Effect of Foliar GA3 and ABA Applications on Reactive Oxygen Metabolism in Black Currants (Ribes nigrum L.) During Bud Para-dormancy and Secondary Bud Burst

The secondary bud burst can cause around 10％-20％ yield losses in black currants, an economically important crop in parts of Europe, Asia and North America. The metabolism of reactive oxygen species (ROS) has been linked to bud dormancy and its early release (secondary bud burst) in several fruit crops. But the relationship between ROS metabolism and the secondary bud burst is still not well understood in black currants. In the present study, two black currant cultivars (Adelinia and Heifeng) with opposing tendency of exhibiting the secondary bud burst were sprayed with abscisic acid (ABA) and gibberellic acid (GA3) to either inhibit or induce the secondary bud burst. The results showed that ABA inhibited the secondary bud burst by reducing the contents of ROS (H2O2, O2-?) in buds; decreasing the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); and increasing the contents of oxidized glutathione (GSSG) and ascorbic acid (AsA). GA3 effectively induced the secondary bud burst by increasing ROS contents; increasing the activities of several antioxidant enzymes, such as SOD, POD, CAT, glutathione reductase (GR), ascorbate peroxidase (APX) and the contents of reduced glutathione (GSH); and decreasing the contents of AsA. The experimental results showed that GA3 treatment increased the content of ROS, accelerated the metabolism of reactive oxygen species, and promoted the second burst of black currants. However, ROS metabolism was at a low level under ABA treatment, and the buds remained dormant. These results suggested that ROS metabolism might play an important role in the two black currants of the secondary bud burst.     

Risk Factors for the Development of Hypokalemia in Neonatal Diarrheic Calves

Background

Neonatal diarrheic calves have a clear negative potassium balance because of intestinal losses and decreased milk intake but in the presence of acidemia, they usually show normokalemic or hyperkalemic plasma concentrations.

Objectives

To assess whether marked hypokalemia occurs in response to the correction of acidemia and dehydration and to identify factors that are associated with this condition.

Animals

Eighty‐three calves with a clinical diagnosis of neonatal diarrhea.

Methods

Prospective cohort study. Calves were treated according to a clinical protocol using an oral electrolyte solution and commercially available packages of 8.4% sodium bicarbonate, 0.9% saline and 40% dextrose infusion solutions.

Results

The proportion of hypokalemic calves after 24 hours of treatment (19.3%) was twice as great as it was on admission to the hospital. Plasma K⁺ after 24 hours of treatment was not significantly correlated to venous blood pH values at the same time but positively correlated to venous blood pH values on admission (r = 0.51, P < .001). Base excess on admission (Odds ratio [OR] = 0.81, 95% confidence interval [CI] = 0.70–0.94), duration of diarrhea (OR = 1.37, 95% CI = 1.05–1.80), milk intake during hospitalization (OR = 0.54, 95% CI = 0.37–0.79) and plasma sodium concentrations after 24 hours (OR = 1.12, 95% CI = 1.01–1.25) were identified to be independently associated (P < .05) with a hypokalemic state after 24 hours of treatment.

Conclusions and Clinical Importance

Findings of this study suggest that marked depletion of body potassium stores is evident in diarrheic calves that suffered from marked metabolic acidosis, have a low milk intake and a long history of diarrhea.     

Secondary Stress Responses in Juvenile Brazilian Flounder,Paralichthys orbignyanus,throughout and after Exposure to Sublethal Levels of Ammonia and Nitrite

