bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolution of the structure and function of the vertebrate tongue
Authors: Iwasaki Shin‐ichi 
Published: March 2003

AbstractStudies of the comparative morphology of the tongues of living vertebrates have revealed how variations in the morphology and function of the organ might be related to evolutional events. The tongue, which plays a very important role in food intake by vertebrates, exhibits significant morphological variations that appear to represent adaptation to the current environmental conditions of each respective habitat. This review examines the fundamental importance of morphology in the evolution of the vertebrate tongue, focusing on the origin of the tongue and on the relationship between morphology and environmental conditions. Tongues of various extant vertebrates, including those of amphibians, reptiles, birds and mammals, were analysed in terms of gross anatomy and microanatomy by light microscopy and by scanning and transmission electron microscopy. Comparisons of tongue morphology revealed a relationship between changes in the appearance of the tongue and changes in habitat, from a freshwater environment to a terrestrial environment, as well as a relationship between the extent of keratinization of the lingual epithelium and the transition from a moist or wet environment to a dry environment. The lingual epithelium of amphibians is devoid of keratinization while that of reptilians is keratinized to different extents. Reptiles live in a variety of habitats, from seawater to regions of high temperature and very high or very low humidity. Keratinization of the lingual epithelium is considered to have been acquired concomitantly with the evolution of amniotes. The variations in the extent of keratinization of the lingual epithelium, which is observed between various amniotes, appear to be secondary, reflecting the environmental conditions of different species.
Keratinization and ultrastructure of the epidermis of late embryonic stages in the alligator (Alligator mississippiensis)
Authors: Alibardi Lorenzo , Thompson Michael B. 
Published: March 2003

AbstractUsing specific anti‐β keratin and general anti‐α keratin antibodies, keratins were located in the epidermis of the alligator during the final developmental stages by ultrastructural and immunocytochemical methods. The maturation of the bilayered periderm (= embryonic epidermis) coincides with the disappearance of cell organelles, including the 25–35‐nm‐thick coarse filaments, and the coalescing of α‐keratin filaments into a compact mass. The plasmalemma of peridermal cells forms a 15–25‐nm‐thick electron‐dense corneous envelope. These changes start at stage 25, about 3 weeks before hatching, and continue until hatching when the embryonic epidermis is shed. Immature β‐keratogenic cells beneath the embryonic epidermis accumulate immunolabelled β‐filaments which are packed into thin, electron‐pale β‐keratogenic cells in the corneous layer. Together, electron‐pale and electron‐dense materials form a compact 3–4‐nm filament pattern of β‐keratin. Melanosomes from epidermal melanocytes, incorporated into β‐cells, give rise to the banded skin pattern of hatchlings. β‐keratin production is much reduced in the hinge regions, where many α‐filaments remain packed together with lipid droplets or mucous granules into thinner, more electron‐dense, α‐cells. The keratinaceous material of the α‐cells is mostly concentrated along the cell membrane, while the lipid/mucous material remains centrally located, as in sebokeratinocytes of the apteric areas of avian skin. Some lipid and mucus is also incorporated into typical β‐cells of the outer scale surface, so that lipids are part of the fully keratinized hard keratin layer of the alligator. Lipids within β‐cells of outer scale surfaces and α‐cells of the hinge region are probably responsible for limiting water loss and ion movements across the skin. Neither typical mammalian keratohyalin granules nor lepidosaurian keratohyalin‐like granules were detected anywhere in alligator epidermis. The combination of anti‐β and anti‐α keratin antibodies revealed different distributions of β‐ and α‐keratins. In late embryonic stages (25–26 to hatching), β‐keratin occurs only in the upper suprabasal cells, in prekeratinized and keratinized layers, whereas α‐keratin bundles (tonofilaments) remain only in the lowest layers. The cross‐reactivity of the β‐antibody, produced against a chick scale keratin, further shows that avian and crocodilian hard (β) keratins share common antigenic sites, reflecting a phylogenetic affinity between these taxa.
Two generations of the tongue and gustatory organs in the development of Hynobius dunni Tago
Authors: Żuwała K. , Kato S. , Jakubowski M. 
Published: March 2003

