Evaluation of monoammonium phosphate and bacterial strains to increase tree growth and fruit yield in apple replant problem soil

The long-term effects of biological agents alone and in combination with monoammonium phosphate on tree growth and fruit production of apple trees planted on apple replant soil was studied for five years. Application of monoammonium phosphate (MAP) in the year of planting increased shoot growth, cross-sectional trunk area and fruit yield of McIntosh on M.26 rootstock for the first two years. The application of bacterial agents alone were not effective in increasing young tree growth except BACT-1 in 1987. None of the bacterial agents increased fruit yield when applied alone. The addition of certain bacterial agents to MAP application increased young tree growth in various years. The combination of bacterial agent B-10 and MAP reduced young tree growth and yield compared with the MAP treatment alone. These results suggest that the application of MAP alone may be sufficient to alleviate the replant problem and the addition of BACT-1, EBW-4 or B8 bacterial agents to this treatment may be beneficial to increase tree growth in some years. Contribution number 822. Contribution number 822.     

Improving the mineral reserves and protein quality of maize (Zea mays L.) kernels using unique genes

The effects of the maize genes, o ₂ and Mal, on the concentrations of mineral nutrient cations and amino acid levels in mature maize (Zea mays L) kernels of various inbred lines were studied. Previously, the o ₂ gene has been used to improve the protein quality and increase the mineral nutrient content of kernels from some inbred lines. Genotypes possessing the Mal (multiple aleurone layer) gene, contain more than one row of aleurone cells in their kernels and this gene enhances the effect of the o ₂gene on improving kernel protein quality. Incorporating these genes into the maize genome increased accumulation of several mineral nutrients (including Ca, Mg, Zn, Fe, Mn, Zn and Cu) in some of the experimental lines studied. The physiological basis for this increase of mineral nutrients in the kernels is discussed. The effect of the Mal gene on the kernel amino acid composition and protein quality was also examined. Possibly, these genes could be used in combination in breeding programs to improve kernel quality and nutritional value of maize.     

Sucrose Synthase,Starch Accumulation,and Tomato Fruit Sink Strength

Contrasting evidence has accumulated regarding the role of acid invertase and sucrose synthase in tomato fruit sink establishment and maintenance. In this work the relationships among the activities of sucrose synthase and acid invertase, Lycopersicon esculentum Mill cv UC-82B fruit growth, and starch accumulation were analyzed in fruit at 0 to 39 d after anthesis. Sucrose synthase, but not acid invertase, was found to be positively correlated with tomato fruit relative growth rate and with starch content in the pericarp tissue. A similar association between sucrose synthase activity and starch accumulation was also evident in the basal portion of the stem. Heat-shock treatments, which inhibited the increase in sucrose synthase activity at the beginning of the light period and had no effect on acid invertase activity, were used to examine the importance of sucrose synthase in relation to sucrose metabolism and starch synthesis. After the heat-shock treatment, concomitantly with the suppressed sucrose synthase activity relative to the controls, there was a reduction in sucrose cleavage and starch accumulation. These data substantiate the conclusion that, during the early phases of tomato fruit development, sucrose synthase rather than acid invertase is the dominant enzyme in metabolizing imported sucrose, which in turn plays a part in regulating the import of sucrose into the fruit.     

Temperature-dependent sex determination in reptiles: Proximate mechanisms,ultimate outcomes,and practical applications

In many egg-laying reptiles, the incubation temperature of the egg determines the sex of the offspring, a process known as temperature-dependent sex determination (TSD). In TSD sex determination is an “all or none” process and intersexes are rarely formed. How is the external signal of temperature transduced into a genetic signal that determines gonadal sex and channels sexual development? Studies with the red-eared slider turtle have focused on the physiological, biochemical, and molecular cascades initiated by the temperature signal. Both male and female development are active processes—rather than the crganized/default system characteristic of vertebrates with genotypic sex determination—that require simultaneous activation and suppression of testis- and ovary-determining cascades for normal sex determination. It appears that temperature accomplishes this end by acting on genes encoaing for steroidogenic enzymes and steroid hormone receptors and modifying the endocrine microenvironment in the embryo. The temperature experienced in development also has long-term functional outcomes in addition to sex determination. Research with the leopard gecko indicates that incubation temperature as well as steroid hormones serve as organizers in shaping the adult phenotype, with temperature modulating sex hormone action in sexual differentiation. Finally, practical applications of this research have emerged for the conservation and restoration of endangered egg-laying reptiles as well as the embryonic development of reptiles as biomarkers to monitor the estrogenic effects of common environmental contaminants. © 1994 Wiley-Liss, Inc.     

Comprehensive assay for pyrazinamide, rifampicin and isoniazid with its hydrazine metabolites in human plasma by column liquid chromatography

A comprehensive assay for determination of pyrazinamide (PZA), rifampicin (RIF), isoniazid (INH) and hydrazine metabolites is described. The method involves organic solvent extraction of PZA and RIF, followed by derivatization of INH, monoacetylhydrazine (mHYD) and hydrazine (HYD) with salicylaldehyde and extraction with diethyl ether. Acetylisoniazid (acINH) and diacetylhydrazine (dHYD) were hydrolyzed to INH and mHYD, respectively, and processed as above. Using a gradient solvent programmer, PZA and RIF were analyzed on a C₈ (5 μm) column at 248 nm, while INH and metabolites were analyzed on a C₁₈ (5 μm) ODS2 column at 280 nm.     

Structure and function of a mating-type gene from the homothallic species Neurospora africana

The homothallic Neurospora species, N. africana, contains sequences that hybridize to the A but not to a mating-type sequences of the heterothallic species N. crassa. In this study, the N. africana mating-type gene, mt A-1, was cloned, sequenced and its function analyzed in N. crassa. Although N. africana does not mate in a heterothallic manner, its mt A-1 gene functions as a mating activator in N. crassa. In addition, the N. africana mt A-1 gene confers mating type-associated vegetative incompatibility in N. crassa. DNA sequence analysis shows that the N. africana mt A-1 open reading frame (ORF) is 93% identical to that of N. crassa mt A-1. The mt A-1 ORF of N. africana contains no stop codons and was detected as a cDNA which is processed in a similar manner to mt A-1 of N. crassa. By DNA blot and orthogonal field agarose gel electrophoretic analysis, it is shown that the composition and location of the mating-type locus and the organization of the mating-type chromosome of N. africana are similar to that of N. crassa.     

Enhanced Staining of Bacterial Flagella Using Aged Mordant in the Silver Stain

Intensity of bacterial flagella staining using a modified silver stain was increased by aging the mordant for one week at room temperature. The use of aged mordant increased the apparent diameters of stained flagella and resulted in a darker stain. The mordant remained stable for at least four months at room temperature. The staining protocol presented allows application to liquid or solid cultures.