Small Sample Distribution and Power of the Binomial Index of Dispersion and Log Likelihood Ratio Tests

This paper considers the exact distribution of the X² index of dispersion and -2 log (likelihood ratio) tests for the hypothesis of homogeneity of c independent samples from a common binomial population. The exact significance levels and power of these tests under ‘logit’ alternatives are compared numerically for the cases: c = 3, 4, 5 and various sample sizes. n₁ = 5,10 for i = 1,…, c.     

Stimulated nodulation of soybeans by Rhizobium japonicum mutant (B-14075) that catabolizes the conversion of tryptophan to indol-3yl-acetic acid

Nodulations of Glycine max L. seedlings by parental Rhizobium japonicum (USDA strain 26) and a tryptophan catabolic mutant (tan 4b, NRRL strain B-14075) were evaluated for effectiveness. Seedlings grown in plastic pouches were compared based on increases in root weight (wt.), nodule volume (vol.) and acetylene-reducing (AR) activity. The tan 4b mutant, which can produce extracellular indol-3yl-acetic (IAA) and indol-3yl-pyruvic (IPA) acids asymbiotically, enhanced nodulation significantly. Nodulation by strain 26 was most effective when a basal nutrient was supplemented with sucrose, CaCO₃, EDTA, nicotinic acid and glutamate. In contrast, effective nodulation by tan 4b did not require an exogenous glutamate (0.34 mM)-nicotinate (81 μM) combination. Like strain 26 inoculum supplemented with exogenous IAA (0.1 mM), taproot formation associated with unsupplemented tan 4b was inhibited by exposure to direct light.     

Fumonisin-stimulatedN-acetyldihydrosphingosine,N-acetylphytosphingosine,and phytosphingosine products ofPichia (Hansenula) ciferri,NRRL Y-1031

Pichia (Hansenula) ciferri Y-1031 grown in the presence of 25–100 mg fumonisin B₁/L for 4–5 days accumulated sphingolipids as evident in the centrifuged cells and extracellular particles (c/p fraction). The c/p fraction of fumonisin-treated (100 mg/L) cultures elicited a 15-fold increase ofN-acetyldihydrosphingosine and 31-fold increase of combinedN-acetylphytosphingosine and phytosphingosine over those from untreated cultures. During exponential growth of 1 day, fumonisin-treated cultures appeared to transfer sphingolipid bases into the medium (22 mg/L) rather than into the c/p (2 mg) fraction. Upon saponification, a residue from the c/p fraction contained 440 mg of additional, unknown polar lipids per liter that was not sphingolipid (14 mg/L).     

Assays for testing Pneumocystis carinii viability.

A series of classical vital stains and fluorescent indicator compounds were evaluated as viability assays of P. carinii. The combination of the acetoxymethyl ester of calcein with either ethidium homodimer or propidium iodide distinguished between live, dead and moribund organisms and provided high fluorescence intensity and low bleaching enabling photodocumentation at high magnifications.