Glucose transport and milk secretion during manipulated plasma insulin and glucose concentrations and during LPS‐induced mastitis in dairy cows

In dairy cows, glucose is essential as energy source and substrate for milk constituents. The objective of this study was to investigate effects of long‐term manipulated glucose and insulin concentrations in combination with a LPS‐induced mastitis on mRNA abundance of glucose transporters and factors involved in milk composition. Focusing on direct effects of insulin and glucose without influence of periparturient endocrine adaptations, 18 dairy cows (28 ± 6 weeks of lactation) were randomly assigned to one of three infusion treatments for 56 h (six animals each). Treatments included a hyperinsulinemic hypoglycaemic clamp (HypoG), a hyperinsulinemic euglycaemic clamp (EuG) and a control group (NaCl). After 48 h of infusions, an intramammary challenge with LPS from E. coli was performed and infusions continued for additional 8 h. Mammary gland biopsies were taken before, at 48 (before LPS challenge) and at 56 h (after LPS challenge) of infusion, and mRNA abundance of genes involved in mammary gland metabolism was measured by RT‐qPCR. During the 48 h of infusions, mRNA abundance of glucose transporters GLUT1, 3, 4, 8, 12, SGLT1, 2) was not affected in HypoG, while they were downregulated in EuG. The mRNA abundance of alpha‐lactalbumin, insulin‐induced gene 1, κ‐casein and acetyl‐CoA carboxylase was downregulated in HypoG, but not affected in EuG. Contrary during the intramammary LPS challenge, most of the glucose transporters were downregulated in NaCl and HypoG, but not in EuG. The mRNA abundance of glucose transporters in the mammary gland seems not to be affected by a shortage of glucose, while enzymes and milk constituents directly depending on glucose as a substrate are immediately downregulated. During LPS‐induced mastitis in combination with hypoglycaemia, mammary gland metabolism was more aligned to save glucose for the immune system compared to a situation without limited glucose availability during EuG.     

Adenosine protects Sprague Dawley rats from high‐fat diet and repeated acute restraint stress‐induced intestinal inflammation and altered expression of nutrient transporters

This study investigated the effect of repeated acute restraint stress and high‐fat diet (HFD) on intestinal expression of nutrient transporters, concomitant to intestinal inflammation. The ability of adenosine to reverse any change was examined. Six‐week‐old male Sprague Dawley rats were divided into eight groups: control or non‐stressed (C), rats exposed to restraint stress for 6 h per day for 14 days (S), control rats fed with HFD (CHF) and restraint‐stressed rats fed with HFD (SHF); four additional groups received the same treatments and were also given 50 mg/l adenosine dissolved in drinking water. Fasting blood glucose, plasma insulin, adiponectin and corticosterone were measured. Intestinal expression of SLC5A1, SLC2A2, NPC1L1 and TNF‐α was analysed. Histological evaluation was conducted to observe for morphological and anatomical changes in the intestinal tissues. Results showed that HFD feeding increased glucose and insulin levels, and repeated acute restraint stress raised the corticosterone level by 22%. Exposure to both stress and HFD caused a further increase in corticosterone to 41%, while decreasing plasma adiponectin level. Restraint stress altered intestinal expression of SLC5A1, SLC2A2 and NPC1L1. These changes were enhanced in SHF rats. Adenosine was found to alleviate HFD‐induced increase in glucose and insulin levels, suppress elevation of corticosterone in S rats and improve the altered nutrient transporters expression profiles. It also prevented upregulation of TNF‐α in the intestine of SHF rats. In summary, a combination of stress and HFD exaggerated stress‐ and HFD‐induced pathophysiological changes in the intestine, and biochemical parameters related to obesity. Adenosine attenuated the elevation of corticosterone and altered expression of SLC5A1, NPC1L1 and TNF‐α.     

