Increase in milt production by hormonal treatment in the pejerrey fish Odontesthes bonariensis (Valenciennes 1835)

In spite of interest in the cultivation of the pejerrey fish Odontesthes bonariensis (Cuvier & Valenciennes 1835), there are few studies on subjects required to advance this activity. One of the problems is the synchronization of female and male maturation to provide eggs and sperm for larval production. The low volume of expressible milt, either in wild or culture fish, is a major problem. The aim of this work was to study the effectiveness of the administration of different hormones on sperm production in pejerrey. Milt production was enhanced by the injection of human chorionic gonadotropin (hCG) (16.7‐fold increase, 625 IU kg^?1), carp pituitary extracts (13.5‐fold increase, 30 mg kg^?1), salmon pituitary extracts (12.8‐fold increase, 30 mg kg^?1), salmon‐type gonadotropin‐releasing hormone analogue (GnRH) (16.7‐fold increase, 10 μg kg^?1) and mammalian‐type GnRH analogue (10.8‐fold increase, 20 μg kg^?1). Sperm concentration, motility and the fertilization rate were not statistically different compared with control groups. It was also demonstrated that sperm could be obtained off‐season. Taken together, hCG is recommended to stimulate pejerrey spermiation because it is effective in low doses is inexpensive and is widely available.     

Feeding responses of juvenile shrimp Litopenaeus vannamei (Boone) fed at different frequencies under laboratory conditions

In shrimp farms, food partitioning during the course of the day is contradictory, ethology studies may help in determining the proper frequency. Litopenaeus vannamei juveniles were placed in 30 L aquariums (41 m⁻²), exposed to a 12:12 h light–dark cycle. Feeding was provided at 10% of biomass three, four and seven times per day, with observations made in 15 min h⁻¹ windows, initiated after the ration was offered. Latency to access the feeding tray and to start eating was recorded using instantaneous focal sampling and digestive tract filling (DTF) by the continuous focal method. Weight gain was recorded at the end of the experiment. We performed seven repetitions, with 28 individuals observed for 33 days for each treatment (490 h of observation). The three-times offering induced less latency for accessing the tray and for ingesting the feed as well as a higher DTF when compared with the other frequencies. Animals fed three and four times had similar weight gains, and were greater than those fed seven times. Our results indicate that a more spaced food offering stimulates the search for and ingestion of feed. As compared with other frequencies, the three-times-per-day option assumes lower labour costs and a more efficient use of the feed.     

Genetic monitoring of deep‐water exploited banks of the precious Sardinia coral Corallium rubrum (L., 1758): useful data for a sustainable management

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Growth, stress response and free amino acid levels in Senegalese sole (Solea senegalensis Kaup 1858) chronically exposed to exogenous ammonia

Stressful husbandry conditions are likely to affect growth and amino acid metabolism in fish. In this study, chronic ammonia exposure was used to test the effects of a stressor on growth and amino acid metabolism of Senegalese sole juveniles. The fish were exposed for 52 days to 11.6 mg L⁻¹ [low‐TAN (L‐TAN)] or 23.2 mg L⁻¹ [high‐TAN (H‐TAN)] of total ammonia nitrogen (TAN), or to 0 mg L⁻¹ (Control). Growth in L‐TAN groups was slightly but significantly different from the Control groups [relative growth rate (RGR=0.35±0.13 and 0.52±0.23% day⁻¹ respectively)]. In H‐TAN groups, growth was severely affected (RGR=0.01±0.13% day⁻¹). Stress parameters (plasma cortisol and glucose) showed slight or no significant differences between treatments. Plasma free amino acid (FAA) concentrations were affected after H‐TAN treatment. Increases in glutamine and aspartate concentrations in H‐TAN fish suggest alterations in amino acid metabolism related to nitrogen excretion processes. Some of the changes in FAA concentrations also suggest mobilization to energy supply and synthesis of metabolites related to stress response. Therefore, Senegalese sole seem to adapt to the L‐TAN concentration tested, but the H‐TAN concentration reduced growth and affected amino acid metabolism.     

Comparison of 2 blind approaches to the paravertebral brachial plexus regional block in canine cadavers

The paravertebral brachial plexus block (PVB) provides thoracic limb analgesia. The objective was to describe a blind craniocaudal (CC) approach to the PVB and compare its accuracy, time, and difficulty of performance with a blind dorsoventral (DV) approach. The operator was initially trained by experienced clinicians to perform both approaches on 5 cadavers. Next, a CC or DV approach to the PVB was performed on both thoracic limbs of 20 cadavers (20 for each approach). Methylene blue dye was equally divided into 4 aliquots to stain the ventral branches of the sixth to eighth cervical and first thoracic spinal nerves. Successfully stained (stain ≥ 1 cm) spinal nerves were counted. The time to perform each approach was recorded and ease of performance was scored using a numerical scale (1 “easy” to 4 “difficult”). The phrenic nerve was checked for stain. A Wilcoxon signed-rank test was used to compare approaches. The data are presented as median (interquartile range; minimum to maximum range). The number of stained nerves with the CC approach 3 (1; 2 to 4), was higher than the DV approach 2 (2; 0 to 4) (P = 0.002). The time (in seconds) to perform the CC approach 125 (79; 70 to 194), was not different from the DV approach 142 (54; 101 to 232) (P = 0.084). The CC approach 2 (2; 1 to 4) was easier to perform than the DV approach 3 (1; 2 to 4) (P = 0.024). No phrenic nerve staining was observed with either approach. The CC approach is an alternative to the DV approach for performing the PVB in dogs.     

