Radial distribution of carbohydrate reserves in the trunk of declining European beech trees (Fagus sylvatica L.)

Context

European beech (Fagus sylvatica L.) is considered threatened by anticipated climate change, but the physiological causes of potential beech decline or mortality remains poorly understood.

Aims

The purpose of the present study was to fuel debate about the assumption that carbohydrate depletion is involved in the decline of mature European beech.

Methods

The health status of beech trees from a severely declining stand was visually assessed by examining their crown condition. Content and radial distribution of non-structural carbohydrates (starch and soluble carbohydrate) were analyzed in the trunks and compared to those reported earlier in trunks of healthy beech trees.

Results and discussion

The distribution of carbohydrate in the beech trunks recorded here seemed affected by decline. We found a stronger radial decrease of starch content than those reported earlier for healthy beech trees. Carbohydrate reserves appear partially maintained in the outermost rings while starch depletion occurred in older wood rings in declining trees that may be able to mobilize carbohydrate reserves from older wood rings in response to successive climatic constraints.     

One dominant gene conferring the resistance to the leafminer, Liriomyza trifolii(Burgess) Diptera: Agromyzidae in melon (Cucumis melo L.)

The line Nantais Oblong, a melon of Charentais type, was shown to be a source of resistance by antibiosis to the leafminer, Liriomyza trifolii (Burgess), Diptera, Agromyzidae. We studied the genetic control of this resistance in F2 and back-cross progenies from the cross between Nantais Oblong and Védrantais, a Charentais line susceptible to the leafminer. Tests were carried out on young plants in plastic cages with controlled infestation. Complete mortality of the L. trifolii larvae was used as indicator of plant resistance. Segregation ratios were consistent with monogenic dominant control of the resistance. The symbol Lt for Liriomyza trifolii resistance is proposed.     

Preliminary investigations of the physiological adjustments associated with compensatory growth in juvenile brook charr (Salvelinus fontinalis)

Various physiological factors suspected to govern or be influenced by growth or feed intake of brook charr (80–120 g) were examined under long and short fasting periods during the year. A control (fed to satiation) was included. During winter, fasting (14 and 28 days) followed by refeeding led to a complete compensation. In summer, longer fasting (39 and 61 days) was applied to exacerbate the physiological response. Compensatory growth was observed in the restricted groups, and overall, adjustments/variations in growth and physiological indicators (feed conversion ratio, organosomatic index, enzymatic activities [CS, TRY, CHY]) were more pronounced. Degree of compensation reached was positively related to the deprivation duration. The summer experiment clearly suggests that compensatory growth takes place in two stages after a long starvation period (61 days): (1) restoration of the digestive system (PSI) followed by enzyme activities (trypsin and chymotrypsin) and (2) rebuilding of somatic tissues.     

Evolutionary discrimination of mammalian conserved non-genic sequences (CNGs)

Analysis of the human and mouse genomes identified an abundance of conserved non-genic sequences (CNGs). The significance and evolutionary depth of their conservation remain unanswered. We have quantified levels and patterns of conservation of 191 CNGs of human chromosome 21 in 14 mammalian species. We found that CNGs are significantly more conserved than protein-coding genes and noncoding RNAS (ncRNAs) within the mammalian class from primates to monotremes to marsupials. The pattern of substitutions in CNGs differed from that seen in protein-coding and ncRNA genes and resembled that of protein-binding regions. About 0.3% to 1% of the human genome corresponds to a previously unknown class of extremely constrained CNGs shared among mammals.     

Modeling carbon stock dynamics under fallow and cocoa agroforest systems in the shifting agricultural landscape of Central Cameroon

With increasing concerns raised by climate change, understanding biological processes within cocoa (Theobroma cacao L.) agroforest (CAF) and fallow systems is a prerequisite for developing actions related to emission reduction in the shifting agricultural landscape of Cameroon. Carbon (C) stocks and accretion were assessed and modeled in various C components (large trees, small trees, dead wood, litter, roots, soil, and total C) of fallow and CAF systems along a 50-year chronosequence. Several functions were empirically fitted to a time series of C stocks. Large tree, soil, and total C stocks were best described by a logistic growth function while that for small trees by a rational quadratic function. The best-fitted functions explained 72–96 % of C stock accumulation over time. Two metrics describing C stock accretion were derived from these functions: the point of maximum C growth and the C growth coefficient (GC). The rate of maximum growth of total C stock was reached after 12–13 years in both fallow and CAF, with maximum GCs of 6.9 and 6.3 Mg C ha^?1 year^?1, respectively. Over the 50-year period, the GCs of total C stocks varied between 0.2 and 6.9 Mg C ha^?1 year^?1, with quick accumulation within the first decade that then slowed until it levelled off after 45 years. Over a period of about 30 years, both systems sequestered a total of ~200 Mg C ha^?1. This indicates that cocoa agroforests, a main source of income for local populations, can also provide significant climate change mitigation services.     

