Intraspecific variability in several isolates of Philasterides dicentrarchi (syn. Miamiensis avidus), a scuticociliate parasite of farmed turbot

Research on intraspecific variation in ciliates is scarce, and in scuticociliate parasite of fish, virtually nonexistent. In this study, seven isolates obtained from turbots affected by scuticociliatosis in different parts of the Iberian Peninsula (northwest Spain and southwest Portugal) were morphologically and genetically characterized to investigate the intraspecific divergence in these amphizoic ciliates. The isolates were stained with ammoniacal silver carbonate and examined in an optical microscope; all were found to have the typical morphological characteristics described for Philasterides dicentrarchi (syn. Miamiensis avidus). Sixteen biometric characteristics of the seven isolates were used in a canonical discrimination analysis (CDA) to select a subset of those that best identified each isolate. Discriminant analysis indicated that the OPK3 width, length of the PM2, length of the buccal field, the body width, L:W ratio, the body length, the OPK1 width and the distance between OPK2 and OPK3 were the most important morphological variables for discriminating the isolates. The first three canonical functions accounted for 86% of the total variance. The scatter plots of the first two canonical variables grouped and separated the P. dicentrarchi isolates into five clusters. Flow cytometry analysis of isolates also indicated intraspecific polymorphisms among P. dicentrarchi isolates. Nuclear markers (a 349-bp and a 390-bp fragment of 18S rRNA and β-tubulin genes) and a 398-bp of the mitochondrial cytocrome oxidase subunit I (Cox1) gene were then used to investigate the intraspecific genetic variation in P. dicentrarchi. Haplotype analysis and neighbour-joining phylogenies of nucleotide sequences of seven isolates revealed a high degree of intraspecific genetic variation among the isolates. Analysis of Cox1 and β-tubulin genes revealed six haplotypes (and clusters) in both cases; however, analysis of the 18S rRNA gene revealed only two haplotypes. The results show clear intraspecific variation at morphological and genetic levels in the scuticociliate P. dicentrarchi, and verify the suitability of mitochondrial (Cox1) and nuclear (β-tubulin) genes for detecting intraspecific genetic variation within populations of scuticociliates that infect cultured turbot. The existence of this intraspecific variation must be taken into account in the design of an effective vaccine to control scuticociliatosis.     

Third‐compartment cannulation in alpacas using a polyurethane gastrostomy tube

Objective To develop a simple and effective surgical technique for third‐compartment cannulation in alpacas. Design Prospective study using six adult male alpacas. Methods General anaesthesia was induced and a polyurethane gastrostomy tube was surgically implanted into the distal portion of the third compartment. Results Three of the alpacas retained their cannulas for a 100‐day period; however, three cannulas were dislodged during the study. Two of the three dislodged cannulas were replaced during a second surgical procedure. Cannulas were well tolerated by the alpacas and all animals remained clinically healthy during the study period. Third compartment contents did not leak from the cannulation site. The tubes were manually removed following the completion of the study and the small defect in the body wall quickly healed over in all animals. Conclusion Surgical placement of polyurethane tubes designed for percutaneous endoscopic gastrostomy is a useful method of cannulating the third compartment in camelids. This technique can be used for experimental studies and possibly could be used for nutritional support and fluid therapy in sick camelids that might need long‐term care.     

Comparison of acetate tape impression with squeezing versus skin scraping for the diagnosis of canine demodicosis

This study compared the sensitivity of acetate tape impression and skin squeezing with that of deep skin scraping for the diagnosis of demodicosis in dogs. Demodex canis was detected in 100% of acetate tape impressions obtained after skin squeezing and in 90% of deep skin scrapings. There was a significant difference (P < 0.001) between the techniques in the total number of mites detected. Acetate tape impression with skin squeezing was found to be more sensitive than deep skin scraping and is an alternative diagnostic method for canine demodicosis.     

Phytoplankton community structure and the drawdown of nutrients and CO2 in the southern ocean

Data from recent oceanographic cruises show that phytoplankton community structure in the Ross Sea is related to mixed layer depth. Diatoms dominate in highly stratified waters, whereas Phaeocystis antarctica assemblages dominate where waters are more deeply mixed. The drawdown of both carbon dioxide (CO2) and nitrate per mole of phosphate and the rate of new production by diatoms are much lower than that measured for P. antarctica. Consequently, the capacity of the biological community to draw down atmospheric CO2 and transport it to the deep ocean could diminish dramatically if predicted increases in upper ocean stratification due to climate warming should occur.