ISSR分子标记在牧草研究中的应用

ISSR（inter-simple sequence repeat）是在SSR标记基础上发展起来的一类新型的分子标记技术。在比较ISSR和其它分子标记的原理和特点的基础上,主要对ISSR标记的原理、特点以及ISSR分子标记在牧草DNA指纹库的构建、遗传多样性、种质资源鉴定、遗传作图和基因定位、分子标记辅助育种等领域的研究进展进行综述,并对其应用前景进行简要概述。     

Normal cellular prion protein is a ligand of selectins: binding requires Le(X) but is inhibited by sLe(X)

The normal PrP(C) (cellular prion protein) contains sLe(X) [sialyl-Le(X) (Lewis X)] and Le(X). sLe(X) is a ligand of selectins. To examine whether PrP(C) is a ligand of selectins, we generated three human PrP(C)-Ig fusion proteins: one with Le(X), one with sLe(X), and the other with neither Le(X) nor sLe(X). Only Le(X)-PrP(C)-Ig binds E-, L- and P-selectins. Binding is Ca(2+)-dependent and occurs with nanomolar affinity. Removal of sialic acid on sLe(X)-PrP(C)-Ig enables the fusion protein to bind all selectins. These findings were confirmed with brain-derived PrP(C). The selectins precipitated PrP(C) in human brain in a Ca(2+)-dependent manner. Treatment of brain homogenates with neuraminidase increased the amounts of PrP(C) precipitated. Therefore the presence of sialic acid prevents the binding of PrP(C) in human brain to selectins. Hence, human brain PrP(C) interacts with selectins in a manner that is distinct from interactions in peripheral tissues. Alternations in these interactions may have pathological consequences.     

Apoptosis of the reduced enamel epithelium and its implications for bone resorption during tooth eruption

Bone remodeling, the selective deposition and resorption of bone, is an important cause of tooth eruption. During tooth eruption, reduced enamel epithelia of the enamel organ interact with follicle cells to recruit osteoclasts for bone remodeling. However, little is known about the relationship between cellular activity of reduced enamel epithelium and bone resorption during tooth eruption. The purpose of this study was to investigate the effect of apoptosis in reduced enamel epithelium on osteoclastogenesis and its implications for bone resorption. We have analyzed erupting mandibular molars in mice by TdT-mediated dUTP-biotin nick end labeling assay, tartrate-resistant acid phosphatase (TRAP) staining, and immunohistochemistry. TRAP-positive cells were detected in the osteoclasts near both the buccal and lingual sides of tooth socket at postnatal day 0 (PN0). They significantly increased until PN3 and decreased thereafter as the tooth erupted. Interestingly, apoptosis was barely detected in the reduced enamel epithelium at PN3 but clearly at PN7. A few apoptotic cells were also investigated within the dental follicle surrounding developing tooth at PN7 and PN10. We observed apoptotic osteoblast-lineage cells along the inner margin of alveolar bone facing the buccal cusp and at the base of the bony crypt at PN3 decreasing until PN10. In contrast, expression levels of bone sialoprotein increased at PN10 compared to levels at PN3. These results suggest that apoptosis of reduced enamel epithelium resulted in a reduction of osteoclast activity and of bone resorption mediated by dental follicle during tooth eruption.     

Incorporation of glycosylphosphatidylinositol-anchored granulocyte- macrophage colony-stimulating factor or CD40 ligand enhances immunogenicity of chimeric simian immunodeficiency virus-like particles

The rapid worldwide spread of human immunodeficiency virus (HIV) mandates the development of successful vaccination strategies. Since live attenuated HIV is not accepted as a vaccine due to safety concerns, virus-like particles (VLPs) offer an attractive safe alternative because they lack the viral genome yet they are perceived by the immune system as a virus particle. We hypothesized that adding immunostimulatory signals to VLPs would enhance their efficacy. To accomplish this we generated chimeric simian immunodeficiency virus (SIV) VLPs containing either glycosylphosphatidylinositol (GPI)-anchored granulocyte-macrophage colony-stimulating factor (GM-CSF) or CD40 ligand (CD40L) and investigated their biological activity and ability to enhance immune responses in vivo. Immunization of mice with chimeric SIV VLPs containing GM-CSF induced SIV Env-specific antibodies as well as neutralizing activity at significantly higher levels than those induced by standard SIV VLPs, SIV VLPs containing CD40L, or standard VLPs mixed with soluble GM-CSF. In addition, mice immunized with chimeric SIV VLPs containing either GM-CSF or CD40L showed significantly increased CD4(+)- and CD8(+)-T-cell responses to SIV Env, compared to standard SIV VLPs. Taken together, these results demonstrate that the incorporation of immunostimulatory molecules enhances humoral and cellular immune responses. We propose that anchoring immunostimulatory molecules into SIV VLPs can be a promising approach to augmenting the efficacy of VLP antigens.     

Mitochondrial reactive oxygen species originating from Romo1 exert an important role in normal cell cycle progression by regulating p27Kip1 expression

Reactive oxygen species (ROS) steady-state levels are required for entry into the S phase of the cell cycle in normal cells, as well as in tumour cells. However, the contribution of mitochondrial ROS to normal cell proliferation has not been well investigated thus far. A previous report showed that Romo1 was responsible for the high ROS levels in tumour cells. Here, we show that endogenous ROS generated by Romo1 are indispensable for cell cycle transition from G1 to S phase in normal WI-38 human lung fibroblasts. The ROS level in these cells was down-regulated by Romo1 knockdown, resulting in cell cycle arrest in the G1 phase. This arrest was associated with an increase in the level of p27^Kip1. These results demonstrate that mitochondrial ROS generated by Romo1 expression is required for normal cell proliferation and it is suggested that Romo1 plays an important role in redox signalling during normal cell proliferation.     

