bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating stem conducting tissue as an estimator of leaf area in four woody angiosperms
Authors: Waring R. H. , Gholz H. L. , Grier C. C. , Plummer M. L.
Published: September 2008

Four woody angiosperm species representing an evergreen tree (Castanopsis chrysophylla (Dougl.) A.DC), a deciduous tree (Acer macrophyllum Pursh), an evergreen shrub (Rhododendron macrophyllum G.Don), and a deciduous shrub (Acer circinatum Pursh) were sampled to assess the relation of cross-sectional area of conducting tissue in the stem to leaf area. For the first three species listed, a linear relation between conducting area and leaf area was obtained with r2 values ranging from 0.89 to 0.96. For Acer circinatum the relation only approached linearity with a log transformation of both axes with r2 = 0.80.
Two new uniporous species of Rhizophydium
Authors: Sparrow Frederick K.
Published: September 2008

Two new species of Rhizophydium (Phycomycetes, Chytridiales) are described, both with uniporous sporangia. Rhizophydium annulatum n.sp. is on pollen from northern Florida, the other, R. lenelangei n.sp., was recovered from Guatemalan soil.
Pulveria, a new genus of Xylariaceae (Ascomycetes)
Authors: Malloch David , Rogerson Clark T.
Published: September 2008

A new genus and species of Xylariaceae, Pulveria porrecta, is described from wood of dead hardwood trees in New York and Ontario. It differs from other genera and species of the Xylariaceae in producing irregularly disposed, globose asci in nonostiolate ascocarps. A short discussion of its morphology and development is included.
The recent fire history of Barron Township, Algonquin Park
Authors: Cwynar Les C.
Published: September 2008

The recent fire history of Barron Township (18 600 ha) in Algonquin Park was studied by examining historical documents and dating past forest fires using dendrochronological techniques. Lightning is still a major ignition source. Over the 36-year period of 1939-1974, lightning accounted for 48.5% of all fires at a rate of 0.19 fires per year per 10 000 ha. Dendrochronological data show that 16 fires burned during the 225-year presuppression interval from1696 to 1920 for a mean frequency of 14.1 years. Five major fires (1875, 1864, 1854, 1780, and 1763) each burned at least half of the township with a mean frequency of 45 years. Meteorological data show that drought prevailed across southern Ontario during 1875, when major fires burned in Barron Township and northern Minnesota, supporting the suggestion that severe fire years correspond with periods of subcontinental drought. Similarly, 1864 appears to have been a major fire year in Barron as it certainly was in Minnesota. The recent fire rotation, i.e., the average time required to burn an area equivalent to the size of the study area, is about 70 years. Field evidence and increment borings suggest that the present vegetation mostly originated as a consequence of the fire of 1875.
Bryophytes of Nahanni National Park and vicinity, Northwest Territories, Canada
Authors: Steere William C. , Scotter George W. , Holmen Kjeld
Published: September 2008

Fifty-one species of Hepaticae and 210 species of Musci, a total of 261 species of bryophytes, are reported from Nahanni National Park and vicinity, southwestern District of Mackenzie, Northwest Territories, Canada. Of those, about 89 species are new to the District of Mackenzie and 11 species are previously unreported from the Northwest Territories.Among the phytogeographically significant species present in the bryoflora are Mesoptychia sahlbergii (Lindb. & Amell) Evans, Molendoa obtusifolia Broth. & Paris, Eucladium verticillatum (Brid.) B.S.G., Scapania simmonsii Bryhn & Kaal., Bryum wrightii Sull & Lesq., Aulacomnium acuminatum (Lindb. & Amell) Kindb., Tortella arctica Crundw. & Nyholm, Didymodon johansenii (R. S. Williams) Crum, Entodon concinnus (De Not.) Paris, Ulota curvifolia (Wahlenb.) Lilj., Bryobrittonia pellucida R. S. Williams, and Andreaeobryum macrocarpum Steere & B. Murray.Hylocomium alaskanum (Lesq. & James) Austin is a name of convenience only and must be abandoned; it is merely a stunted physiological form of H. splendens (Hedw.) B.S.G. that does not merit taxonomic recognition.
Translocation of 11C from leaves of Helianthus: preliminary results
Authors: Fensom D. S. , Williams E. J. , Aikman D. , Dale J. E. , Scobie J. , Ledingham K. W. O. , Drinkwater A. , Moorby J.
Published: September 2008

11C fed to leaves as 11CO2 was used to study the dynamics of short-term translocation of photosynthate in Helianthus. As in 14C studies small amounts of tracer were often detected in the stem close to the fed leaf in the first 5 min, followed by a larger mass flow after 15 min. The speed of mass flow of tracer movement was calculated to be 60 to 400 cm ∙ h−1 depending on the method of calculation. There was no evidence in the premass flow for discrete spots along the stem or petiole where tracer accumulated. Neither was there firm evidence for pulses of tracer moving steadily forward, but there were point fluctuations of greater variability than would be expected by chance alone, which suggest the possibility of abberations of movement superimposed on the mass flow. Details of these abberations could not be assessed with certainty from these preliminary experiments owing to the rather low tracer activity.The translocation profiles were sensitive to the prior light conditioning of the plant and above all to chilling. In Helianthus the latter produced temporary restrictions in translocation which lasted for some 10–12 min.
Cryopreservation of flagellar mutants of Chlamydomonas reinhardtii
Authors: McGrath Marian S. , Daggett Pierre-Marc
Published: September 2008

