Studies on Foliar Penetration: III. THE EFFECTS OF CHLORINATION ON THE RATE OF PENETRATION OF PHENOXYACETIC ACID AND BENZOIC ACID INTO LEAVES OF PHASEOLUS VULGARIS

A comparative study has been made of the penetration into leafdisks of Phaseolus vulgaris of (a) phenoxyacetic acid and its2-, 4-, 2, 4-, 2, 6-, 3-5, 2, 4, 5-, and 2, 4, 6- chloro derivatives,and (b) benzoic acid and its 2-, 2, 4-, 2, 5-, 2, 3, 6-chloroand 3, 6-dichloro-2-methoxy derivatives. The methods of synthesisof each compound with ¹⁴C incorporated in the carboxyl groupare described. In the series of substituted phenoxyacetic acids it was establishedthat only for 2, 4, 5-T was there an appreciable loss of radioactivityfrom the system either in the light or darkness. In contrast,with the exception of 2, 4-DCBA, ¹⁴C is lost from each memberof the series of substituted benzoic acids. The level and pattern of penetration in the two series is differentiallyaffected by chlorination. In general progressive chlorinationof phenoxyacetic acid leads to an increase in the rate of penetrationin both light and darkness. There are, however, exceptions;for illuminated disks the rate of entry of 2,4,5-T is exceededby 2,4,6-T, 2, 4-D, and 2, 6-D whereas in the dark 2,4,5-T hasby far the highest rate of penetration. Progressive chlorinationof benzoic acid, however, depresses entry in both light anddarkness. Possible relationships between these findings and changes inselected physical properties of each series of compounds havebeen examined. Between members of the series of substitutedphenoxyacetic acids there is little variation in the dissociationconstant whereas for the substituted benzoic acids there isa marked lowering of the pK as the degree of chlorination increases.The rate of elution with chloroform of each compound from abuffered Silocel column gives a measure of the degree of partitioninto a lipid medium at a given pH. At pH 5.2 chlorination ofphenoxyacetic acid results in more rapid elution whereas chlorinationof benzoic acid causes a longer hold up. An apparatus was designed to enable measurements to be madeof the rate at which a compound moves from one aqueous phaseto another through a layer of lipid. Chlorination promotes therate of transfer of phenoxyacetic acid through octanol but retardsthe transfer of benzoic acid. The extent to which chlorinationdepresses the rate of transfer of benzoic acid matches the diminutionin the rate of leaf penetration. For the series of substitutedphenoxyacetic acids transfer rates and penetration rates followsimilar trends in the dark but in the light agreement is lessgood. These findings are discussed in relation to prior studies onthe rate of uptake and the metabolic fate of the ndividual compoundsin a number of plant tissues.     

The Uptake of Growth Substances: XIV. PATTERNS OF UPTAKE BY LEMNA MINOR OF PHENOXYACETIC AND BENZOIC ACIDS FOLLOWING PROGRESSIVE CHLORINATION

The interrelationships between chemical structure and patternsof uptake by Lemna minor have been examined for (a) phenoxyaceticacid and its 2-, 4-, 2,4-, 2,6-, 3,5-, 2,5-, 2, 4, 5- and 2,4,6-chloroderivatives and (b) benzoic acid and its 2-, 2,4-, 2,5-, 2,3,6-chloro-and 3,6-dichloro-2-methoxy derivatives. All compounds contained¹⁴C in the carboxyl group. The plants from a clonal populationwere grown at a constant temperature and continuously illuminated. With progressive chlorination of phenoxyacetic acid, uptakeis enhanced, so that by 6 h there is a fourfold difference betweenthe monochloro- and trichloro-derivatives. In complete contrast,chlorination of benzoic acid greatly suppresses uptake and thedifferences associated with the degree of chlorination are smaller. Arising out of previous studies, the effects of adding streptomycin,synthalin, and cetyltri-methylammoniumbromide on the courseof uptake of individual members of the two series have beenexamined. Each of the additions can induce positive, negative,or null changes in the pattern of uptake, but the nature ofthe response is also dependent on the properties of the compound. These findings are discussed in relation to prior studies concerning(a) penetration into the leaves of Phaseolus vulgaris, (b) uptakeby excised segments of etiolated stems, and (c) changes in physico-chemicalproperties resulting from progressive chlorination. Many of the complexities still remain to be resolved but itseems clear that adsorption by Borne membrane system involvingthe carboxyl group of the entering acid and the positively chargedquaternary ammonium group of alpha-lecithin cannot be restrictedto compounds which are physiologically active as auxins or herbicides.     

