Movement behaviour of large female yellow European eel (Anguilla anguilla L.) in a freshwater polder area

Due to a recruitment decline of more than 90% in 30 years, the European eel (Anguilla anguilla L.) has been classified by IUCN as critically endangered. Although the species has been studied intensively to obtain knowledge to improve management, studies about the resident yellow stage are relatively scarce. In this study, 52 large female yellow eels were tagged with acoustic transmitters in a Belgian polder system and tracked by a network of 23 automatic listening stations. We studied both circadian and seasonal movement patterns and the effect of environmental variables on these patterns. Large female yellow eels were most active at night in late summer and early autumn. A generalised linear mixed model showed that their movement is only slightly influenced by environmental variables. Moreover, as yellow eels show high site fidelity (i.e., the majority was detected only in the habitat type of their catch‐release location), they do not encounter many human‐induced connectivity problems in polder systems, which makes these systems highly suitable as eel growth habitat. These results can contribute to an effective eel management regarding habitat protection and restoration.     

Movement patterns of adult pike (Esox lucius L.) in a Belgian lowland river

Northern pike, Esox lucius, needs different habitats to survive and reproduce and thus depends on the availability and accessibility of these habitats. To efficiently manage pike, information is needed on its spatial and temporal patterns of migration. In this study, we investigated the occurrence of adult pike migration and which environmental variables influenced migration. From December 2010, we followed 15 pike for 1 year by use of radio telemetry in the River Yser, a typical lowland river characterised by anthropogenic impacts such as artificial embankments. Pike migrated most in February and March, which could indicate they frequented spawning habitat in this period. Four environmental variables significantly affected pike migration, ranging from the location where pike were observed (strongest effect), over water temperature and flow to diel water temperature change (weakest effect). The relation between migration and the location where pike were observed could demonstrate that pike preferred specific regions in the river. Increasing water temperature triggered migration for both sexes, and males started migrating at lower temperatures than females, which suggests that males start migrating earlier. This was the only substantial difference observed between male and female pike migration. The results suggest that migration was inhibited by high flow, as no migration was observed at high flow. River managers can use this information to efficiently manage their pike populations, for example, by removing or temporarily opening hydraulic structures like valves, weirs and sluices. This may facilitate access to suitable habitats at moments pike needs these habitats to fulfil its life cycle.     

A reassessment of the electrophoretic mobility of high molecular weight glutenin subunits of wheat

The high molecular weight subunits of wheat glutenin (HMW-GS) are important for bread-making quality. Their composition is routinely identified by Tris-glycine SDS-PAGE after reduction of glutenin disulfide bonds. However, the relation between their molecular weight and, hence, their primary structure, and their mobility in Tris-glycine SDS-PAGE has proven to be ambiguous. We demonstrate a Bis-Tris SDS-PAGE procedure with a neutral, instead of alkaline, pH in the gel and running buffers. In this method commonly occurring HMW-GS from wheat migrated in the order 5 > 2 ≈ 3 > 1 > 6 ≈ 2* > 7 > 8 > 9 > 12 > 10, which is different from the order obtained in the Tris-glycine system. HMW-GS were identified by N-terminal sequencing after isolation with RP-HPLC. Protein sequences of HMW-GS were further confirmed by LC-MS/MS analyses of chymotryptic peptides after comparing the MS data to amino acid sequences in protein databases. The numbers of amino acids of HMW-GS reflected well the mobility order in Bis-Tris SDS-PAGE. The results indicate that Bis-Tris SDS-PAGE may not only be used to identify HMW-GS, but also to estimate the length of their polypeptide chain, as such avoiding previously observed anomalies in migration order.     

β-Elimination reactions and formation of covalent cross-links in gliadin during heating at alkaline pH

The aim of this study was to increase insight into gluten polymerisation. While previous research on this topic focused on disulfide (SS) bonds, the present paper focuses on cross-links based on dehydro-protein formation through β-elimination reactions. Gliadin, the monomeric fraction of gluten containing no free sulfhydryl (SH) groups, was heated for 120 min at pH 8.0 and 130 °C, and cross-link formation was evaluated by determining extractability in sodium dodecyl sulfate containing buffer, reaction products of β-elimination reactions, and cross-links involving the latter. Heating decreased gliadin extractability. Reduction of SS bonds increased extractability of heated gliadin, but did not restore it to that of non-heated gliadin, suggesting contribution of both SS and non-SS bonds to gliadin cross-linking. Decreased SS levels and the presence of dehydroalanine and SH groups in heated gliadin samples indicated cleavage of SS bonds by β-elimination reactions. Some of the formed free SH groups were then involved in oxidation and/or SH–SS interchange reactions leading to intermolecular SS bonds. In addition, amino acid analysis revealed formation of an irreversible non-SS cross-link between dehydroalanine and the free SH group of cysteine, namely lanthionine. In conclusion, non-SS bonds may well contribute to the gluten network under specified reaction conditions.     

