Comparative Genomics Identifies Candidate Genes for Infectious Salmon Anemia (ISA) Resistance in Atlantic Salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>)

Infectious salmon anemia (ISA) has been described as the hoof and mouth disease of salmon farming. ISA is caused by a lethal and highly communicable virus, which can have a major impact on salmon aquaculture, as demonstrated by an outbreak in Chile in 2007. A quantitative trait locus (QTL) for ISA resistance has been mapped to three microsatellite markers on linkage group (LG) 8 (Chr 15) on the Atlantic salmon genetic map. We identified bacterial artificial chromosome (BAC) clones and three fingerprint contigs from the Atlantic salmon physical map that contains these markers. We made use of the extensive BAC end sequence database to extend these contigs by chromosome walking and identified additional two markers in this region. The BAC end sequences were used to search for conserved synteny between this segment of LG8 and the fish genomes that have been sequenced. An examination of the genes in the syntenic segments of the tetraodon and medaka genomes identified candidates for association with ISA resistance in Atlantic salmon based on differential expression profiles from ISA challenges or on the putative biological functions of the proteins they encode. One gene in particular, HIV-EP2/MBP-2, caught our attention as it may influence the expression of several genes that have been implicated in the response to infection by infectious salmon anemia virus (ISAV). Therefore, we suggest that HIV-EP2/MBP-2 is a very strong candidate for the gene associated with the ISAV resistance QTL in Atlantic salmon and is worthy of further study.     

What a Plant Sounds Like: The Statistics of Vegetation Echoes as Received by Echolocating Bats

A critical step on the way to understanding a sensory system is the analysis of the input it receives. In this work we examine the statistics of natural complex echoes, focusing on vegetation echoes. Vegetation echoes constitute a major part of the sensory world of more than 800 species of echolocating bats and play an important role in several of their daily tasks. Our statistical analysis is based on a large collection of plant echoes acquired by a biomimetic sonar system. We explore the relation between the physical world (the structure of the plant) and the characteristics of its echo. Finally, we complete the story by analyzing the effect of the sensory processing of both the echolocation and the auditory systems on the echoes and interpret them in the light of information maximization. The echoes of all different plant species we examined share a surprisingly robust pattern that was also reproduced by a simple Poisson model of the spatial reflector arrangement. The fine differences observed between the echoes of different plant species can be explained by the spatial characteristics of the plants. The bat's emitted signal enhances the most informative spatial frequency range where the species-specific information is large. The auditory system filtering affects the echoes in a similar way, thus enhancing the most informative spatial frequency range even more. These findings suggest how the bat's sensory system could have evolved to deal with complex natural echoes.     

Transfer of defined numbers of chloroplasts into albino protoplasts using an improved subprotoplast/protoplast microfusion procedure: Transfer of only two chloroplasts leads to variegated progeny

Summary A procedure is described by which it is possible to perform controlled microfusion of microscopically selected protoplast fusion partners with high efficiencies. The procedure is applied to fusion of Nicotiana tabacum (line 92V37, N. undulata cytoplasm) plastid albino protoplasts as a recipient and spontaneously formed subprotoplasts of green N. tabacum (line SRI) as donor. Products of individual electrofusion events are cloned via single cell nurse culture and the derived cell lines are analysed for the occurrence of variegated or green regenerating shoots, which are indicative of the establishment of the transferred organelles in the cell progeny. The plastid population in green regenerants recovered after the transfer of only two chloroplasts was demonstrated to have originated from the donor subprotoplast organelles by restriction analysis of total DNA using a plastome-specific probe.Some of the results described in this paper have been presented as posters at scientific meetings (Eigel and Koop 1989b; Eigel and Koop 1990)     

Preservation effects on wet weight, dry weight, and ash-free dry weight biomass estimates of four common estuarine macro-invertebrates: no difference between ethanol and formalin

Two preservative treatments traditionally used in aquatic sciences, formalin (4%) and ethanol (70%), were compared for their effects on biomass estimations. The effects of both preservatives on wet weight, dry weight, and ash-free dry weight were determined for samples preserved for 10, 21, and 90 days. The effects were studied in four different macrofauna species commonly found in German estuaries: Heteromastus filiformis (Capitellidae, Polychaeta), Hediste diversicolor (Nereididae, Polychaeta), Corophium sp. (Amphipoda, Crustaceae), and Gammarus spp. (Amphipoda, Crustacea). The biomass estimates of preserved samples were compared with those of unpreserved samples. In all four species the loss in wet weight, dry weight, and ash-free dry weight was most pronounced within the first 10 days, and an additional weight loss was recorded between days 10 and 21. However, there was no further loss in weight for samples kept for as long as 90 days in the preservatives. In general, crustaceans exhibited higher weight loss than polychaetes, and smaller species (H. filiformis and Corophium sp.) showed higher weight loss and a higher variability than larger species. As our main result, significant differences between the two preservative treatments did never occur. Our results contradict some earlier investigations on this matter where formalin has been reported to be superior to alcoholic preservatives because weight loss was less pronounced than in ethanol. Factors affecting biomass estimates are discussed and we conclude that, for the macrofauna groups tested, the use of the toxic formalin solution is not justified when the major intent is biomass estimation.     

