Simple, rapid, and inexpensive cleanup method for quantitation of aflatoxins in important agricultural products by HPLC

A chemical cleanup procedure for low-level quantitative determination of aflatoxins in major economically important agricultural commodities using HPLC has been developed. Aflatoxins were extracted from a ground sample with MeOH/H2O (80:20, v/v), and after a cleanup step on a minicolumn packed with Florisil, aflatoxins were quantified by HPLC equipped with a C18 column, a photochemical reactor, and a fluorescence detector. Water/MeOH (63:37, v/v) served as the mobile phase. Recoveries of aflatoxins B1, B2, G1, and G2 from peanuts spiked at 5, 1.7, 5, and 1.7 ng/g were 89.5+/-2.2, 94.7+/-2.5, 90.4+/-1.0, and 98.2+/-1.1, respectively (mean+/-SD, %, n=3). Similar recoveries, precision, and accuracy were achieved for corn, brown and white rice, cottonseed, almonds, Brazil nuts, pistachios, walnuts, and hazelnuts. The quantitation limits for aflatoxins in peanuts were 50 pg/g for aflatoxin B1 and 17 pg/g for aflatoxin B2. The minimal cost of the minicolumn allows for substantial savings compared with available commercial aflatoxin cleanup devices.     

Interaction of antioxidant biobased epicatechin conjugates with biomembrane models

(-)-Epicatechin conjugates with sulfur-containing moieties are strong free radical scavengers with cell-protecting activities, which may be in part modulated by their capacity to bind to biological membranes. We present here a study of the interaction of these conjugates with membrane models such as multilamellar vesicles and a phospholipid-coated silica column (immobilized artificial membrane), monitored by differential scanning calorimetry and high-performance liquid chromatography, respectively. The nonpolyphenolic moiety significantly influenced the membrane behavior of the whole molecules. Bulky and hydrophobic conjugates clearly interacted with the phospholipids and may have a tendency to penetrate into the hydrophobic core of the vesicles. In contrast, the smaller cationic 4beta-(2-aminoethylthio)epicatechin may be located at the outer interface of the lipid membrane. The outcomes from both experimental set-ups were in good agreement. The differences detected in the biological activities of the conjugates may be explained in part by their tendency to penetrate the cell membrane.     

Effect of blood metabolites, body condition and pasture management on milk yield and postpartum intervals in dual-purpose cattle farms in the tropics of the state of Veracruz, Mexico

Research was conducted on typical smallholder farms with dual-purpose cattle (DPC) (Bos indicus x B. taurus) in the coastal north-central area of Veracruz, Mexico. The study was divided into two phases. The aim of the first phase was to investigate the effect of blood metabolities, body condition and pasture management on milk yield and postpartum intervals, in order to investigate if the former are suitable indicators of the reproductive and nutritional status of DPC. One hundred and sixty-five calvings of crossbred cows were recorded from January 1992 to November 1994 on 12 small farms. Milk samples were collected twice a week for progesterone analysis. Blood samples and BCS were taken once a month. However, in Phase II emphasis was placed on the effect of pasture management upon reproductive and productive performance of DPC. Records of four farms were obtained from June 1995 to November 1996. Stocking rates were 0.40, 0.87, 0.35 and 1.5 cows/ha for farms A, B, C and D, respectively. Farms A and C used a slow rotation while B and D used a rapid rotation. In Phase I, the changes in BCS during the last month of pregnancy and first month postpartum did not correlate (p > 0.05) with milk yield or reproductive performance. Blood the metabolite profiles were not consistently related to productive or reproductive variables. The effect of farm and season was significant (p < 0.05) on most of the response variables and low productivity on overstocked farms lead to the conclusion that the low reproductive performance of DPC was linked to poor pasture management. During Phase II, farms A (FA) and D (FD) produce more milk than the others. Days to first service, days open, and calving interval were similar for farms B (FB) and C (FC), highest for Farm A, and lowest for Farm D. The forage availability mean was above the critical range of 6-8 kg of dry matter per 100 kg of liveweight (kg DM/100 kg LW) in all farms (range from 6.1 +/- 5.0 to 21.1 +/- 11.2 kg DM/100 kg LW). Farm D had the highest stocking rate (1.5 cows/ha), a rapid rotation (10 paddocks), a good forage availability (7.1 +/- 3.9 kg DM/100 kg LW) with a good quality for a tropical pasture (11.6 +/- 2.4% crude protein), and an economic energy supplementation. These results suggest this type of management could be more widely employed to improve the productivity of DPC on smallholder farms in the Mexican tropics.     