Identification of isopeptide bonds in heat-treated wheat gluten peptides

Results in this paper confirm heat-induced isopeptide bond formation in wheat gluten. Heating (24 h, 130 °C) of wheat gluten [moisture content 7.4%] decreased its extractability in sodium dodecyl sulfate containing buffer (pH 6.8), even after reduction of disulfide (SS) bonds. Thus, both SS bonds and non-SS bonds were responsible for the extractability loss. Cross-links of the lysinoalanine and lanthionine type were not present in the heated samples, but heat treatment reduced levels of available amino groups. Heating of purified and alkylated high molecular weight glutenin subunits (HMW-GS) under similar conditions also resulted in extractability loss, demonstrating that cross-linking did not solely depend on the availability of cysteine or cystine. These observations indicated that heat treatment had induced isopeptide bond formation, resulting in larger and unextractable molecules. Heating HMW-GS lysine- and glutamine-containing peptides induced the formation of isopeptide bonds, thereby supporting the above hypothesis. The level of isopeptide bond formation increased with heating time.     

Effects of extracorporeal shock wave therapy and radial pressure wave therapy on elasticity and microstructure of equine cortical bone

OBJECTIVE: To measure changes in the modulus of elasticity (E) and describe histologic findings after extracorporeal shock wave therapy and radial pressure wave therapy on equine cortical bone specimens. SAMPLE POPULATION: 16 bone specimens from the proximodorsal cortex of an equine third metacarpal or metatarsal bone. PROCEDURE: Baseline E was determined by the density (p) and unidirectional ultrasound transmission velocity (C) of each specimen according to the equation E = pC2. Eight specimens were treated with 500 pulses of 0.15 mJ/mm2 of extracorporeal shock wave therapy, and 8 specimens were treated with 500 pulses of 0.16 mJ/mm2of radial pressure wave therapy. After treatment, C was determined again. Four treatment sessions resulted in 2,000 pulses and 5 C measurements. The p of each sample was measured again. Mean post-treatment E was calculated for each group. Nondecalcified sections of all specimens were stained with toluidine blue or basic fuchsin for histologic evaluation. RESULTS: Overall treatment group effect was not significant for C or E. Final E was not different from baseline values for extracorporeal shock wave therapy and radial pressure wave therapy. No histologic changes could be attributed to either treatment modality. CONCLUSIONS AND CLINICAL RELEVANCE: Extracorporeal shock wave therapy and radial pressure wave therapy did not affect the material properties of equine bone at the energy and pulse values used in this study.     

Bilateral ovarian adenocarcinoma in a mare causing haemoperitoneum and colic

Abstract

CASE HISTORY: A 13-year-old Thoroughbred mare was presented with a history of mild colic over 3 days. This colic had acutely exacerbated and was unresponsive to analgesic treatment, and was referred to Massey University Veterinary Teaching Hospital.

CLINICAL FINDINGS: On examination the heart rate was 100 beats per minute, and mucous membranes were pale and tacky. A large mass was detected on transrectal palpation in the caudal abdomen to the left of midline. Explorative laparotomy revealed severe haemoperitoneum and several masses that were associated with the reproductive tract. The mare was then subject to euthanasia. On post-mortem examination, adjacent and attached to each ovary were soft, lobulated dark red masses up to 200 mm in diameter. Similar masses were present in the omentum and on the peritoneal surface of the diaphragm and the serosa of the spleen and liver. Histopathology revealed that the neoplastic component of the masses comprised proliferating cuboidal to columnar cells forming disorganised acini and cords separated by dense collagenous stroma. Immunohistochemistry showed the neoplastic cells were positive for cytokeratin AE1/AE3 and vimentin, but negative for cytokeratin 7 and inhibin α.

DIAGNOSIS: Bilateral ovarian adenocarcinoma with transcoelomic metastasis and terminal decompensation due to rupture of a neoplastic mass and consequent haemoperitoneum.

