Multilocus sequence typing analysis of Italian Xanthomonas campestris pv. campestris strains suggests the evolution of local endemic populations of the pathogen and does not correlate with race distribution

Xanthomonas campestris pv. campestris (Xcc) is the causal agent of black rot in Brassicaceae. It is widespread in Italy and severe outbreaks occur under conditions that favour disease development. In this study a multilocus sequence typing approach (MLST) based on the partial sequence of seven loci was applied to a selection of strains representative of the main areas of cultivation and hosts. The aim was to investigate whether the long tradition of brassica crops in Italy has influenced the evolution of different Xcc populations. All loci were polymorphic; 14 allelic profiles were identified of which 13 were unique to Italian strains. Based on the seven loci, the most common genotype within the Italian Xcc strains (AP1) was also the most representative genotype found in worldwide Xcc strains. This genotype was included in a new clonal complex in addition to three other clonal complexes already identified in Xcc populations. The phylogenetic reconstruction using a concatenated dataset of four conserved protein-coding genes, dnaK, fuyA, gyrB and rpoD, showed that the Italian strains belonged to two genetic groups. Physiological races were also investigated for the first time in Italy. The race structure of Xcc was determined by inoculating eight differential Brassica lines belonging to five species and showed that, in Italy, race 4 is the most widespread, followed by races 1 and 6. No correlation was found between allelic profiles, host of isolation, geographical origin and races, although a prevalent race was identified within the same clonal complex.     

Expression of Orexin A and its Receptor 1 in the Epididymis of the South American Camelid Alpaca (Vicugna pacos)

Orexins A (ox A) and B are two peptides originally discovered in neurons of rat hypothalamus, and later found in different cellular types of the gastrointestinal and genital tracts. They arise from the proteolytic cleavage of a common precursor molecule, prepro‐orexin, and bind to two receptors, namely receptor 1 (ox1r) and receptor 2 for orexins, that show different binding affinity. The central role of the two peptides has been extensively studied, whereas their activity in the periphery is still poorly known. Here, we investigated the presence of ox A and ox1r in the epididymis of a South American camelid species, the alpaca, by immunohistochemistry, and we also assessed the expression of prepro‐orexin and ox1r in tissue extracts by Western blotting analysis. Ox A‐ and ox1r‐immunoreactivity was found in the cytoplasm of principal cells of the caput epididymis. A prevalent supranuclear localization of granular‐shaped positive material was observed. No positivity was present in the other cytotypes of epididymis. The expression of two peptides with molecular weight corresponding to those of prepro‐orexin and ox1r, respectively, was detected in the tissue extracts from the organ.     

Fishing for conservation of freshwater tropical fishes in the Anthropocene

相似文献   

In Vitro Mechanical Evaluation of a Novel Pin–Sleeve System for External Fixation of Distal Limb Fractures in Horses: A Proof of Concept Study

Objective: To evaluate the efficacy of a novel pin–sleeve cast (PSC) system for external fixation of distal limb fractures in horses and to compare it with the transfixation pin cast (TPC) system. Study Design: Experimental. Sample Population: One bone substitute each was used for the TPC and PSC systems. The PSC was tested in 4 configurations characterized by different pin preloads. Methods: Specimens were loaded in axial compression in the elastic range. Variables compared statistically were: bone substitute axial displacement and axial strain measured above implants with strain gauges. Pin preload was correlated with the variables investigated. Load to failure and a fatigue tests supplemented the investigation. Results: The PSC configuration with the highest pin preload showed a significantly lower axial displacement compared with the TPC. No significant differences were observed between all other PSC configurations and the TPC. All PSC systems had a significant decrease in recorded strain compared with the TPC system. Pin axial preload inversely correlated with axial displacement but had no effect on axial strain. In the failure test, the PSC encountered plastic deformation earlier than the TPC. In the fatigue test, the PSC ran >200,000 cycles. Conclusions: Preliminary in vitro tests showed that the PSC system significantly reduced peri‐implant strain while concurrently having comparable axial displacement to the TPC system. Clinical Relevance: The PSC system has the potential to reduce the risk of pin loosening in horses.     

Specific Oligonucleotide Primers for the Rapid Identification and Detection of the Agent of Tomato Pith Necrosis, Pseudomonas corrugata, by PCR Amplification: Evidence for two Distinct Genomic Groups

Unique DNA bands from strains representative of two groups of Pseudomonas corrugata, as shown by amplification of their genomic DNA by polymerase chain reaction using short random sequence oligonucleotide primers (RAPD-PCR), were isolated, cloned and sequenced. Two pairs of specific primer sequences, based on the ends of the cloned unique DNA bands from strains IPVCT10.3 and IPVCT8.1, were used in multiplex PCR with a range of P. corrugata strains. All strains produced one of the two specific bands, 1100bp (from the IPVCT10.3-based primers) and 600bp (from the IPVCT8.1-based primers), representing groups designated I and II, respectively. The primers were also tested on a wider range of Pseudomonas species, including the closely-related fluorescent Pseudomonas genomospecies FP1, FP2 and FP3: none of these bacteria produced any bands following amplification by PCR with these primers. The primer sets detected P. corrugata in tomato pith necrosis-infected plants providing a useful tool for rapid identification and epidemiological studies.     

