Heat-shocked Animals Research Articles

S-adenosylmethionine synthases specify distinct H3K4me3 populations and gene expression patterns during heat stress.

Methylation is a widely occurring modification that requires the methyl donor S-adenosylmethionine (SAM) and acts in regulation of gene expression and other processes. SAM is synthesized from methionine, which is imported or generated through the 1-carbon cycle (1 CC). Alterations in 1 CC function have clear effects on lifespan and stress responses, but the wide distribution of this modification has made identification of specific mechanistic links difficult. Exploiting a dynamic stress-induced transcription model, we find that two SAM synthases in Caenorhabditis elegans, SAMS-1 and SAMS-4, contribute differently to modification of H3K4me3, gene expression and survival. We find that sams-4 enhances H3K4me3 in heat shocked animals lacking sams-1, however, sams-1 cannot compensate for sams-4, which is required to survive heat stress. This suggests that the regulatory functions of SAM depend on its enzymatic source and that provisioning of SAM may be an important regulatory step linking 1 CC function to phenotypes in aging and stress.

Erratum.

Development, Growth & DifferentiationVolume 61, Issue 2 p. 198-199 ERRATUMFree Access Erratum This article corrects the following: Proteasome activity determines pupation timing through the degradation speed of timer molecule Blimp-1 Hamdy Aly, Kazutaka Akagi, Hitoshi Ueda, Volume 60Issue 8Development, Growth & Differentiation pages: 502-508 First Published online: October 18, 2018 First published: 08 February 2019 https://doi.org/10.1111/dgd.12598AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat In 1, the legends of figures 2, 3, 5 and 6 are missing. Below are the correct figures with complete legends. Figure 2Open in figure viewerPowerPoint 26S proteasome mutants exhibited a delay in pupation timing. Heterozygous mutants of 26S proteasome subunits and control (yw) animals were cultured at 25°C, and pupation timing was observed every 30 min. The Kolmogorov–Smirnov test was used to evaluate the differences between pupation timing and to determine p values. Prosα2G8948 line (a) was used for the α subunit mutant, Prosβ3G4206 (b) and Prosβ61 (c) were used for β subunit mutants. Av: average of pupation timing; n: number of animals examined Figure 3Open in figure viewerPowerPoint FBXO11 contributes to the correct determination of pupation timing. FBXO11 mutants and control (yw) animals were cultured at 25°C, and pupation timing was observed every 30 min. The Kolmogorov–Smirnov test was used to evaluate differences between pupation timing and to determine p values. Heterozygous lines FBXO11NP2786 (a), FBXO11GS10050 (b), and homozygous line FBXO11EY09314 (c) were used. Av: average of pupation timing; n: number of animals examined Figure 5Open in figure viewerPowerPoint Rescue of pupation timing delay in FBXO11 mutant by induction of βFTZ-F1. Pupation timing of FBXO11 mutant animals with/without hs-βFTZ-F1 transgene was observed every 30 min. Non-heat shocked (a) and heat shocked (b) animals. Heat shock was given at 34°C for 1 hr at 7 hr APF. The Kolmogorov–Smirnov test was used to evaluate differences in pupation timing between test and control animals and to determine p-values. Av: average of pupation timing; n: number of animals examined Figure 6Open in figure viewerPowerPoint The fat body is responsible for the control of pupation timing by proteasome activity. Pupation timing was observed every 30 min in animals with knockdown of 20S components β6 (a, b) and α4 (c) in the fat body. The Kolmogorov–Smirnov test was used to evaluate differences between pupation timing and to determine p-values versus the RNAi/+ (a, b, c), Cg- Gal4/+ (a) or ppl-Gal4/+ (b, c) as controls. Av: average of pupation timing; n: number of animals examined We apologize for the errorr. REFERENCE 1Aly, H., Akagi, K., & Ueda, H. (2018). Proteasome activity determines pupation timing through the degradation speed of timer molecule Blimp-1. Development, Growth and Differentiation, 60, 502– 508. https://doi.org/10.1111/dgd.12569 Volume61, Issue2February 2019Pages 198-199 FiguresReferencesRelatedInformation

An intron-containing, heat-inducible stress-70 gene in the millipede Tachypodoiulus niger (Julidae, Diplopoda)