荻草谷网蚜ABCG1基因的克隆及表达模式分析

荻草谷网蚜Sitobion miscanthi是严重威胁我国小麦生产安全的迁飞性害虫。蜕皮激素是参与蚜虫翅型分化调控的内激素, 在有翅成蚜体内保持高滴度, 且诱导后代产生更高比例的无翅蚜, 其进出靶细胞需要经过细胞膜上特定蛋白的转运。ATP结合盒转运蛋白家族G亚家族(ATP-binding cassette transporter G, ABCG)中的 ABCG1是通过跨膜转运昆虫类固醇、对蜕皮激素信号进行负调控的功能蛋白之一, 在蚜虫中尚未见报道。本文克隆了荻草谷网蚜ABCG1(SmisABCG1)基因, 并进行了序列比对、系统进化分析以及不同组织部位和发育时期表达模式分析。结果显示, SmisABCG1基因的开放阅读框全长为1 851 bp, 编码616个氨基酸, 含7个跨膜结构域, 符合ABCG蛋白家族典型结构特性, 基因登录ID:OP626323。昆虫间ABCG1较保守, 该蛋白系统进化关系与各自物种间亲缘关系的远近保持一致。其中, SmisABCG1与来自豌豆蚜、禾谷缢管蚜、棉蚜、花生蚜和雪松长足大蚜等的ABCG1氨基酸序列高度一致(>87%), 以上蚜虫聚为一支。与SmisABCG1亲缘关系最近的是豌豆蚜的ABCG1, 其次是半翅目的褐飞虱、白背飞虱和灰飞虱, 与膜翅目的新疆菜叶蜂、阿里山潜蝇茧蜂以及鞘翅目的赤拟谷盗、蜂箱小甲虫亲缘关系较远。该基因在伪胚胎和成蚜阶段高表达。包含伪胚胎的有翅、无翅成蚜整蚜SmisABCG1的转录水平无显著差异, 但其在来自有翅成蚜的伪胚胎中的转录水平高于无翅成蚜伪胚胎, 证实无翅成蚜自身的转录水平较高, 而有翅成蚜较低。进一步分析显示这一差异主要是无翅蚜胸部显著高表达所导致。基于该蛋白对蜕皮激素负调控, 与有翅成蚜转录水平低, 但蜕皮激素水平更高相符合。     

Taurine transporter from the giant Pacific oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis>: function and expression in response to hyper- and hypo-osmotic stress

ABSTRACT:   Taurine is the primary osmolyte in marine molluscs, whose cellular osmo-conforming process is vital for environmental adaptation because of a lack of osmotic homeostasis. Here, cDNA cloning and expression, and functional analyses of taurine transporter (TAUT) from the giant Pacific oyster are reported on. The deduced amino-acid sequence of oyster TAUT (oyTAUT) showed 47–51% identity to those of vertebrate TAUT, whereas identity among the vertebrates is 78–95%. Functional analysis of oyTAUT expressed in Xenopus oocytes revealed that oyTAUT has a lower affinity and specificity for taurine and a requirement for higher NaCl concentration, compared with vertebrate TAUT. Taken together with similar functional properties of TAUT from mussel, indicated by our previous study, it is possible that these functional features reflect the internal environment of the molluscs (i.e. higher taurine and NaCl concentrations). Oyster taurine transporter mRNA expression was induced by not only hyper-osmotic stress, similar to other TAUT, but also hypo-osmotic stress. It is speculated that the expression in response to hypo-osmotic stress was induced by a substantial decrease in tissue taurine content following the decrease in the internal osmolality.     

Lamellarin O,a Pyrrole Alkaloid from an Australian Marine Sponge,Ianthella sp., Reverses BCRP Mediated Drug Resistance in Cancer Cells

ATP binding cassette (ABC) transporters, such as P-gp, BCRP and MRP1, can increase efflux of clinical chemotherapeutic agents and lead to multi-drug resistance (MDR) in cancer cells. While the discovery and development of clinically useful inhibitors has proved elusive to date, this molecular target nevertheless remains a promising strategy for addressing and potentially overcoming MDR. In a search for new classes of inhibitor, we used fluorescent accumulation and efflux assays supported by cell flow cytometry and MDR reversal assays, against a panel of sensitive and MDR human cancer cell lines, to evaluate the marine sponge co-metabolites 1–12 as inhibitors of P-gp, BCRP or MRP1 initiated MDR. These studies identified and characterized lamellarin O (11) as a selective inhibitor of BCRP mediated drug efflux. A structure–activity relationship analysis inclusive of the natural products 1–12 and the synthetic analogues 13–19, supported by in silico docking studies, revealed key structural requirements for the lamellarin O (11) BCRP inhibitory pharmacophore.     

