Characterization of the dermatan sulfate proteoglycans, DS-PGI and DS-PGII, from bovine articular cartilage and skin isolated by octyl-sepharose chromatography

Two forms of dermatan sulfate proteoglycans, called DS-PGI and DS-PGII, have been isolated from both bovine fetal skin and calf articular cartilage and characterized. The proteoglycans were isolated using either (a) molecular sieve chromatography under conditions where DS-PGI selectively self-associates or (b) chromatography on octyl-Sepharose, which separates DS-PGI from DS-PGII based on differences in the hydrophobic properties of their core proteins. The NH2-terminal amino acid sequence of DS-PGI from skin and cartilage is identical. The NH2-terminal amino acid sequence of DS-PGII from skin and cartilage is identical. However, the amino acid sequence data and tryptic peptide maps demonstrate that the core proteins of DS-PGI and DS-PGII differ in primary structure. In DS-PGI from bovine fetal skin, 81-84% of the glycosaminoglycan was composed of IdoA-GalNAc(SO4) disaccharide repeating units. In DS-PGI from calf articular cartilage, only 25-29% of the glycosaminoglycan was composed of IdoA-GalNAc(SO4). In DS-PGII from bovine fetal skin, 85-93% of the glycosaminoglycan was IdoA-GalNAc(SO4), whereas in DS-PGII from calf articular cartilage, only 40-44% of the glycosaminoglycan was IdoA-GalNAc(SO4). Thus, analogous proteoglycans from two different tissues, such as DS-PGI from skin and cartilage, possess a core protein with the same primary structure, yet contain glycosaminoglycan chains which differ greatly in iduronic acid content. These differences in the composition of the glycosaminoglycan chains must be determined by tissue-specific mechanisms which regulate the degree of epimerization of GlcA-GalNAc(SO4) into IdoA-GalNAc(SO4) and not by the primary structure of the core protein.     

Mechanism of food restriction: protection of cellular homeostasis

The major difficulty in defining the mechanisms for the action of food restriction relates to its diversity and lack of specificity. In searching for the common factor(s) and commonality involved in such diversified effects, a cellular homeostasis mechanism is proposed. A study initiated in our laboratory strongly indicates that the cellular homeostatic mechanism is seriously compromised by oxidative damage of free radical reaction with aging. Data on mitochondrial hydroperoxide, microsomal cytochrome P-450 breakdown, and reduction of cytosolic antioxidant capacity support the notion. Remarkably, food restriction attenuates all of these age-related changes. It is concluded therefore that food restriction preserves the homeostatic regulatory processes by maintaining the integrity of (i) membrane structure and function, (ii) proper redox state of cellular components, and (iii) detoxification process of xenobiotics.     

Screening of yeast strains capable of hyperproducing amylolytic enzymes

Summary Fifteen strains of yeast, which produced an extracellular amylolytic enzymes, were isolated from nature. One of them produced more than 100 times the enzyme activity in comparison with the 14 strains and the extremely hyperproducing strain of yeast was identified asCandida sp. 347. Paper chromatograms of the amylolytic enzyme demonstrated activity of amyloglucosidase. The optimum pH for activity of the enzyme was 5.5–6.0 and optimum temperature was 60°C.     

TGF-beta and retinoic acid: regulators of growth and modifiers of differentiation in human epidermal cells.

In the epidermis of skin, a fine balance exists between proliferating progenitor cells and terminally differentiating cells. We examined the effects of TGF-beta s and retinoic acid (RA) on controlling this balance in normal and malignant human epidermal keratinocytes cultured under conditions where most morphological and biochemical features of epidermis in vivo are retained. Our results revealed marked and pleiotropic effects of both TGF-beta and RA on keratinocytes. In contrast to retinoids, TGF-beta s acted on mitotically active basal cells to retard cell proliferation. Although withdrawal from the cell cycle is a necessary prerequisite for commitment to terminal differentiation, TGF-beta s inhibited normal keratinization in suprabasal cells and promoted the type of differentiation commonly associated with wound-healing and epidermal hyperproliferation. The actions of TGF-beta s and RA on normal keratinization were synergistic, whereas those on abnormal differentiation associated with hyperproliferation were antagonistic. These observations underscore the notion that environmental changes can act separately on proliferating and differentiating cells within the population. Under the conditions used here, the action of TGF-beta s on human keratinocytes was dominant over RA, and TGF-beta s did not seem to be induced as a consequence of RA treatment. This finding is consistent with the fact that RA accelerated, rather than inhibited, proliferation in raft cultures. Collectively, our data suggest that the effects of both factors on epidermal growth and differentiation are multifaceted and the extent to which their action is coupled in keratinocytes may vary under different conditions and/or in different species.     

Inhibition of nitric oxide synthesis increases mortality in Sindbis virus encephalitis.

