Periods Of Adverse Conditions Research Articles

Fungal biodeterioration and preservation of cultural heritage, artwork, and historical artifacts: extremophily and adaptation.

SUMMARYFungi are ubiquitous and important biosphere inhabitants, and their abilities to decompose, degrade, and otherwise transform a massive range of organic and inorganic substances, including plant organic matter, rocks, and minerals, underpin their major significance as biodeteriogens in the built environment and of cultural heritage. Fungi are often the most obvious agents of cultural heritage biodeterioration with effects ranging from discoloration, staining, and biofouling to destruction of building components, historical artifacts, and artwork. Sporulation, morphological adaptations, and the explorative penetrative lifestyle of filamentous fungi enable efficient dispersal and colonization of solid substrates, while many species are able to withstand environmental stress factors such as desiccation, ultra-violet radiation, salinity, and potentially toxic organic and inorganic substances. Many can grow under nutrient-limited conditions, and many produce resistant cell forms that can survive through long periods of adverse conditions. The fungal lifestyle and chemoorganotrophic metabolism therefore enable adaptation and success in the frequently encountered extremophilic conditions that are associated with indoor and outdoor cultural heritage. Apart from free-living fungi, lichens are a fungal growth form and ubiquitous pioneer colonizers and biodeteriogens of outdoor materials, especially stone- and mineral-based building components. This article surveys the roles and significance of fungi in the biodeterioration of cultural heritage, with reference to the mechanisms involved and in relation to the range of substances encountered, as well as the methods by which fungal biodeterioration can be assessed and combated, and how certain fungal processes may be utilized in bioprotection.

Transcriptomic and Metabolomic Analyses Reveal Inhibition of Hepatic Adipogenesis and Fat Catabolism in Yak for Adaptation to Forage Shortage During Cold Season.

Animals have adapted behavioral and physiological strategies to conserve energy during periods of adverse conditions. Hepatic glucose is one such adaptation used by grazing animals. While large vertebrates have been shown to have feed utilization and deposition of nutrients—fluctuations in metabolic rate—little is known about the regulating mechanism that controls hepatic metabolism in yaks under grazing conditions in the cold season. Hence, the objective of this research was to integrate transcriptomic and metabolomic data to better understand how the hepatic responds to chronic nutrient stress. Our analyses indicated that the blood parameters related to energy metabolism (glucose, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, lipoprotein lipase, insulin, and insulin-like growth factor 1) were significantly (p < 0.05) lower in the cold season. The RNA-Seq results showed that malnutrition inhibited lipid synthesis (particularly fatty acid, cholesterol, and steroid synthesis), fatty acid oxidation, and lipid catabolism and promoted gluconeogenesis by inhibiting the peroxisome proliferator-activated receptor (PPAR) and PI3K-Akt signaling pathways. For metabolite profiles, 359 metabolites were significantly altered in two groups. Interestingly, the cold season group remarkably decreased glutathione and phosphatidylcholine (18:2 (2E, 4E)/0:0). Moreover, integrative analysis of the transcriptome and metabolome demonstrated that glycolysis or gluconeogenesis, PPAR signaling pathway, fatty acid biosynthesis, steroid biosynthesis, and glutathione metabolism play an important role in the potential relationship between differential expression genes and metabolites. The reduced lipid synthesis, fatty acid oxidation, and fat catabolism facilitated gluconeogenesis by inhibiting the PPAR and PI3K-Akt signaling pathways to maintain the energy homeostasis of the whole body in the yak, thereby coping with the shortage of forages and adapting to the extreme environment of the Qinghai-Tibetan Plateau (QTP).

Depth-Dependent Spatiotemporal Dynamics of Overwintering Pelagic Microcystis in a Temperate Water Body.

