bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES ON THE INTRA‐CELLULAR LOCALIZATION OF THE HEXOSE MONOPHOSPHATE PATHWAY IN USTILAGO MAYDIS
Authors: McKinsey Richard D.
Published: January 2018

The relation of the operation of the hexose monophosphate pathway to cellular particles of Ustilago maydis was investigated. Results obtained indicate that extracts from which all microscopically visible particles had been removed could oxidize glucose through the hexose monophosphate pathway. By tracer techniques it was found that all, or almost all, released CO2 was obtained from the number 1 carbon of glucose. Spectrophotometric studies demonstrated the presence of glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconic acid dehydrogenase. Radiochromatographic studies indicated the formation by mitochondria‐free extracts of glucose‐6‐phosphate, 6‐phosphogluconic acid and possibly ribose‐5‐phosphate. These extracts could metabolize glucose and 6‐phosphogluconate with oxygen uptake. It was concluded that in this fungus the energy‐producing and decarboxylating steps of the hexose monophosphate pathway could operate with the uptake of O2 in the absence of mitochondria. The dehydrogenases present in the supernatant solutions can cooperate with an electron transfer sequence to O2 in the supernatant. Presumptive evidence for the presence and action of glucokinase and phosphoriboisomerase was provided by the results of the aforementioned experiments. Isolated mitochondria were found by spectrophotometric means to contain cytochrome c oxidase and DPNH oxidase. Mitochondria were capable of using succinate as a substrate with oxygen uptake. Under some conditions isolated mitochondria showed a high endogenous rate of metabolism which could be halted by KCN. The use of isotopic tracer techniques indicated that extracts containing mitochondria could carry out the decarboxylation of citric acid via the tricarboxylic acid cycle.
EVIDENCE FOR THE PECTIC NATURE OF THE MIDDLE LAMELLA OF POTATO TUBER CELL WALLS BASED ON CHROMATOGRAPHY OF MACERATING ENZYMES
Authors: McClendon John H.
Published: January 2018

Chromatography of fungal enzyme mixtures on cellulose phosphate columns using pH‐gradient clution was followed by analysis of the separated fractions for polygalacturonase, maceration of killed potato tuber slices, and, in some instances, for pectin transeliminase and cellulase. The peaks of maceration activity coincided with those of endo‐polygalacturonase and pectin transeliminase. The latter was confirmed by further separation on DEAE‐cellulose. Exo‐polygalacturonase appeared not to macerate, and no indication was obtained of maceration by several other polysaccharases known to be present, although they might be demonstrable in the absence of polygalacturonase. These results strongly suggest that the middle lamella of the cell walls of this tissue consist essentially of pectinate (partly esterified polygalacturonate).
SOME EFFECTS OF GAMMA IRRADIATION ON SEEDS AND RHIZOMES OF MUSA
Authors: Stotzky G. , Cox E. A. , Wornick R. C. , Badger A. M.
Published: January 2018

The tolerance of Musa balbisiana Colla seeds to gamma irradiation was found to be considerably greater than that of rhizomes of the parthenocarpic variety ‘Gros Michel': e.g., 11.8 krad reduced the germination of rhizomes 92% and of seeds approximately 15%. Intact seeds exposed to doses higher than 48 krad did not germinate in non‐sterile soil, but, when scarified and cultured axenically after irradiation, seeds which received doses as high as 70 krad germinated. Embryos excised from seeds exposed to doses as high as 285 krad formed callus, indicating that not all metabolic processes were inhibited by these extremely high doses. There was considerable variation in radiation tolerance between seed lots which was not related to their age, moisture content, or pre‐exposure viability. Germination of intact seeds appeared to be stimulated by doses of 3 or 9 krad. No lasting differences attributable to the level of irradiation were apparent in the development of seedlings derived from either intact or scarified seeds nor of plantlets derived from excised embryos. Conversely, there was a significant reduction, proportional to irradiation dose, in the growth of plants developing from rhizomes, emphasizing the greater radiation sensitivity of the vegetative propagule. The radiation tolerance of seed‐borne microorganisms was considerably higher than that of the plant materials, indicating that gamma irradiation is not effective as a means of obtaining pathogen‐free rhizomes or surface‐sterilizing seeds of M. balbisiana.
CHROMOSOMES OF THE CHARACEAE OF THE WOODS HOLE (MASSACHUSETTS) REGION
Authors: Tindall Donald R. , Sawa Takashi
Published: January 2018

Cytological observations were made on material from 35 collections taken from 21 populations representing 10 species and 2 genera. Haploid chromosome numbers observed in Nitella were 9, 12, 18, 18, 18, and 18 + 36. Those observed in Chara were 14, 28, 28, and 42. Several data indicate that Nitella transilis is an established polyploid of N. tenuissima. The evaluation of chromosome numbers in respect to hybridization, polyploidy, and sexuality in haplobiontic plants is discussed.
A FLORA FROM THE CHESTER SERIES (UPPER MISSISSIPPIAN) OF SOUTHERN ILLINOIS
Authors: Lacey William S. , Eggert Donald A.
Published: January 2018

