Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

抗凋亡因子Survivin研究进展

Survivin是在肿瘤组织及胚胎中发现的一类细胞因子,它是IAPs(inhibitorsofapoptosisprotein)家族的成员之一,具有其独特的分子结构和组织表达特异性,在细胞中参与细胞周期的调控,主要在细胞周期的G2/M期通过抑制caspase-3及caspase-7的活性发挥作用.Survivin在细胞中的活性可能受p53的调节.Survivin也是胚胎发育早期过程中调节细胞分裂分化的一类重要的因子.对Survivin的研究对于肿瘤治疗的研究及揭示胚胎早期的发育机制有重要的意义.     

Veterinary clinical application of GnRH--questions of efficacy

The efficacy of GnRH treatments are reviewed in relation to prevention of embryo mortality, control of follicle development in synchronization programmes using PG as luteolysin, induction of ovulation in post-partum anoestrus and in bovine cystic ovarian disease. It is suggested that in cattle that GnRH is effective in increasing pregnancy rates when given either at the time of insemination (first or repeat) or between days 11 and 14 after insemination. Evidence is also presented for positive effects on pregnancy rates in sheep, mares and sows. Use of GnRH as an integral part of synchronising regimens where it is given 7 days before PG and then again 48-60 h after PG appears to be effective in increasing the synchrony of ovulation in controlled breeding programmes. The main synchronizing effect seems to reside in the second GnRH injection whereas the importance of the first is in prolonging the luteal phase in those cows treated late in the cycle. The published work on the potential use of GnRH to induce ovulation in anovulatory cattle is reviewed. Neither bolus dose injections, pulsatile, continuous infusion, nor controlled release formulations of GnRH, have yet proved effective in inducing fertile ovulations in a predictable or consistent manner. It is suggested that this is due to the variability of follicular status when treatment is initiated. GnRH is commonly used in the treatment of bovine cystic ovarian disease. However, although stimulating ovulation/luteinisation of a new follicle and luteinisation of the cyst, fertility of treated cattle remains very poor and it is suggested that a better understanding of the disease is needed before more effective treatments can be developed.     

An Analysis of the Response of Young Barley Seedlings to Time of Application of Nitrogen

The reasons for the sensitivity of young barley seedlings totime of application of nitrogen have been examined. It is shownthat the transfer of nitrogenous reserves from endosperm toembryo which begins at about 36 h from planting proceeds ata faster relative rate than that of dry matter as a whole. Inconsequence embryo and endosperm nitrogen contents become temporarilysimilar some 24–36 h earlier than is the case for dryweights. Addition of nitrate on day 2 does not affect ratesof transfer of endosperm reserves but leads to a significantlyhigher nitrogen content in the embryo of treated plants, particularlyin the shoots. This additional nitrogen is present as nitrateup to around day 5 when reduction of accumulated nitrate commencesin the first leaf in significant amounts. For plants up to 14 days old delay in application of nitrateleads to a lowering of total nitrogen level which is proportionalto the delay in treatment. This is so for all parts of the plantexcept the first leaf for which the evidence indicates thatlevels of total and organic nitrogen and of accumulated nitrateare much lower when treatment is made late. It is argued thatnitrate accumulation by the leaf becomes progressively lessas it reaches full expansion, but irrespective of time of nitrateapplication about 95 per cent of the additional nitrogen presentin the leaf is in organic form Significant increases in organic nitrogen are found from day6 for plants supplied with nitrate up to day 4; for plants suppliedon day 6, or day 8nitrateand nitrate reductase activity in leafextracts are found within 6 h of treatment. Peak levels of nitratereductase activity are found for all treatments around days8–10 when the first leaf is fully expanded and when photosyntheticactivity is maximal. However, late supply of nitrate leads toa lower level of enzyme activity. Nitrate reduction in the rootsystem is undetectably low, and it is concluded that a substantialamount of carbon translocated from leaf to roots is in the formof nitrogenous compounds. The effects of time of application are also found when ammoniumnitrogen is substituted for nitrate indicating that the responseis independent of effects on the nitrate reducing system inthe leaf. Some inhibition of growth, particularly of the roots,is found due to ammonium toxicity. Why plants supplied early with nitrate show superior growthand enhanced photosynthetic activity in the first leaves isexplained in terms of treatment alleviating the restrictiveeffects of declining endosperm reserves. This is only possibleif nitrogen is supplied while the first leaf is expanding andable to accumulateand utilise the available nitrogen. Late supplyis associated with failure to use the nitrogen provided leadingto a lower protein level in the leaf; this can be correlatedwith the smaller size of leaf and the lower rates of carbonfixation occurring there.     

