A study with a 4 × 2 factorial arrangement was conducted to investigate the effects of 4 dietary protein levels and 2 environmental conditions on acute phase proteins (APP), brain heat shock protein (HSP) 70 density, and growth performance of broiler chickens. Day-old broiler chicks (Cobb 500) were fed isocaloric diets but with various levels of crude protein (CP), namely, (1) 21.0 and 19.0% CP in starter and finisher diets, respectively (control), (2) 19.5 and 17.5% CP in starter and finisher diets, respectively (Diet A), (3) 18.0 and 16.0% CP in starter and finisher diets, respectively (Diet B), and (4) 16.5 and 14.5% CP in starter and finisher diets, respectively (Diet C). Equal numbers of birds from each diet were subjected to either 23±1°C throughout or 33±1°C for 6 h per d from 22 to 35 d of age. From d 1 to 21, feed intake (FI) and weight gain (WG) decreased linearly (P = 0.021 and P = 0.009, respectively), as CP level was reduced. During the heat treatment period (d 22 to 35), there were significant (P = 0.04) diet × heat treatment interactions for FCR. Diet had no effect on FCR among the unheated birds, but the ratio increased linearly (P = 0.007) as dietary CP level decreased. Irrespective of ambient temperature, there was a significant linear decrease in FI (P = 0.032) and WG (P < 0.001) as dietary CP level decreased. Low-CP diets improved the survivability of heat-stressed broilers when compared to those fed control diets. Low-CP diets linearly decreased (P < 0.01) APP (ovotransferrin and alpha-acid glycoprotein) responses. Both APP and HSP 70 reactions were elevated following heat treatment. In conclusion, feeding broilers with low-CP diets adversely affect the growth performance of broilers under heat stress condition. However, low-CP diets were beneficial in improving the survivability. Because APP are involved in the restoration of homeostasis, the adverse effect of low-CP diet on the synthesis of these proteins could be of concern.
Feeding of bacterially encapsulated heat shock proteins (Hsps) to invertebrates is a novel way to limit Vibrio infection. As an example, ingestion of Escherichia coli overproducing prokaryotic Hsps significantly improves survival of gnotobiotically cultured Artemia larvae upon challenge with pathogenic Vibrio campbellii. The relationship between Hsp accumulation and enhanced resistance to infection may involve DnaK, the prokaryotic equivalent to Hsp70, a major molecular chaperone in eukaryotic cells. In support of this proposal, heat-stressed bacterial strains LVS 2 (Bacillus sp.), LVS 3 (Aeromonas hydrophila), LVS 8 (Vibrio sp.), GR 8 (Cytophaga sp.), and GR 10 (Roseobacter sp.) were shown in this work to be more effective than nonheated bacteria in protecting gnotobiotic Artemia larvae against V. campbellii challenge. Immunoprobing of Western blots and quantification by enzyme-linked immunosorbent assay revealed that the amount of DnaK in bacteria and their ability to enhance larval resistance to infection by V. campbellii are correlated. Although the function of DnaK is uncertain, it may improve tolerance to V. campbellii via immune stimulation, a possibility of significance from a fundamental perspective and also because it could be applied in aquaculture, a major method of food production.
Athletes exercising in heat stress experience increased perceived fatigue acutely, however it is unknown whether heat acclimation (HA) reduces the magnitude of this perceptual response and whether different HA protocols influence the response. This study investigated sensations of fatigue following; acute exercise-heat stress; short- (5-sessions) and medium-term (10-sessions) HA; and between once- (ODHA) and twice-daily HA (TDHA) protocols. Twenty male participants (peak oxygen uptake: 3.75 ± 0.47 L·min-1) completed 10 sessions (60-min cycling at ~2 W·kg-1, 45°C/20% relative humidity) of ODHA (n = 10) or non-consecutive TDHA (n = 10). Sensations of fatigue (General, Physical, Emotional, Mental, Vigor and Total Fatigue) were assessed using the multi-dimensional fatigue scale inventory-short form pre and post session 1, 5 and 10. Heat adaptation was induced following ODHA and TDHA, with reductions in resting rectal temperature and heart rate, and increased plasma volume and sweat rate (P heat adaptations followed ODHA and TDHA, perceived fatigue is prolonged within TDHA.