QTLs and candidate genes for chlorate resistance in rice (Oryzasativa L.)

Chlorate resistance is one of the reliable characters in Indica/Japonica classification. To understand the genetic basis of chlorate resistance is very important for revealing the evolutionary mechanism of Indica/Japonica differentiation. In this study, a doubled haploid (DH) population derived from anther culture of ZYQ8/JX17, a typical Indica and Japonica hybrid, was used as the genetic material to investigate chlorate sensitivity of the parents and DH lines. The quantitative trait loci (QTLs) of chlorate resistance were analyzed based on the molecular linkage map of this population. Total of 3 QTLs (qCHR-2, qCHR-8 and qCHR-10) for chlorate resistance were detected on chromosomes 2, 8 and 10, respectively. A QTL × QTL epistatic interaction was detected between qCHR-2 and qCHR-10. Genes involved in nitrogen assimilation, such as nitrate reduction, molybdenum cofactor biosynthesis and nitrate transport were strong candidates of QTLs for chlorate resistance. A putative nitrate reductase gene (8611.t00011), and two putative nitrate reductase genes (9319.t00010 and 9319.t00012) were in the genomic region of qCHR-2, and qCHR-8, respectively, and a putative nitrate transporter gene (756.t00011) was in the region of qCHR-10. The expression of 8611.t00011, 9319.t00010 and 756.t00011 were confirmed by the corresponding cDNAs, and 2 in/del and 12 SNPs in the coding regions of these three genes were found between Indica (cv. 9311) and Japonica (cv. Nipponbare) in silico. These results indicated that these three genes were candidates of the chlorate resistance QTLs. An in/del in the coding region of 8611.t00011 was used to develop a new PCR marker. A polymorphism was detected between JX17/Nipponbare and ZYQ8/9311. This polymorphism corresponds to the chlorate sensitivity of Nipponbare and 9311. This marker was located between Y8007R and RM250 on chromosome 2 in the DH population, where qCHR-2 was also located.     

接种丛枝菌根真菌对小麦根内氮转运蛋白基因表达的影响

通过盆栽试验,研究了在低氮(不施氮)和高氮(施氮0.2 g·kg~(-1))水平下接种不同种类丛枝菌根(AM)真菌[Funneliformis mosseae(BGC-NM03D)、Claroideoglomus etunicatum(BGC-NM01B)和Rhizophagus intraradices(BJ09)]对小麦生长、氮吸收及根内4个硝态氮转运蛋白(NRT)基因、1个辅助蛋白(NAR)基因和2个铵态氮转运蛋白(AMT)基因表达的影响。结果表明,3种AM真菌均能够侵染小麦根系,以R.intraradices菌根的侵染率最高;接种R.intraradices或C.etunicatum能够显著提高小麦的生物量或地上部氮吸收量;无论是高氮还是低氮处理,接种AM真菌后均显著下调了小麦根内NRT、NAR和AMT基因的表达水平,且不同AM真菌调控小麦根内氮转运蛋白基因表达的能力具有明显差异。     

拟南芥蔗糖转运蛋白(SUTs)的功能研究进展

蔗糖是光合产物在植物体内贮藏、运输的主要形式.植物蔗糖转运蛋白对蔗糖的装载、运输、卸出与分配过程起着不可替代的作用.本文详细介绍了拟南芥9个蔗糖转运蛋白家族成员的功能、分类、表达定位以及动力学特性等方面的研究进展.