Cyanobacteria in the genus Microcystis are dominant components of many harmful algal blooms worldwide. Their pelagic–benthic life cycle helps them survive periods of adverse conditions and contributes greatly to their ecological success. Many studies on Microcystis overwintering have focused on benthic colonies and suggest that sediment serves as the major inoculum for subsequent summer blooms. However, the contemporaneous overwintering pelagic population may be important as well but is understudied. In this study, we investigated near-surface and near-bottom pelagic population dynamics of both microcystin-producing Microcystis and total Microcystis over six weeks in winter at Dog Lake (South Frontenac, ON, Canada). We quantified relative Microcystis concentrations using real-time PCR. Our results showed that the spatiotemporal distribution of overwintering pelagic Microcystis was depth dependent. The abundance of near-bottom pelagic Microcystis declined with increased depth with no influence of depth on near-surface Microcystis abundance. In the shallow region of the lake (<10 m), most pelagic Microcystis was found near the lake bottom (>90%). However, the proportion of near-surface Microcystis rose sharply to over 60% as the depth increased to approximately 18 m. The depth-dependent distribution pattern was found to be similar in both microcystin-producing Microcystis and total Microcystis. Our results suggest the top of the water column may be a more significant contributor of Microcystis recruitment inoculum than previously thought and merits more attention in early CHAB characterization and remediation.

Quantifying energetic and fitness consequences of seasonal heterothermy in an Arctic ungulate.

Animals have adapted behavioral and physiological strategies to conserve energy during periods of adverse conditions. Heterothermy is one such adaptation used by endotherms. While heterothermy—fluctuations in body temperature and metabolic rate—has been shown in large vertebrates, little is known of the costs and benefits of this strategy, both in terms of energy and in terms of fitness. Hence, our objective was to model the energetics of seasonal heterothermy in the largest Arctic ungulate, the muskox (Ovibos moschatus), using an individual‐based energy budget model of metabolic physiology. We found that the empirically based drop in body temperature (winter max ~−0.8°C) overwinter in adult females resulted in substantial fitness benefits in terms of reduced daily energy expenditure and body mass loss. Body mass and energy reserves were 8.98% and 14.46% greater in modeled heterotherms compared to normotherms by end of winter. Based on environmental simulations, we show that seasonal heterothermy can, to some extent, buffer the negative consequences of poor prewinter body condition or reduced winter food accessibility, leading to greater winter survival (+20%–30%) and spring energy reserves (+10%–30%), and thus increased probability of future reproductive success. These results indicate substantial adaptive short‐term benefits of seasonal heterothermy at the individual level, with potential implications for long‐term population dynamics in highly seasonal environments.

Does the return-state-varying relationship between risk and return matter in modeling the time series process of stock return?

This paper empirically investigates the time series behavior of stock returns and volatility and the relationship between return premium and stock market risk by utilizing a TSV-GARCH(p,q)-Risk-Mean model. The empirical findings of this paper provide evidence for the distinct driving forces in mean and volatility and the state-dependent tradeoff between risk and return. The empirical results demonstrate that the stock market displays four types of dynamic processes (high-return–low-volatility state, low-return–low-volatility state, high-return–high-volatility state, and low-return–high-volatility state) and that the structural change process of stock market returns is greatly at odds with that of stock market volatility. The TSV-GARCH(1,1)-Risk-Mean model provides better in-sample fit compared to the conventional GARCH(p,q) and regime-switching GARCH(p,q) models. Moreover, the relationship between excess returns and risk is positive, and the intensity of this positive relationship during periods of bear market is significantly higher than that during periods of bull market, which provides supporting evidence for the countercyclical risk premiums hypothesis in which the magnitude of compensation for enduring risk is weaker during periods of favorable financial conditions than during periods of adverse conditions.

Out in the wash: spatial ecology of a temperate marine shallow rocky-reef species derived using acoustic telemetry

Characterising the movement and habitat affinities of fish is a fundamental component in understanding the functioning of marine ecosystems. A comprehensive array of acoustic receivers was deployed at two near-shore coastal sites in south-eastern Australia, to examine the movements, activity-space size and residency of a temperate rocky-reef, herbivorous species Girella elevata. Twenty-four G. elevata individuals were internally tagged with pressure-sensing acoustic transmitters across these two arrays and monitored for up to 550 days. An existing network of coastal receivers was used to examine large-scale movement patterns. Individuals exhibited varying residency, but all had small activity-space sizes within the arrays. The species utilised shallow rocky-reef habitat, displaying unimodal or bimodal patterns in depth use. A positive correlation was observed between wind speed and the detection depth of fish, with fish being likely to move to deeper water to escape periods of adverse conditions. Detection frequency data, corrected using sentinel tags, generally illustrated diurnal behaviour. Patterns of habitat usage, residency and spatial utilisation highlighted the susceptibility of G. elevata to recreational fishing pressure. The results from the present study will further contribute to the spatial information required in the zoning of effective marine protected areas, and our understanding of temperate reef fish ecology.

