Keratinocytes Suppress TRP‐1 Expression and Reduce Cell Number of Co‐cultured Melanocytes – Implications For Grafting of Patients with Vitiligo

A pilot study for grafting of patients with vitiligo using cultured epithelial autografts containing melanocytes gave disappointing clinical results, with pigmentation achieved in only one out of five patients. Irrespective of the fate of melanocytes grafted back onto the patients, we experienced problems in identifying melanocytes within these well‐integrated keratinocyte sheets. This led us to explore the fate of these cells within these sheets in vitro and to seek to improve their number and function within the sheets. We report that the introduction of a fibroblast feeder layer can improve melanocyte number within melanocyte/keratinocyte co‐cultures initially, but at very high keratinocyte density, there is a marked loss of melanocytes (as detected by staining for S100). Additionally, we found that keratinocytes not only down‐regulate melanocyte number, but also pigmentary function; thus, it was possible to identify melanocytes that were S100 positive but tyrosinase‐related protein‐1 (TRP‐1) negative in confluent well‐integrated keratinocyte sheets. In summary, our data suggest that keratinocytes at high density initially suppress melanocyte pigmentation (as evidenced by a lack of TRP‐1 expression) and then cause a physical loss of melanocytes. The introduction of a fibroblast feeder layer can help maintain melanocyte number while keratinocytes are subconfluent, but fails to oppose the inhibitory influence of the keratinocytes on melanocyte TRP‐1 expression.     

A wheat canopy model for use in disease management decision support systems

A model is described which predicts those aspects of wheat canopy development and growth which are influential in determining the development of epidemics of foliar pathogens, the efficacy of foliar applied fungicides and the impact of disease on yield; specifically the emergence, expansion and senescence of upper culm leaves in relation to anthesis date. This focus on upper leaves allowed prediction of leaf emergence dates by reference to anthesis, rather than sowing. This avoided the step changes in flag leaf emergence date with temperature, reported with earlier models, without the additional complexity of a stochastic approach. The model is designed to be coupled to models of foliar disease, where the primary effect on yield is via reduction in green canopy area and hence interception of photosynthetically active radiation. Mechanisms were incorporated to allow observations of crop development during the growing season to update state variables and adjust parameters affecting future predictions. The model was calibrated using experimental data, and validated against independent observations of crop development on four wheat cultivars across seven contrasting sites in the UK. Anthesis date and upper culm leaf emergence were always predicted within one week of their observed dates.     

Revealing the hidden complexities of mtDNA inheritance

Mitochondrial DNA (mtDNA) is a pivotal tool in molecular ecology, evolutionary and population genetics. The power of mtDNA analyses derives from a relatively high mutation rate and the apparent simplicity of mitochondrial inheritance (maternal, without recombination), which has simplified modelling population history compared to the analysis of nuclear DNA. However, in biology things are seldom simple, and advances in DNA sequencing and polymorphism detection technology have documented a growing list of exceptions to the central tenets of mitochondrial inheritance, with paternal leakage, heteroplasmy and recombination now all documented in multiple systems. The presence of paternal leakage, recombination and heteroplasmy can have substantial impact on analyses based on mtDNA, affecting phylogenetic and population genetic analyses, estimates of the coalescent and the myriad of other parameters that are dependent on such estimates. Here, we review our understanding of mtDNA inheritance, discuss how recent findings mean that established ideas may need to be re‐evaluated, and we assess the implications of these new‐found complications for molecular ecologists who have relied for decades on the assumption of a simpler mode of inheritance. We show how it is possible to account for recombination and heteroplasmy in evolutionary and population analyses, but that accurate estimates of the frequencies of biparental inheritance and recombination are needed. We also suggest how nonclonal inheritance of mtDNA could be exploited, to increase the ways in which mtDNA can be used in analyses.     

