Denaturing gradient gel electrophoresis detection of polymorphism in a PCR fragment of sheep epidermal growth factor gene

The ovine map is not yet well-developed, which represents a problem when looking for markers of a region of interest in sheep. A means of circumventing this is to use comparative mapping. In this study primers were determined using consensus sequences for the epidermal growth factor gene of humans, rats and mice, and an ovine epidermal growth factor gene fragment was amplified by polymerase chain reaction (PCR). A new set of specific ovine primers was chosen to study the polymorphism of this DNA fragment by denaturing gradient gel electrophoresis. Eighty-four individuals belonging to seven sheep breeds were studied with this technique and four alleles were detected. The heterozygosity rate was 0.57. Family analysis showed mendelian inheritance of the alleles. Usually, genetic analysis of type-I loci used in the comparative mapping is based on the detection of restriction fragment length polymorphisms in sheep DNA using cDNA probes from other species. Our work shows that another method, based on PCR and denaturing gradient gel electrophoresis techniques, can be efficiently used.     

Intraspecific variation of Eolophiodon laboriense,a basal Lophiodontidae (Mammalia,Perissodactyla) from the early Eocene of Southern France

The Lophiodontidae is an emblematic and well-documented Eocene family of perissodactyls from Western Europe. However, after more than a century and a half of studies, lophiodontids still display a complex systematics associated with blurry intraspecific variation and a poorly known early radiation. The locality of La Borie, located near the city of Toulouse, France, has yielded numerous remains of Eolophiodon laboriense. This abundance of remains allows for the first time the study of the intraspecific variation of a basal lophiodontid. The variation has been investigated for dental and cranio-mandibular characters, notably dental polymorphism, size variation and sexual dimorphism. The intraspecific variation of E. laboriense is high with more than 20 polymorphic characters of the dentition, including many additional crests and conules. This dental polymorphism is similar to the one observed in the Bartonian lophiodontid Lophiodon lautricense. E. laboriense also displays an important degree of sexual dimorphism, with male specimens having broader and longer mandibles with larger canines than females. Despite this high intraspecific variation, the low size variation of teeth and the consistency of diagnostic characters strengthen the validity of the genus Eolophiodon and does not impact the previous lophiodontid phylogeny.     

A three-step screening procedure to identify the mode of phloem loading in intact leaves

A three-step screening method was developed to identify the mode of phloem loading in intact leaves. Phloem loading of ¹⁴CO₂-derived photosynthate was challenged by p-chloromercuribenzenesulfonic acid (PCMBS) in leaves of dicotyledons with either a symplasmic (type 1, with intermediary cells as companion cells) or apoplasmic (type 2b, with transfer cells as companion cells) minor-vein configuration. Firstly, photosynthate export as the result of phloem loading was measured by collection of phloem exudate from the petiole. The PCMBS had virtually no effect on photosynthate export in representatives of type-1 families (Lamiaceae, Lythraceae, Onagraceae, Saxifragaceae). In contrast, photosynthate export was strongly reduced by PCMBS in representatives of type-2b families (Asteraceae, Balsaminaceae, Dipsacaceae, Linaceae, Tropaeolaceae, Valerianaceae) and type-2b members of polytypical families (Fabaceae, Scrophulariaceae). Secondly, densitometric measurements of leaf autoradiographs demonstrated that the contrast between the mesophyll and the lower-order veins was hardly affected by PCMBS treatment in type-1 species, whereas PCMBS strongly reduced the contrast in type-2b species. Thirdly, separate ¹⁴C-radioassays of vein and mesophyll tissues confirmed this observation. The three-step procedure thus revealed a strong and consistent reduction of phloem loading by PCMBS in type-2b species which was absent in type-1 species. In conclusion, phloem loading in type-2b species occurs via the apoplast and type-1 species execute an alternative — most likely symplasmic — mode of phloem loading.Abbreviations PCMBS p-chloromercuribenzenesulfonic acid - SE/CC-complex sieve element/companion cell complex We gratefully acknowledge the expert help of Dr. Maarten Terlou, Department of Image Processing and Design, University of Utrecht, in carrying out the densitometric measurements.     

Environmental regulation of surface conductance for evaporation from vegetation

We examine conductances for evaporation from both vegetation and soil in response to environmental variables. Data from a vertically-structured pristine forest of Nothofagus are presented as an example of the effects of biodiversity on the scaling of conductances between tiers of plant organisation. Available data sets of maximum leaf stomatal conductances (g _lmax ) and bulk vegetation surface conductances (G _smax ) are compared. Overall, the ratio G _smax /g _lmax is consistently close to 3 for seven major vegetation types of diverse structure. An analytical model accounts for this close relationship, and in particular how G _smax is conservative against changes in leaf area index because of the compensating decrease in plant canopy transpiration and increase in soil evaporation as leaf area index diminishes. The model is also successfully tested by comparison with canopy conductances of emergent trees measured in the Nothofagus forest. The constraint of vegetation surface conductance and evaporation via environmental regulation by irradiance, air saturation deficit and root zone water supply are discussed.     