New localities in southern Illinois have yielded a flora consisting of 9 taxa. The plant remains occur in sandstones of the Chester Series and consist of casts, molds, and flattened impressions. The most important elements in the flora are: Archaeocalamites radiatus, Lepidodendron volkmannianum, Stigmaria ficoides, Rhynchogonium fayettevillense, and an unnamed Trigonocarpus. Stems probably referable to Lepidodendron veltheimii and Dictyoxylon also occur, as do numerous casts of the Knorria and Bergeria types. The range of features found in specimens of Lepidodendron volkmannianum allows some revision to be made of several species previously described by White in the Wedington Sandstone flora of northwest Arkansas, with which the present flora is closely comparable. The difficulties in making precise correlations with Upper Mississippian floras in other parts of the world are discussed. The necessity for critical re‐examination of existing described collections and of undertaking more extensive field‐work in the Mississippian of N. America is emphasized.
ECOTYPIC DIFFERENTIATION WITHIN FOUR NORTH AMERICAN PRAIRIE GRASSES. II. BEHAVIORAL VARIATION WITHIN TRANSPLANTED COMMUNITY FRACTIONS
Authors: McMillan Calvin
Published: January 2018

Ecotypic differentiation in transplanted clones of Andropogon scoparius Michx., A. gerardi Vitman, Panicum virgatum L. and Sorghastrum nutans (L.) Nash showed north‐south correlations. In Austin, Texas, during 1959–1962, southern populations had earliest spring activity, latest flowering and latest dormancy. Northern community fractions from Massachusetts to North Dakota showed early flowering and a short span separating initial anthesis among the species‐populations. Community fractions from Virginia to Nebraska had initial anthesis over a longer period than in more northern or more southern samples. Community fractions from South Carolina to eastern Texas had late flowering over a short period. Western community fractions, latitudinally and altitudinally diverse, were behaviorally uniform. The length of the growing period and its recurrent selection have sorted out ecological variants in harmony with the habitat gradients. Whether they are of the predominant physiognomic types, as in the true prairie region, or understory plants in the pine forests, the 4 grass taxa are in the climax matrix.
FINE‐STRUCTURAL CHANGES IN THE CYTOPLASM OF GERMINATING POLLEN
Authors: Larson Donald A.
Published: January 2018

Quiescent and germinated pollen grains of Parkinsonia aculeata, Hymenocallis occidentalis, Hippeastrum belladonna, and Ranunculus macranthus were studied electron microscopically following KMnO4‐fixation, and comparisons between the 2 developmental stages were made. In the process of germination, mitochondrial structure characteristically remains unchanged from the quiescent stage form, while other organelles undergo significant modifications. In all 4 species, the Golgi apparatus becomes secretory, producing large vesicles which migrate to the cell surface and contribute substrate(s) to the forming pollen tube wall. In Hymenocallis and Hippeastrum, plastids initiate starch storage only after germination begins; this appears to involve an increase in plastid lamellae. Vacuoles arise in germinating pollen of P. aculeata from elements of the ER, while in the other 3 species vacuoles develop from “prevacuolar bodies.” Generative cell structure, vegetative nuclear structure and a unique plasma membrane‐ER relationship in H. belladonna are briefly described.
THE ACRASIEAE IN NATURE. I. ISOLATION
Authors: Cavender James C. , Raper Kenneth B.
Published: January 2018

The clonal isolation of Acrasieae from suspensions of soils or organic substrates may be accomplished by employing a dilute hay‐infusion agar medium to the surface of which pregrown bacteria have been added as a source of nutrient for the myxamoebae. The method described permits quantitative sampling of cellular slime mold populations, and it has been used by the authors in a study of the occurrence and distribution of these organisms in North and Central American forests.
PHYTOCHROME CHANGES IN TISSUES OF DARK‐GROWN SEEDLINGS REPRESENTING VARIOUS PHOTOPERIODIC CLASSES
Authors: Hopkins William G. , Hillman William S.
Published: January 2018

Excised tissues of dark‐grown seedlings representing long day, short day and daylength indifferent photoperiodic classes were assayed for nonphotochemical changes in phytochrome. In all tissues tested, these changes were qualitatively the same. A brief irradiation with red light was followed in darkness by a decrease in total phytochrome, the disappearance of PFR, and an increase in detectable PR. Within the limits of the tissues tested, the kinetics of phytochrome change can be assigned to three groups on the basis of rates. These groups are represented by coleoptiles, hypocotyls and epicotyls, and mesocotyls. The kinetics could not be distinguished on the basis of the photoperiodic class of the mature plant. The significance of these kinetics with respect to the photochemistry of phytochrome conversion is discussed.
DEVELOPMENT OF VEGETATIVE AND FLORAL MERISTEMS OF ARABIDOPSIS THALIANA
Authors: Miksche Jerome P. , Brown John A. M.
Published: January 2018

Seeds were sown on mineral agar and grown under axenic constant conditions. Floral transition and flower primordia were observed at approximately 172 and 220 hr, respectively. The vegetative apex was flat in outline for 160 hr, after which time it was slightly dome shaped; cytohistological zonation was not readily apparent. The inflorescence apex (172 hr) was markedly convex and possessed 3–5 and 4–6 cell layers in the most axial and lateral portions of the apex, respectively. The nucleoli of cells of the T2 layer were larger than cells of the T1 and outer corpus during vegetative development; in contrast, they were equal in size at reproductive stages.
TRANSLOCATION IN SPOROPHORES OF LENTINUS TIGRINUS
Authors: Littlefield L. J. , Wilcoxson R. D. , Sudia T. W.
Published: January 2018

Upward translocation of methyl violet and P32 in sporophores of Lentinus tigrinus occurred primarily in morphologically specialized hyphae in the center of the stipes. Hyphae in which most of the translocation occurred were loosely arranged, unbranched and seldom septate as contrasted to short, densely packed hyphae in the cortical zone of the stipes where little translocation occurred. More P82 was translocated in a high‐transpiration environment than in a low‐transpiration environment. Nearly all translocation was stopped by killing the sporophores with propylene oxide, even though high‐transpiration conditions were maintained. The respiratory rate of hyphae in the central zone of the stipe was greater than that of hyphae in the cortical zone.
THE NATURE OF THE WALL BETWEEN GENERATIVE AND VEGETATIVE NUCLEI IN THE POLLEN GRAIN OF TRADESCANTIA PALUDOSA
Authors: Maruyama Keizo , Gay Helen , Kaufmann Berwind P.
Published: January 2018

