An empirical model for describing the effects of nitrogen sources on nisin production

AIMS: A study on the effects of tryptone and yeast extract on nisin production by Lactococcus lactis was carried out using a second order rotatable factorial design. METHODS AND RESULTS: The results show that both ingredients increased nisin production, although a small decrease in nisin levels was noted at high tryptone concentrations. In view of the low vitamin content of tryptone, the amino acids present in both tryptone and yeast extract may be responsible for these observations. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The observed response suggests that maintaining tryptone concentrations in the centre of the domain and increasing the concentration of yeast extract would be ideal conditions for nisin production. However, when the economic aspects are considered, it appears that low concentrations of yeast extract and reasonably high concentrations of tryptone are optimal.     

Inhibitory CD161 receptor identified in glioma-infiltrating T cells by single-cell analysis

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Identification of neural circuits by imaging coherent electrical activity with FRET-based dyes.

We show that neurons that underlie rhythmic patterns of electrical output may be identified by optical imaging and frequency-domain analysis. Our contrast agent is a two-component dye system in which changes in membrane potential modulate the relative emission between a pair of fluorophores. We demonstrate our methods with the circuit responsible for fictive swimming in the isolated leech nerve cord. The output of a motor neuron provides a reference signal for the phase-sensitive detection of changes in fluorescence from individual neurons in a ganglion. We identify known and possibly novel neurons that participate in the swim rhythm and determine their phases within a cycle. A variant of this approach is used to identify the postsynaptic followers of intracellularly stimulated neurons.     

The interphase microtubule aster is a determinant of asymmetric division orientation in Drosophila neuroblasts

The mechanisms that maintain the orientation of cortical polarity and asymmetric division unchanged in consecutive mitoses in Drosophila melanogaster neuroblasts (NBs) are unknown. By studying the effect of transient microtubule depolymerization and centrosome mutant conditions, we have found that such orientation memory requires both the centrosome-organized interphase aster and centrosome-independent functions. We have also found that the span of such memory is limited to the last mitosis. Furthermore, the orientation of the NB axis of polarity can be reset to any angle with respect to the surrounding tissue and is, therefore, cell autonomous.     

Sex pheromones in maleMelittobia parasitic wasps: Female response to conspecific and congeneric males of 3 species

Presented a choice between conspecific males and 2 congeneric males, virgin females ofMelittobia australica andM. digitata chose conspecific males disproportionately more often, whereasM. femorata females distributed themselves evenly among the choices. Empty tubes, provided as the fourth choice in the test apparatus, were entered much less often than tubes containing live males. Females of all species chose “wrong” males about equally frequently. These observations suggest that even non-conspecific males possess some degree of attractiveness to virgin females. Chemicals in the sex pheromone of the males are presumed to be the source of the males' attractancy. The incomplete species specificity is interpreted in light of the life history of this genus, and it is suggested that specific recognition cues operate primarily after the sexes come together. Supported by a grant from Kagoshima Prefecture in Japan under the exchange program of faculty members between Kagoshima University and the University of Georgia.     

Complementarity between ferritin H mRNA and 28 S ribosomal RNA

We have found an interesting complementarity in sequences of human ferritin H mRNA and 28 S ribosomal RNA. Immediately upstream of the initiating AUG in the ferritin mRNA is a stretch of 67 nucleotides which contains sequences complementary to several regions in 28 S RNA. One such region can form 55 base pairings with the 5' noncoding region of the ferritin H mRNA. Most of the complementarity is due to repeats of CCG in the ferritin mRNA and GGC in the ribosomal RNA. The regions of complementarity in the 28 S RNA appear to be expansion sequences that have arisen in the evolution of eukaryotic ribosomal RNA. We suggest that interaction of ferritin mRNA and 28 S RNA may function to regulate the stability and/or translatability of ferritin mRNA.     

Dermatophytosis of pigs by Trichophyton mentagrophytes

We describe the isolation of Trichophyton mentagrophytes in two family-operated farms where the animals were suffering skin ailments characterized by a swelling and a reddening of the back and flanks.This condition affected 2 and 5% respectively of the animals on the farms, the younger ones being more frequently affected.