Linkage and association mapping for the slow softening (SwS) trait in peach (<Emphasis Type="Italic">P. persica</Emphasis> L. Batsch) fruit

Fruit texture is a crucial quality factor influencing consumer preference and shelf life. Peach (P. persica L. Batsch) is a highly perishable fruit subjected to a rapid softening after harvest. Improvement of peach shelf life is an important breeding objective, stimulating the characterization and exploitation of texture-related traits. Variants of melting (M) texture have captured an increasing interest, following the economic success of “Big Top” nectarine, one of the most cultivated varieties worldwide. “Big Top” fruit maintains a crispy texture for an extended period before the onset of the melting phase, prolonging its shelf life. Genetic determinants regulating this complex trait, defined as slow softening (SwS), are still unknown, mainly because of limitations in phenotyping methods. In this work, a mechanical approach for measuring SwS fruit texture was used to phenotype offspring derived from a cross between “Rebus028” (SwS texture) and “Max10” (M texture). Mechanical parameters were used in linkage mapping, allowing the identification of a major QTL on chromosome 8 (qSwS8.1). The presence of this QTL was validated by a genome-wide association study (GWAS) in a panel of accessions phenotyped for mechanical properties. Less significant signals were also detected by GWAS in other genomic regions, suggesting that additional loci may regulate the SwS trait, possibly depending on the genetic background. The inheritance pattern of the SwS trait and the presence of additional loci are crucial aspects to be addressed in future studies, along with a better characterization of other important textural attributes.     

Biological activity of <Emphasis Type="Italic">Claviceps gigantea</Emphasis> in juvenile New Zealand rabbits

The Ascomycete fungus Claviceps gigantea infects maize kernels and synthetizes several alkaloids, mostly dihydrolysergamides. There is limited information on the damage these toxins cause in mammals, despite reports from infested areas with 90% presence of the fungus sclerotia. With this background, it was decided to determine the biological activity of chemical compounds present in sclerotia of C. gigantea in rabbits 38 days after weaning. Sclerotia of C. gigantea were collected in fields with high incidence of the disease, ground and analysed for nutrients. Experimental diets were prepared with four treatments, where sclerotial powder was added, substituting for alfalfa flour in increasing proportions [C. gigantea/alfalfa flour (0:100, 5:95, 15:85 and 25:75)]. Total ergot alkaloid content was analysed by high-performance liquid chromatography. Male juvenile rabbits were utilised and distributed in completely randomised design with four replications. Initial weight was recorded in each animal, and experimental diet was offered. In this study, weight of animals, feed consumption and feed conversion were evaluated in individual animals. Blood samples were taken for haemograms, and finally euthanasia was practiced. The consumption of C. gigantea had a negative effect on body weight and feed consumption. The necropsies showed anomalies proportional to the consumption of feed contaminated with the fungus.     

Structural analysis of a peptide synthetase gene required for ergopeptine production in the endophytic fungus Neotyphodium lolii.

Lysergyl peptide synthetase 1 catalyzes the assembly of toxic ergopeptines from activated D-lysergic acid and three amino acids. The gene encoding this enzyme in the endophytic fungus Neotyphodium lolii was analyzed and compared to a homologous gene from the ergot fungus Claviceps purpurea. Each gene contained two introns, which were found in the same relative position within two modules of the gene. The 5' ends of the two genes were unusually divergent. Signature sequences determining substrate specificity were similar in adenylation domains that recognized identical amino acids but differed within the adenylation domain for the amino acid that varies between the major ergopeptines of the two fungi. Homologues were detected in several related endophytic fungi; the tall fescue endophyte Neotyphodium coenophialum contained a divergent, second copy of the gene. Our results provide new information on the structure and distribution of this important peptide synthetase involved in ergot alkaloid biosynthesis.     

