Identification and characterization of large-effect quantitative trait loci for grain yield under lowland drought stress in rice using bulk-segregant analysis.

An F(4:5) population of 490 recombinant inbred lines (RILs) from the cross Apo/(2*)Swarna was used to detect quantitative trait loci (QTL) with large effects on grain yield under drought stress using bulk-segregant analysis (BSA). Swarna is an important rainfed lowland rice variety grown on millions of hectares in Asia, but is highly susceptible to drought and aerobic soil conditions. Apo is an aerobic-adapted variety with moderate tolerance to drought. Two rice microsatellite (RM) markers, RM324, and RM416, located on chromosomes 2 and 3, respectively, were shown via BSA to be strongly associated with yield under lowland drought stress. The effects of these QTL were tested in a total of eight hydrological environments over a period of 3 years. The QTL linked to RM416 (DTY(3.1)) had a large effect on grain yield under severe lowland drought stress, explaining about 31% of genetic variance for the trait (P < 0.0001). It also explained considerable variance for yield under mild stress in lowland conditions and aerobic environments. To our knowledge this is the first reported QTL that has a large effect on yield in both lowland drought and aerobic environments. The QTL linked to RM324 (DTY(2.1)) had a highly significant effect on grain yield in lowland drought stress (R(2) = 13-16%) and in two aerobic trials. The effect of these QTL on grain yield was verified to be not mainly due to phenology differences. Effects of DTY(3.1) on yield under stress have been observed in several other rice mapping populations studied at IRRI. Results of this study indicate that BSA is an effective method of identifying QTL alleles with large effects on rice yield under severe drought stress. The Apo alleles for these large-effect QTL for grain yield under drought and aerobic conditions may be immediately exploited in marker-assisted-breeding to improve the drought tolerance of Swarna.

Cell cycle phase, cellular Ca2+ and development in Dictyostelium discoideum.

In Dictyostelium discoideum, the initial differentiation of cells is regulated by the phase of the cell cycle at starvation. Cells in S and early G2 (or with a low DNA content) have relatively high levels of cellular Ca2+ and display a prestalk tendency after starvation, whereas cells in mid to late G2 (or with a high DNA content) have relatively low levels of Ca2+ and display a prespore tendency. We found that there is a correlation between cytosolic Ca2+ and cell cycle phase, with high Ca2+ levels being restricted to cells in the S and early G2 phases. As expected on the basis of this correlation, cell cycle inhibitors influence the proportions of amoebae containing high or low Ca2+. However, it has been reported that in the rtoA mutant, which upon differentiation gives rise to many more stalk cells than spores (compared to the wild type), initial cell-type choice is independent of cell cycle phase at starvation. In contrast to the wild type, a disproportionately large fraction of rtoA amoebae fall into the high Ca2+ class, possibly due to an altered ability of this mutant to transport Ca2+.

Quantum Entanglement and Chemical Reactivity.

The water molecule and a hydrogenic abstraction reaction are used to explore in detail some quantum entanglement features of chemical interest. We illustrate that the energetic and quantum-information approaches are necessary for a full understanding of both the geometry of the quantum probability density of molecular systems and the evolution of a chemical reaction. The energy and entanglement hypersurfaces and contour maps of these two models show different phenomena. The energy ones reveal the well-known stable geometry of the models, whereas the entanglement ones grasp the chemical capability to transform from one state system to a new one. In the water molecule the chemical reactivity is witnessed through quantum entanglement as a local minimum indicating the bond cleavage in the dissociation process of the molecule. Finally, quantum entanglement is also useful as a chemical reactivity descriptor by detecting the transition state along the intrinsic reaction path in the hypersurface of the hydrogenic abstraction reaction corresponding to a maximally entangled state.

In vitro induction of PDT resistance in HT29, HT1376 and SK-N-MC cells by various photosensitizers.

Our approach to examine the mechanism(s) of action for photodynamic therapy (PDT) has been via the generation of PDT-resistant cell lines. In this study we used three human cell lines, namely, human colon adenocarcinoma (HT29), human bladder carcinoma and human neuroblastoma. The three photosensitizers used were Photofrin, Nile Blue A and aluminum phthalocyanine tetrasulfonate. The protocol for inducing resistance consisted of repeated in vitro photodynamic treatments with a photosensitizer to the 1-10%-survival level followed by regrowth of single surviving colonies. Varying degrees of resistance were observed. The three induced variants of the HT29 cell line were the most extensively studied. Their ratios of increased survival at the LD90 level range between 1.5- and 2.62-fold more resistant.

Complications of heroin injections of the neck.

