The activities of amylase and a trypsin‐like protease in the gut contents of germ‐free and conventional chickens

1. Proteolytic and amylase activities were assayed in the gut contents of germ‐free and conventional chickens aged 3 and 14 d.

2. The tendency was for the proteolytic activity to be increased and the amylase activity to be decreased in conventional chicks. These differences were statistically significant in the caecum.

3. All of the additional proteolytic activity detectable in the caecum of conventional chicks was inhibited by soyabean trypsin inhibitor. However, the increased activity was not detectable in the small intestine and was, therefore, not due to pancreatic trypsin.

4. Attempts to demonstrate in vitro bacterial production of a trypsin‐like enzyme were unsuccessful.     

Prevalence, clinical features, and causes of epistaxis in dogs: 176 cases (1996-2001)

OBJECTIVE: To determine prevalence, clinical features, and causes of epistaxis in dogs. DESIGN: Retrospective case series. ANIMALS: 176 dogs with epistaxis. PROCEDURES: Medical records were reviewed for information related to signalment, clinical features, diagnosis, and outcome. RESULTS: 132 (75%) dogs were initially examined by the hospital's emergency service; prevalence of epistaxis was 0.3%. Dogs with epistaxis were more likely to be old (> or = 6 years), male, and large (> or = 26 kg [58.5 lb]) than were dogs in a reference population. In 109 (62%) dogs with epistaxis, an underlying cause was identified; 115 underlying disorders were identified, with 90 classified as local and 25 classified as systemic. Local causes of epistaxis included nasal neoplasia (n = 35), trauma (33), idiopathic rhinitis (20), and periapical abscess (2). Systemic causes included thrombocytopenia (12), thrombocytopathia (7), coagulopathy (3), hypertension (2), and vasculitis (1). Dogs with local causes were more likely to have unilateral than bilateral epistaxis, but 11 of 21 (52%) dogs with systemic disorders also had unilateral epistaxis. Dogs with systemic disorders were more likely to have clinical signs of systemic disease. Duration of epistaxis (acute vs chronic), severity, and duration of hospitalization were similar for dogs with local versus systemic disorders. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that epistaxis was a common disorder in dogs and frequently regarded as an emergency. Local causes of epistaxis were predominant, but clinical features traditionally thought to be helpful in distinguishing local versus systemic causes could not be reliably used for this purpose.     

Histology and histochemistry of the major salivary glands in the southern white-breasted hedgehog (Erinaceus concolor)

This study aimed to investigate the major salivary glands in the southern white-breasted hedgehog (Erinaceus concolor) histologically and histochemically. Five adult males were included in this study. The results showed that anatomically the shape of the parotid, submandibular and sublingual glands of the Erinaceus concolor was respectively almost pear, elliptical to pyramidal and oval. Histologically, the parotid gland had serous acini and secretory cells showed negative reaction to alcian blue (AB) (pH = 2.5) and negative response to aldehyde fuchsin (AF), methylene blue (MB) and PAS stains. The submandibular gland was a mixed gland of mucous and serous acini. The mucous acini were strongly positive for PAS, AB, MB and AF. However, serous acini were week for PAS and negative against AB, MB and AF stains. The sublingual gland was purely composed of mucous acini. The mucous acini of the sublingual gland were strongly positives for PAS, AB and MB methods. While their reaction to the AF staining was negative. In conclusion, the histological and histochemical observations of the major salivary glands of the southern white-breasted hedgehog (E. concolor) indicated that these glands shown similarities and some special different histochemical features as compared to other mammalian species.     

High-throughput screening reveals small molecule modulators inhibitory to Acidovorax citrulli

Acidovorax citrulli is a seed-transmitted gram-negative bacterium that can cause substantial economic yield loss in watermelon and melon production worldwide. Four small-molecule libraries containing 4,952 compounds were selected for high-throughput screening against A. citrulli wild-type strain Xu3-14 by evaluation of growth inhibition. One hundred and twenty-seven molecules (2.5% hit rate) were identified as bactericidal or bacteriostatic against A. citrulli at 100 μM. Secondary screens indicated that 27 candidate compounds were more effective against A. citrulli Group II strains than Group I strains (classified using repetitive element PCR). Several compounds were inhibitory to other pathogenic bacteria, including Clavibacter michiganensis subsp. michiganensis and Xanthomonas campestris pv. campestris, but did not affect the growth of plant beneficial bacteria Pseudomonas fluorescens and Bacillus subtilis. More than half of the compounds did not inhibit germination of Arabidopsis or watermelon seeds. The effect of small molecules on A. citrulli seed-to-seedling transmission was evaluated by applying each compound to inoculated watermelon seeds and assessing seedling infection. Nine compounds were chosen for further investigation based on their reduction of percentage seedling infection and compiling scores on their specificity, sensitivity, and phytotoxicity obtained in the secondary screens. The five best compounds were selected (thiamphenicol, nadifloxacin, pipemidic acid, ciclopirox, and zinc pyrithione) for greenhouse tests and were found to effectively reduce the seed-to-seedling transmission of A. citrulli in both artificially and naturally infested seeds. These top five compounds provide a basis for future development of an A. citrulli-specific bactericide.     

