Centromere Orientation of Quadrivalents of Heterozygous Translocations and an Autoploid of GOSSYPIUM HIRSUTUM L

Cytological observations of quadrivalents of heterozygous translocations in Gossypium hirsutum L. demonstrate that, in addition to alternate-1 and alternate-2 orientations, a third alternate orientation (alternate-3), which occurs as a three-dimensional, V-type configuration, can be identified.—Two additional types of disjunctions, the centromere orientations of which are rotational modifications of either adjacent or alternate configurations, were also observed in quadrivalents of a translocation heterozygote. These two types are rare, and both appear in the form of the Roman numeral X . The X and the alternate-3 types also occur in quadrivalents of an autoploid of G. hirsutum.—The two X types, along with adjacent-1, adjacent-2, alternate-1 and alternate-2 orientations, represent the six possible types of planar 2 x 2 random orientation of the four centromeres of a quadrivalent. Including the three-dimensional alternate-3 type, there are seven types of orientation.     

ANALYSIS OF THE GEOTROPIC ORIENTATION OF YOUNG RATS. X

The inheritance of elements of geotropic performance in lines of rats (A and B) has been investigated by examining the orientation of young offspring produced in matings of F_1(AxB) with A: Previous studies had shown that the three recognizable groups of receptor elements concerned in geotropic orientation in each of these lines appeared to be inherited in such a way that B groups were dominant with respect to A groups, although this was to a minor extent complicated by influences affecting the variation of orientation as well as the exact form of the curve relating orientation angle (θ) to slope of surface. In the backcross F₁ x A, therefore, at least eight different types of curves were to be expected. These are in fact identifiable among the forty-one individuals carefully studied. Their classification is concordant with the behavior of the respective indices of variation of θ, for which an interpretation has been provided. The basic result is, therefore, that the three receptor groups of excitation units are inherited independently, and alternatively as regards the members of a homologous pair, and that rather simple dominance relations obtain between homologous groups from the two races, namely that a B effect is dominant over the homologous A effect. This interpretation has been tested in various ways, and is in principle completely consistent with the results of a similar experiment involving races A and K.     

Rose Prickles and Asparagus Spines – Different Hook Structures as Attachment Devices in Climbing Plants

Functional morphology and biomechanical properties of hook structures functioning as attachment devices in the leaning climbers Rosa arvensis, Rosa arvensis ‘Splendens‘, Asparagus falcatus and Asparagus setaceus are analysed in order to investigate the variability in closely related species as well as convergent developments of hook structure and properties in distant systematic lineages (monocots and dicots). Prickles and spines were characterised by their size, orientation and the maximum force measured at failure in mechanical tests performed with traction forces applied at different angles. In Rosa arvensis and Rosa arvensis ‘Splendens‘ three types of prickles differing largely in geometrical and mechanical properties are identified (prickles of the wild species and two types of prickles in the cultivar). In prickles of Rosa arvensis no particular orientation of the prickle tip is found whereas in the cultivar Rosa arvensis ‘Splendens‘ prickles gradually gain a downward-orientation due to differential growth in the first weeks of their development. Differences in mechanical properties and modes of failure are correlated to geometrical parameters. In Asparagus falcatus and Asparagus setaceus spines are composed of leaf tissue, stem tissue and tissue of the axillary bud. Between species spines differ in size, orientation, distribution along the stem, tissue contributions and mechanical properties. The prickles of Rosa arvensis and its cultivar and the spines of the studied Asparagus species have several traits in common: (1) a gradual change of cell size and cell wall thickness, with larger cells in the centre and smaller thick-walled cells at the periphery of the hooks, (2) occurrence of a diversity of shape and geometry within one individual, (3) failure of single hooks when submitted to moderate mechanical stresses (F_max/basal area < 35 N/mm²) and (4) failure of the hooks without severe stem damage (at least in the tested wild species).     

DARK ADAPTATION IN AGRIOLIMAX

A method is described which measures the excitation of Agriolimax by light, during the progress of light adaptation, by assuming that the orientating effect of continuous excitation is expressed as a directly proportionate tension difference in the orienting muscles of the two sides of the body. The tendency toward establishment of such a tension difference is caused to work against a similar geotropic effect at right angles to the phototropic one. This enables one to study the kinetics of light adaptation, and of dark adaptation as well. The situation in the receptors is adequately described by the paradigm See PDF for Equation similar to that derived by Hecht for the differential sensitivity of various forms, but with the difference that the "dark" reaction is not only "bimolecular" but also autocatalysed by the reaction product S. The progress of dark adaptation is reflected (1) in the recovery of the amplitude of the orientation and (2) in the rates of light adaptation at different levels of the recovery; each independently supports these assumptions, for which the necessary equations have been provided. These equations also account for the relative variabilities of the angles of orientation, and, more significantly, for the two quite different kinds of curves of dark adaptation which are obtained in slightly different types of tests.     

