凹叶厚朴茎段愈伤组织诱导中的褐变控制研究

目的研究愈伤组织诱导过程中的褐变问题。方法:将采集的标本进行外植体灭菌法再接种到培养基,在培养基中加抗褐变剂,进行防褐变试验。结果外植体在4℃冰箱冷藏48 h的预处理对褐变有较好的控制效果。在培养基中加入抗褐变剂比加入吸附剂抗褐变效果好,抗褐变剂中Vc的效果最佳,吸附剂PVP比活性炭好。结论培养条件,以低温遮光处理效果较好,光、温两个因素中,凹叶厚朴对光敏感,遮光能有效抑制褐变。液体浅层静置培养10 d后转入固体培养抗褐变的效果比单纯的固体培养效果好。     

低氧对体外培养绒毛组织瘦素及其受体表达的实验研究

【目的】探讨低氧对体外培养的绒毛组织瘦素及其可溶性受体表达的影响。【方法】孕早期的绒毛组织分两组培养:常氧对照组和缺氧组。应用RT-PCR方法检测肥胖基因和瘦素受体基因mRNA表达水平,应用酶联免疫吸附ELISA法检测培养液中瘦素和可溶性瘦素受体水平。【结果】与常氧组相比,缺氧组绒毛组织的肥胖基因mRNA表达水平增加,瘦素受体基因mRNA表达水平下降;缺氧组绒毛组织产生的瘦素增加,可溶性瘦素受体减少。【结论】缺氧可以诱导绒毛组织肥胖基因表达,下调瘦素受体基因表达。缺氧可能是子痫前期胎盘组织瘦素高表达的原因。     

Volumetric interpolated contrast-enhanced MRA for the diagnosis of pulmonary embolism in an ex vivo system

PURPOSE: To implement a three-dimensional gradient-recalled echo (GRE) volumetric interpolated breath-hold examination (VIBE) sequence for pulmonary contrast-enhanced MRA (CE-MRA) in an experimental setup. MATERIALS AND METHODS: Eight porcine lungs were intubated, inflated inside a chest phantom, and examined at 1.5 T during slow perfusion (2-300 mL/minute). Three-dimensional-MRA was performed with and without contrast agent using three-dimensional-GRE (VIBE) with TR/TE = 4.5/1.9 msec, TA = 23 seconds, FOV = 390 mm, FA = 12 degrees /30 degrees, as well as a standard three-dimensional-GRE sequence and T2 fast spin-echo (FSE) sequences. Four of the eight lungs were embolized with autologous blood clots. By consensus readings, two observers evaluated the detectability of peripheral vessels, signal intensity over vessels and lung, and visualization of emboli. Digital subtraction angiograms served as a control to document vessel patency. RESULTS: Prior to contrast administration, three-dimensional-VIBE/12 degrees yielded the best results for lung parenchyma signal and visualization of small vessels (third-order, P < 0.01); however, no emboli were detected (due to lack of contrast). After administration of contrast agent, three-dimensional-GRE (VIBE) at FA = 30 degrees provided significantly better results (fifth-order branches, documentation of subsegmental occlusions [fourth order], P < 0.01). T2-FSE images documented water uptake into the lungs. Digitally subtracted angiography (DSA) confirmed the patency of seventh-order branches. CONCLUSION: This ex vivo study confirms the potential advantages of using a dual MR investigation for pulmonary embolism, combining three-dimensional-GRE (VIBE) at FA = 12 degrees to image lung parenchyma and at FA = 30 degrees for CE-MRA..     

