White Pigmentation Research Articles

Dorsal body pigmentation and sexual dimorphism in the marbled salamander (Ambystoma opacum)

Marbled salamanders (Ambystoma opacum) have individually variable dorsal pigmentation patterns. But it is unclear whether or not dorsal pigmentation is associated with variables such as body size and sex. In this study, we test the hypothesis that the body size variables and sex are important predictors of the coverage of dorsal body white pigmentation in adult marbled salamanders. We evaluate the degree of sexual dimorphism in several body traits, including the dorsal body white pigmentation, using univariate and multivariate methods, and analyze the sex-related difference in pigmentation asymmetry. The General Linear Model (GLM) predicts a significant main effect of sex and a significant interaction between sex and dorsal body area (DBA), influencing the coverage of dorsal body white pigmentation. The interaction effect is greater in males than in females. We show significant sex-related differences in body size and shape. Eight morphometric traits reveal female-biased sexual size dimorphism, while males display a greater coverage of dorsal white pigmentation than females. Prominent female characteristics, compared to males, include a significantly heavier and longer body with a wider trunk, head, neck, shoulder and waist. These sex-specific differences suggest selection for a larger body size in females because of increased maternal reproductive success associated with larger body size. Additionally, females display greater pigmentation asymmetry than males, suggesting a significant sex-related disparity in asymmetric pigmentation. Potential ecological and developmental implications of the observed dimorphism are discussed. To our knowledge, this is the first study demonstrating an association of dorsal white pigmentation with dorsal body area and sex, including a significantly disproportionate pigmentation asymmetry between sexes, in adult marbled salamanders.

Role of Pigmentation in Protecting Aspergillus niger Conidiospores Against Pulsed Light Radiation

The photoprotective potential of fungus pigments was investigated by irradiating conidiospores of three Aspergillus niger strains possessing the same genetic background, but differing in their degree of pigmentation with pulsed light (PL) and monochromatic (254 nm) UV-C radiation. Spores of A. niger MA93.1 and JHP1.1 presenting, respectively, a fawn and a white pigmentation were more sensitive to PL and continuous UV-C radiation than the wild-type A. niger strain N402 possessing a dark pigment. Both spores of the dark A. niger N402 and the fawn-color mutant were equally resistant to moist heat at 56°C while spores of the white-color mutant were highly sensitive. These results indicate that melanin protects pigmented spores of A. niger from PL.

<I>Euphorbia mayfieldii</I>, a New Species of Section <I>Poinsettia</I> from Bolivia

Abstract— Euphorbia section Poinsettia contains approximately 25 species native to the Americas. This taxon is sometimes treated as an independent genus or as a subgenus of Euphorbia, but it is currently placed within the recently recircumscribed subgenus Chamaesyce. Four species of Poinsettia have been previously reported from Bolivia, and a fifth species, Euphorbia mayfieldii, is herein described. This new species is a narrow endemic currently known from three collections made in the department of Santa Cruz, where it occurs on grassy cliff faces in tropical forest at elevations from 645–700 m. Flowering occurs at least from July to September. It is probably an attractive and conspicuous plant by virtue of the white pigmentation of the subcyathial leaves. Euphorbia mayfieldii is distinctive due to the combination of glabrous stems and leaves, in addition to cauline leaves that are opposite to rarely in whorls of three with an unlobed and mostly entire blade. Within section Poinsettia, strictly opposite ...

First Report of Fusarium torulosum Causing Dry Rot of Seed Potato Tubers in the United States.

