荞麦、高粱根系分泌物对玉米根边缘细胞和根生长的影响

植物的根系分泌物是植物根系与周围环境之间的化学媒介,通过传递特定的信息,调节根际微环境,影响周围植物的生长。玉米(Zea mays L.)和荞麦(Fagopyrum esculentum Moench)是农作物间套作体系中典型的不能搭配的组合,其障碍因素尚不清楚。以玉米为受体植物,采用根悬空培养的方法,研究了荞麦、高粱(Sorghum bicolor(L.) Moench)根系分泌物对玉米根边缘细胞和根生长的影响。结果发现,玉米根边缘细胞离体培养条件下,用荞麦根系分泌物中的小分子物质处理4、8 h显著诱导边缘细胞凋亡、死亡,细胞活率分别比对照降低了71.6%和72.3%;荞麦根系分泌物中的小分子物质对玉米根产生氧化胁迫,诱导根SOD、POD和CAT活性分别比对照高22.6%、33.9%和107.2%,根中超氧阴离子(O₂^-·)和脯氨酸含量分别比对照高33.9%和49.8%;荞麦根系分泌物中小分子物质的胁迫使根细胞膜透性增大,与对照相比升高80.0%,丙二醛(MDA)含量比对照升高31.5%;荞麦根系分泌物中小分子物质诱导根内源激素(IAA)含...     

Alterations in osteoclast morphology following osteoprotegerin administration in the magnesium-deficient mouse

In the present study, we used osteoprotegerin (OPG), which blocks osteoclastogenesis, to correct and thus explain the hypercalcemia that is seen during dietary Mg deficiency in the mouse. Control and Mg-deficient mice received injections for 12 days of either OPG or vehicle only. Serum Ca was similar in Mg-deficient mice treated with OPG and in control mice receiving OPG (9.2±0.3 mg/dl vs. 9.2±0.5). Both groups had significantly higher serum Ca than controls or Mg-deficient animals receiving vehicle alone. Surprisingly, Mg-depleted mice that received OPG in doses that inhibit osteoclastic bone resorption remained hypercalcemic. Because mature osteoclasts still present in the marrow might be hyperactive, we examined osteoclast morphology at the light microscopic and ultrastructural level. Light microscopic examination of trabecular bone showed few osteoclasts in OPG-treated mice. Ultrastructural examination revealed that osteoclasts in OPG-treated mice have decreased contact with the endosteal bone surface and absence of a ruffled border. Because the morphology of the existing pool of mature osteoclasts did not enhance resorption, another mechanism, such as increased intestinal absorption of Ca in Mg-deficient mice, likely contributes to the hypercalcemia observed during Mg deficiency.     

Fate map and morphogenesis of presumptive neural crest and dorsal neural tube

In contrast to the classical assumption that neural crest cells are induced in chick as the neural folds elevate, recent data suggest that they are already specified during gastrulation. This prompted us to map the origin of the neural crest and dorsal neural tube in the early avian embryo. Using a combination of focal dye injections and time-lapse imaging, we find that neural crest and dorsal neural tube precursors are present in a broad, crescent-shaped region of the gastrula. Surprisingly, static fate maps together with dynamic confocal imaging reveal that the neural plate border is considerably broader and extends more caudally than expected. Interestingly, we find that the position of the presumptive neural crest broadly correlates with the BMP4 expression domain from gastrula to neurula stages. Some degree of rostrocaudal patterning, albeit incomplete, is already evident in the gastrula. Time-lapse imaging studies show that the neural crest and dorsal neural tube precursors undergo choreographed movements that follow a spatiotemporal progression and include convergence and extension, reorientation, cell intermixing, and motility deep within the embryo. Through these rearrangement and reorganization movements, the neural crest and dorsal neural tube precursors become regionally segregated, coming to occupy predictable rostrocaudal positions along the embryonic axis. This regionalization occurs progressively and appears to be complete in the neurula by stage 7 at levels rostral to Hensen's node.     

The effect of right terminal repeat deletion on the oncogenicity of the T-Region of pTiT37

Summary A modified pTiT37 plasmid was constructed by deleting a 103 base fragment between an AhaIII and a Bc/I site. This fragment, located to the right of the nopaline synthase gene contains the right terminal 25 base pair repeat sequence which defines the right limit of the T-Region. The effect of this deletion was determined on a number of host plants. In contrast to previous reports, the deletion does not destroy tumorigenicity on all plant species. It had no effect on tumorigenicity when Linum usitatissimum was used as the test species and an attenuating effect when Kalanchoë tubiflora was used. Only when Nicotiana tabacum was used did the mutant appear avirulent. We propose from these data and the phenotype of those tumours that form, that a pseudo border located in the 3 untranslated region of the ipt locus has been used to provide the right hand limit of the T-Region in the absence of the normal border.     

