Conserved SUN-KASH Interfaces Mediate LINC Complex-Dependent Nuclear Movement and Positioning

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Early development of the limpet Siphonaria lessonii Blainville, 1827 in populations affected by different physical stressors

The limpet Siphonaria lessonii is very common along Atlantic Patagonian intertidal rocky shores. We studied the early intracapsular embryonic development of this limpet in detail in two populations in north Patagonia, with different environmental conditions (i.e. wave exposure, wind, temperature). Early development in both populations was achieved at controlled and equal conditions (13°C). The spawn consisted of a series of enchained egg capsules embedded in a jelly mass. The development from egg to hatching veliger took 9–11 days in embryos from both populations. The developmental process at both sites was identical, differing only in the embryos' sizes at each stage. Larger adult individuals producing larger embryos were registered at the sheltered site. The differences in sizes of adult and embryos of S. lessonii could be attributed to distinct environmental stressful conditions between sites.     

Molecular topology: a useful tool for the search of new antibacterials

Molecular topology has been applied to find new lead antibacterial compounds. Among the selected compounds, hesperidin, neohesperidin and Mordant Brown 24 stand out, with minimum inhibitory concentrations 90, MIC90 < 0.3 mg/mL.     

Functionality of lactic acid bacteria peptidase activities in the hydrolysis of gliadin‐like fragments

Aims: To evaluate the role of the peptidase activities from sourdough lactic acid bacteria (LAB) in the degradation of α‐gliadin fragments. Methods and Results: Different proline‐containing substrates were hydrolysed by LAB indicating pro‐specific peptidase activities. Lactobacillus plantarum CRL 775 and Pediococcus pentosaceus CRL 792 displayed the highest tri‐ and di‐peptidase activities, respectively. Lactobacillus plantarum strains hydrolysed more than 60%α‐gliadin fragments corresponding to the 31–43 and 62–75 amino acids in the protein after 2 h. None of the LAB strains alone could hydrolyse 57–89 α‐gliadin peptide; however, the combination of L. plantarum CRL 775 and P. pentosaceus CRL 792 led to hydrolysis (57%) of this peptide in 8 h. Conclusions: The capacity of LAB strains to degrade α‐gliadin fragments was not correlated to individual peptidase activities. Several strains separately degraded the 31–43 and 62–75 α‐gliadin fragments, while the 57–89 peptide degradation was associated with the combination of peptidase profiles from pooled LAB strains. This is the first report on the peptide hydrolase system of sourdough pediococci and its ability to reduce α‐gliadin fragments. Significance and Impact of the Study: This study contributes to a better knowledge of sourdough LAB proteolytic system and its role in the degradation of proline‐rich α‐gliadin peptides involved in celiac disease.     

Enhanced antibody-mediated neutralization of HIV-1 variants that are resistant to fusion inhibitors

Background

HIV-1 typically develops resistance to any single antiretroviral agent. Combined anti-retroviral therapy to reduce drug-resistance development is necessary to control HIV-1 infection. Here, to assess the utility of a combination of antibody and fusion inhibitor treatments, we investigated the potency of monoclonal antibodies at neutralizing HIV-1 variants that are resistant to fusion inhibitors.

Results

Mutations that confer resistance to four fusion inhibitors, enfuvirtide, C34, SC34, and SC34EK, were introduced into the envelope of HIV-1_JR-FL, a CCR5-tropic tier 2 strain. Pseudoviruses with these mutations were prepared and used for the assessment of neutralization sensitivity to an array of antibodies. The resulting neutralization data indicate that the potencies of some antibodies, especially of those against the CD4 binding site, V3 loop, and membrane-proximal external region epitopes, were increased by the mutations in gp41 that conferred resistance to the fusion inhibitors. C34-, SC34-, and SC34EK-resistant mutants showed more sensitivity to monoclonal antibodies than enfuvirtide-resistant mutants. An analysis of C34-resistant mutations revealed that the I37K mutation in gp41 HR1 is a key mutation for C34 resistance, low infectivity, neutralization sensitivity, epitope exposure, and slow fusion kinetics. The N126K mutation in the gp41 HR2 domain contributed to C34 resistance and neutralization sensitivity to anti-CD4 binding site antibodies. In the absence of L204I, the effect of N126K was antagonistic to that of I37K. The results of a molecular dynamic simulation of the envelope trimer confirmation suggest that an I37K mutation induces the augmentation of structural fluctuations prominently in the interface between gp41 and gp120. Our observations indicate that the “conformational unmasking” of envelope glycoprotein by an I37K mutation is one of the mechanisms of neutralization sensitivity enhancement. Furthermore, the enhanced neutralization of C34-resistant mutants in vivo was shown by its high rate of neutralization by IgG from HIV patient samples.

Conclusions

Mutations in gp41 that confer fusion inhibitor resistance exert enhanced sensitivity to broad neutralizing antibodies (e.g., VRC01 and 10E8) and other conventional antibodies developed in HIV-1 infected patients. Therefore, next-generation fusion inhibitors and monoclonal antibodies could be a potential combination for future regimens of combined antiretroviral therapy.

