Density‐dependent survival and recruitment in a long‐distance Palaearctic migrant,the Sand Martin Riparia riparia

Long‐term studies can provide powerful insights into the relative importance of different demographic and environmental factors determining avian population dynamics. Here we use 23 years of capture–mark–recapture data (1981–2003) to estimate recruitment and survival rates for a Sand Martin Riparia riparia population in Cheshire, NW England. Inter‐annual variation in recruitment and adult survival was positively related to rainfall in the sub‐Saharan wintering grounds, but unrelated to weather conditions on the breeding grounds. After allowing for the effects of African rainfall, both demographic rates were negatively density‐dependent: adult survival was related to the size of the western European Sand Martin population (probably reflecting competition for resources in the shared wintering grounds) while recruitment was related to the size of the local study population in Cheshire (potentially reflecting competition for nesting sites or food). Local population size was more sensitive to variation in adult survival than to variation in recruitment, and an increase in population size after 1995 was driven mainly by the impact of more favourable conditions in the African wintering grounds on survival rates of adults. Overwinter survival in this long‐distance Palaearctic migrant is determined partly by the amount of suitable wetland foraging habitat in the sub‐Saharan wintering grounds (which is limited by the extent of summer rainfall) and partly by the number of birds exploiting that habitat.     

Identifying potentially invasive non‐native marine and brackish water species for the Arabian Gulf and Sea of Oman

Invasive non‐native species (NNS) are internationally recognized as posing a serious threat to global biodiversity, economies and human health. The identification of invasive NNS is already established, those that may arrive in the future, their vectors and pathways of introduction and spread, and hotspots of invasion are important for a targeted approach to managing introductions and impacts at local, regional and global scales. The aim of this study was to identify which marine and brackish NNS are already present in marine systems of the northeastern Arabia area (Arabian Gulf and Sea of Oman) and of these which ones are potentially invasive, and which species have a high likelihood of being introduced in the future and negatively affect biodiversity. Overall, 136 NNS were identified, of which 56 are already present in the region and a further 80 were identified as likely to arrive in the future, including fish, tunicates, invertebrates, plants and protists. The Aquatic Species Invasiveness Screening Kit (AS‐ISK) was used to identify the risk of NNS being (or becoming) invasive within the region. Based on the AS‐ISK basic risk assessment (BRA) thresholds, 36 extant and 37 horizon species (53.7% of all species) were identified as high risk. When the impact of climate change on the overall assessment was considered, the combined risk score (BRA+CCA) increased for 38.2% of all species, suggesting higher risk under warmer conditions, including the highest‐risk horizon NNS the green crab Carcinus maenas, and the extant macro‐alga Hypnea musciformis. This is the first horizon‐scanning exercise for NNS in the region, thus providing a vital baseline for future management. The outcome of this study is the prioritization of NNS to inform decision‐making for the targeted monitoring and management in the region to prevent new bio‐invasions and to control existing species, including their potential for spread.     

Improvement of Coarse Sand Engineering Properties by Microbially Induced Calcite Precipitation

Abstract

This paper investigates the effectiveness of microbially induced calcite precipitation method in improving the strength and stiffness of coarse sands using treatments based on a four-phase percolation technique. An increase of biochemical treatment cycles was associated with increased deposition of calcium carbonate (CaCO₃) and consequently an increase in compressive strength. Furthermore, the bio-cemented coarse sand retained reasonable porosity and permeability, which should allow dissipation of pore water pressure if required. The results also establish a correlation between the strength gained and stiffness of the bio-cemented coarse sand with the increase in the amount of deposited CaCO₃, initial relative density and dry density. Scanning electron microscopy and electron dispersive spectroscopy analysis indicate that the inter-structure of the bio-cemented coarse sand tend to change in morphology based upon the number of biochemical treatments used.     

Differential regulation of cell volume and shape in confluent rat hepatocytes under hypertonic stress.

In confluent primary cultures of rat hepatocytes,hypertonic stress leads to cell shrinkage and activates non-selective cation channels as the main mechanism of regulatory cell volume increase. The process is found to employ the exocytotic insertion of channels into the plasma membrane and (in addition to PKC) PLC, tyrosine kinases and G proteins, but not PI 3-kinase are part of the signalling network. Furthermore, hypertonic stress leads to the formation of stress fibres and significantly alters the activity of RhoA, Rac and Cdc42. These latter effects, however, are likely to reflect the restoration of cell shape rather than the regulation of cell volume, both most probably converging at the level of focal adhesions and integrins.     

Comparative vasodilation of peroxynitrite and 3-morpholinosydnonimine.