Quantitative relationships of specific adsorption of colicins

The decrease in the number of sensitive bacteria in the presence of an excess of colicin is proportionate to their initial concentration; the proportion of surviving cells is not entirely constant, but is to some extent directly correlated to the initial cell concentration. The percentage of surviving cells is in inverse proportion to the colicin titre. The amount of nonadsorbed colicin is directly proportionate to the initial colicin titre. In the presence of an excessive number of sensitive bacteria in the suspension, the free colicin titre is much more lowered than in the suspension of resistant bacteria, the decrease being directly correlated to the number of bacteria in the suspension. Resistant—and even heterologous— bacteria can also adsorb large amounts of colicin nonspecifically, however. The experiments provide evidence in support of the concept of the lethal unit of colicin the course of adsorption of which is apparently different from that of phage.     

Backward simulation of ancestors of sampled individuals

If the population is large and the sampling mechanism is random, the coalescent is commonly used to model the haplotypes in the sample. Ordered genotypes can then be formed by random matching of the derived haplotypes. However, this approach is not realistic when (1) there is departure from random mating (e.g., dominant individuals in breeding populations or monogamy in humans), or (2) the population is small and/or the individuals in the sample are ascertained by applying some particular non-random sampling scheme, as is usually the case when considering the statistical modeling and analysis of pedigree data. For such situations, we present here a data generation method where an ancestral graph with non-overlapping generations is first generated backwards in time, using ideas from coalescent theory. Alleles are randomly assigned to the founders, and subsequently the gene flow over the entire genome is simulated forwards in time by dropping alleles down the graph according to recombination model without interference. The parameters controlling the mating behavior of generated individuals in the graph (degree of monogamy) can be tuned in order to match a particular demographic situation, without restriction to simple random mating.The performance of the approach is illustrated with a simulation example. The software (written in C-language) is freely available for research purposes at http://www.rni.helsinki.fi/∼dag/.     

Hormonal regulation of the process of ovum implantation

Literature is reviewed in which the role of hormones, particularly progesterone and estrogens, and their interaction in the development of contraceptive changes in the uterus and in the regulation of the process of ovicellular implantation is emphasized. Emphasis is placed on hormonal insufficiency in the emergence of experimental and natural blockage of implantation and of asynchronic implantation. It is shown that ovicellular implantation is not automatic or a process divorced from its external environment. The role of several exogenous irritations in the blockade of implantation is examined.     

灰胸薮鹛消化系统形态的初步研究

对灰胸薮鹛（Liocichla omeiensis）消化系统的形态学作了初步观察,结果表明,灰胸薮鹛舌前端有刺毛状结构,后端有一排尖端后指的栉状突,且中间小两边大;雄鸟在舌前端正中央还有一“v”形的凹缺,深约2．5mm;雌鸟食道颈段长为13．2mm,雄鸟为17．5mm;嗉囊雌鸟长7．5mm,雄鸟长8．4mm;食道胸段雌鸟长15．5mm,雄鸟长14．7mm;肌胃发达,具角质膜,腺胃乳突短而小;肠道长与体长基本相等,小肠较发达,雌鸟长153．7mm,占肠道总长92．6％,雄鸟为133mm和95％,具有双侧盲肠,占肠道总长的3．3％,大肠短,雌鸟仅占肠道7．5％,雄鸟仅占4．75％;肝为体内最大的消化腺,分左右两叶;胰位于十二指肠袢内,细长形,分三小叶。     

Regulation of the biosynthesis of steroidogenic enzymes

Recombinant DNA technology can permit study of the regulation of steroid hydroxylase gene expression at three levels. The first of these is cAMP-regulated gene expression. In the adrenal, ACTH, via cAMP, increases the expression of the genes for all of the cytochrome P-450 species involved in the steroid biosynthetic pathway, as well as the iron-sulfur protein, adrenodoxin. This action of cAMP is inhibited by cycloheximide, suggestive of the involvement of a regulatory protein factor in mediating this action of cAMP. The second level is tissue-specific regulation of steroid hydroxylase gene expression. An example of this which we have studied is the expression of cholesterol side-chain cleavage cytochrome P-450 (P-450sec) and 17 alpha-hydroxylase cytochrome P-450 (P-450(17) alpha) in the bovine ovary. P-450sec is expressed at high levels in the corpus luteum but at low levels in follicles, whereas P-450(17)alpha is expressed in follicles, but is undetectable in the corpus luteum. The third level is fetal imprinting. A number of the cytochrome P-450 species involving in the steroidogenic pathway are expressed in the fetal adrenal at a time when exposure of the gland to ACTH is very low, suggestive that factor(s) other than pituitary ACTH mediate this expression in fetal life.     

