The Curatorial Voice: U.S. Institutions Exhibit the Ancient Andes

Two new exhibits on ancient Andean civilizations are open in the United States. Machu Picchu: Unveiling the Mystery of the Incas is a large traveling exhibition and Tiwanaku: Ancestors of the Inca is a smaller temporary exhibition that is not traveling. Both introduce North American audiences to objects and information that have never been exhibited in the United States and each includes some extraordinary artifacts. The two exhibits differ in many ways: Machu Picchu emphasizes information, archaeological science, and cultural history, whereas Tiwanaku focuses on art style and objects. The curatorial voice and point of view are strong in each exhibit, as is the institutional perspective of its originiating museum. In this respect these exhibits differ significantly from contemporary ones on ancient North America, which generally include the voices and points of view of descendant communities and others.     

Melanocytes in Human Embryonic and Fetal Skin: A Review and New Findings

Melanocytes account for approximately 5–10% percent of the cells in adult epidermis. Unlike the ectodermally derived keratinocytes, they originate in the neural crest and migrate into the epidermis early in development. There has been an interest in melanocytes in developing human skin since the late 1800s, when concentrated pigmented cells were identified in the sacro-coccygeal skin of Japanese fetuses. This observation led to speculation and subsequent investigation about the racial nature of the melanocytes in this site (the Mongolian spot), the presence of melanocytes in fetuses of other races, the timing of appearance of these cells in both the dermis and epidermis, and their origin. The early investigators relied primarily on histochemical methods that stained either the premelanosome or the pigmented melanosome, or relied upon the activity of tyrosinase within the melanosome to effect the DOPA reaction. Studies by electron microscopy added further documentation to the presence of melanocytes in the skin by resolving the structure of the melanosome regardless of its state of pigmentation. All of these methods recognized, however, only differentiated melanocytes. The thorough investigations of melanocytes in the skin from a large number of black embryos and fetuses by Zimmerman and colleagues between 1948 and 1955 provided insight into the time of appearance of melanocytes in the dermis (10–11 weeks' menstrual age) and the epidermis (11–12 weeks) and revealed the density of these cells in both zones of the skin of several regions of the body. The precise localization of the melanocytes in the developing hair follicles was contributed by the studies of Mishima and Widlan (J Invest Dermatol 1966; 46:263–277). More recently, monoclonal antibodies have been developed that recognize common oncofetal or oncodifferentiation antigens on the surface or in the cytoplasm of melanoma cells and developing melanocytes (but not normal adult melanocytes). These antibodies recognize the cells irrespective of the presence or absence of melanosomes or their activity in the synthesis of pigment and therefore are valuable tools for re-examining the presence, density, and distribution patterns of melanocytes in developing human skin. Using one of these antibodies (HMB-45), it was found that dendritic melanocytes are present in the epidermis between 40 and 50 days estimated gestational age in a density comparable with that of newborn epidermis and are distributed in relatively non-random patterns. A number of questions about the influx of cells into the epidermis, potential reservoirs of melanoblasts retained within the dermis, division of epidermal melanocytes, and the interaction of melanocytes and keratinocytes during development remain unresolved. The tools now appear to be available, however, to begin to explore many of these questions.     

Evaluating Intracellular Signaling Pathways as Biomarkers for Environmental Contaminant Exposures

