Determining the bioavailability of contaminants and assessing the quality of sediments

Background, Aims and Scope  Our study determined the role of light, aeration, grain size, amount of sediments and of water, density of animals and presence of additional food on the movement of Ilyanassa obsoleta. Spiked relative to reference sediments were also tested for avoidance or preference by the mud snails. Our goal was to develop exposure conditions to be used in future assessment studies of the environmental quality of sediments inhabited by mud snails. The behavioural response of the snails towards different concentrations of contaminated Halifax Harbour sediments placed in one half of a tank relative to reference sediments in the other half is examined in Part 2 and a chemical link investigated. Methods  Animals were exposed in 7 L aquaria at 12°C to their native sediments placed in one or two halves of a tank and the effect due to the presence of a light source, air bubbles, sediment grain size, added algae examined relative to the snails’ behaviour. Preference or avoidance of one half of a tank relative to the second half, the immersed or dry glass surface represented the various media to be chosen by snails. After choosing the optimum set up, exposures were performed in triplicate, under slightly differing initial placement of the snails to compare means and variability in the results. Three specific biogenic chemicals, cholesterol, coprostanol and a fatty acid methyl ester (FAME) were spiked at 0.002, 0.01, 0.05, 0.25 and 1.2 mg/g, dry weight of sediment. A hexane, dichloromethane and methanol extract of harbour sediment were also spiked in reference sediments. In all cases, the location of the snails was recorded over a period extending up to 96 hrs. Results  Twenty snails exposed during a 72 hrs period in commercial 7 L tanks containing 50 g of sediments (wet weight) in the bottom half of a tank filled half way with seawater represented the chosen conditions to test the avoidance/preference behaviour of snails for part of a tank. The presence of additional food on sediments attracted snails within 24 hrs of exposure. Discussion  A general lack of preference was indicated in exposures to three biologically derived compounds spiked in reference sediments, i.e. a C-18 FAME, cholesterol and coprostanol. The repelling properties of a harbour sediment extract pointed to a role for non polar chemicals. Conclusions  It is proposed that behaviour reflects a balance between the repelling effects of contaminants and the attractive value of food. The present study provides a robust green assessment tool that is easy to set up to assess the quality of sediments. Recommendations and Perspectives  The interpretation of field observations regarding the abundance of animals during environmental assessments must consider both nutritional and toxicological causes. Additional laboratory exposures are needed to determine which chemicals play a role in the field.     

The incidence, cost and factors associated with foot lameness in dairy cattle in south-western Victoria

A survey of 73 dairy farms in south-western Victoria was conducted to assess the cost and mean herd incidence of foot lameness for the period from calving to the end of November, 1985, and to identify the herd, management and environmental factors associated with foot lameness. The mean herd size was 125 cows (range 82 to 220). Lameness occurred in 64 (88%) herds, and the mean herd incidence was 7.0% (range 0.0 to 30.9%). The main clinical signs associated with lameness were the presence of overworn and/or bruised soles, or stones lodged in the interdigital cleft. Factors associated with lameness were: property and herd size, age of cow, bail feeding, voluntary entry into the bails, and features of the farm track including its length, the presence of steep slopes, the type of surface material, presence and treatment of broken sections and maintenance including rolling history. The association of these factors with specific clinical signs was examined. The mean cost was estimated to be $42.90 per lame cow due to loss of production, treatment, the culling or death of lame cows, and extra man hours spent managing lame cows. It was concluded that the site, construction, maintenance and use of the farm track were of major importance to the incidence of lameness in herds in this area and recommendations for reducing lameness are made.     

