Survival In Harsh Environments Research Articles

The pathophysiology of survival in harsh environments.

An individual's ability to survive harsh conditions might depend on its available energy, and also on its health, which is expected to decline as conditions deteriorate. Yet, we know little about how health and energy expenditure are shaped by harsh environmental conditions in free-living vertebrates. Here, we studied how African striped mice (Rhabdomys pumilio) that survived summer droughts differed in their energy expenditure and health from non-survivors. Specifically, we tested whether: (1) survivors' and non-survivors' health and energy expenditure differed before environmental conditions declined; (2) non-survivors were in poorer health and had greater energy expenditure than survivors when conditions were harshest; (3) non-survivors' health deteriorated more than that of survivors as conditions deteriorated; and (4) survivors recovered once conditions improved. Survivors and non-survivors' health was assessed using VetsScan ABAXIS, while energy expenditure was measured as resting metabolic rate (RMR). Before conditions declined, non-survivors had lower energy stores and higher globulin levels than survivors. As conditions became harsher, survivors' and non-survivors' health deteriorated but only non-survivors showed signs of permanent pathology (increased glucose and decreased globulin). Once conditions improved, survivors' health improved but was not fully restored (increased alanine aminotransferase and decreased globulin). Furthermore, while survivors and non-survivors had similar RMR before conditions became harsh; their levels diverged considerably when conditions deteriorated, with survivors having a decreased RMR and non-survivors having an increased RMR. Our results show that an individual's health before facing an environmental challenge and the way it regulates its RMR influences its ability to maintain homeostasis when conditions become more taxing.

桑及菌根桑在库区消落带的生态重建功能及应用潜力

PDF HTML阅读 XML下载 导出引用 引用提醒 桑及菌根桑在库区消落带的生态重建功能及应用潜力 DOI: 10.5846/stxb201408211660 作者: 作者单位: 南方山地园艺学教育部重点实验室,南方山地园艺学教育部重点实验室,南方山地园艺学教育部重点实验室,南方山地园艺学教育部重点实验室,西南大学蚕学与系统生物学研究所,西南大学蚕学与系统生物学研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 现代农业产业技术体系专项(CARS-22-ZJ0503);重庆市研究生教育教学改革研究项目(yjg143028) Ecological reconstruction function and potential application of mulberry and mycorrhizal mulberry in the Three Gorges Reservoir area Author: Affiliation: Key Laboratory of Horticulture Science for Southern Mountainous Regions,Ministry of Education,College of Horticulture and Landscape Architecture,Department of Agriculture,Southwest University,Key Laboratory of Horticulture Science for Southern Mountainous Regions,Ministry of Education,College of Horticulture and Landscape Architecture,Department of Agriculture,Southwest University,Key Laboratory of Horticulture Science for Southern Mountainous Regions,Ministry of Education,College of Horticulture and Landscape Architecture,Department of Agriculture,Southwest University,Key Laboratory of Horticulture Science for Southern Mountainous Regions,Ministry of Education,College of Horticulture and Landscape Architecture,Department of Agriculture,Southwest University,Institute of Sericulture and Systems Biology,Southwest University,Institute of Sericulture and Systems Biology,Southwest University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:三峡工程在提供丰富水电资源造福人类的同时,也引发了一些生态环境问题,对库区环境、生物、气候以及人们的生活都产生了不同程度的影响。桑树休眠和生长发育节律与库区水体涨落规律的反向偶联,桑的菌根结构在改善根际土质量,促进桑树水分和养分吸收,增强桑树对盐碱、干旱、重金属的耐受性,提高幼苗的存活率,促进桑苗生长,促进植物群落正向演替等生态过程中发挥着重要的作用。分析了三峡库区消落带周期性水淹的生态特征和岸生植物生态恢复障碍,综述了桑及菌根桑在消落带的生态特性和应用潜力,最后提出了菌根桑生物技术的应用所面临的新课题和挑战。 Abstract:The construction of the Three Gorges Dams in the Yangtze River in the 1990s has induced profound impacts on the environment and biodiversity in the reservoir region, although these hydroelectric dams have supplied an enormous amount of hydropower resources and electricity to all of China. One main example of such environmental effects is the gradual degeneration or death of plants under waterlogging or flooding along the reservoir areas after implementation of the dams. The river banks, which serve as hydro-fluctuation belts, have been annually fluctuated for three to six months at a time, leading to low soil fertility and high erodibility. Meanwhile, some adaptive vegetation with low water-holding capacity has persisted in the drought soil. However, these distinctive characteristics are major restoration obstacles in the hydro-fluctuation belt area, even for plants with strong vitality. Mulberry (Morus alba L.), a plant native to China, has not only economic importance to the Chinese silk industry but also ecological benefits to its plantation regions in China. Studies have shown that mulberry trees have strong ecological adaptation ability and ecological restoration potential, as they are able to hold water and prevent soil erosion with their extensive root systems. These traits facilitate mulberry survival in harsh environments, particularly when they have established symbiotic associations with beneficial soil microorganisms such as arbuscular mycorrhizal (AM) fungi. On the other hand, the application of AM fungi to ecological restoration has been recently proposed. In general, AM fungi and their massive underground hyphal networks could enhance the uptake of plant nutrients and water, formation of soil aggregates, and resistance to biotic and abiotic stresses. Studies have further shown that AM fungi have significant impacts on the soil microflora community and on plant community compositions. As a result, mulberry trees colonized by AM fungi could have the capacity to improve the soil rhizosphere quality, promote the uptake and transportation of minerals and water, and enhance the tolerance to drought and waterlogging. Therefore, mycorrhizal mulberry could promote leaf development and tree performance for the food resource of silk worms as well as function in ecological restoration on the river bank areas of the Three Gorges Reservoir. As the growth rate of mulberry is inversely related to fluctuations of water level in the reservoir, the planting of AM fungi-colonized mulberry trees is considered to be a potential ecological restoration strategy to deal with both the waterlogging in winter or early spring and the drought in summer at the fluctuation belts or in other fragile ecosystems of the Three Gorges Reservoir. In this paper, we review the ecological characteristics and plant growth obstacles faced during the water fluctuation period on the river banks along the Three Gorges Reservoir areas of the Yangtze River, and then propose the potential application of the mycorrhizal mulberry for ecological reconstruction of the hydro-fluctuation belts of these areas. 参考文献 相似文献 引证文献