AbstractIn the development of Hynobius dunni there are two consecutive generations of the tongue and two generations of gustatory organs (taste buds and taste disks). The anlage of the developing secondary tongue appears just in front of the free ending of the primary tongue beginning at the larval developmental stage 62. From stage 67, a gradual reduction in the anterior part of the gill skeleton that supports the primary tongue occurs as the developing secondary tongue replaces the primary one. The lining of the entire oropharyngeal cavity of larvae contains only gustatory organs of the taste bud (TB) type. In younger larvae, the sensory area of a TB has a diameter of between 10 and 13 µm, while in older larvae, TBs reach 16–18 µm in diameter. After metamorphosis, some gustatory organs in the secondary tongue with a sensory area of 26–36 µm in diameter appear. In older animals they may reach as much as 56–71 µm. In other regions of the oropharyngeal epithelium than the tongue, these organs have an ellipsoid shape with a major axis of about 50 µm. On the basis of the cytomorphological criteria established previously, these organs were designated as taste disks. Thus, the presence of two generations of gustatory organs is characteristic of some urodeles, as well as frogs.
Infectivity of the propagules associated with extraradical mycelia of two AM fungi following winter freezing
Authors: ADDY H. D. , MILLER M. H. , PETERSON R. L. 
Published: March 2003

SUMMARYAbuscular mycorrhizal fungi are thought to survive adverse environmental conditions primarily as spores. Extraradical mycelia of two Glomus species were produced in fine mesh pouches which excluded roots but not hyphae. The mycelia in these pouches were exposed to freezing conditions, either in the field or in a controlled–temperature chamber. Bioassay plants were grown directly in the pouches and mycorrhizal colonization was assessed after 1 month. The mycelia remained infective in frozen soil over winter. This survival was not dependent on either the presence of root pieces or on the connection of mycelia to roots. Spores were not an effective inoculum in these bioassays. Overwinter survival of mycelia would enable plants to become incorporated into functional mycorrhizal associations early in spring.
A comparative study of leaf nutrient concentrations in a regional herbaceous flora
Authors: THOMPSON KEN , PARKINSON JOHN A. , BAND STUART R. , SPENCER RITA E. 
Published: March 2003

SUMMARYMineral nutrient concentrations were determined in leaves of 83 mostly herbaceous species collected from central England. Most samples were analysed for N, P, K, Ca, Mg, Na, Fe, Al, Mn, Cu and Zn. Concentrations of K, N and P showed similar levels of interspecific variability, with the highest concentrations being 6–9 times the lowest. Mg and (especially) Ca were much more variable, with the highest concentrations being 24 and 49 times the lowest respectively. Only in the case of P concentration was the majority of the variance in the data found at or below the species level. Most of the variance in Ca and Mg concentrations was between monocots and dicots. Concentrations of N and P were strongly positively correlated with each other. Only Ca and Mn were consistently associated with soil pH, positively and negatively respectively. Dicots tended to accumulate more Ca and Mn from high soil concentrations than did monocots. Concentration of P was significantly positively correlated with maximum potential relative growth rate. Plants of woodland and arable habitats contained high concentrations of P, and those of pasture and skeletal habitats contained low concentrations of P. The P: N ratio was higher in plants of arable habitats. Species with P‐rich leaves tended to be currently increasing in abundance. The results suggest that plants with nutrient‐rich foliage grow quickly, dominate nutrient‐rich ecosystems and are generally increasing as a result of the eutrophication and disturbance arising from human exploitation.
Identification of four starch‐branching enzymes in barley endosperm: partial purification of forms I, IIa and IIb
Authors: SUN CHUANXIN , SATHISH P. , AHLANDSBERG STAFFAN , DEIBER ANNA , JANSSON CHRISTER 
Published: March 2003

summaryDeveloping caryopses of barley (Hardeum vulgare L. ev. Golf) were monitored for starch‐branching enzyme activity for 1 month after anthesis. Homogenized caryopses from grains with the highest specific activity were used as starting material for purification of branching enzyme by FPLC chromatography. Several branching enzyme activity fractions were resolved. We have previously described the isolation of a 51/50 kDa protein with starch branching activity from one of these fractions. From three other fractions, we have now partially purified starch branching enzymes corresponding to forms I, IIa and IIb.
Identification of cultivar‐specific leghaemoglobin components in Pisum sativum
Authors: ULRICH KRISTINA , LENTZSCH PETER , SEYFARTH WOLFGANG 
Published: March 2003