Ten strains of Chlamydomonas reinhardtii flagellar mutants were successfully cryopreserved using two cryogenic freezing methods. Dimethylsulfoxide (DMSO) was found to be the only effective cryoprotectant of those tested. After recovery, cells were viable and morphologically indistinguishable from non-frozen cells. No recovery was obtained after lyophilization.
Rapid cytoplasmic responses of oat coleoptiles to cytochalasin B, auxin, and colchicine
Authors: Thomas D. des S. , Dunn D. M. , Seagull R. W.
Published: September 2008

Cytochalasin B, auxin, and colchicine elicit rapid cytoplasmic weakening in oat coleoptiles as evidenced by centrifugal displacement of nuclei. Cytochalasin B, applied in combination with colchicine or auxin, produced approximately additive effects. In contrast, combination of auxin and colchicine elicited a mutually antagonistic interaction.
Segmentation apicale et initiation foliaire chez Ceratopteris thalictroides (Fougère leptosporangiée)
Authors: Hébant-Mauri Rose
Published: September 2008

In Ceratopteris the tetrahedral apical cell divides into segments from which the leaves are rhythmically initiated (one leaf every two segments). Leaf initiation is followed by intense activation of mitoses within the whole segment. In contrast, the 'empty' segments remain much reduced. As a consequence, distortion of the segmental pattern occurs, which explains certain phyllotactic phenomena. The schematic structure of the apex of Ceratopteris is compared with that of mosses. Analogies are suggested between the stipular scales of Ceratopteris and moss leaves and between fern leaves and moss branches.
Inhibitors of RNA and protein synthesis and the kinetics of growth of lettuce hypocotyls induced by gibberellic acid
Authors: Sawhney V. K. , Srivastava L. M. , Morley D.
Published: September 2008

The effect of the inhibitors of RNA and protein synthesis on the kinetics of hypocotyl growth of lettuce seedlings induced by gibberellic acid (GA3) was studied. Cycloheximide (CH), puromycin (Pu), and 5-fluorouracil (Fu) supplied for 72 h inhibited the GA3-induced growth. Short-term treatments of 4 or 8 h of CH + GA3 and Fu + GA3 inhibited growth only if supplied at earlier stages (0–12 h) of GA3-induced growth, but 4- or 8-h treatments of Pu + GA3 inhibited growth at all stages during the 72-h growth period. Two-hour incubation of [3H]leucine at different times showed that in both the water controls and GA3-treated seedlings there was an initial rise in leucine uptake at times which corresponded with the period before cell elongation, and that during the period of maximum cell elongation, there was a drop in leucine uptake. The results presented here support the hypothesis that in lettuce hypocotyls cell elongation is preceded by extensive protein and ribosomal synthesis.
Ecology of algae in a subarctic stream
Authors: Moore James W.
Published: September 2008

Changes in the density of planktonic, epilithic, and epiphytic algae in a subarctic stream (Baker Creek) were estimated from collections made at least every 2 weeks between June 1975 and November 1976. Simultaneous determinations of 17 nutrients. pH, temperature, discharge, and the gut contents of 29 herbivorous animals were made. Multiple regression analysis indicated that temperature had the greatest overall effect on changes in the density of the plankton (Ankistrodesmus falcatus, Scenedesmus quadricauda, Nostoc pruniforme, and Chlamydomonas lapponica) and epilithon (Nostoc pruniforme) during the growing season. It was followed in significance by either NO3-N, hardness, or discharge. NO3-N was always primarily responsible for initiating changes in the epiphyton (Achnanthes minutissima, A. linearis, and Cocconeis placentula). Temperature did, however, assume secondary importance followed by SiO2. Other environmental factors usually had little effect on all three communities.
Characteristics of clover primary leaf necrosis virus, a new spherical isolate from Trifolium pratense
Authors: Ragetli H. W. J. , Elder M.
Published: September 2008

An unknown virus was isolated from a young red clover plant (Trifolium pratense) with a bright yellow leaf mottle and subsequently was isolated from five other field clover plants with milder symptoms growing in three locations. In the laboratory, red clover became systemically infected by the virus only when the plants were kept between 10 and 16 °C after inoculation, and symptoms were mild. Crimson clover (T. incarnatum) was readily invaded at room temperature, and survivors of the initial shock reaction were severely mottled. White clover (T. repens) and Alsike clover (T. hybridum) did not become systemically infected under either temperature regime. The symptom common to all four species, necrotic spots in the inoculated primary leaves, suggested the name clover primary leaf necrosis virus. Among the nine leguminous and six non-leguminous host species, bean (Phaseolus vulgaris) was best suited for virus propagation, and cucumber (Cucumis sativus) was best suited for quantitative assay and detection.The virus was characterized by a single sedimenting species of spherical nucleoprotein particles with a sedimentation value, S20.w, of 136–137, an average diameter of 36 nm, and a specific extinction, E260 nm1%, 1 cm, of 58.15. The nucleic acid was of the ribose type and constituted 21% of the weight of the virion. Activity was lost from crude juice at 65 °C and from purified suspensions at 85 °C, with about 10% activity persisting between 60–70 °C. Two electrophoretic components were isolated from purified preparations. They induced identical symptoms in three hosts, but one replicated both components in bean and had more antigenic determinants than the other, which replicated itself only. The virus was weakly antigenic inducing an antiserum with titer of 128. Some of its in vitro properties were similar to those of carnation ringspot virus, but the two viruses were serologically unrelated. Nor was this virus serologically related to any of 15 other spherical viruses tested.
Regulation of isocitrate metabolism in Chlamydomonas segnis
Authors: Foo Samuel S. K. , Badour Samir S.
Published: September 2008

