Does the Reproductive Strategy Affect the Transmission and Genetic Diversity of Bionts in Cyanolichens? A Case Study Using Two Closely Related Species

Observed levels of population genetic diversity are often associated with differences in species dispersal and reproductive strategies. In symbiotic organisms, the genetic diversity level of each biont should also be highly influenced by biont transmission. In this study, we evaluated the influence of the reproductive strategies of cyanolichen species on the current levels of population genetic diversity of bionts. To eliminate any phylogenetic noise, we selected two closely related species within the genus Degelia, which only differ in their reproductive systems. We sampled all known populations of both species in central Spain and genotyped the fungal and cyanobacterial components of lichen samples using DNA sequences as molecular markers. We applied population genetics approaches to evaluate the genetic diversity and population genetic structure of the symbiotic components of both lichen species. Our results indicate that fungal and cyanobiont genetic diversity is highly influenced by the reproductive systems of lichen fungus. We detected higher bionts genetic diversity values in the sexual species Degelia plumbea. By contrast, the levels of fungal and cyanobiont genetic diversity in the asexual species Degelia atlantica were extremely low (almost clonal), and the species shows a high specificity towards its cyanobiont. Our results indicate that reproduction by vegetative propagules, in species of the genus Degelia, favors vertical transmission and clonality, which affects the species’ capacity for resources and competition, thereby limiting the species to restricted niches.     

Can zinc influence nutrient resorption? A test with the drought-deciduous desert shrub Fouquieria splendens (ocotillo)

Paradoxically low nitrogen resorption efficiency in the drought-deciduous desert shrub Fouquieria splendens Engelm (ocotillo) triggered tests of the hypotheses that resorption is often low in this species and that resorption is influenced by zinc. Resorption efficiency and proficiency were measured in 1989 and 1994 at two sites in the Chihuahuan Desert in plants to which zinc, or zinc and nitrogen were added. Resorption of nitrogen, phosphorus, and zinc in unfertilized plants varied temporally and spatially, but was both efficient (66%, 49%, and 40%, respectively) and proficient (0.55%, 0.09%, and 9.4 μg g−1, respectively) as determined by comparison to worldwide resorption patterns in a wide variety of other species. Applications of zinc had no significant effect on the resorption of nitrogen and phosphorus, but did influence the resorption of zinc. Resorption of zinc was significantly less efficient in zinc-treated plants than controls at only one of the two sites in one of the 2 years, yet resorption of zinc was significantly less proficient in zinc-treated plants than controls in both years and at both sites. This pattern of zinc resorption adds insight into the continuing debate regarding the relationship between fertility and resorption because the data used to fuel the debate have almost exclusively described macronutrients, not trace metals. The high variability in resorption among individuals, sites, and years observed for F. splendens may well be an attribute of many desert-dwelling, drought-deciduous plants. When senescence is controlled primarily by water availability rather than photoperiod, especially in a landscape characterized by unpredictable amounts and timing of precipitation, high variability in associated processes such as resorption may be inevitable.     

Can Tropical Insects Stand the Heat? A Case Study with the Brown Planthopper Nilaparvata lugens (St?l)

The brown planthopper Nilaparvata lugens (Stål) is the most serious pest of rice across the world, especially in tropical climates. N. lugens nymphs and adults were exposed to high temperatures to determine their critical thermal maximum (CT_max), heat coma temperature (HCT) and upper lethal temperature (ULT). Thermal tolerance values differed between developmental stages: nymphs were consistently less heat tolerant than adults. The mean (± SE) CT_max of nymphs and adult females and males were 34.9±0.3, 37.0±0.2 and 37.4±0.2°C respectively, and for the HCT were 37.7±0.3, 43.5±0.4 and 42.0±0.4°C. The ULT₅₀ values (± SE) for nymphs and adults were 41.8±0.1 and 42.5±0.1°C respectively. The results indicate that nymphs of N. lugens are currently living at temperatures close to their upper thermal limits. Climate warming in tropical regions and occasional extreme high temperature events are likely to become important limiting factors affecting the survival and distribution of N. lugens.     

Can Topical Insect Repellents Reduce Malaria? A Cluster-Randomised Controlled Trial of the Insect Repellent N,N-diethyl-m-toluamide (DEET) in Lao PDR

Background

Mosquito vectors of malaria in Southeast Asia readily feed outdoors making malaria control through indoor insecticides such as long-lasting insecticidal nets (LLINs) and indoor residual spraying more difficult. Topical insect repellents may be able to protect users from outdoor biting, thereby providing additional protection above the current best practice of LLINs.