Fusarium dry rot of potato (Solanum tuberosum L.) is a postharvest disease caused by several Fusarium species and is of worldwide importance. Thirteen species of Fusarium have been implicated in fungal dry rots of potatoes worldwide. Among them, eight species have been reported in the northern United States (2). In Michigan potato production, F. sambucinum was the predominant species reported to be affecting seed potato in storage and causing seed piece decay after planting (3). Some previous identifications of F. sambucinum as dry rot may have been F. torulosum since F. torulosum was previously classified within F. sambucinum (4). To further investigate this, dry rot symptomatic tubers were collected from Michigan seed lots in the summers of 2009 and 2010. Small sections from the margins of necrotic regions were cut with a scalpel, surface sterilized in 0.5% sodium hypochlorite for 10 s, rinsed twice in sterile distilled water, and blotted with sterile filter paper. The tissue pieces were plated on half-strength potato dextrose agar (PDA) amended with 0.5 g/liter of streptomycin sulfate and incubated at 23°C for 5 to 7 days. Cultures resembling Fusarium species were transferred onto water agar, and single hyphal tips from actively growing isolates were removed and plated either on carnation leaf agar (CLA) or on half-strength PDA to generate pure cultures. Among the Fusarium isolates obtained, five isolates were identified as F. torulosum (GenBank Accessions Nos. JF803658-JF803660). Identification was based on colony and conidial morphology on PDA and CLA, respectively. These features included slow growth (2.8 ± 0.2 cm in 5 days), white mycelium that became pigmented with age, narrow concentric rings, red or white pigmentation on agar, macroconidia (32.4 ± 0.4 μm average length) with five septa, a pointed apical cell, and a foot-shaped basal cell (4). The identity was confirmed through DNA extraction followed by amplification and sequencing of the translation elongation factor (EF-1α) gene region (1). The Fusarium-ID.v (1) and the NCBI database were used to obtain the closest match (99%) to previously sequenced materials (GenBank Accession No. AJ543611). Pathogenicity testing was done on disease-free potato tubers cv. Red Norland. Tubers were surface sterilized for 10 min in 0.5% sodium hypochlorite and rinsed twice in distilled water. Three tubers per isolate were injected with 20 μl of a conidial suspension (106 conidia/ml) made from F. torulosum cultures grown on PDA for 7 to 10 days. Control tubers were injected with 20 μl of sterile distilled water. All tubers inoculated with F. torulosum developed typical potato dry rot symptoms consisting of a brown and dry decay. There was no disease incidence on the control tubers. F. torulosum was reisolated from the symptomatic tubers. To our knowledge, this is the first report of F. torulosum causing potato dry rot in the United States.

From one to ten in a single stroke – resolving the European Eumidasanguinea (Phyllodocidae, Annelida) species complex

We investigate the genetic structure of European lineages of the polychaete Eumida sanguinea with mitochondrial COI and nuclear ITS, and demonstrate the presence of ten cryptic species. Within the E. sanguinea species complex there are six different white pigmentation patterns but only three of these are unique for a single species. No other consistent morphological differences were observed. We give new species names to seven of the lineages from our study, providing examples of combined morphological and molecular diagnoses, apply the available name E. sanguinea to one species, and leave two lineages with single representatives unnamed. We also include new data and a diagnosis for the poorly known E. notata, which also belongs to the E. sanguinea species complex.

Divergence of gene regulation through chromosomal rearrangements.

BackgroundThe molecular mechanisms that modify genome structures to give birth and death to alleles are still not well understood. To investigate the causative chromosomal rearrangements, we took advantage of the allelic diversity of the duplicated p1 and p2 genes in maize. Both genes encode a transcription factor involved in maysin synthesis, which confers resistance to corn earworm. However, p1 also controls accumulation of reddish pigments in floral tissues and has therefore acquired a new function after gene duplication. p1 alleles vary in their tissue-specific expression, which is indicated in their allele designation: the first suffix refers to red or white pericarp pigmentation and the second to red or white glume pigmentation.ResultsComparing chromosomal regions comprising p1-ww[4Co63], P1-rw1077 and P1-rr4B2 alleles with that of the reference genome, P1-wr[B73], enabled us to reconstruct additive events of transposition, chromosome breaks and repairs, and recombination that resulted in phenotypic variation and chimeric regulatory signals. The p1-ww[4Co63] null allele is probably derived from P1-wr[B73] by unequal crossover between large flanking sequences. A transposon insertion in a P1-wr-like allele and NHEJ (non-homologous end-joining) could have resulted in the formation of the P1-rw1077 allele. A second NHEJ event, followed by unequal crossover, probably led to the duplication of an enhancer region, creating the P1-rr4B2 allele. Moreover, a rather dynamic picture emerged in the use of polyadenylation signals by different p1 alleles. Interestingly, p1 alleles can be placed on both sides of a large retrotransposon cluster through recombination, while functional p2 alleles have only been found proximal to the cluster.ConclusionsAllelic diversity of the p locus exemplifies how gene duplications promote phenotypic variability through composite regulatory signals. Transposition events increase the level of genomic complexity based not only on insertions but also on excisions that cause DNA double-strand breaks and trigger illegitimate recombination.

