Analysis of chemical changes in Picea abies wood decayed by different Streptomyces strains showing evidence for biopulping procedures

The present study is focused on analysing the suitability of different Streptomyces strains for biomechanical pulping purposes using spruce wood (Picea abies) as substrate. After 2 weeks of incubation, no apparent variations in lignin Klason content of treated woods were detected compared with the control. However, the increase in acid-soluble lignin fraction pointed out chemical alterations in lignin moiety. Through Py-GC/MS analysis enrichment in cellulose and lignin molecule modifications were detected in treated woods. The increase in the relative abundance of the most G-type phenol units with a higher oxidation degree suggests that some oxidation occurred in the lignin C3-alkyl chain. In addition, the decrease in the phenylmethane + phenylethane/phenylpropane (phC1 + ph C2/ph C3) ratio would indicate the ability of Streptomyces strains to breakdown the C3-alkyl chain linkages once carbons had been oxidized. From this study it could be concluded that the assayed strains are able to produce a delignification of spruce wood which may improve mechanical pulping processes.     

A wide diversity of zoonotic intestinal parasites infects urban and rural dogs in Neuquén,Patagonia, Argentina

The presence of parasites was investigated by the examination of 1944 dog faecal samples collected from urban (n = 646) and rural (n = 1298) areas of the province of Neuquén, Patagonia, Argentina. Parasitic agents (PA) were found in 37.86% of samples. A total of 15 different PA were detected, including Toxocara canis (16.35%), Taenia spp./Echinococcus spp. (12.65%), Trichurisvulpis (6.06%), Giardia spp. (1.29%), Toxascaris leonina (0.56%), Ancylostomacaninum (0.41%), Dipylidium caninum (0.31%), Diphyllobothrium spp. (0.10%), among others. Several of these PA are recognized as zoonotic agents. Therefore, the results of this investigation revealed that local population is exposed to a broad spectrum of zoonotic parasites by means of environmental contamination with dog faeces. Prevalence of PA was slightly higher in rural (40.06%) than in urban (33.44%) locations. Distribution of groups of PA (cestodes, nematodes, and protozoa) showed statistical differences between both habitats. Prevalence of cestodes (18.18%) and protozoa (11.86%) was significantly higher in the rural environment than in urban areas and nematodes (29.10%) were more frequent in urban locations. Infection of dogs with Linguatula serrata and Cryptosporidium sp. was demonstrated for the first time in Neuquén. Rural dogs of the study area are under hydatic disease control program, which includes treatment with praziquantel every 6 weeks; thus, the finding of high level of cestode infection in these areas is of great relevance. The epidemiology of zoonotic parasitic infections in urban and rural dogs showed different patterns and, in consequence, different control measurements should be applied in each location.     

Short‐scale distribution of copper fractions in a vineyard acid soil

We studied short‐scale variation in the total concentration of copper and its fractions in a soil vineyard. Soil samples were collected at a depth of 0–20 cm between plant rows (1), between individual plants (2) and at their base (3) in a vine‐grown plot in NW Spain. The mean total content in Cu (Cu_t) in the soil was found to be 97 mg kg⁻¹ and that of potentially available Cu (Cu_EDTA) 34 mg kg⁻¹. Copper bound to organic matter (Cu_OM) and to non‐crystalline inorganic soil components (Cu_IA) were the dominant fractions and accounted for 34% of total copper each. The contents in exchangeable (Cu_e), pyrophosphate‐extractable (Cu_p), oxalic/oxalate‐extractable (Cu_o) and total copper (Cu_t) exhibited statistically significant correlations with pH, sum of base cations (S), cation‐exchange capacity (CEC) and exchangeable calcium (Ca_e). Both total and fractional copper contents were higher in plant rows than between them, particularly in the centre of the plot. Also, Cu_OM and Cu_IA were higher in planting rows than between rows. These copper results may have been influenced by the vine‐growing practices of the area and also by the distribution of plants and their pruning. This variability pattern for Cu distribution is crucial with a view to minimising potential adverse effects of fungicides and optimising any reclamation treatments needed. Copyright © 2007 John Wiley & Sons, Ltd.     

Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere

The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.     

