Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis)

For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.     

The cucumber mosaic virus 1a protein regulates interactions between the 2b protein and ARGONAUTE 1 while maintaining the silencing suppressor activity of the 2b protein

The cucumber mosaic virus (CMV) 2b viral suppressor of RNA silencing (VSR) is a potent counter-defense and pathogenicity factor that inhibits antiviral silencing by titration of short double-stranded RNAs. It also disrupts microRNA-mediated regulation of host gene expression by binding ARGONAUTE 1 (AGO1). But in Arabidopsis thaliana complete inhibition of AGO1 is counterproductive to CMV since this triggers another layer of antiviral silencing mediated by AGO2, de-represses strong resistance against aphids (the insect vectors of CMV), and exacerbates symptoms. Using confocal laser scanning microscopy, bimolecular fluorescence complementation, and co-immunoprecipitation assays we found that the CMV 1a protein, a component of the viral replicase complex, regulates the 2b-AGO1 interaction. By binding 2b protein molecules and sequestering them in P-bodies, the 1a protein limits the proportion of 2b protein molecules available to bind AGO1, which ameliorates 2b-induced disease symptoms, and moderates induction of resistance to CMV and to its aphid vector. However, the 1a protein-2b protein interaction does not inhibit the ability of the 2b protein to inhibit silencing of reporter gene expression in agroinfiltration assays. The interaction between the CMV 1a and 2b proteins represents a novel regulatory system in which specific functions of a VSR are selectively modulated by another viral protein. The finding also provides a mechanism that explains how CMV, and possibly other viruses, modulates symptom induction and manipulates host-vector interactions.     

Consequences of thermal change on the myofibrillar ATPase of five freshwater teleosts

Myofibrillar ATPase activity was measured in the epaxial musculature of five freshwater species of fish acclimated to extremes of temperature within their tolerance ranges. Changes in the enzyme activity were apparent in carp, tench and roach, cold acclimated fish (10°C) having higher enzyme activity levels than hot acclimated fish (28°C). Such changes were not apparent in eels or brook trout. Alteration of the enzyme activity took less than 4 weeks, and was totally reversible. This suggests that seasonal adaptation to environmental temperatures is possible, thus maintaining locomotory efficiency.     

A small one-band paracentric inversion inv (4) (p15.3p16.3).

A neonate with aniridia was found to have a one band paracentric inversion of the short arm of chromosome 4. This was initially difficult to interpret on high resolution banding. The inversion was present in three generations of the family.     

Adaptive variation in sex determination in a crustacean, Gammarus duebeni

In some animals sex is determined after conception by environmental factors (environmental sex determination. ESD). In the amphipod Gammarus duebeni sex is reportedly determined by photoperiod: there is a higher proportion of males in broods reared under long-day than under short-day photoperiods. It has been proposed that this is an adaptive response to seasonal population dynamics. A test of the hypothesis would be to demonstrate changes in the degree to which sex is determined by the environment in populations from different latitudes with different dynamics. This study reports such a test. Environmental response is significantly less strong in a southern population with a long breeding season than in a northern one in which breeding is seasonally restricted. Moreover, the threshold of the ESD cue for male or female determination is not defined when the breeding season is weakly seasonal. There is a broad correlation between latitude (and hence breeding seasonality) and the strength of ESD response across a series of population studies. Similarities between the Gammarus system of sex determination and that of the Atlantic silverside Menidia menidia, a fish with thermal ESD, are discussed.