Development and maturation of surghum seeds on detached panicles grown in vitro

Summary A procedure for culturing detached panicles of sorghum, Sorghum bicolor (L.) Moench, was developed to achieve flowering, fertilization, and subsequent seed development and maturation in vitro. Sixteen sorghum genotypes (five high and eleven low in tannin) were tested for their ability to develop normally in culture. Panicles collected one to two days before the initiation of anthesis were cultured in flasks containing liquid medium. Contamination and medium darkening were the major obstacles encountered. Up to 55% of the panicles cultured reached physiological maturity in vitro. The frequency of seed set ranged from 30 to 97% depending upon genotype and medium. Seed and glume color were normal. Seed produced in vitro resembled those grown in vivo and germinated well, but were smaller than normal (100 kernel weight reached 50 to 70% of the control). Grain polyphenols were synthesized in the cultured panicles. Seed of high tannin genotypes produced in vitro were lower in total phenols and tannins and higher in flavan-4-ols and the 3-deoxyanthocyanidin pigments than control seed. This technique can be used for harvesting late-maturing stocks and for various sorghum studies.     

腺苷及其类似物对猪血小板肌动蛋白聚合的抑制作用及可能机理

凝血酶和ADP刺激血小板肌动蛋白的聚合,腺苷、5′-氯-5′-脱氧腺苷及2′-脱氧腺苷抑制凝血酶和(或)ADP诱导的肌动蛋白聚合;腺苷和5′-氯-5′-脱氧腺苷对磷脂酰肌醇的磷酸化有抑制作用,且呈剂量效应关系;腺苷对凝血酶刺激的血小板中肌醇二磷酸的生成有抑制作用。本实验提示腺苷及其类似物对肌动蛋白聚合的抑制作用可能与它们对肌醇磷脂转换的抑制有关。     

NSA－Ⅱ型生理信号处理系统

介绍一种ＩＢＭ－ＰＣ系列微机生理信号采集、处理系统。该系统信号采集卡集程控放大、脉冲甄别、Ａ／Ｄ、Ｄ／Ａ等电路于一体,可满足各种生理信号的采集需要。采集信号时可长时间显示,动态观察。采样后,按需要给出各种图表与结果。部分处理方法采用独特数学模型,使结果更加精确。     

尼群地平对实验性糖尿病大鼠心肌收缩性的影响

腹腔注射链脲佐霉素（６５ｍｇ／ｋｇ）诱发Ｗｉｓｔａｒ大鼠糖尿病。糖尿病发病４周后,向饲料中加尼群地平（３０ｍｇ·ｋｇ－１·ｄ－１）。结果表明,糖尿病４周时大鼠心室舒张功能首先受损,８周后心室舒张和收缩功能均明显受累。尼群地平处理对糖尿病大鼠的心肌收缩性有一定的改善作用。提示尼群地平对大鼠糖尿病性心肌病有一定有益作用。     

缢蛏碱性磷酸酶胍溶液中分子折叠与活力变化研究

报道了缢蛏碱性磷酸酶（简称ＡＬＰ）经不同浓度盐酸胍处理时酶的分子构象所发生的变化以及酶变化和失活的动力学过程。在胍中酶荧光发射峰强度下降,紫外差光谱在２４６ｎｍ和２８５ｎｍ处出现２个负峰,ＣＤ谱中酶的α螺旋度下降,且随浓度增大,变化程度也加大。动力学研究表明,酶在０．５ｍｏｌ／Ｌ、１．０ｍｏｌ／Ｌ、２．０ｍｏｌ／Ｌ３．０ｍｏｌ／Ｌ、４．０ｍｏｌ／Ｌ盐酸胍中的变性速度常数分别为３．２１×１０~（－４）ｓ~（－１）、６．３８×１０~（－４）ｓ~（－１）、２．１７×１０~（－３）ｓ~（－１）、２．３３×１０~（－３）ｓ~９－１）、５．１７×１０~（－３）ｓ~（－１）;而酶在相应盐酸胍中的失活速度常数分别为２．３３×１０~（－４）ｓ~（－１）、３．５７×１０~（－４）ｓ~（－１）、５．８６×１０~（－４）ｓ~（－１）、１．１４×１０~（－３）ｓ~（－１）、３．４５×１０~（－３）ｓ~（－１）;表现为失活与构象伸展变化基本平行。     

Increase in cytoskeletal actin induced by inositol 1,4-bisphosphate in saponin-permeated pig platelets

