Utilization of wild relatives in the genetic improvement of Arachis hypogaea L.

Summary Synthetic amphidiploids were established in 32 combinations involving 8 diploid wild species representing both A and B genomes of section Arachis. Bivalent and multivalent associations in the amphidiploids of 7 A genome species confirm that these species have identical genomes. Contrastingly, high bivalent frequencies in amphidiploids involving the A and B genome species suggest that A. batizocoi has a distinct B genome that is partially homologous to the other genome A represented in the rest of the species. Crossability, chromosome pairing and pollen and pod fertility in hybrids between A. hypogaea and amphidiploids have revealed that these amphidiploids can be used as a genetic bridge for the transfer of genes from the wild species into the cultivated groundnut.Submitted as Journal Article No. 530 by International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)     

Extraction of total phenolic content from Azadirachta indica or (neem) leaves: Kinetics study

The objective of this work is to put forth the optimization and kinetics of total phenolic compounds extraction from Azadirachta indica leaves in a stirred batch extraction. Various experiential extraction parameters have been studied for maximum extraction of the total phenolic compounds. The maximum yield of total phenolic compounds was found to be 10.80?mg?g^?1 of dried neem powder under the optimized conditions. The extraction kinetics behavior followed first-order kinetics with diffusion coefficient ranged from 1.8?×?10^?12 to 3.2?×?10^?12?m² s^?1 for all sets. Activation energy (E_a) value for the extraction of the total phenolic compounds was found to be 22.87?kJ?mol^?1. The kinetic expression model developed by Spiro and Siddique showed a good agreement with the experimental outcomes. The obtained results can be used to scale up the operations for industrial purposes.     

SWS2 visual pigment evolution as a test of historically contingent patterns of plumage color evolution in warblers

Distantly related clades that occupy similar environments may differ due to the lasting imprint of their ancestors—historical contingency. The New World warblers (Parulidae) and Old World warblers (Phylloscopidae) are ecologically similar clades that differ strikingly in plumage coloration. We studied genetic and functional evolution of the short‐wavelength‐sensitive visual pigments (SWS2 and SWS1) to ask if altered color perception could contribute to the plumage color differences between clades. We show SWS2 is short‐wavelength shifted in birds that occupy open environments, such as finches, compared to those in closed environments, including warblers. Phylogenetic reconstructions indicate New World warblers were derived from a finch‐like form that colonized from the Old World 15–20 Ma. During this process, the SWS2 gene accumulated six substitutions in branches leading to New World warblers, inviting the hypothesis that passage through a finch‐like ancestor resulted in SWS2 evolution. In fact, we show spectral tuning remained similar across warblers as well as the finch ancestor. Results reject the hypothesis of historical contingency based on opsin spectral tuning, but point to evolution of other aspects of visual pigment function. Using the approach outlined here, historical contingency becomes a generally testable theory in systems where genotype and phenotype can be connected.     

Long-Lived, High-Strength States of ICAM-1 Bonds to β2 Integrin, I: Lifetimes of Bonds to Recombinant αLβ2 Under Force

Using single-molecule force spectroscopy to probe ICAM-1 interactions with recombinant α_Lβ₂ immobilized on microspheres and β₂ integrin on neutrophils, we quantified an impressive hierarchy of long-lived, high-strength states of the integrin bond, which start from basal levels with integrin activation in solutions of divalent cations and shift dramatically upward to hyperactivated states with cell signaling in leukocytes. Taking advantage of very rare events, we used repeated measurements of bond lifetimes under steady ramps of force to achieve a direct assay for the off-rates of ICAM-1 from β₂ integrin in each experiment. Of fundamental importance, the assay for off-rates does not depend on how the force is applied over time, and remains valid when the rates of dissociation change with different levels of force. In this first article, we present results from tests of a monovalent ICAM-1 probe against immobilized α_Lβ₂ in environments of divalent cations (Ca²⁺, Mg²⁺, and Mn²⁺) and demonstrate in detail the method for assay of off-rates. When extrapolated to zero force, the force-free values for the off-rates are found to be consistent with published solution-based assays of soluble ICAM-1 dissociation from immobilized LFA-1, i.e., ∼10⁻²/s in Mg²⁺ or Mn²⁺ and ∼1/s in Ca²⁺. At the same time, as expected for adhesive function, we find that the β₂ integrin bonds activated in Mn²⁺ or Mg²⁺ possess significant and persistent mechanical strength (e.g., >20 pN for >1 s) even when subjected to slow force ramps (<10 pN/s). As discussed in our companion article, using the same assay, we find that although the rates of dissociation for diICAM-1fc bonds to LFA-1 on neutrophils in Mn²⁺ are similar to those for mICAM-1 bonds to recombinant α_Lβ₂ on microspheres, they appear to represent a dimeric attachment to a pair of tightly clustered integrin heterodimers. The mechanical strengths and lifetimes of the dimeric interactions increase dramatically when the neutrophils are stimulated by the chemokine IL-8 or are bound with an allosterically activating (anti-CD18) monoclonal antibody, demonstrating the major impact of cell signaling on LFA-1.     

