Quantification of jasmonic acid by SPME in tomato plants stressed by ozone

Jasmonates are signalling molecules induced in plants as a response to various biotic and/or abiotic stresses. As ozone is known to activate defense responses in plants, we have monitored the concentration of jasmonic acid in tomato leaves during and after an acute exposure to this abiotic elicitor. In this experiment, we observed that the maximum induction of jasmonic acid in O3-fumigated plants occurred 9 h after the end of treatment and the concentration of jasmonic acid in stressed plants increased 13-fold. However, the level of endogenous methyl-jasmonate was constant during the observed period. The extraction and quantification of jasmonic acid as its methyl ester was performed by headspace-solid-phase microextraction (or HS-SPME) in combination with GC-FID and GC-MS. The sensitivity (LOD = 2 ng/g) of this method permitted the detection and quantification of jasmonic acid present in plant tissues at very low concentrations.     

Distribution of flavonoids and furocoumarins in juices from cultivars of Citrus bergamia Risso

HPLC separation of flavonoids and furocoumarins in the crude juices of three cultivars of Citrus bergamia Risso ("Castagnaro", "Fantastico", and "Femminello") was carried out on a C18 reversed phase column. The analysis was performed in a single run using a DAD detector coupled with an ESI-MS-MS source. Two furocoumarins (bergapten and bergamottin) were detected and quantified simultaneously with the sixteen flavonoid components previously found in industrial bergamot juice. Full characterization of the furocoumarins was performed by (1)H NMR analysis on samples separated by means of preparative HPLC. The free-radical scavenging ability of cultivar juices was assessed by using DPPH radical. The data presented show that the "Femminello" cultivar, even though it is the least common of the three, is by far the richest in health-promoting bioactive compounds (both flavonoids and furocoumarins). Given the range of applications of furocoumarins, the preparative separation described herein is proposed as a simple and rapid method to obtain this class of compounds in good yield from crude juice.     

In vitro antifungal susceptibility of Malassezia pachydermatis from dogs with and without skin lesions

Canine Malassezia dermatitis is frequently treated with systemic ketoconazole (KTZ) and itraconazole (ITZ). However, no information is available on the antifungal susceptibility to azoles and allilamine of Malassezia pachydermatis isolates from dogs with or without skin lesions. The present study was designed to evaluate the in vitro antifungal susceptibility of M. pachydermatis strains from dogs with or without skin lesions to KTZ, ITZ, miconazole (MICO), fluconazole (FLZ), posaconazole (POS), voriconazole (VOR) and terbinafine (TER) using the Clinical and Laboratory Standards Institute reference Broth Microdilution Method (CLSI M27-A2). The association between the susceptibility to antifungal compounds and the origin of M. pachydermatis, from skin with or without lesions has been also assessed. A total of 62 M. pachydermatis strains from healthy dogs (i.e., Group A=30) or with skin lesions (i.e., Group B=32) were tested. ITZ, KTZ and POS showed the highest activity against M. pachydermatis strains, whereas MICO TER and FLZ the lowest. A higher number of Malassezia resistant strains were registered among isolates from Group B than those from Group A. This study indicates that M. pachydermatis strains were susceptible to ITZ, KTZ, and POS. However, dogs with lesions may harbour strains with low susceptibility to antifungal agents and displaying cross-resistance phenomena to azole. The antifungal therapy in Malassezia infections requires careful appraisal of choice of drugs especially in cases of unresponsiveness to antifungal treatment or recurrent infections.     

Deep human genealogies reveal a selective advantage to be on an expanding wave front

Since their origin, human populations have colonized the whole planet, but the demographic processes governing range expansions are mostly unknown. We analyzed the genealogy of more than one million individuals resulting from a range expansion in Quebec between 1686 and 1960 and reconstructed the spatial dynamics of the expansion. We find that a majority of the present Saguenay Lac-Saint-Jean population can be traced back to ancestors having lived directly on or close to the wave front. Ancestors located on the front contributed significantly more to the current gene pool than those from the range core, likely due to a 20% larger effective fertility of women on the wave front. This fitness component is heritable on the wave front and not in the core, implying that this life-history trait evolves during range expansions.     

Synchrony dynamics during initiation, failure, and rescue of the segmentation clock

The "segmentation clock" is thought to coordinate sequential segmentation of the body axis in vertebrate embryos. This clock comprises a multicellular genetic network of synchronized oscillators, coupled by intercellular Delta-Notch signaling. How this synchrony is established and how its loss determines the position of segmentation defects in Delta and Notch mutants are unknown. We analyzed the clock's synchrony dynamics by varying strength and timing of Notch coupling in zebra-fish embryos with techniques for quantitative perturbation of gene function. We developed a physical theory based on coupled phase oscillators explaining the observed onset and rescue of segmentation defects, the clock's robustness against developmental noise, and a critical point beyond which synchrony decays. We conclude that synchrony among these genetic oscillators can be established by simultaneous initiation and self-organization and that the segmentation defect position is determined by the difference between coupling strength and noise.     

