Bioprospection of Microalgae and Cyanobacteria as Biocontrol Agents Against Vibrio campbellii and Their Use in White Shrimp Litopenaeus vannamei Culture

Vibrio spp. are the most common and harmful shrimp pathogenic bacteria; however, microalgae and cyanobacteria have the ability to produce antimicrobial substances against these species. In this study, the organic and aqueous extracts of 28 species of marine microalgae and cyanobacteria were screened against Vibrio campbellii M1. Two of these phytoplankton species with antibacterial activity in aqueous extracts (Dunaliella tertiolecta and Skeletonema costatum) and nontoxic to brine shrimp Artemia franciscana nauplii were used to evaluate their anti‐Vibrio effect when used as green‐water cultures in Vibrio‐challenged white shrimp Litopenaeus vannamei cultures. No differences in mortality of juvenile L. vannamei were observed between treatments tested, suggesting that the pathogenicity of V. campbellii could be related to the growth stage of shrimp. The proximal composition of D. tertiolecta and S. costatum was in the recommended range for penaeid shrimp nutrition, allowing shrimp supplemented with these microalgae to have significantly greater total length and weight than control shrimp. Shrimp supplemented with S. costatum presented the highest values of organic mass (11.48 mg/organism) and growth rate (0.31 mg/d) in comparison to D. tertiolecta. These results indicate that microalgae are not only capable of producing antibacterial compounds against Vibrio but can also help shrimp nutrition.     

Is there a link between pollutant exposure and emerging infectious disease?

A scoping literature review found evidence supporting the hypothesis that a population’s pollution status could help refine classification of emerging infectious disease (EID) hotspots. Systematic literature reviews and studies designed to specifically test the predictive value of pollutant status on EID risk are recommended.     

Detection efficiency and habitat use to inform inventory and monitoring efforts: juvenile coho salmon in the Knik River basin,Alaska

Imperfect detection associated with sampling gear presents challenges for wildlife inventory and monitoring efforts. We examined occupancy dynamics and habitat use of juvenile coho salmon, Oncorhynchus kisutch, in shallow lake environments over a summer and early fall season in the Knik River area of south central Alaska using models which control for and estimate sampling gear detection efficiency. In addition, we present statements for the probability that observed absences at a survey site or from a survey area (a collection of sites) are true absences given some amount of sampling effort and analysts' beliefs about site occupancy and sampling gear detection efficiency which can be used to guide inventory and monitoring efforts for juvenile salmon or other wildlife and plant species. Occupancy modelling results demonstrate that minnow traps were effective at sampling juvenile coho in shallow lake environments, with a mean probability of detection across the study period of 0.68 (i.e., probability of detecting the presence of juvenile coho given that they are present at a trap site; SE = 0.03). Juvenile coho salmon migrated into shallow water lakes in late summer and early fall, presumably to seek out overwinter habitat. N‐mixture modelling examination of habitat use demonstrated that once in shallow lake environments, juvenile coho were widely distributed across a range of microhabitats, with some evidence for preference for shallower depths and warmer water temperatures.     

Diagnosis of Taxus (yew) poisoning in a horse.

A 2-year-old bay Thoroughbred colt was found dead overnight in its stall without a known history of any illness, existing disease, or toxicant exposure. No information on the clinical signs before this animal's death was reported. A full necropsy was performed the next morning and revealed a mild to moderate degree of endocardial hemorrhages in both ventricles. Microscopic examination of the heart showed an acute mild multifocal necrosis of papillary muscles and ventricles. The stomach content contained approximately 2% Taxus alkaloids as determined by gas chromatography/mass spectrometry. In the past, diagnosis of Taxus poisoning has been mainly based on history of exposure and the presence of plant parts in the gastrointestinal tract. Pathological lesions associated with Taxus poisoning have not been published for horses. Therefore, this is the first report of cardiac lesions in a horse after lethal exposure to Taxus. On the basis of these findings, it is suggested that Taxus exposure needs to be considered in the differential diagnosis of horses that die suddenly or have cardiac lesions suggestive of Taxus exposure, even if intact plant parts are not identified in the stomach by the naked eye.     