The number of biomarkers being evaluated as environmental indicatorscontinues to increase even as proposed assessments expand incomplexity. One key to a rational consolidation may lie in clearlyidentifying and characterizing those biochemical pathways sharedamong many biomarkers which are sensitive to environmental perturbation.Recent studies suggest that signal transduction pathways whichare common to many cell types and species may provide multipletargets for the toxic effects of heavy metals. Such intracellularcommunication pathways might provide a useful framework forunderstanding hormetic effects and for predicting responsesto complex contaminant mixtures. Preliminary in vitro experimentstested the effects of mercuric chloride (HgCl₂) and cadmiumchloride (CdCl₂) on signal transduction in cells of the teleostimmune system. Concentrations of inorganic mercury µMsuppressed DNA synthesis and induced rapid influx of radiolabelledcalcium within ten minutes as well as tyrosine phosphorylationof numerous cellular proteins within one minute. Lower concentrations(0.1 – 1 µM) of HgCl₂ which activated cell growthalso induced a slow rise over two minutes in intracellular calciumin cells loaded with the calcium indicator dye, fura-2, butdid not produce detectable tyrosine phosphorylation of leukocyteproteins. Although CdCl₂ >10 µM also suppressed DNAsynthesis, this environmental metal failed to activate cellgrowth or to induce tyrosine kinase activity at any concentrationtested. Future experiments will assess how cells which are exposedto both metals integrate these mixed signals. This approachmay provide a means of predicting cellular responses to multiplecontaminants over broad dose ranges     

Influence of Reticulocytosis on the Course of Infection of Plasmodium chabaudi and P. berghei*

SYNOPSIS. Reticulocytosis, stimulated by the destruction of red blood cells by phenylhydrazine, altered the course of infection of both Plasmodium chabaudi and P. berghei in the mouse. P. chabaudi, lacking a preference for reticulocytes, was adversely affected when young cells were present in abundance. Parasitemias diminished and most of the animals survived the otherwise fatal infection. P. berghei preferentially invaded reticulocytes to the extent that the parasitemia became contained largely in the reticulocyte population. This was accompanied by a delay in time to death.     

Genomic dissection and prioritizing of candidate genes of QTL for regulating spontaneous arthritis on chromosome 1 in mice deficient for interleukin-1 receptor antagonist

Rheumatoid arthritis is a heterogeneous disease with clinical and biological polymorphisms. IL-1RN is a protein that binds to interleukin-1 (IL-1) receptors and inhibits the binding of IL-1-alpha and IL-1-beta. IL-1RN levels are elevated in the blood of patients with a variety of infectious, immune, and traumatic conditions. Balb/c mice deficient in IL-1ra (mouse gene of IL-1RN) develop spontaneous autoimmune arthritis while DBA/1 mice deficient in IL-1ra do not. Previously, we identified a major QTL that regulates the susceptibility to arthritis in Balb/c mice with IL-1ra deficiency. In this study, we found that the QTL may contain two peaks that are regulated by two sets of candidate genes. By haplotype analysis, the total genomic regions of candidate genes were reduced from about 19 Mbp to approximately 9 Mbp. The total number of candidate genes was reduced from 208 to 21.     

Molecular systematics and evolution of the Ptinidae (Coleoptera: Bostrichoidea) and related families

The Ptinidae (Coleoptera: Bostrichoidea) are a cosmopolitan, ecologically diverse, but poorly known group of Coleoptera and, excluding a few economic pests, species are rarely encountered. This first broad phylogenetic study of the Ptinidae s.l. (i.e. including both the spider beetles and anobiids) examines relationships based on DNA sequence data from two mitochondrial genes (16S and COI) and one nuclear gene (28S), using out‐group taxa from both the Bostrichidae and Dermestidae. Topologies varied depending on the genes used and whether data were analysed with either parsimony or Bayesian methods. Generally the two mitochondrial genes supported relationships near the tips of the phylogeny, whereas the nuclear gene supported the basal relationships. The monophyly of the Ptinidae was not inferred by all of the gene combinations and analysis methods, although the combined Ptinidae and Bostrichidae have a single origin in all cases. Alternative relationships include the Ptinidae s.s. (i.e. Ptininae and Gibbiinae) as sister to the anobiids (i.e. the nine remaining subfamilies of Ptinidae s.l.) + Bostrichidae, or the Bostrichidae as sister to the Ptinidae s.s.+ anobiids. Most of the larger subfamilies within the Ptinidae are not monophyletic. Further analysis with more taxa and more genes will be required to clarify and decide upon the best hypothesis of relationships found within the clades of the Bostrichidae and Ptinidae. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 88–108.