Methods and Findings

A double blind, household randomised, placebo-controlled trial of insect repellent to reduce malaria was carried out in southern Lao PDR to determine whether the use of repellent and long-lasting insecticidal nets (LLINs) could reduce malaria more than LLINs alone. A total of 1,597 households, including 7,979 participants, were recruited in June 2009 and April 2010. Equal group allocation, stratified by village, was used to randomise 795 households to a 15% DEET lotion and the remainder were given a placebo lotion. Participants, field staff and data analysts were blinded to the group assignment until data analysis had been completed. All households received new LLINs. Participants were asked to apply their lotion to exposed skin every evening and sleep under the LLINs each night. Plasmodium falciparum and P. vivax cases were actively identified by monthly rapid diagnostic tests. Intention to treat analysis found no effect from the use of repellent on malaria incidence (hazard ratio: 1.00, 95% CI: 0.99–1.01, p = 0.868). A higher socio-economic score was found to significantly decrease malaria risk (hazard ratio: 0.72, 95% CI: 0.58–0.90, p = 0.004). Women were also found to have a reduced risk of infection (hazard ratio: 0.59, 95% CI: 0.37–0.92, p = 0.020). According to protocol analysis which excluded participants using the lotions less than 90% of the time found similar results with no effect from the use of repellent.

Conclusions

This randomised controlled trial suggests that topical repellents are not a suitable intervention in addition to LLINs against malaria amongst agricultural populations in southern Lao PDR. These results are also likely to be applicable to much of the Greater Mekong Sub-region.

Trial Registration

This trial is registered with number {"type":"clinical-trial","attrs":{"text":"NCT00938379","term_id":"NCT00938379"}}NCT00938379     

Are Morphometrics Sufficient for Estimating Age of Pre-Fledging Birds in the Field? A Test Using Common Terns (Sterna hirundo)

Age is a key component of fitness, affecting survival and reproductive capacities. Where it is not possible to study known individuals from birth, morphometrics (predominantly patterns of plumage development for birds) are most often used to estimate age. Although criteria for age estimations exist for many species, the degree to which these criteria improve the precision of estimates remains to be tested, restricting their widespread acceptance. We develop a photographic tool for estimating ages of Common Tern (Sterna hirundo) chicks and test it using 100 human observers of varying prior experience across four breeding colonies (three North American sites and one European site) and under controlled laboratory conditions. We followed the design approach of other morphometric tools, expanding it to create a user-friendly guide (divided into six age groupings). The majority (86%) of observers improved in chick-aging accuracy when using the tool by an average of 20.1% (±1.4 SE) and correctly estimated 60.3% (±1.4) of chick ages. This was similar to the intrinsic aging ability of our best field observer (63.3%). Observers with limited experience showed the greatest increases in chick-aging accuracy over experienced observers who likely had established a method for estimating chick ages prior to using the tool. Even the best observers only correctly estimated ages of chicks 62.9% (±2.8) of the time in the field and 84.0% (±2.9) of the time in the lab when using the tool and typically underestimated ages. This indicates that developmental variation between individual chicks can prevent completely reliable age estimates and corroborates the few existing data that suggest that morphometric criteria fail to achieve robust levels of accuracy and may introduce error into studies that rely on them. We conclude that novel approaches for estimating age, not only morphometric criteria, must be pursued.     

Can Biomethane Potential (BMP) Be Predicted from Other Variables Such As Biochemical Composition in Lignocellulosic Biomass and Related Organic Residues?

The potential of methane production by anaerobic digestion of lignocellulosic biomass depends not only on the availability of the resources in the considered territory, but also on their physico-chemical characteristics. Relevant methods of characterization are, therefore, needed to select and possibly combine the most appropriate biomass substrates in order to optimize energy recovery through anaerobic digestion processes. The objective of the present study was to determine whether biomethane potential of such substrates could be predicted from a limited number of variables more rapidly or determined more easily. A set of 36 biomass substrates and organic residues from a variety of origins was analyzed for total and easily hydrosoluble organic matter fractions (volatile solid, VS and soluble chemical oxygen demand, SCOD), neutral detergent soluble fraction (SOL), hemicelluloses (HEM), cellulose (CELL), and lignin-like residual fractions (RES). Bioreactivity of all samples was also measured by experimental assays (biochemical oxygen demand, BOD and biochemical methane potential, BMP). The whole set of data thereby obtained was analyzed statistically considering one dependent variable (BMP), and six independent variables (SCOD, SOL, HEM, CELL, RES, and BOD). Partial least square (PLS) analysis revealed very clearly a positive correlation between BMP and BOD, which were both anti-correlated with RES. On the other hand, no correlations were observed between BMP, SCOD, HEM, and CELL contents. PLS analysis showed that BMP was significantly correlated to the six independent variables. The most influential variables were found to be RES and BOD, and a polynomial model was successfully validated for the prediction of BMP from RES and BOD.     