Effects of abamectin on intracellular potassium ion activity and membrane potential in dipteran skeletal muscle

The effects of abamectin (AVMB₁) on intracellular potassium ion activity (aK_i) and resting membrane potential (E_m) of the skeletal muscle cells of final instar larvae of Phormia terraenovae (Diptera) were investigated using K⁺-selective micro-electrodes. Bathing the preparation in 10^? M AVMB₁(+ 1 ml litre^?1 dimethylsulfoxide) for 60 min caused a significant (31%) decrease in aK_i, whilst E_m depolarized on average by 19 mV (nearly 50% of the original control value). The difference E_K-E_m increased by 9 mV, although E_K (potassium equilibrium potential) remained more negative than E_m. These results could be due to a cationic effect of AVMB₁ possibly involving an increase in K⁺ and Na⁺ conductances of the muscle plasma membrane.     

Enzymeimmunoassay of oestrone sulphate concentrations in faeces for non-invasive pregnancy determination in mares

AIM: To determine the suitability of measuring faecal oestrone sulphate (OS) by enzymeimmunoassay as a means of determining pregnancy status in mares bred under New Zealand conditions. METHODS: An antibody-coated microtitre plate-based enzymeimmunoassay was used to determine the concentration of OS in faecal and plasma samples obtained from pregnant and non-pregnant mares. RESULTS: In non-pregnant mares, the mean faecal OS concentration was 34 ng/g, and the value three standard deviations above this was 80 ng/g. None of 427 faecal samples collected from 116 non-pregnant mares over a l-year period had an OS concentration >80 ng/g. Only five samples from three mares had an OS concentration >65 ng/g, the value two standard deviations above the mean non-pregnant value. Analysis of faecal OS concentrations in 532 faecal samples collected from 39 pregnant mares showed that as pregnancy progressed, an increasing proportion of faecal samples had OS concentrations >80 ng/g. None of the mares 150 days or more pregnant had faecal OS concentrations <50 ng/g, and 204/220 samples obtained from these mares had faecal OS concentrations >80 ng/g. Following foaling or foetal death, elevated faecal OS concentrations returned quickly to non-pregnant levels. The mean +/- s.e.m. plasma level of OS in five mares bled daily throughout one oestrous cycle was 1.7 +/- 0.2 ng/ml. Sixty-eight blood samples from pregnant mares bled up to five times between 92 days after mating and foaling all had plasma OS concentrations >30 ng/ml, with 64/68 being >50 ng/ml. CONCLUSIONS: This study shows that measuring faecal OS concentrations by enzymeimmunoassay offers a convenient, accurate, non-invasive means of determining pregnancy status in mares from 150 days after mating onwards. Mares with faecal OS concentrations <50 ng/g can be considered not pregnant, while mares with faecal OS concentrations >80 ng/g can be considered pregnant. Those few mares returning a faecal OS concentration between 50 and 80 ng/g should be retested to obtain a conclusive result. Measuring plasma OS concentrations allows pregnancy status to be determined earlier (from 100 days after mating). Moreover, the discrimination between non-pregnant and pregnant levels is greater for OS in plasma than in faeces. CLINICAL RELEVANCE: Measurement of OS concentrations in faeces provides an alternative and non-invasive means of determining pregnancy status in mares from 150 days after mating.     

Nonendoscopic Antegrade Percutaneous Gastrostomy: The Effect of Preplacement Gastric Insufflation on Tube Position and Intra-Abdominal Anatomy

Nonendoscopic tube gastrostomy was performed on 41 anesthetized dogs using the technique of Fulton and Dennis with or without gastric insufflation prior to tube placement. Immediately after tube placement, dogs were euthanized and postmortem examinations performed. When gastric insufflation was not performed (group I), gastrostomy tubes penetrated the visceral surface of the stomach in 25% of dogs. The deep leaf of the omentum was interposed between stomach and body wall in the majority of these dogs, exposing other intra-abdominal organs to potential injury. Additionally, displacement and tethering of the spleen cranial to the gastrostomy site were observed in 33% of dogs in group I. Similar results were obtained when preplacement gastric insufflation was performed after the orogastric tube was inserted sufficiently far to displace the stomach laterally against the body wall (group II). In contrast, consistent positioning of gastrostomy tubes through the parietal surface of the stomach was achieved when the stomach was insufflated prior to lateralizing the left abdominal wall with the gastric end of the orogastric tube (group III). It was concluded that the blind percutaneous gastrostomy technique is made safer by insufflating the stomach immediately prior to pushing the gastric wall laterally into contact with the parietal peritoneum. J Vet Intern Med 1996;10:15–20. Copyright © 1996 by the American College of Veterinary Internal Medicine .