Meiotic pairing in hybrids between tetraploid Triticale and related species: new elements concerning the chromosome constitution of tetraploid Triticale

Summary Two F5 strains of tetraploid triticale (2n= 4x=28), obtained from 6x triticaleX2 rye progenies, were crossed with diploid and tetraploid rye, some durum and bread wheats, and various 8x and 6x triticale lines. Meiosis in the different hybrid combinations was studied. The results showed that the haploid complement of these triticales consists of seven chromosomes from rye and seven chromosomes from wheat. High frequencies of PMCs showing trivalents were observed in hybrids involving the reference genotypes of wheat and triticale. These findings proved that several chromosomes from the wheat component have chromosome segments coming from two parental wheat chromosomes. The origin of these heterogeneous chromosomes probably lies in homoeologous pairing occurring at meiosis in the 6x triticaleX2x rye hybrids from which 4x triticale lines were isolated. A comparison among different hybrids combinations indicated that the involvement of D-genome chromosomes in homoeologous pairing is quite limited. In contrast, meiotic patterns in 4x triticale X 2x rye hybrids showed a quite high pairing frequency between some R chromosomes and their A and B homoeologues.     

Transdifferentiation of mesenchymal stem cells derived from human fetal lung to hepatocyte-like cells

The great shortage of human hepatic cells makes it desirable to generate extrahepatic stem or precursor cells. In recent years, it has been reported that human multipotential mesenchymal stem cells (hMSCs) differentiate into hepatocyte-like cells. The fetal lung is one of the largest organs containing many MSCs that can be easily obtained. Whether MSCs from fetal lung can differentiate into hepatocytes or bile duct cells is an important issue in basic medicine and clinical application. We isolated fetal lung cells, and expanded and analyzed them. At passage 4, their morphologic, immunophenotyping and cytokine secretions were similar to adult bone marrow-derived MSCs. We conclude that these cells from fetal lung are MSCs, indicating that human fetal lung is an ideal source of hMSCs. hMSCs from fetal lung induced in special differentiation medium showed homogeneous and small polygonal endothelial-like morphology, expressing weak mRNA, as well as Alb and AFP. This implies that hMSCs from fetal lung can differentiate into hepatocyte-like cells.     

Study design and parameter estimability for spatial and temporal ecological models

The statistical tools available to ecologists are becoming increasingly sophisticated, allowing more complex, mechanistic models to be fit to ecological data. Such models have the potential to provide new insights into the processes underlying ecological patterns, but the inferences made are limited by the information in the data. Statistical nonestimability of model parameters due to insufficient information in the data is a problem too‐often ignored by ecologists employing complex models. Here, we show how a new statistical computing method called data cloning can be used to inform study design by assessing the estimability of parameters under different spatial and temporal scales of sampling. A case study of parasite transmission from farmed to wild salmon highlights that assessing the estimability of ecologically relevant parameters should be a key step when designing studies in which fitting complex mechanistic models is the end goal.     

Bystander effect for chromosomal aberrations induced in wild-type and repair deficient CHO cells by low fluences of alpha particles

Ultraviolet (UV) irradiation produces DNA photoproducts that are blocks to DNA replication by normal replicative polymerases. A specialized, damage-specific, distributive polymerase, Pol H or Pol h, that is the product of the hRad30A gene, is required for replication past these photoproducts. This polymerase is absent from XP variant (XP-V) cells that must employ other mechanisms to negotiate blocks to DNA replication. These mechanisms include the use of alternative polymerases or recombination between sister chromatids. Replication forks arrested by UV damage in virus transformed XP-V cells degrade into DNA double strand breaks that are sites for recombination, but in normal cells arrested forks may be protected from degradation by p53 protein. These breaks are sites for binding a protein complex, hMre11/hRad50/Nbs1, that colocalizes with H2AX and PCNA, and can be visualized as immunofluorescent foci. The protein complexes need phosphorylation to activate their DNA binding capacity. Incubation of UV irradiated XP-V cells with the irreversible kinase inhibitor wortmannin, however, increased the yield of Mre11 focus-positive cells. One interpretation of this observation is that two classes of kinases are involved after UV irradiation. One would be a wortmannin-resistant kinase that phosphorylates the Mre11 complex. The other would be a wortmannin-sensitive kinase that phosphorylates and activates the p53/large T in SV40 transformed XP-V cells. The sensitive class corresponds to the PI3-kinases of ATM, ATR, and DNA-PK, but the resistant class remains to be identified. Alternatively, the elevated yield of Mre11 foci positive cells following wortmannin treatment may reflect an overall perturbation to the signaling cascades regulated by wortmannin-sensitive PI3 related kinases. In this scenario, wortmannin could compromise damage inducible-signaling pathways that maintain the stability of stalled forks, resulting in a further destabilization of stalled forks that then degrade, with the formation of DNA double strand breaks.     

'Because we see them naked' - nurses' experiences in caring for hospitalized patients with dementia: considering artificial nutrition or hydration (ANH)

The aim of this study was to explore and describe how Flemish nurses experience their involvement in the care of hospitalized patients with dementia, particularly in relation to artificial nutrition or hydration (ANH). We interviewed 21 hospital nurses who were carefully selected from nine hospitals in different regions of Flanders. 'Being touched by the vulnerability of the demented patient' was the central experience of the nurses, having great impact on them professionally as well as personally. This feeling can be described as encompassing the various stages of the care process: the nurses' initial meeting with the vulnerable patient; the intense decision-making process, during which the nurses experienced several intense emotions influenced by supporting or hindering contextual factors; and the final coping process, a time when nurses came to terms with this challenging experience. From our examination of this care process, it is obvious that nurses' involvement in ANH decision-making processes that concern patients with dementia is a difficult and ethically sensitive experience. On the one hand, the feeling of 'being touched' can imply strength, as it demonstrates that nurses are willing to provide good care. On the other hand, the feeling of 'being touched' can also imply weakness, as it makes nurses vulnerable to moral distress stemming from contextual influences. Therefore, nurses have to be supported as they carry out this ethically sensitive assignment. Practical implications are given.