The highly conserved part of the nucleotide-binding domain of the hsp70 gene family was amplified from the soil diplopod Tachypodoiulus niger (Julidae, Diplopoda). Genomic DNA yielded 701, 549 and 540 bp sequences, whereas cDNA from heat shocked animals produced only one distinct fragment of 543 bp. The sequences could be classified as a 70 kDa heat shock protein (hsp70), the corresponding 70 kDa heat shock cognate (hsc70) and a glucose-related hsp70 homologue (grp78). Comparisons of genomic and cDNA sequences of hsc70 identified two introns within the consensus sequence. Generally, stress-70 expression levels were low, which hampered successful RT-PCR and subsequent subcloning. Following experimental heat shock, however, the spliced hsc70 was amplified predominantly, instead of its inducible homologue hsp70. This finding suggests that microevolution in this soil-dwelling arthropod is directed towards low constitutive stress-70 levels and that the capacity for stress-70 induction presumably is limited. hsc70, albeit having introns, apparently is inducible and contributes to the stress-70 response.

Seasonal effects of heat shock on bacterial populations, including artificial Vibrio parahaemolyticus exposure, in the Pacific oyster, Crassostrea gigas

During the warmer summer months, oysters are conditioned to spawn, resulting in massive physiological efforts for gamete production. Moreover, the higher temperatures during the summer typically result in increased bacteria populations in oysters. We hypothesized that these animals are under multiple stresses that lead to possible immune system impairments during the summer months that can possibly lead to death. Here we show that in the summer and the fall animals exposed to a short heat stress respond similarly, resulting in a general trend of more bacteria being found in heat shocked animals than their non-heat shocked counterparts. We also show that naturally occurring bacterial populations are effected by a heat shock. In addition, oysters artificially contaminated with Vibrio parahaemolyticus were also affected by a heat shock. Heat shocked animals contained higher concentrations of V. parahaemolyticus in their tissues and hemolymph than control animals and this was consistent for animals examined during summer and fall. Finally, oyster hemocyte interactions with V. parahaemolyticus differed based on the time of the year. Overall, these findings demonstrate that seasonal changes and/or a short heat shock is sufficient to impact bacterial retention, particularly V. parahaemolyticus, in oysters and this line of research might lead to important considerations for animal harvesting procedures.

Heat shock affects host–pathogen interaction in Galleria mellonella infected with Bacillus thuringiensis

We report that Galleria mellonella larvae exposed to heat shock was more resistant to infection with entomopathogenic bacteria Bacillus thuringiensis. The insects were exposed to a temperature of 40°C for 30min directly before injection of vegetative bacterial cells. It appeared that the kinetics of the immune response was affected in heat-shocked animals. The infection-induced antimicrobial activity of larval hemolymph was stronger in shocked animals in comparison to the non-shocked ones. Hemolymph proteins of molecular weight below 10kDa, corresponding to the size of antimicrobial peptides, were responsible for this activity. Furthermore, the transcription level of genes encoding antimicrobial peptides: cecropin, gallerimycin, and galiomycin was increased in the fat bodies of insects exposed to heat shock before infection. On the contrary, the heat-shock treatment did not enhance expression of the metalloproteinase inhibitor-IMPI in the infected animals. The difference in the amount of antimicrobial peptides and, consequently, in the defense activity of insect hemolymph, persisted after the action of bacterial metalloproteinases, which are well-known virulence factors. Furthermore, peptides with antimicrobial activity in the hemolymph of infected larvae pre-exposed to heat shock appeared to be more resistant to proteolytic degradation both in vitro and in vivo. Our results point to the mechanism of cross-protection of thermal stress toward innate immune response.

A heat shock protein and Wnt signaling crosstalk during axial patterning and stem cell proliferation

Both Wnt signaling and heat shock proteins play important roles in development and disease. As such, they have been widely, though separately, studied. Here we show a link between a heat shock protein and Wnt signaling in a member of the basal phylum, Cnidaria. A heat shock at late gastrulation in the clonal marine hydrozoan, Hydractinia, interferes with axis development, specifically inhibiting head development, while aboral structures remain unaffected. The heat treatment upregulated Hsc71, a constitutive Hsp70 related gene, followed by a transient upregulation, and long-term downregulation, of Wnt signaling components. Downregulating Hsc71 by RNAi in heat-shocked animals rescued these defects, resulting in normal head development. Transgenic animals, ectopically expressing Hsc71, had similar developmental abnormalities as heat-shocked animals in terms of both morphology and Wnt3 expression. We also found that Hsc71 is upregulated in response to ectopic Wnt activation, but only in the context of stem cell proliferation and not in head development. Hsc71's normal expression is consistent with a conserved role in mitosis and apoptosis inhibition. Our results demonstrate a hitherto unknown crosstalk between heat shock proteins and Wnt/β-catenin signaling. This link likely has important implications in understanding normal development, congenital defects and cancer biology.

