Needle anatomy changes with increasing tree age in Douglas-fir

Morphological differences between old-growth trees and saplings of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) may extend to differences in needle anatomy. We used microscopy with image analysis to compare and quantify anatomical parameters in cross sections of previous-year needles of old-growth Douglas-fir trees and saplings at the Wind River Canopy Crane site in Washington and at three sites in the Cascade Mountains of Oregon. We also compared needle anatomy across a chronosequence of 10-, 20-, 40- and 450-year-old Douglas-fir trees from the Wind River site. Anatomy differed significantly between needles of old-growth trees and saplings at all sites, suggesting a developmental change in needle anatomy with increasing tree age. Compared with needles of old-growth trees, needles of saplings were longer and had proportionately smaller vascular cylinders, larger resin canals and few hypodermal cells. Astrosclereids, which sequester lignin in their secondary cell walls and occupy space otherwise filled by photosynthetic cells, were scarce in needles of saplings but abundant in needles of old-growth trees. Needles of old-growth trees had an average of 11% less photosynthetic mesophyll area than needles of saplings. The percentage of non-photosynthetic area in needles increased significantly with increasing tree age from the chronosequence of 10-, 20-, 40- and 450-year-old trees at the Wind River site. This reduction in photosynthetic area may contribute to decreased growth rates in old trees.     

Effect of bandaging on second intention healing of wounds of the distal limb in horses

Objective   To evaluate the effect of a non-occlusive dressing incorporated in a 3-layer bandage on second intention healing of wounds of the distal portion of the limb.
Study Design   Untreated wounds in 33 adult horses used in four studies using the same wound-healing model conducted over 5 years.
Methods   Standardised, full-thickness wounds were made in the skin overlying the dorsomedial aspect of the mid-metacarpus; 17 horses were bandaged with a non-occlusive dressing covered by gauze-coated cotton wool that was compressed with adhesive tape; 16 horses were left unbandaged. Wounds were photographed weekly for 9 weeks and the images were analysed electronically.
Results   There were significant effects associated with bandage (P < 0.0001), week (P < 0.001), and bandage by week interaction (P < 0.0001). There was no difference in wound area at the first time-point after wound creation (P = 0.38). After week 1, there was a difference between bandaged and unbandaged wounds in wound area at each measurement until the end of the study. Bandaged wounds showed greater and more prolonged retraction. Unbandaged wounds retracted for 2 weeks before beginning to contract, whereas bandaged wounds continued to retract for 3 weeks. In bandaged wounds excess granulation tissue required regular trimming, but not in unbandaged wounds. There was no difference between groups in the total days to healing or the overall rate of healing.
Conclusions   These results should be treated with caution until validated with contemporaneous, controlled studies. Covering a wound with a non-occlusive dressing in a 3-layer bandage led to greater wound retraction, modulated the rate of wound contraction and promoted excessive granulation tissue. If excessive granulation tissue is excised regularly, bandaging has no effect on total time to healing.     

Evaluation of the thyroid status of Basenji dogs in Australia

Objective To determine the thyroid status of Basenji dogs in Australia. Methods Jugular or cephalic venipuncture blood samples were taken from 113 Basenji, comprising 47 males, 5 castrates, 48 entire and 13 spayed bitches, and sent on ice in plain and EDTA tubes to a single laboratory to determine haematocrit and serum concentrations of total thyroid hormone (thyroxine, TT4), thyroid‐stimulating hormone (TSH) and cholesterol. In a subgroup of 8 dogs with abnormal elevated TSH concentrations and subnormal TT4 concentrations, 5 were further examined by dynamic endocrine testing using recombinant human (rh) TSH (54 µg). Results Ages ranged from 1 to 14 years and weight range was 6.5 to 14.0 kg. TT4 concentrations (nmol/L) ranged from 2 to 27, with a median of 13 and a mean ± SD of 13.0 ± 5.7. Importantly, 85/113 (75%) of TT4 values were lower than the normal laboratory reference range (17–37). TSH concentrations (ng/mL) ranged from 0.05 to 5.37, with a median of 0.16 and a mean ± SD of 0.3 ± 0.6. Conclusions Basenji have a similar reference range for serum TSH, but a considerably lower reference range for TT4 (2–27 nmol/L) than most breeds and crossbreds, resembling the sight hounds in this respect. Given the difficulty of accurately measuring TT4 concentrations that are so low, concomitant serial TSH determinations are essential to properly asses thyroid function. Taken alone, TT4 determinations are only of use when the value is within the reference range, in which case a diagnosis of hypothyroidism is likely excluded.     

Methods for the rapid appraisal of African animal trypanosomosis in the Gambia.