Growth and cellular patterns in the petal epidermis of Antirrhinum majus: empirical studies

Background and Aims

Analysis of cellular patterns in plant organs provides information about the orientation of cell divisions and predominant growth directions. Such an approach was employed in the present study in order to characterize growth of the asymmetrical wild-type dorsal petal and the symmetrical dorsalized petal of the backpetals mutant in Antirrhinum majus. The aims were to determine how growth in an initially symmetrical petal primordium leads to the development of mature petals differing in their symmetry, and to determine how specific cellular patterns in the petal epidermis are formed.

Methods

Cellular patterns in the epidermis in both petal types over consecutive developmental stages were visualized and characterized quantitatively in terms of cell wall orientation and predominant types of four-cell packets. The data obtained were interpreted in terms of principal directions of growth (PDGs).

Key Results

Both petal types grew predominantly along the proximo-distal axis. Anticlinal cell walls in the epidermis exhibited a characteristic fountain-like pattern that was only slightly modified in time. New cell walls were mostly perpendicular to PDG trajectories, but this alignment could change with wall age.

Conclusions

The results indicate that the predominant orientation of cell division planes and the fountain-like cellular pattern observed in both petal types may be related to PDGs. The difference in symmetry between the two petal types arises because PDG trajectories in the field of growth rates (growth field) controlling petal growth undergo gradual redefinition. This redefinition probably takes place in both petal types but only in the wild-type does it eventually lead to asymmetry in the growth field. Two scenarios of how redefinition of PDGs may contribute to this asymmetry are considered.     

ORIENTATION BY OPPOSED BEAMS OF LIGHT

Computations of the effective angular inclination (H) of the photoreceptive surfaces of the two sides, based upon measurements of orientation angles under the action of beams of light directly opposed or crossing at right angles, show that with larvae of Calliphora and of Lucillia H declines as the total illumination decreases (i.e., as the angle of orientation away from the more intense light increases). H is greater with the two lights opposed at 180°; this may be due to the difference in refraction. For the more sharply pointed larvae of Lucillia, H is less than half as great as in Calliphora.     

Improving the spatial orientation of human teeth using a virtual 3D approach

Since teeth are resistant to decomposition processes, they provide important and at times unique sources of information about fossil humans. Fortunately, dental remains reflect significant evolutionary changes. These changes make a very important and often exclusive contribution to the definition of new taxa or the attribution of fossil specimens to existing taxa.The traditional approach to dental morphometric analyses usually focuses on the recording of several measures of the tooth with calipers, especially the two basic crown diameters (buccolingual and mesiodistal). However, since these measures do not adequately represent the complex morphology of the tooth, 2D images and 3D digital models of dental morphology have been used. For both types of analysis, the possibility of correctly comparing homologous teeth depends on the adoption of a common orientation system. The lack of such a system makes it difficult to compare the results of different studies.Here we describe a new method for orienting teeth specifically devised for the upper and lower first molar (M1). Samples of unworn maxillary (n = 15) and mandibular (n = 15) first molars of modern humans were scanned with a Roland Picza 3D digitizer. The 3D virtual models were used to compare our new orientation method with those proposed in the literature. The new orientation system, which meets a geometric criterion, is based on three points identified on the cervical line and ensures acceptable repeatability of the spatial positioning and orientation independent of the shape and wear of the first molar under investigation. This orientation system is a first step toward the creation of a virtual set of hominid and fossil human first molars, which will allow us to make comparisons via a sophisticated and noninvasive approach. This pilot study also provides guidelines to extend the new methodology to the other types of teeth.     

Change of Floral Orientation within an Inflorescence Affects Pollinator Behavior and Pollination Efficiency in a Bee-Pollinated Plant,Corydalis sheareri

Vertical raceme or spike inflorescences that are bee-pollinated tend to present their flowers horizontally. Horizontal presentation of flowers is hypothesized to enhance pollinator recognition and pollination precision, and it may also ensure greater consistency of pollinator movement on inflorescences. We tested the hypotheses using bee-pollinated Corydalis sheareri which has erect inflorescences consisting of flowers with horizontal orientation. We altered the orientation of individual flowers and prepared three types of inflorescences: (i) unmanipulated inflorescences with horizontal-facing flowers, (ii) inflorescences with flowers turned upward, and (iii) inflorescences with flowers turned downward. We compared number of inflorescences approached and visited, number of successive probes within an inflorescence, the direction percentage of vertical movement on inflorescences, efficiency of pollen removal and seed production per inflorescence. Deviation from horizontal orientation decreased both approaches and visits by leafcutter bees and bumble bees to inflorescences. Changes in floral orientation increased the proportion of downward movements by leafcutter bees and decreased the consistency of pollinator movement on inflorescences. In addition, pollen removal per visit and seed production per inflorescence also declined with changes of floral orientation. In conclusion, floral orientation seems more or less optimal as regards bee behavior and pollen transfer for Corydalis sheareri. A horizontal orientation may be under selection of pollinators and co-adapt with other aspects of the inflorescence and floral traits.     

