Identification and characterization of serum complement activity in the American crocodile (Crocodylus acutus)

Incubation of unsensitized sheep red blood cells with serum from the American crocodile (Crocodylus acutus) resulted in a concentration-dependent hemolysis. The hemolytic activity was heat-sensitive, and inhibited by EDTA in a concentration-dependent manner. The EDTA-inhibited SRBC hemolysis could be restored by the addition of excess Ca²⁺ or Mg²⁺, but not Ba²⁺ or Cu²⁺, revealing the specificity of this activity for these two divalent cations. The hemolytic activity of crocodile serum was titer-dependent, with 329 μL producing 50% of maximal SRBC hemolysis. The complement activity was also temperature-dependent, with decreased activity at lower temperatures (5–15 °C) and maximal activity occurred at 30–40 °C. The hemolysis occurred relatively slowly, with near zero activity after 10 min, 40% of activity observed within 15 min of exposure to SRBCs, and maximal activity at 30 min.     

Book review

The Microbiology of Poultry Meat Products, Edited by F. E. Cunningham and N. A. Cox, 1987. ix+359 pp. illustrated. Orlando, Florida, Academic Press. £54.00, $65.00. ISBN 0 12 199880 0.     

Microbial cross-contamination during air chilling of poultry

1. Cross-contamination during air chilling of poultry carcases was investigated using a nalidixic acid-resistant strain of Escherichia coli K12 as a marker organism. 2. Experiments were carried out on 2 types of commercial chiller, with and without the use of water sprays (evaporative cooling), and a pilot-scale chiller in which conditions could be varied as required. 3. In the commercial chillers, the marker was dispersed in all directions from a single inoculated carcase and transmission was increased by the use of chlorinated water sprays. 4. Similar results were obtained with the pilot-scale chiller, where the marker was recovered from 45/54 uninoculated carcases; cross-contamination was not prevented by spraying carcases with water containing 50 mg/l of free available chlorine. 5. Despite the ease of microbial transmission from inoculated carcases, cross-contamination during air chilling is likely to be less than that occurring at earlier stages of poultry processing, when carcases are more heavily contaminated.     

Prospects for 'competitive exclusion' treatment to control salmonellas and other foodborne pathogens in poultry

In newly hatched chicks, the rapid establishment of an adult-type intestinal microflora, via the oral route, produces almost immediate resistance to colonization by any food poisoning salmonellas that gain access to the rearing environment. Exploitation of the 'competitive exclusion' (CE) effect is now an accepted part of the overall strategy by which poultry-associated salmonellas are being controlled in some countries.This review covers practical aspects of CE treatment and factors affecting efficacy in both laboratory-scale trials and field studies. It also considers possible applications in preventing colonization of poultry with Escherichia coli O157 and Campylobacter jejuni. For the latter, evidence suggests that the 'protective' organisms are different from those involved in salmonella control.     

Effect of storage on meat quality in uneviscerated turkeys held at 4°C

1. By comparison with birds examined 1 d after slaughter, those held uneviscerated at 4 °C for a further 7 d showed a statistically‐significant difference in flavour (P < 0·01) when examined by a trained taste panel and the difference increased progressively up to 24 d when the experiment ended.

2. Changes in the composition of the microflora in the small intestine and caecum were investigated because of previous evidence that meat flavour development may be influenced by the metabolic activities of intestinal organisms. The only marked effect of storage was a decline in the numbers of lactose‐positive coliform bacteria in the small intestine; there was no clear evidence of any microbial growth in the gut.

3. Although birds examined at day 8 by a sensory panel or by means of a tenderometer were slightly more tender than those tested at day 1, the differences were not statistically significant; nor were there any significant changes in texture during the remainder of the storage period. Possible reasons for the lack of any marked tenderisation are discussed.

     

Non-target effects of dimethoate and acephate against Eusieus tularensis Congdon and Aphytis melinus DeBach on lemons in California

Understanding the non-target effects on pesticides used in crop production systems is essential for the development of IPM programmes in those systems. Two organophosphates for control of citrus thrips in citrus were compared at commercial field rates in a lemon orchard for their effect against a predacious mite and a parasitic wasp, both of which have a significant role in coastal lemon IPM. Dimethoate and acephate greatly reduced populations of both beneficial insects, holding them to below detectable levels for 8 weeks post-treatment. Moreover, citrus red mite, a secondary pest, developed beyond the economic treatment threshold in both the dimethoate and acephate plots 10 weeks and 4 weeks post-treatment, respectively. In addition to predatory mite mortality, hormoligosis is suspected in both instances, and especially with acephate, of causing this secondary pest problem.