Sindbis virus (SV) is an alphavirus that causes acute encephalomyelitis in mice. The outcome is determined by the strain of virus and by the age and genetic background of the host. The mortality rates after infection with NSV, a neurovirulent strain of SV, were as follows v: 81% (17 of 21) in BALB/cJ mice; 20% (4 of 20) in BALB/cByJ mice (P < 0.001); 100% in A/J, C57BL/6J, SJL, and DBA mice; and 79% (11 of 14) in immunodeficient scid/CB17 mice. Treatment with Nomega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthetase (NOS) inhibitor, increased mortality to 100% (P < 0.05) in NSV-infected BALB/cJ mice, to 95% (P < 0.001) in BALB/cByJ mice, and to 100% in scid/CB17 mice. BALB/cJ and BALB/cByJ mice had similar levels of inducible NOS mRNA in their brains, which were not affected by L-NAME or NSV infection. Brain NOS activity was similar in BALB/cJ and BALB/cByJ mice before and after infection and was markedly inhibited by L-NAME. NSV replication in the brains of BALB/cJ mice, BALB/cByJ mice, and mice treated with L-NAME was similar. Treatment of N18 neuroblastoma cells with NO donors S-nitroso-N-acetylpenicillamine or sodium nitroprusside in vitro before infection increased cell viability at 42 to 48 h compared with untreated NSV-infected N18 cells with little effect on virus replication. These data suggest that NO protects mice from fatal encephalitis by a mechanism that does not directly involve the immune response or inhibition of virus growth but rather may enhance survival of the infected neuron until the immune response can control virus replication.     

神经敏感性的降低是棉铃虫对拟除虫菊酯抗药性的重要机制

用扫描电子显微镜和光学显微镜的染色观察,研究了棉铃虫Helicoverpa armigeraHubner 3龄幼虫腹部神经一肌肉的分布,表明其腹纵肌细胞适合于作电生理细胞内记录。用电生理细胞内微电极记录法研究了棉铃虫三个品系：对照品系、功夫菊酯抗性品系(Cy-R,抗性指数13.4)和氰戊菊酯抗性品系(Fn-R,抗性指数37.9)的3龄幼虫神经一肌肉材料对相应杀虫剂的神经敏感性。结果表明：用10^-6mol/L的功夫菊酯处理Cy-R,在30min内有40%的个体对药剂无反应,另外60%的个体产生反应所需的时间是对照品系的3.5倍。用10^-6mol/L的氰戊菊酯处理Fn-R,在30min内有47%的个体对药剂无反应,另外53%的个体产生反应所需的时间是对照品系的4.2倍。这些结果说明神经敏感性降低是棉铃虫对拟除虫菊酯抗药性的重要机制。     

从水稻同源三倍体中鉴定出无融合生殖种质TAR

水稻杂种优势的成功应用使水稻单产提高了20%,这主要得益于70年代初细胞质雄性不育系的发现和利用。但传统的三系法杂交水稻必须做到不育系、保持系、恢复系“三系”配套,选育程序和杂交种子生产环节较复杂,以致培育目标组合的周期长、效率低、推广环节多,同时种子成本高、价格贵[1]。80年代光敏核不育水稻以其“一系两用、配组自由”等优越性大有取代三系杂交水稻的趋势。但是,光敏核不育特性同时又受温度的调控,加之育性波动等缺陷使两系杂交水稻的研究和利用受到严重制约[2]。80年代后期,科技工作者开始探索利用无融合生殖固定水稻杂种优…     

可育的抗除草剂溴苯腈转基因小麦

报道了采用微粒轰击（Ｍｉｃｒｏｐｒｏｊｅｃｔｉｌｅ ｂｏｍ ｂａｒｄｍ ｅｎｔ） 幼胚将除草剂抗性基因导入小麦（Ｔｒｉｔｉｃｕｍａｅｓｔｉｖｕｍ Ｌ．）的转化研究。实验共使用了１３ 个小麦品种, 从开花后１４～１８ ｄ 的籽粒中剥取幼胚, 植物表达质粒含有ＣａＭＶ ３５Ｓ启动子控制的除草剂溴苯腈抗性基因ｂｘｎ 以及筛选标记基因ＮＴＰⅡ。采用高压放电基因枪,用质粒ＤＮＡ 包被的钨粒轰击预培养３ ｄ 的幼胚。在含有卡那霉素类似物ｇｅｎｅｔｉｃｉｎ Ｇ４１８ｓｕｌｐｈａｔｅ 的ＭＳ培养基上, 经过多步骤筛选和分化, 从８００ 多个幼胚中获得了１６ 株转化苗。除草剂抗性鉴定和Ｓｏｕｔｈｅｒｎ 杂交分析证明, 其中４ 株为转基因植物,具有溴苯腈抗性, 并且自交可育。转化工作从分离幼胚到转化苗鉴定完毕, 最短时间为６ 个月, 因此, 该方法是一项快速有效的基因导入技术