Assessment of a fisheries legal framework for potential development of an ecosystem approach to fisheries management in large rivers

Most small‐scale fisheries of large floodplain rivers are still managed under conventional top‐down regulations that limit the application of an ecosystem approach to fisheries (EAF) due to inappropriate legal frameworks. Using the Parana–Paraguay River fisheries (Argentina) as an example, this study examines the extent to which existing provincial legislations can be prepared for the adoption of an EAF. An Ecosystem Fishing Legal Approach (EFLA) framework is proposed based on different criteria across an environmental–ecological, fishing, social, economic and institutional template. Policy Component Scores (PCS) and an Integrated Policy Legal Index (IPLI) were applied to assess the degree of compliance by current provincial legislations to EAF implementation. Cluster analysis was used to recognise the potential for articulating a legal framework at a basin scale. The EFLA framework, which provided an accurate picture of how provinces were poorly prepared to adopt an EAF for the Paraguay–Parana fisheries, and represents a suitable tool that can be adapted and extended to other basins around the world.     

Isolation and inhibitory effect of anti-<Emphasis Type="Italic">Vibrio</Emphasis> substances from <Emphasis Type="Italic">Pseudoalteromonas</Emphasis> sp. A1-J11 isolated from the coastal sea water of Kagoshima Bay

ABSTRACT:   Among several marine antagonistic bacteria isolated from the sea water of Kagoshima Bay, Pseudoalteromonas sp. A1-J11 was found to produce anti- Vibrio substances. The anti- Vibrio substances were extracted from the culture supernatant of the strain with chloroform and isolated using reverse-phase (Cosmosil 75C₁₈-OPN) column chromatography followed by high-pressure liquid chromatography (Mightysil RP-18 GP Aqua). Purified substances, designated as AVS-03 a , c and d showed similar ultraviolet absorption spectra with λ_max at 215, 235, 315 and 327 nm in methanol. AVS-03 d , the major anti- Vibrio substance, was thermostable up to 100°C and pH stable over a pH range higher than 4.0, and also showed strong inhibitory activities, specifically against Vibrio harveyi strains.     

Molecular characteristics of an immobilization antigen gene of the fish-parasitic protozoan Ichthyophthirius multifiliis strain ARS-6

Ichthyophthirius multifiliis (Ich), a ciliated protozoan parasite of fish, expresses surface antigens (i-antigens), which react with host antibodies that render them immobile. The nucleotide sequence of an i-antigen gene of I. multifiliis strain ARS-6 was deduced. The predicted protein of 47 493 Da is comprised of 460 amino acids (aa's) arranged into five imperfect repeats with periodic cysteine residues with the structure: CX₍₁₉₎₂₀CX₂CX₁₆₋₂₇CX₂CX₂₀₍₂₁₎CX₃. The N-terminal aa's typify a signal peptide motif while a stretch of C-terminal aa's resemble a glycosyl–phosphatidyl–inositol (GPI)-anchor addition site. The degree of deduced i-antigen aa sequence identity of strain ARS-6 (GenBank accession # ACH87654 and # ACH95659) with other I. multifiliis i-antigen sequences present in GenBank ranges from 99% to 36% identity with 52 kDa i-antigens of I. multifiliis strain G5 (accession #s AAK94941 and AAK01661 respectively). Immunoblot analysis of i-antigens following exposure of I. multifiliis theronts to catfish anti- I. multifiliis immune serum did not show any appreciable alteration in i-antigen expression. The mechanism that regulates i-antigen expression in I. multifiliis remains a puzzling question.     

Effect of the VP3 gene of chicken anemia virus on canine mammary tumor cells

OBJECTIVE: To investigate the antitumor effect of the chicken anemia virus (CAV) VP3 gene in canine mammary tumor (CMT) cells. SAMPLE POPULATIONS: Established primary canine cell lines that originated from epithelial cells of resected CMTs and nonneoplastic mammary gland epithelial (MGE) cells. PROCEDURES: Expression vectors and lentiviral vectors encoding the VP3 gene from a Taiwan-Ilan isolate of CAV were used to deliver the VP3 gene into CMT cells and nonneoplastic MGE cells. Ectopic gene expression and the pro-apoptotic effect of the VP3 gene on CMT and nonneoplastic MGE cells by either transfection or viral infection were evaluated via immunofluorescence microscopy, western blot analysis, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis. RESULTS: Overexpression of the enhanced green fluorescent protein-VP3 fusion protein was detected predominantly in the nuclei of CMT cells. In contrast, the VP3 protein was localized to the cytoplasm of nonneoplastic MGE cells. Among the fusion protein-expressing CMT cells, most underwent characteristic changes of apoptosis, whereas apoptosis was not detected in fusion protein-expressing, nonneoplastic MGE cells. Induction of apoptosis by VP3 gene overexpression in CMT cells was associated with the caspase-9-, but not the caspase-8-, mediated apoptosis pathway. CONCLUSIONS AND CLINICAL RELEVANCE: These data indicate that the VP3 gene of the CAV induces apoptosis in malignant CMT cells, but not in nonneoplastic canine MGE cells. On the basis of such tumor cell-specific killing, the VP3 gene may be a promising agent for the treatment of malignant mammary gland tumors in dogs.