Soil N mineralization and nitrification in relation to nitrogen solution chemistry in a small forested watershed

Spatial variations in soil processes regulating mineral N losses to streams were studied in a small watershed near Toronto, Ontario. Annual net N mineralization in the 0–8 cm soil was measured in adjacent upland and riparian forest stands using in situ soil incubations from April 1985 to 1987. Mean annual rates of soil N mineralization and nitrification were higher in a maple soil (93.8 and 87.0 kg.ha^–1) than in a pine soil (23.3 and 8.2 kg.ha^–1 ). Very low mean rates of mineralization (3.3 kg.ha^–1) and nitrification (3.4 kg.ha^–1) were found in a riparian hemlock stand. Average NO₃-N concentrations in soil solutions were 0.3–1.0 mg.L^–1 in the maple stand and >0.06mg.L^–1 in the pine stand. Concentrations of NO₃–N in shallow ground water and stream water were 3–4× greater in a maple subwatershed than in a pine subwatershed. Rapid N uptake by vegetation was an important mechanism reducing solution losses of NO₃–N in the maple stand. Low rates of nitrification were mainly responsible for negligible NO₃–N solution losses in the pine stand.     

Bradyrhizobium japonicum Survival in and Soybean Inoculation with Fluid Gels

The utilization of gels, which are used for fluid drilling of seeds, as carriers of Bradyrhizobium japonicum for soybean (Glycine max (L.) Merr.) inoculation was studied. Gels of various chemical composition (magnesium silicate, potassium acrylate-acrylamide, grafted starch, and hydroxyethyl cellulose) were used, although the hydroxyethyl cellulose gels were more extensively investigated. Gel inocula were prepared by mixing gel powder with liquid cultures of B. japonicum (2% [wt/vol]). The population of B. japonicum USDA 110 did not change in each gel type during 8 days of incubation at 28°C. These fluid gels were prepared with late-exponential-growth-phase cells that were washed and suspended in physiological saline. Mid-exponential-growth-phase B. japonicum USDA 110, 123, and 138 grew in cellulose gels prepared with yeast extract-mannitol broth as well as or better than in yeast extract-mannitol broth alone for the first 10 days at 28°C. Populations in these cellulose gels after 35 days were as large as when the gels had originally been prepared, and survival occurred for at least 70 days. Soybeans grown in sand in the greenhouse had greater nodule numbers, nodule weights, and top weights with gel inoculants compared with a peat inoculant. In soil containing 10³ indigenous B. japonicum per g of soil, inoculation resulted in increased soybean nodule numbers, nodule weights, and top weights, but only nodule numbers were greater with gel than with peat inoculation. The gel-treated seeds carried 10² to 10³ more bacteria per seed (10⁷ to 10⁸) than did the peat-treated seeds.     

Relationships among Cell Size, Membrane Permeability, and Preservative Resistance in Yeast Species

The rate of uptake of propanoic acid and the cell dimensions were measured for 23 yeasts differing in their resistance to weak-acid-type preservatives. Relationships between reciprocal uptake rate, reciprocal permeability, cell volume, cell area, volume/area, and the MICs of benzoic acid and propanoic acid for the yeasts were tested by correlation analysis on pairs of parameters. The MIC of methylparaben, which is not a weak-acid-type preservative, was included. The most significant relationships found were between both reciprocal uptake rate and reciprocal permeability and the MICs of propanoic and benzoic acids Cell volume, area, and volume/area were each individually correlated with propanoic and benzoic acid MICs, but less strongly. In multiple regression analyses, inclusion of terms for volume, area, or volume/area did not markedly increase the significance. The MIC of methylparaben was unrelated to the uptake and permeability parameters, but did show a correlation with cell volume/area. Schizosaccharomyces pombe was anomalous in having very low permeability. Exclusion of these outlying data revealed particularly strong relationships (P < 0.001) between both reciprocal uptake rate and reciprocal permeability and the benzoic acid MIC. MICs for Zygosaccharomyces bailii isolates were substantially higher than for the other species, and therefore Z. baillii isolates had a large influence on the regressions. However, the relationships observed remained significant even after removal of the Z. bailii data. In showing a correlation between the rate at which propanoic acid enters yeast cells and the ability of the cells to tolerate this and other weak-acid-type preservatives, but not methylparaben, the results suggest that the resistance mechanism, in which preservative is continuously removed from the cell, is a common and major determinant of the preservative tolerance of yeast species.     

Testosterone, and winning and losing in human competition

Testosterone and cortisol were measured in six university tennis players across six matches during their varsity season. Testosterone rose just before most matches, and players with the highest prematch testosterone had the most positive improvement in mood before their matches. After matches, mean testosterone rose for winners relative to losers, especially for winners with very positive moods after their victories and who evaluated their own performance highly. Winners with rising testosterone had higher testosterone before their next match, in contrast to losers with falling testosterone, who had lower testosterone before their next match. Cortisol was not related to winning or losing, but it was related to seed (top players having low cortisol), and cortisol generally declined as the season progressed. These results are consistent with a biosocial theory of status.     

