Royal jelly: can it reduce physiological strain of growing rabbits under Egyptian summer conditions?

Exposure of growing rabbits to heat stress during summer adversely affects their performance leading to major production losses. A total number of 48 rabbits, unsexed V-line weaned rabbits, were randomly divided into four experimental groups, temperature ranged from high at 32°C to low at 23°C. Animals of the 2nd, 3rd and 4th group were individually orally given 200, 400 or 800 mg royal jelly (RJ)/kg BW once a week, respectively, to evaluate RJ ability to reduce physiological strain resulted from heat stress. Weekly BW gain increased by 10.4, 11.8 and 10.8%, and feed conversion ratio was significantly improved by 20, 24 and 18% with RJ treatments. Serum total protein, albumin and globulin increased, whereas serum total lipids, cholesterol and triglycerides decreased with RJ treatments. Creatinine was reduced by 21, 30 and 18% and uric acid by 14, 25 and 18% compared with the heat stressed control with the three doses of RJ. Glucose level increased significantly to reach 116, 125, and 120% of heat stressed control. Calcium, phosphorus and alkaline phosphatase increased significantly with RJ treatments indicating the occurrence of active bone deposition. Thyroid hormone levels increased significantly to reach 108, 111, and 112% of heat stressed control rabbits with the three doses of RJ, counteracting the hypothyroid state resulted from heat stress. It can be concluded that RJ administration to heat stressed growing rabbits can reduce physiological strain resulted from heat stress.     

Endoplasmic reticulum stress induces the phosphorylation of small heat shock protein, Hsp27

There are several reports describing participation of small heat shock proteins (sHsps) in cellular protein quality control. In this study, we estimated the endoplasmic reticulum (ER) stress-induced response of Hsp27 and alphaB-crystallin in mammalian cells. Treatment targeting the ER with tunicamycin or thapsigargin induced the phosphorylation of Hsp27 but not of alphaB-crystallin in U373 MG cells, increase being observed after 2-10 h and decline at 24 h. Similar phosphorylation of Hsp27 by ER stress was also observed with U251 MG and HeLa but not in COS cells and could be blocked using SB203580, an inhibitor of p38 MAP kinase. Other protein kinase inhibitors, like G?6983, PD98059, and SP600125, inhibitors of protein kinase C (PKC), p44/42 MAP kinase, and JNK, respectively, were without major influence. Prolonged treatment with tunicamycin but not thapsigargin for 48 h caused the second induction of the phosphorylation of Hsp27 in U251 MG cells. Under these conditions, the intense perinuclear staining of Hsp27, with some features of aggresomes, was observed in 10%-20% of the cells.     

CHIP interacts with heat shock factor 1 during heat stress

Heat shock factor 1 (HSF1) is a major transactivator of heat shock genes in response to stress and mediates cell protection against various harmful conditions. In this study, we identified the interaction of CHIP (carboxyl terminus of the heat shock cognate protein 70-interacting protein) with the N-terminus of HSF1. Using GST full-down assay, we found that CHIP directly interacts with C-terminal deleted HSF1 (a.a. 1-290) but not with full-length HSF1 under non-stressed conditions. Interestingly, interaction of CHIP with full-length HSF1 was induced by heat shock treatment. The structural change of HSF1 was observed under heat stressed conditions by CD spectra. These observations demonstrate the direct interaction between HSF1 and CHIP and this interaction requires conformational change of HSF1 by heat stress.     

干旱绿洲灌区大白菜施磷效应与磷肥投入阈值

针对磷肥施用量大且利用率不高的问题,通过2011—2013年在甘肃省农业科学院张掖绿洲灌区农业生态环境重点野外台站进行定位试验,研究了不同施磷量对露地大白菜产量、磷肥利用率以及磷素平衡的影响.结果表明:大白菜产量随施磷量的增加先增加后呈下降的趋势.在施磷量为112.52 kg·hm^-2时产量达到最高(5489.1 kg·hm^-2),且显著高于其他处理,与不施磷处理相比,增产13.3%~23.8%,此时磷肥利用率为14.2%.土壤中土壤有效磷(Olsen-P)和可溶性总磷(CaCl-P)呈现较好的正相关性,土壤Olsen-P含量为24.22 mg·kg-12时对应的施磷量为111.1 kg·hm^-2,表明当土壤中Olsen-P含量小于24.22 mg·kg-1时,土壤中的磷素不发生盈余,对环境不造成污染.当施磷量为60.17 kg·hm^-2时,磷输入与输出达到平衡,即此施磷量水平能满足作物的需求.结合研究区的土壤肥力状况,综合产量、磷肥利用率及土壤有效磷含量,干旱绿洲灌区磷肥投入阈值在60.17~112.52 kg·hm^-2时,能保证露地大白菜高产,并且不会造成环境污染.     