A new genus of metalmark moths (Lepidoptera,Choreutidae) with Afrotropical and Australasian?distribution

Niveas Rota, new genus, and its two new species, N. agassizi Rota, new species, and N. kone Rota, new species, are described and illustrated. Niveas is assigned to the subfamily Choreutinae based on morphological and molecular data. Niveas agassizi is currently known only from Kenya and only from female specimens. Niveas kone has been found on the Solomon Islands and in Papua New Guinea (PNG). In PNG, larvae of this species have been reared from several species of Ficus (Moraceae). The two species are superficially quite dissimilar from each other. However, they share features in wing pattern and venation, as well as female genitalia, and the molecular data strongly support the monophyly of Niveas.     

Is dispersal density-dependent in carabid beetles? A field experiment with Harpalus rufipes (Degeer) and Pterostichus niger (Schaller) (Col., Carabidae)

In order to investigate whether density affects dispersal, carabid beetles of two species, Harpalus rufipes (Degeer) and Pterostichus niger (Schaller), were released separately in six and two field enclosures, respectively. The enclosures were 4 m² each and located in an oat field. The former species was released in seven densities, each with 12 replicates and the latter in five densities each with four replicates. Beetles leaving the centre of the enclosures were captured in pitfall traps along a 1 m wide strip of bare soil. Logistic models were fitted to the data. There were no significant effects of the density treatment variable on P. niger. For H. rufipes the best model was obtained by specifying the density treatment as a nominal variable. The deviance accounted for by this model was highly significant. There were, however, no consistent trends for either species with respect to the density treatment. The inclusion of climatic variables, the number of new beetles introduced at the onset of each trial, or the date of the trial did not improve the fit of any of the models. It is concluded that density did not significantly increase dispersal in the two species. It thus appears that a possible increase in behavioural interactions (i.e. interference competition) did not increase the dispersal in adults of the two species examined in this experiment.     

A case of systemic lupus erythematosus (SLE) and Sj?gren's syndrome associated with anti-T3 autoantibodies

A case of systemic lupus erythematosus (SLE) associated with Sj?gren's syndrome had extremely low serum triiodothyronine (T3) with normal levels of serum thyroxine (T4) measured by single antibody radioimmunoassays (RIAs) and thyroid stimulating hormone (TSH) during steroid treatment. Measurement of serum T3 and T4 with double antibody RIAs showed unusually high T3 and normal T4 concentrations. Examination of her serum revealed the presence of IgG class anti-T3 autoantibodies whose Scatchard plot was analyzed in two components; one with a higher associate constant (8.6 X 10(8)M-1) and a lower binding capacity (5.6 X 10(-7) mol/ml serum); the other a lower associate constant (3.5 X 10(7)M-1) and a higher binding capacity (2.1 X 10(-6) mol/ml serum). Antithyroglobulin (Tg) autoantibody has been positive throughout the seven year observation period. A significant positive correlation between titers of anti-Tg autoantibodies indicated that the antigen of anti-T3 antibodies in the patient could be T3 containing antigenic site(s) on the Tg molecule.     

Diel Calling Activity and Field Survival of the Bushcricket,Sciarasaga quadrata (Orthoptera: Tettigoniidae): A Role for Sound-locating Parasitic Flies?

In this study I examine the variability in calling activity of Sciarasaga quadrata over both the short (4 d) and long term (life span), and the temporal pattern to host searching by its most significant natural enemy, the ormiine fly Homotrixa alleni. Indeed, few male S. quadrata survive the entire calling season as this acoustically orienting parasitoid fly continually ‘culls’ calling males out of the population. I found that male S. quadrata commence calling over 1 h before sunset, cease around midnight and call, on average, for over 3 h within this period (range 0–11 h 09 min). There was significant concordance and repeatability in calling activity over both the short and long term, enabling me to conclude that relative differences in calling activity among males persist throughout a male's life span. There was a distinct peak to host searching by gravid female flies, with 82 % of all flies collected at acoustic traps between sunset and midnight. A positive association between call duration (time spent calling) and fly attraction was evident from multiple collections of flies at single traps. Counter to expectation, there was no significant decline in average call duration across successive collections of males, indicating that long-call-duration males were not being selectively culled by flies from the calling population. Males at the end of the calling season, when their remaining reproductive potential is low, allocate the majority of their calling time between sunset and midnight despite the high risk of fly attack. The distribution of call durations within the population was not skewed, which if heritable, indicates a lack of history of directional selection acting on call duration. Limited evidence suggests that encounters with females are rare in S. quadrata so that males may be selected, irrespective of natural selection pressure, to call for long periods of time to optimize their chance of attracting mates. The above findings are further discussed in relation to parasitoid foraging and acoustic reproductive strategies.     

