Immobilized cells: behaviour of carrageenan entrapped yeast during continuous ethanol fermentation

Summary Data of cell concentration, viability and microscopic observation of cell distribution inside carrageenan immobilized yeast beads are reported. Results were obtained from a continuous packed-bed reactor performing alcoholic fermentation and the main observations made on cell activity are in agreement with the fermentation profiles inside the fermenter.     

Contribution of leaves of different ages to plant carbon balance as affected by potassium supply and water stress

The carbon balances of whole, 21-d old French bean plants (Phaseolus vulgaris L.) grown in standard nutrient solution (1K) and its modifications without (OK) or surplus (2K) potassium were calculated from the daily photosynthetic carbon inputs of individual leaves, and the daily respiratory carbon losses by individual leaves, stalks and petioles, and roots. Under the three K concentrations, maximum net photosynthetic rates (P_n) were found in the 2nd or in the 3rd trifoliate leaves, maximum respiratory rates (R_d) in the youngest, 4th trifoliate leaves; the P_n/R_d ratio decreased with leaf age. In all leaves of 2K plants, leaf dry masses and thicknesses, P_n, P_n/P_d ratios, and stomatal and intracellular conductances were lower than in OK and IK plants. Daily whole-plant net carbon gain was highest in IK plants, whereas in OK and 2K plants it was 98.0 and 81.3 % of IK, respectively. Similar values were found in the parameters of growth analysis, namely in net assimilation rates and relative growth rates. No differences were found in water potential (Ψ _w ) or water saturation deficit (W_sat) in the OK, 1K and 2K plants sufficiently supplied with water or during wilting and resaturation. The decrease in Ψ_w to −0.97 MPa was associated with a 19.9 %, 31.4 % and 23.4 % decrease in P_n of OK, 1K and 2K plants, respectively, but no effect on R_d was found. In the three variants, the short-time effect of mild water stress was fully reversible.     

EMG biofeedback of the abductor pollicis brevis in piano performance

The aim of the present study was to apply EMG biofeedback as an auxiliary to piano teaching techniques. We studied the changes in integrated electromyographic activity, using the abductor pollicis brevis functioning as an agonist during the teaching of identical selective movements of piano playing in two groups, one with EMG biofeedback and the other following traditional method of instruction. The analysis of variance revealed an increase in the peak amplitude and the relaxation rate values for the biofeedback group. These results have implications for the application of piano playing techniques and reveal EMG biofeedback as an aid in the teaching of thumb attack with the abductor pollicis brevis as agonist.We are grateful for the valuable assistance of Dr. Jaime Vila (Professor of Therapy and Behavioral Modification, Faculty of Psychology, Granada), the cooperation of students at the Juventudes Musicales Music School, Santa Fe and at the Victoria Eugenia Conservatoire, (Granada), the Statistical Analysis Centre of University of Filosofia y Letras de Granada; Professor Enrique Garcia Fernandez-Abasal (Complutense University) for the design of the interface and software.     

Substitution of transferrin by FeCl3 in the development of a low foetal calf serum concentration medium for KB-26.5 hybridoma cell line

KB-26.5, a murine hybridoma cell line producing an IgG₃ monoclonal antibody used in blood type determination, primarily adapted to grow at 5% foetal calf serum (FCS) concentration has been adapted to grow at 0.5% FCS, maintaining its ability to produce antibodies at the same level. In the final step of adaptation, the addition of insulin, transferrin, ethanolamine and selenium to the media formulation was studied, using factorial assay techniques to check the effect of the different compounds and to optimize their required level for satisfactory growth and antibody secretion. KB-26.5 cells required only 20 g/ml of transferrin to adapt to 0.5% FCS medium. Furthermore, transferrin could be substituted by FeCl₃, at a relatively low level of 2 g/ml. Maximum cell density decreased by 31.5% in spinner flask test, but the antibody titer was maintained, thus the specific productivity increased. However, inoculum size had to be increased three-fold with 0.5% FCS medium in order to assure cell growth.     

Syncytium-inducing (SI) phenotype suppression at seroconversion after intramuscular inoculation of a non-syncytium-inducing/SI phenotypically mixed human immunodeficiency virus population.

