Taste sorting and naming: can taste concepts be misrepresented by traditional psychophysical labelling systems?

Japanese and American subjects were required to sort filterpapers, soaked in taste stimuli, into categories that had conceptuallythe same taste. Both Japanese and Americans sorted in the samemanner, indicating similar conceptualization. Taste names weregiven to the taste categories obtained by using the traditional‘four basic taste’ naming system, common in tastepsychophysics. This method was seen to underestimate the numberof categories actually present. This suggests a re-assessmentof current psychophysical taste-naming techniques.     

Estrogen can regulate the cell cycle in the early G1 phase of yeast by increasing the amount of adenylate cyclase mRNA

The effects of beta-estradiol (estrogen; a minor component of yeast cells) on S. cerevisiae cells in the G0 and G1 phases were examined. Results showed that estrogen stimulated the recovery of growth from G0 arrest induced by nutrient limitation or ts mutation of cdc35 (adenylate cyclase) in the early G1 phase, and inhibited entry into the resting G0 phase by increasing the intracellular cAMP level. However, estrogen had no effect on late G1 arrest induced by the alpha factor or ts mutation of cdc36. Estrogen was found to lead to higher steady-state levels of adenylate cyclase mRNA but not to affect the expression of the RAS1 and RAS2 genes, although these can also alter the intracellular cAMP level. These results suggest that estrogen influences the cell cycle of yeast in the early G1 phase by controlling the level of cAMP through the increase of adenylate cyclase mRNA.     

Dose-dependent regulation of macrophage differentiation by mos mRNA in a human monocytic cell line.

The proto-oncogene c-mos was expressed during differentiation of the human monocytic cell line U937 into macrophages. To investigate a possible role of the mos oncogene, we introduced the v-mos gene under an inducible promoter, MT-I, into U937 cells. The v-mos transformed cells expressed mos mRNA at an amount proportional to the concentration of Zn2+ ions. The induction of the v-mos gene caused growth inhibition and macrophage differentiation in these cells. The differentiation of v-mos transformed monocytes into macrophages required continuous expression of the v-mos gene. The extent of expression of phenotypic characteristics of macrophages, such as phagocytosis, cell surface antigens and typical morphology, depends on the amount of mos mRNA present. We were therefore able to demonstrate that the expression of only one oncogene, mos, determines monocyte differentiation into macrophages.     

The asymptotic transectional/circumferential homogeneity of the solutions of reaction-diffusion systems in/on cylinder-like domains

It is often reported that an animal with spotty coat markings on its body has a tail with stripe-shaped pattern. In other various biological and chemical phenomena in/on cylinder-like domains, longitudinally periodic band patterns are observed much more often than the other non-uniform patterns. This paper mathematically explains these observations by proving that, in/on a long and narrow cylinder-like domain, any solution of reaction-diffusion system asymptotically loses its spatial dependence in the transectional/circumferential direction.     

Neuronal activity preceding directional and nondirectional cues in the premotor cortex of rhesus monkeys

Pre-cue activity, the neuronal modulation that precedes a predictable stimulus, was studied in the premotor cortex of three rhesus monkeys. In one condition, a directional cue dictated the timing and target of a forelimb movement. In another condition, a nondirectional cue provided identical timing information but did not indicate the target. Of 501 task-related neurons recorded in premotor cortex, 168 showed pre-cue activity. The onset time of pre-cue activity varied markedly from trial to trial and cell to cell, ranging from trial initiation to 4.8 sec later. No pre-cue activity reflected the direction of limb movement; thus, the data argue against the hypothesis that pre-cue activity reflects preparation for specific limb movements. A small number of cells showed greater pre-cue activity before directional than before nondirectional cues, and this difference may reflect anticipation of the cue's directional information. However, the vast majority (84%) of neurons lacked such differences. We therefore hypothesize that most pre-cue activity reflects or contributes to a facet of behavior common to the two conditions: anticipation of the time and/or nature of events.     

Distinction of G0 cells from senescent cells in cultures of non-cycling human fetal lung fibroblasts by anti-MAP-1 monoclonal antibody staining

On staining with a monoclonal antibody raised against microtubule-associated protein-1 (MAP-1), dot-like structures were seen in the nuclei of interphase cells, but not in those of non-cycling G0-arrested cells. Dots were also not seen in the nuclei of non-cycling senescent human cells (IMR-90). A SV40-DNA-transformed subline of IMR-90 with a limited growth potential showed progressive decrease of cells with nuclei containing dots in the final stage of their lifespan. The dots appeared in G0-arrested IMR-90 cells when these cells were incubated in medium of high osmotic pressure for 3 min. In contrast, no dots appeared in senescent cells or X-ray-irradiated young cells when they were incubated in medium of high osmotic pressure. Thus irreversibly non-cycling cells could be distinguished from G0-phase cells on the level of whole cultures. The results suggest that senescent cells lose their division potential by entering an irreversible cell-cycle stage differing from G0.     

