Attraction between social crab spiders: silk pheromones in Diaea socialis

The snare web is used as a medium for communication betweenindividuals within colonies of social spiders and has thereforebeen suggested as necessary for the evolution of sociality inthe Araneae. The social spider Diaea socialis (Thomisidae) isan exception because it does not build a snare web. Experimentsdemonstrate that silk attracts all spiders and that a chemicaldeposited onto the silk attracts adult female spiders, suggestingthat the group living of this species is mediated by a pheromone.The pheromone attracts spiders differentially: females are notattracted to juvenile silk, and it repels gravid females. Thepheromone appears to be stable but volatile, is ether-soluble,and retains its viability after dissolution. Molecular-ionicmasses for 7-8 different compounds were found in the range 220–281atomic units; the pheromone may be one or a combination of severalof these.     

Potential problems in the use of oligonucleotide probes for staphylococcal enterotoxin genes

Oligonucleotide probes unique to the five major enterotoxin genes of Staphylococcus aureus were synthesized and used to detect DNA sequences homologous to these genes in 27 non-clinical isolates of Staph. aureus isolated from nasal swabs of 74 healthy human volunteers. Genomic DNA from all 27 isolates reacted with at least one of the probes. In a phenotypic assay for toxin production by a reverse passive latex agglutination test however, only 15 of the 27 isolates produced enterotoxin in culture. The results raise the possibility that a number of Staph. aureus isolates harbour DNA sequences that are apparently silent or mutant copies of the enterotoxin genes. This complicates the identification of enterotoxin producers by tests which depend on oligonucleotide or DNA hybridization.     

Identification of a UDP-glucosyltransferase conferring deoxynivalenol resistance in Aegilops tauschii and wheat

Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin-induced bleaching. A k-mer-based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non-toxic DON-3-O-glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)-glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full-length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley.     

Novel thieno[2,3-b]- and [3,4-b]pyrans as potassium channel openers. Thiophene systems—XVII

The syntheses and antihypertensive activity of the thieno[3,4-b]pyran and thieno[2,3-b]pyran isosteres of the potassium channel opener (PCO) RWJ 26629 (± 2a) are reported. While the unsubstituted thiophene derivatives were active at 20 mg/kg, introduction of a strong electron withdrawing group in the 2-position of the thieno[3,2-b] series increased potency. Similar substitution on the thieno[3,4-b] series significantly lowered potency. Compounds 26 and 30 are approximately 5-fold more potent than the prototypic PCO cromakalim (± 1).     

Modulation of mechanosensitive calcium-selective cation channels by temperature

Gating of associations of mechanosensitive Ca²⁺-selective cation co-channels in the plasmalemma of onion epidermis has a strong and unusual temperature dependence. Tension-dependent activity rises steeply as temperature is lowered from 25°C to about 6°C, but drops to a low level at about 5°C. Under the conditions tested (with Mg²⁺ and K⁺ at the cytosolic face of outside-out membrane patches), promotion results both from more bursting at all observed linkage levels and from longer duration of bursts of co-channels linked as quadruplets and quintuplets. Co-channel conductance decreases linearly, but only modestly, with declining temperature. It is proposed that these and related mechanosensitive channels may participate in a variety of responses to temperature, including thermonasty, thermotropism, hydrotropism, and both cold damage and cold acclimation.     

Chromosomal mapping in the mouse of eight K-channel-genes representing the four Shaker-like subfamilies Shaker, Shab, Shaw, and Shal

The four Shaker-like subfamilies of Shaker-, Shab-,Shaw-, and Shal-related K⁺ channels in mammals have been defined on the basis of their sequence homologies to the corresponding Drosophila genes. Using interspecific backcrosses between Mus musculus and Mus spretus, we have chromosomally mapped in the mouse the Shaker-related K⁺-channel genes Kcna1, Kcna2, Kcna4, Kcna5, and Kcna6; the Shab-related gene Kcnb1; the Shaw-related gene Kcnc4; and the Shal-related gene Kcnd2. The following localizations were determined: Chr 2, cen-Acra-Kcna4-Pax-6-a-Pck-1-Kras-3-Kcnb1 (corresponding human Chrs 11p and 20q, respectively); Chr 3, cen-Hao-2-(Kcna2, Kcnc4)-Amy-1 (human Chr 1); and Chr 6, cen-Cola-2-Met-Kcnd2-Cpa-Tcrb-adr/Clc-1-Hox-1.1-Myk-103-Raf-1-(Tpi-1, Kcna1, Kcna5, Kcna6) (human Chrs 7q and 12p, respectively). Thus, there is a cluster of at least three Shaker-related K⁺-channel genes on distal mouse Chr 6 and a cluster on Chr 2 that at least consists of one Shaker-related and one Shaw-related gene. The three other K⁺-channel genes are not linked to each other. The map positions of the different types of K⁺-channel genes in the mouse are discussed in relation to those of their homologs in man and to hereditary diseases of mouse and man that might involve K⁺ channels.