Inositol 1,4-bisphosphate (IP₂), which rapidly accumulates during cell activation, strongly stimulates an increase in cytoskeletal actin in saponin-permeated platelets, and the effect is insensitive to 5′-Chloro-5′-deoxyadenosine. Within 10 s, the amount of cytoskeletal actin in platelets rapidly increases by 41%, and then slowly increases further. IP₂ induces the increase in cytoskeletal actin in a dose-dependent manner. The half-maximal effect requires approximately 2 μM of IP₂ Inositol 1,4,5- triphosphate, the messenger for Ca²⁺ release, causes the increase in cytoskeletal actin, but is less effective than IP₂. Inositol 1-monophosphate and inositol 2-monophosphate have no effect on cytoskeletal actin. Phorbol 12-myristate 13-acetate, which has been shown to activate IP₃ 5′-phosphatase through protein kinase C, stimulates the increase in cytoskeletal actin. Spermine, an inhibitor of IP₃ 5′-phosphatase, inhibits the thrombin stimulated increase in cytoskeletal actin. These results suggest that IP₂ may be a messenger that controls the organization of actin filaments during cell activation. This study presents the first evidence for IP₂ as a messenger during cell activation.     

Localization of neuropeptide Y and atrial natriuretic peptide in the endothelial cells of human umibilical blood vessels

The localization of neuropeptide Y (NPY) and atrial natriuretic peptide (ANP) in the endothelial cells of human umbilical blood vessels was studied using the pre-embedding peroxidase-antiperoxidase (PAP) technique for electron microscopy and avidin-biotin-complex (ABC) immunostaining for endothelial cells cultured from umbilical vein. Subpopulations of NPY- and ANP-immunoreactive endothelial cells were present in term umbilical vein and artery. The umbilical vein contained more positive cells than the artery. The percentage of NPY- and ANP-immunoreactive umbilical vein cells in culture was 32% and 44%, respectively, out of a total of 3013 cells examined. The possibility that these potent vasoactive substances located in the endothelial cells of the non-innervated umbilical vessels are involved in the local regulation of blood flow is discussed.     

恒河猴、懒猴和树鼩的短时空间记忆功能与前额叶背侧部进化水平的相关性(英文)

本文研究探讨了进化地位不同的三种动物的短时空间记忆功能及其与前额叶背侧部进化水平的相关性。结果表明,在延缓反应作业中,经1000次训练后,7只恒河猴对空间位置的记忆时间平均为7.7±3.2min,懒猴为3.8±0.44min,而树鼩即使在延缓时间几乎为零秒的延缓反应中,其正确反应率也未达到90％标准。一种延缓时间仅测试一个单元,即不经训练的实验表明,恒河猴在延缓期为“0”—5min的各测试单元中,正确反应率稳定在80％以上;懒猴在延缓时间为“0”—4min的各测试单元中,平均正确反应率与恒河猴无明显差异,而当延缓时间增加到5min时,在延缓反应作业中取得的成绩显著下降;树鼩在延缓时间为1—5min的作业中取得的正确反应率在70％以下。3种动物在视觉辨别学习作业中却无明显差异。形态学研究表明,灵长类大脑前额叶的面积和结构的复杂性在进化过程中逐渐增大,如恒河猴大脑前额叶的表面积占大脑半球表面积的11.5％(Brodmann,1929),其内颗粒层发达,背侧部明显凸起,主沟区发达;懒猴的前额叶表面积占其大脑半球表面积的8.3％,背侧部凸起不显著,主沟未形成,额极内颗粒层分化明显,背侧部的内颗粒层较内侧部的发达程度差(Sanides,1967);树鼩的前额叶表面积占7.5％,额极的内颗粒层分化不明显,为非颗粒化区,此区之后为颗粒区     

Hydrolysis of phosphatidylcholine couples Ras to activation of Raf protein kinase during mitogenic signal transduction.

We have investigated the relationship between hydrolysis of phosphatidylcholine (PC) and activation of the Raf-1 protein kinase in Ras-mediated transduction of mitogenic signals. As previously reported, cotransfection of a PC-specific phospholipase C (PC-PLC) expression plasmid bypassed the block to cell proliferation resulting from expression of the dominant inhibitory mutant Ras N-17. In contrast, PC-PLC failed to bypass the inhibitory effect of dominant negative Raf mutants, suggesting that PC-PLC functions downstream of Ras but upstream of Raf. Consistent with this hypothesis, treatment of quiescent cells with exogenous PC-PLC induced Raf activation, even when normal Ras function was blocked by Ras N-17 expression. Further, activation of Raf in response to mitogenic growth factors was blocked by inhibition of endogenous PC-PLC. Taken together, these results indicate that hydrolysis of PC mediates Raf activation in response to mitogenic growth factors.