Peculiarities of the Heart Rate Control during Competitive Entrance Examinations

A study was made of the dynamics of psychophysiological parameters and the activities of the systems regulating the heart rate in prospective post-secondary students taking competitive entrance examinations. The responses of the regulatory systems to examination stress were of two types, sympathetic and parasympathetic, depending on the initial state of the autonomic nervous system and the psychophysiological personality traits.     

Phytotoxic lignans of Leucophyllum frutescens.

Bioassay-guided fractionation of the hexane:ethyl acetate (1:1) extract of the leaves of Leucophyllum frutescens (Berl.) I.M.Johnst (Scrophulariaceae) led to the isolation of its phytotoxic constituents diayangambin (1), epiyangambin (2), diasesartemin (3) and epiashantin (4). Phytotoxicity was demonstrated as inhibition of seed germination of Agrostis stolonifera cv. penncross (Poaceae) and inhibition of development of Lactuca sativa L. (Asteraceae) seedlings in a microassay using 24-well plates. Compound 1 was the most phytotoxic to L. sativa, showing strong inhibitory activity at 110 microM. Compound 1 was more active than 2 and 3 in inhibiting the growth of A. stolonifera with I(50) values of 160, 670 and 930 microM, respectively. At a concentration of 500 microM, these compounds inhibited all phases of onion root cell division. This is the first demonstration of antimitotic activity of these furofuran lignans, and the first report of their isolation from this species.     

On the role of phylogeny in determining activity patterns of rodents

Evolutionary plasticity is limited, to a certain extent, by phylogenetic constraints. We asked whether the diel activity patterns of animals reflect their phylogenies by analyzing daily activity patterns in the order Rodentia. We carried out a literature survey of activity patterns of 700 species, placing each in an activity time category: diurnal, nocturnal, or active at both periods (a-rhythmic). The proportion of rodents active at these categories in the entire order, was compared to the activity patterns of species of different families for which we had data for over ten species each: Dipodidae, Echimyidae, Geomyidae, Heteromyidae, Muridae, and Sciuridae. Activity times of rodents from different habitat types were also compared to the ordinal activity time pattern. We also calculated the probability that two random species (from a particular subgroup: family, habitat, etc.) will be active in the same period of the day and compared it to this probability with species drawn from the entire order. Activity patterns at the family level were significantly different from the ordinal pattern, emphasizing the strong relationship between intra-family taxonomic affiliation and daily activity patterns. Large families (Muridae and Sciuridae) analyzed by subfamilies and tribes showed a similar but stronger pattern than that of the family level. Thus it is clear that phylogeny constrains the evolution of activity patterns in rodents, and may limit their ability to use the time niche axis for ecological separation. Rodents living in cold habitats differed significantly from the ordinal pattern, showing more diurnal and a-rhythmic activity patterns, possibly due to physiological constraints. Ground-dwelling rodents differed significantly, showing a high tendency towards a-rhythmic activity, perhaps reflecting their specialized habitat. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Oncogene-regulated release of extracellular vesicles

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Green cocoons in silkworm Bombyx mori resulting from the quercetin 5-O-glucosyltransferase of UGT86, is an evolved response to dietary toxins

The glycosylation of UDP-glucosyltransferases (UGTs) is of great importance in the control and elimination of both endogenous and exogenous toxins. Bm-UGT10286 (UGT86) is the sole provider of UGT activity against the 5-O position of quercetin and directly influences the formation of green pigment in the Bombyx cocoon. To evaluate whether cocoon coloration evolved for mimetic purposes, we concentrated on the expression pattern of Ugt86 and the activities of the enzyme substrates. The expression of Ugt86 was not only detected in the cocoon absorbing and accumulating tissues such as the digestive tube and silk glands, but also in quantity in the detoxification tissues of the malpighian tubes and fat body, as well as in the gonads. As in the green cocoon strains, Ugt86 was clearly expressed in the yellow and white cocoon strains. In vitro, the fusion protein of UGT86 showed quercetin metabolic activity. Nevertheless, Ugt86 expression of 5th instar larvae was not up-regulated in the silk gland by exogenous quercetin. However, it was significantly up-regulated in the digestive tube and gonads (P < 0.05). A similar result was observed in experiments where larvae were exposed to rutin, an insect resistance inducer and growth inhibitor typically found in plants, and to 20-hydroxylecdysone (20E), an insect endocrine and plant source hormone. On the contrary, up-regulated Ugt86 expression was almost nil in larvae exposed to juvenile hormone III (P > 0.05). The results of HPLC revealed that a new substance was formed by mixing 20E with the recombinant UGT86 protein in vitro, indicating that the effect of Ugt86 on 20E was similar to that on exogenous quercetin derived from plant food, and that the effect probably initiated the detoxification reaction against rutin. The conclusion is that the reaction of Ugt86 on the silkworm cocoon pigment quercetin is not the result of active mimetic ecogenesis, but derives from the detoxification of UGTs.     

Release of pertussis toxin and its interaction with outer-membrane antigens

The absence of subunit S3 in cell-associated pertussis toxin (PT) from a mutant of Bordetella pertussis which failed to produce cell-free toxin suggested that this subunit was involved in the release of PT into the culture medium. The addition of methylated beta-cyclodextrin (MCD) to the culture medium caused a small but consistent increase in the release of lipopolysaccharide (LPS) by four wild-type strains of B. pertussis. Since previous studies have shown that MCD also enhances the levels of PT in culture supernates, it seemed probable that the increased shedding of outer-membranes vesicles (OMV) may explain the increased levels of both cell-free PT and LPS. Release of PT was inhibited in media buffered with HEPES but was unaffected in Tris/HC1 buffer. This suggested that in addition to shedding of the outer membrane, increased permeability and greater destabilization of the outer membrane, as caused by Tris/HC1 buffer, may be important in the release of PT. Our data do not support the idea that PT is packaged into OMV because only an insignificant proportion (0.01%) of the total cell-free PT was associated with LPS. The association of PT with small micelles derived from outer-membrane amphiphiles may be more important since the LPS content of PT purified from culture supernates (containing no large OMV) was nearly 18% by weight.