Glucose homeostasis and the enteroinsular axis in the horse: A possible role in equine metabolic syndrome

One of the principal components of equine metabolic syndrome (EMS) is hyperinsulinaemia combined with insulin resistance. It has long been known that hyperinsulinaemia occurs after the development of insulin resistance. But it is also known that hyperinsulinaemia itself can induce insulin resistance and obesity and might play a key role in the development of metabolic syndrome. This review focuses on the physiology of glucose and insulin metabolism and the pathophysiological mechanisms in glucose homeostasis in the horse (compared with what is already known in humans) in order to gain insight into the pathophysiological principles underlying EMS. The review summarizes new insights on the oral uptake of glucose by the gut and the enteroinsular axis, the role of diet in incretin hormone and postprandial insulin responses, the handling of glucose by the liver, muscle and fat tissue, and the production and secretion of insulin by the pancreas under healthy and disrupted glucose homeostatic conditions in horses.     

Dopamine modulates the physiological response of the tiger shrimp Penaeus monodon

Levels of glucose, lactate, pO₂, pCO₂, HCO₃⁻, TCO₂, Na⁺, K⁺, Cl⁻, protein, and oxyhemocyanin in the hemolymph and its osmolality and pH were measured when tiger shrimp, Penaeus monodon (13.5 ± 1.5 g body weight), were individually injected with saline or dopamine at 10^− 8, 10^− 7, or 10^− 6 mol shrimp^− 1. Results showed that hemolymph glucose, lactate, pCO₂, HCO₃⁻, and TCO₂ values increased from 2 to 4 h; hemolymph osmolality, Na⁺, and total protein had increased at 2 h; and hemolymph K⁺ decreased from 2 to 8 h after the dopamine injection. All physiological parameters returned to the control values 4–16 h after receiving dopamine. The dopamine injection also significantly decreased the oxyhemocyanin/protein ratio of P. monodon which occurred at 2 h, resulting from an elevation of hemolymph protein and a slight decrease of oxyhemocyanin. These results suggest that stress-inducing dopamine caused a transient period of modulation of energy metabolism, osmoregulation, respiration, and the acid–base balance in P. monodon in adapting to this environmental stress.     

离子色谱法测定乳制品中硫氰酸盐的研究

[目的]建立乳制品中硫氰酸盐含量测定的离子色谱方法。[方法]样品溶液经乙酸沉淀,去除蛋白质及脂肪的干扰后,过滤装瓶。采用Ion Pac AS11-HC柱(4 mm×250 mm)对其进行分离。以保留时间定性,试样中硫氰酸根峰面积比与标准系列比较定量。[结果]试验表明,硫氰酸盐在0.1~2.0 mg/L范围内线性关系良好,相关系数为R2=0.999 6,添加回收率为92.0%~96.6%,变异系数分别为1.18%~2.28%,定量限为1.0 mg/kg。[结论]该方法简便、快速、可靠,可用于市售乳制品中硫氰酸盐含量的测定。     

NaCl胁迫对不同耐盐性小黑麦幼苗Na~+、K~+、Cl~-吸收及分配的影响

为了解小黑麦耐盐性与离子吸收之间的关系,以4个耐盐性不同的小黑麦品种为材料,分析了不同浓度NaCl(0、50、100、200mmol·L-1)胁迫处理10d后,小黑麦幼苗鲜重、地上部分和根部Na+、K+、Cl-分布以及限钠能力和K+/Na+的变化。结果表明,随NaCl浓度的升高,4个小黑麦品种鲜重均逐步降低,Na+、Cl-含量大幅提高;除中饲828外,其他3个品种的地上部Na+、Cl-含量均高于根部;K+含量随NaCl浓度的升高而逐步下降,根部下降幅度大于地上部。随NaCl浓度的升高,小黑麦地上部限钠能力及地上部分和根部K+/Na+逐渐降低。在4个品种中,抗盐性强的中饲828地上部能维持相对较低的Na+、Cl-含量,具有较高的K+/Na+,生物量也较高;盐敏感品种劲松49则相反。说明限制地上部Na+的吸收和维持较高的K+/Na+是小黑麦耐盐的策略之一。     

外源葡萄糖对盐胁迫下黄瓜幼苗光合作用和离子分布的影响

[目的]为了探讨外源葡萄糖缓解盐胁迫下黄瓜幼苗生理伤害的作用机制。[方法]采用营养液水培法,以盐敏感型黄瓜品种‘津春2号’为材料,研究外源葡萄糖对盐胁迫下黄瓜幼苗生长、叶绿素含量、光合作用以及体内离子分布的影响。[结果]盐胁迫(65mmol/L Na Cl)显著降低了黄瓜幼苗叶片的叶绿素含量、净光合速率(Pn)、气孔导度(Gs)和胞间CO2浓度(Ci),限制了黄瓜幼苗植株的生长,而根施2 mmol/L葡萄糖缓解了盐胁迫诱导的光合速率和生长下降;在盐胁迫下,黄瓜幼苗叶片、茎和根中Na+和Cl-含量显著增加,而K+和Mg2+含量明显降低,外源葡萄糖处理逆转盐胁迫诱导黄瓜植株体内离子含量的变化。[结论]外源葡萄糖通过抑制根中Na+和Cl-向地上部的运输,减轻叶片中Na+和Cl-积累诱导的离子毒害,从而缓解盐胁迫对光合作用的抑制,进而促进盐胁迫下黄瓜幼苗的生长。     