Comparative proteomic analysis by iTRAQ-2DLC-MS/MS provides insight into the key proteins involved in Cronobacter sp. biofilm formation

Cronobacter sp., an opportunistic foodborne pathogen, can cause high mortality in neonatal and premature infants because this pathogen is associated with powdered infant formula (PIF) contamination. Biofilm formation is recognized as the most effective means to help Cronobacter survive throughout the long shelf-life of PIF, thus promoting resistance to cleaning agents and disinfectants. Crystal violet (CV) staining and fluorescence microscopy analyses were used to compare the biofilm formation ability among different Cronobacter strains, and then the weak biofilm former Cronobacter sakazakii ATCC 29544 and the strong biofilm former Cronobacter dubliniensis DSM 18707 were selected for further proteomic analysis. Two-dimensional liquid chromatography–tandem mass spectrometry, which was coupled with isobaric tags for relative and absolute quantification (iTRAQ) labeling, was employed to quantitatively identify the proteins that were differentially expressed in C. sakazakii ATCC 29544 compared to C. dubliniensis DSM 18707. In total, 1190 proteins were detected. Gene Ontology (GO) analysis indicated that these differentially expressed proteins are related to biological binding, cell structure, signal transduction, cell adhesion, and cellular interaction. Among these differential proteins, the expression levels of 177 non-redundant proteins were altered significantly by more than 5-fold, with 96 up-regulated proteins and 81 down-regulated. This study provides important information regarding the cellular requirements for the underlying mechanism of Cronobacter biofilm formation and its survival in harsh environments.

Stress Responses in Probiotic Lactobacillus casei

Survival in harsh environments is critical to both the industrial performance of lactic acid bacteria (LAB) and their competitiveness in complex microbial ecologies. Among the LAB, members of the Lactobacillus casei group have industrial applications as acid-producing starter cultures for milk fermentations and as specialty cultures for the intensification and acceleration of flavor development in certain bacterial-ripened cheese varieties. They are amongst the most common organisms in the gastrointestinal (GI) tract of humans and other animals, and have the potential to function as probiotics. Whether used in industrial or probiotic applications, environmental stresses will affect the physiological status and properties of cells, including altering their functionality and biochemistry. Understanding the mechanisms of how LAB cope with different environments is of great biotechnological importance, from both a fundamental and applied perspective: hence, interaction between these strains and their environment has gained increased interest in recent years. This paper presents an overview of the important features of stress responses in Lb. casei, and related proteomic or gene expression patterns that may improve their use as starter cultures and probiotics.