Genetic-diversity assessed by microsatellites in tropical maize populations submitted to a high-intensity reciprocal recurrent selection

BR-105 and BR-106 are important tropical maize populations, which were submitted to a high-intensity reciprocal recurrent selection, generating the IG-3 and IG-4synthetics. Using 30-microsatellite loci,we measured and compared the genetic diversity of these populations and their synthetics. The populations did not differ significantly regarding the amount of genetic diversity. As a consequence of selection, genetic variability losses, in terms of mean number of alleles per locus,proportion of polymorphic loci, and gene diversity did occur and were greater in the synthetic IG-3 than IG-4. In the synthetics, the number of loci in adherence to Hardy-Weinberg proportions was superior to that observed in the populations. The Wright's mean fixation index was higher than the mean value expected for outcrossing species (5%) indicating as light excess of homozygotic individuals in both populations. The genetic distances confirmed the favourable effects of one cycle of recurrent selection, as the synthetics became more isolated in comparison to the original populations. This revised version was published online in July 2006 with corrections to the Cover Date.     

Post‐hatching development of the ornamental ‘Red Cherry Shrimp’ Neocaridina davidi (Bouvier, 1904) (Crustacea,Caridea, Atyidae) under laboratorial conditions

The ‘Red Cherry shrimp’, Neocaridina davidi is a small freshwater caridean shrimp living, originally, in various kinds of inland water bodies around Asian countries. This shrimp has reached several countries for ornamental use; however, basic information on the biology of the species is still scarce in the literature. Its early post embryonic development morphology has not yet been described. This paper focused on the production and the development of early post‐hatching stages of N. davidi, its male secondary sexual features, observation of the gonads and the presence of females with embryos. The larval development of N. davidi was almost suppressed as noted by the presence of relatively large‐sized eggs, first stage hatching as a decapodid; and the tail fans were present only from the 2nd post‐hatching stage. A biological important consequence of the presence of this Red Cherry shrimp species in the Neotropics is its potential release into nature, which could cause its rapid dispersion affecting populations of other indigenous caridean freshwater shrimps.     

Immunohistochemical expression of HER - 2 and Ki - 67 in granulosa cell tumor in bitches

Granulosa cell tumour, an ovarian neoplasm of stromal origin, is an important tumour related to oestrogenic dominance syndrome and cystic endometrial hyperplasia–pyometra complex. In order to analyse ovarian tumour´s malignant potential, immunohistochemical markers can be used, such as anti-HER2 and anti-Ki-67. The aim of this study was to evaluate the expression of immunohistochemical markers HER-2 and Ki-67 in granulosa cell tumour from bitches´ ovaries. In HER-2 immunomarker analysis using the HercepTest^® method, most tumours were classified as 2+ (moderate labelling). Concerning Ki-67 immunomarker, only one case was described as having a high proliferative index. An association was found between immunostained cell percentage by anti-HER-2 antibodies and high pleomorphism, represented by the pattern of follicular/trabecular tumour arrangement. There was no correlation between anti-Ki-67 and anti-HER-2 antibody immunostaining intensities, probably due to only one case with a high Ki-67 index. With an effective protocol for HER-2 and Ki-67 immunohistochemical identification in granulosa cell tumours in bitches, it was possible to characterize this neoplasm proliferation profile.     

Comparison of the effects of six stunning/killing procedures on flesh quality of sea bass (Dicentrarchus labrax,Linnaeus 1758) and evaluation of clove oil anaesthesia followed by chilling on ice/water slurry for potential implementation in aquaculture

The effects of different stunning/killing procedures on flesh quality of European sea bass were investigated: (1) anaesthesia with clove oil, (2) anaesthesia with 2‐phenoxyethanol, (3) percussive stunning, (4) immersion in ice/water slurry, (5) chilling on ice and (6) anaesthesia with clove oil followed by immersion in ice/water slurry. Muscle pH values were significantly lower in sea bass anaesthetized or stunned by a blow to the head compared with fish immersed in ice/water slurry, chilled on ice or immersed in ice/water slurry after clove oil anaesthesia. Lightness was highest in sea bass anaesthetized by 2‐phenoxyethanol or percussively stunned and lowest in ice‐chilled fish. Redness and yellowness were highest in fish chilled on ice and lowest in fish anaesthetized with clove oil. Liquid loss, fat loss and shear values were not significantly different among the procedures. In general, lipid oxidation values during refrigerated or frozen storage did not significantly differ among treatment groups. Combination of clove oil anaesthesia followed by chilling on ice/water slurry appears to improve both flesh quality and welfare of sea bass, although the implementation of further studies is warranted to consolidate this finding.     

Distribution of red-spotted grouper nervous necrosis virus (RGNNV) antigens in nervous and non-nervous organs of European seabass (Dicentrarchus labrax) during the course of an experimental challenge

The distribution of red-spotted grouper nervous necrosis virus (RGNNV) antigens was examined by immunohistochemistry in the nervous and non-nervous organs of juvenile European seabass (Dicentrarchus labrax) during the course of an intramuscular infection. Histological changes resulting from the infection were evaluated from 3 days to 2 months post-infection. The specific antibody response was also studied 2 months post-challenge. Viral proteins were present throughout the experimental period in the retina (inner nuclear layer, ganglion layer, outer limiting membrane, and outer plexiform layer), brain (cerebellum and tectum opticum), and liver (hepatocytes and endothelial cells). These proteins were also observed in the renal tubular cells, white pulp of spleen, and in fibroblasts and cartilage of caudal fin. This is the first report of RGNNV proteins appearing in these organs, where the immunostaining was only detected at certain sampling times after the onset of mortality. Brain and retina of virus-exposed fish showed high levels of vacuolation, while accumulation of fat vacuoles was observed in the liver. RGNNV infection also induced a specific antibody response as measured by an ELISA. In summary, this is the first study demonstrating the presence of viral proteins in cells of caudal fin, kidney and spleen of European seabass.