Die Wirksamkeit von Isomeren des Hexachlorcyclohexans gegen holzzerstörende Käferlarven

Zusammenfassung Es wurde die Giftwirknng der α-, β-, γ- und δ-Isomeren des Hexachlorcyclohexans gegenüber Eilarven des Hausbockk?fers (Hylotrupes bajulus L.) und mittelgro?en Larven des Gew?hnlichen Nagek?fers (Anobium punctatum De Geer) bestimmt. Gegenüber beiden Larvenarten erwies sich das λ-Isomere erwartnngsgema? als der bei weitem wirksamste Stoff. Danach folgt, je nach den Versuchsbedingungen um den Faktor 10 bis 20100 schlechter, unerwartet das α-Isomere. Das δ- und noch ausgepr?gter das β-Isomere sind bedeutend weniger wirksam. Der Unterschied gegenüber dem γ-Isomeren liegt für Hausbock-Eilarven in der Gro?enordnung von 1500 und 80000; für Anobien-Larven ist er mit < 500 geringer. Das Ergebnis mit dem α-Isomeren ist beachtenswert.

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Summary The toxicity of the α-, β-, γ-, and δ-isomers of hexachlorocyclohexane towards egg-larvae of the Old House Borer (Hylotrupes bajulus L.) and medium-sized larvae of the Common Furniture Beetle (Anobium punctatum De Geer) was determined. As was to be expected, the γ-,isomer proved by far most effective against both species of larvae. Then, unexpectedly, the α-isomer follows, inferior by the factor 10 to 2000 according to the testing conditions. The δ- and, even more distinctly, the β-isomer show a considerably smaller efficiency. The difference to the γ-isomer amounts to a relation of 1500 and 80000 withHylotrupes egg-larvae; it is smaller (<500) withAnobium larvae. The result obtained with the α-isomer is remarkable.

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Résumé L'effet toxique des α-, β-, γ-, et δ-isomères du chlorocyclo-hexane contre des ovule-larves desHylotrupes bajulus L. et contre des larves de moyenne grandeur del'Anobium punctatum De Geer fut déterminé. Comme supposé, le γ-isomère était bien la plus efficace substance. Inattendu, le α-isomère, suit, selon les conditions d'essai plus mauvaises du facteur 10 à 2000. Le δ-isomè re et plus distinctement le β-isomère sont efficaces beaucoup moins. La différence entre ces derniers et les γ-isomères est de 1500 et 80000 pour des larves deHylotrupes bajulus L.; elle e'st moindre (< 500) pour des larves del'Anobium punctatum De Geer.

     

PROGRESS ON IMPROVING AGRICULTURAL NITROGEN USE EFFICIENCY: UK-CHINA VIRTUAL JOINT CENTERS ON NITROGEN AGRONOM

● Virtual joint centers on N agronomy were established between UK and China. ● Key themes were improving NUE for fertilizers, utilizing livestock manures, and soil health. ● Improved management practices and technologies were identified and assessed. ● Fertilizer emissions and improved manure management are key targets for mitigation. Two virtual joint centers for nitrogen agronomy were established between the UK and China to facilitate collaborative research aimed at improving nitrogen use efficiency (NUE) in agricultural production systems and reducing losses of reactive N to the environment. Major focus areas were improving fertilizer NUE, use of livestock manures, soil health, and policy development and knowledge exchange. Improvements to fertilizer NUE included attention to application rate in the context of yield potential and economic considerations and the potential of improved practices including enhanced efficiency fertilizers, plastic film mulching and cropping design. Improved utilization of livestock manures requires knowledge of the available nutrient content, appropriate manure processing technologies and integrated nutrient management practices. Soil carbon, acidification and biodiversity were considered as important aspects of soil health. Both centers identified a range of potential actions that could be taken to improve N management, and the research conducted has highlighted the importance of developing a systems-level approach to assessing improvement in the overall efficiency of N management and avoiding unintended secondary effects from individual interventions. Within this context, the management of fertilizer emissions and livestock manure at the farm and regional scales appear to be particularly important targets for mitigation.     

Characteristics of monoclonal antibodies against Piscirickettsia salmonis

A panel of 28 monoclonal antibodies against Piscirickettsia salmonis was produced using a purified fraction of the bacterium. To determine their specificity to the pathogen, the antibodies were assayed by ELISA and indirect immunofluorescence microscopy. Six monoclonal antibodies were selected based on their strong reaction against P. salmonis and absence of cross-reactivity with other common fish pathogens. Western blot analysis showed that the antibodies reacted to several antigens of P. salmonis . Immunofluorescence assays revealed that these antibodies reacted with the same specificity to different isolates of P. salmonis obtained from the south of Chile. This panel of monoclonal antibodies represents an important tool to develop simple, rapid, sensitive and highly specific methods for the detection of the pathogen and diagnosis of the disease.     

