Crown Region Research Articles

The silkmoth chorion: Morphological and biochemical characterization of four surface regions

Four spatially differentiated surface regions, called aeropyle crown, flat, stripe, and micropyle, are found on the mature eggshell (chorion). Specializations of the apical surfaces of the secretory follicular epithelial cells are implicated in the formation of regional patterns on the chorion. Some of these specializations are restricted to cells overlying certain regions; others are shared by more than one region. Differences between regions are more apparent on the surface than within the bulk of the chorion. Evidence is presented that distinct cell populations, corresponding to the regions, are present long before the start of choriogenesis. One hundred eighty-six chorion-specific polypeptides have been resolved by two-dimensional gel electrophoresis. Fifteen of these are found entirely or predominantly in the aeropyle crown and stripe regions, while eight others are restricted to the aeropyle crown region. Certain of the spatially restricted components are quite unusual in their amino acid compositions when compared with previously analyzed chorion components. Others are closely related, although clearly distinct.

The silkmoth chorion: Morphogenesis of surface structures and its relation to synthesis of specific proteins

The morphogenesis of four spatially differentiated surface regions of the silkmoth eggshell (chorion) has been documented and correlated with differing patterns of chorion protein synthesis within the corresponding secretory cells. During the first half of choriogenesis the polygonal pattern of ridges which cover the entire chorion appears. Regional differences in the morphology of developing ridges are not accompanied by significant protein differences, and thus presumably reflect differences in secretory cell behavior and shape. During the second half of choriogenesis expanding domes of the chorion located immediately beneath three-cell junctions of the overlying secretory surface become prominent surface features exclusively in the aeropyle crown region. Domes are composed of a thin lamellar skin and an inner buttressing “filler.” Continued filler deposition appears to cause a ripping of the lamellar skin, transforming the dome into a multiple-pronged crown that overflows with filler. Continued synthesis of lamellar chorion components elongates and strengthens the crowns until they can stand alone without the support of filler. In the aeropyle crown region, synthesis of regionally specific proteins begins in the second half of choriogenesis and accelerates until the final stages, in parallel with dome/crown formation. The more numerous proteins which are common to all regions are synthesized at approximately equal rates within all regions, and their synthesis decelerates toward the end of choriogenesis. Fifteen of the proteins (excluding filler) which are found predominantly in the aeropyle crown region may be necessary but not sufficient for crown formation, since they also occur in the stripe region (1); presumably the secretory cell surfaces mold the same components differently in the two regions. Filler appears to play an important scaffolding role in crown formation. A group of eight aeropyle crown region-specific chorion proteins which compose filler have been identified on two-dimensional gels and shown to be restricted to one of five previously described classes of chorion proteins.

Relationship of Within-tree Placement of the Pheromone Trap to Codling Moth 1 Catches

Choice of pheromone trap location within the tree canopy has a significant effect on catches of the codling moth, Laspeyresia pomonella (L.). Trap elevation is the most important factor, followed by tree quadrant and placement relative to the periphery of the crown region. Along a vertical gradient, response was confined to traps within the canopy and catches increased with trap elevation. The effect of the trap position in the various tree quadrants on catch was of a lesser magnitude than trap elevation and generally less consistent. Overall, traps in the N quadrant caught ca. 30% less than in the other cardinal positions. Response to traps at the periphery of the crown region was not significantly higher than to traps near the center of the tree. Based on these findings, new guidelines for within-tree placement of pheromone traps are proposed. In addition, implications of this research for the direct control of the codling moth with pheromones using the male removal or the mating disruption technique are discussed.

New plant disease recordPhytophthora erythrosepticaPethy. wilt of cineraria (Senecio cruentusD.C.) cultivars

Abstract Laminae of larger basal leaves initially wilted and petioles became epinastic (Fig. 1). In heavily infected younger plants petioles usually became strictured and watersoaked adjacent to the dilated base. In severe cases petiole bases shrivelled and became detached. Infection occurred mainly at the crown region and mature plants often showed very little evidence of rootrot. Young leaves at the growth point often remained turgid until the stem collapsed at soil level.

Representation of head and face in postcentral gyrus of the macaque.

