Suppression of phaseolin and lectin in seeds of common bean, Phaseolus vulgaris L.: increased accumulation of 54 kDa polypeptides is not associated with higher seed methionine concentrations

Suppression of phaseolin and lectin accumulation in common bean resulted in higher concentrations of bean seed polypeptides with apparent molecular weights of 54 kDa and from 70 to 84 kDa on SDS-polyacrylamide gel electrophoresis. Polypeptides of 54 and 56 kDa segregated as products of different alleles. Genes for the 54/56 kDa bands and phaseolin were estimated to be 26.2±3.7 map units apart. The 54 kDa band phenotype manifested by SDS-PAGE consisted of from one to three polypeptides of 54 kDa MW on 2D gels, and the 56 kDa phenotype consisted of one polypeptide of 56 kDa plus two minor polypeptides of 54-54.5 kDa molecular weight. The pK_I of these polypeptides was approximately 5.25. The methionine content of the 54 kDa polypeptides of the cultivar Great Northern Star was 1.6±0.1 g/100 g protein, which was not statistically different from the value (1.5±0.1%) obtained for phaseolin isolated by the same procedure. F₂ seeds deficient for phaseolin and lectin contained as much total N per g as wild-type seeds and were not shrunken, but contained 50% more free amino acids. F₂ seeds from two of the three populations contained from 8 to 13% less methionine per mg total N.     

Size structure of the metazoan community in a Piedmont stream

We characterized the size structure of virtually the entire metazoan community in a fourth order, sandybottomed Piedmont stream during late summer. Our study, the first to sample across all habitat types and sizes of metazoans in an aquatic ecosystem, indicates that at the community level, stream size spectra may be bimodal for the benthos or trimodal when fish are included. Animals spanning 10 orders of magnitude in dry mass (from gastrotrichs to fish) were quantitatively collected from nine habitat types. The bimodal benthic size spectrum was characterized by a meiofaunal component (mostly oligochaetes and micro-crustacea) and a macrobenthic component (mostly the introduced asiatic clam, Corbicula fluminea). Insects contributed little to overall standing crop. Size-specific contribution to whole-community metabolism was assessed using allometric equations for respiration, and we found a distinctly bimodal distribution across the entire metazoan size range, with peaks in the meiofaunal and benthic macrofaunal size ranges. Our bimodal benthic size spectrum is similar to that observed for marine benthos but not to other freshwater benthic systems, possibly because the entire range of habitat types and/or animal sizes were not sampled in the latter. Numerous factors may influence size spectra in stream ecosystems, including local geomorphic (habitat) conditions, water level fluctuations, species introductions, and predation processes.     

Wave-separation in complex systems. Application to brain-signals

A departure from single-system dynamics, that may arise in characterizing self-organized dynamics of complex systems, is dealt with by using the Karhunen-Loève expansion of the trajectory matrix to decompose an experimental signal in a sum of spectral features. For an electroencephalographic -signal, a separation of waves and extraction of additive sub-signals are achieved, each sub-signal covering a well-bounded and physiologically meaningful frequency range. From the subsignals, an attractor that vanishes on phase-randomizing the data is characterized, under conditions where none was found for the recorded signal.     

Fractionation of bovine spermatozoa for sex selection: A rapid immunomagnetic technique to remove spermatozoa that contain the H-Y antigen

A study was conducted to rapidly fractionate bovine spermatozoa on the basis of cell-surface H-Y antigen (i.e., Y chromosome-bearing spermatozoa). A novel, rapid immunomagnetic method was developed for removal of spermatozoa that bound to anti-H-Y IgG. Fluorescent labeling and flow cytometry were used to measure the efficiency with which spermatozoa binding to anti-H-Y were removed by the immunomagnetic technique. Washed bovine spermatozoa (n=7 bulls) were treated with a mouse monoclonal IgG antibody to H-Y antigen (MoAb 12/49). Fluorescent labeled goat antibody against mouse IgG was added to label those spermatozoa with cell-surface H-Y antigens. Supermagnetized polymer beads coated with an anti-antibody to the MoAb 12/49 were then added to the spermatozoa. After 20 min of incubation, spermatozoa were exposed for 2 min to a magnet, causing the magnetized particles to adhere to the sides of the tube. Nonmagnetized spermatozoa in the supernatent were aspirated and analyzed for fluorescent label by flow cytometry. Approximately 50% of spermatozoa not subjected to immunomagnetic separation were fluorescent labeled, and about one-half of the spermatozoa were observed microscopically to be bound to the magnetized polymer beads prior to magnetic separation (P<0.05). Following magnetic separation, only 1.2% (P<0.05) of the spermatozoa in the magnetic supernatent were fluorescent labeled. Assuming that only Y chromosome-bearing spermatozoa have cell-surface H-Y antigens, the present immunomagnetic fractionation removed almost all of the Y chromosome-bearing spermatozoa, leaving a population that was greater than 98% X chromosome-bearing spermatozoa.     