Morphology of wax modified coil coatings without and with pigmentation

Wax modified coil coatings without and with white pigmentation were analyzed by optical light microscopy, Raman spectroscopy and Atomic Force Microscopy. By optical light and Raman microscopy dispersed spherical wax domains in the micrometer range were ascertained on the surface and within the bulk of the coatings. By the combined Atomic Force microscopical and Raman spectroscopical approach it was possible to detect resin and pigment residues in the lubricant features with diameters above 2 μm. Vice versa indications for wax inclusions with diameters below 2 μm in the matrix and rather thin wax layers expanding from the spherical lubricant domains onto the surface were obtained. As to the wax distribution evaluated by optical light and Raman microscopy significant differences between clearcoat and white topcoat were detected. The non-pigmented coating exhibited smaller wax features and an inhomogeneous distribution with less wax on the surface.

The White Elephant in London: An Episode of Trickery, Racism and Advertising

This article shows how the exhibition of a white elephant, owned by Phineas Taylor Barnum, the American showman and trickster, became a forum to discuss nineteenth-century theories of race. To nineteenth-century Britons, white elephants were potent symbols of white superiority, allegedly holy to the kings of Siam and Burma, and worshipped because of their white pigmentation, even if this whiteness was artificially produced. When Barnum exhibited an authentic elephant of splotchy colouration, he provoked a debate about the elephant’s financial value and religious significance. In evaluating the beast, newspaper reports, scientific discussions and advertisements revealed a complex understanding of human whiteness, acknowledging that it was an artificial construct, and a status of the most superficial kind.

A New Gnathiid (Crustacea: Isopoda) Parasitizing Two Species of Requiem Sharks from Lizard Island, Great Barrier Reef, Australia

Third-stage juveniles (praniza 3) of Gnathia grandilaris n. sp. were collected from the gill filaments and septa of 5 requiem sharks, including a white tip reef shark, Triaenodon obesus, and 4 grey reef sharks, Carcharhinus amblyrhynchos, at Lizard Island, Great Barrier Reef, Australia, in March 2002. Some juvenile gnathiids were then maintained in fresh sea water until they molted to adults. Adult males appeared 19 days following detachment of juveniles from host fishes, but no juveniles molted successfully into females. The current description is based, therefore, on bright field and scanning electron microscopy observations of adult males and third-stage juveniles. Unique features of the male include the triangular-shaped inferior medio-frontal process, 2 areolae on the dorsal surface of the pylopod, and a slender pleotelson (twice as long as wide) with lateral concavities. The third-stage juvenile has distinctive white pigmentation on the black pereon when alive, while the mandible has 9 triangular backwardly directed teeth. This species has the largest male and third-stage juvenile of any Gnathia spp. from Australia and of any gnathiid isopods associated with elasmobranchs.

