Keratinocytes in culture accumulate phagocytosed melanosomes in the perinuclear area

There are many techniques for evaluating melanosome transfer to keratinocytes but the spectrophotometric quantification of melanosomes incorporated by keratinocyte phagocytosis has not been previously reported. Here we describe a new method that allows the spectrophotometric visualization of melanosome uptake by normal human keratinocytes in culture. Fontana-Masson staining of keratinocytes incubated with isolated melanosomes showed the accumulation of incorporated melanosomes in the perinuclear areas of keratinocytes within 48 h. Electron microscopic observations of melanosomes ingested by keratinocytes revealed that many phagosomes containing clusters of melanosomes or their fragments were localized in the perinuclear area. A known inhibitor of keratinocyte phagocytosis which inhibits protease-activated receptor-2, i.e., soybean trypsin inhibitor, decreased melanosome uptake by keratinocytes in a dose-dependent manner. These data suggest that our method is a useful model to quantitate keratinocyte phagocytosis of melanosomes visually in vitro.     

Epigenetic variation in tissue cultured Gaura lindheimeri

High levels of variability were observed in tissue cultured Gaura lindheimeri genotypes when flowered in situ. Tissue culture treatments for chromosome doubling (colchicine: 0, 0.25, 1.25 mM; trifluralin: 0, 15, 30 μM) were all highly variable for morphological traits. Experiment No. 1 tested the tissue culture protocols used. In the first control (C1), plantlets were subcultured continuously. Nodes were excised and placed on solid medium for the second control (C2). In the third control (C3), nodes were excised and put in liquid medium for 24 h at room temperature. The fourth control (C4) was the same as the third control except liquid cultures were moved to 4°C for 48 h after treatment at room temperature. Experiment No. 2 examined the stability of the variation. Representative plants with different traits were selected for clonal propagation and grown in a replicated trial in the greenhouse. Several morphological traits (flower size, leaf length:width ratios, petal length:width ratios, and flower color) were measured. All of the controls had as much variability as the treated plants. Flower size of the first flower for plant number 01G-02 was significantly different in C1 compared with C3, but not with C2 and C4. Plant number 443-1 (white) was more stable in the replicated trial for the flower size than plant number 01G-02 (pink). All traits measured for plant number 01G-02 were unstable; most flower colors and patterns reverted back to the original color of the non-tissue cultured plants. The somaclonal variation observed was epigenetic in nature, indicating changes in DNA methylation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Association of a single-nucleotide substitution in TYRP1 with roux in Japanese quail (Coturnix japonica)

We investigated TYRP1 as a candidate locus for the recessive, sex-linked roux (br(r)) phenotype in Japanese quail. A screen of the entire coding sequence of TYRP1 in roux and wild-type quail revealed a non-synonymous T-to-C substitution in exon 3, leading to a Phe282Ser mutation. This was perfectly associated with plumage phenotype: all roux birds were homozygous for Ser282. Co-segregation of the Phe282Ser mutation with the roux phenotype was confirmed in three br(r)/BR+ x br(r)/- backcrosses. We found no significant difference in TYRP1 expression between roux and wild-type birds, suggesting that this association is not due to linkage disequilibrium with an unknown regulatory mutation. In addition, the Phe282 amino acid appears to be of functional significance, as it is highly conserved across the vertebrates. This is the first demonstration that TYRP1 has a role in pigmentation in birds.     

Egg color as an adaptation for thermoregulation

ABSTRACT.   Avian embryos are incubated at temperatures only 2–6 °C below that at which hyperthermia begins to influence survival. In habitats where sunlight directly strikes the eggs, even for short periods, heat gain may be a substantial threat to survival, and reflective pigmentation may reduce the rate of heat gain. The results of previous studies suggest that light-colored eggs acquire heat slower than dark eggs, but artificial pigments were used to create differences in egg coloration. This approach is problematic because natural eggshell pigments have low absorbance in the near-infrared waveband that encompasses about half of incident solar radiation. We used naturally-pigmented eggs to measure the influence of egg coloration on heat gain. Triads ( N = 18) of eggs from Brewer's ( Euphagous cyanocephalus ), Red-winged ( Agelaius phoeniceus ), and Yellow-headed ( Xanthocephalus xanthocephalus ) blackbirds were crossed with six nests of each species and either exposed to full sunlight or placed under a diffusing umbrella. Thermisters recorded internal egg temperature every minute until an asymptotic temperature was reached. Eggs in full sunlight acquired heat more rapidly than eggs in the shaded environment, but heat gain did not vary with egg color in either environment. Eggs placed in Yellow-headed Blackbird nests took longer to reach asymptotic temperature, but there was no significant egg-by-nest interaction. Thus, it appears that differences in reflectivity of eggshell pigments in the visible range (400–700 nm) do not result in different rates of heat acquisition. The thermoregulation hypothesis was not supported.     