Electron‐microscopical studies have revealed the existence of a true cell wall—probably containing cellulose and pectin—between generative and vegetative nuclei in the pollen grain of T. paludosa. The wall is formed by the fusion of pectin vesicles and becomes continuous at the time of its formation with the intine of the pollen‐grain coat. Coincidentally, the inner and outer plasma membranes bordering the newly formed cell wall participate in formation of the plasma membranes of the vegetative and generative cells. Attention is directed to the possible role of the cell wall in facilitating, within the closed system afforded by the pollen grain, the pattern of differentiation that serves to determine the structural and functional properties of the vegetative and generative cells.
THE CHROMOSOME RACES OF ZINNIA JUNIPERIFOLIA
Authors: Torres Andrew M.
Published: January 2018

A comparative study of the distribution, habitat, morphology and cytology of diploid (n = 10) and tetraploid races of Z. juniperifolia of the subgenus Diplothrix (COMPOSITAE‐Heliantheae) was carried out to elucidate their relationships. There is a positive correlation between chromosome number and many floral and vegetative characters, including pollen size. Chiasmata frequency is about 0.63 and 0.62 per chromosome in the diploid and in the tetraploid respectively. Multivalents are common in the latter. Although attempts to obtain colchicine‐induced tetraploids have failed, available morphological, cytological and chromatographic evidence indicate the tetraploid may be of autoploid origin. Alternative ancestries involving other species of the subgenus are discussed. Taxonomically the tetraploid is considered a race of Z. juniperifolia.
GENETIC BLOCKS IN THE THIAMINE SYNTHESIS OF THE ANGIOSPERM ARABIDOPSIS,,
Authors: Rédei G. P.
Published: January 2018

Five thiamine‐requiring mutants were obtained at two loci. Two are blocked in the synthesis of the pyrimidine part of the vitamin, the other three have lost the ability to make the thiazole moiety. None of the tested substances suggested as possible or likely precursors of the pyrimidine or the thiazole components of thiamine displayed any activity in the mutants. These conditional lethals responded to remarkably small supplements of thiamine. The pyrimidine‐requiring mutants utilized to some extent the anti‐vitamin neopyrithiamine. The thiazole‐less mutants grew on basal media supplemented only with the analog, oxythiamine. Thiamine deficiency, irrespective of the position of the genetic block in the synthesis, results in a characteristic anomaly of pigmentation. The position of the py locus in the second linkage group has been determined. Allelic complementation has not been detected. The frequency of mutations affecting thiamine synthesis appears about the same in Arabidopsis as in fungi. The general frequency of reparable genetic lesions is, however, one to two orders of magnitude lower in Arabidopsis than that in fungi or bacteria.
MOVEMENT OF THE FLOWER STIMULUS IN XANTHIUM
Authors: Lam Shue‐Lock
Published: January 2018

A distribution pattern of the flower stimulus is clearly demonstrated. The direction of the movement of the flower stimulus could be altered either by application of GA or by removal of the plant organs concerned. Dormant buds responded to the flower stimulus provided that the flower stimulus was forced down by means of decapitation and disbudding or was raised to a high level by increasing the number of the inductive cycles. A photoperiodically insensitive leaf which had been exposed to short days can still exert the inhibitory effect on flowering.
THE DEPENDENCE OF FLOWERING IN SEVERAL LONG‐DAY PLANTS ON THE SPECTRAL COMPOSITION OF LIGHT EXTENDING THE PHOTOPERIOD
Authors: Lane H. C. , Cathey H. M. , Evans L. T.
Published: January 2018

The results of experiments in which the length, time, and spectral composition of photoperiod extensions and light breaks were varied are presented. The plants used included Hyoscyamus niger L. (annual henbane); Beta vulgaris L. (annual sugar beet); Hordeum vulgare L. (barley); Anethum graveolens L. (dill); Lolium temulentum L. (darnel); and Petunia hybrida Vilm. (petunia). Brief light breaks in the middle of each night failed to cause flower induction. Extended breaks and 8‐hr extensions of the photoperiod were effective, particularly those with light from BCJ, rubyred, or incandescent lamps. For all lamp types and species, 8‐hr extensions prior to each daylight period were more effective than those given at the end of each day. Four‐hour light breaks were most effective when given in the middle of each night. The flowering caused by 4‐hr breaks with BCJ light from 8 pm to 12 pm was suppressed when the BCJ light was preceded by 4 hr of fluorescent light. When light from BCJ or fluorescent lamps was interpolated for 2 hr at various times during 8‐hr extensions with light from the other type of lamp, BCJ light stimulated flowering the most, and fluorescent light inhibited it the most, when interpolated at the end of the daylight period. These results are discussed, and a model of how phytochrome participates in the flowering of long‐day plants is presented.
CYTOLOGY OF DIFFERENTIATING TRACHEARY ELEMENTS I. ORGANELLES AND MEMBRANE SYSTEMS
Authors: Esau K. , Cheadle V. I. , Gill R. H.
Published: January 2018

