Heat shock proteins in the mechanisms of stress adaptation in Baikal amphipods and palearctic <Emphasis Type="Italic">Gammarus lacustris</Emphasis> Sars. I. HSP70 family

The participation of HSP70 family proteins in the mechanisms of stress adaptation under thermal and toxic stress in Baikal endemic and palearctic organisms was investigated. The four Lake Baikal endemic species Gmelinoides fasciatus (Stebb.), Eulimnogammarus cyaneus (Dyb.), E. vittatus (Dyb.), Ommatogammarus fl avus (Dyb.) were compared with the palearctic fauna representative Gammarus lacustris Sars. The type of synthesis of HSP70 family heat shock proteins under thermal (exposure at a temperature of 20, 25, and 30°C) and toxic (exposure in CdCl₂ solutions with the concentrations 50, 10, 5, 0.5, and 0.05 mg/l) stress was determined. All species under investigation were shown to have a common trend towards HSP70 content increase; therewith some species-specific characteristics of the type of synthesis of the protein under investigation were observed. The conclusion has been made on HSP70 participation in the mechanisms of thermal and toxic resistance in the studied amphipod species.     

Heat shock proteins in the mechanisms of stress adaptation in Baikal amphipods and Palaearctic <Emphasis Type="Italic">Gammarus lacustris</Emphasis> Sars II. Small HSP family

The role of low-molecular-weight (small) heat shock proteins (sHSPs) in the mechanisms of thermal and toxic resistance in fresh-water organisms was investigated. The four endemic species of Lake Baikal: Gmelinoides fasciatus (Stebb.), Eulimnogammarus cyaneus (Dyb.), E. vittatus (Dyb.), and Ommatogammarus flavus (Dyb.), and Gammarus lacustris Sars, a representative of the Palaearctic fauna, were studied. The effect of the temperature factor was evaluated by exposure of amphipods to temperatures of 20, 25, and 30°C, and the effect of the toxic factor, by exposure to cadmium chloride solutions with concentrations of 50, 10, 5, 0.5, and 0.05 mg/l. All the species showed a common trend of increasing content of sHSPs; species-specific features were observed in the synthesis of the proteins. It was concluded that sHSPs participate in the mechanisms of thermal and toxic resistance in the investigated amphipod species.     

Attitude of Baikal and Palearctic amphipods to oxygen as a factor of environment and mechanism of adaptation to its lowered level

The paper presents the materials of a comparative study of characteristics of anaerobic mechanisms use under the conditions of lowered oxygen content by Baikal amphipods Eulimnogammarus vittatus (Dyb.), E. cyaneus (Dyb.), as well as by Palearctic Gammarus lacustris Sars. It is shown that the system of anaerobic metabolism works most effectively for Palearctic G. lacustris. This species is characterized by the least degree of use of low-efficient way of energy production—anaerobic lipolysis, and the highest degree of use of the most efficient way of energy production under the conditions of low oxygen content-anaerobic succinate production. For the Baikal species that are less resistant to the lowered level of oxygen we show more expressed induction of anaerobic lipolysis and lower degree of engagement of anaerobic succinate production.     

Speciation of sponges in Baikal-Tuva region: an outline

Lake Baikal is known for its high percentage of endemic fauna and flora. The most abundant sessile animal taxa in the littoral zone of Baikal are the photosymbiotic sponges. These endemic sponges are grouped to the family Lubomirskiidae and are separated, based on molecular data, from the cosmopolitan family Spongillidae Gray 1867. In the present review, recent data on the potential driving forces of the rapid speciation in Lake Baikal have been unified. Current data suggest that the genetic repertoire of the sponges was sufficiently large to cope with the major cold events, occurring 2.8–2.5 and 1.8–1.5 Ma. It is proposed that during those periods of climatic incisions founder populations were separated from the parental cosmopolitan sponge population and developed subsequently to the array of endemic species. To clarify whether the endemic sponge fauna is indeed restricted to Lake Baikal only or whether there exist related taxa in other lakes, a collection of sponges in the 750 km distant Lake Chagytai was performed. This lake harbours unexpectedly large populations of the endemic species Baikalospongia dzhegatajensis . As the habitat of the Lake Chagytai (algal habitat) differs strongly from that of Lake Baikal (rocky habitat), it is proposed that after the formation of the initial founder population in response to the climatic shift, subsequent speciation was driven by habitat differences.     