THE ACTIVATION OF STARFISH EGGS BY ACIDS : II. THE ACTION OF SUBSTITUTED BENZOIC ACIDS AND OF BENZOIC AND SALICYLIC ACIDS AS INFLUENCED BY THEIR SALTS.

1. Comparison of the rates of activation of unfertilized starfish eggs in pure solutions of a variety of parthenogenetically effective organic acids (fatty acids, carbonic acid, benzoic and salicylic acids, chloro- and nitrobenzoic acids) shows that solutions which activate the eggs at the same rate, although widely different in molecular concentration, tend to be closely similar in C_H. The dissociation constants of these acids range from 3.2 x 10^–7 to 1.32 x 10^–3. 2. In the case of each of the fourteen acids showing parthenogenetic action the rate of activation (within the favorable range of concentration) proved nearly proportional to the concentration of acid. The estimated C_H of solutions exhibiting an optimum action with exposures of 10 minutes (at 20°) lay typically between 1.1 x 10^–4 M and 2.1 x 10^–4 M (pH = 3.7–3.96), and in most cases between 1.6 x 10^–4 M and 2.1 x 10^–4 M (pH = 3.7–3.8). Formic acid (C_H = 4.2 x 10^–4 M) and o-chlorobenzoic acid (C_H = 3.5 x 10^–4 M) are exceptions; o-nitrobenzoic acid is ineffective, apparently because of slow penetration. 3. Activation is not dependent on the penetration of H ions into the egg from without, as is shown by the effects following the addition of its Na salt to the solution of the activating acid (acetic, benzoic, salicylic). The rate of activation is increased by such addition, to a degree indicating that the parthenogenetically effective component of the external solution is the undissociated free acid. Apparently the undissociated molecules alone penetrate the egg freely. It is assumed that, having penetrated, they dissociate in the interior of the egg, furnishing there the H ions which effect activation. 4. Attention is drawn to certain parallels between the physiological conditions controlling activation in the starfish egg and in the vertebrate respiratory center.     

The Uptake of Growth Substances: XV. THE DIFFERENTIAL EFFECTS OF PROGRESSIVE CHLORINATION OF PHENOXYACETIC ACID ON ENTRY INTO THE EPIDERMAL AND CUT SURFACES OF STEM SEGMENTS

The comparative patterns of entry into segments with sealedand open ends, excised from etiolated internodes of Pisum sativum,have been examined for phenoxyacetic acid (POA) and its 2-,4-, 2,4-, 2,6-, 3,5-, 2,4,5- and 2,4, 6-chloro derivatives,each containing ¹⁴C in the carboxyl group. Sealing the ends greatly depresses the level of entry, on averagean eight-fold reduction at 9 h. Likewise, the interrelationsbetween the degree of chlorination and uptake potential aredisparate. For segments with exposed cut surfaces the finalcontent is maximal for POA and the 2-chloro compound and minimalfor the 3,5-dichloro derivative (3,5-D) with an eight-fold difference.With sealed ends this difference is reduced to two-fold butwhile 3,5-D accumulates least uptake is now highest for POAand 2,4-D. There are also changes in the order with time. Initially,2,4,5-T penetrates fastest into sealed segments but for segmentswith open ends entry is most rapid for the 4- and 2,4,6-chloroderivatives. Additions of streptomycin and cetyltrimethylammoniumbromide(CTAB) induce differential changes in the patterns of uptake.Where uptake is promoted the enhancement is not restricted toactive auxins. Sealing the ends may alter the nature of theresponse. The likely physico-chemical and metabolic processes concernedin the two routes of entry are discussed and the results comparedwith previous divergent findings on the relationship betweenchemical structure and uptake by Lemna minor and penetrationinto leaves of Phaseolus vulgaris.     