A technique for the rapid field assessment of African animal trypanosomosis (AAT) was developed during studies in the Gambia. This involved gathering indigenous information from rapid-appraisal questionnaires addressed to local informants, the results of single tsetse surveys and evaluations of the prevalence of trypanosome infections in village cattle. Local informants included livestock owners and herdsmen and trained personnel such as livestock assistants. The answers to the questionnaires were weighted in order to translate them into semi-quantitative ranked estimates (zero, low, medium, high or very severe) of the severity of AAT problems. A similar ranking was also defined for tsetse and prevalence data in the Gambia. The three assessment methods generally gave complementary results leading to similar conclusions about the severity of tsetse-trypanosomosis problems in a survey area; inconsistencies usually suggested that additional information was needed. The rankings of AAT intensity were used to develop management guidelines for minimising the impact of AAT at different levels through control interventions or improved livestock management. The methodology was designed to provide reliable, up-to-date and cost-effective assessments of AAT problems. Emphasis was placed on the importance of the involvement, priorities and perceptions of village livestock owners and herdsmen in making these assessments.     

Mytilus species under rope culture in Scotland: implications for management

Mussel (Mytilus spp.) production is one of the most economically important aspects of global aquaculture and, in Scotland, production has increased from 262 t in 1986 to 4,219 t in 2006. Until recently, mussel production in Scotland was considered to be based exclusively on the blue mussel Mytilus edulis, the native species. In Europe, production is known to consist of M. edulis and M. galloprovincialis, while a third less profitable species M. trossulus occurs in the Baltic Sea, where it is unexploited. In Scotland, the sympatric occurrence of M. edulis, M. trossulus, M. galloprovincialis and their hybrids in cultivation in Loch Etive has recently been reported, with significant losses in production attributed to the presence of M. trossulus. Samples of mussels were taken at three depths from 10 rope-farm sites in Loch Etive. The distribution of the Mytilus species and their hybrids in Loch Etive was investigated using the Me 15/16 nuclear DNA locus for species and hybrid identification. All three species and their hybrids were detected and the data were in agreement with the Hardy–Weinberg model suggesting panmixia. Frequencies of M. galloprovincialis and its hybrids were very low. Overall, M. trossulus (37%) was found to be more common than M. edulis (30%) and 23% of the sampled mussels were M. trossulus × M. edulis hybrids. Species distribution did not correlate with year of settlement nor with salinities taken at the time of sampling. There were significant differences in species distribution due to site location and depth, with M. edulis being more frequent at 8 m depth and M. trossulus more common at shallower depths. These differences might be exploitable in management strategies for continuing production, for example to decrease the prevalence of M. trossulus at shellfish farms in favour of the more desirable M. edulis.     

Histology,immunocytochemistry and qRT‐PCR analysis of Atlantic salmon,Salmo salar L., post‐smolts following infection with infectious pancreatic necrosis virus (IPNV)

Infectious pancreatic necrosis (IPN) is a very serious viral disease in terms of its impact on production of Atlantic salmon, Salmo salar L., fry and post‐smolts. Post‐smolts of Atlantic salmon were injected with infectious pancreatic necrosis virus (IPNV) and cohabited with naive fish to produce natural infection. Cohabitant fish were sampled every 2 days, up to day 36 post‐infection (p.i.). From 90 cohabitant fish, 11 (12.2%) were positive by immunohistochemistry (IHC). The first detection of IPNV by IHC occurred on day 16 p.i. which coincided with the onset of mortality in this group. Besides the pancreas, the liver was found to be a key target organ for IPNV. For the first time, the virus was observed in the islets of Langerhans and in the kidney corpuscles of Stannius which suggests that the virus could affect the fish’s metabolism. The liver of two fish, which showed the most widespread presence of IPNV by IHC, had a pathology including focal necrosis and widespread presence of apoptotic hepatocytes, many of which did not stain for virus by IHC. Up‐regulation of cytokine gene expression was found only in the IHC‐positive (IHC+ve) fish and reflected the level of infection as determined by IHC positivity of the liver. In most fish, interferon (IFN), Mx, γIFN and γIP were up‐regulated in liver and kidney, while only IFN and Mx were up‐regulated in gill. IL1β and TNFα were not induced in any tissue. The gill showed variable levels of constitutive expression of IL1β and γIFN. The two fish with liver pathology had the highest level of IFN expression, especially relative to the level of Mx expression, in the liver compared with the other IHC+ve fish which did not have a liver pathology. The results suggest that following widespread infection of hepatocytes, the cells may over‐produce IFN, resulting in apoptosis of neighbouring cells with subsequent death from liver failure.     

In vitro Effect of Zearalenone and α-Zearalenol on Boar Sperm Characteristics and Acrosome Reaction

This study was conducted to determine the in vitro effects of three different concentrations (125, 187.5 and 250 microM in diluted semen) of zearalenone (zen) and alpha-zearalenol (alpha-zen) on boar sperm. Semen parameters such as motility, viability and spontaneous acrosome reaction were evaluated. From the results it was shown that both zen and alpha-zen affected the sperm characteristics significantly (p < 0.05), except for alpha-zen at the low concentration which did not decrease the percentage of live reacted spermatozoa significantly. In conclusion, zen and alpha-zen are directly toxic when they affect boar semen in vitro and consequently decrease the fertilization ability of the sperm. The higher the concentration of mycotoxin tested, the greater the decline of sperm parameters noticed. The influence of mycotoxins was found to be time- and dose-dependent.