Stress-mediated signaling in PC12 cells - the role of the small heat shock protein,Hsp27, and Akt in protecting cells from heat stress and nerve growth factor withdrawal

We have investigated the role of stress-activated signaling pathways and the small heat shock protein, Hsp27, in protecting PC12 cells from heat shock and nerve growth factor (NGF) withdrawal-induced apoptosis. PC12 cells and a stable cell line overexpressing Hsp27 (HSPC cells) were subjected to heat shock. This resulted in the rapid activation of Akt followed by p38 mitogen-activated protein kinase (MAPK) signaling, with phosphorylation and intracellular translocation of Hsp27 also detectable. Hsp27 was found to form an immunoprecipitable complex with Akt and p38 MAPK in both non-stimulated and heat shocked cells, although after heat shock there was a gradual dissociation of Akt and p38 from the Hsp27. Cells were differentiated with NGF and then subjected to NGF withdrawal, a treatment which results in substantial cell death over 24-72 h. Hsp27 was shown to be protective against this treatment, since HSPC cells which overexpress Hsp27 showed significantly less cell death than the parental PC12 cells. In addition, we observed that phosphorylation of Akt was maintained in HSPC cells subjected to heat shock and NGF withdrawal compared with the parental cells. Taken together, our results suggest that Hsp27 may protect Akt from dephosphorylation and may also act in stabilizing Akt.     

Tomato stigma exsertion induced by high temperature is associated with the jasmonate signalling pathway

High temperature (HT) is becoming an increasingly serious factor in limiting crop production with global climate change. During hot seasons, owing to prevailing HT, cultivated tomatoes are prone to exhibiting stigma exsertion, which hampers pollination and causes fruit set failure. However, the underlying regulatory mechanisms of the HT‐induced stigma exsertion remain largely unknown. Here, we demonstrate that stigma exsertion induced by HT in cultivated tomato is caused by more seriously shortened stamens than pistils, which is different from the stigma exsertion observed in wild tomato species. Under the HT condition, the different responses of pectin, sugar, expansin, and cyclin cause cell wall remodelling and differentially localized cell division and selective cell enlargement, which further determine the lengths of stamens and pistils. In addition, auxin and jasmonate (JA) are implicated in regulating cell division and cell expansion in stamens and pistils, and exogenous JA instead of auxin treatment can effectively rescue tomato stigma exsertion through regulating the JA/COI1 signalling pathway. Our findings provide a better understanding of stigma exsertions under the HT condition in tomato and uncover a new function of JA in improving plant abiotic stress tolerance.     

Does Fire Trigger Seed Germination in the Neotropical Savannas? Experimental Tests with Six Cerrado Species

The Cerrado (Brazilian savanna) is a biodiversity hotspot with a history of fire that goes back as far as 10 million years. Fire has influenced the evolution of several aspects of the vegetation, including reproduction and life cycles. This study tested how fire by‐products such as heat and smoke affect the germination of six species common to two Cerrado open physiognomies: wet grasslands and the campo sujo (grassland with scattered shrubs and dwarf trees). We subjected seeds collected in northern Brazil to heat shock and smoke treatments, both separately and combined, using different temperatures, exposure times, and smoke concentrations in aqueous solutions. High temperatures and smoke did not break seed dormancy nor stimulate germination of the Cerrado study species. However, seeds were not killed by high temperatures, indicating that they are fire‐tolerant. Our findings differed from those of other fire‐prone ecosystems (mostly of Mediterranean vegetation), where fire stimulates germination. Moreover, we provide important information regarding germination strategies of non‐woody Cerrado plants, showing the importance of considering the tolerance of seeds to high temperatures when evaluating fire‐related traits in fire‐prone ecosystems.     

Osmotic Survival of the Entomopathogenic Nematode Steinernema carpocapsae

The effect of different osmolytes on the viability and the effect of osmotic pressure on the induction of a dormant state similar to that caused by a slow desiccation rate were evaluated in the entomopathogenic nematode Steinernema carpocapsae ‘All’. For both experiments, a high-temperature (45°C) assay (HTA) was employed. Exposing fresh infective juveniles to the HTA resulted in a drastic reduction in viability. Using the same assay, the mortality of desiccated nematodes was gradual, showing an enhanced ability to withstand high-temperature conditions. The patterns of decline in viability in the evaporatively dehydrated and the osmotically desiccated nematodes were similar. Most of the salts tested in the screening assay caused high mortality levels among the nematodes within the first 24 h of exposure. In contrast, the nonionic solutes tested did not hamper the viability of the infective juveniles. In these nonionic solutions, all nematodes were completely shrunk after 48 h. Furthermore, 72-h exposure to these solutions resulted in an increase in heat tolerance similar to that of the evaporatively dehydrated nematodes. A substantial increase in heat tolerance was recorded in the treatments with glycerol solutions at concentrations from 2.2 to 3.8 M. A similar effect was obtained by polyethylene glycol (PEG) 300 MW at concentrations ranging from 1.2 to 1.6 M. PEG 600 MW induced enhancement of heat tolerance at a concentration of 0.8 M. A high level of viability was attained among nematodes that were stored for 72 days following a gradual increase in glycerol concentrations. Exposure of these nematodes to 45°C in the HTA resulted in 87.3 ± 4.7 and 49.2 ± 3.9% survival after 4 and 8 h, respectively. Reduction in viability was observed among nematodes that were directly exposed to the glycerol solution over a 19-day storage period. With this treatment, survival levels of 72.7 ± 3.9 and 26.5 ± 4.7% after 4 and 8 h, respectively, were recorded in the HTA. Reduction in viability among nematodes stored in distilled water was noted after 36 days of storage. Evaluation of nematode infectivity by two criteria (insect mortality and invasion rate) indicated that infectivity of nematodes desiccated by gradual osmotic pressure induced by glycerol was similar to that of fresh nematodes after 54 days in storage at 25°C. In comparison, infectivity of nematodes stored in distilled water declined significantly compared to that of fresh nematodes.