2,4—D在玉米幼叶培养中的歧义作用

本文报道,在玉米幼苗第二片叶的组织培养中:1.接近叶基的细胞对2,4-D敏感性强,而离叶基较远的细胞对2,4-D敏感性则相对弱;2.在0.02—6mg/L浓度下,2,4-D能刺激细胞进行分裂,而在20—40mg/L浓度时,2,4-D则起抑制作用;3.离叶基21mm以上的叶细胞失去对各种浓度2,4-D的反应能力;4.2,4-D诱导的愈伤组织,大多是由一些原先处于抑制状态的根原基形成的。     

4D和4R对小麦三种同工酶合成的影响

利用聚丙烯酰胺凝胶电泳对小麦品种天选15号、天选15号—4D缺体,黑麦品种德国白粒及利用“缺体回交法”培育的小麦(4D)一黑麦(4R)异代换系幼苗的过氧化物酶同工酶、细胞色素氧化酶同工酶及酯酶同工酶进行了研究,结果表明4D染色体对小麦的一种过氧化物酶同工酶和一种细胞色素氧化酶同工酶量的合成具有控制作用,在小麦4D缺体的遗传背景下,黑麦4R染色体能够补偿由于4D缺失引起的这两种同工酶合成降低的效应。4D对小麦幼苗期酯酶同工酶的合成没有明显的作用,4R在小麦4D缺体遗传背景下对酯酶同工酶的合成也没有明显的影响     

SYNTHESIS OF RNA IN NEURONS OF THE HYPOGLOSSAL NERVE NUCLEUS, AFTER SECTION OF THE AXON, IN MICE

Synthesis of RNA in neurons of the hypoglossal nerve nucleus after axonal section was studied by means of [5-³H]uridine administration and radioautographic counting techniques in mice. The results of the experiments were evaluated by counts of silver grains over the nucleoplasm and cytoplasm of the neurons. RNA synthesis was greater in neurons after axonal section, and this increase was evident from 12 hr after the operation. The greatest increases in the operated side were observed in the 1st, 2nd and 3rd days after operation. In the 7th and 14th days RNA synthesis was still greater in the hypoglossal nucleus of the sectioned nerve but the difference in the control nucleus was not so striking. In the 30th day synthesis of RNA in left and right hypoglossal nuclei was comparable.     

THE ROLE OF PREDATION IN THE ECOLOGY OF THE RINGED SEAL IN BARROW STRAIT, NORTHWEST TERRITORIES, CANADA

Predation on ringed seals ( Phoca hispida ) was examined in Barrow Strait between March and May 1984 to 1986. Polar bears were the most important predator. Evidence of bear predation was observed at 18–30% of the ringed seal subnivean structures we located. Ten to 24% of predation attempts were successful, with pups making up 75% to 100% of the seals killed. Bears killed an average of 0.08 to 0.51 seals/km², which comprised 8 to 44% of the estimated annual pup production. Bears were successful on average in 11.3% of their attempts to kill pups hidden inside birth lairs. On southeast Baffin Island where snow was soft and pups were exposed, bears were successful in 33.5% of their attempts to kill a seal. Negative correlations were found between mean snow depth and predation by polar bears ( r = -0.896, P = 0.04, n = 5) in 1985, and between snow depth and the number of predation attempts ( r = -0.613, P = 0.02, n = 14) in 1986.     

THE EFFECTS OF 4-HYDROXYBUTYRIC ACID ON THE BIOSYNTHESIS OF AMINO ACIDS IN THE CENTRAL NERVOUS SYSTEM

—The effect of 4-hydroxybutyrate (GHB) on cerebral glucose metabolism has been studied. GHB increases the glucose level, decreases the lactate concentration and diminishes the incorporation of glucose carbon into glutamic acid, glutamine, aspartic acid and GABA in the brain of the rat in a state of general anaesthesia. The data reported here suggest that GHB interferes in the metabolism of glucose in brain.     

四种猕猴桃属植物的染色体数目观察

本文报道了四种猕猴桃植物的染色体数目。结合其他作者的有关报道,讨论了猕猴桃属的染色体基数,性染色体,倍性,及其与地理分布之间的关系。     

COMPARATIVE ANALYSIS OF THE CONCENTRATION OF INJECTED HORSERADISH PEROXIDASE IN CYTOPLASMIC GRANULES OF THE KIDNEY CORTEX, IN THE BLOOD, URINE, AND LIVER

The concentration of horseradish peroxidase in total particulate fractions from the kidney cortex did not change much during the first few hours after injection, as long as most of the injected protein was not yet cleared from the blood. It decreased at a rate of 6–8% per hr afterwards. The concentration of peroxidase in total particulate fractions increased in proportion to the load (dose) over a wide range, suggesting that a constant fraction of the protein was reabsorbed by micropinocytic vesicles into the tubule cells from the glomerular filtrate. The amount of peroxidase excreted in the urine also increased in proportion to the injected dose. The proportion of peroxidase taken up by the liver, however, decreased several times when the dose was increased. A marked decrease of protein uptake into the kidney cortex and an increase of urinary excretion were observed when rats received a second, equal dose of peroxidase 4 hr after the first injection, and the rate of clearance of peroxidase from the blood was decreased after the second injection. The liver, on the other hand, took up almost twice as much peroxidase after two injections as after one. The uptake of peroxidase by the kidney cortex increased with age. Cytochemical observations on the preferential absorption of peroxidase by certain cell types and segments of the renal tubules in relation to dose are reported.     

