on the condition of the horizontal suspension system with 12 elastic strings and the fully structural vibrational frequency were given, and the mode of vibration and damping ratio was verified to the correctness of the simulation method. These results provide the reference for the design of inflatable deployment antenna structures

Differential selection on gene translation efficiency between the filamentous fungus Ashbya gossypii and yeasts

<p>Abstract</p> <p>Background</p> <p>The filamentous fungus <it>Ashbya gossypii </it>grows into a multicellular mycelium that is distinct from the unicellular morphology of its closely related yeast species. It has been proposed that genes important for cell cycle regulation play central roles for such phenotypic differences. Because <it>A. gossypii </it>shares an almost identical set of cell cycle genes with the typical yeast <it>Saccharomyces cerevisiae</it>, the differences might occur at the level of orthologous gene regulation. Codon usage patterns were compared to identify orthologous genes with different gene regulation between <it>A. gossypii </it>and nine closely related yeast species.</p> <p>Results</p> <p>Here we identified 3,151 orthologous genes between <it>A. gossypii </it>and nine yeast species. Two groups of genes with significant differences in codon usage (gene translation efficiency) were identified between <it>A. gossypii </it>and yeasts. 333 genes (Group I) and 552 genes (Group II) have significantly higher translation efficiency in <it>A. gossypii </it>and yeasts, respectively. Functional enrichment and pathway analysis show that Group I genes are significantly enriched with cell cycle functions whereas Group II genes are biased toward metabolic functions.</p> <p>Conclusion</p> <p>Because translation efficiency of a gene is closely related to its functional importance, the observed functional distributions of orthologous genes with different translation efficiency might account for phenotypic differentiation between <it>A. gossypii </it>and yeast species. The results shed light on the mechanisms for pseudohyphal growth in pathogenic yeast species.</p

Fault-Tolerant Converter with a Modular Structure for HVDC Power Transmitting Applications

For the high-voltage direct-current (HVDC) power transmission system of offshore wind power, dc/dc converters are the potential solution to collect the power generated by off-shore wind farms to HVDC terminals. The converters operate with high-voltage gain, high efficiency, and fault tolerance over a wide range of operating conditions. In this paper, an isolated ultrahigh step-up dc/dc converter with a scalable modular structure is proposed for HVDC offshore wind power collection. A flyback-forward converter is employed as the power cell to form the expandable electrically isolated modular dc/dc converter. The duty ratio and phase-shift angle control are also developed for the proposed converter. Fault-tolerant characteristics of the converter are illustrated through the redundancy operation and fault-ride-through tests. Redundancy operation is designed to maintain high operation efficiency of the converters and fault-ride-through operation improves the converter reliability under harsh operating conditions. Analytical studies are carried out, and a 750-W prototype with three modular cells is built and experimentally tested to verify the performance of the proposed modular dc/dc converter

Serum 25(OH)D levels are associated with disease activity and renal involvement in initial-onset childhood systemic lupus erythematosus

BackgroundVitamin D deficiency is common in patients with systemic lupus erythematosus (SLE) and may affect their disease activity and severity.ObjectiveThis study aims to assess the vitamin D status in patients with initial-onset SLE during childhood and its association with the clinical and laboratory markers of disease activity.MethodThis is a retrospective study that includes 168 patients with initial-onset SLE during childhood and 109 healthy children as controls. Clinical and laboratory data were recorded. The area under the curve (AUC) method was used to evaluate the efficacy of double-stranded deoxyribonucleic acid (dsDNA), lower 25(OH)D and complement 3 (C3) alone and in combination to diagnose the presence of renal damage in children with SLE.ResultCompared with the controls (25.53 ± 7.02 ng/ml), patients with initial-onset SLE during childhood have lower serum 25(OH)D levels (18.63 ± 5.32 ng/ml) (P &lt; 0.05). Among patients with initial-onset SLE during childhood, SLEDAI-2K scores are significantly higher in the vitamin D insufficiency (median = 14.5) and vitamin D deficiency (median = 14.0) groups than in the vitamin D sufficiency group (median = 9.0) (P &lt; 0.05). Patients with initial-onset SLE during childhood with lower 25(OH)D levels are more likely to have lupus nephritis (LN) and a higher SDI score (P &lt; 0.05). Compared with patients with other types of LN (16.69 ± 3.90 ng/ml), patients with type V LN have lower levels of 25(OH)D (12.27 ± 3.53 ng/ml) (P &lt; 0.05). The AUC was 0.803 when dsDNA antibody, 25(OH)D level and C3 were used in combination to diagnose LN in patients with SLE.ConclusionVitamin D deficiency and insufficiency are closely related to an increase in SLEDAI and SDI scores. Significant decrease in vitamin D level is a risk factor for LN