Role of PhoP–PhoQ two-component system in pellicle formation, virulence and survival in harsh environments of Dickeya dadantii 3937

We investigated pellicle (i.e., the bacterial network formed at the air–liquid interface to block the surface of a standing culture) formation governed by the PhoP–PhoQ two-component system (TCS) and its role in susceptibility to harsh environments and virulence of the phytopathogen Dickeya dadantii (formerly Erwinia chrysanthemi) 3937. Pellicle formation was dramatically reduced in phoP and phoQ mutants compared to the wild type in low (10 μM) magnesium, but was greater and more robust in high (10 mM) magnesium. Pellicles formed by the wild type and by the mutants in low magnesium were composed of cellulose, but pellicles formed by these mutants at high magnesium condition were composed of cellulose and a cellulase-resistant polymer. In the wild type at low magnesium, expression of bcsABCD (cellulose biosynthesis operon), adrA (a GGDEF protein) and fliC (a flagellar component called flagellin) increased significantly, whereas expression of these genes was elevated in the mutants at high magnesium condition. Thus, PhoP–PhoQ TCS may regulate pellicle formation by transcriptional control of bcsABCD, adrA and fliC. Overall, pellicle-associated bacteria were more tolerant to adverse environmental cues and more virulent than aerobically grown cells. Furthermore, at low magnesium, wild-type bacteria associated with a pellicle were more resistant to stress environments and more virulent than the pellicle-associated cells of the mutants. Intriguingly, the reverse relationship is found at high magnesium. Thus, formation of pellicle may be required for survival and virulence of D. dadantii 3937.

Nursery location and potassium enrichment in Aleppo pine stock 2. Performance under real and hydrogel-mediated drought conditions

Summary This work investigates Aleppo pine performance under severe drought conditions according to seedling size and nutritional status, with special emphasis on potassium. The interaction of drought ameliorating measures such as hydrogels is also studied. Seven fertilization treatments applied in two nursery locations provided 14 stocklots, resulting in different seedling sizes for each nutrient concentration and vice versa. Stocklots were tested in a greenhouse experiment and a harsh site plantation experiment. In the greenhouse, seedlings given two hydrogel doses (0.01 and 0.1 per cent w/w) plus a control were allowed to dry and survival and soil moisture were measured. In parallel to this trial, the effects of hydrogel dosage, brand and soil texture on soil water properties were tested in a laboratory. Results show that large stock survived signifi cantly better than conventionally sized stock in both experiments: 37 and 27 per cent more in the greenhouse and harsh site, respectively. Despite presenting wide variation, macronutrient concentration was not related to survival for a given size. Hydrogel effect on soil water was different according to factors, although in all cases , its effect diminished at suction tensions higher than 30 kPa. Results demonstrate the overriding effect of size over nutritional status on seedling survival in harsh environments.

Lipotoxin F of Pseudomonas aeruginosa is an AlgU-dependent and alginate-independent outer membrane protein involved in resistance to oxidative stress and adhesion to A549 human lung epithelia

Chronic lung infection with P. aeruginosa and excessive neutrophil-associated inflammation are major causes of morbidity and mortality in patients with cystic fibrosis (CF). Overproduction of an exopolysaccharide known as alginate leads to the formation of mucoid biofilms that are resistant to antibiotics and host defences. Alginate overproduction or mucoidy is controlled by a stress-related ECF sigma factor AlgU/T. Mutation in the anti-sigma factor MucA is a known mechanism for conversion to mucoidy. Recently, we showed that inactivation of a kinase (KinB) in nonmucoid strain PAO1 results in overproduction of alginate. Here, we report the initial characterization of lipotoxin F (LptF, PA3692), an OmpA-like outer membrane protein that exhibited increased expression in the mucoid PAO1kinB mutant. The lipotoxin family of proteins has been previously shown to induce inflammation in lung epithelia, which may play a role in CF disease progression. Expression of LptF was observed to be AlgU-dependent and upregulated in CF isolates. Deletion of lptF from the kinB mutant had no effect on alginate production. Deletion of lptF from PAO1 caused a differential susceptibility to oxidants that can be generated by phagocytes. The lptF and algU mutants were more sensitive to hypochlorite than PAO1. However, the lptF mutant displayed increased resistance to hydrogen peroxide. LptF also contributed to adhesion to A549 human lung epithelial cells. Our data suggest that LptF is an outer membrane protein that may be important for P. aeruginosa survival in harsh environments, including lung colonization in CF.

Microgravity and the human exploration of space technology challenges

If humans are to explore space beyond low-earth orbit, their health and welfare must be ensured, not only for survival in harsh environments but also so that they can work productively. The requisite technologies, and human physiology itself, are subject to reduced levels of gravity that are indigenous to space travel. Numerous studies have shown that it will require many years of intensive research to develop reliable, efficient, and self-sustaining technologies and to understand the effects of gravity on humans. The research community that was developed to provide crucial specific information has essentially been deactivated because of budget constraints. Thus, the great engineering challenge—to develop advanced and novel technologies that will enable further space exploration—will remain for future generations.

