Association between longline design and mussel productivity in Prince Edward Island, Canada

The first objective of this study was to document the design of subsurface longlines used for the farming of blue mussels (Mytilus edulis) in Prince Edward Island (PEI), Canada; the second objective was to identify possible associations between longline design and mussel growth. In 2003, SCUBA divers visited 54 farms distributed in 16 culture embayments; they measured the spacing between longlines and the spacing between individual socks (sleeves) attached to longlines; they also sampled one-year-old mussels for the determination of the shell length, condition index, and sock weight. Here we report a remarkable degree of variation in longline configuration, with the following range of values: 1.2 to 3.0 m for sock length, 1.5 to 29.5 m for longline spacing, 26.4 to 62.4 cm for sock spacing, and 6.2 to 179.9 socks/100 m² for stocking density at the farm scale. A negative correlation was found between stocking density at the farm scale and total farming area at the bay scale, suggesting that growers adjusted husbandry in relation to the surrounding level of farming activity. In one major culture bay, Tracadie Bay, measurements were repeated over a three-year period (2002-2004). This monitoring led to the discovery of a coordinated effort by growers in raising the average sock spacing by 30% (+ 11 cm). Multiple regression analyses identified sock spacing as the only explanatory variable correlated with mussel weight in Tracadie Bay. The model suggests that an 11-cm increase in sock spacing can lead to an 18% weight gain for pre-market mussels (∼ 34 mm), the size group investigated in the study. However, this correlation between sock spacing and sock weight was tenuous over the three-year study period, showing up only in 2002. A similar correlation was found between sock spacing and condition index, although only in 2004. We conclude by suggesting that close spacing of mussel socks can negatively affect mussel yield, although only under certain conditions.     

Genetic properties influencing the evolvability of gene expression

Identifying the properties of gene networks that influence their evolution is a fundamental research goal. However, modes of evolution cannot be inferred solely from the distribution of natural variation, because selection interacts with demography and mutation rates to shape polymorphism and divergence. We estimated the effects of naturally occurring mutations on gene expression while minimizing the effect of natural selection. We demonstrate that sensitivity of gene expression to mutations increases with both increasing trans-mutational target size and the presence of a TATA box. Genes with greater sensitivity to mutations are also more sensitive to systematic environmental perturbations and stochastic noise. These results provide a mechanistic basis for gene expression evolvability that can serve as a foundation for realistic models of regulatory evolution.     

响应面法优化姬松茸液体发酵培养基中红糖和酵母膏浓度

运用响应面分析法优化姬松茸液体发酵培养基中红糖和酵母膏浓度.结果表明,红糖浓度为20.24g/L、酵母膏浓度为2.055g/L时,菌丝体生物量最高,达2.279g/L;红糖浓度为20.8g/L、酵母膏浓度为2.23g/L时,胞外多糖产量最高,达0.749g/L.     

A scale-sensitive connectivity analysis to identify ecological networks and conservation value in river networks

Existing methods for connectivity analysis still encounter difficulties in explaining functional relationships between network structure and ecological patterns over larger territories or complex structures like dendritic river networks. We propose a method that addresses the problem of scale and resolution in the connectivity analysis of dendritic network structures, illustrated here for the re-colonization of the French Loire river basin by the European otter. The ecological niche factor approach is applied to infer favourable habitat in the river network based on large scale data of land use and hydro-morphology of river segments for the entire river basin. These analyses identified the stressors to the riparian zone of channel straightening, urbanisation and forest fragmentation as the principal factors explaining otter occurrence. Using this estimate of habitat favourability, we used the Integral Index of Connectivity to quantify habitat availability and connectivity in the dendritic river network. When we calculate the integral index of connectivity over different spatial extents by constraining network distances, the scale-sensitivity of the network’s connectivity emerges. Accounting for high mobility by entering larger network distances in the analysis identifies conservation networks and priorities mainly in downstream parts of the river basin, whereas with smaller network distances, more restricted high quality areas in central and upstream parts are highlighted. The presented approach performed better than distribution modelling approaches in explaining species occurrence over the river network and confirms the crucial aspect of connectivity in otter re-colonization.     