summaryThe components of leghaemoglobin (Lb) from twelve different Pisum sativum L. cvs and three near‐isogenic foliar mutants were investigated by anion‐exchange high‐performance liquid chromatography (HPLC). Five different Lb component profiles could he found. The number of components varied from four to six dependent on cultivar used. An Lb pattern composed of four Lb components could be detected in thirteen P. sativum cultivars and lines. Ten of them showed an identical profile. In nodules of each cultivar, the two known major components, LbI and LbV, but also LbIV, could be detected. Additionally, cultivar‐specific Lb components could be identified, each representing up to 10%, of total Lb. One of these components, LbIII, has been described previously, but three new Lb components (LbII, LbVI, and LbVII) were found. The presence of all Lb components detected by HPLC was confirmed by analytical isoelectric focusing. Further, it was shown that age‐dependent changes in the relative concentrations of LbI and LbV are common in P. sativum and that these variations are independent of breeding lines and cultivars.
The occurrence of crassulacean acid metabolism among vascular epiphytes from Central Panama
Authors: ZOTZ G. , ZIEGLER H. 
Published: March 2003

summaryThe occurrence of crassulacean acid metabolism (CAM) among the epiphyte flora of the lowland forest on Barro Colorado Island (BCJ), Panama, was investigated. A total of 116 species was included, i.e. about 2/3 of the known epiphyte taxa. As judged from the carbon isotope ratios and the absence of Kranz anatomy, indications of CAM were found in 29 species of three families, Orchidaceae (20), Bromeliaceae (7), and Cactaceae (2). We estimate that about 25% of the epiphyte flora of BCI are CAM plants. CAM was most prevalent in exposed sites, but even in the understorey two epiphyte species engage in CAM.
Partitioning of 14C‐labelled photosynthate to developing nodules and roots of soybean (Glycine max)
Authors: HACIN JANEZ I. , BOHLOOL B. BEN , SINGLETON PAUL W. 
Published: March 2003

summaryA split‐root growth system was used to study photosynthate partitioning to developing nodules and roots of soybean (Glycine max L., Merr). Opposite sides of the root systems were inoculated with Bradyrhizobium japonicum at 8 and 12 d after planting (early/delayed inoculation treatment) or, alternatively, only one side was inoculated 8 d after planting (early/uninoculated treatment). Plants were incubated with 14CO2 at 24‐h intervals from early inoculation until the onset of N2 fixation (acetylene reduction). After staining with Eriochrome black, root and nodule meristematic structures were excised under a dissecting microscope and their radioactivity determined by scintillation counting. The specific radioactivity of nodule structures increased with nodule development, and was as much as 4 times higher in early nodules than in roots and nodules on half‐roots receiving delayed inoculation By the time that N2 fixation could be measured in the first mature nodules, the early inoculated half‐root contained over 70% of the radioactivity recovered from the entire root systems of both early/delayed and early/uninotulated treatments. These results suggest that developing nodules create a strong sink for photosynthate, and that nodules and roots compete for current photosynthate. Early initiated nodules might develop at the expense of late initiated nodules, as well as at the expense of the roots themselves.
Genetic analysis and physiology of a trait for enhanced K+/Na+ discrimination in wheat
Authors: GORHAM J. , BRIDGES J. , DUBCOVSKY J. , DVORAK J. , HOLLINGTON P. A. , LUO M.‐C. , KHAN J. A. 
Published: March 2003

