Projecting excess emergency department visits and associated costs in Brisbane, Australia, under population growth and climate change scenarios

The direct and indirect health effects of increasingly warmer temperatures are likely to further burden the already overcrowded hospital emergency departments (EDs). Using current trends and estimates in conjunction with future population growth and climate change scenarios, we show that the increased number of hot days in the future can have a considerable impact on EDs, adding to their workload and costs. The excess number of visits in 2030 is projected to range between 98–336 and 42–127 for younger and older groups, respectively. The excess costs in 2012–13 prices are estimated to range between AU$51,000–184,000 (0–64) and AU$27,000–84,000 (65+). By 2060, these estimates will increase to 229–2300 and 145–1188 at a cost of between AU$120,000–1,200,000 and AU$96,000–786,000 for the respective age groups. Improvements in climate change mitigation and adaptation measures are likely to generate synergistic health co-benefits and reduce the impact on frontline health services.

A Chlamydia trachomatis strain with a chemically generated amino acid substitution (P370L) in the cthtrA gene shows reduced elementary body production

Background Chlamydia (C.) trachomatis is the most prevalent bacterial sexually transmitted infection worldwide and the leading cause of preventable blindness. Genetic approaches to investigate C. trachomatis have been only recently developed due to the organism’s intracellular developmental cycle. HtrA is a critical stress response serine protease and chaperone for many bacteria and in C. trachomatis has been previously shown to be important for heat stress and the replicative phase of development using a chemical inhibitor of the CtHtrA activity. In this study, chemically-induced SNVs in the cthtrA gene that resulted in amino acid substitutions (A240V, G475E, and P370L) were identified and characterized. Methods SNVs were initially biochemically characterized in vitro using recombinant protein techniques to confirm a functional impact on proteolysis. The C. trachomatis strains containing the SNVs with marked reductions in proteolysis were investigated in cell culture to identify phenotypes that could be linked to CtHtrA function. Results The strain harboring the SNV with the most marked impact on proteolysis (cthtrAP370L) was detected to have a significant reduction in the production of infectious elementary bodies. Conclusions This provides genetic evidence that CtHtrA is critical for the C. trachomatis developmental cycle.

Determination of the effect of JO146, a CtHtrA inhibitor, on the chlamydial developmental cycle and persistence

The role of Chlamydia trachomatis HtrA (CtHtrA) for the growth and pathogenesis of this organism is presented. Inhibition of CtHtrA led to loss of infectious progeny in Chlamydia, particularly during heat stress or recovery from penicillin persistence. Isolation of CtHtrA inhibitor resistant mutants identified positive selection for mutants in fatty acid related pathways. Importantly, HtrA inhibition was effective against clinical isolates of C. trachomatis. Thus the findings combined indicate that CtHtrA is an important chlamydial growth factor that has the potential to be targeted for the development of anti-chlamydial drugs in the future.

Photosynthetic responses of seven tropical seagrasses to elevated seawater temperature

This study uses chlorophyll a fluorescence to examine the effect of environmentally relevant (1-4 h) exposures of thermal stress (35-45 [deg]C) on seagrass photosynthetic yield in seven tropical species of seagrasses. Acute response of each tropical seagrass species to thermal stress was characterised, and the capacity of each species to tolerate and recover from thermal stress was assessed. Two fundamental characteristics of heat stress were observed. The first effect was a decrease in photosynthetic yield (Fv / Fm) characterised by reductions in F and Fm'. The dramatic decline in Fv / Fm ratio, due to chronic inhibition of photosynthesis, indicates an intolerance of Halophila ovalis, Zostera capricorni and Syringodium isoetifolium to ecologically relevant exposures of thermal stress and structural alterations to the PhotoSystem II (PSII) reaction centres. The decline in Fm' represents heat-induced photoinhibition related to closure of PSII reaction centres and chloroplast dysfunction. The key finding was that Cymodocea rotundata, Cymodocea serrulata, Halodule uninervis and Thalassia hemprichii were more tolerant to thermal stress than H. ovalis, Z. capricorni and S. isoetifolium. After 3 days of 4 h temperature treatments ranging from 25 to 40 [deg]C, C. rotundata, C. serrulata and H. uninervis demonstrated a wide tolerance to temperature with no detrimental effect on Fv / Fm' qN or qP responses. These three species are restricted to subtropical and tropical waters and their tolerance to seawater temperatures up to 40 [deg]C is likely to be an adaptive response to high temperatures commonly occurring at low tides and peak solar irradiance. The results of temperature experiments suggest that the photosynthetic condition of all seagrass species tested are likely to suffer irreparable effects from short-term or episodic changes in seawater temperatures as high as 40-45 [deg]C. Acute stress responses of seagrasses to elevated seawater temperatures are consistent with observed reductions in above-ground biomass during a recent El Nino event.

