Do extrafloral nectaries present a defensive role against herbivores in two species of the family Bignoniaceae in a Neotropical savannas?

Despite the general belief that the interaction between extrafloral nectaries (EFNs) and ants is mutualistic, the defensive function of EFNs has been poorly documented in South American savannas. In this article, we evaluate the potential impact of EFNs (benefits and costs) on two species of plants from the dry areas of Central Brazil, Anemopaegma album and Anemopaegma scabriusculum (Bignoniaceae). In particular, we characterize the composition of substances secreted by the EFNs, test whether EFNs attract ants, and whether ants actually present a defensive role, leading to reduced herbivory and increased plant fitness. Histochemical analyses indicated that EFNs from both species of Anemopaegma secrete an exudate that is composed of sugars, and potentially lipids and proteins. Furthermore, EFNs from both species were shown to present a significant role in ant attraction. However, contrary to common expectations, ants were not found to protect plants against herbivore attack. No effect was found between ant visitation and flower or fruit production in A. album, while the presence of ants led to a significant decrease in flower production in A. scabriusculum. These results suggest that EFNs might present a similar cost and benefit in A. album, and a higher cost than benefit in A. scabriusculum. Since the ancestor of Anemopaegma occupied humid forests and already presented EFNs that were maintained in subsequent lineages that occupied savannas, we suggest that phylogenetic inertia might explain the presence of EFNs in the species of Anemopaegma in which EFNs lack a defensive function.     

Molecular characterization and evaluation of pectinase and cellulase production of Penicillium spp.

Penicillium species were analyzed with molecular markers and for pectinase and cellulase production. RAPD and PCR-RFLP analysis indicated high polymorphism among at least 5 of 10 Penicillium species. Five species were chosen for pectinase and cellulase production in liquid medium and four of which appeared similar based on molecular analyses. P. brevicompactum and P. griseoroseum gave the highest pectinase production and were highly divergent by molecular techniques.     

Left posterior fascicular block,state-of-the-art review: A 2018 update

We conducted a review of the literature regarding epidemiology, clinical, electrocardiographic and vectorcardiographic aspects, classification, and differential diagnosis of left posterior fascicular block.Isolated left posterior fascicular block (LPFB) is an extremely rare finding both in the general population and in specific patient groups. In isolated LPFB 20% of the vectorcardiographic (VCG) QRS loop is located in the right inferior quadrant and when associated with right bundle branch block (RBBB) ≥40%.The diagnosis of LPFB should always consider the clinical aspects, because a definite diagnosis cannot be made in the presence of right ventricular hypertrophy (RVH) (chronic obstructive pulmonary disease (COPD)/emphysema), extensive lateral myocardial infarction (MI) or extremely vertical heart.Intermittent LPFBs are never complete blocks (transient or second degree LPFB) and even in the permanent ones, one cannot be sure that they are complete. When LPFB is associated with RBBB and acute inferior MI, PR interval prolongation is very frequent.     

Nuclear and nucleolar localization signals and their targeting function in phosphatidylinositol 4-kinase PI4K230

PI4K230, an isoform of phosphatidylinositol 4-kinase, known primarily as a cytoplasmic membrane-bound enzyme, was detected recently also in the nucleolus of several cells. Here we provide mechanistic insight on the targeting function of its putative nuclear localization signal (NLS) sequences using molecular modeling, digitonin-permeabilized HeLa cells and binding to various importins. The synthetic sequence ⁹¹⁶NFNHIHKRIRRVADKYLSG⁹³⁴ comprising a putative monopartite NLS (NLS1), targeted covalently bound fluorescent BSA to the nucleoplasm via classical importin α/β mechanism employing importins α1 and α3 but not α5. This transport was inhibited by wheat germ agglutinin and GTPγS. The sequence ¹⁴¹⁴SKKTNRGSQLHKYYMKRRTL¹⁴³³, a putative bipartite NLS (NLS2) proved ineffective in nuclear targeting if conjugated to fluorescently labeled BSA. Nonetheless, NLS2 or either of its basic clusters directed to the nucleolus soybean trypsin inhibitor that can pass the nuclear pore complex passively; moreover, an expressed 58 kDa fragment of PI4K230 (AA1166–1667) comprising NLS2 was also imported into the nucleus by import factors of reticulocyte lysate or by importin α1/β or α3/β complexes and localized to the nucleolus. We conclude that the putative bipartite NLS itself is a nucleolar targeting signal, and for nuclear import PI4K230 requires a larger sequence around it or, alternatively, the monopartite NLS.     

