Chromatophores and color revelation in the blue variant of the Siamese fighting fish (Betta splendens).

Our light and electron microscopy observations have revealed that the chromatic unit for the caudal fin in the blue variant of the Siamese fighting fish consists exclusively of dermal chromatophores comprised of compact and overlapping light-reflecting motile iridophores underlined by a layer of light absorbing melanophores. The 2 subtypes that make up about 70% of the skin tissue are located just below the basal layer of the considerably thin epidermis. The administration of K-rich saline or norepinephrine induced prompt, but gradual and reversible, changes in the color of the skin from blue to a brown-yellowish color. The induced color change is attributable either to the neurotransmitter releasing effects of the K-rich saline or to the direct effects of norepinephrine on the postsynaptic alpha adrenergic receptors. Both of these agents induced aggregation of the melanosomes within the melanophores and apparently shifted the wavelength of the light reflected by the iridophores towards the shorter (blue) end of the spectrum. Based on the distribution and architectural arrangement of the iridophores and melanophores as well as their physiological responses, we conclude that the generation of the blue coloration in this fish predominantly occurs through motile iridophores via a multilayered thin-film interference phenomenon of the non-ideal type. The presence of the underlying melanophores provides a black sheet of melanin that enhances the chroma and purity of the color.

Factors associated with iron depletion and iron deficiency anemia among Arabic preschool children of the United Arab Emirates.

OBJECTIVE: The purpose of this study was: 1. To estimate the prevalence of iron depletion and iron deficiency anemia in preschool Arabic children of the United Arab Emirates (UAE), and 2. To determine the risk factors associated with these conditions in this population of children. METHODS: From April through to October 2000 a questionnaire and capillary blood survey was carried out in one primary health care (PHC) centre of Al Ain, UAE. Children whose capillary hemoglobin (Hb) or mean cell volume (MCV) results fell below predetermined cutoffs were offered venous blood workup. An additional sample of children with capillary blood results above those cutoffs were offered the same workup. All blood sampling was completed by May 2001. RESULTS: Five hundred and eight parents were questionnaired and 496 children capillary blood tested. Of the 320 venous blood tested, 315 were analyzed, in relation to questionnaire responses, using univariate analysis and logistic regression. Anemia, iron depletion and iron deficiency anemia were found in an estimated 36.1%, 26%, and 9.9% of this population of children. Age was a significant independent predictor of both iron depletion and iron deficiency anemia. Mother's current pregnancy was an additional predictor of iron deficiency anemia. CONCLUSION: The prevalences of iron depletion and iron deficiency anemia in this population of children were consistent with other reports from the region. Child's age and mother's current pregnancy were predictors of iron deficiency anemia. These findings have important implications for antenatal and childcare both in hospital and primary health care clinics.

Seroprevalence of antibodies to repetitive domains of Plasmodium vivax circumsporozoite protein in United Arab Emirates children.

The aim of this study was to determine the exposure of child citizens of the United Arab Emirates (UAE) to Plasmodium vivax, and to elucidate if it was related to place of residence or previous international travel to malaria-endemic areas. Blood samples were collected from 1010 primary schoolchildren resident in 7 out of 9 districts of the UAE during October and November 1999. Plasma samples were tested for antibodies against MAP4 (DGQPAGDR)3P2P30, a multiple antigen peptide containing the repeat amino acid sequences of P. vivax circumsporozoite protein (CSP), conjugated to 2 T-helper epitopes, P2 (QYIKANSKFIGITE) and P30 (FNNFTVSFWLRVPKVSASHLE) from tetanus toxin. For confirmation of P. vivax-specific reactivity, positive samples were further tested against (AGDR)6, a synthetic peptide containing 6 copies of a protective epitope within the CSP, and against a recombinant CSP, designated as NS1(81)V20. Results indicated that 3.3% of the children were seropositive. The seropositivity rates differed significantly in relation to place of residence, whereas travel outside the UAE did not significantly affect the exposure rates to P. vivax.