Alternative matrices for cortisol measurement in fish

Plasma cortisol is the most commonly used indicator of stress in fish but, as the blood sampling procedure itself can be a source of stress, it would be helpful to measure cortisol using less invasive matrices. It is also necessary to find alternative matrices as stress indicators in dead fish in which blood sampling is impossible. In the present study, we investigated transport stress in three aquaculture species, European sea bass (Dicentrarchus labrax L.), common carp (Cyprinus carpio L.) and rainbow trout (Oncorhynchus mykiss Walbaum), by cortisol determination (radioimmunoassay) in plasma and other matrices (skin mucus, gut content, lateral muscle and caudal fin). Cortisol significantly increased after transport in all species and matrices, except in the sea bass gut content, where it remained unchanged. The three species responded to transport stress by producing different cortisol levels. In conclusion, the significant correlation found between plasma cortisol and most of the other matrices opens up the possibility of using them to evaluate stress in fish: mucus sampling is a less invasive method than blood sampling, and in addition to muscle and fin sampling, it can be used in postmortem fish.     

稻瘟菌株CH63和TH16杂交后代毒性变异及其无毒基因组成

 报道了两个稻瘟菌株CH63和TH16的杂交后代在36个水稻品种上的致病性分离、遗传分析以及无毒基因组成的分析结果。78个子囊孢子菌株中呈现显著的致病性分离，共出现71种致病类型，在不同品种上分别出现1∶1、1∶3、3∶1、1∶7、1∶15和15∶1等的无毒性/毒性分离，表明供试菌株对不同品种的无毒性/毒性是一个或多个基因控制的。遗传学分析结果表明，亲本菌株对不同品种的无毒性/毒性控制存在多种类型。菌株CH63对品种K 59(Pi-t)、中98－18、特特普、T 641、C 102 TTP(Pi-4)、C 101 TTP 6、E No.11、农虎6号、C 101 PKT(Pi-4a)、C 105 TTP-1(Pi-4)、中156 和中98－19分别持有1个无毒基因；对品种1461选、6392选、麻谷泰引1号、Lemont、宫崎7号、Vandana、长香稻、青珍8号和珍优3号分别持有2个无毒基因；对于品种草笛（Pi-k）、品种20中－1 、C 104 LAC(Pi-1)、C 103 TTP(Pi-1+1b)、K 3(Pi-kh)、梅雨明 (Pi-km)和东农363分别持有2个以上无毒基因；亲本菌株对于品种四丰43、珍龙13、C101LAC和20中－2分别持有2个无毒基因，关东51、欧244持有2个以上的无毒基因，但因亲本菌株对品种的致病型一致，难以判断控制菌株对品种非亲和性的基因来源。     

The BRCT domain is a phospho-protein binding domain

The carboxyl-terminal domain (BRCT) of the Breast Cancer Gene 1 (BRCA1) protein is an evolutionarily conserved module that exists in a large number of proteins from prokaryotes to eukaryotes. Although most BRCT domain-containing proteins participate in DNA-damage checkpoint or DNA-repair pathways, or both, the function of the BRCT domain is not fully understood. We show that the BRCA1 BRCT domain directly interacts with phosphorylated BRCA1-Associated Carboxyl-terminal Helicase (BACH1). This specific interaction between BRCA1 and phosphorylated BACH1 is cell cycle regulated and is required for DNA damage-induced checkpoint control during the transition from G2 to M phase of the cell cycle. Further, we show that two other BRCT domains interact with their respective physiological partners in a phosphorylation-dependent manner. Thirteen additional BRCT domains also preferentially bind phospho-peptides rather than nonphosphorylated control peptides. These data imply that the BRCT domain is a phospho-protein binding domain involved in cell cycle control.     

Microtubule stabilization reduces scarring and causes axon regeneration after spinal cord injury

Hypertrophic scarring and poor intrinsic axon growth capacity constitute major obstacles for spinal cord repair. These processes are tightly regulated by microtubule dynamics. Here, moderate microtubule stabilization decreased scar formation after spinal cord injury in rodents through various cellular mechanisms, including dampening of transforming growth factor-β signaling. It prevented accumulation of chondroitin sulfate proteoglycans and rendered the lesion site permissive for axon regeneration of growth-competent sensory neurons. Microtubule stabilization also promoted growth of central nervous system axons of the Raphe-spinal tract and led to functional improvement. Thus, microtubule stabilization reduces fibrotic scarring and enhances the capacity of axons to grow.