Phenotypic effects of antibiotic‐induced axenity and egg disinfection in early larval European seabass (Dicentrarchus labrax L.)

In the present study, the hypothesis that the difference in axenic conditions in the incubation and rearing environment of European seabass larvae induces size and shape effects on the specimens is tested. This difference is studied between xenic and axenic seabass larvae of DAH (day after hatching) 0, 5, 11 and 15. The axenic rearing protocol involves an egg disinfection with glutaraldehyde after the primary one with iodine in the hatchery, and the hypothesis that this secondary disinfection induces size and shape effects is also tested. In order to accomplish this, three egg and larvae treatments are included: “DA” (disinfected axenic), “DX” (disinfected xenic) and “NX” (nondisinfected xenic). Regarding the effect of antibiotic‐induced axenity, DA larvae exhibited larger bodies than both DX and NX on DAH 5 and 11. They also had a smaller yolk sac than DX at hatching, but consumed it slower. Towards the end of the experiment, DA larvae were thicker, but slightly more curved than DX and NX, which may be an abnormal shape, or a slightly more advanced ontogenetic stage. As far as egg disinfection, it had significant but very moderate shape effects on DAH 5 and 11, and disinfected larvae consumed their yolk sac faster. To the best of our knowledge, this study is one of the first to illustrate the subtle but significant size and shape effects caused by antibiotic‐induced axenity and secondary egg disinfection in the early larval stages, which suggest the existence of bacterial mechanisms that play a phenotypic role.     

The large‐scale removal of mammalian invasive alien species in Northern Europe

Numerous examples exist of successful mammalian invasive alien species (IAS) eradications from small islands (<10 km²), but few from more extensive areas. We review 15 large‐scale removals (mean area 2627 km²) from Northern Europe since 1900, including edible dormouse, muskrat, coypu, Himalayan porcupine, Pallas' and grey squirrels and American mink, each primarily based on daily checking of static traps. Objectives included true eradication or complete removal to a buffer zone, as distinct from other programmes that involved local control to limit damage or spread. Twelve eradication/removal programmes (80%) were successful. Cost increased with and was best predicted by area, while the cost per unit area decreased; the number of individual animals removed did not add significantly to the model. Doubling the area controlled reduced cost per unit area by 10%, but there was no evidence that cost effectiveness had increased through time. Compared with small islands, larger‐scale programmes followed similar patterns of effort in relation to area. However, they brought challenges when defining boundaries and consequent uncertainties around costs, the definition of their objectives, confirmation of success and different considerations for managing recolonisation. Novel technologies or increased use of volunteers may reduce costs. Rapid response to new incursions is recommended as best practice rather than large‐scale control to reduce the environmental, financial and welfare costs. © 2016 Crown copyright. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Distribution and ecology of the Belgian Campodea species (Diplura: Campodeidae)

From 2004 till 2008, Diplura were sampled at 96 localities in Belgium. Nine different species of Campodea were collected: Campodea fragilis Meinert 1865, Campodea lankesteri Silvestri 1912, Campodea lubbocki Silvestri 1912, Campodea meinerti Bagnall 1918, Campodea plusiochaeta Silvestri 1912, Campodea remyi Denis 1930, Campodea rhopalota Denis 1930, Campodea staphylinus Westwood 1842 and Campodea wallacei Bagnall 1918. The ordination technique non-metric multidimensional scaling indicated that pH and temperature/humidity were probably the most important variables determining species composition. However, it was remarkable that almost all combinations of species were encountered in the field, often even under the same stone. As no temporal segregations seem to take place, it remains unknown how these very similar species can occur together.     

No evidence of a plant extinction debt in highly fragmented calcareous grasslands in Belgium

Long transient times in response to decreasing habitat area and increasing isolation may cause the present plant species distribution to reflect the historical rather than the present landscape configuration, resulting in a so-called extinction debt. To investigate how plant species richness is shaped by both present and historical landscape configuration and local environmental conditions in fragmented calcareous grasslands, 64 sites in Southern Belgium were surveyed for their total species richness and environmental characteristics. Species were subdivided in specialist and generalist groups and the former were clustered into emergent groups (EGs) according to 16 relevant life-history traits. Four specialist emergent groups were derived: orchids, rosette species, annuals and half-rosette species. Both specialist and generalist species richness increased with present fragment area, while present fragment connectivity only affected the number of specialist species. This trend was maintained for most EGs, although habitat area was mostly more important than connectivity. All species groups responded to an insolation gradient, except EGs of rosette and annual species. Differential response to fragmentation among emergent groups could be interpreted in terms of dispersal and persistence traits. No relation between species richness and historical area or connectivity was found, making an extinction debt unlikely. Hence, present-day variation in plant species diversity seems to be no legacy of past landscape configuration. Our results clearly indicate that plant species may be quickly lost in response to new fragmentation events. To restore plant diversity, management should focus both on mitigating landscape fragmentation and restoring habitat quality.     

Scale-dependent effects of terrestrial habitat on genetic variation in the great crested newt (Triturus cristatus)

Landscape Ecology - Terrestrial landscapes surrounding aquatic habitat influence the persistence of amphibian spatially structured populations (SSPs) via their crucial role in providing estivation...     

