Vibrogen‐2 vaccine trial in lumpfish (Cyclopterus lumpus) against Vibrio anguillarum

Lumpfish (Cyclopterus lumpus), a native fish of the North Atlantic Ocean, is utilized as cleaner fish to biocontrol sea lice infestations in Atlantic salmon aquaculture. However, bacterial infections are affecting cleaner fish performance. Vibrio anguillarum, the aetiological agent of vibriosis, is one of the most frequent bacterial infections in lumpfish, and effective vaccine programmes against this pathogen have been identified as a high priority for lumpfish. Vibrogen‐2 is a commercial polyvalent bath vaccine that contains formalin‐inactivated cultures of V. anguillarum serotypes O1 and O2, and Vibrio ordalii. In this study, we evaluated Vibrogen‐2 efficacy in lumpfish against a local isolated V. anguillarum strain. Two groups of 125 lumpfish were bath‐immunized, bath‐boost‐immunized at four weeks post‐primary immunization, and intraperitoneally (i.p.) boost‐immunized at eight weeks post‐primary immunization. The control groups were i.p. mock‐immunized with PBS. Twenty‐seven weeks post‐primary immunization, the fish were i.p. challenged with 10 or 100 times the V. anguillarum J360 LD₅₀ dose. After the challenge, survival was monitored daily, and samples of tissues were collected at ten days post‐challenge. Commercial vaccine Vibrogen‐2 reduced V. anguillarum tissue colonization and delayed mortality but did not confer immune protection to C. lumpus against the V. anguillarum i.p. challenge.     

Canopy Size and Induced Resistance in Stylosanthes scabra Determine Anthracnose Severity at High CO(2)

ABSTRACT This study examines the relative importance of canopy size and induced resistance to Colletotrichum gloeosporioides at 350- and 700-ppm atmospheric CO(2) concentrations on susceptible Stylosanthes scabra 'Fitzroy' from two studies in a controlled environment facility (CEF) and in the field. Plants were grown at the two CO(2) concentrations in a repeated experiment in the CEF and inoculated at 6, 9, or 12 weeks of age. Although the physiological maturity of plants was at a similar stage for all three ages, the number of lesions per plant increased with increasing plant age at both CO(2) concentrations. At 350 ppm, the increase was associated with canopy size and increasing infection efficiency of the pathogen, but at 700 ppm, it was associated only with canopy size, because infection efficiency did not change with increasing age. A level of resistance was induced in plants at 700 ppm CO(2). In a second study, plants were raised for 12 to 14 weeks at the two CO(2) concentrations in the CEF and exposed to C. gloeosporioides inoculum in replicated field plots under ambient CO(2) over three successive years. Fitzroy developed a dense and enlarged canopy, with 28 to 46% more nodes, leaf area, and aboveground biomass at high CO(2) than at low CO(2). Up to twice as many lesions per plant were produced in the high CO(2) plants, because the enlarged canopy trapped many more pathogen spores. The transient induced resistance in high CO(2) plants failed to operate when exposed to pathogen inoculum under ambient CO(2) in the field. These results highlight the need to consider both canopy size and host resistance in assessing the influence of elevated CO(2) on plant disease.     

African origin of modern humans in East Asia: a tale of 12,000 Y chromosomes

To test the hypotheses of modern human origin in East Asia, we sampled 12,127 male individuals from 163 populations and typed for three Y chromosome biallelic markers (YAP, M89, and M130). All the individuals carried a mutation at one of the three sites. These three mutations (YAP+, M89T, and M130T) coalesce to another mutation (M168T), which originated in Africa about 35,000 to 89,000 years ago. Therefore, the data do not support even a minimal in situ hominid contribution in the origin of anatomically modern humans in East Asia.     

Protein modification by amino acid addition is increased in crushed sciatic but not optic nerves

Rat optic and sciatic nerves were crushed, and 10 minutes to 3 days later nerve segments between the crushed site and the cell body were removed and assayed for posttranslational protein modification by amino acid addition. Protein modification was comparable in intact optic and sciatic nerves, but in sciatic nerves increased to 1.6 times control levels 10 minutes after crushing and reached a maximum of ten times control levels by 2 hours. In optic nerves activity was decreased throughout the time course studied. The results indicate that, in a nerve which is capable of regeneration (sciatic), protein modification by the addition of amino acids increases immediately after injury, but a nerve incapable of regeneration (optic) is incapable of activating the modification reaction. These findings may be important in understanding the reasons for the lack of a regenerative response after injury to central mammalian nerves.     

Mycophagous soil amoeba: Interactions with three plant pathogenic fungi

An amoeba of the order Leptomyxida was isolated from wheat take-all decline soil and was found to attack and lyse hyphae and spores of Gaeumannomyces graminis var. tritici and Phytophthora cinnamomi. The amoeba enveloped portions of hyphae of both fungi and penetrated the cell walls by means of fine holes. One-week old chlamydospores and hyphal swellings of P. cinnamomi were also attacked in this way, protoplast lysis being completed within 1 h. Hyphal fragments which could be ingested by the amoeba were lysed leaving amorphous cell debris. Three-week old chlamydospores of P. cinnamomi were enclosed within large food vacuoles and completely digested in about 20 h. Pigmented conidia of Cochliobolus sativus were transported across the substratum for up to several hours but were not perforated or lysed.