Vasorelaxation mediated by peroxynitrite (ONOO-) and 3-morpholinosydnonimine (SIN-1) were investigated in isolated bovine intramammary arteries. Both ONOO- and SIN-1 relaxed U 46619-precontracted rings in a dose-dependent, endothelium-independent manner. Pretreatment with an adenylyl cyclase inhibitor, SQ 22536 [(9-tetrahydro-2-furyl)adenine], resulted in an enhanced ONOO--mediated relaxation, but did not modulate the response to SIN-1. ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), a potent and selective inhibitor of soluble guanylyl cyclase (sGC), did not significantly affect relaxant actions of ONOO-, but ODQ markedly attenuated SIN-1-elicited relaxation with a rightward shift in the dose-response curve and an unaltered maximal response. In the presence of carboxy-PTIO (2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide), a putative nitric oxide scavenger and ONOO- inactivator, the relaxant response to ONOO- was abolished, while relaxant actions of SIN-1 appeared to be unaffected. The results reveal a difference between ONOO- and SIN-1-mediated relaxation with regards to the role of the sGC and suggest that ONOO--evoked relaxation may not be associated with sGC activity, but rather depends on an sGC-independent mechanism triggered by ONOO- and/or NO itself. It also re-emphasizes that SIN-1 induces a vasorelaxant response, in part, via stimulation of sGC.     

The global trend in plant twining direction

Aim  To examine, at a global scale, patterns in the direction in which climbing plants twine. We tested three hypotheses: (1) that twining direction is determined randomly; (2) that twining direction is determined by apices following the apparent movement of the sun across the sky; and (3) that twining direction is determined by the Coriolis effect.
Location  Seventeen sites spanning nine countries, both hemispheres and 65° of latitude.
Methods  Twining direction was recorded for the first c . 100 stems encountered along transects through natural vegetation at each site.
Results  Ninety-two per cent of the 1485 twining stems we recorded grew in right-handed helices, i.e. they twined in an anticlockwise direction. This is significantly ( P < 0.001) different from random. The proportion of stems twining right-handedly (anticlockwise) was independent of both latitude ( P = 0.33) and hemisphere ( P = 0.63). These data are inconsistent with the idea that twining direction is determined by either the relative passage of the sun through the celestial sphere or by the Coriolis effect. Thus, we reject all three of our hypotheses.
Main conclusions  The predominance of right-handed helical growth in climbing plants cannot be explained by hypotheses attempting to link plant growth behaviour and global location. One alternative hypothesis for our findings is that the widespread phenomenon of anticlockwise twining arises as a function of microtubule orientation operating at a subcellular level.     

Association of Bartonella with the fleas (Siphonaptera) of rodents and bats using molecular techniques.

Bartonella spp. are putatively vector-borne bacterial agents of humans and animals. Fleas have been incriminated as vectors of Bartonella spp. and are suspected of transmitting Bartonella of rodents and bats, but some of these Bartonella spp. have not yet been directly detected in wild caught fleas. We report the molecular detection of Bartonella tribocorum, Bartonella vinsonii subsp. vinsonii, and two novel genotypes of Bartonella from the fleas Xenopsylla cheopis, Ctenophthalmus pseudagyrtes, Sternopsylla texanus, or Orchopeas howardi.     

Arylmethoxypyridines as novel, potent and orally active mGlu5 receptor antagonists

Optimisation of affinity, chemical stability, metabolic stability and solubility led from a chemically labile HTS hit 1 to mGlu5 receptor antagonists (24-26) with high affinity for the allosteric MPEP binding site, improved microsomal metabolic stability and anxiolytic-like activity in vivo as assessed by the Vogel conflict drinking test.     

Aziridine-2,3-dicarboxylate inhibitors targeting the major cysteine protease of Trypanosoma brucei as lead trypanocidal agents

The protozoan parasite Trypanosoma brucei causes Human African trypanosomiasis, which is fatal if left untreated. Due to the toxicity of currently used drugs and emerging drug resistance, there is an urgent need for novel therapies. The major trypanosome papain-like cysteine protease expressed by the parasite (e.g., rhodesain in T. b. rhodesiense) is considered an important target for the development of new trypanocidal drugs. Series of aziridine-2,3-dicarboxylate-based cysteine protease inhibitors have been tested, most of them inhibiting rhodesain in the low micromolar range. Among these, only dibenzyl aziridine-2,3-dicarboxylates display trypanocidal activity being equipotent to the drug eflornithine. The Leu-Pro-containing aziridinyl tripeptides 13a-f are the most promising as they are not cytotoxic to macrophages up to concentrations of 125microM.     

Physical and chemical interactions between aphids and plants

Aphids feed from sieve tubes deep inside the host plant. Therefore, aphids must be able to recognize their host plant(s) and to direct their stylets which must be long and thin enough to reach and puncture the sieve tubes at a particular site. Sieve tubes in angiosperms are longitudinal arrays of sieve element/companion cell modules which are highly sensitive to disturbance of any kind. The sieve tubes dispose of elaborate sealing mechanisms such as protein plugging and callose sealing which are triggered by a rise in calcium in the sieve tubes. Aphids seem to have developed a range of physical and chemical measures to limit the amount of calcium influx in response to stylet puncturing. Loss of sieve-element turgor pressure induced by stylet insertion is minimized by the minute stylet volume. Turgor-dependent Ca(2+) influx, possibly mediated by mechano sensitive Ca(2+) channels, must therefore be limited. The components of the sheath and watery saliva play a pivotal role in establishing the physical and chemical constraints on the rise of calcium. Most likely, sheath saliva prevents the influx of calcium from the apoplast by sealing the stylet puncture site while watery saliva may prevent plugging and sealing of sieve plates by potential interaction with SE sap ingredients.