A new malaria vector in Africa: Predicting the expansion range of Anopheles stephensi and identifying the urban populations at risk.

In 2012, an unusual outbreak of urban malaria was reported from Djibouti City in the Horn of Africa and increasingly severe outbreaks have been reported annually ever since. Subsequent investigations discovered the presence of an Asian mosquito species; Anopheles stephensi, a species known to thrive in urban environments. Since that first report, An. stephensi has been identified in Ethiopia and Sudan, and this worrying development has prompted the World Health Organization (WHO) to publish a vector alert calling for active mosquito surveillance in the region. Using an up-to-date database of published locational records for An. stephensi across its full range (Asia, Arabian Peninsula, Horn of Africa) and a set of spatial models that identify the environmental conditions that characterize a species' preferred habitat, we provide evidence-based maps predicting the possible locations across Africa where An. stephensi could establish if allowed to spread unchecked. Unsurprisingly, due to this species' close association with man-made habitats, our maps predict a high probability of presence within many urban cities across Africa where our estimates suggest that over 126 million people reside. Our results strongly support the WHO's call for surveillance and targeted vector control and provide a basis for the prioritization of surveillance.

Identifying drivers of forest resilience in long-term records from the Neotropics.

Here, we use 30 long-term, high-resolution palaeoecological records from Mexico, Central and South America to address two hypotheses regarding possible drivers of resilience in tropical forests as measured in terms of recovery rates from previous disturbances. First, we hypothesize that faster recovery rates are associated with regions of higher biodiversity, as suggested by the insurance hypothesis. And second, that resilience is due to intrinsic abiotic factors that are location specific, thus regions presently displaying resilience in terms of persistence to current climatic disturbances should also show higher recovery rates in the past. To test these hypotheses, we applied a threshold approach to identify past disturbances to forests within each sequence. We then compared the recovery rates to these events with pollen richness before the event. We also compared recovery rates of each site with a measure of present resilience in the region as demonstrated by measuring global vegetation persistence to climatic perturbations using satellite imagery. Preliminary results indeed show a positive relationship between pre-disturbance taxonomic richness and faster recovery rates. However, there is less evidence to support the concept that resilience is intrinsic to a region; patterns of resilience apparent in ecosystems presently are not necessarily conservative through time.

The global distribution of plants used by humans.

Plants sustain human life. Understanding geographic patterns of the diversity of species used by people is thus essential for the sustainable management of plant resources. Here, we investigate the global distribution of 35,687 utilized plant species spanning 10 use categories (e.g., food, medicine, material). Our findings indicate general concordance between utilized and total plant diversity, supporting the potential for simultaneously conserving species diversity and its contributions to people. Although Indigenous lands across Mesoamerica, the Horn of Africa, and Southern Asia harbor a disproportionate diversity of utilized plants, the incidence of protected areas is negatively correlated with utilized species richness. Finding mechanisms to preserve areas containing concentrations of utilized plants and traditional knowledge must become a priority for the implementation of the Kunming-Montreal Global Biodiversity Framework.

Quantification of UV-B flux through time using UV-B-absorbing compounds contained in fossil Pinus sporopollenin.

UV-B radiation currently represents c. 1.5% of incoming solar radiation. However, significant changes are known to have occurred in the amount of incoming radiation both on recent and on geological timescales. Until now it has not been possible to reconstruct a detailed measure of UV-B radiation beyond c. 150 yr ago. Here, we studied the suitability of fossil Pinus spp. pollen to record variations in UV-B flux through time. In view of the large size of the grain and its long fossil history, we hypothesized that this grain could provide a good proxy for recording past variations in UV-B flux. Two key objectives were addressed: to determine whether there was, similar to other studied species, a clear relationship between UV-B-absorbing compounds in the sporopollenin of extant pollen and the magnitude of UV-B radiation to which it had been exposed; and to determine whether these compounds could be extracted from a small enough sample size of fossil pollen to make reconstruction of a continuous record through time a realistic prospect. Preliminary results indicate the excellent potential of this species for providing a quantitative record of UV-B through time. Using this technique, we present the first record of UV-B flux during the last 9500 yr from a site near Bergen, Norway.

Conformation and function of the N-linked glycan in the adhesion domain of human CD2.

The adhesion domain of human CD2 bears a single N-linked carbohydrate. The solution structure of a fragment of CD2 containing the covalently bound high-mannose N-glycan [-(N-acetylglucosamine)2-(mannose)5-8] was solved by nuclear magnetic resonance. The stem and two of three branches of the carbohydrate structure are well defined and the mobility of proximal glycan residues is restricted. Mutagenesis of all residues in the vicinity of the glycan suggests that the glycan is not a component of the CD2-CD58 interface; rather, the carbohydrate stabilizes the protein fold by counterbalancing an unfavorable clustering of five positive charges centered about lysine-61 of CD2.

