Seed ontogeny in Adesmia securigerifolia (Fabaceae-Adesmieae)

A study of the reproductive processes of Adesmia securigerifolia from bud to mature seed was carried out by means of field observations and the paraffin technique. Observations revealed the following new contributions to the study of legume embryology: 1) after fertilization, a small nucellar haustorium, or micropylar nucellar beak, was observed for the first time, originating from two obliterating nucellar cells that extended outwards. Their globose distal end comes in contact with the internal carpel wall, while the wedge shaped base stretches into the micropyle; a suspensor consisting of five or more cells - the two basal cells are large and falcate and fit into the micropylar pore - coexists with the undivided polar nuclei thus showing that endosperm formation begins after zygote division; 2) at the young embryo stage, a sac- shaped nuclear haustorium, formed by the endosperm, adjoins the outer integument and is not connected to the chalaza, or any vascular element; at the hilar level, a nucellar projection is formed in connection with the haustorial coenocytic endosperm. This projection persists up to the mature seed stage when it starts to degenerate, after performing another linking with the embryo nutrition system; 3) at the mature seed stage, the seed coat evolving from the outer integument has a single macrosclereid layer, though inclusions in the cell vacuoles simulate the presence of more layers and/or transverse walls. The lens, a hypodermal layer of osteosclereids (hour-glass cells), and the astrosclereids are also described.     

Implantable Electrical Vesical Stimulator: Review of the Literature and Report of a Successful Case

Considerable interest has been shown recently in electrical stimulation of the incompetent urinary bladder. Two types of bladder stimulation have been attempted in dogs and in humans: (a) stimulation of nervi erigentes and (b) direct stimulation of the detrusor urinae muscle.After several years of animal experimentation, a vesical stimulator, built on a new electronic principle, was implanted successfully in a paraplegic patient who has a complete post-traumatic lower motor neuron lesion. The stimulator has been working satisfactorily since November 1965.This stimulator could eventually also be used in purely sensory sacral lesions, in well-selected incomplete lower motor neuron lesions, and in flaccid detrusors of the myogenic type.A review of the literature up to the time of this report shows only a few encouraging but incomplete results in humans. The techniques and the complexities involved in this problem are discussed.     

Regulation of cation transporter genes by the arbuscular mycorrhizal symbiosis in rice plants subjected to salinity suggests improved salt tolerance due to reduced Na<Superscript>+</Superscript> root-to-shoot distribution

Rice is a salt-sensitive crop whose productivity is strongly reduced by salinity around the world. Plants growing in saline soils are subjected to the toxicity of specific ions such as sodium, which damage cell organelles and disrupt metabolism. Plants have evolved biochemical and molecular mechanisms to cope with the negative effects of salinity. These include the regulation of genes with a role in the uptake, transport or compartmentation of Na⁺ and/or K⁺. Studies have shown that the arbuscular mycorrhizal (AM) symbiosis alleviates salt stress in several host plant species. However, despite the abundant literature showing mitigation of ionic imbalance by the AM symbiosis, the molecular mechanisms involved are barely explored. The objective of this study was to elucidate the effects of the AM symbiosis on the expression of several well-known rice transporters involved in Na⁺/K⁺ homeostasis and measure Na⁺ and K⁺ contents and their ratios in different plant tissues. Results showed that OsNHX3, OsSOS1, OsHKT2;1 and OsHKT1;5 genes were considerably upregulated in AM plants under saline conditions as compared to non-AM plants. Results suggest that the AM symbiosis favours Na⁺ extrusion from the cytoplasm, its sequestration into the vacuole, the unloading of Na⁺ from the xylem and its recirculation from photosynthetic organs to roots. As a result, there is a decrease of Na⁺ root-to-shoot distribution and an increase of Na⁺ accumulation in rice roots which seems to enhance the plant tolerance to salinity and allows AM rice plants to maintain their growing processes under salt conditions.     