Comparison of chemical analyses of boat and helicopter-collected water samples

Helicopters can be used to collect water samples from many lakes over a wide geographic area within a relatively short time period. Here we report the results from an experiment in which sequential water samples from a lake were collected first from a nonmotorized boat and then immediately afterward from a helicopter. No significant differences were found between the means of the measurement of 20 chemical parameters for the two methods of collection. When compared to obtaining samples from a boat, collection of samples from a helicopter platform had no effect on the content of the water samples.     

Creatine kinase activity of urinary bladder and skeletal muscle from control and streptozotocin-diabetic rats

The urinary bladder depends on intracellular ATP for the support of a number of essential intracellular processes including contraction. The concentration of ATP is maintained constant primarily via the rapid transfer of a phosphate from creatine phosphate (CP) to ADP catalyzed by the enzyme creatine kinase (CK). Since muscular pathologies associated with diabetes are in part related to intracellular alterations in metabolism, we have characterized the CK activity in both skeletal muscle and urinary bladder from control and streptozotocin-diabetic rats.The following is a summary of the results: 1) Bladder tissue from control rats showed linear kinetics with a V_max = 390 nmoles/mg protein/min, and a K_m = 275 µM. 2) Urinary bladder tissue isolated from diabetic rats displayed biphasic kinetics with V_max = 65 and 324 nmoles/mg protein/min, and K_m's = 10 µM and 190 µM respectively. 3) Skeletal muscle isolated from control rats showed linear kinetics with an approximate V_max of 800 nmoles/mg protein/min and a K_m of 280 µM CP. 4) Homogenates of skeletal muscle from diabetic rats showed complex kinetics not separable into distict component forms. 5) The K_m for ADP for both skeletal muscle and bladder was approximately 10 µM.These studies demonstrate that whereas bladders isolated from both control and diabetic rats possess a low-affinity isomer(s) of CK with similar maximum enzymatic activity, there is a high affinity isomer present within the urinary bladder muscle of diabetic rats that is not present in bladder tissue isolated from control rats. Skeletal muscle isolated from both diabetic and control rats exhibited a maximal activity 2 to 3 times higher than that of the bladder.     

Analysis of rice (Oryza sativa L.) genome using pulsed-field gel electrophoresis and rare-cutting restriction endonucleases

TheOryza sativa (rice) genome is small (600 to 900 megabase pairs) when compared to that of other monocotyledonous plants. Rice was the first of the major cereals to be successfully transformed and regenerated. An RFLP map with approximately 300 markers is readily available, and the DNA content per map unit is only two to three times that ofArabidopsis thaliana. Rice is also the main staple food for the majority of peoples in the world. We developed techniques for the preparation of intact genomic DNA from Indica and Japonica subspecies of rice, used statistical methods to determine which restriction endonucleases are rare-cutting, and used pulsed-field gel electrophoresis (PFE) to separate large fragments of rice DNA. Southern hybridization to blotted rice PFE gels was used to show that the digests were complete. The long-term goal of our work is to generate an integrated genetic/physical map for the rice genome, as well as helping to establish rice as a model for map-based gene cloning and genome analysis.     

Distribution of FMRFamide-like immunoreactivity in the nervous system of the slug Limax maximus

Summary The distribution of FMRFamide-like immunoreactive neurons in the nervous system of the slug Limax maximus was studied using immunohistochemical methods. Approximately one thousand FMRFamide-like immunoreactive cell bodies were found in the central nervous system. Ranging between 15 m and 200 m in diameter, they were found in all 11 ganglia of the central nervous system. FMRFamide-like immunoreactive cell bodies were also found at peripheral locations on buccal nerve roots. FMRFamide-like immunoreactive nerve fibres were present in peripheral nerve roots and were distributed extensively throughout the neuropil and cell body regions of the central ganglia. They were also present in the connective tissue of the perineurium, forming an extensive network of varicose fibres. The large number, extensive distribution and great range in size of FMRFamide-like immunoreactive cell bodies and the wide distribution of immunoreactive fibres suggest that FMRFamide-like peptides might serve several different functions in the nervous system of the slug.     

Evolutionary conservation of the human homologue of the yeast cell cycle control gene cdc2 and assignment of Cd2 to chromosome 10

Summary The human homologue of the fission yeast Schizosaccharomyces pombe cell cycle control gene cdc2 has been assigned to chromosome 10. DNA hybridization reveals that this gene is highly conserved in vertebrates. The human CDC2 gene probe detects a simple two-allele polymorphism in Taq1-digested DNA.