Sea lice treatments on salmon farms have no adverse effects on zooplankton communities: a case study.

The long-term effects of the sea lice treatment products Excis and Slice on zooplankton communities in a Scottish sea loch were investigated at a commercially operating salmon farm over 31 months. Cypermethrin and emamectin benzoate are the active ingredients in Excis and Slice respectively, which are widely used to control ectoparasitic sea lice on farmed salmon. Excis and Slice treatments did not cause basin-wide effects on the zooplankton community. For both formulations, no adverse affects on zooplankton were detected, instead observed changes in zooplankton abundance and community composition displayed natural seasonal cycles of abundance. Water column concentrations of cypermethrin and emamectin benzoate following sea lice treatments at the fish farm were predicted using models. Cypermethrin concentrations of 3000 ng/l were predicted for short periods immediately after each cage treatment assuming no particle adhesion. The 3-h and 24-h Environmental Quality Standards (EQS) were exceeded for 10 h and 32 h respectively on the second day when five cages were treated. However, cypermethrin concentrations higher than 0.5 ng/l (24-h EQS) were predicted to occur over <2% of the total basin area on each treatment day. The 3-h EQS (16 ng/l) was exceeded in <0.3% of the basin on each treatment day. The concentration of soluble emamectin benzoate present in the water column was predicted from modelled deposition footprints and sediment concentrations to be of order 10(-3) ng/l. Predicted concentrations of both chemicals were generally lower than those causing toxicity to copepods in previous laboratory studies and further support the results of this field study that environmental concentrations of Excis and Slice do not adversely impact zooplankton communities.

Hormonal effects of tamoxifen in oligospermic men.

The hormonal effects of tamoxifen (10 mg daily for 6 months) have been studied in nine men with oligospermia. Basal concentrations of serum LH (1-7 +/- 0-1 (S.E.M.) i.u./l) increased to a maximum of 4-1 +/- 1-3 i.u./l (P less than 0-001) after 6 months, and FSH rose from 4-9 +/- 1-0 to a maximum of 7-7 +/- 1-3 i.u./l after 4 months of treatment (P less than 0-01). The response to luteinizing hormone releasing hormone (LH-RH) was studied at monthly intervals. Sums of increments of serum LH increased from 35 +/- 4 to 92 +/- 17 i.u./l at 4 months (P less than 0-001) and of FSH from 14 +/- 3-4 to 23 +/- 3-5 i.u./l at 4 months (P less than 0-01). Basal serum androgens rose from 25 +/- 2-7 to 38 +/- 2-4 nmol/l after 4 months of treatment (P less than 0-05), and serum oestradiol-17beta increased from 185 +/- 25 to 631 +/- 90 pmol/l by 6 months (P less than 0-001). No significant changes occurred in sperm counts. Five normal men acted as controls: they were given tamoxifen for 1 week. No significant changes were observed in serum LH, FSH or release of these hormones following administration of LH-RH. Serum androgens and oestrogens however, increased significantly by day 4 of treatment (P less than 0-05).

The use of Stokes Raman scattering in time correlated single photon counting: application to the fluorescence lifetime of tyrosinate.

The decay kinetics of the tyrosinate form of tyrosine in aqueous solution, pH 11, were investigated by time correlated single photon counting using laser excitation. The lifetime of the single exponential decay was 30.5 +/- 0.2 ps. Stokes Raman scattering was used to determine the instrument response function and the advantages of this approach over the conventional Rayleigh scattering method are discussed.

Holocene biomass burning and global dynamics of the carbon cycle.

Fire regimes have changed during the Holocene due to changes in climate, vegetation, and in human practices. Here, we hypothesise that changes in fire regime may have affected the global CO2 concentration in the atmosphere through the Holocene. Our data are based on quantitative reconstructions of biomass burning deduced from stratified charcoal records from Europe, and South-, Central- and North America, and Oceania to test the fire-carbon release hypothesis. In Europe the significant increase of fire activity is dated approximately 6000 cal. yr ago. In north-eastern North America burning activity was greatest before 7500 years ago, very low between 7500-3000 years, and has been increasing since 3000 years ago. In tropical America, the pattern is more complex and apparently latitudinally zonal. Maximum burning occurred in the southern Amazon basin and in Central America during the middle Holocene, and during the last 2000 years in the northern Amazon basin. In Oceania, biomass burning has decreased since a maximum 5000 years ago. Biomass burning has broadly increased in the Northern and Southern hemispheres throughout the second half of the Holocene associated with changes in climate and human practices. Global fire indices parallel the increase of atmospheric CO2 concentration recorded in Antarctic ice cores. Future issues on carbon dynamics relatively to biomass burning are discussed to improve the quantitative reconstructions.

Determining the response of African biota to climate change: using the past to model the future.