The distribution of organelles, membrane systems, and ribosomes is not at any time obviously related to the pattern of secondary wall in helically thickened tracheary elements in leaves of Beta vulgaris L. (sugar beet) and Cucurbita maxima Duchesne, fixed with potassium permanganate and osmium tetroxide. During the differentiation of the secondary wall, cisternae of the endoplasmic reticulum and dictyosomes are particularly conspicuous, and the dictyosomes are associated with numerous vesicles. Similar vesicles appear to be in various stages of fusion with the secondary wall thickenings. The tracheary elements contain plastids which may include starch granules. Ribosomes occur free in the cytoplasm and in association with endoplasmic membranes.
SYSTEMATIC ANATOMY OF THE FLOWER AND FRUIT OF COROKIA
Authors: Eyde Richard H.
Published: January 2018

Corokia, a genus of shrubs of New Zealand, eastern Australia, and certain Pacific islands, was first placed in Rhamnaceae, later in Cornaceae, and most recently next to Argophyllum, subfamily Escallonioideae, in Engler's monograph of the Saxifragaceae. Most manuals still list Corokia under Cornaceae from which it is readily excluded by several characters, including pluricellular T‐shaped trichomes, ligulate petals, vascular bundles running longitudinally through the center of the inferior gynoecium, histology and germination of the woody endocarp, and a conspicuous subepidermal layer of tannin‐containing cells. Corokia collenettei, endemic to the isolated island Rapa, retains the most primitive floral characters of the genus. Anatomical comparison of Corokia flowers with flowers of Argophyllum shows similarities that probably indicate affinity, but the relation of these two genera to others in Engler's subfamily Escallonioideae is unclear. Engler's inclusion of Berenice and Carpodetus with Corokia and Argophyllum in a tribe Argophylleae seems especially artificial.
THE DIFFERENTIATION OF PIGMENTATION IN FLOWER PARTS. III. METABOLISM OF SOME EXOGENOUS ANTHOCYANINS BY DETACHED PETALS OF IMPATIENS BALSAMINA
Authors: Mansell Richard L. , Hagen Charles W.
Published: January 2018

The anthocyanins of mature petals of Impatiens balsamina L. are distinct from the pigments found in vegetative tissue. In the red genotype (llHHPrPr) a sequential elaboration of the characteristic anthocyanins has been previously demonstrated through the examination of buds at successive stages of development. The metabolism of anthocyanins, especially pelargonidin‐3‐mono‐glucoside, was examined by infiltration into developing petals of a genetically white strain. This anthocyanin appears to play a central role in the biochemical sequences involved and it has been observed that the genetically white flowers possess the enzymatic potential to metabolize this substrate, producing the same final products which are produced in the red genotype. There is a pattern of change in the relative amounts of each anthocyanin during the incubation period which follows closely the pattern which occurs during normal development of the colored genotypes. This indicates that the enzymes which are normally produced in the colored flowers are also produced in flowers which never produce anthocyanins. The metabolic capabilities of several other genetic strains and the influence of light and puromycin have been examined.
ENVIRONMENTAL EFFECTS ON THE DIFFERENTIATION OF ABNORMAL COTTON FLOWERS
Authors: Meyer Vesta G.
Published: January 2018

Previous studies have shown that both genes and cytoplasm have important effects on the number of anthers and external ovules borne by the staminal columns of flowers on plants with the EO gene. Under Mississippi Delta conditions a single plant may produce flowers daily for three months or more. The basic premise for the study reported here was that each of these 100‐200 flowers of a single plant exposed a constant gene‐cytoplasm combination to an extremely variable environment. Highly significant correlations with environment were found as follows: Number of anthers with relative humidity 22 days before anthesis, number of external ovules with minimum temperature 19 days before anthesis, and percentage of sterile anthers with maximum temperature 15‐16 days before anthesis. The external ovule property thus permits study of flower differentiation by manipulating three different variables: (1) cytoplasm, (2) gene dosage, and (3) environment.
THE EVOLUTIONARY SIGNIFICANCE OF NATURAL FRAGARIA CHILOENSIS × F. VESCA HYBRIDS RESULTING FROM UNREDUCED GAMETES
Authors: Bringhurst R. S. , Senanayake Y. D. A.
Published: January 2018

A natural nonaploid hybrid (2n = 63) from fusion of a reduced F. vesca male gamete with an unreduced F. chiloensis gamete, and a partially fertile natural hexaploid hybrid (2n = 42) from fusion of an unreduced F. vesca (2n = 14) male gamete with a reduced F. chiloensis (2n = 56) gamete were discovered in separate mixed colonies along with over 20 additional pentaploid hybrids (2n = 35). Plants of all hybrids aggressively compete with F. chiloensis. This relatively high percentage of hybrids from unreduced gametes may mean that they have higher survival value than pentaploids, since some evidence indicates that unreduced gametes may not function that often in successful F. chiloensis × F. vesca hybridization. The partial fertility of the hexaploid shows that intermediate fertile levels of ploidy need not be derived exclusively from lower ploidy species, and unreduced gametes from such hybrids should produce a high percentage of decaploid offspring in natural backcrossing to F. chiloensis. The successful functioning of unreduced vesca and chiloensis gametes in natural hybridization justifies the postulation that other euploid levels also may occur naturally, including triploids, tetraploids, decaploids, 12 ploids, and 16 ploids. Of these, the even multiples—tetraploids, decaploids, 12 ploids, and 16 ploids—should be at least partially fertile.
FINE STRUCTURE OF SYNAPSED CHOMOSOMES IN F1 LYCOPERSICON ESCULENTUM‐SOLANUM LYCOPERSICOIDES AND ITS PARENTS
Authors: Menzel Maegaret Y. , Price J. M.
Published: January 2018