Panagrellus redivivus mass produced on solid media as live food for Litopenaeus vannamei larvae

The free‐living soil nematode Panagrellus redivivus is well known to be an excellent food source for first feeding fish larvae. It represents an alternative to the highly expensive Artemia, which is commonly used. The lack of a proper method for mass production of P. redivivus has prevented its wider use in commercial hatcheries. A new cultivation method allows the production of a sufficient quantity of nematodes to deliver a standardized and permanently available live food of high quality, throughout the larval rearing period. In two experiments – carried out at the Centro de Investigación en Alimentación y Desarrollo, Mexico – several feeding regimes were established to prove the quality of the mass produced P. redivivus for larvae of Litopenaeus vannamei, the Pacific white shrimp. Two different nematode treatments were compared with a no‐feed group and a control group that was fed with Artemia. All treatments had an additional algal co‐feed and were run in five replicates. Panagrellus redivivus was cultured on two different media (wheat/corn flour and oat flour) to compare these for their suitability as high‐quality live food for the larvae. Shrimp fed nematodes grown on wheat/corn medium reached the postlarval stage earlier than those from other treatments. The nematode treatments showed promising results; however, further research is needed on the development of improved culture media or enrichment methods to further increase the nutritional value of P. redivivus.     

Ion levels in the gastrointestinal tract content and plasma of four teleosts with different feeding habits

The levels of various ions (Na⁺, Cl⁻, Ca²⁺, Mg²⁺, K⁺) in the fluid phase of the gastrointestinal contents and of the plasma were determined in four teleosts with different feeding habits: traira (Hoplias malabaricus), hassar (Hoplosternum littorale), silver catfish (Rhamdia quelen), and grass carp (Ctenopharyngodon idella). The results showed that most ionic levels in the fluid phase of the gastrointestinal tract seem to be affected by feeding habit and that these levels can be different from those found in the plasma. In practical terms, these results suggest that ionic levels of the gastrointestinal contents should be considered when preparing solutions for studies of intestinal absorption in fishes.     

Influence of feeding ratio and size on susceptibility to microsporidial gill disease caused by Loma salmonae in rainbow trout, Oncorhynchus mykiss (Walbaum)

Two trials were designed to quantify the effect of feeding ratio and fish size on the cohabitation transmission of Loma salmonae, the causative agent of microsporidial gill disease (MGD) in salmonids, Oncorhynchus spp. To evaluate the effect of feeding ratio on disease onset, groups of 45 rainbow trout, O. mykiss (Walbaum) (RBT), were fed daily at 1% (low), 2% (medium) or 4% (high) of the fish biomass in the tank. There were three tanks at each feeding level: two tanks were exposed to the pathogen and one was a control. For the second objective, 300 RBT were separated into seven tanks so that the weight classifications were small (17-23 g), medium (32-38 g) and large (57-63 g). Each size class was done in duplicate with one control tank containing medium-sized fish. Separately for each trial, on day 0 post-exposure (PE) five highly infectious RBT were added to each tank (not including the control tanks) to begin the cohabitation exposure period. Beginning on day 21 PE and continuing biweekly until days 70 and 77 PE for the feeding and fish size trials, respectively, each fish was evaluated for visible branchial xenomas to determine disease onset time. Using survival analysis, the survival curves for the low, medium and high feedings were not significantly different from each other. However, there were significant differences amongst the small, medium and large weight classes in the size trial. The median numbers of days to the development of branchial xenomas was 31, 38 and 42 for small, medium and large size fish, respectively. On any given day, a medium or large sized fish had a hazard ratio for developing branchial xenomas of 0.66 and 0.63, respectively, compared with a small fish. In addition to host species and host strain differences, fish size is now considered a host risk factor for the development of MGD.     

Production of Induced Secondary Metabolites by a Co-Culture of Sponge-Associated Actinomycetes,Actinokineospora sp. EG49 and Nocardiopsis sp. RV163

Two sponge-derived actinomycetes, Actinokineospora sp. EG49 and Nocardiopsis sp. RV163, were grown in co-culture and the presence of induced metabolites monitored by ¹H NMR. Ten known compounds, including angucycline, diketopiperazine and β-carboline derivatives 1–10, were isolated from the EtOAc extracts of Actinokineospora sp. EG49 and Nocardiopsis sp. RV163. Co-cultivation of Actinokineospora sp. EG49 and Nocardiopsis sp. RV163 induced the biosynthesis of three natural products that were not detected in the single culture of either microorganism, namely N-(2-hydroxyphenyl)-acetamide (11), 1,6-dihydroxyphenazine (12) and 5a,6,11a,12-tetrahydro-5a,11a-dimethyl[1,4]benzoxazino[3,2-b][1,4]benzoxazine (13a). When tested for biological activity against a range of bacteria and parasites, only the phenazine 12 was active against Bacillus sp. P25, Trypanosoma brucei and interestingly, against Actinokineospora sp. EG49. These findings highlight the co-cultivation approach as an effective strategy to access the bioactive secondary metabolites hidden in the genomes of marine actinomycetes.     

