Further studies on the effect of aldosterone on electrical resistance of toad bladder

The fall in transepithelial electrical resistance which accompanies aldosterone stimulation of short-circuit current ($\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$) in toad urinary bladder has been studied further to evaluate the possible causal role of this response in hormonal stimulation of Na⁺ transport. A steady-state change in tissue conductance was found to depend upon both the simultaneous stimulation of transport by the steroid and the metabolic state of the tissue. Changes in metabolic state alone did not alter resistance. A sustained increase in Na⁺ transport, dependent on pretreatment with aldosterone and elicited by addition of glucose, could be obtained without a sustained decrease in resistance. Amiloride, an inhibitor of Na⁺ uptake, produced changes in $\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$ that were linearly correlated with its effects on tissue conductance. On the basis of the $\text{conductance}\text{-I}{}_{\mathrm{<mtext>sc</mtext>}}$ relationship with amiloride, the $\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$ response to aldosterone was about two-fold higher than would be predicted from its effects on conductance alone. Despite the apparent lack of a simple quantitative dependence of the change in $\text{I}{}_{\mathrm{<mtext>sc</mtext>}}$ on the change in conductance when the response is fully developed, the results suggest that conductance changes may mediate the initial or early stage of the response.     

自分泌生长因子对早期胚胎体外发育的影响(简报)

生长因子(Growth Factors,GFs)对于调节哺乳动物胚胎的早期发育和分化起着重要作用,这些GFs存在于雌性生殖道,也可由胚胎自身合成。正是由于这种自分泌GFs的存在,使我们可以通过改变胚胎培养密度或添加外源性GFs来定性或定量研究GFs对胚胎发育和分化的影响,对于了解GFs在分子水平上的作用途径和机制有着重要的意义。     

关于兰科若干亚族的分类问题

本文对兰科中9个亚族的分类问题进行了探讨,并发表了5个新亚族：宽距兰亚族Subtrib Yoaniinae、肉药兰亚族Subtrib．Sterosandrinae、紫茎兰亚族Subtrib．Risleyinae、坛花兰亚族Subtrib．A- canthephippiinae和筒瓣兰亚族Subtrib．Anthegoiinae。     

The effect of estradiol on isolated rat uterine motility and on prostaglandin generation

The motility of isolated uterine horns as well as the generation of PGE and PGF like material by the uterus from estrus and spayed rats, treated or untreated with 17-beta estradicl, were studied. Following 40 minutes of mounting the spontaneous motility of uteri from estrus rats had a lower magnitude than that from spayed ones. The amount of PGF-like material was similar in both groups whereas the first one liberated less PGE-like substance. In spayed animals treated with 1 μg of 17-beta estradiol the decay of spontaneous contractile force was higher than that observed in untreated rats, and similar to that displayed by uteri from estrus. Less PGE-like material was liberated in comparison with spayed animals and a tendency to produce higher quantity of PGF-like compounds was observed, although the level was not significantly different. With 50 μg of 17-beta estradiol the spontaneous reduction of contractile activity was higher than in spayed animals and than in those treated with 1 μg. The amount of PGF-like material liberated was higher than in spayed rats and less PGE-like substance was generated comparing with spayed and 1 μg-treated animals. These findings show that estradiol decreases the release of PGE-like compound. It would also appear that this may have some relationship with the levels of spontaneous contractile activity of the isolated rat uterus.     

The effect of acid pH and citrate on the release and exchange of iron on rat transferrin

The effect of acid pH and citrate on the exchange of iron between binding sites of rat transferrin has been studied. In the absence of citrate, diferric transferrin shows stepwise loss of iron atoms with the first atom of iron released at approximately pH 5.2. Citrate at physiologic concentrations (1 · 10^?3 M) or greater allows random iron removal at pH 6.5 or less. Iron dissociation from monoferric transferrin at acid pH, with or without citrate, is a random process. At pH 7.4, randomization of iron on transferrin takes from 3 to 6 h in the presence of millimolar concentrations of citrate. We conclude that at acid pH and in the presence of citrate concentrations likely to occur in vivo in the rat there is little scrambling of iron bound to transferrin.     

