Dinoflagellate taxonomy is based primarily on morphology and morphometric data that can be difficult to obtain. In contrast, molecular data can be rapidly and cost-effectively acquired, which has led to a rapid accumulation of sequence data in GenBank. Currently there are no systematic criteria for utilizing taxonomically unassigned sequence data to identify putative species that could in turn serve as a basis for testable hypotheses concerning the taxonomy, diversity, distribution, and toxicity of these organisms. The goal of this research was to evaluate whether simple, uncorrected genetic distances (p) calculated using ITS1/5.8S/ITS2 (ITS region) rDNA sequences could be used to develop criteria for recognizing putative species before formal morphological evaluation and classification. The current analysis used sequences from 81 dinoflagellate species belonging to 14 genera. For this diverse assemblage of dinoflagellate species, the within-species genetic distances between ITS region copies (p 5 0.000-0.021 substitutions per site) were consistently less than those observed between species (p 5 0.042-0.580). Our results indicate that a between-species uncorrected genetic distance of p! 0.04 could be used to delineate most free-living dinoflagellate species. Recently evolved species, however, may have ITS p values <0.04 and would require more extensive morphological and genetic analyses to resolve. For most species, the sequence of the dominant ITS region allele has the potential to serve as a unique species-specific ''DNA barcode'' that could be used for the rapid identification of dinoflagellates in field and laboratory studies.

The cDNA for a novel truncated progesterone receptor (PR-M) was previously cloned from human adipose and aortic cDNA libraries. The predicted protein sequence contains 16 unique N-terminal amino acids, encoded by a sequence in the distal third intron of the progesterone receptor PR gene, followed by the same amino acid sequence encoded by exons 4 through 8 of the nuclear PR. Thus, PR-M lacks the N terminus A/B domains and the C domain for DNA binding, whereas containing the hinge and hormone-binding domains. In this report, we have localized PR-M to mitochondria using immunofluorescent localization of a PR-M-green fluorescent protein (GFP) fusion protein and in Western blot analyses of purified human heart mitochondrial protein. Removal of the putative N-terminal mitochondrial localization signal obviated association of PR-M with mitochondria, whereas addition of the mitochondrial localization signal to green fluorescent protein resulted in mitochondrial localization. Immunoelectron microscopy and Western blot analysis after mitochondrial fractionation identified PR-M in the outer mitochondrial membrane. Antibody specificity was shown by mass spectrometry identification of a PR peptide in a mitochondrial membrane protein isolation. Cell models of overexpression and gene silencing of PR-M demonstrated a progestin-induced increase in mitochondrial membrane potential and an increase in oxygen consumption consistent with an increase in cellular respiration. This is the first example of a truncated steroid receptor, lacking a DNA-binding domain that localizes to the mitochondrion and initiates direct non-nuclear progesterone action. We hypothesize that progesterone may directly affect cellular energy production to meet the increased metabolic demands of pregnancy.

We sought to determine if apoptosis in the chorion of fetal membranes was increased in patients with preterm premature rupture of membranes (PPROM) with histological chorioamnionitis. Using the TUNEL (terminal uridine deoxynucleotidyl transferase dUTP nick-end labeling) method (ApopTag Plus kit; Oncor, Gaithersburg, MD), apoptosis was quantified. Of the 47 subjects with PPROM, 18 lacked sufficient chorion for quantification (confirmed by cytokeratin staining). In the remaining 30 subjects, fetal membranes with and without chorioamnionitis were examined and apoptosis was quantified. There were no differences in maternal age, race, insurance, cesarean rate, or gestational age between groups. The chorion of fetal membranes from PPROM patients with chorioamnionitis had significantly more apoptotic nuclei than those without chorioamnionitis (19.1 versus 0.8; P= .005). Of the 17 subjects excluded for absence of chorion, 16 (94%) had at least moderate chorioamnionitis. This investigation suggests that apoptosis is accelerated in the chorion of PPROM subjects with chorioamnionitis. Absence of the chorion in 37% of subjects is supportive of the hypothesis that inflammation accelerates cell death and destruction of the chorion.

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