bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thoracic origin of a sympathetic supply to the upper limb: the ‘nerve of Kuntz’ revisited
Authors: RAMSAROOP L. , PARTAB P. , SINGH B. , SATYAPAL K. S. 
Published: March 2003

An understanding of the origin of the sympathetic innervation of the upper limb is important in surgical sympathectomy procedures. An inconstant intrathoracic ramus which joined the 2nd intercostal nerve to the ventral ramus of the 1st thoracic nerve, proximal to the point where the latter gave a large branch to the brachial plexus, has become known as the ‘nerve of Kuntz’ (Kuntz, 1927). Subsequently a variety of sympathetic interneuronal connections down to the 5th intercostal space were reported and also described as the nerve of Kuntz. The aim of this study was to determine: (1) the incidence, location and course of the nerve of Kuntz; (2) the relationship of the nerve of Kuntz to the 2nd thoracic ganglion; (3) the variations of the nerve of Kuntz in the absence of a stellate ganglion; (4) to compare the original intrathoracic ramus with sympathetic variations at other intercostal levels; and (5) to devise an appropriate anatomical classification of the nerves of Kuntz.Bilateral microdissection of the sympathetic chain and somatic nerves of the upper 5 intercostal spaces was undertaken in 32 fetuses (gestational age, 18 wk to full term) and 18 adult cadavers. The total sample size comprised 99 sides.Sympathetic contributions to the first thoracic nerve were found in 60 of 99 sides (left 32, right 28). Of these, 46 were confined to the 1st intercostal space only. The nerve of Kuntz (the original intrathoracic ramus) of the 1st intercostal space had a demonstrable sympathetic connection in 34 cases, and an absence of macroscopic sympathetic connections in 12. In the remaining intercostal spaces, intrathoracic rami uniting intercostal nerves were not observed. Additional sympathetic contributions (exclusive of rami communicantes) were noted between ganglia, interganglionic segments and intercostal nerves as additional rami communicantes. The eponym nerve of Kuntz should be restricted to descriptions of the intrathoracic ramus of the 1st intercostal space. Any of these variant sympathetic pathways may be responsible for the recurrence of symptoms after sympathectomy surgery.
Biochemical properties of a keratan sulphate/chondroitin sulphate proteoglycan expressed in primate pluripotent stem cells*
Authors: Cooper Susan , Bennett William , Andrade Jessica , Reubinoff Benjamin E. , Thomson James , Pera Martin F. 
Published: March 2003

AbstractWe previously identified a pericellular matrix keratan sulphate/chondroitin sulphate proteoglycan present on the surface of human embryonal carcinoma stem cells, cells whose differentiation mimics early development. Antibodies reactive with various epitopes on this molecule define a cluster of differentiation markers for primate pluripotent stem cells. We describe the purification of a form of this molecule which is secreted or shed into the culture medium. Biochemical analysis of the secreted form of this molecule shows that the monomeric form, whilst containing keratan sulphate, resembles mucins in its structure and its modification with O‐linked carbohydrate. Immunofluorescence and immunoblotting data show that monkey and human pluripotent stem cells react with antibodies directed against epitopes on either carbohydrate side chains or the protein core of the molecule.
A geometric morphometric study of regional differences in the ontogeny of the modern human facial skeleton†
Authors: Viðarsdóttir Una Strand , O'Higgins Paul , Stringer Chris 
Published: March 2003

