Cytokinins from the tRNA of the Red Alga Porphyra perforata J. Ag.

Isopentenyladenosine and cis-zeatin riboside have been identifiedby GC-MS from the tRNA of a red alga Porphyra perforata. (Received March 12, 1991; Accepted December 7, 1991)     

突尼斯非洲跳鼠(Jaculus jaculus)和埃及跳鼠(J.orientalis)群体的等位酶多态及遗传分化(英文)

运用16种酶蛋白编码的23个遗传座位对突尼斯非洲跳鼠(Jaculus jaculus)和埃及跳鼠(J. orientalis)自然群体的遗传变异和分化进行了电泳分析。结果表明,与其他啮齿动物等哺乳动物的相关数据比较,发现这两个种群体的遗传变异水平较低。非洲跳鼠群体的观测杂合度 (H_obs) 为0.08—0.19,多态座位百分比(P)为26.2%—45.2%,每个座位的平均等位基因数(A)为1.1—1.4;埃及跳鼠的H_obs为0.10—0.15,P为29.3%—44.1%,A为1.1—1.7。两个种群体各自的遗传分化程度较低(非洲跳鼠和埃及跳鼠的F_st分别为0.0017和0.0019)。而两个种群体间的F_st为0.607（P<0.05）,表明两个种之间高度的遗传分化。本研究支持这两个种分类地位的合法性,并强调了地理因素（环境类型和生物气候阶段）对两个种遗传结构的影响。     

Abnormal Behaviour of Stomata in Barley Leaves Infected with Rhynchosporium secalis (Oudem.) J. J. Davis

Infection of barley leaves by the fungus Rhynchosporium secalisincreases the degree to which stomata open in the light. Openingis enhanced at CO₂, levels between 0 and 4000 parts/10⁶. Theability of stomata to close in the dark, as normal, is retaineduntil an advanced stage of tissue necrosis is reached. Increased stomatal opening is confined to those areas of theleaf which have been colonized by the fungus. Abnormal stomatalbehaviour results from the loss of osmotically active substancesfrom the epidermis of diseased leaves with a consequent alterationof the turgor relations between guard cells and their surroundingepidermal cells.     

Control of Germination and Seedling Morphology by Ethene: Differential Responses, Related to Habitat of Epilobium hirsutum L. and Chamerion angustifolium (L.) J. Holub

Germination rate and total germination of Epilobium hirsutumseed were increased by treatment with ethene in air (4 volumesper million) but seeds of Chamerion angustifolium were unaffected.Seventeen days from sowing the elongation of primary roots hadbeen reduced by ethene in both species but more markedly inE. hirsutum. Adventitious root formation at the base of hypocotylswas initiated by ethene in E. hirsutum but not in C. angustifolium.Root hair length was reduced by ethene rather more in E. hirsutumthan in C. angustifolium. The results are discussed in relationto the ecology and known differential waterlogging sensitivityof the two species. Epilobium hirsutum, Chamerion angustifolium, Willowherbs, ethene, germination, waterlogging, growth, roots, adventitious, ecology     

Studies in the Bangioideae III. The Life-history of Porphyra umbilicalis (L.) Kutz. var. lociniata (Lightf.) J. Ag.: A. The Conchocelis-Phase in culture

As the first step in an investigation of the life-history ofPorphyra umbilicalis (L.) Kütz. var. laciniata (Lightf.)J. Ag., spores which have originated as a result of the repeateddivision of the mother-cells have been germinated. When grownon glass their method of germination and growth agrees withthat described by previous investigators, but when germinatedon sterile shell the germ-tubes penetrate the shell and developinto growths identical with Conchocelis rosea Batters. This‘species’, therefore, is a phase in the life-historyof P. umbilicalis var. laciniata and not an autonomous species.The development of the ‘Conchocelis’-phase in cultureis described and also the formation of fertile cell-rows and‘plantlets’. Until the significance of these structuresis understood and a cytological investigation completed, therelationship of the intertidal leafy Porphyra-thallua to thefilamentous, shell-inhabiting, deep-water Conchocelis cannotbe expressed in the terms usually employed to denote the variousphases of the life-histories of algae.     

Hardarson, G. and Broughton, W. J. Maximising the use of biological nitrogen fixation in agriculture

This volume contains invited papers given at an FAO/IAEA technicalmeeting held in Rome in March 2001. Most have already been publishedin Plant and Soil 252(1), 2003 and have been reviewed, althoughthe latter is unclear for two papers, those by Cocking and byJensen et al. In that     

Cytological Investigations on Porphyra umbilicalis(L.) Kutz. var. laciniata(Lightf.) J.Ag.

