Rapid recovery of a population of the cryptic and evolutionarily distinct Hochstetter's Frog,Leiopelma hochstetteri,in a pest‐free environment

New Zealand's native frogs (genus Leiopelma) display a very high degree of endemism and belong to a distinctive and ancient evolutionary lineage. All four extant species are considered to be threatened or endangered, but the mechanisms behind their decline are poorly understood. Many of the potential factors causing population declines are confounded for the two species living on the mainland; in particular, habitat degradation and the presence of introduced mammalian pests have been difficult to disentangle in the past. Here we present data on a population of Hochstetter's Frog (Leiopelma hochstetteri) living in a pest‐free mainland sanctuary, the 3363‐ha Maungatautari Ecological Island. Survey data from this population shows a fourfold increase in numbers between 2009 and 2012 from a very low initial density. Our results suggest that for Hochstetter's Frog at least, and possibly the other mainland species of Leiopelma, introduced mammals are a major driving factor in population declines. Given that the frog population at Maungatautari was discovered by serendipity when planning for the pest‐free sanctuary was already well underway, this also highlights the conservation value of large pest‐free areas and ecosystem‐level management.     

Reconsidering connectivity in the sub‐Antarctic

Extreme and remote environments provide useful settings to test ideas about the ecological and evolutionary drivers of biological diversity. In the sub‐Antarctic, isolation by geographic, geological and glaciological processes has long been thought to underpin patterns in the region's terrestrial and marine diversity. Molecular studies using increasingly high‐resolution data are, however, challenging this perspective, demonstrating that many taxa disperse among distant sub‐Antarctic landmasses. Here, we reconsider connectivity in the sub‐Antarctic region, identifying which taxa are relatively isolated, which are well connected, and the scales across which this connectivity occurs in both terrestrial and marine systems. Although many organisms show evidence of occasional long‐distance, trans‐oceanic dispersal, these events are often insufficient to maintain gene flow across the region. Species that do show evidence of connectivity across large distances include both active dispersers and more sedentary species. Overall, connectivity patterns in the sub‐Antarctic at intra‐ and inter‐island scales are highly complex, influenced by life‐history traits and local dynamics such as relative dispersal capacity and propagule pressure, natal philopatry, feeding associations, the extent of human exploitation, past climate cycles, contemporary climate, and physical barriers to movement. An increasing use of molecular data – particularly genomic data sets that can reveal fine‐scale patterns – and more effective international collaboration and communication that facilitates integration of data from across the sub‐Antarctic, are providing fresh insights into the processes driving patterns of diversity in the region. These insights offer a platform for assessing the ways in which changing dispersal mechanisms, such as through increasing human activity and changes to wind and ocean circulation, may alter sub‐Antarctic biodiversity patterns in the future.     

Ectopic expression of a cyanobacterial flavodoxin in creeping bentgrass impacts plant development and confers broad abiotic stress tolerance

Flavodoxin (Fld) plays a pivotal role in photosynthetic microorganisms as an alternative electron carrier flavoprotein under adverse environmental conditions. Cyanobacterial Fld has been demonstrated to be able to substitute ferredoxin of higher plants in most electron transfer processes under stressful conditions. We have explored the potential of Fld for use in improving plant stress response in creeping bentgrass (Agrostis stolonifera L.). Overexpression of Fld altered plant growth and development. Most significantly, transgenic plants exhibited drastically enhanced performance under oxidative, drought and heat stress as well as nitrogen (N) starvation, which was associated with higher water retention and cell membrane integrity than wild‐type controls, modified expression of heat‐shock protein genes, production of more reduced thioredoxin, elevated N accumulation and total chlorophyll content as well as up‐regulated expression of nitrite reductase and N transporter genes. Further analysis revealed that the expression of other stress‐related genes was also impacted in Fld‐expressing transgenics. Our data establish a key role of Fld in modulating plant growth and development and plant response to multiple sources of adverse environmental conditions in crop species. This demonstrates the feasibility of manipulating Fld in crop species for genetic engineering of plant stress tolerance.     

Comparison of the urban heat island intensity quantified by using air temperature and Landsat land surface temperature in Hangzhou,China

This study compared different measures of urban heat island (UHI) intensity, which were calculated using both air temperature (T_air) at a height of 1.5 m and Landsat land surface temperature (LST) in Hangzhou, China. Two UHI-driven indicators (range and magnitude) and two land-cover-driven indicators (urban-rural and urban-agriculture) were calculated to quantify the UHI intensity based on hourly T_air from five stations and fifteen Landsat 5 LST images. Pearson correlation testing and a moving average times series of the previous 30 days were used to investigate the relationship between UHI intensities calculated by different indicators and data. The results indicate that the land-cover-driven indicators explain UHI better than the UHI-driven indicators, while the calculated values of UHI intensity using Landsat LST and hourly T_air are not comparable. We also investigated the influence of weather conditions on UHI intensity. Generally, Landsat-LST-based UHI performs best on hot sunny days, while T_air-based UHI has a better chance during the nighttime following a dry sunny day. This study suggests that the value of UHI intensity can be influenced by the selected indicators, the data used, the acquisition time and the weather conditions. Thus, these factors should be considered when comparing UHI intensity between different cities or quantifying their influences (e.g., population size, land use and land cover change) on UHI intensity.     