AbstractThis study examines interpopulation variations in the facial skeleton of 10 modern human populations and places these in an ontogenetic perspective. It aims to establish the extent to which the distinctive features of adult representatives of these populations are present in the early post natal period and to what extent population differences in ontogenetic scaling and allometric trajectories contribute to distinct facial forms. The analyses utilize configurations of facial landmarks and are carried out using geometric morphometric methods. The results of this study show that modern human populations can be distinguished based on facial shape alone, irrespective of age or sex, indicating the early presence of differences. Additionally, some populations have statistically distinct facial ontogenetic trajectories that lead to the development of further differences later in ontogeny. We conclude that population‐specific facial morphologies develop principally through distinctions in facial shape probably already present at birth and further accentuated and modified to variable degrees during growth. These findings raise interesting questions regarding the plasticity of facial growth patterns in modern humans. Further, they have important implications in relation to the study of growth in the face of fossil hominins and in relation to the possibility of developing effective discriminant functions for the identification of population affinities of immature facial skeletal material. Such tools would be of value in archaeological, forensic and anthropological applications. The findings of this study underline the need to examine more deeply, and in more detail, the ontogenetic basis of other causes of craniometric variation, such as sexual dimorphism and hominin species differentiation.
Vascularization of the developing chick limb bud: role of the TGFβ signalling pathway
Authors: Vargesson Neil 
Published: March 2003

AbstractThe developing vertebrate limb has fascinated developmental biologists and theoreticians for decades as a model system for investigating cell fate, cell signalling and tissue interactions. We are beginning to understand the mechanisms and signalling pathways that control and regulate the outgrowth and formation of the limb bud into a differentiated identifiable limb by late embryogenesis. However, the mechanisms underlying the development and maintenance of the vasculature of the developing limb are far from being completely understood. The vasculature supplies oxygen, nutrients and signals to developing tissues, allowing them to develop and grow. Moreover, a lot of evidence recently points to molecules involved in morphological development also controlling vascular development. Thus understanding how the vasculature forms and is patterned in the developing limb may further our understanding of limb development. In this review I outline how blood vessels are formed and maintained and how the developing chick limb is vascularized. I also review the role of the TGFβ superfamily signalling pathway in the development of the chick limb vasculature: in particular, how antagonizing TGFβ signalling in the developing chick limb has shed new light on the role vascular smooth muscle cells play in vessel calibre control and how this work has added to our understanding of TGFβ superfamily signal transduction.
The formation of skeletal muscle: from somite to limb
Authors: Buckingham Margaret , Bajard Lola , Chang Ted , Daubas Philippe , Hadchouel Juliette , Meilhac Sigolène , Montarras Didier , Rocancourt Didier , Relaix Frédéric 
Published: March 2003

AbstractDuring embryogenesis, skeletal muscle forms in the vertebrate limb from progenitor cells originating in the somites. These cells delaminate from the hypaxial edge of the dorsal part of the somite, the dermomyotome, and migrate into the limb bud, where they proliferate, express myogenic determination factors and subsequently differentiate into skeletal muscle. A number of regulatory factors involved in these different steps have been identified. These include Pax3 with its target c‐met, Lbx1 and Mox2 as well as the myogenic determination factors Myf5 and MyoD and factors required for differentiation such as Myogenin, Mrf4 and Mef2 isoforms. Mutants for genes such as Lbx1 and Mox2, expressed uniformly in limb muscle progenitors, reveal unexpected differences between fore and hind limb muscles, also indicated by the differential expression of Tbx genes. As development proceeds, a secondary wave of myogenesis takes place, and, postnatally, satellite cells become located under the basal lamina of adult muscle fibres. Satellite cells are thought to be the progenitor cells for adult muscle regeneration, during which similar genes to those which regulate myogenesis in the embryo also play a role. In particular, Pax3 as well as its orthologue Pax7 are important. The origin of secondary/fetal myoblasts and of adult satellite cells is unclear, as is the relation of the latter to so‐called SP or stem cell populations, or indeed to potential mesangioblast progenitors, present in blood vessels. The oligoclonal origin of postnatal muscles points to a small number of founder cells, whether or not these have additional origins to the progenitor cells of the somite which form the first skeletal muscles, as discussed here for the embryonic limb.
Differentiation, growth and morphogenesis:Acetabulariaas a model system
Authors: VANDEN DRIESSCHE THÉRÈSE , VRIES GHISLAINE M. PETIAU‐DE , GUISSET JEAN‐LUC 
Published: March 2003