Abbreviations: ∆: Change; ANOVA: Analysis of variance; HA: Heat acclimation; HR: Heart rate; IL-6: Interleukin-6; MFS-SF: Multi-dimensional fatigue symptom inventory-short form (MFSI-SF); MTHA: Medium-term heat acclimation; Na+: Sodium; ODHA: Once daily heat acclimation; PV: Plasma volume; RH: Relative humidity; RPE: Rating of perceived exertion; SD: Standard deviation; SE: Standard error of the slope coefficient or intercept; SEE : Standard error of the estimate for the regression equation; STHA: Short-term heat acclimation; TDHA: Twice daily heat acclimation; TC: Thermal Comfort; Tre: Rectal temperature; TSS: Thermal sensation; V̇O2peak: Peak oxygen uptake; WBSL: whole-body sweat loss.
In the search for universal vaccine candidates for the prevention of avian influenza, the non-structural (NS)-1 protein of avian influenza virus (AIV) H5N1 has shown promising potential for its ability to effectively stimulate the host immunity. This study was aimed to produce a bacterial expression plasmid using pRSET B vector to harbour the NS1 gene of AIV H5N1 (A/Chicken/Malaysia/5858/2004 (H5N1)) for protein expression in Escherichia coli (E. coli). The NS1 gene (687 bp) was initially amplified by polymerase chain reaction (PCR) and then cloned into a pGEM-T Easy TA vector. The NS1 gene was released from pGEM-T-NS1 using EcoRI and XhoI restriction enzymes (RE). The pRSET B vector was also linearized using the same RE. The digested NS1 gene and linearized pRSET B were ligated using T4 DNA ligase to form the expression plasmid, pRSET B-NS1. The NS1 gene sequence in pRSET B-NS1 was confirmed by DNA sequencing. To prepare recombinant bacterial cells for protein expression in the future, pRSET B-NS1 was transformed into E. coli strain BL21 (DE3) by heat-shock. Colonies bearing the recombinant plasmid were screened using PCR. The DNA sequencing analysis revealed that the NS1 gene sequence was 97% homologous to that of AIV H5N1 A/Chicken/Malaysia/5858/2004 (H5N1). These results indicated that the NS1 gene of influenza A/Chicken/Malaysia/5858/2004 (H5N1) was successfully amplified and cloned into a pRSET B vector. Bacterial colonies carrying pRSET B-NS1 can be used for the synthesis of NS1-based influenza vaccine in the future and thereby aid in the prevention of avian influenza.
International competition inevitably presents logistical challenges for athletes. Events such as the Tokyo 2020 Olympic Games require further consideration given historical climate data suggest athletes will experience significant heat stress. Given the expected climate, athletes face major challenges to health and performance. With this in mind, heat alleviation strategies should be a fundamental consideration. This review provides a focused perspective of the relevant literature describing how practitioners can structure male and female athlete preparations for performance in hot, humid conditions. Whilst scientific literature commonly describes experimental work, with a primary focus on maximizing magnitudes of adaptive responses, this may sacrifice ecological validity, particularly for athletes whom must balance logistical considerations aligned with integrating environmental preparation around training, tapering and travel plans. Additionally, opportunities for sophisticated interventions may not be possible in the constrained environment of the athlete village or event arenas. This review therefore takes knowledge gained from robust experimental work, interprets it and provides direction on how practitioners/coaches can optimize their athletes' heat alleviation strategies. This review identifies two distinct heat alleviation themes that should be considered to form an individualized strategy for the athlete to enhance thermoregulatory/performance physiology. First, chronic heat alleviation techniques are outlined, these describe interventions such as heat acclimation, which are implemented pre, during and post-training to prepare for the increased heat stress. Second, acute heat alleviation techniques that are implemented immediately prior to, and sometimes during the event are discussed. Abbreviations: CWI: Cold water immersion; HA: Heat acclimation; HR: Heart rate; HSP: Heat shock protein; HWI: Hot water immersion; LTHA: Long-term heat acclimation; MTHA: Medium-term heat acclimation; ODHA: Once-daily heat acclimation; RH: Relative humidity; RPE: Rating of perceived exertion; STHA: Short-term heat acclimation; TCORE: Core temperature; TDHA: Twice-daily heat acclimation; TS: Thermal sensation; TSKIN: Skin temperature; V̇O2max: Maximal oxygen uptake; WGBT: Wet bulb globe temperature.