Elimination of animals with best growth potential as a possible effect of the culling of <Emphasis Type="Italic">Mercenaria mercenaria notata</Emphasis> (L.) larvae in hatchery procedure

The Mercenaria mercenaria notata line was introduced into the Canadian Atlantic provinces in the late 1990s because of its fast growth rate when compared with that of the current native line. The purpose of this study was to compare the development of two groups of M. mercenaria notata, according to the initial size of the individuals, in order to check whether the current hatchery practice of keeping only the largest larvae may ultimately eliminate the best performing animals. The larvae were raised and sorted by size according to standard hatchery practices. On the tenth day post-fertilization, the two larval size groups were formed. The “initially smaller” (IS) and the “initially larger” (IL) animals were grown separately. Mortality, shell length and energy reserves were measured for both groups at three stages: veliger, post-settling and juvenile. The observed mortality in the two groups was low varying from 8.1 to 19.6%. The IS animals had a higher shell growth rate (18.2 μm/day) when compared to the IL group (12.7 μm/day) with the result that at the end of the experiment, the IS animals were larger than the IL. In both groups, the lipid and protein concentrations diminished rapidly during the veliger stage but faster in the IL group. The glycogen level remained at the limit of detection for all the three stages. The use of energy reserves followed a different pattern according to the group size. This study indicates that culling would have led us to discard the animals which in fact have the best growth potential in that their rate of shell growth is the highest.     

Congenital portosystemic shunts in Maltese and Australian Cattle Dogs

SUMMARY Congenital portosystemic shunts were definitively diagnosed in 62 dogs over a period of 15 years. Maltese and Australian Cattle Dogs were significantly over-represented, accounting for 14 and 13 cases, respectively. Maltese invariably had a single extrahepatic shunt derived from the left gastric or gastrosplenic vein, whereas Cattle Dogs usually had large intrahepatic shunts involving the right liver lobes. The clinical syndromes resulting from anomalous portosystemic communications were indistinguishable in the 2 breeds. Fasting blood ammonia concentration was elevated in 20 of 22 dogs tested, providing a minimally invasive and effective means of diagnosis. Complete or partial shunt attenuation was performed successfully in all 9 Maltese and in 2 of 6 Cattle Dogs in which it was attempted.     

A phalangeal fusion defect and osteochondrosis dissecans with subluxation of the distal interphalangeal joints in a foal

A fusion defect of the proximal and middle phalanges of both hindlimbs, osteochondrosis dissecans of the distal interphalangeal joints of the forelimbs, and subluxation of all 4 distal interphalangeal joints occurred in a Standardbred filly. Lameness was the first abnormality noted and was observed at one week of age in the left forelimb and progressed until all 4 limbs were affected by 5 weeks of age. On radiographs of both forelimbs, the distal interphalangeal joints were subluxated with irregularity and lucency of subchondral bone. On radiographs of the distal hindlimbs, there was a subluxation of both distal interphalangeal joints and loss of the proximal interphalangeal joint spaces with fusion of the proximal and middle phalanges. The foal was euthanised. On necropsy, there were focal areas of erosion of articular cartilage in the distal interphalangeal joint of both forelimbs. The proximal and middle phalanges of both hindlimbs were fused. Histopathological examination of the distal interphalangeal joint of the right foreleg showed loss of articular cartilage and degenerative changes in the exposed subchondral bone.     

Characterization of structure and function of the mouse retina using pattern electroretinography, pupil light reflex, and optical coherence tomography

Objective To perform in vivo analysis of retinal functional and structural parameters in healthy mouse eyes. Animal Studied Adult C57BL/6 male mice (n?=?37). Procedures Retinal function was evaluated using pattern electroretinography (pERG) and the chromatic pupil light reflex (cPLR). Structural properties of the retina and nerve fiber layer (NFL) were evaluated using spectral-domain optical coherence tomography (SD-OCT). Results The average pERG amplitudes were found to be 11.2?±?0.7?μV (P50-N95, mean?±?SEM), with an implicit time for P50-N95 interval of 90.4?±?5.4?ms. Total retinal thickness was 229.5?±?1.7?μm (mean?±?SEM) in the area centralis region. The thickness of the retinal nerve fiber layer (mean?±?SEM) using a circular peripapillary retinal scan centered on the optic nerve was 46.7?±?0.9?μm (temporal), 46.1?±?0.9?μm (superior), 45.8?±?0.9?μm (nasal), and 48.4?±?1?μm (inferior). The baseline pupil diameter was 2.1?±?0.05?mm in darkness, and 1.1?±?0.05 and 0.56?±?0.03?mm after stimulation with red (630?nm, luminance 200?kcd/m(2) ) or blue (480?nm, luminance 200?kcd/m(2) ) light illumination, respectively. Conclusions Pattern electroretinography, cPLR and SD-OCT analysis are reproducible techniques, which can provide important information about retinal and optic nerve function and structure in mice.     

仔猪腹泻病的鉴别诊断及综合防治

对仔猪腹泻病进行了摸索、研究和总结,根据不同日龄和不同临床表现进行鉴别诊断,同时可采取组织病理学、微生物学方法进一步确诊,并采取针对性防治措施,才能有效地控制仔猪腹泻病.