SUMMARYThe aim of this paper is to review the present knowledge of the main aspects of differentiation ofAcetabularia, a unicellular, eukaryotic organism, and to underline the multiple control pathways modulated by circadian rhythmicity. Growth and morphogenesis are sequentially programmed. Timing of cap differentiation is highly dependent on external conditions. The importance of the sequence of processes is shown by experimental disregulation.The alga is a highly polarized cell, both in morphology and in the relative concentrations of a number of the molecules it contains. Apical cap differentiation is regulated at the post‐transcriptional level and could also depend in part on polyamines and on proteolytic activity.Acetabulariadisplays a number of circadian rhythms (CR). These rhythms form an elaborate biological time structure (also called temporal morphology, or morphology in time as opposed to morphology in space): the distribution in the 24 h cycle of the peaks and troughs of the oscillating functions. The oscillations display fixed relations both with the other functions and with external conditions (such as the transition from dark to light). Interestingly, the CR modulateAcetabularia'sdevelopment, which is influenced by photoperiod; we present preliminary experiments suggesting that disruption of temporal morphology is deleterious to morphogenesis.Induction of growth and of morphogenesis are totally dependent on blue light. However, blue light receptors in plants arc probably multiple, but we present arguments suggesting that flavin‐cytochrome b and the associated KHAM‐sensitive molecule are present inAcetabulariaplasma membrane and are involved in blue light perception. Agents interfering with different steps of signal perception and transduction show that at least some of these steps are temporally regulated. According to recent experiments from our laboratory, the existence of a redox signalling mechanism appears to be highly probable.The phytohormones (or plant regulators), auxin (indole acetic acid), abscisic acid and ethylene, exert cell‐regulatory functions and are involved inAcetabulariadifferentiation. They also modulate at least some circadian rhythms. Finally, circadian rhythms intervene in differentiation and are proposed to have an integrative function.CONTENTSSummary1I.Introduction: the cell cycle and morphology ofAcetabularia2II.Growth and cap morphogenesis: the developmental programme3III.Polarity5IV.Temporal morphology6V.Induction of growth and cap morphogenesis9VI.The plasma membrane12VII.Hormones: development and metabolic activity inAcetabularia12VIII.Phytohormones receptors and insulin receptors15IX.Other possible hormones16X.Fundamental role of CR: their intervention in modulating multiple steps in differentiation16XI.Conclusions and perspectives17Acknowledgements17References17
Mechanical impedance of root growth directly reduces leaf elongation rates of cereals
Authors: YOUNG I. M. , MONTAGU K. , CONROY J. , BENGOUGH A. G. 
Published: March 2003

SUMMARYA dry soil is generally a hard soil. Thus, the effects of water stress and mechanical impedance on plant growth are difficult to separate. To achieve this we have developed a growth cell that allows manipulation of the strength of growth media (i.e. mechanical impedance) without altering the availability of water or nutrients. We monitored leaf elongation rates of barley and wheat seedlings before and after the mechanical impedance to root growth was increased. Results show that a large and rapid reduction (within 10 min) of leaf elongation rates occurred after impedance to the roots was increased. The average reductions for barley and wheat, with associated standard errors, were 22.6 % (4.84) and 36.2% (5.48), respectively. The data are consistent with the hypothesis that mechanical impedance of roots might have a direct negative effect on leaf growth even where nutrients and water are in plentiful supply to the plant. The implications of the rate of the response are examined with respect to the underlying mechanisms controlling root‐shoot signalling.
Ozone uptake inPrunus serotina, Acer rubrumandQuercus rubraforest trees of different sizes
Authors: SAMUELSON L. J. , KELLY J. M. 
Published: March 2003

