Summary Phenotypic scrutiny on the life cycle of Icthyodinium chabelardi ( Perkinsoide chabelardi n. gen.) based on ultrastructural techniques, and molecular phylogenetic analysis of RNA gene sequences, were carried out in order to elucidate the taxonomic position of this parasite. The absence of plastid, presence of trichocysts, and chromosomes or chromatin condensed and low in number, suggested that this protozoan could be considered a dinoflagellate syndinial parasite. However, the life cycle, schizogonic divisions and structure of schizonts inside the host, the nuclei without the typical dinoflagellate appearance, presence of rhoptrias‐like structures, a possible pseudo‐conoid, and the biflagellated spore, resembled those of the genus Perkinsus. Phylogenetic analysis of genes transcribing for the RNA forming the small subunit and the large subunit suggests that this parasite has an ambiguous evolutionary position within the group formed by dinoflagellates, perkinsids and syndinials. Because of differences with dinoflagellates and similarities with perkinsids, we propose to change the generic name to P. chabelardi n. gen. High stationary infection prevalence on Sardina pilchardus eggs was observed. This protozoan parasite caused the death of all the infected sardine eggs, and therefore a high impact in the recruitment of this fishery in the Atlantic coast is expected.
Inbreeding depression is a widespread phenomenon that reflects the burden of deleterious effects hidden in heterozygosis in non-inbred populations but exposed in homozygosis in inbred individuals, known as inbreeding load ( B ). This load can be due to partially or fully recessive deleterious mutations (dominance model) or to heterozygote advantage (overdominance model, where both homozygotes are deleterious relative to the heterozygote). There are many studies addressing the changes in inbreeding load in finite populations assuming the dominance model. However, the contribution of overdominance to inbreeding depression has been focused on infinite-size populations. We carried out computer simulations to investigate the joint impact of dominant and pure overdominant mutations on inbreeding load, both for self-fertilizing populations and for panmictic populations suffering from a drastic bottleneck. We found that the overdominant inbreeding load can be substantially reduced by drift even for symmetrical overdominance, at least when considering mutations of small effect. For panmictic bottlenecked populations, the reduction in inbreeding load under dominance and overdominance loci cannot be easily distinguished. However, while purging depletes inbreeding load from dominant loci, slowing inbreeding depression and leading to partial fitness recovery, for overdominant loci fitness declines monotonically.
The extreme genetic diversity of the HIV-1 remains as a daunting challenge for the development of an effective AIDS vaccine. One strategy for creating a single vaccine that protects against the HIV-1 expanding population is to reconstruct centralized immunogenic sequences that minimize the genetic distance to circulating strains that the vaccine is targeting. Such centralized genes can be estimated with inferred consensus, ancestral and center-of-tree sequences. Although the increased breadth of antibody and T-cell responses induced by the centralized vaccines to date are encouraging, they are modest and may only be partly effective in combating HIV-1. One of the reasons of this limited success might be that several features of HIV-1 molecular evolution have not been yet taken into account in the design of these centralized vaccines, the most important likely being its high recombination rate and complex nucleotide substitution process. Here we describe evolutionary methodologies for the inference of centralized HIV-1 genes, with particular focus on the sources of error introduced by recombination and the model of evolution, in order to foster the development of more effective immunogens before synthesis and assessment in the lab, and final testing in AIDS vaccine trials.
Abstract Metallodielectric composites with tunable optical properties were prepared by layer‐by‐layer assembly of gold nanorods on polystyrene (PS) spheres and subsequent deposition of SiO 2 or TiO 2 encapsulating shells through a sol–gel process. The optical properties of the core‐shells were tailored in the visible and the near‐infrared region through the gold nanorod aspect ratio and the gold nanoparticle density. Removal of the PS core by dissolution in an appropriate solvent, such as THF, yielded metallodielectric hollow shells with optical properties identical to those of the original composites. The presence of gold and the porosity of the SiO 2 or TiO 2 shells, suitable to allow diffusion of reactants and products, make these materials of interest as catalysts, as demonstrated by the reduction of potassium hexacyanoferrate(III) with NaBH 4 .
For the purpose of training the periscope operator on shore, the periscope scene simulation system is designed based on VR technology. The structure of system is introduced at first. Then the method using stencil buffer to achieve the periscope circle window clipping is proposed, which can efficiently ensure the clipping and has little influence in rendering effect. By changing the vertical and horizontal angle of view to achieve the control the display at different magnification, the switching of LOD at different magnification is realized by altering the visible range of LODs. By applying callback functions of OpenGL in Vega Prime, achieved the display of Chinese characters in the coach console. The results show that system can simulate the whole process of periscope training and have good performance in economic efficiency and reliability.