中国野牡丹科植物补充订正

报道了中国野牡丹科Melastomataceae尖子木属Oxyspora一新记录种——柑叶尖子木O. curtisii King,并绘制了特征线条图。另基于花序和花特征的不同, 将翅茎异形木Allomorphia eupteroton Guillaumin var. teretipetiolata C. Y. Wu ＆ C. Chen由变种提升为种, 归入尖子木属, 即翅茎尖子木Oxyspora teretipetiolata （C. Y. Wu ＆ C. Chen） W. H. Chen ＆ Y. M. Shui, 并补充描述了其花部特征。通过扫描电镜观察了它们的花粉和种子形态, 为分类处理提供了佐证。     

米仓山自然保护区水青冈属(Fagus)资源调查报告

使用常规野外种群调查方法调查了米仓山自然保护区中水青冈属(Fagus)林木资源贮量。结果表明保护区有水青冈属分布的林分面积达7 064.8 hm2,占保护区有林地面积40%多;水青冈属活立木总蓄积814 600 m3,是国内目前水青冈属植物保存面积最大的地区。保护区中现有水青冈(F.longipetiolata),亮叶水青冈(F.lucida),台湾水青冈(F.hayatae),米心水青冈(F.engleriana)4个种,而在这4种水青冈属植物中,又以台湾水青冈的发现最为重要,有台湾水青冈分布的林分面积达5 923.3 hm2,以台湾水青冈为优势的林分面积2 511 hm2,台湾水青冈活立木蓄积317 000 m3。     

The effects of prostaglandins on aqueous humor dynamics

PGE₂, applied topically to the cornea of enucleated, arterially perfused cat eyes, produced an increase in the rate of aqueous humor (AH) production but only minimal changes in eye pressure, as observed in vivo. In contrast, PGE₁, E₂ and F_2α, administered intra-arterially, induced no change in AH production or arterial perfusate flow rate. In eyes in which the AH inflow rate had been accelerated by prior administration of acetylcholine plus eserine, PGE₁, E₂ and F_2α caused a lowering of the inflow rate as well as vascular dilatation.     

The effect of intrauterine infusions of prostaglandin E2 on luteal function in nonpregnant gilts

Two trials were conducted to study the effects of intrauterine infusions of prostaglandin E(2) (PGE(2)) on luteal function in nonpregnant gilts. Cannulae were surgically implanted on day 9 postestrus into the lumen of each horn with a cephalic vein cannula inserted for collection of peripheral blood. Intrauterine infusions of 0, 25, 75 or 200 mug of PGE(2) were initiated at 0900 h on day 12 and administered thereafter every 12 hr until estrus or day 22 in the first trial. The second trial protocol included an increase in the dose of PGE(2) administered as well as the frequency of infusion. Infusion of 0, 200, 300 or 400 mug PGE(2) was begun at 0300 h on day 12 and continued every 6 hr until estrus or day 22. Cephalic plasma samples for progesterone analysis were collected every six hours from 0300 h on day 11 to 2100 h on day 26 in both trials. In Trial 1 mean plasma progesterone concentrations for all treatments were not different (P>0.05) from the controls on any given day of the estrous cycle. Interestrous interval was unaffected by intrauterine infusion of PGE(2). The mean plasma progesterone concentrations for all treatments were not different (P>0.05) from the controls on days 11-18 of the estrous cycle in Trial 2. However, plasma progesterone concentrations for the 200-mug and 300-mug PGE(2) groups appeared to be greater than the controls on days 14 and 15, indicating a possible delay in the decline of progesterone for these groups. The mean plasma progesterone concentrations for the treatment groups were lower (P<0.05) than the controls on days 20-26 of the cycle. treatment cycle length did not differ (P>0.05) from previous cycle length; thus treatment with PGE(2) had no effect on interestrous interval. PGE(2) may have retarded the decline of progesterone secretion by the corpus luteum in some cases, but at these dosages and frequencies of administration PGE(2) was ineffective in prolonging luteal maintenance.     

两种过路黄的核型研究

对国产报春花科珍珠菜属植物过路黄和疏节过路黄的核型进行了首次报道。过路黄染色体数目为２ｎ＝２４,核型公式为２ｎ＝２４＝２ｍ＋４ｓｍ＋６ｓｔ＋１２ｔ,核型类型“３Ａ”;疏节过路黄染色体数目为２ｎ＝２２,核型公式为２ｎ＝２２＝４ｍ＋６ｓｍ＋１０ｔ,核型类型“３Ａ”。     

兰属腋花组若干种类的研究

对新种丽花兰Cymbidium concinnum Z. J. Liu &; S. C. Chen和新变种龙州兰C. eburneum var. longzhouense Z. J. Liu &; S. C. Chen进行了描述和绘图; 丽花兰与大雪兰C. mastersii Griff. ex Lindl.有亲缘关系, 区别点在于新种叶片先端不分裂, 花序具18-22朵花, 唇瓣中裂片上有一个V型的紫红色斑块; 龙州兰(变种)与独占春(原变种)的主要区别在于唇瓣中裂片上和侧裂片顶部有较密的紫红色斑。对象牙白C. maguanense的分类问题进行了讨论, 并为其指定了新模式; 还为腋花组sect. Eburnea国产种类提供一个检索表。     

