The analysis of the joint effect of substances on reversion systems and the assessment of antimutagenicity.

The statistical methods for the analysis of mutagenicity and carcinogenicity underwent considerable theoretical-practical development following the need for assessing the mutagenic and carcinogenic potential of substances. Antimutagenicity is investigated through the analysis of respondents in dose-response assays, when two different molecules are administered separately and as a mixture to a respondent system. When the number of respondent units is high, and doses are orthogonal, it is possible to apply simple models such as analysis of variance. This is not always possible or common, and alternative approaches have been developed, based on multiple regression and on tables of proportions. In this work, some of the most frequently used methods for the assessment of joint responses are reviewed, particularly those based on multiple regression, such as the method of Shaeffer et al. and the method of Hass et al. In order to illustrate these methods, joint responses of perylene and cyclopentapyrene, of N-acetylcysteine and dinitropyrene, and of N-acetylcysteine and extracts from diesel exhausts were analyzed. An antagonistic effect of perylene on the action of CPP was detected by the algorithm of Shaeffer et al. The effect is not multiplicative, i.e., it is not proportional to the product of doses. The antimutagenic effect of N-acetylcysteine on dinitropyrene is multiplicative, as detected by the method of Hass et al. The latter reveals that the inhibition by N-acetylcysteine on the mutagenic effect of extracts from diesel exhausts is also multiplicative.     

Modeling the Biogeography of Fossil Baboons

We use a model of modern baboon socio-ecology to explore the behavioral ecology and biogeography of the extinct Plio-Pleistocene baboons (genera Parapapio, Gorgopithecus, Dinopithecus, and Papio). The model is based on the way climate affects the baboons’ time budgets, and focuses on intersite variability in behavior rather than on species-typical patterns of behavior, as most previous approaches have done. We use climate estimates for individual fossil sites based on matching modern habitats using faunal profiles and estimates of individual species’ body masses given in the literature. The model allows us to examine the minimum and maximum sizes of groups that individual species would have been able to support at particular localities, and hence the biogeography of a species on a continental scale. In doing so, the model allows us to examine which variables are most responsible for limiting a species’ ecological and biogeographic flexibility, and through this to explore a species’ capacity for coping with climate change. Feeding time is identified as the main constraint. In general, large-bodied species would have had more difficulty surviving in as wide a range of habitats as smaller-bodied species, and this may explain the limited geographical distribution of large-bodied baboons such as Gorgopithecus and Dinopithecus.     

Internal Rhythmic Pattern of ECG Signal and the Efficiency of Adaptation to Cyclic Muscular Work

Spectral, coherent, and phase analysis within the low-frequency range of ECG records of athletic runners revealed that oscillations of ECG intervals (PQ-, RT-, P–T-, TP, and PP-intervals) were observed during orthostasis. These data were compared with the results of athletic exercise tests performed after the ECG examination. It was shown that the most effective type of adaptive reaction in these tests corresponds to a phase advance of the PQ-interval oscillations relative to the RT-interval oscillations. In the low-frequency range, the phases of the PQ-, RT-, and (P–T)-interval oscillations were ahead of the TP-interval oscillations, whereas the spectral density of the TP interval oscillations was significantly higher than the spectral density of the oscillations of the PC-, RT-, and (P–T)-intervals measured at the same frequency. The least effective type of adaptive reaction was shown to correlate with the phase advance of the TP-interval oscillations relative to the PQ-, RT-, and (P–T)-interval oscillations within the low-frequency range as well as with the lack of low-frequency modulation of the autospectra of the cardiac intervals of interest.     

Insulin-Like Peptides of the Cerebropleural Ganglion of the Mollusc Anodonta cygnea: Isolation, Purification, and Radioligand Analysis

Cerebropleural ganglia from 4000 individuals of the mollusc Anodonta cygnea were submitted to procedures developed for isolation of vertebrate pancreatic insulins: homogenization and extraction, stage-like isoelectrical sedimentation, and ion-exchange chromatography. As a result of purification of the obtained preparation, using high-effective liquid chromatography, there were identified 7 protein peaks differing by time of retention on the reverse-phase sorbent in acetonitryl gradient and designated as insulin-related peptides (IRP), IRP1-IRP7. The material was characterized by the peptide ability to inhibit specific binding of ¹²⁵I-insulin and of insulin-related factor-1 (¹²⁵I-IGF-1) by plasma membranes of the rat liver and brain. The IC₅₀ value of peptide concentration (nM) able to replace 50% of the labeled hormone bound with the receptor amounted in the insulin radioreceptor system for IRP1 to 330, for IRP3 to 130, for IRP4 to 17, for IRP5 to130, for IRP6 to 420 nM. Peptide IRP7 at a maximal concentration (10⁴ ng/ml) replaced less than 50% of labeled hormone, whereas in IRP2 no inhibitory ability was detected under these experimental conditions. The IC₅₀ value in the case of ¹²⁵I-IGF-1 amounted for IRP1, IRP4, and IRP5 to17, for IRP2 to 50, for IRP3 to 83, for IRP6 to 133 nM. IRP7 at a concentration of 10⁴ ng/ml replaced less than 50% of labeled hormone. The same high relative affinity of the peptide IRP4 (12% of activity of standard insulin and IGF-1) to both receptor types is revealed. The results of analysis in two types of hormonal test systems indicate the ability of the insulin-related peptides of the anodonta cerebropleural ganglion to interact with the vertebrate receptor of insulin and IGF-1. This gives grounds to suggest the presence of the metabolic and growth-stimulating properties in these peptides. For the first time, the IGF-1 activity is revealed in insulin-like molecules in invertebrates. Taking into account the chromatographically revealed differences of physicochemical characteristics of individual IRP as well as predominance of their IGF-1-binding properties, there is suggested another organization of the IRP receptor-binding domains in IPR of this mollusc species, as compared with mammalian insulins.     

Endophytic fungi in wild and cultivated grasses in Finland

We examined the occurrence of vertically via host seeds transmitted endophyte infections of 14 grass species in natural populations in Finland and totally 97 agricultural cultivars of 13 grass species. Although endophyte infections were widespread in native grass species, overall endophyte occurrence and frequencies were lower than published reports have suggested. In natural populations, 10 out of 14 grass species examined harbor fungal endophytes in their seeds. The highest species-specific mean incidences of endophyte infected plants in infected populations were found in Agrostis capillaris. Festuca arundinacea. F. ovina. F. Pratensis. F. rubra and Phleum pratense (67%, 98%, 29%., 42%. 32% and 33%, respectively). Mean incidences were < 20% in Dactylis glomerata. Deschampsia flexuosa. D. cespitosa and Elymus repens. and no infections were detected in Calamagrostis lapponica. C. epigejos. Alopecurus pratensis and Phalaris arundinacea. However, we detected a very high variation in infection incidences among natural populations and a large proportion of populations was, indeed, endophyte-free. This supports the ideas that 1) endophytic fungi provide selective advantage of infected grasses to their uninfected eonspecifics in some habitats, and/or 2) fungi are occasionally transmitted horizontally by spores. In grass cultivars, endophyte infected seeds were detected only in F. Pratensis and Lolium perenne. and endophyte frequencies were either very high or very low. Cultivars of 11 other grass species were endophyte-free.