Habitat loss, predation pressure and episodic heat-shocks interact to impact arthropods and photosynthetic functioning of microecosystems

Ecosystems face multiple, potentially interacting, anthropogenic pressures that can modify biodiversity and ecosystem functioning. Using a bryophyte–microarthropod microecosystem we tested the combined effects of habitat loss, episodic heat-shocks and an introduced non-native apex predator on ecosystem function (chlorophyll fluorescence as an indicator of photosystem II function) and microarthropod communities (abundance and body size). The photosynthetic function was degraded by the sequence of heat-shock episodes, but unaffected by microecosystem patch size or top-down pressure from the introduced predator. In small microecosystem patches without the non-native predator, Acari abundance decreased with heat-shock frequency, while Collembola abundance increased. These trends disappeared in larger microecosystem patches or when predators were introduced, although Acari abundance was lower in large patches that underwent heat-shocks and were exposed to the predator. Mean assemblage body length (Collembola) was reduced independently in small microecosystem patches and with greater heat-shock frequency. Our experimental simulation of episodic heatwaves, habitat loss and non-native predation pressure in microecosystems produced evidence of individual and potentially synergistic and antagonistic effects on ecosystem function and microarthropod communities. Such complex outcomes of interactions between multiple stressors need to be considered when assessing anthropogenic risks for biota and ecosystem functioning.

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Impacts of multiple stressors on ecosystem function: Leaf decomposition in constructed urban wetlands

Environmental Pollution ◽

10.1016/j.envpol.2015.08.038 ◽

2016 ◽

Vol 208 ◽

pp. 221-232 ◽

Cited By ~ 10

Author(s):

Teresa J. Mackintosh ◽

Jenny A. Davis ◽

Ross M. Thompson

Keyword(s):

Ecosystem Function ◽

Multiple Stressors ◽

Leaf Decomposition ◽

Urban Wetlands

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Mitochondrial responses towards intermittent heat shocks in the Eastern Oyster, Crassostrea virginica

Journal of Experimental Biology ◽

10.1242/jeb.242745 ◽

2021 ◽

Author(s):

Georges Hraoui ◽

Sophie Breton ◽

Gilles Miron ◽

Luc H. Boudreau ◽

Florence Hunter-Manseau ◽

...

Keyword(s):

Oxygen Consumption ◽

Heat Shock ◽

Crassostrea Virginica ◽

Heat Waves ◽

Physiological Stress ◽

Eastern Oyster ◽

Emission Rates ◽

Mitochondrial Functions ◽

Heat Shocks ◽

Single Stress

Frequent heat waves caused by climate change can cause physiological stress in many animals, particularly in sessile ectotherms such as bivalves. Most studies characterizing thermal stress in bivalves focus on evaluating the responses to a single stress event. This does not accurately reflect the reality faced by bivalves which are often subject to intermittent heat waves. Here, we investigated the effect of intermittent heat stress on mitochondrial functions of Eastern oyster Crassostrea virginica which play a key role in setting ectotherms’ thermal tolerance. Specifically, we measured changes in mitochondrial oxygen consumption and H2O2 emission rates before, during and after intermittent 7.5°C heat shocks in oysters acclimated to 15°C and 22.5°C. Our results showed that oxygen consumption was impaired following the first heat shock at both acclimation temperatures. After the second heat shock, results for oysters acclimated to 15°C indicated a return to normal. However, oysters acclimated to 22.5°C struggled more with the compounding effects of intermittent heat shocks as denoted with an increase contribution of FAD-linked substrates to mitochondrial respiration as well as high levels of H2O2 emission rates. However, both acclimated populations showed signs of potential recovery ten days after the second heat shock, reflecting a surprising resilience to heat waves by C. virginica. Thus, this study highlights the important role of acclimation in oyster's capacity to weather intermittent heat shock.

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Heat shock-induced alterations in phosphorylation of the largest subunit of RNA polymerase II as revealed by monoclonal antibodies CC-3 and MPM-2

Biochemistry and Cell Biology ◽

10.1139/o99-037 ◽

1999 ◽

Vol 77 (4) ◽

pp. 367-374 ◽

Cited By ~ 3

Author(s):

Sébastien B Lavoie ◽

Alexandra L Albert ◽

Alain Thibodeau ◽

Michel Vincent

Keyword(s):

Heat Shock ◽

Rna Polymerase ◽

Rna Polymerase Ii ◽

Transcriptional Activity ◽

Phosphorylation Sites ◽

Stress Genes ◽

Terminal Domain ◽

Carboxy Terminal Domain ◽

Heat Shocks ◽

Carboxy Terminal

The phosphorylation of the carboxy-terminal domain of the largest subunit of RNA polymerase II plays an important role in the regulation of transcriptional activity and is also implicated in pre-mRNA processing. Different stresses, such as a heat shock, induce a marked alteration in the phosphorylation of this domain. The expression of stress genes by RNA polymerase II, to the detriment of other genes, could be attributable to such modifications of the phosphorylation sites. Using two phosphodependent antibodies recognizing distinct hyperphosphorylated forms of RNA polymerase II largest subunit, we studied the phosphorylation state of the subunit in different species after heat shocks of varying intensities. One of these antibodies, CC-3, preferentially recognizes the carboxy-terminal domain of the largest subunit under normal conditions, but its reactivity is diminished during stress. In contrast, the other antibody used, MPM-2, demonstrated a strong reactivity after a heat shock in most species studied. Therefore, CC-3 and MPM-2 antibodies discriminate between phosphoisomers that may be functionally different. Our results further indicate that the pattern of phosphorylation of RNA polymerase II in most species varies in response to environmental stress.Key words: RNA polymerase II, heat shock, phosphorylation, CC-3, MPM-2.

