Complex oscillations in the Belousov-Zhabotinsky batch reaction with methylmalonic acid and manganese(ii).

The Belousov-Zhabotinsky (BZ) oscillating chemical reaction involves the oxidation of an organic compound by the bromate ion in the presence of a metal ion catalyst such as cerium(iv), manganese(ii), or ferroin. Simple periodic oscillations are generally obtained for the BZ reaction in a batch (closed) system. However, complex oscillations have been observed for the BZ reaction in batch with malonic acid and either cerium or ferroin ions as the catalyst.

Batch pH Oscillations in the Belousov-Zhabotinsky Reaction.

No single-phase system has been previously reported to give significant pH oscillations in a closed (batch) reactor. We report here sustained pH oscillations in batch for the Belousov-Zhabotinsky reaction using much lower [H] and much higher [BrO] than in traditional studies of this reaction. In fact, pH oscillations were obtained in the presence of only BrO, malonic acid (MA), and Mn.

Characteristics of a new reovirus isolated from epizootic ulcerative syndrome infected snakehead fish.

Epizootic ulcerative syndrome (EUS) has been infecting a wide range of fishes in the South and Southeast Asia for the last 2 decades. One reovirus-like agent (snakehead reovirus, SKRV), isolated from an EUS-infected snakehead fish and investigated in the present study, is the only reovirus so far isolated from an EUS-infected fish. SKRV was characterised by the presence of a double-stranded RNA genome with icosahedral symmetry and double capsid.

Cell culture isolation of piscine neuropathy nodavirus from juvenile sea bass, Dicentrarchus labrax.

A virus causing a vacuolating encephalopathy and retinopathy in juvenile sea bass, Dicentrarchus labrax, was isolated from brain tissue in a fish cell line (SSN-1) derived from striped snakehead, Channa striatus. The isometric, non-enveloped, 30 nm diameter virus particles were resistant to pH 2-9 and heating at 56 degrees C for 30 min. Infectious particles had a buoyant density of approximately 1.

Complete nucleotide sequence and transcriptional analysis of snakehead fish retrovirus.

The complete genome of the snakehead fish retrovirus has been cloned and sequenced, and its transcriptional profile in cell culture has been determined. The 11.2-kb provirus displays a complex expression pattern capable of encoding accessory proteins and is unique in the predicted location of the env initiation codon and signal peptide upstream of gag and the common splice donor site.

Viruses associated with the epizootic ulcerative syndrome (EUS) of fish in South-East Asia.

A number of birnaviruses, rhabdoviruses and a reovirus have been isolated from occasional fish affected with the epizootic ulcerative syndrome (EUS) in the past decade. The heterogeneous nature of these isolates, together with a low and inconsistent level of recovery from diseases specimens, suggests that these viruses may only represent adventitious infections unrelated to outbreaks of EUS. Furthermore, experimental induction of the condition by direct exposure to cell culture isolated viruses has not been achieved.

Spontaneously productive C-type retrovirus infection of fish cell lines.

The spontaneous production and release of morphologically typical, 85 to 90 nm diameter C-type retrovirus particles from four cell lines derived from three species of warmwater fish have been identified. Virus pellets from cell culture supernatants showed high levels of Mn(2+)-dependent reverse transcriptase activity at 24 degrees C. Peak enzyme activity was associated with a 1 x 16 g/ml sucrose gradient fraction.

Bacterial diseases of marine fish.

The principal bacterial diseases found among wild and cultured marine fish are reviewed. The bacterial agents discussed include the Gram-negative pathogens in the Vibrio, Aeromonas, Pasteurella and Edwardsiella genera, Renibacterium salmoninarum and the myxobacteria, streptococci, mycobacteria, nocardias and anaerobic organisms which have been associated with fish diseases. Methods for the isolation and identification of these organisms are described.

The fatty acid compositions of established fish cell lines after long-term culture in mammalian sera.

The effect of long-term culture of fish cells in mammalian serum on the phospholipid fatty acid composition was investigated. All the cell lines studied had much lower levels of polyunsaturated fatty acids (PUFA) than those found in intact fish tissues. In particular (n-3) PUFA were considerably depleted in the cultured cell lines, leading to very low (n-3)/(n-6) ratios in all the phospholipid classes.

Sterility testing of immunological products: comparative efficacy of media and effect of preservatives.

A comparison was made of the abilities of various culture media to support the growth of a range of micro-organisms commonly recommended as control strains in tests for the sterility of immunological products. The effects of phenol, cresol, formaldehyde and thiomersal on the growth of these organisms were studied. Attention is drawn to some limitations of the current pharmacopoeial test methods.

An inactivated, oil-emulsion vaccine for the prevention of porcine parvovirus-induced reproductive failure.

Pig fetuses inoculated at 45 days gestation with virulent porcine parvovirus (PPV) were harvested 10 days later. Virus was extracted, inactivated with binary ethylenimine and the antigen suspension emulsified with mineral oil adjuvant. One dose of this vaccine, or two doses with a 14 day interval, stimulated high and long lasting serum antibody titres in gilts.

Safety and efficacy of live and inactivated infectious bovine rhinotracheitis vaccines.

Two commercial live virus infectious bovine rhinotracheitis (IBR) vaccines for intranasal administration and an inactivated polyvalent calf pneumonia vaccine were compared for safety and efficacy in calves against experimental IBR infections. All three products were clinically safe for use in young calves; a mild, transient, febrile response was induced by one of the live vaccines. Vaccinal virus was recovered for up to 16 days after vaccination from nasal secretions of all calves given live vaccine.

Practical application of bovine tuberculin PPD in testing cattle in Great Britain.

A national tuberculin testing trial was carried out in 8151 cattle in 132 herds due for normal herd testing and distributed throughout the 11 animal health administrative regions of England, Scotland and Wales. The numbers selected from each region were in approximately equal proportions to the total cattle populations of the regions and comprised a representative sample of the national herd. The standard intradermal comparative tuberculin test using Weybridge avian and human purified protein derivatives (PPD) was carried out on one side of the neck, and Rotterdam bovine PPD (1 X 0 mg per ml) was injected on the opposite side in the usual 'mammalian' site.

Non-parenteral vaccines for veterinary use in the United Kingdom.

The first vaccine specifically formulated for non-parenteral administration was licensed for use in the United Kingdom over 15 years ago. Since that time there has been a dramatic increase in the use of this type of product, particularly within the last five years, and at present no fewer than 46 of the 220 currently licensed vaccines are recommended for administration by the non-parenteral route. The majority (42) of these products are for use in poultry with the remainder being for cattle, pigs and mink (1 vaccine each).

The relation between the rabbit potency test and the response of sheep to sheep clostridial vaccines.

Six commercially available clostridial vaccines comprising one oil-emulsion, two alum-precipitated and three aluminum hydroxide adjuvanted preparations, each containing between two and seven antigenic components, were administered to groups of 10 rabbits and eight sheep in accordance with manufacturers' recommendations. Serum antitoxic values to Cl welchii beta, Cl welchii epsilon, Cl septicum, Cl oedematins and Cl tetani toxins were determined 14 days after completion of each vaccination course. The overall pattern of mean antitoxic values was found to be similar in sheep and rabbits, a vaccine eliciting a comparatively high antibody titre to any given antigen component in sheep also inducing a comparatively high titre in the corresponding group of rabbits.