Overexpression of caveolins in Caenorhabditis elegans induces changes in egg-laying and fecundity

Caveolae are small plasma membrane-associated invaginations that are enriched in proteins of the caveolin family in addition to, sphingolipids, glycosphingolipids and cholesterol. Caveolae have been implicated in several endocytic and trafficking mechanisms. Mutations in caveolins have been shown to cause disease and caveolae offer one site for pathogen entry. The Caenorhabditis elegans genome encodes two caveolins (cav-1 and cav-2); we have shown that these two proteins have distinct expression patterns. CAV-1 is found in the majority of cells in embryos and in the body-wall muscles, neurons and germ line of adult worms. CAV-2 is expressed in the intestine and is required for apical lipid trafficking. In the course of our studies, we generated several constructs to over-express caveolins in C. elegans. Here we show that over-expression of cav-1 protects against the decrease in brood size associated with the effects of heat shock and the presence of extrachromosomal arrays in heat-shocked animals. Furthermore, we show that over-expression of cav-2 in the nervous system increases the rate of egg-laying and total number of eggs laid.

Cytoskeletal stability and heat shock-mediated thermoprotection of central pattern generation in Locusta migratoria

Prior exposure to extreme temperatures can induce thermoprotection in migratory locusts, which is important for survival in their natural environment. An important motor activity that needs to be protected is ventilation. The mechanism underlying heat shock is not fully understood, and our goal was to test the idea that cytoskeletal stability is critical for such thermoprotection. Cytoskeletal stabilizers (concanavalin A) and destabilizers (colchicine) were bath-applied in semi-intact locust preparations in both control (C) and pre-treated heat-shocked (3 h, 45 degrees C) animals. We measured parameters of the ventilatory motor pattern during maintained high temperature (43 degrees C) and recorded the times taken for motor pattern generation to fail and then recover on returning to room temperature. We found that concanavalin A mimicked the effects of a prior heat stress in control animals by increasing time to failure and decreasing time to recovery of motor pattern generation. However, colchicine destroyed protection in heat-shocked animals by decreasing time to failure and increasing time to recovery. Our findings confirm that the cytoskeleton has a mechanistic role in preserving neural function at high temperatures, possibly through stabilizing ion channels and other integral membrane proteins (e.g. Na(+)/K(+) ATPase) and their interactions with heat shock proteins.

Targeted engineering of the Caenorhabditis elegans genome following Mos1-triggered chromosomal breaks

The Drosophila element Mos1 is a class II transposon, which moves by a 'cut-and-paste' mechanism and can be experimentally mobilized in the Caenorhabditis elegans germ line. Here, we triggered the excision of identified Mos1 insertions to create chromosomal breaks at given sites and further manipulate the broken loci. Double-strand break (DSB) repair could be achieved by gene conversion using a transgene containing sequences homologous to the broken chromosomal region as a repair template. Consequently, mutations engineered in the transgene could be copied to a specific locus at high frequency. This pathway was further characterized to develop an efficient tool--called MosTIC--to manipulate the C. elegans genome. Analysis of DSB repair during MosTIC experiments demonstrated that DSBs could also be sealed by end-joining in the germ line, independently from the evolutionarily conserved Ku80 and ligase IV factors. In conjunction with a publicly available Mos1 insertion library currently being generated, MosTIC will provide a general tool to customize the C. elegans genome.

The Gα12-RGS RhoGEF-RhoA signalling pathway regulates neurotransmitter release in C. elegans

In Caenorhabditis elegans adults, the single Rho GTPase orthologue, RHO-1, stimulates neurotransmitter release at synapses. We show that one of the pathways acting upstream of RHO-1 in acetylcholine (ACh)-releasing motor neurons depends on Galpha12 (GPA-12), which acts via the single C. elegans RGS RhoGEF (RHGF-1). Activated GPA-12 has the same effect as activated RHO-1, inducing the accumulation of diacylglycerol and the neuromodulator UNC-13 at release sites, and increased ACh release. We showed previously that RHO-1 stimulates ACh release by two separate pathways-one that requires UNC-13 and a second that does not. We show here that a non-DAG-binding-UNC-13 mutant that partially blocks increased ACh release by activated RHO-1 completely blocks increased ACh release by activated GPA-12. Thus, the upstream GPA-12/RHGF-1 pathway stimulates only a subset of RHO-1 downstream effectors, suggesting that either the RHO-1 effectors require different levels of activated RHO-1 for activation or there are two distinct pools of RHO-1 within C. elegans neurons.