Assembly and analysis of the genome sequence of the yeast Brettanomyces naardenensis CBS 7540

Brettanomyces naardenensis is a spoilage yeast with potential for biotechnological applications for production of innovative beverages with low alcohol content and high attenuation degree. Here, we present the first annotated genome of B. naardenensis CBS 7540. The genome of B. naardenensis CBS 7540 was assembled into 76 contigs, totaling 11,283,072 nucleotides. In total, 5168 protein-coding sequences were annotated. The study provides functional genome annotation, phylogenetic analysis, and discusses genetic determinants behind notable stress tolerance and biotechnological potential of B. naardenensis

Exceptionally low charge trapping enables highly efficient organic bulk heterojunction solar cells

In this study, we investigate the underlying origin of the high performance of PM6:Y6 organic solar cells. Employing transient optoelectronic and photoemission spectroscopies, we find that this blend exhibits greatly suppressed charge trapping into electronic intra-bandgap tail states compared to other polymer/non-fullerene acceptor solar cells, attributed to lower energetic disorder. The presence of tail states is a key source of energetic loss in most organic solar cells, as charge carriers relax into these states, reducing the quasi-Fermi level splitting and therefore device VOC. DFT and Raman analyses indicate this suppression of tail state energetics disorder could be associated with a higher degree of conformational rigidity and uniformity for the Y6 acceptor. We attribute the origin of such conformational rigidity and uniformity of Y6 to the presence of the two alkyl side chains on the outer core that restricts end-group rotation by acting as a conformation locker. The resultant enhanced carrier dynamics and suppressed charge carrier trapping are proposed to be a key factor behind the high performance of this blend. Low energetic disorder is suggested to be a key factor enabling reasonably efficient charge generation in this low energy offset system. In the absence of either energetic disorder or a significant electronic energy offset, it is argued that charge separation in this system is primarily entropy driven. Nevertheless, photocurrent generation is still limited by slow hole transfer from Y6 to PM6, suggesting pathways for further efficiency improvement

Tinkering Evolution of Post-Transcriptional RNA Regulons: Puf3p in Fungi as an Example

Genome-wide studies of post-transcriptional mRNA regulation in model organisms indicate a “post-transcriptional RNA regulon” model, in which a set of functionally related genes is regulated by mRNA–binding RNAs or proteins. One well-studied post-transcriptional regulon by Puf3p functions in mitochondrial biogenesis in budding yeast. The evolution of the Puf3p regulon remains unclear because previous studies have shown functional divergence of Puf3p regulon targets among yeast, fruit fly, and humans. By analyzing evolutionary patterns of Puf3p and its targeted genes in forty-two sequenced fungi, we demonstrated that, although the Puf3p regulon is conserved among all of the studied fungi, the dedicated regulation of mitochondrial biogenesis by Puf3p emerged only in the Saccharomycotina clade. Moreover, the evolution of the Puf3p regulon was coupled with evolution of codon usage bias in down-regulating expression of genes that function in mitochondria in yeast species after genome duplication. Our results provide a scenario for how evolution like a tinker exploits pre-existing materials of a conserved post-transcriptional regulon to regulate gene expression for novel functional roles

Antagonistic Changes in Sensitivity to Antifungal Drugs by Mutations of an Important ABC Transporter Gene in a Fungal Pathogen

Fungal pathogens can be lethal, especially among immunocompromised populations, such as patients with AIDS and recipients of tissue transplantation or chemotherapy. Prolonged usage of antifungal reagents can lead to drug resistance and treatment failure. Understanding mechanisms that underlie drug resistance by pathogenic microorganisms is thus vital for dealing with this emerging issue. In this study, we show that dramatic sequence changes in PDR5, an ABC (ATP-binding cassette) efflux transporter protein gene in an opportunistic fungal pathogen, caused the organism to become hypersensitive to azole, a widely used antifungal drug. Surprisingly, the same mutations conferred growth advantages to the organism on polyenes, which are also commonly used antimycotics. Our results indicate that Pdr5p might be important for ergosterol homeostasis. The observed remarkable sequence divergence in the PDR5 gene in yeast strain YJM789 may represent an interesting case of adaptive loss of gene function with significant clinical implications