Tocopherol content in tissues of mammals of different ecogenesis

Concentration of vitamin E (α-tocopherol) was studied in liver, kidney, heart, and skeletal muscle of 12 mammalian species, of which nine inhabited under natural conditions, while three were farm-bred. In the majority of the species the highest tocopherol content has been found as a rule in the animal liver and kidney. Essential differences have been revealed in distribution and level of α-tocopherol including those in taxonomically close species. These differences seem to be due to ecological peculiarities of the animals. The obtained results allow considering α-tocopherol as one of factors of maintenance of the natural antioxidant system at the steady level.     

Expression of human N-myristoyltransferase inEscherichia coli. Comparison with N-myristoyltransferases expressed in different tissues

Myristoyl CoA:protein N-myristoyltransferase catalyzes the addition of myristate to the amino-terminal glycine residue of a number of eukaryotic proteins.Escherichia coli transformed with human NMT expression construct produced high levels of N-myristoyltransferase. Using the combination of ammonium sulfate precipitation, chromatography on SP-Sepharose fast flow and fast protein liquid chromatography on Mono-S, the enzyme was purified more than 100 fold with 40% yield. The hNMT fusion protein exhibited an apparent molecular weight of 53 kDa on SDS-polyacrylamide gel electrophoresis. Upon cleavage by the Enterokinase [(Asp)₄-Lys], the hNMT exhibited an apparent molecular mass of 49 kDa without loss of catalytic activity. The hNMT activity could be greatly activated severalfold with the use of Tris, SDS, ethanol and acetonitrile. The catalytic activity of hNMT was potently inhibited in a concentration dependent manner by NIP₇₁₁ a bovine brain NMT inhibitory protein with a half maximal inhibition of 31.0 nM. TheE. coli expressed hNMT was homogeneous and showed enzyme activity.Abbreviations NMT N-myristoyl CoA:protein N-myristoyltransferase - NIP₇₁ 71 kDa heat stable membrane bound N-myristoyltransferase inhibitor protein - hNMT human NMT - DTNB N-5,5dithiobis (2-nitrobenzoic acid) - FPLC fast protein liquid chromatography - IPTG isopropyl -D-thiogalactopyranoside - cDNA complementarydeoxyribonucleic acid - SDS sodium dodecyl sulfate - PMSF phenylmethylsulfonyl fluoride     

Increase in calcium content and Ca2+-ATPase activity in the brain of fasted rats: Comparison with different ages

The effect of fasting on calcium content and Ca²⁺-ATPase activity in the brain tissues of 5 weeks and 50 weeks old rats was investigated. Brain calcium content and Ca²⁺-ATPase activity in the microsomal and mitochondrial fractions of the brain homogenate from young and elderly rats were significantly increased by overnight–fasting. These increases were appreciably restored by a single oral administration of glucose solution (400 mg/100 g body weight) to fasted rats. In comparison with young and elderly rats, brain calcium content and microsomal Ca²⁺-ATPase activity were significantly elevated by increasing ages. The effect of ageing was not seen in the brain mitochondrial Ca²⁺-ATPase activity. When calcium (50 mg/100 g) was orally administered to young and elderly rats, brain calcium content was significantly elevated. The calcium administration–induced increase in brain calcium content was greater in elderly r crease in Ca²⁺-ATPase activity in the microsomal and mitochondrial fractions of brain homogenates from young rats. In aged rats, the microsomal Ca²⁺-ATPase activity was not further enhanced by calcium administration, although the mitochondrial enzyme activity was significantly raised. The present study demonstrates that the fasting–induced increase in brain calcium content is involved in Ca²⁺-ATPase activity raised in the brain microsomes and mitochondria of rats with different ages, supporting a energy–dependent mechanism in brain calcium accumulation.     

Comparison of glycopeptide in lung cancer tissues of different histological types

The glycopeptide was studied in the pulmonary cancer tissues of three different histological types including squamous cell carcinoma, undifferentiated cell carcinoma, and adenocarcinoma. The glycopeptide preparation was made by digesting the lung cancer tissues with proteolytic enzymes followed by removal of enzymes and undigested protein. The comparison of the relative proportion of the glycopeptide, which migrated toward the anode slower than hyaluronic acid, and was stained with both alcian blue and PAS, and contained higher sialic acid, was carried out among three different histologic types of lung cancer. This glycopeptide was highest in adenocarcinoma, followed by undifferentiated cell carcinoma, and was lowest in squamous cell carcinoma.     

Comparison of plastid DNA replication in different cells and tissues of the rice plant

In a previous study, we mapped replication origin regions of the plastid DNA around the 3 end of the 23S rRNA gene in rice suspension-cultured cells. Here, we examined initiation of the plastid DNA replication in different rice cells by two-dimensional agarose gel electrophoresis. We show for the first time, to our knowledge, that the replication origin region of the plastid DNA differs among cultured cells, coleoptiles and mature leaves. In addition, digestion of the replication intermediates from the rice cultured cells with mung bean nuclease, a single-strand-specific nuclease, revealed that both two single strands of the double-stranded parental DNA were simultaneously replicated in the origin region. This was further confirmed by two-dimensional agarose gel analysis with single-stranded RNA probes. Thus, the mode of plastid DNA replication presented here differs from the unidirectional replication started by forming displacement loops (D-loops), in which the two D-loops on the opposite strands expand toward each other and only one parental strand serves as a template.     

Total water content in different areas of the human term placenta.

The authors study the total water content in two different areas (parabasal and subchorial), in 40 normal, full-term placentas. The water content is found to be different in these two areas. As an average, it is 0.90% higher in the parabasal area. This difference persists even after washing off the fetal placental blood by perfusión with saline. The difference in the total water content between both areas, which is added to other differences previously demonstrated, must be related to a different functional role of the placental areas.     