In vivo gene delivery of HSP70i by adenovirus and adeno-associated virus preserves contractile function in mouse heart following ischemia-reperfusion

Inducible heat shock protein 70 (HSP70i) has been shown to exert a protective effect in hearts subjected to ischemia-reperfusion. Although studied in heat-shocked animals and in transgenic mice that constitutively overexpress the protein, the therapeutic application of the protein in the form of a viral vector-mediated HSP70i expression has not been widely examined. Accordingly, we have examined the effects of HSP70i delivered in vivo to the left ventricular free wall of the heart via viral gene therapy in mice. The affect of virally mediated HSP70i expression in preserving cardiac function following ischemia-reperfusion was examined after short-term expression (5-day adenovirus mediated) and long-term expression (8-mo adeno-associated virus mediated) in mice by subjecting ex vivo Langendorff perfused hearts to a regime of ischemia-reperfusion. Both vectors were capable of increasing HSP70i expression in the heart, and neither vector had any effect on cardiac function during aerobic (preischemic) perfusion when compared with corresponding controls. In contrast, both adenovirus-mediated and adeno-associated virus-mediated expression of HSP70i improved the contractile recovery of the heart after 120 min of reperfusion following ischemia. This study demonstrates the feasibility of using both short- and long-term expression of virally mediated HSP70i as a therapeutic intervention against cardiac ischemia-reperfusion injury.

Thermal biology of horseshoe crab embryos and larvae: A role for heat shock proteins

Eggs of the American horseshoe crab, Limulus polyphemus L., develop on sandy estuarine beaches during the spring and summer, and are potentially vulnerable to thermal stress during the 3–4 weeks of development to the first instar (trilobite) larval stage. In many marine taxa, heat shock (stress) proteins (Hsp's) help individuals acclimate to stresses by restoring the proper folding of cellular proteins whose shape has been altered by temperature shock or other forms of environmental stress. We examined the survival of embryos and first instar (trilobite) larvae following heat shock, and compared the levels of Hsp70 in heat shocked and control animals. Animals acclimated to 13 or 22 °C had close to 100% survival when heat shocked for 3 h at 35 or 40 °C, but exposure to 45 °C for 3 h was lethal. To study the effect of heat shock on Hsp70 production under environmentally realistic conditions, animals were acclimated to either 13 or 22 °C, heat-shocked at 35 °C for 3 h, and soluble proteins were extracted following 0, 2, 4, or 6 h recovery at 22 °C. The relative amounts of Hsp70 in horseshoe crab embryos and larvae were examined using SDS-PAGE and Western blotting. Relative to controls animals held at a constant temperature, there was a slight elevation of Hsp70 only among heat shocked trilobite larvae in the 6 h recovery treatment. Hsp70 levels did not differ significantly between control and heat shocked embryos. Horseshoe crabs have adapted to living in a thermally stressful environment by maintaining a high baseline (constitutive) level of cellular stress proteins such as Hsp70, rather than by synthesizing inducible Hsp's when stressful temperatures are encountered. This may be an effective strategy given that the heat shocks encountered by intertidal embryos and larvae occur regularly as a function of diurnal and tidal temperature changes.

Heat Stress–Mediated Plasticity in a Locust Looming-Sensitive Visual Interneuron

Neural circuits are strongly affected by temperature and failure ensues at extremes. However, detrimental effects of high temperature on neural pathways can be mitigated by prior exposure to high, but sublethal temperatures (heat shock). Using the migratory locust, Locusta migratoria, we investigated the effects of heat shock on the thermosensitivity of a visual interneuron [the descending contralateral movement detector (DCMD)]. Activity in the DCMD was elicited using a looming stimulus and the response was recorded from the axon using intracellular and extracellular methods. The thoracic region was perfused with temperature-controlled saline and measurements were taken at 5 degrees intervals starting at 25 degrees C. Activity in DCMD was decreased in control animals with increased temperature, whereas heat-shocked animals had a potentiated response such that the peak firing frequency was increased. Significant differences were also found in the thermosensitivity of the action potential properties between control and heat-shocked animals. Heat shock also had a potentiating effect on the amplitude of the afterdepolarization. The concurrent increase in peak firing frequency and maintenance of action potential properties after heat shock could enhance the reliability with which DCMD initiates visually guided behaviors at high temperature.