Can postlarval bivalves select sediment type during settlement? A field test with Macoma balthica (L.) and Cerastoderma edule (L.)

Many soft-bottom benthic invertebrates display sediment-associated patterns of dispersion. Habitat selection experiments have shown that the larvae of some species can choose to settle in favourable habitats, and this process could establish patterns observed in the field. However, many soft-bottom infauna, including the bivalves Cerastoderma edule and Macoma balthica, show postlarval relocation. Such movements could obviate patterns established at initial settlement, and active habitat selection in these postlarval stages may be responsible for adult distributions. We investigated sediment selection in postlarval stages of these bivalves on an intertidal mudflat using a field survey and experiment. Our 1225 m² grid survey showed a strong spatial correlation between the smallest individuals of both species, which showed no correlation with sediment characteristics. Larger size groups showed increasingly strong associations with sediment type: C. edule with sandy sediments and M. balthica with muddy. In our sediment choice experiment, the numbers of bivalves recruited into muddy, sandy and muddy depression (to detect small-scale hydrodynamic effects) treatments after 2 days in the field were recorded. There were no significant treatment effects in either C. edule or M. balthica. All bivalves were too large to be initial settlers; they were thus relocating individuals. Neither the survey nor the experiment provided any evidence that relocating individuals of these two species could choose the sediment in which they alight. The sediment-related patterns observed in adults of these species must therefore be due to other mechanisms, possibly postsettlement predation by Carcinus maenas and/or an ability to leave less-preferred sediments in a series of migrations until the preferred habitat is found.     

Can Scat Analysis Describe the Feeding Habits of Big Cats? A Case Study with Jaguars (Panthera onca) in Southern Pantanal,Brazil

Large cats feeding habits have been studied through two main methods: scat analysis and the carcasses of prey killed by monitored animals. From November 2001 to April 2004, we studied jaguar predation patterns using GPS telemetry location clusters on a cattle ranch in southern Pantanal. During this period, we recorded 431 carcasses of animals preyed upon by monitored jaguars. Concurrently, we collected 125 jaguar scats opportunistically. We compared the frequencies of prey found through each method. We also compared the prey communities using Bray-Curtis similarity coefficient. These comparisons allowed us to evaluate the use of scat analysis as a means to describe jaguar feeding habits. Both approaches identified prey communities with high similarity (Bray-Curtis coefficient > 70). According to either method, jaguars consume three main prey: cattle (Bos taurus), caiman (Caiman yacare) and peccaries (Tayassu pecari and Pecari tajacu). The two methods did not differ in the frequency of the three main prey over dry and wet seasons or years sampled. Our results show that scat analysis is effective and capable of describing jaguar feeding habits.     

Do rice hybrids have heterosis for insect resistance? A study with Nilaparvata lugens (Hemiptera: Delphacidae) and Marasmia patnalis (Lepidoptera: Pyralidae)

Antibiosis-based resistance to two insect pests of rice, Nilaparvata lugens (St?l) (Hemiptera: Delphacidae) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae), was compared in 11 F1 hybrids and their parental lines. Our objective was to determine whether hybrids show heterosis (hybrid vigor) for insect resistance or susceptibility. Heterosis is defined as the amount by which a hybrid exceeds its midparent value or its better parent. Overall, we did not find evidence of heterosis or heterobeltiosis (a type of heterosis in which a hybrid exceeds its better parent) for antibiosis-based resistance or susceptibility to either of the insects. One hybrid, IR64616H, seemed more resistant to M. patnalis than its better parent but none of the other hybrids showed heterobeltiosis for resistance or susceptibility to either insect. Three hybrids had resistance to N. lugens that exceeded their midparent value, possibly due to dominant resistance in one of the parents. The increased frequency and severity of insect outbreaks on hybrid rice that have been reported in China may be attributable to factors other than diminished antibiosis in hybrids, such as greater attractiveness of hybrids to migrating or dispersing insects or differences in agronomic practices applied to hybrids and inbred rice cultivars.     