Metabolomic Tools for Secondary Metabolite Discovery from Marine Microbial Symbionts

Marine invertebrate-associated symbiotic bacteria produce a plethora of novel secondary metabolites which may be structurally unique with interesting pharmacological properties. Selection of strains usually relies on literature searching, genetic screening and bioactivity results, often without considering the chemical novelty and abundance of secondary metabolites being produced by the microorganism until the time-consuming bioassay-guided isolation stages. To fast track the selection process, metabolomic tools were used to aid strain selection by investigating differences in the chemical profiles of 77 bacterial extracts isolated from cold water marine invertebrates from Orkney, Scotland using liquid chromatography-high resolution mass spectrometry (LC-HRMS) and nuclear magnetic resonance (NMR) spectroscopy. Following mass spectrometric analysis and dereplication using an Excel macro developed in-house, principal component analysis (PCA) was employed to differentiate the bacterial strains based on their chemical profiles. NMR ¹H and correlation spectroscopy (COSY) were also employed to obtain a chemical fingerprint of each bacterial strain and to confirm the presence of functional groups and spin systems. These results were then combined with taxonomic identification and bioassay screening data to identify three bacterial strains, namely Bacillus sp. 4117, Rhodococcus sp. ZS402 and Vibrio splendidus strain LGP32, to prioritize for scale-up based on their chemically interesting secondary metabolomes, established through dereplication and interesting bioactivities, determined from bioassay screening.     

Evidence for long‐term spatial displacement of breeding and pupping harbour seals by shellfish aquaculture over three decades

• 1. Shellfish mariculture is increasing worldwide and often occurs adjacent to marine mammal breeding and feeding habitat. To better understand breeding pinniped vulnerability to potential shellfish mariculture disturbance and displacement effects in a US National Park, potential mechanisms were explored that may affect the proportion of harbour seals (Phoca vitulina) selecting high quality haul‐out sites near shellfish aquaculture within a large colony, and overall seal utilization of that colony in relation to other regional colonies.
• 2. Seal haul‐out sites isolated from the mainland (no predator access) had higher pup:adult ratios, indicating they are generally more important for pupping. Short‐term human disturbance did not have a significant effect on spatial use, but rather spatial use was pre‐determined by general sandbar isolation. Using multiple competing hypothesis and an information‐theoretic approach, it was found that within the estuary, after removing effects of El Niño, the proportion of seals (total seals and pups only) hauled out near mariculture sites was 8 ± 2% lower during years of higher oyster harvest. Annual oyster harvest was used as a measure of aquaculture activity that could result in direct disturbance or indirect displacement of harbour seals.
• 3. At the regional scale, oyster harvest, seal counts at a nearby colony, and loss of a major haul‐out site within the estuary, best explained pup and total seal use compared with the region. Regional population size, short‐term human disturbance rate, and other factors were not important. Concurrent with higher oyster harvest, the proportion of regional seals using the estuary declined by 7 ± 2% for seal pups (–65 ± 18 total pups), and 5 ± 2% for total counts ( ? 192 ± 58 total seals). These findings (both within the estuary and at the regional scale) were essentially identical whether modelling oyster harvest as either a continuous or categorical (low/high) variable and when using either frequentist or Bayesian statistical analyses.
• 4. Marine reserves set aside for wildlife may be less effective when the highest quality breeding and pupping sites are adjacent to regular aquaculture activities. These effects may not be detectable until additional natural variation lowers the quality of nearby habitats. Published in 2011. This article is a US Government work and is in the public domain in the USA.

     

Digestion and Assimilation of the Free-living Nematode Panagrellus redivivus Fed to First Feeding Coregonid Larvae: Evidence from Histological and Isotopic Studies

The free-living nematode Panagrellus redivivus is a potential source of live food for first feeding fish. The digestion and assimilation of nematodes by larval fish were investigated with the aid of a histological and stable isotope approach. Larvae of whitefish Coregonus lavaretus were reared for 8 d with nematodes and compared with an unfed control. Nematodes were readily ingested by 3-d-old larvae. Different stages of nematode digestion could be observed in transverse sections of fish larvae sampled on Day 6 at regular intervals after feeding. Nematodes were produced on corn medium. In this way nematodes with a stable carbon isotope signature clearly different from the isotopic pattern of the fish larvae could be obtained. Stable carbon isotope signatures for lipids and lipid-free matter of fish larvae sampled on Days 2 and 8 after first feeding were clearly influenced by the stable isotopic pattern of the nematodes. The high acceptance of the nematodes by Coregonus lavaretus larvae and the early onset of digestion and nutrient retention positively confirm the potential of PanagreUus redivivus as a live food for first feeding fish larvae.