1. Vegetative mitosis of Porphyra umbilicalis var. laciniatais normal, the chromosome number as seen in late prophase beingfive. Special features of this mitosis are the appearance ofseveral stained chromatin segments in early pro-phase and theformation of a crescent-shaped group of chromosomes during metaphaseand anaphase. 2. Genuine monospores have not been seen in the material investigated. 3. Both spores and spermatia arise by repeated division of amother-cell and in identical ways. Evidence is presented toshow that the first division in the mother-cell forming sporesis longitudinal. There is no evidence of reduction divisionin this division, and the chromosome number in the mother-cellis five. 4. The first division in the germinating spore is mitotic andshows five chromosomes. 5. The Conchocelis-phase is haploid throughout and produces‘fertile cell rows’ and ‘plantlets’,but spore liberation has not been observed. It is suggestedthat the ‘plantlets’ may grow out directly intothe leafy phase or may give rise to spores according to prevailingenvironmental conditions. 6. No evidence of sexual reproduction has been obtained in thepresent work and the role of the spermatium in the life-cycleis not clear. It is suggested that further work may profitablybe concerned with investigating the nature of the spermatium.     

Nucleocytoplasmic Interaction During Maturation of the Egg of the Fern Histiopteris incisa (Thunb.) J. Smith

The maturing egg of Histiopteris incisa has many features incommon with that of Pteridium, with which the species may berelated. The nuclear evaginations are however conspicuous inrespect of the extensive development of internal membrane systems,involving dilatation of the perinuclear space. In some in stancesthe inner membrane of the nuclear envelope, the proliferationof which gives rise to the dilatations, was strikingly tenuous,possibly indicating an extensive interchange between the perinuclearspace and that part of the nucleoplasm sequestered in the evaginations.The evaginations frequently contain an aggregate of electron-opaquematerial resembling structurally and in staining propertiessimilar aggregates in Pteridium, but in contrast to Pteridiumthere was no evidence that these aggregates were organized inor near the nucleolus. Histiopteris inciso (Thunb.)J. Smith, Pteridophyta, egg maturation, nucleocytoplasmic interaction, ultrastructure     

H.J. Muller's contributions to mutation research

H. J. Muller is best known for his Nobel Prize work on the induction of mutations by ionizing radiation. Geneticists are less familiar with his contributions to mutation and how he related the process of mutagenesis to the gene and distinguished gene mutations from other genetic and epigenetic events such as polyploidy, chromosome rearrangements, and position effects. The hallmark of Muller's contributions is his design of genetic stocks to solve genetic problems and allow experimentation to reveal new phenomena. In this review I relate Muller's personality to his teaching and research and present a history of Muller's ideas on mutation from his first days in Morgan's fly lab to his final thoughts on what became called “Muller's ratchet”, a term he did not get to enjoy because it was coined seven years after his death.     

Solute Regulation in the Euryhaline Marine Alga Enteromorpha prolifera (O. F. Mull) J. Ag.

Young, A. J., Collins, J. C. and Russell, G. 1987. Solute regulationin the euryhaline marine alga Enteromorpha prolifera (O. F.Mll) J. Ag.—J. exp. Bot. 38: 1298–1308. The physiological basis for salt tolerance has been studiedin the euryhaline alga Enteromorpha prolifera. Levels of inorganicions and organic (compatible) solutes have been measured. K⁺makes the major contribution towards the internal osmotic potentialof the cell, while Cl^– and, in particular, Na⁺ contentsare low. Levels of the organic solute ß-dimethylsulphonio-propionate(DMSP) are high but are fairly insensitive to changes in theexternal salinity. Levels of amino-acids, calcium, phosphateand sulphate contribute relatively little towards the internalosmotic potential of the alga. As salinity is altered there are marked changes in the tissuewater content and volume. These changes directly affect theconcentration of the osmotic solutes within the cell. In diluteseawaters there is an increase in turgor as there is littlechange in the internal solute content of the cell compared tovalues in normal sea water. Inorganic ions, in particular K⁺,and organic solutes are accumulated in concentrated seawaters,although concentrations greater than 2·00 x seawaterresult in a reduction in the internal osmotic potential of thecell, mainly through loss of K⁺. Key words: Enteromorpha, salinity, osmoregulation     

Lam, E., Fukuda, H., Greenberg, J., eds. Programmed cell death in higher plants

‘For everything there is a season . . . a timeto build up and a time to break down . . . a timeto live and a time to die.’ The quotation comes from the work of a Jewish scholar writingunder the pen name Ecclesiastes or The Preacher, several centuriesBC. His words capture the theme of the book under review here:that death is part of life and may be regulated by factors thatinclude time and season. Programmed cell death in higher plantsis a hardback reprint of a special edition of Plant MolecularBiology, devoted to scholarly     

Plant Growth Analysis: Additive and Multiplicative Components of Growth

Three techniques used to investigate whole-plant growth areplant growth analysis, yield component analysis and demographicanalysis. Each subdivides growth into morphological or physiologicalcomponents. This paper derives several relationships which definethe contributions made by components to the performance of thewhole plant. For example, the additive contributions by differentplant parts to overall unit leaf rate may be determined. Also,for multiplicative components, the relative growth rate of yieldis the sum of the relative growth rates of yield components.The relationships developed here serve to link different approachesto growth analysis, and they are illustrated using data fromgrowth studies of bean and sunflower. Plant growth analysis, yield component analysis, demographic analysis, Phaseolus vulgaris L., Helianthus annus L.     