Two distinct biological phenotypes of human immunodeficiency virus (HIV) have been described: the non-syncytium-inducing (NSI) phenotype, best characterized by the inability to infect MT-2 cells, and the syncytium-inducing (SI) phenotype, with the ability to infect MT-2 cells. The earliest virus population observed following HIV transmission is generally of the NSI phenotype, even after exposure to inocula of mixed NSI/SI phenotype. In this study, the issue of intrapatient selection of virus phenotype following transmission was addressed by studying two cases of accidental transmission. A comparison of the sequences of the V1-V2 and the V3 coding regions of the envelope gene and the p17 region of the gag gene showed that the donor-recipient pairs were tightly clustered in all gene segments, but away from local and published transmission controls. The intrasample variation of the p17 sequence was greater in the recipients and smaller in the donors than that of the V3 region sequence, indicating selection of V3 at transmission. In these transmission cases, the effects of an intravenous inoculation of a small quantity of blood containing predominantly SI V3 sequences (6 of 8 clonal sequences) were compared with those of an intramuscular inoculation of a large quantity of blood containing predominantly NSI viruses (14 of 16 clonal sequences). Both SI and NSI V3 regions were demonstrated to be phenotypic expressions of genetically related viral strains. The inoculation of the predominantly SI virus population resulted in the persistence of an SI virus population in the recipient and a rapid CD4+ T-cell decline. The inoculation of the predominantly NSI population resulted in a selective amplification of SI viruses before seroconversion, followed by a suppression of SI viruses at seroconversion and a rapid decline of CD4+ T-cell numbers. These data suggest that the suppression of SI viruses can be accomplished following the development of HIV-specific immunity and that the ability to suppress SI viruses does not prevent the development of immunodeficiency.     

Patchiness and disturbance: plant community responses to porcupine diggings in the central Negev

We tested the hypothesis that diversity and productivity of herbaceous plant communities in disturbed soil are related to the physical and biological heterogeneity of the landscape Our study was earned out on vegetation responses in porcupine diggings on a rocky slope in the central Negev desert in Israel We measured aboveground bio-mass and plant density per species in 150 porcupine diggings (15 cm deep and 15 to 20 cm wide) and in equally sized adjacent control samples in the undisturbed soil matrix We calculated mean annual biomass production, plant density and species richness for 10 sample areas along the slope In addition, we divided the plants into groups according to propagule size and dispersal mode We denoted two types of landscape heterogeneity, which we called physical and biological patchiness Physical patchiness was measured as the ratio of bare rock to soil surface Biological patchiness was the area of the soil covered by shrubs with associated soil mound and under-story relative to the total soil surface We also measured disturbance density, as the long term (17 yr) average density of newly made porcupine diggings We found that 1) the physical patchiness explained 30% of the variation of biological patchiness along the slope, while 2) the patterns of disturbance intensity and biological patchiness were similar (R-=0 386) 3) Biomass, density and species richness were significantly higher in diggings than m the soil matrix 4) Plant density in the matrix, but not m the diggings, was significantly correlated with physical patchiness, 5) species richness in diggings was significantly correlated with biological patchiness, but 6) biomass production in diggings and matrix was not affected by either physical or biological patchiness of the landscape 7) Disturbance density did not affect vegetation responses in diggings and matrix 8) A shift in the plant communities in the matrix towards plants with smaller seeds was associated with increasing physical patchiness, while m diggings there was an opposite shift 9) The proportion of wind dispersers was higher in diggings than outside, while the proportion of runoff dispersers was lower, 10) the densities of runoff dispersers in diggings and matrix were positively correlated with physical and biological patchiness 11) Physical and biological patchiness formed the two major gradients of species composition, explaining 30 and 25% respectively We conclude that the network of physical and biological patchiness and soil disturbance are important in the redistribution of resources and seeds, which control plant biomass, density, species richness and diversity The bare rock surface is the main source for runoff flow with associated soil, organic matter and nutrients The understory vegetation of shrubs provides seeds for creating and maintaining diversity The soil matrix absorbs runoff flow, and disturbances absorb runoff and trap seeds Thus, differences in landscape heterogeneity and their effects on resource and seed movement interact in controlling plant community productivity and diversity in the landscape