两种过路黄的核型研究

对国产报春花科（Ｐｒｉｍｕｌａｃｅａｅ）珍珠菜属（Ｌｙｓｉｍａｃｈｉａ）植物过路黄（Ｌ.ｃｈｒｉｓｔｉｎａｅＨａｎｃｅ）和疏节过路黄（Ｌ.ｒｅｍｏｔａＰｅｔｉｔｍ）的核型进行了首次报道。过路黄染色体数目为２ｎ＝２４,核型公式为２ｎ＝２４＝２ｍ＋４ｓｍ＋６ｓｔ＋１２ｔ,核型类型“３Ａ”;疏节过路黄染色体数目为２ｎ＝２２,核型公式为２ｎ＝２２＝４ｍ＋６ｓｍ＋２ｓｔ＋１０ｔ,核型类型“３Ａ”。     

兰属中若干分类群的订正

基于对许多活植物的观察,对兰科中兰属的若干种类进行了分类学考订,结果承认菅草兰Cymbidium　tortisepalum与峨眉春蕙C. omeiense为独立的种,将春剑C. longibracteatum移至菅草兰之下作为变种,送春C. szechuanicum移至莎叶兰C. cyperifolium之下作为变种。由于春剑、峨眉春蕙和送春的模式标本及引证标本已在30多年前全部丢失,本文指定了新模式。     

Deuterium oxide effects on excitation-contraction coupling of skeletal muscle

²H₂O (99.8%) Ringer's solution greatly reduces the twitch and tetanus of frog sartorius muscle and, as specially shown here, slows the onset features of the mechanical output of the twitch by: (a) increasing the time (L_R) from stimulus to start of latency relaxation; (b) slowing the developmet of the latency relaxation, and (c) greatly decreasing the rate of onset of tension development. These changes reflect effects of ²H₂O on excitation-contraction coupling and they represent the critical direct effects of ²H₂O on muscle since it does not depress either the action potential or the intrinsic myofibrillar contractility. The increase in L_R is attributed to slowed inward electrical propagation in the T-tubule. But the critical effect of ²H₂O on frog muscle is to greatly depress mobilization of activator Ca²⁺. The depression of the Ca²⁺ mobilization and of its effects on the activation of contraction evidently result from (a) a lowered rate of release of Ca²⁺ from the sarcoplasmic reticulum, as indicated by the slowed development of the latency relaxation, (b) a decreased amount of Ca²⁺ released in a twitch, and (c) a reduced speed of diffusion of the Ca²⁺ to the contractile filaments. The depressed mobilization of Ca²⁺ is apparently the essential cause of ²H₂O's general depression of twitch and tetanus output.     

The influence of within-stream disturbance on dissolved nutrient levels during spates

In rivers, variations in concentrations of many dissolved nutrients occur during spates. Increases are usually attributed to concentrated point or non-point inputs, and decreases to dilution associated with rainfall. Increased discharge disturbs sediments and benthic communities, but the effects of such disturbance on nutrient levels are difficult to isolate. Measurements of nutrient levels over three artificial spates revealed that substantial variations in dissolved organic carbon, dissolved phosphate, silicate, nitrate, and potassium levels could result from increased discharge in the absence of allochthonous inputs. Variations were closely related to peaks in suspended solids concentration or water height. Increases in biochemical oxygen demand and suspended bacteria also occurred. Variations in phosphate and silicate could be accounted for by a balance between release of ‘sediment interstitial water’ and exchange processes involving suspended and freshly exposed sediment. An increase in nitrate, during one spate, was probably due to a reduction in the effect of benthic denitrification. Small peaks in dissolved organic matter concentration were detected over each spate. We propose that within-stream disturbance is a factor which may contribute to variations in dissolved nutrient concentration during the rising hydrograph in natural spates.     

Effects of endotoxin on immunity in aging mice

In vivo administration of bacterial lipopolysaccharides (LPS) to young adult mice causes a dose-dependent depression of antibody formation. In contrast, LPS produced no effects on the responses of older mice and these animals appeared to be refractory to the depressive effects observed in the young adults. When young adults were pretreated with endotoxin their baseline control responses were also severely depressed and the LPS response profile resembled that of the normal 9-month-old animals. These results suggest that endotoxin effects may contribute to the genesis of immune abnormalities in the aged.