Reversion in variants from a duplication strain of Aspergillus nidulans.

Summary Strains of Aspergillus nidulans with a chromosome segment in duplicate, one in normal position and one translocated to another chromosome, are unstable at mitosis. In addition to variants which result from deletions in either of the duplicate segments, which usually have improved morphology, they produce variants with deteriorated morphology. Three deteriorated variants reverted frequently to parental type morphology, both spontaneously and after ultra-violet treatment. Of six reversions analysed genetically, five were due to suppressors and one was probably due to back mutation. The suppressors segregated as single genes and were not linked to the mutation which they suppress. The instability of these so-called deteriorated variants is discussed in relation to mitotic instability phenomena in A. nidulans.     

MLL leukemia-associated rearrangements in peripheral blood lymphocytes from healthy individuals

Chromosomal translocations are characteristic of hematopoietic neoplasias and can lead to unregulated oncogene expression or the fusion of genes to yield novel functions. In recent years, different lymphoma/leukemia-associated rearrangements have been detected in healthy individuals. In this study, we used inverse PCR to screen peripheral lymphocytes from 100 healthy individuals for the presence of MLL (Mixed Lineage Leukemia) translocations. Forty-nine percent of the probands showed MLL rearrangements. Sequence analysis showed that these rearrangements were specific for MLL translocations that corresponded to t(4;11)(q21;q23) (66%) and t(9;11) (20%). However, RT-PCR failed to detect any expression of t(4;11)(q21;q23) in our population. We suggest that 11q23 rearrangements in peripheral lymphocytes from normal individuals may result from exposure to endogenous or exogenous DNA-damaging agents. In practical terms, the high susceptibility of the MLL gene to chemically-induced damage suggests that monitoring the aberrations associated with this gene in peripheral lymphocytes may be a sensitive assay for assessing genomic instability in individuals exposed to genotoxic stress.     

Single-molecule FRET study of denaturant induced unfolding of RNase H

Single-molecule fluorescence (F?rster) resonance energy transfer (FRET) experiments were performed on surface-immobilized RNase H molecules as a function of the concentration of the chemical denaturant guanidinium chloride (GdmCl). For comparison, we measured ensemble FRET on RNase H solutions. The single-molecule approach allowed us to study FRET distributions of the subpopulation of unfolded molecules without interference from the folded population. The unfolded ensemble experienced a continuous shift of the FRET efficiency distribution with increasing concentration of GdmCl, indicating a heterogeneous population of expanding, unfolded polypeptide chains. We have analyzed the behavior of the unfolded state quantitatively with a model in which the unfolded state is described by a continuum of substates, with the free energy of each substate linearly coupled to its m-value, the proportionality coefficient between free energy and denaturant activity. By fitting this model to the data, we have derived energetic and structural parameters that describe the unfolded state ensemble. Specifically, we have found that the average size of the unfolded state increases from 23-38 A between 0 and 6 M denaturant. Excellent agreement was achieved between the fitted model and our FRET measurements, and with previously published nuclear magnetic resonance and small-angle X-ray scattering data.     

Deciphering intratumor heterogeneity and temporal acquisition of driver events to refine precision medicine

The presence of multiple subclones within tumors mandates understanding of longitudinal and spatial subclonal dynamics. Resolving the spatial and temporal heterogeneity of subclones with cancer driver events may offer insight into therapy response, tumor evolutionary histories and clinical trial design.