Commerson's Dolphins (<I>Cephalorhynchus commersonii</I>) off Ría Deseado, Patagonia, Argentina

Studies of the biology and ecology of Commerson’s dolphins (Cephalorhynchus commersonii) in the Ria Deseado estuary (47o 46' S, 65o 58' W) were carried out during January-February 1986 to 1991 and 1994 to 1997, August 1987 and 1988, September 1995, and May 2003. Commerson’s dolphins were consistently located along a 24-km stretch of the Ria Deseado. Twenty-six dolphins were identified using marks, scars, and differences in the black and white pigmentation of the head, back, and sides. Two adult dolphins with the typical grey colour pattern of the calves of this species have been observed since 1994. Behavioural observations were recorded and fell into four general categories: (1) traveling (51%), (2) resting (21%), (3) feeding (19%), or (4) socialising (9%). Feeding behaviours included dolphins feeding at the surface, near anchor lines, and around piers. Commerson’s dolphins were directly observed feeding on silversides (Odontesthes). Calves were observed between mid-September and midMarch, which suggests that calves are born in the austral spring and early summer. Interactions between dolphins and seabirds/marine mammals were recorded. Killer whales (Orcinus orca) may prey on Commerson’s dolphins in this area.

Reduced expression of vps11 causes less pigmentation in medaka, Oryzias latipes

In this article, we describe the medaka mutant pale gray eyes (pge) that shows reduction of black, white, and silver pigmentation and lethality approximately a week after hatching. The pge mutation was mapped to the tip of linkage group 14 and no recombinations were observed between the mutation and medaka vps11 in 900 meioses. Vps 11 is one of the evolutionarily conserved class C vacuolar protein sorting genes (c-vps: vps11, vps16, vps18, and vps33), whose products physically associate to form the c-vps protein complex required for vesicle docking and fusion in the budding yeast. Mutations in vps16, vps18, and vps33 are known to result in decreased pigmentation in organisms such as Drosophila. We cloned the full-length medaka vps11 cDNA by rapid amplification of cDNA ends (RACE) and found no RACE products from the pge mutants. Similarly, no vps11 transcripts were detected from the pge mutants by Northern analysis. The injection of an antisense morpholino against vps11 phenocopied the pge mutant. Taken together, the results suggest that reduced expression of medaka vps11 causes pge and that medaka vps11 is indispensable for survival and normal pigmentation.

The mutation causing the black-and-tan pigmentation phenotype of Mangalitza pigs maps to the porcine ASIP locus but does not affect its coding sequence

The gene for agouti signaling protein (ASIP) is centrally involved in the expression of coat color traits in animals. The Mangalitza pig breed is characterized by a black-and-tan phenotype with black dorsal pigmentation and yellow or white ventral pigmentation. We investigated a Mangalitza x Piétrain cross and observed a coat color segregation pattern in the F2 generation that can be explained by virtue of two alleles at the MC1R locus and two alleles at the ASIP locus. Complete linkage of the black-and-tan phenotype to microsatellite alleles at the ASIP locus on SSC 17q21 was observed. Corroborated by the knowledge of similar mouse coat color mutants, it seems therefore conceivable that the black-and-tan pigmentation of Mangalitza pigs is caused by an ASIP allele a(t), which is recessive to the wild-type allele A. Toward positional cloning of the a(t) mutation, a 200-kb genomic BAC/PAC contig of this chromosomal region has been constructed and subsequently sequenced. Full-length ASIP cDNAs obtained by RACE differed in their 5' untranslated regions, whereas they shared a common open reading frame. Comparative sequencing of all ASIP exons and ASIP cDNAs between Mangalitza and Piétrain pigs did not reveal any differences associated with the coat color phenotype. Relative qRT-PCR analyses showed different dorsoventral skin expression intensities of the five ASIP transcripts in black-and-tan Mangalitza. The a(t) mutation is therefore probably a regulatory ASIP mutation that alters its dorsoventral expression pattern.

A New Species of Big Black Bolitoglossa (Amphibia: Caudata) from Central Panamá

Abstract A new species of Bolitoglossa is described from the Cordillera Central of central Panama. This is a large black species, which is likely related to the B. (Eladinea) schizodactyla group of Costa Rica and Panama. The new species, known from a single specimen, differs from other large black Bolitoglossa in having white pigmentation on the lower face and on the ventral portions of the head and chest. It also has more interdigital webbing than most members of the B. (E.) schizodactyla group.