Assay performance during validation of freezing channel catfish Ictalurus punctatus (Rafinesque) infected with a Gram‐negative bacterium

Recovery of bacteria from infected fish during population sampling can be affected by factors including the type of assay, method of specimen preservation and concentration of bacteria present. Consequently, before use in field sampling, methods should be validated. The three objectives of this study were, first, to determine whether a channel catfish Ictalurus punctatus (Rafinesque) fingerling classified as positive for Gram‐negative Edwardsiella ictaluri infection according to bacterial culture before freezing was also classified as positive after freezing, second, to determine how direct culture from the kidney (DIRECT), culture of homogenate (HOMOG) and standard PCR (PCR) agree with bacterial culture in terms of classifying fish as positive or negative and third, to estimate diagnostic sensitivity (dSe) and diagnostic specificity (dSp) for DIRECT, HOMOG and PCR. In fresh and frozen fish, as bacterial concentration decreased, the ability of each assay to detect positive fish also decreased, especially when there were <10⁴ colony‐forming units per gram (CFU g^?1) tissue. HOMOG proved to be the most reliable at correctly classifying catfish, whether they were subclinically or clinically infected. PCR assay was the least reliable. Overall, values for this study population for dSe were 0.66, 0.92 and 0.43, and for dSp were 0.86, 0.91 and 0.95, for DIRECT, HOMOG and PCR respectively.     

Replacement of fishmeal by vegetable meal mix in the diets of Litopenaeus vannamei reared in low‐salinity biofloc system: effect on digestive enzymatic activity

Biofloc (consortium of diverse microorganisms associated to suspending substrates) was developed from waste of shrimp Litopenaeus vannamei postlarvae culture under low salinity (5 g L^?1) to provide an additional nutritious biomass and reduce fishmeal inclusion in feeds in a 28‐day indoor shrimp nursery trial conducted in 15 experimental containers (250 L stocked at 600 org m^?3). Four experimental diets (isoproteic and isocaloric) containing different percentage of fishmeal: 0%, 10%, 20% and 30% substituted by vegetable meal mix (corn, sorghum and wheat) were formulated and elaborated. A control treatment consisted of a commercial feed. The main water quality parameters were monitored, and no significant differences were found among treatments. The growth and survival were similar among treatments. In general, digestive enzymatic activities showed differences being greater in the biofloc system compared with clear water. It was concluded that low‐salinity shrimp nursery could be successfully developed with minimum inclusion of fishmeal in feeds, without significant effect on production response. The adjustment of C : N ratio allowed the increase of microbial biomass in the bioflocs, which contributed to maintain good water quality, provide live food and enhance digestive enzymatic activity of cultured organisms.     

A sensitive dot immunobinding assay for serodiagnosis of African swine fever virus with application in field conditions.

The present work describes a simple dot immunobinding assay (DIA) for African swine fever virus (ASFV) antibody detection that can be used under field conditions. The assay uses nitrocellulose strips dotted with a cytoplasmic soluble antigen (CS-P) of ASFV. The nitrocellulose strips are adhered to a plastic handle. The test serum samples react with the CS-P, and antibodies are detected using a protein A-peroxidase conjugate. Both incubations are carried out at 20 C. The efficacy of the DIA as a screening test for ASFV was compared to an enzyme-linked immunosorbent assay (ELISA) and an immunoblotting (IB) test using 343 sera collected from natural African swine fever epizootics and from inapparent ASFV carriers. The DIA had comparable sensitivity to both reference techniques, and all samples positive in the ELISA and IB test were also positive in the DIA. False-positive reactions were not detected when whole blood or poorly preserved serum samples were tested by DIA. Some poorly preserved sera that were positive initially by the ELISA were no longer ELISA positive in a later run, although they were positive in IB and DIA. These positive DIA and IB test results could be caused by the differences in antibody epitope binding.     

A phalangeal fusion defect and osteochondrosis dissecans with subluxation of the distal interphalangeal joints in a foal

A fusion defect of the proximal and middle phalanges of both hindlimbs, osteochondrosis dissecans of the distal interphalangeal joints of the forelimbs, and subluxation of all 4 distal interphalangeal joints occurred in a Standardbred filly. Lameness was the first abnormality noted and was observed at one week of age in the left forelimb and progressed until all 4 limbs were affected by 5 weeks of age. On radiographs of both forelimbs, the distal interphalangeal joints were subluxated with irregularity and lucency of subchondral bone. On radiographs of the distal hindlimbs, there was a subluxation of both distal interphalangeal joints and loss of the proximal interphalangeal joint spaces with fusion of the proximal and middle phalanges. The foal was euthanised. On necropsy, there were focal areas of erosion of articular cartilage in the distal interphalangeal joint of both forelimbs. The proximal and middle phalanges of both hindlimbs were fused. Histopathological examination of the distal interphalangeal joint of the right foreleg showed loss of articular cartilage and degenerative changes in the exposed subchondral bone.