Animal movements in fire‐prone landscapes

Movement is a trait of fundamental importance in ecosystems subject to frequent disturbances, such as fire‐prone ecosystems. Despite this, the role of movement in facilitating responses to fire has received little attention. Herein, we consider how animal movement interacts with fire history to shape species distributions. We consider how fire affects movement between habitat patches of differing fire histories that occur across a range of spatial and temporal scales, from daily foraging bouts to infrequent dispersal events, and annual migrations. We review animal movements in response to the immediate and abrupt impacts of fire, and the longer‐term successional changes that fires set in train. We discuss how the novel threats of altered fire regimes, landscape fragmentation, and invasive species result in suboptimal movements that drive populations downwards. We then outline the types of data needed to study animal movements in relation to fire and novel threats, to hasten the integration of movement ecology and fire ecology. We conclude by outlining a research agenda for the integration of movement ecology and fire ecology by identifying key research questions that emerge from our synthesis of animal movements in fire‐prone ecosystems.     

Integrin α8β1 regulates adhesion,migration and proliferation of human intestinal crypt cells via a predominant RhoA/ROCK‐dependent mechanism

Background. Integrins are transmembrane αβ heterodimer receptors that function as structural and functional bridges between the cytoskeleton and ECM (extracellular matrix) molecules. The RGD (arginine‐glycine‐aspartate tripeptide motif)‐dependent integrin α8β1 has been shown to be involved in various cell functions in neuronal and mesenchymal‐derived cell types. Its role in epithelial cells remains unknown. Results. Integrin α8β1 was found to be expressed in the crypt cell population of the human intestine but was absent from differentiating and mature epithelial cells of the villus. The function of α8β1 in epithelial crypt cells was investigated at the cellular level using normal HIECs (human intestinal epithelial cells). Specific knockdown of α8 subunit expression using an shRNA (small‐hairpin RNA) approach showed that α8β1 plays important roles in RGD‐dependent cell adhesion, migration and proliferation via a RhoA/ROCK (Rho‐associated kinase)‐dependent mechanism as demonstrated by active RhoA quantification and pharmacological inhibition of ROCK. Moreover, loss of α8β1, through RhoA/ROCK, impairs FA (focal adhesion) complex integrity as demonstrated by faulty vinculin recruitment. Conclusions. Integrin α8β1 is expressed in epithelial cells. In intestinal crypt cells, α8β1 is closely involved in the regulation of adhesion, migration and cell proliferation via a predominant RhoA/ROCK‐dependent mechanism. These results suggest an important role for this integrin in intestinal crypt cell homoeostasis.     

Climate,copepods and seabirds in the boreal Northeast Atlantic – current state and future outlook

The boreal Northeast Atlantic is strongly affected by current climate change, and large shifts in abundance and distribution of many organisms have been observed, including the dominant copepod Calanus finmarchicus, which supports the grazing food web and thus many fish populations. At the same time, large‐scale declines have been observed in many piscivorous seabirds, which depend on abundant small pelagic fish. Here, we combine predictions from a niche model of C. finmarchicus with long‐term data on seabird breeding success to link trophic levels. The niche model shows that environmental suitability for C. finmarchicus has declined in southern areas with large breeding seabird populations (e.g. the North Sea), and predicts that this decline is likely to spread northwards during the 21st century to affect populations in Iceland and the Faroes. In a North Sea colony, breeding success of three common piscivorous seabird species [black‐legged kittiwake (Rissa tridactyla), common guillemot (Uria aalge) and Atlantic puffin (Fratercula arctica)] was strongly positively correlated with local environmental suitability for C. finmarchicus, whereas this was not the case at a more northerly colony in west Norway. Large seabird populations seem only to occur where C. finmarchicus is abundant, and northward distributional shifts of common boreal seabirds are therefore expected over the coming decades. Whether or not population size can be maintained depends on the dispersal ability and inclination of these colonial breeders, and on the carrying capacity of more northerly areas in a warmer climate.     

Molecular cloning,characterization and comparison of bile salt hydrolases from Lactobacillus johnsonii PF01

Aims

To clone, characterize and compare the bile salt hydrolase (BSH) genes of Lactobacillus johnsonii PF01.

Methods and Results

The BSH genes were amplified by polymerase chain reaction (PCR) using specific oligonucleotide primers, and the products were inserted into the pET21b expression vector. Escherichia coli BLR (DE3) cells were transformed with pET21b vectors containing the BSH genes and induced using 0·1 mmol l^?1 isopropylthiolgalactopyranoside. The overexpressed BSH enzymes were purified using a nickel–nitrilotriacetic acid (Ni²⁺‐NTA) agarose column and their activities characterized. BSH A hydrolysed tauro‐conjugated bile salts optimally at pH 5·0 and 55°C, whereas BSH C hydrolysed glyco‐conjugated bile salts optimally at pH 5·0 and 70°C. The enzymes had no preferential activities towards a specific cholyl moiety.