Analysis of morphogenetic mutants of hydra

Summary A mutant ofHydra attenuata is analysed, theaberrant, which is distinct from the wild type in having a smaller head with fewer tentacles and only half the number of head-specific cells. The rate of head and foot regeneration and the doubling time are slower inaberrants than in normal hydra.The lower head-forming potential is paralleled by a reduced concentration of head-specific morphogens: compared to the wild type, in theaberrant the concentration of head activator is reduced to 70% in the head and to 50% in the body, the concentration of head inhibitor is reduced to 50% in the head and to 80% in the body. Theaberrant is more sensitive (3 times) to added head activator and less sensitive (>5 times) to added head inhibitor than the wild type.The slower rate of foot regeneration is paralleled by a lower content of foot-specific morphogens: compared to the wild type, in theaberrant the foot activator is reduced to 40% and the foot inhibitor to 70%.     

Estimation of the dissociation constants of enzyme-substrate complexes from steady-state measurements. Interpretation of pH-independence of Km.

If the Michaelis constant of an enzyme-catalysed reaction is independent of pH under conditions where the catalytic constant varies with pH, it is equal to the thermodynamic dissociation constant of the enzyme-substrate complex. This is true for realistic mechanisms in which binding and catalytic steps, are clearly distinguished, as well as for the simpler mechanisms that have been considered previously. It is also true for a mechanism in which a bell-shaped pH profile for the catalytic constant results from a change of rate-limiting step with pH. The relaxation time for ionization of a typical group in unbuffered solutions at 25 degrees C is of the order of 0.1 ms at the longest, and is much shorter in buffered solutions. Thus ionizations in almost all enzyme mechanisms can properly be treated as equilibria, provided that ionization is not accompanied by a slow, compulsory change in conformation.     

The pathway of biosynthesis of abscisic acid in vascular plants: a review of the present state of knowledge of ABA biosynthesis.

The pathway of biosynthesis of abscisic acid (ABA) can be considered to comprise three stages: (i) early reactions in which small phosphorylated intermediates are assembled as precursors of (ii) intermediate reactions which begin with the formation of the uncyclized C40 carotenoid phytoene and end with the cleavage of 9'-cis-neoxanthin (iii) to form xanthoxal, the C15 skeleton of ABA. The final phase comprising C15 intermediates is not yet completely defined, but the evidence suggests that xanthoxal is first oxidized to xanthoxic acid by a molybdenum-containing aldehyde oxidase and this is defective in the aba3 mutant of Arabidopsis and present in a 1-fold acetone precipitate of bean leaf proteins. This oxidation precludes the involvement of AB-aldehyde as an intermediate. The oxidation of the 4'-hydroxyl group to the ketone and the isomerization of the 1',2'-epoxy group to the 1'-hydroxy-2'-ene may be brought about by one enzyme which is defective in the aba2 mutant and is present in the 3-fold acetone fraction of bean leaves. Isopentenyl diphosphate (IPP) is now known to be derived by the pyruvate-triose (Methyl Erythritol Phosphate, MEP) pathway in chloroplasts. (14C)IPP is incorporated into ABA by washed, intact chloroplasts of spinach leaves, but (14C)mevalonate is not, consequently, all three phases of biosynthesis of ABA occur within chloroplasts. The incorporation of labelled mevalonate into ABA by avocado fruit and orange peel is interpreted as uptake of IPP made in the cytoplasm, where it is the normal precursor of sterols, and incorporated into carotenoids after uptake by a carrier in the chloroplast envelope. An alternative bypass pathway becomes more important in aldehyde oxidase mutants, which may explain why so many wilty mutants have been found with this defect. The C-1 alcohol group is oxidized, possibly by a mono-oxygenase, to give the C-1 carboxyl of ABA. The 2-cis double bond of ABA is essential for its biological activity but it is not known how the relevant trans bond in neoxanthin is isomerized.     

The epidemiology of morbidity of schistosomiasis

The epidemiology of schistosomiasis is changing because treatment of chronically infected individuals is often followed by reinfection. As a major goal of schistosomiasis control is the reduction of morbidity, direct assessment of disease is essential because infection status is a relatively poor indication of morbidity. Introduction of ultrasonography to the study of schistosomiasis and the increased appreciation of the effects of schistosomiasis on growth and development in children have greatly enhanced our understanding of schistosome-induced morbidity in endemic communities. Peter Wiest here reviews the changes in the assessment of schistosomiasis-induced morbidity.     

Evaluation of the Results of Surgery to Correct Congenital Ptosis of the Upper Eyelid

Experience in the surgical correction of congenital ptosis in 203 children operated on at The Hospital for Sick Children, Toronto, demonstrated that because of the different types and complicated nature of ptosis the choice of operation in each case is most important. Occasionally ptosis is associated with other anomalies such as blepharophimosis, epicanthus, and the jawwinking syndrome, which further complicate its repair. Although the results in complicated cases are not perfect, these children should be given the benefit of surgery, since almost all can be greatly improved. The best time for surgery is after three years of age but before the child starts school. If adequate levator action is present, shortening this muscle is the operation of choice. If levator function is poor, the lid is elevated by the frontalis muscle and fascia lata. Achievement of symmetry in the position of the lid and width of the palpebral fissure is the key to real success in ptosis surgery.     