Are Phragmites australis enzymes involved in the degradation of the textile azo dye acid orange 7?

The role of antioxidant and detoxification enzymes of Phragmites australis, in the degradation of an azo dye, acid orange 7 (AO7), was studied. Activities of several enzymes involved in plant protection against stress were assayed through the activity characterization of superoxide dismutase (SOD), peroxidases (POD), catalase (CAT), ascorbate peroxidase (APOX), dehydroascorbate reductase (DHAR) and glutathione S-transferase (GST), obtained from P. australis crude extracts of leaves, stems and roots. A sub-surface vertical flow constructed wetland, planted with P. australis was used to test the plants response to the AO7 exposure at two different concentrations (130 and 700 mg l(-1)). An activity increase was detected for an AO7 concentration of 130 mg l(-1) for most enzymes studied (SOD, CAT and APOX), especially in leaves, suggesting a response of the reactive oxygen species scavenging enzymes to the chemical stress imposed. GST activity increase in this situation can also be interpreted as an activation of the detoxification pathway and subsequent AO7 conjugation. A totally different behaviour was observed for AO7 at 700 mg l(-1). An evident decrease in activity was observed for SOD, CAT, APOX and GST, probably due to enzymatic inhibition by AO7. Contrarily, DHAR activity augmented drastically in this situation. POD activity was not greatly affected during trial. Altogether these results suggest that P. australis effectively uses the ascorbate-glutathione pathway for the detoxification of AO7.     

土壤低剂量芘污染对蚯蚓若干生化指标的影响

通过人工污染土壤的方法,设计芘的暴露浓度为0、60、120、240、480、960μg.kg-1.暴露实验进行1、3、7和14d后,分别检测蚯蚓内脏中细胞色素P450含量、谷胱甘肽转移酶(GST)、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量.结果表明,在供试浓度范围内,蚯蚓内脏中各生化指标对污染物暴露指示的敏感性存在差异:其中P450含量、GST和SOD活性最为敏感;POD和CAT活性次之;而MDA含量未对低剂量的芘暴露起到明显的指示作用.研究同时发现,低剂量污染物暴露的时间效应要强于剂量效应的影响.因而,在进行生态毒性诊断时,采用多指标和多时段的检测对增强指示的灵敏性和有效性尤为重要.     

Thermal stress defense in freshwater amphipods from contrasting habitats with emphasis on small heat shock proteins (sHSPs)

This study comparatively evaluated small heat shock proteins (sHSP) (related to α-crystallin) and antioxidant enzymes such as peroxidase (POD), catalase (CAT), glutathione S-transferase (GST) as anti-thermal stress response in two contrasting freshwater amphipods, the stenoecious Baikalean endemic Eulimnogammarus cyaneus and the Palearctic Gammarus lacustris.The thermal stress modulated the activity of antioxidant enzymes as well as the sHSP synthesis in both species. In both species, only the declining POD activity showed a clear dependency on exposure time.The most expressed response to elevated temperatures has been the activation of sHSP synthesis, with clear differences in the patterns: in G. lacustris, sHSP concentrations peaked after 12 h with a subsequent decline, while they increased steadily in E. cyaneus. Hence, the stenoecious species did not acclimate to the thermal stress within the given exposure time as the euryecious did.     

