Grain size,sucrose level and starch accumulation in developing rice grain

Five rices (Oryza sativa L.) differing in final grain size were studied at the midmilky stage to determine if any factor could be identified which might limit rate of starch accumulation. Only UDP glucose pyrophosphorylase activity increased with increasing grain size. Detached rice panicles incubated in liquid medium containing 1% sucrose and 0.1% glutamine, in addition to minerals and vitamins, produced grains similar to those on intact plants. Sucrose level (0–1.5%) in the medium determined the extent of dry matter and starch accumulation and influenced physiological development of the ripening grains. Chemical and enzymic composition of the grain were similar to previously reported levels in grains of intact panicles analysed at regular intervals after anthesis. Addition of 3-P glycerate or K⁺ to the medium did not improve dry matter accumulation in the developing grain.     

DIASTOLIC OPENING OF THE AORTIC VALVE (AV) IN A CASE OF AORTIC INSUFFICIENCY DUE TO AV FENESTRATION

A patient with severe aortic insufficiency due to fenestration of the non-coronary aortic valve leaflet is described. A preoperative echocardiogram demonstrated early closure of the mitral valve and early diastolic separation of the aortic valve leaflets. These findings disappeared after partial surgical correction and subsequent hemodynamic improvement. Premature opening of the aortic valve is common in severe aortic insufficiency.     

Tradescantia-micronucleus (Trad-MCN) bioassay on clastogenicity of wastewater and in situ monitoring.

The Tradescantia-micronucleus (Trad-MCN) bioassay was used to determine the clastogenicity of wastewater samples collected from the Arena canal which contains effluent from the industrial district Benito Juarez of the city of Queretaro, Mexico. Fifteen wastewater samples which were collected, in most cases, at bi-weekly intervals beginning in September 1986 through February 1988, after a 3-fold dilution were used to treat Tradescantia plant cuttings. The clastogenicity expressed in terms of micronucleus frequencies of treated groups (30 h of treatment without recovery time) was significantly (0.01) higher than that of the tapwater control groups. The Trad-MCN bioassay was also used for in situ monitoring of air pollutants for the clastogenicity at 3 sites near the industrial and residential areas (Flores Magon, Conalep and Bellas Artes) of the city of Queretaro. Fourteen monitoring trips were made to each of the 3 sites at monthly intervals beginning in May 1988 through June 1990. Seasonal variation of micronucleus frequencies was exhibited with the peak clastogenicities shown in May and June 1988, June 1989 and April 1990 at the three sites. Micronucleus frequencies of all the exposed groups at the Conalep site, a predominantly industrial area, were markedly higher than that of the laboratory control groups throughout the 2-year period.     

Regulation of glucose transport in Clone 9 cells by thyroid hormone.

Triiodothyronine (T3) is found to stimulate cytochalasin B-inhibitable glucose transport in Clone 9 cells, a 'non-transformed' rat liver cell line. After an initial lag period of more than 3 h, glucose transport rate is significantly increased at 6 h and reaches more than 3-times the control rate at 24 h. The enhancement of glucose transport by T3 is due to an increase in transport Vmax and occurs in the absence of a change in either the Km for glucose transport (approximately 3 mM) or the Ki for inhibition of transport by cytochalasin B ((1-2).10(-7) M). Consistent with the observed Ki for cytochalasin B, Northern blot analysis of RNA from control and T3-treated cells employing cDNA probes encoding GTs of the human erythrocyte/rat brain/HepG2 cell transporter (GLUT-1), rat muscle/fat cell transporter (GLUT-4), and rat liver transporter (GLUT-2) types indicates expression of only the GLUT-1 mRNA isoform in these cells. The abundance of GLUT-1 mRNA increases approx. 1.9-fold after 24 h of T3 treatment and is accompanied by an approx. 1.3-fold increase in the abundance of GLUT-1 in whole-cell extracts as demonstrated by Western blot analysis employing a polyclonal antibody directed against the 13 amino acid C-terminal peptide of GLUT-1. The more than 3-fold stimulation of glucose transport at 24 h substantially exceeds the fractional increment in transporter abundance suggesting that, in addition to increasing total GLUT-1 abundance, exposure to T3 may result in a translocation of transporters to the plasma membrane or an activation of pre-existing membrane transporter sites.     