Mechanisms and molecular adaptation to extreme dehydration in tardigrades: Hsp gene expression in Milnesium tardigradum

The tardigrade Milnesium tardigradum Doyere 1840 is a well-known cosmopolitan species and a typical inhabitant of moist environments which facilitate the animal's gaseous exchange and avoid desiccation. However, such habitats frequently undergo seasonal changes that impact animal life. M. tardigradum is able to survive these periods of adverse conditions due to its ability to enter into a anhydrobiotic state. In adverse environments, all terrestrial and freshwater tardigades arrest their metabolic activity and get dehydrated to form the tun state. In the anhydrobiotic stage, tardigrades showextraordinary tolerance tophysical extremes includinghigh-energy radiation, immersion inorganic solvents, brief exposure to high temperatures and prolonged exposure to indefinitely low temperatures. When environmental conditions are adequate, tuns rehydrate and the animals resume metabolic activity. Drying of cells generally leads to massive damage to cellular membranes and proteins, which eventually results in cell death and, consequently, in the death of the entire organism.Heat shock proteins and theirmolecular partners are known to play diverse roles, even in unstressed cells, in successful folding, assembly, intracellular localization, secretion, regulation, and degradation of other proteins. In this study, a complementary focus is on tardigrades undergoing stress in nature and on the roles of stress genes of the hsp10, hsp20/30, hsp40, hsp60, hsp70 and hsp90 family in the stress physiology ofwhole organisms in different life history stages. This study is part of the project www.FUNCRYPTA.de, funded by the German Federal Ministry of Education and Research, BMBF (0313838).

Quiescent gemmules of the freshwater sponge, Spongilla lacustris (Linnaeus, 1759), contain remarkably high levels of Hsp70 stress protein and hsp70 stress gene mRNA

With the onset of changing environmental conditions in autumn, the freshwater sponge Spongilla lacustris (Linnaeus, 1759) produces resistant stages (gemmules) which are in the state of quiescence. Gemmules stored at 8 degrees C remained quiescent; however, germination occurred within 24 hr after the water temperature was increased to 22.5 degrees C. Sponges hatched through the micropyle and subsequently built new spicules and a new canal system. The molecular and biochemical mechanisms which enable the gemmules to survive long periods of adverse conditions are not known. For the first time we focused on the role of the stress protein Hsp70 and the expression of hsp70 mRNA in S. lacustris during the development of gemmules in the state of quiescence into growing sponges. The partial sequence of hsp70 seems to be a true hsp gene since transcription could be clearly enhanced by temperature elevation. The results showed a large pool of cellular Hsp70 and hsp70 mRNA in gemmules during the state of quiescence. Within hours after a temperature trigger, the Hsp70 level decreased slowly and reached approximately the level of an adult sponge. Hsp70 presumably allows gemmules to stabilize their proteins and membranes during dormancy from autumn to spring when water temperatures change.

Macrophage migration inhibitory factor ( mif) transcription is significantly elevated in Caenorhabditiselegans dauer larvae

Macrophage migration inhibitory factor (MIF) from vertebrate species is a molecule that exerts a wide-range of effects in inflammatory responses, cell activation and cell differentiation. Several species of parasitic nematodes have been shown to express genes encoding orthologues of the mammalian MIF that appear to play a key role in immune evasion by modifying the activity of host cells. In addition, MIF accumulates in nematode somatic cells where its role has not yet been defined. In order to identify the role that MIF plays in the cell biology of nematodes, we have characterized the members of the mif gene family in the free-living species Caenorhabditis elegans. Unlike the single mif gene found in humans and mice, C. elegans expresses four distinct mif genes: Ce- mif-1, Ce- mif-2, Ce-mif-3 and Ce-mif-4. The Ce-MIF proteins are between 15–30% identical to each other, 34–38% identical to the MIFs from the parasitic nematode Brugia malayi, and 22–35% identical to mammalian MIFs. The transcription of Ce- mif-2 and Ce- mif-3, but not Ce-mif-1, was upregulated >100-fold compared to L2 levels when the worms entered the dauer stage. The transcription levels of Ce- mif-2 and Ce- mif-3 fell to near baseline a few hours after exit from dauer. Ce-MIF/GFP transgenic animals and immunostaining were used to demonstrate that the main sites of MIF production are in the hypodermis, body wall muscles and in the nuclei of developing embryos. The results suggest a role for C. elegans MIF in cellular maintenance during periods of adverse conditions that lead to developmental arrest.