Early Development and Putative Primordial Germ Cells Characterization in Dogs

Previously, three distinct populations of putative primordial germ cells (PGCs), namely gonocytes, intermediate cells and pre‐spermatogonia, have been described in the human foetal testis. According to our knowledge, these PGCs have not been studied in any other species. The aim of our study was to identify similar PGC populations in canine embryos. First, we develop a protocol for canine embryo isolation. Following our protocol, 15 canine embryos at 21–25 days of pregnancy were isolated by ovaryhysterectomy surgery. Our data indicate that dramatic changes occur in canine embryo development and PGCs specification between 21 to 25 days of gestation. At that moment, only two PGC populations with distinct morphology can be identified by histological analyses. Cell population 1 presented round nuclei with prominent nucleolus and a high nuclear to cytoplasm ratio, showing gonocyte morphology. Cell population 2 was often localized at the periphery of the testicular cords and presented typical features of PGC. Both germ cell populations were positively immunostained with anti‐human OCT‐4 antibody. However, at day 25, all cells of population 1 reacted positively with OCT‐4, whereas in population 2, fewer cells were positive for this marker. These two PGCs populations present morphological features similar to gonocytes and intermediate cells from human foetal testis. It is expected that a population of pre‐spermatogonia would be observed at later stages of canine foetus development. We also showed that anti‐human OCT‐4 antibody can be useful to identify canine PGC in vivo.     

Canine mammary mixed tumours: immunohistochemical expressions of EGFR and HER‐2

Background Benign mixed tumours (BMTs) are frequently found in the mammary glands of female dogs, but the factors determining malignant transformation in these tumours are unknown. Objective To evaluate the expression of the oncoproteins, human epidermal growth factor receptor 2 (HER‐2) and epidermal growth factor receptor (EGFR), in 46 carcinomas in BMTs (CBMTs) and to verify their possible association with the malignancy of the tumours. Methods Immunohistochemical expression was analysed in benign and malignant components separately, and then compared with 74 cases of BMTs. Results Among the CBMTs, positivity for HER‐2 was found in the benign histological component of 4.3% (2/46), in the malignant epithelial non‐invasive component of 14.8% (4/27) and in the malignant invasive epithelial component of 13.6% (6/44) of cases. Two of the 24 (8.3%) BMTs were positive for HER‐2. There was no relationship between HER‐2 and the tumour components. There was no significant difference between BMTs and CBMTs. Positivity for EGFR was found in the benign component of 17.4% (8/46) of the CBMTs, in the malignant epithelial non‐invasive component of 40.7% (11/27%) and in the invasive epithelial malignant component of 45.4% (20/44). EGFR positivity was significantly associated with the invasive component of CBMTs. Conclusion EGFR may contribute to malignant epithelial transformation of BMTs. In contrast, HER‐2 overexpression may not be associated with the acquisition of a malignant epithelial phenotype.     

Large first hyperpolarizabilities in push-pull polyenes by tuning of the bond length alternation and aromaticity

Conjugated organic compounds with 3-phenyl-5-isoxazolone or N,N'-diethylthiobarbituric acid acceptors have large first molecular hyperpolarizabilities (beta) in comparison with compounds with 4-nitrophenyl acceptors. For example, julolidinyl-(CH=CH)(3)-CH=N,N'- diethylthiobarbituric acid, which has 12 atoms between the donor and acceptor, has a beta(0) of 911 x 10(-30) electrostatic units, whereas (CH(3))(2)NC(6)H(4),-(CH=CH)(4)-C(6)H(4)NO(2), with 16 atoms between its donor and acceptor, has a beta(0) of 133 x 10(-30) electrostatic units. The design strategies demonstrated here have resulted in chromophores that when incorporated into poled-polymer electrooptic modulators exhibited significant enhancements in electrooptic coefficients relative to polymers containing the commonly used dye Disperse Red-1. Poled polymer devices based on these or related chromophores may ultimately lead to high-speed electrooptic switching elements with low drive-power requirements, suitable for telecommunications applications.     

Attitudes of farm consultants in the South Island of New Zealand towards the role of veterinarians in farm businesses

AIMS: To assess the attitude of dairy farm consultants to the role of veterinarians on dairy farms and whether they viewed veterinary advice as impartial, free from commercial bias and central to farm productivity and profitability.

METHODS: A telephone survey was commissioned in September 2014 of 36 full-time farm consultants in the Canterbury and Otago region of New Zealand using a pre-prepared questionnaire to explore their attitudes towards the veterinary profession. Of those approached, 25 completed the survey.