summaryVariation for K+ and Na+ accumulation at low salinities in hydroponic (water) culture were observed in shoots of different wheat species. Greater discrimination (in favour of K+ and against Na+ accumulation) was shown by hexaploid bread wheat (Triticum aestivum L.) than by tetraploid durum wheat (T. turgidum L.). Since Aegilops tauschii Cosson (A. squarrosa L.), the source of the D genome in bread wheat, also exhibited high discrimination between K+ and Na+, it was concluded that the character resided in the D genome. Studies of aneuploid bread wheat lines and disomic substitution lines of D genome chromosomes for their A and B genome homoeologues in durum wheat cv. Langdon revealed that the trait was controlled by the long arm of chromosome 4D. Since the aneuploid and disomic substitution lines showed better relative salt tolerance than durum wheat, but had lower yield potentials, we recombined chromosome 4D with chromosome 4B in a tetraploid wheat background using a homoeologous pairing mutant. This produced families of 4D/4B recombinant lines, some of which exhibited the enhanced K+/Na+ discrimination trait. RFLP analysis confirmed that the trait was controlled by a single gene (Kna1) which was completely linked to five markers on the distal third of the long arm of 4D. A second cycle of homoeologous recombination was employed to remove the distal 4D genetic material from the recombined Kna1 4B/4D chromosome and to map Kna1 in greater detail. By this strategy, Kna1 was mapped within a short 2 cM region. Genetic analysis of K+: Na+ ratios showed very high LOD scores in this region for plants grown in solution culture, but lower values for plants grown in the field.In general, recombinant lines which exhibited the enhanced K+/Na+ trait were slightly more tolerant of salinity in the field and in sand culture than recombinants lacking the trait. There was, however, considerable variation between individual lines. Ion discrimination and relative tolerance were also higher in a Kna1 recombinant (line no. R3) than in a kna1 recombinant (line no. R165) in sodic conditions. In these two lines the enhanced K+/Na+ discrimination trait did not alter responses to low potassium or calcium supply.
Introgression of salt‐tolerance genes from Thinopyrum bessarabicum into wheat
Authors: KING IAN P. , FORSTER BRIAN P. , LAW COLIN C. , CANT KAREN A. , ORFORD SIMON E. , GORHAM JOHN , READER STEVE , MILLER TERRY E. 
Published: March 2003

summarySalt‐affected soil is a major problem and has led to large areas of the earth's surface being unable to support agriculture. Wheat is not tolerant to high levels of salt; however, a number of its wild relatives, in particular Thinopyrum bessarabicum Savul. and Rayss, which grows on the Black Sea shore in the Crimea, are tolerant to high levels of NaCl. Thus the introgression of genes conferring salt tolerance from Th. bessarabicum into Triticum aestivum is one way in which salt‐tolerant wheat varieties can be produced. This paper reviews the progress made in developing salt‐tolerant wheat carrying Th. bessarabicum genes and salt‐tolerant wheat/Th. bessarabicum amphiploids.
Consequences of high loads of nitrogen for spruce (Picea abies) and beech (Fagus sylvatica) forests
Authors: RENNENBERG HEINZ , KREUTZER KARL , PAPEN HANS , WEBER PAUL 
Published: March 2003

High loads of nitrogen to spruce and beech forests can result in a complete inhibition of NO3− uptake by the roots of the trees. This conclusion is based on (a) a comparison of a field site continuously exposed to high loads of N and a N‐limited site, (b) the results of N fertilization of a N‐limited field site, and (c) laboratory experiments under controlled environmental conditions. From fertilization experiments in the field it appears that NH4+ uptake might become inhibited subsequent to an excessive uptake of NH4+. Apparently, the inhibition of NO3− uptake by high loads of N to forests is a consequence of an accumulation of organic amino compounds in the roots originating from phloem transport from the shoot to the roots. These amino compounds seem to signal the N demand of the shoot to the roots. At present this function cannot be attributed to an individual organic amino compound in beech or spruce, but Gln is a likely candidate in both species among other compounds, e.g. Glu in spruce or Asp in beech trees. Direct inhibition of NO3− uptake by NH4+ can be excluded from the present studies. The mechanism(s) by which elevated levels of particular organic amino compounds interact with NO3− uptake remains to be elucidated. This (these) mechanism(s) seem to affect NO3− influx rather than NO3− efflux. As a consequence of this (these) mechanism(s), spruce and beech trees can prevent, within a certain physiological window, N over‐nutrition when the roots are exposed to excessive amounts of inorganic N. However, inhibition of NO3− and NH4+ uptake by the roots makes more N available for leaching into the ground water and, in addition, for soil microbial processes that result in the production and re‐emission of volatile N compounds into the atmosphere.At the ‘Höglwald’ site, continuously exposed to high loads of N, >20% of the N input from throughfall into the spruce and beech plots is re‐emitted as NO and N2O. However, the NO to N2O ratio is highly dependent on the tree species, with a preference for NO in the spruce and a preference for N2O in the beech plot. Since at least part of the NO emitted from the soil will be converted inside the canopy in the presence of ozone to NO2 that might then be absorbed by the leaves, the portion of the N in the throughfall that will be released from the forest by gaseous N emission is higher in the beech than in the spruce plot. Leaching of NO3− into the ground water is high in the spruce, but minute in the beech plot. However, this positive effect of beech on ground water quality is achieved at the expense of an enhanced release of radiatively active N gases into the troposphere.
Actin versus tubulin configuration in arbuscule‐containing cells from mycorrhizal tobacco roots
Authors: GENRE A. , BONFANTE P. 
Published: March 2003