微丝在卵子极性产生、分裂沟形成和极体排放中的作用

小鼠生发泡（ＧＶ）期卵母细胞在１μｇ／ｍｌ细胞松弛素Ｂ（ＣＢ）中培养,部分微丝解聚,卵母细胞不 能产生极性而在细胞中部形成分裂沟（假分裂）;极泡期印在１μｇ／ｍｌ ＣＢ中,分裂沟继续收缩,排放第 一极体。假分裂的分裂沟和极泡期的极区分裂沟形成均与分裂器中体位置相关。部分微丝解聚并不影响 假分裂和第一极体排放;全部微丝解聚（１０μｇ／ｍｌ ＣＢ）将中断假分裂和胞质分裂,分裂沟消失,卵恢 复球形。由此可见,成熟过程中卵母细胞极性的产生及分裂沟的形成都依赖于微丝的聚合。胞质分裂和 第一极体排放同样需一定量的微丝存在。     

THE 4-O-METHYL METABOLITES OF CATECHOLAMINES IN MAN: CHROMATOGRAPHIC IDENTIFICATION OF 3-HYDROXY,4-METHOXYPHENYLACETIC ACID (HOMO-ISO-VANILLIC ACID) IN CEREBROSPINAL FLUID

Abstract— The isomeric phenolic acids, homovanillic acid (4-hydroxy,3-methoxyphenylacetic acid) and homo-iso-vanillic acid (3-hydroxy,4-methoxyphenylacetic acid), were separated and identified by means of paper chromatography of their azo-derivatives with diazotized para-nitroaniline. Using this chromatographic procedure, homo-iso-vaniliic acid was identified in several samples of human cerebrospinal fluid, an observation which suggests that dopamine may be partly metabolized in brain, with the production of 4-methoxy derivatives.     

THE PHOTOSYNTHETIC EFFICIENCY OF PHYCOCYANIN IN CHROOCOCCUS,AND THE PROBLEM OF CAROTENOID PARTICIPATION IN PHOTOSYNTHESIS

The absorption spectra of the principal pigment components extracted from Chroococcus cells have been measured, and their sum compared with the absorption of a suspension of living cells. The agreement was sufficiently close so that it was concluded the absorption spectra of the extracted and separated pigment components could be used to obtain estimates of the relative absorption of the various components in the living cells. The quantum yield of Chroococcus photosynthesis was measured at a succession of wave lengths throughout the visible spectrum, and the dependence of yield on wave length was compared with the proportions of light absorbed by the pigment components. This comparison showed beyond reasonable doubt that the light absorbed by phycocyanin is utilized in photosynthesis with an efficiency approximately equal to that of the light absorbed by chlorophyll. The light absorbed by the carotenoid pigments of Chroococcus seems for the most part to be unavailable for photosynthesis. The results leave open the possibility that light absorbed by the carotenoids is active in photosynthesis, but with an efficiency considerably lower than that of chlorophyll and phycocyanin. It is also possible that the light absorbed by one or a few of the several carotenoid components is utilized with a high efficiency, while the light absorbed by most of the components is lost for photosynthesis.     

CHANGES IN THE ORGANIZATION OF TUBULIN DURING MEIOSIS IN THE EGGS OF THE SURF CLAM, SPISULA SOLIDISSIMA

Polymerized tubulin can be stabilized in Kane's spindle isolation medium (HGL solution), isolated by differential centrifugation and then assayed by colchicine binding activity. In the eggs of the surf clam, Spisula solidissima, the level of particulate tubulin undergoes a series of specific changes during first meiotic division. In either unactivated ("interphase") eggs or metaphase eggs the amount of particulate tubulin was about 13% of the total at 23°C. The amount of particulate tubulin decreased shortly after activation, reaching a minimum value at about 5 min, the time of nuclear membrane breakdown. The particulate tubulin concentration then rose, reaching a maximum at metaphase, and then decreased again during anaphase, reaching a minimum at first polar body formation. In HGL homogenates of unactivated eggs a structure is present which has been shown to contain the interphase particulate tubulin (IPT). This structure consists essentially of a 10–20 µ granular sphere attached to a membranous material which is probably part of the egg cortex. These particles are absent at the time of nuclear membrane breakdown, when the level of particulate tubulin is minimal and when the first signs of spindle formation are visible. Electron microscopy of these particles by negative staining indicates that they are composed of microtubules associated with a granular matrix which may be a polymorphic aggregate of tubulin.     

SPECIALIZATION OF MESOPHYLL MORPHOLOGY IN RELATION TO C4 PHOTOSYNTHESIS IN THE POACEAE

Our current understanding of the photosynthetic process in species utilizing the C₄ photosynthetic pathway suggests that photosynthetic efficiency should be enhanced by: 1) maximizing the conductance of the gas phase transport pathway from the leaf exterior to the mesophyll cell surfaces; 2) maximizing cytoplasmic connections and metabolite transport between bundle sheath and mesophyll parenchyma cells; and 3) minimizing the conductance of the gas phase transport pathway from the bundle sheath cells to the leaf exterior. In this study we have examined several species in the Poaceae with C₄ photosynthesis to determine if there is any evidence for anatomical specialization which would lead to enhanced photosynthetic efficiency by these processes. Observations with light and scanning electron microscopes revealed specializations in mesophyll cell morphology and arrangement which include branched cells forming intercellular channels. These specializations are hypothesized to contribute to photosynthetic efficiency through its influence on the above transport processes.