Choline transport in Fusarium graminearum A 3 5

Fusarium graminearum A 3/5 possesses a high affinity system (Km = 32 +/- 8 microM; mean +/- SE) for uptake of choline, which was shown to be energy-dependent and constitutive. The maximum rate of choline uptake by this system was repressed by ammonia and glucose, showing a three-fold increase in maximum activity after nitrogen (2 h) or carbon (4 h) starvation. The system was highly specific for choline with only dimethylethanolamine (Ki = 198 +/- 29 microM), betaine aldehyde (Ki = 95 +/- 14 microM) and chlorocholine (Ki = 352 +/- 40 microM) acting as competitive inhibitors. Hemicholinium-3 acted as a mixed (non-competitive) inhibitor (KIES = 1.9 +/- 0.6 microM; KIE = 3.6 +/- 1.9 microM).     

Morphological characteristics in relation to diet in five coexisting Thai fish species

Morphological characteristics and intestinal content were analysed for five species of coexisting freshwater fishes in Thailand: Rasbora caudimaculata , Schistura desmotes , Dermogenys pusillus , Xenentodon cancila and Monopterus albus (all found in riffle habitats in Thai streams). Rasbora caudimaculata , S. desmotes and D. pusillus fed predominantly on ephemeropterans, hymenopterans and dipterans, X. cancila fed predominantly on fishes, and larger aquatic invertebrates such as Odonata, and M. albus fed on detritus as well as invertebrate prey such as crustaceans and Odonata. Intestine length, mouth height, mouth width, eye position and mouth orientation varied among all five species. Canonical analysis of discriminance of mouth height, width and intestine length showed a clear dispersion of species, which was supported by intestine content. Evolutionary processes leading to the present differences in morphological characters resulted in each of the five species consuming a different portion of the available resource base, thereby facilitating coexistence.     

Taxonomic notes on the genus Crataegus (Rosaceae) in Turkey

The Turkish Crataegus taxa were investigated using morphological, palynological, and anatomical characters. A new series ( Crataegus Section Crataegus Series Peshmenia ), two new species ( Crataegus peshmenii and Crataegus christensenii ), and one variety ( Crataegus rhipidophylla var. kutahyaensis ) are described. Furthermore, Crataegus  ×  browicziana has been assigned to Crataegus rhipidophylla with a new status. Illustrations of the described taxa and their distribution map are also given. The lectotype for Crataegus yaltirikii is designated here.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 231–240.     

“Templatic backcopying” in Guarijio abbreviated reduplication

Although a wide array of phonological properties seem to backcopy in reduplication, it is an open question whether reduplicative templates can backcopy as well. It has been argued that natural languages do not have reduplicative constructions where the base truncates to match the truncated reduplicant (McCarthy & Prince, 1994; McCarthy & Prince, 1999; Spaelti, 1997; inter alia). In Guarijio Abbreviated Reduplication (Miller, 1996), however, both copies of the reduplicative construction truncate, instantiating the pattern that has been claimed not to exist. This paper argues that the Guarijio case fills this typological gap. Although the data can be given a templatic backcopying analysis, this paper defends a Morphological Doubling Theory (MDT) analysis using cophonologies (Inkelas & Zoll, 2005). In MDT, Guarijio Abbreviated Reduplication results from the parallel imposition of a truncating cophonology in each copy of the reduplicative construction. Guarijio Abbreviated Reduplication is predicted to exist by MDT together with other documented cases of parallel phonological modification in reduplication. I am grateful to many people for helpful comments and suggestions, including Isabel Barreras Aguilar, Laura Downing, Nicholas Fleisher, Andrew Garrett, Jason Haugen, Larry Hyman, Yuni Kim, Teresa McFarland, David Mortensen, Mary Paster, Eric Raimy, and Timothy Thornes as well as the audience of the LSA 2005 Annual Meeting in Oakland. I would like to extend a special thanks to Alan Yu for his detailed comments and suggestions to latter versions of this paper. I am particularly indebted to Sharon Inkelas, for her generous advice, feedback, and numerous discussions throughout the development of this paper. I am also grateful to two anonymous reviewers for their comments and criticisms, and especially to Ingo Plag for his patience and detailed suggestions as editor. All remaining errors and omissions are mine. This study was made possible by fellowships by CONACYT (Consejo Nacional de Ciencia y Tecnología, México), the University of California Institute for Mexico and the United States (UCMEXUS) and Fulbright.