Isocitrate lyase (EC 4.1.3.1) and isocitrate dehydrogenase (NADP+) (EC 1.1.1.42) activities were detected in cell-free extracts of Chlamydomonas segnis Ettl when the alga was grown photoautotrophically with 5% CO2 in air (v/v) at 11 klx. When the cultures were either bubbled with air (0.03% CO2), exposed to low light intensity (3 klx), or subjected to manganese or nitrogen deficiency, isocitrate lyase activity was undetectable. During growth in batch cultures provided with 5% CO2, the activity of the dehydrogenase was about 5–12 times greater than the lyase.Using partially purified (about 50-fold) enzyme preparations, isocitrate dehydrogenase (NADP+) showed greater affinity for isocitrate (Km = 0.008 mM) than did isocitrate lyase (Km = 0.1 mM). The dehydrogenase had Km values of 0.011 mM and 0.006 mM for NADP and Mn2+, respectively. Both enzymes were inhibited by α-ketoglutarate and oxalacetate at 1 mM, but the dehydrogenase was more sensitive to these two keto acids (68–79%) than the lyase (36%). Glycolate at 1 mM inhibited (36%) only the lyase, while glyoxylate had little effect. The dehydrogenase was subject to concerted inhibition by oxalacetate plus glyoxylate (Ki = 0.01 mM). This inhibition was competitive with respect to isocitrate, and preincubation of the enzyme with NADP in absence of isocitrate was necessary for effective inhibition. Each of NADPH (Ki = 0.06 mM) and ATP (Ki = 0.65 mM) was a non-competitive inhibitor (with respect to isocitrate) of isocitrate dehydrogenase (NADP+), and both nucleotides are suggested to be active in the in vivo regulation of isocitrate metabolism in C. segnis during photoautotrophy.
Bahusutrabeeja, a new genus of the Hyphomycetes
Authors: Subramanian C. V. , Bhat D. Jayarama
Published: September 2008

A dematiaceous hyphomycete, Bahusutrabeeja dwaya gen. et sp. nov., collected on twigs of Cojfea arabica from India, is described and illustrated.
The influence of submersed aquatic plants on temperature gradients in shallow water bodies
Authors: Dale H. M. , Gillespie T. J.
Published: September 2008

In Lake Opinicon, Frontenac County, Ontario, the temperature gradient at midday from 10 cm below the water surface to soil, in clear weather in August, was found to be 10 Celsius degrees (C°)/m in shallow water where there was a large macrophyte biomass and only 0.2 C°/m in deeper water with fewer plants. There was a direct correlation between the log of the biomass per cubic metre and the steepness of the gradient. Reference is made to temperature gradients developed in calm weather during phytoplankton blooms in Scottish lakes.The biomass of aquatic macrophytes growing in a heated greenhouse in tubs with a capacity of 1 m3 increased from early January to the end of February. With increased biomass, the temperature gradient became larger. The size of the gradient correlated with the incoming radiation. Temperature gradients within large populations of the pondweed Potamogeton richardsonii were enhanced by low temperatures near the bottom.Diurnally produced temperature gradients with an algae bloom in the same tubs in the open in late June showed strong correlation with solar radiation, 8 C°/m with cumulative radiation of 22 MJ/m2 and 4.6 C°/m with 12 MJ/m2. The gradients produced by a population of P. richardsonii with tips 17 cm from surface were from 5.2 to 3.4 C°/m but showed less correlation with radiation when the wind velocity was above a threshold value. No gradient was produced in tubs of water without plants.
Architecture of the Agaricus bisporus spore wall
Authors: Rast D. , Hollenstein G. O.
Published: September 2008

Purified wall fragments of Agaricus bisporus spores were examined by electron microscopy untreated or after chemical and enzymatic digestion. The wall is composed of three layers (I, II, III): an electron-dense outer layer (380 nm), a moderately electron-dense middle layer (180 nm), and an almost electron-transparent inner layer (20 nm). Layer I has a smooth outer surface, is granular–amorphous, but also contains some fibrillar material. It has high resistance to alkali and acid and poor susceptibility to enzymic attack. Layer II consists of chitin fibrils embedded in a β-glucan – protein matrix. It is separated into two sublayers by a narrow central band of electron-transparent material. Layer III is amorphous and appears to be a mucilaginous type of substance.
Assembly of particles from southern bean mosaic virus and sowbane mosaic virus components
Authors: Tremaine J. H. , Ronald W. P.
Published: September 2008

Southern bean mosaic virus (SBMV) and sowbane mosaic virus (SoMV) were each dissociated into RNA and protein components in neutral pH buffers containing ethylenediaminetetraacetic acid and 1 M NaCl. The assembly of SBMV particles and of SoMV RNA in SBMV protein was accomplished by dialysis of the virus components into low molarity buffers containing divalent metal ions. Some of these particles were stable in 1% sodium dodecyl sulfate (SDS) and had sedimentation and electrophoretic properties identical with untreated virus. Spherical particles were also assembled with either SBMV or SoMV RNA in SoMV protein and with sodium dextran sulfate in either SBMV or SoMV protein, but these particles were not stable in 1% SDS.
Surface features of the light-colored ascospores of some applanate Hypoxylon species
Authors: Rogers Jack D.
Published: September 2008