不同类型矮杨梅叶片中槲皮素含量比较

矮杨梅 (ＭｙｒｉｃａｎａｎａＣｈｅｖａｌ.)为杨梅科 (Ｍｙｒｉｃａｃｅａｅ)杨梅属 (ＭｙｒｉｃａＬ .)植物 ,自然分布于我国云南、贵州、西藏和四川的部分地区 ,为我国特有植物 ,具有药用价值和果品开发前景。近年来的研究表明 ,矮杨梅叶中含有黄酮类化合物槲皮素 (ｑｕｅｒｃｅｔｉｎ) ,有祛痰、止咳作用 ,还能对抗自由基 ,在抗癌、防癌、抗菌、消炎及心血管疾病的预防和治疗方面均具有较强的药理活性[1～ 4 ] 。虽然野生矮杨梅分布区范围窄 ,但其种内分化明显。刘宁等[5,6] 的研究表明 ,在矮杨梅根、茎、叶和果实等诸多器官的形态特征…     

The cholesterol content of the human erythrocyte influences calcium influx through the channel

In order to study the influence of the cholesterol content on the calcium entry channel, the human red blood cell was used as a model system. The cholesterol to lecithin ratio (C/L ratio) of the membrane was modified experimentally by incubating the cells (15h, 25 degrees) with liposomes of defined C/L ratios. Subsequently, net 45Calcium-influx into the cell was measured by inhibiting the Ca-ejecting ATPase with vanadate. Additionally, the use of nitrendipine, a potent calcium channel inhibitor, during incubation allowed the determination of Ca-influx through the calcium channel. A positive correlation between the 45Ca++-influx and the molar C/L ratio of the membrane was found over a wide C/L range. A molar C/L ratio of 1.4 in the membrane increased calcium influx by 150 % compared to controls (molar C/L ratio = 0.8, calcium influx rate = 100 %), while a molar C/L ratio at less than 0.75 decreased calcium influx by 50 %. We conclude, that the cholesterol content of the membrane greatly influences the calcium channel and thus plays a pivotal role for the availability of calcium as a second messenger. These findings may provide a link between high plasma cholesterol and the development of atherosclerosis as well as enhanced platelet aggregability.     

A survey of the interaction of calcium ions with mitochondria from different tissues and species

A survey was made of the capacity of mitochondria isolated from a number of different tissues and species to accumulate Ca(2+) from the suspending medium during electron transport. The species examined included the rat, mouse, rabbit, hamster, guinea pig, cow, chicken, turtle, blowfly, yeast and Neurospora crassa. The tissues examined included vertebrate liver, kidney, brain, heart, spleen, thyroid and adrenal cortex, and the flight muscle of the blowfly. The mitochondria from all vertebrate tissues examined showed: (a) stimulation of State 4 respiration by added Ca(2+) (Ca(2+)/~ activation ratio about 2.0), accompanied by accumulation of Ca(2+) and ejection of H(+), with a H(+)/Ca(2+) ratio about 1.0; (b) a requirement of phosphate for accumulation of large amounts of Ca(2+); (c) respiration-independent high-affinity binding sites for Ca(2+); (d) endogenous Ca(2+), which is largely released by uncoupling agents. However, mitochondria from yeast and blowfly flight muscle are unable to accumulate Ca(2+) in a respiration-dependent process and possess no high-affinity Ca(2+)-binding sites. These findings support the view that the high-affinity sites represent the ligand-binding sites of a specific Ca(2+) ;permease' or transport system in the membrane. The relatively high affinity for Ca(2+), which equals or exceeds the affinity for ADP, and the generally uniform characteristics of Ca(2+) transport in all the vertebrate mitochondria tested strongly suggest that respiration-linked Ca(2+) accumulation plays a general and fundamental role in vertebrate cell physiology.     

Phosphorylase activity and glycogen content in cerebral and myocardium tissues in rats of different age

The phosphorylase activity (EC 2.4.1.1) and the glycogen content were determined in the brain and myocardium of adult and old rats. In the cortex and while substance of great cerebral hemispheres, the phosphorylase a activity decreases and the phosphorylase b activity increases, while the total enzyme activity remains unchanged with aging. In the myocardium, the activity of phosphorylase a increases, while that of phophorylase b decreases against a background of an insignificant decrease in the total phosphorylase activity. During aging, the glycogen content decreases sharply in the myocardium, whereas in the cerebral tissue it remains unchanged. Age peculiarities of the adrenaline effect upon myocardial phosphorylase activity are presented.     

Comparison of calcium accumulation between the arteries of human and monkey

To examine whether an accumulation of elements in the arteries was affected by the way of walking, the authors investigated age-related changes of elements in the arteries of the Japanese, Thai, and Japanese monkeys. After the ordinary dissections by medical students were finished, the subclavian, axillary, brachial, radial, common iliac, externaliliac, femoral, and posterior tibial arteries were resected from the subjects of the Japanese and Thai over 60 yr of age and they were also resected from the Japanese monkeys over 20 yr of age. The element content was determined by inductively coupled plasma-atomic emission spectrometry. It was found that in an comparison between the arteries of anatomically corresponding regions, the average content of Ca was eight times or four times higher in the arteries of the lower limb than in the arteries of the upper limb in the Japanese or Thai, over 60 yr of age, respectively. In the Japanese monkeys over 20 yr of age, the average content of Ca was 1.2 times higher in the arteries of the lower limb than in the arteries of the upper limb. The result suggests that an accumulation of Ca in the arteries of the lower limb with aging is affected by the way of walking.