Giant tortoise habitats under increasing drought conditions on Aldabra Atoll—Ecological indicators to monitor rainfall anomalies and related vegetation activity

Aldabra Atoll has the largest population of giant tortoises (Aldabrachelys gigantea) in the world. As such an important biological resource, it is necessary to understand how the effects of climate change will impact this keystone species; in particular the frequency of drought, which is likely to affect tortoise habitat. To assess whether drought frequency has changed over the last 50 years on Aldabra, we calculated the standardized precipitation index (SPI) to identify drought periods using monthly rainfall data collected during 1969–2013. We found that drought frequency has increased to more than six drought months per year today compared with about two months per year in the 1970s (t = 2.884, p = 0.006). We used MODIS normalized difference vegetation index (NDVI) as a proxy for vegetation activity, to determine how vegetation has responded to the changing drought frequency between 2000 and 2013. We found that Aldabra’s vegetation is highly responsive to changes in rainfall: anomalies in long-term mean monthly NDVI across Aldabra were found to decrease below the mean during most drought periods and increase above the mean during most non-drought periods. To investigate the response of tortoise habitat to rainfall, we extracted mean NDVI anomalies for three key habitat types. Open mixed scrub and grasslands, the preferred habitat of tortoises, showed the greatest decrease in vegetation activity during drought periods, and the greatest increase in average greenness during non-drought periods. Recent analysis has shown vegetation changes on Aldabra in recent decades. If these changes are caused by decreased precipitation, then the increased frequency of drought could impact the tortoise population, in both the short and long term, by limiting the quality and quantity of forage and/or shade availability within favoured habitats, and by changing the habitat composition across the atoll.     

赤拟谷盗HSP70基因克隆和竞争定量PCR检测

为研究赤拟谷盗Tribolium castaneum受到热胁迫后高度保守的热激蛋白70（heat shock protein 70,HSP70）基因的表达变化,本研究扩增了681 bp的赤拟谷盗hsp70片段,编码227个氨基酸残基,GenBank登录号为HM345948。同源性分析表明：赤拟谷盗hsp70核苷酸序列与马铃薯甲虫Leptinotarsa decemlineata的hsp70（GenBank登录号：AF322911.1）同源性最高,为97%;其推测的蛋白序列与马铃薯甲虫、甘蓝夜蛾Mamestra brassicae、黑腹果蝇Drosophila melanogaster和美洲斑潜蝇Liriomyza sativae的HSP70蛋白均有94%以上的同源性。利用RT-PCR技术得到与赤拟谷盗hsp70进行竞争定量的内部竞争物, 以等量的目标cDNA和一系列稀释的竞争模板进行竞争PCR扩增,构建了hsp70的竞争定量PCR检测体系, 该体系标准曲线的线性方程为Y=1.032X-1.618 (r²=0.975)。这些结果为赤拟谷盗的hsp70定量检测提供了方便,并为热控技术防治害虫提供了基础资料。     

气候变化背景下中国农业气候资源变化Ⅷ.江西省双季稻各生育期热量条件变化特征

基于江西省地面气象资料和农业气象试验站数据,分析了江西省双季稻生育期的变化趋势,并利用生长度日（GDD）、低温度日（CDD）和高温度日（HDD）对1981-2007年江西省水稻各生育期热量资源的变化趋势进行分析.结果表明：气候变暖背景下,江西省水稻生长季平均气温、平均最低气温和平均最高气温均呈升高趋势,引起双季稻生长季缩短,其中,营养生长期日数减少最明显,而生殖生长期延长;生长度日和高温度日均增加,低温度日减少.研究期间,江西省双季稻有效热量资源增加,低温风险减少,但高温风险增多;江西省水稻有效热量资源的空间变化特征表现为东北部的增幅大于西南部,南部的低温风险大于北部,中部的高温风险最大.     

分子伴侣参与调控动、植物的发育和进化进程

近年来, 人们对分子伴侣的功能研究取得了很大进展, 阐明了它参与细胞新合成蛋白多肽的折叠、组装、运输和蛋白质的降解过程。在这些过程中, 伴随着分子伴侣表达量的高低变化, 细胞线粒体数量也会发生相应的变化。文章综述了分子伴侣参与调控动、植物的发育和进化进程, 如: 动、植物育性调控, 抗逆境能力提高及热休克蛋白-多肽复合物的肿瘤免疫治疗探索等。