Indirect effects of bottom fishing on the productivity of marine fish

One quarter of marine fish production is caught with bottom trawls and dredges on continental shelves around the world. Towed bottom‐fishing gears typically kill 20–50 per cent of the benthic invertebrates in their path, depending on gear type, substrate and vulnerability of particular taxa. Particularly vulnerable are epifaunal species, which stabilize the sediment and provide habitat for benthic invertebrates. To identify the habitats, fisheries or target species most likely to be affected, we review evidence of the indirect effects of bottom fishing on fish production. Recent studies have found differences in the diets of certain species in relation to bottom fishing intensity, thereby linking demersal fish to their benthic habitats at spatial scales of ~10 km. Bottom fishing affects diet composition and prey quality rather than the amount of prey consumed; scavenging of discarded by‐catch makes only a small contribution to yearly food intake. Flatfish may benefit from light trawling levels on sandy seabeds, while higher‐intensity trawling on more vulnerable habitats has a negative effect. Models suggest that reduction in the carrying capacity of habitats by bottom fishing could lead to lower equilibrium yield and a lower level of fishing mortality to obtain maximum yield. Trawling effort is patchily distributed – small fractions of fishing grounds are heavily fished, while large fractions are lightly fished or unfished. This patchiness, coupled with the foraging behaviour of demersal fish, may mitigate the indirect effects of bottom fishing on fish productivity. Current research attempts to scale up these localized effects to the population level.     

Compositional analysis of tubers from insect and virus resistant potato plants

Genetically modified potato plants that are resistant to the Colorado potato beetle, plus either the potato leaf roll virus or potato virus Y, have recently been commercialized. As part of the safety assessment for plants produced by modern biotechnology, the composition of the food/feed must be compared to that of the food/feed produced by an equivalent plant variety from a conventional source. The composition of important nutritional and antinutritional factors in tubers produced by virus- and insect-resistant potato plants were compared to tubers produced by conventional potato plants. Key nutritional, quality, and antinutritional components measured were total solids, vitamin C, dextrose, sucrose, soluble protein, and glycoalkaloids. Proximate analyses included fat, ash, calories, total protein, and crude fiber. Minor nutrients measured were vitamin B6, niacin, copper, magnesium, potassium, and amino acids. The results from these analyses confirm that tubers produced by insect- and virus-protected varieties are substantially equivalent to tubers produced by conventional potato varieties.     

Susceptibility of sheep to European bat lyssavirus type-1 and -2 infection: a clinical pathogenesis study

European bat lyssaviruses (EBLVs) have been known to cross the species barrier from their native bat host to other terrestrial mammals. In this study, we have confirmed EBLV-1 and EBLV-2 susceptibility in sheep (Ovis ammon) following intracranial and peripheral (intramuscular) inoculation. Notably, mild clinical disease was observed in those exposed to virus via the intramuscular route. Following the intramuscular challenge, 75% of the animals infected with EBLV-1 and 100% of those that were challenged with EBLV-2 developed clinical signs of rabies and then recovered during the 94-day observation period. Disease pathogenesis also varied substantially between the two viruses. Infection with EBLV-1 resulted in peracute clinical signs, which are suggestive of motor neuron involvement. Antibody induction was observed and substantial inflammatrory infiltrate in the brain. In contrast, more antigen was detected in the EBLV-2-infected sheep brains but less inflammatory infiltrate and no virus neutralising antibody was evident. The latter involved a more protracted disease that was behaviour orientated. A high infectious dose was required to establish EBLV infection under experimental conditions (> or =5.0 logs/ml) but the infectious dose in field cases remains unknown. These data confirm that sheep are susceptible to infection with EBLV but that there is variability in pathogenesis including neuroinvasiveness that varies with the route of infection. This study suggests that inter-species animal-to-animal transmission of a bat variant of rabies virus to a terrestrial mammal host may be limited, and may not always result in fatal encephalitis.     

The effect of pesticide combinations on laboratory rats. II. Modification of selected hematological parameters and blood glucose]

Reference is made to the first communication made under this heading. The haematological parameters did not undergo any visible change in response to the chosen experimental arrangement. Further studies should be undertaken, with the view to elucidating the possibility of bone marrow change. The blood glucose levels were strongly increased two hours from application of parathion-methyl, carbaryl/Lindan, and carbaryl/Lindan/parathion-methyl and strongly decreased 24 hours after application. Complementary experiments should cover chronic and subchronic situations.     

Characterization of a PCR‐based lymphocyte clonality assay as a complementary tool for the diagnosis of feline lymphoma

Differentiation between resident mature lymphocyte populations and small cell lymphoma cannot be made by cytological review alone and remains challenging in histopathological review. These cases warrant application of complementary tools like PCR‐based immunoglobulin (IG) and T‐cell receptor (TCR) clonality testing for confirmation. In this prospective study, diagnostic sensitivity and specificity of different primer sets for routine diagnosis of feline TCR gamma (TCRG) and complete IG heavy chain (IGH) gene rearrangements were assessed. Fine needle aspirates from 20 feline lymphoma cases and lymph node material from 10 cats without hematopoietic neoplasia were subjected to clonality testing. Feline lymphoma cell lines and previously confirmed patient material served as positive control. Detection limits for clonal populations within a polyclonal background was 90% for B‐cells and 50% for T‐cells. Diagnostic sensitivity and specificity of the clonality assay were 70% and 90%. Overall diagnostic accuracy was 77%, positive predictive value 93% and negative predictive value 60%.     

