Cardiolipin biosynthesis and remodeling enzymes are altered during development of heart failure.

Cardiolipin (CL) is responsible for modulation of activities of various enzymes involved in oxidative phosphorylation. Although energy production decreases in heart failure (HF), regulation of cardiolipin during HF development is unknown. Enzymes involved in cardiac cardiolipin synthesis and remodeling were studied in spontaneously hypertensive HF (SHHF) rats, explanted hearts from human HF patients, and nonfailing Sprague Dawley (SD) rats. The biosynthetic enzymes cytidinediphosphatediacylglycerol synthetase (CDS), phosphatidylglycerolphosphate synthase (PGPS) and cardiolipin synthase (CLS) were investigated. Mitochondrial CDS activity and CDS-1 mRNA increased in HF whereas CDS-2 mRNA in SHHF and humans, not in SD rats, decreased. PGPS activity, but not mRNA, increased in SHHF. CLS activity and mRNA decreased in SHHF, but mRNA was not significantly altered in humans. Cardiolipin remodeling enzymes, monolysocardiolipin acyltransferase (MLCL AT) and tafazzin, showed variable changes during HF. MLCL AT activity increased in SHHF. Tafazzin mRNA decreased in SHHF and human HF, but not in SD rats. The gene expression of acyl-CoA: lysocardiolipin acyltransferase-1, an endoplasmic reticulum MLCL AT, remained unaltered in SHHF rats. The results provide mechanisms whereby both cardiolipin biosynthesis and remodeling are altered during HF. Increases in CDS-1, PGPS, and MLCL AT suggest compensatory mechanisms during the development of HF. Human and SD data imply that similar trends may occur in human HF, but not during nonpathological aging, consistent with previous cardiolipin studies.

A p53-dependent S-phase checkpoint helps to protect cells from DNA damage in response to starvation for pyrimidine nucleotides

Normal mammalian cells arrest primarily in G1 in response to N-(phosphonacetyl)-l-aspartate (PALA), which starves them for pyrimidine nucleotides, and do not generate or tolerate amplification of the CAD gene, which confers resistance to PALA. Loss of p53, accompanied by loss of G1 arrest, permits CAD gene amplification and the consequent formation of PALA-resistant colonies. We have found rat and human cell lines that retain wild-type p53 but have lost the ability to arrest in G1 in response to PALA. However, these cells still fail to give PALA-resistant colonies and are protected from DNA damage through the operation of a second checkpoint that arrests them reversibly within S-phase. This S-phase arrest, unmasked in the absence of the G1 checkpoint, is dependent on p53 and independent of p21/waf1.

Mechanisms of G2 Arrest in Response to Overexpression of p53

Overexpression of p53 causes G2 arrest, attributable in part to the loss of CDC2 activity. Transcription of cdc2 and cyclin B1, determined using reporter constructs driven by the two promoters, was suppressed in response to the induction of p53. Suppression requires the regions −287 to −123 of the cyclin B1 promoter and −104 to −74 of the cdc2 promoter. p53 did not affect the inhibitory phosphorylations of CDC2 at threonine 14 or tyrosine 15 or the activity of the cyclin-dependent kinase that activates CDC2 by phosphorylating it at threonine 161. Overexpression of p53 may also interfere with the accumulation of CDC2/cyclin B1 in the nucleus, required for cells to enter mitosis. Constitutive expression of cyclin B1, alone or in combination with the constitutively active CDC2 protein T14A Y15F, did not reverse p53-dependent G2 arrest. However, targeting cyclin B1 to the nucleus in cells also expressing CDC2 T14A Y15F did overcome this arrest. It is likely that several distinct pathways contribute to p53-dependent G2 arrest.

Analysis of Promoter Activity for the Gene Encoding Pyruvate Orthophosphate Dikinase in Stably Transformed C4 Flaveria Species1

The C4 enzyme pyruvate orthophosphate dikinase is encoded by a single gene, Pdk, in the C4 plant Flaveria trinervia. This gene also encodes enzyme isoforms located in the chloroplast and in the cytosol that do not have a function in C4 photosynthesis. Our goal is to identify cis-acting DNA sequences that regulate the expression of the gene that is active in the C4 cycle. We fused 1.5 kb of a 5′ flanking region from the Pdk gene, including the entire 5′ untranslated region, to the uidA reporter gene and stably transformed the closely related C4 species Flaveria bidentis. β-Glucuronidase (GUS) activity was detected at high levels in leaf mesophyll cells. GUS activity was detected at lower levels in bundle-sheath cells and stems and at very low levels in roots. This lower-level GUS expression was similar to the distribution of mRNA encoding the nonphotosynthetic form of the enzyme. We conclude that cis-acting DNA sequences controlling the expression of the C4 form in mesophyll cells and the chloroplast form in other cells and organs are co-located within the same 5′ region of the Pdk gene.

Development of a Mechanism and Process to Continuously Produce Spherical, Torrefied Biomass

Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2016-06-17 02:15:25.215

Statement on metropolitan school desegregation : a report of the United States Commission on Civil Rights /

Mode of access: Internet.

History of Mohammedanism, and its sects; derived chiefly from oriental sources.

Mode of access: Internet.

The Marine Algae of Florida with special reference to the Dry Tortugas.

Bibliography: p. 213.

Array automated assembly : phase 2, quarterly report /

Includes bibliographical references (page 61).

Array automated assembly : phase 2, quarterly report /

Includes bibliographical references (page 43).

Array automated assembly : phase 2, quarterly report /

Includes bibliographical references (page 43).

Goldsmith's history of England : from the invasion of Julius Caesar to the death of George II with a continuation to the present time /

Mode of access: Internet.

Amendments to the charter of the city of Grand Rapids, and to other municipal acts affecting said city, passed by the legislature in the years 1885, 1887 and 1889.

Mode of access: Internet.

The lost found, and the wanderer welcomed.

The lost sheep.--The lost coin.--The prodigal son.

Story of my life; an account of what I have thought and said and done in my ministry of more than fifty-three years in Christian lands and among the heathen ...

Mode of access: Internet.