Anencephaly: its spectrum and relationship to neural tube defects

Anencephaly patients are of renewed interest because they are regarded as a potential source of organ donation. While there has been a longstanding scientific curiosity on this subject, studies have frequently included such cases as part of the larger spectrum of neural tube defects (NTDs). This paper will discuss some unusual features of anencephaly. Following a review of classification and pathogenesis, associated malformations, growth parameters (organ size and anthropometric measurements), and associations with other entities are discussed. Finally, the relationship of anencephaly to NTDs is presented.     

An evolutionarily diverged mitochondrial protein controls biofilm growth and virulence in Candida albicans

A forward genetic screening approach identified orf19.2500 as a gene controlling Candida albicans biofilm dispersal and biofilm detachment. Three-dimensional (3D) protein modeling and bioinformatics revealed that orf19.2500 is a conserved mitochondrial protein, structurally similar to, but functionally diverged from, the squalene/phytoene synthases family. The C. albicans orf19.2500 is distinguished by 3 evolutionarily acquired stretches of amino acid inserts, absent from all other eukaryotes except a small number of ascomycete fungi. Biochemical assays showed that orf19.2500 is required for the assembly and activity of the NADH ubiquinone oxidoreductase Complex I (CI) of the respiratory electron transport chain (ETC) and was thereby named NDU1. NDU1 is essential for respiration and growth on alternative carbon sources, important for immune evasion, required for virulence in a mouse model of hematogenously disseminated candidiasis, and for potentiating resistance to antifungal drugs. Our study is the first report on a protein that sets the Candida-like fungi phylogenetically apart from all other eukaryotes, based solely on evolutionary “gain” of new amino acid inserts that are also the functional hub of the protein.     

Some Notes on the Morphology of an Aberrant Actinian (Hexacorallia, Actiniaria) Associated with the Glaucothoe of the Hermit Crab Paguropsis typica Henderson (Anomura, Paguridae)

The planktonic glaucothoe of the Indo-West Pacific hermit crab Paguropsis typica Henderson has an aberrant anthozoan polyp, identified as a nynanthean actinian, attached to the underside of its thorax. The morphology of the anemone is described. The scapus is dumb-bell shaped and exhibits a slit-like mouth opening oriented transverse to the animal's siphonoglyphal plane. The gonads are very well developed, whereas tentacle-like structures or retractor muscles of certain septa are reduced. In the adult stage, Paguropsis typica is associated with the zoanthidean Epizoanthus paguropsides . It is assumed that the actinian is lost at the ecdysis leading to the first "hermit stage" and that P. typica might possibly seize a free Epizoanthus colony and adapt it to its body.     

Nod1 promotes colorectal carcinogenesis by regulating the immunosuppressive functions of tumor-infiltrating myeloid cells

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Demonstration of a retino-thalamo-hippocampal pathway in the rat

Investigations using double labeling by axonal transport of tracers have shown that in the rat, four nuclei of the anterior thalamus (anterior dorsal, anterior ventral, lateral anterior, bed nucleus of the stria terminalis) that project to the CA1 region of the hippocampus also receive a discrete input from the contralateral eye. The significance of this telencephalic visual pathway is discussed in a phylogenetic context.     

1,25-Dihydroxyvitamin D3 enhances the generation of nonspecific suppressor cells while inhibiting the induction of cytotoxic cells in a human MLR.

The active vitamin D metabolite, 1,25-dihydroxyvitamin D3 (1,25-D3), has been shown in both in vitro and in vivo experiments to be immunoregulatory. We analyzed the effects of the hormone on the human mixed lymphocyte reaction (MLR), the in vitro model of allograft response. Suppressor-cell activity of MLR-generated effector cells was enhanced by calcitriol (10(-10) to 10(-8) M). This suppressor activity was nonspecific since calcitriol-generated effector cells could suppress a primary MLR with stimulators and/or responders heterologous to the effector-generating MLR. Calcitriol (10(-9) to 10(-7) M) was also effective in preventing the generation of cytotoxic T cells when tested in a 51Cr release assay. While no differences were observed in the phenotypic analyses of the MLR-generated effector cells between 1,25-D3-treated cells and control cells, a significant reduction of class II antigen expression was observed in the presence of the hormone. The effects of calcitriol on human MLR are similar to those observed with cyclosporine.     

Modulation of intracellular calcium and proliferative activity of invertebrate and vertebrate cells by ethylene

Background  

Ethylene is a widely distributed alkene product which is formed enzymatically (e.g., in plants) or by photochemical reactions (e.g., in the upper oceanic layers from dissolved organic carbon). This gaseous compound was recently found to induce in cells from the marine sponge Suberites domuncula, an increase in intracellular Ca²⁺ level ([Ca²⁺]_i) and an upregulation of the expression of two genes, the potential ethylene-responsive gene, SDERR, and a Ca²⁺/calmodulin-dependent protein kinase.     

Transverse mixing of transported material in simple and complex stream reaches

Stream ecologists often make assumptions about the extent to which transported materials (such as dissolved nutrients, particulate organic matter and pollutants) are mixed across the width of a channel. Transverse spatial heterogeneity arises whenever material enters the channel at a point or restricted source, and is dissipated downstream as mixing evens out concentration gradients. A frequent assumption is that the distance required for complete mixing is negligibly short, and therefore that transverse heterogeneity in transported material is not to be expected. However, few mixing data are available for small (discharge <5 m³/s) channels. We measured mixing distances in three small (0.04–0.1 m³/s) eastern Iowa streams via mid-channel injections of a fluorescent tracer. Mixing distances varied, with effectively complete mixing (to statistically undetectable heterogeneity in tracer concentration) taking as little as 5 m or as much as 100⁺ m. Mixing was more rapid in more complex stream reaches and across constrictions and pools (vs. simpler channels). These mixing distances are not negligible when compared to typical spatial scales for ecological experiments.