The receptive field and submodality characteristics of individual neurons within the cytoarchitectural and topographic subdivisions of the head and face areas of the postcentral gyrus (SI) were determined with the technique of extracellular recording. Correlation of the single-unit data with the intracortical location of the recording electrode provided a detailed description of the functional organization within each of the several cytoarchitecturally distinct regions contributing to the representation of the head and face in SI. The data indicate that the functional organization of the SI cortex which receives its principal input from trigeminal mechanoreceptors is comparable to the organization within those SI regions which receive their input from the mechanoreceptors of the limbs, trunk, and tail. In each topographic subdivision of the SI cortex 1) a single region in the periphery is represented several times in widely separated locations, each time in a context of different submodalities and peripheral receptive fields; and 2) neurons belonging to the different submodality classes are segregated so that projections from cutaneous afferents terminate mainly in cytoarchitectural area 3 in the adjacent anterior portion of area 1, while projections from the afferents innervating deep tissues terminate mainly in cytoarchitectural area 3a, area 2, and the posterior part of each 1. Although the mechanoreceptor input to SI is segregated according to submodality and the mechanoreceptors from most body regions project to multiple widely separated regions within SI, neurons with receptive fields confined to the ophthalmic division of the trigeminal peripheral innervation field are found within a restricted region of the anterior postcentral gyral crown which is positioned symmetrically about the junction of cytoarchitectural areas 1 and 3. Neurons with receptive fields confined to the maxillary division of the trigeminal innervation field are found within a ring of cortex which a) completely surrounds the representation of the ophthalmic field, and b) includes parts of cytoarchitectural area 2, 1, 3, and 3a. SI neurons with receptive fields restricted to the mandibular division of the trigeminal innervation field occupy the largest portion of the SI face area and form a ring of cortical cell columns which completely surrounds that cortical region which receives its input from the maxillary peripheral innervation field.

Environmental Control of Net Photosynthesis in Naturally Growing Pinus Ponderosa Laws

Carbon dioxide exchange by intact foliage was monitored in the middle—crown region of 30—m tall ponderosa nine trees growing in their natural environment at 1,300 m in the Sierra Nevada of California. Characteristic diurnal patterns of net photosynthesis as a function of temperature are presented for summer conditions of low, medium, and high environmental stress. Changes in relationship between rates of net photosynthesis and factors of the environment were determined by examining the data within different time periods on days of markedly different stress conditions. Highest correlations were obtained under conditions of low stress when 80—90% of the variation in rates of net photosynthesis could be accounted for by changes in temperature and radiation alone. As general stress conditions increased, ability to predict rates of net photosynthesis decreased, with saturation vapor pressure deficit becoming the dominant factor accounting for variation. General prediction equations using data pooled from a wide range of summer conditions accounted for, at best, 65% of the variation in net photosynthesis.

Centrifugal Effects in Inflated, Rotating Bias-Ply Tires

An equation is derived which governs the dynamic equilibrium contour taken by an inflated and rotating, but otherwise unloaded, bias-ply tire. This equation, which is in the form of a hyperelliptic integral, is based on the membrane theory of shells and the netting analysis of composite materials. Results are obtained for the meridional geom etry of a typical two-ply automobile tire, which are in reasonable agreement with ex perimental measurements. This integral, which describes the dynamic equilibrium contour of the tire, is then used to obtain an algebraic cord load formula. The formula shows how the cord tension at any location is dependent on mass distribution, angular velocity, inflation pressure, deformed tire geometry, and number of cords in the tire. Centrifugal effects, as they influence cord tension, are more pronounced in the bead region than in the crown region. Cord forces are experimentally measured up to 1600 rpm, using the tirecord tension transducer which is a strain-gage instrumented tension link embedded in the tire and placed in series with the cord. Agreement between the theoretically predicted and ex perimentally measured cord forces is good, especially in the range of angular velocities and inflation pressures used in service.

THE ETHOLOGY OF THE SYNAPTID HOLOTHURIAN, OPHEODESOMA SPECTABILIS

Opheodesoma spectabilis commonly occurs in aggregations in the alga Sargassum echinocarpus, a source of shade from which it scrapes adhering detritus, and which allows the dense populations necessary for efficient spawning. The animal is photonegative and moves away from a strong light source. Ocelli provide information on the direction and intensity of sunlight. Statocysts, aided by tactile sensitivity, maintain dorsoventral equilibrium."They may also inhibit unwarranted rapid locomotion. The animal shows no gravity orientation. All sensory receptors are most concentrated in the region of the tentacle crown, and their interaction in controlling the animal's reactions implies considerable central integration of stimuli. The three primary muscular activities are the rhythmic contraction and extension of the tentacles, used in feeding and for slow locomotion; peristalsis of the body wall, involved in rapid locomotion; and the contraction, bending, and reextension of the anterior portion of the body. These activities may vary in rate and amplitude and occur independently or in any combinations. Their initiation and coordination are under central nervous control. Opheodesoma spectabilis has a diurnal rhythm of behavior, reaching an activity peak during the early evening hours and apparently directly dependent on changes in light intensity. Spawning occurs during the summer months.