Cloning, sequencing and expression analysis of cDNA encoding a constitutive heat shock protein 70 (HSC70) inFenneropenaeus chinensis

The cDNA encoding hsc70 of Chinese shrimp Fenneropenaeus chinensis was cloned from hepatopancreas by RT-PCR based on its EST sequence. The full length cDNA of 2090 bp contained an open reading frame of 1956 nucleotides and partial 5'- and 3'-untranslated region(5'- and 3'-UTR). PCR amplification and sequencing analysis showed the existence of introns in the region of 1-547 bp, but they did not exist in the region of 548-2090 bp of hsc70 cDNA. When the deduced 652 amino acid sequence of HSC70 was compared with the members of HSP70 family from other organisms, the results showed 85.9% similarity with HSC71 from Oncorhynchus mykiss and HSC70 from Homo sapiens. It also exhibited 85.8% similarity with HSP70 from Mus musculu and 85.4% with HSC70 from Manduca sexta. Expression analysis showed that hsc70 mRNA was espressed constitutively in hepatopancreas, muscle, eyestalks, haemocytes, heart, ovary, intestine and gills in Fenneropenaeus chinensis. No difference could be detected on hsc70 mRNA level in muscle between heat-shocked and control animals.

Genomic approaches to detecting thermal stress in Calanus finmarchicus (Copepoda: Calanoida)

Zooplankton may be subjected to physiological stress as they encounter rapid and large changes in temperature through vertical migration or transfer into different water masses. Induction of one or more heat shock proteins (hsp) is a common protective response to thermal stress in organisms. We looked for evidence for such a response in Calanus finmarchicus. We compared hsp70 expression in copepods exposed to temperature stress with that for non-stressed controls. Partial sequences of the amplified cDNA product were obtained and aligned with known hsp70 sequences to establish the identity of the heat shock protein. In one experiment, animals were transferred from their collection temperature (8 °C) to 20 °C for 30 min, and then returned to 8 °C for 4 h before sampling for gene expression levels. In another, the animals were exposed to 18 °C over 48 h before sampling for molecular analysis. A four-fold induction of hsp70 was measured in both groups of heat shocked animals using quantitative real time polymerase chain reaction (PCR). The experimental temperatures, although high for C. finmarchicus, are within the range of temperatures experienced by this species in their habitat. In addition to confirming an hsp70-mediated response in C. finmarchicus, the findings suggest that a recent history of thermal stress may be assessed in natural populations through a routine molecular assay.

The small heat shock proteins of the nematode Caenorhabditis elegans: structure, regulation and biology.

The first investigations of the heat shock response in C. elegans were carried out by analyzing the patterns of proteins synthesized by 35S-labeled nematodes cultured at various temperatures (Snutch and Baillie 1983). These experiments established a temperature profile for the heat shock response, identified the major molecular weight classes of heat shock proteins (Hsps) and noted the homology between Drosophila and C. elegans Hsp70 genes, based on crosshybridization experiments. In these studies, a prominent, labeled protein with an apparent molecular mass of 16 kDa was noted in heat shocked animals. Partial cDNAs encoding Hspl6 species were subsequently cloned, and these were the first small Hsp (sHsp) sequences determined after those of Drosophila, to which they were found to be related (Russnak et al. 1983). The Hsp 16 sequences of C. elegans thus provided the first indication that small Hsps of varying molecular masses from distantly related organisms were similar to each other and to the mammalian α-crystallins. The completion of the C. elegans genome sequence (The C. elegans Sequencing Consortium 1998) provides an opportunity to examine the entire complement of sHsps from this metazoan. This review will provide an overview of the structures, expression, developmental and tissue specificities and biochemical properties of the C. elegans sHsps which have been studied to date.

The heat shock response of adult Artemia franciscana

1. We studied responses of adult brine shrimp, Artemia franciscana, to high temperature, including LT 50 determination, induced thermotolerance (ITT), the Hsp-70 family of stress proteins and protein synthesis before and after heat shock. 2. Adults were grown in laboratory cultures from encysted embryos (cysts) obtained from San Francisco Bay (SF) and much warmer culture ponds in Vietnam (V). 3. Adults from V cysts were more tolerant of high temperatures than those from SF cysts, but this difference essentially disappeared in the second generation of adults. 4. Levels of constitutive Hsc-70 were very low in adults of both groups, but were strongly upregulated by a sublethal heat shock (37°C, 30 min), with V adults showing the greater degree of upregulation. Heat shock also induced Hsp-67, to a greater extent in V compared to SF adults 5. Incorporation of 14C-leucine into protein did not result in the “classic” heat shock response, possibly due to increased permeability of heat-shocked animals to the tracer.