RESULTS: The consultants surveyed agreed or strongly agreed (21/23) that they were the custodians of animal health expenditure on farms, which was seen as an expense to be controlled (19/25 agreed or strongly agreed). This view was held more strongly (9/9 agreed or strongly agreed) by consultants with >5 years’ professional experience, compared to 10/16 consultants with ≤5 years’ experience. Most consultants (24/25) disagreed that they did not respect veterinary advice, but agreed (24/25) that veterinarians almost always had a vested interest in the advice that they gave. The role of veterinarians was seen by respondents to be mainly treatment of sick animals (22/25) and provision of animal health products (24/25), but not in maximising farm profitability (selected by 8/25 respondents). Consultants viewed their own roles as providing advice on the influence of animal health on farm profitability (21/25), nutrition (22/25) and reproduction (20/25). Most respondents (21/25) stated that reducing disease and animal health issues was important, but they (21/25) also identified a reduction in farm animal health expenditure as a measure of success. Only 7/25 consultants felt that they should work in partnership with veterinarians.

CONCLUSIONS: This was a small scale study from one region of New Zealand but it indicates that consultants are ambivalent about the role and value of working more closely with veterinarians, and about the benefit that veterinary intervention may bring to a farm’s profitability.

CLINICAL RELEVANCE: More successful veterinary involvement on dairy farms will follow from a better understanding of how other rural professionals are involved in the farm’s management and in meeting the individual farmer’s goals and motivations.     

Twentieth-Century Sea Surface Temperature Trends

An analysis of historical sea surface temperatures provides evidence for global warming since 1900, in line with land-based analyses of global temperature trends, and also shows that over the same period, the eastern equatorial Pacific cooled and the zonal sea surface temperature gradient strengthened. Recent theoretical studies have predicted such a pattern as a response of the coupled ocean-atmosphere system to an exogenous heating of the tropical atmosphere. This pattern, however, is not reproduced by the complex ocean-atmosphere circulation models currently used to simulate the climatic response to increased greenhouse gases. Its presence is likely to lessen the mean 20th-century global temperature change in model simulations.     

Effects of frequency and duration of outdoor exercise on the prevalence of hock lesions in tied Swiss dairy cows

Injuries around the tarsal joint are common in dairy cows kept in tie stalls. This study investigated the influence of the frequency and duration of outdoor exercise on the prevalence of hock lesions in tied Swiss dairy cows. Over a 1-year period (from January to December), cows on 66 farms were examined a total of six times (once every 2 months) for the number and severity of hock lesions (hairless patches, scabs and open wounds, swellings). The prevalence of scabs and wounds (mean 2.1 scabs per cow and farm, range 0.3-4.1) was negatively associated with the duration of outdoor exercise, and positively associated with its frequency. It was also significantly affected by the time of visit and the type of bedding (straw being better than other materials). With increasing length of the lying area, the prevalence of scabs and wounds decreased. Based on the interpretation of the final model, it is suggested that a minimum of 50h spent outdoors over a 4-week period is necessary to have a marked result on the prevalence of hock lesions.     

Spina bifida with associated malformations of the central nervous system in Dorper-cross sheep

Abstract

CASE HISTORY: In 2008, six lambs within a flock of Dorpercross sheep were born with musculoskeletal and neurological disease. Clinical signs included hindlimb weakness, and urinary incontinence.

CLINICAL FINDINGS: All lambs had focal, inverted areas of alopecic skin over the caudal sacrum, and short, often kinked tails. Four affected lambs were subject to euthanasia, and necropsied. On gross examination, the arches of sacral vertebrae were absent, and spinal nerves and meninges were adherent to the overlying subcutis. Other gross lesions included narrow, elongated skulls, herniation of the occipital lobes into the caudal fossas, hydrocephalus, and syringomyelia. One lamb had coning of the cerebellar vermis, but cerebellar herniation through the foramen magnum was not identified.

DIAGNOSIS: Spina bifida, with associated malformations of the central nervous system.

CLINICAL RELEVANCE: Examination of breeding records suggested either an autosomal recessive or partially penetrant autosomal dominant pattern of inheritance. Because of the associated tail lesions it is proposed that the pathogenesis of this syndrome involves a defect in development of the tail bud (secondary neurulation), that tethering of the spinal cord resulted in the clinical signs, and abnormal pressure of the cerebral spinal fluid resulted in the defects in the skull and brain.