HISTOCHEMICAL STUDIES OF ENZYME DISTRIBUTION IN SHOOT TIPS OF WHITE SPRUCE (PICEA GLAUCA (MOENCH) VOSS)

The relationship between morphological and metabolic or enzymic differentiation in shoot tips of white spruce has been investigated by histochemical methods revealing the distribution of several enzymes and other cellular constituents in tissues of the shoot tip at different times during the growing season. Most of the enzymes studied showed well-defined distribution patterns which varied with the stage of development of the shoot tip. Less seasonal variation was observed in the distribution of the other substances included.Activity of cytochrome oxidase and succinic dehydrogenase was high in the shoot apex during the flush of growth in the spring, indicating a high level of respiratory activity in that region, consistent with the rapid growth of the shoot. Peroxidase activity was associated particularly with meristematic or potentially meristematic tissue regions. The evidence substantiates the view that mitotic activity is greatest on the flanks of the apex and supports the existence of a quiescent center with relatively low activity in the apical mother cell zone, classically the origin of the primary stem tissues. High phosphatase activity was observed in the crown region and at the bases of needle and cone scale primordia.Young cones in fall or spring exhibited enzyme distribution patterns distinctly different from those in vegetative shoot tips. No evidence was obtained to indicate what enzyme or enzymes might be particularly involved in the differentiation of reproductive buds, but the results provide a basis for a further critical investigation of this differentiation by histochemical means.

The development of loose smut ( Ustilago tritici) in susceptible varieties of wheat, and some observations on field infection

Infected seed of the susceptible wheat varieties Hybrid 46 and Vilmorin 27 was obtained by artificial inoculation. In an infected embryo, loose smut mycelium is present in the scutellum and growing point region. When germination of the seed commences, the fungus also becomes active and the mycelium is carried upwards by the elongation of the epicotyl. This elongation carries the node of the first foliage leaf to a position near the ground level. This node, which contains mycelium, becomes the first crown node. Development then takes place in the crown, until by about April the entire adult plant is laid down in the crown region. The nodes, internodes, and ears of each tiller can be recognized within the leaf sheaths, but their combined length is only about 1/4 in. Loose smut mycelium permeates the whole structure. Expansion of the stems begins from below upwards, the lowest internode of each tiller being the first to elongate. The mycelium already present in the ear is carried up with it, and on emergence the ear is completely replaced by spores. Variations in the amount and forms of infection are discussed. Field observations and a time-of-sowing experiment have shown that loose smut infection is not influenced by environmental conditions after sowing.

On the region of crown from which the cuttings should be collected

On the region of crown from which the cuttings should be collected

Dynamic Compression Test for Adhesion of Rubber to Cord Fabric

Abstract An improved laboratory method has been developed for the purpose of evaluating rubber-cord adhesions. The test-piece consists of a single cord surrounded by a thin cylindrical layer of casing compound which, in turn, is enclosed and protected by a thicker layer of rubber of standard composition. Such test-pieces are subjected to cyclic compression and bending, under controlled conditions of cord tension and ambient temperature, in a specially designed machine. The apparatus simulates the primary stresses and strains which occur in the crown and shoulder regions of a giant tire running under load, and it has been established that the cord bond in the test-pieces breaks down in a manner analogous to that in an overloaded tire. The degree of bond deterioration is determined by comparing the load required to pull the cord axially through that part of the rubber which has been subjected to compression after a specific number of cycles with that required to do so in a similar untreated test-piece. Data show the rate at which the rubber-cord bond deteriorates with various degrees of compression and temperature, and examples are given of the use of the method for evaluating bonding agents for cotton and rayon cords. A general comparison is made between the Henley test and other adhesion tests known to be in use.

Charcoal rot of sugar beet

Abstract does not appear. First page follows. Introduction Charcoal rot of sugar beet (Beta vulgaris L.), caused by Macrophomina phaseoli (Maubl.) Ashby, was found in August, 1932, in Sutter County in the Sacramento Valley and subsequently near Davis, Marysville, Walnut Grove, and on Victoria Island in the delta region west of Stockton. The incidence of infection in numerous fields ranged from 8 to 30 per cent (5).4 Field observations indicated that the fungus attacks half-grown and mature sugar beets during the season of prevailing high temperatures and is probably confined to the hot, interior valleys. It is not known to cause damping-off of sugar-beet seedlings. Inspection of sugar-beet plantings in the cool, coastal valleys has shown them to be free from infection. In studies of a seedling blight of beans (Phaseolus vulgaris L.) caused by this fungus, Kendrick (3) showed that the disease was favored by high temperatures. Later, under controlled conditions, Tompkins and Gardner (6) corroborated Kendrick’s results and found that the fungus from charcoal rot of sugar beet grew throughout a temperature range of 12° to 37° C, with an optimum at 31° and was pathogenic to bean seedlings at high temperatures. A brief discussion on symptoms of the disease, the causal organism, and pathogenicity of the fungus is presented in this paper. Symptoms of the Disease The leaves of diseased plants show pronounced wilting and eventually turn brown and die. Dead leaves remain firmly attached to the crowns. When an infected plant is pulled from the soil, the symptoms of charcoal rot are distinctive enough to readily differentiate it from all other known root rots of sugar beet. Externally, infection is usually confined to the crown region as indicated by brownish-black5 lesions of irregular size and shape (fig. 1) and with a silvery sheen.