盐胁迫对油葵种子萌发和幼苗生长及离子吸收、分布的效应

研究了100～300mmol/L NaCl胁迫对油葵种子萌发、幼苗生长及其离子吸收、分布的效应.结果表明,油葵在种子萌发出苗阶段表现较强的耐盐性.100～300mmol/L NaCl胁迫对油葵萌发的影响主要表现为推迟出苗、不影响出苗率.但100～300mmol/L NaCl处理均显著抑制幼苗生长,干物质积累速率下降.Na 主要积累在茎秆、根部,叶片中较少.Cl-主要积累于茎秆和叶柄,叶片和根系中较少.盐胁迫下叶片、叶柄中K 含量显著增加,根系吸收SK,Na、叶柄和叶片运输TSK,Na均显著上升,表明油葵在离子吸收和向上运输过程中,对K 具有较强的选择性,这是油葵具有较强耐盐性的主要原因.     

离子注入技术及其在小麦育种中的应用

离子注入是一种新的诱变技术,已在作物诱变育种中发挥了重要作用.本文对离子注入引起变异的诱变机理及由此引起的生物体在生理生化、细胞学、分子遗传学等方面产生的各种生物效应进行了综述,同时对离子注入技术在小麦新品种选育、新种质创造以及介导外源基因导入等方面的应用做了分析,并对离子注入改良小麦的发展前景作了展望.     

基于Gouy-Chapman理论估算碱金属离子在Cu2+-蒙脱石表面Hofmeister能

Hofmeister效应在离子交换吸附过程中具有重要的科学意义。本研究基于Gouy-Chapman理论研究三种碱金属阳离子（Na+、K+、Cs+）在Cu2+-蒙脱石饱和样表面吸附过程的Hofmeister效应,进一步计算了离子-表面Hofmeister能以及表观电荷系数。研究发现：（1）Na+ 、K+ 、Cs+在Cu2+-蒙脱石表面的吸附均表现为弱静电力作用下的一级动力学过程, 平均吸附速率以及平衡吸附量均表现出明显的Hofmeister效应,呈现出Na+ < K+ < Cs+的趋势;（2）Hofmeister能随着电解质浓度的降低而增加,在Cs+-粘土矿物相互作用中,Hofmeister能为主要贡献者,在K+/Na+-粘土矿物相互作用,经典库伦能中为主要贡献者;（3）非经典极化作用显著增大了离子的表观电荷系数,Na+、K+、Cs+的表观电荷系数分别从标准的+1值增加为+1.14、+1.76和+2.78。本研究明确了Hofmeister效应主要来源于离子的非经典极化作用引起的离子与表面相互作用能的差异,为阐明土壤这一特殊体系的界面反应机制提供了新的思路。     

A review of phosphorus homeostasis and the impact of different types and amounts of dietary phosphate on metabolism and renal health in cats

Elevated concentrations of serum phosphate are linked with progression and increased case fatality rate in animals and humans with chronic kidney disease. Elevated concentrations of serum phosphate can be a risk factor for development of renal and cardiovascular diseases or osteoporosis in previously healthy people. In rodents, an excess intake of dietary phosphorus combined with an inverse dietary calcium : phosphorus ratio (<1 : 1) contributes to renal calcification. Renal injury also has occured in cats fed experimental diets supplemented with highly soluble phosphate salts, especially in diets with inverse calcium : phosphorus ratios. However, not all phosphorus sources contribute similarly to this effect. This review, which focuses on cats, summarizes the published evidence regarding phosphorus metabolism and homeostasis, including the relative impact of different dietary phosphorus sources, and their impact on the kidneys. No data currently shows that commercial cat foods induce renal injury. However, some diets contain high amounts of phosphorus relative to recommendations and some have inverse Ca : P ratios and so could increase the risk for development of kidney disease. While limiting the use of highly soluble phosphates appears to be important, there are insufficient data to support a specific upper limit for phosphate intake. This review also proposes areas where additional research is needed in order to strengthen conclusions and recommendations regarding dietary phosphorus for cats.     

离子束生物技术在小麦育种上的应用

阐述了离子束生物技术在小麦育种领域应用情况 ,概括介绍了离子束诱变育种和离子束介导转基因技术的原理及方法 ,对离子束小麦育种过程中涉及的主要技术参数作了详细描述。还介绍了最近发现的离子束诱变小麦遗传新规律和离子束辅助外源裸露大分子DNA转移在小麦育种中的新进展 ,提出了离子束生物技术在育种领域急待解决的问题和应用前景