镇海水库拟柱孢藻的分离鉴定和氮磷对其生长的影响

以分离自广东省镇海水库的拟柱孢藻N8为对象, 探究其在不同磷浓度及氮磷浓度组合下的生长情况。结果表明, 拟柱孢藻N8对磷的适应范围很宽, 在0.025.12 mg/L磷浓度下均能生长, 最适生长磷浓度范围为0.165.12 mg/L, 磷浓度的升高能显著延长拟柱孢藻的对数生长期和提高生物量。动力学分析表明, 拟柱孢藻N8有较低的KSP值, 对磷元素的亲和性较高, 在磷营养贫乏的环境下更容易形成优势。在氮磷组合实验中, 低氮(0.5 mg/L)显著抑制拟柱孢藻的生长, 且这种生长抑制不受磷浓度的影响; 而在低磷(0.04 mg/L)条件下, 水体中氮浓度的增加会显著促进拟柱孢藻的生长, 拟柱孢藻在高氮中磷和高氮高磷下的生长显著优于其他氮磷组合条件。研究表明, 广东省水库拟柱孢藻的生长受磷的限制较弱, 氮是其生长的决定因子。       

EFFECTS OF ETHANOL ON THE ACTIVITY OF ADENOSINE TRIPHOSPHATASE AND ACETYLCHOLINESTERASE IN SYNAPTOSOMES ISOLATED FROM GUINEA-PIG BRAIN

Nerve ending fractions from guinea-pig cerebral cortex contained more than one-half of the Na-K ATPase activity present in the original homogenate. Ethanol at concentrations ranging from 0·043 to 2·57 m inhibited the Na-K ATPase to a significantly greater extent than the Mg-activated ATPase or AChE. The inhibition of membrane-bound Na-K ATPase by ethanol was of the non-competetive type and the activity of Na-K ATPase was increasingly inhibited by alcohols of increasingly longer chain length. The ability of various alcohols to inhibit membrane-bound Na-K ATPase activity was correlated with their lipid solubility.     

从甘蓝夜蛾分离的一种微孢子虫生物学特性研究

从广州市郊菜地捕捉的甘蓝夜蛾(\%Barathra brassicae L.\%)幼虫体中分离到一种微孢子虫(简称BabM)。孢子呈长卵圆形,大小为：402±036μm×199±036μm;孢子表面抗原与家蚕传统微粒子孢子(\%Nosema bombycis,简称N.b.\%)具共同抗原性;BabM微孢子虫孢子的内部结构、发育的特征与\%N.b.\%孢子相类似。BabM微孢子虫对三龄起蚕感染中量(IC５０)为６０3×１０４粒孢子;经卵传染频率较高。初步阐明了从甘蓝夜蛾分离的这种微孢子虫与家蚕\%N.b.\%同为\%Nosema bombycis\%种,但存在着变异现象。     