Leaf Abscission and Stem Lesions (Intumescences) on Poplar Clones after SO2 and O3 Fumigation: A Link with Ethylene Release?

Differences in premature leaf abscission and in visible steminjury in genetic lines of poplar followed continuous fumigationswith air pollutant levels of SO₂ (90–100 nl l^–1)and O₃ (70–80 nl l^–1) either separately or together.The clones used were: Populus deltoides var. missiouriensisMarsh., P. nigra cv. ‘italicd’ L., and the hybridsP. nigra cv. ‘italica’ xP. deltoides (He-X/3) andP. nigra cv.‘italica’ x P. nigra cv. ‘Serres’(He-K/7). While most leaf abscission occurred within 20 d fromthe start of fumigation, stem lesions (intumescences), appearedonly after 72 d. Their anatomical characteristics include theformation of lysigenous aerenchyma in the lower parts of theintumescence, the sloughing of superficial cells from the injuredarea, and the development of crystalline formations on the surfaceof the lesions. P. deltoides exhibited the least morphologicalresponse to the gases. Ethylene released from fumigated leaves was determined at thesame gas concentration of SO₂ (100 nl l^–1), O₃ (75 nll^–1) and their mixture. Leaves of P. deltoides consistentlyshowed the lowest ethylene production after the gas treatments.P. ‘italica’ production was higher but was littlealtered by the treatments. The two hybrids He-X/3 and He-K/7showed the greatest increases in ethylene evolution with time.With He-K/7 exposed to the gas mixture the production of ethylenedecreased after the initial sharp rise during days 1–2,and reflected the considerable leaf damage observed after day3. The results suggest that sensitivity to air pollution, (as shownby leaf abscission and the formation of stem intumescences)can be correlated with the level of pollutant-induced ethyleneevolution from leaves. Initially high levels could induce abscission,whilst prolonged production could be responsible for intumescenceinitiation. The discussion proposes a series of events fromSO₂ and/or O₃ entry into the leaf and the physiological reasonsfor the clonal differences. Key words: Sulphur dioxide, ozone, ethylene, poplar, leaf abscission, stem lesions     

Feasibility of Elective Nodal Irradiation (ENI) and Involved Field Irradiation (IFI) in Radiotherapy for the Elderly Patients (Aged ≥ 70 Years) with Esophageal Squamous Cell Cancer: A Retrospective Analysis from a Single Institute

PurposeWe conducted a retrospective analysis to assess the feasibility of involved field irradiation (IFI) in elderly patients with esophageal squamous cell cancer (ESCC).ResultsA total of 137 patients were enrolled. Fifty-four patients (39.4%) were allocated to the ENI group and 83 patients (60.6%) to the IFI group, the median doses in the two groups were 60 Gy and 59.4 Gy, respectively. For the entire group, the median survival time (MST) and PFS were 16 months and 12 months, respectively. The median PFS and 3-year PFS rate in the ENI group were 13 months and 20.6%, compared to 11 months and 21.0% in the IFI groups (p = 0.61). The MST and 3-year OS rate in the ENI and IFI groups were 17 months and 26.4% and 15.5 months and 21.7%, respectively (p = 0.25). The rate of grade ≥ 3 acute irradiation esophagitis in the ENI group was significantly higher than that in the IFI group (18.5% vs. 6.0%; p = 0.027). Other grade ≥ 3 treatment-related toxicities did not significantly differ between the two groups.ConclusionsIFI resulted in decreased irradiation toxicities without sacrificing OS in elderly patients with ESCC.     

Does seed germination contribute to ecological breadth and geographic range? A test with sympatric Diplusodon (Lythraceae) species from rupestrian fields

We tested the regeneration niche hypothesis by comparing the germination ecology of two sympatric Diplusodon species differing in their geographic range and microhabitat. Diplusodon orbicularis is an endemic shrub achieving high densities on sandy soils, whereas Diplusodon hirsutus has a wider geographic range and establishes on rocky outcrops. Seeds were set to germinate under constant temperatures of 15, 20, 25, 30 and 35°C under 12 h light/12 h dark conditions. Light induced germination in both species, but germination under darkness was also observed. Optimum conditions for germination were 25°C/light for both species. The lack of differences in soil temperatures between rocky outcrops and sandy soils provides evidence of no temperature‐dependent microhabitat selection. Unexpectedly, germinability of the more widespread species was lower than that of the endemic congener. Higher germinability of D. orbicularis may account for higher densities when compared with D. hirsutus. Our results provide limited support for the role of germination in contributing to ecological breadth and geographic range.