Bidirectional Echolocation in the Bat Barbastella barbastellus: Different Signals of Low Source Level Are Emitted Upward through the Nose and Downward through the Mouth

The Barbastelle bat (Barbastella barbastellus) preys almost exclusively on tympanate moths. While foraging, this species alternates between two different signal types. We investigated whether these signals differ in emission direction or source level (SL) as assumed from earlier single microphone recordings. We used two different settings of a 16-microphone array to determine SL and sonar beam direction at various locations in the field. Both types of search signals had low SLs (81 and 82 dB SPL rms re 1 m) as compared to other aerial-hawking bats. These two signal types were emitted in different directions; type 1 signals were directed downward and type 2 signals upward. The angle between beam directions was approximately 70°. Barbastelle bats are able to emit signals through both the mouth and the nostrils. As mouth and nostrils are roughly perpendicular to each other, we conclude that type 1 signals are emitted through the mouth while type 2 signals and approach signals are emitted through the nose. We hypothesize that the “stealth” echolocation system of B. barbastellus is bifunctional. The more upward directed nose signals may be mainly used for search and localization of prey. Their low SL prevents an early detection by eared moths but comes at the expense of a strongly reduced detection range for the environment below the bat. The more downward directed mouth signals may have evolved to compensate for this disadvantage and may be mainly used for spatial orientation. We suggest that the possibly bifunctional echolocation system of B. barbastellus has been adapted to the selective foraging of eared moths and is an excellent example of a sophisticated sensory arms race between predator and prey.     

A regression-based 3-D shoulder rhythm

In biomechanical modeling of the shoulder, it is important to know the orientation of each bone in the shoulder girdle when estimating the loads on each musculoskeletal element. However, because of the soft tissue overlying the bones, it is difficult to accurately derive the orientation of the clavicle and scapula using surface markers during dynamic movement. The purpose of this study is to develop two regression models which predict the orientation of the clavicle and the scapula. The first regression model uses humerus orientation and individual factors such as age, gender, and anthropometry data as the predictors. The second regression model includes only the humerus orientation as the predictor. Thirty-eight participants performed 118 static postures covering the volume of the right hand reach. The orientation of the thorax, clavicle, scapula and humerus were measured with a motion tracking system. Regression analysis was performed on the Euler angles decomposed from the orientation of each bone from 26 randomly selected participants. The regression models were then validated with the remaining 12 participants. The results indicate that for the first model, the r² of the predicted orientation of the clavicle and the scapula ranged between 0.31 and 0.65, and the RMSE obtained from the validation dataset ranged from 6.92° to 10.39°. For the second model, the r² ranged between 0.19 and 0.57, and the RMSE obtained from the validation dataset ranged from 6.62° and 11.13°. The derived regression-based shoulder rhythm could be useful in future biomechanical modeling of the shoulder.     

Cuticular terminology in Russula (agaricales)

The pileus cuticle is one-layered in a few species ofRussula, but in the others it can be interpreted as composed of two layers—the epicutis uppermost and below this, the subcutis. The basic difference between the two layers is in hyphal orientation. Cell inflation may obscure the orientation in the cuticles of some species. This has given rise to differing interpretations of cuticular structure, especially in regard to the number of nameable layers present, and thus to differing terms for the layers. No Russulas illustrate this better than those of subsectionVirescentinae, of which the two most common North American species,R. crustosa Peck andR. virescens (Schaeffer ex Secretan) Fries, are discussed and described.     

Influence of a Permanent Magnetic Field on the Composition and Content of Sugars in Leaves and Storage Roots of Radish Plants of Major Types of Magnetic Orientation

The influence of a weak permanent magnetic field (PMF) with a strength of 400 A/m on the composition and content of sugars was investigated in radish (Raphanus sativus L.) leaves and storage roots of the two major types of magnetic orientation (TMO): North–South (NS TMO) and West–East (WE TMO). Plants were grown in spring and autumn in a greenhouse of the Institute of Plant Physiology, Russian Academy of Sciences. The weak PMF changed the total sugar content in the leaves and storage roots of radish depending on the belonging of the radish plants to the NS or WE type of magnetic orientation, the growing season, and age of plants and the plant organ. The PMF was an environmentally significant factor, since radish plants of different types of magnetic orientation (NS and WE) had a different reaction to the effect of the field related to the peculiarities of their physiological status.     