EFFECTS OF TETRODOTOXIN, CALCIUM AND MAGNESIUM ON THE RELEASE OF AMINO ACIDS FROM SLICES OF GUINEA-PIG CEREBRAL CORTEX

Abstract— Tetrodotoxin, Ca²⁺-deprivation and high-Mg²⁺ were used in an effort to identify the portion of the evoked release of endogenous amino acids, labelled via metabolism of [¹⁴C]-glucose, and several exogenous labelled amino acids, that came from nerve terminals when slices of guinea pig cerebral cortex were superfused with glucose-free solutions and stimulated electrically. With some exceptions, spontaneous release of labelled amino acids was decreased by 2 μm -tetrodotoxin but increased in Ca²⁺-free medium and in solutions containing an extra 24 mm -MgCl₂. Tetrodotoxin suppressed 85–90% of the stimulated release of almost all labelled amino acids, but had a smaller effect on the release of endogenous ¹⁴C-labelled threonine-serine-glutamine (unseparated). In Ca²⁺-free solution, the stimulated release of endogenous ¹⁴C-labelled glutamate, aspartate and GABA was suppressed by 80–90%, but that of endogenous ¹⁴C-labelled threonine-serine-glutamine was unaffected as was most of the release of the other labelled amino acids. In medium containing an extra 24mM-MgCl₂, the stimulated release of endogenous ¹⁴C-labelled glutamate, aspartate and GABA was suppressed by 75-85%, that of exogenous labelled aspartate and GABA by 50–65%, but the release of the other labelled amino acids was unaffected. The control stimulated releases of endogenous ¹⁴C-labelled glutamate, aspartate and GABA were much larger than those of other labelled amino acids but were reduced by tetrodotoxin, Ca²⁺-deprivation and high-Mg²⁺ to a level similar to that of the control stimulated releases of the other labelled amino acids. These results suggest that almost all of the stimulated release of endogenous ¹⁴C-labelled glutamate, aspartate and GABA came from nerve terminals while those of the other labelled amino acids came from other tissue elements. In addition, they are in accord with a transmitter role for glutamate, aspartate and GABA in cerebral cortex.     

油柑果超氧化物歧化酶的化学修饰及其性质的研究

从油柑果中提取SOD[Superoxide dismutase(EC1,15,1,1,)],用山梨醇月桂酸酯（Sorbitol laurate)进行化学修饰,得到SL－SOD。比活力为4200u/mg。交联葡聚糖凝胶层析测分子量为38KD,紫外区最大吸收峰是258nm,修饰后SOD对温度和PH的稳定性均有增强。在某些低浓度的有机介质中活性比在水中高。修饰SOD的半衰期为14h,有效保存期为43d。几乎无免疫原性。     

Studies on Foliar Penetration: 2. THE ROLE OF LIGHT IN DETERMINING THE PENETRATION OF 2,4 DICHLOROPHENOXYACETIC, ACID

A further study has been made of the factors determining thelevel of penetration of 2,4-dichlorophenoxyacetic acid (2,4-D)into leaves. The technique involves the use of leaf disks and2,4-D containing carbon-14 in the carboxyl group. For Phaseolus vulgaris the influence of the pH of the appliedsolution is greater in the light than in the dark. Between 0and 1,000 f.c. at 27° C there is a small increase in therate of penetration into the abaxial surface. Under these conditionsthe rates remain constant up to 56 hours. This linear relationshipholds for concentrations ranging from 100 to 1,000 mg/l, andthe rate of penetration is directly proportional to the concentration.For intensities in excess of 1,000 f.c. the light response ismarkedly different: over the first few hours there is a steadyand relatively slow rate of penetration which is followed bya second phase when the rate is greatly accelerated. This acceleratedrate can be reversed by transferring the disks to darkness,and does not take place at 1° C. Likewise, if excised disksare left for more than one hour in either the light or the darkbefore applying 2,4-D then there is subsequently no phase ofaccelerated penetration. The course of penetration into theadaxial surface exhibits no accelerated rate, and compared tothe abaxial surface the rates are lower. For leaves of Ligustrum ovalifolium, which lack stomata on theadaxial surface, the rates of penetration at 27° C intoboth surfaces remain constant in either light or darkness. Forboth the adaxial and abaxial surfaces, the rate progressivelyincreases from 0 to; 2000 f.c. and there is no phase of acceleratedpenetration. Penetration into the adaxial surface is less. At1° C the rates for both surfaces in either light or darknessare depressed. If disks of Phaseolus are irradiated with ultraviolet light,subsequent penetration is markedly depressed in the light at27° C, but in the dark or at 1° C it is enhanced. On the basis of these findings it is concluded that both physicaland metabolic factors control the rate of penetration of 2,4-DTransport through the cuticle will be dependent on adsorptionand the length of the diffusion paths. Once diffusion gradientshave been established between the surface of the cuticle andthe outer surface of the cytoplasm in the epidermal cells, thesteepness will be dependent on the rates at which 2,4-D is eitherconverted into some metabolite or moved away from the surfaceor into other cells. The relative importance of physical andmetabolic process will be dependent on the permeability andthickness of the cuticle and the level of metabolic activity.The possible role of ectodesmata in determining both the lengthand steepness of the diffusion paths is discussed.     