A multisite managed environment facility for targeted trait and germplasm phenotyping

Field evaluation of germplasm for performance under water and heat stress is challenging. Field environments are variable and unpredictable, and genotype x environment interactions are difficult to interpret if environments are not well characterised. Numerous traits, genes and quantitative trait loci have been proposed for improving performance but few have been used in variety development. This reflects the limited capacity of commercial breeding companies to screen for these traits and the absence of validation in field environments relevant to breeding companies, and because little is known about the economic benefit of selecting one particular trait over another. The value of the proposed traits or genes is commonly not demonstrated in genetic backgrounds of value to breeding companies. To overcome this disconnection between physiological trait breeding and uptake by breeding companies, three field sites representing the main environment types encountered across the Australian wheatbelt were selected to form a set of managed environment facilities (MEFs). Each MEF manages soil moisture stress through irrigation, and the effects of heat stress through variable sowing dates. Field trials are monitored continuously for weather variables and changes in soil water and canopy temperature in selected probe genotypes, which aids in decisions guiding irrigation scheduling and sampling times. Protocols have been standardised for an essential core set of measurements so that phenotyping yield and other traits are consistent across sites and seasons. MEFs enable assessment of a large number of traits across multiple genetic backgrounds in relevant environments, determine relative trait value, and facilitate delivery of promising germplasm and high value traits into commercial breeding programs.

Low-frequency electrical stimulation combined with a cooling vest improves recovery of elite kayakers following a simulated 1000-m race in a hot environment

This study compared the effects of a low-frequency electrical stimulation (LFES; Veinoplus® Sport, Ad Rem Technology, Paris, France), a low-frequency electrical stimulation combined with a cooling vest (LFESCR) and an active recovery combined with a cooling vest (ACTCR) as recovery strategies on performance (racing time and pacing strategies), physiologic and perceptual responses between two sprint kayak simulated races, in a hot environment (∼32 wet-bulb-globe temperature). Eight elite male kayakers performed two successive 1000-m kayak time trials (TT1 and TT2), separated by a short-term recovery period, including a 30-min of the respective recovery intervention protocol, in a randomized crossover design. Racing time, power output, and stroke rate were recorded for each time trial. Blood lactate concentration, pH, core, skin and body temperatures were measured before and after both TT1 and TT2 and at mid- and post-recovery intervention. Perceptual ratings of thermal sensation were also collected. LFESCR was associated with a very likely effect in performance restoration compared with ACTCR (99/0/1%) and LFES conditions (98/0/2%). LFESCR induced a significant decrease in body temperature and thermal sensation at post-recovery intervention, which is not observed in ACTCR condition. In conclusion, the combination of LFES and wearing a cooling vest (LFESCR) improves performance restoration between two 1000-m kayak time trials achieved by elite athletes, in the heat.

Sorghum genotypes differ in high temperature responses for seed set

Significant genotypic differences in tolerance of pollen germination and seed set to high temperatures have been shown in sorghum. However, it is unclear whether differences were associated with variation in either the threshold temperature above which reproductive processes are affected, or in the tolerance to increased temperature above that threshold. The objectives of this study were to (a) dissect known differences in heat tolerance for a range of sorghum genotypes into differences in the threshold temperature and tolerance to increased temperatures, (b) determine whether poor seed set under high temperatures can be compensated by increased seed mass, and (c) identify whether genotypic differences in heat tolerance in a controlled environment facility (CEF) can be reproduced in field conditions. Twenty genotypes were grown in a CEF under four day/night temperatures (31.9/21.0 °C, 32.8/21.0 °C, 36.1/21.0 °C, and 38.0/21.0 °C), and a subset of six genotypes was grown in the field under four different temperature regimes around anthesis. The novelty of the findings in this study related to differences in responsiveness to high temperature—genotypic differences in seed set percentage were found for both the threshold temperature and the tolerance to increased maximum temperature above that threshold. Further, the response of seed set to high temperature in the field study was well correlated to that in the CEF (R2 = 0.69), although the slope was significantly less than unity, indicating that heat stress effects may have been diluted under the variable field conditions. Poor seed set was not compensated by increased seed mass in either CEF or field environments. Grain yield was thus closely related to seed set percentage. This result demonstrates the potential for development of a low-cost field screening method to identify high-temperature tolerant varieties that could deliver sustainable yields under future warmer climates.