Discrepancies between the isolation of Salmonella from mesenteric lymph nodes and the results of serological screening in slaughter pigs

Most Salmonella control programmes are based on serological testing in the slaughterhouse. However, from a point of view of carcass contamination, it is rather the presence of Salmonella spp. in the animal at the time of slaughter that is important. The aim of this cross-sectional study was to investigate the possible discrepancies between the isolation of Salmonella spp. in the mesenteric lymph nodes and the results of serological screening. In total, 1821 fattening pigs originating from 60 Belgian farrow-to-finish herds were sampled in the slaughterhouse. The serum samples were analysed using an indirect mix-ELISA for the presence of Salmonella antibodies and evaluated at 3 cut-off values namely 10, 20, and 40% Optical Density (OD). All mesenteric lymph node samples were submitted to qualitative Salmonella isolation and a representative number of isolates was serotyped. From each herd, 30 animals were screened both serologically and bacteriologically and the herd was considered as positive when at least one sample was positive. At the herd level, 83.6% (cut-off OD 40%) to 100.0% (cut-off OD 10%) of the herds from which Salmonella had been isolated were evaluated as seropositive. At the individual level, only 34.5% (cut-off OD 40%) to 82.8% (cut-off OD 10%) of the animals from which Salmonella had been isolated were seropositive. Overall, a weak agreement was found between bacteriology and serology for Salmonella diagnosis. If pig herds are categorised using serological tests in the slaughterhouse, one should be aware of the fact that slaughter pigs can still harbour Salmonella spp. in the mesenteric lymph nodes, without being detected in serological tests. The cut-off value used to evaluate a sample as serologically positive and the number of samples per herd are of major importance to classify herds correctly in order to protect human health.     

Of all the nerve! A subcutaneous forelimb mass on a cat

A 16-year-old, male, neutered cat had a 2.5 X 1.5 cm mass on the medial aspect of the right carpus. Cytologic examination of a fine-needle aspirate of the mass indicated a markedly pleomorphic population of plasmacytoid to histiocytic-appearing cells. The cytologic diagnosis was malignant neoplasia of probable mesenchymal or round cell origin. The right forelimb was surgically removed and the scapular, axillary, and prescapular lymph nodes were excised. Malignant fibrous histiocytoma was tentatively diagnosed histologically; however, the tumor cells subsequently were found to be negative for histiocytic (MAC 387, antitrypsin), T-cell (CD3), and B-lymphocyte (immunoglobulin light chains, Ly 5/CD45R) markers, and positive for glial fibrillary acidic protein, vimentin, and S-100. Based on the immunohistochemical results, the diagnosis was modified to malignant peripheral nerve sheath tumor (PNST). Six months after surgery, the cat was reported to be well and had no evidence of metastasis. PNSTs are rare tumors in cats, and are considered as synonymous with schwannomas, neurofibrosarcomas, and hemangiopericytomas. In this cat, the plasmacytoid and pleomorphic appearance of the PNSTcells in cytologic and histologic specimens was unusual, and made it difficult to reach an accurate diagnosis without immunocytochemistry.     

Prevalence of methicillin-resistant Staphylococcus aureus colonization in horses in Saskatchewan,Alberta, and British Columbia

This study estimated the prevalence of methicillin resistant Staphylococcus aureus (MRSA) in nasal swabs of 458 horses in western Canada. The rate of colonization was 1.3% ± 5.84% [95% confidence interval (CI)], a rate similar to those reported elsewhere. Colonization tended to be transient and seemed unrelated to stress or administration of antimicrobials. Five of the 6 isolates were Canadian epidemic MRSA-5, a human clone that appears to predominate in horses in North America. The other isolate was spa type 539 (t034), a sequence type 398 strain, and this is the first report of this clone in horses in North America. Surveillance is warranted because of the potential of MRSA to cause disease in horses and humans.     

Influence of eggs on the aroma composition of a sponge cake and on the aroma release in model studies on flavored sponge cakes

The use of solvent-assisted flavor evaporation extraction (SAFE) and purge and trap in Tenax allowed the identification of more than 100 volatile compounds in a sponge cake (SC-e). Gas chromatography-olfactometry (GC-O) of the SAFE extracts of crumb and crust were achieved in order to determine the most potent odorants of SC-e. The change in the traditional dough formulation of SC-e in which eggs were substituted by baking powder (SC-b) as the leavening agent produced important changes in some key aroma compounds. The release curves of some aroma compounds-some of them generated during baking and others added in the dough-were followed by cumulative headspace analysis. In the flavored SC-b, the aroma release curves showed a plateau after 15 min of purge, while the release increased proportionally with the purge time in the flavored SC-e. In general, except for some of the aroma compounds with the highest log P values, the rate of release of most of the added and generated aroma compounds was significantly influenced by the changes in the cake formulation. The higher rates of release found for the aroma compounds in SC-b could contribute to explain its rapid exhaustion of aroma compounds in the purge and trap experiments and might lead to poorer sensorial characteristics of this cake during storage.     

Effect of concentration and relative humidity on the transfer of alkan-2-ones through paper coated with wheat gluten

The transport properties of two methyl ketones, 2-heptanone and 2-nonanone, through a paper coated with a wheat gluten (WG) solution were studied as a function of aroma compound concentration differential and relative humidity. Whatever the conditions, coating improved the aroma barrier properties of the paper. Whereas permeability of 2-nonanone through WG coated paper was not affected by the concentration differential, a high concentration of 2-heptanone induced a permeability increase, which can be explained by a slight plasticization effect of this compound. The moisture content of the films markedly affected the barrier properties depending on the aroma compound. For 2-heptanone, the most polar compound, the increase of permeability with relative humidity was related to the increase of diffusivity and solubility coefficient of this compound. With 2-nonanone, permeability and diffusivity coefficients strongly decreased with the increase of moisture content. This decrease could be linked to the hindrance in diffusivity of the less polar compound induced by the presence of water molecules. The different behavior in permeation properties seems to be related to the hydrophobic nature of the aroma compound. At intermediate and high humidity levels, coated papers are found to have better aroma barrier properties than LDPE films.