Microcystins in Cyanobacterial Biofilms from the Littoral Zone of Lake Baikal

Some species of cyanobacteria synthesize toxins whose concentration during water bloom can reach values dangerous for human and animal health. Planktonic cyanobacteria are the most common and well-studied microcystins producers, hepatotoxic cyclic heptapeptides, whereas microcystin-producing benthic cyanobacteria are less known. In recent years, the mass development of benthic cyanobacteria forming extensive fouling on different substrates has been detected in the littoral zone of Lake Baikal. We found microcystins produced by benthic cyanobacteria in the biofouling on different natural and artificial substrates, including diseased and dead endemic sponges Lubomirskia baicalensis and Baikalospongia spp. collected from the littoral area of Lake Baikal. Microscopic analysis of the biofouling revealed prevalence of representatives of Nostocales and Oscillatoriales with predominance of Tolypothrix distorta that is likely the main microcystin producer in Lake Baikal. According to enzyme-linked immunosorbent assay (ELISA), microcystin concentrations in biofouling were 29.8–3050 μg/kg dry weight. We identified eight microcystin variants using MALDI-TOF/TOF; [Dha7]MC-YR was detected in most samples. The presence of microcystins in biofilms formed on the surface of the artificial substrate by Phormidium autumnale was also recorded. The data obtained demonstrated the necessity to monitor potentially toxic species and concentrations of cyanotoxins in plankton and benthos in the littoral zone of Lake Baikal, especially in the regions with intense tourist and recreational activities.     

A transcriptome-wide assessment of differentially expressed genes among two highly divergent,yet sympatric,lineages of the freshwater Atyid shrimp, <Emphasis Type="Italic">Paratya australiensis</Emphasis>

The current study evaluated the possible toxic effects of the water-soluble fraction of crude oil on the general cellular stress-response mechanisms of two dominant representatives of Lake Baikal’s littoral community, the endemic amphipod species Eulimnogammarus verrucosus and E. cyaneus. The acute toxicity effects on the cellular stress-response mechanisms of amphipods were studied in the laboratory by exposing amphipods in water from Lake Baikal to addition of a water-soluble fraction of crude oil at concentrations considered safe for the aquatic environment. The present study found that even short-term exposure to a water-soluble fraction of crude oil at concentration of 50 µg/L, established as the threshold limit for fishery and aquaculture water reservoirs in the Russian Federation, directly affected the general stress-response markers HSP70 and lipid peroxidation and significantly changed the activity of antioxidant enzymes in both studied species. This result confirms the high sensitivity of Baikal endemics to crude oil. Thus, it also indicates that established standards and threshold limit values of oil concentrations estimated for ecological monitoring of general water reservoirs cannot be applied directly to the unique Lake Baikal ecosystem.     

Diet of the Symbiotic Amphipod,Brandtia parasitica parasitica (Crustacea,Amphipoda), Living on Diseased Baikal Sponges of the Family Lubomirskiidae in Southern Lake Baikal

Biology Bulletin - The diet of a symbiont, Brandtia parasitica parasitica (Dybowsky 1874), of Baikal sponges collected during an ecological crisis in the littoral zone of Lake Baikal is analyzed....     

Effect of nickel on antioxidative enzyme activities, proline and chlorophyll contents in wheat shoots

Effect of two Ni concentrations (10 and 200 μM) on growth, Ni accumulation, chlorophyll and proline contents, relative water content (RWC) as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione S-transferase (GST) were studied in shoots of wheat plants. Treatments caused a considerable accumulation of Ni in the shoots. However, exposure of plants to 10 μM Ni did not lead to significant alterations in shoot growth except for a slight increase in fresh mass. The other parameters studied were not affected by treatment of plants with 10 μM Ni. In contrast, 200 μM Ni caused inhibition of shoot growth, a decline in RWC and chlorophyll content, accumulation of proline and occurrence of visible symptoms of Ni toxicity. The activities of SOD and CAT decreased in response to 200 μM Ni. Conversely, several-fold enhancements of POD and GST activities were observed following the 3^rd day of 200 μM Ni treatment.     

New data on the distribution of the Upper Lena form of grayling (Thymallidae) in the basin of Lake Baikal and its taxonomic status

The habitation of the Upper Lena form of grayling in the upper reaches of the Tiya (the northwestern tributary of Lake Baikal) and Barguzin rivers, where Baikal grayling Thymallus baicalensis Dyb. also occurs, was established. The listed forms can be diagnosed from the body coloration, dorsal fin pattern, combination of meristic characters, as well as by molecular-genetic methods. The sympatric habitation of the Upper Lena and Baikal graylings in the northern tributaries of Baikal, considerable phenotypic and genetic differences, as well as the absence of individuals with intermediate characters, make it possible to consider them as independent species. The results indicate the need to revise the intraspecies structure of the Arctic grayling T. arcticus (Pall.) and the entire genus Thymallus. The localization of populations of the Upper Lena grayling in the upper reaches of Baikal tributaries testifies to its possible penetration of the Baikal basin by means of temporary river catchments that formed in the past and which are probable at present at watersheds with the Lena River. A wider distribution of this form is apparently hindered by the pressure of aboriginal species.     