Long-term effects of prior heat shock on neuronal potassium currents recorded in a novel insect ganglion slice preparation.

Brief exposure to high temperatures (heat shock) induces long-lasting adaptive changes in the molecular biology of protein interactions and behavior of poikilotherms. However, little is known about heat shock effects on neuronal properties. To investigate how heat shock affects neuronal properties we developed an insect ganglion slice from locusts. The functional integrity of neuronal circuits in slices was demonstrated by recordings from rhythmically active respiratory neurons and by the ability to induce rhythmic population activity with octopamine. Under these "functional" in vitro conditions we recorded outward potassium currents from neurons of the ventral midline of the A1 metathoracic neuromere. In control neurons, voltage steps to 40 mV from a holding potential of -60 mV evoked in control neurons potassium currents with a peak current of 10.0 +/- 2.5 nA and a large steady state current of 8.5 +/- 2.6 nA, which was still activated from a holding potential of -40 mV. After heat shock most of the outward current inactivated rapidly (peak amplitude: 8.4 +/- 2.4 nA; steady state: 3.6 +/- 2.0 nA). This current was inactivated at a holding potential of -40 mV. The response to temperature changes was also significantly different. After changing the temperature from 38 to 42 degrees C the amplitude of the peak and steady-state current was significantly lower in neurons obtained from heat-shocked animals than those obtained from controls. Our study indicates that not only heat shock can alter neuronal properties, but also that it is possible to investigate ion currents in insect ganglion slices.

Heat shock improves recovery and provides protection against global ischemia after hypothermic storage

Background. Improved methods of donor heart preparation before preservation could allow for prolonged storage and permit remote procurement of these organs. Previous studies have shown that overexpression of heat-shock protein 72 provides protection against ischemic cardiac damage. We sought to determine whether rats subjected to heat stress with only 6-hour recovery could acquire protection to a subsequent heart storage for 12 hours at 4°C.Methods. Three groups of animals (n = 10 each) were studied: control, sham-treated, and heat-shocked rats (whole-body hyperthermia 42°C for 15 minutes). After 12-hour cold ischemia hearts were reperfused on a Langendorff column. To confirm any differences in functional recovery, hearts were then subjected to an additional 15-minute period of warm global ischemia after which function and lactate dehydrogenase enzyme leakage were measured.Results. Heat-shocked animals showed marked improvements compared with controls in left ventricular developed pressure (63 ± 4 mm Hg versus 44 ± 4 mm Hg, p < 0.05) heart rate × developed pressure (13,883 ± 1,174 beats per minute × mm Hg versus 8,492 ± 1,564 beats per minute × mm Hg, p < 0.05), rate of ventricular pressure increase (1,912 ± 112 mm Hg/second versus 1,215 ± 162 mm Hg/second, p < 0.005), rate of ventricular pressure decrease (1,258 ± 89 mm Hg/second versus 774 ± 106 mm Hg/second, p < 0.005). Diastolic compliance and lactate dehydrogenase release were improved in heat-shocked animals compared with controls and sham-treated animals. Differences between heat-shocked animals and control or sham-treated animals were further increased after the additional 15-minute period of warm ischemia. Western blot experiments confirmed increased heat-shock protein 72 levels in heat-shocked animals (> threefold) compared with sham-treated animals and controls.Conclusions. Heat shock 6 hours before heart removal resulted in marked expression of heat-shock protein 72 and protected isolated rat hearts by increased functional recovery and decreased cellular necrosis after 12-hour cold ischemia in a protocol mimicking that of heart preservation for transplantation. Protection was further confirmed after an additional 15-minute period of warm ischemia.

Heat shock protects synaptic transmission in flight motor circuitry of locusts.

We investigated the effects of heat shock on the temperature sensitivity of synaptic transmission in the motor circuit for flight in Locusta migratoria. In heat shocked animals synaptic transmission failed at 5-6 degrees C higher than in control animals and recovery of transmission was more than three times faster upon return to room temperature. We also found that synaptic delay was rendered insensitive to increases in temperature by heat shock. Thus we have shown in the locust that heat shock has important protective effects on synaptic transmission, thereby extending the upper temperature limit for the motor patterns that generate flight. This is the first description of an effect of heat shock that preserves neuronal communication under subsequent stressful conditions.