This study investigated the secondary stress responses of Paralichthys orbignyanus exposed to ammonia and nitrite and after recovery. Fish were exposed to 0.12, 0.28, and 0.57 mg NH₃‐N/L, or 5.72, 10.43, and 15.27 mg NO₂‐N/L for 10 d followed by the same time length for recovery. Ammonia‐ and nitrite‐free water was used as a control treatment. Blood samples were collected after 1, 5, and 10 d of exposure and after recovery. Fish exposed to ammonia presented lower and higher glucose levels after 10 d of exposure and recovery, respectively. Ammonia induced initial and transient ionic disturbances and metabolic alkalosis. Nitrite exposure caused hyperglycemia, increased plasma K⁺ levels, and respiratory alkalosis, whereas metabolic acidosis was observed after recovery. Increased proportion of monocytes and/or granulocytes and reduced number of lymphocytes were demonstrated in fish exposed to 0.28 mg NH₃‐N/L (Day 1) and 10.43 mg NO₂‐N/L (Day 5) and after recovery in the 0.28 and 0.57 mg NH₃‐N/L treatments. Exposure to ammonia decreased the proportion of granulocytes on Day 5. In conclusion, exposure to concentrations at 0.12 mg NH₃‐N/L and 5.72 mg NO₂‐N/L provoked physiological disorders in Brazilian flounder. Nonetheless, fish exposed to 5.72 mg NO₂‐N/L following a 10‐d recovery period showed complete resumption of homeostasis.     

Effect of Psammaplin A on in vitro Development of Bovine Aging Oocytes

To investigate the effect of histone deacetylation inhibitor Psammaplin A (PsA) on the development of bovine aging oocytes in vitro,oocytes were randomly divided into control group,aging group and 50 mmol/L PsA treated aging group (PsA group).Immunofluorescence staining and JC-1 were used to detect the blastocyst rate of bovine oocytes after parthenogenetic activation,the number of cells in blastocysts,apoptosis,reactive oxygen species (ROS),glutathione (GSH) and mitochondrial membrane potential intensity of embryos.The results showed that the blastocyst rate of the aging group was significantly lower than that of PsA and control groups (P<0.05).The blastocyst rate of PsA group was not significantly different from that of control group (P>0.05).The number of cells in the blastocysts of control group and PsA group were significantly higher than that of aging group (P<0.05).The number of cells in the blastocysts of PsA group was not significantly different from that of control group (P>0.05).The apoptosis rate in aging group was significantly higher than that of control and PsA groups (P<0.05),the apoptosis rate of PsA group was significantly higher than that of control group (P<0.05).The GSH level of MⅡ oocytes in aging group was significantly lower than that of control and PsA groups (P<0.05).There was no significant difference in GSH level between control and PsA groups (P>0.05).The ROS level of the embryos in aging group was significantly higher than that of control and PsA groups (P<0.05).The ROS level in PsA group was significantly higher than that of control group (P<0.05).The mitochondrial membrane potential of early embryos of aging group 4-8 cells was significantly lower than that of control and PsA groups (P<0.05).The mitochondrial membrane potential intensity of control group was significantly higher than that of PsA group (P<0.05).In summary,PsA could effectively delay the aging of bovine oocytes and improve the quality of oocytes.     

哺乳动物妊娠期钙代谢的研究进展

哺乳动物体内的钙代谢通常包括钙平衡和钙稳态。钙平衡是指体内总钙含量保持相对恒定的状态,钙稳态则指细胞内外的钙离子浓度保持稳定。肾脏、肠道、骨骼及雌性动物乳腺是动物体钙代谢的主要器官,其中存在着许多精细而复杂的调控网络。妊娠期钙代谢紊乱会严重影响母畜及胎儿的营养健康,维持体内钙代谢稳态对围产期哺乳动物尤为重要。本文综合近年来国内外妊娠期哺乳动物钙代谢相关研究,从不同组织器官钙代谢情况及钙代谢过程中重要的调节因子的调控作用进行综述,旨在为妊娠期哺乳动物钙代谢调控相关研究提供思路。     