Regulation of respiratory activity of brown adipose tissue mitochondria through changes in cytochromes.

Exposure of cold-acclimatized rats to heat (37 degrees C) for a short period decreased brown adipose tissue (BAT) mitochondrial substrate-dependent oxygen uptake and H2O2 generation. Both the concentration and substrate-dependent rate of cytochrome b reduction decreased as early as 3 h of heat exposure. These results identify cytochrome b as the locus of regulation of electron transport in BAT mitochondria under conditions of heat stress.

Additional role for the ccd operon of F-plasmid as a transmissible persistence factor

Toxin-antitoxin (TA) systems are found on both bacterial plasmids and chromosomes, but in most cases their functional role is unclear. Gene knockouts often yield limited insights into functions of individual TA systems because of their redundancy. The well-characterized F-plasmid-based CcdAB TA system is important for F-plasmid maintenance. We have isolated several point mutants of the toxin CcdB that fail to bind to its cellular target, DNA gyrase, but retain binding to the antitoxin, CcdA. Expression of such mutants is shown to result in release of the WT toxin from a functional preexisting TA complex as well as derepression of the TA operon. One such inactive, active-site mutant of CcdB was used to demonstrate the contribution of CcdB to antibiotic persistence. Transient activation of WT CcdB either by coexpression of the mutant or by antibiotic/heat stress was shown to enhance the generation of drug-tolerant persisters in a process dependent on Lon protease and RecA. An F-plasmid containing a ccd locus can, therefore, function as a transmissible persistence factor.

Negative regulation of transcription factors by Srb10 cyclin-dependent kinase

The ubiquitin-dependent proteolytic pathway plays an important role in a broad array of cellular processes, inducting cell cycle control and transcription. Biochemical analysis of the ubiquitination of Sic1, the B-type cyclin-dependent kinase (CDK) inhibitor in budding yeast helped to define a ubiquitin ligase complex named SCF^cdc4 (for Skp1, Cdc53/cullin, F-box protein). We found that besides Sic1, the CDK inhibitor Far1 and the replication initiation protein Cdc6 are also substrates of SCF^cdc4 in vitro. A common feature in the ubiquitination of the cell cycle SCF^cdc4 substrates is that they must be phosphorylated by the major cell cycle CDK, Cdc28. Gcn4, a transcription activator involved in the general control of amino acid biosynthesis, is rapidly degraded in an SCF^cdc4-dependent manner in vivo. We have focused on this substrate to investigate the generality of the SCF^cdc4 pathway. Through biochemical fractionations, we found that the Srb10 CDK phosphorylates Gcn4 and thereby marks it for recognition by SCF^cdc4 ubiquitin ligase. Srb10 is a physiological regulator of Gcn4 stability because both phosphorylation and turnover of Gcn4 are diminished in srb10 mutants. Furthermore, we found that at least two different CDKs, Pho85 and Srb10, conspire to promote the rapid degradation of Gcn4 in vivo. The multistress response transcriptional regulator Msn2 is also a substrate for Srb10 and is hyperphosphorylated in an Srb10-dependent manner upon heat stress-induced translocation into the nucleus. Whereas Msn2 is cytoplasmic in resting wild type cells, its nuclear exclusion is partially compromised in srb10 mutant cells. Srb10 has been shown to repress a subset of genes in vivo, and has been proposed to inhibit transcription via phosphorylation of the C-terminal domain of RNA polymerase II. Our results suggest a general theme that Srb10 represses the transcription of specific genes by directly antagonizing the transcriptional activators.

