The lagoon geomorphology of pearl farming atolls in the Central Pacific Ocean revisited using detailed bathymetry data.

The lagoons of seven French Polynesia and Cook Islands pearl farming atolls (Raroia, Takume, Mopelia, Takapoto, Ahe, Takaroa and Manihiki) were surveyed using multibeam and mono-beam sounders. From the detailed bathymetry, morphometric variables (average and maximum depth, frequency-area of depth, lagoon area and volume) are computed and compared. Remarkable geomorphological structures highlighted by bathymetric variations include deep reticulated structures and pinnacles. The seven atolls appear very different in abundance, size and density of these entities. Considering them as markers of the geological, sedimentological and eustatic processes that shape atoll lagoons, they are discussed in the context of the general theory of atoll lagoon formations involving karstic dissolution during Pleistocene or earlier low sea-level stands. In terms of pearl farming management, accurate bathymetric maps help pearl oyster wild stock assessment, development of circulation and biogeochemical models, better lagoon zoning and strategy to remove pearl farming derelict gears.

Temporal expression of CD184(CXCR4) and CD171(L1CAM) identifies distinct early developmental stages of human retinal ganglion cells in embryonic stem cell derived retina.

Human retinal ganglion cells (RGCs) derived from pluripotent stem cells (PSCs) have anticipated value for human disease study, drug screening, and therapeutic applications; however, their full potential remains underdeveloped. To characterize RGCs in human embryonic stem cell (hESC) derived retinal organoids we examined RGC markers and surface antigen expression and made comparisons to human fetal retina. RGCs in both tissues exhibited CD184 and CD171 expression and distinct expression patterns of the RGC markers BRN3 and RBPMS. The retinal progenitor cells (RPCs) of retinal organoids expressed CD184, consistent with its expression in the neuroblastic layer in fetal retina. In retinal organoids CD184 expression was enhanced in RGC competent RPCs and high CD184 expression was retained on post-mitotic RGC precursors; CD171 was detected on maturing RGCs. The differential expression timing of CD184 and CD171 permits identification and enrichment of RGCs from retinal organoids at differing maturation states from committed progenitors to differentiating neurons. These observations will facilitate molecular characterization of PSC-derived RGCs during differentiation, critical knowledge for establishing the veracity of these in vitro produced cells. Furthermore, observations made in the retinal organoid model closely parallel those in human fetal retina further validating use of retinal organoid to model early retinal development.

Curcumin-mediated oxidative stress resistance in Caenorhabditis elegans is modulated by age-1, akt-1, pdk-1, osr-1, unc-43, sek-1, skn-1, sir-2.1, and mev-1.

Abstract Curcumin (diferuloylmethane), a pharmacologically active substance derived from turmeric, exhibits anti-inflammatory, anticarcinogenic, and antioxidant properties. We examined the modulation of oxidative-stress resistance and associated regulatory mechanisms by curcumin in a Caenorhabditis elegans model. Our results showed that curcumin-treated wild-type C. elegans exhibited increased survival during juglone-induced oxidative stress compared with the control treatment. In addition, curcumin reduced the levels of intracellular reactive oxygen species in C. elegans. Moreover, curcumin induced the expression of the gst-4 and hsp-16.2 stress response genes. Lastly, our findings from the mechanistic study in this investigation suggest that the antioxidative effect of curcumin is mediated via regulation of age-1, akt-1, pdk-1, osr-1, unc-43, sek-1, skn-1, sir-2.1, and mev-1. Our study elucidates the diverse modes of action and signaling pathways that underlie the antioxidant activity exhibited by curcumin in vivo.

Differential display analysis of gene expression in invertebrates.

Screening for differentially expressed genes is a straightforward approach to study the molecular basis for changes in gene expression. Differential display analysis has been used by investigators in diverse fields of research since it was developed. Differential display has also been the approach of choice to investigate changes in gene expression in response to various biological challenges in invertebrates. We review the application of differential display analysis of gene expression in invertebrates, and provide a specific example using this technique for novel gene discovery in the nematode Caenorhabditis elegans.

Characterization of a cadmium-inducible isoform of pyruvate carboxylase from Caenorhabditis elegans.

A homologue of pyruvate carboxylase was isolated as an expressed sequence tag during the identification of cadmium-responsive genes in Caenorhabditis elegans. The C. elegans protein, designated PYC-1, is predicted to contain 1,175 amino acids with a molecular mass of 129,284. Amino acid sequence analysis indicates that PYC-1 will be translocated into mitochondria. PYC-1 has high levels of amino acid sequence identity with other pyruvate carboxylases. The highest levels of identity are in the putative transcarboxylation, biotin carboxylation and biotin carboxyl carrier domains.

Cadmium-regulated genes from the nematode Caenorhabditis elegans. Identification and cloning of new cadmium-responsive genes by differential display.

The transition metal cadmium is a pervasive and persistent environmental contaminant that has been shown to be both a human toxicant and carcinogen. To inhibit cadmium-induced damage, cells respond by increasing the expression of genes encoding stress-response proteins. In most cases, the mechanism by which cadmium affects the expression of these genes remains unknown. It has been demonstrated in several instances that cadmium activates gene transcription through signal transduction pathways, mediated by protein kinase C, cAMP-dependent protein kinase, or calmodulin. A codicil is that cadmium should influence the expression of numerous genes. To investigate the ability of cadmium to affect gene transcription, the differential display technique was used to analyze gene expression in the nematode Caenorhabditis elegans. Forty-nine cDNAs whose steady-state levels of expression change 2-6-fold in response to cadmium exposure were identified. The nucleotide sequences of the majority of the differentially expressed cDNAs are identical to those of C. elegans cosmids, yeast artificial chromosomes, expressed sequence tags, or predicted genes. The translated amino acid sequences of several clones are identical to C. elegans metallothionein-1, HSP70, collagens, and rRNAs. In addition, C. elegans homologues of pyruvate carboxylase, DNA gyrase, beta-adrenergic receptor kinase, and human hypothetical protein KIAA0174 were identified. The translated amino acid sequences of the remaining differentially expressed cDNAs encode novel proteins.