花生硬脂酰-ACP酸脱饱和基因FAB2表达的分子机制

FAB2位于油酸合成通路的上游,编码硬脂酰-ACP脱饱和酶,调控硬脂酸(C18:0)向油酸(C18:1)转化。本研究发现高油酸品种开农176种子发育前期FAB2的表达量升高,而成熟期油酸过量积累会抑制FAB2的表达。利用开农176与开农70构建F2杂交群体,发现当植株油酸含量超过60%时会从整体水平上抑制FAB2的表达。种子发育前期,油酸不断积累会导致过氧化物酶活性升高,并且活性氧含量随之增加;但是在种子发育后期均降低,该结果与FAB2的表达量变化趋势相同。亚细胞定位结果表明, FAB2与FAD2分别定位于叶绿体与内质网。FAB2编码区序列多态性分析显示,该蛋白序列氮端的氨基酸结构缺失可能会导致硬脂酸含量升高。FAB2启动子序列存在大量AT碱基的富集区域,并且含有光响应、激素调控、转录因子结合的保守顺式元件。本研究发现过量积累的油酸会激活过氧化物酶介导的活性氧信号途径,进而通过细胞核内的未知转录因子调节上游基因FAB2的表达量,该结果不仅拓展了对FAB2的功能认知,也为培育高油酸花生品种提供了相关的理论指导。     

植物谷胱甘肽应答非生物胁迫的分子机制

谷胱甘肽(GSH)是一种普遍存在于植物中的抗氧化剂,在维持组织抗氧化防御和调节氧化还原敏感信号转导中起着关键作用。深入研究GSH在非生物胁迫中的作用,对从分子水平揭示植物GSH积累的调控机制具有重要意义。本研究从植物GSH代谢途径及其相关酶、GSH在植物应激反应中的调节、GSH参与植物激素代谢等方面进行综述,并对谷胱甘肽在植物生长发育、与其它信号通路间交互作用的研究前景进行展望,以期为植物谷胱甘肽代谢以及其在非生物胁迫方面的研究提供一定的理论参考。     

Overexpression of StRbohA in Arabidopsis thaliana enhances defence responses against Verticillium dahliae

Plant NADPH oxidases are key regulators of plant–microbe interactions and reactive oxygen species (ROS) are essential to plant defences against pathogens. A significant part in the role played by ROS has been ascribed to plant respiratory burst oxidase homologs (RBOHs). In potato (Solanum tuberosum), where RBOHs were previously shown to be involved in wound-induced oxidative burst, we assessed their expression after inoculation with Verticillium dahliae Kleb. and showed that StRbohA was the only homolog to be differentially induced in potato in response to inoculation. In order to investigate the potential role of this gene in plant protection against wilt diseases, we used Agrobacterium-mediated transformation of Arabidopsis to assess the effects of its overexpression on plant responses to V. dahliae. After inoculation with this pathogen, the transformed Arabidopsis line overexpressing StRbohA showed lower disease severity (percent damaged leaf area and vascular discoloration) as compared to the wild type. It also had higher ROS production and more cell death caused by hydrogen peroxide (H₂O₂), compared to the wild type. Suberization of root cells was also more pronounced in the line overexpressing StRbohA, and supports a possible role for StRBOHA in plant resistance to V. dahliae. Together, these findings indicate that overexpressed StRbohA in Arabidopsis enhances the ROS-mediated defence mechanisms against V. dahliae and can be a potential tool to improve plant resistance to this and other soilborne pathogens that cause wilts in economically important crops.     

Effect of AIR on Inflammatory Reaction Infected by Brucella

In order to investigate the effect of AIR on inflammatory reaction infected by Brucellamelitensis (16M), the AIR domain of Tecpr1 gene of murine macrophages RAW264.7 were knocked down (I-A), overexpressed (O-A) and reversed (OA-IA). Using the chlorine fluorescein (DCFH-DA) as a probe, we detected the variation of ROS production and mitochondria distribution by confocal laser scanning microscopy. We observed the expression changes of NLRP3, ASC and Caspase-1 by qRT-PCR and the expression changes of IL-18,IL-1β and Caspase-1 in host cells by ELISA. The results showed that 16M could stimulate RAW264.7 cells to produce ROS by time-dependent pathway, and I-A group and O-A group showed more abnormal accumulation of mitochondrial. The results of qRT-PCR and ELISA suggested that it had effect on the expression levels of NLRP3, ASC,Caspase-1 and IL-18, IL-1β and Caspase-1 in cells of different groups. Those results indicated that with AIR gene deletion, the release amount of ROS changed, mitochondrial clustered abnormally, and AIR was closely related to the activation of inflammasomes and induction of inflammatory reactions.