Transmission of infectious salmon anaemia (ISA) through natural secretions and excretions from infected smolts of Atlantic salmon Salmo salar during their presymptomatic phase

Short-term (48 h) exposure of healthy Atlantic salmon Salmo salar L. smelts to infectious salmon anemia (ISA)-inoculated cohort smelts showed that the disease was transmitted with near 100% mortality from Day 7 post-inoculation and onwards. This is more than a week before the inoculated fish show any clinical signs and long before the typical petechial bleedings occur. A bloodborne transmission of the disease is therefore unlikely. Skin mucus, faeces, urine and blood, isolated from ISA-inoculated smelt, transmitted the disease to healthy cohort smelt with variable efficiency depending on how the inoculum was administered. All the sources were infectious and transmitted the disease with high efficiency when injected intraperitoneally (i.p.) into cohort smelt. After i.p. injection, skin mucus had somewhat lower infectivity than blood homogenates. Furthermore, in some experiments application of skin mucus to the gills was as efficient as i.p. injection for transmission of the disease. When introduced into the stomach none of the inocula caused ISA. Coprophagy thus seems to be ineffective in the transmission of TSA under laboratory conditions. Skin mucus from non-inoculated cohabitants exposed to ISA-inoculated smelts for 2 d transmitted the disease with close to 100% efficiency to healthy cohort smelts when injected i.p. This indicates that the infectious agent is waterborne and absorbed by the skin mucus rather than being secreted with the skin mucus. Since healthy smelts have an intact skin barrier, proximity to inoculation directly to the vascular bed seems unlikely. An ultrastructural study of 10 different organs, all in close proximity to the secretions/excretions, revealed that at early stages of the disease, the virus was exclusively found in the pillar cells and endocardial cells. This indicates that the gills are the most Likely port of entry of the virus. It also supports a causal relation between the observed virus and the disease

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Unexpected diversity of bioluminescence in planktonic worms

The vast majority of pelagic bioluminescent organisms emit a blue light with emission maxima (λmax) ranging from 450 to 490 nm. Among the known outliers, the tomopterids (Annelida: Polychaeta) are usually described as yellow-emitters (λmax = 565–570 nm) for which bioluminescence functions as a specific recognition signal. Here, we report the first data regarding the colours emitted by four different tomopterid species, Tomopteris pacifica, T. carpenteri, T. septentrionalis and T. planktonis. Surprisingly, T. planktonis is a blue-emitter (λmax = 450 nm). Our pharmacological results on T. planktonis support cholinergic control, as recently demonstrated in the yellow-emitter, T. helgolandica. Moreover, as revealed by epifluorescence microscopy, the light seems to be produced in both species from the same yellow-pigmented parapodial glands. Despite these similarities, tomopterids express an unexpected diversity of bioluminescent colour patterns. This leads us to reassess the ecological value of bioluminescence within this group

Isolation and Properties of the Luciferase Stored in the Ovary of the Scyphozoan Medusa Periphylla periphylla

Volume: 201Start Page: 339End Page: 34

Morphology and fluorescence of the parapodial light glands in Tomopteris helgolandica and allies (Phyllodocida: Tomopteridae)

The histology of putative light organs in the parapodia of five species of Tomopteris (pelagic annelids) is examined and compared using light, epifluorescence and scanning electron microscopy. The structural homology of rosette glands in the parapodial pinnae of the tail-bearing species T. helgolandica and T. pacifica, and hyaline glands of the tail-less species T. carpenteri, T. planktonis and T. septentrionalis is highlighted. However, the rosette glands point towards the ramus of the coelomic cavity inside the parapodia, whereas the hyaline glands point towards the surrounding water and penetrate the pinnal surface on the posterior side of the parapodia. Further, in order to assess the photogenic properties of rosette glands from T. helgolandica, we analysed the distribution and the temporal dynamics of their endogenous fluorescence in isolated parapodia in response to light emission induced by KCl and carbachol. The gradual extinction of bioluminescence was combined to the centrifugal spread of fluorescence from the core of the gland. We suggest this fluorescence to be produced by a “breakdown” product of the chemiluminescent reaction. Finally, both gland types probably evolved from a common light-emitting structure and differentiated along a functional and migrational axis extending from endocrine secretion close to the coelomic ramus to exocrine secretion close to the lateral margin of the pinna

Vertical distribution, behavior, chemical composition and metabolism of Stauroteuthis syrtensis (Octopoda: Cirrata) in the northwest Atlantic

The cirrate octopod Stauroteuthis syrtensis is a mesopelagic species commonly collected in the North Atlantic. Individuals were observed at depths >600 m and typically within 100 m of the bottom in three ~900 m deep canyons indenting the southern edge of Georges Bank. When first sighted, most octopods were floating passively with their webbed arms gathered into a small ball. When disturbed, they expanded their webs to form a ‘balloon’ shape, swam slowly by sculling their fins, pulsed their webs like medusae and, in some cases, streamlined their arms and webs and moved away smoothly by rapidly sculling their fins. The bodies of 9 octopods comprised 92 to 95% water, with tissue containing 9 to 22% carbon (C) and 2 to 4% nitrogen (N). These values were similar to those reported for medusae and ctenophores. Oxygen (O2) consumption rates of 4.6 to 25.8 µmol O2 g–1 C h–1 were within ranges reported for medusae, ctenophores, and deep-water cephalopods. The stomachs of S. syrtensis, dissected immediately after capture, contained only the calanoid copepod Calanus finmarchicus. Calculations indicated that S. syrtensis need 1.3 to 30.1 ind. d–1 of C. finmarchicus to meet their measured metabolic demand. Excretion rates (0.3 to 12.4 µg NH4+ g–1 C h–1 and 0.06 to 4.83 µg PO43– g–1 C h–1) were at least an order of magnitude lower than rates reported for other octopods or gelatinous zooplankters. O:N ratios (11 to 366) suggested that S. syrtensis catabolized lipids, which may be supplied by C. finmarchicus. Vertical distribution, relatively torpid behavior and low metabolic rates characterized S. syrtensis as a benthopelagic and relatively passive predator on copepods