Alate differentiation and compound-eye development in the dry-wood termite <Emphasis Type="Italic">Neotermes koshunensis</Emphasis> (Isoptera,Kalotermitidae)

In social insects, caste-specific characters develop in the postembryonic differentiation processes. However, the mechanisms of caste-specific organ development have yet to be elucidated. In order to obtain insights into the relationship between caste differentiation and the regulation of organ development, we determined the caste-developmental pathway and observed compound-eye development accompanying alate differentiation in the dry-wood termite, Neotermes koshunensis. As previously reported in other Neotermes, this species has a linear caste-developmental pathway, comprising six larval- and two nymphal-instar stages. Although the apparent eye formation occurs during the last nymphal stages, just prior to the imaginal molt, individuals possess eye primordia from the first larval-instar stage. The outer morphological structure of the eye was observed from the third larval-instar stage. The detailed differentiation of cells constituting ommatidia appeared to occur in relatively young larval instars (fourth stage), although the pigmentation of pigment cells and detailed structural formation of ommatidia occurred during the final stage of alate development, i.e., during the late second nymphal-instar stage. This suggests that eye development is arrested in the larval stages, and then resumed during the late nymphal stage to complete functional eye formation, which is required for nuptial flight. In comparison to major hemimetabolous insects, which possess functional compound eyes even at the first instar larva, this termite species shows the heterochronic shift in terms of compound-eye development. Received 20 March 2006; revised 24 September 2006; accepted 4 October 2006.     

Identifying genes underlying skin pigmentation differences among human populations

Skin pigmentation is a human phenotype that varies greatly among human populations and it has long been speculated that this variation is adaptive. We therefore expect the genes that contribute to these large differences in phenotype to show large allele frequency differences among populations and to possibly harbor signatures of positive selection. To identify the loci that likely contribute to among-population human skin pigmentation differences, we measured allele frequency differentiation among Europeans, Chinese and Africans for 24 human pigmentation genes from 2 publicly available, large scale SNP data sets. Several skin pigmentation genes show unusually large allele frequency differences among these populations. To determine whether these allele frequency differences might be due to selection, we employed a within-population test based on long-range haplotype structure and identified several outliers that have not been previously identified as putatively adaptive. Most notably, we identify the DCT gene as a candidate for recent positive selection in the Chinese. Moreover, our analyses suggest that it is likely that different genes are responsible for the lighter skin pigmentation found in different non-African populations. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

A new view on dam lines in Polish Arabian horses based on mtDNA analysis

Polish Arabian horses are one of the oldest and the most important Arab populations in the world. The Polish Arabian Stud Book and the Genealogical Charts by Skorkowski are the main sources of information on the ancestors of Polish Arabs. Both publications were viewed as credible sources of information until the 1990s when the data regarding one of the dam lines was questioned. The aim of the current study was to check the accuracy of the pedigree data of Polish dam lines using mtDNA analysis. The analyses of a 458 bp mtDNA D-loop fragment from representatives of 15 Polish Arabian dam lines revealed 14 distinct haplotypes. The results were inconsistent with pedigree data in the case of two lines. A detailed analysis of the historical sources was performed to explain these discrepancies. Our study revealed that representatives of different lines shared the same haplotypes. We also noted a genetic identity between some lines founded by Polish mares of unknown origin and lines established by desert-bred mares.     

Evaluation of the bioherbicide Myrothecium verrucaria for weed control in tomato (Lycopersicon esculentum)

An isolate of the fungus Myrothecium verrucaria was evaluated for its biocontrol potential against common purslane, horse purslane, spotted spurge, and prostrate spurge, all serious weed pests in commercial tomato fields in the southeastern US. In greenhouse and field tests, M. verrucaria was highly virulent against these weeds when applied as conidial sprays formulated in 0.2% Silwet L-77 surfactant, even in the absence of dew. In field test plots naturally infested with these weeds, seedlings in the two-to-three leaf growth stage treated with M. verrucaria at 2×10⁷ conidia mL^-1 in 0.2% Silwet, exhibited leaf and stem necrosis within 24 h following inoculation, with mortality occurring within 96 h. After 7 days, M. verrucaria had killed 90-95% of both purslane species and 85-95% of both spurge species. Tomatoes that were transplanted into plots treated with M. verrucaria remained healthy and vigorous throughout the growing season. Since M. verrucaria effectively controlled several common weeds under field conditions, this fungus appears to have potential as an effective bioherbicide for pre-plant weed control in production systems with transplanted tomato.