Antioxidant responses of the pest natural enemy Hylyphantes graminicola (Araneae: Linyphiidae) exposed to short-term heat stress

Temperature is a critical abiotic factor that causes physiological changes in arthropods. However, little is known about the effect of heat stress on the antioxidant responses of Araneae species. Hylyphantes graminicola is a dominant predator in many cropping systems in China. In the present study, the effect of short-term heat stress (36, 38, 40 or 42 °C) on the reactive oxygen species (ROS) levels, the activities of antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT], peroxidases [POD] and glutathione-S-transferases GST]), total antioxidant capacity (TAC), malondialdehyde (MDA) concentrations and survival of H. graminicola spiderlings and adults were investigated. The results showed that H. graminicola adults had a significantly higher survival rate compared to spiderlings at 40 °C. The heat stress increased ROS contents in H. graminicola. The SOD, CAT, POD and GST activities increased in spiderlings and adults under heat stress. These data suggest a defensive function for these enzymes in alleviating oxidative damage. Specifically, SOD plays a key role in reducing the high level of superoxide radicals in spiderlings and adults. Moreover, the POD and CAT capabilities for scavenging H₂O₂ in spiderlings were similar, and CAT may play a more important role than POD in scavenging H₂O₂ in adults at 42 °C. The spiderling TAC increased significantly at 40 and 42 °C, and the adult TAC was stable at 36–40 °C but decreased at 42 °C. These data suggest that TAC was insufficient in H. graminicola adults under more severe stress conditions. These results further our understanding of the physiological response of Araneae species exposed to heat stress.     

温度胁迫对茶淡黄刺蛾四种保护酶活力和总抗氧化力的影响

【目的】温度适应性是决定昆虫分布和扩散的重要因素。为探索茶淡黄刺蛾Darna trima(Moore)对温度胁迫的耐受性,本研究测定了温度胁迫对4种抗氧化酶的活力和总抗氧化能力的影响。【方法】分别将茶淡黄刺蛾老熟幼虫置于﹣5、0、5、26(对照)、35、37.5、40℃下处理2、4、6 h,测定其体内超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、谷胱甘肽巯基转移酶(GST)和总抗氧化能力(T-AOC)的活力变化。【结果】茶淡黄刺蛾的4种抗氧化酶的活力和总抗氧化能力在不同温度和时间之间均存在显著变化,但不同指标对温度胁迫具有不同的响应模式。低温胁迫尤其是﹣5℃对各指标影响最为显著,而高温胁迫影响较小。【结论】SOD、CAT、POD、GST和T-AOC在茶淡黄刺蛾应对温度胁迫中具有重要作用,本研究可为判断茶淡黄刺蛾在茶区的分布范围提供一定的理论依据。     

Natural organic matter (NOM) has the potential to modify the multixenobiotic resistance (MXR) activity in freshwater amphipods Eulimnogammarus cyaneus and E. verrucosus

Based on the chemical features of natural organic matter (NOM) with its variety of functional groups, we hypothesized that NOM will modify the multixenobiotic-resistance (MXR) of an organism as xenobiotic chemicals do. The MXR system is a general first rather non-specific line of defense against environmental contaminants. The aim of this study was to compare the impacts on MXR activity in amphipod species (Eulimnogammarus cyaneus and E. verrucosus, from Lake Baikal) stressed by cadmium chloride or dissolved NOM for 24 h. NOM exposure concentrations were environmentally realistic. MXR activity was assessed based on rhodamine B efflux; its specificity was proven by a verapamil inhibition assay. It was shown that both NOM and CdCl₂ lead to substantial reduction of the rhodamine B efflux. This suggests that NOM may be regarded as a chemosensor which is able to reduce the efficiency of the MXR system. Possible mechanisms of direct NOM impact on MXR processes are discussed, such as peroxidation of the membranes (including P-glycoproteins) or internal blockage of the MXR pump by bioconcentrated NOM. In general, our results show that well-developed depuration pathways of freshwater organisms in contaminated environments may be impaired by strong chemical stressors and, more important, by natural biogeochemical matrices such as humic substances — humic substances are present in all freshwater systems.     