Conclusions

BSH enzymes vary in their substrate specificities and characteristics to broaden its activity. Despite the lack of conservation in their putative substrate‐binding sites, these remain functional through motif conservation.

Significance and Impact of the Study

This is to our knowledge the first report of isolation of BSH enzymes from a single strain, showing hydrolase activity towards either glyco‐conjugated or tauro‐conjugated bile salts. Future structural homology studies and site‐directed mutagenesis of sites associated with substrate specificity may elucidate specificities of BSH enzymes.     

Identification and Functional Validation of a 5′ Upstream Regulatory Sequence in the Human Tyrosinase Gene Homologous to the Locus Control Region of the Mouse Tyrosinase Gene

Comparison analysis of the sequences of the mouse and human genomes has proven a powerful approach in identifying functional regulatory elements within the non‐coding regions that are conserved through evolution between homologous mammalian loci. Here, we applied computational analysis to identify regions of homology in the 5′ upstream sequences of the human tyrosinase gene, similar to the locus control region (LCR) of the mouse tyrosinase gene, located at ?15 kb. We detected several stretches of homology within the first 30 kb 5′ tyrosinase gene upstream sequences of both species that include the proximal promoter sequences, the genomic region surrounding the mouse LCR, and further upstream segments. We cloned and sequenced a 5′ upstream regulatory sequence found between ?8 and ?10 kb of the human tyrosinase locus (termed h5′URS) homologous to the mouse LCR sequences, and confirmed the presence of putative binding sites at ?9 kb, homologous to those described in the mouse tyrosinase LCR core. Finally, we functionally validated the presence of a tissue‐specific enhancer in the h5′URS by transient transfection analysis in human and mouse cells, as compared with homologous DNA sequences from the mouse tyrosinase locus. Future experiments in cells and transgenic animals will help us to understand the in vivo relevance of this newly described h5′URS sequence as a potentially important regulatory element for the correct expression of the human tyrosinase gene.     

Recent climate changes interact with stand structure and management to determine changes in tree carbon stocks in Spanish forests

Most temperate forests are accumulating carbon (C) and may continue to do so in the near future. However, the situation may be different in water‐limited ecosystems, where the potentially positive effects of C and N fertilization and rising temperatures interact with water availability. In this study, we use the extensive network of plots of two consecutive Spanish national forest inventories to identify the factors that determine the spatial variation of the C stock change, growth, and mortality rate of forests in Peninsular Spain (below‐ and aboveground). We fitted general linear models to assess the response of C stock change and its components to the spatial variability of climate (in terms of water availability), forest structure (tree density and C stock), previous forest management, and the recent warming trend. Our results show that undisturbed forests in Peninsular Spain are accumulating C at a rate of ~1.4 Mg C ha^?1 yr^?1, and that forest structural variables are the main determinants of forest growth and C stock change. Water availability was positively related to growth and C accumulation. On the other hand, recent warming has reduced growth rate and C accumulation, especially in wet areas. Spatial variation in mortality (in terms of C loss) was mostly driven by differences in growth rate across plots, and was consistent with ‘natural’, self‐thinning dynamics related to the recent abandonment of forest management over large areas of Spain, with the consequent increase in tree density and competition. Interestingly, the negative effect of warming on forest C accumulation disappears if only managed stands are considered, emphasizing the potential of forest management to mitigate the effects of climate change. However, the effect of forest management was weak and, in some cases, not significant, implying the need of further research on its impact.     

Therapeutic potential of α,β‐thujone through metabolic reprogramming and caspase‐dependent apoptosis in ovarian cancer cells

The therapeutic potential of α,β‐thujone, a functional compound found in many medicinal plants of the Cupressaceae, Asteraceae, and Lamiaceae families, has been demonstrated, including in inflammation and cancers. However, its pharmacological functions and mechanisms of action in ovarian cancer remain unclear. We investigated the anticancer properties of α,β‐thujone in ES2 and OV90 human ovarian cancer cells and its effect on sensitization to cisplatin. α,β‐thujone inhibited cancer cell proliferation and induced cell death through caspase‐dependent intrinsic apoptotic pathways. Moreover, α,β‐thujone‐mediated endoplasmic reticulum stress was associated with the loss of mitochondrial functions and altered metabolic landscape of ovarian cancer cells. α,β‐Thujone attenuated blood vessel formation in transgenic zebrafish, implying it has significant antiangiogenic potential. In addition, α,β‐thujone sensitized ovarian cancer cells to cisplatin, causing synergistic pharmacological effects. Collectively, our results suggest that α,β‐thujone has therapeutic potential in human ovarian cancer and functions via regulating multiple intracellular stress‐associated metabolic reprogramming and caspase‐dependent apoptotic pathways.