The purpose of this paper is to emphasize the importance of heroin injections in the neck as an etiology of superficial and deep neck infections and to familiarize the otolaryngologist with the problems in the diagnosis and management of such infections. This study represents the first series to be reported in the world literature of patients with neck infections secondary to heroin injections. Fifty-seven patients with neck infections related to injection of heroin in the neck (main-lining) were studied. These patients were admitted to Detroit General Hospital during the three-year period between January 1974 and December 1976. The clinical signs and symptoms, location of the abscesses, soft tissue radiographs of the neck, arteriograms and ultrasound examinations of the neck are discussed. The diagnostic evaluation and the treatment of the heroin addict who presents with an inflammatory neck mass are outlined, emphasizing the difficulty and the importance of differentiating between cellulitis, abscess, and pseudoaneurysms of the carotid and subclavian arteries.

Motoneuron excitability and the F wave.

For three motoneuron pools that differ in excitability to Ia inputs [tibialis anterior (TA), abductor pollicis brevis (APB), and soleus], F-wave parameters were measured at rest, during voluntary contraction, and following prolonged vibration. There was an inverse relationship between F-wave chronodispersion and F-wave persistence at rest, and this appeared to be related to the ease of recording the H reflex for the motoneuron pool. During a steady voluntary contraction, overall F-wave activity increased in amplitude but decreased in duration for TA and APB. Following vibration of the test muscle at 50 HZ for 10 min there was a long-lasting depression of the H reflexes of TA and APB, but no significant change in F-wave measurements. These findings are consistent with the view that reflex discharges can prevent F waves in low-threshold motor units, and that chronodispersion is affected by the extent of reflex activity; that is, chronodispersion and related F-wave measurements do not measure motor properties exclusively. The findings also suggest that F waves provide a flawed measure of the excitability of the motoneuron pool.

Distinct genomic copy number in mitochondria of different mammalian organs.

This study shows that mitochondria in liver, kidney, heart, and brain of the mouse have a distinct mitochondrial density. It also demonstrates that the mtDNA copy number per mitochondrion is organ-specific. A reliable method of determining mitochondrial density per organ is by stereological analysis of tissue sections while mtDNA quantitation is by the use of radiolabelled mtDNA probe. This is the first study in which a comprehensive examination of mitochondrial density and quantitation of mitochondrial genomes in mouse organs have been done. In summary the variability is not only in mitochondrial density but also in genomic copy number in mitochondria of various tissues.

Differential effects of cisplatin on mouse hepatic and renal mitochondrial DNA.

The objective of this study was to determine if the nephrotoxic effects induced by cisplatin were correlated to mitochondrial DNA damage. Comparisons were made with the liver since hepatotoxicity is rarely observed. Cisplatin doses of 10, 20 and 40 mg/kg were administered intraperitoneally to C57BL/6J mice. Mitochondrial DNA was isolated from both the hepatic and renal tissues and quantitated by hybridization with a specific mitochondrial probe. Cisplatin caused differential effects on mouse hepatic and renal mitochondrial DNA. The 10 and 20 mg/kg dose caused an elevation in mitochondrial DNA levels in the hepatic, but no increase in the renal tissue was observed. This is the first study demonstrating an organ specific effect of cisplatin at the DNA level.

Interactions of saprophytic yeasts with a nor mutant of Aspergillus flavus.

The nor mutant of Aspergillus flavus has a defective norsolorinic acid reductase, and thus the aflatoxin biosynthetic pathway is blocked, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We developed a visual agar plate assay to monitor yeast strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment of the nor mutant. We identified yeast strains that reduced the red-orange pigment accumulation in the nor mutant. These yeasts also reduced aflatoxin accumulation by a toxigenic strain of A. flavus. These yeasts may be useful for reducing aflatoxin contamination of food commodities.

Photodynamic therapy with photofrin in combination with Buthionine Sulfoximine (BSO) of human glioma in the nude rat.

High concentrations of cellular glutathione (GSH) within tumour cells may reduce the ability of photodynamic therapy (PDT) to selectively destroy tumour, consequently, a means of improving the therapeutic ratio of PDT in brain tumour is necessary. Therefore, we hypothesize that PDT in combination with Buthionine Sulfoximine (BSO), an agent which lowers cellular glutathione, can significantly enhance destruction of U87 and U251n tumour cells. PDT was performed using Photofrin as a photosensitiser in combination with BSO administration on male Fisher rats with intracerebral U87 and on non-tumour rats (administered at different optical doses in combination with Photofrin). In vitro experimentation utilising colony forming, cell cytotoxicity, and matrigel artificial basement membrane invasion assays showed significant enhancement of tumour kill and significant reduction of migration in tumour cells treated with BSO in combination with Photofrin PDT in comparison with individual therapies for both U87 and U251n cell lines. In vivo combination PDT-BSO treatment of U87 tumour rats exhibited significantly more tumour necrosis than individual treatments. In conclusion, our data suggests BSO enhances Photofrin PDT treatment of human glioma.