     

One Dose of Staphylococcus aureus 4C-Staph Vaccine Formulated with a Novel TLR7-Dependent Adjuvant Rapidly Protects Mice through Antibodies,Effector CD4+ T Cells,and IL-17A

A rapidly acting, single dose vaccine against Staphylococcus aureus would be highly beneficial for patients scheduled for major surgeries or in intensive care units. Here we show that one immunization with a multicomponent S. aureus candidate vaccine, 4C-Staph, formulated with a novel TLR7-dependent adjuvant, T7-alum, readily protected mice from death and from bacterial dissemination, both in kidney abscess and peritonitis models, outperforming alum-formulated vaccine. This increased efficacy was paralleled by higher vaccine-specific and α-hemolysin-neutralizing antibody titers and Th1/Th17 cell responses. Antibodies played a crucial protective role, as shown by the lack of protection of 4C-Staph/T7-alum vaccine in B-cell-deficient mice and by serum transfer experiments. Depletion of effector CD4⁺ T cells not only reduced survival but also increased S. aureus load in kidneys of mice immunized with 4C-Staph/T7-alum. The role of IL-17A in the control of bacterial dissemination in 4C-Staph/T7-alum vaccinated mice was indicated by in vivo neutralization experiments. We conclude that single dose 4C-Staph/T7-alum vaccine promptly and efficiently protected mice against S. aureus through the combined actions of antibodies, CD4⁺ effector T cells, and IL-17A. These data suggest that inclusion of an adjuvant that induces not only fast antibody responses but also IL-17-producing cell-mediated effector responses could efficaciously protect patients scheduled for major surgeries or in intensive care units.     

Effects of fragmentation and landscape variation on tree diversity in post-logging regrowth forests of the Southern Philippines

The conservation value of forest fragments remains controversial. An extensive inventory of rainforest trees in post-logging regrowth forest in the southern Philippines provided a rare opportunity to compare stem density, species richness, diversity and biotic similarity between two types of post-logging forests: broken-canopy forest fragments and adjacent tracts of closed-canopy ‘contiguous’ forest. Tree density was much lower in the fragments, but rarefied species richness was higher. ‘Hill’ numbers, computed as the exponential of Shannon’s diversity index and the inverse of Simpson’s diversity index, indicated that fragments have higher numbers of typical and dominant species compared to contiguous forest. Beta diversity (based on species incidence) and the exponential of Shannon’s diversity index was higher in fragmented forest, indicating higher spatial species turnover than in contiguous forest samples. Lower mean values of the Chao-Jaccard index in fragmented forest compared to contiguous forest also indicated a lower probability of shared species across fragments. The high species richness of contiguous forest showed that an earlier single logging event had not caused biodiversity to be degraded leaving mostly generalist species. Fragmentation and further low-level utilisation by local farmers has also not caused acute degradation. Post-logging regrowth forest fragments present a window of opportunity for conservation that may disappear in a few years as edge effects become more apparent. For the conservation of trees in forests in south-east Asia generally, our findings also suggest that while conservation of remaining primary forest may be preferable, the conservation value of post-logging regrowth forests can also be high.     

Phylogeny of the spider genus Ixchela Huber, 2000 (Araneae: Pholcidae) based on morphological and molecular evidence (CO1 and 16S), with a hypothesized diversification in the Pleistocene

The genus Ixchela Huber is composed of 20 species distributed from north‐eastern Mexico to Central America, including the five new species described here from Mexico: I xchela azteca sp. nov. , I xchela jalisco sp. nov. , I xchela mendozai sp. nov. , I xchela purepecha sp. nov. and I xchela tlayuda sp. nov. We test the monophyly and investigate the phylogenetic relationships among species of the genus Ixchela using morphological and molecular data. Parsimony (PA) analysis of 24 taxa and 40 morphological characters with equal and implied weights supported the monophyly of Ixchela with eight morphological synapomorphies. The PA analyses with equal and implied weights, and separate Bayesian inference (BI) analyses for the CO1 gene (506 characters), concatenated gene fragments CO1 + 16S (885 characters), morphology + CO1 (546 characters) and the combined evidence data set (morphology + CO1 + 16S) (925 characters) support the monophyly of Ixchela. Our preferred topology shows two large clades; clade 1 has a natural distribution in the Mesoamerican biotic component, whereas clade 2 predominates in the Mexican Montane biotic component. The genus Ixchela diverged in the late Miocene, and the divergence between the internal clades in the genus occurred in the late Pliocene; by contrast, most of the speciation events seem to have occurred mainly during the Pleistocene, where climatic changes brought on by repeated glaciations played an important role in the diversification of the genus. © 2015 The Linnean Society of London     

The Canonical DHHC Motif Is Not Absolutely Required for the Activity of the Yeast S-acyltransferases Swf1 and Pfa4

Protein S-acyltransferases, also known as palmitoyltransferases (PATs), are characterized by the presence of a 50-amino acid domain called the DHHC domain. Within this domain, these four amino acids constitute a highly conserved motif. It has been proposed that the palmitoylation reaction occurs through a palmitoyl-PAT covalent intermediate that involves the conserved cysteine in the DHHC motif. Mutation of this cysteine results in lack of function for several PATs, and DHHA or DHHS mutants are used regularly as catalytically inactive controls. In a genetic screen to isolate loss-of-function mutations in the yeast PAT Swf1, we isolated an allele encoding a Swf1 DHHR mutant. Overexpression of this mutant is able to partially complement a swf1Δ strain and to acylate the Swf1 substrates Tlg1, Syn8, and Snc1. Overexpression of the palmitoyltransferase Pfa4 DHHA or DHHR mutants also results in palmitoylation of its substrate Chs3. We also investigated the role of the first histidine of the DHHC motif. A Swf1 DQHC mutant is also partially active but a DQHR is not. Finally, we show that Swf1 substrates are differentially modified by both DHHR and DQHC Swf1 mutants. We propose that, in the absence of the canonical mechanism, alternative suboptimal mechanisms take place that are more dependent on the reactivity of the acceptor protein. These results also imply that caution must be exercised when proposing non-canonical roles for PATs on the basis of considering DHHC mutants as catalytically inactive and, more generally, contribute to an understanding of the mechanism of protein palmitoylation