The effects of ciliary neurotrophic factor on the hypothalamo-pituitary gonadal axis in vitro in female rats

Ciliary neurotrophic factor (CNTF) is a member of the neuropoietic family of cytokines. CNTF exerts its actions through activation of a receptor complex, which shows similarity of sequence, second messenger systems and distribution to the leptin receptor. Leptin has been demonstrated to exert profound effects on the hypothalamo-pituitary gonadal axis. This study examines the in vitro effects of CNTF on hypothalamic luteinizing hormone releasing hormone release (LHRH) and pituitary luteinizing hormone (LH) release compared to those of leptin in the female. We report that CNTF stimulates LHRH release from medial basal hypothalamic explants harvested from proestrous female rats and this effect is of similar magnitude to that seen with leptin. In contrast, CNTF suppresses LHRH-stimulated LH release from dispersed anterior pituitary cells harvested from proestrous female rats but has no effect on basal LH release. Leptin stimulates basal LH release but has no effect on LHRH-stimulated LH release. The suppressive effect of CNTF on LHRH-stimulated LH release has been confirmed in perifused anterior hemipituitaries. These results suggest a differential effect of CNTF on the hypothalamo-pituitary gonadal axis and a possible role in the modulation of pituitary gonadal function.     

Alpha-dystroglycan interactions affect cerebellar granule neuron migration

The interaction of alpha-dystroglycan (a-DG) with its extracellular binding partners requires glycans attached to its mucin core domain, and defects in the glycosylation of a-DG are associated with both muscular dystrophy and neuronal migration defects. The involvement of a-DG and one of its ligands, agrin, in cerebellar neuronal migration was investigated. Antibodies directed against glycosylated a-DG inhibited granule neuron migration in cerebellar slice cultures. a-DG interactions did not appear to influence neurite outgrowth in cerebellar explant cultures, but enhanced granule neuron binding was observed on cells transfected with a-DG. These results suggest that interactions involving a-DG influence the strength of attachment of granule neurons to the a-DG-expressing Bergmann glial cells that guide granule neuron migration in the cerebellum. Experiments using anti-agrin antibodies suggest that agrin is not involved in these interactions.     

Substrate properties of zebrafish Rtn4b/Nogo and axon regeneration in the zebrafish optic nerve

This study explored why lesioned retinal ganglion cell (RGC) axons regenerate successfully in the zebrafish optic nerve despite the presence of Rtn4b, the homologue of the rat neurite growth inhibitor RTN4‐A/Nogo‐A. Rat Nogo‐A and zebrafish Rtn4b possess characteristic motifs (M1‐4) in the Nogo‐A‐specific region, which contains delta20, the most inhibitory region of rat Nogo‐A. To determine whether zebrafish M1‐4 is inhibitory as rat M1‐4 and Nogo‐A delta20, proteins were recombinantly expressed and used as substrates for zebrafish single cell RGCs, mouse hippocampal neurons and goldfish, zebrafish and chick retinal explants. When offered as homogenous substrates, neurites of hippocampal neurons and of zebrafish single cell RGCs were inhibited by zebrafish M1‐4, rat M1‐4, and Nogo‐A delta20. Neurite length increased when zebrafish single cell RGCs were treated with receptor‐type‐specific antagonists and, respectively, with morpholinos (MO) against S1PR2 and S1PR5a—which represent candidate zebrafish Nogo‐A receptors. In a stripe assay, however, where M1‐4 lanes alternate with polylysine‐(Plys)‐only lanes, RGC axons from goldfish, zebrafish, and chick retinal explants avoided rat M1‐4 but freely crossed zebrafish M1‐4 lanes—suggesting that zebrafish M1‐4 is growth permissive and less inhibitory than rat M1‐4. Moreover, immunostainings and dot blots of optic nerve and myelin showed that expression of Rtn4b is very low in tissue and myelin at 3–5 days after lesion when axons regenerate. Thus, Rtn4b seems to represent no major obstacle for axon regeneration in vivo because it is less inhibitory for RGC axons from retina explants, and because of its low abundance.     

Effect of cytokinins on in vitro multiplication of Sophora tonkinensis

Objective

To determine the effects of different cytokinins at various concentrations on in vitro shoot multiplication of an important medicinal plant.