MglA Regulates Francisella tularensis subsp. novicida ( Francisella novicida ) Response to Starvation and Oxidative Stress

MglA is a transcriptional regulator of genes that contribute to the virulence of Francisella tularensis, a highly infectious pathogen and the causative agent of tularemia. This study used a label-free shotgun proteomics method to determine the F. tularensis subsp. novicida (F. novicida) proteins that are regulated by MglA. The differences in relative protein amounts between wild-type F. novicida and the mglA mutant were derived directly from the average peptide precursor ion intensity values measured with the mass spectrometer by using a suite of mathematical algorithms. Among the proteins whose relative amounts changed in an F. novicida mglA mutant were homologs of oxidative and general stress response proteins. The F. novicida mglA mutant exhibited decreased survival during stationary-phase growth and increased susceptibility to killing by superoxide generated by the redox-cycling agent paraquat. The F. novicida mglA mutant also showed increased survival upon exposure to hydrogen peroxide, likely due to increased amounts of the catalase KatG. Our results suggested that MglA coordinates the stress response of F. tularensis and is likely essential for bacterial survival in harsh environments.

(Genome) Size Matters

(Genome) Size Matters

Long‐term survival of Legionella pneumophila associated with Acanthamoeba castellanii vesicles

Legionella pneumophila, the causative agent of Legionnaires' disease, is ubiquitously found in aquatic environments, associated with free living amoebae. Trophozoite forms of the genus Acanthamoeba have been shown to support the intracellular growth of Legionella while it has been proposed that cyst forms are related to survival in harsh environments. This underlines that amoebae are of primary importance in Legionella spreading. In this study, we followed the survival of L. pneumophila Lens over 6 months in a poor medium, with or without Acanthamoeba castellanii. The results demonstrated that L. pneumophila Lens could survive for at least 6 months in association with A. castellanii and that cultivable bacteria are to be found within expelled vesicles rather than within cysts. Our findings suggest that vesicles might be further studied in order to elucidate their production and their role in the environmental spreading of Legionella.

A review of the behavioural and physiological adaptations of hill and lowland breeds of sheep that favour lamb survival

Extensively managed animals, often living in harsh and unfavourable environments, need specific adaptations that promote survivability. This is particularly important at parturition and during the neonatal period, when ewe and lamb mortality is highest. To understand the survival adaptations of extensively managed breeds, we reviewed the behavioural and physiological adaptations of ewes and lambs of hill (extensive) breeds of sheep to lowland (intensively managed) breeds during pregnancy, parturition and lactation. Hill sheep have a smaller average litter size than lowland sheep but carry a significantly heavier litter (proportional to their own body weight), which may be achieved through more efficient placental exchange. Isolation seeking at parturition by the ewe is affected by maternal experience and familiarity with the environment. However, an increase in domestication and intensification appear to have led to a decrease in isolation seeking at parturition. Hill ewes have a shorter labour, and an easier delivery than lowland ewes, which may be partly related to pelvis dimensions and to lamb characteristics. Hill ewe breeds lick their newborn lambs more than lowland ewes immediately after birth, and have a higher rate of low-pitched bleating (both important behaviours for the development of ewe–lamb attachment). These behavioural differences result in better ewe–lamb recognition 24 h after birth in hill ewes, and closer ewe–lamb spatial relationships during lactation. Hill ewes are more aware of the presence of their lambs during lactation, which may aid defence of the lamb against predators. Hill lambs are quicker to stand and suck after birth than lowland lambs, and show better maternal recognition than lowland lambs. Hill lambs also maintain higher rectal temperatures after birth than lowland lambs and have better cold resistance. Better thermoregulation is partly related to birthcoat characteristics, but is also accompanied by higher thyroid hormone concentrations (important for endogenous heat production) in hill than lowland lambs. The colostrum of hill ewes has higher lipid content than lowland ewes, which may also contribute to improved thermoregulation. This suggests that hill sheep, adapted to extensive management systems, have evolved more efficient behavioural and physiological mechanisms to enhance lamb survivability in harsh environments than have intensively managed lowland sheep breeds.

Kinetic Stability and Crystal Structure of the Viral Capsid Protein SHP

SHP, the capsid-stabilizing protein of lambdoid phage 21, is highly resistant against denaturant-induced unfolding. We demonstrate that this high functional stability of SHP is due to a high kinetic stability with a half-life for unfolding of 25 days at zero denaturant, while the thermodynamic stability is not unusually high. Unfolding experiments demonstrated that the trimeric state (also observed in crystals and present on the phage capsid) of SHP is kinetically stable in solution, while the monomer intermediate unfolds very rapidly. We also determined the crystal structure of trimeric SHP at 1.5A resolution, which was compared to that of its functional homolog gpD. This explains how a tight network of H-bonds rigidifies crucial interpenetrating residues, leading to the observed extremely slow trimer dissociation or denaturation. Taken as a whole, our results provide molecular-level insights into natural strategies to achieve kinetic stability by taking advantage of protein oligomerization. Kinetic stability may be especially needed in phage capsids to allow survival in harsh environments.