Comparative growth and welfare in rainbow trout reared in recirculating and flow through rearing systems

The objective of this study was to compare fish performance and welfare at different stocking densities in a recirculating system (RS) and a flow through system (FTS) under field conditions. During the 77 days experiment, the fish survival rate was high (99.3%) and stocking density increased from 57 to 98–108 kg m^?3. No significant differences in growth were observed between RS and FTS until day 56. Later, growth decreased in the FTS, while it remained similar to the farm reference at 50 kg m^?3 in the RS. Final weight was 17% higher in RS than in FTS. The maximum carrying capacity of the RS was near 100 kg m^?3, limited by NO₂ increase up to safe level at the end of the experiment, the maximum carrying capacity of the FTS was near 85 kg m^?3, probably limited by CO₂ concentration (17.8 ± 5.7 mg l^?1). In the RS, the relative length index of pectoral and dorsal fins was lower than in the FTS, which may be attributed to the tank hydrodynamics. In both systems, an improvement of the pectoral and dorsal profile was observed at the end of the experiment, attributed to a swimming activity reduction that may have decreased contact between individuals. In the RS, high caudal fin deterioration (50% versus 20% in FTS) was observed irrespective of stocking density, that could be linked to the highest water velocity modifying the fish swimming activity. The results confirm that when water quality is maintained in safe level ranges, high densities can be used in trout RS without fish performance and pectoral or dorsal fin deterioration, but with a major caudal impairment.     

Effects of isoxaben on sensitive and tolerant plant cell cultures : II. Cellular alterations and inhibition of the synthesis of acid-insoluble cell wall material

The herbicide isoxaben is selectively phytotoxic to dicotyledonous plants, whereas most monocots are tolerant. We previously selected a soybean cell culture tolerant to isoxaben. Some effects of the herbicide on wild-type soybean cells, tolerant soybean cells, and wheat cells were compared. Cytological observations showed that isoxaben induced some disorganization of sensitive soybean cells, especially at the plasma membrane-cell wall interface. Tolerant soybean cells appeared normal in the presence of isoxaben. The growth of wild-type soybean cells was roughly equally sensitive to isoxaben as to dichlobenil, a cellulose synthesis inhibitor. By comparison, the selected soybean line and a wheat cell culture were less sensitive to isoxaben than to dichlobenil. Glucose incorporation into acid-insoluble cell wall material was more inhibited by isoxaben than by dichlobenil in the wild-type soybean cell culture. In the tolerant soybean cell culture, the incorporation was slightly inhibited by isoxaben, but remained sensitive to dichlobenil. In the wheat cell culture, dichlobenil was also more inhibitory but only at high concentrations. Other compounds, inhibitors of cellulose biosynthesis, of glycosylation of lipids or protein, or of cell division, either had no effect on the synthesis of acid-insoluble cell wall material or exerted apparently unspecific inhibitions. The results are consistent with isoxaben inhibiting the synthesis of a cell wall polysaccharide, which could be cellulose.     

Growth performance and adipose tissue deposition in barrows fed n-methyl-D,L-aspartate

We previously reported that broilers fed n-methyl-D,L-aspartate (NMA) exhibited enhanced feed conversion efficiency and decreased percentage of fat in carcasses. In this experiment, growth performance and backfat thickness were evaluated in barrows fed NMA. Poland China x Yorkshire barrows weighing 68.8 +/- 1.7 kg (mean +/- SE) were allowed ad libitum access to feed containing NMA at levels of either 0 (n = 7), 100 (n = 6), 200 (n = 8), or 300 (n = 8) mg/kg for 36 d. Barrows were slaughtered at 99.5 +/- 2.3 kg BW. There was no effect (P > 0.1) of NMA on ADG or feed consumption. Gain:feed ratio decreased (P < 0.03) in a linear fashion with increasing level of NMA. There was a cubic effect (P < 0.05) of NMA treatment on first-rib backfat thickness. In response to graded levels of NMA, backfat thickness at the 10th rib (P < 0.08) and last rib (P < 0.03) increased in a linear fashion. The NMA had no effect (P > 0.1) on backfat thickness measured at the lumbar vertebra or longissimus muscle area measured at the 10th rib interface. The percentage of lean in the carcass decreased in a linear fashion (P < 0.05) in response to increasing levels of NMA in the diet. In summary, NMA had an overall negative effect on growth performance and carcass yield characteristics in barrows. The dichotomous effects of NMA on feed efficiency and body composition in poultry and swine warrants further scrutiny.     

Comparative analysis of canine dermatophytosis and superficial pemphigus for the prevalence of dermatophytes and acantholytic keratinocytes: a histopathological and clinical retrospective study

Acantholytic dermatophytosis is a rarely reported condition of dogs that clinically and histopathologically mimics superficial pemphigus (erythematosus, foliaceus). Histologically, periodic acid-Schiff (PAS) and Grocott's methenamine-silver (GMS) are often necessary to show the fungus. A retrospective histopathological study was conducted on 190 canine skin biopsy specimens: 95 each with the diagnosis of canine dermatophytosis or of superficial pemphigus. All specimens were stained with haematoxylin and eosin, PAS, and GMS. Dermatophytes were not seen in any superficial pemphigus cases. Acantholytic keratinocytes were noted in 14% of the dermatophytosis cases, none of which had clinical signs consistent with superficial pemphigus. Among cases with acantholytic keratinocytes, superficial pemphigus had significantly more acantholytic cells than dermatophytosis (P = 0.02). When comparing face and nonface cases, there was no difference in prevalence of acantholytic keratinocytes in dermatophytosis or number of acantholytic keratinocytes in superficial pemphigus. All dermatophyte cases were both GMS and PAS positive with neither stain being visually superior. No dermatophyte cases where acantholytic keratinocytes were noted had a history, clinical signs and histopathological features compatible with acantholytic dermatophytosis.     

The new (challenging) role of academia in biomaterial translational research and medical device development

With the ever-changing landscape of translational research, the medical device and pharmaceutical industries increasingly license technologies with the added value of clinical and/or pre-clinical data rather than those in earlier stages of development. Universities have the potential to fill the gap in product development from academic laboratories through enhanced student training and increased implementation of some development and manufacturing activities that are traditionally found only in the private sector. A development roadmap is described from initial product feasibility through commercialization in the context of efficient development practices. The specific challenges in the design and development of biomaterial-based medical devices are described in the context of this development path with an emphasis on unique challenges for academic laboratories.