Studies on Foliar Penetration: VII. FACTORS CONTROLLING THE PENETRATION OF CHLORIDE IONS INTO THE LEAVES OF PHASEOLUS VULGARIS

The pattern of penetration of chloride ions into the abaxialsurfaces of the primary leaves of Phaseolus vulgaris has severalfeatures in common with those previously recorded for 2,4-dichlorophenoxyaceticacid (2,4-D), 2,2-dichloropropionic acid (dalapon), and 4-amino-3,5,6-trichloropicolinicacid (picloram). In the dark the rate of entry of chloride ionsup to 24 h is constant, but in the light entry is at first slowand then more rapid. This acceleration does not occur at lowtemperature or when the tissue is treated with 3-(3,4-dichlorophenyl)-l,l-dimethylureaor phenylmercuric chloride. Neither does it take place at theadaxial surface or when the leaves are more mature. The most distinguishing feature of the pattern of penetrationof chloride ions is its dependence on external pH. In darknessentry is unaffected by changes in pH but in the light the rateof entry is increased as the pH falls, but this response isrestricted to young leaves. No binding of chloride seems tooccur within the tissue. These findings support the view that penetration of the abaxialsurface in young leaves of Phaseolus is largely determined bya membrane system. This system decreases in importance as theleaf matures and the overlying cuticle thickens. At the adaxialsurface the thicker cuticle is seemingly a major barrier topenetration even in very young leaves.     

益智果实,果壳挥发油成分研究

本文报告应用GC—MS用技术从益智果实、果壳挥发油分离鉴定出85种化合物,其中有75种益智挥发油化学成分为首次报导。     

Studies on Foliar Penetration: IX. PATTERNS OF PENETRATION OF 2,4-DICHLOROPHENOXYACETIC ACID INTO THE LEAVES OF DIFFERENT SPECIES

The comparative patterns of penetration of 2,4-dichlorophenoxyaceticacid (2,4-D) into the leaves of Phaseolus vulgaris, Zea mays,Pisum sativum, Beta wlgaris, Helianthus annuus and Gossypiumhirsuium have been examined. Save for Zea and Gossypium where there is little change withthe stage of leaf development the rates of penetration intoboth surfaces decrease as the leaf matures. The relative ratesare dependent on the species and the age of the leaf but thereare differences between the surfaces. In Phaseolus the characteristicsof primary leaves differ from those of trifoliate leaves sinceonly in immature trifoliate leaves is penetration into the adaxialsurface greater. In darkness the rates of penetration over 24 h remain constantor fall but slightly for all species. Light consistently promotespenetration but with Beta there is a lag before entry is acceleratedinto the abaxial surface as has previously been reported foryoung primary leaves of Phaseolus. For the remaining speciesthe courses of penetration in both light and darkness into bothsurfaces follow similar patterns. As the light intensity isincreased entry is enhanced but the limit of response variesbetween species, between surfaces within species, and in trifoliateleaves of Phaseolus with age. For the six species the order of the relative rates of entryis closely similar whether comparisons are made in light ordarkness or between abaxial and adaxial surfaces: viz. Zea >Helianthus > Phaseolus (primary) > Phaseolus (trifoliate)> Pisum = Beta = Gossypium. The observed specific differencesare discussed in relation to variations in leaf structure, theproperties and thickness of the cuticle and the physiologicaland metabolic processes which influence transport within theepidermal tissues after it has passed through the cuticle bydiffusion.     