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Preferential deadenylation of Hsp70 mRNA plays a key role in regulating Hsp70 expression in Drosophila melanogaster

Molecular and Cellular Biology ◽

10.1128/mcb.14.6.3646-3659.1994 ◽

1994 ◽

Vol 14 (6) ◽

pp. 3646-3659

Author(s):

R P Dellavalle ◽

R Petersen ◽

S Lindquist

Keyword(s):

Drosophila Melanogaster ◽

Heat Shock ◽

Rna Processing ◽

Hsp70 Expression ◽

Hsp70 Mrna ◽

Mild Heat ◽

Endonucleolytic Cleavage ◽

Heat Shocks ◽

Low Efficiency ◽

Hsp70 Synthesis

Following a standard heat shock, approximately 40% of Hsp70 transcripts in Drosophila melanogaster lack a poly(A) tail. Since heat shock disrupts other aspects of RNA processing, this observation suggested that heat might disrupt polyadenylation as well. We find, however, that as the temperature is increased a larger fraction of Hsp70 RNA is polyadenylated. Poly(A)-deficient Hsp70 RNAs arise not from a failure in polyadenylation but from the rapid and selective removal of poly(A) from previously adenylated transcripts. Poly(A) removal is highly regulated: poly(A) is (i) removed much more rapidly from Hsp70 RNAs than from Hsp23 RNAs, (ii) removed more rapidly after mild heat shocks than after severe heat shocks, and (iii) removed more rapidly after a severe heat shock if cells have first been conditioned by a mild heat treatment. Poly(A) seems to be removed by simple deadenylation rather than by endonucleolytic cleavage 5' of the adenylation site. During recovery from heat shock, deadenylation is rapidly followed by degradation. In cells maintained at high temperatures, however, the two processes are uncoupled and Hsp70 RNAs are deadenylated without being degraded. These deadenylated mRNAs are translated with low efficiency. Deadenylation therefore allows Hsp70 synthesis to be repressed even when degradation of the mRNA is blocked. Poly(A) tail shortening appears to play a key role in regulating Hsp70 expression.

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THE RELATIONSHIP BETWEEN DEOXYRIBONUCLEIC ACID REPLICATION AND CELL DIVISION IN HEAT-SYNCHRONIZED TETRAHYMENA

The Journal of Cell Biology ◽

10.1083/jcb.46.3.533 ◽

1970 ◽

Vol 46 (3) ◽

pp. 533-543 ◽

Cited By ~ 18

Author(s):

William R. Jeffery ◽

Kenneth D. Stuart ◽

Joseph Frankel

Keyword(s):

Cell Division ◽

Heat Shock ◽

Dna Synthesis ◽

Deoxyribonucleic Acid ◽

Heat Shock Treatment ◽

Heat Shocks ◽

Prolonged Heat ◽

S Period ◽

C 50 ◽

The Relationship

The effect of supraoptimal temperature on macronuclear DNA synthesis in Tetrahymena was studied by radioautography during prolonged heat and heat-shock synchronization treatments. Prolonged heat treatments (34°C) delayed the initiation of S, but did not appreciably delay DNA synthesis in progress. Return to optimal temperature (28°C) 50 or 100 min later resulted in initiation of S, in delayed cells, at a rate greater than in controls. During the synchronization treatment, most cells were unable to enter S during a heat shock, but initiated S with a slight delay during the following intershock period. These cells were not appreciably delayed in completion of S by subsequent heat shocks. Supraoptimal temperature appears to affect the DNA synthetic cycle near the G1 to S transition. Cells subjected to the heat-shock treatment in early G1 all participated in one S period, and many underwent a succession of two S periods. DNA synthesis occurred in about 50% of the cells between EST and the first synchronous division, with the likelihood of DNA synthesis becoming greater the longer the interval between these two events. In some cells no detectable DNA synthesis occurred between EST and the second synchronous division. It was concluded that a precise temporal alternation of DNA replication and cell division is not obligatory in Tetrahymena.