The analysis of the transient temperature distribution of double-slab Nd:YAG laser medium

A novel double-slab Nd:YAG laser, which uses face-pumped slab medium cooled by liquid with different temperatures on both sides, is proposed. The thermal distortion of wavefront caused by the non-uniform temperature distribution in the laser gain media can be self-compensated. According to the method of operation, the models of the temperature distribution and stress are presented, and the analytic solutions for the model are derived. Furthermore, the numerical simulations with pulse pumping energy of 10 J and repetition frequencies of 500 and 1000 Hz are calculated respectively for Nd:YAG laser medium. The simulation results show that the temperature gradient remains the approximative linearity, and the heat stress is within the extreme range. Then the absorption coefficient is also discussed. The result indicates that the doping concentration cannot be too large for the high repetition frequency laser. It has been proved that the high repetition frequency, high laser beam quality, and high average output power of the order of kilowatt of Nd: YAG slab laser can be achieved in this structure.

Populações de Chthamalus spp. em costões rochosos da baía da ilha Grande (RJ) e suas relações com o clima entre 2002 e 2012

Poucos organismos são aptos a suportar o alto estresse provocado pelas variações de temperatura e alta dessecação na faixa superior da região entremarés de costões rochosos, sendo um deles o cirripédio Chthamalus. Apesar da sua resistência, vivem constantemente próximos ao seu limite de tolerância fisiológica, o que pode influenciar suas populações. O objetivo deste estudo foi caracterizar as flutuações das populações de Chthamalus spp. na faixa superior da região entremarés em quatro costões rochosos na Baía da Ilha Grande entre 2002 e 2012, relacionando estas variações com os fatores ambientais temperatura do ar, temperatura superficial marinha e precipitação, verificando o potencial destes organismos como indicadores de variações climáticas. Para isso foram investigadas a temperatura do ar e precipitação a partir de dados da estação meteorológica de Angra dos Reis e temperatura da superfície do mar a partir de imagens de satélite (MODIS/AQUA), além das porcentagens de cobertura de Chthamalus spp. a partir de amostragens sazonais. Em geral o estudo indica que as populações foram influenciadas pelas variáveis biológicas recrutamento e competição intraespecífica. Foram verificadas grandes diferenças entre as populações nos costões rochosos estudados. A estação C1, apresentou altas coberturas de cirripédios jovens e adultos ao longo de praticamente todo o período de estudo. Na estação C2 ocorreram as maiores variações, enquanto nas estações C3 e C4 ocorreram coberturas menores e variações menos proeminentes. Estas diferenças provavelmente estiveram ligadas às características físicas de cada costão rochoso. Os anos de 2003 e 2010 foram caracterizados como de altas temperaturas (temperaturas do mar e do ar) quando comparados com os demais anos de estudo. Estes anos foram ainda caracterizados pela ocorrência do fenômeno El Niño, com altas anomalias térmicas, o que indica que este fenômeno climático influenciou as temperaturas da região. Nestes mesmos anos as coberturas de Chthamalus spp. foram relativamente baixas, o que indica que o estresse térmico afetou as populações deste cirripédio. Pode-se inferir através deste estudo que as populações de Chthamalus spp. sofrem influência direta dos fatores ambientais investigados, sendo com isso um potencial indicador de mudanças climáticas.