盐胁迫对大麦叶片类囊体膜上两种形态多胺含量和膜蛋白合成的影响

 用不同浓度NaCl处理6天龄大麦（Hordeum vulgare）幼苗3 d,以非共价键形式与叶片类囊体膜结合的多胺含量在低浓度盐处理时含量不变,随NaCl处理浓度的上升含量明显下降。在检测到的3种多胺中Spd（亚精胺）含量最高,约占膜上非共价键结合多胺总量的40%。以共价键形式与类囊体膜蛋白结合的多胺含量随NaCl处理浓度的上升一直呈下降趋势。在检测到的3种多胺中Put（腐胺）含量最高,约占膜上共价键结合多胺总量的60%以上。低浓度盐处理对14C-Glu向类囊体膜蛋白的掺入没有影响,随NaCl处理浓度的上升14C-Glu向类囊体膜蛋白的掺入明显下降。     

Studies on Chloroplast Degradation in vivo: III. THE EFFECT OF MAGNESIUM ON ELECTRON TRANSPORT AND PHOSPHORYLATIQN IN PLASTIDS ISOLATED FROM YOUNG AND AGEING COTYLEDONS

The magnesium dependence of NADP-reduction, oxygen evolutionand concomitant ATP-formation was studied as a function of theage of the Cucurbita cotyledons from which the chloroplastswere isolated. Whereas NADP-reduction under alkaline assay conditionsalways exhibits a stimulation upon addition of Mg⁺⁺, measurementsin an acidic medium show an age-dependent reversal to inhibition.The data for oxygen evolution are more complex in nature, dueto participation of consecutive reactions. The Mg⁺⁺ concentrationfor optimal ATP formation decreases with the age of the cotyledonarymaterial. The results are discussed from the viewpoint of apossible control of essential photosynthetic functions in vivoby magnesium.     

Studies on Foliar Penetration: I. FACTORS CONTROLLING THE ENTRY OF 2, 4 - DICHLOROPHENOXYACETIC ACID

A technique, using leaf disks, has been developed to study thepenetration of isotopically labelled compounds into leaves underconditions where there is no appreciable change in the concentrationof the external solution and no subsequent translocation. Inthis preliminary survey, the leaves of Phaseolus vulgaris andColeus Blumei were employed to investigate the entry of 2,4-dichlorophenoxyaceticacid (2,4-D), labelled in the carboxyl group with ¹⁴C. Over3 days there is no loss of ¹⁴C to the atmosphere from treatedleaves of Phaseolus. The rate of penetration is enhanced when(a) the leaves are young, (b) the water status is lowered, (c)the temperature is raised (Q₁₀=2.3–2.8), and (d) a surface-activeagent is added to the external solution. Penetration is alsofavoured by a decrease in the pH, the relation indicating thatboth ions and molecules enter. Penetration is greater in thelight and prior illumination of the tissues positively affectsthe subsequent rate in the light, but not in the dark. In boththe light and the dark considerably more 2,4-D penetrates theabaxial surface of Phaseolus leaves. For Coleus an even greaterdifference between surfaces is found in the light but not inthe dark. For both species in the light the rates of entry intoboth surfaces are proportional to their respective stomataldensities. The simultaneous addition of indoleacetic acid tothe external solution caused more 2,4-D to enter Phaseolus leaves,but the addition of triiodobenzoic acid restricts entry. Therate of penetration remains constant over 24 hours and between0.1 and 200 mg./l. the rate is linearly related to concentration.Subsequent to entry, the 2,4-D is in a form which does not diffusefrom the tissue into buffer or exchange with unlabelled 2,4-D.Moreover, no outward movement takes place from treated tissuewhich has been frozen and thawed. These findings are discussedin relation to previous work on foliar penetration. It is concludedthat at least with Phaseolus penetration largely takes placethrough the guard cells and/or accessory cells.