The Metabolism of Gibberellin A20 to Gibberellin A1 by Tall and Dwarf Mutants of Oryza sativa and Arabidopsis thaliana

The purpose of this study was to demonstrate the metabolism of gibberellin A20 (GA20) to gibberellin A1 (GA1) by tall and mutant shoots of rice (Oryza sativa L.) and Arabidopsis thaliana (L.) Heynh. The data show that the tall and dx mutant of rice and the tall and ga5 mutant of Arabidopsis metabolize GA20 to GA1. The data also show that the dy mutant of rice and the ga4 mutant of Arabidopsis block the metabolism of GA20 to GA1. [17-13C,3H]GA20 was fed to tall and the dwarf mutants, dx and dy, of rice and tall and the dwarf mutants, ga5 and ga4, of Arabidopsis. The metabolites were analyzed by high-performance liquid chromatography and full-scan gas chromatography-mass spectrometry together with Kovats retention index data. For rice, the metabolite [13C]GA, was identified from tall and dx seedlings; [13C]GA1 was not identified from the dy seedlings. [13C]GA29 was identified from tall, dx, and dy seedlings. For Arabidopsis, the metabolite [13C]GA1 was identified from tall, ga5, and ga4 plants. The amount of [13C]GA1 from ga4 plants was less than 15% of that obtained from tall and ga5 plants. [13C]GA29 was identified from tall, ga5, and ga4 plants. [13C]GA5 and [13C]GA3 were not identified from any of the six types of plant material.     

Detecting substitution-rate heterogeneity among regions of a nucleotide sequence

Likelihood-ratio statistics are proposed to test for heterogeneity in nucleotide substitution rate among regions of a DNA sequence. The tests examine three-sequence phylogenies, and two specific tests are proposed: a test to detect rate heterogeneity among genic regions within a sequence, over all evolutionary lineages; and a test to detect rate heterogeneity among regions in a specific evolutionary lineage. Simulations examine the ability of tests to detect a single region that varies in nucleotide substitution rate relative to the remainder of the sequence. A 50-bp region with a fivefold substitution-rate increase can be detected > or = 90% of the time when it is found in all three lineages of the phylogeny, and a 50-bp region of fivefold rate increase can be detected with approximately 70% power when it is found in only one evolutionary lineage. Simulation also examines the effect of transition- and transversion-rate differences. The tests are applied to published DNA sequences. While the tests are powerful, significant results can be difficult to interpret biologically.      

Predictors of mortality of patients newly diagnosed with clinical type 2 diabetes: a 5-year follow up study

Background

At diabetes diagnosis major decisions about life-style changes and treatments are made based on characteristics measured shortly after diagnosis. The predictive value for mortality of these early characteristics is widely unknown. We examined the predictive value of patient characteristics measured shortly after diabetes diagnosis for 5-year all-cause and cardiovascular mortality with special reference to self-rated general health.

Methods

Data were from a population-based sample of 1,323 persons newly diagnosed with clinical diabetes and aged 40 years or over. Possible predictors of mortality were investigated in Cox regression models.

Results

Multivariately patients who rated their health less than excellent experienced increased all-cause and cardiovascular mortality. These end-points also increased with sedentary life-style, relatively young age at diagnosis and presence of cardiovascular disease (CVD) at diagnosis. Further predictors of all-cause mortality were male sex, low body mass index and cancer, while cardiovascular mortality increased with urinary albumin concentration.

Conclusions

We found that patients who rated their health as less than excellent had increased 5-year mortality, similar to that of patients with prevalent CVD, even when biochemical, clinical and life-style variables were controlled for. This finding could motivate doctors to discuss perceptions of health with newly diagnosed diabetic patients and be attentive to patients with suboptimal health ratings. Our findings also confirm that life-style changes and optimizing treatment are particularly relevant for relatively young and inactive patients and those who already have CVD or (micro)albuminuria at the time of diabetes diagnosis.     

Durable remission of diabetes after bariatric surgery: What is the underlying pathway?