Ascospores of Hypoxylon cycliscum, H. flosculosum, H. sulcatum, H. scriblita, H. melanaspis, H. heterostomum, H. tinctor, H. hemisphaericum, and H. punctulatum have been depicted as having smooth walls. Scanning electron microscopy reveals the walls of ascospores of these species to be intricately ornamented. The possible taxonomic significance of these observations is discussed.
Viable seed populations by soil depth and potential site recolonization after disturbance
Authors: Moore Janice M. , Wein Ross W.
Published: September 2008

Seedling emergence from organic and mineral soil layers was measured for nine study sites at the Acadia Forest Experiment Station near Fredericton, New Brunswick. The number of viable seeds showed a decrease from deciduous-dominated forest, to conifer-dominated forest, to organic soil study sites. Viable seed number varied from 3400/m2 for a deciduous-dominated forest study site to zero for a bog study site. Most seeds germinated from the upper organic soil layers of all study sites and were predominantly Rubus strigosus Michx. After the germination experiment, ungerminated seeds, which showed no viability by the tetrazolium test, were separated from the soil. These seeds were almost entirely Betula spp. and seed numbers were as high as 4200–9400/m2 for a deciduous-dominated forest. The applicability of the results to differing types of postdisturbance revegetation is discussed.
Cytology and ultrastructure of Thanatephorus cucumeris and related taxa of the Rhizoctonia complex
Authors: Tu C. C. , Kimbrough James W. , Aldrich H. C.
Published: September 2008

Cytological studies on the vegetative hyphae of members of the Rhizoctonia complex and basidial structures of Thanatephorus cucumeris were performed with light and electron microscopy. Vegetative cells of Thanatephorus and Waitea proved to be multinucleate, whereas those of Uthatobasidium, Ceratobasidium, Athelia. and Botryobasidium are binucleate.Dolipore septa of Thanatephorus, Waitea, Uthatobasidium, and Ceratobasidium are visible with the light microscope when stained with aniline blue in glycerine. Ultrastructurally, pore caps in these genera consisted of two-layered unit membranes, forming cisternae with an electron-dense middle layer. Dolipore septa of Athelia (S. rolfsii) and Botryobasidium are not visible in aniline blue at the light microscope level. At the ultrastructural level, there was an additional cisternal membrane making up a pore cap of three membranes. The fine structure of nuclei, mitochondria, endoplasmic reticula, vacuoles, and other organelles in the basidial structures of T. cucumeris was essentially the same as in other basidiomycetes.Karyogamy of two haploid nuclei occurs in the young basidia of T. cucumeris. The nuclear envelopes of both haploid nuclei break at their adjacent sides and fuse to form a diploid nucleus. After a short interphase, meiosis occurs. No leptotene was observed at prophase I, but a synaptinemal complex was evident and six pairs of chromosomes were observed throughout pachytene, diplotene, and diakinesis. The nuclear envelope disappears at metaphase I and a spindle appears. The second meiotic division is equational. Most of the mature and discharged spores are uninucleate.
Unusual plasties in an endomycorrhizal root
Authors: Scannerini Silvano , Bonfante-Fasolo Paola
Published: September 2008

Unusual plastids, identified as globular chromoplasts directly developed from proplastids, observed in the infected root cells of Ornithogalum umbellatum L. are tentatively interpreted as an expression of host reaction to fungus infection.
Localisation et comportement du mycélium de Taphrina deformans dans le mésophylle et sous la cuticule des feuilles de pêcher (Prunus persica)
Authors: Schneider Alain , Dargent Robert
Published: September 2008

The mycelium of Taphrina deformans (Berk) Tul. stands beneath the cuticule in the layer of pectic substance which spreads over the cellulosic wall of epidermic cells.It also runs within the mesophyll in the amorphous substance of pectic nature which is localized along the ridges of cells and is probably the initium of the middle lamella. This structure often remains incomplete in parasitized leaves.Hyphae do not seem to attack cellulosic walls, cuticule, or pectic substance. They seem to progress chiefly by physical means.
Seed-cone differentiation and sexual reproduction in western white pine (Pinus monticola)
Authors: Owens John N. , Molder Marje
Published: September 2008

Pollen-cone buds differentiated in the fall but meiosis and pollen development did not occur until the next spring. Pollen cones resumed development in mid-April, meiosis occurred in mid-May and pollination about 1 month later. Mature four-celled pollen entered the micropyle by means of a pollination drop and germinated on the nucellus about 1 month after pollination. Pollen tubes grew part way through the nucellus and became dormant in late summer before male gametes formed.Seed-cone buds differentiated in the spring from distal axillary apices which were initiated in the long-shoot terminal buds in the fall. Apices resumed development in early April and bracts and ovuliferous scales were initiated from mid-April until early June. Meiosis of the megaspore mother cell occurred in early July and the functional megaspore underwent free nuclear division until late August when the seed cones became dormant. Ovule and pollen-tube development resumed in early April. Free nuclear division occurred in the female gametophyte until early May when cell walls formed and three to five archegonia differentiated. Two male gametes formed in each pollen tube before it reached the archegonium. Fertilization occurred in early June. Simple polyembryony was rare but cleavage polyembryony was a regular feature. Early embryo development was rapid and easily distinguishable embryos were present by mid-July. Embryos and seeds were mature by early September when seeds were normally shed.The reproductive phenology and morphology of Pinus monticola is similar to other soft pines. Stages in the reproductive cycle are noted where abortion of cones or ovules or adverse weather conditions may result in a poor cone crop or poor seed set.
Resistance to water flow in Fagus grandifolia leaves
Authors: Tyree M. T. , Cheung Y. N. S.
Published: September 2008