Typical synaptinemal complexes consisting of electron‐dense central and lateral elements and much less dense outer fibrillar material are formed at meiotic prophase in Lycopersicon esculentum (tomato), Solanum lycopersicoides, their diploid hybrid, and occasionally in tomato haploids (in which an average of about one chromosome region per cell is synapsed nonhomologously). Complexes in the hybrid (in which the chromosomes synapse completely but often fail to form chiasmata) are similar to those in the parents. Complexes in the haploid are similar to those of diploid tomato. The data suggest that synaptinemal complexes form whenever chromosomes undergo meiotic synapsis, regardless of whether synapsis leads to chiasmata.
SYNTHETIC AGROPYRON‐ELYMUS HYBRIDS. I. ELYMUS CANADENSIS × AGROPYRON SUBSECUNDUM
Authors: Dewey Douglas R.
Published: January 2018

Twenty‐four seeds were formed in 34 hand‐emasculated E. canadensis florets exposed to A. subsecundum pollen. Fifteen of the 24 seeds germinated, and 12 plants were raised to maturity. Each of the 12 plants proved to be a hybrid. The hybrids were morphologically intermediate between the parents, although they favored A. subsecundum in general appearance. The parent plants were meiotically regular and behaved cytologically as strict allotetraploids, 2n = 28. Fourteen bivalents were formed in 12.6% of the hybrid cells interpreted at metaphase I. All other hybrid cells contained various combinations of univalents, bivalents, and multivalents. Mean chromosome associations of 0.22 univalents, 11.70 bivalents, 0.11 trivalente, 0.23 quadrivalents, 0.01 pentavalents, and 0.55 hexavalents were observed in 135 hybrid cells. All hybrid pollen examined was shriveled and non‐staining. Five hybrids produced eight seeds, and seven hybrids were completely sterile. The ready cross‐compatibility of E. canadensis and A. subsecundum and the relatively good chromosome pairing in their hybrids suggest a much closer relationship between the parent species than is implied by the prevailing taxonomic treatment. Structural rearrangements appear to be responsible for the relatively few differences between E. canadensis and A. subsecundum genomes and for the sterility of the hybrids. Cytological data from this and other investigations indicate a close relationship between many self‐fertilizing Agropyron, Elymus, and Sitanion species. It is postulated that this composite of self‐fertilizing Agropyron, Elymus, and Sitanion species originated by hybridization between A. spicatum and an unidentified Hordeum species.
BINDING SITES FOR INORGANIC IONS AND UREA ON ISOLATED CUTICULAR MEMBRANE SURFACES
Authors: Yamada Y. , Rasmussen H. P. , Bukovac M. J. , Wittwer S. H.
Published: January 2018

Binding sites for calcium and chloride ions, and urea on cuticular membrane surfaces were identified by microautoradiography. There was no localization of binding on either the smooth outer or irregular inner surfaces of the astomatous tomato fruit cuticle, and urea was bound to a lesser degree than inorganic ions. Calcium and chloride binding sites on surfaces of green onion leaf cuticles were closely associated with stomatal pores and above the periclinal cell walls. Binding of calcium was more pronounced than of chloride. These results are discussed in light of possible sites of entry for foliar applied nutrients.
VASCULAR DYSFUNCTION IN FUSARIUM WILT OF TOMATO
Authors: Corden Malcolm E. , Chambers Henrietta L.
Published: January 2018

Leaves on tomato plants infected with Fusarium oxysporum f. lycopersici frequently wilt unilaterally when the vascular bundles supplying the affected leaflets are diseased. However, when the vascular bundles on one side of healthy petioles are severed by notching the petiole base, the entire leaf remains turgid. Leaflets on the notched side receive water by diffusion between bundles at the petiole tip. Lateral translocation of water out of individual vessels and between bundles in diseased xylem is impaired by the impregnation of vessel walls, intercellular spaces, and cells adjacent to vessels with the products of vascular discoloration. Waterproofing of vascular bundles can be induced in excised healthy leaves by culture filtrates of the pathogen and catechol. Waterproofing of vessels may play an important role in vascular dysfunction by confining water to individual vessels and thereby increasing the importance of vessel occlusions.
CHROMOSOME NUMBERS IN CHEILANTHES AND POLYPODIUM
Authors: Knobloch Irving W.
Published: January 2018

Six chromosome observations are reported, two being confirmations and four being new counts. Polypodium plesiosorum (from Mexico) shows 37 pairs at meiotic metaphase and thus conforms to past counts of diploid species in this genus. Cheilanthes wrightii (Arizona) has 2n = 58 and is a diploid member of the x = 29 series of that genus. Cheilanthes tomentosa (Alabama) shows 90 units at metaphase of meiosis and approximately the same number during mitosis in the crozier cells. It has 32 spores and our plant is an apogamous triploid. Both Cheilanthes siliquosa (Washington) and C. californica (California) show 30 pairs at meiotic metaphase. Counts on plants identified as C. carlotta‐halliae (California) show 30 bivalents and 30 univalents at diakinesis, suggesting that they actually represent allopolyploid backcrosses of C. carlotta‐halliae and one of its parents.
A SIMPLE NEW MYCETOZOAN WITH BALLISTOSPORES
Authors: Olive Lindsay S. , Stoianovitch Carmen
Published: January 2018

A new, single‐spored mycetozoan, Schizoplasmodium cavostelioides, was isolated from dead plant materials collected in New Zealand, Australia, Ceylon, North Carolina, and Florida. Its vegetative stage consists of thin, colorless plasmodia that grow vigorously in culture with an unidentified yeast (or yeast and bacterium). Prior to sporulation the plasmodium breaks up into multinucleate prespore cells which develop immediately into simple fruiting bodies, each consisting of a single multinucleate spore on a short stalk. Under proper conditions a gas bubble appears on one side of the spore, enlarges and bursts, thus discharging the spore. Upon germination the spore releases a single small, multinucleate Plasmodium.
THE SYSTEMATICS AND ANATOMY OF GONGYLOCARPUS (ONAGRACEAE)
Authors: Carlquist Sherwin , Raven Peter H.
Published: January 2018