Safety and efficacy of emamectin benzoate administered in-feed to Atlantic salmon, Salmo salar L., smolts in freshwater, as a preventative treatment against infestations of sea lice, Lepeophtheirus salmonis (Krøyer)

The safety and efficacy of emamectin benzoate, administered in-feed to Atlantic salmon smolts, Salmo salar L., held in freshwater, was evaluated as a preventative treatment against sea lice, Lepeophtheirus salmonis, following transfer of fish to seawater.

In the safety study, salmon smolts held in freshwater were fed with diets containing emamectin benzoate at nominal doses of 0 (control), 50 (recommended dose) and 250 (5× recommended dose) μg kg⁻¹ fish day⁻¹ for 7 days (days 0–6). Actual dose rates, based on measured concentrations of emamectin benzoate in feed, differences in fish weight, and feed consumed, were 0, 54, and 272 μg kg⁻¹ day⁻¹, respectively. On day 9, fish were transferred to seawater and observed for 14 days. No differences in feeding response, coordination, behaviour, gross and histological appearance were observed between control fish and those that received 54 μg kg⁻¹ day⁻¹. Among smolts that received 272 μg kg⁻¹ day⁻¹, approximately 50% exhibited darker coloration, and one fish (1%) exhibited uncoordinated swimming behaviour. No pathognomonic signs of emamectin benzoate toxicity were identified.

In the efficacy study, smolts held in freshwater were fed an unmedicated ration (control group) or emamectin benzoate at 50 μg kg⁻¹ day⁻¹ (treated group) for 7 days (days 0–6). On day 9, fish were re-distributed to eight seawater tanks, each holding 30 control and 30 treated fish. On days 28, 56, 77 and 109, respectively, control and treated fish in two tanks were challenged with L. salmonis copepodites. When lice in each group reached chalimus stage IV, fish were sampled and the numbers of lice were recorded. Fish challenged at day 109 were sampled for the second time when lice were at the adult stage. Efficacy was calculated as the reduction in the mean number of lice on treated fish relative to the mean on control fish. Treatment with emamectin benzoate resulted in an efficacy of 85.0–99.8% in fish challenged at days 28–77, from the start of treatment, and lice counts were significantly lower (P<0.001) on treated fish than on controls. When fish challenged at day 109 were sampled at day 128, efficacy was 44.3%, but survival of chalimus to adult lice on treated fish was lower, and at day 159, efficacy had increased to 73%. These results demonstrate that treatment of salmon smolts with emamectin benzoate in freshwater was well tolerated and highly effective in preventing sea lice infestation following transfer of fish to seawater.     

Ultrastructural morphogenesis of salmonid alphavirus 1

Studies on the ultrastructural morphogenesis of viruses give an insight into how the host cell mechanisms are utilized for new virion synthesis. A time course examining salmonid alphavirus 1 (SAV 1) assembly was performed by culturing the virus on Chinook salmon embryo cells (CHSE‐214). Different stages of viral replication were observed under electron microscopy. Virus‐like particles were observed inside membrane‐bound vesicles as early as 1 h following contact of the virus with the cells. Membrane‐dependent replication complexes were observed in the cytoplasm of the cells, with spherules found at the periphery of late endosome‐like vacuoles. The use of intracellular membranes for RNA replication is similar to other positive‐sense single‐stranded RNA (+ssRNA) viruses. The number of Golgi apparatus and associated vacuoles characterized by ‘fuzzy’‐coated membranes was greater in virus‐infected cells. The mature enveloped virions started to bud out from the cells at approximately 24 h post‐infection. These observations suggest that the pathway used by SAV 1 for the generation of new virus particles in vitro is comparable to viral replication observed with mammalian alphaviruses but with some interesting differences.