The fine structure of the male genital organs of Allacma fusca (L.) (Collembola, Symphypleona)

The fine structure of the male reproductive system of Allacma fusca (L.) is described. The system consists of testes, deferent ducts, seminal vesicles, ejaculatory duct and accessory glands. The nature of each part is established. Secretions from the seminal vesicles are stored in the lumen of these organs, then flow into the ejaculatory duct and are used to produce spermatophores. The epithelium of this tract has secretory activity and osmoregulatory function. Secretions and spermatozoa are stored into two distinct parts of the ejaculatory duct, divided by a transverse cuticular septum.     

Sorption and degradation of azimsulfuron on iron(III)-rich soil colloids

The sorption of N-[[(4,6-dimethoxypyrimidin-2-yl)amino]carbonyl]-1-methyl-4-(2-methyl-2H-tetrazole-5-yl)1H-pyrazole-5-sulfonamide (AZS) on an iron oxide, iron(III)-humate, and an Fe3+-saturated clay was studied using a batch equilibrium method. Generally, 20 mg of each colloid was equilibrated with 20 mL of AZS solution (1.5-12.7 microM). The sorption on iron-montmorillonite and iron oxide was rapid, and the equilibrium was attained within 1.5 and 5 h, respectively. In the case of Fe-saturated humic acid the equilibrium time was 20 h. After equilibration, the phases were centrifuged (19000g, 15 min) and the supernatant was sampled and analyzed by HPLC. The values of Freundlich constants indicate that iron oxide (Kads = 199.5) shows the highest sorptive capacity toward AZS, followed by iron(III)-clay (Kads = 146.6) and iron(III)-humate (Kads = 108.2). With elapsing time, AZS degradation was observed in all colloidal suspensions. Iron-humate (t(1/2) = 136 h) is most effective in promoting AZS degradation, followed by iron oxide (t(1/2) = 204 h) and iron-clay (t(1/2) = 385 h). The metabolites 2-amino-4,6-dimethoxypyrimidine and 1-methyl-4-(2-methyl-2H-tetrazole-5-yl)-1H-pyrazole-5-sulfonamide, arising from a hydrolytic cleavage of the sulfonylurea bridge, were the only byproducts observed. A Fourier transform infrared study suggests that the sorption of AZS on iron-clay involves the protonation of one of the two basic pyrimidine nitrogens induced by the acidic water surrounding the saturating Fe3+ ions. Instead, the formation of a six-membered chelated complex favors the sorption of AZS on iron oxide.     

Azimsulfuron sorption--desorption on soil

The sorption and desorption of the herbicide azimsulfuron, N-[[(4-dimethoxypyrimidin-2-yl)amino]carbonyl]1-methyl-4-(2-methyl-2H-tetrazole-5-yl)1H-pyrazole-5-sulfonamide, were studied using five soils. Sorption isotherms conformed to the Freundlich equation. It was found that pH is the main factor influencing the sorption and that the sorption on soils was negatively correlated with pH. The highest level of sorption was measured on soils with low pH and high organic carbon content. Moreover, inorganic soil colloids, for example, smectite clay minerals and iron oxides, contributed to the sorption of azimsulfuron. Desorption was hysteretic on soils with high organic and inorganic colloid contents.     

Effect of wine inhibitors on free pineapple stem bromelain activity in a model wine system

The influence of potential inhibitors, naturally present in wine, on the activity of stem bromelain was investigated in order to evaluate the applicability of this enzyme for protein stabilization in white wine. Bromelain proteolytic activity was tested against a synthetic substrate (Bz-Phe-Val-Arg-pNA) in a model wine system after adding ethanol, sulfur dioxide (SO(2)), skin, seed, and gallic and ellagic tannins at the average range of their concentration in wine. All the inhibitors of stem bromelain activity tested turned out to be reversible. Ethanol was a competitive inhibitor with a rather limited effect. Gallic and ellagic tannins have no inhibitory effect on stem bromelain activity, while both seed and skin tannins were uncompetitive inhibitors. The strongest inhibition effect was revealed for sulfur dioxide, which was a mixed-type inhibitor for the enzyme activity. This study provides useful information relative to a future biotechnological application of stem bromelain in winemaking.