Pituitary response to thyrotropin, corticotropin, and gonadotropin-releasing hormones in lactating cows treated with sometribove for a fourth consecutive lactation

The effect of chronic treatment with recombinant methionyl bovine somatotropin (USAN, sometribove) on anterior pituitary secretions and its target organs was investigated in six control and six sometribove-treated British Friesian cows. Cows averaged 112 and 119 d postpartum in their fourth lactation of treatment and, except for one control, had active corpora lutea. During each lactation, treated cows received sometribove injections (500 mg) every 2 wk (injection cycle) starting 60 ± 3 d postpartum. On Day 9 of one injection cycle, blood was sampled for 390 min, starting 30 min before an intravenous injection of thyrotropin (TRH, 0.33 μg/kg), corticotropin (100 μg), and gonadotropin (GnRH, 200 μg)-releasing hormones. Baseline somatotropin (bST) and adrenocorticotropin (ACTH) were higher in sometribove-treated cows vs. controls (3.27 vs. 1.03 ng/ml and 35.24 vs. 19.28 pg/ml, respectively). Baseline total thyroxine, free thyroxine, triiodothyronine, prolactin, follicle stimulating and luteinizing hormones, estradiol, and progesterone (P4) were similar across treatments. Circulating cortisol levels did not differ between control and sometribove cows, indicating a reduced adrenal ACTH responsiveness in the latter. Releasing factors induced similar changes across treatments in hormones studied with the following exceptions: a bST spike was seen in control cows only, cortisol response to ACTH was reduced in treated cows, and a significantly higher P4 concentration was detected in the plasma of sometribove-treated cows, suggesting increased ovarian responsiveness to GnRH-stimulated P4 output. The study demonstrated reduced bST response to TRH, consistent with physiologic feedback mechanisms, whereas the release profiles of the other pituitary hormones were unaffected. Target tissue responses affected by chronic sometribove treatment appear to be adrenal cortisol and ovarian P4 output.     

Saddleback syndrome in European sea bass Dicentrarchus labrax (Linnaeus, 1758): anatomy,ontogeny and correlation with lateral‐line,anal and pelvic fin abnormalities

This study focused on the anatomy and ontogeny of saddleback syndrome (SBS) in reared European sea bass. The abnormality was detected at an unusually high frequency (12–94%) during a routine quality control in a commercial hatchery. Anatomically the abnormality was mainly characterized by the loss of 1–5 hard spines and severe abnormalities of the proximal pterygiophores (anterior dorsal fin), size reduction of a few lepidotrichia, missing lepidotrichia and/or lepidotrichia of poor ossification (posterior dorsal fin). SBS was significantly correlated with abnormalities of the anal and pelvic fins in all the examined populations. Moreover, in juvenile fish, SBS was significantly correlated with an abnormal lack of sectors of the lateral line. The examination of early larval samples revealed that SBS was ontogenetically associated with severe abnormalities of the primordial marginal finfold, which developed at the flexion stage (ca 8.5–11.0 mm SL). Histologically, these abnormalities were associated with extensive epidermal erosion. The results are discussed in respect of the critical ontogenetic period and the possible causative factors of SBS in European sea bass. It is suggested that causative factors acted during a wide ontogenetic period including flexion and metamorphosis phases.     

Morphological and histological characterization of an ectopically mineralized structure in a gilthead sea bream Sparus aurata with opercular deformation

In this study, we describe an abnormal ectopically mineralized structure (EMS) that was found inside the skull of a juvenile Sparus aurata that also showed a bilateral opercular deformation. The overall phenotype and tissue composition were studied using micro‐CT scanning and histological analyses. The ectopic structure occupies a large volume of the brain cavity, partially extruding into the gill cavity. It shows a dense mineralization and an extracellular matrix‐rich phenotype, with variation in both the morphology and size of the cell lacunae, combined with an irregular fibre organization inside the matrix. This study is the first to report such an EMS in a juvenile teleost fish, where the tissue does not resemble any other connective tissue type described in bony fish so far. The tissue phenotype seems to rule out that the EMS corresponds to a tumorous cartilage. Yet, it is rather reminiscent of a highly mineralized structure found in cartilaginous fish, where it is suggested to be associated with damage repair.     

NORMAL REGIONAL DISTRIBUTION OF CEREBRAL BLOOD FLOW IN DOGS: COMPARISON BETWEEN 99mTc‐ETHYLCYSTEINATE DIMER AND 99mTc‐ HEXAMETHYLPROPYLENE AMINE OXIME SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY

Functional imaging provides important insights into canine brain pathologies such as behavioral problems. Two ^99mTc‐labeled single photon emission computed tomography (SPECT) cerebral blood flow tracers—ethylcysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO)—are commonly used in human medicine and have been used previously in dogs but intrasubject comparison of both tracers in dogs is lacking. Therefore, this study investigated whether regional distribution differences between both tracers occur in dogs as is reported in humans. Eight beagles underwent two SPECT examinations first with ^99mTc‐ECD and followed by ^99mTc‐HMPAO. SPECT scanning was performed with a triple head gamma camera equipped with ultrahigh resolution parallel hole collimators. Images were reconstructed using filtered backprojection with a Butterworth filter. Emission data were fitted to a template permitting semiquantification using predefined regions or volumes of interest (VOIs). For each VOI, perfusion indices were calculated by normalizing the regional counts per voxel to total brain counts per voxel. The obtained perfusion indices for each region for both tracers were compared with a paired Student's T‐test. Significant (P < 0.05) regional differences were seen in the subcortical region and the cerebellum. Both tracers can be used to visualize regional cerebral blood flow in dogs, however, due to the observed regional differences, they are not entirely interchangeable.