Chemotaxonomy of Gibberella zeae with special reference to production of trichothecenes and zearalenone.

By adopting a single-spore isolation technique, 113 isolates of Gibberella zeae, the perfect stage of Fusarium graminearum, were isolated from rice stubbles in barley and wheat fields and tested for production of trichothecenes and zearalenone on rice grains. Of the isolates, 93% produced the trichothecenes, and they could be subdivided into two chemotaxonomic groups: nivalenol and fusarenon-X producers and deoxynivalenol and 3-acetyldeoxynivalenol producers. No cross production of these two types of trichothecenes was observed in these isolates. Zearalenone was detected in 68% of the isolates, but no clear relationship could be observed regarding its position with respect to the two chemotaxonomic groups.     

Detection of chemiluminescence in lipid peroxidation of biological systems and its application to HPLC

A combined system of chemiluminescence detection and high performance liquid chromatography (CL–HPLC) was developed to determine primary peroxidation products in biological tissues, such as phosphatidylcholine hydroperoxide (PCOOH). The CL–HPLC assay consists of separation of lipid classes with HPLC and detection of hydroperoxide-specific chemiluminescence. Hydroperoxides react with heme compounds to produce oxidants as suggested by our early studies on tissue low-level chemiluminescence in which singlet molecular oxygen is generated as one of the excited species in several biological systems involving free radical events. In the CL–HPLC method, a cytochrome c–luminol mixture was used as a hydroperoxide-specific luminescent reagent, and the quantification of hydroperoxide was performed by detecting chemiluminescence due to the luminol oxidation caused by the oxidant produced during the lipid hydroperoxides with heme. The detection limit of PCOOH was 10 pmole hydroperoxide–O₂. PCOOH in normal human blood was found to be 10–500 pmol/ml plasma and significantly higher levels of PCOOH were observed in some hospitalized patients.     

Set-related activity in the premotor cortex of rhesus monkeys: effect of triggering cues and relatively long delay intervals

"Set-related activity" has been defined as a significant alteration in neuronal discharge rate during an "instructed delay period," a period when a previously instructed movement is being withheld. It has been argued that set-related activity in the primate premotor cortex, or at least a significant proportion of it, reflects motor preparation. In most previous investigations, however, in which visual stimuli have triggered the movement and simultaneously indicated its target, set-related activity might reflect either the anticipation of or attention to the trigger stimulus. The present report shows that set-related activity is robust and can be directionally selective when trigger stimuli do not indicate the target and when a trigger stimulus is absent. Another feature of previous studies has been the relatively brief intervals between the instruction and trigger stimuli (typically 3 sec or less). In the present study, we were able to observe the activity of a small number of cells during longer delay periods. Set-related activity persists, although it becomes less consistent, for as much as 7.5 sec after an instruction stimulus. These results support the hypothesis that set-related activity reflects the preparation for specific limb movements.     

Hypervariability of intronic simple (gt)n(ga)m repeats in HLA-DRB genes

We have investigated the extent of DNA variability in intronic simple (gt)_n(ga)_m repeat sequences and correlated this to sequence polymorphisms in the flanking exon 2 of HLA-DRB genes. The polymerase chain reaction (PCR) was used to amplify a DNA fragment containing exon 2 and the repeat region of intron 2. The PCR products were separated on sequencing gels in order to demonstrate length hypervariability of the (gt)_n(ga)_m repeats. In a parallel experiment, the PCR products were cloned and sequenced (each exon 2 plus adjacent simple repeats) to characterize the simple repeats in relation to the HLA-DRB sequences. In a panel of 25 DRB1, DRB4, and DRB5 alleles new sequences were not detected. Restriction fragment length polymorphism (RFLP) subtyping of serologically defined haplotypes corresponds to translated DNA sequences in 85% of the cases, the exceptions involving unusual DR/DQ combinations. Many identical DRB1 alleles can be distinguished on the basis of their adjacent simple repeats. We found group-specific organization of the repeats: the DRw52 supergroup repeats differ from those of DRB1*0101, DRB4*0101, and DRB5*0101 alleles and from those of pseudogenes. Finally, we amplified baboon DNA and found a DRB allele with extensive similarity to DRB1 sequences of the DRw52 supergroup. The simple repeat of the baboon gene, however, resembles that of human pseudogenes. In addition to further subtyping, the parallel study of polymorphic protein and hypervariable DNA alleles may allow conclusions to be drawn on the relationships between the DRB genes and perhaps also on the theory of trans-species evolution.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number M 34258.