Tinnitus Suppression by Intracochlear Electrical Stimulation in Single Sided Deafness – A Prospective Clinical Trial: Follow-Up

IntroductionEarlier studies show that a Cochlear Implant (CI), capable of providing intracochlear electrical stimulation independent of environmental sounds, appears to suppress tinnitus at least for minutes. The current main objective is to compare the long-term suppressive effects of looped (i.e. repeated) electrical stimulation (without environmental sound perception) with the standard stimulation pattern of a CI (with environmental sound perception). This could open new possibilities for the development of a “Tinnitus Implant” (TI), an intracochlear pulse generator for the suppression of tinnitus.ResultsResults show that tinnitus can be suppressed with intracochlear electrical stimulation independent of environmental sounds, even long term. No significant difference in tinnitus suppression was found between the standard clinical CI and the TI.ConclusionIt can be concluded that coding of environmental sounds is no requirement for tinnitus suppression with intracochlear electrical stimulation. It is therefore plausible that tinnitus suppression by CI is not solely caused by an attention shift from the tinnitus to environmental sounds. Both the standard clinical CI and the experimental TI are potential treatment options for tinnitus. These findings offer perspectives for a successful clinical application of the TI, possibly even in patients with significant residual hearing.

Trial Registration

TrialRegister.nl NTR3374     

Multiple Exposures to Ascaris suum Induce Tissue Injury and Mixed Th2/Th17 Immune Response in Mice

Ascaris spp. infection affects 800 million people worldwide, and half of the world population is currently at risk of infection. Recurrent reinfection in humans is mostly due to the simplicity of the parasite life cycle, but the impact of multiple exposures to the biology of the infection and the consequences to the host’s homeostasis are poorly understood. In this context, single and multiple exposures in mice were performed in order to characterize the parasitological, histopathological, tissue functional and immunological aspects of experimental larval ascariasis. The most important findings revealed that reinfected mice presented a significant reduction of parasite burden in the lung and an increase in the cellularity in the bronchoalveolar lavage (BAL) associated with a robust granulocytic pulmonary inflammation, leading to a severe impairment of respiratory function. Moreover, the multiple exposures to Ascaris elicited an increased number of circulating inflammatory cells as well as production of higher levels of systemic cytokines, mainly IL-4, IL-5, IL-6, IL-10, IL-17A and TNF-α when compared to single-infected animals. Taken together, our results suggest the intense pulmonary inflammation associated with a polarized systemic Th2/Th17 immune response are crucial to control larval migration after multiple exposures to Ascaris.     

Effect of L-propranolol on the binding,internalization and degradation of 125I-low density lipoproteins by human skin fibroblasts

The effect of L-propranolol on the receptor mediated uptake of human LDL by fibroblasts was investigated. When L-propranolol was tested between 10^?6 and 10^?4 M at a ¹²⁵I LDL concentration ranging from 6.25 to 198 μg/ml, an increase in binding, internalization and degradation of the labelled lipoproteins was demonstrated with a maximal effect respectively of 52%, 680% and 105% observed with L-propranolol at 10^?4 M and a lipoprotein concentration of 37.5 μg/ml. The effect occurs rapidly and is seen 2 hrs after the addition of the drug. Lower drug concentrations, although less effective, still produced significant increase in lipoprotein uptake and degradation. Procaine, a local anesthetic, used at 10^?4 M has no effect on ¹²⁵I-LDL binding and internalization. D-propranolol, another local anesthetic and L-propranolol enantiomer, is also without effect. This, excluding a drug induced stabilization of the membrane as the responsible mechanism of action, indicates that stereospecificity is important.     

Relationship between the Accumulation of Putrescine and the Tolerance to Oxygen-Deficit Stress in Gramineae Seedlings

The accumulation of putrescine under anoxia was studied in seedlingsof 6 Gramineae species showing tolerance to the stress in thefollowing order: rice, barnyard grass>maize>rye, barleyand wheat. The accumulation of putrescine in shoots and rootsduring 6 h of oxygen deprivation was different among the speciesand correlated with their tolerance to anaerobic conditions.In both tissues, rice and barnyard grass accumulated more than0.6 µmol/g fresh weight. The lower increase in the putrescinetiter was observed in wheat tissues with less than 0.1 µmol/gfresh weight. Feeding experiments with [^l4C]arginine showedthat rice tissues have a greater capacity than wheat tissuesto synthesize putrescine under anoxia. The better tolerant speciesto anaerobic conditions showed high arginine decarboxylase activityin shoots and roots than the sensitive species. The presenceof exogenous Put partially increased the survival of wheat rootsafter 7.5 h of oxygen-deficit stress. The role of putrescinein determining differences in the tolerance to anoxia in Gramineaeseedlings is discussed. (Received December 20, 1989; Accepted March 12, 1990)