染色体加倍对忍冬生物学性状及其生态适应性的影响

忍冬（Lonicera japonica Thunb.）属忍冬科忍冬属，是一种重要的药用植物，其花蕾称为金银花（Flos Lonicerae），在我国已有1000多年的药用历史，具有清热解毒、凉散风热等功效。我们利用秋水仙素诱导二倍体“大毛花”品种茎尖选育出同源四倍体“九丰一号”品种，并在生产中发现花蕾产量显著提高，而药效成份含量是否发生变化了呢？四倍体忍冬表现出典型的器官巨大性，这些变化是否与其较强生态适应性之间存在联系呢？染色体加倍增强了忍冬的生态适应性，其生态修复功能如何呢？在本研究中，主要从以下几个方面进行了探讨：（1）染色体加倍对其叶片，茎、花蕾和花蕾产量及其药效成份等生物学性状的影响;（2）染色体加倍后植物对水分胁迫的响应;（3）染色体加倍后植物对热胁迫的响应;（4）除上述两个品种外，增加一个变异品种“红银花”，探讨3个忍冬品种对退化生态系统的修复功能。主要结果如下： 1. 通过测定根尖细胞染色体数目和使用流式细胞仪分析茎尖细胞DNA含量，表明四倍体忍冬（2n = 4x = 36）确实来自二倍体忍冬（2n = 2x = 18）的染色体加倍。四倍体忍冬气孔细胞大小显著大于二倍体，而气孔密度显著低于二倍体。四倍体忍冬没有光合“午休”，而二倍体存在明显的光合“午休”，这可能与其存在抗高温的叶片解剖结构特性有关。四倍体忍冬叶片较二倍体变大、变厚、变浓绿（较高叶绿素含量）。与二倍体相比，四倍体忍冬单位叶面积重量显著增高，表明其具有较强的生态适应性。四倍体忍冬单个花蕾的鲜重和干重均显著大于二倍体。连续3年的花蕾产量调查表明，四倍体显著高于二倍体。染色体加倍使其茎干粗壮、节间变短、新梢上着生花蕾数目增多及单个花蕾变大，这是其花蕾高产的生物学基础。对金银花的药效成份而言，染色体加倍不影响绿原酸的含量，但增加了木犀草苷的含量。结果表明，染色体加倍能增加金银花的产量和药效成份的含量，建议四倍体忍冬在药材生产中推广应用。 2. 水分胁迫显著降低二倍体和四倍体忍冬叶片的净光合速率、气孔导度和蒸腾速率。水分胁迫也降低电子传递速率、光系统II实际量子产量和光化学猝灭，而增加非光化学猝灭、总可溶性糖、脯氨酸和丙二醛的含量。四倍体忍冬对水分胁迫的响应表现为其叶片水势、气体交换、叶绿素荧光和有关代谢物含量的变化程度低于二倍体，并且复水后其恢复能力快于二倍体，表明染色体加倍增强了忍冬的抗旱能力。分析其主要原因，可能是由于四倍体植株总叶面积减少、单位叶面积重量增加、叶片表皮细胞和栅栏组织增大以及叶片表皮毛较浓密等形态解剖结构特性有关。结果表明，染色体加倍能增加忍冬植物的抗旱能力，而使其具有较强的生态适应性。 3. 二倍体和四倍体忍冬受48 ºC热胁迫处理6 h和恢复10 h，以及离体叶片45 ºC，50 ºC，55 ºC 水浴热胁迫3 min，应用叶绿素荧光成像系统研究了它们对热胁迫的响应。热胁迫显著降低了两个品种叶片的最大光化学效率、电子传递速率、光系统II实际量子产量和光化学猝灭，降低了四倍体的非光化学猝灭，而增加了二倍体的非光化学猝灭。热胁迫增加了两个品种叶片的总可溶性糖、脯氨酸和丙二醛的含量。四倍体受热胁迫的叶绿素荧光参数和有关代谢物的响应程度低于二倍体，以及其恢复程度快于二倍体，表明染色体加倍提高了抗热性。此外，叶绿素荧光成像的异质性也表明，四倍体的抗热能力大于二倍体。进一步的叶片解剖结构分析表明，四倍体叶片的表皮细胞变大、栅栏组织增厚、表皮毛较浓密等特点，是其抗热性强的主要原因。 4.根据以上的研究结果，通过四倍体忍冬生态修复功能的野外试验证明染色体加倍后其生态适应性变化。在本研究中，针对北京市门头沟区大面积不同类型的废弃地急需恢复植被和景观的问题，在恢复生态学理念的指导下，综合运用集成技术，将3个忍冬品种植物用于这些退化生态系统的恢复。在王平镇的公路下边坡（以碎石和矿渣为主）、煤矿、石灰窑和采石场4种类型废弃地建立生态修复的试验示范区。结果表明，在4个废弃地类型上引进的3个金银花品种，具有使示范区快速复绿、当年成景和群落快速形成的潜力，并具有对不同退化迹地的适应能力和恢复效果，其中四倍体忍冬效果更好些，这主要与其形态解剖结构和较强的生态适应性有关。

