Real Time Measures of Prestin Charge and Fluorescence during Plasma Membrane Trafficking Reveal Sub-Tetrameric Activity

Prestin (SLC26a5) is the outer hair cell integral membrane motor protein that drives cochlear amplification, and has been described as an obligate tetramer. We studied in real time the delivery of YFP-prestin to the plasma membrane of cells from a tetracycline-inducible cell line. Following the release of temperature block to reinstate trans Golgi network delivery of the integral membrane protein, we measured nonlinear capacitance (NLC) and membrane fluorescence during voltage clamp. Prestin was delivered exponentially to the plasma membrane with a time constant of less than 10 minutes, with both electrical and fluorescence methods showing high temporal correlation. However, based on disparity between estimates of prestin density derived from either fluorescence or NLC, we conclude that sub-tetrameric forms of prestin contribute to our electrical and fluorescence measures. Thus, in agreement with previous observations we find that functional prestin is not an obligate tetramer.     

Cardiac glycosides stimulate phospholipase C activity in rat pinealocytes

Ouabain and related cardiac glycosides stimulate phospholipase C activity 5-fold in rat pinealocytes. The combined treatment of ouabain and norepinephrine, which also stimulates phospholipase C, produces an additive effect. The effects of either ouabain or norepinephrine are blocked by EGTA. However, there are notable differences. The stimulatory effect of ouabain is lost when extracellular Na+ is reduced to 20 mM and is not blocked by prazosin. In contrast, the stimulatory effect of norepinephrine is not blocked when extracellular Na+ is reduced to 20 mM but is blocked by prazosin. Ouabain appears to increase phospholipase C activity through a mechanism involving inhibition of Na+,K+-ATPase, and an accumulation of intracellular Na+ and Ca2+, not involving alpha 1-adrenoceptors. These findings raise the possibility that activation of phospholipase C might be a more general effect of cardiac glycosides.     

主养青鱼池塘生态系统能量转换率的研究

1985—1987年对苏州市郊区主养青鱼池塘生态系统的能量转换率进行了分析。结果表明,主养青鱼净产7.5、11.25、15t/ha 3个产量级型池塘青鲤团头鲂产出能占养鱼总产出能的比例分别为82.49、78.03、79.34％;总投入能(太阳辐射能+辅助能)转移到鱼的总产出能转换率分别为0.19、0.24、0.31％;太阳辐射能转移到毛和净初级生产力的能量转换率分别为0.76、0.90、0.96％和0.61、0.72、0.77％;净初级生产力转移到滤食性鱼净产量的能量转换率分别为4.02、4.63、5.27％;辅助能转移到鱼净产量的能量转换率分别为12.20、11.33。11.74％。在3个产量级型池塘中,以15t/ha产量级的能量转换率为最佳型。     

皖南、赣北奥陶纪笔石立体标本形成环境的初步研究*

皖南、赣东北和赣西北地区奥陶纪笔石地层发育良好,笔石化石丰富。宁国组和胡乐组均为笔石相地层,但笔石的保存特点并不相同。立体保存的黄铁矿化笔石标本主要见于宁国组,而胡乐组的笔石几乎均为薄膜标本。在比较宁国组和胡乐组在岩性、颜色、化石、矿物和元素等方面的特点后发现,两者有较明显的差异。这表明宁国组和胡乐组形成时的环境是不同的,前者为弱还原环境,后者为较强的还原环境,而在研究区内影响笔石体立体保存的主要因素为还原环境和较高的铁含量。在还原环境下,铁可呈Fe~(2+)存在,笔石体内含有硫,死亡后经降解作用可生成H_2S;H_2S和Fe~(2+)结合可使笔石体黄铁矿化,从而使笔石体硬化而呈立体保存下来。宁国组的铁含量明显高于胡乐组,这似可以解释宁国组产有较多笔石立体标本的原因。     