Prediction of biotic responses to future climate change in tropical Africa tends to be based on two modelling approaches: bioclimatic species envelope models and dynamic vegetation models. Another complementary but underused approach is to examine biotic responses to similar climatic changes in the past as evidenced in fossil and historical records. This paper reviews these records and highlights the information that they provide in terms of understanding the local- and regional-scale responses of African vegetation to future climate change. A key point that emerges is that a move to warmer and wetter conditions in the past resulted in a large increase in biomass and a range distribution of woody plants up to 400-500 km north of its present location, the so-called greening of the Sahara. By contrast, a transition to warmer and drier conditions resulted in a reduction in woody vegetation in many regions and an increase in grass/savanna-dominated landscapes. The rapid rate of climate warming coming into the current interglacial resulted in a dramatic increase in community turnover, but there is little evidence for widespread extinctions. However, huge variation in biotic response in both space and time is apparent with, in some cases, totally different responses to the same climatic driver. This highlights the importance of local features such as soils, topography and also internal biotic factors in determining responses and resilience of the African biota to climate change, information that is difficult to obtain from modelling but is abundant in palaeoecological records.

Biodiversity baselines, thresholds and resilience: testing predictions and assumptions using palaeoecological data.

Fossil records are replete with examples of long-term biotic responses to past climate change. One particularly useful set of records are those preserved in lake and marine sediments, recording both climate changes and corresponding biotic responses. Recently there has been increasing focus on the need for conservation of ecological and evolutionary processes in the face of climate change. We review key areas where palaeoecological archives contribute to this conservation goal, namely: (i) determination of rates and nature of biodiversity response to climate change; (ii) climate processes responsible for ecological thresholds; (iii) identification of ecological resilience to climate change; and (iv) management of novel ecosystems. We stress the importance of long-term palaeoecological data in fully understanding contemporary and future biotic responses.

What is natural? The need for a long-term perspective in biodiversity conservation.

Ecosystems change in response to factors such as climate variability, invasions, and wildfires. Most records used to assess such change are based on short-term ecological data or satellite imagery spanning only a few decades. In many instances it is impossible to disentangle natural variability from other, potentially significant trends in these records, partly because of their short time scale. We summarize recent studies that show how paleoecological records can be used to provide a longer temporal perspective to address specific conservation issues relating to biological invasions, wildfires, climate change, and determination of natural variability. The use of such records can reduce much of the uncertainty surrounding the question of what is "natural" and thereby start to provide important guidance for long-term management and conservation.

Interaction with model membrane systems induces secondary structure in amino-terminal fragments of parathyroid hormone related protein.

The secondary structure of amino terminal fragments of human parathyroid hormone related protein (PTHrP) in aqueous solution, in trifluoroethanol solution and in the presence of model membrane systems has been studied by circular dichroism (CD) spectroscopy. Far-UV CD spectra of PTHrP 1-40, 1-34 amide, 7-34 amide and 1-16 are consistent with a predominantly unordered structure. Addition of trifluoroethanol stabilized alpha-helical structure in the 1-34 amide and 7-34 amide peptides. The effect reached a plateau at a trifluoroethanol concentration of approximately 40%, and a helix content of some 23 residues was determined. PTHrP 1-34 amide interacted with palmitoyloleoylphosphatidyl serine vesicles and exhibited an increased alpha-helix content of approximately 12 helical residues. Similar results were observed for monomyristoyllecithin micelles and sodium dodecyl sulfate micelles. No interaction with dimyristoylphosphatidylcholine vesicles was detected by CD. The ability to bind to palmitoyloleoylphosphotidyl serine vesicles was also a feature of the 1-40 and 7-34 fragments, while the 1-16 fragment was apparently unaffected by interaction with this model membrane system. These results indicate that the conformational properties of the functionally significant amino terminal 1-34 region of PTHrP parallel those reported for the corresponding, but largely nonhomologous, region of parathyroid hormone. Conformational similarities may account for the ability of PTHrP to mimic the functional properties of parathyroid hormone.

Broccoli and phyletic gradualism.

The Evolutionary Biology of Plants by K.J. Niklas University of Chicago Press, 1997. £51.95/$65.00 hbk, £15.95/$19.95 pbk (xix +449 pages) ISBN 0 226 58082 2/0 226 58083 0.

A fluorogenic, mixed-disulfide reagent for thiol assay.

The design and synthesis of the mixed disulfide (ortho-nitroaniline-N-ethyldithio) 2-[pyridyl-5-thioureido-N'-(5-fluorescein)] are described and the chemical and spectroscopic properties of this thiol-specific fluorogenic reagent are presented. The high reactivity and sensitivity of this reagent in thiol assay are demonstrated with low-molecular-weight thiols and with human carbonmonoxyhemoglobin and its subunits. Comparison with conventional absorption methods shows that at least 100 times less material is needed; moreover, high background absorbance or turbidity do not interfere with the assay.