The tempo of water efflux from single Fagus grandifolia leaves has been measured. The resistance to pressure-driven water efflux has been measured for normal leaves, Rs, and for leaves in which extracellular mesophyll spaces are infiltrated with water, Rs*. The ratio Rs*/Rs is about 0.4. The resistance to water flow through the xylem, Rx, was also measured and found to be a small part of Rs, i.e., Rx/Rs = 0.08. The activation energies for water efflux from normal and infiltrated leaves are both about 26 ± 4 kJ/mol.After an analysis of our data, we conclude that the membrane hydraulic conductivity of F. grandifolia leaves is roughly 10−6 cm s−1 bar−1 (1 bar = 100 kPa) and that water travels the shortest path between the cell sap and the nearest xylem vessel, flowing in and out of mesophyll cells through the areas in contact between adjacent cells along the pathway.
Environmental control of lateral bud growth in the sunflower (Helianthus annuus)
Authors: McIntyre Gordon I.
Published: September 2008

A study of environmental effects on lateral bud growth in the sunflower, Helianthus annuus, showed that the provision of a high relative humidity (90 ± 5%) in conjunction with a high light intensity (about 30 000 lx) and an abundant N supply (420 ppm) permitted the buds at the basal nodes to escape from apical dominance and to develop as lateral branches. A reduction in any one of these three factors was sufficient to prevent the release of the buds from inhibition. The marked effect of humidity on bud growth suggested that the degree of water stress is the factor most likely to limit the growth of the lateral buds under field conditions. The mode of action of water stress and the N supply is discussed in relation to the genetic control of bud activity and to the role of nutrient competition in the mechanism of apical dominance.
Polychlorinated biphenyls and their effects on photosynthesis and respiration
Authors: Sinclair J. , Garland S. , Arnason T. , Hope P. , Granville M.
Published: September 2008

The effects of short-term exposures to polychlorinated biphenyls were investigated using Chlorella vulgaris and isolated spinach chloroplasts as experimental material. When Chlorella were immersed in a Warburg-Buck medium to which 10 mM glucose had been added. Aroclor 1221 was found to cause a significant inhibition of the respiration rate at concentrations above 10−7 M. When Chlorella were immersed in the same Warburg-Buck medium to which no glucose had been added, Aroclor 1221 caused a stimulation of the respiration rate at concentrations above 10−5 M. There appeared to be little effect on photosynthesis in Chlorella when Aroclor 1221 was present even at concentrations as high as 10−3 M. In contrast, oxygen evolution from isolated spinach chloroplasts using potassium ferricyanide as the electron acceptor was inhibited by Aroclor 1221. This inhibition was also apparent when the uncoupler ammonium chloride was present. Since there was no inhibition when photosystem I was examined on its own, it is suggested that Aroclor 1221 can inhibit photosynthesis in spinach chloroplasts at a site on the electron transport chain close to photosystem II.
Morphogenesis of azygospores induced in Gilbertella persicaria (+) by imperfect hybridization with Rhizopus stolonifer (−)
Authors: O'Donnell K. L. , Ellis J. J. , Hesseltine C. W. , Hooper G. R.
Published: September 2008

Morphogenesis of azygospores induced in Gilbertella persicaria (+) by the illegitimate cross of this species with Rhizopus stolonifer (−) was examined by light microscopy and transmission and scanning electron microscopy. Gametangia were formed only in G. persicaria. A continuous secondary azygospore wall was laid down within the original gametangial walls, and it was within this secondary wall that the conical, electron-opaque warts developed. Simultaneously, autophagic vacuoles filled the suspensor of R. stolonifer. Mature azygosporangia possessed a black outer ornamental layer consisting of connate truncate, conical warts. Azygosporangia were adjoined by intact fusion septa at their interface with a R. stolonifer progametangium. The significance of azygosporangia induced during imperfect hybridization was discussed in relation to the taxonomy and biology of the Mucorales.
Bud development in Picea glauca. I. Annual growth cycle of vegetative buds and shoot elongation as they relate to date and temperature sums
Authors: Owens John N. , Molder Marje , Langer Hilary
Published: September 2008