盐适应植物光合作用耐热性研究

　　"盐渍土是一种分布广泛的土壤类型，盐渍土中生长的植物如何响应夏季较常出现的高温生长环境一直很少受到人们关注，我们以5种不同耐盐类型的植物为材料，研究其盐适应后光合作用的耐热性，并对耐热性原因做了进一步探讨，主要研究结果如下： 　　1． 用0、100、200、400 mM NaCl处理盐生植物碱蓬、滨藜、大莳萝蒿;用0、50、100、150 mM NaCl处理耐盐的甜土植物小麦和棉花。盐处理后碱蓬的整株干重变化不显著，而其他四种植物随着盐浓度的升高，整株干重逐渐减小，说明5种植物耐盐能力不同。盐处理对所有实验植物的光系统II最大光化学效率（Fv/Fm）、反应中心能量捕获效率（Fv′/Fm′）、实际量子产率（ΦPSII）、光化学猝灭系数（qP）等影响不显著;但对碳同化有明显影响。碱蓬盐处理后虽然气孔导度和胞间CO2浓度稍有下降，但CO2同化速率却高于对照;其他4种植物盐处理后CO2同化速率都明显降低，同时伴随着气孔导度和胞间CO2浓度的显著下降。以上结果表明盐适应植物的PSII并没有受到盐胁迫伤害，盐胁迫抑制这4种植物光合作用的一个重要原因可能是气孔限制。 　　2． 高温处理（36～48℃）结果显示，在42℃或45℃以上极端高温下，非盐处理植物的CO2同化速率下降至很低甚至为零，而盐适应植物仍保持一定强度的CO2同化能力。高温处理后盐适应植物的Fv/Fm、Fv′/Fm′、qP、ΦPSII下降幅度也都小于非盐处理植物。不同程度的盐胁迫都能诱导5种植物的光合作用对热胁迫产生抗性，说明植物在适应盐胁迫过程中都能启动一些耐逆机制，使得这5种植物的光合作用在获得耐盐性的同时也获得了对热胁迫的抗性。 　　3． 室温下（30℃）碱蓬盐处理后，过氧化氢酶、单脱氢抗坏血酸还原酶、抗坏血酸过氧化物酶和谷胱甘肽还原酶活性等显著下降，超氧化物岐化酶活性变化不大，只有脱氢抗坏血酸还原酶活性显著增加;抗坏血酸和谷胱甘肽含量也显著下降。42℃高温处理后，碱蓬叶片的抗氧化系统的酶活性和抗氧化小分子物质含量变化与室温时变化类似。而且盐处理碱蓬叶片的膜脂过氧化产物MDA含量无论在室温下还是42℃处理后都显著高于非盐处理。盐处理后，碱蓬的抗氧化能力没有提高，推测盐处理叶片抗氧化能力大小不是决定其光合作用耐热性主要因素。 　　4． 在菠菜PSII颗粒的保存液中加入不同浓度的甜菜碱、脯氨酸和蔗糖（0~800 mM），测定PSII最大光化学效率（Fv/Fm）结果表明，有机相容性溶质的积累能显著缓解盐（400 mM和800mM NaCl）、热(30℃和40℃)及盐热胁迫共同作用对菠菜PSII颗粒的伤害。而盐处理后碱蓬、滨藜和莳萝蒿叶片中脯氨酸和可溶性糖含量都显著升高，说明盐胁迫诱导的有机相容性溶质的积累可能在盐适应植物光合作用的耐热性中起重要作用。 　　5． 提取室温下（30℃）或42℃高温处理碱蓬叶片的叶绿体和类囊体膜，用30℃、35℃、40℃、45℃、50℃水浴进行热处理，结果显示：用室温下或42℃高温处理的碱蓬盐适应叶片提取的叶绿体和类囊体经45℃以上水浴温度处理后，其PSII最大光化学效率（Fv/Fm）和放氧活性都显著高于非盐处理碱蓬叶片的叶绿体和类囊体;用42℃高温处理碱蓬叶片提取的叶绿体和类囊体热稳定性显著高于室温下碱蓬的叶绿体和类囊体。表明盐胁迫和热胁迫类似，都能在类囊体水平上诱导某些保护物质，增加植物PSII的耐热性。 　　6． 分析类囊体膜膜脂组成，结果显示，盐处理后碱蓬的类囊体膜脂中的饱和脂肪酸含量减少，不饱和脂肪酸含量增加;MGDG和DGDG含量变化不明显，而PG含量显著下降;42℃高温处理后碱蓬的类囊体膜脂组成也有类似的变化规律。盐诱导的碱蓬类囊体膜脂成分的变化可能不影响盐适应植物光系统的耐热性。"