猪精子凝集素的纯化,性质及其作用

用胎球蛋白－Ｓｅｐｈａｒｏｓｅ亲和层析和凝胶过滤层析从精子和精浆中分离纯化了猪精子凝集素（简称ＢＳＬ）。ＢＳＬ的血凝活性只被若干糖蛋白和聚糖所抑制。ＢＳＬ的分子量为５６ｋｄ,由分子量分别为１３．６ｋｄ（β）和１６．０ｋｄ（α）的两个不同的亚基以α１β３所组成。ＢＳＬ为糖蛋白,含中性糖３．２％,不含唾液酸。用ＥＬＩＳＡ法测定猪精子中ＢＳＬ的含量及分布,表明７０％嵌入在精子膜中,２５％结合在精子表面,     

南京紫金山现代植被表土孢粉的初步研究

 选择南京紫金山现代植被进行植被调查和表土孢粉分析。结合中国东部不同气候带下的几个地点表土孢粉分析,把孢粉百分含量、孢粉组合及孢粉优势种、标志种与植被的各项参数进行对比,找出植被与孢粉之间的关系。为恢复古植被、古生态和古气候提供科学依据。     

Conformation and activity ofPhaseolus coccineus var. rubronanus lectin

The conformation of native and denaturedPhaseolus coccineus var. rubronanus lectin was studied by circular dichroism (CD) and correlated to the hemagglutinating activity. The far-UV CD spectrum at 25°C showed a broad, negative band around 223 nm and a positive one at 196 nm. CD data analysis of the lectin indicated a -sheet-rich protein. At high temperatures, the spectrum was blue-shifted with increasing magnitude; these changes correlated well with the loss of the activity. The conformation of lectin betweenpH 2 and 10 remained essentially unchanged. AtpH 13 the CD spectrum resembled that of unordered form with a negative band near 200 nm and the activity was completely lost. The denatured lectin in 6 M guanidine hydrochloride would be renatured upon diluting the denaturant to 0.75 M; the changes in CD spectrum again correlated well with the loss of the activity. The effect of sodium dodecyl sulfate on the lectin was drastic; it sharply increased thea-helix at the expense of the -sheet and reduced the activity; the changes reached a plateau above 20 mM surfactant.     

声学指数在城市森林鸟类多样性评估中的应用

鸣声是鸟类之间进行沟通和传递信息的重要方式,这为通过声学监测评估鸟类多样性提供了独特的机会。利用声学指数快速评估生物多样性是一种新兴的调查方法,但城市森林中的复杂声环境可能会导致声学指数的指示结果出现偏差。为了解声学指数在城市森林中应用的可行性,本研究在北京市东郊森林公园设置了50个矩阵式调查样点,于2021年4–6月每月进行1次鸟类传统观测和同步鸣声采集,通过比较两种方法的结果来探究声学监测的有效性。采用Spearman相关分析和广义线性混合模型评估6个常用声学指数与鸟类丰富度和多度的关系,并衡量了每个指数的性能。结果表明:(1)本研究共记录到鸟类10目23科35种,通过声学监听识别的总物种数与传统鸟类观测相等,但具体鸟种存在差异;(2)不同月份间声学指数与鸟类丰富度和多度的相关性有明显差别,声学复杂度指数(ACI)和标准化声景差异指数(NDSI)优于其他指数,是评估鸟类多样性的关键变量;(3)声学指数对鸟类多度的预测能力(R²m=0.32,R2c=0.80)要高于丰富度(R²m=0.12,R2c=0.18)。声学指数为快速评估生物多样性提...     

High-resolution mapping of the S and Z loci of Phalaris coerulescens.

Self incompatibility (SI) in Phalaris coerulescens is gametophytically determined by two unlinked multi allelic loci (S and Z). Neither the S nor Z genes have yet been cloned. As part of a map-based cloning strategy, high-resolution maps of the S and Z regions were generated from distorted segregating populations using RFLP probes from wheat, barley, oat, and Phalaris. The S locus was delimited to 0.26 cM with two boundary markers (Xwg811 and Xpsr168) and cosegregated with Xbm2 and Xbcd762. Xbcd266 was the closest marker linked to Z (0.9 cM). A high level of colinearity in the S and Z regions was found in both self-incompatible and -compatible species. The S locus was localized to the subcentromere region of chromosome 1 and the Z locus to the long arm end of chromosome 2. Several rice BAC clones orthologous to the S and Z locus regions were identified. This opens the possibility of using the rice genome sequence data to generate more closely linked markers and identify SI candidate genes. These results add further support to the conservation of gene order in the S and Z regions of the grass genomes.