Stimulation of intestinal Na+/d-glucose cotransport by monoclonal antibodies

Summary The small intestinal brush border membrane is endowed with a number of transport systems. Monoclonal antibodies were produced against integral membrane proteins and tested for their ability to bind to such membranes. For this purpose papain-digested, deoxycholate-extracted BBMVs from rabbit small intestine were used to immunize mice. Of the 765 hybridoma supernatants tested, 119 gave a significantly higher extent of binding to the crude antigen preparation as compared with the background. The monoclonal antibodies were also tested for their ability to influence the sodium-dependent uptake of solutes into intact BBMVs. Two monoclonal antibodies clearly showed stimulation of secondary actived-glucose transport, whereas sodium-dependent uptake ofl-alanine andl-proline was not affected. Hydrophobically labeled, i.e. intrinsic, membrane proteins of 175, 78 and 65 kilodaltons could be immunoprecipitated by both monoclonal antibodies, the 78 kDa band corresponding in all likelihood to the Na⁺/glucose cotransporter.     

Ca2+-activated K+ channels in the apical membrane ofNecturus choroid plexus

Summary The properties of Ca²⁺-activated K⁺ channels in the apical membrane of theNecturus choroid plexus were studied using single-channel recording techniques in the cell-attached and excised-patch configurations. Channels with large unitary conductances clustered around 150 and 220 pS were most commonly observed. These channels exhibited a high selectivity for K⁺ over Na⁺ and K⁺ over Cs⁺. They were blocked by high cytoplasmic Na⁺ concentrations (110mm). Channel activity increased with depolarizing membrane potentials, and with increasing cytoplasmic Ca²⁺ concentrations. Increasing Ca²⁺ from 5 to 500nm, increased open probability by an order of magnitude, without changing single-channel conductance. Open probability increased up to 10-fold with a 20-mV depolarization when Ca²⁺ was 500nm. Lowering intracellular pH one unit, decreased open probability by more than two orders of magnitude, but pH did not affect single-channel conductance. Cytoplasmic Ba²⁺ reduced both channel-open probability and conductance. The sites for the action of Ba²⁺ are located at a distance more than halfway through the applied electric field from the inside of the membrane. Values of 0.013 and 117mm were calculated as the apparent Ba²⁺ dissociation constants (K _d (0 mV) for the effects on probability and conductance, respectively. TEA⁺ (tetraethylammonium) reduced single-channel current. Applied to the cytoplasmic side, it acted on a site 20% of the distance through the membrane, with aK _d (0 mV)=5.6mm. A second site, with a higher affinity,K _d (0 mV)=0.23mm, may account for the near total block of chanel conductance by 2mm TEA⁺ applied to the outside of the membrane. It is concluded that the channels inNecturus choroid plexus exhibit many of the properties of maxi Ca²⁺-activated K⁺ channels found in other tissues.     

超声心动图检查对慢性肺源性心脏病患者右心功能的诊断价值

目的:探讨超声心动图检查对慢性肺源性心脏病患者右心功能的诊断价值。方法:选取2016年8月至2017年12月间本院收治的35例慢性肺源性心脏病患者作为实验组,并选择同期健康体检者35例作为对照组,全部受试者均给予超声心动图检查。分别比较两组右房横径(RA)、右室前后径(RV)、肺动脉平均压(MPAP)、射血分数(EF)、舒张晚期A波峰值流速与舒张早期E波峰值流速的比值(A/E)和右心室Tei指数。同时比较实验组采用常规12导联心电图检查及超声心动图检查的诊断阳性率、右心扩大阳性率和右心扩大伴心衰阳性率。结果:与对照组相比,实验组RA、RV以及MPAP均升高,组间比较差异有统计学意义(P0.05)。与对照组相比,实验组EF明显降低,而A/E值、Tei指数明显升高,组间比较差异有统计学意义(P0.05)。实验组超声心动图检查的诊断阳性率、右心扩大阳性率和右心扩大伴心衰阳性率均高于常规12导联心电图检查(P0.05)。结论:应用超声心动图检查能够有效诊断慢性肺源性心脏病患者的右心功能,而且操作简单方便,诊断阳性率较高。