Strategies of emergence from diapause for cyclopoid copepods in a temporary pond

Many cyclopoid copepods employ diapause to survive periods of adverse conditions. Because emergence from diapause is irreversible, replenishment of the diapausing population depends on production of a new generation of diapausing animals. We hypothesized that cyclopoid copepods in Rainbow Bay, a temporary pond in South Carolina, USA, would use environmental cues to limit emergence to hydroperiods long enough to allow production of diapausing offspring. To test this hypothesis, we used classification trees to help us identify patterns of emergence. The data set included 16 hydroperiods over five years. From the emergence patterns for the copepods, we inferred five strategies: 1) emergence early in the hydroperiod in all seasons (Acanthocyclops robustus and Microcyclops sp.); 2) emergence early in the hydroperiod in fall, winter, or spring (Diacyclops crassicaudis brachycercus and Diacyclops haueri); 3) emergence in spring, summer, or fall (Macrocyclops fuscus); 4) emergence in long photoperiod (Tropocyclops extensus); and 5) emergence in late summer (Mesocyclops americanus). We tested reliability of the inferred emergence strategies with a 15-yr record of 50 hydroperiods at the pond. Generally, the results do not support our hypothesis. For strategies 1-4, production of diapausing offspring was possible in only 50-61 % of emergences, but in 13-14 of 15 yrs. For strategy 5, production of diapausing offspring was possible in 90 % of emergences, but in only 8 of 15 yrs. We conclude that reserve populations of diapausing copepods must reduce the demographic impact of emergences into hydroperiods too short for production of diapausing offspring.

Sahelian woody vegetation in S�n�gal

Structure and composition of woody vegetation in Sahelian forest types (not including riparian and riverine types) were studied in Senegal. The application of classification and ordination resulted in the recognition of seven distinctive woody community types, related to soil and precipitation gradients. The described vegetation types only contained four strictly Saharan species, the rest being of Sahelian and Soudanean affinity, so a floristic change from savanna to desert vegetation after two decades of drought could not be confirmed. Tree density was lower in the northern part than earlier, possibly an indication of degradation. Rejuvenation was greatest at the northernmost arenosolic stations, but low in the southern, ferrouginous areas. This presumably demonstrates the resilience of North-Sahelian vegetation, at the moment being in a dynamic rejuvenation phase, after a period of adverse conditions.

The Functional Morphology of Turf-Forming Seaweeds: Persistence in Stressful Marine Habitats

Many seaweeds that occur in physically stressful habitats or habitats subject to mod- erate herbivory grow as colonial turfs rather than as spatially separated individuals. The turf growth form is energetically expensive (the net production per gram ash free dry mass of turfs being 33-61% lower than that of individuals), but turfs suffer less physiological damage during desiccating low tides and lose less biomass to herbivores. The upper portions of turf-forming species show significantly greater rates of apparent photosynthesis and dark respiration than do the lower portions. This spatial partitioning of photosynthetic activity decreases the energetic cost of the turf arrangement and may allow basal portions to function as persistent resting stages during periods of adverse conditions when uprights cannot be maintained. Turf-forming species are specialized for areas that are subject to moderate grazing pressure and physical stresses. They are dependent upon these factors to prevent their competitive exclusion by more productive, but less resistant, seaweeds. Damage to apical por- tions causes increased branching that results in a more tightly compacted turf. Algae that regenerate in this way can adjust their growth form in accordance with varying levels of disturbance encountered in different habitats and thus incur the minimal cost consistent with survival in that area. For seaweeds occurring in stressful habitats, selection has favored characteristics that increase persistence in space and time even though these involve considerable losses in competitive ability and productivity.