Estimating transpiration from 6-year-old Eucalyptus grandis trees: development of a canopy conductance model and comparison with independent sap flux measurements

Daily patterns of stomatal conductance (g_s), xylem pressure potential (P) and canopy microclimatic variables were recorded on 11 sample days as part of a one-year study of the water use of Eucalyptus grandis Hill ex Maiden in the eastern Transvaal, South Africa. Measured g_s was found to be largely controlled by quantum flux density (Q) and ambient vapour pressure deficit (D). Canopy conductance (g_c) was determined for hourly intervals using g_s measurements and leaf areas in four different canopy levels. A simple model was constructed to allow the prediction of g_c and transpiration from Q, D and season of year. The model was used to estimate transpiration rates from 10 trees in a later study of similarly-aged E. grandis trees, in which sap flow in each tree was measured using the heat pulse velocity (HPV) technique. Five of the trees were monitored on a summer day and five on a winter day. Correspondence between HPV sap flow and modelled transpiration was good for the summertime comparisons, but measured winter-time sap flow rates were underestimated by the model, especially under conditions of high sap flow. The discrepancy is believed to result from having insufficient data from the conductance study to describe the response of g_s to relatively high D in winter. Marked variation in transpiration per unit leaf area indicates that a relatively large number of trees must be sampled for the HPV technique to be used to obtain a mean rate for an entire stand in winter.     

The interaction of the vanadyl(IV) cation with phytic acid

The interactions of VO²⁺ with phytate to form both soluble and insoluble complexes, have been studied by electronic absorption spectroscopy. A soluble 1∶1 VO²⁺: phytate complex is formed at pH <1. At higher pH-values insoluble complexes are produced. Two different solid complexes, obtained respectively at pH=2 and 4, were isolated and characterized. The maximal bonding ratio of VO²⁺: phytate was found to be 4, on the basis of a pH binding profile.     

经颅多普勒超声对80例偏头痛病人的检测分析

经颅多普勒超声波对８０例偏头痛病人与１１０例正常对照组血流速度进行检测．结果发现病例组血流速度异常为８７．５％。根据血流速度改变,本组分为血流速度增快型与血流速度减慢型,这有助于偏头痛的临床诊断。     

新生儿接种小剂量乙肝疫苗后3-5年随访观察

本文对９３８例初生婴儿接种小剂量（１０ｕｇ×３）乙肝疫苗后３－５年的预防效果进行了随访观察,并以２５３例初生儿未接种疫苗者作为对照,结果表明,接种组３－５年后抗－ＨＢｓ阳性率显著高于对照组,ＨＢｓＡｇ阳性率则较对照组显著为低。感染保护率８６．７％。结果还表明,接种乙肝疫苗３年后加强１次,比不加强者Ｐ／Ｎ均值显著增高。文章认为初生儿接种小剂量乙肝疫苗有长期免疫效果;接种后３年加强接种１次,可保持较高免疫力。     

The Value of a hoard: not just energy

We present a stochastic dynamic programming model of the contributionof stored food to winter survival. Using the acorn woodpecker(Melanerpes formtcivorus) as a model organism, we demonstratethat a hoard of small energetic value can impart considerableimprovement in the probability of surviving the winter and soimprove fitness. With this model we hope to resolve Koenig andMumme's paradox, that acorn woodpeckers expend much time andeffort to create and maintain hoards of acorns which provideno more that 16% of their energetic needs over the period inwhich they are used. We further demonstrate that the contributionof hoarded acorns to survival depends on the variability inforaging outcome, independently of the energetic value of thehoard in absolute terms. We point out that the results applyin principle to all hoarding animals and suggest a number offurther elaborations of the model.     

Transpiration by an emergent macrophyte: source of water and implications for nutrient supply

The contribution of sediment interstitial water and the water column to the transpiration stream of Myriophyllum aquaticum (Vellozo) Verdcourt was determined to estimate the significance of mass flow in supply of sediment nutrients for plant growth. Sediment interstitial water accounted for about 2% of the water transpired over a 37 day period. Because of the small volume of water that originated in the sediment we concluded that mass flow did not significantly enhance nutrient supply to the roots of M. aquaticum. Relative growth rate (RGR) of adventitious, water roots was greater than whole plant RGR, and RGR of sediment roots was not significantly different from zero, indicating a shift in the biomass allocation after emergence of the apical meristem into the air. Water use, measured by the transpiration coefficient, averaged 260 ml H₂O mg DW^-1, which is similar to C-4 terrestrial plants. M. aquaticum has leaf characteristics commonly associated with xerophytic habitats. These characteristics may be necessary if a high transpiration rate and a mechanical requirement for high cell turgor pressure, required by a reliance upon hydrostatic pressure for support of the aerial stems, are mutually exclusive because of morphological constraints on hydraulic conductivity.