Y chromosome haplotype distribution of brown bears (Ursus arctos) in Northern Europe provides insight into population history and recovery

High‐resolution, male‐inherited Y‐chromosomal markers are a useful tool for population genetic analyses of wildlife species, but to date have only been applied in this context to relatively few species besides humans. Using nine Y‐chromosomal STRs and three Y‐chromosomal single nucleotide polymorphism markers (Y‐SNPs), we studied whether male gene flow was important for the recent recovery of the brown bear (Ursus arctos) in Northern Europe, where the species declined dramatically in numbers and geographical distribution during the last centuries but is expanding now. We found 36 haplotypes in 443 male extant brown bears from Sweden, Norway, Finland and northwestern Russia. In 14 individuals from southern Norway from 1780 to 1920, we found two Y chromosome haplotypes present in the extant population as well as four Y chromosome haplotypes not present among the modern samples. Our results suggested major differences in genetic connectivity, diversity and structure between the eastern and the western populations in Northern Europe. In the west, our results indicated that the recovered population originated from only four male lineages, displaying pronounced spatial structuring suggestive of large‐scale population size increase under limited male gene flow within the western subpopulation. In the east, we found a contrasting pattern, with high haplotype diversity and admixture. This first population genetic analysis of male brown bears shows conclusively that male gene flow was not the main force of population recovery.     

Freezing behaviour facilitates bioelectric crypsis in cuttlefish faced with predation risk

Cephalopods, and in particular the cuttlefish Sepia officinalis, are common models for studies of camouflage and predator avoidance behaviour. Preventing detection by predators is especially important to this group of animals, most of which are soft-bodied, lack physical defences, and are subject to both visually and non-visually mediated detection. Here, we report a novel cryptic mechanism in S. officinalis in which bioelectric cues are reduced via a behavioural freeze response to a predator stimulus. The reduction of bioelectric fields created by the freeze-simulating stimulus resulted in a possible decrease in shark predation risk by reducing detectability. The freeze response may also facilitate other non-visual cryptic mechanisms to lower predation risk from a wide range of predator types.     

Water discharge affects Atlantic salmon Salmo salar smolt production: a 27 year study in the River Orkla,Norway

A model that explains 48% of the annual variation in Atlantic salmon Salmo salar smolt production in the River Orkla, Norway, has been established. This variation could be explained by egg deposition, minimum daily discharge during the previous winter and minimum weekly discharge during the summer 3 years before smolt migration. All coefficients in the model were positive, which indicates that more eggs and higher minimum discharge levels during the winter before smolt migration and the summer after hatching benefit smolt production. Hence, when the spawning target of the river is reached, the minimum levels of river discharge, in both winter and summer, are the main bottlenecks for the parr survival, and hence for smolt production. The River Orkla was developed for hydropower production in the early 1980s by the construction of four reservoirs upstream of the river stretch accessible to S. salar. Although no water has been removed from the catchment, the dynamics of water flow has been altered, mainly by increasing discharges during winter and reducing spring floods. In spite of the higher than natural winter discharges, minimum winter discharge is still a determinant of smolt production. Hence, in regulated rivers, the maintenance of discharges to ensure that they are as high as possible during dry periods is an important means of securing high S. salar smolt production.     

The G157C mutation in the Escherichia coli sliding clamp specifically affects initiation of replication

Escherichia coli cells with a point mutation in the dnaN gene causing the amino acid change Gly157 to Cys, were found to underinitiate replication and grow with a reduced origin and DNA concentration. The mutant β clamp also caused excessive conversion of ATP-DnaA to ADP-DnaA. The DnaA protein was, however, not the element limiting initiation of replication. Overproduction of DnaA protein, which in wild-type cells leads to over-replication, had no effect in the dnaN(G157C) mutant. Origins already opened by DnaA seemed to remain open for a prolonged period, with a stage of initiation involving β clamp loading, presumably limiting the initiation process. The existence of opened origins led to a moderate SOS response. Lagging strand synthesis, which also requires loading of the β clamp, was apparently unaffected. The result indicates that some aspects of β clamp activity are specific to the origin. It is possible that the origin specific activities of β contribute to regulation of initiation frequency.     

Sheep prefer clean forage over forage contaminated with military explosives TNT, RDX and HMX

The common military explosives 2-methyl-1,3,5-trinitrobenzene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) are distributed in many military training areas, and are thus encountered by grazing animals. The aim of this study was to examine small ruminant's intake of forage contaminated with explosives. An indoor, experimental setup was used to determine if contamination of forage by these compounds affected intake by sheep. The results clearly demonstrate that contamination by any of the three explosives reduced forage intake in sheep; in order of increasing avoidance: RDX < TNT < HMX. The results are discussed in a risk assessment context.     

Emergence, spread, persistence and fade-out of sylvatic plague in Kazakhstan

Predicting the dynamics of zoonoses in wildlife is important not only for prevention of transmission to humans, but also for improving the general understanding of epidemiological processes. A large dataset on sylvatic plague in the Pre-Balkhash area of Kazakhstan (collected for surveillance purposes) provides a rare opportunity for detailed statistical modelling of an infectious disease. Previous work using these data has revealed a host abundance threshold for epizootics, and climatic influences on plague prevalence. Here, we present a model describing the local space-time dynamics of the disease at a spatial scale of 20 × 20 km(2) and a biannual temporal scale, distinguishing between invasion and persistence events. We used a Bayesian imputation method to account for uncertainties resulting from poor data in explanatory variables and response variables. Spatial autocorrelation in the data was accounted for in imputations and analyses through random effects. The results show (i) a clear effect of spatial transmission, (ii) a high probability of persistence compared with invasion, and (iii) a stronger influence of rodent abundance on invasion than on persistence. In particular, there was a substantial probability of persistence also at low host abundance.     

A chiton uses aragonite lenses to form images

Hundreds of ocelli are embedded in the dorsal shell plates of certain chitons. These ocelli each contain a pigment layer, retina, and lens, but it is unknown whether they provide chitons with spatial vision. It is also unclear whether chiton lenses are made from proteins, like nearly all biological lenses, or from some other material. Electron probe X-ray microanalysis and X-ray diffraction revealed that the chiton Acanthopleura granulata has the first aragonite lenses ever discovered. We found that these lenses allow A. granulata's ocelli to function as small camera eyes with an angular resolution of about 9°-12°. Animals responded to the sudden appearance of black, overhead circles with an angular size of 9°, but not to equivalent, uniform decreases in the downwelling irradiance. Our behavioral estimates of angular resolution were consistent with estimates derived from focal length and receptor spacing within the A. granulata eye. Behavioral trials further indicated that A. granulata's eyes provide the same angular resolution in both air and water. We propose that one of the two refractive indices of the birefringent chiton lens places a focused image on the retina in air, whereas the other does so in water.