Background: In the past, type 2 diabetes mellitus (DM) was regarded as a progressive, incurable disease for which palliative therapy could not, over the long term, prevent the associated amputations, blindness, renal failure, and early mortality. This is no longer true. Full and durable remission of type 2 DM, with major decreases in morbidity and mortality, is now achieved regularly with several types of surgery that reduce contact between food and the foregut.Objectives: The aims of this article are to review the impact of bariatric surgery on obesity, remission of DM, and obesity-related morbidity and mortality, and the possible mechanisms for this advance.Methods: This article is based on our 2 meta-analyses of the literature published through April 30, 2006, as well as the most significant reports in the bariatric surgical literature that have been published in English since April 30, 2006. The studies included in our second meta-analysis provided the details of the methodology for the present literature review, including the levels of evidence.Results: Results of our 2 meta-analyses were published previously. Briefly, the analyses revealed that the clinical and laboratory manifestations of type 2 DM resolved or improved in most of the patients who underwent bariatric surgery; the responses were greatest in the patients who lost the most excess body weight; and the improvements were maintained for ≥2 years. The studies reported that intestinal operations such as gastric bypass reduced contact between food and the foregut, produced full and durable remission of DM, reduced mortality, and reversed other comorbidities associated with severe obesity (eg, asthma, gastroesophageal reflux, hypertension, stress incontinence). Insulin levels decreased markedly after surgery, as did glycosylated hemoglobin (A1C) and fasting blood glucose levels. Although these effects were initially attributed to weight loss, the rapid reversal of DM within a matter of days after surgery suggest that bariatric surgery changes the signaling mechanism of the gut with pancreatic islet cells, muscles, fat, the liver, and other organs.Conclusions: Bariatric surgery has opened new vistas, producing durable full remission of type 2 DM—a breakthrough previously considered impossible—with normalization of A1C levels over time and discontinuation of all antidiabetes medication for many patients. These advances create new opportunities for exploring the mechanisms of type 2 DM and its control through pharmaceutical approaches. DM is no longer an irreversible, incurable, or hopeless disease.     

Sindbis virus glycoprotein E1 is divided into two discrete domains at amino acid 129 by disulfide bridge connections

The E1 membrane glycoprotein of Sindbis virus contains structural and functional domains, which are conformationally dependent on the presence of intramolecular disulfide bridges (B. A. Abell and D. T. Brown, J. Virol. 67:5496-5501, 1993; R. P. Anthony, A. M. Paredes, and D. T. Brown, Virology 190:330-336, 1992). We have examined the disulfide bonds in E1 and have determined that the E1 membrane glycoprotein contains two separate sets of interconnecting disulfide linkages, which divide the protein into two domains at amino acid 129. These separate sets of disulfides may stabilize and define the structural and functional regions of the E1 protein.     

THE BIOCHEMICAL ANALYSIS OF SOME ESTUARINE PHYTOPLANKTON SPECIES. I. FATTY ACID COMPOSITION12

The fatty acid composition of 10 species of estuarine phytoplankton was determined using gas-liquid chromatography. Nine of the species were isolated from Yaquina Bay, Oregon. These species were common components of the phytoplankton of the bay. The tenth species, Isochrysis galbana, was obtained from the Culture Collection of Algae at Indiana University. The 10 organisms comprised 3 species of Chlorophyta, 1 species of Cryptophyta, and 6 species of Chrysophyta. Twenty-eight fatty acids were found in the 10 species. The fatty acids common to all species were 14:0, 16:0, 16:1, 13:0, 18:1, and 18:2. The Chlorophyta were distinguished by a high content of linolenic acid, 18:3. The diatoms were distinguished by very low amounts of C₁₈ acids and high proportion of 20:5. All species contained a high proportion of palmitic acid, 16:0.     

Effects of Step-Wise Increases in Dietary Carbohydrate on Circulating Saturated Fatty Acids and Palmitoleic Acid in Adults with Metabolic Syndrome

Recent meta-analyses have found no association between heart disease and dietary saturated fat; however, higher proportions of plasma saturated fatty acids (SFA) predict greater risk for developing type-2 diabetes and heart disease. These observations suggest a disconnect between dietary saturated fat and plasma SFA, but few controlled feeding studies have specifically examined how varying saturated fat intake across a broad range affects circulating SFA levels. Sixteen adults with metabolic syndrome (age 44.9±9.9 yr, BMI 37.9±6.3 kg/m²) were fed six 3-wk diets that progressively increased carbohydrate (from 47 to 346 g/day) with concomitant decreases in total and saturated fat. Despite a distinct increase in saturated fat intake from baseline to the low-carbohydrate diet (46 to 84 g/day), and then a gradual decrease in saturated fat to 32 g/day at the highest carbohydrate phase, there were no significant changes in the proportion of total SFA in any plasma lipid fractions. Whereas plasma saturated fat remained relatively stable, the proportion of palmitoleic acid in plasma triglyceride and cholesteryl ester was significantly and uniformly reduced as carbohydrate intake decreased, and then gradually increased as dietary carbohydrate was re-introduced. The results show that dietary and plasma saturated fat are not related, and that increasing dietary carbohydrate across a range of intakes promotes incremental increases in plasma palmitoleic acid, a biomarker consistently associated with adverse health outcomes.