Vegetative buds of Picea glauca (Moench) Voss were studied throughout the annual growth cycle in several trees in 1975 and 1976 and bud development was related to lateral vegetative shoot growth, date, and temperature sums.Vegetative buds became mitotically active in mid-April at lower elevations and about 6 weeks later at higher elevations. Shoot elongation was characterized by similar smooth sigmoid curves in both years. Shoot growth was slow for the 1st month, rapid during the 2nd month, and slow again for the 3rd month and ended by early August. Temperature sums related best to percentage of shoot elongation if the end of vegetative bud dormancy was used as the starting date and 5 °C was used as the threshold temperature. Arbitrarily chosen starting dates and threshold temperatures gave temperature sums which were related to shoot elongation only when shoot elongation was nearly completed. Generally, if the end of vegetative bud dormancy is known, the number of days from that time is nearly as accurate as the more complex use of temperature sums in predicting the percentage of shoot elongation or the stage of vegetative bud development.Bud-scale initiation occurred during shoot elongation. Axillary buds were initiated in mid-May and flushing occurred when shoots had elongated to about 30% of their final length in late May or early June. The end of shoot elongation coincided with the onset of leaf initiation on all trees in both years. The change from bud-scale initiation to leaf initiation was preceded by a marked increase in apical width and a slight increase in apical height and mitotic frequency. Leaf initiation was rapid for 6 weeks then slower for the last 4 weeks. Vegetative buds became dormant in mid-October.Vegetative bud development is closely related to shoot elongation. Breaking of vegetative bud dormancy was not affected by temperature but shoot elongation and flushing were affected by temperatures which occurred after dormancy was broken.
Effect of naphthalene and aqueous crude oil extracts on the green flagellate Chlamydomonas angulosa. III. Changes in cellular composition
Authors: Soto C. , Hellebust J. A. , Hutchinson T. C.
Published: September 2008

Changes in major cellular composition during growth have been determined for normal Chlamydomonas angulosa batch cultures, napthalene-treated cultures, and cultures treated with aqueous crude oil extracts.During the exponential phase of normal growth, the cellular content of all major constituents varied in a rhythmic pattern in response to the growth rate of the cultures. The extent of initial compositional changes depended on whether the cell inoculum originated from exponential or stationary phase cultures. When cultures reached stationary phase, increases in all major constituents were observed.When C. angulosa was incubated in a closed system with 50% saturated naphthalene medium. pigments and total cellular carbon remained constant, total protein decreased, whereas carbohydrate and lipids increased. Immediate recovery was not observed upon transfer to an open system unless the cells were resuspended in fresh medium.When C. angulosa was incubated in a closed system with aqueous crude oil extract, cellular carbohydrate remained constant, total protein decreased significantly, whereas pigments, cellular total carbon, and lipids increased. On transferring to an open system, these cells recovered more readily as compared with naphthalene-treated cells.
A fine-structural study of the pea downy mildew fungus Peronospora pisi in its host Pisum sativum
Authors: Hickey Edward L. , Coffey Michael D.
Published: September 2008

Downy mildew disease of the cultivated pea Pisum sativum L. caused by the fungus Peronospora pisi Sydow was studied in mature leaves and young shoots of the host plant. Particularly in systemic infections of young shoot tissue, a common occurrence was an extremely electron-opaque membrane-bound, hemispherical deposit extending through the host cell wall into the host cytoplasm. This material which abutted directly onto the intercellular hyphal wall was termed the penetration matrix. Its formation was apparently the result of a specific interaction between the host and obligate fungal parasite. Similar apparently solid or gellike material constituted the matrix surrounding the digitlike intracellular haustorium. This membrane-bound extrahaustorial matrix was present through the penetrated host cell wall and formed a relatively thick layer around haustoria in young shoot tissue, but was much thinner distally around haustoria in mature leaf mesophyll cells. An unusual, regularly arranged, tubular network of ribosome-free endoplasmic reticulum was occasionally found in the host cytoplasm in systemically infected shoot tissue adjacent to haustoria.
The effects of chlordane on the green algae Scenedesmus quadricauda and Chlamydomonas sp.
Authors: Glooschenko Valanne , Lott John N. A.
Published: September 2008

Chlordane is an organochlorine soil insecticide whose effects upon aquatic ecosystems, and particularly on algae, are little known. Experimental results indicate that chlordane concentrations ranging from 0.1 to 100 μg/ℓ significantly stimulate cell division of Scenedesmus quadricauda, a common planktonic green alga. Chlordane in concentrations from 0.1 to 50 μg/ℓ is also stimulatory to the growth of Chlamydomonas sp., isolated from soil. However, 100 μg/ℓ was inhibitory to cell division in this species.Significant stimulatory effects on the respiration rates of these two species were observed at all concentrations within 3 to 4 h of chlordane addition. Stimulation of respiration increased with increasing chlordane concentration. Similar stimulatory effects on respiration were produced using 2,4-dinitrophenol (DNP), a known uncoupling agent of oxidative phosphorylation. Long-term inhibition of photosynthetic response of Scenedesmus quadricauda treated with the higher chlordane concentrations was observed over the course of the experiment even though a significant increase in cell numbers over the control was noted. A highly significant chlordane–light interaction was observed on photosynthesis of both S. quadricauda and Chlamydomonas sp.
The morphogenesis of substomatal structures in Polypodium vulgare
Authors: Stevens R. A. , Martin E. S.
Published: September 2008

The development of substomatal sacs and the capacity of the underlying ion-adsorbent sites to accumulate potassium is examined in relation to the ontogeny of the stomatal complex and mature guard cells of the fern, Polypodium vulgare. It is suggested that while the substomatal structures are formed at an early stage of stomatal development, their functional capacity may not be fully realised until the guard cell complex is fully matured.
Transmission and scanning electron microscope observations on the trapping of nematodes by Dactylaria Candida
Authors: Dowsett James A. , Reid J.
Published: September 2008

