The Effect of Different Environmental Conditions on the Viability of Naegleria fowleri Amoebae

Naegleria fowleri, a free‐living amoeba found in soil and freshwater environments, is the causative agent of Primary Amoebic Meningoencephalitis. Infection occurs when amoebae enter the nasal cavity, attach to the nasal mucosa and travel along olfactory neurons towards the olfactory bulb. Upon reaching the central nervous system, the amoebae replicate very rapidly and can cause death in 3–10 days. Little is known about the conditions in which the amoeba can survive in the environment. We have tested conditions beyond the known boundaries on the viability of amoebae by introducing them into moderate and extreme salinity, pH, and temperatures. Our data shows that although viability expectedly decreases towards each of these extreme conditions, their tolerance was much greater than anticipated, including viability in moderate salinity, a wide pH range, and temperatures higher than the previously reported 45 °C.     

Birth weight and physical stature in St. Petersburg: Living standards of women in Russia, 1980–2005

We analyze data on the height and weight of mothers and newborn babies between 1980 and 2005 in St. Petersburg, Russia. We find that women's living standards, as measured by their height, improved steadily from the end of World War II through those born in 1972, hence reached adulthood in 1990. Thereafter, heights declined. Evidence on both the length and weight of babies corroborates this pattern. Their values trace a "U" shaped curve with troughs near the mid-1990s. Thus, the anthropometric results on newborn as well as for their mother point to the strains and challenges to living standards experienced during the restructuring of the post-Soviet economy. This is a general result that has become a recurring pattern: economic transitions are almost always accompanied by biological strains.     

Testing the 'free radical theory of aging' hypothesis: physiological differences in long-lived and short-lived colubrid snakes

We test the 'free radical theory of aging' using six species of colubrid snakes (numerous, widely distributed, non-venomous snakes of the family Colubridae) that exhibit long (> 15 years) or short (< 10 years) lifespans. Because the 'rate of living theory' predicts metabolic rates to be correlated with rates of aging and oxidative damage results from normal metabolic processes we sought to answer whether physiological parameters and locomotor performance (which is a good predictor of survival in juvenile snakes) mirrored the evolution of lifespans in these colubrid snakes. We measured whole animal metabolic rate (oxygen consumption Vo2), locomotor performance, cellular metabolic rate (mitochondrial oxygen consumption), and oxidative stress potential (hydrogen peroxide production by mitochondria). Longer-lived colubrid snakes have greater locomotor performance and reduced hydrogen peroxide production than short-lived species, while whole animal metabolic rates and mitochondrial efficiency did not differ with lifespan. We present the first measures testing the 'free radical theory of aging' using reptilian species as model organisms. Using reptiles with different lifespans as model organisms should provide greater insight into mechanisms of aging.     

The importance of substrate type, shading and scorching for the attractiveness of dead wood to saproxylic beetles

Modern forestry management has reduced the amount of dead wood in forest ecosystems and this has become a serious threat to flora and fauna. Efforts are therefore being made to reverse this trend but one problem is that we still lack detailed knowledge regarding the substrate requirements of many saproxylic species. In a field experiment, conducted in three forest types (forest reserve, mature managed forest and clear-cut), we evaluated the value, from a conservation perspective, of different substrate types (logs, snags and tops) of Norway Spruce, Picea abies, and if the quality of spruce logs as saproxylic habitats can be improved by simple log treatments (scorching and shading). We collected 9982 individuals representing 262 saproxylic beetle species in window traps. Both substrate type and, to a lesser extent, log treatment had a significant effect on the abundance and species richness of saproxylic beetles attracted to the different dead wood substrates. However, more importantly, the composition of the beetle assemblages differed significantly between both substrates and log treatments. Snags, logs and tops all attracted significantly different beetle assemblages and scorched logs differed from untreated control logs. Sixteen red listed species were trapped, with the highest number (11 species) being found on scorched logs. We found strong evidence that some species preferred a specific substrate type, mainly logs, in some cases treated logs (scorched or shaded), but not snags, the substrate commonly provided for conservation purposes on e.g. clear-cuts. This stresses the importance of conducting forestry in such a way that a multitude of both forest habitats and dead wood substrates are available continuously in the forest landscape to maintain biodiversity.     

A field demonstration of the costs and benefits of group living to edible and defended prey

Both theoretical and laboratory research suggests that many prey animals should live in a solitary, dispersed distribution unless they lack repellent defences such as toxins, venoms and stings. Chemically defended prey may, by contrast, benefit substantially from aggregation because spatial localization may cause rapid predator satiation on prey toxins, protecting many individuals from attack. If repellent defences promote aggregation of prey, they also provide opportunities for new social interactions; hence the consequences of defence may be far reaching for the behavioural biology of the animal species. There is an absence of field data to support predictions about the relative costs and benefits of aggregation. We show here for the first time using wild predators that edible, undefended artificial prey do indeed suffer heightened death rates if they are aggregated; whereas chemically defended prey may benefit substantially by grouping. We argue that since many chemical defences are costly to prey, aggregation may be favoured because it makes expensive defences much more effective, and perhaps allows grouped individuals to invest less in chemical defences.     