The aim of this work was to evaluate the impacts of feeding different levels of postbiotic RI11 on antioxidant enzyme activity, physiological stress indicators, and cytokine and gut barrier gene expression in broilers under heat stress. A total of 252 male broilers Cobb 500 were allocated in cages in environmentally controlled chambers. All the broilers received the same basal diet from 1 to 21 d. On day 22, the broilers were weighed and grouped into 7 treatment groups and exhibited to cyclic high temperature at 36 ± 1°C for 3 h per day until the end of the experiment. From day 22 to 42, broilers were fed with one of the 7 following diets: negative control, basal diet (0.0% RI11) (NC group); positive control, NC diet + 0.02% (w/w) oxytetracycline (OTC group); antioxidant control, NC diet + 0.02% (w/w) ascorbic acid. The other 4 other groups were as follows: NC diet + 0.2% cell-free supernatant (postbiotic RI11) (v/w), NC diet + 0.4% cell-free supernatant (postbiotic RI11) (v/w), NC diet + 0.6% cell-free supernatant (postbiotic RI11) (v/w), and NC diet + 0.8% cell-free supernatant (postbiotic RI11) (v/w). Supplementation of different levels (0.4, 0.6, and 0.8%) of postbiotic RI11 increased plasma glutathione peroxidase, catalase, and glutathione enzyme activity. Postbiotic RI11 groups particularly at levels of 0.4 and 0.6% upregulated the mRNA expression of IL-10 and downregulated the IL-8, tumor necrosis factor alpha, heat shock protein 70, and alpha-1-acid glycoprotein levels compared with the NC and OTC groups. Feeding postbiotic RI11, particularly at the level of 0.6%, upregulated ileum zonula occludens-1 and mucin 2 mRNA expressions. However, no difference was observed in ileum claudin 1, ceruloplasmin, IL-6, IL-2, and interferon expression, but downregulation of occludin expression was observed as compared with the NC group. Supplementation of postbiotic RI11 at different levels quadratically increased plasma glutathione peroxidase, catalase and glutathione, IL-10, mucin 2, and zonula occludens-1 mRNA expression and reduced plasma IL-8, tumor necrosis factor alpha, alpha-1-acid glycoprotein, and heat shock protein 70 mRNA expression. The results suggested that postbiotics produced from Lactiplantibacillus plantarum RI11 especially at the level of 0.6% (v/w) could be used as an alternative to antibiotics and natural sources of antioxidants in poultry feeding.
The heat-shock responses of barley (Hordeum vulgare L. cv Hi- malaya) aleurone layers incubated with or without gibberellic acid (GA3) were compared. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that heat shock blocked the synthesis and secretion of secretory proteins from GA3-treated layers but not untreated layers. This suppression of secretory protein synthesis has been correlated with changes in endoplasmic reticulum (ER) membranes (F.C. Belanger, M. R. Brodl, T.-h.D. Ho [1986] Proc Natl Acad Sci USA 83: 1354-1358; L. Sticher, A.K. Biswas, D.S. Bush, R.L. Jones [1990] Plant Physiol 92: 506-513). Our secretion data suggested that the ER membranes of aleurone layers incubated without GA3 may be more heat shock tolerant. To investigate this, the lipid profiles of membrane extracts in aleurone layers labeled with [14C]glycerol were examined. Heat shock markedly increased [14C]glycerol incorporation into phosphatidylcholine (PC), and gas chromatography revealed an increase in the amount of saturated fatty acids associated with thin layer chromatography-purified PC in GA3-treated layers. In contrast, aleurone layers incubated without GA3 at normal temperature contained PC-associated fatty acids with a greater degree of saturation than GA3-treated layers. Heat shock modestly increased the degree of fatty acid saturation in untreated aleurone layers. This same trend was noted in fatty acids isolated from ER membranes purified by continuous sucrose density centrifugation. We propose that increased fatty acid saturation may help sustain ER membrane function in heat-shocked aleurone layers incubated in the absence of GA3.