The unique fruiting structures of the closely related, principally Mexican, monotypic genera Gongylocarpus and Burragea (Onagraceae) compelled a detailed anatomical and cytological investigation of these plants which led to the conclusion that they should be included in a single genus, Gongylocarpus. Gongylocarpus fruticulosus (Burragea), endemic to two adjacent islands off the west coast of Baja California, is divided into two subspecies, subsp. fruticulosus and subsp. glaber. The vegetative and floral anatomy, including wood anatomy, of both species is described. The fruits of these two species grow into the stem by meristematic activity during the course of ontogeny, the ovaries in the mature flower being superficial and sessile in the leaf axil. There is no pedicel associated with the flower, but only a branch gap. Meristematic tissue at the base of the locules divides rapidly at a relatively late ontogenetic stage, the ovaries growing downward into the stem and crushing the pith. The mature, heavily sclerenchymatous fruits are located wholly within the stem, and in G. fruticulosus they are aggregated into long chains. Both species have a gametic chromosome number of n = 11, a characteristic otherwise unknown in the tribe Onagreae but shared with other generalized groups in the family. Taken together with other features, this suggests a primitive position within the tribe for Gongylocarpus.
ALTERNATIVE MORPHOGENETIC EVENTS IN CELL SUSPENSIONS
Authors: Halperin Walter
Published: January 2018

Two distinct types of regeneration, rhizogenesis and embryogenesis, were observed as alternative morphogenetic events in wild carrot cell suspensions. Petiole‐derived callus, grown on high‐auxin media lacking reduced nitrogen, was dispersed, passed through sieves, and the 45–75‐μ fraction was used to inoculate low‐auxin liquid media. After 2–3 weeks adventitious roots developed from endogenous primordia within large cell clumps. In contrast, liquid cultures inoculated with the same fraction, or with the fraction that passed a 45 μ pore sieve, from callus grown on media containing reduced nitrogen yielded enormous numbers of embryos. Globular proembryos were recognizable within several days of inoculation as bud‐like outgrowths from relatively few‐celled proembryogenic masses. The ontogeny of embryos from cultured cells has been compared to the ontogeny of the carrot seed embryo. These new data are discussed in the light of previous regenerative work with carrot cell cultures, current theories of causal aspects of embryogenesis in vitro, and current concepts of the forces controlling embryo development.
POLLEN TUBE GROWTH AND RIBONUCLEIC ACID SYNTHESIS BY VEGETATIVE AND GENERATIVE NUCLEI OF TRADESCANTIA
Authors: Mascarenhas Joseph P.
Published: January 2018

Uridine–H3 is incorporated into both the vegetative (tube) nucleus and the generative nucleus of Tradescantia paludosa within 15 min after transfer of pollen to the growth medium. This incorporation is sensitive to actinomycin‐D. In the presence of actinomycin‐D in the medium at concentrations high enough to inhibit all RNA synthesis, germination, early pollen tube elongation, and the movement of the two nuclei from the pollen grain into the tube does not seem to be inhibited. Actinomycin‐D inhibits later tube elongation and generative‐nucleus division. From these results it is concluded that the vegetative nucleus is biochemically functional at least during the early period of tube growth and is not a degenerate structure. It seems logical also to assume that the messenger‐RNAs required for early tube elongation and nuclear migration are of the long‐lived type, and that both the messenger‐RNA and the ribosomal‐RNA required for these processes is synthesized in the pollen grain prior to anther dehiscence.
AUXOSPORE FORMATION IN TWO MARINE CLONES OF THE DIATOM GENUS COSCINODISCUS
Authors: Holmes Robert W.
Published: January 2018

Auxospore formation has been observed in two marine clones of the diatom genus Coscinodiscus. In each of these clones the variation in valve morphology and structure before and after auxospore formation is appreciable. This variability suggests a reappraisal of the taxonomic characters within the genus will be required if the kinds and types of variation noted are substantiated in other clones. The clones are monecious and the 32 uniflagellate colorless monads, inferred from indirect evidence to be male gametes, form within an undifferentiated mother cell. The method of release of the male gametes differs in the two clones; otherwise their development is similar. The zygote is recognizable and the formation of large diameter cells within the zygote membranes has been observed.
COMPARISON OF NUCLEIC ACIDS IN MAIZE SHOOTS AND PEA EPICOTYLS
Authors: Cherry Joe H. , Lessman K. J.
Published: January 2018

A nucleic acid component (x‐RNA) has been found in high concentration in maize shoots. It is eluted from a MAK (methylated albumin kieselguhr) column at about the same position as messenger RNA. The amount of x‐RNA in pea epicotyls is absent or very low. It is suggested that x‐RNA is long‐lived messenger RNA and is found in high concentration in monocotyledonous plants, especially in the case of plants of the Gramineae family. Dicotyledonous plants, typically, contain little or no detectable x‐RNA as observed by ultraviolet absorbancy. In the case of corn shoots, x‐RNA is in highest concentration in the ribosomal fraction (78,500 × g, 70 min). In both maize shoots and pea epicotyls the newly synthesized nucleic acids were confined to the nuclear fraction (10,000 × g, 10 min).
POLLEN‐FORAGING BEHAVIOR OF BOMBUS IN RELATION TO POLLINATION OF NOTOTRIBIC FLOWERS
Authors: Macior Lazarus Walter
Published: January 2018

