Evaluation of the effect of chitin-rich residues on the chitinolytic activity of Trichoderma harzianum: In vitro and greenhouse nursery experiments

The chitin-rich residues obtained from several industries have numerous applications in diverse fields such as biotechnology, pharmacology, medicine and agriculture. In this study, three different chitin-rich residues were evaluated with regard to enhancement of the chitinolytic activity of the mycoparasitic fungus Trichoderma harzianum, used for biological control of Fusarium oxysporum in greenhouse nurseries. Chitosan (CHIT), shrimp shell powder (SSP) and mushroom wastes (MW) activated the expression of the T. harzianum genes encoding the NAGase and chitinase activities (exc1, exc2, chit42, chit33 and chit37), the highest in vitro activities of T. harzianum being seen with MW. Under greenhouse nursery conditions, the treatments involving amendment with these residues and with T. harzianum increased the NAGase activity (between 5- and 20-times higher than peat) and the chitinase activity (between 3- and 6-times higher than peat) of the growing media and maintained the shoot dry weight of plants infected with F. oxysporum. Moreover, the incorporation of these residues into the growing media enhanced the growth (first leaf length, stem length and shoot dry weight) of muskmelon seedlings. The use of these residues with T. harzianum as amendments of growing media enhanced the growth of muskmelon seedlings and decreased the weight loss due to the pathogen, giving an added-value to these residues and enhancing their management.     

Development of an Isavirus minigenome system to study the function of the pocket RNA-binding domain of the viral nucleoprotein (NP) in salmon cells

The Isavirus is an orthomyxovirus with a genome composed of eight segments of negative single-strand RNA (−ssRNA). It has been proposed that the eight genomic segments of the Isavirus are organized as a ribonucleoprotein (RNP) complex called a minigenome, which contains all the viral RNA segments, a viral heterotrimeric polymerase and multiple copies of the viral nucleoprotein (NP). Here, we develop an Isavirus minigenome system and show the importance of the formation of active RNPs and the role of viral NP R189, R194, R302 and K325 residues in the NP RNA-binding domain in the context of RNPs. The results indicate it is possible to generate a minigenome in salmon cells, a composite ISAV RNPs with EGFP-based chimeric vRNA with heterotrimeric polymerase (PB1, PB2, PA) and NP protein using CMV-based auxiliary plasmids. It was also shown that NP R189, R194, R302 and K325 residues are important to generate viral mRNA from the constituted RNPs and a detectable reporter protein. This work is the first salmon cell-based minigenome assay for the Isavirus, which was evaluated by a bioinformatic and functional study of the NP protein in viral RNPs, which showed that correct NP-vRNA interaction is key to the functioning of RNPs.     

Influence of dietary fatty acids and cholesterol on the growth and survival of the Argentine prawn,Artemesia longinaris Bate

The influence of essential fatty acids and cholesterol on the growth and survival of the Argentine shrimp Artemesia longinaris, was tested using experimental pelleted diets based on a standard diet. A series of diets were designed and prepared by adding cholesterol, pure oleic acid, raw linseed oil and fish oil (rich in fatty acids of the ω 3 series).After 30 days, no significant differences in growth were registered among the animals fed different rations, although significant differences in survival were found. The best survival was obtained with the diet supplemented with fish oil (87.3%). Survival of prawns fed the other diets was significantly lower (53.3–56.7%). Animals fed low fat diet, showed the lowest survival (30%).The results indicated the importance of cholesterol in the diet, and stressed the dietary necessity of highly unsaturated fetty acids of the linolenic acid series for the optimal survival of A. longinaris.     