Extrachromosomal human immunodeficiency virus type-1 DNA can initiate a spreading infection of HL-60 cells

In this report, we describe a human immunodeficiency virus type-1 (HIV-1)-infected promyelocytic cell line, OM, derived from HL-60 cells. Although the OM cell line was biologically cloned twice, the pattern of HIV-1 expression during culture appeared analogous to a classical acute spreading infection and was inhibited by both azidothymidine and recombinant soluble CD4 treatment. The number of OM cells actually expressing HIV-1 at the beginning of culture was 0%, reached a peak of nearly 100% at 6 weeks, and then fell to less than 10% HIV-1+ cells by 10 weeks. Clonal analysis of the surviving cells verified that stable HIV-1+ OM cells resulted from the spreading infection. Southern analysis confirmed the transmission of HIV-1 through these OM cultures and the occurrence of stable clones which resulted. The initial percentage of OM cells actually harboring the HIV-1 genome was less than 0.1%, indicating nonfaithful transmission of an unintegrated HIV-1 genome during clonal expansion. These results demonstrate that extrachromosomal HIV-1 DNA can contribute to the spread of HIV-1 infection and give rise to cells which have stably integrated HIV-1 provirus.     

Hypertrophic cardiomyopathy associated with left ventricular aneurysm and normal coronary arteries: Case study indicating genetic tendencies of cardiomyopathy

A 50-year-old man presented with hypertrophic obstructive cardiomyopathy (HOC) associated with a left ventricular aneurysm and normal coronary arteries. His history revealed no evidence of myocardial infarction or atypical angina. Physical examination disclosed HOC but did not suggest the presence of an aneurysm. Although the patient was treated medically, heart failure ensued, and he died suddenly while working his farm. Subsequent investigation of the patient's family revealed that three of his five children were also affected by cardiomyopathy, which was especially pronounced in the eldest, a 22-year-old man. The possible hemodynamic relationship between HOC and left ventricular aneurysm is discussed, along with probable indications. The role of left ventricular aneurysm is also presented in relation to the natural history of the disease.     

Growth of Thiobacillus novellus on mixed substrates (mixotrophic growth).

In a mixotrophic environment, Thiobacillus novellus concurrently utilized glucose and thiosulfate but showed no stimulation of growth rate or yield. In most mixotrophic environments examined, the growth rate was lower than the heterotrophic growth rate, the extent of the decrease depending on the concentration and relative proportion of thiosulfate and glucose in the medium. Both thiosulfate and glucose were degraded to their most oxidized products in mixotrophic medium, yet the biomass production in this medium was comparable to that found in heterotrophic medium containing glucose alone at the corresponding concentration. It was postulated that in mixotrophic medium the oxidation of thiosulfate, glucose, or partially that of both was uncoupled from energy generation. These results differ in many respects from those reported earlier by LeJohn et al. (J. Bacteriol. 94: 1484--1491, 1967); experiments designed to exactly duplicate some of the growth conditions employed by these workers did not resolve the discrepancy.     

Lytic enzymes in the autolysis of filamentous fungi

The degrees of autolysis attained by five different genera of filamentous fungi during an incubation period of 60 days, under the same culture conditions were: 87.3% for Penicillium oxalicum; 65.9% for Neurospora crassa; 62.7% for Polystictus versicolor; 51.7% for Aspergillus niger and 23.5% for Nectria galligena. N. crassa, A. niger and P. versicolor reached the end of the autolysis during this incubation period (60 days), whereas P. oxalicum and N. galligena did not.The excretion of the lytic enzymes -N-acetyl-glucosaminidase, -1–3 glucanase, chitinase, invertase and acid phosphatase into the culture medium during growth and autolysis was investigated. The excretion of these enzymes was consistent with the degree of autolysis reached, the maximum excretion belonging to P. oxalicum and the minimum to N. galligena. The N. crassa invertase was excreted into the culture liquid at levels very much higher than the other enzymes studied, and at levels very much higher than the invertases excreted by the other fungi.