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A primary-structure analysis of the 16s rRNA gene was performed with 10 strains representing five described and one unidentified species of the genus Microcystis. The phylogenies determined illustrate the evolutionary affiliations among Microcystis strains, other cyanobacteria, and related plastids and bacteria. A cluster of 10 strains that included hepatotoxic isolates identified as Microcystis aeruginosa formed a monophyletic group. However, the genus Microcystis appeared to be polyphyletic and contained two strains that clustered with unicellular cyanobacteria belonging to the genus Synechococcus. The clustering of related Microcystis strains, including strains involved in the production of the cyclic peptide toxin microcystin, was consistent with cell morphology, gas vacuolation, and the low G+C contents of the genomes. The Microcystis lineage was also distinct from the lineage containing the unicellular genus Synechocystis and the filamentous, heterocystforming genus Nostoc. The secondary structure of a Microcystis 16s rRNA molecule was determined, and genus-specific sequence signatures were used to design primers that permitted identification of the potentially toxic cyanobacteria belonging to the genus Microcystis via DNA amplification.The Cyanobacteria is a diverse bacterial phylum with respect to form, function, and habitat. On the basis of microfossil and geochemical evidence the origin of cyanobacterium-like organisms has been dated to the late Precambrian era. On the basis of the results of phylogenetic studies workers have inferred that the cyanobacterial phylum is 1 of the 11 bacterial phyla (32,42). The possibility that eukaryotic chloroplasts arose from a cyanobacterial ancestor by a symbiotic event has also been inferred on the basis of molecular data (8, 38).Members of the genus Microcystis are a major cause of freshwater noxious cyanobacterial blooms, which have a broad geographical distribution. The microcystins, a family of cyclic heptapeptide toxins that are not synthesized ribosomally (3) and are produced by most members of this genus, cause acute hepatotoxicity in agricultural livestock. Recent epidemiological data have also linked chronic subacute consumption of microcystins to human liver tumor promotion (5). The increasing occurrence of Microcystis blooms in major sources of human drinking water makes identification and prediction of these toxic blooms very important.Due to the variably expressed and minor morphological and developmental characteristics used for identification, classification of cyanobacterial strains at the genus or species level may be ambiguous (29), particularly when laboratory cultures and environmental isolates are compared (7). The current cyanobacterial taxonomy does not provide an unequivocal system for identification of the toxigenic and bloom-forming genus Microcystis (20). Depending on the taxonomic treatises used for classification, which differ in their emphasis on the cell size, shape, buoyancy, and toxicity of the planktonic, freshwater cyanobacteria, d...

Cyanobacteria are a highly diverse group in relation to form, function, and habitat. Current cyanobacterial systematics relies on the observation of minor and plastic morphological characters. Accurate and reliable delineation of toxic and bloom-forming strains of cyanobacteria has not been possible by traditional methods. We have designed general primers to the phycocyanin operon (cpc gene) and developed a PCR which allows the amplification of a region of this gene, including a variable intergenic spacer sequence. Because of the specificity of this PCR for cyanobacterial isolates, the assay is appropriate for the rapid and reliable identification of strains in freshwater samples. Successive restriction endonuclease digestion of this amplification product, with a total of nine enzymes, yielded many identifying DNA profiles specific to the various taxonomic levels of cyanobacteria. The restriction enzyme profiles for MspI, RsaI, and TaqI were conserved for strains within each of the eight genera (40 strains) studied and clearly discriminated among these genera. Intrageneric delineation of strains was revealed by the enzymes AluI, CfoI, and HaeIII for members of the genus Microcystis, while strains of genus Anabaena were differentiated by the digestion patterns provided by AluI, CfoI, and ScrFI. Phenetic and cladistic analyses of the data were used to infer the genetic relatedness and evolution of toxic and bloom-forming cyanobacteria.

Although PIWI-interacting RNAs (piRNAs) account for the largest class of the small non-coding RNA superfamily, virtually nothing is known of their function in human carcinogenesis. Once thought to be expressed solely in the germ line where they safeguard the genome against transposon-induced insertional mutations, piRNAs are now believed to play an active role in somatic gene regulation through sequence-specific histone modification and DNA methylation. In the current study, we investigate the role of piRNA-021285 (piR-021285) in the regulation of the breast cancer methylome. Genotypic screening of a panel of single-nucleotide polymorphism (SNP)-containing piRNAs revealed a significant association between SNP rs1326306 G>T in piR-021285 and increased likelihood for breast cancer in a Connecticut-based population (441 cases and 479 controls). Given nascent but compelling evidence of piRNA-mediated gene-specific methylation in the soma, a genome-wide methylation screen was then carried out using wild type (WT) and variant piR-021285 mimic-transfected MCF7 cells to explore whether the observed association could be attributed in part to piR-021285-induced methylation at cancer-relevant genes. We found significant methylation differences at a number of experimentally implicated breast cancer-related genes, including attenuated 5' untranslated region (UTR)/first exon methylation at the proinvasive ARHGAP11A gene in variant mimic-transfected cells. Follow-up functional analyses revealed both concurrent increased ARHGAP11A mRNA expression and enhanced invasiveness in variant versus WT piR-021285 mimic-transfected breast cancer cell lines. Taken together, our findings demonstrate the first evidence supporting a role of piRNAs, a novel group of non-coding RNA, in human tumorigenesis via a piRNA-mediated epigenetic mechanism, which warrants further confirmation and investigation.

Background:Prepectoral breast reconstruction is increasingly popular. This study compares complications between 2 subpectoral and 1 prepectoral breast reconstruction technique.Methods:Between 2008 and 2015, 294 two-staged expander breast reconstructions in 213 patients were performed with 1 of 3 surgical techniques: (1) Prepectoral, (2) subpectoral with acellular dermal matrix (ADM) sling (“Classic”), or (3) subpectoral/subserratus expander placement without ADM (“No ADM”). Demographics, comorbidities, radiation therapy, and chemotherapy were assessed for correlation with Clavien IIIb score outcomes. Follow-up was a minimum of 6 months.Results:Surgical cohorts (n = 165 Prepectoral; n = 77 Classic; n = 52 No ADM) had comparable demographics except Classic had more cardiac disease (P = 0.03), No ADM had higher body mass index (BMI) (P = 0.01), and the Prepectoral group had more nipple-sparing mastectomies (P < 0.001). Univariate analysis showed higher expander complications with BMI ≥ 40 (P = 0.05), stage 4 breast cancer (P = 0.01), and contralateral prophylactic mastectomy (P = 0.1), whereas implant complications were associated with prior history of radiation (P < 0.01). There was more skin necrosis (P = 0.05) and overall expander complications (P = 0.01) in the Classic cohort, whereas the No ADM group trended toward the lowest expander complications among the 3. Multivariate analysis showed no difference in overall expander complication rates between the 3 groups matching demographics, mastectomy surgery, risks, and surgical technique.Conclusions:Prepectoral and subpectoral Classic and No ADM breast reconstructions demonstrated comparable grade IIIb Clavien score complications. BMI > 40, stage 4 cancer, and contralateral prophylactic mastectomy were associated with adverse expander outcomes and a prior history of radiation therapy adversely impacted implant outcomes. Ninety-day follow-up for expander and implant complications may be a better National Surgical Quality Improvement Program measure.