Physiological indicators of fitness in benthic invertebrates: a useful measure for ecological health assessment and experimental ecology

Physiological indicators of fitness present a measure of an organism’s response to a changing environment. An analysis of how these organisms allocate and store their energy resources provides an understanding of how they cope with such environmental changes. Each individual has to balance the investment necessary to acquire a certain resource with the energy gained by it. This trade-off can be monitored by measuring several physiological indicators of fitness such as energy storage components, metabolic state or RNA/DNA ratio. Because environmental adaptations and ecological strategies of survival are best examined within the natural environment, our research has to rely on the physiological indicators that are easily accessible in the field. The physiological indicators presented here are significant for an individual’s fitness and in turn lead to reliable values in field-collected samples. Based on our own expertise and on a literature survey, the physiological relevance of the presented indicators is explained. Furthermore, some consideration to the analytical methods used to obtain the physiological indicators is given, and possible errors introduced at the sampling site and during the laboratory procedures are discussed. This work demonstrates that the integration of ecological and physiological expertise facilitates the identification of future ecological problems much earlier than separate approaches of both disciplines alone.     

Windkanalversuche zur Abh?ngigkeit der Fluggeschwindigkeit einer Wei?scheitelammer (Zonotrichia leucophrys) von der Windgeschwindigkeit

Zusammenfassung In einem Windkanal wurde für eine Weißscheitelammer (Zonotrichia leucophrys) die Abhängigkeit der Fluggeschwindigkeit in Luft (v_F) und der Geschwindigkeit über Grund (v_G) von der Windgeschwindigkeit (v_W) bestimmt. Das Versuchstier flog bei Windstille mit einer mittleren v_F von 5,15 m/sec. Bei zunehmenden Gegenwinden wurde v_F so stark erhöht, daß sich v_G nur langsam verringerte. Bei v_W=16,2 m/sec wurde noch v_G=1,4 m/sec erreicht. Bei zunehmenden Rückenwinden wurde v_F immer mehr herabgesetzt, so daß sich v_G kaum erhöhte. Bei v_W=–7 m/sec flog das Versuchstier sogar langsam rückwärts in der Luft, um seine Manövrierfähigkeit im engen Kanal zu erhalten. Der Gesamtgeschwindigkeitsbereich für v_F lag zwischen –0,9 bis 17,6 m/sec.

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Flight speed of a White-Crowned Sparrow in a Wind Tunnel at different Wind Speeds

Summary In an experimental wind tunnel air speed (v_F) and ground speed (v_G) of a White-Crowned Sparrow (Zonotrichia leucophrys) were measured as a function of wind speed (v_W). The bird had an average v_F of 5,15 m/sec in still air. With rising head winds it increased its v_F. At v_W=16,2 m/sec v_F was 17,6 m/sec and v_G was still 1,4 m/sec. With tailwinds it tended to maintain constant v_G and lowered v_F. At v_W=–7 m/sec it even flew slowly backward in the air in order to maintain its maneuvrability. The complete speed range for v_F was from –0,9 to + 17,6 m/sec.

     

Numerous chromosomal polymorphisms in a natural population of rice rats (Oryzomys, Cricetidae)

Based on G- and C-banded karyotypes of 10 specimens of rice rats, genus Oryzomys (a member of the macconnelli-capito complex but species identification is not possible at this time) from a single isolated population, we found at least nine different centric fusion/fission polymorphisms. No two individuals examined had the same karyotype. Polymorphic variation appears to be stable in the population and not the result of hybridization, human disturbance, or non-specific mutagenic agents. Among the 14 largest chromosomes, polymorphism is restricted to fusion/fission rearrangements. Among the smaller ones, there is polymorphism in the total number of euchromatic arms, which indicates that rearrangements other than fusion/fission exist within our sample. Data from these rice rats document the presence of a greater number of chromosomal polymorphisms within a single, natural population than have previously been reported in a higher vertebrate.     

Ueber den abbau von riboflavin in pflanzlichen zellsuspensionskulturen

The degradation of (2-¹⁴C)-riboflavin was investigated in plant cell suspension cultures of Cicer arietinum, Glycine max, Phaseolus aureus, Nicotiana glauca, Petroselinum crispum und Triticum aestivum. All cultures showed degradation of the isoalloxazine system with decreasing magnitude in the order shown above. Riboflavin is not degraded via lumichrome. (2-¹⁴C)lumichrome was not degraded but rather excreted from the cells into the nutrient medium after conversion to a water soluble compound. Riboflavin, but not lumichrome, was incorporated into the coenzymes FMN and FAD.     

Microculture and Electrofusion of Defined Protoplasts of the Moss Funaria hygrometrica

Protoplasts isolated from protonemata of Funaria hygrometrica wild type and developmentally abnormal mutants were individually selected and cultured in microdroplets of defined, unconditioned culture medium. Up to 60 % of the microcultured wild type protoplasts regenerated whole plants after 4 weeks. Electrofusion in different combinations of defined protoplast pairs of wild type and mutated forms was performed. The products derived from one-to-one electric field induced fusion were efficiently microcultured and somatic hybrids were regenerated.