Syntheseaktivität und Grösse der Zellkerne von Phaseolus vulgaris nach Infektion mit Uromyces phaseoli typica

Zusammenfassung In rostinfizierten Bohnenblättern werden acht Tage nach der Infektion¹⁴C-Orotsäure und³H-Uridin in die Zellkerne von Wirt und Parasit eingebaut, wobei relativ hohe Aktivität in den Wirtskernen unter der Pustel gefunden wird. Vorbehandlungen mit Actinomycin D verhindert diesen Einbau zum grössten Teil. Die Durchmesser der Wirtskerne sind im Pustelbereich klein und nehmen nach aussen stetig zu; die Nucleolen sind dagegen im Bereich der Pusteln ebenso gross wie in 750–1000 Abstand vom Pustelrand, und im dazwischen liegenden Bereich kleiner. Unter den Pusteln vonUromyces phaseoli typica treten in grösserem Umfang Mitosen auf; die relative Zahl nimmt vom Pustelkern aus gegen das ungestörte Gewebe zu ab. Die Ergebnisse werden im Blick auf verschiedene Typen der Wirt-Parasit-Beziehung diskutiert.Orotic acid-¹⁴C and uridine-³H was applied to floating discs of tissue from main leaflets ofPhaseolus vulgaris infected withUromyces phaseoli. Label appeared not only in the nuclei of the host cells but also in the nuclei of actively growing hyphae of the rust, as shown by Tschen (1966). The label is accumulated by DNA-dependent RNA synthesis. Pretreatment with actinomycin D limits labelling to about 10%. The label is destroyed by treating the tissue with RNAse, not with DNAse.In sections of host tissues near the rust pustule, the activity was higher in host nuclei near the pustule. In this region there were many dividing nuclei. The nuclei are smaller directly below the pustule than in zones of tissue further away from the centre of infection. Cell divisions are most frequent on the 7th to 8th day after inoculation.The results contrast with those on wheat with rust and are considered as a stimulation of the host tissue in a progressed stage of host-parasite relationship; it depends on the density of infection. The results are consistent with observations of Yarwood and Cohen (1950) on hypertrophy of bean leaves with rust.Samenvatting Met orotzuur-¹⁴C, toegediend aan drijvende schijfjes van primaire bladeren vanPhaseolus vulgaris geïnoculeerd metUromyces phaseoli, is het niet slechts mogelijk de kernen van de waardplant te merken, maar zoals aangetoond door Tschen (1966) ook die van de actief groeiende hyphen van de roest.¹⁴C-accumulatie vindt plaats door van DNA afhankelijke RNA-synthese. Voorbehandeling met actinomycine D voorkomt de inbouw van¹⁴C voor ongeveer 90%. De substitutie wordt teniet gedaan door behandeling van het weefsel met RNAse, niet met DNAse.Coupes van het waardplantweefsel onder en rond het roest-sporehoopje geven een grotere activiteit in de waardplantkernen te zien dichtbij het sporehoopje. In deze omgeving zijn vele delende kernen te zien. Onder het sporehoopje zijn de kernen kleiner dan in de weefselgedeelten die verder van het infectiecentrum zijn verwijderd. Celdelingen vinden het meest plaats 7–8 dagen na de inoculatie.De resultaten, strijdig met waarnemingen aan door roest aangetaste tarwe, worden beschouwd als een activering van het waardplantweefsel in een vergevorderd stadium van de waardplant-parasiet-relatie, afhankelijk van de mate van infectie. Deze resultaten stemmen overeen met waarnemingen van Yarwood en Cohen (1950) betreffende hypertrofie bij door roest aangetaste bonebladeren.     

Experimental infection of rabbits (Oryctolagus cuniculus) with Brucella suis biovar 1 isolated from wild hares (Lepus europaeus)

Brucella suis biovar 1 is the causative agent of brucellosis in several domestic and wild animals and it is a common agent of human brucellosis. European hares (Lepus europaeus) have been shown to be infected by B. suis biovar 1 and the transmission to other animals has been suggested. In this work, experimental rabbits (Cuniculus orictolagus) were infected with B. suis biovar 1 isolated from wild hares. Infected rabbits showed high serological response in 2 weeks after discharge and typical granulomatous lesions (2mm diameter) were found in liver, spleen and kidneys after 50 days. B. suis biovar 1 was cultured from the lesion of the organs mentioned above as well as from urine, placenta and fetuses. These data suggest that hares are a potential source for horizontal transmission of B. suis biovar 1 to other mammalians.