Machado-Joseph Disease in Pedigrees of Azorean descent is Linked to Chromosome 14

A locus for Machado-Joseph disease (MJD) has recently been mapped to a 30-cM region of chromosome 14q in five pedigrees of Japanese descent. MJD is a clinically pleomorphic neurodegenerative disease that was originally described in subjects of Azorean descent. In light of the nonallelic heterogeneity in other inherited spinocere-bellar ataxias, we were interested to determine if the MJD phenotype in Japanese and Azorean pedigrees arose from mutations at the same locus. We provide evidence that MJD in five pedigrees of Azorean descent is also linked to chromosome 14q in an 18-cM region between the markers D14S67 and AACT (multipoint lod score +7.00 near D14S81). We also report molecular evidence for homozy-gosity at the MJD locus in an MJD-affected subject with severe, early-onset symptoms. These observations confirm the initial report of linkage of MJD to chromosome 14; suggest that MJD in Japanese and Azorean subjects may represent allelic or identical mutations at the same locus; and provide one possible explanation (MJD gene dosage) for the observed phenotypic heterogeneity in this disease.     

The pKa of the protonated Schiff bases of gecko cone and octopus visual pigments.

A visual pigment is composed of retinal bound to its apoprotein by a protonated Schiff base linkage. Light isomerizes the chromophore and eventually causes the deprotonation of this Schiff base linkage at the meta II stage of the bleaching cycle. The meta II intermediate of the visual pigment is the active form of the pigment that binds to and activates the G protein transducin, starting the visual cascade. The deprotonation of the Schiff base is mandatory for the formation of meta II intermediate. We studied the proton binding affinity, pKa, of the Schiff base of both octopus rhodopsin and the gecko cone pigment P521 by spectral titration. Several fluorinated retinal analogs have strong electron withdrawing character around the Schiff base region and lower the Schiff base pKa in model compounds. We regenerated octopus and gecko visual pigments with these fluorinated and other retinal analogs. Experiments on these artificial pigments showed that the spectral changes seen upon raising the pH indeed reflected the pKa of the Schiff base and not the denaturation of the pigment or the deprotonation of some other group in the pigment. The Schiff base pKa is 10.4 for octopus rhodopsin and 9.9 for the gecko cone pigment. We also showed that although the removal of Cl- ions causes considerable blue-shift in the gecko cone pigment P521, it affects the Schiff base pKa very little, indicating that the lambda max of visual pigment and its Schiff base pKa are not tightly coupled.     

Effects of irradiation on neuropeptide expression in rat salivary gland and spinal cord

Summary It is well-known that a large number of factors can influence the expression of neuropeptides in the nervous system. In the present study, the effects of unilateral and bilateral irradiation to the rat head and neck on the expression of neuropeptides in the innervation of the submandibular gland and in the ganglionic cells of the submandibular ganglion was examined ten days and six months after treatment. Antisera directed against enkephalin and bombesin and immunohistochemical methods were used. The effects of bilateral irradiation on the staining pattern of various neuropeptides in the cervical spinal cord were also studied. In the submandibular gland and in the submandibular ganglionic cells, there was a markedly increased neuropeptide expression ten days after bilateral treatment, as seen after staining with both antisera used, while no changes occurred after unilateral treatment. Six months after treatment, the pattern of neuropeptide expression in the submandibular gland/ganglion corresponded to that seen in controls. Irradiation did not lead to any changes in the staining pattern of neuropeptides in the spinal cord. The observations show that there is a great complexity in the susceptibility of nervous tissues to radiotherapy with respect to influences on the expression of neuropeptides.     

RFLP tagging of a new semidwarfing gene in rice

A new rice semidwarfing gene which is not allelic tosd1, temporarily designated assdg, might be of use as a new source of semidwarfism in rice breeding programs. We report here the identification of a DNA marker closely linked to this gene. The DNA marker was identified by testing 120 mapped rice RFLP makers as hybridization probes for Southern analysis of a pair of nearly isogenic lines with or withoutsdg. Linkage association of the marker with the gene was verified using a F₂ population segregating for semidwarfism. RFLP analysis showed thatsdg is closely linked to a single-copy DNA clone RZ182 on chromosome 5, with a distance of 4.3 centiMorgans between them. This marker may facilitate early selection for the semidwarfing gene in rice breeding programs     

田林老山中山两类森林凋落物研究

田林老山中山两类森林凋落物研究梁宏温（广西农学院林学分院,南宁５３０００１）ＳｔｕｄｉｅｓｏｎｔｈｅＬｉｔｔｅｒｆａｌｌｏｆＴｗｏＦｏｒｅｓｔＴｙｐｃｓｉｎＭｉｄ—ＡｌｔｉｔｕｄｅｏｆＬａｏｓｈａｎＭｏｕｎｔａｉｎｉｎＴｉａｎｌｉｎＣｏｕｎｔｙ．￥Ｌ...     

细胞间粘附分子1的研究进展

细胞间粘附分子1(ICAM-1),又名CD54,是一种重要的细胞表面粘附分子,属免疫球蛋白超家族．它可与鼻病毒以及整合素家族成员结合,参与炎症,普通感冒,变态反应及移植排斥反应．文章就其细胞分布、表达调节、结构功能、基因工程以及临床应用进行了综述．     

低营养条件下Paclobutrazol(PP333)对黄瓜去顶幼苗直接形成花芽的影响(简报)

植物开花机理是生物学中的一个基本问题,多年来人们进行过许多的研究,积累了大量的事实,然而对开花的机理仍然还不甚清楚。因而在利用原有实验系统的同时,有必要寻找更多简单,又便于分析的实验系统。Jullien等报告离体培养的大豆子叶节能直接产生花芽。我们在建立离体培养黄瓜子叶直接单独形成雄花或雌花的实验系统的过程中,发现黄瓜幼苗去除顶芽后在子叶节处也能直接形成花芽。这一现象有可能用于深入研究各营养器官和花启动间关系等问题,定将     

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。     

肌苷发酵液絮凝除菌体的研究

目前国内肌苷生产厂家普遍采用的提取方法是“双柱法”,即先用阳离子柱吸附,然后再用炭柱吸附。该方法不但周期长,工作量大,能耗高,而且提取收率低,一般只有60％左右,使我国肌苷的生产成本大大提高。因此,寻求新的提取方法,降低生产成本,是肌苷生产厂家及有关科技人员所共同关注的问题。肌苷发酵液的除菌体就是新法提取的步骤之一,它可以省去阳离子吸附柱,直接采用炭柱吸附,采用此法可使提取周期大大缩短,降低能耗,提高提取收率。 肌苷菌体较难清除,本研究采用能耗低、易操作,工作量小的絮凝方法,所用的絮凝剂为天然无毒物质,因此沉淀菌体可用作饲料蛋白,起到一举两得的作用。