Density of the neurovegetative innervation of the uterus of rats

Using the Karnovsky and Roots modified by E1 Badawi and Schenk's technic for the cholinergic innervation and with the method of Lindvall and Bj?rklund modified by de la Torre and Surgeon for the adrenergic ones, we demonstrate the innervation of each tissular layer, in cervix, corpus and cornua of the uterus of the she-rat in pro-oestrus state. A statistic evaluation is established for the different areas. The density of cholinergic innervation is richer than the adrenergic one. The number of cholinergic fibers is maximum in the cervix. It decreases in corpus and cornua especially in the mucosal and sub-mucosal layers. The density of the muscular nervous network is predominant in the corpus versus the cervix. The number of adrenergic nerves is maximum in corpus it diminishes in the cervix and the cornua. In each region, the muscular adrenergic network domines over the other tissular layers. We confirm statistically morphometric non parametric observations of these other authors.     

The Influence of Temperature on the Effect of Bacteriostatic Concentrations of Phenol Against Escherichia coli

S ummary . During early exponential growth of Escherichia coli in the absence of phenol there is a natural death rate at 20, 30, and 44° but at the optimum temperature around 37° there is little if any significant death. The influence of a rise in temperature from 20 to 44° is to decrease the generation time and at 44° the lower generation time compensates for a reduced generation index. The main effect of sub-bacteriostatic concentrations of phenol is to increase the generation time but at 30, 37 and 44° there is a significant reduction in the generation index at the higher concentrations resulting in a dynamic bacteriostasis. At 20° bacteriostasis is due mainly to a large generation time but there is a little growth and so bacteriostasis is essentially dynamic. There is also evidence to suggest that the effect of a particular concentration of phenol on the generation index is not merely influenced by the temperature but by the generation time under the particular set of conditions. If phenol is added to rapidly growing cultures of E. coli the effect of a rise in temperature is to reduce the concentration required for bacteriostasis but if it is added during the lag phase there is a maximum in the bacteriostatic concentration between 20 and 37°.     

Induction of the Acrosome Reaction of Sea Urchin Spermatozoa by Means of Urea

Urea is an effective reagent for inducing the acrosome reaction of spermatozoa in sea urchins. Urea-treated spermatozoa are capable of fertilizing eggs in Ca-deficient sea water. The pH of the urea solution is an important factor affecting the induction of the acrosome reaction. The reaction occurs at a high percentage in urea Solution at pH's higher than 7.8, while the reaction is almost completely suppressed at pH 7.2. Ca⁺⁺ is also an important factor for the induction of the reaction, although the minimum concentration required is very low.
The acrosomal filament formed in urea solution is similar in shape to that formed in egg-water, when fixed after 10 seconds' urea-treatment. The acrosome granule material is found around the basal portion of the acrosomal filament.     

Database of sentences of Croatian language

The aim of this paper is to investigate morphological and syntactical levels of sentences of Croatian Language. Morphological grammatical level is represented by 16 categories and 47 features with theirs value. Syntactical level is represented with constituent structure trees of sentences. Database has 1001 grammatical sentences of Croatian literature. Database of sentences is the result of theoretical research in computational linguistics. This study extends the analysis of the linguistic data in anthropology in Croatian. Access to database is through the Internet on the address: http://infoz.ffzg.hr/tepes.     

液体培养基条件下乌毛蕨配子体发育的研究

在液体培养基条件下对中国产乌毛蕨(Blechnum orientaleL.)配子体发育进行了观察。结果表明:乌毛蕨的孢子为两面体型,两侧对称,极面观为椭圆形,赤道面观为半圆形或豆形,周壁具脊状褶皱;孢子萌发为书带蕨型;原叶体发育为三叉蕨型,成熟原叶体为对称的心脏形。经比较分析,蕨类植物孢子繁殖时采用混合土培养较适宜;液体培养基和混合土在研究蕨类植物配子体发育时同样具有可行性。孢子形态和配子体发育的观察结果表明,乌毛蕨是蕨类植物中较进化的种类;乌毛蕨科与鳞毛蕨科亲缘关系较近。     

Investigation of the level of genetical safety of urban population

As it is universally recognized, the population is a sound criteria of the environment quality. The most reliable method to evaluate genetic processes in a population under the condition of the environmental pollution is genetic monitoring, a survey of dynamic parameters of genetic load. An evaluation of genetical safety of an urbanized area of a city is represented in this article. The parameters of genetic load like congenital malformations and multifactorial diseases have been used in the models of monitoring. The analysis and comparison of disease frequencies in Kharkiv Dzerzhinsky District, in other European populations and in regional rural districts with various levels of production have been made.