SUMMARYInformation on ozone uptake by various tree species has been derived mainly from controlled‐exposure studies of seedlings. Parallel measurements of foliar physiological processes in large trees are rare, as are measurements of local ozone concentrations within forest environments. Thus, our objectives were to characterize foliar ozone uptake in forest trees of different size and to identify a mechanistic linkage between small and large trees. Light‐saturated net photosynthesis (Pn), stomatal conductance (gH2O), and ozone uptake (gO23) in seedling (< 2 m), sapling (2–5 m) and mature (9–21 m) black cherry (Prunus serotinaEhrh.), northern red oak (Quercus rubraL.) and red maple (Acer rubrumL.) trees were measured monthly over two growing seasons at sites at high (1240 m) and low (600 m) elevation in the Great Smoky Mountains National Park. Seasonal ozone dose to northern red oak and red maple in the upper crown of mature trees was approx. double that of respective understorey seedlings and saplings. Seasonal ozone dose to black cherry was up to six times greater in mature trees than in seedlings and saplings. The lower ozone dose to understorey trees was mainly a function of lower gH2o, although canopy gradients in ozone concentration were indicated. Differences inPnandgH2O between small and large deciduous forest trees were linked to variation in nitrogen concentration expressed on a leaf area basis.
Biological control of pathozone behaviour and disease dynamics of Rhizoctonia solani by Trichoderma viride
Authors: BAILEY D. J. , GILLIGAN C. A. 
Published: March 2003

SUMMARYThis paper presents and tests a method to scale up from the dynamics of infection and disease on single plants in order to predict the behaviour of epidemics in populations of plants, in the presence of a biological control agent. Specifically, we quantify the effect of the antagonistic fungus, Trichoderma viride, Pers ex. Gray, on the pathozone dynamics of the damping‐off fungus, Rhizoctonia solani Kühn on radish. The results from these individual‐based experiments are used to predict the progress of an epidemic and the results are compared with experimental epidemics in microcosms. The addition of T. viride close to a germinating radish plant reduced the extent of the pathozone influence from 22.6 to 13.8 mm. Trichoderma viride also inhibited the evolution of infection efficiency of R. solani. The evolution of infection efficiency over time is described by a simple non‐linear model for the probability of infection with distance, in which certain of the parameters vary with time. By combining this with a model based on conditional probabilities for the location and infectivity of randomly dispersed propagules within the pathozone, we were able to scale up and predict the disease progress of R. solani in a population of radish plants, and the extent of control effected by T. viride. Disease progress rose progressively to a maximum of 42 % diseased plants in the unprotected crop compared with a sigmoidal approach to 13 % in the protected crop. We show that these properties are consistent with a monomolecular function for primary infection with a temporally‐varying rate parameter. We also show that the central region of the pathozone, where the joint probabilities of occurrence of a randomly located propagule and its ability to infect are maximal, has a large influence on the sensitivity of epidemics to pathozone dynamics. This is an important example of interpreting population behaviour of an epidemic from the infection and disease of single plants.
Structural diversity in (vesicular)–arbuscular mycorrhizal symbioses
Authors: SMITH F. A. , SMITH S. E. 
Published: March 2003

summaryThis review describes diversity in the structure of (vesicular)‐arbuscutar (VA) mycorrhizas, i.e. endomycorrhizas formed by Glomalean fungi. In particular, we consider the extent in the plant kingdom of the two classes first described by Gallaud (1905). These are: (1) the Arum‐type, defined on the basis of an extensive intercellular phase of hyphai growth in the root cortex and development of terminal arbuscules on intracellular hyphai branches; (2) the Paris‐type, defined by the absence of the intercellular phase and presence of extensive intracellular hyphai coils. Arbuscules are intercalary structures on the coils. However, there have been many reports that in Paris‐types arbuscules are relatively few in numbers, small, or absent altogether.A survey of the literature has revealed that Paris‐types occur more frequently in the plant kingdom than Arum‐types and predominate in ferns, gymnosperms and many wild angiosperms. The cultivated herbs that are the subject of much experimental work are mostly Arum‐types. Although evidence is still limited, there are differences at the family level. In 41 angiosperm families there are records of only Poris‐type VA mycorrhizas and in 30 families records of only Arum‐types. Another 21 families have examples of both classes, or intermediates between them. Accordingly, we consider whether the original division into two classes is still useful. We conclude that it is when considering the physiology of the symbiosis and especially the issue of whether different fungus/host interfaces have specialized roles in transfer of inorganic nutrients and organic carbon between the partners, if there is no such specialization between hyphai coils and arbuscules, then the latter might not be necessary1 for the function of Paris‐types. This would account for reports of the infrequency or absence of arbuscules in this class. The control exerted on structures by the genomes of host and fungus, and possible reasons (anatomical and physiological) for the existence of the VA mycorrhizal structures, are discussed. The presence or absence of extensive intercellular spaces and differences in the wall structure of cortical cells might be particularly important in determining which type of VA mycorrhiza is formed.