Brainstem Auditory-Evoked Potential Assessment of Auditory Function and Congenital Deafness in Llamas (Lama glama) and Alpacas (L pacos)

Auditory function of llamas and alpacas was assessed objectively by means of brainstem auditory-evoked response audiometry (BAER) to establish the normal hearing range and to test the hypothesis of a correlation between blue eyes, white coat, and deafness. Sixty-three camelids were available for the study. Thirteen animals had blue irides; 1 animal had 1 blue and 1 pigmented iris. Wave latencies, amplitudes, and interpeak latencies were measured under general anesthetic. Click stimuli (dB [HL]) were delivered by an insert earphone. Four to five positive peaks could be detected; waves I, II, and V were reproducible; wave II appeared infrequently; and wave IV generally merged with wave V to form a complex. Peak latencies decreased and peak amplitudes increased as stimulus intensity increased. A hearing threshold level of 10-20 dB (HL) was proposed as the normal range in llamas and alpacas. None of the animals with pigmentation of coat and iris showed any degree of hearing impairment. Seven of the 10 blue-eyed, pure-white animals were bilaterally deaf and one of them was unilaterally deaf. However, 2 blue-eyed, white animals exhibited normal hearing ability. Three blue-eyed animals with pigmented coat did not show any hearing impairment. All white animals with normal iris pigmentation had normal auditory function; so did the 1 animal with 1 normal and 1 blue iris. The high frequency (78%) of bilaterally deaf animals with pure white coat and blue iris pigmentation supports the hypothesis of a correlation between pigmentation anomalies and congenital deafness in llamas and alpacas.

Agarivorans albus gen. nov., sp. nov., a gamma-proteobacterium isolated from marine animals.

Six bacterial strains were isolated from healthy marine organisms that were collected from the coast of the Kanto area in Japan. Phylogenetic analysis based on 16S rDNA sequence similarity showed that the six isolates formed a separate cluster in the gamma-Proteobacteria and were related to the genera Alteromonas and Glaciecola (<91.6 % similarity). The isolates were related closely to each other (DNA-DNA reassociation values of 74-93 %). The isolates had a polar flagellum and were Gram-negative, mesophilic, strictly aerobic rods that required salt for growth. Distinct phenotypic features of this group included the ability to hydrolyse agar and white pigmentation of colonies. The DNA G+C content of the isolates was 48-50 mol%. The major quinone was Q-8. Phenotypic characteristics of the isolates differed from those of members of the genera Alteromonas and GLACIECOLA: The name Agarivorans albus gen. nov., sp. nov. is proposed for the six isolates; the type strain is MKT 106(T) (=IAM 14998(T)=LMG 21761(T)).

A new Haploposthia species (Acoela) from the Swedish west coast

A large new species of acoel belonging to the genus Haploposthia (Acoela) is described. Haploposthia lactomaculata sp. nov. was collected by dredging from the Swedish west coast at depths of 45–55 m. The main diagnostic features of the species are a whitish translucent body with opaque white or milky dot pigmentation on the dorsal side around the midbody, epidermis with a smooth surface, sclerotized conical penis papilla, seminal vesicle surrounded by accessory glands, mixed germinal centre for ovary and testis, and large size (2–3 mm).

Whiter than white: options for the compounder

A number of white pigments can be employed in plastic compounds to achieve strong white colours and high reflectance, as well as for modifying other colours and increasing brightness. Titanium dioxide is the most important of these pigments for the plastics industry, but there are some alternatives as well. Plastics Additives & Compounding summarizes some of the issues at stake for compounders when selecting a suitable white pigmentation system.