The role of the sun in the celestial compass of dung beetles

Recent research has focused on the different types of compass cues available to ball-rolling beetles for orientation, but little is known about the relative precision of each of these cues and how they interact. In this study, we find that the absolute orientation error of the celestial compass of the day-active dung beetle Scarabaeus lamarcki doubles from 16° at solar elevations below 60° to an error of 29° at solar elevations above 75°. As ball-rolling dung beetles rely solely on celestial compass cues for their orientation, these insects experience a large decrease in orientation precision towards the middle of the day. We also find that in the compass system of dung beetles, the solar cues and the skylight cues are used together and share the control of orientation behaviour. Finally, we demonstrate that the relative influence of the azimuthal position of the sun for straight-line orientation decreases as the sun draws closer to the horizon. In conclusion, ball-rolling dung beetles possess a dynamic celestial compass system in which the orientation precision and the relative influence of the solar compass cues change over the course of the day.     

Microtubule reorganization as a response to implementation of NO signals in plant cells

The effects of an exogeneous NO donor, sodium nitroprusside, on the orientation and organization of cortical microtubules in Arabidopsis thaliana root cells expressing GFP-MAP4 were studied in vivo. It was found that sodium nitroprusside treatment (10–500 μM, 24 h) caused the acceleration of primary root growth and enhanced initiation of root hairs in the differentiation zone. The influence of sodium nitroprusside revealed in changes in the orientation and organization of cortical microtubules in different types of cells of A. thaliana root. The most sensitive to sodium nitroprusside exposure were microtubules in epidermal cells of the elongation zone, where native transverse orientation of cortical microtubules turned into random, oblique, or longitudinal relative to the primary root axis. We suggest that NO, as one of the intracellular secondary messengers, triggers cell differentiation by reorientation of cortical microtubules, possibly via tubulin nitrotyrosination.     

Temporal and topographic characteristics of evoked potentials in the conflict of two consecutive visual stimuli in a working memory task

Behavioral reactions and brain mechanisms involved in processing two matching or mismatching (conflicting) visual stimuli were studied in healthy subjects (mean age 22.57 ± 0.46 years). Line orientations (vertical, horizontal, or 45°) were used as stimuli and were presented with an interval of 1500–1800 ms. The reaction time was shown to increase in the case of a conflict of two orientations as compared with matching orientations. The reaction time depended on the orientation of the reference stimulus and was minimal when a vertical line was used as a reference. An increase in N2 negativity (time window 200–280 ms) in the frontal and parietal cortical areas was identified as an informative indicator of a conflict between the current orientation and the orientation stored in working memory. The dipole sources of N2 were localized to the prefrontal cortex (middle frontal gyrus, frontal pole, and pars orbitalis). The N2 amplitude was found to depend on the orientation of the first stimulus in a pair, being higher in the case of a 45° orientation. The visual areas were shown to play a role in detecting a conflict of two consecutive signals because the early sensory components increased in amplitude. The results implicate cortical structures, including the sensory-specific visual, parietal, and prefrontal areas, in comparing consecutive visual signals and detecting their conflict.     

Ultraviolet floral patterns as functional orientation cues in hymenopterous pollination systems

Field modifications of U.V. floral patterns of Caesalpinia eriostachys Benth. and Parkinsonia aculeata L. showed that bees used U.V. designs as orientation cues. Bees exhibited an in-flight orientation ability which was apparently correlated with size, with smaller bees frequently orienting to the manipulated position of the U.V. absorbent banner petal prior to landing on the flower. The U.V. absorptive banner petal and staminal portions of the flowers of both species seemed to be the most important visual orientation guides, and except for Trigona fuscipennis and T. pectoralis, the banner petal was the more important of the two. Emasculation of the flowers may have removed the orientation cue used by these species of Trigona, which may be orienting to the flowers solely on the basis of pollen odour. Morphological and physiological changes in the floral colour patterns of both species following pollination appear to inhibit visitation by bees. The significance of U.V. floral patterns was also considered.     

Horizontal organization of orientation-sensitive cells in primate visual cortex

In the visual cortex of the monkey the horizontal organization of the preferred orientations of orientation-selective cells follows two opposing rules:(1) neighbors tend to have similar orientation preferences, and(2) many different orientations are observed in a local region. We have described a classification for orientation maps based on the types of topological singularities and the spacing of these singularities relative to the cytochrome oxidase blobs. Using the orientation drift rate as a measure we have compared simulated orientation maps to published records of horizontal electrode recordings.