Transmission of Plant-Pathogenic Viruses by Aphids

Although many new vectors of plant viruses have been discovered dur­ ing the past decade including nematodes and fungi, aphids stilI remain the taxon that transmits a greater number and variety of viruses than does any other group of organisms. This may partly be explained by their way of life, which is specialized to use food to the full when it is plentiful and suffer the least loss when it is lacking. They reproduce by parthenogenesis, viviparously, and rapidly on susceptible lush vegetation, and then have a short period of sexual activity sufficient to produce eggs that withstand long periods of adverse conditions, and for beneficial mutations to survive. Muta­ tions are many because of the very large populations aphids achieve, and these mutations help them to adapt to changing conditions of climate and host plants. Hence, they have been able to meet changes in agriculture and become ubiquitous in crops of the temperate region. Viruses, which multiply very much faster and attain larger populations than do aphids, have also become adapted efficiently to agricultural condi­ tions and have exploited different kinds of aphid behavior for their trans­ mission. These relationships seem to have evolved around three kinds of aphid behavior: 1. Host selection. Aphids make brief, shallow probes into a plant after migration or other movements between plants. 2. Colony estab­ lishment. Invading alatae of some species deposit a few larvae on each of several instead of establishing a single large colony on one plant. 3. Dispersal of population. After colonies of apterous alienicolae have be­ come dense alatae develop which move within and be. tween crops, establish­ ing new colonies. This insures against extinction of the race by overpopula­ tion and spreads viruses from the parent plants to new hosts. Watson & Roberts (178) and Sylvester (153) separated three categories of viruses which they call nonpersistent, semipersistent, and persistent, ac­ cording to the period during which feeding aphids remain infective after acquiring virus, respectively, one hour, one to three days, and an indefinite number of weeks.

Effects of early drought and transplanting on the subsequent development of the tobacco plant

Detailed studies were made of the growth of tobacco plants during and after the experimental imposition of water stresses similar to those of commercial hardening and transplanting. During water stress (due to root damage, drought, or both) all growth rates were depressed, but, a short time after the relief of stress, relative leaf expansion rates, net assimilation rates, and relative growth rates rose to higher values than were reached by untreated plants at comparable stages of development. As a result, all stressed plants rapidly recovered from their period of adverse conditions. The plants that had originally been subjected to the most severe treatments overhauled those that had suffered less and finally acquired the greatest total leaf areas and dry weights. The increase was due to: (1) a change in the distribution of leaf surfaces, which occurred when leaf initiation was retarded relative to leaf expansion and resulted in increased growth of the lower leaves; (2) a delay in flower initiation, which took place at a higher node, increased the number of leaves, and prolonged the period of vegetative growth.

STUDIES OF THE CLOVE TREE

A detailed study was made of the histology of apparently healthy clove trees and of trees expected to die from sudden death disease, in an attempt to find either a diagnostic character of the disease or some indication of a possible pathogen.The apparently healthy clove tree differs from a typical dicotyledon in a number of ways. This is especially true of the vascular system where, not only are the bundles bicollateral, but, in the stem, secondary thickening occurs in the internal phloem, necrosis of the first formed cells keeping pace with the production of new cells. A definite cambium is found only to the exterior of the xylem and this is exceptionally narrow and the cells have very delicate walls. Phloem necrosis may occur in any part of the tree. The development and lignification of the xylem is very uneven, but this seems to bear no relation to the season. Tyloses are formed in the vessels of the root and, to a less extent, in those of the stem. Starch reserves are usually small, but large quantities of tannins, oils and calcium oxalate are secreted in all tissues. The oil may be contained in special schizogenous glands which are abundant in the aerial parts of the tree. Much mechanical tissue, consisting of fibres and stone cells, is formed in the pith and cortex of the stem and in the phloem in all parts of the tree, but lignification of this tissue is very uneven. Occasional dead cells are found in all tissues, even in the primary meristem. In the leaf, the plastids develop very unevenly; this is followed by retarded development of the pigment in some parts, resulting in a flecked appearance. Stomata are exceptionally numerous; in the leaf, they are confined to the lower surface and always communicate with very small cavities. Air spaces in the mesophyll are very small and are almost non‐existent in other tissues. Bodies, morphologically similar to the amorphous intracellular inclusions due to some viruses but differing chemically from them, are abundant in the leaves.Some of these characters are usually associated with a diseased condition, but they occur in both healthy and diseased cloves in the Zanzibar Protectorate. In the sudden death suspect, some may occur earlier or be more accentuated than in the healthy tree. This evidence alone might suggest that sudden death is merely the culmination of a long period of adverse conditions, but other evidence suggests very strongly that the disease is due to a pathogen. Of the groups of organisms which may cause disease, only fungi were found. These occurred in the absorbing roots but are unlikely to be the pathogens causing sudden death, for, until the tree has actually wilted, very few hyphae are present, and no more than are found in healthy trees. Nothing incompatible with the suggestion that sudden death is caused by a virus was found.