Cinematographic records of the pollen‐foraging behavior of six Bombus species on Linaria vulgaris, Lobelia siphilitica, and Antirrhinum majus revealed a generally uniform pattern of pollen deposition by the nototribic flowers on the frons and scutum of the foragers. A forward sweeping motion of the tarsal brushes of their middle legs removed some of this pollen which was transferred to the tibial corbicula of the hind legs. Some insects foraged in an inverted position. An analysis of 804 pollen samples from frons, scutum, and corbiculum of 331 from a total of 395 Bombus visitors, representing eight of the nine native species, on the three plants indicated a high proportion of proper pollen being collected in addition to 15 kinds of foreign pollen. The pollen‐sweeping behavior of Bombus on nototribic flowers is suggested as an important means of pollen‐foraging apart from its utility in insect grooming. Pollen‐foraging insects are considered important pollinators of these nototribic flowers.
ULTRASTRUCTURE OF THE DEVELOPING MEGASPORE MOTHER CELL OF GINKGO BILOBA
Authors: Stewart K. D. , Gifford E. M.
Published: January 2018

The immature megaspore mother cell of Ginkgo biloba is essentially spherical and is surrounded by a thick, complex wall. A large nucleus occupies the central region of the cell, and the organelles appear to be randomly arranged in the cytoplasm. With approaching maturity and the onset of meiosis, the cell elongates in the direction of the ovular axis. An extensive system of ER develops at the micropylar pole of the cell during elongation, and the plastids and mitochondria migrate to the opposite or chalazal pole. The micropylar end of the mature megaspore mother cell is usually devoid of plastids and mitochondria, but these organelles are densely packed in the chalazal end of the cell below the nucleus. The dictyosomes and dense spherosome‐like bodies do not show such polarity in their distribution. At meiosis I plastids and mitochondria are, as a rule, restricted to the chalazal dyad cell that is destined to produce the functional megaspore. The wall of the megaspore mother cell consists of a middle lamella which is irregularly thickened, an outer wall layer resembling the walls of the surrounding nutritive cells, and an inner layer resembling the middle lamella in appearance.
ESSENTIAL OILS AS TAXONOMIC AIDS IN THE CLASSIFICATION OF DICHANTHIUM PARVIFLORUM
Authors: de Wet J. M. J.
Published: January 2018

Essential oil components and gross morphological characters are closely correlated in Dichanthium parviflorum (R. Br.) de Wet et Harlan (Gramineae) and related species. Different species, varieties, and geographical races, as well as hybrids between them, can be identified on the basis of absence or presence and quantity of essential oil components. The morphologically variable D. parviflorum was subdivided into four varieties: var. parviflorum, var. capilliflorum (Steud.) de Wet et Harlan comb. nov., var. mutispiculum (Ohwi) de Wet et Harlan comb. nov., and var. spicigerum (S. T. Blake) de Wet et Harlan comb. nov. These varieties differ from each other morphologically in having respectively racemes with 1‐4 and awned, 3‐5 and awned, 1‐2 and awnlass, and 4‐10 and awned spikelet pairs per raceme.
POLAR GROWTH OF HORMOSIRA BÁNKSII ZYGOTES IN SHAKE CULTURE
Authors: Sussex I. M.
Published: January 2018

Zygotes of the fucalean alga Hormosira banksii initiate rhizoidal outgrowths in stationary culture 15 hr after fertilization and are then recognizably polar. By 24 hr most embryos are two‐celled, and a few are four‐celled. In a dark‐grown population orientation of the developmental axis, as indicated by the direction of the rhizoidal outgrowth, was random around the vertical axis. In a unilaterally illuminated population the rhizoid usually emerged on the shaded side. Zygotes grown in light or darkness in shake culture, where they were continuously reoriented, usually developed as polar embryos, indicating that gradients of environmental factors are not required for initiation of polar growth. Some apolar embryos developed in stationary and shake cultures, but they were most frequent in dark shake cultures.
THE CRAMPON‐BASED DICTYOSTELIA
Authors: Raper Kenneth B. , Fennell Dorothy I.
Published: January 2018

Four new species of Dictyostelium, all with sorophore bases of a unique crampon‐like pattern, are recognized among 25 isolates obtained from samples of soil and leaf litter collected in forests of Panama, Mexico, Costa Rica, Florida, and Texas. The species described are as follows: D. rhizopodium, characterized by frequently clustered sorocarps with yellowish to grayish olive sori and yellow or brownish purple sorophores; D. coeruleo‐slipes with white or cream‐colored sori and purplish blue sorophores; D. lavandulum with grayish lavender to drab vinaceous sori and vinaceous purple sorophores; and D. vinaceo‐fuscum with deep vinaceous gray to dark smoke‐colored sori and lavender sorophores.
OBSERVATIONS ON THE MORPHOLOGY AND PHYSIOLOGY OF MARSILEA SPERM
Authors: Rice Harbert V. , Laetsch W. M.
Published: January 2018

The multiciliated sperm of the water fern Marsilea vestita was examined with a view to establishing its suitability as an experimental subject. Time‐course experiments revealed spermatid development to be temperature dependent. Sterile techniques were devised for observation of sperm on both a population and an individual basis. Sperm discharge, active and senescing sperm were examined by phase‐contrast microscopy. A regular pattern of senescence was ascertained. This included vacuolation of the cytoplasmic vesicle, loss of motility, and ultimate loss of the helical structure of the sperm coil. Sperm life spans were recorded using motility and O2 uptake as criteria. Sperm populations are active 3–3½ hr at ambient temperature (22–25 C). Individual sperm are active less than 1 hr. Sperm suspensions show a decline in O2 uptake which parallels the loss of motility. Various constituents affecting the life span were investigated. A twofold prolongation of the sperm life span occurred in the presence of 0.1 m sucrose. An ultrastructural examination of the mature sperm was made to aid in assessing its metabolic potential. The sperm shows little ultrastructural differentiation. The cytoplasmic vesicle is predominantly composed of starch‐containing plastids. The main structural components of the sperm coil are a continuous mitochondrial band, an elongate nucleus, and a series of microtubules which separate the basal bodies from the nucleus and mitochondrion. A comparison of ultrastructural features common to Pteridium and Marsilea was made and factors affecting senescence discussed.
SITES OF CALLUS PRODUCTION IN PRIMARY EXPLANTS OF SPRUCE TISSUE
Authors: White Philip R.
Published: January 2018