Influence of control parameters in VOCs evolution during MSW trimming residues composting

The influence of control parameters (aeration, moisture, and C/N ratio) during composting of a municipal solid waste (MSW)-legume-trimming residue (LTR) mixture was studied at a pilot plant scale. Factors measured included the composition of the main volatile organic carbons (VOCs) emitted including limonene, β-pinene, 2-butanone, undecane, phenol, toluene, and dimethyl disulfide. Polynomial models were found to reproduce the experimental results with errors at less than 10%. The relative influence of the independent variables on temperature and selected VOCs followed the order: aeration > moisture > C/N. A high aeration rate results in higher (strong negative effect) values on selected VOCs emissions (41-71% on emitted VOCs variation). Moisture had a positive and negative effect depending on the selected VOCs. A high C/N ratio caused lower production of VOCs except for undecane and 2-butanone. Providing an aerobic environment (0.05 Lair kg(-1) min(-1)), high C/N ratios (>50), and medium moisture (55%) minimize emitted VOCs during MSW composting, ultimately resulting in less odors in the surrounding environment.     

A classical nova,V2487 Oph 1998, seen in x-rays before and after its explosion

Classical nova explosions are very energetic and frequent phenomena caused by explosive hydrogen burning on top of an accreting white dwarf. Observations of the recent nova V2487 Oph 1998 by the X-ray Multi-Mirror satellite (XMM-Newton) provide evidence that accretion (probably on a magnetic white dwarf) was reestablished as early as 2.7 years after the explosion. In addition, positional correlation with a source previously discovered by the R?ntgen Satellite (ROSAT) in 1990 suggests that the site of a nova explosion had been seen in x-rays before the outburst.     

Root morphology of Thlaspi goesingense Hálácsy grown on a serpentine soil

The contribution of root morphology to enhanced uptake of heavy metals by hyperaccumulating plants is not well understood. The objective of this study was to describe root‐morphological characteristics of the natural nickel (Ni) hyperaccumulator Thlaspi goesingense Hálácsy. Plant samples were collected from a serpentine site near Redlschlag (East Austria), characterized by large soil Ni concentrations. Roots were evaluated for mass, length, surface area, diameter, and related ratios using an image‐analysis approach. Results showed that on the indigenous site, T. goesingense Hálácsy developed a fine‐branched root system, confined within a shallow soil depth. Coarse roots (>1 mm) accounted for about 60% of the total root mass (fresh and dry), while their contribution to the surface area and especially to the length of the system was small. Conversely, fine roots (<1 mm) represented 99% of the total root length and 88% of the surface area. The largest proportion of root length and area was found in the smallest diameter class of 0.0 to 0.5 mm. Shoot‐biomass production per unit root was high, in spite of the adverse soil conditions. Roots accounted for 8% of the total plant mass and about 4% of the total Ni accumulation. We conclude that the root system of natively grown T. goesingense Hálácsy exhibits a potential for enhanced Ni extraction from soil, since it mainly consists of very fine roots with extended absorptive area.     

Isolation of amoebae of the genera Naegleria and Acanthamoeba from public fountains in Galicia (N.W. Spain)

Tests for free-living amoebae in water from 11 public fountains in Galicia were conducted at two seasons of the year, winter and summer. Only one fountain gave a negative result for the presence of amoebae in both samples. Twenty five strains were isolated, 14 belonging to the genus Acanthamoeba and 10 to the genus Naegleria. The Acanthamoeba strains were made up of the species A. polyphaga, A. quina, A. castellanii and A. paradivionensis. No relation was found between temperature, presence of free chlorine in the water and whether the water was drinkable and the presence or absence of amoebae, nor with the number of strains present in the water samples. The pathogenic capacity of the strains isolated from the genera Naegleria and Acanthamoeba was tested in vivo. It was found that of the 22 strains that would grow at 37 °C, 4 (3 strains of Acanthamoeba and 1 of Naegleria) caused the death of a statistically significant number of mice that had been inoculated intracerebrally, and the presence of amoebae was confirmed in the brains of all the animals inoculated. Intranasal inoculation caused less mice deaths than intracerebral inoculation, and less organs were found containing amoebae.     