Methods

Nodal explants (1.5-2.0 cm) of Sophora tonkinensis were used. Multiple shoots were induced from nodal explants cultured on the Murashige and Skoog (MS) medium supplemented with 0.0, 0.5, 1.0, 2.0, 4.0, 8.0, or 16.0 µmol 2-isopentyladenine (2iP), N6 benzyladenine, kinetin or thiadiazuron.

Results

Among the four investigated cytokinins, 2iP showed the best response for shoot multiplication. Maximum shoot induction (75%) was achieved on the MS medium supplemented with 2.0 µmol 2iP, with a mean number of 5.0 shoots per explant. In comparison to other cytokinins tried, 2iP showed the highest shoot elongation with a mean shoot length of 4.8 cm. Root initiation was observed within 15 d within the transfer of shoots onto the MS basal medium, and the rooting percentage was 100% with a mean number of 5.4 roots per shoot and root length of 6.2 cm over a period of 4 weeks. The healthy plants, hardened and transferred to a greenhouse for proper acclimatization, exhibited 100% survival.

Conclusions

It can be summarized that 2iP is the optimal plant growth regulator for Sophora multiplication.     

胡萝卜直根诱导愈伤组织实验研究

目的：探讨胡萝卜直根诱导愈伤组织的最佳条件.方法：以新鲜胡萝卜直根为外植体,将直根皮层、形成层及中轴3个部位分别置于MS（培养基）＋2,4-D（2,4-二氯苯氧乙酸）＋6-BA（6-苄基腺嘌呤）与MS＋NAA（α-萘乙酸）＋6-BA两类培养基中,观察3种外植体愈伤组织的生长情况及诱导率.结果：直根皮层外植体在这两类培养基中均未长出愈伤组织,即愈伤组织诱导率为0;直根形成层及中轴外植体在这两类培养基中均长出愈伤组织,即愈伤组织诱导率为100％,其中在MS＋ NAA＋ 6-BA培养基中愈伤组织质地疏松、颜色浅黄鲜亮、生长旺盛、增殖快速,在MS＋2,4-D＋ 6-BA培养基中愈伤组织质地紧密、颜色深黄、增殖缓慢.结论：诱导疏松型胡萝卜愈伤组织的最佳外植体是胡萝卜直根形成层及中轴,最佳培养基类型是MS＋ NAA＋ 6-BA.     

Effects of patulin and ascladiol on porcine intestinal mucosa: An ex vivo approach

Patulin (PAT) is a secondary metabolite mainly produced by Aspergillus and Penicillium that is frequently found contaminating apples and rotten fruits. Patulin can be transformed in potencially less toxic compounds such as ascladiol (ASC). Toxic effects of patulin were described in rats and in in vitro models, however concerning ascladiol, data are restricted to metabolic pathways. The aim of the present study was to evaluate the effects of different concentrations of PAT (10 μM, 30 μM, 100 μM) and ASC (30 μM, 100 μM) on intestinal tissue using the jejunal explant model. Explants from pigs were exposed for 4 h to PAT and ASC and after this period were processed for histological, morphometrical and immunohistochemical analysis. Mild histological changes were observed in jejunal explants exposed to PAT and ASC, however no significant difference in the lesional score or villi height was observed between the PAT/ASC-groups and the control. Also, explants exposed to 100 μM of PAT showed a significant decrease in goblet cells density and a significant increase in cell apoptosis. These results indicate that high levels of patulin can induce mild toxic effects on intestinal mucosa whereas ascladiol apparently is non-toxic to intestinal tissue.     

Quality of placental RNA: Effects of explant size and culture duration

We evaluated the impact of placental micro (≤50 mg) and macro (∼200 mg) explants, oxygen concentration and culture method on placental RNA quality after long-term culture. Our findings show that micro explants cultured at 8% oxygen have the best RNA quality and tissue structure. Macro explants were less viable after long-term culture. Macro explants and explants undergoing syncytial degeneration produced poor quality RNA and should be avoided.