When explants for tissue cultures taken from mature spruce trees, consisting only of xylem‐cambium‐phloem without pith or cortex, are placed on nutrient agar, callus forms first from the cambium, then from phloem parenchyma, and finally from the lining of xylem resin ducts. The proliferating cells of the phloem are the tannin cells which in situ give rise to sclereids in the bark.
HYBRIDIZATION BETWEEN ANNUAL SPECIES OF PHLOX: POPULATION STRUCTURE
Authors: Levin Donald A.
Published: January 2018

Phlox cuspidata (n = 7) and P. drummondii subsp. drummondii (n = 7) are closely related annuals which are indigenous to eastern and central Texas. The species typically occupy different ecological niches but may form contiguous or confluent populations in disturbed habitats and hybridize therein. On the basis of correlative interpretations of exomorphic, chromatographic and fertility information, hybridizing populations can be segregated into three distinct classes: (1) highly fertile plants with the morphological and phenolic attributes of P. drummondii; (2) highly fertile plants with the morphological and chemical attributes of P. cuspidata; (3) sterile plants with manifestly intermediate morphology and complementary chromatographic patterns. These data strongly suggest that hybridizing populations of P. drummondii and P. cuspidata are tritypic, being composed of “pure” or essentially “pure” parental species and a group of plants which has all of the attributes characteristic of an F1 hybrid.
FLOATING STOMATES (ADETOSTOMY) IN FERNS: DISTRIBUTION AND ONTOGENY
Authors: Mickel John T. , Lersten Nels R.
Published: January 2018

A unique guard cell apparatus occurs in certain species of Anemia (Schizaeaceae) and in certain species of the unrelated family Polypodiaceae. A guard cell pair is completely surrounded by one epidermal cell, with no attachment to lateral (anticlinal) walls of adjacent epidermal cells. This condition of “floating stomates” is called adetostomy. In rare cases the surrounding epidermal cell is in turn entirely enclosed by another single epidermal cell. The ontogeny of floating stomates has been variously interpreted. This study supports the early view of Rauter that a funnel‐shaped guard mother cell is initiated in place entirely within a protodermal cell.
STAINING AND ACID PHOSPHATASE REACTIONS OF SPHEROSOMES IN PLANT TISSUE CULTURE CELLS
Authors: Holcomb G. E. , Hildebrandt A. C. , Evert R. F.
Published: January 2018

Spherosomes in plant tissue culture cells from normal sunflower stems and sunflower crown gall tumors reacted similarly to several nonfluorescent and fluorescent lipid dyes. Sudan IV and black B were good selective spherosome stains. The lipid fluorochromes, Nile blue and 3, 4‐benzpyrene were excellent selective spherosome stains and visualized the smallest particles more readily than did Sudan IV. Spherosomes could not be seen in tissues stained with Sudan IV or 3,4‐benzpyrene after ether‐alcohol extraction. Acid phosphatase was detected on the spherosomes in both normal and tumor tissues using the lead sulfide precipitation and the post‐incubation coupling procedures.
A COMPARATIVE STUDY OF THE PRIMARY VASCULAR SYSTEM OF CONIFERS. II. GENERA WITH OPPOSITE AND WHORLED PHYLLOTAXIS
Authors: Namboodiri Kadambari K. , Beck Charles B.
Published: January 2018

This paper reports the results of a detailed comparative investigation of the primary vascular system of seven species of conifers characterized by opposite and whorled phyllotaxis. Three patterns, indicated as types I, II and III, are described. Type I is similar to the sympodial pattern of conifers with helical phyllotaxis. Type III is a reticulate system which results from a fusion of a pair of traces that form the vascular supply to each leaf. Each trace of the pair branches from a separate, adjacent sympodium, and the two traces diverge synchronously in opposite directions. Type II is intermediate between types I and III. It resembles type I in that the vascular supply to a leaf originates as a single trace, and it is similar to type III in that direction of trace divergence may be either sinistrorse or dextrorse. Four species were found to be characterized by both types II and III, the different types occurring in different shoot tips of the same individual. All three types were observed in one species. Where type II occurred in the same plant with either type I or type III, or in the one species in which all types occurred, some leaves were supplied by a trace originating singly, others by a trace originating as a pair of bundles. On the basis of a comparative analysis of the vascular patterns in conifers with helical, opposite and whorled phyllotaxis, including a correlation of the type of vascular pattern with other characters, it was concluded that the reticulate system is probably derived from the open system characteristic of conifers with helical leaf arrangement, that this type of vascular system is composed of sympodia, and that the origin of the vascular supply to a leaf as a single trace is the primitive condition in the Coniferales.
NEW WORLD JUGLANDACEAE: A NEW SPECIES OF ALFAROA FROM MEXICO
Authors: Stone Donald E.
Published: January 2018

Alfaroa mexicana is described as new. Certain aspects of the wood anatomy, inflorescence, pollen, staminate flower, and pistillate flower morphology are compared with previous findings on the three other species of Alfaroa and representatives of the closely related genus Engelhardia.