DESCRIPTIONS OF THE DORID NUDIBRANCHS POLYCERA HEDGPETHI MARCUS, 1964 AND P. FUJITAI BABA, 1937 IN NEW ZEALAND (GASTROPODA: OPISTHOBRANCHIA)

New Zealand specimens of Polycera hedgpethi Marcus, 1964 and P. fujitai Baba, 1937 are described formally and in detail for the first time. Both species are easily recognised from previous descriptions. Five polycerid species are known now from New Zealand waters. The largest New Zealand specimen of P. hedgpethi collected so far is only two-thirds of the size of the type. This size difference may account for some of the differences noted, e.g., number of rows of radular teeth. New Zealand specimens differ from the original description in lacking yellow pigment on the notal ridge, tail crest and upper border of the foot, and in possessing a wider foot, a subterminal band of orange brown pigment on the extrabranchial processes, and opaque and crystalline white scattered on the body and appendages. Subsequent description shows close similarity except in two cases, in one the grey/black pigment is flecked not spotted, the jaws are rounded not angular and allosperm and vaginal ducts join before reaching the spermatheca, in the other the primary colour is dark brown, there is no white pigmentation and the jaws are rounded. Polycera hedgpethi is compared with three very similar species, P. hummi Abbott, 1952, P. aurisula Marcus, 1956 and P. gnupa Marcus & Marcus, 1967: it is distinguished from them by the dense grey/black spotting and lack of blue pigment on the notal appendages. Polycera gnupa is believed by some to be synonymous with P. hedgpethi. Here P. gnupa is maintained as a distinct species in having brown as the basic colour, cylindrical extrabranchial processes and unipinnate gills. The New Zealand specimens of Polycera fujitai agree well in colour and form with the original description except that they differ in basic colour in being dull orange not brown or yellowish brown. There are differences in colouring between the local and Hong Kong specimens, the former having grey and orange as the foundation of the pattern, a blue tinge to the rhinophores and the opaque yellow widespread.

Congenital Deafness and its Recognition

Congenital deafness in dogs and cats is primarily of the hereditary sensorineural form associated with white pigmentation genes, although acquired forms of deafness are possible. Highest prevalence is seen in white cats, especially those with blue eyes, and the Dalmatian, with many other dog breeds affected to some extent. This deafness results from degeneration of the cochlear blood supply at age 3-4 weeks, presumably resulting from suppression of melanocytes by the white (cat) or merle or piebald (dog) genes. Mechanism of inheritance is not understood for most breeds. Such animals should not be bred and may present liabilities for their owners. Objective diagnosis of deafness, especially when unilateral, relies on the brainstem auditory evoked response, an electrodiagnostic test where electrical activity in response to a click stimulus is recorded from the scalp using needle electrodes and a special purpose computer. Client counseling guidelines are presented.

Genetic analysis of steel and the PG-M/versican-encoding gene AxPG as candidates for the white (d) pigmentation mutant in the salamander Ambystoma mexicanum.

Vertebrate non-retinal pigment cells are derived from neural crest (NC) cells, and several mutations have been identified in the Mexican axolotl Ambystoma mexicanum (Ambystomatidae) that affect the development of these cell lineages. In "white" (d) mutant axolotls, premigratory NC cells differentiate as pigment cells, yet fail to disperse, survive, or both, and this leads to a nearly complete absence of pigment cells in the skin. Previous studies revealed that d affects pigment cell development non-autonomously, and have reported differences between white and wild-type axolotls in the structure and composition of the extracellular matrix through which NC and pigment cells migrate. Here we test the correspondence of d and two candidate genes: steel and AxPG. In amniotes, Steel encodes the cytokine Steel factor (mast cell growth factor; stem cell factor; kit ligand), which is expressed along the migratory pathways of melanocyte precursors and is required by these cells for their migration and survival; mammalian Steel mutants resemble white mutant axolotls in having a deficit or complete absence of pigment cells. In contrast, AxPG encodes a PG-M/versican-like proteoglycan that may promote the migration of A. mexicanum pigment cells, and AxPG expression is reduced in white mutant axolotls. We cloned a salamander orthologue of steel and used a partial genetic linkage map of Ambystoma to determine the genomic locations of steel, AxPG, and d. We show that the three genes map to different linkage groups, excluding steel and AxPG as candidates for d.