Isolation and Molecular Characterization of Acanthamoeba Strains from Dental Units in Costa Rica

Free‐living amoebae are protozoa widely distributed in nature, which can be found in a variety of environments. Four genera are recognized as causal agents of infections in humans and animals: Acanthamoeba, Naegleria, Balamuthia, and Sappinia. In this study, the presence of Acanthamoeba in dental units was determined and the isolates obtained were molecularly characterized; osmotolerance and thermotolerance assays were also performed to evaluate multiplication under these conditions, frequently associated with pathogenicity. The morphological analysis and partial sequencing of the 18S rDNA gene revealed the presence of Acanthamoeba genotype T4 in 14% of the units sampled. Osmotolerance and thermotolerance tests were positive for more than 80% of the isolates. Up to date, this is the first study that reports the detection, identification, and genotyping of Acanthamoeba isolated from dental units in Costa Rica and even in Latin‐America. Further assays to determine the potential pathogenicity of these Acanthamoeba isolates are underway.     

A genus-level taxonomic review of primitively segmented spiders (Mesothelae,Liphistiidae)

The spider suborder Mesothelae, containing a single extant family Liphistiidae, represents a species-poor and ancient lineage. These are conspicuous spiders that primitively retain a segmented abdomen and appendage-like spinnerets. While their classification history is nearly devoid of phylogenetic hypotheses, we here revise liphistiid genus level taxonomy based on original sampling throughout their Asian range, and on the evidence from a novel molecular phylogeny. By combining morphological and natural history evidence with phylogenetic relationships in the companion paper, we provide strong support for the monophyly of Liphistiidae, and the two subfamilies Liphistiinae and Heptathelinae. While the former only contains Liphistius Schiödte, 1849, a genus distributed in Indonesia (Sumatra), Laos, Malaysia, Myanmar, Thailand, we recognize and diagnose seven heptatheline genera, all but three removed from the synonymy of Heptathela: i) Ganthela Xu & Kuntner, gen. n. with the type species Ganthela yundingensis Xu, sp. n. is known from Fujian and Jiangxi, China; ii) a rediagnosed Heptathela Kishida, 1923 is confined to the Japanese islands (Kyushu and Okinawa); iii) Qiongthela Xu & Kuntner, gen. n. with the type species Qiongthela baishensis Xu, sp. n. is distributed disjunctly in Hainan, China and Vietnam; iv) Ryuthela Haupt, 1983 is confined to the Ryukyu archipelago (Japan); v) Sinothela Haupt, 2003 inhabits Chinese areas north of Yangtze; vi) Songthela Ono, 2000 inhabits southwest China and northern Vietnam; and vii) Vinathela Ono, 2000 (Abcathela Ono, 2000, syn. n.; Nanthela Haupt, 2003, syn. n.) is known from southeast China and Vietnam.     

砂质潮间带自由生活海洋线虫对缺氧的响应——微型受控生态系研究

以青岛砂质潮间带自由生活海洋线虫为研究对象,建立微型受控生态系,研究缺氧对海洋线虫群落结构和垂直分布的影响,以及环境复氧后海洋线虫群落的恢复能力。研究结果显示,海洋线虫是耐低氧的小型底栖动物类群,可通过垂直迁移来耐受缺氧造成的不利条件。但是,海洋线虫通过主动迁出而耐受缺氧条件的特性具有种的区别。研究中Pseudosteineria sp1、Rhynchonema sp1等海洋线虫通过向有氧环境的主动迁移耐受缺氧条件;Thalassironus sp1却可通过自身耐受机制抵御缺氧条件,在缺氧生境中仍能保持较高的丰度。此外,研究结果显示,当表层海洋线虫暴露于缺氧环境时,其总丰度显著降低,种类组成发生改变。Pseudosteineria sp1对缺氧环境较为敏感,可暂时性地离开沉积物进入水层;而沉积物溶解氧恢复正常后,该种可以重新回到沉积物中。Daptonema sp1成熟个体及其幼龄个体对缺氧均具有较高的耐受性,是缺氧群落的绝对优势种。D.sp3则表现出对缺氧环境较高的敏感性。环境恢复正常,线虫群落丰度及多样性增加,Neochromadora sp1和Spilophorella sp1等具有机会种的特点,首先表现出丰度和繁殖能力的增加。但是线虫群落种类组成在受测时间内并未能完全恢复,群落结构的恢复需要更长的时间。     

高住低练对游泳运动员红细胞免疫黏附功能及白细胞计数的影响

目的:了解高住低练对高水平游泳运动员血细胞天然免疫功能的影响。方法:6名女子游泳运动员进行2周高住低练,训练前、训练期间及恢复1周分别测试红细胞黏附功能、白细胞计数指标。结果:训练期间运动员红细胞C3b受体花环率(RBC-C3bRR)明显下降(P<0.05),红细胞免疫复合物花环率(RBC-ICR)明显上升(P<0.05),恢复1周后指标回归正常;白细胞、粒细胞在训练期总体上呈显著性下降(P<0.05),训练结束1周后恢复;单核细胞和淋巴细胞训练期间总体趋势是下降,训练结束1周后仍未恢复。结论:红细胞和粒细胞的天然免疫功能下降快,恢复快,但淋巴细胞、单核细胞计数恢复较慢,运动员对本次训练基本适应。