Biosorption Capacity for Cadmium of Brown Seaweed Sargassum sinicola and Sargassum lapazeanum in the Gulf of California

Brown algae Sargassum sinicola and Sargassum lapazeanum were tested as cadmium biosorbents in coastal environments close to natural and enriched areas of phosphorite ore. Differences in the concentration of cadmium in these brown algae were found, reflecting the bioavailability of the metal ion in seawater at several sites. In the laboratory, maximum biosorption capacity (q _max) of cadmium by these nonliving algae was determined according to the Langmuir adsorption isotherm as 62.42?±?0.44 mg g^?1 with the affinity constant (b) of 0.09 and 71.20?±?0.80 with b of 0.03 for S. sinicola and S. lapazeanum, respectively. Alginate yield was 19.16?±?1.52% and 12.7?±?1.31%, respectively. Although S. sinicola had far lower biosorption capacity than S. lapazeanum, the affinity for cadmium for S. sinicola makes this alga more suitable as a biosorbent because of its high q _max and large biomass on the eastern coast of the Baja California Peninsula. Sargassum biomass was estimated at 180,000 t, with S. sinicola contributing to over 70%.     

A Survey of Infectious Diseases and Parasites of Penaeid Shrimp from the Gulf of Mexico

A histopathological survey of wild and cultured shrimp from the Gulf of Mexico was carried out to determine the prevalence and severity of infectious diseases and parasites, affecting four species of penaeid shrimp (Litopenaeus setiferus, Farfantepenaeus aztecus, F. duorarum, and L. vannamei). Around 60 shrimp were obtained from each of 10 sampling stations during different months in 1999 and 2000. One station was a shrimp culture farm from Tamaulipas State, and nine were wild stations from Tamaulipas (five), Veracruz (one), and Campeche (three) States. Thirty shrimp from each station were used for histological analysis. The remaining shrimp were frozen and kept at ?20 C to carry out PCR techniques to determine the presence of white spot syndrome virus (WSSV). Some in situ hybridization analyses were applied to ascertain cases of WSS viral disease. Fresh analysis was carried out in shrimp from only one station for parasite identification. The histopathological survey performed on 688 shrimp showed no evidence of viral diseases. Two shrimp from one station were histologically diagnosed as having presumptive WSSV. Tissues from the same shrimp were processed for in situ hybridization and another 20 samples from the same station were processed to run PCR techniques. In each case, the results were negative. The same PCR procedure was applied to the rest of the frozen samples and none of them showed the presence of the WSSV. No important bacterial infections were observed in any of the wild or cultured shrimp analyzed. Fresh analysis demonstrated the presence of the cestode Prochristianella hispida and the gregarines Cephalolobus penaeus and Nematopsis penaeus. Histological analysis showed that the abundance of P. hispida varied from 7 to 90%, and G1 to G4 grades of severity were observed, with G1 being the most common. Gregarines were commonly observed in the histological slides, with a prevalence varying from 3 to 56% and G1 severity in most cases. Haplosporidan infection was observed in one sample of F. duorarum, which is the first report of this parasite in this host. Two invasive epibionts, the filamentous bacteria Leucothrix sp. and the ciliate Ascophrys sp., were found in four sampled stations. The study showed that in ten stations sampled from 1999 to 2000 in the Gulf of Mexico, shrimp populations had no serious infectious diseases.     

Presence of an emerging pathogen of amphibians in introduced bullfrogs Rana catesbeiana in Venezuela

Chytridiomycosis is an emerging fungal disease of amphibians responsible for mass mortalities and population declines globally. One hypothesis for its recent emergence is anthropogenic introduction of the causative agent Batrachochytrium dendrobatidis through trade in amphibians for pets, food and biocontrol. In this study, we examined histological samples from apparently healthy American bullfrogs Rana catesbeiana that have been introduced into the Venezuelan Andes. B. dendrobatidis was present in 96% (46/48) of the individuals examined. In contrast to cases of chytridiomycosis outbreaks, the majority (44/46) of frogs had few, small lesions consistent with little or no clinical disease and no unusual mortality was observed. These findings have implications for amphibian declines in Venezuela and elsewhere. First, the high prevalence of Batrachochytrium but lack of clinical signs or chytridiomycosis-related mortality suggests that R. catesbeiana may be a good reservoir for this parasite in Venezuela. Second, the presence of this emerging pathogen in an introduced amphibian species suggests that trade and introduction of amphibians should be monitored and controlled to halt the spread of this pathogen nationally and internationally.