The involvement of the cytoskeleton in symbiotic interactions such as arbuscular mycorrhizas has received little attention. In this paper, we examine the organization of actin in tobacco mycorrhizal roots and compare actin and tubulin patterns within arbuscule‐containing cells.Our results show drastic reorganization of microfilaments and microtubules upon fungal infection and how those new cytoskeletal patterns relate to the host cytoplasm rearrangement and the intracellular fungal structures. Whereas in uninfected cells a network of cortical and perinuclear actin filaments was observed, in infected cells actin filaments closely follow the fungal branches and envelop the whole arbuscule in a dense coating network. Microtubules are less closely connected with the fungus surface. They run across the whole arbuscule mass, linking branches to each other and to the host cell cortex and nucleus.These major differences between the two cytoskeletal components are used to advance some suggestions concerning their contribution to structural functions in the plant–fungus interactions during the mycorrhizal symbiosis.
Tansley Review No. 104
Authors: McLAUGHLIN S. B. , WIMMER R. 
Published: March 2003

SummaryCalcium occupies a unique position among plant nutrients both chemically and functionally. Its chemical properties allow it to exist in a wide range of binding states and to serve in both structural and messenger roles. Despite its importance in many plant processes, Ca mobility is low, making Ca uptake and distribution rate a limiting process for many key plant functions. Ca plays an essential role in regulating many physiological processes that influence both growth and responses to environmental stresses. Included among these are: water and solute movement, influenced through effects on membrane structure and stomatal function; cell division and cell wall synthesis; direct or signaling roles in systems involved in plant defense and repair of damage from biotic and abiotic stress; rates of respiratory metabolism and translocation; and structural chemistry and function of woody support tissues. Forest trees, because of their size and age capacity, have been examined for evidence of limitations imposed by the timing and level of Ca supply. Examination of Ca physiology and biogeochemical cycling for forested systems reveals many indications that Ca supply places important limitations on forest structure and function. These limitations are likely to be most significant with older trees, later successional stages, high levels of soil acidity and/or high canopy Ca leaching losses, or under conditions where plant competition is high or transpiration is limited by high humidity or low soil moisture. Evidence of structural and physiological adaptations of forests to limited Ca supply; indicators of system dysfunction at many levels under reduced Ca supply; and the positive responses of diverse indicators of forest vitality in liming experiments indicate that Ca is more important to forest function and structure than has generally been recognized. Lack of recognition of Ca limitations is due in part to that fact some important plant functions are controlled by changes in very small physiologically active pools within the cytoplasm, and whole‐leaf Ca levels may not reflect these limitations. An additional aspect is the fact that Ca availability has declined significantly for many forests in just the past few decades. Additional research on the role of Ca supply in resistance of forests to disease, changes in structural integrity of woody tissues, restrictions on rooting patterns and function, and uptake of other nutrients, notably N, is needed. Increased understanding of the physiological ecology of Ca supply can be anticipated to provide important insights that will aid in future protection and management of both natural and commercial forest systems.

contents

Summary

I.
introduction – a hypothesis
374

II.
effects of calcium on physiological processes
376

III.
calcium uptake and distribution at the whole‐plant level
382

IV.
ecosystem processes and calcium supply
387

V.
plant and ecosystem responses to human alterations in calcium supply
391

VI.
conclusion
407

VII.
evaluation of the hypothesis
410

Acknowledgements
411

References
411