CLINICAL RELEVANCE: To the authors' knowledge, bilateral ovarian adenocarcinoma has not been previously reported in a horse. Ovarian adenocarcinoma should be considered when horses present with haemoperitoneum and colic. Further research is required on the immunohistochemical differentiation of adenocarcinoma of ovarian and intestinal origin in the horse.     

A decision support system to simulate and compare silvicultural scenarios for pure even-aged larch stands

In sustained forest management, it is particularly useful to test the adequacy of various silvicultural scenarios, but decision-making is also becoming increasingly complex because forest managers have to simultaneously meet several different objectives in response to society demands. In order to help forest managers make appropriate choices in silvicultural systems, we propose a SDSS (Silvicultural Decision Support System) that applies to pure and even-aged larch stands (Larix sp.) in lowland areas where site conditions are similar to those encountered in Southern Belgium. Its main purpose is (i) to predict the influence of silvicultural treatments on stand evolution and (ii) assist forest managers in comparing different scenarios with respect to predefined goals. This SDSS consists in three modules designed to elaborate silvicultural scenarios involving (i) stand growth prediction and thinning simulation; (ii) assessment of indicators selected to define the scenarios referring to wood production, financial, technico-economic and ecological components, tree stability and wood quality; and (iii) comparison of the scenarios on the basis of the set of previously assessed indicators (multi-criteria analysis). User-friendly “MGC_Larch” software helps managers to formulate, evaluate and compare different silvicultural scenarios for larch.     

Disaggregating ecosystem services and disservices in the cultural landscapes of southwestern Ethiopia: a study of rural perceptions

Context

Cultural landscapes provide essential ecosystem services to local communities, especially in poor rural settings. However, potentially negative impacts of ecosystems—or disservices—remain inadequately understood. Similarly, how benefit–cost outcomes differ within communities is unclear, but potentially important for cultural landscape management.

Objectives

Here we investigated whether distinct forest ecosystem service–disservice outcomes emerge within local communities. We aimed to characterize groups of community members according to service–disservice outcomes, and assessed their attitudes towards the forest.

Methods

We interviewed 150 rural households in southwestern Ethiopia about locally relevant ecosystem services (provisioning services) and disservices (wildlife impacts). Households were grouped based on their ecosystem service–disservice profiles through hierarchical clustering. We used linear models to assess differences between groups in geographic and socioeconomic characteristics, as well as attitudes toward the forest.

Results

We identified three groups with distinct ecosystem service–disservice profiles. Half of the households fell into a “lose–lose” profile (low benefits, high costs), while fewer had “lose–escape” (low benefits, low costs) and “win–lose” (high benefits, high costs) profiles. Location relative to forest and altitude explained differences between the “lose–escape” profile and other households. Socioeconomic factors were also important. “Win–lose” households appeared to be wealthier and had better forest use rights compared to “lose–lose” households. Attitudes towards the forest did not differ between profiles.

Conclusions

Our study demonstrates the importance of disaggregating both ecosystem services and disservices, instead of assuming that communities receive benefits and costs homogenously. To manage cultural landscapes sustainably, such heterogeneity must be acknowledged and better understood.

     

Effect of food matrix and pH on the volatilization of bases (TVB) in packed north Atlantic gray shrimp (Crangon crangon): volatile bases in MAP fishery products

The total volatile basic nitrogen fraction (TVB-N) is often used as a quality parameter in the fish industry to assess spoilage. This parameter often leads to discussions between producers and retailers when it comes to defining clear limits of acceptability for modified atmosphere (MA) packed fish and fishery products. Suggested product limits (mg N/100 g fish) do not always correlate with the presence of off-odors. Gray shrimp are an economic valuable, very perishable niche product, where the TVB-N fraction plays an important role considering its shelf life. This research focuses on the effect of a shrimp matrix and its pH on the volatilization of these formed bases, revealing the relationship between concentrations in the fishery product and the concentrations of these bases present in the headspace of the packed product. Especially, the pH of the product, which is lowered when fishery products are packed under a carbon dioxide enriched atmosphere, appeared to have an immense effect on the volatilization of these bases. The effect of the fish matrix itself is established by means of calculated equilibration constants (dimensionless) being 2.13×10(-4)±0.38×10(-4) for trimethylamine, 6.34×10(-5)±1.71×10(-5) for dimethylamine, and 2.58×10(-5)±0.49×10(-5) for ammonia. Comparison of these constants with the equilibration constants of an aqueous solution indicated the retention of these bases in the product. This article provides not only the important insights for the interpretation of TVB-N values in modified atmosphere packaged gray shrimp but also the methodology to extend these findings to other fish and fishery products.