The host–predator relationship of the myceliophagous nematode Aphelenchus avenae Bastian and the predaceous hyphomycete Dactylaria Candida (Nees) Sacc. was investigated using scanning electron microscopy of whole-mount preparations and transmission electron microscopy of ultrathin resin (Spurr) sections. Trapping knobs and knobs with associated hyphae were found to be effective nematode-trapping agents. The ultrastructure of the trapping apparatus and of the nematodes and hyphae during the infection process is reported herein, as is the phenomenon of postinfection 'breakout.' Nonconstricting rings were not observed during this study.
Spatial and temporal patterns in transport and respiratory allocation of [14C]sucrose by white oak (Quercus alba) roots
Authors: McLaughlin S. B. , Edwards N. T. , Beauchamp J. J.
Published: September 2008

The spatial and temporal pattern of carbohydrate movement and respiratory use by the root system of a 15-cm dbh (diameter at breast height) white oak tree was examined by introducing [14C] sucrose into the stem and measuring subsequent efflux of respired 14CO2 from the soil surface. Average specific label of 14CO2 collected from 18 soil-surface chambers representing three distances (0.5, 1.0, and 1.5 m) and six radial lines from the tree was determined on eight sampling dates after introduction of the radiocarbon in October. Average activity peaked at 5, 10, and 10–17 days at distances of 0.5, 1.0, and 1.5 m, respectively, indicating a movement rate of about 0.1 m per day. Equilibrium of 14C with endogenous substrate pools occurred after 17 days. Analysis of variance of gross CO2 efflux rates over six sample dates in late October and early November detected no consistent differences either radially or circumferentially around the sample tree. About 65% of the variability noted was attributed to variables describing time, temperature, days since rainfall, and sampling position relative to adjoining trees. Both conventional and nonparametric statistical analysis of concurrent rates of 14CO2 and CO2 efflux indicated no consistent correlation between autotrophic and total CO2 efflux over the sampling interval analyzed.
Revision of Torula species. Rutola, a new genus for Torula graminis
Authors: Crane J. L. , Schoknecht Jean D.
Published: September 2008

The terminal or intercalary conidiogenous cells of Torula graminis are monoblastic and integrated on micronematous conidiophores. The conidia are phragmosporous and consist of simple or branched chains of acrogenous, brown, minutely verruculose cells which frequently fragment into one- or many-celled segments. Torula graminis differs from T. herbarum, the type species of Torula, in lacking the diagnostic coronate conidiogenous cell that is characteristic of the genus Torula and is, therefore, placed in the new Hyphomycete genus Rutola, as Rutola graminis n.comb.
The occurrence of nuclear fusion in the amoebal phase of the slime mold Echinostelium minutum: a reinterpretation of the significance of this phenomenon
Authors: Haskins E. F.
Published: September 2008

Nuclear fusion occurs in less than 1% of the myxamoebae of Echinostelium minutum de Bary, isolate D-3, sublines 1965 and 1971. Binucleate amoebae undergo synchronous mitosis, the two nuclei fuse, the fusion nucleus divides, cytokinesis occurs, and uninucleate daughter cells are formed. Failure to find a haploid–diploid alternance between the amoebal and plasmodial phases using Feulgen cytophotometry suggests that nuclear fusion is not a prerequisite for plasmodial formation in this isolate. Nuclear fusion may be one of the mechanisms which has led to the polyploid condition of the 1971 subline. This phenomenon may also represent a parasexual process.
Chemosystematic studies in the genus Abies. III. Leaf and twig oil analysis of amabilis fir
Authors: von Rudloff E. , Hunt R. S.
Published: September 2008

The volatile oil of the leaves, and also the twigs, of amabilis fir consists mainly of (−)-β-phellandrene, (+)-car-3-ene, (−)-β-pinene, (−)-α-pinene, myrcene, (−)-limonene, terpinolene, β-sesquiphellandrene, and β-bisabolene. Smaller relative amounts of santene, tricyclene, camphene, sabinene, α-phellandrene, cis- and trans-ocimene, γ-terpinene, linalool, terpinen-4-ol, α-terpineol, bornyl acetate, methyl thymol, thymol, α-cubebene, α-copaene, caryophyllene, humulene, and cadinene–muurolene isomers and their corresponding alcohols were also identified. The presence of three minor diterpene hydrocarbons and manool was indicated by gas chromatography – mass spectrometry.The quantitative variation within trees, between trees, and among northern, central, and southern populations was determined. The high tree-to-tree variability obscures any significant (P = 0.05) geographic trend that may exist. Several qualitative and many significant quantitative differences exist between the leaf oil compositions of amabilis, grand, alpine, and balsam firs andpossibly also noble, white, and California red firs, and these can serve well in chemosystematic studies.
Do North Sea cod (Gadus morhua) fisheries maintain high catch rates at low stock size?
Authors: Rindorf Anna , Andersen Bo Sølgaard
Published: September 2008

This study presents an investigation of the relationship between stock size of North Sea cod ( Gadus morhua ) and catch rates in seven commercial fishing fleets. The shape of the relationship was estimated using a new model allowing both density-dependent changes in catchability and bias in the assessment biomass estimates. Catchability in fisheries targeting a mixed species composition either remained constant or decreased with decreasing stock size, whereas catchability in targeted cod fisheries increased with decreasing stock size. However, even in the cases where catchability increased, the change was insufficient to compensate for the decrease in stock size, and catch rates of all fleets decreased. Two factors that could lead to nonconstant catchability were investigated: (i) the presence of a decoupling between stock size and density in high-density areas and (ii) the presence of concurrent shifts in the spatial distribution of the cod stock and the cod fishery. No evidence of the former was found, but there was a northern shift in the spatial distribution of both effort and the cod stock.
Extending the von Bertalanffy growth model using explanatory variables
Authors: Kimura Daniel K.
Published: September 2008