Microstructure and mineralogy of the outer calcareous layer in the lower jaws of Cretaceous Tetragonitoidea and Desmoceratoidea (Ammonoidea)

Tanabe, K., Landman, N.H. & Kruta, I. 2011: Microstructure and mineralogy of the outer calcareous layer in the lower jaws of Cretaceous Tetragonitoidea and Desmoceratoidea (Ammonoidea). Lethaia, Vol. 45, pp. 191–199. Based on the differences in their relative size, overall shape, structure and the degree of development of an outer calcified covering, lower jaws of the Ammonoidea have been classified into four morphotypes: normal, anaptychus, aptychus and rhynchaptychus types. However, detailed microstructural and mineralogical comparison of these morphotypes has not yet been addressed. This article documents the results of SEM and XRD observations of the lower jaws of three Late Cretaceous ammonoid species belonging to the Tetragonitoidea (Anagaudryceras limatum) and Desmoceratoidea (Pachydiscus kamishakensis and Damesites aff. sugata), based on excellent material preserved in situ within the body chamber, and retaining an aragonitic shell wall. The lower jaws of the three species are assigned to an intermediate form between anaptychus and aptychus types for the first two species and the rhynchaptychus type for the third species. Their black, presumably originally chitinous outer lamella is wholly covered with a calcareous layer. The calcareous layer is composed of aragonite in D. aff. sugata and A. limatum, and calcite in P. kamishakensis. The microstructure of the outer calcareous layer differs among the three species, i.e. granular in A. limatum, spherulitic prismatic in D. sugata, and prismatic in P. kamishakensis, all of which can be distinguished from the lamellar and spongy structure of the outer‐paired calcitic plates of the typical aptychus‐type lower jaws in some Jurassic and Cretaceous Ammonitina and Ancyloceratina. Our study suggests that most Jurassic and Cretaceous ammonoids possessed an outer calcareous layer in their lower jaws, although its mineralogy, microstructure and relative thickness vary among different taxa. □Ammonoidea, Cretaceous, Desmoceratoidea, lower jaw, microstructure, Tetragonitoidea.     

A Neuroethological Study of Display Behavior in the Lizard Anolis Carolinensis (Reptilia, Lacertilia, Iguanidae)

A behavior inventory and ethogram for display behavior, an atlasof the principal forebrain nuclei and fiber tracts, and microtechniquesfor stereotaxic surgery were developed in conjunction with astudy of forebrain involvement in the display behavior of Anoliscarolinensis In a behavior inventory of 100 units consistingof states and events, forty-seven were observed exclusivelyor frequently in social situations. An analysis of the effectsof forebrain lesions on two stereotyped displays indicated involvementof the striatal area of the basal forebrain in species-typical"challenge" displays that are characteristic of territorialencounters between adult conspecifics. "Assertive" displaysassociated with elevated behavioral arousal were not significantlyaffected Lesions confined to the dorsal ventricular ridge resultedin no significant deficits in either display type.     

Identification and characterization of QTL underlying whole-plant physiology in Arabidopsis thaliana: δ13C, stomatal conductance and transpiration efficiency

Water limitation is one of the most important factors limiting crop productivity world-wide and has likely been an important selective regime influencing the evolution of plant physiology. Understanding the genetic and physiological basis of drought adaptation is therefore important for improving crops as well as for understanding the evolution of wild species. Here, results are presented from quantitative trait loci (QTL) mapping of flowering time (a drought escape mechanism) and carbon stable isotope ratio (δ¹³C) (a drought-avoidance mechanism) in Arabidopsis thaliana. Whole-genome scans were performed using multiple-QTL models for both additive and epistatic QTL effects. We mapped five QTL affecting flowering time and five QTL affecting δ¹³C, but two genomic regions contained QTL with effects on both traits, suggesting a potential pleiotropic relationship. In addition, we observed QTL–QTL interaction for both traits. Two δ¹³C QTL were captured in near-isogenic lines to further characterize their physiological basis. These experiments revealed allelic effects on δ¹³C through the upstream trait of stomatal conductance with subsequent consequences for whole plant transpiration efficiency and water loss. Our findings document considerable natural genetic variation in whole-plant, drought resistance physiology of Arabidopsis and highlight the value of quantitative genetic approaches for exploring functional relationships regulating physiology.