Genetic variants and signatures of selective sweep of Hanwoo population (Korean native cattle)

Although there have been many studies of native Korean cattle, Hanwoo, there have been no selective sweep studies in these animals. This study was performed to characterize genetic variation and identify selective signatures. We sequencedthe genomes of 12 cattle, and identified 15125420 SNPs, 1768114 INDELs, and 3445 CNVs. The SNPs, INDELs, and CNVs were similarly distributed throughout the genome, and highly variable regions were shown to contain the BoLA family and GPR180, which are related to adaptive immunity. We also identified the domestication footprints of the Hanwoo population by searching for selective sweep signatures, which revealed the RCN2 gene related to BPV resistance. The results of this study may contribute to genetic improvement of the Hanwoo population in Korea. [BMB Reports 2013; 46(7):346-351]     

SolVES模型价值转移方法对不同空间尺度的响应评估

随着人类对生态系统服务压力的不断增加,生态系统服务社会价值的评估变得至关重要。利用SolVES模型将太白山国家森林公园的社会价值转移到牛背梁国家森林公园和秦岭山地,评估两者的社会价值并探讨不同尺度下转移结果的差异。结果表明:1)牛背梁国家森林公园游憩价值指数与高程负相关,美学价值指数与高程正相关,羚牛谷山水观光游憩区的游憩价值较高,高山风光区的美学价值较高;2)秦岭山地的游憩价值与高程正相关,美学价值与高程负相关,森林公园的游憩价值较高,山地整体美学价值指数偏低;3)秦岭山地的社会价值集中于高程1000—2000m、坡度25°—35°处,而牛背梁国家森林公园的社会价值分布规律不明显;4)不同尺度下相同的转移模型输出的转移结果与环境变量的关系存在差异。SolVES模型的价值转移子模型是一个可以进行生态系统服务社会价值评估的快速有效的工具,但应根据需求精度选择合适的统计模型。     

肠激酶在毕赤酵母中的分泌表达优化

肠激酶 (Enterokinase,EK) 是一类特异性识别切割DDDDK序列的丝氨酸蛋白酶,作为一种工具酶广泛应用于生物医药领域。目前,EK在毕赤酵母Pichia pastoris中的表达水平较低,难以应用。本研究比较了6种不同的信号肽SP1、SP2、SP3、SP4、SP7和SP8对毕赤酵母分泌表达EK的影响。在摇瓶水平上,与α-factor信号肽相比,SP1信号肽显著提高了EK的分泌表达 (从6.8 mg/L提高至14.3 mg/L),酶活从 (2 390±212) U/mL提高至 (4 995±378) U/mL。在此基础上,通过共表达毕赤酵母内源蛋白Kex2,EK酶活提高至 (7 219±489) U/mL。另外,N端融合WLR三个氨基酸进一步提高酶活至 (15 145±920) U/mL,比酶活为 (1 174 600±53 100) U/mg。EK在毕赤酵母中的高效分泌表达为未来应用奠定了基础。     

Identification of vasopressin-induced genes in AQP2-transfected MDCK cells by suppression subtractive hybridization

Arginine vasopressin (AVP) plays a major role in the modulation of water reabsorption in mammalian kidney. In addition to short-term regulation of aquaporin 2 (AQP2) trafficking, AVP also has long-term effects to regulate the expression of AQP2 in renal collecting duct. However, the detailed mechanism of the long-term effects of AVP in kidney remains to be elucidated. We have searched for genes induced by AVP using the polymerase chain reaction-based suppression subtractive hybridization technique in AVP-responsive AQP2-transfected MDCK cells. We found that the expression of the genes such as VIP17/MAL, annexin II, stimulatory GTP binding protein, tubulin, and mitochondrial ATP synthase was induced by AVP treatment for 4h. These results suggest that AVP might induce the expression of several genes related to the apical targeting of newly synthesized AQP2 as well as that of AQP2 for the long-term modification of water permeability in renal collecting duct.     

Alkaline conditions stimulate the production of 1,3-propanediol in Lactobacillus panis PM1 through shifting metabolic pathways

A novel Lactobacillus panis PM1 isolate was found to be capable of converting glycerol to 1,3-propanediol (1,3-PDO), an increasingly valuable commodity chemical. In this study the effects of various process parameters, including glucose and glycerol concentrations, inoculum size, temperature, aeration, pH, and carbon source were examined to determine the optimal conditions for the production of 1,3-PDO using a culture method simulating late log to early stationary phases. Inoculum size did not influence the production of 1,3-PDO, and temperature variance showed similar 1,3-PDO production between 25 and 37 °C under the examined conditions. Glycerol concentration and pH played a primary role in the final concentration of 1,3-PDO. The highest production occurred at 150–250 mM glycerol when 50 mM glucose was available. Alkaline initial conditions (pH 9–10) stimulated the production of 1,3-PDO which concurrently occurred with increased acetic acid production. Under these conditions, 213.6 mM of 1,3-PDO were produced from 300 mM glycerol (conversion efficiency was 71 %). These observations indicated that the production of 1,3-PDO was associated with the shift of the metabolic end-product ethanol to acetic acid, and that this shift resulted in an excess concentration of NADH available for the processing of glycerol to 1,3-PDO.