Temporal trends of the airborne fungal spores in Catalonia (NE Spain), 1995–2013

To establish the trends in the period 1995–2013 of the annual fungal spore index of 20 taxa in 8 aerobiological sites of Catalonia, located in 4 phytoclimates, we use the nonparametric Spearman’s Rho and Mann–Kendall tests; when significant, we calculate the magnitude of the change applying the Theil–Sen estimator. We analyze whether the proportional annual change is significantly different from zero, according to phytoclimate, station, and spore taxon, with the Wilcoxon–Mann–Whitney test. Cladosporium, Coprinaceae and Agrocybe are the most prevalent taxa. The proportional annual change analysis shows that 12 taxa present significant increasing trends and 2 decreasing, that the Fresh-Continental Oriental-Humid phytoclimate and Agrocybe show the highest significant increase, while Roquetes-Tortosa (Fresh-Tethyc-Semiarid phytoclimate) and Torula the lowest. The greater significant decreasing proportional annual change corresponds to Drechslera–Helminthosporium and the lesser to Curvularia, and there are no results per phytoclimate and locality. The diversity of characteristics of the sites studied brings the opportunity to evaluate the variability of the fungal values and the magnitude of their change across the study period as depending on the intensity of the land use (urbanization versus agriculture) and the distance to the sea (inland versus littoral), but the effect of the change of the meteorological patterns in the recent years is not negligible. The increasing temperatures and precipitation instability established as effects of the climate change in Catalonia in the last 50 years could be stimulating the sporulation in mountain areas and affecting it in the southern Catalan littoral, thus affecting spore counts.     

Statistical analysis of structural determinants for protein–DNA‐binding specificity

DNA‐binding proteins play critical roles in biological processes including gene expression, DNA packaging and DNA repair. They bind to DNA target sequences with different degrees of binding specificity, ranging from highly specific (HS) to nonspecific (NS). Alterations of DNA‐binding specificity, due to either genetic variation or somatic mutations, can lead to various diseases. In this study, a comparative analysis of protein–DNA complex structures was carried out to investigate the structural features that contribute to binding specificity. Protein–DNA complexes were grouped into three general classes based on degrees of binding specificity: HS, multispecific (MS), and NS. Our results show a clear trend of structural features among the three classes, including amino acid binding propensities, simple and complex hydrogen bonds, major/minor groove and base contacts, and DNA shape. We found that aspartate is enriched in HS DNA binding proteins and predominately binds to a cytosine through a single hydrogen bond or two consecutive cytosines through bidentate hydrogen bonds. Aromatic residues, histidine and tyrosine, are highly enriched in the HS and MS groups and may contribute to specific binding through different mechanisms. To further investigate the role of protein flexibility in specific protein–DNA recognition, we analyzed the conformational changes between the bound and unbound states of DNA‐binding proteins and structural variations. The results indicate that HS and MS DNA‐binding domains have larger conformational changes upon DNA‐binding and larger degree of flexibility in both bound and unbound states. Proteins 2016; 84:1147–1161. © 2016 Wiley Periodicals, Inc.     

Molecular and genetic characterization of the <Emphasis Type="Italic">Ry</Emphasis><Subscript><Emphasis Type="Italic">adg</Emphasis></Subscript> locus on chromosome XI from Andigena potatoes conferring extreme resistance to potato virus Y

Key message

We have elucidated the Andigena origin of the potato Ry_adg gene on chromosome XI of CIP breeding lines and developed two marker assays to facilitate its introgression in potato by marker-assisted selection.

Abstract

Potato virus Y (PVY) is causing yield and quality losses forcing farmers to renew periodically their seeds from clean stocks. Two loci for extreme resistance to PVY, one on chromosome XI and the other on XII, have been identified and used in breeding. The latter corresponds to a well-known source of resistance (Solanum stoloniferum), whereas the one on chromosome XI was reported from S. stoloniferum and S. tuberosum group Andigena as well. To elucidate its taxonomic origin in our breeding lines, we analyzed the nucleotide sequences of tightly linked markers (M45, M6) and screened 251 landraces of S. tuberosum group Andigena for the presence of this gene. Our results indicate that the PVY resistance allele on chromosome XI in our breeding lines originated from S. tuberosum group Andigena. We have developed two marker assays to accelerate the introgression of Ry_adg gene into breeding lines by marker-assisted selection (MAS). First, we have multiplexed RYSC3, M6 and M45 DNA markers flanking the Ry_adg gene and validated it on potato varieties with known presence/absence of the Ry_adg gene and a progeny of 6,521 individuals. Secondly, we developed an allele-dosage assay particularly useful to identify multiplex Ry_adg progenitors. The assay based on high-resolution melting analysis at the M6 marker confirmed Ry_adg plex level as nulliplex, simplex and duplex progenitors and few triplex progenies. These marker assays have been validated and can be used to facilitate MAS in potato breeding.