Potential contributions of vertically migrating Rhizosolenia to nutrient cycling and new production in the open ocean

We present a numerical model of nutrient uptake and photosynthesisduring migrations of the marine diatom Rhizosolenia that wasdeveloped to estimate fluxes of carbon and nitrogen due to thesemigrations in the open ocean. The predicted specific rate ofincrease of Rhizosolenia was 0.11–0.15 day¹, whereas thetotal time for one migration cycle ranged between 3 and 5 days.Using published estimates of Rhizosolenia abundance, we estimatethat new primary production due to Rhizosolenia migrations rangesbetween 0.018 and 0.033 mmol N m^–2 day^–1. Thesevalues represent up to 17% of new production due to turbulentdiffusive fluxes of nitrate into the euphotic zone and are ofthe same order of magnitude as new production due to nitrogenfixation in tropical oceans. Large-scale contributions of Rhizosoleniato oceanic new production are limited by their relatively lowstanding crop. Variations in the formulation of losses withdepth greatly affected gross and net fluxes of carbon and nitrogen.Better characterization of losses of Rhizosolenia and improvedestimates of its abundance will help determine more accuratelythe contributions of Rhizosolenia to global biogeochemical cycles. ¹Present address: Department of Agricultural and EnvironmentalScience, The Queen's University of Belfast New forge Lane, BelfastBT95PX, UK     

Addenda Clavariacea. III

1. The following noveltiea are described, with notes on otherspecies of their genera : Aphelaria subgen. Tremellodendropsis for the A. tuberosa alliancewith subtremellaceous basidia: A. amboinensis (Lév.)comb. nov. Chaetotyphula gelatinosa sp. nov. and C. tetraspora sp. nov.from Tropical America, whence C. hyalina (Jungh.) Corner isalso recorded. Clavariadelphus junceus (Fr.) Corner is recorded from Brazil. Mucronella flava sp. nov. from Iowa. Phaeoapheloria austra1iensis gen. et sp. nov. is intermediatebetween Aphelaria and stereoid fungi. Pistillaria trispora sp. nov. from Iowa: P. tucumanensis (Speg.)comb. nov. for Typhula tucumanensis Speg. Phistillina calyx Heim is excluded as marasmioid. 2. The Physalacria-subseriea is reviewed, and the followingare described aa new: Hormomitaria albidula sp. nov. from Brazil Pseudotyhula gen. nov. from West Africa: P. ochracea sp. nov.as the typespecies : P. tenuipes (Lloyd) comb. nov. (= Mucronellatenuipes Lloyd).     

Ayala, F.J., Fitch, W.M. and Clegg, M.T. Variation and evolution in plants and microorganisms: toward a new synthesis 50 years after Stebbins

In January 2000, an impressive cohort of evolutionary biologistsconvened in Irvine, California, to celebrate the 50th anniversaryof the publication of G. Ledyard Stebbins’ Variation andevolution in plants. The brief introductory appreciation ofStebbins by Peter Raven describes Variation as ‘the mostimportant book on plant evolution of the 20th century’(p. 5). This strongly worded claim is not entirely without justification.Among the ‘New Synthesists’, Stebbins achieved forbotanists what Theodosius Dobzhansky (later to be a colleagueof Stebbins at UC Davis) had previously achieved for geneticists,Ernst Mayr for zoologists and G. G. Simpson for palaeontologists.Admittedly, the     

Somatic Hybrids of the Forage Legumes Medicago sativa L. and M. falcata L.

Protoplasts isolated from embryogenic cell suspensions of tetraploidMedicago sativa cv. Europe (2n= 4? = 32) and M. falcata (2n=4? = 32) were fused using polyethylene glycol (PEG). Heterokaryonswere isolated by micromanipulation and cultured in the presenceof nurse protoplasts from albino or embryogenic cell suspensionsof M. sativa, to give free-floating embryos and embryogeniccalli. Ninety-nine plants were regenerated from somatic embryos.Fifteen of the plants exhibited leaf abnormalities and did notsurvive transfer from culture to the glasshouse. The remainingphenotypically normal plants were established ex vitro and floweredat maturity. Morphological and biochemical analyses confirmedthat 12 of the phenotypically normal plants were somatic hybrids.Morphological characteristics of the hybrids, including plantstature, internode length, leaf size, flower colour, and podshape, were intermediate compared with those of the purple floweredM. sativa and yellow flowered M. falcata parents. Flowers ofthe hybrids were yellow traced with purple-blue veins. Isoenzymebanding patterns for esterase showed bands additional to thoseof M. sativa and M. falcata. The chromosome complements of individualhybrids varied from (2n= 4? = 32) to 58.     

Floral biology, pollination and fertilisation in temperate zone fruit species and grape. * Kozma P, Nyeki J, Soltesz M, Szabo Z. 2003. * Budapest: Akademiai Kiado. $98 (hardback).621 pp.

The primary focus of this book is to discuss the floral biologyof the fruit crops including apple, grape, Ribes, Rubus, strawberry,the stone fruits and several