von Bertalanffy parameters are usually estimated for a species, perhaps by sex, in some well-defined geographical area. An alternative way to estimate von Bertalanffy parameters is to model them in a general fixed-effects nonlinear model. For this model, the length of the ith individual is modeled as yi= f(φ, ti, xi) + εi, where yiis the length and tiis the age of the ith specimen at the time of sampling, φ are the unknown parameters required to model von Bertalanffy growth, and xiare covariates associated with the ith specimen that minimally contain sex information (xi1), but may also contain additional covariates. Standard nonlinear least squares and associated likelihood methods can be used to estimate parameters for this model. For Pacific ocean perch ( Sebastes alutus ), we model the effect that depth of collection has on estimated von Bertalanffy growth parameters; for sablefish ( Anoplopoma fimbria ), we model the effects due to latitude of collection; and for walleye pollock ( Theragra chalcogramma ) in the eastern Bering Sea, we model the effects due to variations in year classes. Results illustrate how modeling von Bertalanffy growth parameters directly using explanatory variables can be used to describe how growth relates to geographic, environmental, or biological factors.
Evaluating probability sampling strategies for estimating redd counts: an example with Chinook salmon (Oncorhynchus tshawytscha)
Authors: Courbois Jean-Yves , Katz Stephen L. , Isaak Daniel J. , Steel E. Ashley , Thurow Russell F. , Wargo Rub A. Michelle , Olsen Tony , Jordan Chris E.
Published: September 2008

Precise, unbiased estimates of population size are an essential tool for fisheries management. For a wide variety of salmonid fishes, redd counts from a sample of reaches are commonly used to monitor annual trends in abundance. Using a 9-year time series of georeferenced censuses of Chinook salmon ( Oncorhynchus tshawytscha ) redds from central Idaho, USA, we evaluated a wide range of common sampling strategies for estimating the total abundance of redds. We evaluated two sampling-unit sizes (200 and 1000 m reaches), three sample proportions (0.05, 0.10, and 0.29), and six sampling strategies (index sampling, simple random sampling, systematic sampling, stratified sampling, adaptive cluster sampling, and a spatially balanced design). We evaluated the strategies based on their accuracy (confidence interval coverage), precision (relative standard error), and cost (based on travel time). Accuracy increased with increasing number of redds, increasing sample size, and smaller sampling units. The total number of redds in the watershed and budgetary constraints influenced which strategies were most precise and effective. For years with very few redds (<0.15 redds·km–1), a stratified sampling strategy and inexpensive strategies were most efficient, whereas for years with more redds (0.15–2.9 redds·km–1), either of two more expensive systematic strategies were most precise.
Historical trends in productivity of 120 Pacific pink, chum, and sockeye salmon stocks reconstructed by using a Kalman filter
Authors: Dorner Brigitte , Peterman Randall M. , Haeseker Steven L.
Published: September 2008

Temporal trends in productivity of Pacific salmon ( Oncorhynchus spp.) stocks are important to detect in a timely and reliable manner to permit appropriate management responses. However, detecting such trends is difficult because observation error and natural variability in survival rates tend to obscure underlying trends. A Kalman filter estimation procedure has previously been shown to be effective in such situations. We used it on a Ricker spawner–recruit model to reconstruct indices of annual productivity (recruits per spawner (R/S) at low spawner abundance) based on historical data for 120 stocks of pink ( Oncorhynchus gorbuscha ), chum ( Oncorhynchus keta ), and sockeye ( Oncorhynchus nerka ) salmon. These stocks were from Washington, British Columbia, and Alaska. The resulting estimated temporal trends in productivity show large changes (on average 60%–70% differences in R/S and average ratios of highest to lowest R/S between 5.4 and 7.9 for the three species). Such changes suggest that salmon stock assessment methods should take into account possible nonstationarity. This step will help provide scientific advice to help managers to meet conservation and management objectives. The Kalman filter results also identified some stocks that did not share temporal trends with other stocks; these exceptions may require special monitoring and management efforts.
Yellow perch (Perca flavescens) stock structure in Lake Michigan: an analysis using mark–recapture data
Authors: Glover David C. , Dettmers John M. , Wahl David H. , Clapp David F.
Published: September 2008

To evaluate the stock structure of yellow perch ( Perca flavescens ) in the southern basin of Lake Michigan and in Green Bay, we analyzed recaptures from a lake-wide mark–recapture study implemented from 1996 to 2001 to infer the range and pattern of movement and spawning-site fidelity. Yellow perch generally moved south along the western shoreline, west along the southern shoreline, and north along the eastern shoreline during summer and non-summer months; the magnitude of movement was greater after spawning. Spawning yellow perch frequently returned to the same site, with 35%–80% of recaptured individuals returning to their marking site. Results from multiple tagging sites within Illinois indicated that spawners may return to larger areas rather than to specific sites, suggesting that large spawning complexes exist. Despite strong fidelity in some areas, straying was evident from all sites during spawning, resulting in mixing throughout the southern basin. Such mixing could promote gene flow and diminish stock differentiation. Dispersal of yellow perch within the southern basin of Lake Michigan occurred regularly across adjacent management boundaries. Therefore, adjacent jurisdictions may wish to consider re-examining their regulations based on this information to ensure consistent, complementary regulations that incorporate the movement patterns of yellow perch.