Genetics of host-pathogen interactions in the <Emphasis Type="Italic">Pyrenophora teres</Emphasis> f. <Emphasis Type="Italic">teres</Emphasis> (net form) – barley (<Emphasis Type="Italic">Hordeum vulgare)</Emphasis> pathosystem

The genetics of host-pathogen interactions in the Hordeum vulgare – P. teres f. teres pathosystem was studied in twelve resistant barley accessions, i.e. CI 9825, CI 9819, Diamond, CI 4922, CI 5401, Harbin, c-8755, c-21849, c-8721 c-23874, c-19979, c-15811. F₂ analyses of crosses with susceptible genotypes employing various isolates (from Europe, USA, Canada, and Australia) revealed that resistance is mostly isolate-specific and controlled by one or two genes. Segregation in ascospore progeny from two crosses between isolates of different origin revealed that avirulence in P. teres is also determined by one or two genes. An epistatic effect of suppressor genes on avirulence genes is proposed for the genetics of virulence to Diamond, Harbin, CI 5401 and c-8721 in the fungal crosses D (181-6 × A80) and F (H-22 × 92-178/9). Segregation in F₂ of crosses of three new sources of resistance (c-23874, c-19979, c-15811) to the susceptible cv. Pirkka was studied in laboratory and greenhouse tests by using seven P. teres isolates, i.e. 181-6, d8-3, d8-4, d9-1, d9-4, F4 and F74. In addition, virulence to these barley accessions of ascospore progeny from crosses of the same isolates was studied. Based on these studies it was concluded that depending on the isolate used, resistance of c-23874 is determined at least by two genes and in c-19979 and c-15811 by three genes. The results of this parallel analyses of genetics of resistance and genetics of virulence allows the postulation of a gene–for–gene interaction in the P. teres – H. vulgare pathosystem.     

Water supply and growing season influence glucosinolate concentration and composition in turnip root (Brassica rapa ssp. rapifera L.)

The overall objective of this study was to determine whether growing season, water supply, and their interaction influence glucosinolate (GSL) concentration and composition in turnip roots (Brassica rapa ssp. rapifera L.). Field experiments on a loamy soil in Großbeeren, Germany, were conducted in the spring‐summer (SS), summer‐autumn (SA), and autumn‐winter (AW) growing seasons. Each experiment included three water‐supply treatments with 25%, 50%, and 75% of available soil water (ASW) as lower thresholds. We found that the total GSL concentration in turnip roots was 1774–3221 μmol (kg fresh matter [FM])^–1 and the dominant GSL was aromatic gluconasturtiin (GST) with concentrations of 1004–1628 μmol (kg FM)^–1 in turnip roots. Total, aliphatic, and some specific individual GSLs in turnip roots were significantly influenced by water supply, growing season, and their interaction, due to the variations of the root sulfur (S) concentration, climatic conditions, or both. The influence of water supply on GSL concentration was modified by growing season, which in turn influenced S concentration in turnips. In the SS season, the 25%‐ASW water treatment enhanced concentrations of total GSLs by 52% and 47%, aliphatic GSLs by 60% and 131%, and aromatic GSLs by 47% and 21% when compared to the 50%‐ and 75%‐ASW water treatments, respectively. No reduction of root yield was observed, although the shoot yield was reduced by limited water supply. In SA and AW, total GSL concentration did not change under different water‐supply levels, but concentration of individual aliphatic and indole GSLs did. Based on these results, growers can adjust their irrigation and S‐fertilization practices to growing season in order to optimize turnip quality in terms of GSL concentration and composition, while still obtaining higher root yield and enabling better resource utilization.     

Understanding feline behavior and application for appropriate handling and management

Feline handling in the veterinary hospital is important to protect both people and cats. Restraint has been used to enable us to perform our duties as veterinarians. With increased knowledge of feline behavior and how cats react to fear, newer information provides us with safer handling techniques. With safer and more respectful handling based on understanding the nature of cats and their communication, we can improve feline health care in our hospitals, the human-animal-veterinarian bond, and the welfare of both cats and people. This article explains important aspects of feline communication and how our actions affect cats. By understanding the cat, we can improve our handling techniques to prevent fear and pain for our feline patients, and thus make our veterinary practices more feline friendly and safer for our clients, their cats, and veterinary staff.     

Protective role of <Emphasis Type="Italic">S</Emphasis>-methylmethionine-salicylate in maize plants infected with <Emphasis Type="Italic">Maize dwarf mosaic virus</Emphasis>

This study aimed to detect the harmful effects of Maize dwarf mosaic virus (MDMV) infection, and to demonstrate the potential benefits of S-methylmethionine-salicylate (MMS) pretreatment in infected maize (Zea mays L.) plants. The results of chlorophyll a fluorescence measurements showed that in MDMV-infected plants additional quenchers of fluorescence appear, probably as the result of associations between the virus coat protein and thylakoid membranes. It is important to note that when infected plants were pretreated with MMS, such associations were not formed. MDMV infection and MMS pretreatment resulted in a decrease in ascorbate peroxidase (APX) activity in maize leaves, while infection contributed to an increase in activity in the roots. Infection raised the guaiacol peroxidase (GPX) enzyme activity level, which was reduced by MMS pretreatment. MMS contributed to a decrease in both the RNA and coat protein content of MDMV, to an equal extent in maize leaves and roots. The results showed that MMS pretreatment enhanced the stress response reactions against MDMV infection in maize plants and retarded the spreading of infection.     

A new approach to water disinfection: I. N,N-dimethylalkylbenzyl-polystyrene anion exchange resins as contact disinfectants

A quaternary ammonium type anion exchange resin with the N,N-dimethyldodecylbenzyl moiety as the functional group was synthesized and tested as a contact water disinfectant. The long chain alkyl groups are attached to a conventional polystyrene matrix with 2% divinylbenzene as a crosslinker which is insoluble and chemically stable. Suspensions containing up to a total of >10⁹ live cells of the gram positiveBacillus subtilis were disinfected by passage through 1 ml beds of the polymer, Resin 12, at flow rates of 10 to 12 ml min^?1 before any viable cells could be detected in the effluent. The disinfectant action increased with increasing temperature and was attributed to the intrinsic antimicrobial properties of the N,N-dimethyldodecylbenzyl function. The large disinfectant capacity and instant disinfection on contact may be understood as a consequence of the extremely high surface concentration of the quaternary functions on the resin beads and the strong hydrophobic effect driving the organisms toward the solution-resin interface. Resin 12 can be regenerated although the ethanolic HCL used in our experiments should be replaced by a less harsh regenerant for practical applications. The results obtained with Resin 12 are to be seen as the demonstration of a new approach to water disinfection using insoluble contact antimicrobials as an alternative to chlorination and other methods based on soluble, reactive agents.