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Impairment of microbial and meiofaunal ecosystem functions linked to algal forest loss

Scientific Reports ◽

10.1038/s41598-020-76817-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Silvia Bianchelli ◽

Roberto Danovaro

Keyword(s):

Habitat Loss ◽

Ecosystem Functioning ◽

Negative Impact ◽

Ecosystem Functions ◽

Marine Biodiversity ◽

Forest Loss ◽

Higher Taxa ◽

Vulnerable Habitats ◽

Nematode Biodiversity ◽

Barren Grounds

AbstractHabitat loss is jeopardizing marine biodiversity. In the Mediterranean Sea, the algal forests of Cystoseira spp. form one of the most complex, productive and vulnerable shallow-water habitats. These forests are rapidly regressing with negative impact on the associated biodiversity, and potential consequences in terms of ecosystem functioning. Here, by comparing healthy Cystoseira forests and barren grounds (i.e., habitats where the macroalgal forests disappeared), we assessed the effects of habitat loss on meiofaunal and nematode biodiversity, and on some ecosystem functions (here measured in terms of prokaryotic and meiofaunal biomass). Overall, our results suggest that the loss of Cystoseira forests and the consequent barren formation is associated with the loss of meiofaunal higher taxa and a decrease of nematode biodiversity, leading to the collapse of the microbial and meiofaunal variables of ecosystem functions. We conclude that, given the very limited resilience of these ecosystems, active restoration of these vulnerable habitats is needed, in order to recover their biodiversity, ecosystem functions and associated services.

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P transposons controlled by the heat shock promoter.

Molecular and Cellular Biology ◽

10.1128/mcb.6.5.1640 ◽

1986 ◽

Vol 6 (5) ◽

pp. 1640-1649 ◽

Cited By ~ 50

Author(s):

H Steller ◽

V Pirrotta

Keyword(s):

Heat Shock ◽

Germ Line ◽

Fusion Gene ◽

P Element ◽

Translational Efficiency ◽

Heat Shock Promoter ◽

P Elements ◽

Heat Shocks ◽

Neomycin Resistance ◽

Heat Shock Induction

We have transformed Drosophila melanogaster with modified P-element transposons, which express the transposase function from the heat-inducible hsp70 heat shock promoter. The Icarus transposon, which contains a direct hsp70-P fusion gene, behaved like a very active autonomous P element even before heat shock induction. Although heat shock led to abundant somatic transcription, transposition of the Icarus element was confined to germ line cells. To reduce the constitutive transposase activity observed for the Icarus element, we attenuated the translational efficiency of the transposase RNA by inserting the transposon 5 neomycin resistance gene between the hsp70 promoter and the P-element sequences. The resulting construct, called Icarus-neo, conferred resistance to G418, and its transposition was significantly stimulated by heat shock. Heat shocks applied during the embryonic or third instar larval stage had similar effects, indicating that transposition of P elements is not restricted to a certain developmental stage. Both Icarus and Icarus-neo destabilized snw in a P-cytotype background and thus at least partially overcome the repression of transposition. Our results suggest that the regulation of P-element transposition occurs at both the transcriptional and posttranscriptional levels.

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Seed germination response of a potential rangeland weed Psilocaulon granulicaule to selected environmental conditions

Australian Journal of Botany ◽

10.1071/bt20060 ◽

2020 ◽

Vol 68 (5) ◽

pp. 363

Author(s):

Rekha Ranaweera ◽

Sandra L. Weller ◽

Singarayer K. Florentine

Keyword(s):

Water Stress ◽

Heat Shock ◽

Seed Germination ◽

Management Practices ◽

Germination Rate ◽

Radiant Heat ◽

Weed Species ◽

Light Regimes ◽

Heat Shocks ◽

Environmental Weed

Studies show that just over 620 non-native naturalised plant species have been recorded within the Australian rangelands, some of which have a capacity to cause significant impacts on rangeland flora and grazing activity. Although Psilocaulon granulicaule (Haw.), Schwantes is listed as a highly invasive environmental weed species, there has been no previous research into its seed ecology. Therefore, this study was conducted to investigate the effects of temperature, light, pH, water stress, heat-shock, and salinity on the germination of P. granulicaule. In this study, four temperature regimes covering four different day and night temperature variations (17–7°C, 25–15°C, 30–25°C and 40–30°C) and two light regimes (12-h light–12-h dark, 24-h dark) were investigated. The effects of pH, water stress, heat-shock and salinity were investigated, using pH buffers, polyethylene glycol solutions, three heat shock events under four temperatures and a range of NaCl solutions. These tests were conducted under the identified optimum temperature range (25/15°C) and light regime for seed germination. The results showed that both temperature and photoperiod significantly influenced the germination rate, with 94.2% germination in the 25–15°C range under a 12-h light-12-h dark regime. Higher temperatures (30–40°C) reduced seed germination to <58% germination in both light regimes (57.5%, 12-h light-12-h dark; 54.17%, 24-h dark). The highest germination rates were observed in low pH solutions, high moisture levels, low heat-shocks and low salinity. The study showed that this species is sensitive to environmental factors such as temperature, light, pH, moisture, heat shock and salinity, suggesting that these factors can be used as critical indicators to guide effective management practices to address this weed problem. Given that seeds are sensitive to radiant heat, burning could be used as a tool to effectively manage this species.

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