CONTENTS

Summary
373

I.
Introduction: Arum‐types and Pom‐types
374

II.
Possible functional implications
375

III.
Extent of the two classes in the plant kingdom
377

IV.
Is the distinction between classes useful?
383

V.
The structural basis
383

VI.
The role of the fungal genome
384

VII.
Physiology revisited
384

VIII.
Conclusions
385

Acknowledgements
386

References
386
Surface tension and viscosity of axenic maize and lupin root mucilages
Authors: READ D. B. , GREGORY P. J. 
Published: March 2003

summaryIn many plants, mucilage permeates the interface between root and soil, yet little is known about its physical properties or its influence on the physical properties of the rhizoasphere. Mucilage was collected from 3–4‐d‐old, axenically‐grown maize (Zea mays L. cv. Freya) and lupin (Lupinus angustifolius L. cv. Merrit) seedlings. Surface tension and viscosity were measured over a range of mucilage hydration, and neutral sugar analyses of the hydrolysed mucilages were obtained by gas chromatography. Surface tension of both maize and lupin mucilage was reduced to ∼ 48 mN m−1 at total solute concentrations > 0.7 mg ml−1, indicating the presence of powerful surfactants. Mucilage viscosity increased with increasing solute concentration and decreasing temperature. At a total solute concentration of 0.7 mg ml−1, the viscosity of maize mucilage at 20 °C was 2.1 mPa s (approx. double that of pure water), increasing to 3.3 mPa s at 5 °C. Both maize and lupin mucilage showed viscoelastic behaviour. The major component of maize mucilage was found to be glucose, but in lupin it was fucose.The surface tension and viscosity results support the idea that mucilage plays a major role in the maintenance of root‐soil contact in drying soils. As surface tension decreases, the ability of the mucilage to wet the surrounding soil particles becomes greater. Also, as viscosity and elasticity increase, the resistance to movement of any soil particles in contact with the mucilage increases, a degree of stabilization of the rhizosphere structure is achieved and hydraulic continuity is maintained. It is unclear whether the surfactant is actively secreted by the root or is present simply as a result of leakage from root cells.
An image‐analysis technique for accurate counting of pollen on stigmas
Authors: BECHAR A. , GAN‐MOR S. , VAKNIN Y. , SHMULEVICH I. , RONEN B. , EISIKOWITCH D. 
Published: March 2003

summaryPollen counting is an important element of research in pollination, and the majority of current methods involve manual counting. An image‐processing technique has been developed for accurate counting and sizing of small particles, and this was tested on almond pollen grains. Our automatic process was found to be several times faster than manual counting and more accurate, with an average error of only 3 %. Because of its simplicity, it is an attractive tool for research on such topics as pollen viability or germination. It was found that in the methods using vials there were ‘residues’ of c. 17 % on the vial walls and on the handling tools. In addition, the first drop from each vial contained, on average, 1–65 times more grains than the average number of grains in all drops, whereas the last drop from each vial contained fewer grains than the average. This phenomenon was correlated with the non‐uniform pollen distribution in the suspension. An automatic counting system is therefore, recommended, to avoid the problem, otherwise a calibration procedure should be used that accounts for both the residues on the tools and the non‐uniformity of contents of sample drops.