Food composition and feeding rate of the lake Baikal invader <Emphasis Type="Italic">Gmelinoides fasciatus</Emphasis> (Stebbing, 1899) in Lake Ladoga

The feeding of the Baikal invader Gmelinoiudes fasciatus (Stebbing, 1899) in Lake Ladoga has been studied based on field and experimental data. The food spectrum of this amphipod was revealed; it includes many plant and animal species. Differences in the feeding of G. fasciatus living in different littoral biotopes were shown. The ecological and physiological rations of this species were determined. The effect that the bottom substrate has on the feeding rate of the amphipod was estimated. The introduction of G. fasciatus into Lake Ladoga provided a more adequate utilization of the energy accumulated by the primary producers and its transfer to higher trophic levels. This Baikal amphipod occupied a niche that had been, in effect, vacant. This made the invader capable of maintaining the quantitative parameters of its population at a very high level, and it largely reorganized the flow of matter and energy in the littoral zone of the lake.     

Can acclimation of amphipods change their antioxidative response?

The aim of this study was to evaluate whether experimental conditions, particularly duration of acclimation in the laboratory with artificial water and diet prior to the actual experiment, can affect the antioxidant response of amphipods. This issue was evaluated using the Baikalian amphipod Eulimnogammarus cyaneus (Dyb.) exposed to two sources of natural organic matter (NOM). NOM elicits several oxidative stress symptoms and we used peroxidase activity as a representative response parameter. Pretest acclimation periods of the amphipods lasted from 3 days to 5 months. The exposure of E. cyaneus to NOM resulted in significant modulation of the peroxidase activity with a clear dependence on the duration of the acclimation period. Animals experiencing short-term acclimation showed reduced activity, whereas long-term acclimated animals exhibited an increase in peroxidase activity. We suggest that this difference was due to laboratory conditions particularly the artificial diet. This fact should be considered in future studies using field-collected animals kept in the laboratory for different periods of time.     

Lipid and fatty acid composition of scavenging amphipods Ommatogammarus spp. from different depths of lake Baikal

Limnology - The lipid and fatty acid content of benthopelagic scavenging amphipods Ommatogammarus flavus and O. albinus from different depths of Lake Baikal were studied. These amphipods, known to...     

Vertical distribution of acanthocephalans of the order Echinorhynchida in Lake Baikal

Vertical distribution of acanthocephalans of the order Echinorhynchida is studied in Lake Baikal. Four species and subspecies from cottid fishes (Perciformes: Cottoidei) were examined, namely Pseudoechinorhynchus borealis (Linstow, 1901), Metechinorhynchus salmonis salmonis (Muller, 1780), M.s. baicalensis Bogolepova, 1957, M. truttae (Schrank, 1788). In the littoral (0-5 m) and sublittoral (5-100 m) areas all these species and subspecies were occurred, white in the profundal (100-300 m) and abyssal (900-1600 m) areas only Metechinorhynchus salmonis baisalensis has been found.     

Palaearctic gastropod gains a foothold in the dominion of endemics: range expansion and morphological change of Lymnaea (Radix) auricularia in Lake Baikal

In and around the endemic-dominated Lake Baikal, palaearctic species are generally restricted to shallow, sheltered bays and in- and out-flowing river floodplains. However, we observed populations of the palaearctic snail Lymnaea (Radix) auricularia on the steep, rocky littoral of Lake Baikal proper. We compared the morphology of 542 shells sampled from this new habitat with potential source populations from conventional habitats. A size-free Discriminant Analysis indicated a strong morphological differentiation of the newly established populations from their likely sources. The new populations had a more compact shell shape with a wide aperture, which may be advantageous in wave-exposed habitats where a firm attachment to the substrate is needed. Shells from the conventional habitats were more elongated, with a narrow aperture, which may be advantageous in habitats that have a dry period where retreating into the mud is required and water loss should be limited. These results may suggest that selection is acting on shell shape in Lake Baikal. The apparent recent arrival of this pandemic gastropod in a habitat previously dominated by endemics constitutes a potential ecological threat and an alert to possible ecological change.