Brown Spider (Loxosceles genus) Venom Toxins: Tools for Biological Purposes

Venomous animals use their venoms as tools for defense or predation. These venoms are complex mixtures, mainly enriched of proteic toxins or peptides with several, and different, biological activities. In general, spider venom is rich in biologically active molecules that are useful in experimental protocols for pharmacology, biochemistry, cell biology and immunology, as well as putative tools for biotechnology and industries. Spider venoms have recently garnered much attention from several research groups worldwide. Brown spider (Loxosceles genus) venom is enriched in low molecular mass proteins (5–40 kDa). Although their venom is produced in minute volumes (a few microliters), and contain only tens of micrograms of protein, the use of techniques based on molecular biology and proteomic analysis has afforded rational projects in the area and permitted the discovery and identification of a great number of novel toxins. The brown spider phospholipase-D family is undoubtedly the most investigated and characterized, although other important toxins, such as low molecular mass insecticidal peptides, metalloproteases and hyaluronidases have also been identified and featured in literature. The molecular pathways of the action of these toxins have been reported and brought new insights in the field of biotechnology. Herein, we shall see how recent reports describing discoveries in the area of brown spider venom have expanded biotechnological uses of molecules identified in these venoms, with special emphasis on the construction of a cDNA library for venom glands, transcriptome analysis, proteomic projects, recombinant expression of different proteic toxins, and finally structural descriptions based on crystallography of toxins

Analysis on influence of grid density on element failure strain in penetration numerical simulation

ObjectivesIn order to solve the problem of numerical simulation of flat-nosed projectile penetration into metal plates, the influence of mesh size on element failure strain value and residual velocity of projectiles was studied. MethodsThe finite element software LS-DYNA was used to simulate the process of uniaxial tensile test of Q235 steel sample, and the failure strain of the element under the grid density is obtained by the elongation of the tensile sample during fracture. In the meantime, the correction curve of the failure strain with the grid density was plotted and dynamically corrected. Then, the numerical simulation of flat-nosed projectile penetrating Q235 steel plate was carried out with the target plate meshed with different sizes. The failure strain of Q235 steel material was selected according to the correction curve. Finally, the residual velocity of the projectile is compared with the experimental results to analyze the influence of mesh size on the simulation results of the penetration resistance problem of the metal plate in the numerical simulation.ResultsThe results show that the element failure strain selected in the numerical simulation should increase with the increase in grid density, and in the case of the metal plate anti-penetration problem, it should increase with the increase of the grid density. In the problem of penetration resistance of metal plates, the simulation results of residual velocity prediction gradually converge with the experimental results. With the increase of mesh density, when the grid size is 0.5 mm, the average relative error of the numerical simulation and the test fitting curve in the velocity section is 5.13%, and the error between the numerical simulation and the test is larger in the low-speed section. Moreover, the residual velocity of the projectile body is more sensitive to mesh density in the low velocity range.ConclusionsThe related calculation methods and research results have a certain reference value for the selection of mesh size and material failure strain in the projectile penetration problem

Saccharomyces cerevisiae CWH43 Is Involved in the Remodeling of the Lipid Moiety of GPI Anchors to Ceramides

The glycosylphosphatidylinositol (GPI)-anchored proteins are subjected to lipid remodeling during their biosynthesis. In the yeast Saccharomyces cerevisiae, the mature GPI-anchored proteins contain mainly ceramide or diacylglycerol with a saturated long-fatty acid, whereas conventional phosphatidylinositol (PI) used for GPI biosynthesis contains an unsaturated fatty acid. Here, we report that S. cerevisiae Cwh43p, whose N-terminal region contains a sequence homologous to mammalian PGAP2, is involved in the remodeling of the lipid moiety of GPI anchors to ceramides. In cwh43 disruptant cells, the PI moiety of the GPI-anchored protein contains a saturated long fatty acid and lyso-PI but not inositolphosphorylceramides, which are the main lipid moieties of GPI-anchored proteins from wild-type cells. Moreover, the C-terminal region of Cwh43p (Cwh43-C), which is not present in PGAP2, is essential for the ability to remodel GPI lipids to ceramides. The N-terminal region of Cwh43p (Cwh43-N) is associated with Cwh43-C, and it enhanced the lipid remodeling to ceramides by Cwh43-C. Our results also indicate that mouse FRAG1 and C130090K23, which are homologous to Cwh43-N and -C, respectively, share these activities